Pentagalloyl glucose as an inhibitor of monosodium urate induced inflammation

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Project Summary Monosodium urate-induced inflammation begins with hyperuricemia leading to monosodium urate (MSU) crystal deposition in the joints and periarticular tissues. These deposits can cause inflammation, pain, and tissue destruction through either acute inflammatory flares or chronic disease. In MSU-induced inflammation, activated macrophages produce the pleiotropic cytokine Interleukin-1β (IL-1β) which is recognized as the major driver of pathogenesis and a key inducer of other pro-inflammatory molecules. The inflammatory signaling cascade begins with activation of Toll-like/IL-1β receptors (TIRs) in macrophages, which triggers production of pro-IL-1β and other inflammasome components. Pro-IL-1β is then activated by cleaved caspase from the NOD-Like Receptor Protein 3 (NLRP3) inflammasome before being exported and initiating further inflammation. Several treatment options exist for gout patients, mostly falling into two categories – reduction of circulating levels of soluble urate, or the suppression of pain and inflammation. These therapies, however, leave much to be desired as they have significant adverse effects, deleterious drug-drug interactions, high cost and low/non-responder groups. This project investigates a potential novel therapeutic agent for MSU-induced inflammation – pentagalloyl glucose (PGG) – that is known to have strong antioxidant and anti-inflammatory effects. Additionally, our preliminary data shows that this compound inhibits xanthine oxidase which produces soluble urate. We also demonstrate that PGG inhibits TGFβ-activated kinase which plays a role in the upregulation of proinflammatory mediators critical to MSU-induced inflammation. Finally, we have demonstrated that PGG inhibits both a critical downstream kinase and proinflammatory cytokines. In Aim one we will investigate the mechanism by which PGG reduces MSU-induced inflammation in vitro using THP-1 macrophages, investigate the atomistic interactions of PGG with MSU in-silico, then use phosphoproteomics to identify global changes induced by MSU and PGG. In Aim two we will determine the effects of PGG treatment in vivo using mouse models of gout previously published by our group. Taken together, these findings will provide a more complete knowledge of MSU-induced inflammatory signaling while exploring a potential novel therapeutic and providing a training mechanism for this student.