Toll-like receptor agonists Porphyromonas gingivalis LPS and CpG differentially regulate IL-10 competency and frequencies of mouse B10 cells

Abstract IL-10 expressing regulatory B cells (B10) play a key role in immune system balance by limiting excessive inflammatory responses. Effects of toll-like receptor signaling and co-stimulatory molecules on B10 activity during innate and adaptive immune responses are not fully understood. Objective This study is to determine the effects of P. gingivalis LPS and CpG on B10 cell expansion and IL-10 competency in vitro. Material and Methods Spleen B cells were isolated from C57BL/6J mice with or without formalin-fixed P. gingivalis immunization. B cells were cultured for 48 hours under the following conditions: CD40L, CD40L+LPS, CD40L+CpG, and CD40L+LPS+CpG in the presence or absence of fixed P. gingivalis. Percentages of CD1dhiCD5+ B cells were measured by flow cytometry. IL-10 mRNA expression and secreted IL-10 were measured by real-time quantitative PCR and by ELISA respectively. Results P. gingivalis LPS plus CD40L significantly increased CD1dhiCD5+ B cell percentages and secreted IL-10 levels in both immunized and non-immunized mice B cells in the presence or absence of P. gingivalis, compared with control group. Secreted IL-10 levels were significantly increased in CD40L+LPS treated group compared with CD40L treatment group in the absence of P. gingivalis. CpG plus CD40L significantly decreased CD1dhiCD5+ B cell percentages, but greatly elevated secreted IL-10 levels in immunized and non-immunized mice B cells in the absence of P. gingivalis, compared with CD40L treatment group. Conclusions P. gingivalis LPS and CpG differentially enhance IL-10 secretion and expansion of mouse B10 cells during innate and adaptive immune responses.

Porphyromonas gingivalis Lipopolysaccharide Regulates Migration of Vascular Smooth Muscle Cells

Porphyromonas gingivalis, a foremost periodontal pathogen, has been known to cause periodontal diseases. Epidemiologic evidences have indicated the involvement of P. gingivalis in the development of cardiovascular diseases. In this study, we show that the P. gingivalis lipopolysaccharide increases the mRNA expression and protein secretion of interleukin-6 in vascular smooth muscle cells. We demonstrate that P. gingivalis LPS activates the extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and Akt, which mediate the IL-6 expression in vascular smooth muscle cells. Also, P. gingivalis LPS stimulates the vascular smooth muscle cell migration, which is a critical step for the progression of atherosclerosis. Moreover, neutralization of the IL-6 function inhibits the migration of vascular smooth muscle cells induced by P. gingivalis LPS. Taken together, these results indicate that P. gingivalis LPS promotes the expression of IL-6, which in turn increases the migration of vascular smooth muscle cells.