Evidence for homology of buffalo and goat granular cationic peptides

Beta-defensin antibiotic peptides in the innate immunity of the buffalo: in vivo and in vitro studies

Beta-defensin antimicrobial peptides are multifunctional biomolecules, which are a major component of the oxygen-independent microbicidal system of buffalo polymorphonuclear (PMN) cells. They have great potential for use as proteomic biomarkers of host cell responses in the presence of microbial agents. On purifying these peptides by RP-HPLC, four defensin peptides were revealed. The results from testing against Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, Candida albicans, Rinderpest Virus (RPV) and Newcastle Disease Virus (NDV), showed that the peptides possessed antimicrobial and antiviral activities. Minimum inhibitory concentration (MIC) values varied according to the peptide amounts and the exposure time. Furthermore, an increase in the levels of these cationic antimicrobial peptides was apparent in milk obtained from natural cases of mastitis, as compared to the levels in normal milk. MALDI-TOF-based amino acid sequencing confirmed the expression of two beta-defensins (LAP and BNBD-2) in mastitis milk. A comparison of peptide sequences revealed that buffalo LAP and BNBD-2 share 98.6% and 100% sequence identity, respectively, with those of cattle. In vitro, Bovine Viral Diarrhoea Virus (BVDV) infection was shown to induce the expression of the beta-defensin gene, as evidenced by the PCR amplification of cDNA with specific primers. The determination of the enhanced expression of beta-defensin peptides in mastitis milk and in PMN cells, can be considered as an advanced approach to the assessment of cellular and molecular responses to cell injury. It is hoped that in vitro studies on phagocytes such as PMN cells and other cell lines, will eventually replace the use of animals in elucidating the roles of these cytokines in response to microbe-derived cell damage. It will also be possible to use defensins as biomarkers to correlate failure in host cell defence systems with peptide heterogeneity.

An evaluation of the metabolic basis of aflatoxin B1 toxicity by using buffalo granulocytes and agranulocytes in vitro

This study was aimed at monitoring cytotoxic changes in buffalo leukocyte subpopulations exposed to aflatoxin B1 (AFB1), since no such information is available for this species. The effects of AFB1 on glutathione (GSH) S-transferase, Ca2+Mg2+ATPase and protein synthesis in leukocyte subpopulations, namely, mononuclear (MN) cells and polymorphonuclear (PMN) cells isolated from the blood of the domestic buffalo (Bos bubalis), were studied. The cells were separated by using Ficoll-Paque and incubated in the presence of AFB1. GSH S-transferase activity was found to increase in cells exposed to AFB1, but there was no difference in activity between MN and PMN cells. PMN cell ATPase activity increased after AFB1 treatment, whereas no such effect was observed in the MN cells, which showed higher basal levels of ATPase activity. In the presence of AFB1, all the cells showed significant decreases in 14C-leucine incorporation, but the MN cells showed higher 14C-leucine incorporation than the PMN cells. Nevertheless, both cell types were affected by AFB1 and participated in its detoxification. There was also an appreciable decrease in the release of myeloperoxidase by activated PMN cells in the presence of AFB1.

A comparative study on certain enzymes of the granulocyte from different ruminant species

In the present study the level of enzyme hydrolases (alkaline phosphatase, myeloperoxidase, elastase, arginase, lysozyme and beta-galactosidase) of polymorphonuclear cell (PMN) granules in different ruminant species and their release in response to activation was studied. Buffalo PMN alkaline phosphatase activity was higher (P < 0.01) than in PMNs of cattle and goats. Interestingly, myeloperoxidase was higher in cattle PMNs and least in goat PMNs (P < 0.01), a similar pattern was observed in the distribution of enzyme arginase. As far as lysozyme is concerned, its activity was significantly higher (P < 0.01) in PMNs of buffaloes than in the case of cattle and goat PMNs. On activation, these cells released MPO and elastase, in all the species studied, while lysozyme was secreted only in buffalo PMN cells. Activity of certain enzymes related to oxidant defence systems such as glutathione peroxidase and glutathione reductase were higher in cattle and goats compared to that in buffaloes. These observations are likely to have bearing on immunodefense roles played by PMNs and reflected differences among the ruminant species studied.

Some biochemical responses of buffalo PMN cells to various stimuli

In view of great species differences in biology of polymorphonuclear cells, and non-availability of basic data on buffalo PMN cells for assessing their functional activity, the present work on the immuno-defence system involving protein synthesis and O2- production was undertaken to highlight the immunomodulatory role of thyroxine. Digitonin, LPS and Con-A activation generated superoxide, which was monitored by NBT reduction. The study suggested that concanvalin A (Con-A) and T4 were able to synergetically increase the production of superoxide and H2O2. The likely involvement of thyroxine in activation was studied by [125I]thyroxine incorporation, which was significantly increased due to activation. In contrast, aflatoxin B1 together with Con-A caused a significant decrease (P < 0.05) in incorporation of [125I]T4. Optimum time dependence in [14C]leucine incorporation by buffalo PMN cells was found to be 30 min and the factors like T4 (7.7 ng/ml) and glutathione (400 micrograms/ml) significantly enhanced the incorporation. In contrast, antiinflammatory agent, indomethacin (40 micrograms/ml) inhibited protein synthesis in PMN cells; while puramycin also significantly lowered the [14C]leucine incorporation. Total [14C]leucine incorporation in acid extractable cationic proteins and peptides, known for their antibacterial properties was found to be 30-40% when separated on AU-PAGE. The studies revealed the in vitro immunomodulatory role of T4 in O2-, H2O2 production and cationic protein synthesis by the activated PMN cells of buffalos.