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

Unraveling the gut microbiota's role in obesity: key metabolites, microbial species, and therapeutic insights

Obesity, characterized by excessive fat accumulation, stems from an imbalance between energy intake and expenditure, with the gut microbiota playing a crucial role. This review highlights how gut microbiota influences metabolic pathways, inflammation, and adipose tissue regulation in obesity. Specific bacteria and metabolites, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), modulate gut permeability, inflammation, and energy harvest, impacting obesity development. Certain gut bacteria, including Clostridium XIVb, Dorea spp., Enterobacter cloacae, and Collinsella aerofaciens, promote obesity by increasing energy harvest, gut permeability, and inflammatory response through LPS translocation into the bloodstream. Conversely, beneficial bacteria like Akkermansia muciniphila, Lactobacillus spp., and Bifidobacterium spp. enhance gut barrier integrity, regulate SCFA production, and modulate fasting-induced adipose factor, which collectively support metabolic health by reducing fat storage and inflammation. Metabolites such as SCFAs (acetate, propionate, and butyrate) interact with G-protein coupled receptors to regulate lipid metabolism and promote the browning of white adipose tissue (WAT), thus enhancing thermogenesis and energy expenditure. However, LPS contributes to insulin resistance and fat accumulation, highlighting the dual roles of these microbial metabolites in both supporting and disrupting metabolic function. Therapeutic interventions targeting gut microbiota, such as promoting WAT browning and activating brown adipose tissue (BAT), hold promise for obesity management. However, personalized approaches are necessary due to individual microbiome variability. Further research is essential to translate these insights into microbiota-based clinical therapies.

Chronic Inflammation and Immune Dysregulation in Metabolic-Dysfunction-Associated Steatotic Liver Disease Progression: From Steatosis to Hepatocellular Carcinoma

Background/Objectives: Metabolic-dysfunction-associated steatotic liver disease (MASLD) progresses from hepatic steatosis to hepatocellular carcinoma (HCC) as a result of systemic immunometabolic dysfunction. This review summarizes the key roles of the innate and adaptive immune mechanisms driving hepatic injury, fibrogenesis, and carcinogenesis in MASLD. Methods: A comprehensive literature review was performed using PubMed to identify relevant published studies. Eligible articles included original research and clinical studies addressing immunological and metabolic mechanisms in MASLD, as well as emerging therapeutic strategies. Results: We highlight the roles of cytokine networks, the gut-liver axis, and immune cell reprogramming. Emerging therapeutic strategies, including cytokine inhibitors, anti-fibrotic agents, metabolic modulators, and nutraceuticals, offer several indications for attenuating MASLD progression and reducing the prevalence of extrahepatic manifestations. Conclusions: Given the heterogeneity of MASLD, personalized combination-based approaches targeting both inflammation and metabolic stress are essential for effective disease management and the prevention of systemic complications.

Causal relationship between metabolic dysfunction-associated fatty liver disease and endotoxin biomarkers: A Mendelian randomization study

Although the relationship among lipopolysaccharides (LPS), LPS-binding proteins, and metabolic dysfunction-associated fatty liver disease (MAFLD) is widely studied, no conclusive evidence is available. In this study, we used mendelian randomization (MR) to study the causal relationship of LPS, LPS-binding proteins, and MAFLD. Using bidirectional two-sample MR method, we evaluated data from the genome wide association study; for this analysis, nonalcoholic fatty liver disease (NAFLD), liver fat percentage, and other metabolic syndromes were employed as outcomes. Furthermore, MR analysis mainly involved the inverse variance weighted method. Heterogeneity and pleiotropy tests were also conducted. LPS was found to have a causal relationship with NAFLD, obesity, high density lipoprotein cholesterol, and TG levels. Furthermore, TG levels and LBP had significant causal relationships. This study mainly concluded that LPS is a risk factor for NAFLD, obesity, high density lipoprotein cholesterol, and TG, corroborating it's the LPS role in MAFLD pathogenesis. Hence, optimizing the gut microbiota using proper diet, probiotics, or fecal microbiota transplantation may help to reduce inflammation and (IR), thereby improving lipid and glucose metabolism disorders. Although a causal relationship between TG and LBP was observed, further studies are required to determine a specific mechanism.

