CCR2 promotes monocyte recruitment and intestinal inflammation in mice lacking the interleukin-10 receptor

Macrophages are a heterogeneous population of mononuclear phagocytes abundantly distributed throughout the intestinal compartments that adapt to microenvironmental specific cues. In adult mice, the majority of intestinal macrophages exhibit a mature phenotype and are derived from blood monocytes. In the steady-state, replenishment of these cells is reduced in the absence of the chemokine receptor CCR2. Within the intestine of mice with colitis, there is a marked increase in the accumulation of immature macrophages that demonstrate an inflammatory phenotype. Here, we asked whether CCR2 is necessary for the development of colitis in mice lacking the receptor for IL10. We compared the development of intestinal inflammation in mice lacking IL10RA or both IL10RA and CCR2. The absence of CCR2 interfered with the accumulation of immature macrophages in IL10R-deficient mice, including a novel population of rounded submucosal Iba1+ cells, and reduced the severity of colitis in these mice. In contrast, the absence of CCR2 did not reduce the augmented inflammatory gene expression observed in mature intestinal macrophages isolated from mice lacking IL10RA. These data suggest that both newly recruited CCR2-dependent immature macrophages and CCR2-independent residual mature macrophages contribute to the development of intestinal inflammation observed in IL10R-deficient mice.

Brain Tissue-Derived Extracellular Vesicle Mediated Therapy in the Neonatal Ischemic Brain

Hypoxic-Ischemic Encephalopathy (HIE) in the brain is the leading cause of morbidity and mortality in neonates and can lead to irreparable tissue damage and cognition. Thus, investigating key mediators of the HI response to identify points of therapeutic intervention has significant clinical potential. Brain repair after HI requires highly coordinated injury responses mediated by cell-derived extracellular vesicles (EVs). Studies show that stem cell-derived EVs attenuate the injury response in ischemic models by releasing neuroprotective, neurogenic, and anti-inflammatory factors. In contrast to 2D cell cultures, we successfully isolated and characterized EVs from whole brain rat tissue (BEV) to study the therapeutic potential of endogenous EVs. We showed that BEVs decrease cytotoxicity in an ex vivo oxygen glucose deprivation (OGD) brain slice model of HI in a dose- and time-dependent manner. The minimum therapeutic dosage was determined to be 25 μg BEVs with a therapeutic application time window of 4–24 h post-injury. At this therapeutic dosage, BEV treatment increased anti-inflammatory cytokine expression. The morphology of microglia was also observed to shift from an amoeboid, inflammatory phenotype to a restorative, anti-inflammatory phenotype between 24–48 h of BEV exposure after OGD injury, indicating a shift in phenotype following BEV treatment. These results demonstrate the use of OWH brain slices to facilitate understanding of BEV activity and therapeutic potential in complex brain pathologies for treating neurological injury in neonates.

Whole-Tissue Deconvolution and scRNAseq Analysis Identify Altered Endometrial Cellular Compositions and Functionality Associated With Endometriosis

The uterine lining (endometrium) exhibits a pro-inflammatory phenotype in women with endometriosis, resulting in pain, infertility, and poor pregnancy outcomes. The full complement of cell types contributing to this phenotype has yet to be identified, as most studies have focused on bulk tissue or select cell populations. Herein, through integrating whole-tissue deconvolution and single-cell RNAseq, we comprehensively characterized immune and nonimmune cell types in the endometrium of women with or without disease and their dynamic changes across the menstrual cycle. We designed metrics to evaluate specificity of deconvolution signatures that resulted in single-cell identification of 13 novel signatures for immune cell subtypes in healthy endometrium. Guided by statistical metrics, we identified contributions of endometrial epithelial, endothelial, plasmacytoid dendritic cells, classical dendritic cells, monocytes, macrophages, and granulocytes to the endometrial pro-inflammatory phenotype, underscoring roles for nonimmune as well as immune cells to the dysfunctionality of this tissue.

Prevalence of Pathogenic and Potentially Pathogenic Inborn Error of Immunity Associated Variants in Children with Severe Sepsis

Purpose Our understanding of inborn errors of immunity is increasing; however, their contribution to pediatric sepsis is unknown. Methods We used whole-exome sequencing (WES) to characterize variants in genes related to monogenic immunologic disorders in 330 children admitted to intensive care for severe sepsis. We defined candidate variants as rare variants classified as pathogenic or potentially pathogenic in QIAGEN’s Human Gene Mutation Database or novel null variants in a disease-consistent inheritance pattern. We investigated variant correlation with infection and inflammatory phenotype. Results More than one in two children overall and three of four African American children had immunodeficiency-associated variants. Children with variants had increased odds of isolating a blood or urinary pathogen (blood: OR 2.82, 95% CI: 1.12–7.10, p = 0.023, urine: OR: 8.23, 95% CI: 1.06–64.11, p = 0.016) and demonstrating increased inflammation with hyperferritinemia (ferritin $$\ge 500$$ ≥ 500 ng/mL, OR: 2.16, 95% CI: 1.28–3.66, p = 0.004), lymphopenia (lymphocyte count < 1000/µL, OR: 1.66, 95% CI: 1.06 – 2.60, p = 0.027), thrombocytopenia (platelet count < 150,000/µL, OR: 1.76, 95% CI: 1.12–2.76, p = 0.013), and CRP greater than 10 mg/dl (OR: 1.71, 95% CI: 1.10–2.68, p = 0.017). They also had increased odds of requiring extracorporeal membrane oxygenation (ECMO, OR: 4.19, 95% CI: 1.21–14.5, p = 0.019). Conclusion Herein, we describe the genetic findings in this severe pediatric sepsis cohort and their microbiologic and immunologic significance, providing evidence for the phenotypic effect of these variants and rationale for screening children with life-threatening infections for potential inborn errors of immunity.

