IL-1R Pathways Research Articles

Discovery of KT-474─a Potent, Selective, and Orally Bioavailable IRAK4 Degrader for the Treatment of Autoimmune Diseases.

Interleukin-1 receptor associated kinase 4 (IRAK4) is an essential mediator of the IL-1R and TLR signaling pathways, both of which have been implicated in multiple autoimmune conditions. Hence, blocking the activity of IRAK4 represents an attractive approach for the treatment of autoimmune diseases. The activity of this serine/threonine kinase is dependent on its kinase and scaffolding activities; thus, degradation represents a potentially superior approach to inhibition. Herein, we detail the exploration of structure-activity relationships that ultimately led to the identification of KT-474, a potent, selective, and orally bioavailable heterobifunctional IRAK4 degrader. This represents the first heterobifunctional degrader evaluated in a nononcology indication and dosed to healthy human volunteers. This molecule successfully completed phase I studies in healthy adult volunteers and patients with atopic dermatitis or hidradenitis suppurativa. Phase II clinical trials in both of these indications have been initiated.

The IL-17 pathway intertwines with neurotrophin and TLR/IL-1R pathways since its domain shuffling origin

The IL-17 pathway displays remarkably diverse functional modes between different subphyla, classes, and even orders, yet its driving factors remains elusive. Here, we demonstrate that the IL-17 pathway originated through domain shuffling between a Toll-like receptor (TLR)/IL-1R pathway and a neurotrophin-RTK (receptor-tyrosine-kinase) pathway (a Trunk-Torso pathway). Unlike other new pathways that evolve independently, the IL-17 pathway remains intertwined with its donor pathways throughout later evolution. This intertwining not only influenced the gains and losses of domains and components in the pathway but also drove the diversification of the pathway's functional modes among animal lineages. For instance, we reveal that the crustacean female sex hormone, a neurotrophin inducing sex differentiation, could interact with IL-17Rs and thus be classified as true IL-17s. Additionally, the insect prothoracicotropic hormone, a neurotrophin initiating ecdysis in Drosophila by binding to Torso, could bind to IL-17Rs in other insects. Furthermore, IL-17R and TLR/IL-1R pathways maintain crosstalk in amphioxus and zebrafish. Moreover, the loss of the Death domain in the pathway adaptor connection to IκB kinase and stress-activated protein kinase (CIKSs) dramatically reduced their abilities to activate nuclear factor-kappaB (NF-κB) and activator protein 1 (AP-1) in amphioxus and zebrafish. Reinstating this Death domain not only enhanced NF-κB/AP-1 activation but also strengthened anti-bacterial immunity in zebrafish larvae. This could explain why the mammalian IL-17 pathway, whose CIKS also lacks Death, is considered a weak signaling activator, relying on synergies with other pathways. Our findings provide insights into the functional diversity of the IL-17 pathway and unveil evolutionary principles that could govern the pathway and be used to redesign and manipulate it.

Effects of regulatory B cells on intracranial aneurysms by mediating IL-1β/IL-1R pathways.

The purpose of this study was to explore the effects of regulatory B-cells (Breg) on intracranial aneurysms by mediating IL-1β/IL-1R pathways. The study involved 60 patients undergoing angiography in a hospital from January to June 2022, divided into two groups: 30 with intracranial aneurysms (observation group) and 30 without (control group). Researchers extracted peripheral blood mononuclear cells (PBMC) to analyze the proportion of CD19+CD24hiCD38hiB cells using flow cytometry. These cells, along with T-cells and regulatory T-cells (Treg), were isolated through magnetic bead cell sorting. Following co-culture, the proliferation of T-cells and their related secretory factors were assessed. Additionally, Breg cells, treated with an IL-1R receptor blocker or IL-1R expression adenovirus, were studied to evaluate the levels of IL-10 and TGF-β. In the study, the observation group showed lower levels of CD19+CD24hiCD38hiB cells, IL-10, and TGF-β in PBMC than the control group (P<0.05). T-cell proportions were similar in both groups pre and post co-culture (P>0.05). Post co-culture, IFN-γ decreased while IL-4 increased in both groups. The observation group had higher IFN-γ and lower IL-4 than the control group (P<0.05). TNF-α in CD8+T cells, and granzyme B and perforin mRNA levels decreased post co-culture but were higher in the observation group (P<0.05). IL-10 and TGF-β in Treg cells increased in both groups post co-culture but were lower in the observation group (P<0.05). The observation group also had fewer CD19+IL-1R+IL-10+B cells (P<0.05). After IL-1R blocker addition, IL-10 and TGF-β in the supernatant decreased in the observation group (P<0.05). Following transfection, IL-1 and TGF-β levels increased compared to the blank group (P<0.05). The function of peripheral blood CD19+CD24hiCD38hiB cells is impaired in patients with intracranial aneurysms, which may be related to IL-1β/IL-1R pathways disorder.

