Characterization of the blastogenic response to LPS of bovine peripheral blood mononuclear cells

• Published in: PloS one 2018-10, Vol.13 (10), p.e0204827
• Main Authors: Amadori, Massimo, Soares-Filipe, Joel Fernando, Riva, Federica, Vitali, Andrea, Ruggeri, Jessica, Lacetera, Nicola
• Format: Article
• Language: English
• Subjects: Animal models; Animals; B-Lymphocytes - cytology; B-Lymphocytes - metabolism; Biology and Life Sciences; Blood; Blood cells; Bromodeoxyuridine - adverse effects; Cattle; CD4 antigen; CD4-Positive T-Lymphocytes - cytology; CD4-Positive T-Lymphocytes - metabolism; Cell cycle; Cell Cycle - drug effects; Cell proliferation; Cell Proliferation - drug effects; Concanavalin A; Concanavalin A - pharmacology; Correlation; Dairy cattle; Disease resistance; Endotoxins; Female; Flow cytometry; Gene expression; Gene Expression Profiling - veterinary; Gene Expression Regulation - drug effects; Genes; Immunocompetence; Immunological tolerance; Indoleamine-Pyrrole 2,3,-Dioxygenase - genetics; Inflammation; Kinases; Laboratories; Leukocytes (mononuclear); Leukocytes, Mononuclear - cytology; Leukocytes, Mononuclear - drug effects; Lipopolysaccharides; Lipopolysaccharides - adverse effects; Lipopolysaccharides - pharmacology; Lymphocyte transformation; Lymphocytes; Lymphocytes B; Lymphocytes T; Magnetic separation; Medicine and Health Sciences; Microorganisms; Mitogens; Peripheral blood mononuclear cells; Replication; S phase; Stimulation; TLR4 protein; Toll-Like Receptor 4 - genetics; Toll-like receptors; Tryptophan 2,3-dioxygenase; Tumor Necrosis Factor-alpha - genetics; Tumor necrosis factor-α
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0204827

Mitogens are diverse compounds of plant and microbial origin, widely employed to test immunocompetence in animals. The blastogenic response of bovine Peripheral Blood Mononuclear Cells (PBMC) to lypopolysaccharides (LPS) has been investigated in our laboratories for a long time. In particular, a possible correlation between blastogenic response to LPS and disease resistance of periparturient dairy cows had been observed in previous studies. Most important, low responder cows presented a higher frequency of disease cases after calving, compared with high responder animals. Owing to the above, different aspects of the blastogenic response to LPS were investigated on PBMC of healthy Friesian cows, using a 72-hour Bromodeoxyuridin (BrDU) cell proliferation assay. Stimulation with LPS induced little if any replication of bovine PBMC over 72 hours despite consistent BrDU detection in all the PBMC samples under study. Poor replication of LPS-stimulated PBMC was confirmed by cell cycle and cell growth flow cytometry analyses. In particular, LPS stimulation gave rise to very low percentages of S phase cells, sometimes lower than in control, unstimulated cells, as opposed to Concanavalin A-stimulated PBMC. Magnetic separation and analysis of BrDU-treated bovine PBMC after exposure to LPS showed that both B and CD4 T cells are involved in the blastogenic response to LPS, in contrast with current data based on human and murine models. Finally, LPS caused an early, specific up-regulation of TNF-α and TLR4 genes in bovine PBMC, and significant correlations were shown between the expression of inflammatory cytokine and Indoleamine-pyrrole 2,3-dioxygenase (IDO1) genes. On the whole, our data indicate that differences in the blastogenic response to LPS could be partly accounted for by heterogenicity of responding cells (B and T lymphocytes), which might also have an impact on induction and regulation of inflammatory responses and endotoxin tolerance.