MPO and interstitial cystitis: Quercetin has been shown to enhance the expression of lipoprotein lipase, enhance the production of glycosaminoglycan while decreasing myeloperoxidase (MPO), IL-1β, and TNF-α levels, so as to attenuate bladder injury and mast cell degranulation in a rat model of interstitial cystitis/bladder pain syndrome (74).