title: Inflammatory PAF Receptor Signaling Initiates Hedgehog Signaling and Kidney Fibrogenesis During Ethanol Consumption.
abstract: Acute inflammation either resolves or proceeds to fibrotic repair that replaces functional tissue. Pro-fibrotic hedgehog signaling and induction of its Gli transcription factor in pericytes induces fibrosis in kidney, but molecular instructions connecting inflammation to fibrosis are opaque. We show acute kidney inflammation resulting from chronic ingestion of the common xenobiotic ethanol initiates Gli1 transcription and hedgehog synthesis in kidney pericytes, and promotes renal fibrosis. Ethanol ingestion stimulated transcription of TGF-ß, collagens I and IV, and alpha-smooth muscle actin with accumulation of these proteins. This was accompanied by deposition of extracellular fibrils. Ethanol catabolism by CYP2E1 in kidney generates local reactive oxygen species that oxidize cellular phospholipids to phospholipid products that activate the Platelet-activating Factor receptor (PTAFR) for inflammatory phospholipids. Genetically deleting this ptafr locus abolished accumulation of mRNA for TGF-ß, collagen IV, and α-smooth muscle actin. Loss of PTAFR also abolished ethanol-stimulated Sonic (Shh) and Indian hedgehog (Ihh) expression, and abolished transcription and accumulation of Gli1. Shh induced in pericytes and Ihh in tubules escaped to urine of ethanol-fed mice. Neutrophil myeloperoxidase (MPO) is required for ethanol-induced kidney inflammation, and Shh was not present in kidney or urine of mpo-/- mice. Shh also was present in urine of patients with acute kidney injury, but not in normal individuals or those with fibrotic liver cirrhosis We conclude neither endogenous PTAFR signaling nor CYP2E1-generated radicals alone are sufficient to initiate hedgehog signaling, but instead PTAFR-dependent neutrophil infiltration with myeloperoxidase activation is necessary to initiate ethanol-induced fibrosis in kidney. We also show fibrogenic mediators escape to urine, defining a new class of urinary mechanistic biomarkers of fibrogenesis for an organ not commonly biopsied.
authors.affiliation: Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Calivarathan
authors.initials: C
authors.lastname: Latchoumycandane
authors.affiliation: Department of Internal Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Hanouneh
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Nagy
authors.affiliation: Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: McIntyre
mesh_terms: D000818:Animals; D024141:Collagen Type IV; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D000431:Ethanol / Q000008:administration & dosage*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005355:Fibrosis / Q000139:chemically induced* / Q000378:metabolism; D053823:Hedgehog Proteins / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced* / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D020286:Pericytes / Q000187:drug effects / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D024141:Collagen Type IV; D053823:Hedgehog Proteins; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C039351:platelet activating factor receptor; D000431:Ethanol; D009195:Peroxidase; D019392:Cytochrome P-450 CYP2E1