Inflammasome is a central player in B cell development and homing

The NLRP3 Inflammasome in inflammatory diseases: Cellular dynamics and role in granuloma formation

The innate immune system recognizes pathogen-associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) through pattern recognition receptors (PRRs). Inflammasomes, cytoplasmic protein complexes, are activated in response to PAMPs and DAMPs, leading to the release of inflammatory cytokines such as IL-1β and IL-18. NLRP3 inflammasome is one of the best characterized inflammasomes and recently its activation has been associated with granuloma formation, structures that aggregate immune cells in response to infections, such as those caused by bacteria, fungi and parasites, and autoinflammatory diseases, such as sarcoidosis. Activation of NLRP3 inflammasomes in macrophages induces the release of cytokines that recruit immune cells, such as monocytes and lymphocytes, to the site of infection. Neutrophils, monocytes, T and B lymphocytes are important in the formation and maintenance of granulomas. Although NLRP3 plays a key role in the immune response, cell recruitment and granuloma formation, many aspects of its function in different cell types remain to be elucidated. In this review, we aim to outline the NLRP3 inflammasome not only as a protein complex that aids innate immune cells in combating intracellular pathogens but also as a platform with broader implications in orchestrating immune responses. This underexplored aspect of the NLRP3 inflammasome presents a novel perspective on its involvement in immunity. Thus, we review the current understanding of the role of the NLRP3 inflammasome in immune cell infiltration and its significance in the organization and formation of granulomas in inflammatory diseases.

Inflammasomes and autophagy in cancer: unlocking targeted therapies

This study clarifies the interaction between autophagy and inflammasome within the cancer framework. The inflammasome generates pro-inflammatory cytokines to direct the immune response to pathogens and cellular stressors. Autophagy maintains cellular homeostasis and can either promote or inhibit cancer. These pathways interact to affect tumorigenesis, immune responses, and therapy. Autophagy controls inflammasome activity by affecting cancer pathogenesis and tumor microenvironment inflammation, highlighting novel cancer therapeutic approaches. Recent studies indicate that modulating autophagy and inflammasome pathways can boost anti-cancer immunity, reduce drug-resistance, and improve therapeutic efficacy. Recent studies indicate modulating inflammasome and autophagy pathways can augment anti-cancer immunity, mitigate therapy resistance, and improve treatment efficacy. Cancer research relies on understanding the inflammasome-autophagy relationship to develop targeted therapies that enhance anti-tumor efficacy and reduce inflammatory symptoms. Customized therapies may improve outcomes based on autophagy gene variations and inflammasome polymorphisms. This study investigates autophagy pathways and the inflammasome in tumor immunopathogenesis, cytokine function, and cancer therapeutic strategies, highlighting their significance in cancer biology and treatment.

The entrenchment of NLRP3 inflammasomes in autoimmune disease-related inflammation

Autoinflammation and autoimmunity are almost "opposite" phenomena characterized by chronic activation of the immune system, 'innate' in the first and 'adaptive' in the second, leading to inflammation of several tissues with specific protean effectors of tissue damage. The mechanism of involvement of multiprotein complexes called 'inflammasomes' within autoimmune pictures, differently from autoinflammatory conditions, is yet undeciphered. In this review we provide a comprehensive overview on NLRP3 inflammasome contribution into the pathogenesis of some autoimmune diseases. In response to autoantibodies against nucleic acids or tissue-specific antigens the NLRP3 inflammasome is activated within dendritic cells and macrophages of patients with systemic lupus erythematosus. Crucial is NLRP3 inflammasome to amplify tissue inflammation with interleukin-1 overexpression and matrix metalloproteinase production at the joint level in rheumatoid arthritis. A deregulated NLRP3 inflammasome activation occurs in the serous acini of salivary and lacrimal glands prone to Sjogren's syndrome, but also in the inflammatory process involving endothelial cells, leucocyte recruitment, and platelet plugging of vasculitides. Furthermore, organ-specific autoimmune diseases such as thyroiditis and hepatitis may display hyperactive NLRP3 inflammasomes at the level of resident immune cells within thyroid or liver, respectively. Therefore, it is not unexpected that preclinical studies have shown how specific inflammasome inhibitors may significantly overthrow the severity of different autoimmune diseases and slow down their trend towards an ominous progression. Specific markers of inflammasome activation could also reveal subclinical inflammatory components escaping conventional diagnostic approaches or improve monitoring of autoimmune diseases and personalizing their treatment.