Adjuvant AS01 activates human monocytes for costimulation and systemic inflammation

BackgroundThe adjuvanted recombinant zoster vaccine (RZV) is highly effective even in adults over 80 years old. The high efficacy of RZV is attributed to its highly reactogenic adjuvant, AS01, but limited studies have been done on AS01’s activation of human immune cells. MethodsWe stimulated peripheral blood mononuclear cells (PBMC) with AS01 and used flow cytometry and RNA Sequencing (RNAseq) to analyze the impacts on human primary cells. ResultsWe found that incubation of PBMC with AS01 activated monocytes to a greater extent than any other cell population, including dendritic cells. Both classical and non-classical monocytes demonstrated this activation. RNASeq showed that TNF-ɑ and IL1R pathways were highly upregulated in response to AS01 exposure, even in older adults. ConclusionsIn a PBMC co-culture, AS01 strongly activates human monocytes to upregulate costimulation markers and induce cytokines that mediate systemic inflammation. Understanding AS01’s impacts on human cells opens possibilities to further address the reduced vaccine response associated with aging.

Luspatercept Modulates Inflammation in the Bone Marrow, Restores Effective Erythropoiesis/Hematopoiesis, and Provides Sustained Clinical Benefit Versus Epoetin Alfa (EA): Biomarker Analysis from the Phase 3 COMMANDS Study

Introduction :Anemia is common in patients (pts) with myelodysplastic syndromes (MDS) due to ineffective erythropoiesis, characterized by increased dysplastic erythroid precursors (EPs) and abortive differentiation in the bone marrow (BM). Insufficient red blood cells (RBCs) lead to chronic anemia and heart failure due to oxygen deprivation. Luspatercept is approved to treat anemia after erythropoiesis-stimulating agent (ESA) failure in pts with transfusion-dependent, lower-risk MDS (LR-MDS). In the phase 3 COMMANDS trial (NCT03682536), 58.5% of ESA-naive luspatercept treated pts with LR-MDS experienced RBC transfusion independence for ≥ 12 wk with concurrent mean hemoglobin (Hb) increase ≥ 1.5 g/dL during wk 1-24, vs 31.2% of EA-treated pts. Aims :To differentiate the mechanism of action of luspatercept from EA and determine its correlation with clinical benefit in the COMMANDS study. Methods :Cytomorphology assessments were performed on BM aspirates at baseline, wk 24 and 48. Complete blood count, Hb, and reticulocytes (retics) were measured in peripheral blood. BM mononuclear cells (BMMC) were subjected to bulk RNA-seq. Serum cytokine analysis was performed at screening and wk 24 using Rules-Based Medicine's Human Inflammation MAP ® v.1.1 and a custom Human MAP ELISA panel. Results :In ITT population, EPs, retics, and Hb were increased vs baseline in the luspatercept arm at wk 24 ( P &amp;lt; 0.001) and wk 48 ( P &amp;lt; 0.005). EPs, retics, and Hb were increased in the EA arm at wk 24 ( P &amp;lt; 0.01), but this was not sustained to wk 48. Subgroup analysis showed similar trends for ring sideroblast (RS)+ pts in both arms. While RS− pts in the EA arm showed similar trends to the ITT population, luspatercept RS− pts showed trends of EP expansion post-wk 24 only. Retics increased significantly in RS− luspatercept pts at wk 24 ( P &amp;lt; 0.005). Hb increased more significantly at wk 24 with EA ( P &amp;lt; 0.003) but at wk 48 with luspatercept ( P &amp;lt; 0.005).Gene set enrichment analysis of BMMC revealed enrichment of early, mid, and late EP genes at baseline favored response to luspatercept, but enrichment of mid and late EP genes was unfavorable for EA (Figure A). Significant downregulation of REACTOME IL-1 signaling (normalized enrichment score [NES] = −2.27; adjusted [Adj] P &amp;lt; 0.0001 [vs EA = not significant (ns)]), BIOCARTA IL-6 pathway (NES = −1.99; Adj P = 0.0025 [vs EA = ns]) and IFNα response (NES: −2.26; Adj P &amp;lt; 0.0001 [vs EA = ns]) was observed with luspatercept. BIOCARTA IL-1R pathway was more significantly reduced with luspatercept (NES = −1.78; Adj P = 0.0073) compared with EA (NES = −1.79; Adj P = 0.0172), as was IL-10 signaling (luspatercept NES = −2.39; Adj P &amp;lt; 0.001 vs EA NES = −1.82; Adj P = 0.0125). TGF-β, apoptosis, and spliceosome pathways down regulation was also observed with luspatercept. At wk 24, luspatercept responders had a median 640 pg/mL decrease ( P = 0.0035) of N-terminal pro-brain natriuretic peptide (NT-proBNP), produced by the heart, compared with a median 360 pg/mL decrease in EA arm responders ( P = 0.37). At wk 24, non-responders had a median increase of 775 pg/mL ( P = 0.0032) in the EA arm and 31.5 pg/mL ( P = 0.95) in the luspatercept arm. Conclusions : Multiplatform analysis of primary BM samples from a phase 3 trial of luspatercept revealed novel response-associated biomarkers. Compared with EA, luspatercept led to sustained increase of EPs and retics over 48 wk with a concomitant Hb increase. RS− pts showed Hb accumulation peaked at wk 24 in the EA arm. Conversely, luspatercept in RS− pts significantly increased retics at wk 24 and EPs past wk 24 with concomitant peaking of Hb at wk 48, suggesting gradual and sustained clinical benefit. Unlike EA, which plays a role in early differentiation of hematopoietic stem cells (HSCs), luspatercept acts on different erythroid stages, leading to EP expansion and maturation. Furthermore, downregulation of IL-1, IL-1R, IFNα, IL-6 pro-inflammatory (Figure B), and IL-10 anti-inflammatory signaling with luspatercept suggests modulation of the BM inflammatory environment in MDS to restore HSC function for normal hematopoiesis (Wang J, et al. Front Immunol 2022;13:951937). Additionally, decreased or static levels of NT-proBNP with luspatercept suggest a positive effect in mitigating cardiac damage. These novel insights obtained from analysis of a large controlled clinical trial mechanistically differentiate the superior clinical benefit of luspatercept from EA in treating anemia due to MDS.

