Association of NLRP3 single nucleotide polymorphisms with ulcerative colitis: A case-control study

Mechanistic insight: Linking cardiovascular complications of inflammatory bowel disease

Cardiovascular diseases (CVD) are the leading cause of mortality worldwide despite an aggressive reduction of traditional cardiovascular risk factors. Underlying inflammatory conditions such as inflammatory bowel disease (IBD) increase the risk of developing CVD. A broad understanding of the underlying pathophysiological processes between IBD and CVD is required to treat and prevent cardiovascular events in patients with IBD. This review highlights the commonality between IBD and CVD, including dysregulated immune response, genetics, environmental risk factors, altered gut microbiome, stress, endothelial dysfunction and abnormalities, to shed light on an essential area of modern medicine.

Emerging role of exosomes in ulcerative colitis: Targeting NOD-like receptor family pyrin domain containing 3 inflammasome

Ulcerative colitis (UC) is a chronic recurrent inflammatory bowel disease. Despite ongoing advances in our understanding of UC, its pathogenesis is yet unelucidated, underscoring the urgent need for novel treatment strategies for patients with UC. Exosomes are nanoscale membrane particles that mediate intercellular communication by carrying various bioactive molecules, such as proteins, RNAs, DNA, and metabolites. The NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a cytosolic tripartite protein complex whose activation induces the maturation and secretion of proinflammatory cytokines interleukin-1β (IL-1β) and IL-18, triggering the inflammatory response to a pathogenic agent or injury. Growing evidence suggests that exosomes are new modulators of the NLRP3 inflammasome, with vital roles in the pathological process of UC. Here, recent evidence is reviewed on the role of exosomes and NLRP3 inflammasome in UC. First, the dual role of exosomes on NLRP3 inflammasome and the effect of NLRP3 inflammasome on exosome secretion are summarized. Finally, an outlook on the directions of exosome-NLRP3 inflammasome crosstalk research in the context of UC is proposed and areas of further research on this topic are highlighted.

Treatment of Ulcerative Colitis by Cationic Liposome Delivered NLRP3 siRNA

Purpose

The abnormal activation of NLRP3 inflammasome is related to the occurrence and development of ulcerative colitis (UC). However, the ideal drug and delivery system remain important factors limiting the targeting of NLRP3 inflammasome in UC therapy. Gene therapy by delivering siRNA is effective in treating various diseases. Therefore, delivering siNLRP3 using an ideal vector for UC treatment is necessary.

Materials and Methods

Nanoparticles delivering siNLRP3 were developed based on cationic liposome (CLP/siNLRP3). Their ability to inhibit NLRP3 inflammasome activation was monitored using Western blot (WB) and Enzyme-linked Immunosorbent Assay (ELISA). The ASC oligomerization in LPS-primed peritoneal macrophages (PMs) was detected by WB and immunofluorescence. Moreover, we assessed the role of CLP/siNLRP3 on dextran sodium sulfate (DSS)-induced UC by examining NLRP3 levels, pro-inflammatory cytokines expression, and disease-associated index (DAI). Flow cytometry (FCM) was used to detect the contents of macrophages and T cells. Finally, we assessed the safety of CLP/siNLRP3.

Results

The prepared CLP was spherical, with a small particle size (94 nm) and low permeability. The CLP could efficiently protect siNLRP3 from degradation and then deliver siNLRP3 into PMs, inhibiting NLRP3 inflammasome activation. Also, the CLP/siNLRP3 could inhibit the secretion of mature IL-1β and IL-18 from PMs, thereby achieving a favorable anti-inflammation effect. In vivo, CLP/siNLRP3 could effectively alleviate intestinal injury in UC mice, which was attributed to down-regulating levels of IL-1β and IL-18, inhibiting infiltration of macrophages and other immune cells, and the polarization of M1 macrophages. Finally, pathological testing of tissue sections and blood biochemical tests showed no significant toxic effects of CLP/siNLRP3.

