The toxic effects of 4-octylphenol (4-OP) have been studied in species such as mouse and fish; however, the toxic effects of 4-OP in male specific niche cells has not been researched. In this study, we investigated the molecular mechanism of toxicity of 4-OP in mouse TM4 Sertoli cells. TM4 cells were treated with four concentrations (0, 10, 30, and 50 µM/mL) of 4-OP at time points 24, 48, and 72 h. Cell viability and apoptosis assay was conducted following exposure. 4-OP significantly decreased cell viability in a concentration- and time-dependent manner, and increased apoptosis. Quantitative PCR analysis showed that Bad, Bax, and Bak mRNA expression levels were higher in exposed cells than in the control, but Bcl-2 expression was decreased. Western blotting revealed that 4-OP induced activities of caspase-3 and phosphorylation of Bad in a concentration- and time-dependent manner. Additionally, cytochrome C protein did not colocalize with mitochondria marker dye by 24 h. Cytochrome c protein expression increased in a time-dependent manner with 50 µM/mL. These results suggest that 4-OP induces mitochondria-mediated apoptosis by regulation of Bcl-2 family proteins and caspase-3 activation in male Sertoli cells.

Acellular bacterial ghosts (BGs) are empty non-living bacterial cell envelopes, commonly generated by controlled expression of the cloned lysis gene E of bacteriophage PhiX174. In this study, Vibrio parahaemolyticus ghosts (VPGs) were generated by chemically induced lysis and the method is based on minimum inhibitory concentration (MIC) of sodium hydroxide (NaOH), acetic acid, boric acid, citric acid, maleic acid, hydrochloric acid and sulfuric acid. The MIC values of the respective chemicals were 3.125, 6.25, < 50.0, 25.0, 6.25, 1.56 and 0.781 mg/ml. Except boric acid, the lysis efficiency was reached more than 99.99% at 5 min after treatment of all chemicals. Among those chemicals, NaOH-induced VPGs showed completely DNA-free that was confirmed by quantitative real-time PCR. Besides, lipopolysaccharides (LPS) extracted from the NaOH-induced VPGs showed no distinctive band on SDS-PAGE gel after silver staining. On the other hand, LPS extracted from wild-type bacterial cells as well as the organic acids-induced VPGs showed triple major bands and LPS extracted from the inorganic acids-induced VPGs showed double bands. It suggests that some surface structures in LPS of the NaOH-induced VPGs may be lost, weakened or modified by the MIC of NaOH. Nevertheless, Limulus amoebocyte lysate assay revealed that there is no significant difference in endotoxic activity between the NaOH-induced VPGs and wild-type bacterial cells. Macrophages exposed to the NaOH-induced VPGs at 0.5 × 106 CFU/mL showed cell viability of 97.9%, however the MIC of NaOH did not reduce the cytotoxic effect of wild-type bacterial cells. Like Escherichia coli LPS, the NaOH-induced VPGs are an excellent activator of pro-inflammatory cytokines (IL-1β and iNOS), anti-inflammatory cytokine (IL-10) and dual activities (IL-6) in the stimulated macrophage cells. On the other hand, the induction of TNF-α mRNA was remarkable in the macrophages exposed with wild-type cells. Scanning electron microscopy showed the formation of trans-membrane lysis tunnel structures in the NaOH-induced VPGs. SDS-PAGE and agarose gel electrophoresis also confirmed that cytoplasmic proteins and genomic DNA released from the VPGs to culture medium through the lysis tunnel structures. Taken together, all these results indicated that the NaOH-induced VPGs show the potency of safe, economical and effective inactivated bacterial vaccine candidate.