Interleukin-7 production by B lymphocytes affects the T cell-dependent osteoclast formation in an in vitro model derived from human periodontitis patients

PERIODONTITIS IS CHARACTERIZED BY IRREVERSIBLE DESTRUCTION OF ALVEOLAR BONE AND CONNECTIVE TISSUE ATTACHMENT IN THE PERIODONTIUM. WE RECENTLY REPORTED THAT T CELL SUPPORT THE OSTEOCLASTOGRENESIS BY THE OVERPRODUCTION OF NUCLEAR FACTOR-KAPPA-B-LIGAND (RANKL) AND TUMOR NECROSIS FACTORS ALFA(TNFa) IN AN IN VITRO OSTEOCLASTOGENESIS MODEL FROM PERIODONTITIS PATIENTS (Pp). IT IS KNOW THAT IL7 STIMULATES THE PRODUCTION OF OSTEOCLASTOGENESIS FACTORS BY T CELLS AND IL6 POTENTIATES IL7 EXPRESSION. THUS WE STUDIES THE INVOLVEMENT OF IL6 AND IL7 IN THE T CELLS REGULATION OF OSTEOCLAST (OC) FORMATION, IN AN INVITRO OSTEOCLASTOGENESIS MODEL FROM Pp. WE DEMONSTRATED HIGH LEVELS OF IL7 IN BOTH THE MEDIA COLLECTED FROM PBMC CULTURED OF Pp AND THE SERA OF THE SAME PATIENTS. WE ALSO DEMONSTRATED THAT FRESHLY ISOLATED B CELLS FROM PBMCs OF Pp WERE THE SOURCE OF IL7 IN OUR MODEL. B CELLS, IN FACT, OVEREXPRESSED IL7 AT mRNA AND PROTEIN LEVELS, AND THIS PRODUCTION WAS UP-REGULATED BY IL6. MOREOVER THE OC FORMATION DECREASED IN THE PRESENCE OF ANTI-IL6 AND IL7 FUNCTIONAL ANTIBODIES IN PBMC CULTURES FROM Pp. THESE DATA SUGGEST THAT B CELLS COULD BE RESPONSIBLE FOR THE T CELL-DEPENDENT OSTEOCLASTOGENESIS IN PERIODONTITIS THROUGH THE INVOLVMENT OF IL6 AND IL7.