Downregulated NLRP3 and NLRP1 inflammasomes signaling pathways in the development and progression of type 1 diabetes mellitus

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Inflammasome functional activities in B lymphocytes

Studies in animal models and human subjects have shown that, in addition to their implication in innate immunity, inflammasomes also can play a role in adaptive immunity. However, the contribution of the nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome pathway to adaptive immunity remains incompletely explored. Here, we show that NLRP3 plays an important role in different facets of B cell functions, including proliferation, antibody production, and secretion of inflammatory and anti-inflammatory cytokines. When exposed to B cell receptor engagement, Toll-like receptor activation, stimulation in conditions that mimic T cell-dependent responses, or NLRP3 activation, B cells manifest disparate responses and produce different cytokine patterns critical for modulating innate and adaptive immunity, indicating that the cytokines produced serve a critical link between the early innate immune response and the delayed adaptive immunity. Importantly, genetic ablation of nlrp3 reduced the inflammasome-mediated functions of B cells. We propose that, in the absence of other cell types, the potential of B lymphocytes to respond to NLRP3 engagement enables them to initiate inflammatory cascades through recruitment of other cell subsets, such as macrophages and neutrophils. Since NLRP3 activation of B cells is not followed by pyroptosis, even in the presence of a basal caspase-1 activity, this pathway acts as a bridge that optimizes interactions between the innate and adoptive branches of the immune response.

Exploring the molecular mechanism of Xuebifang in the treatment of diabetic peripheral neuropathy based on bioinformatics and network pharmacology

Background

Xuebifang (XBF), a potent Chinese herbal formula, has been employed in managing diabetic peripheral neuropathy (DPN). Nevertheless, the precise mechanism of its action remains enigmatic.

Purpose

The primary objective of this investigation is to employ a bioinformatics-driven approach combined with network pharmacology to comprehensively explore the therapeutic mechanism of XBF in the context of DPN.

Study design and Methods

The active chemicals and their respective targets of XBF were sourced from the TCMSP and BATMAN databases. Differentially expressed genes (DEGs) related to DPN were obtained from the GEO database. The targets associated with DPN were compiled from the OMIM, GeneCards, and DrugBank databases. The analysis of GO, KEGG pathway enrichment, as well as immuno-infiltration analysis, was conducted using the R language. The investigation focused on the distribution of therapeutic targets of XBF within human organs or cells. Subsequently, molecular docking was employed to evaluate the interactions between potential targets and active compounds of XBF concerning the treatment of DPN.

Results

The study successfully identified a total of 122 active compounds and 272 targets associated with XBF. 5 core targets of XBF for DPN were discovered by building PPI network. According to GO and KEGG pathway enrichment analysis, the mechanisms of XBF for DPN could be related to inflammation, immune regulation, and pivotal signalling pathways such as the TNF, TLR, CLR, and NOD-like receptor signalling pathways. These findings were further supported by immune infiltration analysis and localization of immune organs and cells. Moreover, the molecular docking simulations demonstrated a strong binding affinity between the active chemicals and the carefully selected targets.

Conclusion

In summary, this study proposes a novel treatment model for XBF in DPN, and it also offers a new perspective for exploring the principles of traditional Chinese medicine (TCM) in the clinical management of DPN.

Gut-Gonad Perturbations in Type-1 Diabetes Mellitus: Role of Dysbiosis, Oxidative Stress, Inflammation and Energy-Dysbalance

Type 1 diabetes mellitus is a major metabolic disorder that affects people of all age groups throughout the world. It is responsible for the alterations in male gonadal physiology in experimental models as well as in clinical cases. On the other side, diabetes mellitus has also been associated with perturbations in the gut physiology and microbiota dysbiosis. The accumulating evidence suggests a link between the gut and gonad as evident from the i) experimental data providing insights into type 1 diabetes mellitus induced gut perturbations, ii) link of gut physiology with alterations of testicular health, iii) role of gut microbiota in androgen metabolism in the intestine, and iv) epidemiological evidence linking type 1 diabetes mellitus with inflammatory bowel disease and male infertility. Considering all the pieces of evidence, it is summarized that gut dysbiosis, oxidative stress, inflammation and energy dys-balance are the prime factors involved in the gonadal damage under type 1 diabetes mellitus, in which the gut contributes significantly. Identification of novel biomarkers and intervention of suitable agents targeting these prime factors may be a step forward to restore the gonadal damage in diabetic conditions.

