International Journal of Molecular Sciences

Editorial

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11 pages, 219 KiB

Open AccessEditorial

Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms

by Susanne Grässel and Attila Aszodi

Int. J. Mol. Sci. 2019, 20(24), 6156; https://doi.org/10.3390/ijms20246156 - 6 Dec 2019

Cited by 21 | Viewed by 4140

Abstract

Osteoarthritis (OA) is a leading cause of disability and source of societal cost in older adults [...] Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

Research

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16 pages, 2060 KiB

Open AccessArticle

Vascular Adhesion Protein-1 (VAP-1) as Predictor of Radiographic Severity in Symptomatic Knee Osteoarthritis in the New York University Cohort

by Eirini Bournazou, Jonathan Samuels, Hua Zhou, Svetlana Krasnokutsky, Jyoti Patel, Tianzhen Han, Jenny Bencardino, Leon Rybak, Steven B. Abramson, Uwe Junker, Karen S. Brown and Mukundan Attur

Int. J. Mol. Sci. 2019, 20(11), 2642; https://doi.org/10.3390/ijms20112642 - 29 May 2019

Cited by 14 | Viewed by 3910

Abstract

Background: To investigate the expression of vascular adhesion protein-1 (VAP-1) in joint tissues and serum in symptomatic knee osteoarthritis (SKOA) patients and examine whether VAP-1 levels predict increased risk of disease severity in a cross-sectional study. Methods: Baseline VAP-1 expression and soluble VAP-1 [...] Read more.

Background: To investigate the expression of vascular adhesion protein-1 (VAP-1) in joint tissues and serum in symptomatic knee osteoarthritis (SKOA) patients and examine whether VAP-1 levels predict increased risk of disease severity in a cross-sectional study. Methods: Baseline VAP-1 expression and soluble VAP-1 (sVAP-1) levels were assessed in the synovium synovial fluid and in the serum in cohorts of patients with tibiofemoral medial knee OA and healthy subjects. Standardized fixed-flexion poster anterior knee radiographs scored for Kellgren–Lawrence (KL) grade (0–4) and medial joint space width (JSW). KL1/2 vs. KL3/4 scores defined early and advanced radiographic severity, respectively. Biochemical markers assessed in serum or synovial fluids (SF) comprised sVAP-1, interleukin 1 receptor antagonist (IL-1Ra), interleukin 6 (IL-6), soluble receptor for advanced glycation end-products (sRAGE), C-C motif chemokine ligand 2 (CCL2), C-C motif chemokine ligand 4 (CCL4), cluster of differentiation 163 (CD163), high sensitivity C-reactive protein (hsCRP), and matrix metalloproteinases (MMPs)-1,-3,-9. Associations between biomarkers and radiographic severity KL1/2 vs. KL3/4 (logistic regression controlling for covariates) and pain (Spearman correlation) were evaluated. Results: Elevated levels of sVAP-1 observed in OA synovial fluid and VAP-1 expression in synovium based on immunohistochemical, microarray, and real-time quantitative polymerase chain reaction (qRT-PCR) analyses. However, serum sVAP-1 levels in OA patients were lower than in controls and inversely correlated with pain and inflammation markers (hsCRP and soluble RAGE). Soluble VAP-1 levels in serum were also lower in radiographically advanced (KL3/4) compared with early KL1/2 knee SKOA patients. Conclusion: Local (synovial fluid) semicarbazide-sensitive amine oxidase (SSAO)/sVAP-1 levels were elevated in OA and correlated with radiographic severity. However, systemic (serum) sVAP-1 levels were lower in SKOA patients than normal and inversely correlated with pain and inflammation markers. Serum sVAP-1 levels were higher in early (KL1/2) compared with advanced (KL3/4) SKOA patients. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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19 pages, 2928 KiB

Open AccessArticle

Bioreactor-Controlled Physoxia Regulates TGF-β Signaling to Alter Extracellular Matrix Synthesis by Human Chondrocytes

by Holger Jahr, Seval Gunes, Annika-Ricarda Kuhn, Sven Nebelung and Thomas Pufe

Int. J. Mol. Sci. 2019, 20(7), 1715; https://doi.org/10.3390/ijms20071715 - 6 Apr 2019

Cited by 22 | Viewed by 5732

Abstract

Culturing articular chondrocytes under physiological oxygen tension exerts positive effects on their extracellular matrix synthesis. The underlying molecular mechanisms which enhance the chondrocytic phenotype are, however, still insufficiently elucidated. The TGF-β superfamily of growth factors, and the prototypic TGF-β isoforms in particular, are [...] Read more.

Culturing articular chondrocytes under physiological oxygen tension exerts positive effects on their extracellular matrix synthesis. The underlying molecular mechanisms which enhance the chondrocytic phenotype are, however, still insufficiently elucidated. The TGF-β superfamily of growth factors, and the prototypic TGF-β isoforms in particular, are crucial in maintaining matrix homeostasis of these cells. We employed a feedback-controlled table-top bioreactor to investigate the role of TGF-β in microtissues of human chondrocytes over a wider range of physiological oxygen tensions (i.e., physoxia). We compared 1%, 2.5%, and 5% of partial oxygen pressure (pO₂) to the ‘normoxic’ 20%. We confirmed physoxic conditions through the induction of marker genes (PHD3, VEGF) and oxygen tension-dependent chondrocytic markers (SOX9, COL2A1). We identified 2.5% pO₂ as an oxygen tension optimally improving chondrocytic marker expression (ACAN, COL2A1), while suppressing de-differentiation markers (COL1A1, COL3A1). Expression of TGF-β isoform 2 (TGFB2) was, relatively, most responsive to 2.5% pO₂, while all three isoforms were induced by physoxia. We found TGF-β receptors ALK1 and ALK5 to be regulated by oxygen tension on the mRNA and protein level. In addition, expression of type III co-receptors betaglycan and endoglin appeared to be regulated by oxygen tension as well. R-Smad signaling confirmed that physoxia divergently regulated phosphorylation of Smad1/5/8 and Smad2/3. Pharmacological inhibition of canonical ALK5-mediated signaling abrogated physoxia-induced COL2A1 and PAI-1 expression. Physoxia altered expression of hypertrophy markers and that of matrix metalloproteases and their activity, as well as expression ratios of specific proteins (Sp)/Krüppel-like transcription factor family members SP1 and SP3, proving a molecular concept of ECM marker regulation. Keeping oxygen levels tightly balanced within a physiological range is important for optimal chondrocytic marker expression. Our study provides novel insights into transcriptional regulations in chondrocytes under physoxic in vitro conditions and may contribute to improving future cell-based articular cartilage repair strategies. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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13 pages, 1312 KiB

Open AccessArticle

Association of Human FOS Promoter Variants with the Occurrence of Knee-Osteoarthritis in a Case Control Association Study

by René Huber, Holger Kirsten, Annu Näkki, Dirk Pohlers, Hansjörg Thude, Thorsten Eidner, Matthias Heinig, Korbinian Brand, Peter Ahnert and Raimund W. Kinne

Int. J. Mol. Sci. 2019, 20(6), 1382; https://doi.org/10.3390/ijms20061382 - 19 Mar 2019

Cited by 12 | Viewed by 3883

Abstract

Our aim was to analyse (i) the presence of single nucleotide polymorphisms (SNPs) in the JUN and FOS core promoters in patients with rheumatoid arthritis (RA), knee-osteoarthritis (OA), and normal controls (NC); (ii) their functional influence on JUN/FOS transcription levels; and [...] Read more.

