Dietary supply with polyunsaturated fatty acids and resulting maternal effects influence host -- parasite interactions

Interactions between hosts and parasites can be substantially modulated by host nutrition. Polyunsaturated fatty acids (PUFAs) are essential dietary nutrients; they are indispensable as structural components of cell membranes and as precursors for eicosanoids, signalling molecules which act on reproduction and immunity. Here, we explored the potential of dietary PUFAs to affect the course of parasitic infections using a well-established invertebrate host -- parasite system, the freshwater herbivore Daphnia magna and its bacterial parasite Pasteuria ramosa.; Using natural food sources differing in their PUFA composition and by experimentally modifying the availability of dietary arachidonic acid (ARA) and eicosapentaenoic acid (EPA) we examined PUFA-mediated effects resulting from direct consumption as well as maternal effects on offspring of treated mothers. We found that both host and parasite were affected by food quality. Feeding on C20 PUFA-containing food sources resulted in higher offspring production of hosts and these effects were conveyed to a great extent to the next generation. While feeding on a diet containing high PUFA concentrations significantly reduced the likelihood of becoming infected, the infection success in the next generation increased whenever the maternal diet contained PUFAs. We suggest that this opposing effect was caused by a trade-off between reproduction and immunity in the second generation.; Considering the direct and maternal effects of dietary PUFAs on host and parasite we propose that host -- parasite interactions and thus disease dynamics under natural conditions are subject to the availability of dietary PUFAs

Are Raw Brassica Vegetables Healthier Than Cooked Ones? A Randomized, Controlled Crossover Intervention Trial on the Health-Promoting Potential of Ethiopian Kale

The present human intervention trial investigated the health-promoting potential of B. carinata, with a focus on effects of thermal processing on bioactivity. Twenty-two healthy subjects consumed a B. carinata preparation from raw (allyl isothiocyanate-containing) or cooked (no allyl isothiocyanate) leaves for five days in a randomized crossover design. Peripheral blood mononuclear cells were exposed to aflatoxin B1 (AFB1), with or without metabolic activation using human S9 mix, and subsequently analyzed for DNA damage using the comet assay. Plasma was analyzed for total antioxidant capacity and prostaglandin E2 (PGE2) levels. Cooked B. carinata significantly reduced DNA damage induced by AFB1 as compared to baseline levels (+S9 mix: 35%, −S9 mix: 33%, p ≤ 0.01, respectively). Raw B. carinata only reduced DNA damage by S9-activated AFB1 by 21% (p = 0.08). PGE2 plasma levels were significantly reduced in subjects after consuming raw B. carinata. No changes in plasma antioxidant capacity were detectable. A balanced diet, including raw and cooked Brassica vegetables, might be suited to fully exploit the health-promoting potential. These results also advocate the promotion of B. carinata cultivation in Eastern Africa as a measure to combat effects of unavoidable aflatoxin exposure

The potential of dietary polyunsaturated fatty acids to modulate eicosanoid synthesis and reproduction in Daphnia magna : A gene expression approach

Nutritional ecology of the aquatic model genus Daphnia has received much attention in past years in particular with regard to dietary polyunsaturated fatty acids (PUFAs) which are crucial for growth and reproduction. Besides their significant role as membrane components, C20 PUFAs serve as precursors for eicosanoids, hormone-like mediators of reproduction, immunity and ion transport physiology. In the present study we investigate transcriptomic changes in Daphnia magna in response to different algal food organisms substantially differing in their PUFA composition using quantitative real-time PCR and relate them to concomitantly documented life history data. The selection of target genes includes representatives that have previously been shown to be responsive to the eicosanoid biosynthesis inhibitor ibuprofen. The beneficial effect of C20 PUFA-rich food on reproduction and population growth rates was accompanied by an increased vitellogenin (DmagVtg1) gene expression in D. magna. Additionally, genes involved in eicosanoid signaling were particularly influenced by dietary C20 PUFA availability. For example, the cyclooxygenase gene (Cox), coding for a central enzyme in the eicosanoid pathway, was highly responsive to the food treatments. Our results suggest that dietary PUFAs are fundamental in D. magna physiology as substrate for eicosanoid synthesis and that these eicosanoids are important for D. magna reproduction

Combined effects of dietary polyunsaturated fatty acids and parasite exposure on eicosanoid-related gene expression in an invertebrate model

