Reduced proinflammatory activity of outer membrane vesicles of Tannerella forsythia treated with quorum sensing inhibitors.

Outer membrane vesicles (OMVs) of bacteria harbor physiologically active molecules, and quorum sensing inhibitors (QSIs) are expected to regulate bacterial virulence. In this study, we analyzed the proinflammatory activity of OMVs of the periodontal pathogen Tannerella forsythia treated with d-arabinose and d-galactose as QSIs, which inhibit the biofilm formation of periodontal pathogens and autoinducer 2 activity. Compared to OMVs of nontreated T. forsythia (TF OMVs), OMVs released from QSI-treated T. forsythia, designated TF ara-OMVs and TF gal-OMVs, showed reduced production of TNF-α, IL-1ß, IL-6, and IL-8 in THP-1 monocytes through decreased activation of NF-κB/MAPKs. Using a human NF-κB reporter cell line and bone marrow-derived macrophages from TLR2-/- mice, TF ara-OMVs and TF gal-OMVs showed less activation of TLR2 than TF OMVs. These results demonstrated that QSIs provide a dual advantage against bacterial infection by inhibiting bacterial biofilm formation and generating OMVs with reduced proinflammatory activity.

Inhibitory effect of d-arabinose on oral bacteria biofilm formation on titanium discs.

OBJECTIVES: Biofilm formation on dental implant surfaces can cause peri-implant mucositis and peri-implantitis. Lectins are involved in interactions between bacteria or between bacteria and their hosts. Disrupting these interactions via specific sugars can result in reduced adhesion and biofilm formation. The purpose of this study was to identify sugars that function as antiadhesion or antibiofilm agents on titanium discs. METHODS: Of the sugars tested, the sugars that did not affect the planktonic growth of Streptococcus oralis, Fusobacterium nucleatum, and Porphyromonas gingivalis were selected. The selected sugars were assessed for their ability to inhibit biofilm formation of bacteria in single and consortium species by crystal violet staining, confocal laser scanning microscopy after live/dead staining, and scanning electron microscopy. The sugars were evaluated for their ability to inhibit activity of the quorum sensing molecule autoinducer 2 (AI-2) by bioluminescence assay. RESULTS: Biofilm formation of single bacteria or consortia of S. oralis, F. nucleatum, and P. gingivalis on titanium discs was significantly inhibited in the presence of d-arabinose. Pretreating titanium discs with d-arabinose for 3 min inhibited biofilm formation at a level comparable to that observed when d-arabinose was present over the entire period, suggesting that d-arabinose had initial anti-adhesive activity. In addition, d-arabinose inhibited the activity of AI-2. CONCLUSIONS: d-Arabinose may be a good candidate for application as an antibiofilm agent and AI-2 inhibitor.

Successful readministration of second-line antituberculous agents in a patient with near-fatal drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome

For the treatment of multidrug-resistant (MDR) tuberculosis, maintenance of appropriate antituberculous agents is essential because of its low cure rate and high dropout rate. Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a severe drug-induced systemic hypersensitivity response resulting in cessation of causative agents. In cases of second-line antituberculous agent-induced DRESS, it is extremely difficult to find other replacement medications to cure MDR tuberculosis. A 53-year-old male who had taken the second-line antituberculous agents (cycloserine, streptomycin, p-aminosalicylic acid, and prothionamide) as well as pyrazinamide for 5 weeks experienced DRESS syndrome accompanying hepatic coma. His symptoms improved with discontinuation of antituberculous agents and administration of high-dose methylprednisolone for 1 month. To resume the antituberculous medication, second-line antituberculous agents were administered one by one using a rapid desensitization protocol. While kanamycin, levofloxacin, and cycloserine were successfully readministered, p-aminosalicylic acid- and prothionamide-induced cutaneous hypersensitivity symptoms were relatively mild compared to previous reactions. Herein, we report a case of successfully treated MDR tuberculosis having a history of fatal DRESS syndrome to antituberculous agents using the rapid desensitization protocol.