Microbiota, Obesity and NAFLD

Dietary inflammatory impact on NAFLD development in obese vs. lean individuals: an analysis based on NHANES 2003-2018

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), often linked with obesity, can also affect individuals with normal weight, a condition known as "lean NAFLD", imposing comparable burdens and adverse effects. However, the impact of diet on lean NAFLD remains underexplored. The objective of this study is to investigate the correlation between the Dietary Inflammatory Index (DII) and NAFLD among Americans, stratified by waist-to-height ratio (WHtR) and body mass index (BMI).

METHODS

Five thousand one hundred fifty-two participants from the National Health and Nutrition Examination Survey (NHANES) 2003-2018 were comprised in the final analysis. NAFLD and advanced liver fibrosis were diagnosed by serological markers. Lean and abdominal lean individuals were identified using BMI and WHtR, separately. DII was determined by assigning scores to 28 distinct food parameters based on their inflammatory potential, obtained from the NAHNES website. Differences across DII quartiles were evaluated using the Kruskal-Wallis H Test, Chi-Square Test along with One-Way ANOVA. The correlation between DII and NAFLD was determined by multiple regression models and subgroup analyses.

RESULTS

Among the 5152 subjects, 2503 were diagnosed with NAFLD, including 86 cases of lean NAFLD and 8 cases of abdominal lean NAFLD. DII was positively linked with NAFLD (Odds Ratio (OR) = 1.81 [1.48-2.21], P < 0.001) and advanced liver fibrosis (OR = 1.46 [1.02-2.07], P = 0.037). Further analysis revealed that this association was primarily observed in obese or abdominal obese participants (In BMI ≥ 25.00 kg/m^2, OR = 1.56 [1.23-1.98], P < 0.001. In WHtR> 0.50, OR = 1.48 [1.23-1.79], P < 0.001.), rather than their lean counterparts. Subgroup analyses indicated that female individuals, without a diagnosis of hypertension or diabetes appeared to be more sensitive to the rise in DII.

CONCLUSIONS

Our data demonstrated a significant positive correlation between DII and NAFLD in the general population. However, the impact of a pro-inflammatory diet was less prominent in lean individuals compared to obese ones.

Short-chain fatty acids in nonalcoholic fatty liver disease: New prospects for short-chain fatty acids as therapeutic targets

Nonalcoholic fatty liver disease (NAFLD) is a stress-induced liver injury related to heredity, environmental exposure and the gut microbiome metabolism. Short-chain fatty acids (SCFAs), the metabolites of gut microbiota (GM), participate in the regulation of hepatic steatosis and inflammation through the gut-liver axis, which play an important role in the alleviation of NAFLD. However, little progress has been made in systematically elucidating the mechanism of how SCFAs improve NAFLD, especially the epigenetic mechanisms and the potential therapeutic application as clinical treatment for NAFLD. Herein, we adopted PubMed and Medline to search relevant keywords such as 'SCFAs', 'NAFLD', 'gut microbiota', 'Epigenetic', 'diet', and 'prebiotic effect' to review the latest research on SCFAs in NAFLD up to November 2023. In this review, firstly, we specifically discussed the production and function of SCFAs, as well as their crosstalk coordination in the gut liver axis. Secondly, we provided an updated summary and intensive discussion of how SCFAs affect hepatic steatosis to alleviate NAFLD from the perspective of genetic and epigenetic. Thirdly, we paid attention to the pharmacological and physiological characteristics of SCFAs, and proposed a promising future direction to adopt SCFAs alone or in combination with prebiotics and related clinical drugs to prevent and treat NAFLD. Together, this review aimed to elucidate the function of SCFAs and provide new insights to the prospects of SCFAs as a therapeutic target for NAFLD.

Bacteria-based drug delivery for treating non-oncological diseases

Bacteria inhabit all over the human body, especially the skin, gastrointestinal tract, respiratory tract, urogenital tract, as well as specific lesion sites, such as wound and tumor. By leveraging their distinctive attributes including rapid proliferation, inherent abilities to colonize various biointerfaces in vivo and produce diverse biomolecules, and the flexibility to be functionalized via genetic engineering or surface modification, bacteria have been widely developed as living therapeutic agents, showing promising potential to make a great impact on the exploration of advanced drug delivery systems. In this review, we present an overview of bacteria-based drug delivery and its applications in treating non-oncological diseases. We systematically summarize the physiological positions where living bacterial therapeutic agents can be delivered to, including the skin, gastrointestinal tract, respiratory tract, and female genital tract. We discuss the success of using bacteria-based drug delivery systems in the treatment of diseases that occur in specific locations, such as skin wound healing/infection, inflammatory bowel disease, respiratory diseases, and vaginitis. We also discuss the advantages as well as the limitations of these living therapeutics and bacteria-based drug delivery, highlighting the key points that need to be considered for further translation. This review article may provide unique insights for designing next-generation bacteria-based therapeutics and developing advanced drug delivery systems.

The Correlation Between Serum Copper and Non-alcoholic Fatty Liver Disease in American Adults: an Analysis Based on NHANES 2011 to 2016

Copper functions as an essential micronutrient influencing diverse metabolic processes in mammals, encompassing oxidative stress responses, lipid metabolism, and participation in enzymatic reactions. However, the impact of serum copper on non-alcoholic fatty liver disease (NAFLD) remains controversial. Our aim was to explore the precise correlation between serum copper and NAFLD in a large-scale population-based study. A total of 1377 participants from the National Health and Nutrition Examination Survey (NHANES) 2011-2016 were included in our study. The diagnosis of NAFLD and its progress to advanced liver fibrosis were based on serological indexes. One-way ANOVA, Kruskal-Wallis H test, and Chi-square test were used to access variations between quartiles groups of serum copper. We conducted multivariate-adjusted logistic regression models and subgroup analyses to investigate the association between serum copper and NAFLD, along with several metabolic diseases. Among the 1377 participants, 661 were diagnosed with NAFLD, and 141 of whom were classified into advanced liver fibrosis. Higher serum copper levels (≥ 21.00 μmol/L) were associated with an increased incidence of NAFLD (odds ratio (OR) = 2.07 (1.38-3.10), p < 0.001), as well as advanced liver fibrosis (OR = 2.40 (1.17-5.19), p = 0.025). Moreover, serum copper exhibited a positive correlation with hypertension, overweight, and abdominal obesity, all of which have been identified as risk factors of NAFLD. Additionally, female participants, under the age of 60, and with a higher body mass index (BMI) (> 24.9 kg/m2) emerged as the most vulnerable subgroup concerning the relationship between serum copper and NAFLD. In the U.S. population, a notable association has been identified, linking elevated serum copper to an increased susceptibility for both the onset and progression of NAFLD, along with several metabolic disorders associated with NAFLD. The adverse effects of excess copper warrant attention in the context of public health considerations.

The promotion of fatty acid β-oxidation by hesperidin via activating SIRT1/PGC1α to improve NAFLD induced by a high-fat diet

Reducing fat deposits in hepatocytes is a direct treatment for nonalcoholic fatty liver disease (NAFLD) and the fatty acid metabolic processes mediated by fatty acid β-oxidation are important for the prevention of NAFLD. In this study, we established high-fat-diet models in vitro and in vivo to investigate the mechanism by which hesperidin (HDN) prevents NAFLD by modulating fatty acid β oxidation. Based on LC-MS screening of differential metabolites, many metabolites involved in phospholipid and lipid metabolism were found to be significantly altered and closely associated with fatty acid β-oxidation. The results from COIP experiments indicated that HDN increased the deacetylation of PGC1α by SIRT1. In addition, the results of CETSA and molecular docking experiments suggest that HDN targeting of SIRT1 plays an important role in their stable binding. Meanwhile, it was found that HDN reduced fatty acid uptake and synthesis and promoted the expression of SIRT1/PGC1α and fatty acid β-oxidation, and the latter process was inhibited after transfection to knockdown SIRT1. The results suggest that HDN improves NAFLD by promoting fatty acid β-oxidation through activating SIRT1/PGC1α. Thus, the findings indicate that HDN may be a potential drug for the treatment of NAFLD.

