Bovine viral diarrhea viruses modulate toll-like receptors, cytokines and co-stimulatory molecules genes expression in bovine peripheral blood monocytes.

We have used noncytopathic (ncp) and cytopathic (cp) Bovine Viral Diarrhea Viruses (BVDV) to determine the expression levels of TLR genes, type I IFN, pro-inflammatory and Th1/Th2 cytokine gene expression in bovine monocytes. In general, both BVDV strains had similar effects. However, we found some significant differences that could be due to biological differences between cp and ncp BVDV strains. TLR3 was significantly up-regulated in 1h ncp, but not in cp BVDV- infected monocytes, whereas TLR7 expression dominated in 24h infection with both BVDV strains. Type I IFN and IL-12 gene expression was also significantly up-regulated in 1h ncp, but not cp BVDV infection that correlated with the enhanced TLR3 gene expression. Both BVDV biotypes suppressed pro-inflammatory cytokines TNF-alpha, IL-1beta, and IL-6, co-stimulatory molecules CD80 and CD86, but did not change Th1 type cytokine IL-12 and INF-gamma, gene expression after 24h infection. We hypothesize that BVDV may escape immune responses by altering the expression of TLR 3 and 7 and their signaling pathways.

Differential detergent fractionation for non-electrophoretic bovine peripheral blood monocyte proteomics reveals proteins involved in professional antigen presentation.

Professional antigen presenting cells (APC), dendritic cells (DC) and their myeloid progenitors, monocytes/macrophages are critical controllers of innate and adaptive immunity. Here we show that differential detergent fractionation (DDF) analysis of bovine monocytes reveals proteins related to antigen pattern recognition, uptake and presentation to immunocompetent lymphocytes. We identify 53 bovine proteins involved in immune function of professional APC. In particular, 13 adhesion molecules, three toll-like receptors (TLR1, 6 and 8), three antigen uptake-related proteins (including mannose receptor [MR] precursor), and eight actin-like proteins involved in active endocytosis were identified. In addition, MHC class I and II-related proteins, cytokines, active substances and growth factors have been identified. We conclude that the DDF approach can provide interpretable and meaningful functional information concerning protein expression profiles associated with monocyte activation, transformation into macrophages and/or immature DC, and maturation of monocyte-derived DC in the presence of multiple bovine pathogens.

Bovine monocytes induce immunoglobulin production in peripheral blood B lymphocytes.

Although a role for monocytes and monocyte-derived dendritic cells (DC) in the activation of T cells is well established, it is less clear to what extent DC and their precursors, monocytes, regulate B cell immune responses. Here we show that regulatory mechanisms similar to those in humans are in place in the bovine immune system. In vitro culture of bovine monocytes with bovine B cells activated by the anti-CD3 triggered CD4+ T cells or through immunoglobulin (Ig) receptor crosslinking induces B cell Ig secretion. Unlike bovine monocyte-derived DC, monocytes do not promote Ig class switching to IgG and IgA in activated peripheral blood B cells. These results suggest that bovine monocytes are capable of directly inducing Ig secretion in activated bovine peripheral blood B cells, but do not provide the signals for B cell Ig class switching.

Bovine dendritic cells generated from monocytes and bone marrow progenitors regulate immunoglobulin production in peripheral blood B cells.

We examined whether bovine monocyte-derived and bone marrow (BM) dendritic cells (DCs) regulate antibody production in activated peripheral blood B cells. DCs were generated from monocytes and BM progenitors in the presence of bovine recombinant granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4). Monocyte-derived DCs promoted B cells activated by the anti-CD3 triggered CD4(+) T cells or through immunoglobulin M (IgM) receptor to increase the level of IgG secretion. Furthermore, the addition of DCs triggered B cells activated through IgM receptors to produce IgG2 and IgA, thus inducing an isotype switch. BM-derived DCs increased the production of IgG in B cells activated by the anti-CD3 triggered CD4(+) T cells, but unlike monocyte-derived DCs did not have any effect on B cells activated through surface IgM. These data suggest that the regulation of humoral immune responses in cattle depends on the origin of DCs and the mode of B cell activation.