Calcineurin-mediated IL-2 production by CD11chighMHCII+ myeloid cells is crucial for intestinal immune homeostasis

Restoring Treg/Th17 cell balance in ulcerative colitis through HRas silencing and MAPK pathway inhibition

This study investigates HRas-dependent mechanisms in the disruption of regulatory T (Treg) cells and T helper 17 (Th17) cells balance in ulcerative colitis (UC). Comprehensive RNA sequencing and bioinformatics analyses revealed elevated HRas and MAPK pathway-related protein expression in UC samples. Using a murine UC model induced by dextran sulfate sodium (DSS), HRas silencing was found to promote Treg cell differentiation and suppress Th17 cell production, effectively restoring balance. Inactivation of the MAPK pathway played a pivotal role in this rebalancing effect. In vivo experiments further confirmed that HRas silencing mitigated colon tissue damage in DSS-induced mice, emphasizing its potential as a therapeutic strategy for UC.

Bactericidal/permeability-increasing protein instructs dendritic cells to elicit Th22 cell response

Neutrophil-derived bactericidal/permeability-increasing protein (BPI) is known for its bactericidal activity against gram-negative bacteria and neutralization of lipopolysaccharide. Here, we define BPI as a potent activator of murine dendritic cells (DCs). As shown in GM-CSF-cultured, bone-marrow-derived cells (BMDCs), BPI induces a distinct stimulation profile including IL-2, IL-6, and tumor necrosis factor expression. Conventional DCs also respond to BPI, while M-CSF-cultivated or peritoneal lavage macrophages do not. Subsequent to BPI stimulation of BMDCs, CD4+ T cells predominantly secrete IL-22 and, when naive, preferentially differentiate into T helper 22 (Th22) cells. Congruent with the tissue-protective properties of IL-22 and along with impaired IL-22 induction, disease severity is significantly increased during dextran sodium sulfate-induced colitis in BPI-deficient mice. Importantly, physiological diversification of intestinal microbiota fosters BPI-dependent IL-22 induction in CD4+ T cells derived from mesenteric lymph nodes. In conclusion, BPI is a potent activator of DCs and consecutive Th22 cell differentiation with substantial relevance in intestinal homeostasis.

Fine tuning of the innate and adaptive immune responses by Interleukin-2

Novel immunotherapies for cancer and other diseases aim to trigger the immune system to produce durable responses, while overcoming the immunosuppression that may contribute to disease severity, and in parallel considering immunosafety aspects. Interleukin-2 (IL-2) was one of the first cytokines that the FDA approved as a cancer-targeting immunotherapy. However, in the past years, IL-2 immunotherapy is not actively offered to patients, due to limited efficacy, when compared to other novel immunotherapies, and the associated severe adverse events. In order to design improved in vitro and in vivo models, able to predict the efficacy and safety of novel IL-2 alternatives, it is important to delineate the mechanistic immunological events triggered by IL-2. Particularly, in this review we will discuss the effects IL-2 has with the bridging cell type of the innate and adaptive immune responses, dendritic cells. The pathways involved in the regulation of IL-2 by dendritic cells and T-cells in cancer and autoimmune disease will also be explored.

Dietary-fat supplementation alleviates cold temperature-induced metabolic dysbiosis and barrier impairment by remodeling gut microbiota

As important components of the mammalian diet and tissues, fats are involved in a variety of biological processes in addition to providing energy. In general, the increase in basal metabolism and health risks under cold temperature conditions causes the host to need more energy to maintain body temperature and normal biological processes. The intestine and its microbiota are key components in orchestrating host metabolic homeostasis and immunity, and respond rapidly to changing environmental conditions. However, the role of dietary-fat supplementation in regulating host homeostasis of metabolism and barrier functions through gut microbiota at cold temperatures is incompletely understood. Our results showed that dietary-fat supplementation alleviated the negative effects of cold temperatures on the alpha-diversity of both ileal and colonic microbiota. Cold temperatures altered the ileal and colonic microbiota of pigs, and the extent of changes was more pronounced in the colonic microbiota. Translocation of the gut microbiota was restored after supplementation with a high-fat diet. In addition, cold temperatures exacerbated ileal mucosal damage and inflammation, and disrupted barrier function, which may be associated with decreased concentrations of butyrate and isobutyrate. Cold temperature-induced metabolic dysbiosis was manifested by altered hormone levels and upregulation of expression of multiple metabolites involved in metabolism (lipids, amino acids and minerals) and the immune response. Supplementation with a high-fat diet restored metabolic homeostasis and barrier function by improving gut-microbiota composition and increasing SCFAs concentrations in pigs. In conclusion, cold temperatures induced severe translocation of microbiota and barrier damage. These actions increased the risk of metabolic imbalance. Dietary-fat supplementation alleviated the adverse effects of cold temperatures on host metabolism by remodeling the gut microbiota.

