Dietary tryptophan deficiency and its supplementation compromises inflammatory mechanisms and disease resistance in a teleost fish

Abstract

Tryptophan participates on several physiological mechanisms of the neuroendocrine-immune network and plays a critical role in macrophages and lymphocytes function. This study intended to evaluate the modulatory effects of dietary tryptophan on the European seabass ( Dicentrarchus labrax ) immune status, inflammatory response and disease resistance to Photobacterium damselae piscicida . A tryptophan deficient diet (NTRP); a control diet (CTRL); and two other diets supplemented with tryptophan at 0.13% (TRP13) and 0.17% (TRP17) of feed weight were formulated. Fish were sampled at 2 and 4 weeks of feeding and the remaining were i.p. injected with Phdp (3 × 10 6 cfu/fish) at 4 weeks and the inflammatory response (at 4, 24, 48 and 72 hours post-infection) as well as survival were evaluated. Results suggest that fish immune status was not altered in a tryptophan deficient scenario whereas in response to an inflammatory insult, plasma cortisol levels increased and the immune cell response was compromised, which translated in a lower disease resistance. When dietary tryptophan was offered 30% above its requirement level, plasma cortisol increased and, in response to bacterial infection, a decrease in lymphocytes, monocytes/macrophages and several immune-related genes was observed, also compromising at some degree fish disease resistance.

Effects of dietary tryptophan levels and fish stocking density on immunological and antioxidant responses and bactericidal activity againstAeromonas hydrophilain rainbow trout (Oncorhynchus mykiss)

“…The present results suggest 10 g Trp per kg diet was surplus causing health deterioration and immunosuppression in the fish. These results are in line with Machado et al () showing that surplus dietary Trp significantly compromised immune responses in fish.…”

Methionine and Tryptophan Play Different Modulatory Roles in the European Seabass (Dicentrarchus labrax) Innate Immune Response and Apoptosis Signaling—An In Vitro Study

“…First-strand cDNA was synthesized with NZY First-Strand cDNA Synthesis Kit (NZYTech). Quantitative PCR assays and primer design ( Table 1) were performed as described by Machado et al (24). The expression of the target gene was normalized using the average The efficiency of PCR reactions was calculated from serial dilutions of tissue RT reactions in the validation procedure.…”

“…Studies in fish showed that increasing dietary tryptophan levels did not significantly modulate European seabass (11) and Persian sturgeon (Acipenser persicus) (23) basal innate immunerelated mechanisms activity, while a clear effect of tryptophan surplus was observed upon inflammation induction. For instance, in European seabass Azeredo et al (12) observed an inhibitory action of tryptophan on HK inflammatory transcripts while Machado et al (24) reported a compromised immune response and disease resistance to Phdp. In macrophages, tryptophan catabolism occurs through the kynurenine-niacin pathway, mediated by indoleamine 2, 3-dioxygenase (IDO) (25).…”

Metabolic Regulation of Immune Responses to Mycobacterium tuberculosis: A Spotlight on L-Arginine and L-Tryptophan Metabolism

“…L-TRP supplementation has been investigated in other infection models. In teleost fish, L-TRP supplementation increased plasma cortisol levels, which decreased circulating leukocytes following Photobacterium infection ( 238 ). However, infected fish receiving excess dietary L-TRP displayed increased survival ( 238 ).…”

“…In teleost fish, L-TRP supplementation increased plasma cortisol levels, which decreased circulating leukocytes following Photobacterium infection ( 238 ). However, infected fish receiving excess dietary L-TRP displayed increased survival ( 238 ). In a pig model of rotavirus infection, L-TRP supplementation expanded the Foxp3 + T reg population ( 239 ).…”