From Gut to Glucose: A Comprehensive Review on Functional Foods and Dietary Interventions for Diabetes Management

BACKGROUND

In the realm of diabetes research, considerable attention has been directed toward elucidating the intricate interplay between the gastrointestinal tract and glucose regulation. The gastrointestinal tract, once exclusively considered for its role in digestion and nutrient assimilation, is presently acknowledged as a multifaceted ecosystem with regulatory supremacy over metabolic homeostasis and glucose metabolism. Recent studies indicate that alterations in the composition and functionality of the gut microbiota could potentially influence the regulation of glucose levels and glucose homeostasis in the body. Dysbiosis, characterized by perturbations in the equilibrium of gut microbial constituents, has been irrevocably linked to an augmented risk of diabetes mellitus (DM). Moreover, research has revealed the potential influence of the gut microbiota on important factors, like inflammation and insulin sensitivity, which are key contributors to the onset and progression of diabetes. The key protagonists implicated in the regulation of glucose encompass the gut bacteria, gut barrier integrity, and the gut-brain axis. A viable approach to enhance glycemic control while concurrently mitigating the burden of comorbidities associated with diabetes resides in the strategic manipulation of the gut environment through adapted dietary practices.

OBJECTIVE

This review aimed to provide a deep understanding of the complex relationship between gut health, glucose metabolism, and diabetes treatment.

CONCLUSION

This study has presented an exhaustive overview of dietary therapies and functional foods that have undergone extensive research to explore their potential advantages in the management of diabetes. It looks into the role of gut health in glucose regulation, discusses the impact of different dietary elements on the course of diabetes, and evaluates how well functional foods can help with glycemic control. Furthermore, it investigates the mechanistic aspects of these therapies, including their influence on insulin sensitivity, β-cell activity, and inflammation. It deliberates on the limitations and potential prospects associated with integrating functional foods into personalized approaches to diabetes care.

Advances in the pharmacological effects and molecular mechanisms of emodin in the treatment of metabolic diseases

Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. are traditional Chinese medicines that have been used for thousands of years. They are formulated into various preparations and are widely used. Emodin is a traditional Chinese medicine monomer and the main active ingredient in Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. Modern research shows that it has a variety of pharmacological effects, including promoting lipid and glucose metabolism, osteogenesis, and anti-inflammatory and anti-autophagy effects. Research on the toxicity and pharmacokinetics of emodin can promote its clinical application. This review aims to provide a basis for further development and clinical research of emodin in the treatment of metabolic diseases. We performed a comprehensive summary of the pharmacology and molecular mechanisms of emodin in treating metabolic diseases by searching databases such as Web of Science, PubMed, ScienceDirect, and CNKI up to 2023. In addition, this review also analyzes the toxicity and pharmacokinetics of emodin. The results show that emodin mainly regulates AMPK, PPAR, and inflammation-related signaling pathways, and has a good therapeutic effect on obesity, hyperlipidemia, non-alcoholic fatty liver disease, diabetes and its complications, and osteoporosis. In addition, controlling toxic factors and improving bioavailability are of great significance for its clinical application.

Prevalence and Determinants of Undiagnosed Liver Steatosis and Fibrosis in a Nationally Representative Sample of US Adults

Background Chronic liver diseases account for approximately 1.9 million deaths globally every year and negatively affect health-related quality of life. Early detection of liver disease may enable timely treatment, potentially improving patient outcomes. This study aimed to determine the prevalence and determinants of liver steatosis and fibrosis in US adults with no previously diagnosed liver condition. Methods We conducted an observational, nationally representative, cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) conducted from January 2017 to March 2020. Study participants were 7,391 adults aged 21 and older with no history of diagnosed liver disorders who underwent vibration-controlled transient elastography (VCTE) to determine liver steatosis and fibrosis. Controlled attenuation parameter (CAP) values between 248 and 267 dB/m were classified as mild steatosis, and those over 267 dB/m as advanced steatosis. Liver stiffness measurement (LSM) values between 7.65 and 13 kPa were classified as moderate/severe fibrosis, and those over 13 kPa as cirrhosis. Covariates included age, sex, race, body mass index (BMI), diabetes mellitus, kidney disease, smoking history, alcohol intake, alanine aminotransferase (ALT), aspartate aminotransferase (AST), physical activity, sedentary time, and sleep time. The associations of subject characteristics with liver CAP and LSM were evaluated using survey multivariable linear regression. Shapley Additive Explanations values determined the relative importance of each attribute in the model. The discriminative performance of classification models was assessed using the area under the receiver operating characteristic (AUROC) curve. Results The population prevalence of liver steatosis was 57.2% (10.2% mild; 47.0% advanced). The relative importance of covariates in predicting liver CAP was 63.1% for BMI, 10.7% for ALT, and less than 10% for the other covariates. The prevalence of significant fibrosis was 11.4% (8.3% moderate/severe fibrosis; 3.1% cirrhosis). The relative importance of covariates in predicting LSM was 67.3% for BMI and less than 10% for the other covariates. BMI alone demonstrated acceptable discriminative performance in classifying varying severities of steatosis and fibrosis (AUROC range 72%-78%) at cutoffs between 28 and 33 kg/m2. Conclusions Undiagnosed chronic liver disease based on VCTE findings is highly prevalent among US adults, particularly in obese individuals. Efforts to increase awareness about liver disease and to reconsider existing BMI thresholds for liver disease screening may be warranted.

Recent Advances in the Nanoshells Approach for Encapsulation of Single Probiotics

The intestine, often referred to as the "second brain" of the human body, houses a vast microbial community that plays a crucial role in maintaining the host's balance and directly impacting overall health. Probiotics, a type of beneficial microorganism, offer various health benefits when consumed. However, probiotics face challenges such as acidic conditions in the stomach, bile acids, enzymes, and other adverse factors before they can colonize the intestinal tissues. At present, pills, dry powder, encapsulation, chemically modified bacteria, and genetically engineered bacteria have emerged as the preferred method for the stable and targeted delivery of probiotics. In particular, the use of nanoshells on the surface of single probiotics has shown promise in regulating their growth and differentiation. These nanoshells can detach from the probiotics' surface upon reaching the intestine, facilitating direct contact between the probiotics and intestinal mucosa. In this perspective, we provide an overview of the current developments in the formation of nanoshells mediated by single probiotics. We also discuss the advantages and disadvantages of different nanocoating strategies and explore future trends in probiotic protection.

Quinoa Ameliorates Hepatic Steatosis, Oxidative Stress, Inflammation and Regulates the Gut Microbiota in Nonalcoholic Fatty Liver Disease Rats

A long-term high-fat diet causes hepatic steatosis, which further leads to oxidative stress and inflammation. In this study, we firstly investigated the regulation effects of different amounts of quinoa on hepatic steatosis, oxidative stress, and inflammation of rats fed a high-fat diet, then the gut microbiota was dynamically determined. Sprague-Dawley (SD, male) rats were randomized into four groups: normal controls (NC, fed standard chow), model groups (HF, fed a high-fat diet), low quinoa intake (HF + LQ), and high quinoa intake (HF + HQ) groups, which were supplemented with 9% and 27% quinoa in the high-fat feed (equivalent to 100 g/day and 300 g/day human intake, respectively). The results showed that quinoa intake significantly inhibited the hepatomegaly and splenomegaly, ameliorated hepatic steatosis pathologically; effectively rescued the decrease in the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) and the increase in malondialdehyde (MDA). The levels of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), transforming growth factor-β (TGF-β), and leptin in rats of two quinoa groups were close to those of the NC group. Besides, high quinoa intake significantly increased the relative abundance of Akkermansia, and low quinoa intake significantly increased the relative abundance of Blautia at the genus level. The relative abundances of Blautia and Dorea in rats in the HF + HQ group were lower than those in rats in the HF + LQ group. In addition, the relative abundances of Clostridium and Turicibacter of rats in the two quinoa intervention groups were lower than those of rats in the HF group after 12 weeks of intervention. In summary, quinoa exhibits a series of beneficial effects in the prevention of nonalcoholic fatty liver disease (NAFLD) and is suggested to be a component of a daily diet for the prevention of NAFLD.

