PPARs as Metabolic Sensors and Therapeutic Targets in Liver Diseases

Exercise-induced signaling activation by Chrysanthemum zawadskii and its active compound, linarin, ameliorates age-related sarcopenia through Sestrin 1 regulation

BACKGROUND

Exercise is an effective strategy to prevent sarcopenia, but high physical inactivity in the elderly requires alternative therapeutic approaches. Exercise mimetics are therapeutic compounds that simulate the beneficial effects of exercise on skeletal muscles. However, the toxicity and adverse effects of exercise mimetics raise serious concerns.

PURPOSE

We aimed to search novel plant-based alternatives to activate exercise induced-signaling.

METHODS

We used open databases and luciferase assays to identify plant-derived alternatives to activate exercise-induced signaling and compared its efficacy to mild intensity continuous training (MICT) in aged C57BL/6 mice. The nineteen-month-old mice were either fed an experimental diet supplemented with the isolated alternative or subjected to MICT for up to 21 mo of age.

RESULTS

Our analysis revealed that Chrysanthemum zawadskii Herbich var latillobum (Maxim.) Kitamura (CZH), a medicinal plant rich in linarin, is a novel activator of peroxisome proliferator-activated receptor δ (PPARδ) and estrogen-related receptor γ (ERRγ), key regulators of exercise-induced positive effects on muscles. CZH supplementation ameliorated the loss of muscle function and mass, and increased PPARδ and ERRγ expression in mouse muscles. CZH also improved mitochondrial functions and proteostasis in aged mice, similar to MICT. Furthermore, CZH and linarin induced the activation of Sestrin 1, a key mediator of exercise benefits, in muscle. Silencing Sestrin 1 negated the increase in myogenesis and mitochondrial respiration by CZH and linarin in primary myoblasts from old mice.

CONCLUSION

Our findings suggest the potential of CZH as a novel plant-derived alternative to activate exercise-induced signaling for preventing sarcopenia in sedentary older adults. This could offer a safer therapeutic option for sarcopenia treatment.

The effect of saraglitazar on TGF-β-induced smad3 phosphorylation and expression of genes related to liver fibrosis in LX2 cell line

BACKGROUND AND PURPOSE

Liver fibrosis is a reversible liver injury that occurs as a result of many chronic inflammatory diseases and can lead to cirrhosis, which is irreversible and fatal. So, we studied the anti-fibrotic effects of saroglitazar on LX-2 cell lines, as a dual PPARα/γ agonist.

METHODS

Cells, after 80% confluence, were treated with TGF-β (2 ng/mL) for 24 h. Then cells were treated with saroglitazar at different doses (2.5, 5, 10 µM) for 24 h. After same incubation, the cells of control group, TGF-β group, and TGF-β + saroglitazar group were harvested for RNA and protein extraction to determine the effects of saroglitazar. RT-PCR and western blot methods were used to express genes related to fibrosis.

RESULTS

Our results show that the relative expression of α-SMA, collagen1α, N-cadherin, NOX (1, 2, and 4), and phosphorylated Smad3 protein was significantly higher in TGF-β-treated cells compared with the normal group, and E-cadherin expression was decreased in TGF-β-treated cells. After TGF-β-treated cells were exposed to saroglitazar, the expression of these genes was significantly reversed (P < 0.05).

CONCLUSIONS

Our results clearly show the short-term inhibitory role of saroglitazar in the expression of fibrotic factors using the TGF-β/Smad signaling pathway. These results suggest that saroglitazar can be considered as a suitable therapeutic strategy for fibrotic patients. Although more studies are needed.

