International Journal of Molecular Sciences

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Open AccessEditorial

Editorial of Special Issue “Inflammasomes and Inflammation”

by Young-Su Yi

Int. J. Mol. Sci. 2022, 23(5), 2489; https://doi.org/10.3390/ijms23052489 - 24 Feb 2022

Cited by 1 | Viewed by 1502

Abstract

Although inflammation is a host-protective mechanism from infection and cellular danger signals, chronic inflammation is a major risk factor for various human diseases [...] Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

Research

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13 pages, 4704 KiB

Open AccessArticle

Human Endothelial Progenitor Cells Protect the Kidney against Ischemia-Reperfusion Injury via the NLRP3 Inflammasome in Mice

by Ha Nee Jang, Jin Hyun Kim, Myeong Hee Jung, Taekil Tak, Jung Hwa Jung, Seunghye Lee, Sehyun Jung, Se-Ho Chang and Hyun-Jung Kim

Int. J. Mol. Sci. 2022, 23(3), 1546; https://doi.org/10.3390/ijms23031546 - 28 Jan 2022

Cited by 9 | Viewed by 3037

Abstract

Ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and progression to chronic kidney disease (CKD). However, no effective therapeutic intervention has been established for ischemic AKI. Endothelial progenitor cells (EPCs) have major roles in the maintenance of vascular integrity [...] Read more.

Ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and progression to chronic kidney disease (CKD). However, no effective therapeutic intervention has been established for ischemic AKI. Endothelial progenitor cells (EPCs) have major roles in the maintenance of vascular integrity and the repair of endothelial damage; they also serve as therapeutic agents in various kidney diseases. Thus, we examined whether EPCs have a renoprotective effect in an IRI mouse model. Mice were assigned to sham, EPC, IRI-only, and EPC-treated IRI groups. EPCs originating from human peripheral blood were cultured. The EPCs were administered 5 min before reperfusion, and all mice were killed 72 h after IRI. Blood urea nitrogen, serum creatinine, and tissue injury were significantly increased in IRI mice; EPCs significantly improved the manifestations of IRI. Apoptotic cell death and oxidative stress were significantly reduced in EPC-treated IRI mice. Administration of EPCs decreased the expression levels of NLRP3, cleaved caspase-1, p-NF-κB, and p-p38. Furthermore, the expression levels of F4/80, ICAM-1, RORγt, and IL-17RA were significantly reduced in EPC-treated IRI mice. Finally, the levels of EMT-associated factors (TGF-β, α-SMA, Snail, and Twist) were significantly reduced in EPC-treated IRI mice. This study shows that inflammasome-mediated inflammation accompanied by immune modulation and fibrosis is a potential target of EPCs as a treatment for IRI-induced AKI and the prevention of progression to CKD. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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16 pages, 3015 KiB

Open AccessArticle

Soluble Endoglin Stimulates Inflammatory and Angiogenic Responses in Microglia That Are Associated with Endothelial Dysfunction

by Eun S. Park, Sehee Kim, Derek C. Yao, Jude P. J. Savarraj, Huimahn Alex Choi, Peng Roc Chen and Eunhee Kim

Int. J. Mol. Sci. 2022, 23(3), 1225; https://doi.org/10.3390/ijms23031225 - 22 Jan 2022

Cited by 12 | Viewed by 3460

Abstract

Increased soluble endoglin (sENG) has been observed in human brain arteriovenous malformations (bAVMs). In addition, the overexpression of sENG in concurrence with vascular endothelial growth factor (VEGF)-A has been shown to induce dysplastic vessel formation in mouse brains. However, the underlying mechanism of [...] Read more.

Increased soluble endoglin (sENG) has been observed in human brain arteriovenous malformations (bAVMs). In addition, the overexpression of sENG in concurrence with vascular endothelial growth factor (VEGF)-A has been shown to induce dysplastic vessel formation in mouse brains. However, the underlying mechanism of sENG-induced vascular malformations is not clear. The evidence suggests the role of sENG as a pro-inflammatory modulator, and increased microglial accumulation and inflammation have been observed in bAVMs. Therefore, we hypothesized that microglia mediate sENG-induced inflammation and endothelial cell (EC) dysfunction in bAVMs. In this study, we confirmed that the presence of sENG along with VEGF-A overexpression induced dysplastic vessel formation. Remarkably, we observed increased microglial activation around dysplastic vessels with the expression of NLRP3, an inflammasome marker. We found that sENG increased the gene expression of VEGF-A, pro-inflammatory cytokines/inflammasome mediators (TNF-α, IL-6, NLRP3, ASC, Caspase-1, and IL-1β), and proteolytic enzyme (MMP-9) in BV2 microglia. The conditioned media from sENG-treated BV2 (BV2-sENG-CM) significantly increased levels of angiogenic factors (Notch-1 and TGFβ) and pERK1/2 in ECs but it decreased the level of IL-17RD, an anti-angiogenic mediator. Finally, the BV2-sENG-CM significantly increased EC migration and tube formation. Together, our study demonstrates that sENG provokes microglia to express angiogenic/inflammatory molecules which may be involved in EC dysfunction. Our study corroborates the contribution of microglia to the pathology of sENG-associated vascular malformations. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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15 pages, 3213 KiB

