Circadian Rhythm Disruption Influenced Hepatic Lipid Metabolism, Gut Microbiota and Promoted Cholesterol Gallstone Formation in Mice

Gut microbiota promotes cholesterol gallstone formation through the gut-metabolism-gene axis

BACKGROUND

Gallstone disease, arising from the interplay between host metabolism and gut microbiota, represents a significant health concern. Dysbiosis of the gut microbiome and disruptions in circadian rhythm contribute to the pathogenesis of gallstones. This study conducted a comprehensive analysis of gut microbiota and metabolites derived from stool and serum samples of 28 patients with cholesterol gallstones (CGS) and 19 healthy controls, employing methodologies such as 16S rRNA sequencing, metaproteomics, metabolomics, and host genetic analysis. Additionally, a retrospective cohort study was utilized to assess the efficacy of probiotics or ursodeoxycholic acid (UDCA) in preventing CGS formation post-bariatric surgery.

RESULTS

In CGS patients, gut microbiota diversity shifted, with harmful bacteria rising and beneficial ones declining. The altered microbiota primarily affected amino acid, lipid, nucleotide, and carbohydrate metabolism. Metabolic abnormalities were noted in amino acids, glucose, lipids, and bile acids with decreased levels of ursodeoxycholic, glycosodeoxycholic, and glycolithocholic acids, and increased glycohyodeoxycholic and allocholic acids. Glutamine and alanine levels dropped, while phenylalanine and tyrosine rosed. Animal studies confirmed gene changes in gallbladder tissues related to bile acid, energy, glucose, and lipid metabolism. Importantly, UDCA and probiotics effectively reduced CGS risk post-bariatric surgery, especially when combined.

CONCLUSIONS

Multi-omics can clarify CGS pathology, by focusing on the gut-metabolism-gene axis, paving the way for future studies on CGS prevention and treatment through gut microbiota or metabolic interventions.

Quantity and meal timing of dietary cholesterol intake and cerebrovascular disease mortality

Background: Recent guidelines have removed specific limitations of dietary cholesterol, which has raised considerable debate regarding the significance of cholesterol in the context of cerebrovascular disease (CBD). Furthermore, the relationship between the quantity and meal timing of dietary cholesterol intake and CBD mortality remains unclear. This study aims to explore the relationships between the quantity and meal timing of dietary cholesterol intake and CBD mortality among older adults using the U.S. National Health and Nutrition Examination Survey (NHANES) (2003-2018). Methods: In this prospective study of 7906 older adults aged over 50 years in the National Health and Nutrition Examination Survey (2003-2018), dietary intake was divided into quintiles, and meal timing was evaluated using two days of 24-hour dietary recall. Serum cholesterol levels were measured. The relationship between the quantity and meal timing of dietary cholesterol and mortality was examined with survey-weighted Cox regression models. Results: During a follow-up of 15 years, 107 participants died of CBD. Compared with participants with the lowest quintile of total cholesterol intake (CHO-T) and cholesterol at breakfast (CHO-B), no significant association between CHO-T and CHO-B and mortality (HRCHO-T 0.48; 95%CI 0.18-1.23 and HRCHO-B 0.98; 95%CI 0.37-2.47) was observed. For the difference of cholesterol at dinner (CHO-D) minus CHO-B (ΔCHO), which was related to lower CBD mortality (HR 0.45; 95%CI 0.21-0.97), 29-142 mg of ΔCHO was associated with lower CBD mortality in a non-linear manner and 29-112 mg of ΔCHO was associated with lower TC and LDL-C levels. Conclusions: Moderate consumption of dietary cholesterol at dinner rather than breakfast was associated with a lower risk of CBD mortality in a nonlinear manner, whereas the total quantity of dietary cholesterol throughout the day was not associated with CBD mortality.

Depressive symptoms mediate the association between sleep disorders and gallstone disease: a causal mediation analysis of NHANES 2017-2020

Background

Gallstones are a prevalent digestive system disorder with significant health implications. Recent research suggests that sleep disorders, such as insomnia and obstructive sleep apnea hypopnea syndrome, may influence the development of gallstones through various metabolic pathways. Depression, often accompanying sleep disorders, may play a mediating role in this relationship. This study uses data from the 2017-2020 National Health and Nutrition Examination Survey (NHANES) to explore the potential mediating role of depression in the association between sleep disorders and gallstones.

Methods

We analyzed data from 7,868 adults aged 20 and older from NHANES 2017-2020. Gallstones were defined based on self-reported medical diagnoses. Sleep disorders were assessed through self-reported sleep difficulties, and depressive symptoms were measured using the Patient Health Questionnaire-9 (PHQ-9) scale. Logistic regression models evaluated direct associations between sleep disorders, depressive symptoms, and gallstones. Causal mediation analysis further examined the mediating role of depressive symptoms. Finally, subgroup analyses were performed by age, sex, and obesity status.

Results

Both sleep disorders (OR = 2.00; 95% CI, 1.73-2.32; P<0.001) and depressive symptoms (OR = 2.09; 95% CI, 1.70-2.56; P<0.001) were significantly associated with gallstones, with results remaining significant after adjusting for confounders. A significant association was also observed between sleep disorders and depressive symptoms (OR = 5.53; 95% CI, 4.71-6.50; P<0.001). Mediation analysis indicated that depressive symptoms partially mediate the relationship between sleep disorders and gallstones, with an average causal mediation effect (ACME) of 0.00720 (95% CI, 0.00299-0.01220; P<0.001) and an average direct effect (ADE) of 0.0305 (95% CI, 0.0129-0.0488; P<0.001). Depression mediates 18.89% (95% CI, 0.0704-0.4096; P<0.001) of the association between sleep disorders and gallstones. Subgroup analyses showed significant mediation by depressive symptoms in individuals aged 40-59, males, and both obese and non-obese groups (all P<0.05), although no significant mediation was found in females (P>0.05).

Conclusion

This study demonstrates a significant association between sleep disorders and gallstones, with depressive symptoms playing a partial mediating role. Improving depressive symptoms may help reduce the risk of gallstones associated with sleep disorders.