Identification of a novel FOXO3 agonist that protects against alcohol induced liver injury

Alcohol-related liver disease (ALD) is a global healthcare concern which caused by excessive alcohol consumption with limited treatment options. The pathogenesis of ALD is complex and involves in hepatocyte damage, hepatic inflammation, increased gut permeability and microbiome dysbiosis. FOXO3 is a well-recognized transcription factor which associated with longevity via promoting antioxidant stress response, preventing senescence and cell death, and inhibiting inflammation. We and many others have reported that FOXO3-/- mice develop more severe liver injury in response to alcohol. In the present study, we aimed to develop compounds that activate FOXO3 and further investigate their effects in alcohol induced liver injury. Through virtual screening, we discovered series of small molecular compounds that showed high affinity to FOXO3. We confirmed effects of compounds on FOXO3 target gene expression, as well as antioxidant and anti-apoptotic effects in vitro. Subsequently we evaluated the protective efficacy of compounds in alcohol induced liver injury in vivo. As a result, the leading compound we identified, 214991, activated downstream target genes expression of FOXO3, inhibited intracellular ROS accumulation and cell apoptosis induced by H2O2 and sorafenib. By using Lieber-DeCarli alcohol feeding mouse model, 214991 showed protective effects against alcohol-induced liver inflammation, macrophage and neutrophil infiltration, and steatosis. These findings not only reinforce the potential of FOXO3 as a valuable target for therapeutic intervention of ALD, but also suggested that compound 214991 as a promising candidate for the development of innovative therapeutic strategies of ALD.

Metabolic Flexibility of the Heart: The Role of Fatty Acid Metabolism in Health, Heart Failure, and Cardiometabolic Diseases

This comprehensive review explores the critical role of fatty acid (FA) metabolism in cardiac diseases, particularly heart failure (HF), and the implications for therapeutic strategies. The heart's reliance on ATP, primarily sourced from mitochondrial oxidative metabolism, underscores the significance of metabolic flexibility, with fatty acid oxidation (FAO) being a dominant source. In HF, metabolic shifts occur with an altered FA uptake and FAO, impacting mitochondrial function and contributing to disease progression. Conditions like obesity and diabetes also lead to metabolic disturbances, resulting in cardiomyopathy marked by an over-reliance on FAO, mitochondrial dysfunction, and lipotoxicity. Therapeutic approaches targeting FA metabolism in cardiac diseases have evolved, focusing on inhibiting or stimulating FAO to optimize cardiac energetics. Strategies include using CPT1A inhibitors, using PPARα agonists, and enhancing mitochondrial biogenesis and function. However, the effectiveness varies, reflecting the complexity of metabolic remodeling in HF. Hence, treatment strategies should be individualized, considering that cardiac energy metabolism is intricate and tightly regulated. The therapeutic aim is to optimize overall metabolic function, recognizing the pivotal role of FAs and the need for further research to develop effective therapies, with promising new approaches targeting mitochondrial oxidative metabolism and FAO that improve cardiac function.

Combined quercetin and simvastatin attenuate hepatic fibrosis in rats by modulating SphK1/NLRP3 pathways

Liver fibrosis involves several signalling pathways working in concert regulating the deposition of extracellular matrix. In this study, we evaluated the effect of quercetin and simvastatin alone and their combination on the treatment of experimentally induced hepatic fibrosis in rats. To decipher the potential mechanisms involved, liver fibrosis was induced in rats by administration of 40 % carbon tetrachloride (CCl4) (1 μl/g rat, i.p., twice weekly) for 6 weeks. Quercetin (50 mg/kg, orally), simvastatin (40 mg/kg, orally) either individually or combined were administered for another 4 weeks. The three treatment groups ameliorated hepatic dysfunction and altered parameters of sphingolipid and pyroptosis pathways. Yet, the combined group showed a more pronounced effect. Treatments lowered serum levels of GOT, GPT, ALP and elevated albumin and total protein levels. Histopathological and electron microscope examination of liver tissue revealed diminished fibrosis and inflammation. Protein expression levels of α-SMA, IL-1β, PPAR-γ, TGF-β1, caspase-1 and caspase-3 expression in liver tissues were reduced. Additionally, hepatic mRNA levels of SphK1 and NLRP3 decreased after treatment. Furthermore, the three groups lowered MDA levels and elevated total antioxidant capacity, GSH and Nrf2 expression levels. Treatments downregulated sphingolipid pathway and NLRP3-mediated pyroptosis and stimulated an anti-apoptotic, anti-proliferative and antioxidant activity. This suggests that targeting the SphK1/NLRP3 pathway could be a prospective therapeutic strategy against liver fibrosis.

