High–molecular weight hyaluronan attenuates tubulointerstitial scarring in kidney injury
Xinyi Wang, Swathi Balaji, Emily H. Steen, Alexander J. Blum, Hui Li, Christina K. Chan, Scott R. Manson, Thomas C. Lu, Meredith M. Rae, Paul F. Austin, Thomas N. Wight, Paul L. Bollyky, Jizhong Cheng, Sundeep G. Keswani
Xinyi Wang, Swathi Balaji, Emily H. Steen, Alexander J. Blum, Hui Li, Christina K. Chan, Scott R. Manson, Thomas C. Lu, Meredith M. Rae, Paul F. Austin, Thomas N. Wight, Paul L. Bollyky, Jizhong Cheng, Sundeep G. Keswani
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Research Article Nephrology

High–molecular weight hyaluronan attenuates tubulointerstitial scarring in kidney injury

Abstract

Renal fibrosis features exaggerated inflammation, extracellular matrix (ECM) deposition, and peritubular capillary loss. We previously showed that IL-10 stimulates high–molecular weight hyaluronan (HMW-HA) expression by fibroblasts, and we hypothesize that HMW-HA attenuates renal fibrosis by reducing inflammation and ECM remodeling. We studied the effects of IL-10 overexpression on HA production and scarring in mouse models of unilateral ureteral obstruction (UUO) and ischemia/reperfusion (I/R) to investigate whether IL-10 antifibrotic effects are HA dependent. C57BL/6J mice were fed with the HA synthesis inhibitor, 4-methylumbelliferone (4-MU), before UUO. We observed that in vivo injury increased intratubular spaces, ECM deposition, and HA expression at day 7 and onward. IL-10 overexpression reduced renal fibrosis in both models, promoted HMW-HA synthesis and stability in UUO, and regulated cell proliferation in I/R. 4-MU inhibited IL-10–driven antifibrotic effects, indicating that HMW-HA is necessary for cytokine-mediated reduction of fibrosis. We also found that IL-10 induces in vitro HMW-HA production by renal fibroblasts via STAT3-dependent upregulation of HA synthase 2. We propose that IL-10–induced HMW-HA synthesis plays cytoprotective and antifibrotic roles in kidney injury, thereby revealing an effective strategy to attenuate renal fibrosis in obstructive and ischemic pathologies.

Authors

Xinyi Wang, Swathi Balaji, Emily H. Steen, Alexander J. Blum, Hui Li, Christina K. Chan, Scott R. Manson, Thomas C. Lu, Meredith M. Rae, Paul F. Austin, Thomas N. Wight, Paul L. Bollyky, Jizhong Cheng, Sundeep G. Keswani

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Figure 5

IL-10–driven HMW-HA synthesis and regulation of kidney cell proliferation attenuate fibrosis in I/R mice.

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IL-10–driven HMW-HA synthesis and regulation of kidney cell proliferatio...
(A) Images of trichrome and α-SMA staining of control and day 7 I/R-only and IL-10–treated I/R tissue, with HABP staining of day 14 I/R-only and IL-10–treated I/R tissue. Scale bars: 75 μm for trichrome and α-SMA staining, 100 μm for HABP staining. (B) Quantification of fibrotic area (trichrome), α-SMA, and HABP from images of panel A. Data were analyzed with an unpaired t test. (C) HA concentration (ng/mL/mg) extracted from control and day 3, 7, and 14 post-UUO kidneys was measured by an HA test kit (modified ELISA). CTR vs. 3D/14D/30D (P < 0.01); CTR vs. 7D (P < 0.05); 3D and 7D I/R vs. IL-10–treated I/R (P < 0.01); 14D and 30D I/R vs. IL-10–treated I/R were not significant (ns). (D) Relative mRNA expression of Has1–3 and Hyal1–2 in normal kidney, I/R kidney, and IL-10–treated I/R kidney. n ≥ 3 per sex per condition, P < 0.05. (E) Images of BrdU incorporation at day 3 post-I/R and IL-10–treated I/R in the kidney cortex and medulla. Scale bar: 50 μm. (F) Quantification of proliferating cells (% positive cells) from cortex and medulla sections in normal, I/R-only, and IL-10–treated I/R kidneys. P < 0.01. Data from panels B, D, and F were analyzed by 1-way ANOVA with post hoc Tukey’s test. Data from C were analyzed by covariance (ANCOVA) with the time points as a continuous covariate, and post hoc Tukey’s tests were performed between the pairs at each time point. Groups annotated with different letters indicate significant differences at indicated P values.