Claudia Nonnenmacher

DNA from periodontopathogenic bacteria is immunostimulatory for mouse and human immune cells

ABSTRACT Although bacterial DNA (bDNA) containing unmethylated CpG motifs stimulates innate immune cells through Toll-like receptor 9 (TLR-9), its precise role in the pathophysiology of diseases is still equivocal. Here we examined the immunostimulatory effects of DNA extracted from periodontopathogenic bacteria. A major role in the etiology of periodontal diseases has been attributed to Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Peptostreptococcus micros. We therefore isolated DNA from these bacteria and stimulated murine macrophages and human gingival fibroblasts (HGF) in vitro. Furthermore, HEK 293 cells transfected with human TLR-9 were also stimulated with these DNA preparations. We observed that DNA from these pathogens stimulates macrophages and gingival fibroblasts to produce tumor necrosis factor alpha and interleukin-6 in a dose-dependent manner. Methylation of the CpG motifs abolished the observed effects. Activation of HEK 293 cells expressing TLR-9 which were responsive to bDNA but not to lipopolysaccharide confirmed that immunostimulation was achieved by bDNA. In addition, the examined bDNA differed in the ability to stimulate murine macrophages, HGF, and TLR-9-transfected cells. DNA from A. actinomycetemcomitans elicited a potent cytokine response, while DNA from P. gingivalis and P. micros showed lower immunostimulatory activity. Taken together, the results strongly suggest that DNA from A. actinomycetemcomitans, P. gingivalis, and P. micros possesses immunostimulatory properties in regard to cytokine secretion by macrophages and fibroblasts. These stimulatory effects are due to unmethylated CpG motifs within bDNA and differ between distinct periodontopathogenic bacteria strains. Hence, immunostimulation by DNA from A. actinomycetemcomitans, P. gingivalis, and P. micros could contribute to the pathogenesis of periodontal diseases.

Comparison of two full-mouth approaches in the treatment of peri-implant mucositis: a pilot study.

OBJECTIVES The aim of the present study was to test the hypothesis that an additional full-mouth disinfection results in a greater clinical and microbiological improvement compared with sole mechanical debridement within one session in patients with peri-implant mucositis and treated chronic periodontitis. MATERIAL AND METHODS The study included 13 partially edentulous patients (mean age 51.5 years) with treated chronic periodontitis and 36 dental implants with mucositis (bleeding on probing and/or a gingival index > or =1 at least at one site at baseline, absence of peri-implant bone loss during the last 2 years before baseline). After randomized assignment to a test and a control group, patients received a one-stage full-mouth scaling with or without chlorhexidine. Clinical and microbiological examination was performed at baseline, after 1, 2, 4 and 8 months. Additional microbial samples were taken 24 h after treatment. Microbiological analysis was performed by real-time polymerase chain reaction. RESULTS Both treatment modalities resulted in significant reductions of probing depth at implant sites after 8 months, with no significant group differences. The bacteria at implants and teeth could be reduced in every group 24 h after treatment; however, this reduction was not significant after 8 months. CONCLUSIONS Both treatment modalities led to an improvement of the clinical parameters and a temporary reduction of the microflora at implants with mucositis, but without significant inter-group differences after 8 months.

One‐stage full‐mouth disinfection versus quadrant and full‐mouth root planing

OBJECTIVE The aim of this study was to test the hypothesis that the one-stage full-mouth disinfection (FMD) provides greater clinical and microbiological improvement compared with full-mouth scaling and root planing (FM-SRP) within 24 h and quadrant scaling and root planing (Q-SRP) in patients with generalized chronic periodontitis. MATERIAL & METHODS Twenty-eight patients were randomized into three groups. 25 patients completed the study and were the basis for analysis. The Q-SRP group was scaled quadrant-wise at 1-week intervals. The other groups received a one-stage full-mouth scaling with (FMD) and without (FM-SRP) chlorhexidine. At baseline, after 1, 2, 4 and 8 months clinical parameters were recorded and microbiological analysis was performed. RESULTS All three treatment modalities resulted in significant clinical improvement at any time. There were only group differences after 1 and 2 months: in the FM-SRP group was a significantly higher reduction of probing depth and bleeding on probing compared with the other two groups. The bacteria could be reduced in every group although this reduction was only significant for Prevotella intermedia in the FMD group 8 months after treatment. CONCLUSION All three treatment modalities lead to an improvement of the clinical and microbiological parameters, however, without significant group differences after 8 months.

Cost-effectiveness of rapid MRSA screening in surgical patients

This study investigates the effectiveness of a same-day polymerase chain reaction (PCR) test for the rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) in a general screening of patients admitted to the trauma surgery and heart surgery department in a German university hospital. A total of 442 patients were screened over a 4-month period by using a PCR assay, compared to culture methods, for specimens from the nose and throat. The MRSA carriage rate on admission was 3.85% during the study period. The PCR results of 1,680 swabs showed a sensitivity of 85% and a specificity of 99.39% for swabs from the nares and for the throat 42.11% and 98.78%, respectively. A combination of specimens from the nose and throat from the same patient led to a sensitivity of 100% with a specificity of 98.29%. Cost calculation under the circumstances of a diagnosis-related groups (DRG) payment system found that the eight MRSA-positive patients created costs of €38,472, i.e. €4,809 per patient, facing screening costs of €36.62 per sample. Screening patients by using the rapid PCR assay for a combination of specimens from the nose and throat would offer a safe and cost-effective way of MRSA screening on admission.

Effect of Age on Gingival Crevicular Fluid Concentrations of MIF and PGE2

We used an experimental gingivitis study design to compare crevicular fluid concentrations of Migration Inhibitory Factor (MIF) and Prostaglandin E2 (PGE2) in younger (18 to 30 yrs) and older (46 to 77 yrs) healthy adults. PGE2 increased after 1 wk in younger participants, whereas it decreased in older individuals after 1 wk of plaque accumulation. A significant interaction between age and time was observed for PGE2 (p = 0.04). High concentrations of MIF were identified in both age groups at baseline. MIF increased in the younger participants, whereas in the older individuals a decrease over time was observed. MIF concentration was positively correlated with plaque index and gingival index in the older age group. Total counts of bacteria, Parvimonas micra and Prevotella intermedia, were significantly correlated with MIF concentration in older participants. In conclusion, MIF and PGE2 production in response to bacterial accumulation seems to be modified by age.