A Dectin-1-Caspase-8 Pathway Licenses Canonical Caspase-1 Inflammasome Activation and Interleukin-1β Release in Response to a Pathogenic Fungus

Unveiling the hidden players: exploring the role of gut mycobiome in cancer development and treatment dynamics

The role of gut fungal species in tumor-related processes remains largely unexplored, with most studies still focusing on fungal infections. This review examines the accumulating evidence suggesting the involvement of commensal and pathogenic fungi in cancer biological process, including oncogenesis, progression, and treatment response. Mechanisms explored include fungal influence on host immunity, secretion of bioactive toxins/metabolites, interaction with bacterial commensals, and migration to other tissues in certain types of cancers. Attempts to utilize fungal molecular signatures for cancer diagnosis and fungal-derived products for treatment are discussed. A few studies highlight fungi's impact on the responsiveness and sensitivity to chemotherapy, radiotherapy, immunotherapy, and fecal microbiota transplant. Given the limited understanding and techniques in fungal research, the studies on gut fungi are still facing great challenges, despite having great potentials.

INPP5D regulates inflammasome activation in human microglia

Microglia and neuroinflammation play an important role in the development and progression of Alzheimer's disease (AD). Inositol polyphosphate-5-phosphatase D (INPP5D/SHIP1) is a myeloid-expressed gene genetically-associated with AD. Through unbiased analyses of RNA and protein profiles in INPP5D-disrupted iPSC-derived human microglia, we find that reduction in INPP5D activity is associated with molecular profiles consistent with disrupted autophagy and inflammasome activation. These findings are validated through targeted pharmacological experiments which demonstrate that reduced INPP5D activity induces the formation of the NLRP3 inflammasome, cleavage of CASP1, and secretion of IL-1β and IL-18. Further, in-depth analyses of human brain tissue across hundreds of individuals using a multi-analytic approach provides evidence that a reduction in function of INPP5D in microglia results in inflammasome activation in AD. These findings provide insights into the molecular mechanisms underlying microglia-mediated processes in AD and highlight the inflammasome as a potential therapeutic target for modulating INPP5D-mediated vulnerability to AD.

Dectin-2 is critical for phagocyte function and resistance to Paracoccidioides brasiliensis in mice

Germline-encoded pattern recognition receptors, particularly C-type lectin receptors (CLRs), are essential for phagocytes to sense invading fungal cells. Among CLRs, Dectin-2 (encoded by Clec4n) plays a critical role in the antifungal immune response as it recognizes high-mannose polysaccharides on the fungal cell wall, triggering phagocyte functional activities and ultimately determining adaptive responses. Here, we assessed the role of Dectin-2 on the course of primary Paracoccidioides brasiliensis systemic infection in mice with Dectin-2-targeted deletion. Paracoccidioides brasiliensis constitutes the principal etiologic agent of paracoccidioidomycosis, the most prominent invasive mycosis in Latin American countries. The deficiency of Dectin-2 resulted in shortened survival rates, high lung fungal burden, and increased lung pathology in mice infected with P. brasiliensis. Consistently, dendritic cells (DCs) from mice lacking Dectin-2 infected ex vivo with P. brasiliensis showed impaired secretion of several proinflammatory and regulatory cytokines, including TNF-α, IL-1β, IL-6, and IL-10. Additionally, when cocultured with splenic lymphocytes, DCs were less efficient in promoting a type 1 cytokine pattern secretion (i.e., IFN-γ). In macrophages, Dectin-2-mediated signaling was required to ensure phagocytosis and fungicidal activity associated with nitric oxide production. Overall, Dectin-2-mediated signaling is critical to promote host protection against P. brasiliensis infection, and its exploitation might lead to the development of new vaccines and immunotherapeutic approaches.

Immunological protein profiling of first-episode psychosis patients identifies CSF and blood biomarkers correlating with disease severity

BACKGROUND AND HYPOTHESIS

Immune activation is suggested to play an important role in psychosis. In this study, a large number of immune-related proteins were analyzed to obtain a more comprehensive picture of immune aberrations in schizophrenia.

STUDY DESIGN

Ninety-two immune markers were analyzed by the Olink Protein Extension Assay (Inflammatory Panel) in plasma and cerebrospinal fluid (CSF) from 77 first-episode psychosis (FEP) patients (of which 43 later received the diagnosis of schizophrenia) and 56 healthy controls, all recruited from the Karolinska Schizophrenia Project (KaSP), Stockholm, Sweden.

