Marriage and Gut (Microbiome) Feelings: Tracing Novel Dyadic Pathways to Accelerated Aging.

Within a couple, partners influence each other's mental and physical health. This review focuses on how couples' relationships, the partners' individual and joint vulnerabilities, and their health behaviors influence health through changes in the gut microbiota, metabolism, and immune function. Couples' shared stressors and emotions and their intertwined lifestyles and routines serve to promote common disease risks in part through parallel changes in their gut microbiotas. Marital discord, stress, and depression have strong bidirectional links, fueling one another. Chronic marital stress and depression can elevate the risk for obesity, metabolic syndrome, and cardiovascular disease by altering resting energy expenditure, insulin production, and triglyceride responses after unhealthy meals. During stressful times, health behaviors typically suffer-and sleep disturbances, poor diets, and sedentary behavior all influence these metabolic pathways while also promoting gut dysbiosis. Dysbiosis increases intestinal permeability (gut leakiness), providing a mechanistic pathway from marital distress and depression to heightened inflammation and accelerated aging. Age-related changes in the gut microbiota's composition and gut leakiness foster immunosenescence, as well as the progression of inflamm-aging; these age-related risks may be altered by stress and depression, diet, sleep, exercise habits, and developmental shifts in emotion regulation strategies. Consideration of the strong mutual influences that partners have on each other's mood and health behaviors, as well as the biological pathways that underlie these influences, provides a new way to view marriage's health implications.

The effect of dietary lipid on gut microbiota in a senescence-accelerated prone mouse model (SAMP8).

Gut microbiota change with aging and diet. In a previous study, it was shown that a moderate-fat diet enriched with fish oil had beneficial effects for elderly patients, so we examined the effect of this diet on aging-related changes in gut microbiota in this study. We used 3-month-old male senescence-accelerated prone mice (SAMP8). The mice were fed a normal diet containing 4 g soybean oil/100 g of diet for 6 months and then divided into 4 groups: (1) the Baseline group, ended breeding at 6 months old; (2) the Control group, continued on a normal diet until 15 months old; (3) the MF group, switched to a moderate-fat diet until 15 months old; and (4) the MF + FO group, switched to a moderate-fat diet enriched with fish oil until 15 months old. When mice were 6 or 15 months old, fecal samples were collected and gut microbiota analysis was performed. Gut microbiota analysis at the genus level showed that bacteria known to increase in association with fatty liver and intestinal inflammation increased with aging. However, this alteration was largely inhibited by the moderate-fat diet enriched with fish oil. On the other hand, there was a decrease with aging in the bacteria that play a role in energy consumption, but this alteration was inhibited by the moderate-fat diet enriched with fish oil. These results suggest that a moderate-fat diet enriched with fish oil has beneficial effects on gut microbiota in aging.

Frontline Science: Tryptophan restriction arrests B cell development and enhances microbial diversity in WT and prematurely aging Ercc1-/Δ7 mice.

With aging, tryptophan metabolism is affected. Tryptophan has a crucial role in the induction of immune tolerance and the maintenance of gut microbiota. We, therefore, studied the effect of dietary tryptophan restriction in young wild-type (WT) mice (118-wk life span) and in DNA-repair deficient, premature-aged (Ercc1-/Δ7 ) mice (20-wk life span). First, we found that the effect of aging on the distribution of B and T cells in bone marrow (BM) and in the periphery of 16-wk-old Ercc1-/Δ7 mice was comparable to that in 18-mo-old WT mice. Dietary tryptophan restriction caused an arrest of B cell development in the BM, accompanied by diminished B cell frequencies in the periphery. In general, old Ercc1-/Δ7 mice showed similar responses to tryptophan restriction compared with young WT mice, indicative of age-independent effects. Dietary tryptophan restriction increased microbial diversity and made the gut microbiota composition of old Ercc1-/Δ7 mice more similar to that of young WT mice. The decreased abundances of Alistipes and Akkermansia spp. after dietary tryptophan restriction correlated significantly with decreased B cell precursor numbers. In conclusion, we report that dietary tryptophan restriction arrests B cell development and concomitantly changes gut microbiota composition. Our study suggests a beneficial interplay between dietary tryptophan, B cell development, and gut microbial composition on several aspects of age-induced changes.

Sepsis-induced hypercytokinemia and lymphocyte apoptosis in aging-accelerated Klotho knockout mice.

Sepsis is primarily a disease of the aged, with 65% of sepsis cases reported in patients older than 65 years and 80% of deaths due to sepsis occurring in this age group. Klotho knockout mice (Klotho mice) are a mouse model of accelerated aging and shortened life span. The purpose of the study was to elucidate the immunological changes occurring in Klotho mice during sepsis. Five-week-old homozygous female Klotho knockout (Klotho) and wild-type (WT) mice were subjected to 1 × 27-gauge cecal ligation and puncture (CLP), and survival was compared after 4 days. Another set of mice was killed at 8 h after CLP or sham surgery, and the spleen, thymus, and serum were harvested. Apoptosis was measured by flow cytometry by using caspase 3. Serum cytokines and bacterial colony count in peritoneal lavage were also analyzed. Klotho septic mice started to die at 8 to 12 h after CLP, and the final survival of Klotho mice was significantly lower than that of WT mice (0% vs. 100%, P < 0.01). Increased bacterial count in the peritoneal cavity and decreased recruitment of neutrophils and macrophages to the peripheral cavity were observed in Klotho-CLP mice. Both flow cytometric and immunohistological analyses showed a dramatic increase in caspase 3-positive cells in the thymus and spleen of Klotho-CLP mice (P < 0.01). Serum concentrations of interleukin 6, tumor necrosis factor α, and interleukin 10 were higher in Klotho-CLP mice than in WT-CLP mice. Hypercytokinemia with impaired bacterial clearance and increased apoptosis of lymphocytes may be related to poor survival in Klotho-septic mice.