ACTINOBACILLUS-ACTINOMYCETEMCOMITANS Y4 CAPSULAR-POLYSACCHARIDE-LIKE POLYSACCHARIDE PROMOTES OSTEOCLAST-LIKE CELL-FORMATION BY INTERLEUKIN-1-ALPHA PRODUCTION IN MOUSE MARROW CULTURES

The mechanism of osteoclast-like cell formation induced by periodontop athic bacterium Actinobacillus actinomycetemcomitans Y4 (serotype b) c apsular-polysaccharide-like polysaccharide (capsular-like polysacchari de) was examined in a mouse bone marrow culture system. When mouse bon e marrow cells were cultured with A. actinomycetemcomitans Y4 capsular -like polysaccharide for 9 days, many multinucleated cells were formed . The multinucleated cells showed several characteristics of osteoclas ts, including tartrate-resistant acid phosphatase (TRACP) and the abil ity to resorb the calcified dentine. In this study, we examined the ef fects of antisera to interleukins on the formation of osteoclast-like cells induced by A. actinomycetemcomitans Y4 capsular-like polysacchar ide. Monospecific anti-mouse recombinant interleukin-1 alpha (rIL-1 al pha) serum completely inhibited the formation of osteoclast-like cells in the presence of A. actinomycetemcomitans Y4 capsular-like polysacc haride. However, anti-mouse rIL-1 beta and anti-mouse rIL-6 sera showe d no effect on osteoclast-like cell formation. IL-1 receptor antagonis t significantly inhibited the osteoclast-like cell formation mediated by A. actinomycetemcomitans Y4 capsular-like polysaccharide in mouse m arrow cultures. The bioactive IL-1 was detected in the culture media o f mouse bone marrow cells stimulated with A. actinomycetemcomitans Y4 capsular-like polysaccharide. These results indicate that IL-1 alpha i s involved in the mechanism of the formation of osteoclast-like cells induced by A. actinomycetecomitans Y4 capsular-like polysaccharide. We sought to determine whether osteoclast-like cell formation induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide could be mod ulated by the protein kinase inhibitors H8 and HA1004. The formation o f osteoclast-like cells was suppressed by H8 and HA1004. These finding s suggest that the signals by protein kinases may regulate osteoclast- like cell formation induced by A. actinomycetecomitans Y4 capsular-lik e polysaccharide. Furthermore, a correlation between IL-1 alpha and pr ostaglandin E(2) in the osteoclast recruitment induced by A. actinomyc etemcomitans Y4 capsular-like polysaccharide is discussed.