The inhibition of inner mitochondrial fusion in hepatocytes reduces non-alcoholic fatty liver and improves metabolic profile during obesity by modulating bile acid conjugation

Natural bioactive compounds reprogram bile acid metabolism in MAFLD: Multi-target mechanisms and therapeutic implications

Metabolic-associated fatty liver disease (MAFLD) has become an increasingly prevalent liver disorder worldwide, being closely associated with obesity, metabolic syndrome, and insulin resistance. Bile acids (BAs), beyond their traditional role in lipid digestion, play a pivotal part in regulating lipid and glucose metabolism as well as inflammatory responses. Recent investigations have recognized BAs as key factors in the onset and progression of MAFLD, mainly via their interactions with nuclear receptors such as the farnesoid X receptor (FXR) and the G protein-coupled bile acid receptor (TGR5). Additionally, active compounds derived from traditional Chinese medicine (TCM) have shown promising potential in the treatment of MAFLD. This study systematically reviews and analyzes the molecular mechanisms and recent progress in the application of TCM active ingredients for MAFLD treatment, with a focus on their regulation of BAs. These active ingredients, including saponins, flavonoids, polysaccharides, and sterols, exert therapeutic effects through diverse mechanisms, such as modulating BA synthesis and mediating receptor-signaling pathways, and are expected to restore metabolic homeostasis.

Physical exercise ameliorates pain, mood alterations and neuroinflammation in a murine model of osteoarthritis

Osteoarthritis (OA) is largely associated with chronic pain, and it is a social and economic problem worldwide. OA pain can lead to psychiatric symptom onset, such as anxiety and depression. Emerging evidence suggest neuroinflammation as a common denominator between OA pain and mood disorders. OA pain pharmacological strategies are often ineffective or cause side effects, therefore, identifying novel non-pharmacological therapeutic approaches, like diet and exercise, could be important. Here, using 8-month-old male C57BL/6 J mice, we evaluated the effect of regular physical exercise on OA pain and related comorbidities. OA was induced by monoiodoacetate-(MIA) administration in knee joint in mice that had undergone physical exercise-(PE) or a sedentary lifestyle-(SL) for two months. After OA induction, mice continued the exercise/not-exercise protocol for another month and subsequently all animals were sacrificed. An in-depth biochemical evaluation (RT-qPCR) was performed at the level of the knee joint, sciatic nerve, dorsal root ganglia, spinal cord and brain areas (brainstem, hypothalamus and hippocampus) and myenteric plexus to evaluate the effect of both OA and exercise on (neuro)inflammation in regions involved in pain and mood regulation. Throughout the experimental protocol, pain-like behavior and motor performance were evaluated, and before sacrifice, mood alterations and metabolic changes were also assessed. Our results showed that OA_SL mice exhibit painful symptoms and mood disturbances. These alterations were also associated with (neuro)inflammation. PE mitigates pain-like behavior and mood alterations and reduces (neuro)inflammation, suggesting that a healthy and active lifestyle may have a positive impact in preventing and/or counteracting OA onset and related comorbidities.

Gut microbiota Lactobacillus johnsonii alleviates hyperuricemia by modulating intestinal urate and gut microbiota-derived butyrate

BACKGROUND

Gut microbiota are important for uric acid (UA) metabolism within hyperuricemia (HUA); however, the underlying mechanisms of how the gut microbiota regulate intestinal UA metabolism remain unclear. This study aimed to explore the function of the intestine in HUA and to further reveal the possible mechanism.

METHODS

We conducted gut microbiota depletion to validate the role of gut microbiota in UA metabolism. A mouse model of HUA was established, and the gut microbiota and microbiome-derived metabolites were analyzed via 16S RNA gene sequencing and metabolomics analysis. The mechanism of the gut microbiota in HUA was elucidated by in vivo and in vitro experiments.

