Search

Pregnenolone is a steroid hormone precursor that is synthesized in various steroidogenic tissues, in the brain, and in lymphocytes. In addition to serving as the precursor for other steroid hormones, pregnenolone exerts its own effect as an anti-inflammatory molecule to maintain immune homeostasis in various inflammatory conditions. Pregnenolone and its metabolic derivatives have been shown to have beneficial effects in the brain, including enhancing memory and learning, reversing depressive disorders, and modulating cognitive functions. A decreased level of pregnenolone has been observed in neuroinflammatory diseases, which emphasizes its role in neuroprotection and neuroregeneration. Although the anti-inflammatory property of pregnenolone was recognized several decades ago, its mechanism of action remains unknown. Here we report that pregnenolone promotes ubiquitination and degradation of the TLR2/4 adaptor protein TIRAP and TLR2 in macrophages and microglial cells. Pregnenolone and its metabolites suppressed the secretion of tumor necrosis factor α and interleukin-6 mediated through TLR2 and TLR4 signaling. Pregnenolone has been reported to induce activation of cytoplasmic linker protein 170, and this protein has recently been shown to promote targeted degradation of TIRAP. We observed enhanced degradation of TIRAP and TLR4 suppression by cytoplasmic linker protein 170 in the presence of pregnenolone. Our experimental data reveal novel nongenomic targets of pregnenolone and provide important leads to understand its role in restoring immune homeostasis in various inflammatory conditions.

Recombinant avian influenza vaccines offer several advantages over the conventional vaccines. In this study, the haemagglutinin (HA) gene of highly pathogenic avian influenza H5N1 was cloned and expressed as His tagged protein in methylotropic yeast Pichia pastoris. The expression of recombinant HA (rHA) protein was confirmed by SDS-PAGE and western blot analysis. The rHA protein was purified using Ni-NTA affinity chromatography under denaturing conditions and the functions of the protein was assessed by the haemagglutinin assay after refolding. The immunogenicity of the rHA was evaluated by immunizing four groups of mice with different payloads (2.5, 5.0, 10 and 25 μg) of purified rHA and the production of rHA specific antibodies were analysed by haemagglutinin inhibition assay (HI) and enzyme-linked immunosorbent assay (ELISA). An antigen specific immune response was observed against rHA indicating that the rHA antigen could be used as a vaccine candidate against avian influenza. These results suggest that this strategy would pave the way for the development of rapid and cost effective method for the production of an avian influenza vaccine.