Our aim was to analyse (i) the presence of single nucleotide polymorphisms (SNPs) in the JUN and FOS core promoters in patients with rheumatoid arthritis (RA), knee-osteoarthritis (OA), and normal controls (NC); (ii) their functional influence on JUN/FOS transcription levels; and (iii) their associations with the occurrence of RA or knee-OA. JUN and FOS promoter SNPs were identified in an initial screening population using the Non-Isotopic RNase Cleavage Assay (NIRCA); their functional influence was analysed using reporter gene assays. Genotyping was done in RA (n = 298), knee-OA (n = 277), and NC (n = 484) samples. For replication, significant associations were validated in a Finnish cohort (OA: n = 72, NC: n = 548). Initially, two SNPs were detected in the JUN promoter and two additional SNPs in the FOS promoter in perfect linkage disequilibrium (LD). JUN promoter SNP rs4647009 caused significant downregulation of reporter gene expression, whereas reporter gene expression was significantly upregulated in the presence of the FOS promoter SNPs. The homozygous genotype of FOS promoter SNPs showed an association with the susceptibility for knee-OA (odds ratio (OR) 2.12, 95% confidence interval (CI) 1.2–3.7, p = 0.0086). This association was successfully replicated in the Finnish Health 2000 study cohort (allelic OR 1.72, 95% CI 1.2–2.5, p = 0.006). FOS Promoter variants may represent relevant susceptibility markers for knee-OA. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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16 pages, 5691 KiB

Open AccessArticle

Role of Norepinephrine in IL-1β-Induced Chondrocyte Dedifferentiation under Physioxia

by Saskia Speichert, Natalie Molotkov, Karima El Bagdadi, Andrea Meurer, Frank Zaucke and Zsuzsa Jenei-Lanzl

Int. J. Mol. Sci. 2019, 20(5), 1212; https://doi.org/10.3390/ijms20051212 - 11 Mar 2019

Cited by 23 | Viewed by 5631

Abstract

As part of the pathogenesis of osteoarthritis (OA), chondrocytes lose their phenotype and become hypertrophic, or dedifferentiate, mainly driven by interleukin-1β (IL-1β). The contribution of other factors to the dedifferentiation process is not completely understood. Recent studies suggested a dose-dependent role for the [...] Read more.

As part of the pathogenesis of osteoarthritis (OA), chondrocytes lose their phenotype and become hypertrophic, or dedifferentiate, mainly driven by interleukin-1β (IL-1β). The contribution of other factors to the dedifferentiation process is not completely understood. Recent studies suggested a dose-dependent role for the sympathetic neurotransmitter norepinephrine (NE) in OA chondrocyte metabolism. Therefore, the aim of this study was to analyze the contribution of NE (10⁻⁸ M, 10⁻⁶ M) to human articular OA chondrocyte dedifferentiation in the absence or presence of IL-1β (0.5 ng/mL). Here, we demonstrate that OA chondrocytes express α2A-, α2C- and β2-adrenoceptors (AR) and show the characteristic shift towards a fibroblast-like shape at day 7 in physioxic monolayer culture. NE alone did not affect morphology but, in combination with IL-1β, markedly accelerated this shift. Moderate glycosaminoglycan (GAG) staining was observed in untreated and NE-treated cells, while IL-1β strongly decreased GAG deposition. IL-1β alone or in combination with NE decreased SOX9, type II collagen, COMP, and aggrecan, and induced MMP13 and ADAMTS4 gene expression, indicating an accelerated dedifferentiation. NE alone did not influence gene expression and did not modulate IL-1β-mediated effects. In conclusion, these results indicate that low-grade inflammation exerts a dominant effect on chondrocyte dedifferentiation and should be targeted early in OA therapy. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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19 pages, 9000 KiB

Open AccessArticle

Aggrecan Hypomorphism Compromises Articular Cartilage Biomechanical Properties and Is Associated with Increased Incidence of Spontaneous Osteoarthritis

by Paolo Alberton, Hans Christian Dugonitsch, Bastian Hartmann, Ping Li, Zsuzsanna Farkas, Maximilian Michael Saller, Hauke Clausen-Schaumann and Attila Aszodi

Int. J. Mol. Sci. 2019, 20(5), 1008; https://doi.org/10.3390/ijms20051008 - 26 Feb 2019

Cited by 37 | Viewed by 5592

Abstract

The gene encoding the proteoglycan aggrecan (Agc1) is abundantly expressed in cartilage during development and adulthood, and the loss or diminished deposition of the protein results in a wide range of skeletal malformations. Furthermore, aggrecan degradation is a hallmark of cartilage [...] Read more.

The gene encoding the proteoglycan aggrecan (Agc1) is abundantly expressed in cartilage during development and adulthood, and the loss or diminished deposition of the protein results in a wide range of skeletal malformations. Furthermore, aggrecan degradation is a hallmark of cartilage degeneration occurring in osteoarthritis. In the present study, we investigated the consequences of a partial loss of aggrecan in the postnatal skeleton and in the articular cartilage of adult mice. We took advantage of the previously described Agc1^{tm(IRES-CreERT2)} mouse line, which allows for conditional and timely-regulated deletion of floxed, cartilage-expressed genes. As previously reported, the introduction of the CreER^T2 cassette in the 3’UTR causes a disruption of the normal expression of Agc1 resulting in a hypomorphic deposition of the protein. In homozygous mice, we observed a dwarf phenotype, which persisted throughout adulthood supporting the evidence that reduced aggrecan amount impairs skeletal growth. Homozygous mice exhibited reduced proteoglycan staining of the articular cartilage at 6 and 12 months of age, increased stiffening of the extracellular matrix at six months, and developed severe cartilage erosion by 12 months. The osteoarthritis in the hypomorph mice was not accompanied by increased expression of catabolic enzymes and matrix degradation neoepitopes. These findings suggest that the degeneration found in homozygous mice is likely due to the compromised mechanical properties of the cartilage tissue upon aggrecan reduction. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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15 pages, 1624 KiB

Open AccessArticle

Increased TGF-β and BMP Levels and Improved Chondrocyte-Specific Marker Expression In Vitro under Cartilage-Specific Physiological Osmolarity

by Ufuk Tan Timur, Marjolein Caron, Guus van den Akker, Anna van der Windt, Jenny Visser, Lodewijk van Rhijn, Harrie Weinans, Tim Welting, Pieter Emans and Holger Jahr

Int. J. Mol. Sci. 2019, 20(4), 795; https://doi.org/10.3390/ijms20040795 - 13 Feb 2019

Cited by 22 | Viewed by 4302

Abstract

During standard expansion culture (i.e., plasma osmolarity, 280 mOsm) human articular chondrocytes dedifferentiate, making them inappropriate for autologous chondrocyte implantation to treat cartilage defects. Increasing the osmolarity of culture media to physiological osmolarity levels of cartilage (i.e., 380 mOsm), increases collagen type II [...] Read more.