Identification of mitochondrial related signature associated with immune microenvironment in Alzheimer’s disease

BackgroundAlzheimer's disease (AD) is the most common neurodegenerative disease. Mitochondrial dysfunction and immune responses are important factors in the pathogenesis of AD, but their crosstalk in AD has not been studied. In this study, the independent role and interaction of mitochondria-related genes and immune cell infiltration in AD were investigated using bioinformatics methods.MethodsThe datasets of AD were obtained from NCBI Gene Expression Omnibus (GEO), and the data of mitochondrial genes was from MitoCarta3.0 database. Subsequently, differential expression genes (DEGs) screening and GSEA functional enrichment analysis were performed. The intersection of DEGs and mitochondrial related genes was used to obtain MitoDEGs. The MitoDEGs most relevant to AD were determined by Least absolute shrinkage and selection operator and multiple support vector machine recursive feature elimination, as well as protein–protein interactions (PPI) network and random forest. The infiltration of 28 kinds of immune cells in AD was analyzed by ssGSEA, and the relationship between hub MitoDEGs and the proportion of immune infiltration was studied. The expression levels of hub MitoDEGs were verified in cell models and AD mice, and the role of OPA1 in mitochondrial damage and neuronal apoptosis was investigated.ResultsThe functions and pathways of DEGs were significantly enriched in AD, including immune response activation, IL1R pathway, mitochondrial metabolism, oxidative damage response and electron transport chain-oxphos system in mitochondria. Hub MitoDEGs closely related to AD were obtained based on PPI network, random forest and two machine learning algorithms. Five hub MitoDEGs associated with neurological disorders were identified by biological function examination. The hub MitoDEGs were found to be correlated with memory B cell, effector memory CD8 T cell, activated dendritic cell, natural killer T cell, type 17 T helper cell, Neutrophil, MDSC, plasmacytoid dendritic cell. These genes can also be used to predict the risk of AD and have good diagnostic efficacy. In addition, the mRNA expression levels of BDH1, TRAP1, OPA1, DLD in cell models and AD mice were consistent with the results of bioinformatics analysis, and expression levels of SPG7 showed a downward trend. Meanwhile, OPA1 overexpression alleviated mitochondrial damage and neuronal apoptosis induced by Aβ1-42.ConclusionsFive potential hub MitoDEGs most associated with AD were identified. Their interaction with immune microenvironment may play a crucial role in the occurrence and prognosis of AD, which provides a new insight for studying the potential pathogenesis of AD and exploring new targets.

