IL-1R Signaling Research Articles

NPAT Supports CD8+ Immature Single-Positive Thymocyte Proliferation and Thymic Development.

Thymocytes need to proliferate into a significant cell mass to allow a subsequent selection process during the double-positive (DP) stage. However, it is not clear at what stage this massive cell proliferation occurs. Immature CD8 single-positive (ISP) cells are a well-defined thymocyte subpopulation. However, the function of this cell subset has not yet been characterized. In this study, we analyzed the transcription pattern of mouse ISP cells and observed higher expression levels of cell cycling genes. We also found out that ISP cells exhibited the highest cell proliferative capacity among thymocytes in different developmental stages. Nuclear protein ataxia-telangiectasia (NPAT/p220) is one of the highly expressed cell cycling genes in ISP cells, which is known to play a critical role in coordinating histone gene expression necessary for rapid cell proliferation. Selective deletion of NPAT at the ISP stage led to reduced thymus size and significant loss of DP cells, secondary to reduced histone gene expression and impaired ISP cell proliferation capacity. A block of thymocyte development at the ISP stage was also observed, which was due to increased IL-7R expression. Continuous IL-7R signal served as a compensating mechanism for cell proliferation upon NPAT deletion, but in turn inhibited the expression of transcription factors TCF-1 and LEF-1, which is essential for the transition of ISP to DP cells. In summary, our study revealed the proliferation capacity of the ISP subpopulation during thymocyte differentiation as well as a vital role of NPAT in this developmental stage.

Induction of a colitogenic phenotype in Th1-like cells depends on interleukin-23 receptor signaling

Interleukin-23 receptor plays a critical role in inducing inflammation and autoimmunity. Here, we report that Th1-like cells differentiated invitro with IL-12+ IL-21 showed similar IL-23R expression to that of pathogenic Th17 cells using eGFP reporter mice. Fate mapping established that these cells did not transition through a Th17 cell state prior to becoming Th1-like cells, and we observed their emergence invivo in the Tcell adoptive transfer colitis model. Using IL-23R-deficient Th1-like cells, we demonstrated that IL-23R was required for the development of a highly colitogenic phenotype. Single-cell RNA sequencing analysis of intestinal Tcells identified IL-23R-dependent genes in Th1-like cells that differed from those expressed in Th17 cells. The perturbation of one of these regulators (CD160) in Th1-like cells inhibited the induction of colitis. We thus uncouple IL-23R as a purely Th17 cell-specific factor and implicate IL-23R signaling as a pathogenic driver in Th1-like cells inducing tissue inflammation.

Arsenic Induces GSK3β-Dependent p-Tau, Neuronal Apoptosis, and Cognitive Impairment via an Interdependent Hippocampal ERα and IL-1/IL-1R1 Mechanism in Female Rats.

Arsenic is an environmental contaminant with potential neurotoxicity. We previously reported that arsenic promoted hippocampal neuronal apoptosis, inducing cognitive loss. Here, we correlated it with tau pathology. We observed that environmentally relevant arsenic exposure increased tau phosphorylation and the principal tau kinase, glycogen synthase kinase-3 beta (GSK3β), in the female rat hippocampal neurons. We detected the same in primary hippocampal neurons. Because a regulated estrogen receptor (ER) level and inflammation contributed to normal hippocampal functions, we examined their levels following arsenic exposure. Our ER screening data revealed that arsenic down-regulated hippocampal neuronal ERα. We also detected an up-regulated hippocampal interleukin-1 (IL-1) and its receptor, IL-1R1. Further, co-treating arsenic with the ERα agonist, 4,4',4″-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), or IL-1R antagonist (IL-1Ra) resulted in reduced GSK3β and p-tau, indicating involvement of decreased ERα and increased IL-1/IL-1R1 in tau hyperphosphorylation. We then checked whether ERα and IL-1/IL-1R1 had linkage, and detected that although PPT reduced IL-1 and IL-1R1, the IL-1Ra restored ERα, suggesting their arsenic-induced interdependence. We finally correlated this pathway with apoptosis and cognition. We observed that PPT, IL-1Ra and the GSK3β inhibitor, LiCl, reduced hippocampal neuronal cleaved caspase-3 and TUNEL+ve apoptotic count, and decreased the number of errors during learning and increased the saving memory for Y-Maze test and retention performance for Passive avoidance test in arsenic-treated rats. Thus, our study reveals a novel mechanism of arsenic-induced GSK3β-dependent tau pathology via interdependent ERα and IL-1/IL-1R1 signaling. It also envisages the protective role of ERα agonist and IL-1 inhibitor against arsenic-induced neurotoxicity.

