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.

Biallelic TLR4 deficiency in humans.

BACKGROUND: Toll-like receptors (TLRs) mediate functions for host defense and inflammatory responses. TLR4 recognizes LPS, a component of gram-negative bacteria as well as host-derived endogenous ligands such as S100A8 and S100A9 proteins. OBJECTIVE: We sought to report phenotype and cellular function of individuals with complete TLR4 deficiency. METHODS: We performed genome sequencing and investigated exome and genome sequencing databases. Cellular responses were studied on primary monocytes, macrophages, and neutrophils, as well as cell lines using flow cytometry, reporter, and cytokine assays. RESULTS: We identified 2 individuals in a family of Qatari origin carrying a homozygous stop codon variant p.Q188X in TLR4 presenting with a variable phenotype (asymptomatic and inflammatory bowel disease consistent with severe perianal Crohn disease). A third individual with homozygous p.Y794X was identified in a population database. In contrast to hypomorphic polymorphisms p.D299G and p.T399I, the variants p.Q188X and p.Y794X completely abrogated LPS-induced cytokine responses whereas TLR2 response was normal. TLR4 deficiency causes a neutrophil CD62L shedding defect, whereas antimicrobial activity toward intracellular Salmonella was intact. CONCLUSIONS: Biallelic TLR4 deficiency in humans causes an inborn error of immunity in responding to LPS. This complements the spectrum of known primary immunodeficiencies, in particular myeloid differentiation primary response 88 (MYD88) or the IL-1 receptor-associated kinase 4 (IRAK4) deficiency that are downstream of TLR4 and TLR2 signaling.

Hermansky-Pudlak syndrome type 1 causes impaired anti-microbial immunity and inflammation due to dysregulated immunometabolism.

Hermansky-Pudlak syndrome (HPS) types 1 and 4 are caused by defective vesicle trafficking. The mechanism for Crohn's disease-like inflammation, lung fibrosis, and macrophage lipid accumulation in these patients remains enigmatic. The aim of this study is to understand the cellular basis of inflammation in HPS-1. We performed mass cytometry, proteomic and transcriptomic analyses to investigate peripheral blood cells and serum of HPS-1 patients. Using spatial transcriptomics, granuloma-associated signatures in the tissue of an HPS-1 patient with granulomatous colitis were dissected. In vitro studies were conducted to investigate anti-microbial responses of HPS-1 patient macrophages and cell lines. Monocytes of HPS-1 patients exhibit an inflammatory phenotype associated with dysregulated TNF, IL-1α, OSM in serum, and monocyte-derived macrophages. Inflammatory macrophages accumulate in the intestine and granuloma-associated macrophages in HPS-1 show transcriptional signatures suggestive of a lipid storage and metabolic defect. We show that HPS1 deficiency leads to an altered metabolic program and Rab32-dependent amplified mTOR signaling, facilitated by the accumulation of mTOR on lysosomes. This pathogenic mechanism translates into aberrant bacterial clearance, which can be rescued with mTORC1 inhibition. Rab32-mediated mTOR signaling acts as an immuno-metabolic checkpoint, adding to the evidence that defective bioenergetics can drive hampered anti-microbial activity and contribute to inflammation.

An Integrated Taxonomy for Monogenic Inflammatory Bowel Disease.

BACKGROUND & AIMS: Monogenic forms of inflammatory bowel disease (IBD) illustrate the essential roles of individual genes in pathways and networks safeguarding immune tolerance and gut homeostasis. METHODS: To build a taxonomy model, we assessed 165 disorders. Genes were prioritized based on penetrance of IBD and disease phenotypes were integrated with multi-omics datasets. Monogenic IBD genes were classified by (1) overlapping syndromic features, (2) response to hematopoietic stem cell transplantation, (3) bulk RNA-sequencing of 32 tissues, (4) single-cell RNA-sequencing of >50 cell subsets from the intestine of healthy individuals and patients with IBD (pediatric and adult), and (5) proteomes of 43 immune subsets. The model was validated by addition of newly identified monogenic IBD defects. As a proof-of-concept, we explore the intersection between immunometabolism and antimicrobial activity for a group of disorders (G6PC3/SLC37A4). RESULTS: Our quantitative integrated taxonomy defines the cellular landscape of monogenic IBD gene expression across 102 genes with high and moderate penetrance (81 in the model set and 21 genes in the validation set). We illustrate distinct cellular networks, highlight expression profiles across understudied cell types (e.g., CD8+ T cells, neutrophils, epithelial subsets, and endothelial cells) and define genotype-phenotype associations (perianal disease and defective antimicrobial activity). We illustrate processes and pathways shared across cellular compartments and phenotypic groups and highlight cellular immunometabolism with mammalian target of rapamycin activation as one of the converging pathways. There is an overlap of genes and enriched cell-specific expression between monogenic and polygenic IBD. CONCLUSION: Our taxonomy integrates genetic, clinical and multi-omic data; providing a basis for genomic diagnostics and testable hypotheses for disease functions and treatment responses.

