Pathogenic Interleukin-10 Receptor Alpha Variants in Humans - Balancing Natural Selection and Clinical Implications.

Balancing natural selection is a process by which genetic variants arise in populations that are beneficial to heterozygous carriers, but pathogenic when homozygous. We systematically investigated the prevalence, structural, and functional consequences of pathogenic IL10RA variants that are associated with monogenic inflammatory bowel disease. We identify 36 non-synonymous and non-sense variants in the IL10RA gene. Since the majority of these IL10RA variants have not been functionally characterized, we performed a systematic screening of their impact on STAT3 phosphorylation upon IL-10 stimulation. Based on the geographic accumulation of confirmed pathogenic IL10RA variants in East Asia and in Northeast China, the distribution of infectious disorders worldwide, and the functional evidence of IL-10 signaling in the pathogenesis, we identify Schistosoma japonicum infection as plausible selection pressure driving variation in IL10RA. Consistent with this is a partially augmented IL-10 response in peripheral blood mononuclear cells from heterozygous variant carriers. A parasite-driven heterozygote advantage through reduced IL-10 signaling has implications for health care utilization in regions with high allele frequencies and potentially indicates pathogen eradication strategies that target IL-10 signaling.

Association of IL10RA, IL10RB, and IL22RA Polymorphisms/Haplotypes with Susceptibility to and Clinical Manifestations of SLE.

Systemic lupus erythematosus (SLE) is characterized by an imbalance between proinflammatory and anti-inflammatory mediators. Single-nucleotide polymorphisms (SNPs) in genes coding IL10RA, IL10RB, and IL22RA could affect their expression or function and disrupt immune homeostasis. We aimed to analyze the associations of IL10RA, IL10RB, and IL22RA polymorphisms/haplotypes with patients' susceptibility to and clinical manifestations of SLE. Our study included 103 SLE patients and 99 healthy controls. The genotypes of the selected polymorphisms within IL10RA (rs10892202, rs4252270, rs3135932, rs2228055, rs2229113, and rs9610), IL10RB (rs999788, rs2834167, and rs1058867), and IL22RA (rs3795299 and rs16829204) genes were determined by TaqMan® Assays. IL10RB rs1058867 G allele carriers were significantly more frequent among the controls than among the SLE patients (76.8% vs. 61.2%; p = 0.017, OR = 0.477, 95% CI: 0.258-0.879). The IL10RB CAA haplotype was more frequent among the SLE patients than in the control group (42.7% vs. 30.7%; p = 0.027). The IL22RA rs3795299 C allele and rs16829204 CC genotype were associated with Hashimoto thyroiditis in the SLE patients (n = 103; p = 0.002 and p = 0.026, respectively), and in all the included participants (n = 202, p < 0.000 and p = 0.007, respectively), and the IL22RA CC haplotype was more frequent in the SLE patients with Hashimoto thyroiditis (p = 0.047) and in the overall participants with Hashimoto thyroiditis (n = 32, p = 0.004). The IL10RA, IL10RB, and IL22RA polymorphisms/haplotypes could be associated with SLE susceptibility and various clinical manifestations, and the IL22RA CC haplotype could be associated with Hashimoto thyroiditis.

IL10RA modulates crizotinib sensitivity in NPM1-ALK+ anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL) is a T-cell malignancy predominantly driven by a hyperactive anaplastic lymphoma kinase (ALK) fusion protein. ALK inhibitors, such as crizotinib, provide alternatives to standard chemotherapy with reduced toxicity and side effects. Children with lymphomas driven by nucleophosmin 1 (NPM1)-ALK fusion proteins achieved an objective response rate to ALK inhibition therapy of 54% to 90% in clinical trials; however, a subset of patients progressed within the first 3 months of treatment. The mechanism for the development of ALK inhibitor resistance is unknown. Through genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) activation and knockout screens in ALCL cell lines, combined with RNA sequencing data derived from ALK inhibitor-relapsed patient tumors, we show that resistance to ALK inhibition by crizotinib in ALCL can be driven by aberrant upregulation of interleukin 10 receptor subunit alpha (IL10RA). Elevated IL10RA expression rewires the STAT3 signaling pathway, bypassing otherwise critical phosphorylation by NPM1-ALK. IL-10RA expression does not correlate with response to standard chemotherapy in pediatric patients, suggesting that a combination of crizotinib and chemotherapy could prevent ALK inhibitor resistance-specific relapse.