Swaying the advantage: multifaceted functions of inflammasomes in adaptive immunity

Eukaryotic cells are equipped with cytoplasmic sensors that recognize diverse pathogen- or danger-associated molecular patterns. In cells of the myeloid lineage, activation of these sensors leads to the assembly of a multimeric protein complex, called the inflammasome, that culminates in the production of inflammatory cytokines and pyroptosis. Recently, investigation of the inflammasomes in lymphocytes led to the discovery of functional pathways that were initially believed to be confined to the innate arm of the immune system. Thus, the adapter protein apoptosis-associated speck-like protein containing a CARD (ASC) was documented to play a critical role in antigen uptake by dendritic cells, and regulation of T- and B-cell motility at several stages, and absent in melanoma 2 (AIM2) was found to act as a modulator of regulatory T-cell differentiation. Remarkably, NLRP3 was demonstrated to act as a transcription factor that controls Th2 cell polarization, and as a negative regulator of regulatory T-cell differentiation by limiting Foxp3 expression. In B lymphocytes, NLRP3 plays a role in the transcriptional network that regulates B-cell development and homing, and its activation is essential for germinal center formation and maturation of high-affinity antibody responses. Such recently discovered inflammasome-mediated functions in T and B lymphocytes offer multiple cross-talk opportunities for the innate and adaptive arms of the immune system. A better understanding of the dialog between inflammasomes and intracellular components could be beneficial for therapeutic purposes in restoring immune homeostasis and mitigating inflammation in a wide range of disorders.

Inflammasome activation in melanoma progression: the latest update concerning pathological role and therapeutic value

The progression of melanoma is a complex process influenced by both internal and external cues which encourage the transition of tumour cells, uncontrolled growth, migration, and metastasis. Additionally, inflammation allows tumours to evade the immune system, contributing to cancer development. The inflammasome, a complex of many proteins, is crucial in enhancing immune responses to external and internal triggers. As a critical inflammatory mechanism, it contributes to the development of melanoma. These mechanisms may be triggered via various internal and external stimuli, causing the induction of specific enzymes such as caspase-1, caspase-11, or caspase-8. This, in turn, leads to the release of interleukin (IL)-1β and IL-18 and cell death by apoptosis and pyroptosis. Proper inflammasome stimulation is crucial for the host to deal with invading pathogens or tissue injury. However, inappropriate inflammasome stimulation can result in unregulated tissue reactions, thus easing many diseases, including melanoma. Hence, keeping a delicate equilibrium between the stimulation and prohibition of inflammasomes is crucial, necessitating meticulous control of the assembly and functional aspects of inflammasomes. This review examines the latest advancements in inflammasome studies, specifically focusing on the molecular processes that control inflammasome formation, signalling, and modulation in melanoma.

Unraveling the NLRP family: Structure, function, activation, critical influence on tumor progression, and potential as targets for cancer therapy

The innate immune system serves as the body's initial defense, swiftly detecting danger via pattern recognition receptors (PRRs). Among these, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing proteins (NLRPs) are pivotal in recognizing pathogen-associated and damage-associated molecular patterns, thereby triggering immune responses. NLRPs, the most extensively studied subset within the NLR family, form inflammasomes that regulate inflammation, essential for innate immunity activation. Recent research highlights NLRPs' significant impact on various human diseases, including cancer. With differential expression across organs, NLRPs influence cancer progression by modulating immune reactions, cell fate, and proliferation. Their clinical significance in cancer makes them promising therapeutic targets. This review provides a comprehensive overview of the structure, function, activation mechanism of the NLRPs family and its potential role in cancer progression. In addition, we particularly focused on the concept of NLRP as a therapeutic target and its potential value in combination with immune checkpoint inhibitors.

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.

Unraveling the Role of the NLRP3 Inflammasome in Lymphoma: Implications in Pathogenesis and Therapeutic Strategies

Inflammasomes are multimeric protein complexes, sensors of intracellular danger signals, and crucial components of the innate immune system, with the NLRP3 inflammasome being the best characterized among them. The increasing scientific interest in the mechanisms interconnecting inflammation and tumorigenesis has led to the study of the NLRP3 inflammasome in the setting of various neoplasms. Despite a plethora of data regarding solid tumors, NLRP3 inflammasome's implication in the pathogenesis of hematological malignancies only recently gained attention. In this review, we investigate its role in normal lymphopoiesis and lymphomagenesis. Considering that lymphomas comprise a heterogeneous group of hematologic neoplasms, both tumor-promoting and tumor-suppressing properties were attributed to the NLRP3 inflammasome, affecting neoplastic cells and immune cells in the tumor microenvironment. NLRP3 inflammasome-related proteins were associated with disease characteristics, response to treatment, and prognosis. Few studies assess the efficacy of NLRP3 inflammasome therapeutic targeting with encouraging results, though most are still at the preclinical level. Further understanding of the mechanisms regulating NLRP3 inflammasome activation during lymphoma development and progression can contribute to the investigation of novel treatment approaches to cover unmet needs in lymphoma therapeutics.