During standard expansion culture (i.e., plasma osmolarity, 280 mOsm) human articular chondrocytes dedifferentiate, making them inappropriate for autologous chondrocyte implantation to treat cartilage defects. Increasing the osmolarity of culture media to physiological osmolarity levels of cartilage (i.e., 380 mOsm), increases collagen type II (COL2A1) expression of human articular chondrocytes in vitro, but the underlying molecular mechanism is not fully understood. We hypothesized that TGF-β superfamily signaling may drive expression of COL2A1 under physiological osmolarity culture conditions. Human articular chondrocytes were cultured in cytokine-free medium of 280 or 380 mOsm with or without siRNA mediated TGF-β2 knockdown (RNAi). Expression of TGF-β isoforms, and collagen type II was evaluated by RT-qPCR and immunoblotting. TGF-β2 protein secretion was evaluated using ELISA and TGF-β bioactivity was determined using an established reporter assay. Involvement of BMP signaling was investigated by culturing human articular chondrocytes in the presence or absence of BMP inhibitor dorsomorphin and BMP bioactivity was determined using an established reporter assay. Physiological cartilage osmolarity (i.e., physosmolarity) most prominently increased TGF-β2 mRNA expression and protein secretion as well as TGF-β bioactivity. Upon TGF-β2 isoform-specific knockdown, gene expression of chondrocyte marker COL2A1 was induced. TGF-β2 RNAi under physosmolarity enhanced TGF-β bioactivity. BMP bioactivity increased upon physosmotic treatment, but was not related to TGF-β2 RNAi. In contrast, dorsomorphin inhibited COL2A1 mRNA expression in human articular chondrocytes independent of the osmotic condition. Our data suggest a role for TGF-β superfamily member signaling in physosmolarity-induced mRNA expression of collagen type II. As physosmotic conditions favor the expression of COL2A1 independent of our manipulations, contribution of other metabolic, post-transcriptional or epigenetic factors cannot be excluded in the underlying complex and interdependent regulation of marker gene expression. Dissecting these molecular mechanisms holds potential to further improve future cell-based chondral repair strategies. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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13 pages, 1952 KiB

Open AccessArticle

Developmental Transformation and Reduction of Connective Cavities within the Subchondral Bone

by Shahed Taheri, Thomas Winkler, Lia Sabrina Schenk, Carl Neuerburg, Sebastian Felix Baumbach, Jozef Zustin, Wolfgang Lehmann and Arndt F. Schilling

Int. J. Mol. Sci. 2019, 20(3), 770; https://doi.org/10.3390/ijms20030770 - 12 Feb 2019

Cited by 14 | Viewed by 4087

Abstract

It is widely accepted that the subchondral bone (SCB) plays a crucial role in the physiopathology of osteoarthritis (OA), although its contribution is still debated. Much of the pre-clinical research on the role of SCB is concentrated on comparative evaluations of healthy vs. [...] Read more.

It is widely accepted that the subchondral bone (SCB) plays a crucial role in the physiopathology of osteoarthritis (OA), although its contribution is still debated. Much of the pre-clinical research on the role of SCB is concentrated on comparative evaluations of healthy vs. early OA or early OA vs. advanced OA cases, while neglecting how pure maturation could change the SCB’s microstructure. To assess the transformations of the healthy SCB from young age to early adulthood, we examined the microstructure and material composition of the medial condyle of the femur in calves (three months) and cattle (18 months) for the calcified cartilage (CC) and the subchondral bone plate (SCBP). The entire subchondral zone (SCZ) was significantly thicker in cattle compared to calves, although the proportion of the CC and SCBP thicknesses were relatively constant. The trabecular number (Tb.N.) and the connectivity density (Conn.D) were significantly higher in the deeper region of the SCZ, while the bone volume fraction (BV/TV), and the degree of anisotropy (DA) were more affected by age rather than the region. The mineralization increased within the first 250 µm of the SCZ irrespective of sample type, and became stable thereafter. Cattle exhibited higher mineralization than calves at all depths, with a mean Ca/P ratio of 1.59 and 1.64 for calves and cattle, respectively. Collectively, these results indicate that the SCZ is highly dynamic at early age, and CC is the most dynamic layer of the SCZ. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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19 pages, 2838 KiB

Open AccessArticle

IL-10 Could Play a Role in the Interrelation between Diabetes Mellitus and Osteoarthritis

by Sandeep Silawal, Maximilian Willauschus, Gundula Schulze-Tanzil, Clemens Gögele, Markus Geßlein and Silke Schwarz

Int. J. Mol. Sci. 2019, 20(3), 768; https://doi.org/10.3390/ijms20030768 - 12 Feb 2019

Cited by 15 | Viewed by 5582

Abstract

The association between osteoarthritis (OA), obesity and metabolic syndrome suggests an interrelation between OA and diabetes mellitus (DM). Little is known about the role of anti-inflammatory cytokine interleukin (IL)-10 in the interrelation between OA and DM. Hence, the effects of IL-10 under hyperglycemia [...] Read more.

The association between osteoarthritis (OA), obesity and metabolic syndrome suggests an interrelation between OA and diabetes mellitus (DM). Little is known about the role of anti-inflammatory cytokine interleukin (IL)-10 in the interrelation between OA and DM. Hence, the effects of IL-10 under hyperglycemia (HG) and hyperinsulinemia (HI) in human articular chondrocytes (hAC) and chondrosarcoma cell line Okayama University Medical School (OUMS)-27 were examined. HAC and OUMS-27, cultured in normoglycemic (NG) and HG conditions were stimulated with insulin and/or IL-10. Cell survival, metabolic activity, proliferation and extracellular matrix (ECM) synthesis were immunocytochemically examined. No significant differences in vitality of hAC neither in pure NG (NG_w/o) nor HG (HG_w/o) conditions were found. Applying HI and/or IL-10 in both conditions reduced significantly the vitality of hAC but not of OUMS-27. HG impaired significantly hAC metabolism. When combined with HI + IL-10 or IL-10 alone it decreased also significantly hAC proliferation compared to NG_w/o. In OUMS-27 it induced only a trend of impaired proliferation compared to NG_w/o. hAC but not OUMS-27 reduced significantly their collagen type (col) I, SOX9 and proteoglycan (PG) synthesis in HG combined with HI +/− IL-10 compared to NG_w/o. IL-10 could not moderate HI and HG effects. In contrast to hAC OUMS-27 showed limited sensitivity as DM model. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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17 pages, 3058 KiB

Open AccessArticle

Treatment of Focal Cartilage Defects in Minipigs with Zonal Chondrocyte/Mesenchymal Progenitor Cell Constructs

by Friederike Bothe, Anne-Kathrin Deubel, Eliane Hesse, Benedict Lotz, Jürgen Groll, Carsten Werner, Wiltrud Richter and Sebastien Hagmann

Int. J. Mol. Sci. 2019, 20(3), 653; https://doi.org/10.3390/ijms20030653 - 2 Feb 2019

Cited by 20 | Viewed by 5011

Abstract

Despite advances in cartilage repair strategies, treatment of focal chondral lesions remains an important challenge to prevent osteoarthritis. Articular cartilage is organized into several layers and lack of zonal organization of current grafts is held responsible for insufficient biomechanical and biochemical quality of [...] Read more.