STUDY RESULTS

Differential analysis showed that 12 of 92 inflammatory proteins were significantly higher in the plasma of FEP patients (n = 77) than in controls, and several proteins were positively correlated with disease severity. Patients from the same cohort diagnosed with schizophrenia (n = 43), showed significantly higher levels of 15 plasma proteins compared to controls whereas those not receiving this diagnosis showed no significant differences. The presently used OLINK inflammatory panel allowed the detection of only 47 CSF proteins of which only CD5 differed between patients and controls.

CONCLUSIONS

The levels of several peripheral immune markers, particularly those interfering with WNT/β-catenin signaling, were significantly higher in patients with FEP than in healthy controls and associated with illness severity.

Genome-Wide Association Study Reveals CLEC7A and PROM1 as Potential Regulators of Paracoccidioides brasiliensis-Induction of Cytokine Production in Peripheral Blood Mononuclear Cells

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by fungi of the genus Paracoccidioides and the different clinical forms of the disease are associated with the host immune responses. Quantitative trait loci mapping analysis was performed to assess genetic variants associated with mononuclear-cells-derived cytokines induced by P. brasiliensis on 158 individuals. We identified the rs11053595 SNP, which is present in the CLEC7A gene (encodes the Dectin-1 receptor) and the rs62290169 SNP located in the PROM1 gene (encodes CD133) associated with the production of IL-1β and IL-22, respectively. Functionally, the blockade of the dectin-1 receptor abolished the IL-1β production in P. brasiliensis-stimulated PBMCs. Moreover, the rs62290169-GG genotype was associated with higher frequency of CD38+ Th1 cells in PBMCs cultured with P. brasiliensis yeasts. Therefore, our research indicates that the CLEC7A and PROM1 genes are important for the cytokine response induced by P. brasiliensis and may influence the Paracoccidioidomycosis disease outcome.

Involvement of inflammasomes in tumor microenvironment and tumor therapies

Inflammasomes are macromolecular platforms formed in response to damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns, whose formation would cause maturation of interleukin-1 (IL-1) family members and gasdermin D (GSDMD), leading to IL-1 secretion and pyroptosis respectively. Several kinds of inflammasomes detecting different types of dangers have been found. The activation of inflammasomes is regulated at both transcription and posttranscription levels, which is crucial in protecting the host from infections and sterile insults. Present findings have illustrated that inflammasomes are involved in not only infection but also the pathology of tumors implying an important link between inflammation and tumor development. Generally, inflammasomes participate in tumorigenesis, cell death, metastasis, immune evasion, chemotherapy, target therapy, and radiotherapy. Inflammasome components are upregulated in some tumors, and inflammasomes can be activated in cancer cells and other stromal cells by DAMPs, chemotherapy agents, and radiation. In some cases, inflammasomes inhibit tumor progression by initiating GSDMD-mediated pyroptosis in cancer cells and stimulating IL-1 signal-mediated anti-tumor immunity. However, IL-1 signal recruits immunosuppressive cell subsets in other cases. We discuss the conflicting results and propose some possible explanations. Additionally, we also summarize interventions targeting inflammasome pathways in both preclinical and clinical stages. Interventions targeting inflammasomes are promising for immunotherapy and combination therapy.

INPP5D/SHIP1 regulates inflammasome activation in human microglia

Microglia and neuroinflammation are implicated in the development and progression of Alzheimer's disease (AD). To better understand microglia-mediated processes in AD, we studied the function of INPP5D/SHIP1, a gene linked to AD through GWAS. Immunostaining and single nucleus RNA sequencing confirmed that INPP5D expression in the adult human brain is largely restricted to microglia. Examination of prefrontal cortex across a large cohort revealed reduced full length INPP5D protein levels in AD patient brains compared to cognitively normal controls. The functional consequences of reduced INPP5D activity were evaluated in human induced pluripotent stem cell derived microglia (iMGLs), using both pharmacological inhibition of the phosphatase activity of INPP5D and genetic reduction in copy number. Unbiased transcriptional and proteomic profiling of iMGLs suggested an upregulation of innate immune signaling pathways, lower levels of scavenger receptors, and altered inflammasome signaling with INPP5D reduction. INPP5D inhibition induced the secretion of IL-1ß and IL-18, further implicating inflammasome activation. Inflammasome activation was confirmed through visualization of inflammasome formation through ASC immunostaining in INPP5D-inhibited iMGLs, increased cleaved caspase-1 and through rescue of elevated IL-1ß and IL-18 with caspase-1 and NLRP3 inhibitors. This work implicates INPP5D as a regulator of inflammasome signaling in human microglia.

