Gut dysbiosis and body composition in cirrhosis

Causal relationship between gut microbiota and idiopathic pulmonary fibrosis: A two-sample Mendelian randomization

To explore the causal relationship between gut microbiota (GM) and Idiopathic pulmonary fibrosis (IPF), we performed a two-sample Mendelian randomization (MR). GM was used as an exposure factor, and instrumental variables were determined from the GWAS of 18,340 participants. GWAS of IPF (including 1028 IPF patients and 196,986 controls) from the FinnGen was used as the outcome factor. The primary analysis method is the inverse variance weighted (IVW) method, and sensitivity analysis was used to validate the reliability. Family Bacteroidaceae (OR = 1.917 95% CI = 1.083-3.393, P = .026), order Gastranaerophilales (OR = 1.441 95% CI = 1.019-2.036, P = .039), genus Senegalimassilia (OR = 2.28 95% CI = 1.174-4.427, P = .015), phylum Cyanobacteria (OR = 1.631 95% CI = 1.035-2.571, P = .035) were positively correlated with IPF. FamilyXIII(OR = 0.452 95% CI = 0.249-0.82, P = .009), order Selenomonadale (OR = 0.563 95% CI = 0.337-0.941, P = .029), genus Veillonella (OR = 0.546 95% CI = 0.304-0.982, P = .043) (OR = 0.717 95% CI = 0.527-0.976, P = .034), genus Ruminococcusgnavus (OR = 0.717 95% CI = 0.527-0.976, P = .034), genus Oscillibacter (OR = 0.571 95% CI = 0.405-0.806, P = .001) was negatively correlated with IPF. Sensitivity analysis showed no evidence of pleiotropy or heterogeneity (P > .05). The results of MR demonstrated a causal relationship between GM and IPF. Further studies are needed to investigate the intrinsic mechanisms of the GM in the pathogenesis of IPF.

Parameters of the Component Composition of the Body and Their Relationship with the Development of Ascites in Liver Cirrhosis

Aim: to evaluate the relationship of body composition components with the development of ascites in patients with liver cirrhosis.

Materials and methods. One hundred and ten patients (44 men and 66 women) with the established diagnosis of liver cirrhosis were treated at the University Clinical Hospital No 2 of the Sechenov University. The assessment of the component composition of the patients’ body was carried out using the ABC-01 “MEDASS” device  (“MEDASS”, Russia). Ascites diagnosis was performed using ultrasound examination of the abdominal cavity and retroperitoneal space.

Results. The values of body mass index (p < 0.001), fat mass (p = 0.002), active cell mass (p < 0.001), and phase angle (p < 0.001) were lower in patients with ascites than without it. Patients with a lower percentage of body fat mass had a more severe ascites severity and vice versa, and the proportion of fat mass was generally higher in women than in men (r = –0.290; p = 0.002). Patients with lower active cell mass had higher ascites severity (r = –0.380; p < 0.001). However, this indicator was lower in women than in men. Significant negative correlations were revealed between fat mass, active cell mass, phase angle (r = –0.395; p < 0.001) and the severity of ascites.

Conclusion. Our study confirms the importance of body composition parameters in the development of ascites in patients with cirrhosis of the liver. Insufficient amount of fat and muscle mass, as well as low values of the phase angle according to the results of bioimpedance can become predictors of the development of ascites. Evaluation of these components can be used in prognostic models to identify patients with an increased risk of ascites. Further research in this area will help to better understand the mechanisms of ascites development and develop effective methods of prevention and treatment of this complication in patients with liver cirrhosis.

Decreased Abundance of Genus Slackia in Individuals With Obesity and Colorectal Adenoma

Background and Aims

The increasing prevalence of obesity has significantly contributed to the global burden of colorectal cancer and the precancerous colorectal adenoma (CRA). Gut microbiota vary at each stage of colorectal carcinogenesis and participate in energy homeostasis. Elucidating gut microbiotal characteristics in obesity-related CRA may help prevent and treat colorectal tumors; however, this remains unclarified. Therefore, this study investigated the gut microbiota profile of patients with obesity-related CRA.