A Novel Subset of Anti-Inflammatory CD138+ Macrophages Is Deficient in Mice with Experimental Lupus.

Dead cells accumulating in the tissues may contribute to chronic inflammation. We examined the cause of impaired apoptotic cell clearance in human and murine lupus. Dead cells accumulated in bone marrow from lupus patients but not from nonautoimmune patients undergoing myeloablation, where they were efficiently removed by macrophages (MΦ). Impaired apoptotic cell uptake by MΦ also was seen in mice treated i.p. with pristane (develop lupus) but not mineral oil (MO) (do not develop lupus). The inflammatory response to both pristane and MO rapidly depleted resident (Tim4+) large peritoneal MΦ. The peritoneal exudate of pristane-treated mice contained mainly Ly6Chi inflammatory monocytes; whereas in MO-treated mice, it consisted predominantly of a novel subset of highly phagocytic MΦ resembling small peritoneal MΦ (SPM) that expressed CD138+ and the scavenger receptor Marco. Treatment with anti-Marco-neutralizing Abs and the class A scavenger receptor antagonist polyinosinic acid inhibited phagocytosis of apoptotic cells by CD138+ MΦ. CD138+ MΦ expressed IL-10R, CD206, and CCR2 but little TNF-α or CX3CR1. They also expressed high levels of activated CREB, a transcription factor implicated in generating alternatively activated MΦ. Similar cells were identified in the spleen and lung of MO-treated mice and also were induced by LPS. We conclude that highly phagocytic, CD138+ SPM-like cells with an anti-inflammatory phenotype may promote the resolution of inflammation in lupus and infectious diseases. These SPM-like cells are not restricted to the peritoneum and may help clear apoptotic cells from tissues such as the lung, helping to prevent chronic inflammation.

Neonatal Crohn's disease with Oral ulcer as the first symptom caused by a compound heterozygote mutation in IL-10RA: a case report.

OBJECTIVE: To investigate the clinical and genetic characteristics of neonatal Crohn's disease (CD), improve recognition of neonatal CD, and reduce the number of patients that are missed or misdiagnosed. METHODS: A 10-day-old Chinese girl with oral ulcers was admitted to the Department of Neonatology. She later developed a rash and perianal disease, but without diarrhea and stool abnormalities. The patient and her parents underwent next-generation sequencing. RESULTS: The results showed that the patient carries a compound heterozygous mutation in the interleukin-10 receptor A (IL-10RA) (NM_001558.3) gene. One heterozygous mutation was c.301 c > T, P. (Arg 101 Trp) in exon 3 of IL-10RA (a missense mutation), and the other was c. 537G > A, P. (Thr 179 =) in exon 4 of IL 10RA (a synonymous mutation). The patient's father also carries the c.301 c > T, P. (Arg 101 Trp) heterozygous mutation in exon 3 of IL-10RA, whereas her mother carries the c.537G > A, P. (Thr 179 =) heterozygous mutation in exon 4 of IL-10RA. CONCLUSIONS: The results show that a compound heterozygous mutation in IL-10RA is associated with neonatal CD. Oral ulcers with a rash and perianal disease may be an early symptom of neonatal CD; therefore, such patients should undergo genetic identification as soon as possible.

IL-10 Receptor Signaling Empowers Regulatory T Cells to Control Th17 Responses and Protect from GN.