Bacterial PncA improves diet-induced NAFLD in mice by enabling the transition from nicotinamide to nicotinic acid

Nicotinamide adenine dinucleotide (NAD⁺) is crucial for energy metabolism, oxidative stress, DNA damage repair, longevity regulation, and several signaling processes. To date, several NAD⁺ synthesis pathways have been found in microbiota and mammals, but the potential relationship between gut microbiota and their hosts in regulating NAD⁺ homeostasis remains largely unknown. Here, we showed that an analog of the first-line tuberculosis drug pyrazinamide, which is converted by nicotinamidase/pyrazinamidase (PncA) to its active form, affected NAD⁺ level in the intestines and liver of mice and disrupted the homeostasis of gut microbiota. Furthermore, by overexpressing modified PncA of Escherichia coli, NAD⁺ levels in mouse liver were significantly increased, and diet-induced non-alcoholic fatty liver disease (NAFLD) was ameliorated in mice. Overall, the PncA gene in microbiota plays an important role in regulating NAD⁺ synthesis in the host, thereby providing a potential target for modulating host NAD⁺ level.

Nutritional implications in the mechanistic link between the intestinal microbiome, renin-angiotensin system, and the development of obesity and metabolic syndrome

Obesity and metabolic disorders represent a significant global health problem and the gut microbiota plays an important role in modulating systemic homeostasis. Recent evidence shows that microbiota and its signaling pathways may affect the whole metabolism and the Renin-Angiotensin System (RAS), which in turn seems to modify microbiota. The present review aimed to investigate nutritional implications in the mechanistic link between the intestinal microbiome, renin-angiotensin system, and the development of obesity and metabolic syndrome components. A description of metabolic changes was obtained based on relevant scientific literature. The molecular and physiological mechanisms that impact the human microbiome were addressed, including the gut microbiota associated with obesity, diabetes, and hepatic steatosis. The RAS interaction signaling and modulation were analyzed. Strategies including the use of prebiotics, symbiotics, probiotics, and biotechnology may affect the gut microbiota and its impact on human health.

Microbe-Derived Antioxidants Alleviate Liver and Adipose Tissue Lipid Disorders and Metabolic Inflammation Induced by High Fat Diet in Mice

Obesity induces lipodystrophy and metabolic inflammation. Microbe-derived antioxidants (MA) are novel small-molecule nutrients obtained from microbial fermentation, and have anti-oxidation, lipid-lowering and anti-inflammatory effects. Whether MA can regulate obesity-induced lipodystrophy and metabolic inflammation has not yet been investigated. The aim of this study was to investigate the effects of MA on oxidative stress, lipid disorders, and metabolic inflammation in liver and epididymal adipose tissues (EAT) of mice fed with a high-fat diet (HFD). Results showed that MA was able to reverse the HFD-induced increase in body weight, body fat rate and Lee's index in mice; reduce the fat content in serum, liver and EAT; and regulate the INS, LEP and resistin adipokines as well as free fatty acids to their normal levels. MA also reduced de novo synthesis of fat in the liver and EAT and promoted gene expression for lipolysis, fatty acid transport and β-oxidation. MA decreased TNF-α and MCP1 content in serum, elevated SOD activity in liver and EAT, induced macrophage polarization toward the M2 type, inhibited the NLRP3 pathway, increased gene expression of the anti-inflammatory factors IL-4 and IL-13 and suppressed gene expression of the pro-inflammatory factors IL-6, TNF-α and MCP1, thereby attenuating oxidative stress and inflammation induced by HFD. In conclusion, MA can effectively reduce HFD-induced weight gain and alleviate obesity-induced oxidative stress, lipid disorders and metabolic inflammation in the liver and EAT, indicating that MA shows great promise as a functional food.

Overview of Cellular and Soluble Mediators in Systemic Inflammation Associated with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent chronic liver disease in Western countries, affecting approximately 25% of the adult population. This condition encompasses a spectrum of liver diseases characterized by abnormal accumulation of fat in liver tissue (non-alcoholic fatty liver, NAFL) that can progress to non-alcoholic steatohepatitis (NASH), characterized by the presence of liver inflammation and damage. The latter form often coexists with liver fibrosis which, in turn, may progress to a state of cirrhosis and, potentially, hepatocarcinoma, both irreversible processes that often lead to the patient's death and/or the need for liver transplantation. Along with the high associated economic burden, the high mortality rate among NAFLD patients raises interest, not only in the search for novel therapeutic approaches, but also in early diagnosis and prevention to reduce the incidence of NAFLD-related complications. In this line, an exhaustive characterization of the immune status of patients with NAFLD is mandatory. Herein, we attempted to gather and compare the current and relevant scientific evidence on this matter, mainly on human reports. We addressed the current knowledge related to circulating cellular and soluble mediators, particularly platelets, different leukocyte subsets and relevant inflammatory soluble mediators.

Lessons on Drug Development: A Literature Review of Challenges Faced in Nonalcoholic Fatty Liver Disease (NAFLD) Clinical Trials

NAFLD is the most common chronic liver disease worldwide, occurring in both obese and lean patients. It can lead to life-threatening liver diseases and nonhepatic complications, such as cirrhosis and cardiovascular diseases, that burden public health and the health care system. Current care is weight loss through diet and exercise, which is a challenging goal to achieve. However, there are no FDA-approved pharmacotherapies for NAFLD. This review thoroughly examines the clinical trial findings from 22 drugs (Phase 2 and above) and evaluates the future direction that trials should take for further drug development. These trialed drugs can broadly be categorized into five groups-hypoglycemic, lipid-lowering, bile-pathway, anti-inflammatory, and others, which include nutraceuticals. The multitude of challenges faced in these yet-to-be-approved NAFLD drug trials provided insight into a few areas of improvement worth considering. These include drug repurposing, combinations, noninvasive outcomes, standardization, adverse event alleviation, and the need for precision medicine with more extensive consideration of NAFLD heterogenicity in drug trials. Understandably, every evolution of the drug development landscape lies with its own set of challenges. However, this paper believes in the importance of always learning from lessons of the past, with each potential improvement pushing clinical trials an additional step forward toward discovering appropriate drugs for effective NAFLD management.

Shedding light on non-alcoholic fatty liver disease: Pathogenesis, molecular mechanisms, models, and emerging therapeutics

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder globally impacting an estimated 25% of the population associated with severe consequences such as cirrhosis, hepatocellular carcinoma (HCC), and overall mortality. Fatty liver disease is triggered through multiple pathways, but the most prominent cause is either diabetes or obesity, or a combination of both. Therefore, hepatic glucose, insulin and fatty acid signaling becomes a dire need to understand which is well elaborated in this review. This review summarizes the popular two-hit pathogenesis of NAFLD, the molecular mechanisms underlying hepatic insulin resistance. As fatty liver disease gets advanced, it requires in-vitro as well as in-vivo models closer to disease progression in humans for better understanding the pathological state and identifying a novel therapeutic target. This review summarizes in-vitro (2D cell-culture/co-culture, 3D spheroid/organoid/liver-on-a-chip) models as well as in-vivo (genetically/dietary/chemically induced fatty liver disease) research models. Fatty liver disease research has gathered lots of attention recently since there is no FDA approved therapy available so far. However, there have been numerous promising targets to treat fatty liver disease including potential therapeutic targets under clinical trials are listed in this review.