Methods

This hospital setting-based cross-sectional study included 113 participants (66 [without CRA control group] and 37 [with CRA group]; each group was divided into obese and nonobese groups) who underwent screening colonoscopy between June 2019 and January 2020. Gut microbiota were analyzed using 16S rRNA and polymerase chain reaction techniques and the data compared between the aforementioned groups.

Results

No between-group difference was observed in the diversity index; however, α diversity was the lowest in the obese CRA group. The CRA group had significantly higher and lower numbers of 26 and 17 genera, respectively. Genus Slackia was significantly lower in the obese CRA group than in the nonobese CRA group. Multivariate analysis of the quartiles according to genus Slackia relative abundance rates revealed that the first quartile was an independent risk factor for CRA (odds ratio, 3.57; 95% confidence interval 1.19-10.7). The proportion of equol reductase-positive participants was lowest in the obese CRA group (P = .04). Multivariate odds ratio for CRA was 5.46 (95% confidence interval 1.35-22.0) for genus Slackia and equol reductase-negative participants.

Conclusion

Decreased abundance of genus Slackia and absence of equol reductase potentially influence obesity-related CRA development.

Human metabolism and body composition: prospects for novel studies

CONTEXT

Most articles on gut microbiota argue the importance of body composition assessment in patients; however, body composition assessments are fragile (ie, with methodological limitations) in the most recent studies.

OBJECTIVE

To present two suggestions for further research using the human body composition assessment.

METHODS

The methods used in this study are based on a Pinto et al article published in Nutrition Reviews.

DATA EXTRACTION

On the basis of data.

obtained from the PubMed, SCOPUS, LILACS, and Web of Science databases, Pinto et al provided a current survey of intermittent fasting protocols and an understanding of the outcomes to date in terms of the profile of the intestinal microbiota in obese organisms.

DATA ANALYSIS

Of the 82 original articles identified from the databases, 35 were eliminated because of duplication and 32 were excluded for not meeting the inclusion criteria. Two additional articles found in a new search were added, yielding a total of 17 studies to be included in this review. Among the protocols, alternate-day fasting and time-restricted feeding were the most common, and they were shown to have different mechanisms of metabolic signaling. Time-restricted feeding influences body mass control and biochemical parameters by regulating the circadian system and improving satiety control systems by acting on leptin secretion. In contrast, alternate-day fasting leads to a reduction of ±75% of all energy consumption regardless of dietary composition, in addition to promoting hormonal adjustments that promote body mass control. Furthermore, both protocols could remodel the intestinal microbiota by changing the Firmicutes to Bacteroidetes ratio and increasing the abundance of strains such as Lactobacillus spp. and Akkermansia that have a protective effect on metabolism against the effects of body mass gain.

CONCLUSION

Changes in adipose tissue (eg, body mass loss, control, gain) should be interpreted via the sum of skinfolds in absolute values, waist perimeter, and patients' body proportionality, because fat is just a fraction of the adipocyte (lipid).

Causal effect between gut microbiota and pancreatic cancer: a two-sample Mendelian randomization study

BACKGROUND

Gut microbiota (GM) comprises a vast and diverse community of microorganisms, and recent studies have highlighted the crucial regulatory roles of various GM and their secreted metabolites in pancreatic cancer (PC). However, the causal relationship between GM and PC has yet to be confirmed.

METHODS

In the present study, we used two-sample Mendelian randomization (MR) analysis to investigate the causal effect between GM and PC, with genome-wide association study (GWAS) from MiBioGen consortium as an exposure factor and PC GWAS data from FinnGen as an outcome factor. Inverse variance weighted (IVW) was used as the primary method for this study.

RESULTS

At the genus level, we observed that Senegalimassilia (OR: 0.635, 95% CI: 0.403-0.998, P = 0.049) exhibited a protective effect against PC, while Odoribacter (OR:1.899, 95%CI:1.157-3.116, P = 0.011), Ruminiclostridium 9(OR:1.976,95%CI:1.128-3.461, P = 0.017), Ruminococcaceae (UCG011)(OR:1.433, 95%CI:1.072-1.916, P = 0.015), and Streptococcus(OR:1.712, 95%CI:1.071-1.736, P = 0.025) were identified as causative factors for PC. Additionally, sensitivity analysis, Cochran's Q test, the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO), and MR-Egger regression indicated no heterogeneity, horizontal pleiotropy, or reverse causality between GM and PC.

