Hybrid N-glycans on the host protective activation-associated secreted proteins of Ostertagia ostertagi and their importance in immunogenicity.

Previous vaccination trials with calves have shown that intramuscular immunization with natively purified activation-associated secreted proteins (ASPs) of Ostertagia ostertagi induces protection against a homologous challenge infection with a 74% reduction in cumulative faecal egg counts and a significant reduction in worm length. Recently, O. ostertagi ASP1 was recombinantly expressed using a baculovirus system and tested in a vaccination trial. However, immunized calves failed to recognize native ASPs and no protection was observed. These results suggest an important structural difference between the baculo r-ASP1 and its native counterpart. Therefore, we investigated whether glycans and/or structural epitopes are key features in the induction of a protective immune response. The results show that ASPs carry two hybrid N-glycosylations with a complex alpha-1,3-arm, an unprocessed alpha-1,6-arm and an alpha-1,6-fucose core. While removal of these glycans had little effect on antibody recognition by vaccinated animals, denaturing and reducing the proteins dramatically reduced recognition, suggesting the importance of conformational protein backbone epitopes.

Analysis of the translationally controlled tumour protein in the nematodes Ostertagia ostertagi and Caenorhabditis elegans suggests a pivotal role in egg production.

The translationally controlled tumour protein (TCTP) is a conserved protein which has been described for a wide range of eukaryotic organisms including protozoa, yeasts, plants, nematodes and mammals. Several parasitic organisms have been shown to actively secrete TCTP during host infection as part of their immuno-evasive strategy. In this study, we have studied TCTP in Ostertagia ostertagi, a parasitic nematode of cattle, and in the free-living nematode Caenorhabditis elegans. An analysis of the transcription and expression patterns showed that TCTP was present in the eggs of both species. This localisation is consistent for some other Strongylida such as Teladorsagia circumcincta, Cooperia oncophora and Haemonchus contortus. TCTP was also detected at low levels in excretory-secretory material from adult O. ostertagi worms. The role of TCTP in nematode biology was also investigated by RNA interference in C. elegans. Knock-down of C. elegans tctp (tct-1) transcription reduced the numbers of eggs laid by the hermaphrodite in the F(0) and F(1) generations by 90% and 72%, respectively, indicating a pivotal role of TCTP in reproduction.

Pro-inflammatory properties of stromal cell-derived factor-1 (CXCL12) in collagen-induced arthritis.

CXCL12 (stromal cell-derived factor 1) is a unique biological ligand for the chemokine receptor CXCR4. We previously reported that treatment with a specific CXCR4 antagonist, AMD3100, exerts a beneficial effect on the development of collagen-induced arthritis (CIA) in the highly susceptible IFN-gamma receptor-deficient (IFN-gammaR KO) mouse. We concluded that CXCL12 plays a central role in the pathogenesis of CIA in IFN-gammaR KO mice by promoting delayed type hypersensitivity against the auto-antigen and by interfering with chemotaxis of CXCR4+ cells to the inflamed joints. Here, we investigated whether AMD3100 can likewise inhibit CIA in wild-type mice and analysed the underlying mechanism. Parenteral treatment with the drug at the time of onset of arthritis reduced disease incidence and modestly inhibited severity in affected mice. This beneficial effect was associated with reduced serum concentrations of IL-6. AMD3100 did not affect anti-collagen type II antibodies and, in contrast with its action in IFN-gammaR KO mice, did not inhibit the delayed type hypersensitivity response against collagen type II, suggesting that the beneficial effect cannot be explained by inhibition of humoral or cellular autoimmune responses. AMD3100 inhibited the in vitro chemotactic effect of CXCL12 on splenocytes, as well as in vivo leukocyte infiltration in CXCL12-containing subcutaneous air pouches. We also demonstrate that, in addition to its effect on cell infiltration, CXCL12 potentiates receptor activator of NF-kappaB ligand-induced osteoclast differentiation from splenocytes and increases the calcium phosphate-resorbing capacity of these osteoclasts, both processes being potently counteracted by AMD3100. Our observations indicate that CXCL12 acts as a pro-inflammatory factor in the pathogenesis of autoimmune arthritis by attracting inflammatory cells to joints and by stimulating the differentiation and activation of osteoclasts.