Identification of CD8α+ dendritic cells in rainbow trout (Oncorhynchus mykiss) intestine

Abstract

Dendritic cells (DCs) are professional antigen presenting cells located at mucosal surfaces and lymphoid tissues. Their main role is to present antigens to T cells and thus regulate the initiation of the acquired immune response and modulate tolerance mechanisms towards self-antigens. Despite their relevance, not many studies have addressed the identification and characterization of specific DC subsets in teleost fish. Previous studies in our group identified a DC subpopulation co-expressing CD8α and major histocompatibility complex II (MHC II) on the cell surface in rainbow trout ( Oncorhynchus mykiss ) skin and gills. A complete functional and phenotypical characterization of these cell subsets was then undertaken, unequivocally recognizing them as DCs (CD8 + DCs). In the current study, we report the identification of a homologous population in rainbow trout intestinal lamina propria (LP). We have studied the main features of these intestinal CD8 + DCs, comparing them to those of CD8 + DCs from another mucosal tissue (gills). Interestingly, intestinal CD8 + DCs exhibited significant phenotypical and functional differences when compared to gill CD8 + DCs, suggesting that the location of DCs strongly conditions their activation state. These results will contribute to further expand our knowledge on how intestinal immune responses are regulated in fish, helping us to rationally design oral vaccines in the future.

Review on Immersion Vaccines for Fish: An Update 2019

“…Immune cells are present in all mucosal tissues/linings (MALT), from nasopharynx-associated lymphoid tissue (NALT), gill-associated lymphoid tissue (GIALT), skin-associated lymphoid tissue (SALT), buccal cavity-associated lymphoid tissue, and gut-associated lymphoid tissue (GALT). These tissues contain characteristics important to the adaptive immune system [28][29][30][31][32][33]. The mucosal integument and soft tissues also contain innate defense molecules which may be fully protective against early stage infection [34].…”

Mucosal delivery of fish vaccines: Local and systemic immunity following mucosal immunisations

“…Antigen-sampling cells sharing some morphological similarities with mammalian M cells and macrophage-like cells have been identified in salmon intestine [23], [24], [25]. In addition to the gills and skin, CD8 + DCs are present within rainbow trout intestinal lamina propria, where they exhibit significant phenotypical and functional differences from gill CD8 + DCs [26].…”

“…2). Teleost DCs have already been found in the intestine, gills and skin where they exhibit varying phenotypic and functional characteristics, suggesting the existence of distinct DC subsets in the mucosal tissues [97], [98], [99]. Understanding mucosal DC functions may shed light upon the development of effective vaccines against both viral and intracellular bacterial infections.…”

Teleost IgD+IgM− B Cells Mount Clonally Expanded and Mildly Mutated Intestinal IgD Responses in the Absence of Lymphoid Follicles

“…Spleen, gill and kidney cell suspensions were obtained by passing the tissues through a 100 mm nylon mesh (BD Biosciences) using Leibovitz's medium (L-15, GIBCO) containing 100 I.U./ml penicillin, 100 mg/ml streptomycin (P/S, Life Technologies), 10 U/ml heparin (Sigma-Aldrich) and 5% fetal calf serum (FCS, GIBCO). Skin and gut leukocytes were isolated following an enzymatic digestion of the tissues as previously described (Granja et al, 2015;Soleto et al, 2019). For all tissues, cell suspensions were placed onto 30/51% Percoll discontinuous density gradients and centrifuged at 500 x g for 30 min at 4 C. Blood was diluted 10 times with L-15 medium containing antibiotics, 10 U/ml heparin and 5% FCS.…”