Causal relationship between gut microbiota and metabolic syndrome: A bidirectional Mendelian randomization study

Metabolic syndromes (MetS) are complex metabolic disorders, the pathogenesis of which has not been fully elucidated. In recent years, the association between the gut microbiota and MetS has attracted widespread attention, but the causal relationship remains unclear. We performed a 2-sample Mendelian randomization analysis (MR) to examine whether the gut microbiota is causally related to MetS and its components to find a basis for potential diagnostic or intervention approaches for MetS. We utilized summary statistics from whole-genome association analyses of gut microbiota from the MiBioGen consortium and obtained MetS-related data from the UK Biobank, IEU Open GWAS project, and The Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC). MR analyses were performed using inverse variance weighted, MR-Egger, and weighted median. Sensitivity analyses were conducted to verify the robustness of the results. Among the 211 gut microbiota, we identified 8 that were significantly associated with the risk of MetS. Specifically, Lachnospiraceae (family), Veillonellaceae (family), Victivallaceae (family), Odoribacter (genus), and Olsenella (genus) may increase the risk of MetS, while Bifidobacteriaceae (family), Ruminococcaceae UCG-010 (genus), Actinobacteria (phylum) may decrease the risk of MetS. Additionally, we discovered that multiple microbiota are associated with various components of MetS, such as BMI, hypertension, and blood lipid levels. This study is the first to use MR methods to reveal the potential causal relationship between specific gut microbiota and MetS, providing a new perspective for understanding the pathogenesis of MetS, and offering important evidence for the development of gut microbiota-based prevention and treatment strategies for MetS.

Unraveling Metabolic Syndrome in Youth: The Obesity Epidemic's Hidden Complication

BACKGROUND/OBJECTIVES

One of the metabolic complications of obesity is known as Metabolic Syndrome (MetS). This narrative review aims to synthesize current research on MetS in young populations, identify knowledge gaps, and guide future studies and funding priorities. It provides evidence-based insights into screening, diagnosis, and treatment, offering practical guidance for healthcare professionals.

METHODS

A comprehensive search of the literature was conducted to identify relevant studies on obesity in MetS in PubMed and Google Academic electronic database. The search was performed using a combination of "obesity", "complications", "metabolic syndrome", "children", and "adolescents" keywords. Studies were selected based on predefined inclusion and exclusion criteria to ensure relevance and methodological rigor.

RESULTS

The lack of universally accepted diagnostic criteria for MetS in children has led to inconsistencies in its definition across medical literature. Irrespective of the chosen diagnostic approach, the prevalence of MetS in children and adolescents has exhibited a concurrent rise with the increasing rates of obesity in this age group. The pathophysiology of MetS remains incompletely understood, with ongoing discussions on the interplay of genetic, epigenetic, environmental, dietary, and lifestyle factors. Screening for MetS is recommended for overweight and obese children.

CONCLUSIONS

Establishing global, consensus-driven criteria that account for ethnicity, gender, and age would enhance diagnostic accuracy and treatment approaches. The prevention of excessive weight among children and adolescents stands as a paramount objective within modern society's healthcare system. Considering the complexity of the disease and the treatment, the team must be multidisciplinary.

Gut microbiota differences, metabolite changes, and disease intervention during metabolic - dysfunction - related fatty liver progression

In the current era, metabolic dysfunction-associated steatotic liver disease (MASLD) has gradually developed into a major type of chronic liver disease that is widespread globally. Numerous studies have shown that the gut microbiota plays a crucial and indispensable role in the progression of MASLD. Currently, the gut microbiota has become one of the important entry points for the research of this disease. Therefore, the aim of this review is to elaborate on the further associations between the gut microbiota and MASLD, including the changes and differences in the microbiota between the healthy liver and the diseased liver. Meanwhile, considering that metabolic dysfunction-associated fatty liver and metabolic dysfunction-associated steatohepatitis are abnormal pathological states in the development of the disease and that the liver exhibits different degrees of fibrosis (such as mild fibrosis and severe fibrosis) during the disease progression, we also conduct a comparison of the microbiota in these states and use them as markers of disease progression. It reveals the changes in the production and action mechanisms of short-chain fatty acids and bile acids brought about by changes in the gut microbiota, and the impact of lipopolysaccharide from Gram-negative bacteria on the disease. In addition, the regulation of the gut microbiota in disease and the production and inhibition of related disease factors by the use of probiotics (including new-generation probiotics) will be explored, which will help to monitor the disease progression of patients with different gut microbiota compositions in the future and carry out personalized targeted therapies for the gut microbiota. This will achieve important progress in preventing and combating this disease.