Conclusion

We introduced a prospective approach for the efficient delivery of siRNA in vitro and in vivo with high safety and stability, which was found to have great potential in treating NLRP3-driven diseases in an RNA-silencing manner.

Study of NLRP3 Single Nucleotide Polymorphisms in Juvenile Systemic Lupus Erythematosus (JSLE)

Juvenile systemic lupus erythematosus (JSLE) is a multifaceted multifactorial disorder with an unclear etiopathogenesis. Environmental factors, genetic factors, and dysregulated and defective immune system responses are known to have a role in JSLE etiopathogenesis. NLRP3 inflammasome, as an important contributor to immune-mediated inflammatory responses, is assumed to be involved in JSLE etiopathogenesis. To determine whether the NLRP3 genetic variants are altered in patients with JSLE. Fifty-three patients diagnosed with JSLE and 56 healthy sex-matched controls were studied. NLRP3 (C/G rs10754558, C/T rs3806265, C/T rs4612666, A/C rs35829419) gene polymorphisms were evaluated using a TaqMan single-nucleotide polymorphism assay. C allele at position rs3806265 was detected in higher frequencies in patients than in the control group (37.74% vs 23.21%, P-value = .028). At the genotype level at the same position, CT has a significantly higher frequency in patients than the healthy subjects (75.47% vs 46.43%, P-value = .003). The NLRP3 rs3806265 CT genotype was detected at a higher frequency in patients with JSLE than in the healthy control group.

Posttraumatic Osteomyelitis Risks Associated with NLRP3 Gene Polymorphisms in the Chinese Population

The purpose of this case-control study was to examine possible links between NLRP3 gene polymorphisms and the risk of developing posttraumatic osteomyelitis (PTOM) in the Chinese population. A total of 306 patients with PTOM and 368 normal controls were genotyped for NLRP3 (rs35829419, rs10754558, rs7525979, rs4612666), ELP2 (rs1785929, rs1789547, rs1785928, rs12185396, rs681757, rs8299, rs2032206, rs559289), STAT3 (rs4796793, rs744166, rs1026916, rs2293152, rs1053004), CASP1 (rs501192, rs580253, rs556205, rs530537), NFKBIA (rs696), NFKB1 (rs4648068), CARD8 (rs204321), and CD14 (rs2569190) using the genotyping technique SNaPshot. The genotype distributions of NLRP3 gene rs10754558 (p = 0.047) and rs7525979 (p = 0.048) significantly differed between the patients and the healthy controls. Additionally, heterozygous models indicated a significant association between NLRP3 rs10754558 and the likelihood of developing PTOM (OR = 1.600, p = 0.039), as did recessive and homozygous models of NLRP3 rs7525979 (OR = 0.248, p = 0.019 and 0.239, p = 0.016, respectively). Collectively, our findings suggest that, in the Chinese population, the risk of developing PTOM was increased by the association between NLRP3 rs10754558 and rs7525979. Therefore, our findings may provide novel insights and guidance in the prevention and development of PTOM.

Research trends in ulcerative colitis: A bibliometric and visualized study from 2011 to 2021

Background: Ulcerative colitis (UC) is an idiopathic inflammatory bowel disease with repeated relapses and remissions. Despite decades of effort, numerous aspects, including the initiating event and pathogenesis of UC, still remain ambiguous, which requires ongoing investigation. Given the mass of publications on UC, there are multidimensional challenges to evaluating the scientific impact of relevant work and identifying the current foci of the multifaceted disease. Accordingly, herein, we aim to assess the global growth of UC research production, analyze patterns of research areas, and evaluate trends in this area.

Methods: The Web of Science Core Collection of Clarivate Analytics was searched for articles related to UC published from 2011 to 2021. Microsoft Office Excel 2019 was used to visualize the number of publications over time. Knowledge maps were generated using CiteSpace and VOSviewer to analyze collaborations among countries, institutions, and authors and to present the journey of UC research as well as to reveal the current foci of UC research.