Single-Cell Transcriptomic Analysis Reveals Neutrophil as Orchestrator during β-Glucan-Induced Trained Immunity in a Teleost Fish.

Trained immunity defines long-term memory of innate immunity based on transcriptional, epigenetic, and metabolic modifications of myeloid cells, which are characterized by elevated proinflammatory responses toward homologous or heterologous secondary stimuli in mammals. However, the evidence of trained immunity-associated immune cells and its molecular mechanism in teleost fish remains largely unknown. In this study, we established a trained immunity activation model in turbot (Scophthalmus maximus) and found that administration with β-glucan induces protection against a bacterial infection. Through single-cell RNA sequencing to annotate 14 clusters of innate and adaptive immune cells, as well as two clusters of blood cells, from head kidney and spleen, respectively, we characterized that neutrophil displays cardinal features of trained immunity by analyzing the expression abundance of trained immunity database-related genes at the single-cell level. Subsequently, through establishing an in vivo training and in vitro neutrophil challenge model, we found that the trained neutrophils exhibit a significant elevation of the IL-1R signaling pathway after Edwardsiella piscicida infection. Furthermore, inhibition of neutrophil's IL-1R signaling pathway through anakinra treatment impaired the heightened production of reactive oxygen, nitrogen species, lactate, as well as the neutrophil extracellular traps formation and bacterial killing ability. Taken together, these findings characterized neutrophil as the orchestrator to express features of trained immunity, and revealed that the IL-1R signaling pathway plays a critical role in induction of trained immunity for bacterial clearance in teleost fish.

Regulation of Interleukin-36γ/IL-36R Signaling Axis by PIN1 in Epithelial Cell Transformation and Breast Tumorigenesis.

Simple SummaryMembers of the interleukin (IL)-1 cytokine family exhibit dual functions in the regulation of inflammation and cancer. Recent studies have shown the critical role of IL-36γ, the newly identified IL-1 family member, in the regulation of cellular processes implicated in the progression of cancer. Therefore, the underlying mechanism of IL-36γ in tumor development is of considerable interest. Here, we identified the pivotal role of IL-36γ in the proliferation of breast cancer cells. Consistently, IL-36γ was found to promote epithelial cell transformation via the activation of c-Fos, c-Jun, and AP-1 transcription factors, followed by the IL36R-mediated MEK/ERK and JNK/c-Jun cascades. Furthermore, our findings demonstrate the critical role of PIN1 in the regulation of IL-36γ-induced mammary gland tumorigenesis. Given the increasing recognition of the relationship between IL-1 cytokines, inflammation, and cancer, the significance of distinct members of the IL-1 cytokine family in the etiology of cancer has been widely researched. In the present study, we investigated the underlying mechanism of the IL-36γ/IL-36R axis during breast cancer progression, which has not yet been elucidated. Initially, we determined the effects of IL-36γ on the proliferation and epithelial cell transformation of JB6 Cl41 mouse epidermal and MCF7 human breast cancer cells using BrdU incorporation and anchorage-independent growth assays. We found that treatment with IL-36γ increased the proliferation and colony formation of JB6 Cl41 and MCF7 cells. Analysis of the mechanism underlying the neoplastic cell transformation revealed that IL-36γ induced IL-36R-mediated phosphorylation of MEK1/2, ERK1/2, JNK1/2, and c-Jun, resulting in increased c-Fos, c-Jun, and AP-1 activities in JB6 Cl41 and MCF7 cells. Furthermore, the IL-36γ-induced tumorigenic capacity of MCF7 cells was considerably enhanced by PIN1, following MEK/ERK and JNK/c-Jun signaling. Interestingly, blocking PIN1 activity using juglone suppressed the IL-36γ-induced increase in the anchorage-independent growth of 4T1 metastatic mouse breast cancer cells. Finally, in a syngeneic mouse model, IL-36γ-induced tumor growth in the breast mammary gland was significantly inhibited following PIN1 knockout.

