POS0376 MONOMERIC C REACTIVE PROTEIN (mCRP) REGULATES INFLAMMATORY RESPONSES IN HUMAN AND MOUSE CHONDROCYTES
Authors: C. Ruiz-Fernández, M. González-Rodríguez, V. Francisco, I. M. Rajab, R. Gómez Bahamonde, J. Conde Aranda, F. Lago, J. Pino, A. Mobasheri, M. A. González-Gay, A. Mera Varela, L. A. Potempa, O. Gualillo
Journal: Annals of the Rheumatic Diseases (2021)

Background: C-reactive protein (CRP) is an acute-phase protein that is used as an established biomarker to follow disease severity and progression in a plethora of inflammatory diseases. However, its pathophysiologic mechanisms of action are still poorly defined and remain elusive. CRP, in its pentameric form, exhibits weak anti-inflammatory activity. On the contrary, the monomeric isoform (mCRP) exhibits potent pro-inflammatory properties in endothelial cells, leukocytes, and platelets. So far, no data exists regarding mCRP effects in human or mouse chondrocytes Objectives: This work aimed to verify the pathophysiological relevance of mCRP in the etiology and/or progression of osteoarthritis (OA) Methods: We investigated the effects of mCRP in cultured human primary chondrocytes and in the chondrogenic ATDC5 mouse cell line. We determined mRNA and protein levels of relevant factors involved in inflammatory responses and the modulation of nitric oxide synthase type II (NOS2), an early inflammatory molecular target. Results: We demonstrate, for the first time, that monomeric C reactive protein increases NOS2, COX2, MMP13, VCAM1, IL-6, IL-8, and LCN2 expression in human and murine chondrocytes. We also demonstrated that NF-kB is a key factor in the intracellular signaling of mCRP-driven induction of pro-inflammatory and catabolic mediators in chondrocytes. Conclusion: mCRP exerts a sustained catabolic effect on human and murine chondrocytes, increasing the expression of inflammatory mediators and proteolytic enzymes, which can promote extracellular matrix (ECM) breakdown in healthy and OA cartilage. In addition, our results implicate the NF-kB signaling pathway in catabolic effects mediated by mCRP. References: [1]Sproston NR, Ashworth JJ. Role of C-reactive protein at sites of inflammation and infection. Front Immunol. 2018;9(APR). doi:10.3389/fimmu.2018.00754 [2]Francisco V, Pérez T, Pino J, et al. Biomechanics, obesity, and osteoarthritis. The role of adipokines: When the levee breaks. J Orthop Res. 2018;36(2):594-604. doi:10.1002/jor.23788 [3]Kozijn AE, Tartjiono MT, Ravipati S, et al. Human C-reactive protein aggravates osteoarthritis development in mice on a high-fat diet. Osteoarthr Cartil. 2019;27(1):118-128. doi:10.1016/j.joca.2018.09.007 [4]Rajab IM, Majerczyk D, Olson ME, et al. C-reactive protein in gallbladder diseases: diagnostic and therapeutic insights. Biophys Reports. 2020;6(2-3):49-67. doi:10.1007/s41048-020-00108-9 [5]Wu Y, Potempa LA, El Kebir D, Filep JG. C-reactive protein and inflammation: conformational changes affect function. Biol Chem. 2015;396(11):1181-1197. doi:10.1515/hsz-2015-0149 [6]Thiele JR, Zeller J, Bannasch H, Stark GB, Peter K, Eisenhardt SU. Targeting C-Reactive Protein in Inflammatory Disease by Preventing Conformational Changes. Mediators Inflamm. 2015;2015(372432):9. doi:10.1155/2015/372432 [7]Khreiss T, József L, Hossain S, Chan JSD, Potempa LA, Filep JG. Loss of pentameric symmetry of C-reactive protein is associated with delayed apoptosis of human neutrophils. J Biol Chem. 2002;277(43):40775-40781. doi:10.1074/jbc.M205378200 [8]Jia ZK, Li HY, Liang YL, Potempa LA, Ji SR, Wu Y. Monomeric C-reactive protein binds and neutralizes receptor activator of NF-κB ligand-induced osteoclast differentiation. Front Immunol. 2018;9(FEB). doi:10.3389/fimmu.2018.00234 [9]Francisco V, Ruiz-Fernández C, Pino J, et al. Adipokines: Linking metabolic syndrome, the immune system, and arthritic diseases. Biochem Pharmacol. 2019;165:196-206. doi:10.1016/j.bcp.2019.03.030 [10]Ullah N, Ma FR, Han J, et al. Monomeric C-reactive protein regulates fibronectin mediated monocyte adhesion. Mol Immunol. 2020;117:122-130. doi:10.1016/j.molimm.2019.10.013 [11]Boras E, Slevin M, Alexander MY, et al. Monomeric C-reactive protein and Notch-3 co-operatively increase angiogenesis through PI3K signalling pathway. Cytokine. 2014;69(2):165-179. doi:10.1016/j.cyto.2014.05.027 Disclosure of Interests: None declared