Results: A total of 5,088 publications were evaluated in the present study. China had the most publications (1,099, 22.5%). Univ Calif San Diego was the most productive institution (126, 2.48%). William J Sandborn published the greatest number of articles (100, 1.97%). Toshifumi Hibi was the most influential author in the field with a betweenness centrality of 0.53. Inflammatory bowel diseases was identified as the most prolific journal (379, 7.45%). Gastroenterology was the most co-cited journal (3,730, 4.02%). “Vedolizumab,” “tofacitinib,” “Faecalibacterium prausnitzii,” “fecal microbiota transplantation (FMT),” “toll-like receptor 4,” and “nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome” were considered the hot topics.

Conclusion: In UC research, manuscripts that had high impacts on the scientific community provided an evidence base. UC therapy has entered the era of personalized and precision therapy. As research on FMT, anti-integrin antibodies, Janus kinase inhibitors, and anti-tumor necrosis factor drugs continues to grow, their use in the clinical setting may also expand.

Novel splice‑site variants c.393G>A, c.278_2A>G in exon 2 and Q705K variant in exon 3 of NLRP3 gene are associated with bipolar I disorder

NOD‑like receptor pyrin domain‑containing 3 (NLRP3) has been considered to play a crucial role in triggering the host's immune and inflammatory responses. Genetic variants are critical determinants of interindividual variances in inflammatory responses and clinical outcomes. The role of NLRP3 gene variations in bipolar I (BPI) disorder, which is known to include genetic factors in its aetiology, has not been previously reported, at least to the best of our knowledge. The present study aimed to determine the role and frequency ofta exon 2 and exon 3 variants of NLRP3 in BPI disorder and to evaluate the association between different phenotypic traits. A case‑control study with 123 patients and 107 healthy controls was conducted to investigate the association of variants identified in the exon 2 and exon 3 regions of NLRP3, with the risk of BPI. Regions of interest were sequenced using a PCR‑based Sanger sequencing method. Three BPI‑related variants were identified. The genotype Q705K CA was detected more frequently in BPI patients, as compared to the control group [P<0.001; odds ratio (OR), 0.202; 95% confidence interval (CI), 0.080‑0.508]. In addition, two novel splice‑site variants (c.393G>A and c.278_2A>G) that, to the best of our knowledge, have not been previously reported in any database, were detected only in the BPI patient group [P<0.001; OR, 0.846; 95% CI, 0.784‑0.912; P<0.001; OR, 0.886; 95% CI, 0.832‑0.944, respectively]. There was no significant association between the Q795K variant and phenotypic traits (P>0.05). However, there was a significant association between those carrying the heterozygous c.393G>A variant and a positive family history (P=0.043). It was also observed that those with the heterozygous c.278‑2A>G variant presented with a significantly early‑onset (P=0.003). On the whole, the data of the present study suggested that NLRP3 plays a crucial role in the pathogenesis of BPI and may be a potential risk factor. However, further functional studies and repeated studies in other populations are required to properly comprehend the roles of the NLRP3 variants in the risk of developing BPI.

Identification of WT161 as a Potent Agent for the Treatment of Colitis by Targeting the Nucleotide-Binding Domain-Like Receptor Family Pyrin Domain Containing 3 Inflammasome

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis (UC), are chronic and recurrent intestinal inflammatory disorders. Numerous studies have revealed that the nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a pivotal role in the pathogenesis of IBD, and inhibition of the NLRP3 inflammasome alleviates colitis in experimental animals. Our previous study showed that C646, an inhibitor of histone acetyltransferase p300, has a protective role in dextran sulfate sodium (DSS)-induced colitis by targeting the NLRP3 inflammasome, making us further study the inhibitors of histone deacetylases (HDACs) in the treatment of colitis. In this study, we have shown that WT161, an inhibitor of HDAC6, exerts a protective role in a colitis model, blocks NLRP3 inflammasome activation, disrupts ASC speck formation, and decreases the expression of NLRP3. This study uncovers a new inhibitor of the NLRP3 inflammasome and suggests its potential application in the treatment of active IBD.

rs3806265 and rs4612666 of the NLRP3 Gene Are Associated With the Titer of Glutamic Acid Decarboxylase Antibody in Type 1 Diabetes

BACKGROUND AND AIMS

The NLRP3 gene is reportedly associated with several autoimmune diseases. However, in the Chinese Han population, whether NLRP3 polymorphisms are associated with type 1 diabetes (T1D) is unclear. Therefore, this study examined the associations of rs3806265 and rs4612666 of the NLRP3 gene with T1D susceptibility and the clinical characteristics of Chinese Han T1D patients.

