Acquired protective immune response in a fish-myxozoan model encompasses specific antibodies and inflammation resolution

• Published in: Fish & shellfish immunology Vol. 90; pp. 349 - 362
• Main Authors: Picard-Sánchez, Amparo, Estensoro, Itziar, del Pozo, Raquel, Piazzon, M. Carla, Palenzuela, Oswaldo, Sitjà-Bobadilla, Ariadna
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2019
• Subjects: Acquired immune response; Enteromyxum leei; Fish IgM; Gene expression; Parasite resistance; Sparus aurata; Fish IgM; HK; Parasite resistance; AI; Gene expression; SUR; Sparus aurata; GSB; NAI; Enteromyxum leei; dpe; PI; Acquired immune response; PO; gilthead sea bream; anterior intestine; days post-exposure; head kidney; naïve fish never exposed before to E. leei; fish that survived and cleared an established E. leei infection; peroxidases; posterior intestine
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2019.04.300

The myxozoan parasite Enteromyxum leei causes chronic enteritis in gilthead sea bream (GSB, Sparus aurata) leading to intestinal dysfunction. Two trials were performed in which GSB that had survived a previous infection with E. leei (SUR), and naïve GSB (NAI), were exposed to water effluent containing parasite stages. Humoral factors (total IgM and IgT, specific anti-E. leei IgM, total serum peroxidases), histopathology and gene expression were analysed. Results showed that SUR maintained high levels of specific anti-E. leei IgM (up to 16 months), expressed high levels of immunoglobulins at the intestinal mucosa, particularly the soluble forms, and were resistant to re-infection. Their acquired-type response was complemented by other immune effectors locally and systemically, like cell cytotoxicity (high granzyme A expression), complement activity (high c3 and fucolectin expression), and serum peroxidases. In contrast to NAI, SUR displayed a post-inflammatory phenotype in the intestine and head kidney, characteristic of inflammation resolution (low il1β, high il10 and low hsp90α expression). [Display omitted] •Resistance to E. leei in re-exposed fish lasts up to 16 months.•Specific antibodies (IgM) have a protective role for re-exposed fish at early times.•Re-exposed fish show inflammatory resolution phenotype in intestine and head kidney.•Cell cytotoxicity, peroxidases, and complement contribute to acquired resistance.