Despite advances in cartilage repair strategies, treatment of focal chondral lesions remains an important challenge to prevent osteoarthritis. Articular cartilage is organized into several layers and lack of zonal organization of current grafts is held responsible for insufficient biomechanical and biochemical quality of repair-tissue. The aim was to develop a zonal approach for cartilage regeneration to determine whether the outcome can be improved compared to a non-zonal strategy. Hydrogel-filled polycaprolactone (PCL)-constructs with a chondrocyte-seeded upper-layer deemed to induce hyaline cartilage and a mesenchymal stromal cell (MSC)-containing bottom-layer deemed to induce calcified cartilage were compared to chondrocyte-based non-zonal grafts in a minipig model. Grafts showed comparable hardness at implantation and did not cause visible signs of inflammation. After 6 months, X-ray microtomography (µCT)-analysis revealed significant bone-loss in both treatment groups compared to empty controls. PCL-enforcement and some hydrogel-remnants were retained in all defects, but most implants were pressed into the subchondral bone. Despite important heterogeneities, both treatments reached a significantly lower modified O’Driscoll-score compared to empty controls. Thus, PCL may have induced bone-erosion during joint loading and misplacement of grafts in vivo precluding adequate permanent orientation of zones compared to surrounding native cartilage. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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12 pages, 1055 KiB

Open AccessArticle

Impact of Mechanical Load on the Expression Profile of Synovial Fibroblasts from Patients with and without Osteoarthritis

by Agnes Schröder, Ute Nazet, Dominique Muschter, Susanne Grässel, Peter Proff and Christian Kirschneck

Int. J. Mol. Sci. 2019, 20(3), 585; https://doi.org/10.3390/ijms20030585 - 30 Jan 2019

Cited by 37 | Viewed by 5284

Abstract

Osteoarthritis (OA) affects the integrity of the entire joint including the synovium. The most abundant cells in the synovium are fibroblasts (SF). Excessive mechanical loading might contribute to OA pathogenesis. Here, we investigate the effects of mechanical loading on SF derived from non-OA [...] Read more.

Osteoarthritis (OA) affects the integrity of the entire joint including the synovium. The most abundant cells in the synovium are fibroblasts (SF). Excessive mechanical loading might contribute to OA pathogenesis. Here, we investigate the effects of mechanical loading on SF derived from non-OA (N-SF) and OA patients (OA-SF). We treated N-SF and OA-SF with or without mechanical loading for 48h after 24h of preincubation. Then we assessed gene and protein expression of proinflammatory factors (TNFα, COX-2, PG-E2, IL-6), extracellular matrix (ECM) components (COL1, FN1) and glycosaminoglycans (GAGs) via RT-qPCR, ELISA, DMMB assay and HPLC. Mechanical loading significantly increased TNFα and PG-E2 secretion by N-SF and OA-SF, whereas in OA-SF IL-6 secretion was reduced. COL1 and FN1 secretion were downregulated in N-SF during loading. OA-SF secreted less COL1 compared to N-SF under control conditions. In contrast, OA-SF in general expressed more FN1. GAG synthesis was upregulated in N-SF, but not in OA-SF during loading with OA-SF displaying a higher charge density than N-SF. Mechanical loading enhanced proinflammatory factor expression and GAG synthesis and decreased secretion of ECM components in N-SFs, indicating a contributing role of SF to OA development. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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21 pages, 13574 KiB

Open AccessArticle

Catabolism of Fibromodulin in Developmental Rudiment and Pathologic Articular Cartilage Demonstrates Novel Roles for MMP-13 and ADAMTS-4 in C-terminal Processing of SLRPs

by Cindy C Shu, Carl R Flannery, Christopher B Little and James Melrose

Int. J. Mol. Sci. 2019, 20(3), 579; https://doi.org/10.3390/ijms20030579 - 29 Jan 2019

Cited by 24 | Viewed by 4668

Abstract

Background: Cartilage regeneration requires a balance of anabolic and catabolic processes. Aim: To examine the susceptibility of fibromodulin (FMOD) and lumican (LUM) to degradation by MMP-13, ADAMTS-4 and ADAMTS-5, the three major degradative proteinases in articular cartilage, in cartilage development and in osteoarthritis [...] Read more.

Background: Cartilage regeneration requires a balance of anabolic and catabolic processes. Aim: To examine the susceptibility of fibromodulin (FMOD) and lumican (LUM) to degradation by MMP-13, ADAMTS-4 and ADAMTS-5, the three major degradative proteinases in articular cartilage, in cartilage development and in osteoarthritis (OA). Methods: Immunolocalization of FMOD and LUM in fetal foot and adult knee cartilages using an FMOD matrix metalloprotease (MMP)-13 neoepitope antibody (TsYG11) and C-terminal anti-FMOD (PR184) and anti-LUM (PR353) antibodies. The in vitro digestion of knee cartilage with MMP-13, A Disintegrin and Metalloprotease with Thrompospondin motifs (ADAMTS)-4 and ADAMTS-5, to assess whether FMOD and LUM fragments observed in Western blots of total knee replacement specimens could be generated. Normal ovine articular cartilage explants were cultured with interleukin (IL)-1 and Oncostatin-M (OSM) ± PGE3162689, a broad spectrum MMP inhibitor, to assess FMOD, LUM and collagen degradation. Results and Discussion: FMOD and LUM were immunolocalized in metatarsal and phalangeal fetal rudiment cartilages and growth plates. Antibody TsYG11 localized MMP-13-cleaved FMOD in the hypertrophic chondrocytes of the metatarsal growth plates. FMOD was more prominently localized in the superficial cartilage of normal and fibrillated zones in OA cartilage. TsYG11-positive FMOD was located deep in the cartilage samples. Ab TsYG11 identified FMOD fragmentation in Western blots of normal and fibrillated cartilage extracts and total knee replacement cartilage. The C-terminal anti-FMOD, Ab PR-184, failed to identify FMOD fragmentation due to C-terminal processing. The C-terminal LUM, Ab PR-353, identified three LUM fragments in OA cartilages. In vitro digestion of human knee cartilage with MMP-13, ADAMTS-4 and ADAMTS-5 generated FMOD fragments of 54, 45 and 32 kDa similar to in blots of OA cartilage; LUM was less susceptible to fragmentation. Ab PR-353 detected N-terminally processed LUM fragments of 39, 38 and 22 kDa in 65–80-year-old OA knee replacement cartilage. FMOD and LUM were differentially processed in MMP-13, ADAMTS-4 and ADAMTS-5 digestions. FMOD was susceptible to degradation by MMP-13, ADAMTS-4 and to a lesser extent by ADAMTS-5; however, LUM was not. MMP-13-cleaved FMOD in metatarsal and phalangeal fetal rudiment and growth plate cartilages suggested roles in skeletogenesis and OA pathogenesis. Explant cultures of ovine cartilage stimulated with IL-1/OSM ± PGE3162689 displayed GAG loss on day 5 due to ADAMTS activity. However, by day 12, the activation of proMMPs occurred as well as the degradation of FMOD and collagen. These changes were inhibited by PGE3162689, partly explaining the FMOD fragments seen in OA and the potential therapeutic utility of PGE3162689. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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24 pages, 3834 KiB

