Gut microbiota in nonalcoholic fatty liver diseases with and without type-2 diabetes mellitus

Role of FXR in the development of NAFLD and intervention strategies of small molecules

Non-alcoholic fatty liver disease (NAFLD) remains a prevailing etiological agent behind hepatocyte diseases like chronic liver disease. The spectrum of processes involved in NAFLD stages includes hepatic steatosis, non-alcoholic fatty liver, and non-alcoholic steatohepatitis (NASH). Without intervention, the progression of NASH can further deteriorate into cirrhosis and ultimately, hepatocellular carcinoma. The cardinal features that characterize NAFLD are insulin resistance, lipogenesis, oxidative stress and inflammation, extracellular matrix deposition and fibrosis. Due to its complex pathogenesis, existing pharmaceutical agents fail to take a curative or ameliorative effect on NAFLD. Consequently, it is imperative to identify novel therapeutic targets and strategies for NAFLD, ideally to improve the aforementioned key features in patients. As an enterohepatic regulator of bile acid homeostasis, lipid metabolism, and inflammation, FarnesoidX receptor (FXR) is an important pharmacological target for the treatment of NAFLD. Manipulating FXR to regulate lipid metabolic signaling pathways is a potential mechanism to mitigate NAFLD. Therefore, elucidating the modulatory character of FXR in regulating lipid metabolism in NAFLD has the potential to yield groundbreaking perspectives for drug design. This review details recent advances in the regulation of lipid depletion in hepatocytes and investigates the pivotal function of FXR in the progress of NAFLD.

Berberine prevents NAFLD and HCC by modulating metabolic disorders

Non-alcoholic fatty liver disease (NAFLD) is a global metabolic disease with high prevalence in both adults and children. Importantly, NAFLD is becoming the main cause of hepatocellular carcinoma (HCC). Berberine (BBR), a naturally occurring plant component, has been demonstrated to have advantageous effects on a number of metabolic pathways as well as the ability to kill liver tumor cells by causing cell death and other routes. This permits us to speculate and make assumptions about the value of BBR in the prevention and defense against NAFLD and HCC by a global modulation of metabolic disorders. Herein, we briefly describe the etiology of NAFLD and NAFLD-related HCC, with a particular emphasis on analyzing the potential mechanisms of BBR in the treatment of NAFLD from aspects including increasing insulin sensitivity, controlling the intestinal milieu, and controlling lipid metabolism. We also elucidate the mechanism of BBR in the treatment of HCC. More significantly, we provided a list of clinical studies for BBR in NAFLD. Taking into account our conclusions and perspectives, we can make further progress in the treatment of BBR in NAFLD and NAFLD-related HCC.

Composition of gut microbiota and non-alcoholic fatty liver disease: A systematic review and meta-analysis

The present systematic review and meta-analysis aimed to summarize the associations between gut microbiota composition and non-alcoholic fatty liver disease. To compare the differences between individuals with or without NAFLD, the standardized mean difference and 95% confidence interval were computed for each α-diversity index and relative abundance of gut microbes. The β-diversity indices were summarized in a qualitative manner. A total of 54 studies with 8894 participants were included. Overall, patients with NAFLD had moderate reduction in α-diversity indices including Shannon (SMD = -0.36, 95% CI = [-0.53, -0.19], p < 0.001) and Chao 1 (SMD = -0.42, 95% CI = [-0.68, -0.17], p = 0.001), but no significant differences were found for Simpson, observed species, phylogenetic diversity, richness, abundance-based coverage estimator, and evenness (p ranged from 0.081 to 0.953). Over 75% of the included studies reported significant differences in β-diversity. Although there was substantial interstudy heterogeneity, especially for analyses at the phylum, class, and family levels, the majority of the included studies showed alterations in the depletion of anti-inflammatory microbes (i.e., Ruminococcaceae and Coprococcus) and the enrichment of proinflammatory microbes (i.e., Fusobacterium and Escherichia) in patients with NAFLD. Perturbations in gut microbiota were associated with NAFLD, commonly reflected by a reduction in beneficial species and an increase in the pathogenic species.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Integrated serum pharmacochemistry, 16S rRNA sequencing and metabolomics to reveal the material basis and mechanism of Yinzhihuang granule against non-alcoholic fatty liver disease

ETHNOPHARMACOLOGICAL RELEVANCE

Yinzhihuang granule (YZHG) has liver protective effect and can be used for clinical treatment of non-alcoholic fatty liver disease (NAFLD), but its material basis and mechanism need to be further clarified.