An Overview of the Role of Peroxisome Proliferator-activated Receptors in Liver Diseases

Peroxisome proliferator-activated receptors (PPARs) are a superfamily of nuclear transcription receptors, consisting of PPARα, PPARγ, and PPARβ/δ, which are highly expressed in the liver. They control and modulate the expression of a large number of genes involved in metabolism and energy homeostasis, oxidative stress, inflammation, and even apoptosis in the liver. Therefore, they have critical roles in the pathophysiology of hepatic diseases. This review provides a general insight into the role of PPARs in liver diseases and some of their agonists in the clinic.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Effects of Foods of Mesoamerican Origin in Adipose Tissue and Liver-Related Metabolism

Adipose tissue and liver metabolism play a key role in maintaining body homeostasis; therefore, their impairment conduces a pathological state. Nowadays, occidental lifestyle is a common etiological issue among a variety of chronic diseases, while diet is a unique strategy to prevent obesity and liver metabolism impairment and is a powerful player in the treatment of metabolic-related diseases. Mesoamerican foods are rich in bioactive molecules that enhance and improve adipose tissue and liver performance and represent a prophylactic and therapeutic alternative for disorders related to the loss of homeostasis in the metabolism of these two important tissues.

Inflammatory signaling in NASH driven by hepatocyte mitochondrial dysfunctions

Liver steatosis, inflammation, and variable degrees of fibrosis are the pathological manifestations of nonalcoholic steatohepatitis (NASH), an aggressive presentation of the most prevalent chronic liver disease in the Western world known as nonalcoholic fatty liver (NAFL). Mitochondrial hepatocyte dysfunction is a primary event that triggers inflammation, affecting Kupffer and hepatic stellate cell behaviour. Here, we consider the role of impaired mitochondrial function caused by lipotoxicity during oxidative stress in hepatocytes. Dysfunction in oxidative phosphorylation and mitochondrial ROS production cause the release of damage-associated molecular patterns from dying hepatocytes, leading to activation of innate immunity and trans-differentiation of hepatic stellate cells, thereby driving fibrosis in NASH.

Breastfeeding-Related Health Benefits in Children and Mothers: Vital Organs Perspective

Breast milk (BM) is a constantly changing fluid that represents the primary source of nutrition for newborns. It is widely recognized that breastfeeding provides benefits for both the child and the mother, including a lower risk of ovarian and breast cancer, type 2 diabetes mellitus, decreased blood pressure, and more. In infants, breastfeeding has been correlated with a lower risk of infectious diseases, obesity, lower blood pressure, and decreased incidence of respiratory infections, diabetes, and asthma. Various factors, such as the baby's sex, the health status of the mother and child, the mother's diet, and the mode of delivery, can affect the composition of breast milk. This review focuses on the biological impact of the nutrients in BM on the development and functionality of vital organs to promote the benefit of health.

Nutrient sensors and their crosstalk

The macronutrients glucose, lipids, and amino acids are the major components that maintain life. The ability of cells to sense and respond to fluctuations in these nutrients is a crucial feature for survival. Nutrient-sensing pathways are thus developed to govern cellular energy and metabolic homeostasis and regulate diverse biological processes. Accordingly, perturbations in these sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Molecular sensors are the core within these sensing pathways and have a certain degree of specificity and affinity to sense the intracellular fluctuation of each nutrient either by directly binding to that nutrient or indirectly binding to its surrogate molecules. Once the changes in nutrient levels are detected, sensors trigger signaling cascades to fine-tune cellular processes for energy and metabolic homeostasis, for example, by controlling uptake, de novo synthesis or catabolism of that nutrient. In this review, we summarize the major discoveries on nutrient-sensing pathways and explain how those sensors associated with each pathway respond to intracellular nutrient availability and how these mechanisms control metabolic processes. Later, we further discuss the crosstalk between these sensing pathways for each nutrient, which are intertwined to regulate overall intracellular nutrient/metabolic homeostasis.