Tryptophol Acetate and Tyrosol Acetate, Small-Molecule Metabolites Identified in a Probiotic Mixture, Inhibit Hyperinflammation

Probiotic fermented foods are perceived as contributing to human health; however, solid evidence for their presumptive therapeutic systemic benefits is generally lacking. Here we report that tryptophol acetate and tyrosol acetate, small-molecule metabolites secreted by the probiotic milk-fermented yeast Kluyveromyces marxianus, inhibit hyperinflammation (e.g., “cytokine storm”). Comprehensive in vivo and in vitro analyses, employing LPS-induced hyperinflammation models, reveal dramatic effects of the molecules, added in tandem, on mice morbidity, laboratory parameters, and mortality. Specifically, we observed attenuated levels of the proinflammatory cytokines IL-6, IL-1α, IL-1β, and TNF-α and reduced reactive oxygen species. Importantly, tryptophol acetate and tyrosol acetate did not completely suppress proinflammatory cytokine generation, rather brought their concentrations back to baseline levels, thus maintaining core immune functions, including phagocytosis. The anti-inflammatory effects of tryptophol acetate and tyrosol acetate were mediated through downregulation of TLR4, IL-1R, and TNFR signaling pathways and increased A20 expression, leading to NF-kB inhibition. Overall, this work illuminates phenomenological and molecular details underscoring anti-inflammatory properties of small molecules identified in a probiotic mixture, pointing to potential therapeutic avenues against severe inflammation.

Identification of oncogenic signatures in the inflammatory colon of C57BL/6 mice fed a high-fat diet

Adoption of an obesogenic diet such as a high-fat diet (HFD) results in obesity, bacterial dysbiosis, chronic inflammation, and cancer. Gut bacteria and their metabolites are recognized by interleukin-1 (IL-1R)/toll-like receptors (TLRs) which are essential to maintain intestinal homeostasis. Moreover, host extracellular microRNAs (miRNAs) can alter bacterial growth in the colon. Characterization of the underlying mechanisms may lead to identifying fecal oncogenic signatures reflecting colonic health. We hypothesize that an HFD accelerates the inflammatory process and modulates IL-1R/TLR pathways, gut microbiome, and disease-related miRNA in the colon. In this study, 4-week-old C57BL/6 mice were fed a modified AIN93G diet (AIN, 16% energy fat) or an HFD (45% energy fat) for 15 weeks. In addition to increased body weight and body fat composition, the concentrations of plasma interleukin 6 (IL-6), inflammatory cell infiltration, β-catenin, and cell proliferation marker (Ki67) in the colon were elevated > 68% in the HFD group compared to the AIN group. Using a PCR array analysis, we identified 14 out of 84 genes with a ≥ 24% decrease in mRNA content related to IL-1R and TLR pathways in colonic epithelial cells in mice fed an HFD compared to the AIN. Furthermore, the content of Alistipes bacteria, the Firmicutes/Bacteroidetes ratio, microRNA-29a, and deoxycholic and lithocholic acids (secondary bile acids with oncogenic potential) were 55% greater in the feces of the HFD group compared to the AIN group. Collectively, this composite, a multimodal profile may represent a unique HFD-induced fecal signature for colonic inflammation and cancer in C57BL/6 mice.

P-397 How do extracellular vesicles secreted by human embryos impact decidualized endometrial stromal cells?

