Serum antibody reactivity against recombinant PrtC of Porphyromonas gingivalis following periodontal therapy

Functional study of gene hp0169 in Helicobacter pylori pathogenesis

Many virulence genes have been reported to play important roles in Helicobacter pylori pathogenesis. However the detailed mechanisms of many of them have not been completely clear. In this study, we found gene hp0169, encoding a putative collagenase (HpPrtC), was involved in pathogenesis of H. pylori. Recombinant HpPrtC shows activities to both native and heat-denatured collagens. This result indicated that HpPrtC may act as a virulence factor to help the bacterium colonize in their host stomach by degrading surrounding collagens. hp0169 was deleted by homologous recombination to study its function in bacterium-host cell interaction. For the pathogenic functions on the host cells, the hp0169 mutant exhibits no significant changes on inducing apoptosis of GES-1 cells. However, the viability and proliferation rate of GES-1 cells infected with mutant strain were higher than the cells infected with wild-type strain. These results indicated that except for its collagenolytic activity, HpPrtC might participate in H. pylori pathogenesis through an additional pathway. Functional studies on hp0169 involved in pathogenesis would shed light on deep understanding of the pathogenic mechanism of H. pylori.

In situ visualization of plasma cells producing antibodies reactive to Porphyromonas gingivalis in periodontitis: the application of the enzyme-labeled antigen method

Porphyromonas gingivalis is a keystone periodontal pathogen. Histologocally, the gingival tissue in periodontitis shows dense infiltration of plasma cells. However, antigens recognized by antibodies secreted from the immunocytes remain unknown. The enzyme-labeled antigen method was applied to detecting plasma cells producing P. gingivalis-specific antibodies in biopsied gingival tissue of periodontitis. N-terminally biotinylated P. gingivalis antigens, Ag53 and four gingipain domains (Arg-pro, Arg-hgp, Lys-pro and Lys-hgp) were prepared by the cell-free protein synthesis system using wheatgerm extract. With these five labeled proteins as probes, 20 lesions of periodontitis were evaluated. With the AlphaScreen method, antibodies against any one of the five P. gingivalis antigens were detected in 11 (55%) serum samples and 17 (85%) tissue extracts. Using the enzyme-labeled antigen method on paraformaldehyde-fixed frozen sections of gingival tissue, plasma cells were labeled with any one of the five antigens in 17 (94%) of 18 specimens, in which evaluable plasma cells were detected. The positivity rates in periodontitis were significantly higher than those found previously in radicular cysts (20% in sera and 33% in tissue extracts with the AlphaScreen method, and 25% with the enzyme-labeled antigen method). Our findings directly indicate that antibodies reactive to P. gingivalis are locally produced in the gingival lesions, and that inflammatory reactions against P. gingivalis are involved in periodontitis.

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.

Association between infection of different strains of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans in subgingival plaque and clinical parameters in chronic periodontitis

OBJECTIVE

The aim of this study was to investigate subgingival infection frequencies of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans strains with genetic variation in Chinese chronic periodontitis (CP) patients and to evaluate its correlation with clinical parameters.

METHODS

Two multiplex polymerase chain reaction (PCR) assays were developed to detect the 16SrDNA, collagenase (prtC) and fimbria (fimA) genes of P. gingivalis and the 16SrDNA, leukotoxin (lktA) and fimbria-associated protein (fap) genes of A. actinomycetemcomitans in 60 sulcus samples from 30 periodontal healthy subjects and in 122 subgingival plaque samples from 61 patients with CP. The PCR products were further T-A cloned and sent for nucleotide sequence analysis.

RESULTS

The 16SrDNA, prtC and fimA genes of P. gingivalis were detected in 92.6%, 85.2% and 80.3% of the subgingival plaque samples respectively, while the 16SrDNA, lktA and fap genes of A. actinomycetemcomitans were in 84.4%, 75.4% and 50.0% respectively. Nucleotide sequence analysis showed 98.62%~100% homology of the PCR products in these genes with the reported sequences. P. gingivalis strains with prtC+/fimA+ and A. actinomycetemcomitans with lktA+ were predominant in deep pockets (>6 mm) or in sites with attachment loss > or =5 mm than in shallow pockets (3~4 mm) or in sites with attachment loss < or =2 mm (P<0.05). P. gingivalis strains with prtC+/fimA+ also showed higher frequency in gingival index (GI)=3 than in GI=1 group (P<0.05).

CONCLUSION

Infection of P. gingivalis with prtC+/fimA+ and A. actinomycetemcomitans with lktA+ correlates with periodontal destruction of CP in Chinese. Nonetheless P. gingivalis fimA, prtC genes and A. actinomycetemcomitans lktA gene are closely associated with periodontal destruction, while A. actinomycetemcomitans fap gene is not.