Open AccessArticle

Sensory Neuropeptides and their Receptors Participate in Mechano-Regulation of Murine Macrophages

by Dominique Muschter, Anna-Sophie Beiderbeck, Tanja Späth, Christian Kirschneck, Agnes Schröder and Susanne Grässel

Int. J. Mol. Sci. 2019, 20(3), 503; https://doi.org/10.3390/ijms20030503 - 24 Jan 2019

Cited by 15 | Viewed by 5197

Abstract

This study aimed to analyze if the sensory neuropeptide SP (SP) and the neurokinin receptor 1 (NK1R) are involved in macrophage mechano-transduction, similar to chondrocytes, and if alpha-calcitonin gene-related peptide (αCGRP) and the CGRP receptor (CRLR/Ramp1) show comparable activity. Murine RAW264.7 macrophages were [...] Read more.

This study aimed to analyze if the sensory neuropeptide SP (SP) and the neurokinin receptor 1 (NK1R) are involved in macrophage mechano-transduction, similar to chondrocytes, and if alpha-calcitonin gene-related peptide (αCGRP) and the CGRP receptor (CRLR/Ramp1) show comparable activity. Murine RAW264.7 macrophages were subjected to a cyclic stretch for 1–3 days and 4 h/day. Loading and neuropeptide effects were analyzed for gene and protein expression of neuropeptides and their receptors, adhesion, apoptosis, proliferation and ROS activity. Murine bone marrow-derived macrophages (BMM) were isolated after surgical osteoarthritis (OA) induction and proliferation, apoptosis and osteoclastogenesis were analyzed in response to loading. Loading induced NK1R and CRLR/Ramp1 gene expression and altered protein expression in RAW264.7 macrophages. SP protein and mRNA level decreased after loading whereas αCGRP mRNA expression was stabilized. SP reduced adhesion in loaded RAW264.7 macrophages and both neuropeptides initially increased the ROS activity followed by a time-dependent suppression. OA induction sensitized BMM to caspase 3/7 mediated apoptosis after loading. Both sensory neuropeptides, SP and αCGRP, and their receptors are involved in murine macrophage mechano-transduction affecting neuropeptide impact on adhesion and ROS activity. OA induction altered BMM apoptosis in response to loading indicate that OA-associated biomechanical alterations might affect the macrophage population. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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26 pages, 8501 KiB

Open AccessArticle

A Retrospective Analysis of the Cartilage Kunitz Protease Inhibitory Proteins Identifies These as Members of the Inter-α-Trypsin Inhibitor Superfamily with Potential Roles in the Protection of the Articulatory Surface

by Susan M. Smith and James Melrose

Int. J. Mol. Sci. 2019, 20(3), 497; https://doi.org/10.3390/ijms20030497 - 24 Jan 2019

Cited by 7 | Viewed by 6006

Abstract

Aim: The aim of this study was to assess if the ovine articular cartilage serine proteinase inhibitors (SPIs) were related to the Kunitz inter-α-trypsin inhibitor (ITI) family. Methods: Ovine articular cartilage was finely diced and extracted in 6 M urea and SPIs isolated [...] Read more.

Aim: The aim of this study was to assess if the ovine articular cartilage serine proteinase inhibitors (SPIs) were related to the Kunitz inter-α-trypsin inhibitor (ITI) family. Methods: Ovine articular cartilage was finely diced and extracted in 6 M urea and SPIs isolated by sequential anion exchange, HA affinity and Sephadex G100 gel permeation chromatography. Selected samples were also subjected to chymotrypsin and concanavalin-A affinity chromatography. Eluant fractions from these isolation steps were monitored for protein and trypsin inhibitory activity. Inhibitory fractions were assessed by affinity blotting using biotinylated trypsin to detect SPIs and by Western blotting using antibodies to α1-microglobulin, bikunin, TSG-6 and 2-B-6 (+) CS epitope generated by chondroitinase-ABC digestion. Results: 2-B-6 (+) positive 250, 220,120, 58 and 36 kDa SPIs were detected. The 58 kDa SPI contained α1-microglobulin, bikunin and chondroitin-4-sulfate stub epitope consistent with an identity of α1-microglobulin-bikunin (AMBP) precursor and was also isolated by concanavalin-A lectin affinity chromatography indicating it had N-glycosylation. Kunitz protease inhibitor (KPI) species of 36, 26, 12 and 6 kDa were autolytically generated by prolonged storage of the 120 and 58 kDa SPIs; chymotrypsin affinity chromatography generated the 6 kDa SPI. KPI domain 1 and 2 SPIs were separated by concanavalin lectin affinity chromatography, domain 1 displayed affinity for this lectin indicating it had N-glycosylation. KPI 1 and 2 displayed potent inhibitory activity against trypsin, chymotrypsin, kallikrein, leucocyte elastase and cathepsin G. Localisation of versican, lubricin and hyaluronan (HA) in the surface regions of articular cartilage represented probable binding sites for the ITI serine proteinase inhibitors (SPIs) which may preserve articulatory properties and joint function. Discussion/Conclusions: The Kunitz SPI proteins synthesised by articular chondrocytes are members of the ITI superfamily. By analogy with other tissues in which these proteins occur we deduce that the cartilage Kunitz SPIs may be multifunctional proteins. Binding of the cartilage Kunitz SPIs to HA may protect this polymer from depolymerisation by free radical damage and may also protect other components in the cartilage surface from proteolytic degradation preserving joint function. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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17 pages, 3644 KiB

Open AccessArticle

The Expression of Thrombospondin-4 Correlates with Disease Severity in Osteoarthritic Knee Cartilage

by Kathrin Maly, Inna Schaible, Jana Riegger, Rolf E. Brenner, Andrea Meurer and Frank Zaucke

Int. J. Mol. Sci. 2019, 20(2), 447; https://doi.org/10.3390/ijms20020447 - 21 Jan 2019

Cited by 15 | Viewed by 5311

Abstract

Osteoarthritis (OA) is a progressive joint disease characterized by a continuous degradation of the cartilage extracellular matrix (ECM). The expression of the extracellular glycoprotein thrombospondin-4 (TSP-4) is known to be increased in injured tissues and involved in matrix remodeling, but its role in [...] Read more.