RESULTS

Antibiotic treatment elevated serum UA, disturbed purine metabolism, and decreased the relative abundance of Lactobacillus. HUA mice had a lower relative abundance of Lactobacillus johnsonii (L. johnsonii) and decreased gut butyrate concentration. Supplementation of L. johnsonii significantly reduces serum UA in hyperuricemia mice by preventing UA synthesis and promoting the excretion of gut purine metabolites. In addition, L. johnsonii enhanced intestinal UA excretion by heightening the urate transporter ABCG2 (adenosine triphosphate-binding cassette transporter, subfamily G, member 2) expression, and increasing the levels of butyrate, which upregulated ABCG2 expression via the Wnt5a/b/β-catenin signaling pathway.

CONCLUSION

Our results suggest that gut microbiota and microbiota-derived metabolites directly regulate gut UA metabolism, highlighting potential applications in the treatment of diet-induced HUA by targeting gut microbiota and its metabolites.

High-fat diet restriction to adult male mice maintains normal body weight but leads to liver impairment by disrupting mitochondrial oxidative phosphorylation

Dietary restriction (DR) delays aging and supports health primarily through its effects on mitochondrial function. Conversely, a high-fat diet (HFD) with excess calories promotes obesity and health risks via mitochondrial dysfunction. However, the role of an HFD in the benefits of DR remains unclear. This study investigated whether sustainable and intermittent DR with an HFD positively affects liver and heart health. Mice were assigned to four groups: chow diet ad libitum (CTR), HFD ad libitum (H), 60% HFD intake (HDR), and intermittent HFD restriction with weight cycling (WC). The results showed that the mice in the HDR and WC groups had reduced body weight, while animals in neither group had lower blood glucose levels compared to the H group. Hepatic steatosis, fibrosis, and NAFLD activity scores were similar in H, HDR, and WC mice but were higher than in CTR mice. The livers of mice in the HDR and WC groups also showed reduced ATP content and altered protein expressions related to mitochondrial dynamics. Liver in animals from the H group exhibited reduced LC3I expression and an increased LC3II to LC3I ratio compared with liver CTR. In contrast, livers of animals in the HDR and WC groups showed lower levels of p62, LC3I, and LC3II expression. Fibrosis was observed in the hearts of mice in the CTR and H groups, and DR did not reverse this damage. In conclusion, although HFD restriction maintained body weight, it adversely affected liver health by disrupting mitochondrial function. These findings emphasize the critical role of dietary fat in liver health when adopting calorie-restricted therapy.

Mitochondrial Dysfunction as a Pathogenesis and Therapeutic Strategy for Metabolic-Dysfunction-Associated Steatotic Liver Disease

Metabolic-dysfunction-associated steatotic liver disease (MASLD) has emerged as a significant public health concern, attributed to its increasing prevalence and correlation with metabolic disorders, including obesity and type 2 diabetes. Recent research has highlighted that mitochondrial dysfunction can result in the accumulation of lipids in non-adipose tissues, as well as increased oxidative stress and inflammation. These factors are crucial in advancing the progression of MASLD. Despite advances in the understanding of MASLD pathophysiology, challenges remain in identifying effective therapeutic strategies targeting mitochondrial dysfunction. This review aims to consolidate current knowledge on how mitochondrial imbalance affects the development and progression of MASLD, while addressing existing research gaps and potential avenues for future research. This review was conducted after a systematic search of comprehensive academic databases such as PubMed, Embase, and Web of Science to gather information on mitochondrial dysfunction as well as mitochondrial-based treatments for MASLD.

Crosstalk Between Bile Acids and Intestinal Epithelium: Multidimensional Roles of Farnesoid X Receptor and Takeda G Protein Receptor 5

Bile acids and their corresponding intestinal epithelial receptors, the farnesoid X receptor (FXR), the G protein-coupled bile acid receptor (TGR5), play crucial roles in the physiological and pathological processes of intestinal epithelial cells. These acids and receptors are involved in the regulation of intestinal absorption, signal transduction, cellular proliferation and repair, cellular senescence, energy metabolism, and the modulation of gut microbiota. A comprehensive literature search was conducted using PubMed, employing keywords such as bile acid, bile acid receptor, FXR (nr1h4), TGR5 (gpbar1), intestinal epithelial cells, proliferation, differentiation, senescence, energy metabolism, gut microbiota, inflammatory bowel disease (IBD), colorectal cancer (CRC), and irritable bowel syndrome (IBS), with a focus on publications available in English. This review examines the diverse effects of bile acid signaling and bile receptor pathways on the proliferation, differentiation, senescence, and energy metabolism of intestinal epithelial cells. Additionally, it explores the interactions between bile acids, their receptors, and the microbiota, as well as the implications of these interactions for host health, particularly in relation to prevalent intestinal diseases. Finally, the review highlights the importance of developing highly specific ligands for FXR and TGR5 receptors in the context of metabolic and intestinal disorders.

