apyrase and Schistosomiasis

NTPDases are enzymes that hydrolyse diphosphate and triphosphate nucleosides, regulating purinergic signalling in many organisms. The Schistosoma mansoni NTPDases, SmATPDases 1 and 2, are antigenic proteins and display a significant homology with the isoforms found in mammalian cells. In this work, we investigated whether anti-SmATPDase antibodies from S. mansoni-infected mice sera show cross-reactivity with the NTPDase 1 isoform from macrophages and how this event affects the cell proliferation. By Western blot, anti-SmATPDase antibodies present in serum from infected mice recognized 2 bands with approximately 53 and 58 kDa, corresponding to NTPDase 1. Additionally, the enzyme was identified in macrophages by immunofluorescence and the anti-SmATPDase antibodies were able to reduce activity enzyme (22%). Macrophages incubated with commercial polyclonal antibodies reactive with NTPDase 1 (anti-CD39) showed a reduction of 40% of the enzyme activity. In proliferation assays, macrophage proliferation was inhibited 11% and 90% by pooled sera from infected animals and anti-CD39, respectively. The results suggest that inhibition of NTPDase 1 in macrophages by antibodies produced against the isoforms of the S. mansoni ATPDases could be a mechanism of regulation in the immune response during experimental schistosomiasis.

Topics: Animals; Antibodies, Protozoan; Antigens, CD; Antigens, Protozoan; Apyrase; Blotting, Western; Cell Line; Cell Proliferation; Cross Reactions; Female; Macrophages; Mice; Mice, Inbred C57BL; RAW 264.7 Cells; Schistosoma mansoni; Schistosomiasis; Snails

A polypeptide (r78-117) belonging to the potato apyrase was identified as a conserved domain shared with apyrase-like proteins from distinct pathogenic organisms, and was obtained as a 6xHis tag polypeptide (r-Domain B). By ELISA, high IgG, and IgG1 and IgG2a subtypes levels were detected in BALB/c mice pre-inoculated with r-Domain B. In Schistosoma mansoni adult worm or Leishmania (V.) braziliensis promastigote preparation, anti-r-Domain B antibodies inhibit 22-72% of the phosphohydrolytic activities and when immobilized on Protein A-Sepharose immunoprecipitate 42-91% of them. Western blots of the immunoprecipitated resin-antibody-antigen complexes identified bands of mw similar to those predicted for parasite proteins. Total IgG and subclasses of patients with leishmaniasis or schistosomiasis exhibited cross-immunoreactivity with r-Domain B. Therefore, the domain B within both S. mansoni SmATPDase 2 (r156-195) and L. (V.) braziliensis NDPase (r83-122) are potentially involved in the host immune response, and also seem to be conserved during host and parasites co-evolution.

Topics: Adult; Amino Acid Sequence; Animals; Antibodies, Helminth; Antibodies, Protozoan; Apyrase; Case-Control Studies; Conserved Sequence; Cross Reactions; Humans; Immunoprecipitation; Leishmania braziliensis; Leishmaniasis; Mice; Mice, Inbred BALB C; Middle Aged; Schistosoma mansoni; Schistosomiasis; Sequence Homology, Amino Acid; Trypanosoma cruzi

Evolutionary and closer structural relationships are demonstrated by phylogenetic analysis, peptide prediction and molecular modelling between Solanum tuberosum apyrase, Schistosoma mansoni SmATPase 2 and Leishmania braziliensis NDPase. Specific protein domains are suggested to be potentially involved in the immune response, and also seem to be conserved during host and parasite co-evolution. Significant IgG antibody reactivity was observed in sera from patients with American cutaneous leishmaniasis (ACL) and schistosomiasis using potato apyrase as antigen in ELISA. S. mansoni adult worm or egg, L. braziliensis promastigote (Lb) and Trypanosoma cruzi epimastigote (EPI) have ATP diphosphohydrolases, and antigenic preparations of them were evaluated. In ACL patients, IgG seropositivity was about 43% and 90% for Lb and potato apyrase, respectively, while IgM was lower (40%) or IgG (100%) seropositivity for both soluble egg (SEA) and adult worm (SWAP) antigens was higher than that found for potato apyrase (IgM=10%; IgG=39%). In Chagas disease, IgG seropositivity for EPI and potato apyrase was 97% and 17%, respectively, while the IgM was low (3%) for both antigens. The study of the conserved domains from both parasite proteins and potato apyrase could lead to the development of new drug targets or molecular markers.

Topics: Amino Acid Sequence; Animals; Antibodies, Protozoan; Apyrase; Chagas Disease; Conserved Sequence; Epitope Mapping; Humans; Leishmania braziliensis; Leishmaniasis, Cutaneous; Molecular Sequence Data; Parasites; Phylogeny; Protein Structure, Tertiary; Schistosoma mansoni; Schistosomiasis; Sequence Alignment; Solanum tuberosum