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 2

IL-10 upregulates HA synthesis in vivo, increases HMW-HA, and reduces renal fibrosis.

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IL-10 upregulates HA synthesis in vivo, increases HMW-HA, and reduces re...
(A) Images of PAS, trichrome, α-SMA, and HABP staining in untreated controls, day 14 UUO, and IL-10–treated day 14 UUO kidneys. Scale bars: 75 μm for PAS, trichrome, and α-SMA staining; 100 μm for HABP staining. (B) Quantification of respective PAS intratubular space, trichrome fibrotic area, α-SMA, and HABP-stained HA levels from panel A. Data were analyzed by 1-way ANOVA with post hoc Tukey’s tests. Significantly different groups are not connected by the same letter. P < 0.01 for fibrotic area and α-SMA; P < 0.05 for intratubular space and HA. (C) Relative mRNA level of Has1–3 and Hyal1–2 with control, day 14 UUO, and day 14 IL-10–treated UUO kidneys. n ≥ 3 per sex per condition; P < 0.01 for Has1 and Has2; P < 0.05 for Hyal1. (D) HA tissue concentration in IL-10–treated UUO kidneys was sustained for at least 21 days. Tissue HA concentration (ng/mL/mg) in untreated CTR and UUO kidneys with or without IL-10 treatment over time was measured by an ELISA-like HA assay. 21D UUO vs. IL-10–treated UUO (P < 0.001); 14D UUO vs. IL-10–treated UUO (P = 0.011); 3D and 7D of UUO vs. IL-10–treated UUO was not significant (ns). Data in B and C were analyzed by 1-way ANOVA with post hoc Tukey’s test. Data in D were used for covariance (ANCOVA) analyses with the time points as a continuous covariate, while post hoc Tukey’s tests were performed between the pairs at each time point. Groups annotated with different letters indicate they are significantly different. P < 0.01 unless otherwise noted.