Evaluation of interleukin-17 receptor(IL-17RA) gene expression in PBMCs of patients with premature coronaryartery disease.

Present study has been carried out to analyze the IL-17R gene expression in PBMCs of patients with premature coronary artery disease (CAD) in comparison to normal controls. Premature CAD results in disability and lack of quality of life over the years and consequent mortality.Cardiovascular disease (CVD) has global distribution. In 2022, CAD is the leading cause of mortality in the United States and Iran. IL-17 cytokine family plays an important role in promoting inflammation and producing pro-inflammatory cytokines, chemokines, and matrix metalloproteinases. Entirely, 60 subjects were entered into this examination. The case group consisted of 30 subjects with CAD as well as the control group which consisted of 30 healthy persons. The real-time quantitative reverse transcription PCR assay was used to find out, the relative expression (fold) level of IL-17R gene. Our findings indicated that, the relative expression (fold) level of IL-17R gene in the patients group showed an increased level as compared to the control group. The analysis of findingsobtained in this study showed that the patient group is significantly different from the control group regarding the IL-17R mRNA level (fold) (p = 0.035). It has been concluded that IL-17R plays an important role in the pathogenesis of CAD. It follows that superior understanding of IL-17/IL-17R signaling way will be vital for innovating novel therapeutic targets that will facilitate the designing of new drugs for the management of patients (Ref. 40).

LB993 Kinetics of IRAK4 degradation and impact on functional response in circulating immune cells and skin cell subsets

Kymera has developed selective IRAK4 degraders for the treatment of autoimmune and inflammatory diseases where IL-1R/TLR activation plays a central role in driving the inflammatory response. In autoimmune diseases of the skin, like hidradenitis suppurativa, keratinocytes are active inflammatory mediators that are triggered by IL1R signaling. IL1R signals through the myddosome which is dependent on the kinase and scaffold functions of Interleukin-1 receptor associated kinase 4 (IRAK4) to induce downstream production of proinflammatory cytokines like IL6 and IL8.

Prevalence and Mechanisms of Mucus Accumulation in COVID-19 Lung Disease.

Rationale: The incidence and sites of mucus accumulation and molecular regulation of mucin gene expression in coronavirus (COVID-19) lung disease have not been reported. Objectives: To characterize the incidence of mucus accumulation and the mechanisms mediating mucin hypersecretion in COVID-19 lung disease. Methods: Airway mucus and mucins were evaluated in COVID-19 autopsy lungs by Alcian blue and periodic acid-Schiff staining, immunohistochemical staining, RNA in situ hybridization, and spatial transcriptional profiling. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected human bronchial epithelial (HBE) cultures were used to investigate mechanisms of SARS-CoV-2-induced mucin expression and synthesis and test candidate countermeasures. Measurements and Main Results: MUC5B and variably MUC5AC RNA concentrations were increased throughout all airway regions of COVID-19 autopsy lungs, notably in the subacute/chronic disease phase after SARS-CoV-2 clearance. In the distal lung, MUC5B-dominated mucus plugging was observed in 90% of subjects with COVID-19 in both morphologically identified bronchioles and microcysts, and MUC5B accumulated in damaged alveolar spaces. SARS-CoV-2-infected HBE cultures exhibited peak titers 3 days after inoculation, whereas induction of MUC5B/MUC5AC peaked 7-14 days after inoculation. SARS-CoV-2 infection of HBE cultures induced expression of epidermal growth factor receptor (EGFR) ligands and inflammatory cytokines (e.g., IL-1α/β) associated with mucin gene regulation. Inhibiting EGFR/IL-1R pathways or administration of dexamethasone reduced SARS-CoV-2-induced mucin expression. Conclusions: SARS-CoV-2 infection is associated with a high prevalence of distal airspace mucus accumulation and increased MUC5B expression in COVID-19 autopsy lungs. HBE culture studies identified roles for EGFR and IL-1R signaling in mucin gene regulation after SARS-CoV-2 infection. These data suggest that time-sensitive mucolytic agents, specific pathway inhibitors, or corticosteroid administration may be therapeutic for COVID-19 lung disease.

