Study on the possible role of heat shock proteins in host resistance to Trichinella spiralis infection in experimental animals.

The expression of heat shock proteins (HSPs) and their immunogenic role in host parasite relationship has been studied in T. spiralis infection in mice. Two groups of infective stage larvae were incubated at 37 degrees C or at 43 degrees C for 3 hours in a nutrient medium. Crude somatic extracts and excretory/secretory (E/S) products were obtained. Quantitative estimation and in vitro translation of mRNA were carried out. Crude somatic extracts, E/S products and in vitro translated proteins were all subjected to SDS-PAGE and immunoelectrophoresis against a monoclonal antibody to HSP70. They were further used to immunize mice which were then infected with T. spiralis. The degree of immunization was assessed by counting adult worms, muscle larvae and estimating total gamma globulins of mice. SDS-PAGE revealed intense peaks of 71 KDa and 81 KDa in all proteins obtained from heat shocked larvae. These proteins have been proved to involve HSP70 as manifested by their strong reactivity with anti-HSP70. In vitro translated products of heat shocked larvae (at 43 degrees C) proved to be strongly immunogenic as evidenced by the lower adult worm, muscle larval counts and higher total gamma globulins in sera of mice in comparison with the control non immunized group as well as to other larval antigens incubated at 37 degrees C. So, exposure to heat, can induce the synthesis of heat shock proteins which can defend the organism against environmental stress. Meanwhile, these heat shock proteins can render the host more refractory to reinfection.

The role of Fas system [Fas-FasL] as an inducer of apoptosis in cutaneous leishmaniasis: a combined human and experimental study.

Cutaneous leishmanial lesions as well as serum samples from both infected human and Swiss-albino mice were used to investigate the role of Fas system (Fas-FasL) as an inducer of apoptosis and other leishmanicidal cytokines in the disease development in cutaneous leishmaniasis. Soluble Fas was estimated by ELISA, other leishmanicidal cytokines were detected by PAP technique and tissue Fas by RT-PCR. Results showed a significant increase in interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), nitric oxide (NO) and soluble Fas in both infected human and mice. As regards the tissue Fas, there was marked expression in human samples while in murine samples, the expression was reduced in chronic infected mice than in the late acute infected animals which can explain the progression of the lesion in the animals. This study confirms the role of Fas system as an inducer of apoptosis.