Single and Multiple Doses of Seladelpar Decrease Diurnal Markers of Bile Acid Synthesis in Mice

Peroxisome proliferator-activated receptors (PPARs) modulate bile metabolism and are important therapeutic options in cholestatic diseases. This study was aimed at understanding the effects of single and multiple doses of seladelpar, a PPARδ (peroxisome proliferator-activated receptor delta) agonist, on plasma C4 (a freely diffusible metabolite accepted as a proxy for de novo bile acid biosynthesis), Fibroblast Growth Factor 21 (Fgf21), and gene expression changes in the liver of male and female mice. C57BL/6 mice were treated with seladelpar 10 mg/kg/day or vehicle through oral gavage before lights out on Day 1 (single dose) or from Day 1 to Day 7 (multiple doses). Liver samples were obtained at 0, 1, 2, 4, 8, 12, 16, and 24 h postdosing, and plasma C4 and Fgf21 levels were measured. In vehicle-treated mice, C4 levels were higher in the dark cycle compared to the light cycle, with higher levels in females than in males. Plasma Fgf21 did not vary substantially over the dark-light cycle or show a sex-specific expression pattern. Seladelpar treatment significantly reduced plasma C4 and increased Fgf21 levels in both sexes, which coincided with a decrease in cholesterol 7α-hydroxylase mRNA and an increase in Fgf21 mRNA in the livers. Untargeted RNA sequencing revealed a strong correlation between the genes differentially expressed after single- and multiple-dose seladelpar treatment. PPAR-responsive genes, including pyruvate dehydrogenase kinase 4, acyl-CoA thioesterase 2, and angiopoietin-like 4, were upregulated. No changes in nuclear receptors, clock genes, and sex-specific genes were observed. Overall, these results are consistent with a model where seladelpar treatment reduces bile acid synthesis by upregulating Fgf21 and modulating other PPAR-responsive genes.

Theabrownin remodels the circadian rhythm disorder of intestinal microbiota induced by a high-fat diet to alleviate obesity in mice

The intestinal microbiota undergoes diurnal compositional and functional oscillations within a day, which affect the metabolic homeostasis of the host and exacerbate the occurrence of obesity. TB has the effect of reducing body weight and lipid accumulation, but the mechanism of improving obesity caused by a high-fat diet based on the circadian rhythm of intestinal microorganisms has not been clarified. In this study, we used multi-omics and imaging approaches to investigate the mechanism of TB in alleviating obesity in mice based on the circadian rhythm of gut microbiota. The results showed that TB could significantly regulate the levels and rhythmic expression of serum lipid indicators (TG, TC, LDL) and serum hormones (MT, FT3, LEP, CORT). The number of intestinal microbiota colonizing the colonic epithelium underwent daily fluctuations. TB remodeled the rhythmic oscillation of gut microbes (i.e., Lachnospiraceae_NK4A136_group, Alistipes, etc.), including the number, composition, abundance and rhythmic expression of the biogeographic localization of microbes. TB notably reduced the levels of 16 bile acids (TCA, THDCA, TCDA, GHDCA, T-α-MCA, etc.) and restored the balance of bile acid metabolism. It was found that TB may mitigate high-fat diet-induced obesity in mice by reshaping the circadian rhythm of the gut microbiome and regulating bile acid metabolism.

The association between life's essential 8 and gallstones: A cross-sectional study

This study investigates the relationship between Life's Essential 8 (LE8), a measure of cardiovascular health (CVH), and the risk of gallstones in adult Americans. We analyzed data from 5,024 participants aged 20 and older, using information from the 2017-2020 National Health and Nutrition Examination Survey. Gallstone presence was determined via a standard questionnaire. LE8 scores, representing four health behaviors (sleep, tobacco/nicotine exposure, physical activity, and diet) and four health factors (body mass index, non-high-density lipoprotein cholesterol, blood glucose, and blood pressure), were categorized into low, moderate, and high CVH groups. Weighted logistic regression, restricted cubic splines (RCS), and stratified analyses were used to assess the association between LE8 and gallstones. Of the 5,024 participants, 543 (11.22%) had gallstones. In fully adjusted models, participants with high CVH (LE8 ≥ 80) had a 59% lower risk of gallstones compared to those with low CVH (LE8 < 50) (OR: 0.41, 95% CI: 0.23-0.72, P = 0.010). RCS analyses suggested a nonlinear relationship between LE8 and gallstones. Stratified analysis showed a stronger association in participants under 65 (OR: 0.26, 95% CI: 0.15-0.44), females (OR: 0.44, 95% CI: 0.24-0.81), those with higher education (OR: 0.39, 95% CI: 0.19-0.78), non-white individuals (OR: 0.28, 95% CI: 0.13-0.60), and married participants (OR: 0.40, 95% CI: 0.20-0.80).Higher CVH, as measured by LE8, is associated with a lower risk of gallstones among adult Americans.

An association between average daily sleep duration and gallstones in US adults

Despite extensive research on the impact of health factors and sleep, the specific association between average daily sleep duration and the prevalence of gallstones in adults has not been thoroughly investigated. This study analyzes data from 7,441 individuals from the NHANES 2017-2020 dataset, using exclusion criteria to refine the participant pool. Employing multivariate logistic regression and subgroup analyses while controlling for potential confounders, we assessed the association between average daily sleep duration and the prevalence of gallstones. Our results revealed a statistically significant inverse association (OR = 0.92; 95% CI: 0.86, 0.99; p = 0.0236). This association was consistent across various demographic and health-related subgroups. Interestingly, the inflection points were observed among middle-aged adults (40-60 years) and individuals with diabetes. These findings could inform public health strategies on sleep management, potentially aiding in the prevention of gallstones within these populations.

NXT629 Ameliorates Cholesterol Gallstones in Mice Model by Improving Lipid Metabolism Disorder and Cholesterol Homeostasis Through Inhibiting the GPAM Pathway

BACKGROUND

NXT629, a PPAR-alpha antagonist, exerts widespread effects in many diseases; however, its function and relevant mechanism in cholesterol gallstones (CG) remain largely unknown.

METHODS

Male C57BL/6 J mice were fed a regular diet or lithogenic diet (LD), followed by treatment with intraperitoneal injection of NXT629. H&E staining was performed to analyze hepatic pathological changes, and Oil red O staining was conducted to detect lipid accumulation. Concentrations of total cholesterol (TC), triglyceride (TG), phospholipids (PL), total bile acids (TBA), and cholesterol saturation index (CSI) in both bile and serum were analyzed using commercially available kits. The mRNA expressions of ABCG5/8, CYP7A1, CYP7B1, PPAR-α, and ABCB11 in mouse liver tissues were measured by qRT-PCR assay. Overexpression of glycerol-3-phosphate acyltransferase mitochondrial (GPAM) was constructed to investigate the molecular mechanism of NXT629 in CG.