Role of NLRP3 inflammasome in diabetes and COVID-19 role of NLRP3 inflammasome in the pathogenesis and treatment of COVID-19 and diabetes NLRP3 inflammasome in diabetes and COVID-19 intervention

2019 Coronavirus Disease (COVID-19) is a global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). A "cytokine storm", i.e., elevated levels of pro-inflammatory cytokines in the bloodstream, has been observed in severe cases of COVID-19. Normally, activation of the nucleotide-binding oligomeric domain-like receptor containing pyrin domain 3 (NLRP3) inflammatory vesicles induces cytokine production as an inflammatory response to viral infection. Recent studies have found an increased severity of necrobiosis infection in diabetic patients, and data from several countries have shown higher morbidity and mortality of necrobiosis in people with chronic metabolic diseases such as diabetes. In addition, COVID-19 may also predispose infected individuals to hyperglycemia. Therefore, in this review, we explore the potential relationship between NLRP3 inflammatory vesicles in diabetes and COVID-19. In contrast, we review the cellular/molecular mechanisms by which SARS-CoV-2 infection activates NLRP3 inflammatory vesicles. Finally, we propose several promising targeted NLRP3 inflammatory vesicle inhibitors with the aim of providing a basis for NLRP3-targeted drugs in diabetes combined with noncoronary pneumonia in the clinical management of patients.

Sterile inflammation and the NLRP3 inflammasome in cardiometabolic disease

Inflammation plays an important role in the pathophysiology of cardiometabolic diseases. Sterile inflammation, a non-infectious and damage-associated molecular pattern (DAMP)-induced innate response, is now well-established to be closely associated with development and progression of cardiometabolic diseases. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is well-established as a major player in sterile inflammatory responses. It is a multimeric cytosolic protein complex which regulates the activation of caspase-1 and subsequently promotes cleavage and release of interleukin (IL)-1 family cytokines, which have a deleterious impact on the development of cardiometabolic diseases. Therefore, targeting NLRP3 itself or the downstream consequences of NLRP3 activation represent excellent potential therapeutic targets in inflammatory cardiometabolic diseases. Here, we review our current understanding of the role which NLRP3 inflammasome regulation plays in cardiometabolic diseases such as obesity, diabetes, non-alcoholic steatohepatitis (NASH), atherosclerosis, ischemic heart disease and cardiomyopathy. Finally, we highlight the potential of targeting NLPR3 or related signaling molecules as a therapeutic approach.

From Innate Immunity to Metabolic Disorder: A Review of the NLRP3 Inflammasome in Diabetes Mellitus

The role of the NLRP3 inflammasome is pivotal in the pathophysiology and progression of diabetes mellitus (DM), encompassing both type 1 (T1D), or type 2 (T2D). As part of the innate immune system, NLRP3 is also responsible for the chronic inflammation triggered by hyperglycemia. In both conditions, NLRP3 facilitates the release of interleukin-1β and interleukin-18. For T1D, NLRP3 perpetuates the autoimmune cascade, leading to the destruction of pancreatic islet cells. In T2D, its activation is associated with the presence of insulin resistance. NLRP3 activation is also instrumental for the presence of numerous complications associated with DM, microvascular and macrovascular. A considerable number of anti-diabetic drugs have demonstrated the ability to inhibit the NLRP3 inflammasome.

Role of the inflammasome in insulin resistance and type 2 diabetes mellitus

The inflammasome is a protein complex composed of a variety of proteins in cells and which participates in the innate immune response of the body. It can be activated by upstream signal regulation and plays an important role in pyroptosis, apoptosis, inflammation, tumor regulation, etc. In recent years, the number of metabolic syndrome patients with insulin resistance (IR) has increased year by year, and the inflammasome is closely related to the occurrence and development of metabolic diseases. The inflammasome can directly or indirectly affect conduction of the insulin signaling pathway, involvement the occurrence of IR and type 2 diabetes mellitus (T2DM). Moreover, various therapeutic agents also work through the inflammasome to treat with diabetes. This review focuses on the role of inflammasome on IR and T2DM, pointing out the association and utility value. Briefly, we have discussed the main inflammasomes, including NLRP1, NLRP3, NLRC4, NLRP6 and AIM2, as well as their structure, activation and regulation in IR were described in detail. Finally, we discussed the current therapeutic options-associated with inflammasome for the treatment of T2DM. Specially, the NLRP3-related therapeutic agents and options are widely developed. In summary, this article reviews the role of and research progress on the inflammasome in IR and T2DM.