METHODS

In total, 510 classic T1D patients and 531 healthy controls from the Chinese Han population were recruited for a case-control study. rs3806265 and rs4612666 of the NLRP3 gene were genotyped by MassARRAY. Logistic regression analysis and the chi-square test were used to compare the distributions of the alleles and genotypes of rs3806265 and rs4612666. The relationships between rs3806265 and rs4612666 and the clinical characteristics of T1D patients were analyzed by Kruskal-Wallis one-way ANOVA. Student's t test was used to analyze normally distributed data. Bonferroni correction was used for multiple comparisons.

RESULTS

1) rs3806265 was associated with glutamic acid decarboxylase antibody (GADA) titers (P = 0.02), and patients with the CC genotype had higher GADA titers than patients with the TT genotype. 2) rs4612666 was also associated with GADA titers (P=0.041). Compared with patients with the CC genotype, patients with the TT genotype had higher GADA titers. 3) rs3806265 and rs4612666 of the NLRP3 gene were not significantly associated with T1D susceptibility under different genetic models.

CONCLUSION

rs3806265 and rs4612666 of the NLRP3 gene were significantly associated with GADA titers in Chinese Han T1D patients.

Interaction between the inflammasome and commensal microorganisms in gastrointestinal health and disease

The inflammasome is a cytosolic multiprotein complex that plays a crucial role in inflammation and cell death. The sensor proteins in the inflammasome complex detect various microbial and endogenous stimuli, leading to subsequent caspase activation. The activation of caspases results in the maturation of pro-inflammatory cytokines IL-1β and IL-18 or pyroptosis. Inflammasome dysfunction is associated with the pathogenesis of various diseases, including autoimmune disease and cancer. It appears that the interactions between the gut microbiota and the inflammasome play crucial roles in the gastrointestinal tract. The gut microbiota induces the expression and activation of inflammasome proteins, which contribute to both homeostasis and disease in the gut. Likewise, although controversial, mounting evidence suggests that inflammasome activation can modulate the composition of the gut microbiota, which, in turn, affects disease progression. In this review, we summarize the current concepts and recent insights linking the inflammasome and gut commensal microorganisms. We describe how the reciprocal interaction between the inflammasome and the commensal microbiota relates to physiological and pathophysiological consequences in the host.

Intestinal Inflammation and Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease which significantly influences the life quality of patients. The protein α-synuclein plays an important driving role in PD occurrence and development. Braak's hypothesis suggests that α-synuclein is produced in intestine, and then spreads into the central nervous system through the vagus nerve. The abnormal expression of α-synuclein has been found in inflammatory bowel disease (IBD). Intestinal inflammation and intestinal dysbiosis have been involved in the occurrence and development of PD. The present review aimed to summarize recent advancements in studies focusing on intestinal inflammation and PD, especially the mechanisms through which link intestinal inflammation and PD. The intestinal dysfunctions such as constipation have been introduced as non-motor manifestations of PD. The possible linkages between IBD and PD, including genetic overlaps, inflammatory responses, intestinal permeability, and intestinal dysbiosis, are mainly discussed. Although it is not confirmed whether PD starts from intestine, intestinal dysfunction may affect intestinal microenvironment to influence central nervous system, including the α-synuclein pathologies and systematic inflammation. It is expected to develop some new strategies in the diagnosis and treatment of PD from the aspect of intestine. It may also become an exciting direction to find better ways to regulate the composition of gut microorganism to treat PD.