PPAR-γ signaling in nonalcoholic fatty liver disease: Pathogenesis and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD), currently the leading cause of global chronic liver disease, has emerged as a major public health problem, more efficient therapeutics of which are thus urgently needed. Peroxisome proliferator-activated receptor γ (PPAR-γ), ligand-activated transcription factors of the nuclear hormone receptor superfamily, is considered a crucial metabolic regulator of hepatic lipid metabolism and inflammation. The role of PPAR-γ in the pathogenesis of NAFLD is gradually being recognized. Here, we outline the involvement of PPAR-γ in the pathogenesis of NAFLD through adipogenesis, insulin resistance, inflammation, oxidative stress, endoplasmic reticulum stress, and fibrosis. In addition, the evidence for PPAR-γ- targeted therapy for NAFLD are summarized. Altogether, PPAR-γ is a promising therapeutic target for NAFLD, and the development of drugs that can balance the beneficial and undesirable effects of PPAR-γ will bring new light to NAFLD patients.

Coumestrol as a new substance that may diminish lipid precursors of the inflammation in steatotic primary rat hepatocytes

Coumestrol is a phytoestrogen found in various plant foods. Increasing evidence ascertained its robust anti-inflammatory, anti-oxidative properties likewise ability to mitigate insulin resistance. Thus, it may be a potential medicine in the treatment of many metabolic disorders, including obesity, type 2 diabetes (T2D) as well as non-alcoholic fatty liver disease (NAFLD). In this study, we aimed to shed some light on its influence on the accumulation of certain lipid fractions and the expression of pro-inflammatory proteins in primary rat hepatocytes during the lipid-overload state. The cells were isolated from the male Wistar rat's liver with the use of collagenase perfusion. It was followed by incubation of the cells with the presence or absence of palmitic acid and/or coumestrol. The accumulation of lipid fractions was assessed by gas-liquid chromatography (GLC) whereas the expression of the proteins was evaluated by the Western blot technique. Treatment with coumestrol in the state of increased fatty acids availability led to the deposition of triacylglycerols rather than diacylglycerols, significantly decreased expression of proinflammatory and profibrotic cytokines, especially interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), as well as transforming growth factor β (TGF-β), and nuclear factor κβ (NF-κβ). Also, we observed a substantial diminution in proinflammatory enzymes expression. Taking into consideration the direction of the aforementioned changes, we may assume that coumestrol can ameliorate the array of factors leading to the development of steatosis, likewise counteracting progression to steatohepatitis, thus it may be a step forward to the long-awaited breakthrough in the treatment of NAFLD.

Endocannabinoid-Binding Receptors as Drug Targets

Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century. In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB₁, CB₂, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV₁ and even nuclear receptors of the PPAR family. Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies. This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.