Gain-of-function variants in SYK cause immune dysregulation and systemic inflammation in humans and mice.

Spleen tyrosine kinase (SYK) is a critical immune signaling molecule and therapeutic target. We identified damaging monoallelic SYK variants in six patients with immune deficiency, multi-organ inflammatory disease such as colitis, arthritis and dermatitis, and diffuse large B cell lymphomas. The SYK variants increased phosphorylation and enhanced downstream signaling, indicating gain of function. A knock-in (SYK-Ser544Tyr) mouse model of a patient variant (p.Ser550Tyr) recapitulated aspects of the human disease that could be partially treated with a SYK inhibitor or transplantation of bone marrow from wild-type mice. Our studies demonstrate that SYK gain-of-function variants result in a potentially treatable form of inflammatory disease.

Loss of IL-10 signaling in macrophages limits bacterial killing driven by prostaglandin E2.

Loss of IL-10 signaling in macrophages (Mφs) leads to inflammatory bowel disease (IBD). Induced pluripotent stem cells (iPSCs) were generated from an infantile-onset IBD patient lacking a functional IL10RB gene. Mφs differentiated from IL-10RB-/- iPSCs lacked IL-10RB mRNA expression, were unable to phosphorylate STAT3, and failed to reduce LPS induced inflammatory cytokines in the presence of exogenous IL-10. IL-10RB-/- Mφs exhibited a striking defect in their ability to kill Salmonella enterica serovar Typhimurium, which was rescuable after experimentally introducing functional copies of the IL10RB gene. Genes involved in synthesis and receptor pathways for eicosanoid prostaglandin E2 (PGE2) were more highly induced in IL-10RB-/- Mφs, and these Mφs produced higher amounts of PGE2 after LPS stimulation compared with controls. Furthermore, pharmacological inhibition of PGE2 synthesis and PGE2 receptor blockade enhanced bacterial killing in Mφs. These results identify a regulatory interaction between IL-10 and PGE2, dysregulation of which may drive aberrant Mφ activation and impaired host defense contributing to IBD pathogenesis.

The Short Chain Fatty Acid Butyrate Imprints an Antimicrobial Program in Macrophages.

Host microbial cross-talk is essential to maintain intestinal homeostasis. However, maladaptation of this response through microbial dysbiosis or defective host defense toward invasive intestinal bacteria can result in chronic inflammation. We have shown that macrophages differentiated in the presence of the bacterial metabolite butyrate display enhanced antimicrobial activity. Butyrate-induced antimicrobial activity was associated with a shift in macrophage metabolism, a reduction in mTOR kinase activity, increased LC3-associated host defense and anti-microbial peptide production in the absence of an increased inflammatory cytokine response. Butyrate drove this monocyte to macrophage differentiation program through histone deacetylase 3 (HDAC3) inhibition. Administration of butyrate induced antimicrobial activity in intestinal macrophages in vivo and increased resistance to enteropathogens. Our data suggest that (1) increased intestinal butyrate might represent a strategy to bolster host defense without tissue damaging inflammation and (2) that pharmacological HDAC3 inhibition might drive selective macrophage functions toward antimicrobial host defense.

Permethrin pesticide induces NURR1 up-regulation in dopaminergic cell line: Is the pro-oxidant effect involved in toxicant-neuronal damage?

The mechanisms associated to the development of neurodegeneration due to pesticide exposure are not clear yet. In this study we evaluated how permethrin pesticide (PERM) can influence the Nurr1 gene and protein expression, and if a pro-oxidant activity of the pesticide contributes to up-regulation of Nurr1 in a dopaminergic cell line. Incubation of PC12 cells with 1µM PERM for 72h, leads to over expression of Nurr1 gene. This effect occurs with both corn oil and extra virgin olive oil (EVO) used to solubilize the toxicant. In order to investigate if the Nurr1 up-regulation induced by PERM, was associated to the pro-oxidant activity of the pesticide, anti-oxidants as glutathione (GSH), tocotrienols (TOC) and Electrolyzed Reduced Water (ERW) were tested. RT-PCR of Nurr1 showed that its up-regulation was significantly reduced in the presence of antioxidants, especially by addition of ERW. Western-blot analysis reveals that ERW was able to counterbalance the up-regulation of Nurr1 protein induced by permethrin exposure.