Crosstalk of NLRP3 inflammasome and noncoding RNAs in cardiomyopathies

Cardiovascular diseases (CVDs) identified as a serious public health problem. Although there is a lot of evidence that inflammatory processes play a significant role in the progression of CVDs, however, the precise mechanism is not fully understood. Nevertheless, recent studies have focused on inflammation and its related agents. Nucleotide oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) is a type of pattern recognition receptor (PRR) that can recognize pathogen-associated molecular patterns and trigger innate immune response. NLRP3 is a component of the NOD-like receptor (NLR) family and have a pivotal role in detecting damage to cardiovascular tissue. It is suggested that activation of NLRP3 inflammasome leads to initiating and propagating the inflammatory response in cardiomyopathy. So, late investigations have highlighted the NLRP3 inflammasome activation in various forms of cardiomyopathy. On the other side, it was shown that noncoding RNAs (ncRNAs), particularly, microRNAs, lncRNAs, and circRNAs possess a regulatory function in the immune system's inflammatory response, implicating their involvement in various inflammatory disorders. In addition, their role in different cardiomyopathies was indicated in recent studies. This review article provides a summary of recent advancements focusing on the function of the NLRP3 inflammasome in common CVDs, especially cardiomyopathy, while also discussing the therapeutic potential of inhibiting the NLRP3 inflammasome regulated by ncRNAs.

Implications of combined NOD2 and other gene mutations in autoinflammatory diseases

NOD-like receptors (NLRs) are intracellular sensors associated with systemic autoinflammatory diseases (SAIDs). We investigated the largest monocentric cohort of patients with adult-onset SAIDs for coinheritance of low frequency and rare mutations in NOD2 and other autoinflammatory genes. Sixty-three patients underwent molecular testing for SAID gene panels after extensive clinical workups. Whole exome sequencing data from the large Atherosclerosis Risk in Communities (ARIC) study of individuals of European-American ancestry were used as control. Of 63 patients, 44 (69.8%) were found to carry combined gene variants in NOD2 and another gene (Group 1), and 19 (30.2%) were carriers only for NOD2 variants (Group 2). The genetic variant combinations in SAID patients were digenic in 66% (NOD2/MEFV, NOD2/NLRP12, NOD2/NLRP3, and NOD2/TNFRSF1A) and oligogenic in 34% of cases. These variant combinations were either absent or significantly less frequent in the control population. By phenotype-genotype correlation, approximately 40% of patients met diagnostic criteria for a specific SAID, and 60% had mixed diagnoses. There were no statistically significant differences in clinical manifestations between the two patient groups except for chest pain. Due to overlapping phenotypes and mixed genotypes, we have suggested a new term, "Mixed NLR-associated Autoinflammatory Disease ", to describe this disease scenario. Gene variant combinations are significant in patients with SAIDs primarily presenting with mixed clinical phenotypes. Our data support the proposition that immunological disease expression is modified by genetic background and environmental exposure. We provide a preliminary framework in diagnosis, management, and interpretation of the clinical scenario.

Inflammasome: structure, biological functions, and therapeutic targets

Inflammasomes are a group of protein complex located in cytoplasm and assemble in response to a wide variety of pathogen-associated molecule patterns, damage-associated molecule patterns, and cellular stress. Generally, the activation of inflammasomes will lead to maturation of proinflammatory cytokines and pyroptotic cell death, both associated with inflammatory cascade amplification. A sensor protein, an adaptor, and a procaspase protein interact through their functional domains and compose one subunit of inflammasome complex. Under physiological conditions, inflammasome functions against pathogen infection and endogenous dangers including mtROS, mtDNA, and so on, while dysregulation of its activation can lead to unwanted results. In recent years, advances have been made to clarify the mechanisms of inflammasome activation, the structural details of them and their functions (negative/positive) in multiple disease models in both animal models and human. The wide range of the stimuli makes the function of inflammasome diverse and complex. Here, we review the structure, biological functions, and therapeutic targets of inflammasomes, while highlight NLRP3, NLRC4, and AIM2 inflammasomes, which are the most well studied. In conclusion, this review focuses on the activation process, biological functions, and structure of the most well-studied inflammasomes, summarizing and predicting approaches for disease treatment and prevention with inflammasome as a target. We aim to provide fresh insight into new solutions to the challenges in this field.