IL-36γ promotes psoriasis-like features in keratinocytes in an imiquimod-induced murine model of psoriasis

IntroductionPsoriasis is a recurrent, chronic inflammatory skin disease with complex pathogenesis. The disease imposes a heavy burden on patients. Interleukin (IL)-36γ belongs to the IL-36 family and is predominantly expressed by epithelial cells. IL-36γ is upregulated in psoriasis lesions. However, the effects of IL-36γ in keratinocytes remain unclear.Material and methodsEighteen IL-36γ-deficient mice were divided into three groups: the vaseline group, the imiquimod (IMQ) group, and the IMQ/IL-36γ group. Vaseline or IMQ was administered for 6 consecutive days. The severity of psoriasis-like lesions was evaluated using a modified Psoriasis Area and Severity Index (PASI) scoring system. Production of cytokines and expression of differentiation markers were assessed by immunohistochemistry.ResultsIMQ-induced psoriasis lesions were significantly more severe in IMQ/IL-36γ-treated mice compared with vaseline-treated and IMQ-treated mice, as shown by an exacerbated inflammatory phenotype, increased numbers of blood vessels, increased infiltration of cells, and increased epidermal thickness. Expression of loricrin and keratin 5 in skin lesions was decreased following treatment with IL-36γ. Levels of IL-17A, interferon-γ, β-catenin and Dickkopf-related protein 1 were elevated in keratinocytes within psoriatic lesions following IL-36γ stimulation.ConclusionsTogether, these data showed that IL-36γ contribute to abnormal keratinocytes proliferation and keratinocyte-related proinflammatory cytokines, and suggest that IL-36γ may play an important role in the pathogenesis of psoriasis.

A virus-specific monocyte inflammatory phenotype is induced by SARS-CoV-2 at the immune–epithelial interface

Infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) provokes a potentially fatal pneumonia with multiorgan failure, and high systemic inflammation. To gain mechanistic insight and ferret out the root of this immune dysregulation, we modeled, by in vitro coculture, the interactions between infected epithelial cells and immunocytes. A strong response was induced in monocytes and B cells, with a SARS-CoV-2–specific inflammatory gene cluster distinct from that seen in influenza A or Ebola virus-infected cocultures, and which reproduced deviations reported in blood or lung myeloid cells from COVID-19 patients. A substantial fraction of the effect could be reproduced after individual transfection of several SARS-CoV-2 proteins (Spike and some nonstructural proteins), mediated by soluble factors, but not via transcriptional induction. This response was greatly muted in monocytes from healthy children, perhaps a clue to the age dependency of COVID-19. These results suggest that the inflammatory malfunction in COVID-19 is rooted in the earliest perturbations that SARS-CoV-2 induces in epithelia.

LY6S, a New Interferon-Inducible Human Member of the Ly6a-Subfamily Expressed by Spleen Cells and Associated with Inflammation and Viral Resistance

Syntenic genomic loci on human chromosome 8 (hChr8) and mouse chromosome 15 (mChr15) code for LY6/Ly6 (lymphocyte antigen 6) family proteins. The 23 murine Ly6 family genes include eight genes that are flanked by the murine Ly6e and Ly6l genes and form an Ly6 subgroup referred to here as the Ly6a subfamily gene cluster. Ly6a, also known as Sca1 (Stem Cell Antigen-1) and TAP (T-cell activating protein), is a member of the Ly6a subfamily gene cluster. No LY6 genes have been annotated within the syntenic LY6E to LY6L human locus. We report here on LY6S, a solitary human LY6 gene that is syntenic with the murine Ly6a subfamily gene cluster, and with which it shares a common ancestry. LY6S codes for the interferon-inducible GPI-linked LY6S-iso1 protein that contains only 9 of the 10 consensus LY6 cysteine residues and is most highly expressed in a non-classical cell population. Its expression leads to distinct shifts in patterns of gene expression, particularly of genes coding for inflammatory and immune response proteins, and LY6S-iso1 expressing cells show increased resistance to viral infection. Our findings reveal the presence of a previously un-annotated human interferon-stimulated gene, LY6S, which has a one to eight ortholog relationship with the genes of the Ly6a subfamily gene cluster, is most highly expressed in spleen cells of a non-classical cell-lineage and whose expression induces viral resistance and is associated with an inflammatory phenotype and with the activation of genes that regulate immune responses.

Nonclassical Monocytes Are Prone to Migrate Into Tumor in Diffuse Large B-Cell Lymphoma

Absolute count of circulating monocytes has been proposed as an independent prognostic factor in diffuse large B-cell lymphoma (DLBCL). However, monocyte nomenclature includes various subsets with pro-, anti-inflammatory, or suppressive functions, and their clinical relevance in DLBCL has been poorly explored. Herein, we broadly assessed circulating monocyte heterogeneity in 91 DLBCL patients. Classical- (cMO, CD14pos CD16neg) and intermediate- (iMO, CD14pos CD16pos) monocytes accumulated in DLBCL peripheral blood and exhibited an inflammatory phenotype. On the opposite, nonclassical monocytes (ncMOSlanpos, CD14low CD16pos Slanneg and ncMOSlanneg, CD14low CD16pos, Slanneg) were decreased in peripheral blood. Tumor-conditioned monocytes presented similarities with ncMO phenotype from DLBCL and were prone to migrate in response to CCL5 and CXCL12, and presented similarities with DLBCL-infiltrated myeloid cells, as defined by mass cytometry. Finally, we demonstrated the adverse value of an accumulation of nonclassical monocytes in 2 independent cohorts of DLBCL.