Gut microbiota-mitochondrial crosstalk in obesity: novel mechanistic insights and therapeutic strategies with traditional Chinese medicine

Obesity rates are rising globally and have become a major public health issue. Recent research emphasizes the bidirectional communication between gut microbiota and mitochondrial function in obesity development. Gut microbiota regulates energy metabolism through metabolites that impact mitochondrial processes, such as oxidative phosphorylation, biogenesis, and autophagy. In turn, alterations in mitochondrial function impact microbiota homeostasis. Traditional Chinese medicine (TCM), which encompasses TCM formulas and the metabolites of botanical drugs, employs a holistic and integrative approach that shows promise in regulating gut microbiota-mitochondrial crosstalk. This review systematically explores the intricate interactions between gut microbiota and mitochondrial function, underscoring their crosstalk as a critical mechanistic axis in obesity pathogenesis. Furthermore, it highlights the potential of TCM in developing innovative, targeted interventions, paving the way for personalized approaches in obesity treatment through the precise modulation of gut microbiota-mitochondrial interactions, offering more effective and individualized therapeutic options.

Efficacy of In Vitro Addition of Low-Dose Arachidonic Acid in Improving the Sperm Motility of Obese Infertile Men With Asthenozoospermia

This study aimed to investigate the impact of in vitro low-dose arachidonic acid (AA) addition on enhancing sperm motility in obese infertile men with asthenozoospermia. Semen samples were collected from 115 infertile men, categorized into two BMI groups: 18.5-23.9 kg/m2 and ≥ 28 kg/m2, with all subjects demonstrating a sperm concentration of ≥ 15 × 106/mL. These were further divided into four cohorts based on the percentage of sperm progressive motility (PR): control-normal, control-asthenozoospermia, obese-normal, and obese-asthenozoospermia. Normal PR was classified as ≥ 32%, while asthenozoospermia was characterized by PR < 32%. Metabolomic analysis was employed to quantify seminal plasma metabolites, with differential metabolites identified through statistical evaluation. Additionally, semen samples from 10 infertile men-5 with a body mass index (BMI) of 18.5-23.9 kg/m2 and 5 with a BMI of ≥ 28 kg/m2-underwent further scrutiny. Post-initial semen analysis, 1 mL of semen stock was extracted, treated with 100 pg of AA, incubated at 37°C for 1 h, and reanalyzed to determine the impact on sperm motility. Additionally, 16 Sprague Dawley (SD) rats were split into two groups: control and obese. The control group received a standard diet, while the obese group was subjected to a 45% high-fat diet. After 3 months, the rats were euthanized via cervical dislocation, and their prostate and seminal vesicles were collected for metabolite analysis. A comprehensive analysis of 4635 metabolites in seminal plasma revealed that bile acid secretion emerged as the most significant pathway within the organic systems category, accounting for 0.6% of the total metabolites. Meanwhile, metabolic pathways overwhelmingly dominated the metabolism category, with AA metabolism contributing 4.62%. Notably, 29 metabolites were associated with bile acid secretion, yet no significant differences were observed between the PR ≥ 32% and < 32% groups. In contrast, 214 metabolites were linked to AA metabolism, exhibiting a predominantly downregulated trend, with no upregulated metabolites identified. Within the seminal plasma AA metabolic network, indicators showed a positive association with the induced acrosome reaction, seminal plasma Ca2+ levels, PR, and the proportion of grade A sperm (rapid forward motion, speed ≥ 25 μm/s). Additionally, secretory phospholipase A2 (sPLA2), AA, and cyclooxygenase-1 (COX1) levels demonstrated a negative correlation with anthropometric measurement parameters in the Control-SP group, though this correlation did not reach statistical significance, while a positive correlation was evident in the Obesity-SP group. The concentrations of sPLA2, AA, and COX1 within the AA metabolic network exhibited the following trend: Control-SP-N > Obesity-SP-N > Control-SP-A > Obesity-SP-A. In vitro addition of 100 pg AA significantly enhanced the proportion of grade B sperm (slow-moving, speed < 25 μm/s) while reducing grade C sperm (non-forward-moving) in individuals with a BMI of 18.5-23.9 kg/m2 (p < 0.05). In contrast, for those with a BMI ≥ 28 kg/m2, a marked increase in grade A and grade B sperm and a corresponding reduction in grade C sperm was noted (p < 0.05). Human seminal plasma levels of sPLA2, AA, and COX1 were significantly elevated in the Control-SP group compared to the Obesity-SP group (p < 0.05). However, sPLA2, AA, and COX1 levels in the prostate and seminal vesicle of SD rats did not differ significantly between the Control and Obesity groups (p > 0.05). Distinct metabolic profiles in seminal plasma of infertile men, stratified by BMI, exhibit significant impacts on sperm quality. Low-dose AA, under physiological conditions, maintains sperm integrity and augments fertilization potential. In vitro administration of low-dose AA demonstrates superior effectiveness in enhancing sperm parameters, particularly in obese individuals with asthenozoospermia.

