High–molecular weight hyaluronan attenuates tubulointerstitial scarring in kidney injury
Xinyi Wang, … , Jizhong Cheng, Sundeep G. Keswani
Xinyi Wang, … , Jizhong Cheng, Sundeep G. Keswani
Published June 18, 2020; First published May 12, 2020
Citation Information: JCI Insight. 2020;5(12):e136345. https://doi.org/10.1172/jci.insight.136345.
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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 1

Increased HA in UUO-induced renal fibrosis.

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Increased HA in UUO-induced renal fibrosis. (A) Images of PAS, trichrome...
(A) Images of PAS, trichrome, and HABP staining of the cortex from control and UUO kidneys show fibrotic remodeling and HA accumulation after UUO injury. Scale bars: 75 μm for PAS and trichrome staining, 100 μm for HABP to depict broader HA changes during the process. (B) Quantitative assessment of PAS intratubular space (0.94 ± 0.23 vs. 1.13 ± 0.22 vs. 1.48 ± 0.38 vs. 1.64 ± 0.51), trichrome fibrotic area (17.33% ± 3.18% vs. 19.82% ± 3.71% vs. 27.56% ± 6.57% vs. 34.11% ± 5.72%), and HABP-detected HA levels (1.01 ± 0.09 vs. 1.28 ± 0.23 vs. 1.85 ± 0.29 vs. 2.45 ± 0.22). P < 0.0001. (C) Extracted HA concentration (ng/mL/mg) from control and 3-, 7-, and 14-day UUO kidneys, measured by a modified ELISA HA test kit. (D) Plots of total incorporated [3H] in labeled HA samples were used to determine the relative MW of HA synthesized by control and 3D UUO kidneys (n ≥ 3 per condition) using Sephacryl S-1000 chromatography. Data were plotted as HA concentration versus the partition coefficient (Kav), showing an increase in HA size distribution in samples with UUO injury. (E) The extracted HA from control and 3-, 7-, and 14-day untreated and treated UUO kidneys is shown on a 0.5% agarose gel electrophoresis, supporting our chromatography results. (F) Relative mRNA level of Has1–3 and hyaluronidases (Hyal1–2) in untreated control and UUO kidneys; n ≥ 3 per sex per condition; P < 0.01. All data were analyzed by 1-way ANOVA with post hoc Tukey’s test for differences between groups. Groups annotated with different letters indicate that they are significantly different.