CONCLUSIONS

Our analysis establishes a causal effect between specific GM and PC, which may provide new insights into the potential pathogenic mechanisms of GM in PC and the assignment of effective therapeutic strategies.

Intestinal Microbiome in Dogs with Chronic Hepatobiliary Disease: Can We Talk about the Gut-Liver Axis?

The gut-liver axis represents a current topic in human medicine. Extensive research investigates the gut microbiome (GM) modifications in relation to various kinds of chronic hepatobiliary diseases (CHD), with many mechanisms and therapeutical implications recognized. Those aspects in veterinary medicine are still quite unexplored. The aim of the present study was to evaluate GM in dogs diagnosed with CD. Comparison among CHD dogs were made considering some clinical and biochemical variables (lipemia and alanine-aminotransferase activities), presence of cholestasis or endocrine disorders, diet). Sixty-five dogs were prospectively enrolled with clinical and hematobiochemical evaluation and 16S-RNA GM sequencing assessed. Dogs that received antibiotics and/or pre/pro/symbiotics administration were excluded. Deeper GM alteration was observed between dogs with or without ultrasonographic and biochemical cholestatic CHD. Cholestasis was associated with a decrease in several bacterial taxa, including Clostridium hiranonis, Fusobacterium, Megamonas, Ruminococcus faecis, Turicibacter, and higher levels of Escherichia/Shigella and Serratia. Thus, the alteration in bile flow and composition, typical of cholestasis, may directly affect the local intestinal microbial environment. For the management of dogs with CHD and especially cholestatic CHD, clinicians should be aware that gut-liver interaction may lead to dysbiosis.

Sarcopenia in cirrhosis: Prospects for therapy targeted to gut microbiota

Decreased muscle mass and function, also known as sarcopenia, is common in patients with cirrhosis and is associated with a poor prognosis. Although the pathogenesis of this disorder has not been fully elucidated, a disordered gut-muscle axis probably plays an important role. Decreased barrier function of the gut and liver, gut dysbiosis, and small intestinal bacterial overgrowth (SIBO) can lead to increased blood levels of ammonia, lipopolysaccharides, pro-inflammatory mediators, and myostatin. These factors have complex negative effects on muscle mass and function. Drug interventions that target the gut microbiota (long-term use of rifaximin, lactulose, lactitol, or probiotics) positively affect most links of the compromised gut-muscle axis in patients with cirrhosis by decreasing the levels of hyperammonemia, bacterial translocation, and systemic inflammation and correcting gut dysbiosis and SIBO. However, although these drugs are promising, they have not yet been investigated in randomized controlled trials specifically for the treatment and prevention of sarcopenia in patients with cirrhosis. No data exist on the effects of fecal transplantation on most links of gut-muscle axis in cirrhosis; however, the results of animal experimental studies are promising.

Accounting Gut Microbiota as the Mediator of Beneficial Effects of Dietary (Poly)phenols on Skeletal Muscle in Aging

Sarcopenia, the age-related loss of muscle mass and function increasing the risk of disability and adverse outcomes in older people, is substantially influenced by dietary habits. Several studies from animal models of aging and muscle wasting indicate that the intake of specific polyphenol compounds can be associated with myoprotective effects, and improvements in muscle strength and performance. Such findings have also been confirmed in a smaller number of human studies. However, in the gut lumen, dietary polyphenols undergo extensive biotransformation by gut microbiota into a wide range of bioactive compounds, which substantially contribute to bioactivity on skeletal muscle. Thus, the beneficial effects of polyphenols may consistently vary across individuals, depending on the composition and metabolic functionality of gut bacterial communities. The understanding of such variability has recently been improved. For example, resveratrol and urolithin interaction with the microbiota can produce different biological effects according to the microbiota metabotype. In older individuals, the gut microbiota is frequently characterized by dysbiosis, overrepresentation of opportunistic pathogens, and increased inter-individual variability, which may contribute to increasing the variability of biological actions of phenolic compounds at the skeletal muscle level. These interactions should be taken into great consideration for designing effective nutritional strategies to counteract sarcopenia.