Quyu Shengxin Decoction Alleviates DSS-Induced Ulcerative Colitis in Mice by Suppressing RIP1/RIP3/NLRP3 Signalling

Purpose

To study the therapeutic effect of Quyu (QY) Shengxin (SX) decoction (QYSXD) in mice with dextran sulfate sodium- (DSS-) induced ulcerative colitis and to investigate the effects of QYSXD on the regulation of the receptor-interacting protein kinase 1 (RIP1)/receptor-interacting protein kinase 3 (RIP3)/nucleotide-binding oligomerization domain-like receptor family pyrin domain protein 3 (NLRP3) signaling pathway.

Method

Thirty-six mice were randomly divided into the following 6 groups: the experimental group (QYSX group), the model group (DSS group), the positive control group (5-aminosalicylic acid (5-ASA) group), the control group, the first component group (QY group), and the second component group (SX group). Each group included 6 mice. Ulcerative colitis (UC) was induced in the mice by providing 3.5% DSS in drinking water. The mice were weighed every day to evaluate the disease activity index (DAI). After 7 days, the mice were sacrificed, and colonic tissues were obtained for colon length measurement. The morphological changes in the colon and the pathological scores of the mice in each group were observed by hematoxylin-eosin (HE) staining. The messenger ribonucleic acid (mRNA) and protein expression levels of RIP1, RIP3, dynamin-related protein 1 (Drp1), NLRP3, cysteinyl aspartate specific proteinase-1 (caspase-1), interleukin (IL)-1β, and IL-18 in the colon tissues of the mice in each group were detected and compared by real-time quantitative reverse transcription PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). The levels of RIP1, RIP3, NLRP3, IL-1β, and IL-8 in the colonic mucosa were detected by ELISA. Western blotting was used to compare the protein expression of Drp1, caspase-1, mitochondrial fission protein 1 (FIS1), and mitophagy-associated protein light chain 3a/b (LC3a/b) among groups. The levels of reactive oxygen species (ROS) in the colonic mucosal cells were compared by immunofluorescence.

Results

Compared with those in the DSS group, the mice with DSS-induced colitis in the QYSX group exhibited clearly higher body weights (P < 0.05) and DAI scores (P < 0.05). The colon lengths of the mice in the QYSX group were longer than those in the DSS group (P < 0.05), and the pathological score of the QYSX group was lower than that of the DSS group (P < 0.05). The RIP1, RIP3, Drp1, IL-1β, IL-18, and caspase-1 mRNA levels in the QYSX, 5-ASA, SX, and QY groups were significantly lower than those in the DSS group (P < 0.05), but there were no differences between the QYSX group and the 5-ASA group. The levels of RIP1, RIP3, NLRP3, IL-1β, and IL-18 in the QYSX group were lower than those in the DSS group (P < 0.01). The levels of Drp1, caspase-1, FIS1, and LC3a/b in the QYSX group and the 5-ASA group were lower than those in the DSS group (P < 0.05). The levels of ROS in the colonic mucosal cells in the QYSX, 5-ASA, and QY groups were lower than those in the DSS group (P < 0.05).

Conclusion

QYSXD has certain therapeutic effects on DSS-induced colitis in mice and may be as effective as 5-ASA. QY and SX decoctions also have certain effects on colitis; however, these decoctions are not as beneficial as QYSXD. QYSXD may ameliorate colitis by inhibiting the expression of RIP1/RIP3/NLRP3 pathway-related proteins and reversing mitochondrial dysfunction to control inflammation.

Inflammasomes and Colorectal Cancer

Inflammasomes are important intracellular multiprotein signaling complexes that modulate the activation of caspase-1 and induce levels of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18 in response to pathogenic microorganisms and molecules that originated from host proteins. Inflammasomes play contradictory roles in the development of inflammation-induced cancers. Based on several findings, inflammasomes can initiate and promote carcinogenesis. On the contrary, inflammasomes also exhibit anticancer effects by triggering pyroptosis and immunoregulatory functions. Herein, we review extant studies delving into different functions of inflammasomes in colorectal cancer development.