Exploring the Regulatory Role of ncRNA in NAFLD: A Particular Focus on PPARs

Liver diseases are responsible for global mortality and morbidity and are a significant cause of death worldwide. Consequently, the advancement of new liver disease targets is of great interest. Non-coding RNA (ncRNA), such as microRNA (miRNA) and long ncRNA (lncRNA), has been proven to play a significant role in the pathogenesis of virtually all acute and chronic liver disorders. Recent studies demonstrated the medical applications of miRNA in various phases of hepatic pathology. PPARs play a major role in regulating many signaling pathways involved in various metabolic disorders. Non-alcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease in the world, encompassing a spectrum spanning from mild steatosis to severe non-alcoholic steatohepatitis (NASH). PPARs were found to be one of the major regulators in the progression of NAFLD. There is no recognized treatment for NAFLD, even though numerous clinical trials are now underway. NAFLD is a major risk factor for developing hepatocellular carcinoma (HCC), and its frequency increases as obesity and diabetes become more prevalent. Reprogramming anti-diabetic and anti-obesity drugs is an effective therapy option for NAFLD and NASH. Several studies have also focused on the role of ncRNAs in the pathophysiology of NAFLD. The regulatory effects of these ncRNAs make them a primary target for treatments and as early biomarkers. In this study, the main focus will be to understand the regulation of PPARs through ncRNAs and their role in NAFLD.

The immune response as a therapeutic target in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a complex and heterogeneous disorder considered a liver-damaging manifestation of metabolic syndrome. Its prevalence has increased in the last decades due to modern-day lifestyle factors associated with overweight and obesity, making it a relevant public health problem worldwide. The clinical progression of NAFLD is associated with advanced forms of liver injury such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). As such, diverse pharmacological strategies have been implemented over the last few years, principally focused on metabolic pathways involved in NAFLD progression. However, a variable response rate has been observed in NAFLD patients, which is explained by the interindividual heterogeneity of susceptibility to liver damage. In this scenario, it is necessary to search for different therapeutic approaches. It is worth noting that chronic low-grade inflammation constitutes a central mechanism in the pathogenesis and progression of NAFLD, associated with abnormal composition of the intestinal microbiota, increased lymphocyte activation in the intestine and immune effector mechanisms in liver. This review aims to discuss the current knowledge about the role of the immune response in NAFLD development. We have focused mainly on the impact of altered gut-liver-microbiota axis communication on immune cell activation in the intestinal mucosa and the role of subsequent lymphocyte homing to the liver in NAFLD development. We further discuss novel clinical trials that addressed the control of the liver and intestinal immune response to complement current NAFLD therapies.

Physical exercise regulates apoptosis and prostatic inflammatory effects induced by high-fat diet in PPAR-alpha deleted mice

The high-fat diet (HFD) promotes obesity and develops inflammation, causing dysregulation of energy metabolism and prostatic neoplastic tissue changes. PPARɑ deletion leads to loss of homeostasis between the pro and anti-inflammatory response, and dysregulation of lipid metabolism, causing changes in different physiological processes and damage to the prostate. On the other hand, aerobic physical exercise has been suggested as a non-pharmacological tool to improve energy metabolism and cellular metabolism in the prostate, however, the underlying molecular mechanism remains unclear. the current study aimed to evaluate PPARα as a possible regulator of the protective effects of aerobic physical exercise in the prostate by examining prostatic alterations in wild-type and PPARα deletion mice fed a standard diet or an HFD. Wild-type and PPARα-null mice were fed a standard or HFD diet for 12 weeks, and submitted to aerobic physical exercise for 8 weeks. The HFD promoted the increase of inflammatory markers IL-6, TNF-α, NF-kB, and an increase of inflammatory foci in animals in both genotypes. Although the PPARα deletion animals submitted to the aerobic physical exercise were not able to regulate response pro-inflammatory, but promoted an increase in IL-10 in the prostate. In animals WT, the aerobic physical exercise, reduced all inflammatory markers, improve the inflammatory response, and showed a higher expression of BAX and IL-10 proteins was protective against prostatic tissue lesions. Suggested that PPARα deletion associated with HFD suppressed apoptosis and increased damage prostate. On other hand, aerobic physical exercise improves prostatic tissue by increasing the response to anti-inflammatory and apoptosis protein.

