title: Inflammatory macrophages can transdifferentiate into myofibroblasts during renal fibrosis.
abstract: Myofibroblasts play a central role in renal fibrosis although the origin of these cells remains controversial. We recently reported that bone marrow-derived macrophages can give rise to myofibroblasts through macrophage to myofibroblast transition (MMT). However, several important issues remain to be addressed, including whether MMT occurs in human kidney disease and verification of the MMT process through lineage tracing. Biopsies from a cohort of 58 patients with various forms of kidney disease were examined for MMT cells that co-express macrophage (CD68) and myofibroblast (α-smooth muscle actin, α-SMA) markers. MMT cells were evident in active fibrotic lesions, but were largely absent in acute inflammatory or sclerotic lesions, suggesting that MMT cells contribute to progressive renal fibrosis. Fate-mapping studies in LysMCreTomato mice identified substantial numbers of Tomato+myeloid cells with F4/80+macrophage phenotype expressing α-SMA and collagen I in the unilateral ureteral obstructive model of renal fibrosis, providing direct evidence for the MMT process during the development of renal fibrosis. In addition, MMT cells had a predominant M2 phenotype in both human and mouse renal fibrosis. Finally, selective depletion of myeloid cells via diphtheria toxin in LysMCreiDTR mice largely abolished macrophage infiltration and MMT cells in the obstructed kidney and substantially reduced accumulation of α-SMA+myofibroblasts and collagen deposition, revealing a pathogenic role for inflammatory macrophages in MMT and tissue fibrosis. In conclusion, these findings provide substantial new data to support the postulate that macrophages can directly transdifferentiate into collagen-producing myofibroblasts in human and experimental kidney disease.
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.|School of Pharmacy, Anhui Medical University, Anhui, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Meng
authors.affiliation: Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Xiao-Ru
authors.initials: XR
authors.lastname: Huang
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.affiliation: Department of Nephrology and Monash University Centre for Inflammatory Diseases, Monash Medical Centre, Clayton, VIC 3168, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Nikolic-Paterson
authors.affiliation: Li Ka Shing Institute of Health Sciences, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Hui-Yao
authors.initials: HY
authors.lastname: Lan
mesh_terms: D000818:Animals; D019070:Cell Lineage; D016764:Cell Polarity; D054338:Cell Transdifferentiation; D003094:Collagen / Q000378:metabolism; D005355:Fibrosis; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D019426:Integrases / Q000378:metabolism; D007674:Kidney Diseases / Q000473:pathology*; D008264:Macrophages / Q000473:pathology*; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000473:pathology; D058628:Myofibroblasts / Q000473:pathology*; D010641:Phenotype; D014517:Ureteral Obstruction / Q000473:pathology
chemical_list: D003094:Collagen; C045073:Cre recombinase; D019426:Integrases