Porphyromonas gingivalis LPS inhibits osteoblastic differentiation and promotes pro-inflammatory cytokine production in human periodontal ligament stem cells

Effect of retinoic acid on the function of lipopolysaccharide-stimulated bone marrow stromal cells grown on titanium surfaces

OBJECTIVE AND DESIGN

This study aimed to evaluate the effect of all-trans retinoic acid (atRA) on suppressing the inflammatory response and promoting the osteoblastic differentiation of bone marrow stromal cells (BMSCs) on titanium in a lipopolysaccharide (LPS)-induced microenvironment.

METHODS

BMSCs were divided into four groups and treated with LPS (1 μg/mL), atRA (1 nmol/L), LPS + atRA, or left untreated. Cells were then cultured on titanium surfaces and cell function compared. BMSC proliferation and osteoblastic differentiation were assessed using the MTT assay, alkaline phosphatase (ALP) activity, alizarin red staining, and quantitative real-time polymerase chain reaction (RT-PCR). Expression levels of inflammatory factors were measured by quantitative RT-PCR and enzyme-linked immunosorbent assay.

RESULTS

Increased mineralized nodule formation, ALP activity, osteocalcin, and osteopontin expression levels were detected in LPS + atRA-treated BMSCs after osteogenic induction, when compared with LPS-treated cells. In addition, the high levels of tumor necrosis factor-α, interleukin-1β, and receptor activator of nuclear factor-κ B ligand (RANKL) expression induced by LPS were inhibited after treatment with atRA.

CONCLUSIONS

Our results showed the effects of atRA on suppressing inflammatory responses and promoting osteoblastic differentiation of BMSCs on titanium in an LPS-induced microenvironment. This indicates the potential therapeutic value of atRA for treating peri-implants inflammatory disease.

Porphyromonas gingivalis: major periodontopathic pathogen overview

Porphyromonas gingivalis is a Gram-negative oral anaerobe that is involved in the pathogenesis of periodontitis and is a member of more than 500 bacterial species that live in the oral cavity. This anaerobic bacterium is a natural member of the oral microbiome, yet it can become highly destructive (termed pathobiont) and proliferate to high cell numbers in periodontal lesions: this is attributed to its arsenal of specialized virulence factors. The purpose of this review is to provide an overview of one of the main periodontal pathogens—Porphyromonas gingivalis. This bacterium, along with Treponema denticola and Tannerella forsythia, constitute the “red complex,” a prototype polybacterial pathogenic consortium in periodontitis. This review outlines Porphyromonas gingivalis structure, its metabolism, its ability to colonize the epithelial cells, and its influence upon the host immunity.