Rapid activation of IL-2 receptor signaling by CD301b+ DC-derived IL-2 dictates the outcome of helper T cell differentiation

Effector T helper (Th) cell differentiation is fundamental to functional adaptive immunity. Different subsets of dendritic cells (DCs) preferentially induce different types of Th cells, but the fate instruction mechanism for Th type 2 (Th2) differentiation remains enigmatic, as the critical DC-derived cue has not been clearly identified. Here, we show that CD301b+ DCs, a major Th2-inducing DC subset, drive Th2 differentiation through cognate interaction by 'kick-starting' IL-2 receptor signaling in CD4T cells. Mechanistically, CD40 engagement induces IL-2 production selectively from CD301b+ DCs to maximize CD25 expression in CD4 T cells, which is required specifically for the Th2 fate decision. On the other hand, CD25 in CD301b+ DCs facilitates directed action of IL-2 toward cognate CD4T cells. Furthermore, CD301b+ DC-derived IL-2 skews CD4T cells away from the T follicular helper fate. These results highlight the critical role of DC-intrinsic CD40-IL-2 axis in bifurcation of Th cell fate.

The kinetics of signaling through the common FcRγ chain determine cytokine profiles in dendritic cells

The common Fc receptor γ (FcRγ) chain is a signaling subunit common to several immune receptors, but cellular responses induced by FcRγ-coupled receptors are diverse. We investigated the mechanisms by which FcRγ generates divergent signals when coupled to Dectin-2 and Mincle, structurally similar C-type lectin receptors that induce the release of different cytokines from dendritic cells. Chronological tracing of transcriptomic and epigenetic changes upon stimulation revealed that Dectin-2 induced early and strong signaling, whereas Mincle-mediated signaling was delayed, which reflects their expression patterns. Generation of early and strong FcRγ-Syk signaling by engineered chimeric receptors was sufficient to recapitulate a Dectin-2-like gene expression profile. Early Syk signaling selectively stimulated the activity of the calcium ion-activated transcription factor NFAT, which rapidly altered the chromatin status and transcription of the Il2 gene. In contrast, proinflammatory cytokines, such as TNF, were induced regardless of FcRγ signaling kinetics. These results suggest that the strength and timing of FcRγ-Syk signaling can alter the quality of cellular responses through kinetics-sensing signaling machineries.

USP2 promotes experimental colitis and bacterial infections by inhibiting the proliferation of myeloid cells and remodeling the extracellular matrix network

Inflammatory bowel disease (IBD) is closely associated with dysregulation of genetic factors and microbial environment. Here, we report a susceptible role of ubiquitin-specific protease 2 (USP2) in experimental colitis and bacterial infections. USP2 is upregulated in the inflamed mucosa of IBD patients and in the colon of mice treated with dextran sulfate sodium salt (DSS). Knockout or pharmacologic inhibition of USP2 promotes the proliferation of myeloid cells to activate IL-22 and IFNγ production of T cells. In addition, knockout of USP2 in myeloid cells inhibits the production of pro-inflammatory cytokines to relieve the dysregulation of extracellular matrix (ECM) network and promote the gut epithelial integrity after DSS treatment. Consistently, Lyz2-Cre;Usp2fl/fl mice exhibit hyper-resistance to DSS-induced colitis and Citrobacter rodentium infections compared to Usp2fl/fl mice. These findings highlight an indispensable role of USP2 in myeloid cells to modulate T cell activation and epithelial ECM network and repair, indicating USP2 as a potential target for therapeutic intervention of IBD and bacterial infections in the gastrointestinal system.