RESULTS

NXT629 could prevent the formation of cholesterol gallstones (CG) and improve lipid metabolic disorders in mice fed a lithogenic diet (LD). Treatment with NXT629 significantly reduced the levels of ABCG5, ABCG8, and ABCB11, while increasing the levels of CYP7A1 and CYP7B1 in the LD group. Additionally, NXT629 treatment downregulated GPAM expression in hepatic tissue from LD-fed mice. Overexpression of GPAM partially counteracted the beneficial effects of NXT629 on CG formation, lipid metabolic disorders, and lipid-related gene expressions.

CONCLUSION

NXT629 can inhibit CG formation, improve lipid metabolism disorders and cholesterol homeostasis by inhibiting GPAM expression, suggesting that NXT629 may serve as a potential therapeutic strategy for cholesterol stones prevention and treatment.

Relationship between mucin gene polymorphisms and different types of gallbladder stones

BACKGROUND

Gallstones, a common surgical condition globally, affect around 20% of patients. The development of gallstones is linked to abnormal cholesterol and bilirubin metabolism, reduced gallbladder function, insulin resistance, biliary infections, and genetic factors. In addition to these factors, research has shown that mucins play a role in gallstone formation. This study aims to explore the connection between different types of gallstones and mucin gene polymorphisms.

METHODS

For this purpose, a total of 121 patients with gallbladder stones PNS and 107 patients with healthy controls PNS were enrolled in this case-control study. One SNPs (rs4072037) of MUC1 gene、 three SNPs (rs2856111、rs41532344、rs41349846) of MUC2 gene、four SNPs (rs712005、rs2246980、rs2258447、rs2259292) of MUC4 gene、seven SNPs (rs28415193、rs56047977、rs2037089、rs2075854、rs3829224、rs2672785、rs2735709) of MUC5 gene、eight SNPs (rs10902268、rs61869016、rs573849895、rs59257210、rs7396383、rs74644072、rs7481521、rs9704308) of MUC6 gene、five SNPs (rs10229731、rs73168398、rs4729655、rs55903219、rs74974199) of MUC17 gene. We amplified SNP sites by polymerase chain reaction (PCR) using specific primer sets followed by DNA sequencing.

RESULTS

The frequencies of MUC2 rs2856111 C/T genotype (OR = 3.81, 95%CI: 1.06-13.68) was higher than the control group. MUC17 rs10229731 A/C genotype (OR = 0.33, 95%CI: 0.12-0.95), rs73168398 G/A genotype (OR = 0.26, 95%CI: 0.07-0.98), MUC6 rs10902268 G/A genotype (OR = 0.40, 95%CI: 0.17-0.95) at lower frequencies than controls. The frequencies of MUC2 rs41532344 T allele (OR = 2.55, 95%CI: 1.06-6.13), MUC4 rs712005 G allele (OR = 2.51, 95%CI: 1.20-5.22), MUC5B rs2037089 C allele (OR = 3.54, 95%CI: 1.14-11.01) and MUC5AC rs28415193 G allele (OR = 1.77, 95%CI: 1.02-3.07) were higher than the control group. MUC6 rs10902268 A allele (OR = 0.004, 95%CI: 0.00-0.27), rs61869016 C allele (OR = 0.07, 95%CI: 0.01-0.63) at lower frequencies than controls.

CONCLUSIONS

Polymorphisms in the mucin gene were linked to the formation of gallbladder stones. The MUC4 rs712005 G allele, MUC5B rs2037089 C allele, MUC2 rs41532344 T allele and MUC5AC rs28415193 G allele were found to predispose individuals to the development of the disease. MUC6 rs10902268 A allele and rs61869016 C allele were identified as protective factors. Meanwhile, MUC2 rs2856111 CT genotype was found to predispose individuals to the development of the disease. MUC17 rs10229731 AC genotype, rs73168398 GA genotype and MUC6 rs10902268 GA genotype were identified as protective factors.

Gut microbiota and eating behaviour in circadian syndrome

Eating behaviour and circadian rhythms are closely related. The type, timing, and quantity of food consumed, and host circadian rhythms, directly influence the intestinal microbiota, which in turn impacts host circadian rhythms and regulates food intake beyond homeostatic eating. This Opinion discusses the impact of food intake and circadian disruptions induced by an obesogenic environment on gut-brain axis signalling. We also explore potential mechanisms underlying the effects of altered gut microbiota on food intake behaviour and circadian rhythmicity. Understanding the crosstalk between gut microbiota, circadian rhythms, and unhealthy eating behaviour is crucial to addressing the obesity epidemic, which remains one of the biggest societal challenges of our time.

Association between circadian syndrome and gallstones in US adult: a cross-sectional study of NHANES 2017-2020

BACKGROUND

The circadian syndrome is linked with chronic diseases such as stroke, kidney stones, and overactive bladder. However, the relationship between circadian syndrome and gallstones is poorly understood. In this study, we aim to investigate whether circadian syndrome is associated with gallstones in a population-based study.

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES) database spanning from 2017 to 2020, a cross-sectional study with 2913 participants was performed to assess the relationship between circadian syndrome and gallstones. Univariate and two adjusted multivariate regression models were used to examine the connection between circadian syndrome and gallstones incidence. Smoothed curve fitting using the generalized additive model (GAM) was used to describe the nonlinear relationship. Subgroup analyses were also performed to investigate potential variations in the relationship between circadian syndrome and the risk of developing gallstones.

RESULT

The findings indicated a positive association of circadian syndrome with gallstones, with model 2 showing a 117% increase in risk (OR = 2.17, 95% CI 1.43, 3.29). In model 3, the incidence of gallstones increased by 76% (OR = 1.76, 95% CI 0.91, 3.43). However, there was no significant relationship between the number of circadian syndrome components and the risk of gallstones. Smooth curve fitting based on the GAM further demonstrated linear relationships between CircS and the risk of gallstones. Subgroup analyses further demonstrated statistically significant associations between circadian syndrome and the prevalence of gallstones among individuals who were non-smokers.

CONCLUSION

Circadian syndrome was positively associated with the prevalence of gallstones, particularly among non-smoking participants.

Association between sleep and gallstone disease in United States adults: A cross-sectional study

BACKGROUND

Both gallstone disease and sleep disorders are important public health problems. Few studies to date have investigated the associations between sleep and gallstone disease in humans. This study aimed to assess whether sleep factors (sleep time, sleep amounts, trouble sleeping) were associated with gallstone disease in the United States adults.