ASGR1 deficiency improves atherosclerosis but alters liver metabolism in ApoE-/- mice

The asialoglycoprotein receptor 1 (ASGR1), a multivalent carbohydrate-binding receptor that primarily is responsible for recognizing and eliminating circulating glycoproteins with exposed galactose (Gal) or N-acetylgalactosamine (GalNAc) as terminal glycan residues, has been implicated in modulating the lipid metabolism and reducing cardiovascular disease burden. In this study, we investigated the impact of ASGR1 deficiency (ASGR1-/-) on atherosclerosis by evaluating its effects on plaque formation, lipid metabolism, circulating immunoinflammatory response, and circulating N-glycome under the hypercholesterolemic condition in ApoE-deficient mice. After 16 weeks of a western-type diet, ApoE-/-/ASGR1-/- mice presented lower plasma cholesterol and triglyceride levels compared to ApoE-/-. This was associated with reduced atherosclerotic plaque area and necrotic core formation. Interestingly, ApoE-/-/ASGR1-/- mice showed increased levels of circulating immune cells, increased AST/ALT ratio, and no changes in the N-glycome profile and liver morphology. The liver of ApoE-/-/ASGR1-/- mice, however, presented alterations in the metabolism of lipids, xenobiotics, and bile secretion, indicating broader alterations in liver homeostasis beyond lipids. These data suggest that improvements in circulating lipid metabolism and atherosclerosis in ASGR1 deficiency is paralleled by a deterioration of liver injury. These findings point to the need for additional evaluation before considering ASGR1 as a pharmacological target for dyslipidemia and cardiovascular disorders.

Profiling the impact of anti-human CD20 monoclonal antibodies on lymphocyte B cell subsets and their precursors in the bone marrow and in lymphoid tissues in an immunocompromised mouse engrafted with human cells

Ofatumumab (OFA) and ocrelizumab (OCRE) are two anti-CD20 monoclonal antibodies approved for the treatment of relapsing forms of multiple sclerosis due to their ability to deplete B lymphocytes. The aim of this study was to investigate the impact of these anti-hCD20 antibodies on B lymphocyte subsets in the circulation and in primary and secondary lymphoid organs in an immune system humanized mouse model (immunocompromised Rag2-/-Il2rg-/-CD47-/-) engrafted with human CD34+ hematopoietic stem cells. Three months after humanization, mice, which present adaptive immune cells only of human origin, were treated with OFA (0.3 mg/Kg; day 1, 3 and 5), or OCRE (10 mg/kg; day 1) or saline. Seven days after the last injection a robust (>90 %) decrease of circulating human CD20+ B lymphocytes was observed in both OFA- and OCRE-treated mice. A partial replenishment of B lymphocytes was detectable in blood 36 days from the last injection in OFA-treated mice, while no B lymphocytes could be detected in OCRE-treated mice up to 65 days post injection. Bone marrow profiling showed that during hCD20+ B cell depletion and replenishment, OCRE-treated mice preserved only preB-I cells in the bone marrow, while the bone marrow of OFA-treated mice presented both preB-I as well as preB-II cells, with the latter subset being the one closest to differentiate into immature B cells. These data together with changes in B cell distribution in other tissues suggest that ofatumumab preserve BM niches, critical for B lymphocyte replenishment, limiting potential side effects of the treatment associated with the increased risk of infection.

