Full length article Impact of date palm fruits extracts and probiotic enriched diet on antioxidant status, innate immune response and immune-related gene expression of European seabass (Dicentrarchus labrax) F.A. Guardiola a, 1 , C. Porcino b, 1 , R. Cerezuela a , A. Cuesta a , C. Faggio b , M.A. Esteban a, * a Fish Innate Immune System Group, Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional “Campus Mare Nostrum”, University of Murcia, 30100, Murcia, Spain b Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, Viale F. Stagnod'Alcontres, 31, 98166, Messina, Italy article info Article history: Received 26 January 2016 Received in revised form 15 March 2016 Accepted 22 March 2016 Available online 24 March 2016 Keywords: Date palm fruit extracts Probiotics Immunostimulants Antioxidant status Innate immunity European sea bass (Dicentrarchus labrax) Teleosts abstract The application of additives in the diet as plants or extracts of plants as natural and innocuous com- pounds has potential in aquaculture as an alternative to antibiotics and immunoprophylactics. The aim of the current study was to evaluate the potential effects of dietary supplementation of date palm fruit extracts alone or in combination with Pdp11 probiotic on serum antioxidant status, on the humoral and cellular innate immune status, as well as, on the expression levels of some immune-related genes in head-kidney and gut of European sea bass (Dicentrarchus labrax) after 2 and 4 weeks of administration. This study showed for the first time in European sea bass an immunostimulation in several of the pa- rameters evaluated in fish fed with date palm fruits extracts enriched diet or fed with this substance in combination with Pdp 11 probiotic, mainly after 4 weeks of treatment. In the same way, dietary sup- plementation of mixture diet has positive effects on the expression levels of immune-related genes, chiefly in head-kidney of Dicentrarchus labrax. Therefore, the combination of both could be considered of great interest as potential additives for farmed fish. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The contribution of aquaculture to world food production has increased significantly over the last few decades and this sector now supplies nearly half of the total fish and shellfish used for human consumption [1]. This industry remains as an important food producing sector in the world [2], nonetheless is challenged by several daunting issues on sustainability from biological, environ- mental and socio-economic points of view [3]. The downside of intensification of the farming operations have been economic los- ses because of the mortality, since these conditions can lead the animals to be susceptible to infections and stressors [4]. In aqua- culture, one of the most promising methods of controlling diseases and stressors impact is by enhancing the defense mechanism of fish through prophylactic administration of immunostimulants [5], which are considered as a hopeful alternative to chemotherapy and vaccines [6]. All these preventive measures are aimed at enhancing the innate and/or the adaptive immune system [7], as well as, protect animals from free radicals and the effects of ROS. The use of immunostimulants is an effective means of increasing the immuno competency and disease resistance of fish [8]. Their most proved effect is to facilitate the function of phagocytic cells and increase their bactericidal and fungicidal activities, as well as, to play an important role as natural antioxidants [see Refs. [9e12] for review]. From these reviews could be extracted than a wide variety of plant extracts have been studied as dietary additives in different fish species of interest in aquaculture, with the endeavor of fighting fish diseases, due to the fact that they have varied beneficial effects on the host, like stimulation of immunity, among others. Plant extracts have been reported as anti-stressors, growth promoters, appetite stimulators, enhancement of tonicity and immunostimulation, maturation of culture species and anti- pathogen properties in aquaculture fish due to active principles (e.g. alkaloids, terpenoids, tannins, saponins, etc.) [13,14]. Further- more, plant extracts can be considered as an alternative to other * Corresponding author. E-mail address: aesteban@um.es (M.A. Esteban). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Fish & Shellfish Immunology journal homepage: www.elsevier.com/locate/fsi http://dx.doi.org/10.1016/j.fsi.2016.03.152 1050-4648/© 2016 Elsevier Ltd. All rights reserved. Fish & Shellfish Immunology 52 (2016) 298e308