METHODS

This was a population-based cross-sectional study of US adults, which included data of participants aged over 20 years from the National Health and Nutrition Examination Survey (NHANES) gathered between 2017 and March 2020. The assessment of gallstone disease and sleep factors was based on self-reported data. We used sample-weighted logistic regression and restricted cubic spline models to explore the associations between sleep factors and gallstone disease. Subgroup analyses were conducted to assess the interaction between trouble sleeping and interacting factors.

RESULTS

The prevalence of gallstone disease was 11% among the 9,210 adult participants. Going to bed late on weekdays (OR, 1.41; 95% CI, 1.15 to 1.74) and weekends (OR, 1.43; 95% CI, 1.14 to 1.78), and short sleep duration on weekdays (OR, 1.29; 95% CI, 1.00 to 1.68) were factors associated with increased risk of gallstone disease, and we detected dose-response associations with the restricted cubic spline model (RCS) models, after adjusting for confounders. Presenting trouble sleeping was associated with increased risk of gallstone disease (OR, 1.52; 95% CI, 1.03 to 2.23) and the association was influenced by the presence of thyroid disease (P for interaction = 0.037).

CONCLUSIONS

Our study results indicate that going to bed late, short sleep duration, and trouble sleeping were associated with increased risk of gallstone disease in a nationally representative sample of adults in the US.

Essential Fatty Acids along the Women’s Life Cycle and Promotion of a Well-balanced Metabolism

Abstract:

Linoleic acid (ω-6 LA) and α-linolenic acid (ω-3 ALA) are essential fatty acids (EFA) for human beings. They must be consumed through diet and then extensively metabolized, a process that plays a fundamental role in health and eventually in disease prevention. Given the numerous changes depending on age and sex, EFA metabolic adaptations require further investigations along the women’s life cycle, from onset to decline of the reproductive age. Thus, this review explains women’s life cycle stages and their involvement in diet intake, digestion and absorption, the role of microbiota, metabolism, bioavailability, and EFA fate and major metabolites. This knowledge is crucial to promoting lipid homeostasis according to female physiology through well-directed health strategies. Concerning this, the promotion of breastfeeding, nutrition, and physical activity is cardinal to counteract ALA deficiency, LA/ALA imbalance, and the release of unhealthy derivatives. These perturbations arise after menopause that compromise both lipogenic and lipolytic pathways. The close interplay of diet, age, female organism, and microbiota also plays a central role in regulating lipid metabolism. Consequently, future studies are encouraged to propose efficient interventions for each stage of women's cycle. In this sense, plant-derived foods and products are promising to be included in women’s nutrition to improve EFA metabolism.

The association between triglyceride-glucose index and gallstones: NHANES 2017-2020

Objects

It remains unclear whether the triglyceride-glucose (TyG) index has correlations with gallstones. This study aimed to investigate the association between TyG index and gallstones.

Methods

Data was obtained from the 2017-2020 National Health and Nutrition Examination Survey (NHANES). Participants who provided complete data about TyG index and gallstones were included in the analysis. Multivariable regression analysis and subgroup analysis were preformed to estimate the relationship between TyG index and gallstones. Restricted cubic splines (RSC) was employed to calculate the cut off value.

Results

The TyG index was independently associated with gallstones and demonstrates a clear positive correlation (OR = 1.10; 95% CI: 1.01-1.21; p = 0.033). The threshold value is 8.98, showing a positive correlation between TyG index and gallstones when the TyG index is less than 8.98 (Log likelihood ratio P < 0.001). Subgroup analysis indicates that the correlation between TyG and gallstones is mainly observed in individuals with obesity, females, younger individuals, and those with normal blood sugar levels, with these subgroups all acting as mediators between TyG and gallstones.

Conclusions

Higher TyG index was linked to a higher chance of developing gallstones. Managing insulin resistance (IR) could help reduce the risk of gallstones since the TyG index is an indicator of IR.

Day and Night Reversed Feeding Aggravates High-Fat Diet-Induced Abnormalities in Intestinal Flora and Lipid Metabolism in Adipose Tissue of Mice

BACKGROUND

The incongruity between dietary patterns and the circadian clock poses an elevated risk for metabolic health issues, particularly obesity and associated metabolic disorders. The intestinal microflora engages in regulating various physiological functions of the host through its metabolites.

OBJECTIVES

This study aimed to investigate the impact of reversed feeding schedules during the day and night on intestinal flora and lipid metabolism in high-fat diet-induced obese mice.

METHODS

Mice aged 8-10 wk were subjected to either daytime or nighttime feeding and were administered a control or high-fat diet for 18 wk. At the end of the experiment, various assessments were conducted, including analysis of serum biochemic indices, histologic examination, evaluation of gene and protein expression in adipose tissue, and scrutiny of changes in intestinal microbial composition.

RESULTS

The results showed that day-night reversed feeding caused an increase in fasting blood glucose and exacerbated the high-fat diet-induced weight gain and lipid abnormalities. The mRNA expression levels of Leptin and Dgat1 were increased by day-night reversed feeding, which also reduced the expression level of adiponectin under the high-fat diet. Additionally, there was a significant increase in the protein concentrations of PPARγ, SREBP1c, and CD36. Inverted feeding schedules led to a reduction in intestinal microbial diversity, an increase in the abundance of inflammation-related bacteria, such as Coriobacteriaceae_UCG-002, and a suppression of beneficial bacteria, including Akkermansia, Candidatus_Saccharimonas, Anaeroplasma, Bifidobacterium, Carnobacterium, and Odoribacter. Acinetobacter exhibited a significant negative correlation with Leptin and Fasn, suggesting potential involvement in the regulation of lipid metabolism.

CONCLUSIONS

The results elucidated the abnormalities of lipid metabolism and intestinal flora caused by day-night reversed feeding, which exacerbates the adverse effects of a high-fat diet on lipid metabolism and intestinal microflora. This reversal in feeding patterns may disrupt both intestinal and lipid metabolism homeostasis by altering the composition and abundance of intestinal microflora in mice.