Calcineurin in development and disease

Calcineurin (CaN) is a unique calcium (Ca²⁺) and calmodulin (CaM)-dependent serine/threonine phosphatase that becomes activated in the presence of increased intracellular Ca²⁺ level. CaN then functions to dephosphorylate target substrates including various transcription factors, receptors, and channels. Once activated, the CaN signaling pathway participates in the development of multiple organs as well as the onset and progression of various diseases via regulation of different cellular processes. Here, we review current literature regarding the structural and functional properties of CaN, highlighting its crucial role in the development and pathogenesis of immune system disorders, neurodegenerative diseases, kidney disease, cardiomyopathy and cancer.

The Microbiota and Cytokines Correlation between the Jejunum and Colon in Altay Sheep

Simple Summary

Both the jejunum and the colon secrete unique immune factors that interact with the gut microbiota. Investigating the association of gut microbiota and the host immune system, we detected higher populations of Bacteroides, Fibrobacteres and Spirochetes in the colon than in the jejunum of Altay sheep, which is a unique breed in Xinjiang. Levels of IL-6 and IL-12 were lower in the colon than in the jejunum. IL-10 was positively correlated with Ruminococcus_2 in the jejunum. These results indicate a potential interaction between intestinal microbiota and the host immune system that may be considered for the prevention of sheep diseases and the screening of probiotics.

Abstract

Both the jejunum and colon release cytokines that interact with intestinal microbiota. However, it is largely unclear which cytokines and microbial populations are involved in the homeostasis of the intestinal ecosystem for sheep health. To address this, we collected contents for isolating microbiota and tissues for determining cytokines from the jejunum and colon of 7-month-old Altay sheep. We used the techniques of 16S rRNA sequencing and ELISA to detect microbial population and cytokine level, respectively. Correlations between microbial population and cytokines were analyzed by Spearman correlation coefficient. The correlation analysis revealed higher populations of Bacteroides, Fibrobacteres and Spirochetes in the colon than in the jejunum, and IL-6 and IL-12 levels were higher in the jejunum than in the colon. Association analysis further revealed a positive association between IL-10 level and both Ruminococcus_2 and norank_f_Bifidobacteriaceae population in the jejunum. The analysis also revealed positive associations between IL-6 level and Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013 population, IL-10 and Prevotellaceae_UCG-004, as well as TNF-α and Prevotellaceae_UCG-003 in the colon. These results indicate a potential interaction between the intestinal microbiota and the host immune system that needs to be further clarified for considering dietary formulations to maintain animal health and disease prevention.

Guanylin ligand protects the intestinal immune barrier by activating the guanylate cyclase-C signaling pathway

Inflammatory bowel disease (IBD) impacts patient quality of life significantly. The dysfunction of intestinal immune barrier is closely associated with IBD. The guanylate cyclase-C (GC-C) signaling pathway activated by the guanylin (Gn) ligand is involved in the occurrence and development of IBD. However, how it regulates the intestinal immune barrier is still unclear. To investigate the effect of the GC-C pathway on intestinal mucosal immunity and provide experimental basis for seeking new therapeutic strategies for IBD, we focused on Caco-2 cells and intestinal intra-epithelial lymphocytes (IELs), which displayed inflammatory responses induced by lipopolysaccharide (LPS). GC-C activity was modulated by transfection with Gn overexpression or GC-C shRNA plasmid. Levels of Gn, GC-C, and CFTR; transepithelial electrical resistance (TER); paracellula r permeability; and levels of IL-2, IFN-γ, and secretory IgA (sIgA) were examined. The study found that after stimulation with LPS, Gn, GC-C, CFTR, TER, and sIgA levels were all significantly reduced, IL-2 and IFN-γ levels as well as paracellular permeability were significantly increased. These indicators changed inversely and significantly after transfection with the Gn overexpression vector. Compared to the vector controls, GC-C-silenced cells displayed significantly decreased levels of GC-C, CFTR, and TER and increased levels of IL-2, IFN-γ, and paracellular permeability stimulated by LPS. The results show that Gn ligand can protect the intestinal immune barrier by activating the GC-C signaling pathway, which may be helpful for the development of new treatments for IBD. DATA AVAILABILITY STATEMENT: The data used to support the findings of this study are available from the corresponding author upon request.

