Blockade of bovine PD-1 increases T cell function and inhibits bovine leukemia virus expression in B cells in vitro

Abstract

Programmed death-1 (PD-1) is a known immunoinhibitory receptor that contributes to immune evasion of various tumor cells and pathogens causing chronic infection, such as bovine leukemia virus (BLV) infection. First, in this study, to establish a method for the expression and functional analysis of bovine PD-1, hybridomas producing monoclonal antibodies (mAb) specific for bovine PD-1 were established. Treatment with these anti-PD-1 mAb enhanced interferon-gamma (IFN-γ) production of bovine peripheral blood mononuclear cells (PBMC). Next, to examine whether PD-1 blockade by anti-PD-1 mAb could upregulate the immune reaction during chronic infection, the expression and functional analysis of PD-1 in PBMC isolated from BLV-infected cattle with or without lymphoma were performed using anti-PD-1 mAb. The frequencies of both PD-1+ CD4+ T cells in blood and lymph node and PD-1+ CD8+ T cells in lymph node were higher in BLV-infected cattle with lymphoma than those without lymphoma or control uninfected cattle. PD-1 blockade enhanced IFN-γ production and proliferation and reduced BLV-gp51 expression and B-cell activation in PBMC from BLV-infected cattle in response to BLV-gp51 peptide mixture. These data show that anti-bovine PD-1 mAb could provide a new therapy to control BLV infection via upregulation of immune response.

Bovine leukemia virus reduces anti‐viral cytokine activities and NK cytotoxicity by inducing TGF‐β secretion from regulatory T cells

“…In further experiments, anti‐virus cytokine production was reduced as was shown in our previous reports 23, 24, 28. Moreover, CD4 + CD25 high Foxp3 + T cell numbers were increased in conjunction with increasing proportions of TGF‐β‐secreting CD4 + CD25 high Foxp3 + T cells, leading to correlations with increased proviral loads in BLV‐infected cattle, as shown previously 25, 26.…”

“…Moreover, cell‐mediated immune dysfunction accelerates disease progression during BLV‐infection as indicated in previous studies showing that IFN‐γ plays important roles in protective mechanisms against BLV propagation in infected animals 23, 24, 28. In addition, the ensuing immune disorder may contribute to the development of opportunistic infections in BLV‐infected cattle 31, 32.…”

Bovine Immunoinhibitory Receptors Contribute to Suppression of Mycobacterium avium subsp. paratuberculosis-Specific T-Cell Responses

“…PBMCs, splenocytes, and lymphocytes were isolated from tissues and incubated in PBS containing 10% goat serum (Sigma-Aldrich) at room temperature for 15 min to prevent nonspecific reactions. Cells were then washed and stained with MAbs against PD-1:5D2 (rat IgG2a [13]) or LAG-3:71-2D8 (rat IgG1; the present study) for 30 min at room temperature. After being washed with PBS containing 10% goat serum, the cells were stained with CD4-FITC: CC8 (AbD Serotec, Oxford, United Kingdom), CD8-PerCp/Cy5.5:CC63 (AbD Serotec), IgM-PE/Cy7:IL-A30 (AbD Serotec), CD3:MM1A (VMRD, Pullman, WA) prelabeled with a Zenon R-PE mouse IgG1 labeling kit (Life Technologies, Carlsbad, CA), and allophycocyanin (APC)-conjugated anti-rat immunoglobulin (Beckman Coulter, Fullerton, CA) antibody conjugates for 30 min at room temperature.…”

“…Our previous studies revealed that the upregulation of bovine PD-1 and LAG-3 in T cells was closely associated with disease progression in cattle infected with bovine leukemia virus (BLV) (13)(14)(15). Moreover, blockade of these inhibitory pathways restores exhausted T-cell function and induces antiviral responses in vitro (13,15,16).…”

“…Moreover, blockade of these inhibitory pathways restores exhausted T-cell function and induces antiviral responses in vitro (13,15,16). However, it remains unclear whether PD-1 and LAG-3 pathways are involved in the development of T-cell exhaustion in other chronic infections of cattle.…”