Destructive Intestinal Translocation of Vibrio vulnificus Determines Successful Oral Infection

Vibrio vulnificus causes primary septicemia as a result of the consumption of contaminated seafood. The intestinal epithelial layer is the first host barrier encountered by V. vulnificus upon oral intake; however, epithelial translocation (invasion) of V. vulnificus has not been extensively studied. In this study, we investigated in vivo translocation of V. vulnificus using clinical (CMCP6) and environmental isolates (96-11-17M). And we analyzed physiological changes of intestinal epithelium concurrent with bacterial translocation by using polarized HCA-7 transwell culture system. The efficiency of epithelial translocation of 97-11-17M strains was significantly lower than that of pathogenic clinical isolate CMCP6 in a murine ligated ileal loop model. In an oral infection model, the survival rate was reciprocally related with efficacy of in vivo epithelial translocation. These results indicate that efficient translocation of V. vulnificus through intestinal epithelium is highly correlated with successful oral infection. We determined translocation of the bacteria from upper to lower chamber, changes of transepithelial electric resistance (TER) and cytotoxicity of the polarized HCA-7 cells to understand general features of V. vulnificus invasion. Bacterial translocation was accompanied by big decrease of TER (about 90%) and about 50% cytotoxicity of the epithelial cells. Taken together, these results indicate that V. vulnificus actively translocates the epithelium by destruction of epithelium and the efficiency of intestinal invasion by V. vulnificus is critical for successful oral infection. From this result, it is suggested that integrity of intestinal barrier is an important factor for susceptibility to oral infection of V. vulnificus.

Intranasal immunization with a flagellin-adjuvanted peptide anticancer vaccine prevents tumor development by enhancing specific cytotoxic T lymphocyte response in a mouse model

PURPOSE: Human papillomavirus (HPV) is a significant cause of cervical cancer-related deaths worldwide. Because HPV is a sexually transmitted mucosal pathogen, enhancement of antigen-specific mucosal immune response likely serves good strategy for vaccination. However, mucosal vaccines generally do not induce strong enough immune responses. Previously we proved that a bacterial flagellin, Vibrio vulnificus FlaB, induce strong antigen-specific immune responses by stimulating the Toll-like receptor 5. In this study, we tested whether FlaB could serve as an effective mucosal adjuvant for a peptide-based HPV preventive cancer vaccine. MATERIALS AND METHODS: Mice were intranasally administered with a mixture of FlaB and E6/E7 protective peptides in 5-day interval for a total of two times. Five-days after the last vaccination, cellular immune responses of the vaccinated mice were analyzed. Tumor growth was also observed after a subcutaneous implantation of TC-1 cells bearing E6/E7 antigens. RESULTS: Intranasal administration of the E6/E7 peptide mixture with FlaB elicited a strong antigen-specific cytotoxic T lymphocyte activity and antigen-specific interferon-gamma production from splenocytes and cervical lymph node cells. Furthermore, FlaB, as a mucosal adjuvant, conferred an excellent protection against TC-1 tumor challenge with high survival rates in E6/E7 immunized animals. CONCLUSION: These results indicate that FlaB can be a promising mucosal adjuvant for nasal HPV vaccine development.

Effects of Phenylephrine on the Excitability of Medial Vestibular Nuclear Neurons in Rats

Coeruleo-vestibular pathway which connects locus coeruleus and vestibular nuclei is noradrenergic. This study was designed to elucidate the effects of phenylephrine on the spontaneous activity of acutely isolated medial vestibular nuclear neurons of rat by whole-cell patch-clamp technique. Sprague-Dawley rats, aged 14 to 16 days, were used. After enzymatic digestion, dissociated medial vestibular neurons were transferred to a recording chamber mounted on an inverted microscope, and spontaneous action potentials were recorded by standard patch-clamp techniques. In current-clamp mode, the frequency of spontaneous action potential of medial vestibular nuclear neurons was decreased by phenylephrine (n=15). Phenylephrine increased the amplitude of afterhyperpolarization without changes in the resting membrane potential and spike width. In voltage-clamp mode, the whole potassium currents of the medial vestibular nuclear neurons were increased by phenylephrine (n=12). These experimental results suggest that alpha-receptor mediates the inhibitory effects on the neuronal activity of the medial vestibular nuclear neuron.