Role of gut microbiota in the pathogenesis and treatment of diabetes mullites: Advanced research-based review

Gut microbiota plays an important role in the proper functioning of human organisms, while its dysbiosis is associated with disease in various body organs. Diabetes mellitus (DM) is a set of heterogeneous metabolic diseases characterized by hyperglycemia caused by direct or indirect insulin deficiency. There is growing evidence that gut microbiota dysbiosis is closely linked to the development of DM. Gut microbiota composition changes in type 1 diabetes mullites (T1DM) and type 2 diabetes mullites (T2DM) patients, which may cause gut leakiness and uncontrolled entry of antigens into the circulation system, triggering an immune response that damages the isle β cells or metabolic disorders. This review summarizes gut microbiota composition in healthy individuals and compares it to diabetes mullites patients. The possible pathogenesis by which gut microbiota dysbiosis causes DM, particularly gut leakiness and changes in gut microbiota metabolites is also discussed. It also presents the process of microbial-based therapies of DM.

Evaluate the elasticity of carotid artery in the type 2 diabetes mellitus patients with nonalcoholic fatty liver disease by two-dimensional strain imaging

To evaluate carotid elasticity by using two-dimensional strain imaging (2DSI) in type 2 diabetes mellitus (T2DM) patients with nonalcoholic fatty liver disease (NAFLD). 98 patients with T2DM diagnosed in our hospital were selected. All the patients were without carotid plaque, which were proved by carotid ultrasonography. According to the fatty liver classification standard, patients were divided into three groups. There were 35 cases without NAFLD in group A, 33 cases with mild NAFLD in group B and 30 cases with moderate to severe NAFLD in group C. By using two-dimensional and M-mode ultrasound to measure the left carotid intima-media thickness (IMT), common carotid arterial systolic diameter (Ds) and diastolic diameter (Dd). The systolic peak velocity was measured by spectral Doppler ultrasound. The systolic global peak circumferential strain (CS), early and late systolic global circumferential strain rate (CSr) were measured by 2DSI. The stiffness parameters β1 and β2 were calculated by M-mode ultrasound and 2DSI separately. Among three groups, the Ds, Dd and systolic peak velocity showed no significant difference (all P > .05). In group C, IMT and β1 were obviously increased than those of groups A and B (all P < .05). Compared groups A and B, there were no significant difference in IMT and β1 (all P > .05). β2 was higher in groups B and C than those in group A, CS, CSr were lower in groups B and C than those in group A (both P > .05). The carotid elasticity of T2DM patients with NAFLD can be evaluated by 2DSI.

Impact on Prevalence of the Application of NAFLD/MAFLD Criteria in Overweight and Normal Weight Patients

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome. Recently, the term metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed and adapted to body mass index (BMI). This study describes the impact on prevalence of the application of both criteria in overweight and lean patients.

METHODS

Patients who were evaluated for liver steatosis by transient elastography were included and divided according to BMI (≥25 kg/m² and <25 kg/m²) and classified as NAFLD or MAFLD, according to metabolic abnormalities. Differences in prevalence were evaluated applying both criteria. A multivariate analysis was performed to evaluate independent associations of metabolic abnormalities and liver steatosis in lean patients.

RESULTS

3847 patients were included. In overweight patients (61%), the prevalence NAFLD was 63.6% and 65.3% for MAFLD (p = 0.22). In contrast, the prevalence of MAFLD was lower (7.9% vs. 18.3%, p ≤ 0.001) in lean patients. In this group, higher age, fasting glucose, triglycerides, and waist circumference showed independent association with liver steatosis.

CONCLUSION

The application of NAFLD/MAFLD criteria did not show prevalence differences in overweight patients. With MAFLD criteria, the prevalence is lower in lean patients, but patients with high risk of progression of liver disease for steatosis were identified, according to their metabolic abnormalities.

Gut microbiota and obesity

Worldwide, adults and childhood obesity are increasing alarmingly, being a major health problem. Obesity is correlated with an increased incidence of various systemic diseases including cancer, heart diseases, and diabetes mellitus type 2. Risk factors for obesity are dysbiosis, genetic, socioeconomic, behavioural and environmental. The gut microbiota has beneficial effects on human health, like host immune system stimulation, being influenced by pH, or nutrient intake. Studies performed on humans and animal models reported differences regarding microbiota at lean and obese individuals. The consumption of probiotics and prebiotics may balance the microbiota with positive effects in obesity. The main aim of this review is to reveal the interaction between dysbiosis and obesity

Just Drink a Glass of Water? Effects of Bicarbonate–Sulfate–Calcium–Magnesium Water on the Gut–Liver Axis

Background and Aim: Fonte Essenziale® water is a bicarbonate–sulfate–calcium–magnesium water, low in sodium, recognized by the Italian health care system in hydropinotherapy and hepatobiliary dyspepsia therapy. We wanted to explore its effects on the gut–liver axis and microbiota in non-alcoholic fatty liver disease patients.

Patients and Methods: We considered enrollment for 70 patients, of which four were excluded. We finally enrolled 55 patients with ultrasound-documented steatosis (SPs+) and 11 patients without it (SPs−). They then drank 400 ml of water for 6 months in the morning on an empty stomach. Routine hematochemical and metabolic parameters, oxidative stress parameters, gastrointestinal hormone levels, and fecal parameters of the gut microbiota were evaluated at three different assessment times, at baseline (T0), after 6 months (T6), and after a further 6 months of water washout (T12). We lost, in follow-up, 4 (T6) and 22 (T12) patients.

Results: Between T0–T6, we observed a significant Futuin A and Selenoprotein A decrease and a GLP-1 and PYY increase in SPs+ and the same for Futuin A and GLP-1 in SPs−. Effects were lost at T12. In SPs+, between T0–T12 and T6–12, a significant reduction in Blautia was observed; between T0–T12, a reduction of Collinsella unc. was observed; and between T0–T12 and T6–12, an increase in Subdoligranulum and Dorea was observed. None of the bacterial strains we analyzed varied significantly in the SPs− population.

Conclusion: These results indicate beneficial effects of water on gastrointestinal hormones and hence on the gut–liver axis in the period in which subjects drank water both in SPs− and in SPs+.

Encoding with a fluorescence-activating and absorption-shifting tag generates living bacterial probes for mammalian microbiota imaging

The mammalian microbiota plays essential roles in health. A primary determinant to understand the interaction with the host is the distribution and viability of its key microorganisms. Here, a strategy of encoding with a fluorescence-activating and absorption-shifting tag (FAST) is reported to prepare living bacterial probes for real-time dynamic, dual-modal, and molecular oxygen-independent imaging of the host microbiota. Carrying FAST endows bacteria with rapid on-demand turn on-off fluorescence by adding or removal of corresponding fluorogens. Encoded bacteria are able to reversibly switch emission bands for dual-color fluorescence imaging via fluorogen exchange. Due to molecular oxygen-independent emission of FAST, encoded bacteria can emit fluorescence under anaerobic environments including the gut and tumor. These living probes demonstrate the applicability to quantify the vitality of bacteria transplanted to the gut microbiota. This work proposes a unique fluorescence probe for investigating the dynamics of the host microbiota.

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Living bacterial probes for real-time dynamic, dual-modal, and molecular oxygen-independent imaging of mammalian microbiota.

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Engineered bacteria showing on-demand turn on-off fluorescence by adding or removal of corresponding fluorogens.

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Fluorescence emission under anaerobic in vivo environments including the gut and tumor.

