Cysteine-Rich Protein 61 Plays a Proinflammatory Role in Obstructive Kidney Fibrosis
et al. (2013) Cysteine-Rich Protein 61 Plays a Proinflammatory Role in Obstructive Kidney Fibrosis. PLoS
ONE 8(2): e56481. doi:10.1371/journal.pone.0056481
Cysteine-Rich Protein 61 Plays a Proinflammatory Role in Obstructive Kidney Fibrosis
Jun Tsai 0
Chun-Fu Lai 0
Yung-Ming Chen 0
Wen-Chih Chiang 0
Shuei-Liong Lin 0
Min-Liang Kuo 0
Tun- 0
Niels Olsen Saraiva Camara, Universidade de Sao Paulo, Brazil
0 1 Department of Internal Medicine, National Taiwan University Hospital and College of Medicine , Taipei, Taiwan , 2 Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine , Taipei, Taiwan , 3 Graduate Institute of Physiology, National Taiwan University College of Medicine , Taipei, Taiwan , 4 Graduate Institute of Toxicology, National Taiwan University College of Medicine , Taipei, Taiwan , 5 Department of Internal Medicine, National Taiwan University Hospital Yun-Lin Branch , Douliou City , Taiwan
Cysteine-rich protein 61 (Cyr61) is a secreted matrix-associated protein that regulates a broad spectrum of biological and cellular activities. This study aimed to investigate the role of Cyr61 in progressive kidney fibrosis induced by unilateral ureteral obstruction (UUO) surgery in mice. The expression of Cyr61 transcripts and proteins in the obstructed kidneys were increased from day 1 and remained high until day 10 after surgery. Immunohistochemistry indicated that Cyr61 was expressed mainly in renal tubular epithelial cells. The upregulated Cyr61 in UUO kidneys was reduced in mice treated with pan-transforming growth factor-b (TGF-b) antibody. The role of TGF-b in tubular Cyr61 upregulation after obstructive kidney injury was further supported by experiments showing that TGF-b1 stimulated Cyr61 expression in cultured tubular epithelial cells. Notably, the upregulation of Cyr61 in UUO kidneys was followed by a marked increase in monocyte chemoattractant protein 1 (MCP-1) transcripts and macrophage infiltration, which were attenuated in mice treated with anti-Cyr61 antibodies. This proinflammatory property of Cyr61 in inducing MCP-1 expression was further confirmed in tubular epithelial cells cultured with Cyr61 protein. The anti-Cyr61 antibody in UUO mice also reduced the levels of collagen type 1-a1 transcripts, collagen fibril accumulation evaluated by picrosirius red staining, and the levels of a-smooth muscle actin (aSMA) transcripts and proteins on day 4 after surgery; however, the antifibrotic effect was not sustained. In conclusion, the TGF-b-mediated increase in tubular Cyr61 expression involved renal inflammatory cell infiltration through MCP-1 induction during obstructive kidney injury. The Cyr61 blockade attenuated kidney fibrosis in the early phase, but the antifibrotic effect could not be sustained.
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Funding: This study was supported by grants from the National Science Council (NSC 96-2628-B-002-015-MY3), Far Eastern Memorial Hospital (FEMH-95-C-024),
Ta-Tung Kidney Foundation and Mrs. Hsiu-Chin Lee Kidney Research Fund for supporting this study. The funders had no role in study design, data collection and
analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Chronic tubulointerstitial fibrosis is regarded as the final
common pathway leading to end-stage renal failure [13]. During
the evolution of renal fibrosis, multiple pathologic mechanisms
occur, including inflammation, proteolysis, hypoxia, tubular
decomposition, and extracellular matrix accumulation [4]. So
far, there is no effective therapeutic strategy capable of fully
stopping its progression. Therefore, the identification of the
detailed mechanisms of tubulointerstitial fibrosis with the ultimate
goal of halting renal disease progression is of great interest to
researchers.
Cysteine-rich protein 61 (Cyr61) is a secreted,
matrix-associated, heparin-binding protein belonging to the CCN family,
which comprises Cyr61 (CCN1), connective tissue growth factor
(CTGF, CCN2), nephroblastoma overexpressed (NOV, CCN3),
WNT 1-inducible signaling pathway proteins (WISP)-1 (CCN4),
WISP-2 (CCN5), and WISP-3 (CCN6) [57]. Cyr61 has been
reported to control the cell cycle, stimulate chemostasis, and
augment growth factor-induced effects [6,8]. It also participates in
angiogenesis by promoting endothelial cell survival and
stimulating pro-angiogenic factors [911]. In addition, Cyr61 has been
shown to integrate the biological mechanisms of cutaneous wound
healing. It can regulate the expression of genes involved in matrix
remodeling [9] and induce senescence and apoptosis in fibroblasts
[11,12]. Recently, it was discovered that Cyr61 promoted
inflammation and modified the effects of cytokines on cell death
[6,13,14]. All of these mechanisms in which Cyr61 is involved are
crucial processes in the context of renal fibrosis progression [4].
Animal and human studies have demonstrated Cyr61
expression in normal and diseased kidney (...truncated)