NLRC4 inhibits NLRP3 inflammasome and abrogates effective antifungal CD8+ T cell responses

The recognition of fungi by intracellular NOD-like receptors (NLRs) induces inflammasome assembly and activation. Although the NLRC4 inflammasome has been extensively studied in bacterial infections, its role during fungal infections is unclear. Paracoccidioidomycosis (PCM) is a pathogenic fungal disease caused by Paracoccidioides brasiliensis. Here, we show that NLRC4 confers susceptibility to experimental PCM by regulating NLRP3-dependent cytokine production and thus protective effector mechanisms. Early after infection, NLRC4 suppresses prostaglandin E₂ production, and consequently reduces interleukin (IL)-1β release by macrophages and dendritic cells in the lungs. IL-1β is required to control fungal replication via induction of the nitric oxide synthase 2 (NOS2) pathway. At a later stage of the disease, NLRC4 impacts IL-18 release, dampening robust CD8⁺IFN-γ⁺ T cell responses and enhancing mortality of mice. These findings demonstrate that NLRC4 promotes disease by regulating the production of inflammatory cytokines and cellular responses that depend on the NLRP3 inflammasome activity.

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NLRC4 promotes susceptibility to a highly pathogenic fungus.

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NLRC4 regulates NLRP3 activity.

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NLRC4 inhibits early NLRP3/IL-1β/NOS2/NO axis and promotes fungal replication.

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NLRC4 dampens late IL-18 production, suppressing CD8⁺IFN-γ⁺ T cell responses.

Inflammasomes in dendritic cells: Friend or foe?

Inflammasomes are cytosolic multiprotein complexes that crucially contribute to host defense against pathogens but are also involved in the pathogenesis of autoinflammatory diseases. Inflammasome formation leads to activation of effector caspases (caspase-1, 4, 5, or 11), the proteolytic maturation of IL-1β and IL-18 as well as cleavage of the pore-forming protein Gasdermin D. Dendritic cells are major regulators of immune responses as they bridge innate and adaptive immunity. We here summarize the current knowledge on inflammasome expression and formation in murine bone marrow-, human monocyte-derived as well as murine and human primary dendritic cells. Further, we discuss both, the beneficial and detrimental, involvement of inflammasome activation in dendritic cells in cancer, infections, and autoimmune diseases. As inflammasome activation is typically accompanied by Gasdermin d-mediated pyroptosis, which is an inflammatory form of programmed cell death, inflammasome formation in dendritic cells seems ill-advised. Therefore, we propose that hyperactivation, which is inflammasome activation without the induction of pyroptosis, may be a general model of inflammasome activation in dendritic cells to enhance Th1, Th17 as well as cytotoxic T cell responses.

Role for IL-1 Family Cytokines in Fungal Infections

Fungal pathogens kill approximately 1.5 million individuals per year and represent a severe disease burden worldwide. It is estimated over 150 million people have serious fungal disease such as recurrent mucosal infections or life-threatening systemic infections. Disease can ensue from commensal fungi or new infection and involves different fungal morphologies and the expression of virulence factors. Therefore, anti-fungal immunity is complex and requires coordination between multiple facets of the immune system. IL-1 family cytokines are associated with acute and chronic inflammation and are essential for the innate response to infection. Recent research indicates IL-1 cytokines play a key role mediating immunity against different fungal infections. During mucosal disease, IL-1R and IL-36R are required for neutrophil recruitment and protective Th17 responses, but function through different mechanisms. During systemic disease, IL-18 drives protective Th1 responses, while IL-33 promotes Th2 and suppresses Th1 immunity. The IL-1 family represents an attractive anti-fungal immunotherapy target. There is a need for novel anti-fungal therapeutics, as current therapies are ineffective, toxic and encounter resistance, and no anti-fungal vaccine exists. Furthering our understanding of the IL-1 family cytokines and their complex role during fungal infection may aid the development of novel therapies. As such, this review will discuss the role for IL-1 family cytokines in fungal infections.

