T helper 17-associated cytokines are produced during antigen-specific inflammation in the mammary gland

PLoS One. 2013 May 16;8(5):e63471. doi: 10.1371/journal.pone.0063471. Print 2013.

Abstract

Infectious mastitis cuts down milk production profitability and is a major animal welfare problem. Bacteria-induced inflammation in the mammary gland (MG) is driven by innate immunity, but adaptive immunity can modulate the innate response. Several studies have shown that it is possible to elicit inflammation in the MG by sensitization to an antigen subsequently infused into the lumen of the gland. The objective of our study was to characterize the inflammation triggered in the MG of cows sensitized to ovalbumin, by identifying the cytokines and chemokines likely to play a part in the reaction. Among immunized cows, responders mobilized locally high numbers of leukocytes. An overexpression of the genes encoding IL-17a, IL-17F, IL-21, IL-22 and INF-γ was found in milk cell RNA extracts in the early phase of the inflammatory response. At the protein level, IL-17A was detected in milk as soon as the first sampling time (8 h post-challenge), and both IL-17A and IFN-γ concentrations peaked at 12 to 24 h post-challenge. In mammary tissue from challenged quarters, overexpression of the genes encoding IL-17A, IL-17F, IL-21, IL-22, IL-26 and IFN-γ was observed. Neutrophil-attracting chemokines (CXCL3 and CXCL8) were found in milk, and overexpressed transcripts of chemokines attracting lymphocytes and other mononuclear leukocytes (CXCL10, CCL2, CCL5, CCL20) were detected in mammary tissue. Expression of IL-17A, as revealed by immunohistochemistry, was located in epithelial cells, in leukocytes in the connective tissue and in association with the epithelium, and in migrated alveolar leukocytes of challenged quarters. Altogether, these results show that antigen-specific inflammation in the MG was characterized by the production of IL-17 and IFN-γ. The orientation of the inflammatory response induced by the antigen-specific response has the potential to strongly impact the outcome of bacterial infections of the MG.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Female
  • Humans
  • Immunohistochemistry
  • Inflammation / metabolism*
  • Interferon-gamma / metabolism
  • Interleukin-17 / metabolism
  • Interleukin-22
  • Interleukins / metabolism
  • Mammary Glands, Animal / drug effects
  • Mammary Glands, Animal / immunology*
  • Mammary Glands, Animal / metabolism*
  • Mammary Glands, Human
  • Milk / metabolism
  • Ovalbumin / toxicity

Substances

  • Interleukin-17
  • Interleukins
  • Interferon-gamma
  • Ovalbumin
  • interleukin-21

Grants and funding

This work was funded in part by Pfizer Animal Health. Pfizer’s contribution to the experimental costs came as a supplement to the authors’ Institute (INRA - Institut Scientifique de Recherche Agronomique) funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.