Abstract Study question What is the transcriptomic response of decidualized endometrial stromal cells (DESCs) to the uptake of extracellular vesicles (EVs) secreted by human embryos? Summary answer Human embryo derived EVs can impact DESCs transcriptomic profile via a cargo that can induce a positive effect on the expression of some decidualization-related genes. What is known already The establishment of an appropriate embryo–endometrial communication is essential for the implantation process and a successful pregnancy. Embryo-released factors are able to elicit biological effects on the endometrium. Among these, EVs secreted by embryos carry molecules potentially able to modulate endometrial function and favour the implantation process. However, most results come from animal species as few studies were performed using EVs derived from human embryos, due to difficulty in sample collection or ethical reasons. Study design, size, duration EVs were isolated from one pool of IVF media where embryos were cultured between day 3 and 5 of development (blastocyst). Initially, DESCs(n = 4) were treated with different concentrations of EVs at different time points and RNA-sequencing was performed to define optimal conditions.Subsequently, EVs were isolated from one pool of IVF media where blastocysts diagnosed as euploid were cultured (EVe). To increase the reliability of the results, DESCs(n = 5) were treated with EVe using the optimal conditions. Participants/materials, setting, methods EVs were isolated by differential ultracentrifugation from spent media of in vitro cultured human blastocyst stage embryos and from an equal volume of control medium (not exposed to embryos). DESCs were in vitro decidualized (E2:10nM+ P4:1uM+cAMP:0.5mM) and treated with different concentrations of EVs (10µg,50µg,100µg) for 24hours and 48hours. RNA-sequencing analysis was then performed. Once established the conditions that allow to better detect differences in trascriptomic profile, RNA-sequencing analysis on DESCs treated specifically with EVe was performed. Main results and the role of chance The best response of DESCs to EVs uptake was induced by treatment with 10µg of EVs for 48hours. Using this condition, differential gene expression analysis allowed the identification of 166 upregulated and 124 downregulated genes in DESCs treated with EVe, when compared to DESCs treated with control. Based on Over-Representation analysis, DESCs treated with EVe were found to be enriched in transcripts of genes involved in signalling and cell communication. Moreover, based on Gene Set Enrichment Analysis results, EVe may regulate decidualization and the implantation process by targeting cholesterol biosynthesis and metabolism pathways, being among the most enriched pathways. The depletion of transcripts related to inflammatory and IL1R pathways in DESCs treated with EVe was also observed, suggesting a role of EVe in the fine regulation of inflammatory/immunomodulatory events occurring during implantation. At the intersection of genes whose expression was modified by EVe-treatment and those modified by the decidualization treatment, thirty-one transcripts exhibited the same trend, demonstrating that EVe exerted a positive effect on decidualization-related genes expression in DESCs. Specifically, expression of genes involved in the implantation process (PTGER2, IL15, WNT4) increased after decidualization and were further up-regulated after EVe-treatment, confirming the crucial role of EVs in the embryo-endometrium cross-talk. Limitations, reasons for caution Larger studies are needed to validate these findings. Wider implications of the findings EVs derived from human euploid embryos can evoke a specific transcriptional response in DESCs. Moreover, we speculate that these EVs may exert favourable effects on the endometrial tissue, increasing its receptivity for embryo implantation by modulating decidualization-related genes expression. Trial registration number not applicable

The genetic basis of pneumococcal and staphylococcal infections: inborn errors of human TLR and IL-1R immunity.

Many bacteria can cause pyogenic lesions in humans. Most of these bacteria are harmless in most individuals, but they, nevertheless, cause significant morbidity and mortality worldwide. The inherited and acquired immunodeficiencies underlying these pyogenic infections differ between bacteria. This short review focuses on two emblematic pyogenic bacteria: pneumococcus (Streptococcus pneumoniae) and Staphylococcus, both of which are Gram-positive encapsulated bacteria. We will discuss the contribution of human genetic studies to the identification of germline mutations of the TLR and IL-1R pathways.

Transcriptomic analysis reveals that IL-1R8/Sigirr is a novel macrophage migration regulator and suppresses macrophage proliferation through p38 MAPK signaling pathway

IL-1R8, also known as the Single immunoglobin interleukin-1 (IL-1)-related receptor (Sigirr), has been demonstrated as a negative regulator of IL-1R and Toll-like receptor (TLR) downstream signaling pathways and inflammation. However, the role of IL-1R8 in macrophage migration and proliferation remains unknown. Here we investigated transcriptome profiles of WT and Il1r8-deficient splenocytes and found that innate immunity and cell migration related pathways were significantly correlated with IL-1R8 expression. Cell migration-related genes were downregulated in Il1r8−/− splenocytes or IL-1R8-depleted RAW264.7 cells. Further experiments revealed that IL-1R8-depleted RAW264.7 cells or Il1r8−/− BMDMs exhibited impaired cell migration. Moreover, we found that IL-1R8 suppresses macrophage proliferation through p38 MAPK signaling pathway. Therefore, our study suggests that IL-1R8 is a new positive regulator for macrophage migration and suppresses macrophage proliferation.

Anti-inflammatory mediators ST2 and SIGIRR are induced by diphenyldifluoroketone EF24 in lipopolysaccharide-stimulated dendritic cells.

The objective of this study was to investigate the effect of EF24, an NF-κB-inhibitor, on the expression of negative regulators in IL-1R pathway, namely ST2 and SIGIRR. Murine JAWS II dendritic cells (DC) were challenged with lipopolysaccharide (LPS, 100 ng/ml) for 4 h, followed by treatment with 10 μM EF24 for 1 h. ST2 and SIGIRR expression was monitored by qRT-PCR and immunoblotting. ST2L and MyD88 interaction was studied by co-immunoprecipitation, and IL-33, a ST2L ligand, was assayed by ELISA. Activation of transcription factor SP1 was examined by confocal microscopy, immunoblotting, and EMSA. The effect of EF24 on accumulation of ubiquitinated proteins in DCs and proteolysis of fluorogenic peptides by purified proteasome was studied. We found that EF24 upregulated the expression of ST2 and SIGIRR and decreased the interaction of the membrane-bound ST2 (ST2L) with MyD88, and significantly reduced IL-33 levels in LPS-stimulated DCs. Simultaneously it increased the activation of transcription factor SP1and restored the basal level of ubiquitinated proteins in LPS-stimulated DCs. Moreover, EF24 inhibited trypsin- and chymotrypsin-like activity of proteasome by directly interacting with 26S proteasome. The results suggest that EF24 activates endogenous anti-inflammatory arm of IL-1R signaling, most likely by stabilizing SP1 against proteasomal degradation.