Leptin-depended NLRP3 inflammasome activation in osteoarthritic chondrocytes is mediated by ROS

Leptin and ROS are implicated in the regulation of inflammatory pathways including NLRP3-inflammasome. We investigated the functional link between leptin, ROS and NLRP3-inflammasome formation/activation in osteoarthritis (OA), an age-related disease. We found that inflammasome components' (NLRP3, ASC, Caspase-1 and cleaved Caspase-1) protein expression were increased in OA cartilage biopsies and chondrocytes compared to healthy cartilage and chondrocytes. Immunofluorescence showed increased co-localization of NLRP3/ASC and NLRP3/Caspase-1, ASC-specks formation and ROS levels in OA compared to normal chondrocytes. NOX4 mRNA expression and IL-1β/IL-18 secretion levels were also elevated in OA chondrocytes. Furthermore, NLRP3-siRNA in OA chondrocytes revealed significant MMP-9/MMP-13 downregulation. To elucidate leptin/ROS/NLRP3-inflammasome interactions, OA chondrocytes were treated with ROS-inhibitor NAC, NOXs-inhibitor DPI, NOX4-inhibitor GLX351322 and leptin-siRNA, while normal chondrocytes were incubated with leptin with or without DPI or GLX351322. We observed attenuated ROS levels and NLRP3-inflammasome formation/activation in NAC-, DPI- or GLX351322-treated OA chondrocytes, while the same effect was shown after transfection with leptin-siRNA. Furthermore, incubation of normal chondrocytes with leptin enhanced ROS production and inflammasome formation/activation, while pretreatment with DPI or GLX351322 abolished leptin's stimulatory effects confirming leptin-NOX4-ROS-inflammasome regulatory axis. Overall, our findings provide novel evidence indicating that leptin-induced NLRP3-inflammasome formation/activation in OA chondrocytes is mediated by NOX4-dependent ROS production.

Obesity and Coronavirus Disease 2019

The coronavirus disease 2019 (COVID-19) pandemic has brought severe challenges to global public health. Many studies have shown that obesity plays a vital role in the occurrence and development of COVID-19. Obesity exacerbates COVID-19, leading to increased intensive care unit hospitalization rate, high demand for invasive mechanical ventilation, and high mortality. The mechanisms of interaction between obesity and COVID-19 involve inflammation, immune response, changes in pulmonary dynamics, disruptions of receptor ligands, and dysfunction of endothelial cells. Therefore, for obese patients with COVID-19, the degree of obesity and related comorbidities should be evaluated. Treatment methods such as administration of anticoagulants and anti-inflammatory drugs like glucocorticoids and airway management should be actively initiated. We should also pay attention to long-term prognosis and vaccine immunity and actively address the physical and psychological problems caused by longterm staying-at-home during the pandemic. The present study summarized the research to investigate the role of obesity in the incidence and progression of COVID-19 and the psychosocial impact and treatment options for obese patients with COVID-19, to guide the understanding and management of the disease.

Changes in plasma IRAK-M in patients with prediabetes and its relationship with related metabolic indexes: a cross-sectional study

OBJECTIVE

To investigate whether IL-1R-associated kinase (IRAK)-M is associated with prediabetes and type 2 diabetes (T2D).

METHODS

In this cross-sectional study, enrolled subjects were assigned to different groups according to their fasting plasma glucose (FPG) values. IRAK-M and metabolic parameters, including fasting insulin (FINS), glycosylated hemoglobin (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-β), and thioredoxin-interacting protein (TXNIP), were evaluated. The area under the receiver operating characteristic curve of IRAK-M and TXNIP for prediabetes and T2D was determined.

RESULTS

IRAK-M decreased significantly with increasing FPG levels. IRAK-M was negatively correlated with TXNIP, FPG, FINS, HbA1c, and HOMA-IR and positively correlated with HOMA-β. The diagnostic cutoff value of IRAK-M was 3.76 ng/mL for prediabetes and 3.45 ng/mL for T2D. After stratifying by IRAK-M (<3.76 and ≥3.76 ng/mL), patients with a higher TXNIP level showed a greater risk of prediabetes or T2D in the subgroup with low IRAK-M (<3.76 ng/mL).

CONCLUSIONS

IRAK-M is independently and positively associated with prediabetes and T2D, while TXNIP is independently and negatively associated with prediabetes and T2D. IRAK-M and TXNIP serve as diagnostic factors for prediabetes.