High-dose thiamine supplementation ameliorates obesity induced by a high-fat and high-fructose diet in mice by reshaping gut microbiota

Introduction

Thiamine (vitamin B1) in the gut is crucial for maintaining intestinal homeostasis and host health. Our previous study identified significantly lower levels of fecal thiamine in individuals with obesity; however, its potential and mechanisms for alleviating obesity induced by a high-fat and high-fructose diet (HFFD) remain unclear. Therefore, in the present study, the effects of high-dose thiamine supplementation on HFFD-induced obesity and gut microbiota dysbiosis were investigated.

Methods

HFFD-fed mice were supplemented with high-dose thiamine for eight weeks. Biochemical analysis and histological analysis were conducted to assess phenotypic changes. Fecal 16S rRNA gene sequencing was performed to analyze alterations in the gut microbiota.

Results

The results showed that high-dose thiamine supplementation for eight weeks could significantly alleviate symptoms of HFFD-induced obesity and improve HFFD-induced intestinal epithelial barrier dysfunction by enhancing the tight junction function. Furthermore, oral administration of high-dose thiamine also regulated HFFD-induced gut microbiota dysbiosis by reshaping its structure and composition of gut microbiota, such as increasing the relative abundance of Actinobacteria and Bifidobacterium pseudolongum, and reducing the relative abundance of Proteobacteria and Ruminococcus gnavus, accompanied by decreased level of gut-derived endotoxin. Finally, significant correlations were found between obesity-related phenotypes and gut microbiota through correlation analysis.

Conclusion

Our findings suggest that the potential mechanism by which high-dose thiamine supplementation alleviated HFFD-induced obesity might involve reshaping gut microbiota and restoring the intestinal barrier, thereby ameliorating gut microbiota-related endotoxemia.

Unraveling the Role of the Human Gut Microbiome in Health and Diseases

The human gut is a complex ecosystem that supports billions of living species, including bacteria, viruses, archaea, phages, fungi, and unicellular eukaryotes. Bacteria give genes and enzymes for microbial and host-produced compounds, establishing a symbiotic link between the external environment and the host at both the gut and systemic levels. The gut microbiome, which is primarily made up of commensal bacteria, is critical for maintaining the healthy host's immune system, aiding digestion, synthesizing essential nutrients, and protecting against pathogenic bacteria, as well as influencing endocrine, neural, humoral, and immunological functions and metabolic pathways. Qualitative, quantitative, and/or topographic shifts can alter the gut microbiome, resulting in dysbiosis and microbial dysfunction, which can contribute to a variety of noncommunicable illnesses, including hypertension, cardiovascular disease, obesity, diabetes, inflammatory bowel disease, cancer, and irritable bowel syndrome. While most evidence to date is observational and does not establish direct causation, ongoing clinical trials and advanced genomic techniques are steadily enhancing our understanding of these intricate interactions. This review will explore key aspects of the relationship between gut microbiota, eubiosis, and dysbiosis in human health and disease, highlighting emerging strategies for microbiome engineering as potential therapeutic approaches for various conditions.

