B SANGANERIA1, N ROGERS1,2,3
1Westmead Institute For Medical Reserach, Westmead, Australia, 2Westmead Hospital, Westmead, Australia, 3The University of Sydney, Camperdowm, Australia
Background: Acute kidney injury triggers a complex cascade of cellular and molecular responses that culminates in maladaptive repair. This leads to the development of fibrosis. We have previously reported that the matrix protein thrombospondin-1 (TSP1) and its receptor CD47 are induced following acute kidney injury and promote epithelial cell damage. However, the role of this axis has not been characterized in chronic kidney disease.
Methods: Age and gender-matched wild-type (WT), CD47-/- and WT mice treated with CD47 blocking antibody (WT+CD47Ab) were compared in two chronic kidney injury models: unilateral ischemia- reperfusion and contralateral nephrectomy (RN), and unilateral ureteric obstruction (UUO). All animals underwent analysis of renal function and bimolecular phenotyping. Human and murine WT and CD47-/- renal tubular epithelial cells (rTEC) were studied in vitro.
Results: WT, WT + CD47Ab, and CD47-/- RN mice showed no difference in serum creatinine regardless of injury model, however there was clear amelioration of renal histological changes and fibrosis with blockade or knockout of CD47. WT RN mice showed upregulated mRNA and protein expression of TSP-1 and pro-fibrotic markers TGF-ß, SMAD2, smooth muscle actin, fibronectin and collagen. These markers were significantly abrogated in both CD47-/- and WT + CD47Ab counterparts. Interestingly, both WT and CD47-/- UUO mice showed equivalent increases in pro-fibrotic tendency, regardless of overall TSP1 expression. Renal tubular epithelial cells isolated from WT mice showed robust upregulation of TSP1 and pro-fibrotic markers under hypoxic stress, which was mitigated in CD47-/- cells.
Conclusions: These data suggest that renal tubular epithelial cells contribute to fibrosis by activating TSP1-CD47 signalling, and point to CD47 as a target to limit fibrosis following injury.
Barkha Sanganeria is in her early research career and has 2 years of research experience at the Centre for transplant and renal research, Westmead Institute for Medical Research, Sydney. She conferred her PhD in molecular biology from Texas Woman’s University, received several awards and presented her thesis at several U.S.A. conferences and was awarded with Chancellors Student Research Scholarship in 2015. Prior to PhD she worked as a project officer at Central Drug Research Institute” in India and screened for the drugs targeting hyperlipidaemia. Barkha also undertook a master’s degree in biochemistry and bachelor’s degree in biology from India.