Nanovesicles From Lactobacillus johnsonii N6.2 Reduce Apoptosis in Human Beta Cells by Promoting AHR Translocation and IL10 Secretion

L. johnsonii N6.2 releases nano-sized vesicles (NVs) with distinct protein and lipid contents. We hypothesized that these NVs play a central role in the delivery of bioactive molecules that may act as mechanistic effectors in immune modulation. In this report, we observed that addition of NVs to the human pancreatic cell line βlox5 reduced cytokine-induced apoptosis. Through RNAseq analyses, increased expression of CYP1A1, CYP1B1, AHRR, and TIPARP genes in the aryl hydrocarbon receptor (AHR) pathways were found to be significantly induced in presence of NVs. AHR nuclear translocation was confirmed by confocal microscopy. The role of NVs on beta cell function was further evaluated using primary human pancreatic islets. It was found that NVs significantly increased insulin secretion in presence of high glucose concentrations. These increases positively correlated with increased GLUT6 and SREBF1 mRNA and coincided with reduced oxidative stress markers. Furthermore, incubation of NVs with THP-1 macrophages promoted the M2 tolerogenic phenotype through STAT3 activation, expression of AHR-dependent genes and secretion of IL10. Altogether, our findings indicate that bacterial NVs have the potential to modulate glucose homeostasis in the host by directly affecting insulin secretion by islets and through the induction of a tolerogenic immune phenotype.

Role of NLRP3 Inflammasome in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by multi-articular, symmetrical and invasive arthritis resulting from immune system abnormalities involving T and B lymphocytes. Although significant progress has been made in the understanding of RA pathogenesis, the underlying mechanisms are not fully understood. Recent studies suggest that NLRP3 inflammasome, a regulator of inflammation, might play an important role in the development of RA. There have been increasing clinical and pre-clinical evidence showing the treatment of NLRP3/IL-1β in inflammatory diseases. To provide a foundation for the development of therapeutic strategies, we will briefly summarize the roles of NLRP3 inflammasome in RA and explore its potential clinical treatment.

Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.

Pyroptosis and inflammasomes in diabetic wound healing

Diabetic wound is one of the complications of diabetes and is not easy to heal. It often evolves into chronic ulcers, and severe patients will face amputation. Compared with normal wounds, diabetic wounds have an increased proportion of pro-inflammatory cytokines that are detrimental to the normal healing response. The burden of this disease on patients and healthcare providers is overwhelming, and practical solutions for managing and treating diabetic wounds are urgently needed. Pyroptosis, an inflammatory type of programmed cell death, is usually triggered by the inflammasome. The pyroptosis-driven cell death process is primarily mediated by the traditional signaling pathway caused by caspase -1 and the non-classical signaling pathways induced by caspase -4/5/11. Growing evidence that pyroptosis promotes diabetic complications, including diabetic wounds. In addition, inflammation is thought to be detrimental to wound healing. It is worth noting that the activation of the NLRP3 inflammasome plays a crucial role in the recovery of diabetic wounds. This review has described the mechanisms of pyroptosis-related signaling pathways and their impact on diabetic wounds. It has discussed new theories and approaches to promote diabetic wound healing, as well as some potential compounds targeting pyroptosis and inflammasome signaling pathways that could be new approaches to treating diabetic wounds.

NLRP3 Inflammasome: Checkpoint Connecting Innate and Adaptive Immunity in Autoimmune Diseases

Autoimmune diseases are a broad spectrum of human diseases that are characterized by the breakdown of immune tolerance and the production of autoantibodies. Recently, dysfunction of innate and adaptive immunity is considered to be a key step in the initiation and maintenance of autoimmune diseases. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a multimeric protein complex, which can detect exogenous pathogen irritants and endogenous danger signals. The main function of NLRP3 inflammasome is to promote secretion of interleukin (IL)-1β and IL-18, and pyroptosis mediated by caspase-1. Served as a checkpoint in innate and adaptive immunity, aberrant activation and regulation of NLRP3 inflammasome plays an important role in the pathogenesis of autoimmune diseases. This paper reviewed the roles of NLRP3 inflammasome in autoimmune diseases, which shows NLRP3 inflammasome may be a potential target for autoimmune diseases deserved further study.

