Medicinal and Pharmaceutical Chemistry Commons^™

Proteoglycan 4 (Prg4)/Lubricin And The Extracellular Matrix In Gout, Khaled A. Elsaid, Gregory D. Jay, Ru Liu-Bryan, Robert Terkeltaub

Pharmacy Faculty Articles and Research

Proteoglycan 4 (PRG4) is a mucinous glycoprotein secreted by synovial fibroblasts and superficial zone chondrocytes, released into synovial fluid, and adsorbed on cartilage and synovial surfaces. PRG4′s roles include cartilage boundary lubrication, synovial homeostasis, immunomodulation, and suppression of inflammation. Gouty arthritis is mediated by monosodium urate (MSU) crystal phagocytosis by synovial macrophages, with NLRP3 inflammasome activation and IL-1β release. The phagocytic receptor CD44 mediates MSU crystal uptake by macrophages. By binding CD44, PRG4 limits MSU crystal uptake and downstream inflammation. PRG4/CD44 signaling is transduced by protein phosphatase 2A, which inhibits NF-κB, decreases xanthine oxidoreductase (XOR), urate production, and ROS-mediated IL-1β …

Quadruped Gait And Regulation Of Apoptotic Factors In Tibiofemoral Joints Following Intra-Articular Rhprg4 Injection In Prg4 Null Mice, Daniel S. Yang, Edward E. Dickerson, Ling X. Zhang, Holly Richendrfer, Padmini N. Karamchedu, Gary A. Badger, Tannin A. Schmidt, Alger M. Fredericks, Khaled A. Elsaid, Gregory D. Jay

Pharmacy Faculty Articles and Research

Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome leads to diarthrodial joint arthropathy and is caused by the absence of lubricin (proteoglycan 4—PRG4), a surface-active mucinous glycoprotein responsible for lubricating articular cartilage. In this study, mice lacking the orthologous gene Prg4 served as a model that recapitulates the destructive arthrosis that involves biofouling of cartilage by serum proteins in lieu of Prg4. This study hypothesized that Prg4-deficient mice would demonstrate a quadruped gait change and decreased markers of mitochondrial dyscrasia, following intra-articular injection of both hindlimbs with recombinant human PRG4 (rhPRG4). Prg4^−/− (N = 44) mice of both sexes were injected with rhPRG4 …

Recombinant Human Proteoglycan 4 Regulates Phagocytic Activation Of Monocytes And Reduces Il-1Β Secretion By Urate Crystal Stimulated Gout Pbmcs, Sandy Elsayed, Gregory D. Jay, Ralph Cabezas, Marwa Qadri, Tannin A. Schmidt, Khaled A. Elsaid

Pharmacy Faculty Articles and Research

Objectives

To compare phagocytic activities of monocytes in peripheral blood mononuclear cells (PBMCs) from acute gout patients and normal subjects, examine monosodium urate monohydrate (MSU) crystal-induced IL-1β secretion ± recombinant human proteoglycan 4 (rhPRG4) or interleukin-1 receptor antagonist (IL-1RA), and study the anti-inflammatory mechanism of rhPRG4 in MSU stimulated monocytes.

Methods

Acute gout PBMCs were collected from patients in the Emergency Department and normal PBMCs were obtained from a commercial source. Monocytes in PBMCs were identified by flow cytometry. PBMCs were primed with Pam3CSK4 (1μg/mL) for 24h and phagocytic activation of monocytes was determined using fluorescently labeled latex beads. MSU …

Proteoglycan-4 Is An Essential Regulator Of Synovial Macrophage Polarization And Inflammatory Macrophage Joint Infiltration, Marwa Qadri, Gregory D. Jay, Ling X. Zhang, Tannin A. Schmidt, Jennifer Totonchy, Khaled A. Elsaid

Pharmacy Faculty Articles and Research

Background

Synovial macrophages perform a multitude of functions that include clearance of cell debris and foreign bodies, tissue immune surveillance, and resolution of inflammation. The functional diversity of macrophages is enabled by distinct subpopulations that express unique surface markers. Proteoglycan-4 (PRG4) is an important regulator of synovial hyperplasia and fibrotic remodeling, and the involvement of macrophages in PRG4’s synovial role is yet to be defined. Our objectives were to study the PRG4’s importance to macrophage homeostatic regulation in the synovium and infiltration of pro-inflammatory macrophages in acute synovitis and investigate whether macrophages mediated synovial fibrosis in Prg4 gene-trap (Prg4 …

A Two Compartment Pharmacokinetic Model Describes The Intra‐Articular Delivery And Retention Of Rhprg4 Following Acl Transection In The Yucatan Mini Pig, Mark Hurtig, Iman Zaghoul, Heather Sheardown, Tannin A. Schmidt, Lina Liu, Ling Zhang, Khaled A. Elsaid, Gregory D. Jay

Pharmacy Faculty Articles and Research

Treatment of the injured joint with rhPRG4 is based on recent observations that inflammation diminishes expression of native PRG4. Re‐establishing lubrication between pressurized and sliding cartilage surfaces during locomotion promotes the nascent expression of PRG4 and thus intra‐articular (IA) treatment strategies should be supported by pharmacokinetic evidence establishing the residence time of rhPRG4. A total of 21 Yucatan minipigs weighing ∼55 Kg each received 4 mg of 131I‐rhPRG4 delivered by IA injection 5 days following surgical ACL transection. Animals were sequentially euthanized following IA rhPRG4 at 10 mins (time zero), 24, 72 hrs, 6, 13 and 20 days later. The …