B. ABORTUS INFECTION MODULATES OSTEOCYTE FUNCTION

PESCE VIGLIETTI AYELÉN ; GENTILINI M. VIRGINIA; ARRIOLA BENITEZ PAULA C.; VELAZQUEZ LIS; GIAMBARTOLOMEI GUILLERMO H.; DELPINO M. VICTORIA

Congreso; LIX REUNIÓN CIENTÍFICA ANUAL Sociedad Argentina de Investigación Clínica LXII REUNIÓN ANUAL Sociedad Argentina de Inmunología; 2014

Osteoarticular brucellosis is the most common localization ofhuman active disease. Osteocytes are the most abundant cellsof bone. They secrete factors that regulate osteoclast differentiation(cells involved in bone resorption). The aim is to determineif Brucella abortus (Ba) infection modifies osteocyte (MLO-Y4)function. Cytokine and chemokine production was determined byELISA, osteoclast differentiation was determined by microscopyas the number of multinucleated cells that express tartrate-resistantacid phosphatase (TRAP). Conexin 43, E11/gp38, integrin-α and -β,tubulin-α, CD44 expression was determined by qRT-PCR. Apoptosiswas determined by Hoechst dye 33342 (microscopy) and by AnnexinV-FITC/Propidium Iodide (PI) (cytometry). Ba infection induced thesecretion of pro-inflammatory cytokines (IL-6 and TNF-α, but notIL-1β), KC and RANKL (the main regulator of osteoclastogenesis) byosteocytes. In inflammatory condition TNF-α could be also involvedin osteoclastogenesis. Our results indicated that supernatants fromBa infected osteocytes could induce osteoclast differentiation ofmonocytes in the presence of M-CSF (p<0,001). Using a neutralizingantibody against TNF-α or osteoprotegerin (OPG), RANKL?sdecoy receptor, we determined that TNF-α and RANKL are involvedin osteoclastogenesis induced by supernatants from Ba- infectedosteocytes, since the number of TRAP+ multinucleated cells weresignificantly reduced (p<0.01). Conexin 43 and accessory moleculessuch as E11/gp38, integrin-α and -β, tubulin-α, and CD44 areinvolved in cell-cell interaction necessary for osteocyte survival. Bainfection inhibits the expression of all molecules studied (p<0.05).This indicated that Ba-infection could alter osteocyte survival. Wefound that Ba infection induced osteocyte apoptosis, Hoechst dye33342 (p<0.01) and Annexin V-FITC/ PI (p<0.01). Taking togetherour results indicated that Ba-infection could alter osteocyte functioncontributing to bone damage.