Obesity dysregulates B cell populations, which contributes toward poor immunological outcomes. We previously reported that differing B cell subsets are lowered in the bone marrow of obese male mice. Here, we focused on how lipid metabolites synthesized from docosahexaenoic acid (DHA) known as specialized pro-resolving lipid mediators (SPMs) influence specific B cell populations in obese male mice. Metabololipidomics revealed that splenic SPM precursors 14-hydroxydocosahexaenoic acid (14-HDHA), 17-hydroxydocosahexaenoic acid (17-HDHA), and downstream protectin DX (PDX) were decreased in obese male C57BL/6J mice. Simultaneous administration of these mediators to obese mice rescued major decrements in bone marrow B cells, modest impairments in the spleen, and circulating IgG2c, which is pro-inflammatory in obesity. In vitro studies with B cells, flow cytometry experiments with ALOX5−/− mice, and lipidomic analyses revealed the lowering of 14-HDHA/17-HDHA/PDX and dysregulation of B cell populations in obesity was driven indirectly via B cell extrinsic mechanisms. Notably, the lowering of lipid mediators was associated with an increase in the abundance of n-6 polyunsaturated fatty acids, which have a high affinity for SPM-generating enzymes. Subsequent experiments revealed female obese mice generally maintained the levels of SPM precursors, B cell subsets, and antibody levels. Finally, obese human females had increased circulating plasma cells accompanied by ex vivo B cell TNFα and IL-10 secretion. Collectively, the data demonstrate that DHA-derived mediators of the SPM pathway control the number of B cell subsets and pro-inflammatory antibody levels in obese male but not female mice through a defect that is extrinsic to B cells.

Plasma lipid levels are altered in chronic conditions such as type 2 diabetes and cardiovascular disease as well as during acute stresses such as fasting and cold exposure. Advances in MS-based lipidomics have uncovered a complex plasma lipidome of more than 500 lipids that serve functional roles, including as energy substrates and signaling molecules. This plasma lipid pool is maintained through regulation of tissue production, secretion, and uptake. A major challenge in understanding the lipidome complexity is establishing the tissues of origin and uptake for various plasma lipids, which is valuable for determining lipid functions. Using cold exposure as an acute stress, we performed global lipidomics on plasma and in nine tissues that may contribute to the circulating lipid pool. We found that numerous species of plasma acylcarnitines (ACars) and ceramides (Cers) were significantly altered upon cold exposure. Through computational assessment, we identified the liver and brown adipose tissue as major contributors and consumers of circulating ACars, in agreement with our previous work. We further identified the kidney and intestine as novel contributors to the circulating ACar pool and validated these findings with gene expression analysis. Regression analysis also identified that the brown adipose tissue and kidney are interactors with the plasma Cer pool. Taken together, these studies provide an adaptable computational tool to assess tissue contribution to the plasma lipid pool. Our findings have further implications in understanding the function of plasma ACars and Cers, which are elevated in metabolic diseases.

Consumer interest in the source of their food, its environmental footprint, and the impact of diet on health has supported the growth of the grass-finished beef (GFB) industry. Studies have concluded that GFB has distinct nutritional differences from conventionally-finished beef. As the GFB industry continues to expand, it is vital to continue to explore the nutritional complexities and variation in the product. To achieve this, a survey of grass-finishing production systems throughout the USA was conducted, and beef finished on the participating farms was analyzed for its nutritional composition, including fatty acid (FA), mineral and fat-soluble vitamin contents. Samples were analyzed from 12 producers and annual production capacity of farms ranged from 25 to 5,000 cattle, with a mean age of cattle at harvest of 26.8 ± 2.30 mo. An array of finishing diets included grazing exclusively in perennial pasture, incorporating annual forage crops, and feeding a variety of harvested forages with supplementation of non-starch feed byproducts. Beef muscle tissue FA content was analyzed by gas chromatography-mass spectrometry (GC–MS). The mean ratio of omega-6 (n-6) to omega-3 (n-3) FA in samples varied significantly by producer, ranging from 1.80 to 28.3 (P < 0.0001), with an overall sample set median of 4.10. A selection of minerals including iron, magnesium, and potassium were analyzed by ICP emission spectroscopy and mineral content significantly differed by producer for all minerals (P < 0.001). Mean α-tocopherol and β-carotene content was 610.6 µg/100 g beef and 32.2 µg/100 g, respectively. The amount of these antioxidants also varied between producers (P < 0.0001), but tended to be greater in beef finished solely on fresh forages. This survey indicates that commercially available GFB can vary in nutritional composition due to the diverse practices used to grass-finish cattle. Copyright © 2019. American Meat Science Association .

In Northern Ghana, 33% of children are stunted due to economic disparities. Dietary fatty acids (FA) are critical for growth, but whether blood FA levels are adequate in Ghanaian children is unknown. The objective of this study was to determine the association between whole blood FAs and growth parameters in Northern Ghanaian children 2–6 years of age. A drop of blood was collected on an antioxidant treated card and analyzed for FA composition. Weight and height were measured and z-scores were calculated. Relationships between FAs and growth parameters were analyzed by Spearman correlations, linear regressions, and factor analysis. Of the 307 children who participated, 29.7% were stunted and 8% were essential FA deficient (triene/tetraene ratio>0.02). Essential FA did not differ between stunted and non-stunted children and was not associated with height-for-age z-score (HAZ) or weight-for-age z-score (WAZ). In hemoglobin adjusted regression models, both HAZ and WAZ were positively associated with arachidonic acid (p≤0.01), dihomo-gamma-linolenic acid (DGLA, p≤0.05), docosatetraenoic acid (p≤0.01) and the ratio of DGLA/linoleic acid (p≤0.01). These data add to the growing body of evidence indicating n-6 FAs are critical in childhood linear growth. Our findings provide new insights into the health status of an understudied Northern Ghanaian population.

There is increased consumer interest in grass-finished beef (GFB) with retail sales reaching $272 million in 2016. GFB contains higher omega-3 fatty acid levels compared to grain-finished beef, but variations in fatty acid (FA), mineral, and antioxidant content by producers and season is poorly documented. Hence, GFB samples from cattle finished in both fall and spring were obtained from four producers representing several US sub-regions. FAs were extracted using microwave-assisted extraction, derivatized to methyl-esters, and quantified using gas chromatography-mass spectrometry. Mineral content was quantified using coupled plasma mass-spectrometry and antioxidants were quantified via UV-absorption. Overall, total omega-3 FA content was greater in beef from cattle finished in the spring (13.4 mg/100g beef) than the fall (10.3; P<0.001). Additionally, α-tocopherol was present in greater amounts in spring-finished beef (259 vs. 223 ug/100g beef, P<0.001) as was the micromineral selenium (18.2 vs. 17.3ug/100g beef, P = 0.008). Despite using the same feed in fall and spring, cattle from producer 4 had higher total omega-3, omega-6, and total polyunsaturated fatty acids in spring compared to fall (P<0.010). These results suggest there are seasonal differences in omega-3 and omega-6 fatty acids, minerals and antioxidants in grass-finished beef independent of finishing diet.