Bifidobacterium longumBL-19 inhibits oxidative stress and inflammatory damage in the liver of mice with NAFLD by regulating the production of butyrate in the intestine

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease, but there is currently no effective treatment method. Probiotics have been used as an adjunct therapy for NAFLD, but the mechanism is not clear. This study used Bifidobacterium longum BL19 (BL-19) to treat the NAFLD mice induced by a high-fat diet, and explored the treatment mechanism through gut microbiota and serum metabolomics techniques. We found that BL-19 effectively prevented rapid weight gain in NAFLD mice and reduced their overall food and energy intake, decreased liver inflammatory factors expressions, and increased the bile acid synthetase enzyme CYP7A1 and superoxide dismutase. After BL-19 treatment, the abundances of butyric acid bacteria (Oscillospira and Coprococcus) in the feces of mice increased significantly, and the concentration of butyric acid also increased significantly. We believe that BL-19 promotes the production of butyrate in the intestines, which in turn regulates the activity of CYP7A1 in the liver and bile acid synthesis, ultimately treating liver inflammation and lipid accumulation in NAFLD mice. Serum metabolomics results indicated that BL-19 affected multiple pathways related to inflammation and lipid metabolism in NAFLD mice. These findings suggest that BL-19 shows promise as an adjunct therapy for NAFLD, as it can significantly improve oxidative stress, reduce inflammation in the liver, and decrease lipid accumulation.

Depressive symptoms were associated with an elevated prevalence of gallstones among adults in the United States: A cross-sectional analysis of NHANES 2017-2020

Background

 Gallstone disease is one of the most common gastrointestinal disorders. Despite extensive research exploring the risk factors associated with gallstones, the association between depressive symptoms and gallstones remains inadequately understood. This study aimed to assess the association between depressive symptoms and the prevalence of gallstones among adults in the United States.

Methods

In this study, a cross-sectional design utilized data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2017 to 2020. The assessment of depressive symptoms was conducted through the utilization of the Patient Health Questionnaire-9 (PHQ-9), which assigns total scores ranging from 0 to 27. Participants with PHQ-9 scores equal to or exceeding 10 were categorized as having clinically relevant depressive symptoms. Multivariable adjusted logistic regression and subgroup analysis were used to assess the association between depressive symptoms and gallstone prevalence.

Results

A total of 7,797 participants aged 20 years or older were enrolled in this study, of whom 835 had a self-reported history of gallstones. After multiple adjustments, each one-point increase in PHQ-9 scores was associated with a 5 % increase in the risk of gallstones (odds ratio [OR], 1.05; 95 % confidence interval [CI], 1.03, 1.07, P < 0.001). Compared to individuals with PHQ-9 scores < 10, participants with PHQ-9 total scores ≥ 10 exhibited a 79 % higher risk of gallstones (OR = 1.79, 95 % CI: 1.43, 2.23, P < 0.001).

Conclusion

Depressive symptoms were associated with an elevated prevalence of gallstones. However, it is important to note that further validation through prospective cohort studies is warranted to confirm this finding.

The effects of time-restricted eating and Ramadan fasting on gut microbiota composition: a systematic review of human and animal studies

CONTEXT

It is well known that the microbiome undergoes cyclical diurnal rhythms. It has thus been hypothesized that meal timing may affect gut microbial composition, function, and host health.

OBJECTIVE

This review aims to examine the effects of time-restricted eating (TRE) and Ramadan fasting (RF) on the composition of the gut microbiota in animal and human studies. The associations between composition of microbiota and host metabolic parameters are also examined.

DATA SOURCES

A search was performed on the PubMed, Cochrane, Scopus, and Web of Science databases up to December 31, 2022. The search strategy was performed using the Medical Subject Heading (MeSH) terms "intermittent fasting" and "gastrointestinal microbiome" and the key words "Ramadan fasting" and "microbes."

DATA EXTRACTION

Seven human studies (4 TRE and 3 RF) and 9 animal studies (7 TRE, 2 RF-like) were retrieved.

DATA ANALYSIS

TRE and RF in human studies lead to an increase in gut microbial community alpha-diversity. In animal studies (both TRE and RF-like), fasting is not associated with improved alpha-diversity, but enhancement of microbial fluctuation is observed, compared with high-fat diet ad libitum groups. Within Firmicutes and Bacteroidetes phyla, no specific direction of changes resulting from fasting are observed in both animals and human. After TRE or RF, a greater abundance of the Faecalibacterium genus is observed in human studies; changes in Lactobacillus abundance are found in animal studies; and increases in Akkermansia are seen both in humans and in animals fed a feed-pellet diet. Only 2 human studies show a beneficial correlation between microbiota changes and host metabolic (HDL cholesterol) or anthropometric parameters (body mass index).

CONCLUSIONS

These findings support the importance of both regimens in improving the gut microbiota composition. However, based on results of animal studies, it can be suggested that diet remains the essential factor in forming the microbiota's environment.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021278918.

Resistance to Cholesterol Gallstone Disease: Hepatic Cholesterol Metabolism

Cholesterol gallstone disease (CGD) is one of the most common digestive diseases, and it is closely associated with hepatic cholesterol metabolism. Cholesterol gallstones may be caused by abnormal hepatic cholesterol metabolism, such as excessive cholesterol biosynthesis within the liver, interfering with the uptake or export of cholesterol in the liver, and abnormal hepatic cholesterol esterification. In this review, we begin with a brief overview of the clinical diagnosis and treatment of gallstone disease (GSD). Then, we briefly describe the major processes of hepatic cholesterol metabolism and summarize the key molecular expression changes of hepatic cholesterol metabolism in patients with gallstones. We review and analyze the recent advances in elucidating the relationships between these key molecules and CGD, and some targets significantly impacting on CGD via hepatic cholesterol metabolism are also listed. We also provide a significant discussion on the relationship between CGD and nonalcoholic fatty liver disease (NAFLD). Finally, the new discoveries of some therapeutic strategies associated with hepatic cholesterol metabolism to prevent and treat CGD are summarized.

Inhibition of PCSK9 prevents and alleviates cholesterol gallstones through PPARα-mediated CYP7A1 activation

BACKGROUND & AIMS

Dysregulated cholesterol metabolism is the major factor responsible for cholesterol gallstones (CGS). Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in cholesterol homeostasis and its inhibitors secure approval for treating various cholesterol metabolic disorders such as hypercholesterolemia and cardiovascular diseases, but its role in CGS remains unclear. Our study aims to clarify mechanisms by which PCSK9 promotes CGS formation and explore the application of the PCSK9 inhibitor, alirocumab, in preventing and treating CGS.

APPROACH & RESULTS

The expressions of PCSK9 were notably increased in CGS patients' serum, bile, and liver tissues compared to those without gallstones. Moreover, among CGS patients, hepatic PCSK9 was positively correlated with hepatic cholesterol and negatively correlated with hepatic bile acids (BAs), suggesting PCSK9 was involved in disrupted hepatic cholesterol metabolism related to CGS. Mechanistically, in vitro experiments demonstrated that inhibition of PCSK9 enhanced nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Finally, inhibition of PCSK9 prevented CGS formation and dissolved the existing stones in CGS mice by elevating the conversion of cholesterol into BAs through PPARα-mediated CYP7A1 activation. Additionally, serum PCSK9 level may function as a prognostic signature to evaluate the therapeutic efficacy of PCSK9 inhibitors.

