PEGPH20 Attenuates Hyaluronan-CD44 Mediated Renal Injury in Obesity Related Glomerulopathy

Background and aims: Obesity is considered as one of the biggest public health threats worldwide and increases the risk of incident chronic kidney disease. Hyaluronan (HA) is a major component of the extracellular matrix (ECM). We hypothesised that HA content was increased in the ECM of Obesity-Related Glomerulopathy (ORG) and PEGPH20, human recombinant PEGylated hyaluronidase PH-20, reversed high-fat (HF) diet-induced HA accumulation and renal dysfunction. We further investigated whether its renal protective effect was dependent upon the main HA receptor, CD44.

Materials and methods: C57BL/6 mice, global CD44-deficient (cd44-/-) mice, and their wildtype littermate controls (cd44+/+) were fed a chow diet or HF diet for 16 weeks. HF diet-fed mice received injections of either vehicle or PEGPH20 once every 3 days for 24 days. After treatment, mice were euthanized and tissue and blood samples were collected. CD44 expression was detected by Western Blotting. PAS staining was used to observe renal pathology. HA accumulation and α-SMA expression were assessed by histochemistry. Collagen deposition was measured by picrosirius red staining and renal function was assessed by a creatinine assay kit.

Results: HF diet feeding in C57BL/6 mice led to an increase in CD44 expression, HA accumulation, glomerular area and tubular injury score in the renal tissue, as well as an increase in serum creatinine levels. PEGPH20 treatment ameliorated some of these adverse effects including reducing renal CD44 expression (3.02 ± 0.33 (Vehicle HF) vs 1.49 ± 0.16 (PEGPH20 HF) fold increase relative to chow-fed mice, p =0.0092), HA accumulation (31.39 ± 3.48 vs 13.58 ± 1.81 %, p =0.0078), tubular injury score (3.28 ± 0.15 vs 1.39 ± 0.06, p =0.0003) and serum creatinine levels (1.40 ± 0.09 vs 0.79 ± 0.07 mg/dl, p =0.0002),without affecting glomerular area. Furthermore, PEGPH20-treated obese mice had reduced renal fibrosis evidenced by decreased α-SMA expression (5.18 ± 0.17 vs 1.21 ± 0.11 %, p =0.0001) and collagen deposition (9.76 ± 0.76 vs 6.30 ± 0.23 %, p =0.0164) compared with obese mice receiving vehicle. Global deletion of cd44 gene in HF-fed mice significantly reduced renal CD44 expression (1.00 ± 0.05 (cd44+/+ HF) vs 0.13 ± 0.02 (cd44-/- HF) fold change, p =0.0001), HA accumulation (24.44 ± 3.33 vs 6.60 ± 0.58 %, p =0.0001) and tubular injury score (3.28 ± 0.20 vs 1.89 ± 0.06, p =0.0001), as well as reduced α-SMA expression (5.02 ± 0.16 vs 0.43 ± 0.06 %, p =0.0001) and collagen deposition (9.48 ± 0.29 vs 6.08 ± 0.73 %, p =0.0063). PEGPH20 caused further reductions in serum creatinine levels, in HF-fed cd44-/- mice (0.67 ± 0.08 mg/dl) when compared with HF-fed cd44 +/+ mice (1.63 ± 0.05 mg/dl, p =0.0001).

Conclusion: PEGPH20 treatment and global cd44 deletion suppressed HA accumulation during ORG, which prevented obesity-associated renal fibrosis and dysfunction. Our results demonstrate that HA plays an important role in the pathogenesis of ORG, perhaps in part through binding to receptor CD44.

Supported by: BHF Project Grant PG/18/56/33935, BX Qi is supported by a scholarship from CSC Disclosure: B. Qi: None.