Gut Microbiota and Metabolic Dysfunction-Associated Steatotic Liver Disease

Background: The gut microbiota constitutes a complex microorganism community that harbors bacteria, viruses, fungi, protozoa, and archaea. The human gut bacterial microbiota has been extensively proven to participate in human metabolism, immunity, and nutrient absorption. Its imbalance, namely "dysbiosis", has been linked to disordered metabolism. Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the features of deranged human metabolism and is the leading cause of liver cirrhosis and hepatocellular carcinoma. Thus, there is a pathophysiological link between gut dysbiosis and MASLD. Aims and Methods: We aimed to review the literature data on the composition of the human bacterial gut microbiota and its dysbiosis in MASLD and describe the concept of the "gut-liver axis". Moreover, we reviewed the approaches for gut microbiota modulation in MASLD treatment. Results: There is consolidated evidence of particular gut dysbiosis associated with MASLD and its stages. The model explaining the relationship between gut microbiota and the liver has a bidirectional organization, explaining the physiopathology of MASLD. Oxidative stress is one of the keystones in the pathophysiology of MASLD and fibrosis generation. There is promising and consolidated evidence for the efficacy of pre- and probiotics in reversing gut dysbiosis in MASLD patients, with therapeutic effects. Few yet encouraging data on fecal microbiota transplantation (FMT) in MASLD are available in the literature. Conclusions: The gut dysbiosis characteristic of MASLD is a key target in its reversal and treatment via diet, pre/probiotics, and FMT treatment. Oxidative stress modulation remains a promising target for MASLD treatment, prevention, and reversal.

Altitude shapes gut microbiome composition accounting for diet, thyroid hormone levels, and host genetics in a subterranean blind mole rat

The animal gut microbiome acts as a crucial link between the host and its environment, playing a vital role in digestion, metabolism, physiology, and fitness. Using 16S rRNA metabarcoding, we investigated the effect of altitude on the microbiome composition of Anatolian Blind Mole Rats (Nannospalax xanthodon) across six locations and three altitudinal groups. We also factored in the host diet, as well as host microsatellite genotypes and thyroid hormone levels. The altitude had a major effect on microbiome composition, with notable differences in the relative abundance of several bacterial taxa across elevations. Contrary to prior research, we found no significant difference in strictly anaerobic bacteria abundance among altitudinal groups, though facultatively anaerobic bacteria were more prevalent at higher altitudes. Microbiome alpha diversity peaked at mid-altitude, comprising elements from both low and high elevations. The beta diversity showed significant association with the altitude. Altitude had a significant effect on the diet composition but not on its alpha diversity. No distinct altitude-related genetic structure was evident among the host populations, and no correlation was revealed between the host genetic relatedness and microbiome composition nor between the host microbiome and the diet. Free thyroxine (FT4) levels increased almost linearly with the altitude but none of the bacterial ASVs were found to be specifically associated with hormone levels. Total thyroxine (TT4) levels correlated positively with microbiome diversity. Although we detected correlation between certain components of the thyroid hormone levels and the microbiome beta diversity, the pattern of their relationship remains inconclusive.

Biological aging accelerates hepatic fibrosis: Insights from the NHANES 2017-2020 and genome-wide association study analysis

INTRODUCTION AND OBJECTIVES

This study aimed to investigate the association between biological aging and liver fibrosis in patients with metabolic dysfunction-associated steatotic liver disease (MASLD).

MATERIALS AND METHODS

We analyzed NHANES 2017-2020 data to calculate phenotypic age. Hepatic steatosis and fibrosis were identified using controlled attenuation parameters (CAP), fatty liver index (FLI) and transient elastography (TE). The odds ratios (ORs) and 95 % confidence intervals (CI) for significant MASLD fibrosis were calculated using multivariate logistic regression, and subgroup analyses were performed. We explored the potential causal relationship between telomere length and liver fibrosis using Mendelian randomization (MR). Additionally, we used the expression quantitative trait loci (eQTL) method and GSE197112 data to identify genes related to liver fibrosis and senescence. Finally, the APOLD1 expression was validated using GSE89632.

RESULTS

Phenotypic age was associated with liver fibrosis occurrence in MASLD (OR = 1.08, 95 % CI 1.05-1.12). Subgroup analyses by BMI and age revealed differences. For obese or young to middle-aged MASLD patients, phenotypic age is significantly associated with liver fibrosis. (OR = 1.14, 95 % CI 1.10-1.18; OR = 1.07, 95 % CI 1.01-1.14 and OR = 1.14, 95 % CI 1.07-1.22). MR revealed a negative association between telomere length and liver fibrosis (IVW method: OR = 0.63288, 95 % CI 0.42498-0.94249). The gene APOLD1 was identified as a potential target through the intersection of the GEO dataset and eQTL genes.

CONCLUSIONS

This study emphasized the link between biological aging and fibrosis in young to middle-aged obese MASLD patients. We introduced phenotypic age as a clinical indicator and identified APOLD1 as a potential therapeutic target.

