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.
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.
Project description:The sphingolipid, ceramide-1-phosphate (C1P), directly binds and activates Group IVA cytosolic phospholipase A2 (cPLA2) to generate eicosanoids. Due to the role of eicosanoids in wound healing, we choose to use our novel genetic mouse model expressing cPLA2 with an ablated C1P interaction site (KI) to examine the cPLA2/C1P interaction in wound healing. Wound closure rate was not affected, but wound maturation was enhanced by loss of the C1P/cPLA2α interaction based on the following findings. Wounds in KI mice displayed: i) increased infiltration of dermal fibroblasts into the wound environment; ii) increased wound tensile strength; and iii) higher Type I/Type III collagen ratios. These findings were recapitulated in vitro as primary dermal fibroblasts (pDFs) from KI mice showed significantly increased collagen deposition and migration velocity compared to WT and KO pDFs. Additionally, the KI showed an altered eicosanoid profile of reduced pro-inflammatory prostaglandins (PGE2) and increased levels of specific HETE species (5-HETE). Elevated 5-HETE levels promoted increased dermal fibroblast migration and collagen deposition. This “gain of function” role for the mutant cPLA2 was also linked to differential cellular localization of cPLA2α and 5-HETE biosynthetic factors. These studies demonstrate regulation of key biological mechanisms by a defined protein:lipid interaction in vivo and provide new insights into cPLA2 function.
Project description:The sphingolipid, ceramide-1-phosphate (C1P), directly binds and activates Group IVA cytosolic phospholipase A2 (cPLA2) to generate eicosanoids. Due to the role of eicosanoids in wound healing, we choose to use our novel genetic mouse model expressing cPLA2 with an ablated C1P interaction site (KI) to examine the cPLA2/C1P interaction in wound healing. Wound closure rate was not affected, but wound maturation was enhanced by loss of the C1P/cPLA2α interaction based on the following findings. Wounds in KI mice displayed: i) increased infiltration of dermal fibroblasts into the wound environment; ii) increased wound tensile strength; and iii) higher Type I/Type III collagen ratios. These findings were recapitulated in vitro as primary dermal fibroblasts (pDFs) from KI mice showed significantly increased collagen deposition and migration velocity compared to WT and KO pDFs. Additionally, the KI showed an altered eicosanoid profile of reduced pro-inflammatory prostaglandins (PGE2) and increased levels of specific HETE species (5-HETE). Elevated 5-HETE levels promoted increased dermal fibroblast migration and collagen deposition. This “gain of function” role for the mutant cPLA2 was also linked to differential cellular localization of cPLA2α and 5-HETE biosynthetic factors. These studies demonstrate regulation of key biological mechanisms by a defined protein:lipid interaction in vivo and provide new insights into cPLA2 function.
Project description:The goal of this project is to compare the protein composition of the extracellular matrices (ECMs) deposited in vitro by wild type, heterozygous, or SPAG17 KO neonatal mouse dermal fibroblasts.