Antibacterial activity of the human host defence peptide LL-37 and selected synthetic cationic lipids against bacteria associated with oral and upper respiratory tract infections.

OBJECTIVES: We aim to develop antibacterial peptide mimics resistant to protease degradation, with broad-spectrum activity at sites of infection. METHODS: The bactericidal activities of LL-37, ceragenins CSA-13, CSA-90 and CSA-92 and the spermine-conjugated dexamethasone derivative D2S were evaluated using MIC and MBC measurements. Gingival fibroblast counting, interleukin-8 (IL-8) and lactate dehydrogenase (LDH) release from keratinocytes (HaCat) were used to determine effects on cell growth, pro-inflammatory response and toxicity. RESULTS: All tested cationic lipids showed stronger bactericidal activity than LL-37. Incubation of Staphylococcus aureus with half the MIC of LL-37 led to the appearance of bacteria resistant to its bactericidal effects, but identical incubations with CSA-13 or D2S did not produce resistant bacteria. Cathelicidin LL-37 significantly increased the total number of gingival fibroblasts, but ceragenins and D2S did not alter gingival fibroblast growth. Cationic lipids showed no toxicity to HaCat cells at concentrations resulting in bacterial killing. CONCLUSIONS: These data suggest that cationic lipids such as ceragenins warrant further testing as potential novel antibacterial agents.

Salivary mucins inhibit antibacterial activity of the cathelicidin-derived LL-37 peptide but not the cationic steroid CSA-13.

OBJECTIVES: Cationic antimicrobial peptides (CAPs) are the effector molecules of innate immunity, similar in potency to classic antibiotics that function in the first-line of defence against infectious agents. The purpose of this study was to investigate the effects of negatively charged mucins on the antibacterial activity of the positively charged cathelicidin LL-37 peptide, its synthetic analogue WLBU2 and the antimicrobial cationic steroid CSA-13. METHODS: Mucin, DNA, F-actin and hCAP-18/LL-37 in saliva samples were evaluated by microscopy or immunoblotting. Bacterial killing assays and determination of MICs were used to determine bactericidal activity. Binding of rhodamine-B-labelled LL-37 peptide to mucin was fluorimetrically assessed. RESULTS: Microscopic evaluation of saliva after addition of rhodamine-B-labelled LL-37 showed localization similar to that observed after the addition of a specific mucin-binding lectin. Immunoblotting confirmed the presence of hCAP-18/LL-37 in saliva samples and LL-37 peptide bound to isolated submaxillary gland mucin-coated plates. Mucin/LL-37 binding was partially prevented by treatment of mucin with neuraminidase, indicating involvement of sialic acid moieties. Decreased LL-37 and WLBU2 antibacterial activity was observed in the presence of mucin or dialysed human saliva, whereas CSA-13 antibacterial activity was significantly resistant to inhibition by mucins. CONCLUSIONS: This study shows that the antibacterial LL-37 peptide and its synthetic analogue WLBU2 are inhibited by salivary mucin and that the cationic steroid CSA-13 retains most of its function in the presence of an equal amount of mucin or saliva.

Effect of antibacterial therapy and salivary secretion on the efficacy of Helicobacter pylori eradication in duodenal ulcer patients.

OBJECTIVE: Oral health status may play a role in Helicobacter pylori eradication. Because adequate secretion of saliva promotes oral health, the aim of the study was to assess the effect of salivary secretion on the efficacy of H pylori eradication from the stomach. STUDY DESIGN: The study involved 90 H pylori-positive subjects with duodenal ulcer (68 men, 22 women, aged 20-70 years) in whom saliva was collected under basal conditions for 45 min before antibacterial treatment began. They received no drugs for at least 3 days prior to saliva collection. A 7-day course of either of 2 eradication regimens--omeprazole, amoxicillin, and tinidazole (OAT); or omeprazole, amoxicillin, and clarithromycin (OAC)--was used. The efficacy of eradication therapy was evaluated 30 days after its completion. RESULTS: The efficacy of H pylori eradication from the stomach (per protocol analysis) was 77.5% in the group of subjects treated with OAT and 81.6% with OAC. Combined analysis of both groups (OAT+OAC) showed reduced salivary secretion in subjects with eradication failure (0.395 +/- 0.266 vs 0.25 +/- 0.176 mL/min, P=.042). A similar outcome was obtained when the OAT group was analyzed separately (0.436 +/- 0.316 vs 0.211 +/- 0.216 mL/min, P=.022), but in the OAC group the difference was not significant. In the combined analysis, the efficacy of eradication therapy was lower in women than in men (52.9% vs 86.9%, P=.005). In women, it corresponded to salivary secretion (successful eradication 0.337 +/- 0.133 mL/min, unsuccessful eradication 0.180 +/- 0.144 mL/min, P=.043); whereas in men, the difference was not significant (successful eradication 0.405 +/- 0.282 mL/min, unsuccessful eradication 0.321 +/- 0.186 mL/min). CONCLUSION: Low salivary secretion may contribute to the decrease in efficacy of H pylori eradication from the stomach, at least in subjects treated with certain drug regimens.

Oral health status and oral hygiene practices of patients with peptic ulcer and how these affect Helicobacter pylori eradication from the stomach.

BACKGROUND: Helicobacter pylori eradication from the oral cavity is more difficult than from the stomach. Thus, if the bacterium survives the antibacterial therapy in the oral cavity, it would be able to re-infect the stomach within a few weeks. Since oral health status could correspond to oral infection with H. pylori, the aim of the study was to determine whether oral health and oral hygiene practices affect the efficacy of H. pylori eradication from the stomach. MATERIAL AND METHODS: The study was performed in 137 patients with peptic ulcer who had undergone a 7-day course of eradication treatment with one of two sets of drugs: 1, omeprazole, amoxicillin, and tinidazole or 2, omeprazole, clarithromycin, and tinidazole. The efficacy of H. pylori eradication from the stomach was evaluated at the second gastroscopy 4 weeks after cessation of eradication therapy by means of two methods: rapid urease test and histology. The examination of natural dentition and prosthetic restorations as well as the assessment of hygienic procedures referring to natural dentition and dentures accompanied the second gastroscopy. RESULTS: No association was found between the efficacy of H. pylori eradication from the stomach and the number of natural teeth, decayed teeth, use of dentures, debris index, or periodontal index. However, an association between eradication success and some oral hygiene procedures were noted. Unexpectedly, in patients treated with omeprazole, amoxicillin and tinidazole, the removal of dental prosthesis for the night and brushing the natural teeth twice a day or more reduced the efficacy of H. pylori eradication from the stomach. CONCLUSIONS: Oral health and oral hygiene practices seem unlikely to increase the efficacy of H. pylori eradication from the stomach.