Frontiers in Veterinary Science (Dec 2020)

The Suppression of Th1 Response by Inducing TGF-β1 From Regulatory T Cells in Bovine Mycoplasmosis

  • Yamato Sajiki,
  • Satoru Konnai,
  • Satoru Konnai,
  • Shinya Goto,
  • Tomohiro Okagawa,
  • Kosuke Ohira,
  • Honami Shimakura,
  • Naoya Maekawa,
  • Satoshi Gondaira,
  • Hidetoshi Higuchi,
  • Motoshi Tajima,
  • Yuki Hirano,
  • Junko Kohara,
  • Shiro Murata,
  • Shiro Murata,
  • Kazuhiko Ohashi,
  • Kazuhiko Ohashi

DOI
https://doi.org/10.3389/fvets.2020.609443
Journal volume & issue
Vol. 7

Abstract

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Regulatory T cells (Tregs) regulate immune responses and maintain host immune homeostasis. Tregs contribute to the disease progression of several chronic infections by oversuppressing immune responses via the secretion of immunosuppressive cytokines, such as transforming growth factor (TGF)-β and interleukin-10. In the present study, we examined the association of Tregs with Mycoplasma bovis infection, in which immunosuppression is frequently observed. Compared with uninfected cattle, the percentage of Tregs, CD4+CD25highFoxp3+ T cells, was increased in M. bovis-infected cattle. Additionally, the plasma of M. bovis-infected cattle contained the high concentrations of TGF-β1, and M. bovis infection induced TGF-β1 production from bovine immune cells in in vitro cultures. Finally, we analyzed the immunosuppressive effects of TGF-β1 on bovine immune cells. Treatment with TGF-β1 significantly decreased the expression of CD69, an activation marker, in T cells, and Th1 cytokine production in vitro. These results suggest that the increase in Tregs and TGF-β1 secretion could be one of the immunosuppressive mechanisms and that lead to increased susceptibility to other infections in terms of exacerbation of disease during M. bovis infection.

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