Abnormal food timing and predisposition to weight gain: Role of barrier dysfunction and microbiota

Abstract

Obesity has become a common rising health care problem, especially in "modern" societies. Obesity is considered a low-grade systemic inflammation, partly linked to leaky gut. Circadian rhythm disruption, a common habit in modern life, has been reported to cause gut barrier impairment. Abnormal time of eating, defined by eating close to or during rest time, is shown to cause circadian rhythm disruption. Here, using a non-obesogenic diet, we found that abnormal feeding time facilitated weight gain and induced metabolic dysregulation in mice. The effect of abnormal time of eating was associated with increased gut permeability, estimated by sucralose and/or lactulose ratio and disrupted intestinal barrier marker. Analysis of gut microbiota and their metabolites, as important regulators of barrier homeostasis, revealed that abnormal food timing reduced relative abundance of butyrate-producing bacteria, and the colonic butyrate level. Overall, our data supported that dysbiosis was characterized by increased intestinal permeability and decreased beneficial barrier butyrate-producing bacteria and/or metabolite to mechanistically link the time of eating to obesity. This data provides basis for noninvasive microbial-targeted interventions to improve intestinal barrier function as new opportunities for combating circadian rhythm disruption induced metabolic dysfunction.

Figure 1.. Schematic overview of the study design.

C57BL/6J mice (n = 5 per group) underwent right-time feeding (RTF) only during the dark vs. wrong-time feeding (WTF) only during the light, with water available ad-libitum for 12 weeks.

Figure 2.. Abnormal Time of Eating Predisposes to Weight Gain in Mice.

(A) Right time fed (active/dark phase) and wrong time fed (resting/light phase) mice groups, with regular non-obesogenic chow diet, both showed similar weight trends that increased over a period of 12-weeks. (B) Each mouse group’s weight gain can be explained by their food intake which showed a significant negative correlation between food intake and weight gain over time. As food intake decreased over time, weight increased. Mice group’s mean and standard deviation (SD) error bars for each time point collection depicted. Multiple group comparisons by controlling for false-discovery rate, where wrong time fed mice significantly consumed less total calories than right time fed mice are indicated by asterisks (Week 1: q=0.016; Week 3: q=0.016; Week 5 p=0.041; Week 7 q=0.016; Week 9 p=0.032).

Figure 3.. Abnormal Time of Eating is associated with Increased Gut Permeability and Systemic Metabolic Dysregulation.

Intestinal barrier was compared between the groups: (A) The sucralose/lactulose ratio and (B) mucosal E-cadherin expression as markers of gut permeability were compared in the wrong-time fed vs. right-time fed mice. Metabolic markers of obesity were compared between the groups: (C) The homeostatic model assessment of insulin resistance (HOMA-IR) was calculated using the equation [(Glucose × Insulin)/405]; (D) Fasting serum Leptin was measured. Data are expressed as mean ± SEM; *P<0.05, **P<0.01.

Figure 4.. E-Cadherin Immunofluorescent Colonic Mucosal Tissue Staining.

Representative of colonic E-Cadherin expression in the Right Time and Wrong Time Fed Mice.

Figure 5.. Wrong Time Feeding is associated with altered Microbial Structure and Decreased Butyrate-Producing Bacteria.

(A) The nMDS plot of fecal microbial community structure showed a significant effect of time of eating (ANOSIM: R = 0.464, P=0.008; taxonomic level of genus). (B) The average relative abundance of order Lactobacillales was higher (Kruskal-Wallis CLR: P = 0.009) in wrong time fed mice feces; whereas, (C) the average relative abundance of order Clostridiales trended lower compared to right time fed mice feces. (D) Feeding time affected microbial taxa: stacked column plots depicting the average number of rarefied microbial reads (>1%), with different taxa bolded (Kruskal-Wallis CLR: P < 0.009) between right time and wrong time fed mice feces, at the genus taxonomic level. (E) Mice fed at the wrong time had significantly lower (MWU: P=0.032) average relative abundance ratio of total Butyrate-to-total SCFA-producing genera in feces. Data are expressed as mean ± SEM; *P<0.05, ***P<0.001.

Figure 6.. Wrong Time Feeding is associated with Decreased Intestinal Butyrate Levels.

(A) The total SCFA metabolites and (B) the total Butyrate metabolites as measured by gas chromatography in stool samples, are compared following wrong time vs. right time feeding. Data are expressed as mean ± SEM; *P<0.05.