Inositol 1,4,5-trisphosphate 3-kinase B promotes Ca2+ mobilization and the inflammatory activity of dendritic cells

Innate immune responses to Gram-negative bacteria depend on the recognition of lipopolysaccharide (LPS) by a receptor complex that includes CD14 and TLR4. In dendritic cells (DCs), CD14 enhances the activation not only of TLR4 but also that of the NFAT family of transcription factors, which suppresses cell survival and promotes the production of inflammatory mediators. NFAT activation requires Ca²⁺ mobilization. In DCs, Ca²⁺ mobilization in response to LPS depends on phospholipase C γ2 (PLCγ2), which produces inositol 1,4,5-trisphosphate (IP₃). Here, we showed that the IP₃ receptor 3 (IP₃R3) and ITPKB, a kinase that converts IP₃ to inositol 1,3,4,5-tetrakisphosphate (IP₄), were both necessary for Ca²⁺ mobilization and NFAT activation in mouse and human DCs. A pool of IP₃R3 was located on the plasma membrane of DCs, where it colocalized with CD14 and ITPKB. Upon LPS binding to CD14, ITPKB was required for Ca²⁺ mobilization through plasma membrane-localized IP₃R3 and for NFAT nuclear translocation. Pharmacological inhibition of ITPKB in mice reduced both LPS-induced tissue swelling and the severity of inflammatory arthritis to a similar extent as that induced by the inhibition of NFAT using nanoparticles that delivered an NFAT-inhibiting peptide specifically to phagocytic cells. Our results suggest that ITPKB may represent a promising target for anti-inflammatory therapies that aim to inhibit specific DC functions.

Murine myeloid cell MCPIP1 suppresses autoimmunity by regulating B-cell expansion and differentiation

Myeloid-derived cells, in particular macrophages, are increasingly recognized as critical regulators of the balance of immunity and tolerance. However, whether they initiate autoimmune disease or perpetuate disease progression in terms of epiphenomena remains undefined.Here, we show that depletion of MCPIP1 in macrophages and granulocytes (Mcpip1fl/fl-LysMcre+ C57BL/6 mice) is sufficient to trigger severe autoimmune disease. This was evidenced by the expansion of B cells and plasma cells and spontaneous production of autoantibodies, including anti-dsDNA, anti-Smith and anti-histone antibodies. Consequently, we document evidence of severe skin inflammation, pneumonitis and histopathologic evidence of glomerular IgG deposits alongside mesangioproliferative nephritis in 6-month-old mice. These phenomena are related to systemic autoinflammation, which secondarily induces a set of cytokines such as Baff, Il5, Il9 and Cd40L, affecting adaptive immune responses. Therefore, abnormal macrophage activation is a key factor involved in the loss of immune tolerance.Overall, we demonstrate that deficiency of MCPIP1 solely in myeloid cells triggers systemic lupus-like autoimmunity and that the control of myeloid cell activation is a crucial checkpoint in the development of systemic autoimmunity.

Role of nuclear factor of activated T cells 2 (NFATc2) in allergic asthma

Background

We recently described increased NFATc1, IRF4, and NIP45 messenger RNA (mRNA) expression in peripheral blood mononuclear cells (PBMCs) of asthmatic children and adults with multiple allergies.

Objective

NFATc2 has been described to associate with IRF4 to induce interleukin‐4, and to be inhibited by T‐bet. Here, we analyzed the role of NFATc2 in asthmatic children and adults.

Methods

PBMCs were isolated from the blood of control of asthmatics subjects. Some PBMCs were analyzed untreated and some cultured with and without phytohemagglutinin. Then, RNA was extracted from the cells and cytokines were measured in the supernatants via enzyme‐linked immunosorbent assay or multiplex analysis. RNA was then reverse‐transcribed and NFATc1, NFATC2, IRF4, and T‐bet mRNA were analyzed by real‐time polymerase chain reaction. In addition, in peripheral blood cells, NFATc2 expression was analyzed, in a population of asthmatic children and adults from the Asthma BRIDGE study.

Results

In addition to NFATc1 and NIP45, also NFATc2 was found upregulated in PBMCs and peripheral blood cells from asthmatic children and adults with allergic asthma. Moreover, NFATc1 directly correlated with lymphocytes number whereas NFATc2 correlated with peripheral eosinophilia in asthma.

Conclusions

In addition to NFATc1 and NIP45, NFATc2 was found upregulated in asthma. Moreover, NFATc1 mRNA correlated with lymphocytes both in control and asthma, and NFATC1 and NFATc2 mRNA showed a direct correlation with eosinophils in controls but not in asthma, indicating that NFATc1 is associated with lymphocytes and not eosinophils in asthma.