A gain-of-function NLRP3 3'-UTR polymorphism causes miR-146a-mediated suppression of NLRP3 expression and confers protection against sepsis progression

Nucleotide-binding domain and leucine-rich repeat (LRR)-containing family protein 3 (NLRP3) regulated the maturation of inflammation-related cytokines by forming NLRP3 inflammasome, which plays pivotal roles in sepsis pathogenesis. In this study, we evaluated the genetic association of NLRP3 polymorphisms with sepsis (640 patients and 769 controls) and characterized the impact of NLRP3 polymorphisms on NLRP3 expression and inflammatory responses. No significant differences were observed in genotype/allelic frequencies of NLRP3 29940G>C between sepsis cases and controls. The G allele was significantly overrepresented in patients with septic shock than those in sepsis subgroup, and the GC/GG genetypes were related to the 28-day mortality of sepsis. Lipopolysaccharide challenge to peripheral blood mononuclear cells showed a significant suppression of NLRP3 mRNA expression and release of IL-1β and TNF-α in CC compared with the GC/GG genotype category. Functional experiments with luciferase reporter vectors containing the NLRP3 3′-UTR with the 29940 G-to-C variation in HUVECs and THP-1 cells showed a potential suppressive effect of miR-146a on NLRP3 transcription in the presence of the C allele. Taken together, these results demonstrated that the 29940 G-to-C mutation within the NLRP3 3′-UTR was a gain-of-function alteration that caused the suppression of NLRP3 expression and downstream inflammatory cytokine production via binding with miR-146a, which ultimately protected patients against susceptibility to sepsis progression and poor clinical outcome.

Three functional variants in the NLRP3 gene are associated with susceptibility and clinical characteristics of systemic lupus erythematosus

OBJECTIVE

Nod-like receptor pyrin domain containing 3 (NLRP3) gene encodes an intracellular receptor whose dysregulation in systemic lupus erythematosus (SLE) has been reported in multiple studies. Activation of NLRP3 inflammasome leads to the induction of inflammatory response via cleaving and producing of specific cytokines. In the present study, we assessed the possible association between three functional polymorphisms in this gene and SLE risk in the Iranian population. These variants include two gain of function (rs4612666 and rs10754558) and one loss of function (rs6672995) which are correlated with modulation of expression of NLRP3.

METHODS

A case-control study involving 110 SLE patients and 116 control subjects was undertaken to estimate the frequency of rs4612666, rs10754558, and rs6672995 genotypes using real-time PCR high resolution melting method (HRM).

RESULTS

Our findings revealed significant associations between GG genotype and G allele of rs10754558 with increased risk of SLE (OR _{for GG genotype}= 2.82; 95%CI [1.45-5.46]/OR _{for G allele}= 1.97; 95%CI [1.36-2.87]). Although, no significant associations were recognized between allele and genotype frequencies of rs4612666 and rs6672995 polymorphisms with SLE risk (P > 0.05). Also, our analysis revealed that the C allele in rs4612666 and G allele in rs10754558 was correlated with the severity of disease activity (P < 0.001). Moreover, these common variants were associated with lower age of onset and some clinical symptoms in the patient group, such as skin manifestation, neurological symptom and, renal involvement (P < 0.05).

CONCLUSION

This study demonstrates a substantial association between NLRP3 polymorphisms with increased risk, clinical symptoms, and the severity of disease activity of SLE.

Biological functions of NLRP3 inflammasome: A therapeutic target in inflammatory bowel disease

Cases of inflammatory bowel disease (IBD), a debilitating intestinal disorder with complex pathological mechanisms, have been increasing in recent years, straining the capacity of healthcare systems. Thus, novel therapeutic targets and innovative agents must be developed. Notably, the NLRP3 inflammasome is upregulated in patients with IBD and/or in animal experimental models. As an innate immune supramolecular assembly, the NLRP3 inflammasome is persistently activated during the pathogenesis of IBD by multiple stimuli. Moreover, this protein complex regulates pro-inflammatory cytokines. Thus, targeting this multiprotein oligomer may offer a feasible way to relieve IBD symptoms and improve clinical outcomes. The mechanisms by which the NLRP3 inflammasome is activated, its role in IBD pathogenesis, and the drugs administered to target this protein complex are reviewed herein. This review establishes that the use of inflammasome-targeting drugs are effective for IBD treatment. Moreover, this review suggests that the value and potential of naturally sourced or derived medicines for IBD treatment must be recognized and appreciated.

