ARS | Publication request: First identification of regulatory B cell subsets expressing IL-10 in teleost fish

Submitted to: Congress International Society Develop Comparative Immunology
Publication Type: Abstract Only
Publication Acceptance Date: June 14, 2012
Publication Date: July 15, 2012
Citation: Takizawa, F., Gomez, D., Xu, Z., Parra, D., Bjork, S., Zhang, Y., Bartholomew, J., Wiens, G.D., Sunyer, J. 2012. First identification of regulatory B cell subsets expressing IL-10 in teleost fish. Congress International Society Develop Comparative Immunology. 367.

Technical Abstract: IL-10 is an immunoregulatory cytokine with a potent anti-inflammatory activity, thus inhibiting the production of proinflammatory cytokines as well as processes of antigen presentation. IL-10 is produced by variety of cells, including antigen presentation cells (i.e., monocytes, macrophages and dendritic cells) and T cells (Th2 and regulatory T cells). Notably, mammalian B cells producing IL-10, referred to as regulatory B (Breg) cells, have recently attracted considerable attention due to their immunosuppressive roles in autoimmunity, inflammation and tumorigenesis. In teleost, IL-10 has been identified in some fish species including Cyprinidae and Salmonidae. Interestingly, goldfish IL-10 was revealed to possess the inhibiting bioactivity of inflammatory responses in vitro. However, the cell types producing transcripts and proteins of IL-10 are largely unknown in teleost. Here, to determine whether teleost have B cell subset homologous to mammalian Breg cells, we sorted IgM+ and IgT+ B cells from rainbow trout infected with Yersinia ruckeri or Ceratomyxa shasta and analyzed the transcription levels of IL-10 in these B cell subpopulations. Moreover, we developed rabbit antibodies against recombinantly produced rainbow trout IL-10 to detect the presence of Il-10-producing B cells in lymphoid tissues. In Y. ruckeri infected fish, only spleen IgT+ B cells induced statistically significant higher IL-10 transcripts when compared to spleen IgT+ B cells of control fish. Moreover, IgT+ B cells represented the spleen leukocyte population expressing the highest Il-10 transcript levels. Interestingly, C. Shasta-infected fish showed an increase in IL-10 transcripts for both gut IgM+ and IgT+ B cell subsets when compared to control fish. The presence of Il-10 positive cells could be identified by immunohistochemistry in the gut of C. Shasta-infected fish. Whether these Il-10 positive cells represent B lymphocytes is currently under investigation. These results imply for the first time the existence of Il-10 producing B cells in a non-mammalian species, and establish the basis for studying the role and evolution of regulatory B cells using teleosts as model species.