Background Th17 cells are central pathogenic mediators of autoimmune disease, including many forms of GN. IL-10 receptor signaling (IL-10R) in regulatory T cells (Tregs) has been implicated in the downregulation of Th17 cells, but the underlying molecular mechanisms and functional relevance of this process remain unclear.Methods We generated mice with Treg-specific IL-10Ra deficiency and subjected these mice to nephrotoxic serum-induced nephritis as a model of crescentic GN. Immune responses and Treg phenotypes were extensively analyzed.Results Compared with controls, mice with IL-10Ra-/- Tregs showed a spontaneously overshooting Th17 immune response. This hyper-Th17 phenotype was further boosted during GN and associated with aggravated renal injury. Notably, abrogation of IL-10Ra signaling in Tregs increased dendritic cell activation and production of Th17-inducing cytokines. In contrast, Treg trafficking and expression of chemokine receptor CCR6 remained unaffected, indicating mechanisms of Th17 control, differing from those of previously identified CCR6+ Treg17 cells. Indeed, the capacity for direct in vitro suppression of Th17 responses by IL-10Ra-/- Tregs was significantly impaired. As underlying pathology, analyses conducted in vitro and in vivo using double-fluorescent reporter mice revealed strikingly decreased IL-10 production by IL-10Ra-/- Tregs. To assess, whether reduced IL-10 could explain the hyper Th17 phenotype, competitive cotransfer experiments were performed. Supporting our concept, IL-10Ra-/- T cells differentiated into Th17 cells at much higher frequencies than wild type T cells did during GN.Conclusions IL-10R engagement optimizes Treg-mediated suppression of Th17 immunity. We hypothesize a feed-forward loop, in which IL-10Ra signaling reinforces IL-10 secretion by Tregs which potently controls Th17 development via direct and indirect mechanisms. IL-10R thus may be a promising therapeutic target for the treatment of GN.

Identification of new molecular alterations in fatal familial insomnia.

Fatal familial insomnia is a rare disease caused by a D178N mutation in combination with methionine (Met) at codon 129 in the mutated allele of PRNP (D178N-129M haplotype). FFI is manifested by sleep disturbances with insomnia, autonomic disorders and spontaneous and evoked myoclonus, among other symptoms. This study describes new neuropathological and biochemical observations in a series of eight patients with FFI. The mediodorsal and anterior nuclei of the thalamus have severe neuronal loss and marked astrocytic gliosis in every case, whereas the entorhinal cortex is variably affected. Spongiform degeneration only occurs in the entorhinal cortex. Synaptic and fine granular proteinase K digestion (PrPres) immunoreactivity is found in the entorhinal cortex but not in the thalamus. Interleukin 6, interleukin 10 receptor alpha subunit, colony stimulating factor 3 receptor and toll-like receptor 7 mRNA expression increases in the thalamus in FFI. PrPc levels are significantly decreased in the thalamus, entorhinal cortex and cerebellum in FFI. This is accompanied by a particular PrPc and PrPres band profile. Altered PrP solubility consistent with significantly reduced PrP levels in the cytoplasmic fraction and increased PrP levels in the insoluble fraction are identified in FFI cases. Amyloid-like deposits are only seen in the entorhinal cortex. The RT-QuIC assay reveals that all the FFI samples of the entorhinal cortex are positive, whereas the thalamus is positive only in three cases and the cerebellum in two cases. The present findings unveil particular neuropathological and neuroinflammatory profiles in FFI and novel characteristics of natural prion protein in FFI, altered PrPres and Scrapie PrP (abnormal and pathogenic PrP) patterns and region-dependent putative capacity of PrP seeding.

Differential T Cell Cytokine Receptivity and Not Signal Quality Distinguishes IL-6 and IL-10 Signaling during Th17 Differentiation.

How a large number of cytokines differentially signal through a small number of signal transduction pathways is not well resolved. This is particularly true for IL-6 and IL-10, which act primarily through STAT3 yet induce dissimilar transcriptional programs leading alternatively to pro- and anti-inflammatory effects. Kinetic differences in signaling, sustained to IL-10 and transient to IL-6, are critical to this in macrophages. T cells are also key targets of IL-6 and IL-10, yet how differential signaling in these cells leads to divergent cellular fates is unclear. We show that, unlike for macrophages, signal duration cannot explain the distinct effects of these cytokines in T cells. Rather, naive, activated, activated-rested, and memory CD4(+) T cells differentially express IL-6 and IL-10 receptors in an activation state-dependent manner, and this impacts downstream cytokine effects. We show a dominant role for STAT3 in IL-6-mediated Th17 subset maturation. IL-10 cannot support Th17 differentiation because of insufficient cytokine receptivity rather than signal quality. Enforced expression of IL-10Rα on naive T cells permits an IL-10-generated STAT3 signal equivalent to that of IL-6 and equally capable of promoting Th17 formation. Similarly, naive T cell IL-10Rα expression also allows IL-10 to mimic the effects of IL-6 on both Th1/Th2 skewing and Tfh cell differentiation. Our results demonstrate a key role for the regulation of receptor expression rather than signal quality or duration in differentiating the functional outcomes of IL-6 and IL-10 signaling, and identify distinct signaling properties of these cytokines in T cells compared with myeloid cells.