Inflammasome Regulation: Therapeutic Potential for Inflammatory Bowel Disease

Inflammasomes are multiprotein complexes formed to regulate the maturation of pro-inflammatory caspases, in response to intracellular or extracellular stimulants. Accumulating studies showed that the inflammasomes are implicated in the pathogenesis of inflammatory bowel disease (IBD), although their activation is not a decisive factor for the development of IBD. Inflammasomes and related cytokines play an important role in the maintenance of gut immune homeostasis, while its overactivation might induce excess immune responses and consequently cause tissue damage in the gut. Emerging studies provide evidence that some genetic abnormalities might induce enhanced NLRP3 inflammasome activation and cause colitis. In these cases, the colonic inflammation can be ameliorated by blocking NLRP3 activation or its downstream cytokine IL-1β. A number of natural products were shown to play a role in preventing colon inflammation in various experimental colitis models. On the other hand, lack of inflammasome function also causes intestinal abnormalities. Thus, an appropriate regulation of inflammasomes might be a promising therapeutic strategy for IBD intervention. This review aims at summarizing the main findings in these studies and provide an outline for further studies that might contribute to our understanding of the role of inflammasomes in the pathogenesis and therapeutic treatment of IBD.

Targeting the NLRP3 inflammasome as new therapeutic avenue for inflammatory bowel disease

The incidence and prevalence of inflammatory bowel disease (IBD) are increasing worldwide. Current approved medication for IBD treatment in the clinic mainly includes corticosteroids and neutralization antibodies to pro-inflammatory cytokines. However, drug resistance and severe side effect hinder long-term efficacy of these agents. The NOD-like receptor family pyrin domain containing protein 3 (NLRP3) is exclusively expressed in several inflammatory and autoimmune diseases. Excessive expression, aberrant activation, polymorphism, and gain-of-function mutation of the NLRP3 inflammasome contribute to IBD pathogenesis. In this article, we summarize the regulatory factors to NLRP3, and review recently developed NLRP3 inhibitors and their preclinical and clinical applications in treating inflammatory and autoimmune diseases. We present our views on the therapeutic potential of NLRP3 inhibitors as emerging therapeutic avenue for IBD.

Investigating the possible association between NLRP3 gene polymorphisms and myasthenia gravis

INTRODUCTION

In this case-control study, we investigated the association between nucleotide oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) single-nucleotide polymorphisms (SNPs) rs10754558, rs3806265, rs4612666, and rs35829419 and myasthenia gravis (MG).

METHODS

Samples from MG patients were selected from a previous study conducted in our neuromuscular clinic, which investigated the association between human leukocyte antigen (HLA) class II genes and MG. Genetic data of controls were also available from another study. The NLRP3 SNPs genotyping was performed using the TaqMan method.

RESULTS

A total of 93 blood samples from eligible Iranian patients with MG and 56 samples from healthy controls were obtained. The NLRP3 rs3806265 "C" allele was significantly more frequent in MG patients (P < .001; odd ratio [OR] = 2.33, 95% confidence interval [CI]: 1.4-4.0) than controls. The "CC" genotype of this SNP was found in 18.27% of patients, but none of the controls (P < .001). The distribution of other SNPs was similar between the groups.

DISCUSSION

These preliminary results suggest that there might be some associations between the NLRP3 gene polymorphism and MG.