AIM OF THE STUDY

This study aims to reveal the material basis and mechanism of YZHG treating NAFLD.

MATERIALS AND METHODS

Serum pharmacochemistry were employed to identify the components from YZHG. The potential targets of YZHG against NAFLD were predicted by system biology and then preliminarily verified by molecular docking. Furthermore, the functional mechanism of YZHG in NAFLD mice was elucidated by 16S rRNA sequencing and untargeted metabolomics.

RESULTS

From YZHG, 52 compounds were identified, of which 42 were absorbed into the blood. Network pharmacology and molecular docking showed that YZHG treats NAFLD with multi-components and multi-targets. YZHG can improve the levels of blood lipids, liver enzymes, lipopolysaccharide (LPS), and inflammatory factors in NAFLD mice. YZHG can also significantly improve the diversity and richness of intestinal flora and regulate glycerophospholipid and sphingolipid metabolism. Moreover, Western Blot experiment showed that YZHG can regulate liver lipid metabolism and enhance intestinal barrier function.

CONCLUSIONS

YZHG may treat NAFLD by improving the disruption of intestinal flora and enhancing the intestinal barrier. This will reduce the invasion of LPS into the liver subsequently regulate liver lipid metabolism and reduce liver inflammation.

Non-Alcoholic Fatty Liver Disease or Type 2 Diabetes Mellitus—The Chicken or the Egg Dilemma

In clinical practice, we often deal with patients who suffer from non-alcoholic fatty liver disease (NAFLD) concurrent with type 2 diabetes mellitus (T2DM). The etiopathogenesis of NAFLD is mainly connected with insulin resistance (IR) and obesity. Similarly, the latter patients are in the process of developing T2DM. However, the mechanisms of NAFLD and T2DM coexistence have not been fully elucidated. Considering that both diseases and their complications are of epidemic proportions and significantly affect the length and quality of life, we aimed to answer which of these diseases appears first and thereby highlight the need for their diagnosis and treatment. To address this question, we present and discuss the epidemiological data, diagnoses, complications and pathomechanisms of these two coexisting metabolic diseases. This question is difficult to answer due to the lack of a uniform procedure for NAFLD diagnosis and the asymptomatic nature of both diseases, especially at their beginning stages. To conclude, most researchers suggest that NAFLD appears as the first disease and starts the sequence of circumstances leading ultimately to the development of T2DM. However, there are also data suggesting that T2DM develops before NAFLD. Despite the fact that we cannot definitively answer this question, it is very important to bring the attention of clinicians and researchers to the coexistence of NAFLD and T2DM in order to prevent their consequences.

Targeted modulation of gut microbiota by traditional Chinese medicine and natural products for liver disease therapy

The gut microbiota not only constitutes intestinal microenvironment homeostasis and human health but also exerts indispensable roles in the occurrence and progression of multiple liver diseases, including alcohol-related liver disease, nonalcoholic fatty liver disease, autoimmune liver disease and liver cancer. Given the therapeutic status of these diseases, their prevention and early therapy are crucial, and the detailed mechanism of gut microbiota in liver disease urgently needs to be explored. Meanwhile, multiple studies have shown that various traditional Chinese medicines, such as Si Miao Formula, Jiangzhi Granules, Liushen Capsules, Chaihu-Shugan Power, Cassiae Semen and Gynostemma, as well as some natural products, including Costunolide, Coprinus comatus polysaccharide, Antarctic krill oil, Oridonin and Berberine, can repair liver injury, improve fatty liver, regulate liver immunity, and even inhibit liver cancer through multiple targets, links, and pathways. Intriguingly, the aforementioned effects demonstrated by these traditional Chinese medicines and natural products have been shown to be closely related to the gut microbiota, directly driving the strategy of traditional Chinese medicines and natural products to regulate the gut microbiota as one of the breakthroughs in the treatment of liver diseases. Based on this, this review comprehensively summarizes and discusses the characteristics, functions and potential mechanisms of these medicines targeting gut microbiota during liver disease treatment. Research on the potential effects on gut microbiota and the regulatory mechanisms of traditional Chinese medicine and natural products provides novel insights and significant references for developing liver disease treatment strategies. In parallel, such explorations will enhance the comprehension of traditional Chinese medicine and natural products modulating gut microbiota during disease treatment, thus facilitating their clinical investigation and application.