Is mitochondrial morphology important for cellular physiology?

Mitochondria are double membrane-bound organelles the network morphology of which in cells is shaped by opposing events of fusion and fission executed by dynamin-like GTPases. Mutations in these genes can perturb the form and functions of mitochondria in cell and animal models of mitochondrial diseases. An expanding array of chemical, mechanical, and genetic stressors can converge on mitochondrial-shaping proteins and disrupt mitochondrial morphology. In recent years, studies aimed at disentangling the multiple roles of mitochondrial-shaping proteins beyond fission or fusion have provided insights into the homeostatic relevance of mitochondrial morphology. Here, I review the pleiotropy of mitochondrial fusion and fission proteins with the aim of understanding whether mitochondrial morphology is important for cell and tissue physiology.

Altered Mitochondrial Function in MASLD: Key Features and Promising Therapeutic Approaches

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD), encompasses a range of liver conditions from steatosis to nonalcoholic steatohepatitis (NASH). Its prevalence, especially among patients with metabolic syndrome, highlights its growing global impact. The pathogenesis of MASLD involves metabolic dysregulation, inflammation, oxidative stress, genetic factors and, notably, mitochondrial dysfunction. Recent studies underscore the critical role of mitochondrial dysfunction in MASLD's progression. Therapeutically, enhancing mitochondrial function has gained interest, along with lifestyle changes and pharmacological interventions targeting mitochondrial processes. The FDA's approval of resmetirom for metabolic-associated steatohepatitis (MASH) with fibrosis marks a significant step. While resmetirom represents progress, further research is essential to understand MASLD-related mitochondrial dysfunction fully. Innovative strategies like gene editing and small-molecule modulators, alongside lifestyle interventions, can potentially improve MASLD treatment. Drug repurposing and new targets will advance MASLD therapy, addressing its increasing global burden. Therefore, this review aims to provide a better understanding of the role of mitochondrial dysfunction in MASLD and identify more effective preventive and treatment strategies.

ASGR1 deficiency diverts lipids toward adipose tissue but results in liver damage during obesity

BACKGROUND

Asialoglycoprotein receptor 1 (ASGR1), primarily expressed on hepatocytes, promotes the clearance and the degradation of glycoproteins, including lipoproteins, from the circulation. In humans, loss-of-function variants of ASGR1 are associated with a favorable metabolic profile and reduced incidence of cardiovascular diseases. The molecular mechanisms by which ASGR1 could affect the onset of metabolic syndrome and obesity are unclear. Therefore, here we investigated the contribution of ASGR1 in the development of metabolic syndrome and obesity.

METHODS

ASGR1 deficient mice (ASGR1-/-) were subjected to a high-fat diet (45% Kcal from fat) for 20 weeks. The systemic metabolic profile, hepatic and visceral adipose tissue were characterized for metabolic and structural alterations, as well as for immune cells infiltration.

RESULTS

ASGR1-/- mice present a hypertrophic adipose tissue with 41% increase in fat accumulation in visceral adipose tissue (VAT), alongside with alteration in lipid metabolic pathways. Intriguingly, ASGR1-/- mice exhibit a comparable response to an acute glucose and insulin challenge in circulation, coupled with notably decreased in circulating cholesterol levels. Although the liver of ASGR1-/- have similar lipid accumulation to the WT mice, they present elevated levels of liver inflammation and a decrease in mitochondrial function.

CONCLUSION

ASGR1 deficiency impacts energetic homeostasis during obesity leading to improved plasma lipid levels but increased VAT lipid accumulation and liver damage.