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Project description:The complex system by which the skin regulates immune responses to the external environment is unclear. Here, we investigated cell-cell interactions underlying cutaneous defense against S. aureus. Single-cell transcriptomics (scRNA-Seq) and unbiased network analysis revealed unexpected, dominant IL-17-mediated dermal reticular fibroblast-to-neutrophil communication. Multi-faceted in vitro omics studies demonstrated that IL-17 synergized with several factors including TNF⍺ to induce fibroblast NFKBIZ and chemokine secretion. Cultured fibroblasts drove robust neutrophil recruitment through NFKBIZ-dependent CXCR2 and CXCR4 ligands. Mice lacking IL-17R in fibroblasts (PdgfraΔIl17ra) were generated to determine the significance of fibroblast-neutrophil communication. PdgfraΔIl17ra mice exhibited drastically reduced skin neutrophilia in multiple disease models and reduced defense against S. aureus. These findings were translated to humans by comprehensive analysis of biopsies from psoriasis patients on and off anti-IL-17 treatment. Thus, dermal fibroblasts are critical for skin type 17 inflammation and represent a novel target for treatment of infection and inflammatory disease.
2024-02-15 | GSE230512 | GEO
Project description:The complex system by which the skin regulates immune responses to the external environment is unclear. Here, we investigated cell-cell interactions underlying cutaneous defense against S. aureus. Single-cell transcriptomics (scRNA-Seq) and unbiased network analysis revealed unexpected, dominant IL-17-mediated dermal reticular fibroblast-to-neutrophil communication. Multi-faceted in vitro omics studies demonstrated that IL-17 synergized with several factors including TNF⍺ to induce fibroblast NFKBIZ and chemokine secretion. Cultured fibroblasts drove robust neutrophil recruitment through NFKBIZ-dependent CXCR2 and CXCR4 ligands. Mice lacking IL-17R in fibroblasts (PdgfraΔIl17ra) were generated to determine the significance of fibroblast-neutrophil communication. PdgfraΔIl17ra mice exhibited drastically reduced skin neutrophilia in multiple disease models and reduced defense against S. aureus. These findings were translated to humans by comprehensive analysis of biopsies from psoriasis patients on and off anti-IL-17 treatment. Thus, dermal fibroblasts are critical for skin type 17 inflammation and represent a novel target for treatment of infection and inflammatory disease.
2024-02-14 | GSE230511 | GEO
Project description:The skin provides an essential barrier for host defense through rapid action of multiple resident and recruited cell types, but the complex communication network governing these processes is incompletely understood. To define these cell-cell interactions more clearly, we performed an unbiased network analysis of mouse skin during invasive S. aureus infection and revealed a dominant role for CXCL12+ fibroblast subsets in neutrophil communication. These subsets predominantly reside in the reticular dermis, express adipocyte lineage markers, detect IL-17 and TNFα, and promote robust neutrophil recruitment through NFKBIZ-dependent release of CXCR2 ligands and CXCL12. Targeted deletion of Il17ra in mouse fibroblasts resulted in greatly reduced neutrophil recruitment and increased infection by S. aureus. Analogous human CXCL12+ fibroblast subsets abundantly express neutrophil chemotactic factors in psoriatic skin that are subsequently decreased upon therapeutic targeting of IL-17. These findings show that CXCL12+ dermal immune acting fibroblast subsets play a critical role in cutaneous neutrophil recruitment and host defense.
| S-EPMC10890925 | biostudies-literature
Project description:IL-17 activates dermal reticular fibroblasts to promote neutrophil recruitment and host defense
| PRJNA961668 | ENA
Project description:IL-17 activates dermal reticular fibroblasts to promote neutrophil recruitment and host defense [scRNAseq]
| PRJNA961680 | ENA
Project description:IL-17 activates dermal reticular fibroblasts to promote neutrophil recruitment and host defense [RNAseq]
| PRJNA961678 | ENA
Project description:IL-23 induces IL-17 production in activated CD4+ T cells and participates in host defense against many encapsulated bacteria. However, whether the IL-23/IL-17 axis contributes to a Mycoplasma pneumoniae (Mp)-induced lung inflammation (e.g., neutrophils) has not been addressed. Using an acute respiratory Mp infection murine model, we found significantly up-regulated lung IL-23p19 mRNA in the early phase of infection (4h), and alveolar macrophages were an important cell source of Mp-induced IL-23. We further showed that Mp significantly increased IL-17 protein levels in bronchoalveolar lavage (BAL). Lung gene expression of IL-17, IL-17C and IL-17F was also markedly up-regulated by Mp in vivo. IL-17 and IL-17F were found to be derived mainly from lung CD4+ T cells, and were increased upon IL-23 stimulation in vitro. In vivo blocking of IL-23p19 alone or in combination with IL-23/IL-12p40 resulted in a significant reduction of Mp-induced IL-17 protein and IL-17/IL-17F mRNA expression, which was accompanied by a trend toward reduced lung neutrophil recruitment, BAL neutrophil activity, and Mp clearance. However, IL-23 neutralization had no effect on Mp-induced lung IL-17C mRNA expression. These results demonstrate that IL-17/IL-17F production is IL-23-dependent in an acute Mp infection, and contributes to neutrophil recruitment and activity in the lung defense against the infection.