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A fluorescence probe to determine the vitality of transplanted bacteria and investigate the dynamics of the host microbiota.

Characterization of microbiome and metabolite analyses in patients with metabolic associated fatty liver disease and type II diabetes mellitus

Background

State-of-the-art renewal has indicated the improvement of diagnostics of patients with metabolic associated fatty liver disease (MAFLD) and/or type II diabetes mellitus (T2DM) by dissecting the clinical characteristics as well as genomic analysis. However, the deficiency of the characterization of microbial and metabolite signatures largely impedes the symptomatic treatment.

Methods

For the purpose, we retrospectively analyzed the clinical data of 20 patients with MAFLD (short for “M”), 20 cases with MAFLD and T2DM (short for “MD”), together with 19 healthy donors (short for “Ctr”). Microbial and metabolite analyses were further conducted to explore the similarities and differences among the aforementioned populations based on feces and blood samples, respectively.

Results

Compared with those in the Ctr group, patients with M or MD revealed multifaceted similarities (e.g., Age, ALP, LDL, BUN) and distinctions in clinical indicators of liver (e.g., BMI, ALT, PCHE, CAP). With the aid of microbial and metabolite analyses as well as bioinformatic analyses, we found that the characteristics of gut microbiota (e.g., abundance, hierarchical clustering, cladogram, species) and lipid metabolism (e.g., metabolite, correlation coefficient and scatter plot) were distinct among the indicated groups.

Conclusions

The patients with MD revealed multifaceted similarities and distinctions in characteristics of microbiome and metabolites with those in the M and HD groups, and in particular, the significantly expressed microbes (e.g., Elusimicrobiota, Berkelbacteria, Cyanobacteria, Peregrinibacteria) and lipid metabolites (e.g., Lipid-Q-P-0765, Lipid-Q-P-0216, Lipid-Q-P-0034, Lipid-Q-P-0800), which would collectively benefit the clinical diagnosis of MAFLD and T2DM.

Cancer cachexia: lessons from Drosophila

Cachexia, a wasting syndrome that is often associated with cancer, is one of the primary causes of death in cancer patients. Cancer cachexia occurs largely due to systemic metabolic alterations stimulated by tumors. Despite the prevalence of cachexia, our understanding of how tumors interact with host tissues and how they affect metabolism is limited. Among the challenges of studying tumor-host tissue crosstalk are the complexity of cancer itself and our insufficient knowledge of the factors that tumors release into the blood. Drosophila is emerging as a powerful model in which to identify tumor-derived factors that influence systemic metabolism and tissue wasting. Strikingly, studies that are characterizing factors derived from different fly tumor cachexia models are identifying both common and distinct cachectic molecules, suggesting that cachexia is more than one disease and that fly models can help identify these differences. Here, we review what has been learned from studies of tumor-induced organ wasting in Drosophila and discuss the open questions.

Effect of Fecal Microbiota Transplantation on Non-Alcoholic Fatty Liver Disease: A Randomized Clinical Trial

BACKGROUND AND AIMS

The clinical efficacy of fecal microbiota transplantation (FMT) in patients with non-alcoholic fatty liver disease (NAFLD) and the variant effects of FMT on lean and obese NAFLD patients remain elusive. Our study aimed to determine the clinical efficacy and safety of FMT for patients with NAFLD, elucidating its different influences on lean and obese patients with NAFLD.

METHODS

We performed a randomized and controlled clinical trial. Patients in the non-FMT group were administered oral probiotics. In the FMT group, patients were randomized to receive FMT with donor stool (heterologous) via colonoscopy, followed by three enemas over 3 days. Both groups were also required to maintain a healthy diet and keep regular exercise for more than 40 min every day. They returned to the hospital for reexamination 1 month after treatment.

RESULTS

FMT can decrease the fat accumulation in the liver by improving the gut microbiota dysbiosis, thus attenuating fatty liver disease. Significant differences in the clinical features and gut microbiota between lean and obese NAFLD patients were unveiled. Moreover, FMT had better effects on gut microbiota reconstruction in lean NAFLD than in obese NAFLD patients.

CONCLUSIONS

FMT could successfully improve the therapeutic effects on patients with NAFLD, and its clinical efficacy was higher in lean NAFLD than in obese NAFLD patients.

The Role of the Gut Microbiota in the Pathogenesis of Diabetes

Diabetes mellitus is a significant clinical and therapeutic problem because it can lead to serious long-term complications. Its pathogenesis is not fully understood, but there are indications that dysbiosis can play a role in the development of diabetes, or that it appears during the course of the disease. Changes in microbiota composition are observed in both type 1 diabetes (T1D) and type 2 diabetes (T2D) patients. These modifications are associated with pro-inflammation, increased intestinal permeability, endotoxemia, impaired β-cell function and development of insulin resistance. This review summarizes the role of the gut microbiota in healthy individuals and the changes in bacterial composition that can be associated with T1D or T2D. It also presents new developments in diabetes therapy based on influencing the gut microbiota as a promising method to alter the course of diabetes. Moreover, it highlights the lacking data and suggests future directions needed to prove the causal relationship between dysbiosis and diabetes, both T1D and T2D.

Understanding the Role of the Gut Microbiome and Microbial Metabolites in Non-Alcoholic Fatty Liver Disease: Current Evidence and Perspectives

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD begins as a relatively benign hepatic steatosis which can evolve to non-alcoholic steatohepatitis (NASH); the risk of cirrhosis and hepatocellular carcinoma (HCC) increases when fibrosis is present. NAFLD represents a complex process implicating numerous factors—genetic, metabolic, and dietary—intertwined in a multi-hit etiopathogenetic model. Recent data have highlighted the role of gut dysbiosis, which may render the bowel more permeable, leading to increased free fatty acid absorption, bacterial migration, and a parallel release of toxic bacterial products, lipopolysaccharide (LPS), and proinflammatory cytokines that initiate and sustain inflammation. Although gut dysbiosis is present in each disease stage, there is currently no single microbial signature to distinguish or predict which patients will evolve from NAFLD to NASH and HCC. Using 16S rRNA sequencing, the majority of patients with NAFLD/NASH exhibit increased numbers of Bacteroidetes and differences in the presence of Firmicutes, resulting in a decreased F/B ratio in most studies. They also present an increased proportion of species belonging to Clostridium, Anaerobacter, Streptococcus, Escherichia, and Lactobacillus, whereas Oscillibacter, Flavonifaractor, Odoribacter, and Alistipes spp. are less prominent. In comparison to healthy controls, patients with NASH show a higher abundance of Proteobacteria, Enterobacteriaceae, and Escherichia spp., while Faecalibacterium prausnitzii and Akkermansia muciniphila are diminished. Children with NAFLD/NASH have a decreased proportion of Oscillospira spp. accompanied by an elevated proportion of Dorea, Blautia, Prevotella copri, and Ruminococcus spp. Gut microbiota composition may vary between population groups and different stages of NAFLD, making any conclusive or causative claims about gut microbiota profiles in NAFLD patients challenging. Moreover, various metabolites may be involved in the pathogenesis of NAFLD, such as short-chain fatty acids, lipopolysaccharide, bile acids, choline and trimethylamine-N-oxide, and ammonia. In this review, we summarize the role of the gut microbiome and metabolites in NAFLD pathogenesis, and we discuss potential preventive and therapeutic interventions related to the gut microbiome, such as the administration of probiotics, prebiotics, synbiotics, antibiotics, and bacteriophages, as well as the contribution of bariatric surgery and fecal microbiota transplantation in the therapeutic armamentarium against NAFLD. Larger and longer-term prospective studies, including well-defined cohorts as well as a multi-omics approach, are required to better identify the associations between the gut microbiome, microbial metabolites, and NAFLD occurrence and progression.

