A gut microbial metabolite of linoleic acid ameliorates liver fibrosis by inhibiting TGF-β signaling in hepatic stellate cells

The Many Facets of PPAR-γ Agonism in Obesity and Associated Comorbidities: Benefits, Risks, Challenges, and Future Directions

PURPOSE OF REVIEW

Obesity is strongly associated with cardiometabolic disorders and certain malignancies, emphasizing the key role of adipose tissue in human health. While incretin mimetics have shown effectiveness in glycemic control and weight loss, a holistic strategy for combating obesity and associated comorbidities remains elusive. This review explores peroxisome proliferator-activated receptor gamma (PPAR-γ) agonism as a potential therapeutic approach, highlighting its benefits, addressing its limitations, and outlining future directions for developing more effective treatment strategies.

RECENT FINDINGS

Both natural and synthetic PPAR-γ agonists hold significant therapeutic potential as insulin sensitizers, while also demonstrating anti-inflammatory properties and playing a critical role in regulating lipid metabolism. However, the clinical use of natural agonists is limited by poor bioavailability, while synthetic agents like thiazolidinediones are associated with adverse effects, including fluid retention, weight gain, and bone loss. Current research is focused on developing modified, tissue-specific PPAR-γ agonists, as well as dual PPAR-α/PPAR-γ agonists, with improved safety profiles to mitigate these side effects. Nanotechnology-based drug delivery systems also hold promise for enhancing bioavailability and therapeutic efficacy. Furthermore, the transformative potential of machine learning and artificial intelligence offers opportunities to accelerate advancements in this field. PPAR-γ agonists exhibit significant potential in addressing metabolic syndrome, cardiovascular disease, and cancer. However, their clinical use is restricted by safety concerns and suboptimal pharmacokinetics. Innovations in modified PPAR-γ agonists, nanotechnology-based delivery systems, and computational tools hold promise for creating safer and more effective therapeutic options for obesity and its associated disorders.

Elucidating the role of gut microbiota metabolites in diabetes by employing network pharmacology

BACKGROUND

Extensive research has underscored the criticality of preserving diversity and equilibrium within the gut microbiota for optimal human health. However, the precise mechanisms by which the metabolites and targets of the gut microbiota exert their effects remain largely unexplored. This study utilizes a network pharmacology methodology to elucidate the intricate interplay between the microbiota, metabolites, and targets in the context of DM, thereby facilitating a more comprehensive comprehension of this multifaceted disease.

METHODS

In this study, we initially extracted metabolite information of gut microbiota metabolites from the gutMGene database. Subsequently, we employed the SEA and STP databases to discern targets that are intricately associated with these metabolites. Furthermore, we leveraged prominent databases such as Genecard, DisGeNET, and OMIM to identify targets related to diabetes. A protein-protein interaction (PPI) network was established to screen core targets. Additionally, we conducted comprehensive GO and KEGG enrichment analyses utilizing the DAVID database. Moreover, a network illustrating the relationship among microbiota-substrate-metabolite-target was established.

RESULTS

We identified a total of 48 overlapping targets between gut microbiota metabolites and diabetes. Subsequently, we selected IL6, AKT1 and PPARG as core targets for the treatment of diabetes. Through the construction of the MSMT comprehensive network, we discovered that the three core targets exert therapeutic effects on diabetes through interactions with 8 metabolites, 3 substrates, and 5 gut microbiota. Additionally, GO analysis revealed that gut microbiota metabolites primarily regulate oxidative stress, inflammation and cell proliferation. KEGG analysis results indicated that IL-17, PI3K/AKT, HIF-1, and VEGF are the main signaling pathways involved in DM.

CONCLUSION

Gut microbiota metabolites primarily exert their therapeutic effects on diabetes through the IL6, AKT1, and PPARG targets. The mechanisms of gut microbiota metabolites regulating DM might involve signaling pathways such as IL-17 pathways, HIF-1 pathways and VEGF pathways.

The role of ferroptosis-related non-coding RNA in liver fibrosis

Liver fibrosis represents a reversible pathophysiological process, caused by chronic inflammation stemming from hepatocyte damage. It delineates the initial stage in the progression of chronic liver disease. This pathological progression is characterized by the excessive accumulation of the extracellular matrix (ECM), which leads to significant structural disruption and ultimately impairs liver function. To date, no specific antifibrotic drugs have been developed, and advanced liver fibrosis remains largely incurable. Liver transplantation remains the sole efficacious intervention for advanced liver fibrosis; nevertheless, it is constrained by exorbitant costs and the risk of postoperative immune rejection, underscoring the imperative for novel therapeutic strategies. Ferroptosis, an emergent form of regulated cell death, has been identified as a pivotal regulatory mechanism in the development of liver fibrosis and is intricately linked with the progression of liver diseases. Recent investigations have elucidated that a diverse array of non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs, and circular RNAs, are involved in the ferroptosis pathway, thereby modulating the progression of various diseases, including liver fibrosis. In recent years, the roles of ferroptosis and ferroptosis-related ncRNAs in liver fibrosis have attracted escalating scholarly attention. This paper elucidates the pathophysiology of liver fibrosis, explores the mechanisms underlying ferroptosis, and delineates the involvement of ncRNA-mediated ferroptosis pathways in the pathology of liver fibrosis. It aims to propose novel strategies for the prevention and therapeutic intervention of liver fibrosis.