Synthetic Lethal Screen Demonstrates That a JAK2 Inhibitor Suppresses a BCL6-dependent IL10RA/JAK2/STAT3 Pathway in High Grade B-cell Lymphoma.

We demonstrate the usefulness of synthetic lethal screening of a conditionally BCL6-deficient Burkitt lymphoma cell line, DG75-AB7, with a library of small molecules to determine survival pathways suppressed by BCL6 and suggest mechanism-based treatments for lymphoma. Lestaurtinib, a JAK2 inhibitor and one of the hits from the screen, repressed survival of BCL6-deficient cells in vitro and reduced growth and proliferation of xenografts in vivo BCL6 deficiency in DG75-AB7 induced JAK2 mRNA and protein expression and STAT3 phosphorylation. Surface IL10RA was elevated by BCL6 deficiency, and blockade of IL10RA repressed STAT3 phosphorylation. Therefore, we define an IL10RA/JAK2/STAT3 pathway each component of which is repressed by BCL6. We also show for the first time that JAK2 is a direct BCL6 target gene; BCL6 bound to the JAK2 promoter in vitro and was enriched by ChIP-seq. The place of JAK2 inhibitors in the treatment of diffuse large B-cell lymphoma has not been defined; we suggest that JAK2 inhibitors might be most effective in poor prognosis ABC-DLBCL, which shows higher levels of IL10RA, JAK2, and STAT3 but lower levels of BCL6 than GC-DLBCL and might be usefully combined with novel approaches such as inhibition of IL10RA.

Targeted Sequencing and Immunological Analysis Reveal the Involvement of Primary Immunodeficiency Genes in Pediatric IBD: a Japanese Multicenter Study.

PURPOSE: Pediatric inflammatory bowel disease (IBD) is a heterogeneous disorder caused by multiple factors. Although genetic and immunological analyses are required for a definitive diagnosis, no reports of a comprehensive genetic study of a Japanese population are available. METHODS: In total, 35 Japanese patients <16 years of age suffering from IBD, including 27 patients aged <6 years with very early-onset IBD, were enrolled in this multicenter study. Exome and targeted gene panel sequencing was performed for all patients. Mutations in genes responsible for primary immunodeficiency diseases (PID) and clinical and immunological parameters were evaluated according to disease type. RESULTS: We identified monogenic mutations in 5 of the 35 patients (14.3 %). We identified compound heterozygous and homozygous splice-site mutations in interleukin-10 receptor A (IL-10RA) in two patients, nonsense mutations in X-linked inhibitor of apoptosis protein (XIAP) in two patients, and a missense mutation in cytochrome b beta chain in one patient. Using assays for protein expression levels, IL-10 signaling, and cytokine production, we confirmed that the mutations resulted in loss of function. For each patient, genotype was significantly associated with clinical findings. We successfully treated a patient with a XIAP mutation by allogeneic cord blood hematopoietic stem cell transplantation, and his symptoms were ameliorated completely. CONCLUSIONS: Targeted sequencing and immunological analysis are useful for screening monogenic disorders and selecting curative therapies in pediatric patients with IBD. The genes responsible for PID are frequently involved in pediatric IBD and play critical roles in normal immune homeostasis in the gastrointestinal tract.

Interleukin 1ß Mediates Intestinal Inflammation in Mice and Patients With Interleukin 10 Receptor Deficiency.

