Multiomics assessment of dietary protein titration reveals altered hepatic glucose utilization

Chronic polypharmacy, monotherapy, and deprescribing: Understanding complex effects on the hepatic proteome of aging mice

Polypharmacy (use of ≥5 concurrent medications) is highly prevalent among older adults to manage chronic diseases and is linked to adverse geriatric outcomes, including physical and cognitive functional impairments, falls, frailty, hospitalization, and mortality. Deprescribing (withdrawal) is a potential strategy to manage polypharmacy. The broad molecular changes by which polypharmacy causes harm and deprescribing may be beneficial are unknown and unfeasible to study rigorously in tissue from geriatric patients. Therefore, in a randomized controlled trial, we administered therapeutic doses of commonly used chronic medications (oxycodone, oxybutynin, citalopram, simvastatin, or metoprolol) as monotherapy or concurrently (polypharmacy) from middle-age (12 months) to old-age (26 months) to male C57BL/6J (B6) mice and deprescribed (gradually withdrew) treatments in a subset from age 21 months. We compared drug-related hepatic effects by applying proteomics along with transcriptomics and histology. We found that monotherapy effects on hepatic proteomics were limited but significant changes were seen with polypharmacy (93% unique to polypharmacy). Polypharmacy altered the hepatic expression of proteins involved in immunity, and in drug, cholesterol, and amino acid metabolism, accompanied by higher serum drug levels than monotherapies. Deprescribing not only reversed some effects but also caused irreversible and novel changes in the hepatic proteome. Furthermore, our study identified several hepatic protein co-expressed modules that are associated with clinically relevant adverse geriatric outcomes, such as mobility, frailty, and activities of daily living. This study highlights the complex molecular changes following aging, chronic polypharmacy, and deprescribing. Further exploration of these mechanistic pathways may inform management of polypharmacy and deprescribing in older adults.

Sex-Specific Variation in Metabolic Responses to Diet

Suboptimal nutrition is a leading cause of cardiometabolic disease and mortality. Biological sex is a variable that influences individual responses to dietary components and may modulate the impact of diet on metabolic health and disease risk. This review describes findings of studies reporting how biological sex may associate with or affect metabolic outcomes or disease risk in response to varying dietary macronutrient content, Mediterranean diet, Western diet, and medical very low-calorie diet. Although few dietary interventions have been specifically designed to identify sex-diet interactions, future studies improving understanding how sex influences dietary responses could inform precision nutrition interventions for disease prevention and management.

Sulfur Amino Acid Restriction Enhances Exercise Capacity in Mice by Boosting Fat Oxidation in Muscle

Dietary restriction of the sulfur-containing amino acids methionine and cysteine (SAAR) improves body composition, enhances insulin sensitivity, and extends lifespan; benefits seen also with endurance exercise. Yet, the impact of SAAR on skeletal muscle remains largely unexplored. Here we demonstrate that one week of SAAR in sedentary, young, male mice increases endurance exercise capacity. Indirect calorimetry showed that SAAR increased lipid oxidation at rest and delayed the onset of carbohydrate utilization during exercise. Transcriptomic analysis revealed increased expression of genes involved in fatty acid catabolism especially in glycolytic muscle following SAAR. These findings were functionally supported by increased fatty acid circulatory turnover flux and muscle β-oxidation. Reducing lipid uptake from circulation through endothelial cell (EC)-specific CD36 deletion attenuated the running phenotype. Mechanistically, VEGF-signaling inhibition prevented exercise increases following SAAR, without affecting angiogenesis, implicating noncanonical VEGF signaling and EC CD36-dependent fatty acid transport in regulating exercise capacity by influencing muscle substrate availability.

Dietary factors and their influence on immunotherapy strategies in oncology: a comprehensive review

Immunotherapy is emerging as a promising avenue in oncology, gaining increasing importance and offering substantial advantages when compared to chemotherapy or radiotherapy. However, in the context of immunotherapy, there is the potential for the immune system to either support or hinder the administered treatment. This review encompasses recent and pivotal studies that assess the influence of dietary elements, including vitamins, fatty acids, nutrients, small dietary molecules, dietary patterns, and caloric restriction, on the ability to modulate immune responses. Furthermore, the article underscores how these dietary factors have the potential to modify and enhance the effectiveness of anticancer immunotherapy. It emphasizes the necessity for additional research to comprehend the underlying mechanisms for optimizing the efficacy of anticancer therapy and defining dietary strategies that may reduce cancer-related morbidity and mortality. Persistent investigation in this field holds significant promise for improving cancer treatment outcomes and maximizing the benefits of immunotherapy.