The first line of defense: effector pathways of anti-fungal innate immunity

The innate immune system is critical to proper host defense against fungal pathogens, which is highlighted by increased susceptibility to invasive disease in immunocompromised patients. Innate cells (e.g. macrophages, neutrophils, dendritic cells, eosinophils) are equipped with intricate cell machinery to detect invading fungi and facilitate fungal killing, recruit additional immune cells, and direct the adaptive immune system responses. Understanding the mechanisms that govern a protective response will enable the development of novel treatment strategies. This review focuses on recent insights of signaling and regulation of C-type lectin receptors and their effector mechanisms enabling an effective host antifungal immunity.

Unraveling the susceptibility of paracoccidioidomycosis: Insights towards the pathogen-immune interplay and immunogenetics

Paracoccidioidomycosis (PCM) is a life-threatening systemic mycosis caused by Paracoccidioides spp. This disease comprises three clinical forms: symptomatic acute and chronic forms (PCM disease) and PCM infection, a latent form without clinical symptoms. PCM disease differs markedly according to severity, clinical manifestations, and host immune response. Fungal virulence factors and adhesion molecules are determinants for entry, latency, immune escape and invasion, and dissemination in the host. Neutrophils and macrophages play a paramount role in first-line defense against the fungus through the recognition of antigens by pattern recognition receptors (PRRs), activating their microbicidal machinery. Furthermore, the clinical outcome of the PCM is strongly associated with the variability of cytokines and immunoglobulins produced by T and B cells. While the mechanisms that mediate susceptibility or resistance to infection are dictated by the immune system, some genetic factors may alter gene expression and its final products and, hence, modulate how the organism responds to infection and injury. This review outlines the main findings relative to this topic, addressing the complexity of the immune response triggered by Paracoccidioides spp. infection from preclinical investigations to studies in humans. Here, we focus on mechanisms of fungal pathogenesis, the patterns of innate and adaptive immunity, and the genetic and molecular basis related to immune response and susceptibility to the development of the PCM and its clinical forms. Immunogenetic features such as HLA system, cytokines/cytokines receptors genes and other immune-related genes, and miRNAs are likewise discussed. Finally, we point out the occurrence of PCM in patients with primary immunodeficiencies and call attention to the research gaps and challenges faced by the PCM field.

Caspase-8 mediates inflammation and disease in rodent malaria

Earlier studies indicate that either the canonical or non-canonical pathways of inflammasome activation have a limited role on malaria pathogenesis. Here, we report that caspase-8 is a central mediator of systemic inflammation, septic shock in the Plasmodium chabaudi-infected mice and the P. berghei-induced experimental cerebral malaria (ECM). Importantly, our results indicate that the combined deficiencies of caspases-8/1/11 or caspase-8/gasdermin-D (GSDM-D) renders mice impaired to produce both TNFα and IL-1β and highly resistant to lethality in these models, disclosing a complementary, but independent role of caspase-8 and caspases-1/11/GSDM-D in the pathogenesis of malaria. Further, we find that monocytes from malaria patients express active caspases-1, -4 and -8 suggesting that these inflammatory caspases may also play a role in the pathogenesis of human disease.

Inflammasome activation plays a role in malaria pathogenesis, but details aren’t well understood. Here, the authors show that caspase-8 is a central mediator of systemic inflammation in rodent malaria and that monocytes from malaria patients express active caspases-1, -4 and -8.

Inflammasome signaling and regulation of interleukin-1 family cytokines

Specific IL-1 family cytokines are initially expressed as inactive, cytosolic pro-forms. Chan and Schroder review inflammasome signaling and cell death decisions, mechanisms underpinning IL-1α, IL-1β, IL-18, and IL-37 maturation and release, and the functions of these cytokines in protective and pathological inflammation.

Specific IL-1 family cytokines are expressed by cells as cytosolic pro-forms that require cleavage for their activity and cellular release. IL-1β, IL-18, and IL-37 maturation and secretion is governed by inflammatory caspases within signaling platforms called inflammasomes. By inducing pyroptosis, inflammasomes can also drive the release of the alarmin IL-1α. Recent advances have transformed our mechanistic understanding of inflammasome signaling, cell death decisions, and cytokine activation and secretion. Here, we provide an updated view of inflammasome signaling; mechanisms underpinning IL-1α, IL-1β, IL-18, and IL-37 maturation and release; and the functions of these cytokines in protective and pathological inflammation.