A biallelic mutation in IL6ST encoding the GP130 co-receptor causes immunodeficiency and craniosynostosis.

Multiple cytokines, including interleukin 6 (IL-6), IL-11, IL-27, oncostatin M (OSM), and leukemia inhibitory factor (LIF), signal via the common GP130 cytokine receptor subunit. In this study, we describe a patient with a homozygous mutation of IL6ST (encoding GP130 p.N404Y) who presented with recurrent infections, eczema, bronchiectasis, high IgE, eosinophilia, defective B cell memory, and an impaired acute-phase response, as well as skeletal abnormalities including craniosynostosis. The p.N404Y missense substitution is associated with loss of IL-6, IL-11, IL-27, and OSM signaling but a largely intact LIF response. This study identifies a novel immunodeficiency with phenotypic similarities to STAT3 hyper-IgE syndrome caused by loss of function of GP130.

In vivo biocompatibility of p(HPMAm-lac)-PEG hydrogels hybridized with hyaluronan.

The present study reports on the biocompatibility in vivo after intramuscular and subcutaneous administration in Balb/c mice of vinyl sulphone bearing p(HPMAm-lac1-2)-PEG-p(HPMAm-lac1-2)/thiolated hyaluronic acid hydrogels, designed as novel injectable biomaterials for potential application in the fields of tissue engineering and regenerative medicine. Ultrasonography, used as a method to study hydrogel gelation and residence time in vivo, showed that, upon injection, the biomaterial efficiently formed a hydrogel by simultaneous thermal gelation and Michael Addition cross-linking forming a viscoelastic spherical depot at the injection site. The residence time in vivo (20 days) was found to be shorter than that observed in vitro (32 days), indicating that the injected hydrogel was resorbed not only by chemical hydrolysis but also by cellular metabolism and/or enzymatic activity. Systemic biocompatibility was tested by analysing routine haematological parameters at different time-points (7, 14 and 21 days after administration) and histology of the main organs, including the haematopoietic system. No statistically significant difference between parameters of the saline-treated group and those of the hydrogel-treated group was found. Importantly, a time-dependent decrease of important pro-inflammatory cytokines (TREM1 (Triggering Receptor Expressed on Myeloid cells-1), tumour necrosis factor-α and interleukin-1ß) in cultured bone marrow cells extracted from hydrogel treated mice was observed, possibly correlated to the anti-inflammatory effect of hyaluronic acid released in time as hydrogel degraded. Copyright © 2016 John Wiley & Sons, Ltd.

INF-γ encoding plasmid administration triggers bone loss and disrupts bone marrow microenvironment.

IFN-γ is a pleotropic cytokine produced in the bone microenvironment. Although IFN-γ is known to play a critical role on bone remodeling, its function is not fully elucidated. Consistently, outcomes on the effects of IFN-γ recombinant protein on bone loss are contradictory among reports. In our work we explored, for the first time, the role of IFN-γ encoding plasmid (pIFN-γ) in a mouse model of osteopenia induced by ovariectomy and in the sham-operated counterpart to estimate its effects in skeletal homeostasis. Ovariectomy produced a dramatic decrease of bone mineral density (BMD). pINF-γ injected mice showed a pathologic bone and bone marrow phenotype; the disrupted cortical and trabecular bone microarchitecture was accompanied by an increased release of pro-inflammatory cytokine by bone marrow cells. Moreover, mesenchymal stem cells' (MSCs) commitment to osteoblast was found impaired, as evidenced by the decline of osterix-positive (Osx+) cells within the mid-diaphyseal area of femurs. For instance, a reduction and redistribution of CXCL12 cells have been found, in accordance with bone marrow morphological alterations. As similar effects were observed both in sham-operated and in ovariectomized mice, our studies proved that an increased IFN-γ synthesis in bone marrow might be sufficient to induce inflammatory and catabolic responses even in the absence of pathologic predisposing substrates. In addition, the obtained data might raise questions about pIFN-γ's safety when it is used as vaccine adjuvant.

Administration of DNA Plasmid Coding Protein Aggregating Domain Induces Inflammatory Bone Loss.