Host cell proteins modulated upon Toxoplasma infection identified using proteomic approaches: a molecular rationale

Toxoplasma gondii is a pathogenic protozoan parasite belonging to the apicomplexan phylum that infects the nucleated cells of warm-blooded hosts leading to an infectious disease known as toxoplasmosis. Apicomplexan parasites such as T. gondii can display different mechanisms to control or manipulate host cells signaling at different levels altering the host subcellular genome and proteome. Indeed, Toxoplasma is able to modulate host cell responses (especially immune responses) during infection to its advantage through both structural and functional changes in the proteome of different infected cells. Consequently, parasites can transform the invaded cells into a suitable environment for its own replication and the induction of infection. Proteomics as an applicable tool can identify such critical proteins involved in pathogen (Toxoplasma)-host cell interactions and consequently clarify the cellular mechanisms that facilitate the entry of pathogens into host cells, and their replication and transmission, as well as the central mechanisms of host defense against pathogens. Accordingly, the current paper reviews several proteins (identified using proteomic approaches) differentially expressed in the proteome of Toxoplasma-infected host cells (macrophages and human foreskin fibroblasts) and tissues (brain and liver) and highlights their plausible functions in the cellular biology of the infected cells. The identification of such modulated proteins and their related cell impact (cell responses/signaling) can provide further information regarding parasite pathogenesis and biology that might lead to a better understanding of therapeutic strategies and novel drug targets.

PPARs as Key Mediators in the Regulation of Metabolism and Inflammation

Nuclear receptors (NRs) form a large family of ligand-dependent transcription factors that control the expression of a multitude of genes involved in diverse, vital biological processes[…]

PPAR-Targeted Therapies in the Treatment of Non-Alcoholic Fatty Liver Disease in Diabetic Patients

Peroxisome proliferator-activated receptors (PPAR), ligand-activated transcription factors of the nuclear hormone receptor superfamily, have been identified as key metabolic regulators in the liver, skeletal muscle, and adipose tissue, among others. As a leading cause of liver disease worldwide, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) cause a significant burden worldwide and therapeutic strategies are needed. This review provides an overview of the evidence on PPAR-targeted treatment of NAFLD and NASH in individuals with type 2 diabetes mellitus. We considered current evidence from clinical trials and observational studies as well as the impact of treatment on comorbid metabolic conditions such as obesity, dyslipidemia, and cardiovascular disease. Future areas of research, such as possible sexually dimorphic effects of PPAR-targeted therapies, are briefly reviewed.

Lipid Metabolism Regulation Based on Nanotechnology for Enhancement of Tumor Immunity

The hallmarks of cancer include dysregulated metabolism and immune evasion. As a basic way of metabolism, lipid metabolism is reprogrammed for the rapid energy and nutrient supply in the occurrence and development of tumors. Lipid metabolism alterations that occur in the tumor microenvironment (TME) affect the antitumor responses of immune cells and cause immune evasion. Therefore, targeting lipid metabolism in the TME for enhancing the antitumor effect of immune cells is a promising direction for cancer treatment. Cancer nanomedicine has great potential in regulating tumor metabolism and tumor immunity. This review summarizes the nanotechnology-based strategies for lipid metabolism regulation in the TME for enhanced anticancer immune responses.

Uncovering the Potential of Lipid Drugs: A Focus on Transient Membrane Microdomain-Targeted Lipid Therapeutics

Membrane lipids are generally viewed as inert physical barriers, but many vital cellular processes greatly rely on the interaction with these structures, as expressed by the membrane hypothesis that explain the genesis of schizophrenia, Alzheimer's and autoimmune diseases, chronic fatigue or cancer, among others. The concept that the cell membrane displays transient membrane microdomains with distinct lipid composition provide the basis for the development of selective lipid-targeted therapies, the membrane-lipid therapies (MLTs). In this concern, medicinal chemists may design therapeutically valuable compounds 1) with a higher affinity for the lipids in these microdomains to restore the normal physiological conditions, 2) that can directly or 3) indirectly (via enzyme inhibition/activation) replace damaged lipids or restore the regular lipid levels in the whole membrane or microdomain, 4) that alter the expression of genes related to lipid genesis/metabolism or 5) that modulate the pathways related to the membrane binding affinity of lipid-anchored proteins. In this context, this mini-review aims to explore the structural diversity and clinical applications of some of the main membrane and microdomain-targeted lipid drugs.

