Water-insoluble α-glucans from Streptococcus sobrinus induce inflammatory immune responses

Abstract

Recently, several studies have revealed that β-glucans in fungal cell wall components are known to modulate innate immunity. Water-insoluble α-glucans are synthesized from sucrose by glucosyltransferase-I of mutans streptococci and play an important role in the development of dental plaque. However, it remains unknown whether water-insoluble α-glucans also initiate these disease processes because of their innate immune response. In the present study, we showed that water-insoluble α-glucans synthesized by Streptococcus sobrinus activated mouse peritoneal exudate macrophages to produce proinflammatory cytokines. Furthermore, human monocytes stimulated by water-insoluble α-glucans produced TNF-α and IL-8, whereas human polymorphonuclear cells were activated by waterinsoluble α-glucans, resulting in chemotaxis and hydrogen peroxide production. The results demonstrated that water-soluble α-glucans modulate macrophage- and granulocyte-induced inflammatory immune responses, and suggest that inflammation induced by those α-glucans is associated with the development of periodontal diseases.