Mutant IL7R collaborates with MYC to induce T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive pediatric cancer. Amongst the wide array of driver mutations, 10% of T-ALL patients display gain-of-function mutations in the IL-7 receptor α chain (IL-7Rα, encoded by IL7R), which occur in different molecular subtypes of this disease. However, it is still unclear whether IL-7R mutational activation is sufficient to transform T-cell precursors. Also, which genes cooperate with IL7R to drive leukemogenesis remain poorly defined. Here, we demonstrate that mutant IL7R alone is capable of inducing T-ALL with long-latency in stable transgenic zebrafish and transformation is associated with MYC transcriptional activation. Additionally, we find that mutant IL7R collaborates with Myc to induce early onset T-ALL in transgenic zebrafish, supporting a model where these pathways collaborate to drive leukemogenesis. T-ALLs co-expressing mutant IL7R and Myc activate STAT5 and AKT pathways, harbor reduced numbers of apoptotic cells and remake tumors in transplanted zebrafish faster than T-ALLs expressing Myc alone. Moreover, limiting-dilution cell transplantation experiments reveal that activated IL-7R signaling increases the overall frequency of leukemia propagating cells. Our work highlights a synergy between mutant IL7R and Myc in inducing T-ALL and demonstrates that mutant IL7R enriches for leukemia propagating potential.

Transcriptome and chromatin changes as regulatory T cells expand and contract to IL-2R signaling in vivo

Abstract Regulatory T cells are essential to maintain peripheral T cell tolerance and require IL-2R signaling for their development and homeostasis. Here, we used mouse IL-2 (mIL-2) and a fusion protein of mouse IL-2 linked to mouse CD25 (mIL-2/CD25) to induce acute, periodic, and persistent IL-2R-dependent signaling in peripheral Tregs in vivo. RNA- and ATAC-seq assessed longitudinal shifts in the transcriptome and chromatin landscape to define the molecular steps associated with IL-2R-dependent Treg activation, expansion, and subsequent contraction in vivo. Analysis of the RNA-seq data revealed that STAT5 and MYC were two critical drivers of IL-2R-dependent signaling in Tregs. Other signaling pathways were also identified that facilitate cell transcription, integration of TCR signaling, cell cycle progression, and growth. Sustained IL-2R signaling by mIL-2/CD25, but not periodic signaling by mIL-2, more effectively supported Treg expansion, oxidative phosphorylation, and development into eTregs. With respect to chromatin remodeling, IL-2R signaling initially preferentially increased accessibility to binding sites and activity of STAT5, whereas more persistent IL-2R signaling favored accessibility and activity of other transcription factors, dominantly CTCF, followed by a genome-wide less accessible chromatin. Our data favor a model whereby persistent IL-2R signaling initially supports more accessible chromatin and active transcription leading to a metabolic shift toward a more energetic type required for Treg proliferation. Subsequently, as IL-2R signaling diminishes, a shift toward less accessible chromatin occurs that facilitates contraction of the expanded Tregs to restore homeostasis. This research was supported by funding from Bristol Myers Squibb and the NIH (R01AI148675).