Osteoarthritis (OA) is a progressive joint disease characterized by a continuous degradation of the cartilage extracellular matrix (ECM). The expression of the extracellular glycoprotein thrombospondin-4 (TSP-4) is known to be increased in injured tissues and involved in matrix remodeling, but its role in articular cartilage and, in particular, in OA remains elusive. In the present study, we analyzed the expression and localization of TSP-4 in healthy and OA knee cartilage by reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and immunoblot. We found that TSP-4 protein expression is increased in OA and that expression levels correlate with OA severity. TSP-4 was not regulated at the transcriptional level but we detected changes in the anchorage of TSP-4 in the altered ECM using sequential protein extraction. We were also able to detect pentameric and fragmented TSP-4 in the serum of both healthy controls and OA patients. Here, the total protein amount was not significantly different but we identified specific degradation products that were more abundant in sera of OA patients. Future studies will reveal if these fragments have the potential to serve as OA-specific biomarkers. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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17 pages, 1433 KiB

Open AccessArticle

The Effect of Dexamethasone, Adrenergic and Cholinergic Receptor Agonists on Phospholipid Metabolism in Human Osteoarthritic Synoviocytes

by Katarzyna D. Sluzalska, Gerhard Liebisch, Bernd Ishaque, Gerd Schmitz, Markus Rickert and Juergen Steinmeyer

Int. J. Mol. Sci. 2019, 20(2), 342; https://doi.org/10.3390/ijms20020342 - 15 Jan 2019

Cited by 3 | Viewed by 3853

Abstract

Phospholipids (PLs) possess the unique ability to contribute to synovial joint lubrication. The aim of our study was to determine for the first time the effect of dexamethasone and some adrenergic and cholinergic agonists on the biosynthesis and release of PLs from human [...] Read more.

Phospholipids (PLs) possess the unique ability to contribute to synovial joint lubrication. The aim of our study was to determine for the first time the effect of dexamethasone and some adrenergic and cholinergic agonists on the biosynthesis and release of PLs from human fibroblast-like synoviocytes (FLS). Osteoarthritic human knee FLS were treated with dexamethasone, terbutaline, epinephrine, carbachol, and pilocarpine, or the glucocorticoid receptor antagonist RU 486. Simultaneously PL biosynthesis was determined through the incorporation of stable isotope-labeled precursors into PLs. Radioactive isotope-labeled precursors were used to radiolabel PLs for the subsequent quantification of their release into nutrient media. Lipids were extracted and quantified using electrospray ionization tandem mass spectrometry or liquid scintillation counting. Dexamethasone significantly decreased the biosynthesis of phosphatidylcholine, phosphatidylethanolamine (PE), PE-based plasmalogen, and sphingomyelin. The addition of RU 486 abolished these effects. A release of PLs from FLS into nutrient media was not recognized by any of the tested agents. None of the adrenergic or cholinergic receptor agonists modulated the PL biosynthesis. We demonstrate for the first time an inhibitory effect of dexamethasone on the PL biosynthesis of FLS from human knees. Moreover, our study indicates that the PL metabolism of synovial joints and lungs are differently regulated. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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16 pages, 38376 KiB

Open AccessArticle

Continuous Passive Motion Promotes and Maintains Chondrogenesis in Autologous Endothelial Progenitor Cell-Loaded Porous PLGA Scaffolds during Osteochondral Defect Repair in a Rabbit Model

by Hsueh-Chun Wang, Tzu-Hsiang Lin, Nai-Jen Chang, Horng-Chaung Hsu and Ming-Long Yeh

Int. J. Mol. Sci. 2019, 20(2), 259; https://doi.org/10.3390/ijms20020259 - 10 Jan 2019

Cited by 12 | Viewed by 4239

Abstract

Continuous passive motion (CPM) is widely used after total knee replacement. In this study, we investigated the effect of CPM combined with cell-based construct-transplantation in osteochondral tissue engineering. We created osteochondral defects (3 mm in diameter and 3 mm in depth) in the [...] Read more.

Continuous passive motion (CPM) is widely used after total knee replacement. In this study, we investigated the effect of CPM combined with cell-based construct-transplantation in osteochondral tissue engineering. We created osteochondral defects (3 mm in diameter and 3 mm in depth) in the medial femoral condyle of 36 knees and randomized them into three groups: ED (empty defect), EPC/PLGA (endothelial progenitor cells (EPCs) seeded in the poly lactic-co-glycolic acid (PLGA) scaffold), or EPC/PLGA/CPM (EPC/PLGA scaffold complemented with CPM starting one day after transplantation). We investigated the effects of CPM and the EPC/PLGA constructs on tissue restoration in weight-bearing sites by histological observation and micro-computed tomography (micro-CT) evaluation 4 and 12 weeks after implantation. After CPM, the EPC/PLGA construct exhibited early osteochondral regeneration and prevention of subchondral bone overgrowth and cartilage degeneration. CPM did not alter the microenvironment created by the construct; it up-regulated the expression of the extracellular matrix components (glycosaminoglycan and collagen), down-regulated bone formation, and induced the biosynthesis of lubricin, which appeared in the EPC/PLGA/CPM group after 12 weeks. CPM can provide promoting signals during osteochondral tissue engineering and achieve a synergistic effect when combined with EPC/PLGA transplantation, so it should be considered a non-invasive treatment to be adopted in clinical practices. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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22 pages, 2534 KiB

Open AccessArticle

Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) Reduces Oxidative and Mechanical Stress-Evoked Matrix Degradation in Chondrifying Cell Cultures

by Eszter Szentléleky, Vince Szegeczki, Edina Karanyicz, Tibor Hajdú, Andrea Tamás, Gábor Tóth, Róza Zákány, Dóra Reglődi and Tamás Juhász

Int. J. Mol. Sci. 2019, 20(1), 168; https://doi.org/10.3390/ijms20010168 - 4 Jan 2019

Cited by 27 | Viewed by 4431

Abstract

Pituitary adenylate cyclase activating polypeptide (PACAP) is an endogenous neuropeptide also secreted by non-neural cells, including chondrocytes. PACAP signaling is involved in the regulation of chondrogenesis, but little is known about its connection to matrix turnover during cartilage formation and under cellular stress [...] Read more.