BACKGROUND: Plasmids coding protein aggregation polypeptides from different sources have been proposed as genetic adjuvants for DNA vaccines. We reported that a plasmid (pATRex), encompassing the DNA sequence for the von Willebrand A (vWA/A) domain of the Anthrax Toxin Receptor-1 (ANTXR-1, alias TEM8, Tumor Endothelial Marker 8), acts as strong immune adjuvant by inducing formation of insoluble intracellular aggregates and subsequent cell death. OBJECTIVE: In the present study we addressed the question of whether there is any substantial immunotoxicity associated with the use of self-aggregating proteins as genetic adjuvants. METHODS & RESULTS: Here we report, by mean of histology, X-ray and molecular examinations of bone specimens, the unexpected finding that intramuscular injection of pATRex in mice triggers, per se, severe bone loss (osteoporosis) independently from the sex and genotype of the treated animals. CONCLUSION: Even though the study suggests that proteinaceous "sticky " adjuvants are unlikely to find their way into practical vaccination, the information gained is of value as ATRex injections could provide an additional, simplified, mouse model of osteoporosis. Moreover, our results provide experimental support to the hypothesis that proteotoxic aggregates chronically activate the innate immune system in amyloid and aggregosome associated disorders.

Plasmid DNA-coding p62 as a bone effective anti-inflammatory/anabolic agent.

We recently reported that a DNA plasmid coding p62-SQSTM1 acts as an effective anti tumor vaccine against both transplantable mouse tumors and canine spontaneous mammary neoplasms. Here we report the unexpected finding that intramuscular delivery of p62 DNA exerts a powerful anti-osteoporotic activity in a mouse model of inflammatory bone loss (i.e, ovariectomy) by combining bone-sparing and osteo-synthetic effects. Notably, the suppression of osteoporosis by p62DNA was associated with a sharp down-regulation of master inflammatory cytokines, and up-regulation of endogenous p62 protein by bone-marrow stromal cells. The present data provide a solid rational to apply p62 DNA vaccine as a safe, new therapeutic for treatment of inflammatory related bone loss diseases.

The dual face of parathyroid hormone and prostaglandins in the osteoimmune system.

The microenvironment of bone marrow, an extraordinarily heterogeneous and dynamic system, is populated by bone and immune cells, and its functional dimension has been at the forefront of recent studies in the field of osteoimmunology. The interaction of both marrow niches supports self-renewal, differentiation, and homing of the hematopoietic stem cells and provides the essential regulatory molecules for osteoblast and osteoclast homeostasis. Impaired signaling within the niches results in a pathological tableau and enhances disease, including osteoporosis and arthritis, or the rejection of hematopoietic stem cell transplants. Discovering the anabolic players that control these mechanisms has become warranted. In this review, we focus on parathyroid hormone (PTH) and prostaglandins (PGs), potent molecular mediators, both of which carry out a multitude of functions, particularly in bone lining cells and T cells. These two regulators proved to be promising therapeutic agents when strictly clinical protocols on dose treatments were applied.

The functional VNTR MNS16A of the TERT gene is associated with human longevity in a population of Central Italy.

BACKGROUND: Telomerase, encoded by TERT, is the ribonucleoprotein polymerase that maintains telomere ends and it plays a crucial role in cellular senescence. TERT single nucleotide polymorphisms (SNPs) have been associated both with various malignancies and telomere length (TL). The association of TERT SNPs with longevity remains uncertain and varies with ethnicity. The aim of this study was to investigate whether the functional variable number of tandem repeat (VNTR) MNS16A of TERT is associated with longevity. METHODS: MNS16A genotypes have been determined for 1072 unrelated healthy individuals from Central Italy (18-106 years old) divided into three gender-specific age classes defined according to demographic information and accounting for the different survivals between sexes: for men (women), the first class consists of individuals <66 years old (<73 years old), the second class of individuals 66-88 years old (73-91 years old), and the third class of individuals >88 years old (>91 years old). TL was assessed using genomic DNA from whole blood of 72 selected individuals by a multiplex real-time PCR assay. RESULTS: MNS16A appears associated to longevity, showing significant associations in Comparison 2 (Age Class 3 vs. Age Class 2) under both additive (odds ratio [O.R.] 0.749; p=0.019) and dominant (O.R. 0.579; p=0.011) models. The MNS16A*L allele is significantly underrepresented in Age Class 3 (O.R. 0.759; p=0.020) compared to Age Class 2. A significant telomere attrition is reported along the three age classes (p=0.0001), that remains significant only in L*/L* genotype carriers (p=0.002) when the analysis was conducted according to MNS16A genotype. CONCLUSIONS: The TERT MNS16A*L allele appears negatively associated with longevity. The concomitant significant telomere cross sectional attrition rate observed for L*/L* genotype suggests that this polymorphism could influence human longevity by affecting TL.