Eicosanoids derive from essential polyunsaturated fatty acids (PUFA) and play crucial roles in immunity, development, and reproduction. However, potential links between dietary PUFA supply and eicosanoid biosynthesis are poorly understood, especially in invertebrates. Using Daphnia magna and its bacterial parasite Pasteuria ramosa as model system, we studied the expression of genes coding for key enzymes in eicosanoid biosynthesis and of genes related to oogenesis in response to dietary arachidonic acid and eicosapentaenoic acid in parasite-exposed and non-exposed animals. Gene expression related to cyclooxygenase activity was especially responsive to the dietary PUFA supply and parasite challenge, indicating a role for prostanoid eicosanoids in immunity and reproduction. Vitellogenin gene expression was induced upon parasite exposure in all food treatments, suggesting infection-related interference with the host's reproductive system. Our findings highlight the potential of dietary PUFA to modulate the expression of key enzymes involved in eicosanoid biosynthesis and reproduction and thus underpin the idea that the dietary PUFA supply can influence invertebrate immune functions and host-parasite interactions

A dietary polyunsaturated fatty acid improves consumer performance during challenge with an opportunistic bacterial pathogen

A dietary deficiency in polyunsaturated fatty acids (PUFAs) and/or sterols can severely constrain growth and reproduction of invertebrate consumers. Single nutrients are potentially assigned to different physiological processes, for example to support defence mechanisms; therefore, lipid requirements of healthy and pathogen-challenged consumers might differ. In an oral exposure experiment, we explored the effects of dietary PUFAs and cholesterol on growth, reproduction and survival of an aquatic key herbivore (Daphnia magna) exposed to an opportunistic pathogen (Pseudomonas sp.). We show that healthy and pathogen-challenged D. magna are strongly albeit differentially affected by the biochemical composition of their food sources. Supplementation of a C20 PUFA-deficient diet with arachidonic acid (ARA) resulted in increased survival and reproduction of pathogen-challenged D. magna. We propose that the observed benefit of consuming an ARA-rich diet during pathogen challenge is conveyed partially via ARA-derived eicosanoids. This study is one of the first to consider the importance of dietary PUFAs in modifying fitness parameters of pathogen-challenged invertebrate hosts. Our results suggest that dietary PUFA supply should receive increased attention in host–microorganisms interactions and invertebrate disease models to better understand and predict disease dynamics in natural population

Short-Term Dietary Intervention with Cooked but Not Raw <em>Brassica</em> Leafy Vegetables Increases Telomerase Activity in CD8+ Lymphocytes in a Randomized Human Trial

Telomerase in T lymphocytes is dynamic and limited evidence from epidemiological studies indicates that the enzyme can be modulated in peripheral lymphocytes by dietary and lifestyle factors. The differential effect of dietary intervention on T cell subsets has not been investigated so far. Brassica vegetables are known for their multiple beneficial effects on human health, and here, the effect of a five-day short-term intervention with raw or cooked leaves of Brassica carinata on telomerase activity in CD4+ and CD8+ T cells from 22 healthy volunteers was investigated in a randomized single-blind, controlled crossover study. Blood samples were collected before and after intervention, and CD4+/CD8+ T lymphocytes were isolated. Telomerase activity was quantified using the TRAP-ELISA assay. Intervention with both preparations led to a marginal increase in telomerase activity of CD4+ cells compared to the baseline level. In CD8+ cells, a significant increase in telomerase activity (25%, p &lt; 0.05) was seen after intervention with the cooked material. An increase in telomerase activity in CD8+ cells of healthy volunteers could be regarded as beneficial in terms of helping with the cell-mediated immune response. Whether a Brassica intervention has long-term effects on telomere extension in specific T cell subsets needs to be determined

African Nightshade (Solanum scabrum Mill.): Impact of Cultivation and Plant Processing on Its Health Promoting Potential as Determined in a Human Liver Cell Model

Plant cultivation and processing may impact nutrient and phytochemical content of vegetables. The present study aimed at determining the influence of cultivation and processing on the health promoting capacity of African nightshade (Solanum scabrum Mill.) leaves, an indigenous vegetable, rich in nutrients and phytochemicals. Anti-genotoxicity against the human liver carcinogen aflatoxin B1 (AFB1) as determined by the comet assay and radical oxygen species (ROS) scavenging capacity of ethanolic and aqueous extracts were investigated in human derived liver (HepG2) cells. ROS scavenging activity was assessed using electron paramagnetic spin resonance and quantification of ARE/Nrf2 mediated gene expression. The cultivation was done under different environmental conditions. The processing included fermentation and cooking; postharvest ultraviolet irradiation (UV-C) treatment was also investigated. Overall, S. scabrum extracts showed strong health promoting potential, the highest potential was observed with the fermented extract, which showed a 60% reduction of AFB1 induced DNA damage and a 38% reduction in FeSO4 induced oxidative stress. The content of total polyphenols, carotenoids and chlorophylls was indeed affected by cultivation and processing. Based on the present in vitro findings consumption of S. scabrum leaves could be further encouraged, preferentially after cooking or fermentation of the plant.Peer Reviewe