Luteolin alleviates non-alcoholic fatty liver disease in rats via restoration of intestinal mucosal barrier damage and microbiota imbalance involving in gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) is demonstrated to be closely related to the disorder of gut microbiota and the intestinal mucosal barrier. Luteolin is a natural flavonoid with various activities. We aimed to investigate whether Luteolin can alleviate NAFLD and its possible mechanism involving the gut-liver axis. A rat NAFLD model was established by feeding a high-fat diet (HFD), and Luteolin was administered intragastrically. The effects of Luteolin on liver biochemical parameters, intestinal histopathology and integrity, gut microbiota, lipopolysaccharides (LPS), inflammatory cytokines, and the Toll-like receptor 4 (TLR4) signaling pathway were evaluated. We found that Luteolin restored the expression of the tight junction proteins in the intestine and ameliorated the increase permeability of the intestinal mucosa to Fluorescein isothiocyanate-dextran (FD4) caused by a high-fat diet, thus enhancing the function of the intestinal barrier. In addition, Luteolin inhibited the TLR4 signaling pathway in the liver, thereby reducing the secretion of pro-inflammatory factors and alleviating NAFLD. 16S rRNA gene sequencing revealed that Luteolin intervention significantly altered the composition of the gut microbiota in NAFLD rats and increased the richness of gut microbiota. Luteolin alleviates NAFLD in rats via restoration and repair of the damaged intestinal mucosal barrier and microbiota imbalance.

Emodin palliates high-fat diet-induced nonalcoholic fatty liver disease in mice via activating the farnesoid X receptor pathway

BACKGROUND

Cassia mimosoides Linn (CMD) is a traditional Chinese herb that clears liver heat and dampness. It has been widely administered in clinical practice to treat jaundice associated with damp-heat pathogen and obesity. Emodin (EMO) is a major bioactive constituent of CMD that has apparent therapeutic efficacy against obesity and fatty liver. Here, we investigated the protective effects and underlying mechanisms of EMO against high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD).

OBJECTIVE

We aimed to investigate whether EMO activates farnesoid X receptor (FXR) signaling to alleviate HFD-induced NAFLD.

MATERIALS AND METHODS

In vivo assays included serum biochemical indices tests, histopathology, western blotting, and qRT-PCR to evaluate the effects of EMO on glucose and lipid metabolism disorders in wild type (WT) and FXR knockout mice maintained on an HFD. In vitro experiments included intracellular triglyceride (TG) level measurement and Oil Red O staining to assess the capacity of EMO to remove lipids induced by oleic acid and palmitic acid in WT and FXR knockout mouse primary hepatocytes (MPHs). We also detected mRNA expression of FXR signaling genes in MPHs.

RESULTS

After HFD administration, body weight and serum lipid and inflammation levels were dramatically increased in the WT mice. The animals also presented with impaired glucose tolerance, insulin resistance, and antioxidant capacity, liver tissue attenuation, and pathological injury. EMO remarkably reversed the foregoing changes in HFD-induced mice. EMO improved HFD-induced lipid accumulation, insulin resistance, inflammation, and oxidative stress in a dose-dependent manner in WT mice by inhibiting FXR expression. EMO also significantly repressed TG hyperaccumulation by upregulating FXR expression in MPHs. However, it did not improve lipid accumulation, insulin sensitivity, or glucose tolerance in HFD-fed FXR knockout mice.

CONCLUSIONS

The present study demonstrated that EMO alleviates HFD-induced NAFLD by activating FXR signaling which improves lipid accumulation, insulin resistance, inflammation, and oxidative stress.

Bacteria-Based Microdevices for the Oral Delivery of Macromolecules

The oral delivery of macromolecules is quite challenging due to environmental insults and biological barriers encountered along the gastrointestinal (GI) tract. Benefiting from their living characteristics, diverse bacterial species have been engineered as intelligent platforms to deliver various therapeutics. To tackle difficulties in oral delivery, innovative bacteria-based microdevices have been developed by virtue of advancements in synthetic biology and nanotechnology, with aims to overcome the instability and short half-life of macromolecules in the GI tract. In this review, we summarize the main classes of macromolecules that are produced and delivered through the oral ingestion of bacteria and bacterial derivatives. Furtherly, we discuss the engineering strategies and biomedical applications of these living microdevices in disease diagnosis, bioimaging, and treatment. Finally, we highlight the advantages as well as the limitations of these engineered bacteria used as platforms for the oral delivery of macromolecules and also propose their potential for clinical translation. The results summarized in this review article would contribute to the invention of next-generation bacteria-based systems for the oral delivery of macromolecules.

Decorating Bacteria with a Therapeutic Nanocoating for Synergistically Enhanced Biotherapy

Disorders in the gut microbiota have been implicated in various diseases, such as inflammatory bowel diseases, diabetes, and cancers. Oral microecologics are of great importance due to their ability to directly intervene the gut microbiome as well as their noninvasiveness and low side effects, while have suffered from low bioavailability and a single therapeutic effect. Here, probiotics are coated with a therapeutic nanocoating for synergistically enhanced biotherapy, a method inspired by the robust protective and therapeutic effectiveness of silkworm cocoon. With its transition from a random coil to β-sheet conformation, silk fibroin can self-assemble onto the surface of bacteria. By a simple layer-by-layer procedure, an entire nanocoating can be formed along with a near quantitative coating ratio and almost uninfluenced bacterial viability. Thanks to its protective barrier role and innate pharmaceutical activity, silk fibroin nanocoating endows the coated bacteria with a markedly improved survival against gastric insults and a synergistically enhanced therapeutic effect in a murine model of intestinal mucositis. This work demonstrates how therapeutic elements can be combined with probiotics via a simple coating strategy and proposes an alternative to enhance bioavailability and treatment efficacy of oral microecologics.

Curcumin modulates gut microbiota and improves renal function in rats with uric acid nephropathy

It is well known that the progression of hyperuricemia disease often contributes to renal dysfunction. However, there have been few studies on uric acid nephropathy (UAN), especially its relationship with gut microbiota. UAN is usually accompanied by disordered intestinal flora, and damaged gut barrier, which are closely related to tubulointerstitial fibrosis, and systemic inflammation. In previous studies, it has been confirmed that curcumin could alleviate tubulointerstitial fibrosis, and improve renal function through its antioxidant, anti-apoptotic, and anti-inflammatory efficacies. However, the effects curcumin exerts on intestinal flora in uric acid nephropathy are still unknown. Therefore, we used next-generation sequencing technology to investigate the effects of curcumin on gut microbiota in a rat model of UAN induced by adenine and potassium oxonate, and rats were randomly divided into control, model or curcumin treatment groups. The results demonstrated that, compared to the model group, the treatment group showed decreased serum uric acid (156.80 ± 11.90 μmol/L vs. 325.60 ± 18.65 μmol/L, p < 0.001), serum creatinine (66.20 ± 11.88 μmol/L vs. 182.20 ± 8.87 μmol/L, p < 0.001) and BUN level (13.33 ± 3.16 mmol/L vs. 36.04 ± 6.60 mmol/L, p < 0.001). The treatment group also displayed attenuated renal pathological lesions and metabolic endotoxemia (25.60 ± 5.90 ng/mL vs. 38.40 ± 4.98 ng/mL, p < 0.01), and improved tightly linked proteins expression. Besides, curcumin altered the gut microbiota structure in UAN rats. More specifically, curcumin treatment protected against the overgrowth of opportunistic pathogens in UAN, including Escherichia-Shigella and Bacteroides, and increased the relative abundance of bacteria producing short‐chain fatty acids (SCFAs), such as Lactobacillus and Ruminococcaceae. These results suggest that curcumin could modulate gut microbiota, fortify the intestinal barrier, attenuate metabolic endotoxemia, and consequently protect the renal function in UAN rats.