NLRP3 Inflammasome as a Potentially New Therapeutic Target of Mesenchymal Stem Cells and Their Exosomes in the Treatment of Inflammatory Eye Diseases

Due to their potent immunoregulatory and angio-modulatory properties, mesenchymal stem cells (MSCs) and their exosomes (MSC-Exos) have emerged as potential game-changers in regenerative ophthalmology, particularly for the personalized treatment of inflammatory diseases. MSCs suppress detrimental immune responses in the eyes and alleviate ongoing inflammation in ocular tissues by modulating the phenotype and function of all immune cells that play pathogenic roles in the development and progression of inflammatory eye diseases. MSC-Exos, due to their nano-sized dimension and lipid envelope, easily bypass all barriers in the eyes and deliver MSC-sourced bioactive compounds directly to target cells. Although MSCs and their exosomes offer a novel approach to treating immune cell-driven eye diseases, further research is needed to optimize their therapeutic efficacy. A significant number of experimental studies is currently focused on the delineation of intracellular targets, which crucially contribute to the immunosuppressive and anti-inflammatory effects of MSCs and MSC-Exos. The activation of NLRP3 inflammasome induces programmed cell death of epithelial cells, induces the generation of inflammatory phenotypes in eye-infiltrated immune cells, and enhances the expression of adhesion molecules on ECs facilitating the recruitment of circulating leukocytes in injured and inflamed eyes. In this review article, we summarize current knowledge about signaling pathways that are responsible for NLRP3 inflammasome-driven intraocular inflammation and we emphasize molecular mechanisms that regulate MSC-based modulation of NLRP3-driven signaling in eye-infiltrated immune cells, providing evidence that NLRP3 inflammasome should be considered a potentially new therapeutic target for MSCs and MSC-Exo-based treatment of inflammatory eye diseases.

Cell type-specific roles of NLRP3, inflammasome-dependent and -independent, in host defense, sterile necroinflammation, tissue repair, and fibrosis

The NLRP3 inflammasome transforms a wide variety of infectious and non-infectious danger signals that activate pro-inflammatory caspases, which promote the secretion of IL-1β and IL-18, and pyroptosis, a pro-inflammatory form of cell necrosis. Most published evidence documents the presence and importance of the NLRP3 inflammasome in monocytes, macrophages, and neutrophils during host defense and sterile forms of inflammation. In contrast, in numerous unbiased data sets, NLRP3 inflammasome-related transcripts are absent in non-immune cells. However, an increasing number of studies report the presence and functionality of the NLRP3 inflammasome in almost every cell type. Here, we take a closer look at the reported cell type-specific expression of the NLRP3 inflammasome components, review the reported inflammasome-dependent and -independent functions, and discuss possible explanations for this discrepancy.

B Cells at the Cross-Roads of Autoimmune Diseases and Auto-Inflammatory Syndromes

Whereas autoimmune diseases are mediated primarily by T and B cells, auto-inflammatory syndromes (AIFS) involve natural killer cells, macrophages, mast cells, dendritic cells, different granulocyte subsets and complement components. In contrast to autoimmune diseases, the immune response of patients with AIFS is not associated with a breakdown of immune tolerance to self-antigens. Focusing on B lymphocyte subsets, this article offers a fresh perspective on the multiple cross-talks between both branches of innate and adaptive immunity in mounting coordinated signals that lead to AIFS. By virtue of their potential to play a role in adaptive immunity and to exert innate-like functions, B cells can be involved in both promoting inflammation and mitigating auto-inflammation in disorders that include mevalonate kinase deficiency syndrome, Kawasaki syndrome, inflammatory bone disorders, Schnitzler syndrome, Neuro-Behçet's disease, and neuromyelitis optica spectrum disorder. Since there is a significant overlap between the pathogenic trajectories that culminate in autoimmune diseases, or AIFS, a more detailed understanding of their respective roles in the development of inflammation could lead to designing novel therapeutic avenues.