Advances in the pathophysiology, diagnosis and management of chronic diarrhoea from bile acid malabsorption: a systematic review

Bile acid malabsorption (BAM) is an important disorder of digestive pathophysiology as it generates chronic diarrhoea. This condition originates from intricate pathways involving bile acid synthesis and metabolism in the liver and gut, the composition of gut microbiota, enterohepatic circulation and key receptors as farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and the G-protein bile acid receptor-1 (GPBAR-1). Although symptoms can resemble those related to disorders of gut brain interaction, accurate diagnosis of BAM may greatly benefit the patient. The empiric diagnosis of BAM is primarily based on the clinical response to bile acid sequestrants. Specific tests including the 48-hour fecal bile acid test, serum levels of 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19), and the 75Selenium HomotauroCholic Acid Test (SeHCAT) are not widely available. Nevertheless, lack of diagnostic standardization of BAM may account for poor recognition and delayed management. Beyond bile acid sequestrants, therapeutic approaches include the use of FXR agonists, FGF19 analogues, glucagon-like peptide-1 (GLP-1) receptor agonists, and microbiota modulation. These novel agents can best make their foray into the therapeutic armamentarium if BAM does not remain a diagnosis of exclusion. Ignoring BAM as a specific condition may continue to contribute to increased healthcare costs and reduced quality of life. Here, we aim to provide a comprehensive review of the pathophysiology, diagnosis, and management of BAM.

The Possible Involvement of Glucagon-like Peptide-2 in the Regulation of Food Intake through the Gut-Brain Axis

Food intake regulation is a complex mechanism involving the interaction between central and peripheral structures. Among the latter, the gastrointestinal tract represents one of the main sources of both nervous and hormonal signals, which reach the central nervous system that integrates them and sends the resulting information downstream to effector organs involved in energy homeostasis. Gut hormones released by nutrient-sensing enteroendocrine cells can send signals to central structures involved in the regulation of food intake through more than one mechanism. One of these is through the modulation of gastric motor phenomena known to be a source of peripheral satiety signals. In the present review, our attention will be focused on the ability of the glucagon-like peptide 2 (GLP-2) hormone to modulate gastrointestinal motor activity and discuss how its effects could be related to peripheral satiety signals generated in the stomach and involved in the regulation of food intake through the gut-brain axis. A better understanding of the possible role of GLP-2 in regulating food intake through the gut-brain axis could represent a starting point for the development of new strategies to treat some pathological conditions, such as obesity.

Gut Microbiota Dysbiosis, Oxidative Stress, Inflammation, and Epigenetic Alterations in Metabolic Diseases

Gut dysbiosis, resulting from an imbalance in the gut microbiome, can induce excessive production of reactive oxygen species (ROS), leading to inflammation, DNA damage, activation of the immune system, and epigenetic alterations of critical genes involved in the metabolic pathways. Gut dysbiosis-induced inflammation can also disrupt the gut barrier integrity and increase intestinal permeability, which allows gut-derived toxic products to enter the liver and systemic circulation, further triggering oxidative stress, inflammation, and epigenetic alterations associated with metabolic diseases. However, specific gut-derived metabolites, such as short-chain fatty acids (SCFAs), lactate, and vitamins, can modulate oxidative stress and the immune system through epigenetic mechanisms, thereby improving metabolic function. Gut microbiota and diet-induced metabolic diseases, such as obesity, insulin resistance, dyslipidemia, and hypertension, can transfer to the next generation, involving epigenetic mechanisms. In this review, we will introduce the key epigenetic alterations that, along with gut dysbiosis and ROS, are engaged in developing metabolic diseases. Finally, we will discuss potential therapeutic interventions such as dietary modifications, prebiotics, probiotics, postbiotics, and fecal microbiota transplantation, which may reduce oxidative stress and inflammation associated with metabolic syndrome by altering gut microbiota and epigenetic alterations. In summary, this review highlights the crucial role of gut microbiota dysbiosis, oxidative stress, and inflammation in the pathogenesis of metabolic diseases, with a particular focus on epigenetic alterations (including histone modifications, DNA methylomics, and RNA interference) and potential interventions that may prevent or improve metabolic diseases.

