The dangers of sublethal carvacrol exposure: increases in virulence of Bacillus cereus during endophthalmitis.

Bacillus cereus can cause endophthalmitis through secretion of virulence factors, including hemolysin BL (Hbl) and nonhemolytic entertoxin (Nhe). Carvacrol is an extract from oregano oil, with potential for curtailing B. cereus endophthalmitis, due to antimicrobial and anti-inflammatory qualities. However, sublethal levels of carvacrol increases B. cereus virulence. The goal of this study was to investigate the increase in B. cereus virulence potential in response stress induced by a subinhibitory concentration (SIC) of carvacrol. Enterotoxin production and tissue damage were examined during ocular infections in vitro and in vivo. We hypothesized that the SIC of carvacrol would significantly increase toxin production in B. cereus without progressing systemically. RT-PCR determined SIC carvacrol-treated B. cereus had significantly higher hblC and nheA mRNA expression levels than controls in vitro. ELISA and RPLA analysis revealed a 46.8% and 50% increase in NheA and HblC toxin levels, respectively, in SIC-treated cultures. Caenorhabditis elegans-fed SIC carvacrol-treated B. cereus had a significantly higher mean mortality rate than nematodes fed untreated B. cereus. Significantly higher TNF-α levels were observed in SIC carvacrol-treated B. cereus mice compared to other treatment groups except for mice infected with B. cereus alone. Significantly higher IL-6 levels were also found in SIC-B. cereus mice. Histological analysis using Rose-Bengal and DAPI determined that the eyes of mice infected with SIC carvacrol-treated B. cereus had significantly more damage than eyes treated with B. cereus alone. The SIC of carvacrol increased B. cereus virulence in vitro and in vivo, with a mild systemic infection noted.

VAMP2 is implicated in the secretion of antibodies by human plasma cells and can be replaced by other synaptobrevins.

The production and secretion of antibodies by human plasma cells (PCs) are two essential processes of humoral immunity. The secretion process relies on a group of proteins known as soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), which are located in the plasma membrane (t-SNAREs) and in the antibody-carrying vesicle membrane (v-SNARE), and mediate the fusion of both membranes. We have previously shown that SNAP23 and STX4 are the t-SNAREs responsible for antibody secretion. Here, using human PCs and antibody-secreting cell lines, we studied and characterized the expression and subcellular distribution of vesicle associated membrane protein (VAMP) isoforms, demonstrating that all isoforms (with the exception of VAMP1) are expressed by the referenced cells. Furthermore, the functional role in antibody secretion of each expressed VAMP isoform was tested using siRNA. Our results show that VAMP2 may be the v-SNARE involved in vesicular antibody release. To further support this conclusion, we used tetanus toxin light chain to cleave VAMP2, conducted experiments to verify co-localization of VAMP2 in antibody-carrying vesicles, and demonstrated the coimmunoprecipitation of VAMP2 with STX4 and SNAP23 and the in situ interaction of VAMP2 with STX4. Taken together, these findings implicate VAMP2 as the main VAMP isoform functionally involved in antibody secretion.

Anti-nuclear antibodies positive serum from systemic lupus erythematosus patients promotes cardiovascular manifestations and the presence of human antibody in the brain.

BACKGROUND: Systemic lupus erythematosus (SLE) is characterized by the presence of anti-nuclear antibodies (ANAs) in the serum of patients. These antibodies may cross over into the brain resulting in the development of neuropsychiatric symptoms and result in abnormal pathology in other organs such as the heart and kidneys. OBJECTIVE: The objective of this study was to determine if SLE pathology could be detected in the hearts and brains of rats injected with positive human ANA serum. MATERIALS AND METHODS: Lewis rats (n = 31) were selected for this study due to documented research already performed with this strain in the investigation of serum sickness, encephalitis and autoimmune related carditis. Rats were injected once a week with either ANA positive or negative control serum or saline. Hearts were examined for initial signs of heart disease including the presence of lipid deposits, vegetation, increased ventricular thickness and a change in heart weight. Brains were examined for the presence of human antibody and necrotic lesions. Animals were observed for outward signs of neuropathy as well. Blood samples were taken in order to determine final circulating concentrations of IgG and monitor histamine levels. RESULTS: Animals injected with ANA were significantly higher for lipid deposits in the heart and an increased ventricular thickness was noted. One animal even displayed Libman-Sacks endocarditis. Brains were positive for the presence of human IgG and diffuse internal lesions occurred in 80% of the ANA positive serum injected animals examined. Blood histamine levels were not significantly different, but actually lower than controls by the end of the experiment. CONCLUSION: Since human antibodies were detected in the brain, further studies will have to identify which antibody cross reactions are occurring within the brain, examine cell infiltration as well as characterize the antibodies associated with more destructive consequences such as lesion formation.