Author(s)

Genu George¹, Molly Antony², Jaisy Mathai³, Padinjaradath S. Appukuttan^1*

¹Department of Biochemistry, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India.
²Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India.
³Department of Transfusion Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India.

Atheromatous plaques usually contain antigens of the periodontitis-causing bacteria Streptococcus mutans though molecular mechanism of this incorporation remains unknown. Since vascular adhesion and inflammatory potential of Immune Complexes (IC) are known we investigated the naturally occurring plasma antibodies that recognize major antigens from S. mutans. S. mutans-binding plasma proteins (SMBP) prepared by affinity chromatography on a column of heat-killed S. mutans could recognize α- and β-linked glucose in dextran and yeast respectively but not galactose in glycoproteins. SMBP contained only three proteins, each corresponding in electrophoretic mobility to standard plasma IgG, IgA or IgM. The major positively and negatively charged protein antigens (PSMAg and NSMAg) isolated from S. mutans by electrophoresis and ion exchange chromatography respectively were recognized sugar-reversibly by the anti-β-glucan antibody (ABG) and though less avidly, by the dextran-binding immunoglobulin (DIg) in normal plasma. NSMAg addition resulted in near doubling of IC-bound immunoglobulins in immunoglobulin-rich fraction of plasma. IC isolated from above fraction after NSMAg addition had substantially more IgA and IgM content than total plasma immunoglobulins. IC formation by NSMAg was significantly inhibited by ABG- and DIg-specific sugars or by selective withdrawal of ABG or DIg from plasma. ABG and DIg being relatively high titer plasma antibodies IC formation with them suggested a possible route for vascular adhesion and damage by S. mutans and its antigens. Further, high IgA content of these ICs indicated their susceptibility to tissue uptake through cell surface galectin-1 for which IgA is the lone immunoglobulin ligand.

Streptococcus mutans, Anti-β-Glucan Antibody (ABG), Dextran Binding Immunoglobulins (DIg), Immune Complexes

George, G. , Antony, M. , Mathai, J. and Appukuttan, P. (2016) Periodontitis and Inflammation: Plasma High Titer Naturally Occurring Anti-Glucan Antibodies Form Immune Complex with Streptococcus mutans Antigen. Modern Research in Inflammation, 5, 45-54. doi: 10.4236/mri.2016.53005.