Clinical Significance

Targeting NFATc2 in T lymphocytes might ameliorate the allergic phenotype in asthmatic subjects.

Roles of IL-2 in bridging adaptive and innate immunity, and as a tool for cellular immunotherapy

IL-2 was initially characterized as a T cell growth factor in the 1970s, and has been studied intensively ever since. Decades of research have revealed multiple and diverse roles for this potent cytokine, indicating a unique linking role between adaptive and innate arms of the immune system. Here, we review the literature showing that IL-2 is expressed in a plethora of cell types across the immune system, where it has indispensable functions in orchestrating cellular interactions and shaping the nature and magnitude of immune responses. Emerging from the basic research that has revealed the molecular mechanisms and the complexity of the biologic actions of IL-2, several immunotherapeutic approaches have now focused on manipulating the levels of this cytokine in patients. These strategies range from inhibition of IL-2 to achieve immunosuppression, to the application of IL-2 as a vaccine adjuvant and in cancer therapies. This review will systematically summarize the major findings in the field and identify key areas requiring further research in order to realize the potential of IL-2 in the treatment of human diseases.

Duan-Nai-An, A Yeast Probiotic, Improves Intestinal Mucosa Integrity and Immune Function in Weaned Piglets

Post-weaning diarrhea commonly occurs in piglets and results in significant economic loss to swine producers. Non-antibiotic measures for managing post-weaning diarrhea are critically needed. Duan-Nai-An, a probiotic produced from the yeast fermentation of egg whites, was previously shown to optimize intestinal flora and reduce the incidence of clinical diarrhea in weaning piglets. To study the effects of Duan-Nai-An on mucosal integrity and immunity in pig intestine, we examined the microstructure and ultrastructure of the intestines of weaned pigs with or without Duan-Nai-An as a feed supplement. The piglets of the Duan-Nai-An-fed group developed intestines with intact columnar epithelia covered by tightly packed microvilli on the apical surface. However, piglets of the control group (no supplement) showed villous atrophy and thinning, microvillus slough, and in the severe cases, damage of intestinal epithelia and exposure of the underlying lamina propria. Moreover, piglets of the Duan-Nai-An-fed group showed apparent plasmocyte hyperplasia, increased lymphoid nodule numbers, well-developed Peyer's Patchs, and apparent germinal centers. The lymphoid tissues of the control group were far less developed, showing lymph node atrophy, lymphocyte reduction, degeneration, and necrosis. These results indicate that Duan-Nai-An improves the development of the intestinal structures and lymphoid tissues and promotes intestinal health in weaned piglets.

JQ1-Loaded Polydopamine Nanoplatform Inhibits c-MYC/Programmed Cell Death Ligand 1 to Enhance Photothermal Therapy for Triple-Negative Breast Cancer

Programmed cell death ligand 1 (PD-L1) blockade has achieved great success in cancer immunotherapy; however, the response of triple-negative breast cancer (TNBC) to PD-L1 antibodies is limited. To address this challenge, we use the bromodomain and extra-terminal inhibitor JQ1 to down-regulate the expression of PD-L1 and thus elicit the immune response to TNBC instead of using antibodies to block PD-L1. JQ1 also inhibits the growth of TNBC as a targeted therapeutic agent by inhibiting the BRD4-c-MYC axis. The polydopamine nanoparticles (PDMNs) are introduced as a biodegradable and adaptable platform to load JQ1 and induce photothermal therapy (PTT) as another synergistic therapeutic modality. Because the JQ1-loaded PDMNs (PDMN-JQ1) are self-degradable and release JQ1 continuously, this synergistic treatment can lead to remarkable activation of cytotoxic T lymphocytes and induce a strong immune-memory effect to protect mice from tumor re-challenge. Taken together, our study demonstrates a compact and simple nanoplatform for triple therapy, including targeted therapy, PTT, and immunotherapy, for TNBC treatment.