The NLRP3 Inflammasome in the Pathogenesis and Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia. Although AD is one of the most socioeconomically devastating diseases confronting humanity, no "curative" disease modifying drug has been identified. Recent decades have witnessed repeated failures of drug trials and have called into question the utility of the amyloid hypothesis approach to AD therapeutics design. Accordingly, new neurochemical processes are being evaluated and explored as sources of alternative druggable targets. Among these newly identified targets, neuroinflammation is emerging as a front-runner, and within the realm of neuroinflammation, the inflammasome, particularly the NLRP3 complex, is garnering focussed attention. This review summarizes current data and approaches to understanding the role of the NLRP3 inflammasome in neuroinflammation and AD, and systematically identifies and evaluates multiple targets within the NLRP3 inflammasome cascade as putative drug targets.

Inflammasomes and Type 1 Diabetes

Microbiota have been identified as an important modulator of susceptibility in the development of Type 1 diabetes in both animal models and humans. Collectively these studies highlight the association of the microbiota composition with genetic risk, islet autoantibody development and modulation of the immune responses. However, the signaling pathways involved in mediating these changes are less well investigated, particularly in humans. Importantly, understanding the activation of signaling pathways in response to microbial stimulation is vital to enable further development of immunotherapeutics, which may enable enhanced tolerance to the microbiota or prevent the initiation of the autoimmune process. One such signaling pathway that has been poorly studied in the context of Type 1 diabetes is the role of the inflammasomes, which are multiprotein complexes that can initiate immune responses following detection of their microbial ligands. In this review, we discuss the roles of the inflammasomes in modulating Type 1 diabetes susceptibility, from genetic associations to the priming and activation of the inflammasomes. In addition, we also summarize the available inhibitors for therapeutically targeting the inflammasomes, which may be of future use in Type 1 diabetes.

Identification of hub genes related to the progression of type 1 diabetes by computational analysis

BACKGROUND

Type 1 diabetes (T1D) is a serious threat to childhood life and has fairly complicated pathogenesis. Profound attempts have been made to enlighten the pathogenesis, but the molecular mechanisms of T1D are still not well known.

METHODS

To identify the candidate genes in the progression of T1D, expression profiling by high throughput sequencing dataset GSE123658 was downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified, and gene ontology (GO) and pathway enrichment analyses were performed. The protein-protein interaction network (PPI), modules, target gene - miRNA regulatory network and target gene - TF regulatory network analysis were constructed and analyzed using HIPPIE, miRNet, NetworkAnalyst and Cytoscape. Finally, validation of hub genes was conducted by using ROC (Receiver operating characteristic) curve and RT-PCR analysis. A molecular docking study was performed.

RESULTS

A total of 284 DEGs were identified, consisting of 142 up regulated genes and 142 down regulated genes. The gene ontology (GO) and pathways of the DEGs include cell-cell signaling, vesicle fusion, plasma membrane, signaling receptor activity, lipid binding, signaling by GPCR and innate immune system. Four hub genes were identified and biological process analysis revealed that these genes were mainly enriched in cell-cell signaling, cytokine signaling in immune system, signaling by GPCR and innate immune system. ROC curve and RT-PCR analysis showed that EGFR, GRIN2B, GJA1, CAP2, MIF, POLR2A, PRKACA, GABARAP, TLN1 and PXN might be involved in the advancement of T1D. Molecular docking studies showed high docking score.

CONCLUSIONS

DEGs and hub genes identified in the present investigation help us understand the molecular mechanisms underlying the advancement of T1D, and provide candidate targets for diagnosis and treatment of T1D.

Inflammasomes and adaptive immune responses

A fundamental concept in immunology is that the innate immune system initiates or instructs downstream adaptive immune responses. Inflammasomes are central players in innate immunity to pathogens, but how inflammasomes shape adaptive immunity is complex and relatively poorly understood. Here we highlight recent work on the interplay between inflammasomes and adaptive immunity. We address how inflammasome-dependent release of cytokines and antigen activates, shapes or even inhibits adaptive immune responses. We consider how distinct tissue or cellular contexts may alter the effects of inflammasome activation on adaptive immunity and how this contributes to beneficial or detrimental outcomes in infectious diseases, cancer and autoimmunity. We aspire to provide a framework for thinking about inflammasomes and their connection to the adaptive immune response.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic β-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1β protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1β secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

Lipid deposition and metaflammation in diabetic kidney disease

A critical link between metabolic disorders and a form of low-grade systemic and chronic inflammation has been recently established and named 'Metaflammation'. Metaflammation has been recognized as a key mediator of both microvascular and macrovascular complications of diabetes and as a significant contributor to the development of diabetic kidney disease (DKD). The goal of this review is to summarize the contribution of diabetes-induced inflammation and the related signaling pathways to diabetic complications, with a particular focus on how innate immunity and lipid metabolism influence each other.