Pituitary adenylate cyclase activating polypeptide (PACAP) is an endogenous neuropeptide also secreted by non-neural cells, including chondrocytes. PACAP signaling is involved in the regulation of chondrogenesis, but little is known about its connection to matrix turnover during cartilage formation and under cellular stress in developing cartilage. We found that the expression and activity of hyaluronidases (Hyals), matrix metalloproteinases (MMP), and aggrecanase were permanent during the course of chondrogenesis in primary chicken micromass cell cultures, although protein levels changed daily, along with moderate and relatively constant enzymatic activity. Next, we investigated whether PACAP influences matrix destructing enzyme activity during oxidative and mechanical stress in chondrogenic cells. Exogenous PACAP lowered Hyals and aggrecanase expression and activity during cellular stress. Expression and activation of the majority of cartilage matrix specific MMPs such as MMP1, MMP7, MMP8, and MMP13, were also decreased by PACAP addition upon oxidative and mechanical stress, while the activity of MMP9 seemed not to be influenced by the neuropeptide. These results suggest that application of PACAP can help to preserve the integrity of the newly synthetized cartilage matrix via signaling mechanisms, which ultimately inhibit the activity of matrix destroying enzymes under cellular stress. It implies the prospect that application of PACAP can ameliorate articular cartilage destruction in joint diseases. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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22 pages, 3551 KiB

Open AccessArticle

A Complex Relationship between Visfatin and Resistin and microRNA: An In Vitro Study on Human Chondrocyte Cultures

by Sara Cheleschi, Nicola Giordano, Nila Volpi, Sara Tenti, Ines Gallo, Martina Di Meglio, Stefano Giannotti and Antonella Fioravanti

Int. J. Mol. Sci. 2018, 19(12), 3909; https://doi.org/10.3390/ijms19123909 - 6 Dec 2018

Cited by 31 | Viewed by 4419

Abstract

Growing evidence indicates the important role of adipokines and microRNA (miRNA) in osteoarthritis (OA) pathogenesis. The purpose of the present study was to investigate the effect of visfatin and resistin on some miRNA (34a, 140, 146a, 155, 181a, let-7e), metalloproteinases (MMPs), and collagen [...] Read more.

Growing evidence indicates the important role of adipokines and microRNA (miRNA) in osteoarthritis (OA) pathogenesis. The purpose of the present study was to investigate the effect of visfatin and resistin on some miRNA (34a, 140, 146a, 155, 181a, let-7e), metalloproteinases (MMPs), and collagen type II alpha 1 chain (Col2a1) in human OA chondrocytes and in the T/C-28a2 cell line. The implication of nuclear factor (NF)-κB in response to adipokines was also assessed. Chondrocytes were stimulated with visfatin (5 or 10 μg/mL) and resistin (50 or 100 ng/mL) with or without NF-κB inhibitor (BAY-11-7082, 1 μM) for 24 h. Viability and apoptosis were detected by MMT and cytometry, miRNA, MMP-1, MMP-13, and Col2a1 by qRT-PCR and NF-κB activation by immunofluorescence. Visfatin and resistin significantly reduced viability, induced apoptosis, increased miR-34a, miR-155, miR-181a, and miR-let7e, and reduced miR-140 and miR-146a gene expression in OA chondrocytes. MMP-1, MMP-13, and Col2a1 were significantly modulated by treatment of OA chondrocytes with adipokines. Visfatin and resistin significantly increased NF-κB activation, while the co-treatment with BAY11-7082 did not change MMPs or Col2a1 levels beyond that caused by single treatment. Visfatin and resistin regulate the expression levels of some miRNA involved in OA pathogenesis and exert catabolic functions in chondrocytes via the NF-κB pathway. These data confirm the complex relationship between adipokines and miRNA. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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15 pages, 1424 KiB

Open AccessArticle

A Novel High Sensitivity Type II Collagen Blood-Based Biomarker, PRO-C2, for Assessment of Cartilage Formation

by Yunyun Luo, Yi He, Ditte Reker, Natasja Stæhr Gudmann, Kim Henriksen, Ole Simonsen, Christoph Ladel, Martin Michaelis, Ali Mobasheri, Morten Karsdal and Anne-Christine Bay-Jensen

Int. J. Mol. Sci. 2018, 19(11), 3485; https://doi.org/10.3390/ijms19113485 - 6 Nov 2018

Cited by 39 | Viewed by 5797

Abstract

N-terminal propeptide of type II collagen (PIINP) is a biomarker reflecting cartilage formation. PIINP exists in two main splice variants termed as type IIA and type IIB collagen NH₂-propeptide (PIIANP, PIIBNP). PIIANP has been widely recognized as a cartilage formation biomarker. [...] Read more.

N-terminal propeptide of type II collagen (PIINP) is a biomarker reflecting cartilage formation. PIINP exists in two main splice variants termed as type IIA and type IIB collagen NH₂-propeptide (PIIANP, PIIBNP). PIIANP has been widely recognized as a cartilage formation biomarker. However, the utility of PIIBNP as a marker in preclinical and clinical settings has not been fully investigated yet. In this study, we aimed to characterize an antibody targeting human PIIBNP and to develop an immunoassay assessing type II collagen synthesis in human blood samples. A high sensitivity electrochemiluminescence immunoassay, hsPRO-C2, was developed using a well-characterized antibody against human PIIBNP. Human cartilage explants from replaced osteoarthritis knees were cultured for ten weeks in the presence of growth factors, insulin-like growth factor 1 (IGF-1) or recombinant human fibroblast growth factor 18 (rhFGF-18). The culture medium was changed every seven days, and levels of PIIBNP, PIIANP, and matrix metalloproteinase 9-mediated degradation of type II collagen (C2M) were analyzed herein. Serum samples from a cross-sectional knee osteoarthritis cohort, as well as pediatric and rheumatoid arthritis samples, were assayed for PIIBNP and PIIANP. Western blot showed that the antibody recognized PIIBNP either as a free fragment or attached to the main molecule. Immunohistochemistry demonstrated that PIIBNP was predominately located in the extracellular matrix of the superficial and deep zones and chondrocytes in both normal and osteoarthritic articular cartilage. In addition, the hsPRO-C2 immunoassay exhibits acceptable technical performances. In the human cartilage explants model, levels of PIIBNP, but not PIIANP and C2M, were increased (2 to 7-fold) time-dependently in response to IGF-1. Moreover, there was no significant correlation between PIIBNP and PIIANP levels when measured in knee osteoarthritis, rheumatoid arthritis, and pediatric serum samples. Serum PIIBNP was significantly higher in controls (KL0/1) compared to OA groups (KL2/3/4, p = 0.012). The hsPRO-C2 assay shows completely different biological and clinical patterns than PIIANP ELISA, suggesting that it may be a promising biomarker of cartilage formation. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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13 pages, 2821 KiB

Open AccessArticle

Correlation between Diabetes Mellitus and Knee Osteoarthritis: A Dry-To-Wet Lab Approach

by Navneet Kumar Dubey, Dina Nur Anggraini Ningrum, Rajni Dubey, Yue-Hua Deng, Yu-Chuan Li, Peter D. Wang, Joseph R. Wang, Shabbir Syed-Abdul and Win-Ping Deng

Int. J. Mol. Sci. 2018, 19(10), 3021; https://doi.org/10.3390/ijms19103021 - 3 Oct 2018

Cited by 28 | Viewed by 6826

Abstract

Recent years have witnessed an increased prevalence of knee osteoarthritis (KOA) among diabetes mellitus (DM) patients—conditions which might share common risk factors such as obesity and advanced aging. Therefore, we conducted dry-to-wet lab research approaches to assess the correlation of type 1 DM [...] Read more.