An Integrated Analysis of the Role of Gut Microbiome-Associated Metabolites in the Detection of MASH-Related Cirrhosis

BACKGROUND AND AIM

The prevalence and adverse outcomes of metabolic dysfunction associated with steatotic liver disease (MAFLD) are increasing. The changes in the gut microbiota and metabolites associated with metabolic dysfunction-associated steatohepatitis (MASH) are regarded as an essential part of the progression of MAFLD. This study aimed to identify the gut microbiota and metabolites involved in the development of MAFLD in patients.

METHOD

This study enrolled 90 patients (healthy controls, HC: n = 30; MASH: n = 30; MASH-related cirrhosis, MC: n = 30), and their fecal samples were collected for 16S rRNA sequencing and non-targeted LC-MS/MS metabolomics analysis. Data preprocessing and statistical analyses were performed using QIIME2 software, Pynast, QIIME2 package, Progenesis QI, and R program.

RESULTS

The abundance of Prevotellaceae at the family level and Prevotella at the genus level was lower in the MASH and NC samples than in the HC samples. Both Prevotellaceae and Prevotella showed the strongest correlation with MASH progression via random forest analysis. Untargeted metabolomics was used to quantitatively screen for discrepant metabolites in the stool samples from the three groups. Linolenic acid (LA)-related metabolite levels were significantly lower in MASH and NC samples. Associations between Prevotella- or LA-related metabolites and liver function were discovered. A high abundance of Prevotella was associated with LA-related metabolites and MASH.

CONCLUSION

This study identified that gut microbiota and metabolites are associated with MASH-related metabolic dysfunction. LA and Prevotella are depleted during MASH progression, and additional supplementation with Prevotella may be a potential strategy for the future treatment of MAFLD.

Circulating fatty acids and risk of severe non-alcoholic fatty liver disease in the UK biobank: a prospective cohort of 116 223 individuals

Fatty acid (FA) metabolism plays an important role in the development of nonalcoholic fatty liver disease (NAFLD). However, data on the relationship between circulating FAs and NAFLD risk are limited. This study aims to assess the associations between specific circulating FAs and severe NAFLD risk among the general population. Overall 116 223 participants without NAFLD and other liver diseases from the UK Biobank were enrolled between 2006 and 2010 and were followed up until the end of 2021. Plasma concentrations of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) were analyzed using an NMR-based biomarker profiling platform. Hazard ratios (HRs) and 95% confidence intervals (CIs) of NAFLD risk were estimated using Cox proportional-hazard models adjusted for other potential confounders. During a mean follow-up of 12.3 years, we documented 1394 cases of severe NAFLD. After multivariate adjustment, plasma SFAs and MUFAs were associated with a higher risk of severe NAFLD, whereas plasma n-3 PUFAs, n-6 PUFAs, and linoleic acid (LA) were associated with a lower risk. As compared with the lowest quartile, HRs (95% CIs) of severe NAFLD risk in the highest quartiles were 1.85 (1.45-2.36) for SFAs, 1.74 (1.23-2.44) for MUFAs, 0.79 (0.65-0.97) for n-3 PUFAs, 0.68 (0.48-0.96) for n-6 PUFAs, and 0.73 (0.54-0.99) for LA. The significant relationships were mainly mediated by serum TG for SFAs, HDL-C for MUFAs and n-6 PUFAs, and C-reactive protein for n-3 PUFAs. Plasma SFAs were associated with a more pronounced increase in the risk of severe NAFLD among participants with fewer SFA-associated alleles (P interaction = 0.032). Dietary recommendations for reducing plasma SFAs and MUFAs while increasing n-3 and n-6 PUFAs may be protective for severe NAFLD, which could be mediated by lipid metabolism and inflammation.