Contradictory Effects of NLRP3 Inflammasome Regulatory Mechanisms in Colitis

The inflammasome is an intracellular molecular complex, which is mainly involved in innate immunity. Inflammasomes are formed in response to danger signals, associated with infection and injury, and mainly regulate the secretion of interleukin-1β and interleukin-18. Inflammasome dysregulation is known to be associated with various diseases and conditions, and its regulatory mechanisms have become of great interest in recent years. In the colon, inflammasomes have been reported to be associated with autophagy and the microbiota, and their dysregulation contributes to colitis and. However, the detailed role of inflammasomes in inflammatory bowel disease is still under debate because the mechanisms that regulate the inflammasome are complex and the inflammasome components and cytokines show seemingly contradictory multiple effects. Herein, we comprehensively review the literature on inflammasome functioning in the colon and describe the complex interactions of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome components with inflammatory cytokines, autophagy, and the microbiota in experimental colitis models and patients with inflammatory bowel disease.

Targeting NLRP3 Inflammasome in Inflammatory Bowel Disease: Putting out the Fire of Inflammation. Inflammation. 2019;42:1147-1159. [PMID: 30937839 DOI: 10.1007/s10753-019-01008-y]

Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine, comprised of ulcerative colitis and Crohn's disease. Among the complicated pathogenic factors of IBD, the overaction of inflammatory and immune reaction serves as an important factor. Inflammasome is a form of innate immunity as well as inflammation. Among all kinds of inflammasomes, the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is the most studied one, and has been revealed to be involved in the pathogenesis and progression of IBD. Here, in this review, the association between the NLRP3 inflammasome and IBD will be discussed. Furthermore, several NLRP3 inflammasome inhibitors which have been demonstrated to be effective in the alleviation of IBD will be described in this review.

Contribution of Non-immune Cells to Activation and Modulation of the Intestinal Inflammation

The mucosal immune system constitutes a physical and dynamic barrier against foreign antigens and pathogens and exerts control mechanisms to maintain intestinal tolerance to the microbiota and food antigens. Chronic alterations of the intestinal homeostasis predispose to inflammatory diseases of the gastrointestinal tract, such as Inflammatory Bowel Diseases (IBD). There is growing evidence that the frequency and severity of these diseases are increasing worldwide, which may be probably due to changes in environmental factors. Several stromal and immune cells are involved in this delicate equilibrium that dictates homeostasis. In this review we aimed to summarize the role of epithelial cells and fibroblasts in the induction of mucosal inflammation in the context of IBD. It has been extensively described that environmental factors are key players in this process, and the microbiome of the gastrointestinal tract is currently being intensively investigated due to its profound impact the immune response. Recent findings have demonstrated the interplay between dietary and environmental components, the gut microbiome, and immune cells. "Western" dietary patterns, such as high caloric diets, and pollution can induce alterations in the gut microbiome that in turn affect the intestinal and systemic homeostasis. Here we summarize current knowledge on the influence of dietary components and air particulate matters on gut microbiome composition, and the impact on stromal and immune cells, with a particular focus on promoting local inflammation.

NLRP3 Inflammasome and Inflammatory Bowel Disease

NLRP3 inflammasome can be widely found in epithelial cells and immune cells. The NOD-like receptors (NLRs) family member NLRP3 contains a central nucleotide-binding and oligomerization (NACHT) domain which facilitates self-oligomerization and has ATPase activity. The C-terminal conserves a leucine-rich repeats (LRRs) domain which can modulate NLRP3 activity and sense endogenous alarmins and microbial ligands. In contrast, the N-terminal pyrin domain (PYD) can account for homotypic interactions with the adaptor protein-ASC of NLRP3 inflammasome. These characters enable it function in innate immunity. Its downstream effector proteins include caspase-1 and IL-1β etc. which exhibit protective or detrimental roles in mucosal immunity in different studies. Here, we comprehensively review the current literature regarding the physiology of NLRP3 inflammasome and its potential roles in the pathogenesis of IBD. We also discuss about the complex interactions among the NLRP3 inflammasome, mucosal immune response, and gut homeostasis as found in experimental models and IBD patients.