CONCLUSIONS

Inhibition of PCSK9 exerts preventive and therapeutic effects on CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs, which highlights the potential of PCSK9 inhibition as a promising candidate for preventing and treating CGS in clinical applications.

IMPACT AND IMPLICATIONS

PCSK9 plays a pivotal role in cholesterol metabolism and its inhibitors are approved for clinical use in cardiovascular diseases. Our study observes inhibition of PCSK9 prevents and dissolves CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs. Mechanistically, PCSK9 inhibition enhanced the nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Our study sheds light on the new function and mechanism of PCSK9 in CGS, providing a novel preventive and therapeutic target with potential clinical applications.

Effect of Aerobic Exercise and Time-Restricted Feeding on Metabolic Markers and Circadian Rhythm in Mice Fed with the High-Fat Diet

SCOPE

Diet and exercise are significant players in obesity and metabolic diseases. Time-restricted feeding (tRF) has been shown to improve metabolic responses by regulating circadian clocks but whether it acts synergically with exercise remains unknown. It is hypothesized that forced exercise alone or combined with tRF alleviates obesity and its metabolic complications.

METHODS AND RESULTS

Male C57bl6 mice are fed with high-fat or a control diet for 12 weeks either ad libitum or tRF for 10 h during their active period. High-fat diet (HFD)-fed mice are divided into exercise (treadmill for 1 h at 12 m min-1 alternate days for 9 weeks and 16 m min-1 daily for the following 3 weeks) and non-exercise groups. tRF and tRF-Ex significantly decreased body weight, food intake, and plasma lipids, and improved glucose tolerance. However, exercise reduced only body weight and plasma lipids. tRF and tRF-Ex significantly downregulated Fasn, Hmgcr, and Srebp1c, while exercise only Hmgcr. HFD feeding disrupted clock genes, but exercise, tRF, and tRF-Ex coordinated the circadian clock genes Bmal1, Per2, and Rev-Erbα in the liver, adipose tissue, and skeletal muscles.

CONCLUSION

HFD feeding disrupted clock genes in the peripheral organs while exercise, tRF, and their combination restored clock genes and improved metabolic consequences induced by high-fat diet feeding.

The Role of the Circadian Rhythm in Dyslipidaemia and Vascular Inflammation Leading to Atherosclerosis

Cardiovascular diseases (CVD) are among the leading causes of death worldwide. Many lines of evidence suggest that the disturbances in circadian rhythm are responsible for the development of CVDs; however, circadian misalignment is not yet a treatable trait in clinical practice. The circadian rhythm is controlled by the central clock located in the suprachiasmatic nucleus and clock genes (molecular clock) located in all cells. Dyslipidaemia and vascular inflammation are two hallmarks of atherosclerosis and numerous experimental studies conclude that they are under direct influence by both central and molecular clocks. This review will summarise the results of experimental studies on lipid metabolism, vascular inflammation and circadian rhythm, and translate them into the pathophysiology of atherosclerosis and cardiovascular disease. We discuss the effect of time-respected administration of medications in cardiovascular medicine. We review the evidence on the effect of bright light and melatonin on cardiovascular health, lipid metabolism and vascular inflammation. Finally, we suggest an agenda for future research and recommend on clinical practice.

AQP3-mediated activation of the AMPK/SIRT1 signaling pathway curtails gallstone formation in mice by inhibiting inflammatory injury of gallbladder mucosal epithelial cells

BACKGROUND

Inflammatory injury of gallbladder mucosal epithelial cells affects the development of cholelithiasis, and aquaporin 3 (AQP3) is an important regulator of inflammatory response. This study reports a mechanistic insight into AQP3 regulating gallstone formation in cholelithiasis based on high-throughput sequencing.

METHODS

A mouse model of cholelithiasis was induced using a high-fat diet, and the gallbladder tissues were harvested for high-throughput sequencing to obtain differentially expressed genes. Primary mouse gallbladder mucosal epithelial cells were isolated and induced with Lipopolysaccharides (LPS) to mimic an in vitro inflammatory injury environment. Cell biological phenotypes were detected by TdT-mediated dUTP Nick-End Labeling (TUNEL) assay, flow cytometry, Cell Counting Kit-8 (CCK-8) assay, and Trypan blue staining. In addition, enzyme linked immunosorbent assay (ELISA) determined the production of inflammatory factors in mouse gallbladder mucosa.

RESULTS

Whole-transcriptome sequencing data analysis identified 489 up-regulated and 1007 down-regulated mRNAs. Bioinformatics analysis revealed that AQP3 was significantly down-regulated in mice with cholelithiasis. AQP3 might also confer an important role in LPS-induced gallbladder mucosal injury. Overexpression of AQP3 activated the AMPK (adenosine monophosphate-activated protein kinase) / SIRT1 (sirtuin-1) signaling pathway to reduce LPS-induced inflammatory injury of the gallbladder mucosa epithelium, thereby ameliorating gallbladder damage and repressing gallstone formation in mice.

CONCLUSION

Data from our study highlight the inhibitory role of AQP3 in gallbladder damage and gallstone formation in mice by reducing inflammatory injury of gallbladder mucosal epithelial cells, which is achieved through activation of the AMPK/SIRT1 signaling pathway.

Lipid metabolism around the body clocks

Lipids play important roles in energy metabolism along with diverse aspects of biological membrane structure, signaling and other functions. Perturbations of lipid metabolism are responsible for the development of various pathologies comprising metabolic syndrome, obesity, and type 2 diabetes. Accumulating evidence suggests that circadian oscillators, operative in most cells of our body, coordinate temporal aspects of lipid homeostasis. In this review we summarize current knowledge on the circadian regulation of lipid digestion, absorption, transportation, biosynthesis, catabolism, and storage. Specifically, we focus on the molecular interactions between functional clockwork and biosynthetic pathways of major lipid classes comprising cholesterol, fatty acids, triacylglycerols, glycerophospholipids, glycosphingolipids, and sphingomyelins. A growing body of epidemiological studies associate a socially imposed circadian misalignment common in modern society with growing incidence of metabolic disorders, however the disruption of lipid metabolism rhythms in this connection has only been recently revealed. Here, we highlight recent studies that unravel the mechanistic link between intracellular molecular clocks, lipid homeostasis and development of metabolic diseases based on animal models of clock disruption and on innovative translational studies in humans. We also discuss the perspectives of manipulating circadian oscillators as a potentially powerful approach for preventing and managing metabolic disorders in human patients.