NLRP3 Inflammasome: The Stormy Link Between Obesity and COVID-19

Several countries around the world have faced an important obesity challenge for the past four decades as the result of an obesogenic environment. This disease has a multifactorial origin and it is associated with multiple comorbidities including type 2 diabetes, hypertension, osteoarthritis, metabolic syndrome, cancer, and dyslipidemia. With regard to dyslipidemia, hypertriglyceridemia is a well-known activator of the NLRP3 inflammasome, triggering adipokines and cytokines secretion which in addition induce a systemic inflammatory state that provides an adequate scenario for infections, particularly those mediated by viruses such as HIV, H1N1 influenza, and SARS-CoV-2. The SARS-CoV-2 infection causes the coronavirus disease 2019 (COVID-19) and it is responsible for the pandemic that we are currently living. COVID-19 causes an aggressive immune response known as cytokine release syndrome or cytokine storm that causes multiorgan failure and in most cases leads to death. In the present work, we aimed to review the molecular mechanisms by which obesity-associated systemic inflammation could cause a more severe clinical presentation of COVID-19. The SARS-CoV-2 infection could potentiate or accelerate the pre-existing systemic inflammatory state of individuals with obesity, via the NLRP3 inflammasome activation and the release of pro-inflammatory cytokines from cells trough Gasdermin-pores commonly found in cell death by pyroptosis.

The NLRP3 Inflammasome and Its Role in T1DM

The NLRP3 (nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3) inflammasome is a protein complex expressed in cells. It detects danger signals and induces the production of active caspase-1 and the maturation and release of IL (interleukin)-33, IL-18, IL-1β and other cytokines. T1DM (type 1 diabetes mellitus) is defined as a chronic autoimmune disorder characterized by the autoreactive T cell-mediated elimination of insulin-positive pancreatic beta-cells. Although the exact underlying mechanisms are obscure, researchers have proposed that both environmental and genetic factors are involved in the pathogenesis of T1DM. Furthermore, immune responses, including innate and adaptive immunity, play an important role in this process. Recently, the NLRP3 inflammasome, a critical component of innate immunity, was reported to be associated with T1DM. Here, we review the assembly and function of the NLRP3 inflammasome. In addition, the activation and regulatory mechanisms that enhance or attenuate NLRP3 inflammasome activation are discussed. Finally, we focus on the relationship between the NLRP3 inflammasome and T1DM, as well as its potential value for clinical use.

[Expression of NLRP1 inflammasomes in myocardial tissue of diabetic rats]

OBJECTIVE

To observe the expression of NLRP1 inflammasomes in myocardial tissues in rats with a high-fat and highsugar diet and in diabetic rats analyze the role of NLRP1 inflammasomes in the pathogenesis of diabetic cardiomyopathy.

METHODS

Male SD rats were divided into normal control group, high-sugar and high-fat diet (HC) group and diabetes group. Rat models of diabetes were established by intraperitoneal injection of streptozotocin (STZ; 30 mg/kg). Serum levels of cholesterol (TC), triglyceride (TG), and fasting insulin (FINS) were measured after 8 weeks of feeding, and the insulin resistance index (IRI) and insulin sensitivity index (ISI) were calculated; Echocardiographic evaluation of cardiac structure and function was performed, and Western blotting and real-time fluorescent quantitative PCR (RT-qRCP) were used to detect the protein and mRNA expressions of NLRP1, ASC, and caspase 1 in the myocardial tissue.

RESULTS

Compared with the control rats, the rats in the HC group had significantly increased body weight (BW), serum levels of TG and TC, mRNA expressions of NLRP1 and caspase 1, and the protein expression of NLRP1 (P < 0.01) without significant changes in FINS, IRI, ISI, or cardiac ultrasound findings (P > 0.05) or in myocardial ASC and caspase 1 protein expressions or serum levels of IL-1β and IL-18 (P > 0.05). In the diabetic rats, TC, TG, and FBG levels increased and FINS, ISI decreased significantly (P < 0.01); the left ventricular end-diastolic diameter (LVID) and the left ventricular end-systolic diameter (LVSD) increased while the ejection fraction (LVEF), short axis shortening rate (FS), and E/A ratio all decreased. The expressions of NLRP1/ASC/caspase 1 pathway mRNA and NLRP1 and caspase 1 proteins also increased but myocardium ASC protein expression did not show significant changes in the diabetic rats (P > 0.05). IL-1β and IL-18 levels were also significantly higher in the diabetic rats than in the control group (P < 0.05). Compared with those in HC group, the diabetic rats showed significantly increased serum FBG and decreased FINS, ISI and BW (P < 0.01) with decreased LVSD, LVEF and E/A ratio and increased levels of NLRP1 and caspase 1 protein expressions and serum L-1β and IL-18 levels (P < 0.01).