Paeonol ameliorates murine alcohol liver disease via mycobiota-mediated Dectin-1/IL-1β signaling pathway

Alcoholic liver disease (ALD) is caused by long-term consumption of alcohol and has become an important social and medical problem. Intestinal fungal flora (mycobiota) play an important role in ALD, so we used the mycobiota as an entry point to explore the mechanism of action of Paeonol against ALD. Here, we found that Paeonol is effective against ALD inflammatory lesions and relieves liver fat lesions. Furthermore, we found that after the treatment of Paeonol, the fungal dysbiosis is improved, and the fungal abundance is reduced, and the translocation of β-glucan to the liver and its mediated Dectin-1/IL-1β signaling pathway is blocked. Our study shows that paeonol ameliorated acute ALD-related inflammatory injury to the liver by alleviating intestinal fungal dysbiosis and inhibiting the mycobiota-mediated Dectin-1/IL-1β signaling pathway.

Caspase-11-dependent IL-1α release boosts Th17 immunity against Paracoccidioides brasiliensis

The granulomatous lesion resulting from infection with the fungus Paracoccidioides brasiliensis is characterized by a compact aggregate of mature cells, surrounded by a fibroblast- and collagen-rich content. Granuloma formation requires signaling elicited by inflammatory molecules such as members of the interleukin-1 family. Two members of this family have been thoroughly studied, namely IL-1α and IL-1β. In this study, we addressed the mechanisms underlying IL-1α secretion and its functional role on the host resistance to fungal infection. We found that, the expression of caspase-11 triggered by P. brasiliensis infection of macrophages depends on IFN-β production, because its inhibition reduced procaspase-11 levels. Curiously, caspase-11 deficiency did not impair IL-1β production, however caspase-11 was required for a rapid pore-mediated cell lysis. The plasma membrane rupture facilitated the release of IL-1α, which was necessary to induce NO production and restrict fungal replication. Furthermore, P. brasiliensis-infected macrophages required IL-1α to produce optimal levels of IL-6, a major component of Th17 lymphocyte differentiation. Indeed, IL-1α deficiency accounted for a significant reduction of Th17 lymphocytes in lungs of infected mice, correlating with diminished neutrophil infiltration in the lungs. Strikingly, we identified that IL-1α directly reprograms the transcriptional profile of Th17-committed lymphocytes, increasing cellular proliferation, as for boosting IL-17 production by these cells. Beyond neutrophil chemotaxis in vivo, IL-17 also amplified IL-1α production by infected macrophages in vitro, endorsing a critical amplification loop of the inflammatory response. Therefore, our data suggest that the IFN-β/caspase-11/IL-1α pathway shapes a protective antifungal Th17 immunity, revealing a molecular mechanism underlying the cross-talk between innate and adaptive immunity.

Involvement of the Dectin-1 Receptor upon the Effector Mechanisms of Human Phagocytic Cells against Paracoccidioides brasiliensis

Paracoccidioidomycosis (PCM), a systemic mycosis endemic in Latin America, occurs after inhalation of mycelial components of Paracoccidioides spp. When the fungus reaches the lungs and interacts with the alveolar macrophages and other cells, phagocytic cells such as neutrophils and monocytes are immediately recruited to the injured site. The interaction between surface molecules of pathogens and homologous receptors, present on the surface membrane of phagocytes, modulates the innate immune cell activation. Studies have shown the importance of fungal recognition by the Dectin-1 receptor, which can induce a series of cellular protective responses against fungi. The objective of the present study was to evaluate Dectin-1 receptor expression and the effector mechanisms of human monocytes and neutrophils activated or not with different cytokines, such as IFN-γ, TNF-α, and GM-CSF, followed by the challenge with Paracoccidioides brasiliensis (P. brasiliensis or Pb265). Therefore, analysis of Dectin-1 receptor expression was done by flow cytometry whereas the effector mechanisms were evaluated by fungal recovery by colony-forming unit (CFU) counting and hydrogen peroxide (H₂O₂) production. Our results showed that, after treatment with IFN-γ, TNF-α, and GM-CSF and challenge with Pb265, cells, especially monocytes, demonstrated an increase in Dectin-1 expression. Both types of cells treated with the cytokines exhibited a decreased fungal recovery and, conversely, an increased production of H₂O₂. However, when cultures were treated with an anti-Dectin-1 monoclonal antibody, to block the P. brasiliensis binding, a decrease in H₂O₂ production and an increase in fungal recovery were detected. This effect was observed in all cultures treated with the specific monoclonal antibody. These results show the involvement of the Dectin-1 receptor in fungal recognition and its consequent participation in the induction of the killing mechanisms against P. brasiliensis.