Open AccessArticle

Differential Expression of Inflammasome-Related Genes in Induced Pluripotent Stem-Cell-Derived Retinal Pigment Epithelial Cells with or without History of Age-Related Macular Degeneration

by Maria Hytti, Eveliina Korhonen, Heidi Hongisto, Kai Kaarniranta, Heli Skottman and Anu Kauppinen

Int. J. Mol. Sci. 2021, 22(13), 6800; https://doi.org/10.3390/ijms22136800 - 24 Jun 2021

Cited by 11 | Viewed by 3041

Abstract

Inflammation is a key underlying factor of age-related macular degeneration (AMD) and inflammasome activation has been linked to disease development. Induced pluripotent stem-cell-derived retinal pigment epithelial cells (iPSC-RPE) are an attractive novel model system that can help to further elucidate disease pathways of [...] Read more.

Inflammation is a key underlying factor of age-related macular degeneration (AMD) and inflammasome activation has been linked to disease development. Induced pluripotent stem-cell-derived retinal pigment epithelial cells (iPSC-RPE) are an attractive novel model system that can help to further elucidate disease pathways of this complex disease. Here, we analyzed the effect of dysfunctional protein clearance on inflammation and inflammasome activation in iPSC-RPE cells generated from a patient suffering from age-related macular degeneration (AMD) and an age-matched control. We primed iPSC-RPE cells with IL-1α and then inhibited both proteasomal degradation and autophagic clearance using MG-132 and bafilomycin A1, respectively, causing inflammasome activation. Subsequently, we determined cell viability, analyzed the expression levels of inflammasome-related genes using a PCR array, and measured the levels of pro-inflammatory cytokines IL-1β, IL-6, IL-8, and MCP-1 secreted into the medium. Cell treatments modified the expression of 48 inflammasome-related genes and increased the secretion of mature IL-1β, while reducing the levels of IL-6 and MCP-1. Interestingly, iPSC-RPE from an AMD donor secreted more IL-1β and expressed more Hsp90 prior to the inhibition of protein clearance, while MCP-1 and IL-6 were reduced at both protein and mRNA levels. Overall, our results suggest that cellular clearance mechanisms might already be dysfunctional, and the inflammasome activated, in cells with a disease origin. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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Review

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21 pages, 1075 KiB

Open AccessReview

NLRP3 Ubiquitination—A New Approach to Target NLRP3 Inflammasome Activation

by Mahbuba Akther, Md Ezazul Haque, Jooho Park, Tae-Bong Kang and Kwang-Ho Lee

Int. J. Mol. Sci. 2021, 22(16), 8780; https://doi.org/10.3390/ijms22168780 - 16 Aug 2021

Cited by 51 | Viewed by 6852

Abstract

In response to diverse pathogenic and danger signals, the cytosolic activation of the NLRP3 (NOD-, LRR-, and pyrin domain-containing (3)) inflammasome complex is a critical event in the maturation and release of some inflammatory cytokines in the state of an inflammatory response. After [...] Read more.

In response to diverse pathogenic and danger signals, the cytosolic activation of the NLRP3 (NOD-, LRR-, and pyrin domain-containing (3)) inflammasome complex is a critical event in the maturation and release of some inflammatory cytokines in the state of an inflammatory response. After activation of the NLRP3 inflammasome, a series of cellular events occurs, including caspase 1-mediated proteolytic cleavage and maturation of the IL-1β and IL-18, followed by pyroptotic cell death. Therefore, the NLRP3 inflammasome has become a prime target for the resolution of many inflammatory disorders. Since NLRP3 inflammasome activation can be triggered by a wide range of stimuli and the activation process occurs in a complex, it is difficult to target the NLRP3 inflammasome. During the activation process, various post-translational modifications (PTM) of the NLRP3 protein are required to form a complex with other components. The regulation of ubiquitination and deubiquitination of NLRP3 has emerged as a potential therapeutic target for NLRP3 inflammasome-associated inflammatory disorders. In this review, we discuss the ubiquitination and deubiquitination system for NLRP3 inflammasome activation and the inhibitors that can be used as potential therapeutic agents to modulate the activation of the NLRP3 inflammasome. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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11 pages, 658 KiB

Open AccessReview

Inflammatory Response in COVID-19 Patients Resulting from the Interaction of the Inflammasome and SARS-CoV-2

by So Yeong Cheon and Bon-Nyeo Koo

Int. J. Mol. Sci. 2021, 22(15), 7914; https://doi.org/10.3390/ijms22157914 - 24 Jul 2021

Cited by 18 | Viewed by 3491

Abstract

The outbreak of the coronavirus disease 2019 (COVID-19) began at the end of 2019. COVID-19 is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and patients with COVID-19 may exhibit poor clinical outcomes. Some patients with severe COVID-19 experience [...] Read more.