CONCLUSIONS

Diabetes can cause abnormal changes in cardiac structure and functions and induce inflammatory response in the myocardium, which may be related to the activation of NLRP1/ASC/ caspase 1 inflammasomes.

Omeprazole attenuates cisplatin-induced kidney injury through suppression of the TLR4/NF-κB/NLRP3 signaling pathway

Renal toxicity is the primary factor that limits clinical use of cisplatin (CP). A previous study showed that omeprazole (OME) protected against CP-induced toxicity in human renal tubular HK-2 cells and rat kidneys. However, the protective mechanisms of OME have not been characterized. We evaluated the ability of OME to inhibit CP-induced inflammation, and characterized the pathways responsible for this effect. Rats were randomly divided into five groups (n = 10/group). The OME groups were intraperitoneally injected with 1.8 or 3.6 mg OME /kg body weight once daily for 5 days. One hour after final administration of vehicle or OME, all rats (except those in control group and OME alone group) were intraperitoneally injected with 15 mg/kg CP. Twenty-four hours after CP injection, the surgery was applied. The time points and dosing of OME and CP were calculated based on previous studies and the therapeutic dose for patients. Omeprazole attenuated CP-induced apoptosis and damage in vivo and in vitro, as evidenced by increased cell viability and prevention of structural damage. Omeprazole ameliorated CP-induced renal injury through inhibition of NF-κB activation and IκBα degradation, and down-regulation of toll-like receptor 4 (TLR4) and Nod-like receptor protein 3 (NLRP3). Lipopolysaccharide, a TLR4 agonist, was used to verify this mechanism. The results indicated that OME inhibited CP-induced expression of inflammatory proteins, and this effect was blunted by co-treatment with LPS in HK-2 cells. These findings suggested that the protective effects of OME against CP-induced kidney damage may occur through inhibition of the TLR4/NF-κB/NLRP3 signaling pathway. This study provided evidence that OME may be a promising agent to inhibit CP-induced nephrotoxicity.

To protect or adversely affect? The dichotomous role of the NLRP1 inflammasome in human disease

NLRP1 is an inflammasome forming pattern recognition receptor (PRR). When activated by pathogen- and damage- associated molecular patterns (PAMPS/DAMPS), NLRP1 inflammasome formation leads to inflammation through the production of proinflammatory cytokines IL-18 and IL-1β. As with other inflammasome forming NLR family members, NLRP1 also regulates cell death processes, termed pyroptosis. The domain structure of NLRP1 differs between mice and humans, making it possible for the function of the inflammasome to differ between species and adds complexity to the study of this NLR family member. In humans, mutations in both coding and non-coding regions of the NLRP1 gene are linked to a variety of diseases. Likewise, interruption of NLRP1 inhibitors or changes in the prevalence of NLRP1 activators can also impact disease pathobiology. Adding to its complexity, the NLRP1 inflammasome plays a dichotomous role in human diseases, functioning to either attenuate or augment miscellaneous biological processes in a tissue specific manner. For example, NLRP1 plays a protective role in the gastrointestinal tract by modulating the microbiome composition; however, it augments neurological disorders, cardio-pulmonary diseases, and cancer through promoting inflammation. Thus, it is critical that the role of NLRP1 in each of these disease processes be robustly defined. In this review, we summarize the current research landscape to provide a better understanding of the mechanisms associated with NLRP1 function and dysfunction in human disease pathobiology. We propose that a better understanding of these mechanisms will ultimately result in improved insight into immune system dysfunction and therapeutic strategies targeting inflammasome function in multiple human diseases.

Attenuation of inflammation in streptozotocin-induced diabetic rabbits by Matricaria chamomilla oil: A focus on targeting NF-κB and NLRP3 signaling pathways

Objectives

The present study was conducted to investigate the protective effects of chamomile oil from Matricaria chamomilla against type 1 diabetes mellitus (T1DM) and its potential mechanisms.