| S-EPMC1832075 | biostudies-literature
Project description:Chronic kidney disease (CKD) has been associated with impaired host response and increased susceptibility to infections. Leukocyte recruitment during inflammation must be tightly regulated to protect the host against pathogens. FGF23 levels are increased in blood during CKD, and levels of this hormone have been associated with a variety of adverse effects in CKD patients. Here, we have shown that CKD impairs leukocyte recruitment into inflamed tissue and host defense in mice and humans. FGF23 neutralization during CKD in murine models restored leukocyte recruitment and host defense. Intravital microscopy of animals with chronic kidney failure showed that FGF23 inhibits chemokine-activated leukocyte arrest on the endothelium, and downregulation of FGF receptor 2 (FGFR2) on PMNs rescued host defense in these mice. In vitro, FGF23 inhibited PMN adhesion, arrest under flow, and transendothelial migration. Mechanistically, FGF23 binding to FGFR2 counteracted selectin- and chemokine-triggered ?2 integrin activation on PMNs by activating protein kinase A (PKA) and inhibiting activation of the small GTPase Rap1. Moreover, knockdown of PKA abolished the inhibitory effect of FGF23 on integrin activation. Together, our data reveal that FGF23 acts directly on PMNs and dampens host defense by direct interference with chemokine signaling and integrin activation.
| S-EPMC4767336 | biostudies-literature
Project description:Bacterial pneumonia is an increasing complication of HIV infection and inversely correlates with the CD4(+) lymphocyte count. Interleukin (IL)-17 is a cytokine produced principally by CD4(+) T cells, which induces granulopoiesis via granulocyte colony-stimulating factor (G-CSF) production and induces CXC chemokines. We hypothesized that IL-17 receptor (IL-17R) signaling is critical for G-CSF and CXC chemokine production and lung host defenses. To test this, we used a model of Klebsiella pneumoniae lung infection in mice genetically deficient in IL-17R or in mice overexpressing a soluble IL-17R. IL-17R-deficient mice were exquisitely sensitive to intranasal K. pneumoniae with 100% mortality after 48 h compared with only 40% mortality in controls. IL-17R knockout (KO) mice displayed a significant delay in neutrophil recruitment into the alveolar space, and had greater dissemination of K. pneumoniae compared with control mice. This defect was associated with a significant reduction in steady-state levels of G-CSF and macrophage inflammatory protein (MIP)-2 mRNA and protein in the lung in response to the K. pneumoniae challenge in IL-17R KO mice. Thus, IL-17R signaling is critical for optimal production of G-CSF and MIP-2 and local control of pulmonary K. pneumoniae infection. These data support impaired IL-17R signaling as a potential mechanism by which deficiency of CD4 lymphocytes predisposes to bacterial pneumonia.
| S-EPMC2193502 | biostudies-literature
Project description:The role of mouse dermal ?? T cells in inflammatory skin disorders and host defense has been studied extensively. It is known that dendritic epidermal T cells (DETC) have a monomorphic ?? T cell receptor (TCR) and reside in murine epidermis from birth. We asked if dermal ?? cells freely re-circulated out of skin, or behaved more like dermal resident memory T cells (TRM) in mice. We found that, unlike epidermal ?? T cells (DETC), dermal ?? cells are not homogeneous with regard to TCR, express the tissue resident T cell markers CD69 and CD103, bear skin homing receptors, and produce IL-17 and IL-22. We created GFP+: GFP- parabiotic mice and found that dermal ?? T cells re-circulate very slowly-more rapidly than authentic ?? TCR TRM, but more slowly than the recently described dermal ?? TCR T migratory memory cells (TMM). Mice lacking the TCR ? gene (?-/-) had a significant reduction of 2,4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity (CHS). We created mice deficient in dermal ?? T cells but not DETC, and these mice also showed a markedly reduced CHS response after DNFB challenge. The infiltration of effector T cells during CHS was not reduced in dermal ?? T cell-deficient mice; however, infiltration of Gr-1+CD11b+ neutrophils, as well as ear swelling, was reduced significantly. We next depleted Gr-1+ neutrophils in vivo, and demonstrated that neutrophils are required for ear swelling, the accepted metric for a CHS response. Depletion of IL-17-producing dermal V?4+ cells and neutralization of IL-17 in vivo, respectively, also led to a significantly reduced CHS response and diminished neutrophil infiltration. Our findings here suggest that dermal ?? T cells have an intermediate phenotype of T cell residence, and play an important role in primary CHS through producing IL-17 to promote neutrophil infiltration.
| S-EPMC5230790 | biostudies-literature