Metabolic Syndrome and Psoriasis: Pivotal Roles of Chronic Inflammation and Gut Microbiota

In recent years, the incidence of metabolic syndrome (MS) has increased due to lifestyle-related factors in developed countries. MS represents a group of conditions that increase the risk of diabetes, cardiovascular diseases, and other severe health problems. Low-grade chronic inflammation is now considered one of the key aspects of MS and could be defined as a new cardiovascular risk factor. Indeed, an increase in visceral adipose tissue, typical of obesity, contributes to the development of an inflammatory state, which, in turn, induces the production of several proinflammatory cytokines responsible for insulin resistance. Psoriasis is a chronic relapsing inflammatory skin disease and is characterized by the increased release of pro-inflammatory cytokines, which can contribute to different pathological conditions within the spectrum of MS. A link between metabolic disorders and Psoriasis has emerged from evidence indicating that weight loss obtained through healthy diets and exercise was able to improve the clinical course and therapeutic response of Psoriasis in patients with obesity or overweight patients and even prevent its occurrence. A key factor in this balance is the gut microbiota; it is an extremely dynamic system, and this makes its manipulation through diet possible via probiotic, prebiotic, and symbiotic compounds. Given this, the gut microbiota represents an additional therapeutic target that can improve metabolism in different clinical conditions.

Gender-specific insights into the irritable bowel syndrome pathophysiology. Focus on gut dysbiosis and permeability

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder involving the brain-gut interaction. IBS is characterized by persistent abdominal pain and changes in bowel habits. IBS exerts significant impacts on quality of life and imposes huge economic costs. Global epidemiological data reveal variations in IBS prevalence, both globally and between genders, necessitating comprehensive studies to uncover potential societal and cultural influences. While the exact pathophysiology of IBS remains incompletely understood, the mechanism involves a dysregulation of the brain-gut axis, leading to disturbed intestinal motility, local inflammation, altered intestinal permeability, visceral sensitivity, and gut microbiota composition. We reviewed several gender-related pathophysiological aspects of IBS pathophysiology, by focusing on gut dysbiosis and intestinal permeability. This perspective paves the way to personalized and multidimensional clinical management of individuals with IBS.

Understanding how pre- and probiotics affect the gut microbiome and metabolic health

The gut microbiome, a complex assembly of microorganisms, significantly impacts human health by influencing nutrient absorption, the immune system, and disease response. These microorganisms form a dynamic ecosystem that is critical to maintaining overall well-being. Prebiotics and probiotics are pivotal in regulating gut microbiota composition. Prebiotics nourish beneficial bacteria and promote their growth, whereas probiotics help maintain balance within the microbiome. This intricate balance extends to several aspects of health, including maintaining the integrity of the gut barrier, regulating immune responses, and producing metabolites crucial for metabolic health. Dysbiosis, or an imbalance in the gut microbiota, has been linked to metabolic disorders such as type 2 diabetes, obesity, and cardiovascular disease. Impaired gut barrier function, endotoxemia, and low-grade inflammation are associated with toll-like receptors influencing proinflammatory pathways. Short-chain fatty acids derived from microbial fermentation modulate anti-inflammatory and immune system pathways. Prebiotics positively influence gut microbiota, whereas probiotics, especially Lactobacillus and Bifidobacterium strains, may improve metabolic outcomes, such as glycemic control in diabetes. It is important to consider strain-specific effects and study variability when interpreting these findings, highlighting the need for further research to optimize their therapeutic potential. The aim of this report is therefore to review the role of the gut microbiota in metabolic health and disease and the effects of prebiotics and probiotics on the gut microbiome and their therapeutic role, integrating a broad understanding of physiological mechanisms with a clinical perspective.