Methods

T1DM was established in male New Zealand white rabbits via a single intraperitoneal infusion of streptozotocin (STZ) (80 mg/kg body weight⁻¹, dissolved in 0.2 mL of normal saline). Different doses of chamomile oil (25, 50 and 100 mg/kg) were orally administrated to STZ induced diabetic rabbits for 21 consecutive days. The expression of pro-inflammatory cytokines was determined using ELISA assay. The expression of NF-κB and NLRP3 was measured using Western blot assay.

Results

Compared with normal rabbits, STZ-induced diabetic rabbits exhibited significant increased levels of blood glucose and decreased levels of serum insulin that were reversed using middle and high tested dose of chamomile oil. Likewise, STZ-induced diabetic rabbits showed a significant increased expression of NF-κB and NLRP3 proteins in the pancreas tissue that was reversed by high tested dose of chamomile oil.

Conclusion

Collectively, our findings demonstrated that chamomile oil possesses anti-hyperglycemic, and anti-inflammatory activities in STZ-induced diabetic rabbits by targeting inflammatory cytokines and NF-κB and NLRP3 signaling pathways.

Modulatory Mechanisms of the NLRP3 Inflammasomes in Diabetes

The inflammasome is a multiprotein complex that acts to enhance inflammatory responses by promoting the production and secretion of key cytokines. The best-known inflammasome is the NLRP3 (nucleotide-binding oligomerization domain-like receptor [NLR] family pyrin domain-containing 3) inflammasome. The evidence has shown that the NLRP3 inflammasome, IL-1β, thioredoxin-interacting protein (TXNIP), and pyroptosis play vital roles in the development of diabetes. This review summarizes the regulation of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) by NLRP3 via modulation of glucose tolerance, insulin resistance, inflammation, and apoptosis mediated by endoplasmic reticulum stress in adipose tissue. Moreover, NLRP3 participates in intestinal homeostasis and inflammatory conditions, and NLRP3-deficient mice experience intestinal lesions. The diversity of an individual's gut microbiome and the resultant microbial metabolites determines the extent of their involvement in the physiological and pathological mechanisms within the gut. As such, further study of the interaction between the NLRP3 inflammasome and the complex intestinal environment in disease development is warranted to discover novel therapies for the treatment of diabetes.

Metabolic regulation of inflammasomes in inflammation

Inflammasome activation and subsequent inflammatory cytokine secretion are essential for innate immune defence against multiple stimuli and are regarded as a link to adaptive immune responses. Dysfunction of inflammasome activation has been discovered at the onset or progression of infectious diseases, autoimmune diseases and cancer, all of which are also associated with metabolic factors. Furthermore, many studies concerning the metabolic regulation of inflammasome activation have emerged in recent years, especially regarding the activity of the NLRP3 inflammasome under metabolic reprogramming. In this review, we discuss the molecular mechanisms of the interactions between metabolic pathways and inflammasome activation, which exerts further important effects on various diseases.

NLRP1 promotes TGF-β1-induced myofibroblast differentiation in neonatal rat cardiac fibroblasts

Nuclear localization leucine-rich-repeat protein 1 (NLRP1) is a member of Nod-like receptors (NLRs) family. Recent studies have reported that NLRP1 is involved in various diseases, especially in cardiovascular diseases. However, the effect of NLRP1 on cardiac fibrosis remains unclear. In this study, NLRP1 overexpression and NLRP1 silencing constructs were transfected into neonatal rat cardiac fibroblasts induced by TGF-β1 for 48 h to investigate the effect of NLRP1 in cardiac fibrosis and its molecular mechanisms. Cardiac fibroblasts were transfected with NLRP1 and then cultured in the presence and absence of TGF-β1and Smad3 inhibitor (SIS3). Our data indicated that NLRP1 not only promoted fibroblast activation and myofibroblast differentiation, but also upregulated the mRNA and protein levels of α-SMA in the TGF-β1-treated neonatal rat cardiac fibroblasts. Overexpressing NLRP1 in TGF-β1-induced cardiac fibroblasts upregulated the mRNA and protein levels of Collagen I, Collagen III, and connective tissue growth factor. Moreover, NLRP1 upregulated the protein levels of Smad2, Smad3, and Smad4 in nuclei of fibroblasts, and attenuated levels of phosphorylated Smad2 and Smad3 in the cytoplasm of fibroblasts induced by TGF-β1. In addition, the increase in fibrotic genes and Smad proteins was significantly reduced in the presence of SIS3. Our findings illustrated that NLRP1 promoted myofibroblast differentiation and excessive ECM production in TGF-β1-induced neonatal cardiac fibroblasts through directly targeting TGF-β1/Smad signaling pathways.