The Versatile Role of Peroxisome Proliferator-Activated Receptors in Immune-Mediated Intestinal Diseases

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that sense lipophilic molecules and act as transcription factors to regulate target genes. PPARs have been implicated in the regulation of innate immunity, glucose and lipid metabolism, cell proliferation, wound healing, and fibrotic processes. Some synthetic PPAR ligands are promising molecules for the treatment of inflammatory and fibrotic processes in immune-mediated intestinal diseases. Some of these are currently undergoing or have previously undergone clinical trials. Dietary PPAR ligands and changes in microbiota composition could modulate PPARs' activation to reduce inflammatory responses in these immune-mediated diseases, based on animal models and clinical trials. This narrative review aims to summarize the role of PPARs in immune-mediated bowel diseases and their potential therapeutic use.

Increased Odds of Metabolic Dysfunction-Associated Steatotic Liver Disease Are Linked to Reduced n-6, but Not n-3 Polyunsaturated Fatty Acids in Plasma

The increasing prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) underscores the need for better understanding of its complex pathogenesis. Lipid accumulation in hepatocytes is among principal mechanisms contributing to MASLD development. While routine lipid parameters are well studied, the profile of circulating fatty acids in MASLD patients remains less explored. This study aimed to assess relative proportions of individual fatty acids in plasma of MASLD patients and to explore their associations with other biochemical markers of MASLD. Ninety-one patients and 48 healthy individuals were enrolled. The relative proportions of fatty acids in plasma were determined using gas chromatography with FID detection. Proportions of total n-6 polyunsaturated fatty acids (PUFAs) and linoleic acid (LA) in plasma were lower in MASLD patients (p = 0.001 and p = 0.004, respectively), with no differences observed in n-3 PUFAs. Total plasma n-6 PUFAs correlated negatively with body mass index, hepatic steatosis indices, triglyceride concentration and coronary risk index. Decreased prevalence of n-6 PUFAs in plasma was independently associated with higher odds of MASLD (OR = 0.769; CI: 0.611-0.968; p = 0.025). Our findings indicate an altered circulatory fatty acid distribution in MASLD, characterized by a reduced amount of n-6 PUFAs, particularly LA, which may have significant implications for the prevention and treatment of MASLD.

Can essential fatty acids (EFAs) prevent and ameliorate post-COVID-19 long haul manifestations?

It is hypothesized that COVID-19, post-COVID and post-mRNA COVID-19 (and other related) vaccine manifestations including "long haul syndrome" are due to deficiency of essential fatty acids (EFAs) and dysregulation of their metabolism. This proposal is based on the observation that EFAs and their metabolites can modulate the swift immunostimulatory response of SARS-CoV-2 and similar enveloped viruses, suppress inappropriate cytokine release, possess cytoprotective action, modulate serotonin and bradykinin production and other neurotransmitters, inhibit NF-kB activation, regulate cGAS-STING pathway, modulate gut microbiota, inhibit platelet activation, regulate macrophage and leukocyte function, enhance wound healing and facilitate tissue regeneration and restore homeostasis. This implies that administration of EFAs could be of benefit in the prevention and management of COVID-19 and its associated complications.

Untargeted Metabolomics Based on UPLC-Q-Exactive-Orbitrap-MS/MS Revealed the Differences and Correlations between Different Parts of the Root of Paeonia lactiflora Pall

BACKGROUND

Paeonia lactiflora Pall. (PLP) is a plant with excellent ornamental and therapeutic value that can be utilized in traditional Chinese medicine as Paeoniae Radix Alba (PRA) and Paeoniae Radix Rubra (PRR). PRA must undergo the "peeling" process, which involves removing the cork and a portion of the phloem. PLP's biological function is strongly linked to its secondary metabolites, and the distribution of metabolites in different regions of the PLP rhizome causes changes in efficacy when PLP is processed into various therapeutic compounds.

METHODS

The metabolites of the cork (cor), phloem (phl), and xylem (xyl) were examined in the roots of PLP using a metabolomics approach based on UPLC-Q-Exactive-Orbitrap-MS/MS (UPLC-MS/MS), and the differential metabolites were evaluated using multivariate analysis.

RESULTS

Significant changes were observed among the cor, phl, and xyl samples. In both positive and negative ion modes, a total of 15,429 peaks were detected and 7366 metabolites were identified. A total of 525 cor-phl differential metabolites, 452 cor-xyl differential metabolites, and 328 phl-xyl differential metabolites were evaluated. Flavonoids, monoterpene glycosides, fatty acids, sugar derivatives, and carbohydrates were among the top 50 dissimilar chemicals. The key divergent metabolic pathways include linoleic acid metabolism, galactose metabolism, ABC transporters, arginine biosynthesis, and flavonoid biosynthesis.

CONCLUSION

The cor, phl, and xyl of PLP roots exhibit significantly different metabolite types and metabolic pathways; therefore, "peeling" may impact the pharmaceutical effect of PLP. This study represents the first metabolomics analysis of the PLP rhizome, laying the groundwork for the isolation and identification of PLP pharmacological activity, as well as the quality evaluation and efficacy exploration of PLP.