Short-term hypercaloric carbohydrate loading increases surgical stress resilience by inducing FGF21

Dietary restriction promotes resistance to surgical stress in multiple organisms. Counterintuitively, current medical protocols recommend short-term carbohydrate-rich drinks (carbohydrate loading) prior to surgery, part of a multimodal perioperative care pathway designed to enhance surgical recovery. Despite widespread clinical use, preclinical and mechanistic studies on carbohydrate loading in surgical contexts are lacking. Here we demonstrate in ad libitum-fed mice that liquid carbohydrate loading for one week drives reductions in solid food intake, while nearly doubling total caloric intake. Similarly, in humans, simple carbohydrate intake is inversely correlated with dietary protein intake. Carbohydrate loading-induced protein dilution increases expression of hepatic fibroblast growth factor 21 (FGF21) independent of caloric intake, resulting in protection in two models of surgical stress: renal and hepatic ischemia-reperfusion injury. The protection is consistent across male, female, and aged mice. In vivo, amino acid add-back or genetic FGF21 deletion blocks carbohydrate loading-mediated protection from ischemia-reperfusion injury. Finally, carbohydrate loading induction of FGF21 is associated with the induction of the canonical integrated stress response (ATF3/4, NF-kB), and oxidative metabolism (PPARγ). Together, these data support carbohydrate loading drinks prior to surgery and reveal an essential role of protein dilution via FGF21.

Protein Restriction in Metabolic Health: Lessons from Rodent Models

Consumption of protein-rich diets and supplements has been increasingly advocated by individuals seeking to optimize metabolic health and mitigate the effects of aging. Protein intake is postulated to support muscle mass retention and enhance longevity, underscoring its perceived benefits in age-related metabolic regulation. However, emerging evidence presents a paradox; while moderate protein consumption contributes to health maintenance, an excessive intake is associated with an elevated risk of chronic diseases, notably obesity and diabetes. Furthermore, recent studies suggest that reducing the ratio of protein intake to macronutrients improves metabolic parameters and extends lifespan. The aim of this study is to review the current evidence concerning the metabolic effects of protein-restricted diets and their potential mechanisms. Utilizing rodent models, investigations have revealed that protein-restricted diets exert a notable influence over food intake and energy consumption, ultimately leading to body weight loss, depending on the degree of dietary protein restriction. These phenotypic alterations are primarily mediated by the FGF21 signaling pathway, whose activation is likely regulated by ATF4 and the circadian clock. The evidence suggests that protein-restricted diets as an alternative approach to calorie-restricted regimes, particularly in overweight or obese adults. However, more research is needed to determine the optimal level of restriction, duration, and long-term effects of such interventions.

Dietary restriction of isoleucine increases healthspan and lifespan of genetically heterogeneous mice

Low-protein diets promote health and longevity in diverse species. Restriction of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine recapitulates many of these benefits in young C57BL/6J mice. Restriction of dietary isoleucine (IleR) is sufficient to promote metabolic health and is required for many benefits of a low-protein diet in C57BL/6J males. Here, we test the hypothesis that IleR will promote healthy aging in genetically heterogeneous adult UM-HET3 mice. We find that IleR improves metabolic health in young and old HET3 mice, promoting leanness and glycemic control in both sexes, and reprograms hepatic metabolism in a sex-specific manner. IleR reduces frailty and extends the lifespan of male and female mice, but to a greater degree in males. Our results demonstrate that IleR increases healthspan and longevity in genetically diverse mice and suggests that IleR, or pharmaceuticals that mimic this effect, may have potential as a geroprotective intervention.

Effects of Omega-3-Rich Pork Lard on Serum Lipid Profile and Gut Microbiome in C57BL/6NJ Mice

Background and Aims. Hyperlipidemia is a risk factor for cardiovascular diseases. This study is aimed at investigating the effects of consuming omega-3-rich pork lard on the serum lipid profile and gut microbiome of the mice model. Methods and Results. We divided 23 C57BL/6NJ males (16-week-old) into 3 groups, and each group received either a control diet, a high-fat diet of coconut oil (coconut oil), or a high-fat diet of omega-3-rich pork lard (omega lard) for 28 days. Thereafter, fasting serum lipids and fecal microbiomes were analyzed. The serum cholesterol, triglyceride, and LDL levels of the omega lard-treated group were significantly reduced compared to the coconut oil-treated group ( $P<0.05$ ). However, the microbiome analysis revealed a significant increase in the abundance of Lachnospiraceae in the omega lard-treated group compared to the coconut oil-treated group ( $P<0.05$ ). Furthermore, Spearman’s correlation analysis revealed that the increased serum lipid content was positively correlated with the abundance of Bacteroidaceae ( $P<0.05$ ) and negatively correlated with the abundance of Lachnospiraceae ( $P<0.05$ ). Conclusions. These findings suggested that omega-3-rich pork lard altered the serum lipid profile and gut microbiome in the mice model. Practical Application. The excellent protection offered by omega-3-rich pork lard against hyperlipidemia indicated that pork lard could be used as alternative cooking oil for health-conscious individuals. It could also be introduced as a functional ingredient for patients with hyperlipidemia.