Time Spent Outdoors and Associations with Sleep, Optimism, Happiness and Health before and during the COVID-19 Pandemic in Austria

Social restriction measures (SRM) implemented during the COVID-19 pandemic led to a reduction in time spent outdoors (TSO). The aim of this study was to describe TSO and evaluate its association with sleep outcomes, optimism, happiness and health-status before and during SRM. Two online surveys were conducted in 2017 (N = 1004) and 2020, during SRM (N = 1010), in samples representative of the age, sex and region of the Austrian population. Information on the duration of TSO, sleep, optimism, happiness and health-status was collected. Multivariable-adjusted logistic regression models were used to study the association of TSO with chronic insomnia, short sleep, late chronotype, optimism, happiness and self-rated health-status. The mean TSO was 3.6 h (SD: 2.18) in 2017 and 2.6 h (SD: 1.87) during times of SRM. Men and participants who were older, married or in a partnership and lived in a rural area reported longer TSO. Participants who spent less time outdoors were more likely to report short sleep or a late chronotype in both surveys and, in 2020, also chronic insomnia. Less TSO was associated with lower happiness and optimism levels and poor health-status. Our findings suggest that TSO may be a protective factor for sleep, mood and health, particularly during stressful and uncertain times.

Metabolic-Associated Fatty Liver Disease and Insulin Resistance: A Review of Complex Interlinks

Metabolic-associated fatty liver disease (MAFLD) has now surpassed alcohol excess as the most common cause of chronic liver disease globally, affecting one in four people. Given its prevalence, MAFLD is an important cause of cirrhosis, even though only a small proportion of patients with MAFLD ultimately progress to cirrhosis. MAFLD suffers as a clinical entity due to its insidious and often asymptomatic onset, lack of an accurate and reliable non-invasive diagnostic test, and lack of a bespoke therapy that has been designed and approved for use specifically in MAFLD. MAFLD sits at a crossroads between the gut and the periphery. The development of MAFLD (including activation of the inflammatory cascade) is influenced by gut-related factors that include the gut microbiota and intactness of the gut mucosal wall. The gut microbiota may interact directly with the liver parenchyma (through translocation via the portal vein), or indirectly through the release of metabolic metabolites that include secondary bile acids, trimethylamine, and short-chain fatty acids (such as propionate and acetate). In turn, the liver mediates the metabolic status of peripheral tissues (including insulin sensitivity) through a complex interplay of hepatokines, liver-secreted metabolites, and liver-derived micro RNAs. As such, the liver plays a key central role in influencing overall metabolic status. In this concise review, we provide an overview of the complex mechanisms whereby MAFLD influences the development of insulin resistance within the periphery, and gut-related factors impact on the development of MAFLD. We also discuss lifestyle strategies for optimising metabolic liver health.

Association between the prevalence rates of circadian syndrome and testosterone deficiency in US males: data from NHANES (2011-2016)

Objective

The objective of this study is to explore the association between the prevalence rates of circadian syndrome (CircS) and testosterone deficiency (TD).

Materials and methods

Cross-sectional analysis was conducted on the basis of the National Health and Nutrition Examination Survey 2011-2016. The target population was males aged ≥20 years old. A total of three multivariable logistic regression models were built to elucidate the association between the prevalence rates of CircS and TD. Interactive and stratified analyses were employed to explore whether some variables can modify the above association. Sensitivity analyses were also conducted to verify the stability of the results with extreme values removed.

Results

A total of 3,436 eligible participants were involved. Multivariable logistic regression in the fully adjusted model suggested the CircS group had a significantly higher prevalence rate of TD compared with the non-CircS group (OR = 2.284, 95%CI 1.569 to 3.323). No significant correlation between the number of CircS components and TD was observed in any of the three models. The interactive and stratified analyses showed the association was more obvious in the population with moderate or vigorous activities. The results were robust after extreme data were excluded.

Conclusion

There is a positive association between the prevalence rates of CircS and TD in US men. The association becomes more obvious owing to moderate or vigorous activities.

1,3-dichloro-2-propanol caused lipid droplets accumulation by suppressing neutral lipases via BMAL1 in hepatocytes

Circadian rhythm regulates body physiology and metabolism to adapt to the external environment. 1,3-dichloro-2-propanol (1,3-DCP) is a food pollutant formed during food processing. Our study explored whether toxicity of 1,3-DCP was related to circadian rhythm. We discovered that 1,3-DCP caused lipid droplets (LDs) accumulation via suppression of neutral lipases ATGL and HSL in mice liver and HepG2 cells. Meanwhile, 1,3-DCP caused rhythmic disruption of key circadian rhythm molecules BMAL1/CLOCK at protein and mRNA levels in HepG2 cells. Studies have shown that BMAL1 regulates PPARα by binding to the promoter E-box. 1,3-DCP inhibited PPARα expression. A PPARα activator WY-14643 up-regulated ATGL and HSL expression. BMAL1 overexpression up-regulated PPARα, ATGL and HSL expression. WY-14643 or BMAL1 overexpression attenuated 1,3-DCP-caused LDs accumulation in HepG2 cells. The results revealed that 1,3-DCP caused LDs accumulation by neutral lipases suppression via inhibiting key circadian rhythm protein BMAL1, indicating that circadian rhythm can be related to the regulation of LDs accumulation caused by 1,3-DCP.

Chronic circadian desynchronization of feeding-fasting rhythm generates alterations in daily glycemia, LDL cholesterolemia and microbiota composition in mice

Introduction

The circadian system synchronizes behavior and physiology to the 24-h light- dark (LD) cycle. Timing of food intake and fasting periods provide strong signals for peripheral circadian clocks regulating nutrient assimilation, glucose, and lipid metabolism. Mice under 12 h light:12 h dark (LD) cycles exhibit behavioral activity and feeding during the dark period, while fasting occurs at rest during light. Disruption of energy metabolism, leading to an increase in body mass, was reported in experimental models of circadian desynchronization. In this work, the effects of chronic advances of the LD cycles (chronic jet-lag protocol, CJL) were studied on the daily homeostasis of energy metabolism and weight gain.