The outbreak of the coronavirus disease 2019 (COVID-19) began at the end of 2019. COVID-19 is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and patients with COVID-19 may exhibit poor clinical outcomes. Some patients with severe COVID-19 experience cytokine release syndrome (CRS) or a cytokine storm—elevated levels of hyperactivated immune cells—and circulating pro-inflammatory cytokines, including interleukin (IL)-1β and IL-18. This severe inflammatory response can lead to organ damage/failure and even death. The inflammasome is an intracellular immune complex that is responsible for the secretion of IL-1β and IL-18 in various human diseases. Recently, there has been a growing number of studies revealing a link between the inflammasome and COVID-19. Therefore, this article summarizes the current literature regarding the inflammasome complex and COVID-19. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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22 pages, 2239 KiB

Open AccessReview

Functional Interplay between Methyltransferases and Inflammasomes in Inflammatory Responses and Diseases

by Young-Su Yi

Int. J. Mol. Sci. 2021, 22(14), 7580; https://doi.org/10.3390/ijms22147580 - 15 Jul 2021

Cited by 12 | Viewed by 3224

Abstract

An inflammasome is an intracellular protein complex that is activated in response to a pathogenic infection and cellular damage. It triggers inflammatory responses by promoting inflammatory cell death (called pyroptosis) and the secretion of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. Many types of [...] Read more.

An inflammasome is an intracellular protein complex that is activated in response to a pathogenic infection and cellular damage. It triggers inflammatory responses by promoting inflammatory cell death (called pyroptosis) and the secretion of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. Many types of inflammasomes have been identified and demonstrated to play a central role in inducing inflammatory responses, leading to the onset and progression of numerous inflammatory diseases. Methylation is a biological process by which methyl groups are transferred from methyl donors to proteins, nucleic acids, and other cellular molecules. Methylation plays critical roles in various biological functions by modulating gene expression, protein activity, protein localization, and molecular stability, and aberrant regulation of methylation causes deleterious outcomes in various human diseases. Methylation is a key determinant of inflammatory responses and diseases. This review highlights the current understanding of the functional relationship between inflammasome regulation and methylation of cellular molecules in inflammatory responses and diseases. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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32 pages, 2936 KiB

Open AccessReview

Aberrant NLRP3 Inflammasome Activation Ignites the Fire of Inflammation in Neuromuscular Diseases

by Christine Péladeau and Jagdeep K. Sandhu

Int. J. Mol. Sci. 2021, 22(11), 6068; https://doi.org/10.3390/ijms22116068 - 4 Jun 2021

Cited by 11 | Viewed by 5373

Abstract

Inflammasomes are molecular hubs that are assembled and activated by a host in response to various microbial and non-microbial stimuli and play a pivotal role in maintaining tissue homeostasis. The NLRP3 is a highly promiscuous inflammasome that is activated by a wide variety [...] Read more.

Inflammasomes are molecular hubs that are assembled and activated by a host in response to various microbial and non-microbial stimuli and play a pivotal role in maintaining tissue homeostasis. The NLRP3 is a highly promiscuous inflammasome that is activated by a wide variety of sterile triggers, including misfolded protein aggregates, and drives chronic inflammation via caspase-1-mediated proteolytic cleavage and secretion of proinflammatory cytokines, interleukin-1β and interleukin-18. These cytokines further amplify inflammatory responses by activating various signaling cascades, leading to the recruitment of immune cells and overproduction of proinflammatory cytokines and chemokines, resulting in a vicious cycle of chronic inflammation and tissue damage. Neuromuscular diseases are a heterogeneous group of muscle disorders that involve injury or dysfunction of peripheral nerves, neuromuscular junctions and muscles. A growing body of evidence suggests that dysregulation, impairment or aberrant NLRP3 inflammasome signaling leads to the initiation and exacerbation of pathological processes associated with neuromuscular diseases. In this review, we summarize the available knowledge about the NLRP3 inflammasome in neuromuscular diseases that affect the peripheral nervous system and amyotrophic lateral sclerosis, which affects the central nervous system. In addition, we also examine whether therapeutic targeting of the NLRP3 inflammasome components is a viable approach to alleviating the detrimental phenotype of neuromuscular diseases and improving clinical outcomes. Full article

(This article belongs to the Special Issue Inflammasomes and Inflammation)

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