Teleost intestinal immunology
Author(s)
Rombout, Jan H.W.M.
Abelli, Luigi
Picchietti, Simona
Scapigliati, Giuseppe
Kiron, Viswanath
Date Issued
2010
Type
Article
Abstract
Teleosts clearly have a more diffuse gut associated lymphoid system, which is morphological and
functional clearly different from the mammalian GALT. All immune cells necessary for a local immune
response are abundantly present in the gut mucosa of the species studied and local immune responses
can be monitored after intestinal immunization. Fish do not produce IgA, but a special mucosal IgM
isotype seems to be secreted and may (partly) be the recently described IgZ/IgT. Fish produce a pIgR in
their mucosal tissues but it is smaller (2 ILD) than the 4e5 ILD pIgR of higher vertebrates. Whether
teleost pIgR is transcytosed and cleaved off in the same way needs further investigation, especially
because a secretory component (SC) is only reported in one species. Teleosts also have high numbers of
IEL, most of them are CD3-3
þ/CD8-a
þ and have cytotoxic and/or regulatory function. Possibly many of
these cells are TCRgd cells and they may be involved in the oral tolerance induction observed in fish.
Innate immune cells can be observed in the teleost gut from first feeding onwards, but B cells appear
much later in mucosal compartments compared to systemic sites. Conspicuous is the very early presence
of putative T cells or their precursors in the fish gut, which together with the rag-1 expression of
intestinal lymphoid cells may be an indication for an extra-thymic development of certain T cells.
Teleosts can develop enteritis in their antigen transporting second gut segment and epithelial cells, IEL
and eosinophils/basophils seem to play a crucial role in this intestinal inflammation model. Teleost
intestine can be exploited for oral vaccination strategies and probiotic immune stimulation. A variety of
encapsulation methods, to protect vaccines against degradation in the foregut, are reported with
promising results but in most cases they appear not to be cost effective yet. Microbiota in fish are clearly
different from terrestrial animals. In the past decade a fast increasing number of papers is dedicated to
the oral administration of a variety of probiotics that can have a strong health beneficial effect, but much
more attention has to be paid to the immune mechanisms behind these effects. The recent development
of gnotobiotic fish models may be very helpful to study the immune effects of microbiota and probiotics
in teleosts.
Additional information
L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.com/
Citation
Rombout, J.H.W.M. et al. 2010. Teleost intestinal immunology. "Fish and Shellfish Immunology", in press.
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