Interleukin-2 signaling engages de novo cholesterol biosynthesis in regulatory T cells

Abstract In the absence of IL-2R signaling, Treg homeostasis is severely disrupted. This is accompanied by a decrease in the expression of enzymes related to cholesterol biosynthesis, but the function of this pathway in Tregs is unknown. To investigate this, we selectively ablated Sterol Regulatory Binding Element Protein 2 by crossing Srebp2flox/flox mice to Foxp3cre mice (Srebp2cKO). Consistent with published studies, homozygous Srebp2cKO mice are outwardly normal. However, when Srebp2cKO Tregs are placed in competition with wild-type Tregs, they are found at a reduced frequency in the spleen, lymph nodes and gut mucosa. In this setting, Srebp2cKO Tregs have reduced Foxp3 expression, suggesting that their function and/or stability may be impacted by altered cholesterol biosynthesis. These defects persist in lymphoid and non-lymphoid tissues when Tregs in competition are treated with an IL-2R agonist. In addition, a marked reduction in effector Treg differentiation is associated with Srebp2cKO Tregs, as expression of CD39, CD73, CD103, Klrg1 and ICOS is reduced while Bcl-2 and CD62L are increased. In response to IL-2R signaling, Srebp2cKO Tregs do not optimally upregulate CD25, which suggests a function for cholesterol biosynthesis in supporting the high affinity IL-2R. These results are consistent with a model whereby IL-2R signaling coordinates Treg cholesterol biosynthesis, which contributes to effector Treg development and raises the possibility that cholesterol biosynthesis could be a target in the therapeutic manipulation of Tregs. Supported by grants from NIH (F30 AI157211-01A1, RO1 AI148675-01)

The Protective Role of IL-36/IL-36R Signal in Con A-Induced Acute Hepatitis

Abstract The IL-36 family, including IL-36α, IL-36β, IL-36γ, and IL-36 receptor antagonist (IL-36Ra), belongs to the IL-1 super-family. Although IL-36 is known to play a role in autoimmune diseases, it remains unclear as how IL-36 regulates inflammation in the liver. To determine the role of IL-36/IL-36R signaling pathways, we established an acute hepatitis mouse model by intravenous injection of the plant lectin concanavalin A (Con A), and found that the levels of IL-36 were increased in the liver following Con A injection. We also demonstrated that intrahepatic leukocytes, but not hepatocytes, were the main source of IL-36. Moreover, further research verified that infiltrated neutrophils were the main source of IL-36γ in the liver. Using the IL-36R knockout mouse model (H-2b), surprisingly, we found that the absence of IL-36 signals led to aggravated liver injuries, as evidenced by increased mortality, accompanied by elevated serum ALT and AST levels and severe pathological changes in the liver. Further investigations demonstrated that a lack of IL-36 signaling induced intrahepatic activation of CD4+ and CD8+T lymphocytes and increased the production of inflammatory cytokines. In addition, IL-36R knockout mice had reduced Treg cell functions and chemotaxis in the liver. Together, our results suggest a vital role of IL-36 in regulating T cell function and homeostasis during liver injury and inflammation. Supported by grants from NIH (R01 EY028773, AI132674, R21 AI153586)

Abstract 507: Adipocyte-specific Cytokine Signaling Regulates Inflammation And Atherosclerosis