NAFLD/MASLD and the Gut-Liver Axis: From Pathogenesis to Treatment Options

Nonalcoholic fatty liver disease (NAFLD) poses an emerging threat topublic health. Nonalcoholic steatohepatitis (NASH) is reported to be the most rapidly rising cause of hepatocellular carcinoma in the western world. Recently, a new term has been proposed: metabolic dysfunction-associated steatotic liver disease (MASLD). The introduction of this new terminology has sparked a debate about the interchangeability of these terms. The pathogenesis of NAFLD/MASLD is thought to be multifactorial, involving both genetic and environmental factors. Among these factors, alterations in gut microbiota and gut dysbiosis have recently garnered significant attention. In this context, this review will further discuss the gut-liver axis, which refers to the bidirectional interaction between the human gut microbiota and the liver. Additionally, the therapeutic potential of probiotics, particularly next-generation probiotics and genetically engineered bacteria, will be explored. Moreover, the role of prebiotics, synbiotics, postbiotics, and phages as well as fecal microbiota transplantation will be analyzed. Particularly for lean patients with NAFLD/MASLD, who have limited treatment options, approaches that modify the diversity and composition of the gut microbiota may hold promise. However, due to ongoing safety concerns with approaches that modulate gut microbiota, further large-scale studies are necessary to better assess their efficacy and safety in treating NAFLD/MASLD.

Gut Microbiota and Sinusoidal Vasoregulation in MASLD: A Portal Perspective

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common condition with heterogeneous outcomes difficult to predict at the individual level. Feared complications of advanced MASLD are linked to clinically significant portal hypertension and are initiated by functional and mechanical changes in the unique sinusoidal capillary network of the liver. Early sinusoidal vasoregulatory changes in MASLD lead to increased intrahepatic vascular resistance and represent the beginning of portal hypertension. In addition, the composition and function of gut microbiota in MASLD are distinctly different from the healthy state, and multiple lines of evidence demonstrate the association of dysbiosis with these vasoregulatory changes. The gut microbiota is involved in the biotransformation of nutrients, production of de novo metabolites, release of microbial structural components, and impairment of the intestinal barrier with impact on innate immune responses, metabolism, inflammation, fibrosis, and vasoregulation in the liver and beyond. The gut-liver axis is a conceptual framework in which portal circulation is the primary connection between gut microbiota and the liver. Accordingly, biochemical and hemodynamic attributes of portal circulation may hold the key to better understanding and predicting disease progression in MASLD. However, many specific details remain hidden due to limited access to the portal circulation, indicating a major unmet need for the development of innovative diagnostic tools to analyze portal metabolites and explore their effect on health and disease. We also need to safely and reliably monitor portal hemodynamics with the goal of providing preventive and curative interventions in all stages of MASLD. Here, we review recent advances that link portal metabolomics to altered sinusoidal vasoregulation and may allow for new insights into the development of portal hypertension in MASLD.

Could Insulin Be a Better Regulator of Appetite/Satiety Balance and Body Weight Maintenance in Response to Glucose Exposure Compared to Sucrose Substitutes? Unraveling Current Knowledge and Searching for More Appropriate Choices

BACKGROUND

Insulin exerts a crucial impact on glucose control, cellular growing, function, and metabolism. It is partially modulated by nutrients, especially as a response to the intake of foods, including carbohydrates. Moreover, insulin can exert an anorexigenic effect when inserted into the hypothalamus of the brain, in which a complex network of an appetite/hunger control system occurs. The current literature review aims at thoroughly summarizing and scrutinizing whether insulin release in response to glucose exposure may be a better choice to control body weight gain and related diseases compared to the use of sucrose substitutes (SSs) in combination with a long-term, well-balanced diet.

METHODS

This is a comprehensive literature review, which was performed through searching in-depth for the most accurate scientific databases and applying effective and relevant keywords.

RESULTS

The insulin action can be inserted into the hypothalamic orexigenic/anorexigenic complex system, activating several anorexigenic peptides, increasing the hedonic aspect of food intake, and effectively controlling the human body weight. In contrast, SSs appear not to affect the orexigenic/anorexigenic complex system, resulting in more cases of uncontrolled body weight maintenance while also increasing the risk of developing related diseases.

CONCLUSIONS

Most evidence, mainly derived from in vitro and in vivo animal studies, has reinforced the insulin anorexigenic action in the hypothalamus of the brain. Simultaneously, most available clinical studies showed that SSs during a well-balanced diet either maintain or even increase body weight, which may indirectly be ascribed to the fact that they cannot cover the hedonic aspect of food intake. However, there is a strong demand for long-term longitudinal surveys to effectively specify the impact of SSs on human metabolic health.