Hepatic Disorders and COVID-19: From Pathophysiology to Treatment Strategy

Following the SARS-CoV-2 outbreak and the subsequent development of the COVID-19 pandemic, organs such as the lungs, kidneys, liver, heart, and brain have been identified as priority organs. Liver diseases are considered a risk factor for high mortality from the COVID-19 pandemic. Besides, liver damage has been demonstrated in a substantial proportion of patients with COVID-19, especially those with severe clinical symptoms. Furthermore, antiviral medications, immunosuppressive drugs after liver transplantation, pre-existing hepatic diseases, and chronic liver diseases such as cirrhosis have also been implicated in SARS-CoV-2-induced liver injury. As a result, some precautions have been taken to prevent, monitor the virus, and avoid immunocompromised and susceptible individuals, such as liver and kidney transplant recipients, from being infected with SARS-CoV-2, thereby avoiding an increase in mortality. The purpose of this review was to examine the impairment caused by SARS-CoV-2 infection and the impact of drugs used during the pandemic on the mortality range and therefore the possibility of preventive measures in patients with liver disease.

The gut microbiota and celiac disease: Pathophysiology, current perspective and new therapeutic approaches

Celiac disease (CD) as a chronic gluten-sensitive intestinal condition, mainly affects genetically susceptible hosts. The primary determinants of CD have been identified as environmental and genetic variables. The development of CD is significantly influenced by environmental factors, including the gut microbiome. Therefore, gut microbiome re-programming-based therapies using probiotics, prebiotics, postbiotics, gluten-free diet, and fecal microbiota transplantation have shown promising results in the modification of the gut microbiome. Due to the importance and paucity of information regarding the CD pathophysiology, in this review, we have covered the association between CD development and gut microbiota, the effects of infectious agents, particularly the recent Covid-19 infection in CD patients, and the efficacy of potential therapeutic approaches in the CD have been discussed. Hence, scientific literature indicates that the diverse biological functions of the gut microbiota against immunomodulatory responses have made microbiome-based therapy an alternative therapeutic paradigm to ameliorate the symptoms of CD and quality of life. However, the exact potential of microbiota-based techniques that aims to quantitatively and qualitatively alter the gut microbiota to be used in the treatment and ameliorate the symptoms of CD will be determined with further research in the future.

The role of microbiota in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease worldwide. Gut microbiota can play a role in the pathogenesis of NAFLD since dysbiosis is associated with reduced bacterial diversity, altered Firmicutes/Bacteroidetes ratio, a relative abundance of alcohol-producing bacteria, or other specific genera. Changes can promote disrupted intestinal barrier and hyperpermeability, filtration of bacterial products, activation of the immune system, and pro-inflammatory changes in the intestine, in the liver, and at a systemic level. Microbiota-derived molecules can contribute to the steatogenic effects. The link between gut dysbiosis and NAFLD, however, is confused by several factors which include age, BMI, comorbidities, dietary components, and lifestyle. The role of toxic chemicals in food and water requires further studies in both gut dysbiosis and NAFLD. We can anticipate that gut microbiota manipulation will represent a potential therapeutic tool to delay or reverse the progression of NAFLD, paving the way to primary prevention measures.