Adipose tissue inflammation has been implicated in various chronic inflammatory diseases and cancer. Perivascular adipose tissue (PVAT) surrounds the aorta as a fourth layer and was previously shown to regulate the function of endothelial and vascular smooth muscle cells. Moreover, PVAT contains various immune cells and therefore could contribute to the inflammatory environment in the aorta during atherosclerosis development via cross-talk with adventitia. We found that Western diet (WD) feeding increases the accumulation of immune cells in PVAT of atherosclerosis-prone Ldlr -/- mice and increases the expression of IL-1β. As IL-1 is essential for atherosclerosis development and its inhibition in patients in CANTOS trial reduced inflammation and cardiovascular events, we further evaluated the potential role of IL1R signaling in adipocytes of PVAT.We found that adipocyte-specific ablation of IL1R in Il1r fl/fl Ldlr -/- AdipoCre + mice fed with Western Diet for 16 weeks led to significant reduction in atherosclerosis when compared to Il1r fl/fl Ldlr -/- AdipoCre - controls. Gene expression analysis of isolated adipocytes revealed a significant reduction of expression of several chemokines, including Ccl2, Ccl5, Ccl7 as well as pro-atherogenic cytokines IL-6 and IL-1β . The analysis of immune cell composition by Flow cytometry and scRNA sequencing further demonstrated reduced representation of key pro-inflammatory cell subsets in PVAT of l1r fl/fl Ldlr -/- AdipoCre + which also reflected in their reduced accumulation in the aorta and atherosclerotic plaques. Our data suggest novel adipocyte-specific mechanisms controlling inflammation in atherosclerosis. IL1R signaling therefore directly regulates pro-inflammatory chemokines and cytokines in adipocytes thereby controlling immune cell recruitment to PVAT and aortic wall, which in turn contributes to the enhanced aortic inflammation and atherosclerosis.

CEACAM1 is an IL-2R-dependent biomarker in patients with multiple autoimmune-diseases undergoing low-dose IL-2 therapy

Abstract Low-dose (LD) IL-2 is a promising strategy to boost Tregs in patient with autoimmune diseases. This therapeutic strategy would benefit by identifying biomarkers that are highly and selectively responsive to IL-2R signaling in Treg and Teff cells. To initially address this point, RNA-seq was used to screen for genes that are induced in CD4+ Foxp3+ Treg and CD4+ CD45RO+ T effector/memory (TEM) cells from normal subjects in vitro by IL-2R, but not TCR/CD28, signaling. CEACAM1 was identified as a candidate gene in Tregs 4 and 24 hours post-stimulation. However, CEACAM1 was optimally upregulated in Treg and TEM cells after an extended 5 day culture with anti-CD3/CD28 and IL-2. Notably, anti-IL-2 essentially completely inhibited this upregulation, indicating that CEACAM1 expression was strictly IL-2 dependent. Tregs were shown to express the long isoform of CEACAM1 with inhibitory ITIM domains and the ITIMs may be functionally active as most in vitro activated CEACAM1+ Tregs did not express Ki67. To assess CEACAM1 as an IL-2-dependent biomarker during LD-IL-2 therapy, CD25 and CEACAM1 were evaluated at the protein and RNA levels for patient samples from eight distinct autoimmune diseases. In all samples, CEACAM1 was upregulated after a 5-day induction course of LD-IL-2 in Tregs but not TEM cells. This finding correlated with the effect of LD-IL-2 on CD25. CEACAM1 levels returned to baseline 14 days post-LD-IL-2 treatment. After the induction course of LD-IL-2, most CEACAM1+ Tregs were Ki67−, consisting with an inhibitory role for CEACAM1. Collectively, our findings indicate that CEACAM1 is a biomarker for LD-IL-2 therapy whose expression is highly dependent on IL-2R signaling and suggest that CEACAM1 may function to regulate Treg homeostasis. Supported by R01AI131643

Abstract 150: Cytokine Signaling In Intestinal Epithelial Cells As A Regulator Of Microbiota, Inflammation And Atherosclerosis