Metabolic Dysfunction-Associated Steatotic Liver Disease: From Pathogenesis to Current Therapeutic Options

The epidemiological burden of liver steatosis associated with metabolic diseases is continuously growing worldwide and in all age classes. This condition generates possible progression of liver damage (i.e., inflammation, fibrosis, cirrhosis, hepatocellular carcinoma) but also independently increases the risk of cardio-metabolic diseases and cancer. In recent years, the terminological evolution from "nonalcoholic fatty liver disease" (NAFLD) to "metabolic dysfunction-associated fatty liver disease" (MAFLD) and, finally, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been paralleled by increased knowledge of mechanisms linking local (i.e., hepatic) and systemic pathogenic pathways. As a consequence, the need for an appropriate classification of individual phenotypes has been oriented to the investigation of innovative therapeutic tools. Besides the well-known role for lifestyle change, a number of pharmacological approaches have been explored, ranging from antidiabetic drugs to agonists acting on the gut-liver axis and at a systemic level (mainly farnesoid X receptor (FXR) agonists, PPAR agonists, thyroid hormone receptor agonists), anti-fibrotic and anti-inflammatory agents. The intrinsically complex pathophysiological history of MASLD makes the selection of a single effective treatment a major challenge, so far. In this evolving scenario, the cooperation between different stakeholders (including subjects at risk, health professionals, and pharmaceutical industries) could significantly improve the management of disease and the implementation of primary and secondary prevention measures. The high healthcare burden associated with MASLD makes the search for new, effective, and safe drugs a major pressing need, together with an accurate characterization of individual phenotypes. Recent and promising advances indicate that we may soon enter the era of precise and personalized therapy for MASLD/MASH.

Applications of Strain-Specific Probiotics in the Management of Cardiovascular Diseases: A Systemic Review

Cardiovascular diseases (CVDs) are a leading cause of global mortality and novel approaches for prevention and management are needed. The human gastrointestinal tract hosts a diverse microbiota that is crucial in maintaining metabolic homeostasis. The formulation of effective probiotics, alone or in combination, has been under discussion due to their impact on cardiovascular and metabolic diseases. Probiotics have been shown to impact cardiovascular health positively. An imbalance in the presence of Firmicutes and Bacteroidetes has been linked to the progression of CVDs due to their impact on bile acid and cholesterol metabolism. The probiotics primarily help in the reduction of plasma low-density lipoprotein levels and attenuation of the proinflammatory markers. These beneficial microorganisms contribute to lowering cholesterol levels and produce essential short-chain fatty acids. The impact of lipid-regulating probiotic strains on human health is quite significant. However, only a few have been tested for potential beneficial efficacy, and ambiguity exists regarding strain dosages, interactions with confounding factors, and potential adverse effects. Hence, more comprehensive studies and randomized trials are needed to understand the mechanisms of probiotics on CVDs and to ensure human health. This review assesses the evidence and highlights the roles of strain-specific probiotics in the management of CVDs.

Intestinal Effects of Filtered Alkalinized Water in Lean and Obese Zucker Rats

This study evaluated the intestinal effects of alkalinized filtered water in lean and obese adult Zucker rats. For 3 months, 12-week-old rats consumed either tap water or filtered alkalinized tap water from Madrid city. Weight gain was monitored, changes in metabolism were evaluated by indirect calorimetry, and total antioxidant capacity and levels of inflammatory mediators were measured in plasma. Feces were collected, their microbial composition was analyzed and histological analysis of the small and large intestine was performed, assessing the general state of the mucosa (MUC2), the inflammatory state (F4/80) and the presence of oxidative modifications in protein 4-Hydroxynonenal (4-HNE) by immunofluorescence (IF) and immunohistochemistry (IHC). The results obtained showed that the consumption of alkalinized filtered water improved the composition of the intestinal microbiome and the state of the intestinal mucosa, reducing both local and systemic inflammation and the level of oxidative stress. These changes were accompanied by a better maintenance of the oxidative status in rats. No differences were observed in antioxidant capacity nor in weight gain. The incorporation of probiotics in the diet had a significant impact on the microbiome. These effects were indicative of an improvement in general metabolic, oxidative and inflammatory status.