Tumor necrosis factor-α-induced inflammatory responses in cattle

Tumor necrosis factor-alpha (TNF-α) is recognized as a cytokine because of its involvement in inflammation-mediated biological defense functions. Although TNF-α is primarily produced by macrophages, it is also produced by other cells, including lymphocytes, Kupffer cells, natural killer cells and adipocytes. While TNF-α has diverse immune system functions, including antitumor activity, antimicrobial activity and mediation of inflammation, it also regulates a number of physiological functions, including appetite, fever, energy metabolism and endocrine activity. Factors such as viruses, parasites, other cytokines, and endotoxins induce TNF-α production. In combination with other cytokines, TNF-α plays a clinically important role in cattle by mediating immune inflammatory responses such as mastitis and endotoxic shock. It has been reported that cytokines such as TNF-α are involved in metabolic disease such as acidosis. On the other hand, several data suggest that lactoferrin (LF) acts to prevent the release of a number of inflammatory mediators from various activated cells, and further suggest that the prophylactic effect of LF involves inhibition of cytokine production, including TNF-α, that are principal mediators of the inflammatory response leading to death from toxic shock. This review discusses the role of TNF-α in pathological conditions in cattle, including infections and metabolic diseases caused by perturbation of metabolism and endocrine functions.