While microbiota regulates immunity and was suggested to play a role in atherosclerosis, the specific role of cytokine signaling in intestinal epithelial cells (IEC) in control of microbiota, inflammation, and vascular disease remains unknown. We previously showed that IL-23 enforces intestinal barrier, controls pro-atherogenic bacteria, metabolites, and activation of myeloid cells, and protects from atherosclerosis. Here we investigate the role of IL-23-regulated IL-17 signaling in IEC using newly generated Ldlr -/- Il17rc fl/fl VillinCre + mice. We found that IEC-specific ablation of IL-17RC heightened subclinical intestinal inflammation, altered microbiota composition, and led to enhanced atherosclerosis development accompanied by accumulation of activated myeloid and T cells in aortas. Mechanistically, IL-17RC ablation in IEC reduced tight junction proteins as well as IgA transport to the lumen due to altered Pigr expression thereby contributing to the expansion of pro-atherogenic microbiota. RNAseq analysis revealed upregulation of multiple inflammatory pathways, including interferon and TLR signaling, while several metabolic pathways such as fatty acid oxidation and pyruvate pathways were downregulated in IL17RC IEC Ldlr -/- mice; implying an important role of IL-17R signaling in the control of IEC and microbial metabolism. Our work uncovers a novel protective role of IEC-specific IL-17 signaling in atherosclerosis and establishes a paradigm of cytokine-mediated regulation of barrier, microbiota, and metabolic pathways in cardiovascular diseases.

IL-7 and IL-7R regulate fetal macrophage establishment via survival and proliferation

Abstract We have recently reported that IL7R signaling regulates fetal macrophage development, in addition to lymphocyte lineage commitment and development. Specifically, IL7R deletion and pharmacological blockade during a defined fetal developmental window impairs the establishment of fetal macrophage populations in the liver, lung, brain, and epidermis. We next hypothesized that IL-7 is also required for fetal macrophage establishment and that IL-7 signaling activates developmental programs that facilitate macrophage development via proliferation and survival. Immunofluorescent staining of E14.5 murine embryos revealed abundant co-localized IL7R and F4/80 expression in fetal liver, lung, brain, and skin. IL7R+ F4/80-expressing cells were also found in close proximity to IL-7+ cells, suggesting they participate in IL-7 signaling. Moreover, germline deletion of IL-7 also resulted in postnatal depletion of fetal-derived macrophage populations. Antibody blockade of IL-7R receptor during late gestation revealed tissue-specific deficits in survival and proliferation the day before birth. Specifically, liver and lung macrophages showed increased apoptosis, as determined by Annexin V staining, while brain and epidermal macrophages were less proliferative, as determined by Ki67 staining. Here we have shown that IL-7, in addition to IL7R, regulates establishment of tissue-resident macrophages and that fetal blockade of IL7R signaling regulates establishment by impairing survival and proliferation during late gestation. Ongoing work seeks to define IL7/IL7R signaling pathways in developing macrophages, as well as use genetic models to pinpoint the requirement for IL7R in fetal myeloid specification. Supported by grants from NIH (R01 10057561).

Interleukin-36β exacerbates DSS-induce acute colitis via inhibiting Foxp3+ regulatory T cell response and increasing Th2 cell response

Backgroundinterleukin (IL)-36β is a member of the IL-36 subfamily of the IL-1 family. Usually, serum levels of IL-36β are higher in patients with inflammatory bowel disease (IBD), indicating that IL-36β has a pathophysiological role in IBD. At the time of writing, no studies were published reporting the role of IL-36β in modulating T cell-mediated immune responses in gastrointestinal inflammation. This research aimed to determine the function of IL-36β in regulating T cells in mice with colitis caused by dextran sulfate sodium (DSS). Methodsrecombinant IL-36β (rIL-36β) was administered by intraperitoneal injection to mice with DSS-induced colitis. Clinical symptoms, colon length, and histological changes were determined. The production of cytokines was measured by ELISA. The help T (Th) cell subsets were measured by flow cytometry. The expression of mRNA of IL-36β was measured by quantitative real-time PCR. Resultsthere was an increased expression of IL-36 in the inflamed colonic mucosa of mice with DSS-induced acute colitis. Mice treated with recombinant IL-36β (rIL-36β) were more susceptible to DSS-induced colitis than PBS-treated mice. Moreover, spontaneous inflammatory cytokines produced by neutrophils greatly increased in the lamina propria lymphocytes (LPL) of rIL-36β-treated animals with DSS-induced colitis. Besides, rIL-36β-treatment dramatically elevated Th2 cell responses but significantly downregulated Foxp3+ regulatory T cell (Treg) responses. Conclusionthese findings indicate that IL-36β enhances the pathology of DSS-induced colitis in mice by promoting Th2 responses in LPL while decreasing Foxp3+ Treg responses. Thus, we propose the regulation of the IL-36β/IL-36R signaling pathway as a potential biological treatment for IBD.