Regulation of Staphylococcus aureus-induced CXCR1 expression via inhibition of receptor mobilization and receptor shedding during dual receptor (TNFR1 and IL-1R) neutralization.

Our earlier studies proposed a radically new idea suggesting interdependency between TNF-α/TNFR1 and IL-1β/IL-1R pathways in modulation of Staphylococcus aureus-induced CXCL8/CXCR1 axis. However, the effects of inhibition of cytokine receptor mobilization at intracellular level and surface TNFR1 and IL-1R shedding on S. aureus-induced CXCR1 expression have not been studied so far in peritoneal macrophages. This study aimed to investigate the role of inhibition of receptor mobilization from the intracellular pool (using brefeldin A) and surface receptor shedding (using TAPI-1) on CXCR1 expression during dual receptor (TNFR1 plus IL-1R) neutralization in peritoneal macrophages isolated from wild-type Swiss Albino mice. Release of superoxide anion, nitric oxide, and hydrogen peroxide was measured and cytokine production was done by ELISA. Expression of surface receptors (TNFR1, IL-1R, and CXCR1) and inflammatory mediators was studied by Western blot. It was observed that S. aureus-infected macrophages showed elevated ROS production, secretion of TNF-α, IL-1β, and CXCL8, along with increased expression of surface receptors (TNFR1, IL-1R, and CXCR1), and inflammatory markers (iNOS and COX-2) compared with control or treated groups (p < 0.05). However, prior treatment of macrophages with BFA or TAPI-1 in the presence of anti-TNFR1 antibody and IRAP during S. aureus infection showed significant reduction of all these parameters (p < 0.05). We can conclude that targeting of TNFR1 and IL-1R (with major focus on surface expression study) either through blockage of intracellular receptor trafficking pathway or via surface receptor shedding diminishes TNFR1/IL-1R interaction and consequently downregulates CXCR1 expression along with inflammatory signalling pathways during bacterial infections.

ST2/MyD88 Deficiency Protects Mice against Acute Graft-versus-Host Disease and Spares Regulatory T Cells.

Acute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (HCT). Plasma levels of soluble membrane-bound ST2 (ST2) are elevated in human and murine aGVHD and correlated to type 1 T cells response. ST2 signals through the adapter protein MyD88. The role of MyD88 in T cells during aGVHD has yet to be elucidated. We found that knocking out MyD88 in the donor T cells protected against aGVHD independent of IL-1R and TLR4 signaling in two murine HCT models. This protection was entirely driven by MyD88-/- CD4 T cells. Transplanting donor MyD88-/- conventional T cells (Tcons) with wild-type (WT) or MyD88-/- regulatory T cells (Tregs) lowered aGVHD severity and mortality. Transcriptome analysis of sorted MyD88-/- CD4 T cells from the intestine 10 d post-HCT showed lower levels of Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, Batf, and Jak2 Transplanting donor ST2-/- Tcons with WT or ST2-/- Tregs showed a similar phenotype with what we observed when using donor MyD88-/- Tcons. Decreased ST2 was confirmed at the protein level with less secretion of soluble ST2 and more expression of ST2 compared with WT T cells. Our data suggest that Treg suppression from lack of MyD88 signaling in donor Tcons during alloreactivity uses the ST2 but not the IL-1R or TLR4 pathways, and ST2 represents a potential aGVHD therapeutic target sparing Tregs.

Deficiency of MyD88 signaling in CD4 Tconvs increases Tregs suppression through loss of ST2 signaling