Akkermansia muciniphila: from its critical role in human health to strategies for promoting its abundance in human gut microbiome

Akkermansia muciniphila, a frequent colonizer in the gut mucous layer of individuals, has constantly been recognized as a promising candidate for the next generation of probiotics due to its biological advantages from in vitro and in vivo investigations. This manuscript comprehensively reviewed the features of A. muciniphila in terms of its function in host physiology and frequently utilized nutrition using the published peer-reviewed articles, which should present valuable and critical information to scientists, engineers, and even the general population. A. muciniphila is an important bacterium that shows host physiology. However, its physiological advantages in several clinical settings also have excellent potential to become a probiotic. Consequently, it can be stated that there is a coherent and direct relation between the biological activities of the gut microbiota, intestinal dysbiosis/eubiosis, and the population of A. muciniphila in the gut milieu, which is influenced by various genetical and nutritional factors. Current regulatory barriers, the need for large-scale clinical trials, and the feasibility of production must be removed before A muciniphila can be extensively used as a next-generation probiotic.

The Association Between Vitamin D and Type 2 Diabetes Mellitus Complicated with Non-Alcoholic Fatty Liver Disease: An Observational Cross-Sectional Study

OBJECTIVE

To investigate the association between vitamin D deficiency and NAFLD risk in patients with type 2 diabetes mellitus (T2DM).

METHODS

Overall, 434 patients with T2DM admitted to Hebei General Hospital from January 2019 to December 2019 were selected as the study subjects. According to abdominal ultrasound findings, patients were divided into the NAFLD group and the non-NAFLD group. Participants were divided into two study groups according to the 25-hydroxyvitamin D [25(OH)D] level. 25(OH)D deficiency was defined if 25(OH)D vitamin levels were <20 ng/mL. Chi-square test and one-way analysis of variance were used to compare groups. The relationship between 25(OH)D and NAFLD risk was analyzed using correlation and regression analyses. Furthermore, subgroup analyses were performed to verify the robustness of the results.

RESULTS

The 25(OH)D level in patients with T2DM complicated by NAFLD was significantly lower than in patients with T2DM only. Vitamin D deficiency was highly prevalent among T2DM patients with NAFLD. This study suggested that vitamin D deficiency was an independent factor for developing NAFLD in patients with T2DM. T2DM patients with vitamin D deficiency had 2.045 times higher risk of developing NAFLD than those without vitamin D deficiency. Vitamin D deficiency was associated with high NAFLD preference in T2DM patients with BMI >23kg/m², but not those with BMI ≤23kg/m². The significant correlation between vitamin D deficiency and NAFLD was found in participants with BMI >23kg/m², age ≤65 years, without hypertension, TG <1.7mmol/l, HDL ≥1 mmol/l in men, ≥1.3 mmol/l in women, HBA1C ≤7%, or females.

CONCLUSION

This study suggests that T2DM people with BMI >23kg/m² were more susceptible to NAFLD by vitamin D deficiency and that it is necessary to maintain optimal serum vitamin D levels in this population.

Antidiabetic Function of Lactobacillus fermentum MF423-Fermented Rice Bran and Its Effect on Gut Microbiota Structure in Type 2 Diabetic Mice

Rice bran is an industrial byproduct that exerts several bioactivities despite its limited bioavailability. In this study, rice bran fermented with Lactobacillus fermentum MF423 (FLRB) had enhanced antidiabetic effects both in vitro and in vivo. FLRB could increase glucose consumption and decrease lipid accumulation in insulin resistant HepG2 cells. Eight weeks of FLRB treatment significantly reduced the levels of blood glucose and lipids and elevated antioxidant activity in type 2 diabetic mellitus (T2DM) mice. H&E staining revealed alleviation of overt lesions in the livers of FLRB-treated mice. Moreover, high-throughput sequencing showed notable variation in the composition of gut microbiota in FLRB-treated mice, especially for short-chain fatty acids (SCFAs)-producing bacteria such as Dubosiella and Lactobacillus. In conclusion, our results suggested that rice bran fermentation products can modulate the intestinal microbiota and improve T2DM-related biochemical abnormalities, so they can be applied as potential probiotics or dietary supplements.