Dendritic Cells Control Regulatory T Cell Function Required for Maintenance of Intestinal Tissue Homeostasis

Dendritic cells (DCs) together with regulatory T cells (Tregs) are essential mediators of immune homeostasis. Disruption of function or frequency of either cell type can lead to fatal autoimmunity. We previously described that mice constitutively lacking DCs (∆DC) develop autoimmunity characterized by reduced body weight, autoantibodies, and pronounced intestinal inflammation. In this study, we show that lack of DCs leads to an altered gene expression profile in peripheral but not thymic Tregs with increased expression of inhibitory receptors. The suppressive function of Tregs from ΔDC mice was impaired in T cell cocultures. In a model of transfer colitis, Tregs from ∆DC mice were only functional in the presence of DCs in recipient mice. Lack of MHC class II on DCs also resulted in upregulation of inhibitory receptors on Tregs, reduced body weight, and elevated serum IgA levels. Further analysis of the IgA response revealed an expansion of IgA⁺ germinal center B cells and plasma cells in mesenteric lymph nodes and more IgA-coated commensal bacteria in feces of ∆DC mice. Thus, we show a critical role for DCs to establish intestinal homeostasis by regulating Treg function for prevention of spontaneous inflammation.

USP16-mediated deubiquitination of calcineurin A controls peripheral T cell maintenance

Calcineurin acts as a calcium-activated phosphatase that dephosphorylates various substrates, including members of the nuclear factor of activated T cells (NFAT) family, to trigger their nuclear translocation and transcriptional activity. However, the detailed mechanism regulating the recruitment of NFATs to calcineurin remains poorly understood. Here, we report that calcineurin A (CNA), encoded by PPP3CB or PPP3CC, is constitutively ubiquitinated on lysine 327, and this polyubiquitin chain is rapidly removed by ubiquitin carboxyl-terminal hydrolase 16 (USP16) in response to intracellular calcium stimulation. The K29-linked ubiquitination of CNA impairs NFAT recruitment and transcription of NFAT-targeted genes. USP16 deficiency prevents calcium-triggered deubiquitination of CNA in a manner consistent with defective maintenance and proliferation of peripheral T cells. T cell-specific USP16 knockout mice exhibit reduced severity of experimental autoimmune encephalitis and inflammatory bowel disease. Our data reveal the physiological function of CNA ubiquitination and its deubiquitinase USP16 in peripheral T cells. Notably, our results highlight a critical mechanism for the regulation of calcineurin activity and a novel immunosuppressive drug target for the treatment of autoimmune diseases.

Calcineurin inhibitors reduce NFAT-dependent expression of antifungal pentraxin-3 by human monocytes

Calcineurin (CN) inhibitors are effective clinical immunosuppressants but leave patients vulnerable to potentially fatal fungal infections. This study tested the hypothesis that CN inhibition interferes with antifungal immune defenses mediated by monocytes. We showed that NFAT is expressed by human monocytes, and is activated by exposure to fungal ligands. We confirmed that NFAT translocation potently activated target gene transcription using a human monocytic reporter cell line. Inhibition of CN‐NFAT by cyclosporine A significantly reduced monocyte production of TNF‐α, IL‐10, and MCP‐1 proteins in response to pattern recognition receptor ligands as well as to Aspergillus fumigatus conidia. Moreover, we revealed that human monocytes express the antifungal protein pentraxin‐3 under control of NFAT. In conclusion, clinical CN inhibitors have the potential to interfere with the novel NFAT‐dependent pentraxin‐3 pathway as well as antifungal cytokine production in human monocytes, thereby impeding monocyte‐mediated defenses against fungal infection in immune‐suppressed patients.

Modulation of innate immunity by cyclosporine A

Cyclosporine A has long been known to suppress T cell responses by inhibiting the production of IL-2, which drives T cell proliferation, enabling its use as a therapeutic for transplantation or autoimmunity. However, cyclosporine A also impacts on innate immune cells including dendritic cells, macrophages and neutrophils. In dendritic cells, which are essential for T cell priming, cyclosporine A can modulate both expression of surface molecules that engage with T cells and cytokine secretion, leading to altered induction of T cell responses. In macrophages and neutrophils, which play key antimicrobial roles, cyclosporine A reduces the production of cytokines that can play protective roles against pathogens. Some of these molecules, if produced in the context of chronic disease, can also contribute to pathology. There have been a number of elegant recent studies addressing the mechanisms by which cyclosporine A can modulate innate immunity. In particular, cyclosporine A inhibits the release of mitochondrial factors that stimulate the production of type 1 interferons by innate immune cells. This review addresses the emerging literature on modulation of innate immune responses by cyclosporine A, its resultant impact on adaptive immune responses and how this offers potential for new therapeutic applications.