Interleukin 10 receptor (IL10R)-deficient mice develop spontaneous colitis and, similarly, patients with loss-of-function mutations in IL10R develop severe infant-onset inflammatory bowel disease. Loss of IL10R signaling in mouse and human macrophages is associated with increased production of interleukin 1ß. We demonstrated that innate immune production of IL1ß mediates colitis in IL10R-deficient mice. Transfer of Il1r1-/- CD4+ T cells into Rag1-/-/Il10rb-/- mice reduced the severity of their colitis (compared to mice that received CD4+ T cells that express IL1R), accompanied by decreased production of interferon gamma, tumor necrosis factor-α, and IL17A. In macrophages from mice without disruption of IL10R signaling or from healthy humans (controls), incubation with IL10 reduced canonical activation of the inflammasome and production of IL1ß through transcriptional and post-translational regulation of NLRP3. Lipopolysaccharide and adenosine triphosphate stimulation of macrophages from Il10rb-/- mice or IL10R-deficient patients resulted in increased production of IL1ß. Moreover, in human IL10R-deficient macrophages, lipopolysaccharide stimulation alone triggered IL1ß secretion via non-canonical, caspase 8-dependent activation of the inflammasome. We treated 2 IL10R-deficient patients with severe and treatment-refractory infant-onset inflammatory bowel disease with the IL1-receptor antagonist anakinra. Both patients had marked clinical, endoscopic, and histologic responses after 4-7 weeks. This treatment served as successful bridge to allogeneic hematopoietic stem cell transplantation in 1 patient. Our findings indicate that loss of IL10 signaling leads to intestinal inflammation, at least in part, through increased production of IL1 by innate immune cells, leading to activation of CD4+ T cells. Agents that block IL1 signaling might be used to treat patients with inflammatory bowel disease resulting from IL10R deficiency.

Investigation of Genetic Defects in Severe Combined Immunodeficiency Patients from Turkey by Targeted Sequencing.

Primary immunodeficiencies (PIDs) represent a large group of disorders with an increased susceptibility to infections. Severe combined immunodeficiency (SCID) is the most severe form of primary immunodeficiencies (PIDs) with marked T-cell lymphopenia. Investigation of the genetic aetiology using classical Sanger sequencing is associated with considerable diagnostic delay. We here established a custom-designed, next-generation sequencing (NGS)-based panel to efficiently identify disease-causing genetic defects in PID patients and applied this method in SCID patients of Turkish origin with previously undefined genetic aetiology. We used HaloPlex enrichment technology, a targeted, NGS-based method which was designed to diagnose patients with SCID and other PIDs. Our HaloPlex panel included a total of 356 PID-related genes, and we searched disease-causing mutations in 19 Turkish SCID patients without a genetic diagnosis. The coverage of targeted regions ranged from 97.47% to 99.62% with an average of 98.31% for all patients. All known SCID genes were covered with a percentage of at least 97.3%. We made a genetic diagnosis in six of 19 (33%) patients, including four novel disease-causing mutations identified in RAG1, JAK3 and IL2RG, respectively. We showed that this NGS-based method can provide rapid genetic diagnosis for patients suffering from SCID, potentially facilitating clinical treatment decisions.

Development and Function of Immune Cells in an Adolescent Patient With a Deficiency in the Interleukin-10 Receptor.

OBJECTIVE: Monogenic defects in the interleukin-10 (IL-10) pathway are extremely rare and cause infantile-onset inflammatory bowel disease (IBD)-like pathology. Understanding how immune responses are dysregulated in monogenic IBD-like diseases can provide valuable insight in "classical" IBD pathogenesis. Here, we studied long-term immune cell development and function in an adolescent IL-10 receptor (IL10RA)-deficient patient who presented in infancy with severe colitis and fistulizing perianal disease and is currently treated with immune suppressants. METHODS: Biomaterial was collected from the IL10RA-deficient patient, pediatric patients with IBD, and healthy controls. The frequency and phenotype of immune cells were determined in peripheral blood and intestinal biopsies by flow cytometry and immunohistochemistry. Functional changes in monocyte-derived dendritic cells and T cells were assessed by in vitro activation assays. RESULTS: The IL10RA-deficient immune system developed normally with respect to numbers and phenotype of circulating immune cells. Despite normal co-stimulatory molecule expression, bacterial lipopolysaccharide-stimulated monocyte-derived dendritic cells from the IL10RA-deficient patient released increased amounts of tumor necrosis factor α compared to healthy controls. Upon T-cell receptor ligation, IL10RA-deficient peripheral blood mononuclear cells released increased amounts of T-cell cytokines interferon γ and IL-17 agreeing with high numbers of T-bet and IL-17 cells in intestinal biopsies taken at disease onset. In vitro, the immunosuppressive drug thalidomide used to treat the patient's decreased peripheral blood mononuclear cell-derived tumor necrosis factor production. CONCLUSIONS: With time and during immunosuppressive treatment the IL10RA-deficient immune system develops relatively normally. Upon activation, IL-10 is crucial for controlling excessive inflammatory cytokine release by dendritic cells and preventing interferon γ and IL-17-mediated T-cell responses.