Abstract Acute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (allo-HCT). We found that plasma soluble suppression of tumorigenicity 2 (sST2) predicted GVHD-related mortality in allo-HCT patients. ST2 signals through the adapter protein MyD88. Lack of MyD88 in CD4 Tconvs has been shown to decrease ovalbumin or a peptide to the haplotype H2b stimulated Th1/Th17 cells via the IL-1R. Thus, we hypothesized that absence of MyD88 signaling would protect against aGVHD through IL-1R, ST2, or both. We found that knocking out MyD88 in the donor T cells protected against aGVHD while recipients of IL-1R−/− donor T cells showed no difference. We found that the aGVHD protection was entirely driven by MyD88−/− CD4 T cells. There were no differences in proliferation, apoptosis, or migration in WT or MyD88−/− CD4 T cells. We next explored the cell-intrinsic role of MyD88−/− Tconvs and Tregs. We did not find a difference in survival in aGVHD models with MyD88−/− Tconvs or MyD88−/− Tregs. However, use of MyD88−/− Tconvs with WT or MyD88−/− Tregs ameliorated aGVHD. We hypothesized that this was mediated by lack of ST2 on donor Tconvs. Recipients of ST2−/− Tconvs with WT or ST2−/− Tregs lowered aGVHD mortality, mirroring MyD88−/− Tconvs. Transcriptome analysis comparing 10 days post-HCT CD4 T cells from MyD88−/− versus WT recipients showed lower levels of Irak1, Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, and Jak2 as well as decreased systemic plasma sST2 and IFN-γ levels. Our data suggests that Tregs suppression from lack of MyD88 signaling in Tconvs during alloreactivity uses the ST2 but not the IL-1R pathway, possibly by different antigen stimulation. MyD88 represents an aGVHD therapeutic target sparing Treg function.

IRAK1 Drives Intestinal Inflammation by Promoting the Generation of Effector Th Cells with Optimal Gut-Homing Capacity.

IL-1R-associated kinase (IRAK) 1 is an important component of the IL-1R and TLR signaling pathways, which influence Th cell differentiation. In this study, we show that IRAK1 promotes Th17 development by mediating IL-1β-induced upregulation of IL-23R and subsequent STAT3 phosphorylation, thus enabling sustained IL-17 production. Moreover, we show that IRAK1 signaling fosters Th1 differentiation by mediating T-bet induction and counteracts regulatory T cell generation. Cotransfer experiments revealed that Irak1-deficient CD4(+) T cells have a cell-intrinsic defect in generating Th1 and Th17 cells under inflammatory conditions in spleen, mesenteric lymph nodes, and colon tissue. Furthermore, IRAK1 expression in T cells was shown to be essential for T cell accumulation in the inflamed intestine and mesenteric lymph nodes. Transcriptome analysis ex vivo revealed that IRAK1 promotes T cell activation and induction of gut-homing molecules in a cell-intrinsic manner. Accordingly, Irak1-deficient T cells failed to upregulate surface expression of α4β7 integrin after transfer into Rag1(-/-) mice, and their ability to induce colitis was greatly impaired. Lack of IRAK1 in recipient mice provided additional protection from colitis. Therefore, IRAK1 plays an important role in intestinal inflammation by mediating T cell activation, differentiation, and accumulation in the gut. Thus, IRAK1 is a promising novel target for therapy of inflammatory bowel diseases.

IL-1 beta but not the NALP3 inflammasome is an important determinant of endothelial cell responses to necrotic/dangerous trophoblastic debris

IntroductionNecrotic but not apoptotic trophoblastic debris can induce endothelial cell activation but the mechanism by which endothelial cells distinguish apoptotic from necrotic debris is unclear. The NALP3 inflammasome is a pattern recognition receptor that macrophages employ to recognise “danger signals” in necrotic cell corpses. In this study, we hypothesized that endothelial cells can identify and respond to necrotic trophoblastic debris via the NALP3 inflammasome. MethodsThe effect of trophoblastic debris on endothelial expression of NALP3 inflammasome components was investigated using qRT-PCR, immunoassays and fluorescent caspase 1 activity assay. IL-1β in was quantified by ELISA. Endothelial cell activation was measured by cell surface ICAM expression and monocytes adhesion assay. ResultsThe NALP3 inflammasome was expressed in resting vascular endothelial cells and is involved in endothelial response to danger signals. However, exposure to necrotic trophoblastic debris did not significantly alter the expression of any of the three components of the NALP3 inflammasome at the mRNA level, nor was caspase-1 activation increased. Conditioned media from endothelial cells exposed to necrotic trophoblastic debris contained elevated levels of IL-1β which was derived from the necrotic debris and which contributed to endothelial cell activation. DiscussionNecrotic trophoblastic debris induced endothelial cell activation through the IL-1β/IL-1R pathway. However, the NALP3 inflammasome in endothelial cells was not involved in this process.

IMQ-induced skin inflammation in mice is dependent on IL-1R1 and MyD88 signaling but independent of the NLRP3 inflammasome.

