Hyaluronidase 1 and hyaluronidase 2 are required for renal hyaluronan turnover

Kidney function was not impaired in the knockout mice but they displayed elevated HA concentrations in the plasma and in the kidney. Hyal1−/− mice presented an accumulation of HA inside the proximal tubular cells whereas Hyal2−/− mice showed HA accumulation in the interstitial space. In the cortex and in the outer medulla, HYAL1 mRNA expression was up-regulated in Hyal2−/− mice. From our study we conclude that somatic hyaluronidases are not required for renal function. However, HYAL1 is necessary for the breakdown of intracellular HA in the cortex, whereas HYAL2 is essential for the degradation of extracellular HA in all kidney regions.