Recent years have witnessed an increased prevalence of knee osteoarthritis (KOA) among diabetes mellitus (DM) patients—conditions which might share common risk factors such as obesity and advanced aging. Therefore, we conducted dry-to-wet lab research approaches to assess the correlation of type 1 DM (T1DM) and type 2 DM (T2DM) with KOA among all age and genders of Taiwanese population. The strength of association (odds ratio: OR) was analyzed using a phenome-wide association study portal. Populations of 37,353 T1DM and 1,218,254 T2DM were included. We observed a significant association of KOA with T1DM (OR: 1.40 (1.33–1.47), p< 0.0001) and T2DM (OR: 2.75 (2.72–2.78), p< 0.0001). The association between T1DM and KOA among the obese (OR: 0.99 (0.54–1.67), p = 0.0477) was insignificant compared to the non-obese (OR: 1.40 (1.33–1.48), p < 0.0001). Interestingly, a higher association between T2DM and KOA among non-obese persons (OR: 2.75, (2.72–2.79), p < 0.0001) compared to the obese (OR: 1.71 (1.55–1.89), p < 0.0001) was noted. Further, histopathologic and Western blot studies of diabetic mice knee joints revealed enhanced carboxymethyl lysine (advanced glycation end product), matrix metalloproteinase-1, and reduced cartilage-specific proteins, including type II collagen (Col II), SOX9, and aggrecan (AGN), indicating deteriorated articular cartilage and proteoglycans. Results indicate that DM is strongly associated with KOA, and obesity may not be a confounding factor. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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16 pages, 3624 KiB

Open AccessArticle

Comparative Transcriptomics Identifies Novel Genes and Pathways Involved in Post-Traumatic Osteoarthritis Development and Progression

by Aimy Sebastian, Jiun C. Chang, Melanie E. Mendez, Deepa K. Murugesh, Sarah Hatsell, Aris N. Economides, Blaine A. Christiansen and Gabriela G. Loots

Int. J. Mol. Sci. 2018, 19(9), 2657; https://doi.org/10.3390/ijms19092657 - 7 Sep 2018

Cited by 26 | Viewed by 5414

Abstract

Anterior cruciate ligament (ACL) injuries often result in post-traumatic osteoarthritis (PTOA). To better understand the molecular mechanisms behind PTOA development following ACL injury, we profiled ACL injury-induced transcriptional changes in knee joints of three mouse strains with varying susceptibility to OA: STR/ort (highly [...] Read more.

Anterior cruciate ligament (ACL) injuries often result in post-traumatic osteoarthritis (PTOA). To better understand the molecular mechanisms behind PTOA development following ACL injury, we profiled ACL injury-induced transcriptional changes in knee joints of three mouse strains with varying susceptibility to OA: STR/ort (highly susceptible), C57BL/6J (moderately susceptible) and super-healer MRL/MpJ (not susceptible). Right knee joints of the mice were injured using a non-invasive tibial compression injury model and global gene expression was quantified before and at 1-day, 1-week, and 2-weeks post-injury using RNA-seq. Following injury, injured and uninjured joints of STR/ort and injured C57BL/6J joints displayed significant cartilage degeneration while MRL/MpJ had little cartilage damage. Gene expression analysis suggested that prolonged inflammation and elevated catabolic activity in STR/ort injured joints, compared to the other two strains may be responsible for the severe PTOA phenotype observed in this strain. MRL/MpJ had the lowest expression values for several inflammatory cytokines and catabolic enzymes activated in response to ACL injury. Furthermore, we identified several genes highly expressed in MRL/MpJ compared to the other two strains including B4galnt2 and Tpsab1 which may contribute to enhanced healing in the MRL/MpJ. Overall, this study has increased our knowledge of early molecular changes associated with PTOA development. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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28 pages, 36090 KiB

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The Importance of Physioxia in Mesenchymal Stem Cell Chondrogenesis and the Mechanisms Controlling Its Response

by Girish Pattappa, Brian Johnstone, Johannes Zellner, Denitsa Docheva and Peter Angele

Int. J. Mol. Sci. 2019, 20(3), 484; https://doi.org/10.3390/ijms20030484 - 23 Jan 2019

Cited by 61 | Viewed by 7282

Abstract

Articular cartilage covers the surface of synovial joints and enables joint movement. However, it is susceptible to progressive degeneration with age that can be accelerated by either previous joint injury or meniscectomy. This degenerative disease is known as osteoarthritis (OA) and it greatly [...] Read more.

Articular cartilage covers the surface of synovial joints and enables joint movement. However, it is susceptible to progressive degeneration with age that can be accelerated by either previous joint injury or meniscectomy. This degenerative disease is known as osteoarthritis (OA) and it greatly affects the adult population. Cell-based tissue engineering provides a possible solution for treating OA at its earliest stages, particularly focal cartilage lesions. A candidate cell type for treating these focal defects are Mesenchymal Stem Cells (MSCs). However, present methods for differentiating these cells towards the chondrogenic lineage lead to hypertrophic chondrocytes and bone formation in vivo. Environmental stimuli that can stabilise the articular chondrocyte phenotype without compromising tissue formation have been extensively investigated. One factor that has generated intensive investigation in MSC chondrogenesis is low oxygen tension or physioxia (2–5% oxygen). In vivo articular cartilage resides at oxygen tensions between 1–4%, and in vitro results suggest that these conditions are beneficial for MSC expansion and chondrogenesis, particularly in suppressing the cartilage hypertrophy. This review will summarise the current literature regarding the effects of physioxia on MSC chondrogenesis with an emphasis on the pathways that control tissue formation and cartilage hypertrophy. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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17 pages, 1215 KiB

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Role of Forkhead Box O Transcription Factors in Oxidative Stress-Induced Chondrocyte Dysfunction: Possible Therapeutic Target for Osteoarthritis?

by Rikang Wang, Shuai Zhang, Rahul Previn, Di Chen, Yi Jin and Guangqian Zhou

Int. J. Mol. Sci. 2018, 19(12), 3794; https://doi.org/10.3390/ijms19123794 - 28 Nov 2018

Cited by 21 | Viewed by 6934

Abstract

Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have [...] Read more.

Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have recently been shown to play a protective role in chondrocyte dysfunction through the regulation of inflammation, autophagy, aging, and oxidative stress. They also regulate growth, maturation, and matrix synthesis in chondrocytes. In this review, we discuss the recent progress made in the field of oxidative stress-induced chondrocyte dysfunction. We also discuss the protective role of FoxO transcription factors as potential molecular targets for the treatment of OA. Understanding the function of FoxO transcription factors in the OA pathology may provide new insights that will facilitate the development of next-generation therapies to prevent OA development and to slow OA progression. Full article

(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: Focus on Pathophysiology and Molecular Mechanisms)

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