title: Fibroblasts secrete Slit2 to inhibit fibrocyte differentiation and fibrosis.
abstract: Monocytes leave the blood and enter tissues. In healing wounds and fibrotic lesions, some of the monocytes differentiate into fibroblast-like cells called fibrocytes. In healthy tissues, even though monocytes enter the tissue, for unknown reasons, very few monocytes differentiate into fibrocytes. In this report, we show that fibroblasts from healthy human tissues secrete the neuronal guidance protein Slit2 and that Slit2 inhibits human fibrocyte differentiation. In mice, injections of Slit2 inhibit bleomycin-induced lung fibrosis. In lung tissue from pulmonary fibrosis patients with relatively normal lung function, Slit2 has a widespread distribution whereas, in patients with advanced disease, there is less Slit2 in the fibrotic lesions. These data may explain why fibrocytes are rarely observed in healthy tissues, may suggest that the relative levels of Slit2 present in healthy tissue and at sites of fibrosis may have a significant effect on the decision of monocytes to differentiate into fibrocytes, and may indicate that modulating Slit2 signaling may be useful as a therapeutic for fibrosis.
authors.affiliation: Department of Biology, Texas A&M University, College Station, TX 77843; and rgomer@tamu.edu dpilling@bio.tamu.edu.
authors.forename: Darrell
authors.initials: D
authors.lastname: Pilling
authors.affiliation: Department of Biology, Texas A&M University, College Station, TX 77843; and.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251.
authors.forename: Varsha
authors.initials: V
authors.lastname: Vakil
authors.affiliation: Department of Biology, Texas A&M University, College Station, TX 77843; and Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251 rgomer@tamu.edu dpilling@bio.tamu.edu.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Gomer
mesh_terms: D000818:Animals; D001761:Bleomycin / Q000633:toxicity; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000139:chemically induced; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000502:physiology; D011658:Pulmonary Fibrosis; D000098552:Slit Homolog 2 Protein
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D001761:Bleomycin; D000098552:Slit Homolog 2 Protein
keywords: Slit2; fibroblast; fibrocyte; fibrosis; lung