Colostrum proinflammatory cytokines as biomarkers of bovine immune response to bovine tuberculosis (bTB).

Bovine colostrum contains compounds, which provide passive immune protection from mother to newborn calves. Little is known about cytokine levels and their role in bovine colostrum. Moreover, the capacity of bovine colostrum cells to mount specific immune responses after natural exposure to bovine tuberculosis (bTB) antigens in dairy herds has not been studied, thus far. The purpose of this study was to identify biomarkers for bTB infection measurable in bovine colostrum. The present study reveals that isolated-immune colostrum cells can mount a specific immune response against bTB antigens, by measuring the novo IFN-γ release in cell culture. We found that IFN-γ levels in the responders (Bov+) to bTB antigen were higher than in non-responders (Bov-). On the other hand, proinflammatory cytokines contained in colostrum's whey were tested in Tuberculin Skin Test (TST) reactor (TST+) and non-reactor (TST-) animals to assess their potential role as biomarker. We observed that IFN-γ levels were lower or undetectable, as opposed to IL4 levels were measurable, the TNF-α level was higher in TST- than TST+, while IL-6 levels showed the opposite reaction and with no statistical significance. Moreover, IL-1α mRNA expression levels were higher in colostrum mononuclear cells (CMC) in Bov+ cattle. Collectively, these data suggest that the differential expression of pro and anti-inflammatory cytokines could have relevant value to diagnose bTB in cattle.

Preexisting Heterogeneity of Inducible Nitric Oxide Synthase Expression Drives Differential Growth of Mycobacterium tuberculosis in Macrophages.

Mycobacterium tuberculosis infection is initiated by the inhalation and implantation of bacteria in the lung alveoli, where they are phagocytosed by macrophages. Even a single bacterium may be sufficient to initiate infection. Thereafter, the clinical outcome is highly variable between individuals, ranging from sterilization to active disease, for reasons that are not well understood. Here, we show that the rate of intracellular bacterial growth varies markedly between individual macrophages, and this heterogeneity is driven by cell-to-cell variation of inducible nitric oxide synthase (iNOS) activity. At the single-cell level, iNOS expression fluctuates over time, independent of infection or activation with gamma interferon. We conclude that chance encounters between individual bacteria and host cells randomly expressing different levels of an antibacterial gene can determine the outcome of single-cell infections, which may explain why some exposed individuals clear the bacteria while others develop progressive disease. IMPORTANCE In this report, we demonstrate that fluctuations in the expression of antimicrobial genes can define how single host cells control bacterial infections. We show that preexisting cell-to-cell variation in the expression of a single gene, that for inducible nitric oxide synthase, is sufficient to explain why some macrophages kill intracellular M. tuberculosis while others fail to control bacterial replication, possibly leading to disease progression. We introduce the concept that chance encounters between heterogeneous bacteria and host cells can determine the outcome of a host-pathogen interaction. This concept is particularly relevant for all the infectious diseases in which the number of interacting pathogens and host cells is small at some point during the infection.

Evaluation of tumor necrosis factor-alpha (TNF-α); gamma interferon (IFN-γ) genes and oxidative stress in sheep: immunological responses induced by Oestrus ovis (Diptera: Oestridae) infestation.

This study aimed to evaluate the cell mediated immune responses against Oestrus ovis (O. ovis) in sheep through measurement of the changes in mRNA expression of the tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) cytokines using quantitative Real time-PCR (qRt-PCR). Also; to detect the role of Oestrus ovis infestation in the oxidative stress markers in sheep. Fifty sheep head were examined in Cairo abattoir from the period of May to August 2019. Sera were separated and collected for measurement of nitric oxide, zinc and malondialdehyde (MDA). While TNF-α and IFN-γ mRNA were extracted from nasal mucosa. Levels of IFN-γ and TNF-α were significantly higher in infested sheep than that in non-infested one. Also, oxidative stresses were indicated by high level of nitric oxide as one of reactive oxygen species (ROS) and serum MDA as oxidative stress marker and low antioxidant capacity (zinc concentration in serum) in infested sheep. The obtained results indicated that measurements of TNF-α and IFN-γ cytokines using qRT-PCR could be used as an association and reproducible quantitative method for the diagnosis of O. ovis infestation in sheep.

Fas/FasL and perforin-granzyme pathways mediated T cell cytotoxic responses in infectious bursal disease virus infected chickens.

Infectious bursal disease (IBD) is a highly contagious disease of chickens which leads to immunosuppression. In our previous study it was demonstrated that, possibly, CD4(+) and CD8(+) T cells may employ perforin and granzyme-A pathway for the clearance of IBDV-infected bursal cells. In this study, we evaluated the cytotoxic T cell responses involving two independently functioning but complementary mechanisms: Fas-Fas ligand and perforin-granzyme pathways in IBDV-infected chickens. As demonstrated previously, infection of chickens with IBDV was accompanied by influx of CD8(+) T cells in the bursa and spleen. There was an upregulation in the gene expression of cytolytic molecules: Fas and Fas ligand (FasL), perforin (PFN) and granzyme-A (Gzm-A) in bursal and in the splenic tissues of IBDV inoculated chickens. Additionally, for the first time, we detected Fas, Fas ligand, Caspase-3 and PFN producing CD8(+) T cells in the bursa and spleen of IBDV-infected chickens. The infiltration and activation of CD8(+) T cells was substantiated by the detection of Th1 cytokine, IFN-γ. These data suggest that T cells may be involved in the clearance of virus from the target organ bursa and peripheral tissues such as spleen. The findings of these studies provide new insights into the pathogenesis of IBD and provide mechanistic evidence that the cytotoxic T cells may act through both Fas-FasL and perforin-granzyme pathways in mediating the clearance of virus-infected cells.