Coronavirus disease 2019 severity in obesity: Metabolic dysfunction-associated fatty liver disease in the spotlight

The coronavirus disease 2019 (COVID-19) outbreak has drawn the scientific community's attention to pre-existing metabolic conditions that could aggravate the infection, causing extended viral shedding, prolonged hospitalization, and high death rates. Metabolic dysfunction-associated fatty liver disease (MAFLD) emerges as a surrogate for COVID-19 severity due to the constellation of metabolic alterations it entails. This review outlines the impact MAFLD exerts on COVID-19 severity in obese subjects, besides the possible mechanistic links to the poor outcomes. The data collected showed that MAFLD patients had poorer COVID-19 outcomes than non-MAFLD obese subjects. MAFLD is generally accompanied by impaired glycemic control and systemic arterial hypertension, both of which can decompensate during the COVID-19 clinical course. Also, MAFLD subjects had higher plasma inflammatory marker concentrations than non-MAFLD subjects, which might be related to an intensified cytokine storm syndrome frequently associated with the need for mechanical ventilation and death. In conclusion, MAFLD represents a higher risk than obesity for COVID-19 severity, resulting in poor outcomes and even progression to non-alcoholic steatohepatitis. Hepatologists should include MAFLD subjects in the high-risk group, intensify preventive measurements, and prioritize their vaccination.

Pure total flavonoids from citrus attenuate non-alcoholic steatohepatitis via regulating the gut microbiota and bile acid metabolism in mice

BACKGROUND

Our previous studies found that Pure total flavnoids from citrus (PTFC) can effectively improve non-alcoholic steatohepatitis (NASH) in mice. Here, we discuss on the mechanism of PTFC in treating NASH with focus on the regulation of the gut microbiota and bile acid metabolism.

METHODS

C57BL/6 J mice were randomly divided into three groups: normal diet group (Normal), high-fat diet group (HFD) and high-fat + PTFC treatment group (PTFC). Mice in the Normal group were fed chow diet, while the other groups were fed high fat diet (HFD) for 16 weeks. In the 5th week, the mice in the PTFC group were treated with 50 mg/kg/day PTFC for an additional twelve weeks. After sacrifice, histopathology of the liver was assessed, and the gut microbial composition was analyzed by 16S rDNA gene sequencing. Bile Acid profiles in serum were determined by ultraperformance liquid chromatography (UPLC-MS/MS).

RESULTS

PTFC intervention significantly attenuated HFD-induced NASH symptoms compared with the HFD group in mice. 16S rDNA sequencing showed that PTFC treatment increased the phylogenetic diversity of the HFD-induced microbiota dysbiosis. PTFC intervention significantly increased the relative abundances of Bacteroidaceae and Christensenellaceae. Furthermore, PTFC reduced the content of toxic bile acids, such as TDCA, DCA, TCA, CA and increased the ratio of secondary to primary bile acids. FXR and TGR5 deficiency were significantly alleviated.

CONCLUSION

PTFC can improve NASH via the the gut microbiota and bile acid metabolism.

Understanding the Effects of Gut Microbiota Dysbiosis on Nonalcoholic Fatty Liver Disease and the Possible Probiotics Role: Recent Updates

Nonalcoholic fatty liver disease (NAFLD) is leading chronic liver syndrome worldwide. Gut microbiota dysbiosis significantly contributes to the pathogenesis and severity of NAFLD. However, its role is complex and even unclear. Treatment of NAFLD through chemotherapeutic agents have been questioned because of their side effects on health. In this review, we highlighted and discussed the current understanding on the importance of gut microbiota, its dysbiosis and its effects on the gut-liver axis and gut mucosa. Further, we discussed key mechanisms involved in gut dysbiosis to provide an outline of its role in progression to NAFLD and liver cirrhosis. In addition, we also explored the potential role of probiotics as a treatment approach for the prevention and treatment of NAFLD. Based on the latest findings, it is evident that microbiota targeted interventions mostly the use of probiotics have shown promising effects and can possibly alleviate the gut microbiota dysbiosis, regulate the metabolic pathways which in turn inhibit the progression of NAFLD through the gut-liver axis. However, very limited studies in humans are available on this issue and suggest further research work to identify a specific core microbiome association with NAFLD and to discover its mechanism of pathogenesis, which will help to enhance the therapeutic potential of probiotics to NAFLD.

Pre-transplant hepatic steatosis (fatty liver) is associated with chronic graft-vs-host disease but not mortality

Allogeneic-HCT (allo-HCT), while potentially curative, can result in significant complications including graft versus host disease (GVHD). Prior studies suggest that metabolic syndrome may be one risk factor for GVHD. We hypothesized that hepatic steatosis on pre-HCT computed tomography (CT) scans may be a marker for development of GVHD and poor outcomes in allo-HCT. In this retrospective study, we reviewed the pre-HCT CT scans and transplant outcome data of patients who underwent allo-HCT at Duke University Medical Center from 2009 to 2017. The presence of steatosis was confirmed using CT attenuation measurements. We then assessed the association between pre-HCT hepatic steatosis and HCT-related outcomes including GVHD. 80 patients who had pre-HCT CT scans were included in the study. Pre-transplant hepatic steatosis was associated with the development of chronic GVHD (OR 4.2, p = 0.02), but was not associated with acute GVHD (OR 1.3, p = 0.7), non-relapse mortality (p = 0.81) or overall survival (p = 0.74). Based on this single center retrospective study, pre-transplant hepatic steatosis is associated with development of chronic GVHD. Further, prospective study with other imaging modalities including non-contrasted CT scans is needed to determine if this association is reproducible.

The Gut Microbiota and Its Metabolites, Novel Targets for Treating and Preventing Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent metabolic disorders worldwide, along with obesity and type 2 diabetes. NAFLD involves a series of liver abnormalities from simple hepatic steatosis to non-alcoholic steatohepatitis, which can ultimately lead to liver cirrhosis and cancer. The gut-liver axis plays an important role in the development of NAFLD, which depends mainly on regulation of the gut microbiota and its bacterial products. These intestinal bacterial species and their metabolites, including bile acids, tryptophan catabolites, and branched-chain amino acids, regulate adipose tissue and intestinal homeostasis and contribute to the pathogenesis of NAFLD/non-alcoholic steatohepatitis. In this review, the current evidence regarding the key role of the gut microbiota and its metabolites in the pathogenesis and development of NAFLD is highlighted, and the advances in the progression and applied prospects of gut microbiota-targeted dietary and exercise therapies is also discussed.

Role of Overweight and Obesity in Gastrointestinal Disease

The prevalence of obesity is increasing worldwide, leading to a severe impairment of overall health. Actually, obesity has been associated with several pathological conditions, causing an excess overall mortality. In particular, overweight and obesity are well known risk factors for a variety of gastrointestinal (GI) disorders i.e., functional GI disorders as well as, inflammatory bowel disease (IBD), pancreatitis, and GI cancer. The aim of the present review is to summarize the potential role of overweight and obesity in GI disease with particular focus on plausible biological mechanisms that could explain the association between obesity and GI disease based on the most recent evidence in the literature.

Biointerfacial self-assembly generates lipid membrane coated bacteria for enhanced oral delivery and treatment

The gut microbiota represents a huge community of microorganisms that play essential roles in immune modulation and homeostasis maintenance. Microbiota transplantation is an important approach to prevent and treat disease as it can inhibit pathogen colonization and positively modulate bacterial composition. However, the development of oral bacterial therapeutics has been restricted by low bioavailability and limited retention in the gastrointestinal tract. Here, we report a simple yet highly efficient method to coat gut microbes via biointerfacial supramolecular self-assembly. Coating can be performed within 15 min by simply vortexing with biocompatible lipids. Bacteria coated with an extra self-assembled lipid membrane exhibit significantly improved survival against environmental assaults and almost unchanged viability and bioactivity. We demonstrate their enhanced efficacies in oral delivery and treatment using two murine models of colitis. We suggest that biointerfacial supramolecular self-assembly may provide a unique platform to generate advanced bacterial therapeutics for the treatment of various diseases.