Ex Vivo Cytokine Release, Determined by a Multiplex Cytokine Assay, in Response to Coccidioidal Antigen Stimulation of Whole Blood among Subjects with Recently Diagnosed Primary Pulmonary Coccidioidomycosis

Coccidioidomycosis, commonly known as Valley fever, is a common pneumonia in the southwestern United States. In this paper, we examined the release of 30 inflammatory proteins in whole-blood samples obtained from persons with coccidioidal pneumonia after the blood samples were incubated with a preparation made from the causative fungus, Coccidioides. We found that six of these proteins, all cytokines, were specifically released in high concentrations in these patients. Three of the cytokines were seen very early in disease, and an assay for all six might serve as a marker for the early diagnosis of Valley fever.

The elements of the cellular immune response in human coccidioidomycosis remain undefined. We examined the ex vivo release of an array of inflammatory proteins in response to incubation with a coccidioidal antigen preparation to ascertain which of these might be associated with diagnosis and outcome. Patients with a recent diagnosis of primary pulmonary coccidioidomycosis and a control group of healthy subjects were studied. Blood samples were incubated for 18 h with T27K, a soluble coccidioidal preparation containing multiple glycosylated antigens, and the supernatant was assayed for inflammatory proteins using the multiplex Luminex system. The presentation and course of illness were compared to the levels of the inflammatory proteins. Among the 31 subjects studied, the median time from diagnosis to assay was 15 days. Of the 30 inflammatory proteins measured, the levels of only 7 proteins, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 receptor alpha (IL-1RA), interleukin-1β (IL-1β), interferon gamma (IFN-γ), IL-2, IL-13, and tumor necrosis factor alpha (TNF-α), were more than 10-fold above the levels seen without antigen stimulation. The levels of IFN-γ and IL-2 were significantly elevated in those subjects not receiving triazole antifungal therapy compared to those who were receiving triazole antifungal therapy. While the levels of IL-1RA were nonspecifically elevated, elevated levels of IL-13 were seen only in those with active pulmonary coccidioidomycosis. Only six cytokines were specifically increased in subjects with recently diagnosed primary pulmonary coccidioidomycosis. While IFN-γ, IL-2, and TNF-α have been previously noted, the finding of elevated levels of the innate cytokines GM-CSF and IL-1β could suggest that these, as well as IL-13, are early and specific markers for pulmonary coccidioidomycosis.

IMPORTANCE Coccidioidomycosis, commonly known as Valley fever, is a common pneumonia in the southwestern United States. In this paper, we examined the release of 30 inflammatory proteins in whole-blood samples obtained from persons with coccidioidal pneumonia after the blood samples were incubated with a preparation made from the causative fungus, Coccidioides. We found that six of these proteins, all cytokines, were specifically released in high concentrations in these patients. Three of the cytokines were seen very early in disease, and an assay for all six might serve as a marker for the early diagnosis of Valley fever.

NLRP3 inflammasome is involved in the recognition of Paracoccidioides brasiliensis by human dendritic cells and in the induction of Th17 cells

OBJECTIVES

To investigate the involvement of NLRP3 in the effector functions of human dendritic cells (DCs) in response to Paracoccidioides brasiliensis yeast cells (Pb) and to evaluate its role in the modulation of the adaptive immune response.

METHODS

DCs were differentiated from purified peripheral blood monocytes and analyzed in relation to the participation of TLR-2, dectin-1, and Syk in Pb recognition, as well as, the indirect mechanisms (Reactive Oxygen Species production, endosome acidification, or K⁺ efflux) involved in NLRP3 inflammasome activation after the stimulus with Pb. Additionally, we analyzed the role of NLRP3 in the activation of T cells.

RESULTS

Our results demonstrated that the NLRP3 inflammasome activation and cytokines production by DCs are dependent on ROS generation, endosome acidification, and K⁺ efflux and involve the Pb recognition by dectin-1 and Syk phosphorylation. Our data also demonstrate that the NLRP3 inflammasome is essential for the activation/expansion of Th1/Th17 cells and its inhibition leads to an increased frequency of Th2 and Treg cells.

CONCLUSION

Altogether our data indicated that activation of NLRP3 presents an important role in both the induction of the initial inflammatory response and in the development of the acquired immune response associated with resistance to infection.