Exome sequencing analysis reveals variants in primary immunodeficiency genes in patients with very early onset inflammatory bowel disease.

BACKGROUND & AIMS: Very early onset inflammatory bowel disease (VEO-IBD), IBD diagnosed at 5 years of age or younger, frequently presents with a different and more severe phenotype than older-onset IBD. We investigated whether patients with VEO-IBD carry rare or novel variants in genes associated with immunodeficiencies that might contribute to disease development. METHODS: Patients with VEO-IBD and parents (when available) were recruited from the Children's Hospital of Philadelphia from March 2013 through July 2014. We analyzed DNA from 125 patients with VEO-IBD (age, 3 wk to 4 y) and 19 parents, 4 of whom also had IBD. Exome capture was performed by Agilent SureSelect V4, and sequencing was performed using the Illumina HiSeq platform. Alignment to human genome GRCh37 was achieved followed by postprocessing and variant calling. After functional annotation, candidate variants were analyzed for change in protein function, minor allele frequency less than 0.1%, and scaled combined annotation-dependent depletion scores of 10 or less. We focused on genes associated with primary immunodeficiencies and related pathways. An additional 210 exome samples from patients with pediatric IBD (n = 45) or adult-onset Crohn's disease (n = 20) and healthy individuals (controls, n = 145) were obtained from the University of Kiel, Germany, and used as control groups. RESULTS: Four hundred genes and regions associated with primary immunodeficiency, covering approximately 6500 coding exons totaling more than 1 Mbp of coding sequence, were selected from the whole-exome data. Our analysis showed novel and rare variants within these genes that could contribute to the development of VEO-IBD, including rare heterozygous missense variants in IL10RA and previously unidentified variants in MSH5 and CD19. CONCLUSIONS: In an exome sequence analysis of patients with VEO-IBD and their parents, we identified variants in genes that regulate B- and T-cell functions and could contribute to pathogenesis. Our analysis could lead to the identification of previously unidentified IBD-associated variants.

IFN-γ-mediated induction of an apical IL-10 receptor on polarized intestinal epithelia.

Cytokines secreted at sites of inflammation impact the onset, progression, and resolution of inflammation. In this article, we investigated potential proresolving mechanisms of IFN-γ in models of inflammatory bowel disease. Guided by initial microarray analysis, in vitro studies revealed that IFN-γ selectively induced the expression of IL-10R1 on intestinal epithelia. Further analysis revealed that IL-10R1 was expressed predominantly on the apical membrane of polarized epithelial cells. Receptor activation functionally induced canonical IL-10 target gene expression in epithelia, concomitant with enhanced barrier restitution. Furthermore, knockdown of IL-10R1 in intestinal epithelial cells results in impaired barrier function in vitro. Colonic tissue isolated from murine colitis revealed that levels of IL-10R1 and suppressor of cytokine signaling 3 were increased in the epithelium and coincided with increased tissue IFN-γ and IL-10 cytokines. In parallel, studies showed that treatment of mice with rIFN-γ was sufficient to drive expression of IL-10R1 in the colonic epithelium. Studies of dextran sodium sulfate colitis in intestinal epithelial-specific IL-10R1-null mice revealed a remarkable increase in disease susceptibility associated with increased intestinal permeability. Together, these results provide novel insight into the crucial and underappreciated role of epithelial IL-10 signaling in the maintenance and restitution of epithelial barrier and of the temporal regulation of these pathways by IFN-γ.

Interleukin-10 receptor-1 expression in monocyte-derived antigen-presenting cell populations: dendritic cells partially escape from IL-10's inhibitory mechanisms.

Interleukin (IL)-10 is an important immunoregulatory cytokine that mediates its effects via a transmembrane receptor complex consisting of two different chains, IL-10R1 and IL-10R2. While IL-10R2 is ubiquitously expressed and does not bind IL-10 primarily, the expression of IL-10R1 determines cellular responsiveness. However, the current knowledge about the expression and regulation of IL-10R1 is still limited. Here we analyzed the expression of IL-10R1 on monocytic cells and demonstrated that human blood monocytes carried about 720 IL-10-binding sites on their surface. Compared with lymphocytes and various tissue cells and tissues, blood monocytes expressed the highest IL-10R1 levels. The in vitro differentiation of these cells into macrophages provoked a further increase of IL-10R1 surface expression. In contrast, their differentiation into myeloid dendritic cells (mDCs) resulted in reduced surface IL-10R1 levels. The different IL-10R1 levels expressed by monocyte-derived antigen-presenting cell populations were reflected in their different responsiveness toward IL-10. Importantly, also in vivo developed immature macrophages and mDCs showed different IL-10 sensitivity. These data suggest that, compared with monocytes and macrophages, mDCs partially escape from IL-10's inhibitory mechanisms by downregulating IL-10R1.

