Effect of Porphyromonas gingivalis PrtC on cytokine expression in ECV304 endothelial cells and its level in subgingival plaques from patients with chronic periodontitis.

AIM: To investigate the effect of the collagenase gene (prtC) product of Porphyromonas gingivalis on inducing host cells to secrete inflammatory cytokines, and to discuss the correlation between the PrtC level in subgingival plaque samples and clinical parameters. METHODS: A prokaryotic expression system pET32a-prtC-Escheria coli BL21DE3 was constructed. Antigenicity and immunoreactivity of the recombinant PrtC protein (rPrtC) was identified by Western blotting. ELISA was applied to detect interleukin (IL)-1alpha, IL-8, and TNF-alpha levels in supernatants from rPrtC-induced human umbilical vein endothelial cells (HUVEC) originated ECV304 cells. Clinical parameters recorded at baseline and after treatment included bleeding on probing (BOP), probing depth (PD), and attachment loss (AL). ELISA was established to measure the PrtC level in 196 subgingival plaque samples from 49 patients with chronic periodontitis. RESULTS: After coincubation with 1 microg/mL rPrtC for 24 h and with 5 or 10 microg/mL rPrtC for 12 h, the levels of IL-1 alpha, IL-8, and TNF-alpha secreted by the ECV304 cells increased significantly (P<0.05). The PrtC level in the BOP-positive or the > or =5 mm AL or > or = 6 mm PD sites was higher than that in the BOP-negative or the < or =2 mm AL or < or =6 mm PD sites (P<0.05), respectively. Compared with baseline, the PrtC levels in different AL sites or in the < or =6 mm PD pockets decreased remarkably after treatment (P<0.01), but in the BOP-positive or in the > 6 mm PD sites, the PrtC levels changed insignificantly (P>0.05). CONCLUSION: rPrtC is able to directly induce host cells to synthesize and secrete IL-1 alpha, IL-8, and TNF-alpha. The PrtC level in subgingival samples is correlated with BOP, AL, and PD.

[Cloning and expression of Porphyromonas gingivalis pgmA gene encoding outer membrane protein associated with fimbria].

OBJECTIVE: To clone pgmA gene of Porphyromonas gingivalis, to construct the expression vector of the gene and to identify immunity of the fusion protein. METHODS: The pgmA genes from ATCC 33277 and 47A-1 strains of P.gingivalis were amplified by high fidelity PCR. The nucleotide of the target DNA amplification fragments were sequenced after T-A cloning. The pET32a expression vectors inserted with pgmA gene fragments were constructed. PgmA fusion protein was expressed in E.coli strain BL21DE3 induced by IPTG with different dosages. Western blot test by using rabbit antiserum against the fusion protein was applied to determine immunity of the fusion protein. ELISA was applied to determine the immunoreaction of antibody against PgmA fusion protein and 65 strains of P.gingivalis isolates. RESULT: The nucleotide sequence homology of the cloned pgmA gene fragments from ATCC 33277 and 47A-1 strains was 100%. In comparison with the reported corresponding sequences, the homologies of the nucleotide sequences of the cloned pgmA gene fragments were 98.98%, while the homologies of their putative amino acid sequences were 99.18%. The expression output of PgmA fusion protein in pET32a-pgmA-BL21DE3 system was approximately 50% of the total bacterial proteins. PgmA fusion protein was able to induce rabbit to produce specific antibody that could combine with PgmA protein. 92.3% of P. gingivalis isolates (60/65) were able to react with the antibody against PgmA fusion protein. CONCLUSION: An expression system of P.gingivalis pgmA gene with high efficiency was established successfully. The expressed PgmA fusion protein possesse satisfied immunogenicity and immunoreactivity,which can be used as a candidate antigen in detection of P.gingivalis and possible development of corresponding vaccine.