Oral microbiota delivery is an approach to treat and prevent disease but suffers from low retention and bioavailability. Here the authors report on a lipid coating to protect against environmental assault maintaining viability and bioactivity of the bacteria and demonstrate effective application in a colitis model.

From circadian clocks to non-alcoholic fatty liver disease

Introduction: The circadian rhythm is an integral regulator of various endocrine processes in the body, including sleep-wake cycles, hormonal regulation, and metabolism. In addition to metabolic, genetic, and environmental factors, a dysregulated circadian rhythm resulting from lifestyle changes has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). An accumulating body of evidence also supports strong association between NAFLD and metabolic disorder, the pathogenesis of which is related to periodic fluctuations in hormonal homeostasis. It is clear that endocrine and circadian rhythms are tightly interconnected. Generally, the circadian rhythm regulates flux patterns of physiological functions. The present review will discuss the modulation of bodily processes by the circadian rhythm with specific attention to the regulation of NAFLD by leptin and related hormones.Areas covered: PubMed/MEDLINE was searched for articles related to concomitant occurrence of NAFLD and T2DM between January 1995 and September 2019. Areas covered included epidemiological, physiology and pathophysiology aspects.Expert opinion: NAFLD and NASH are increasingly prevalent and may be largely mitigated with effective lifestyle modification and, potentially, circadian rhythm stabilization. Improved knowledge of the specific pathogenesis of NAFLD in addition to enhanced diagnostic screening tools and prediction of future disease burden is imperative.

Understanding the Role of the Gut Microbiome and Microbial Metabolites in Obesity and Obesity-Associated Metabolic Disorders: Current Evidence and Perspectives

PURPOSE

In this review, we summarize current evidence on the gut microbiome and microbial metabolites in relation to obesity and obesity-associated metabolic disorders. Special emphasis is given on mechanisms interconnecting gut microbiome and microbial metabolites with metabolic disorders as well as on potential preventive and therapeutic perspectives with a "bench to bedside" approach.

RECENT FINDINGS

Recent data have highlighted the role of gut dysbiosis in the etiology and pathogenesis of metabolic disorders, including obesity, metabolic syndrome, type 2 diabetes mellitus, and non-alcoholic fatty liver disease. Overall, most studies have demonstrated a reduction in gut microbiome diversity and richness in obese subjects, but there is still much debate on the exact microbial signature of a healthy or an obese gut microbiome. Despite the controversial role of an altered gut microbiome as a cause or consequence of obesity in human studies, numerous animal studies and certain human studies suggest beneficial metabolic effects of certain microbial intestinal metabolites, such as butyrate, that could be used in the prevention and treatment of obesity and its comorbidities. More randomized controlled trials and larger prospective studies including well-defined cohorts as well as a multi-omics approach are warranted to better identify the associations between the gut microbiome, microbial metabolites, and obesity and its metabolic complications.

The role of gut microbiota in non-alcoholic fatty liver disease: pathways of mechanisms

Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome. Its prevalence increases with increasing rates of obesity, insulin resistance, and diabetes mellitus. The pathogenesis of NAFLD involves many factors, including the gastrointestinal microbiota. However, there is still debate about the impact of gut dysbiosis in the NAFLD disease progression. Therefore, this paper aims to review the relationship between gut microbiota and other risk factors for NAFLD and how gut dysbiosis plays a role in the pathogenesis of NAFLD. Hopefully, this paper can make an appropriate contribution to the development of NAFLD research in the future.

Potential role of phytochemicals in metabolic syndrome prevention and therapy

Metabolic syndrome (MetS) is a set of cardiovascular risk factors which severely increases the risk of type II diabetes, renal disease and cardiovascular disease. Over the last decades, the role of dietary bioactive substances in features of MetS has been extensively investigated. Due to their multiple properties, these plant-derived natural compounds have demonstrated to provide positive effects in obesity, diabetes, renal and in cardiovascular disease. Catechins of green tea and caffeine reduce body mass index and waist circumference. Catechins, anthocyanins and proanthocyanidins of cocoa reduce blood pressure and blood glucose. Curcumin and silymarin exert hepatoprotective effects. Monacolins of red yeast rice are effective cholesterol-lowering agents. However, inconsistent or conflicting results have been found in clinical trials when other promising compounds in vitro or in animal studies, such as policosanol, curcumin or silymarin, were used. Low oral bioavailability of substances, ineffective dosages, inadequate treatment duration and insufficient statistical approach may explain the lack of effectiveness observed in some human studies. Further clinical studies are needed to better understand the role of bioactive compounds in the prevention and management of MetS.

Interaction of gut microbiota with dysregulation of bile acids in the pathogenesis of nonalcoholic fatty liver disease and potential therapeutic implications of probiotics

The intestinal microbiota is now recognised to play key roles in health due to its involvement in many aspects of human physiology. Disturbance in gut microbiota (dysbiosis) is thus associated with many diseases including nonalcoholic fatty liver disease (NAFLD) which includes nonalcoholic fatty liver and nonalcoholic steatohepatitis. The mechanisms for the effect of dysbiosis in NAFLD pathogenesis are not completely elucidated. Many explanations have been proposed to trigger dysbiosis, leading to NAFLD including inflammation, ethanol produced by the gut bacteria and lipotoxicity. Recently the roles of bile acids and nuclear receptors are highly regarded. It is well known that gut microbes produce enzymes that convert primary bile acids into secondary bile acids in the intestines. Several studies have demonstrated that disturbance of the intestinal microbiota leads to decreased synthesis of secondary bile acids, which in turn decreases activation of nuclear receptors such as farnesoid X receptor (FXR), pregnane X receptor, Takeda G-protein-coupled bile acid protein 5 and vitamin D receptor. These receptors are important in energy regulation and their dysregulation can cause NAFLD. Therefore, stimulation of nuclear receptors especially FXR has been extensively explored for the amelioration of NAFLD. However, paradoxical effects of nuclear receptor activation are a major problem for the clinical application of nuclear receptor stimuli. We further posit that microbiome restoration could be an alternative approach for the treatment of NAFLD. Several gut bacteria are now known to be involved in bile acid metabolism. It will be necessary to identify which one/ones is/are feasible. Careful selection of commensal bacteria for probiotics may lead to an effective therapy for NAFLD.

Isolation and Characterization of Potentially Probiotic Bacterial Strains from Mice: Proof of Concept for Personalized Probiotics

Modulation of the gut microbiota through the use of probiotics has been widely used to treat or prevent several intestinal diseases. However, inconsistent results have compromised the efficacy of this approach, especially in severe conditions such as inflammatory bowel disease (IBD). The purpose of our study was to develop a personalized probiotic strategy and assess its efficacy in a murine model of intestinal inflammation. Commensal bacterial strains were isolated from the feces of healthy mice and then administered back to the host as a personalized treatment in dextran sodium sulfate (DSS)-induced colitis. Colonic tissues were collected for histological analysis and to investigate inflammatory markers such as Il-1β, Il-6, TGF-β, and Il-10, and the enzyme myeloperoxidase as a neutrophil marker. The group that received the personalized probiotic showed reduced susceptibility to DSS-colitis as compared to a commercial probiotic. This protection was characterized by a lower disease activity index and reduced histopathological damage in the colon. Moreover, the personalized probiotic was more effective in modulating the host immune response, leading to decreased Il-1β and Il-6 and increased TGF-β and Il-10 expression. In conclusion, our study suggests that personalized probiotics may possess an advantage over commercial probiotics in treating dysbiotic-related conditions, possibly because they are derived directly from the host's own microbiota.