Effect of Choline Forms and Gut Microbiota Composition on Trimethylamine-N-Oxide Response in Healthy Men.

BACKGROUND: Trimethylamine-N-oxide (TMAO), a choline-derived gut microbiota-dependent metabolite, is a newly recognized risk marker for cardiovascular disease. We sought to determine: (1) TMAO response to meals containing free versus lipid-soluble choline and (2) effects of gut microbiome on TMAO response. METHODS: In a randomized, controlled, double-blinded, crossover study, healthy men (n = 37) were provided meals containing 600 mg choline either as choline bitartrate or phosphatidylcholine, or no choline control. RESULTS: Choline bitartrate yielded three-times greater plasma TMAO AUC (p = 0.01) and 2.5-times greater urinary TMAO change from baseline (p = 0.01) compared to no choline and phosphatidylcholine. Gut microbiota composition differed (permutational multivariate analysis of variance, PERMANOVA; p = 0.01) between high-TMAO producers (with ≥40% increase in urinary TMAO response to choline bitartrate) and low-TMAO producers (with <40% increase in TMAO response). High-TMAO producers had more abundant lineages of Clostridium from Ruminococcaceae and Lachnospiraceae compared to low-TMAO producers (analysis of composition of microbiomes, ANCOM; p < 0.05). CONCLUSION: Given that phosphatidylcholine is the major form of choline in food, the absence of TMAO elevation with phosphatidylcholine counters arguments that phosphatidylcholine should be avoided due to TMAO-producing characteristics. Further, development of individualized dietary recommendations based on the gut microbiome may be effective in reducing disease risk.

The new total Western diet for rodents does not induce an overweight phenotype or alter parameters of metabolic syndrome in mice.

In this study, we determined the impact of the total Western diet (TWD) for rodents and its macro- and micronutrient components on weight gain and biomarkers of metabolic function in mice compared to a 45% fat diet-induced obesity (DIO) diet and the standard AIN93G diet. We hypothesized that mice fed the TWD would have increased body fat with indicators of metabolic syndrome similar to mice consuming the DIO diet. As expected, DIO-fed mice acquired a metabolic syndrome phenotype typified by increased energy intake, increased body weight gain, increased fat mass, higher fasting glucose, impaired glucose tolerance, and higher plasma leptin relative to the AIN93G diet. Mice fed a macronutrient-modified (MM) diet (with standard vitamin and mineral composition) had a similar response, albeit to a lesser degree than mice fed the DIO diet. Mice fed a vitamin- and mineral-modified diet (with standard macronutrient composition) were not different from mice fed the AIN93G diet. Surprisingly, the TWD (with modified macronutrients, vitamins and minerals) did not significantly affect any of these parameters, despite the fact that the TWD macronutrient profile was identical to the MM diet. These data suggest that, in the context of the TWD, vitamin and mineral intakes in mice that reflect a Western dietary pattern inhibit the hyperphagia and resulting increased weight gain associated with the higher fat content of the TWD. In conclusion, these observations underscore the need to consider the influence of micronutrient intakes in pre-clinical models of obesity and metabolic syndrome.

Vascular leak ensues a vigorous proinflammatory cytokine response to Tacaribe arenavirus infection in AG129 mice.

BACKGROUND: Tacaribe virus (TCRV) is a less biohazardous relative of the highly pathogenic clade B New World arenaviruses that cause viral hemorrhagic fever syndromes and require handling in maximum containment facilities not readily available to most researchers. AG129 type I and II interferon receptor knockout mice have been shown to be susceptible to TCRV infection, but the pathogenic mechanisms contributing to the lethal disease are unclear. METHODS: To gain insights into the pathogenesis of TCRV infection in AG129 mice, we assessed hematologic and cytokine responses during the course of infection, as well as changes in the permeability of the vascular endothelium. We also treated TCRV-challenged mice with MY-24, a compound that prevents mortality without affecting viral loads during the acute infection, and measured serum and tissue viral titers out to 40 days post-infection to determine whether the virus is ultimately cleared in recovering mice. RESULTS: We found that the development of viremia and splenomegaly precedes an elevation in white blood cells and the detection of high levels of proinflammatory mediators known to destabilize the endothelial barrier, which likely contributes to the increased vascular permeability and weight loss that was observed several days prior to when the mice generally succumb to TCRV challenge. In surviving mice treated with MY-24, viremia and liver virus titers were not cleared until 2-3 weeks post-infection, after which the mice began to recover lost weight. Remarkably, substantial viral loads were still present in the lung, spleen, brain and kidney tissues at the conclusion of the study. CONCLUSIONS: Our findings suggest that vascular leak may be a contributing factor in the demise of TCRV-infected mice, as histopathologic findings are generally mild to moderate in nature, and as evidenced with MY-24 treatment, animals can survive in the face of high viral loads.