Methods

Male C57 mice were subjected to a CJL or LD schedule, measuring IPGTT, insulinemia, microbiome composition and lipidemia.

Results

Mice under CJL show behavioral desynchronization and feeding activity distributed similarly at the light and dark hours and, although feeding a similar daily amount of food as compared to controls, show an increase in weight gain. In addition, ad libitum glycemia rhythm was abolished in CJL-subjected mice, showing similar blood glucose values at light and dark. CJL also generated glucose intolerance at dark in an intraperitoneal glucose tolerance test (IPGTT), with increased insulin release at both light and dark periods. Low-density lipoprotein (LDL) cholesterolemia was increased under this condition, but no changes in HDL cholesterolemia were observed. Firmicutes/Bacteroidetes ratio was analyzed as a marker of circadian disruption of microbiota composition, showing opposite phases at the light and dark when comparing LD vs. CJL.

Discussion

Chronic misalignment of feeding/fasting rhythm leads to metabolic disturbances generating nocturnal hyperglycemia, glucose intolerance and hyperinsulinemia in a IPGTT, increased LDL cholesterolemia, and increased weight gain, underscoring the importance of the timing of food consumption with respect to the circadian system for metabolic health.

Prolonged Administration of Melatonin Ameliorates Liver Phenotypes in Cholestatic Murine Model

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is characterized by biliary senescence and hepatic fibrosis. Melatonin exerts its effects by interacting with Melatonin receptor 1 and 2 (MT1/MT2) melatonin receptors. Short-term (1 wk) melatonin treatment reduces a ductular reaction and liver fibrosis in bile duct-ligated rats by down-regulation of MT1 and clock genes, and in multidrug resistance gene 2 knockout (Mdr2-/-) mice by decreased miR200b-dependent angiogenesis. We aimed to evaluate the long-term effects of melatonin on liver phenotype that may be mediated by changes in MT1/clock genes/miR200b/maspin/glutathione-S transferase (GST) signaling.

METHODS

Male wild-type and Mdr2-/- mice had access to drinking water with/without melatonin for 3 months. Liver damage, biliary proliferation/senescence, liver fibrosis, peribiliary inflammation, and angiogenesis were measured by staining in liver sections, and by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay in liver samples. We confirmed a link between MT1/clock genes/miR200b/maspin/GST/angiogenesis signaling by Ingenuity Pathway Analysis software and measured liver phenotypes and the aforementioned signaling pathway in liver samples from the mouse groups, healthy controls, and PSC patients and immortalized human PSC cholangiocytes.

RESULTS

Chronic administration of melatonin to Mdr2-/- mice ameliorates liver phenotypes, which were associated with decreased MT1 and clock gene expression.

CONCLUSIONS

Melatonin improves liver histology and restores the circadian rhythm by interaction with MT1 through decreased angiogenesis and increased maspin/GST activity.

Per1/Per2 Disruption Reduces Testosterone Synthesis and Impairs Fertility in Elderly Male Mice

Circadian rhythm disorders caused by genetic or environmental factors lead to decreased male fertility but the mechanisms are poorly understood. The current study reports that the mechanism of Per1/Per2 Double knockout (DKO) reduced the reproductive capacity of elderly male mice. The sperm motility and spermatogenic capacity of male DKO mice were weak. Hormone-targeted metabolomics showed reduced plasma levels of free testosterone in DKO male mice compared with WT male mice. Transcriptomic analysis of testicular tissue showed the down-regulation of testosterone synthesis-related enzymes (Cyp11a1, Cyp17a1, Hsd17b3, Hsd3b1, and Star) in the steroid hormone synthesis pathway. Spermatogenesis genes, Tubd1 and Pafah1b were down-regulated, influencing tubulin dynamics and leading to impaired motility. Seleno-compound metabolic loci, Scly and Sephs2, were up-regulated and Slc7a11 and Selenop were down-regulated. Western-blotting showed that steroid acute regulatory protein (StAR) and p-CREB, PKA and AC1 were reduced in testicular tissue of DKO mice compared to WT. Therefore, Per1/Per2 disruption reduced testosterone synthesis and sperm motility by affecting the PKA-StAR pathway, leading to decreased fertility.

Resistance is futile? Mucosal immune mechanisms in the context of microbial ecology and evolution

In the beginning it was simple: we injected a protein antigen and studied the immune responses against the purified protein. This elegant toolbox uncovered thousands of mechanisms via which immune cells are activated. However, when we consider immune responses against real infectious threats, this elegant simplification misses half of the story: the infectious agents are typically evolving orders-of-magnitude faster than we are. Nowhere is this more pronounced than in the mammalian large intestine. A bacterium representing only 0.1% of the human gut microbiota will have a population size of 109 clones, each actively replicating. Moreover, the evolutionary pressure from other microbes is at least as profound as direct effects of the immune system. Therefore, to really understand intestinal immune mechanisms, we need to understand both the host response and how rapid microbial evolution alters the apparent outcome of the response. In this review we use the examples of intestinal inflammation and secretory immunoglobulin A (SIgA) to highlight what is already known (Fig. 1). Further, we will explore how these interactions can inform immunotherapy and prophylaxis. This has major implications for how we design effective mucosal vaccines against increasingly drug-resistant bacterial pathogens Fig. 1 THE IMMUNE RESPONSE SHAPES THE FITNESS LANDSCAPE IN THE GASTRO-INTESTINAL TRACT.: The red arrows depict possible evolutionary paths of a novel colonizer along adaptive peaks in the intestinal fitness landscapes that change with the status of the host immune system. The flat surfaces represent the non-null fitness baselines (values x or y) at which a bacterium can establish at minimum carrying capacity. a In the healthy gut, metabolic competence, resistance to aggressions by competitors and predators, swift adaptation to rapid fluctuations as well as surviving acidic pH and the flow of the intestinal content, represent potent selective pressures and as many opportunities for bacteria to increase fitness by phenotypic or genetic variations. b When pathogens trigger acute inflammation, bacteria must adapt to iron starvation, killing by immune cells and antimicrobial peptides, and oxidative stress, while new metabolic opportunities emerge. c When high-affinity SIgA are produced against a bacterium, e.g., after oral vaccination, escape of SIgA by altering or losing surface epitopes becomes crucial for maximum fitness. However, escaping polyvalent SIgA responses after vaccination with "evolutionary trap" vaccines leads to evolutionary trade-offs: A fitness maximum is reached in the vaccinated host gut that represents a major disadvantage for transmission into naïve hosts (fitness diminished below x) (d).