The pathogenesis of inflammatory skin diseases such as psoriasis involves the release of numerous proinflammatory cytokines, including members of the IL-1 family. Here we report overexpression of IL-1α, IL-1β, and IL-1 receptor antagonist mRNA, associated to expression of IL-23p19, IL-17A, and IL-22 in skin cells, upon topical application of the TLR7 agonist imiquimod (IMQ) in C57BL/6J mice. IMQ-induced skin inflammation was partially reduced in mice deficient for both IL-1α/IL-1β or for IL-1 receptor type 1 (IL-1R1), but not in IL-1α- or IL-1β-deficient mice, demonstrating the redundant activity of IL-1α and IL-1β for skin inflammation. NLRP3 or apoptosis-associated Speck-like protein containing a Caspase recruitment domain-deficient mice had no significant reduction of skin inflammation in response to IMQ treatment, mainly due to the redundancy of IL-1α. However, IMQ-induced skin inflammation was abolished in the absence of MyD88, the adaptor protein shared by IL-1R and TLR signaling pathways. These results are consistent with the TLR7 dependence of IMQ-induced skin inflammation. Thus, IL-1R1 contributes to the IMQ-induced skin inflammation, and disruption of MyD88 signaling completely abrogates this response.

The novel S59P mutation in the TNFRSF1A gene identified in an adult onset TNF receptor associated periodic syndrome (TRAPS) constitutively activates NF-κB pathway

IntroductionMutations in the TNFRSF1A gene, encoding tumor necrosis factor receptor 1 (TNF-R1), are associated with the autosomal dominant autoinflammatory disorder, called TNF receptor associated periodic syndrome (TRAPS). TRAPS is clinically characterized by recurrent episodes of long-lasting fever and systemic inflammation. A novel mutation (c.262 T > C; S59P) in the TNFRSF1A gene at residue 88 of the mature protein was recently identified in our laboratory in an adult TRAPS patient. The aim of this study was to functionally characterize this novel TNFRSF1A mutation evaluating its effects on the TNF-R1-associated signaling pathways, firstly NF-κB, under particular conditions and comparing the results with suitable control mutations.MethodsHEK-293 cell line was transfected with pCMV6-AC construct expressing wild-type (WT) or c.262 T > C (S59P), c.362G > A (R92Q), c.236C > T (T50M) TNFRSF1A mutants. Peripheral blood mononuclear cells (PBMCs) were instead isolated from two TRAPS patients carrying S59P and R92Q mutations and from five healthy subjects. Both transfected HEK-293 and PBMCs were stimulated with tumor necrosis factor (TNF) or interleukin 1β (IL-1β) to evaluate the expression of TNF-R1, the activation of TNF-R1-associated downstream pathways and the pro-inflammatory cytokines by means of immunofluorescent assay, array-based technique, immunoblotting and immunometric assay, respectively.ResultsTNF induced cytoplasmic accumulation of TNF-R1 in all mutant cells. Furthermore, all mutants presented a particular set of active TNF-R1 downstream pathways. S59P constitutively activated IL-1β, MAPK and SRC/JAK/STAT3 pathways and inhibited apoptosis. Also, NF-κB pathway involvement was demonstrated in vitro by the enhancement of p-IκB-α and p65 nuclear subunit of NF-κB expression in all mutants in the presence of TNF or IL-1β stimulation. These in vitro results correlated with patients’ data from PBMCs. Concerning the pro-inflammatory cytokines secretion, mainly IL-1β induced a significant and persistent enhancement of IL-6 and IL-8 in PBMCs carrying the S59P mutation.ConclusionsThe novel S59P mutation leads to defective cellular trafficking and to constitutive activation of TNF-R1. This mutation also determines constitutive activation of the IL-1R pathway, inhibition of apoptosis and enhanced and persistent NF-κB activation and cytokine secretion in response to IL-1β stimulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0604-7) contains supplementary material, which is available to authorized users.

Tollip or not Tollip: what are the evolving questions behind it?

Tollip plays an important role in the interleukin-1 receptor IL-1R and Toll pathways. As a modulator of the immune pathway, it indirectly controls the amount of antimicrobial peptides. This could indicate a vital step in maintaining animal immune systems and preventing infection. Evolutionary questions are crucial to understanding the conservation and functioning of the biochemical pathways like the Tollip-mediated one. Through an analysis of 36 sequences of the Tollip protein from different animal taxa, downloaded from Kyoto Encyclopedia of Genes and Genomes (KEGG) databank, we inferred diverse evolutionary parameters, such as molecular selection and structure conservation, by analyzing residue by residue, beyond the canonical parameters to this type of study, as maximum likelihood trees. We found that Tollip presented different trends in its evolving history. In primates, the protein is becoming more unstable, just the opposite is observed in the arthropod group. The most interesting finding was the concentration of positively selected residues at amino terminal ends. Some observed topological incongruences in maximum likelihood trees of complete and curated Tollip data sets could be explained through horizontal transfers, evidenced by recombination detection. These results suggest that there is more to be researched and understood about this protein.