Effect of Cysticercus cellulosae fractions on the respiratory burst of pig neutrophils

Functional characterization of partial recombinant goat conglutinin: Its role as innate immunity marker and use as antigen in sandwich ELISA

Conglutinin, a liver synthesized versatile innate immune marker consisting C-type lectin domain belongs to collectin superfamily of proteins. The protein, first detected in bovine serum as soluble pattern recognition receptor (PRR) has wide range of antimicrobial activities. In the present study, open reading frame (ORF) encoding neck and carbohydrate recognition domain (NCRD) of goat conglutinin gene ligated to the vector pRSET-A was expressed in E. coli BL-21(pLys) cells. The 27 kDa recombinant protein (rGCGN) purified by single step Ni⁺² -NTA affinity chromatography was found to cross-react with recombinant anti-buffalo conglutinin antibody raised in poultry. Further, it displayed calcium-dependant sugar binding activity towards yeast mannan and calcium-independent binding activity towards LPS. The mannan binding activity of rGCGN was inhibited in the presence of N-acetyl-glucosamine because of higher affinity towards this sugar. The recombinant protein was found to stimulate production of superoxide ions and hydrogen peroxide in goat neutrophils, which are instrumental in stimulating phagocytic activity of cells. When used as antigen in Sandwich ELISA, straight line (Y = 0.299x + 0.067, R² = 0.997) was observed within the concentration range of 200-1000 ng/100 μl of rGCGN. Using this equation, the native conglutinin concentration in goat sera was estimated to be 0.5-7.5 μg/ml. The results indicated that prokaryotically expressed functionally active rGCGN can be used as antigen to assess native serum conglutinin levels in Sandwich ELISA and as immunomodulator in therapeutic applications to sequester unwanted immune complexes from the circulation.

The state of art of neutrophil extracellular traps in protozoan and helminthic infections

Neutrophil extracellular traps (NETs) are DNA fibers associated with histones, enzymes from neutrophil granules and anti-microbial peptides. NETs are released in a process denominated NETosis, which involves sequential steps that culminate with the DNA extrusion. NETosis has been described as a new mechanism of innate immunity related to defense against different pathogens. The initial studies of NETs were carried out with bacteria and fungi, but currently a large variety of microorganisms capable of inducing NETs have been described including protozoan and helminth parasites. Nevertheless, we have little knowledge about how NETosis process is carried out in response to the parasites, and about its implication in the resolution of this kind of disease. In the best case, the NETs entrap and kill parasites in vitro, but in others, immobilize the parasites without affecting their viability. Moreover, insufficient studies on the NETs in animal models of infections that would help to define their role, and the association of NETs with chronic inflammatory pathologies such as those occurring in several parasitic infections have left open the possibility of NETs contributing to pathology instead of protection. In this review, we focus on the reported mechanisms that lead to NET release by protozoan and helminth parasites and the evidence that support the role of NETosis in the resolution or pathogenesis of parasitic diseases.

Anti-oxidant activity of superoxide dismutase and glutathione peroxidase enzymes in skeletal muscles from slaughter cattle infected with Taenia saginata

It is known that highly reactive oxygene species produced during normal cellular metabolism represent a powerful effector mechanism against parasites. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) belong to the main defense anti-oxidants that prevent the formation of new free radical species. The aim of this study was to assess the activities of SOD and GPx in cattle tissues infected with Taenia saginata. We observed a statistically significant increase in the SOD and GPx activities (p=0.00003, 0.00008, respectively, Student's t-test) in skeletal muscles infected with T. saginata in spectrophotometric analysis. With the use of western blot technique, SOD synthesis stimulation has appeared in the host tissues containing cysticerci in contrast with the control samples. There was no statistically significant increase in the GPx band intensity observed in the studied samples in comparison to controls (Gene Tools Version 4.01 program). These results support the significance of anti-oxidant processes in host defense mechanism during parasitic infections.

Effects of protoscoleces and AgB from Echinococcus granulosus on human neutrophils: possible implications on the parasite's immune evasion mechanisms

The factors affecting the innate susceptibility to Echinococcus granulosus infections are largely unknown. We assessed the interaction of healthy human neutrophils with protoscoleces (PSC) and antigen B (AgB) of E. granulosus by analysis of CD11b upregulation and H(2)O(2) production by flow cytometry. PSC induced neutrophil activation, but their viability was not affected. In contrast, no effects were observed with AgB in both assays. Neutrophil-enriched fractions were also incubated with PSC or AgB, and interleukin 8 (IL-8) production was measured by ELISA. Significant increment in IL-8 production was detected only in supernatants from neutrophil-enriched fractions cultured with PSC. The possible effect of a prior incubation with AgB on the phorbol myristate acetate-induced activation was also evaluated. No changes were observed in CD11b expression, but the H(2)O(2) production was significantly reduced in platelet-activating factor (PAF)-primed neutrophils. These results suggest a possible AgB-mediated mechanism of evasion of the host immune response, which would operate upon events of spillage of the fertile hydatid cyst content.