IL-27 receptor signalling restricts the formation of pathogenic, terminally differentiated Th1 cells during malaria infection by repressing IL-12 dependent signals.

The IL-27R, WSX-1, is required to limit IFN-γ production by effector CD4⁺ T cells in a number of different inflammatory conditions but the molecular basis of WSX-1-mediated regulation of Th1 responses in vivo during infection has not been investigated in detail. In this study we demonstrate that WSX-1 signalling suppresses the development of pathogenic, terminally differentiated (KLRG-1⁺) Th1 cells during malaria infection and establishes a restrictive threshold to constrain the emergent Th1 response. Importantly, we show that WSX-1 regulates cell-intrinsic responsiveness to IL-12 and IL-2, but the fate of the effector CD4⁺ T cell pool during malaria infection is controlled primarily through IL-12 dependent signals. Finally, we show that WSX-1 regulates Th1 cell terminal differentiation during malaria infection through IL-10 and Foxp3 independent mechanisms; the kinetics and magnitude of the Th1 response, and the degree of Th1 cell terminal differentiation, were comparable in WT, IL-10R1⁻/⁻ and IL-10⁻/⁻ mice and the numbers and phenotype of Foxp3⁺ cells were largely unaltered in WSX-1⁻/⁻ mice during infection. As expected, depletion of Foxp3⁺ cells did not enhance Th1 cell polarisation or terminal differentiation during malaria infection. Our results significantly expand our understanding of how IL-27 regulates Th1 responses in vivo during inflammatory conditions and establishes WSX-1 as a critical and non-redundant regulator of the emergent Th1 effector response during malaria infection.

A Mendelian predisposition to B-cell lymphoma caused by IL-10R deficiency.

Monogenic interleukin-10 (IL-10) and IL-10 receptor (IL-10R) deficiencies cause very early onset severe inflammatory bowel disease. Here, we report that 5 patients with an IL-10R1 (n = 1) or IL-10R2 (n = 4) deficiency developed B-cell non-Hodgkin lymphoma between the ages of 5 and 6 years (which was recurrent in 1 patient). These lymphomas had some of the characteristics of diffuse large B-cell lymphomas and contained monoclonal, Epstein-Barr virus-negative germinal center B cells. The tumors displayed a remarkably homogeneous signature, with original activation of the nuclear factor κB pathway and a decrease in intratumor T-cell infiltration. Hence, IL-10R deficiency is associated with a high risk of developing B-cell lymphoma. Our results revealed an unexpected role of the IL-10R pathway in lymphomagenesis.

Monogenic autoinflammatory diseases: Cytokinopathies.

Rapid advances in genetics are providing unprecedented insight into functions of the innate immune system with identification of the mutations that cause monogenic autoinflammatory disease. Cytokine antagonism is profoundly effective in a subset of these conditions, particularly those associated with increased interleukin-1 (IL-1) activity, the inflammasomopathies. These include syndromes where the production of IL-1 is increased by mutation of innate immune sensors such as NLRP3, upstream signalling molecules such as PSTPIP1 and receptors or downstream signalling molecules, such as IL-1Ra. Another example of this is interferon (IFN) and the interferonopathies, with mutations in the sensors STING and MDA5, the upstream signalling regulator AP1S3, and a downstream inhibitor of IFN signalling, ISG15. We propose that this can be extended to cytokines such as IL-36, with mutations in IL-36Ra, and IL-10, with mutations in IL-10RA and IL-10RB, however mutations in sensors or upstream signalling molecules are yet to be described in these instances. Additionally, autoinflammatory diseases can be caused by multiple cytokines, for example with the activation of NF-κB/Rel, for which we propose the term Relopathies. This nosology is limited in that some cytokine pathways may be degenerate in their generation or execution, however provides insight into likely autoinflammatory disease candidates and the cytokines with which newly identified mutations may be associated, and therefore targeted.