Hyaluronan, a double-edged sword in kidney diseases.

Over the years, hyaluronic acid (HA) has emerged as an important molecule in nephrological and urological studies involving extracellular matrix (ECM) organization, inflammation, tissue regeneration, and viral sensing. During this time, many have noted the perplexing double-edged nature of the molecule, at times promoting pro-fibrotic events and at other times promoting anti-fibrotic events. Different molecular weights of HA can be attributed to these disparities, though most studies have yet to focus on this subtlety. With regard to the kidney, HA is induced in the initial response phase of injury and is subsequently decreased during disease progression of AKI, CKD, and diabetic nephropathy. These and other kidney diseases force patients, particularly pediatric patients, to face dialysis, surgical procedures, and ultimately, transplant. To summarize the current literature for researchers and pediatric nephrologists, this review aims to expound HA and elucidate its paradoxical effects in multiple kidney diseases using studies that emphasize HA molecular weight when available.