Interleukin-38 in Health and Disease.

• IL-38 is a member of the IL-1 Family that inhibits IL-1R6, IL-1R9, and IL-1R1 signaling. • IL-38 inhibits the innate, trained, and adaptive immune response. • IL-38 polymorphisms are associated with inflammatory disease and biomarkers thereof. • IL-38 is often indicative of human disease severity, and generally protective in animal models. • The role of B cells in the biology of IL-38 remains elusive.

Acute exposure to phthalates during recovery from a myocardial infarction induces greater inflammasome activation in male C57bl/6N mice

Plasticizers escape from medical devices used in cardiac surgery into patient blood and tissues. Increased di-ethylhexyl phthalate (DEHP) exposure is correlated with chronic inflammation in vivo and increased cytokine release in exposed monocytes in vitro. To determine if acute phthalate exposure enhanced inflammation in a model of cardiac damage, we measured immune cell infiltration, inflammasome expression and cardiac function in male C57bl/6 N mice exposed to phthalates during recovery from a surgically-induced myocardial infarction (MI). Phthalate exposed mice had greater neutrophil and pro-inflammatory macrophage infiltration, greater cardiac dilation and reduced cardiac function when compared with control mice. The greater expression of NLRP3 and NLRP6, but not AIM2 or P2xR7, in the infarcts of phthalate exposed versus control mice suggests a selectivity in pattern recognition receptor activation. Treatment of human THP-1 macrophages with phthalates revealed increased NLRP3 and NLRP6 expression and induction of a pro-inflammatory macrophage population. Pre-treatment with the PPARγ antagonist GW9662 reduced these increases. An increase in expression of IL-1R, MyD88 and IRAK4 in infarcts of phthalate exposed mice and THP-1 cells argues for greater priming downstream of IL-1R signaling and increased susceptibility for inflammasome activation. Importantly, these effects were moderated in vivo when phthalate exposure was reduced by 90% and when the NLRP3 antagonist MCC950 was co-administered. Our study suggests that reductions in phthalate exposure, which might be realized using plasticizers with a reduced ability to leach out from plastic, or short-term treatment with an anti-inflammasome may improve healing post-surgery.

The Protective Role of IL-36/IL-36R Signal in Con A-Induced Acute Hepatitis.

The IL-36 family, including IL-36α, IL-36β, IL-36γ, and IL-36R antagonist, belong to the IL-1 superfamily. It was reported that IL-36 plays a role in immune diseases. However, it remains unclear how IL-36 regulates inflammation. To determine the role of IL-36/IL-36R signaling pathways, we established an acute hepatitis mouse model (C57BL/6) by i.v. injection of the plant lectin Con A. We found that the levels of IL-36 were increased in the liver after Con A injection. Our results demonstrated the infiltrated neutrophils, but not the hepatocytes, were the main source of IL-36 in the liver. Using the IL-36R-/- mouse model (H-2b), we surprisingly found that the absence of IL-36 signals led to aggravated liver injury, as evidenced by increased mortality, elevated serum alanine aminotransferase and aspartate aminotransferase levels, and severe liver pathological changes. Further investigations demonstrated that a lack of IL-36 signaling induced intrahepatic activation of CD4+ and CD8+ T lymphocytes and increased the production of inflammatory cytokines. In addition, IL-36R-/- mice had reduced T regulatory cell numbers and chemokines in the liver. Together, our results from the mouse model suggested a vital role of IL-36 in regulating T cell function and homeostasis during liver inflammation.