Therapeutic developments in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become one of the most prevalent chronic liver diseases worldwide, bringing risk of multiorgan disfunctions including cardiovascular events, complications of cirrhosis, and even malignance. In terms of health burden management, screening patients with high risk of MAFLD and providing individual comprehensive treatment is critical. Although there are numerous agents entering clinical trials for MAFLD treatment every year, there is still no effective approved drug. The nomenclature of MAFLD highlighted the concomitant metabolic disorders and obesity. MAFLD patients with type 2 diabetes had higher risk of developing liver cirrhosis and cancer, and would benefit from anti-hyperglycemic agents; overweight and obese patients may benefit more from weight loss therapies; for patients with metabolic syndrome, individual comprehensive management is needed to reduce the risk of adverse outcomes. In this review, we introduced the current status and advances of the treatment of MAFLD based on weight loss, improving insulin resistance, and management of cardiometabolic disorders, in order to provide individualized therapy approaches for patients with MAFLD.

HA-20 prevents hepatocyte steatosis in metabolic-associated fatty liver disease via regulating Ca2+ relative signalling pathways

Metabolic-associated fatty liver disease (MAFLD) is caused by hepatocyte steatosis and is associated with obesity, type II diabetes, and heart disease. There are currently no effective drugs to treat MAFLD. This study explored the effect of HA-20, an oleanolic acid derivative, on hepatocyte steatosis in MAFLD. HepG2, L02, and AML12 cells were developed using oleic acid for in vitro MAFLD cell assays, and a high-fat diet + high-fructose diet-induced (HFHF) MAFLD mouse model was established for in vivo studies. The results demonstrated that HA-20 prevented hepatocyte steatosis in cell assays and caused 26.3, 57.7 and 70.0% inhibition of triglyceride (TG) levels in the 5.0, 10.0 and 20.0 μM HA-20 groups, respectively. The EC₅₀ values of HA-20 treatment in HepG2, L02 and AML12 cells were 9.7 ± 0.6 μM, 42.4 ± 3.5 μM and 71.0 ± 14.7 μM, respectively. HA-20 also prevented hepatocyte steatosis in the MAFLD mouse model, the liver triglyceride contents were 2.3 ± 0.4 and 1.5 ± 0.2 mmol/L in the 2.5 and 5.0 mg/kg/day HA-20 groups, lower than 6.2 ± 0.7 mmol/L in the HFHF group and 3.3 ± 0.4 mmol/L in the metformin group. Further mechanistic investigation revealed that HA-20 increased the phosphorylation of calmodulin-dependent protein kinase kinase (p-CaMKK) and the phosphorylation of AMP-activated protein kinase (p-AMPK), at least partially by increasing intracellular Ca²⁺ concentration, which suppressed lipogenesis and enhanced β-oxidation. Our findings provide new insight into preventing MAFLD by increasing Ca²⁺ and suggest that HA-20 possesses therapeutic potential for MAFLD management.

Fibrates for the Treatment of Primary Biliary Cholangitis Unresponsive to Ursodeoxycholic Acid: An Exploratory Study

Aim: Up to 40% of patients with primary biliary cholangitis (PBC) will have a suboptimal biochemical response to ursodeoxycholic acid (UDCA), which can be improved by the addition of fibrates. This exploratory study aims to evaluate the long-term real-life biochemical response of different fibrates, including ciprofibrate, in subjects with UDCA-unresponsive PBC.

Methods: The Brazilian Cholestasis Study Group multicenter database was reviewed to assess the response rates to UDCA plus fibrates in patients with UDCA-unresponsive PBC 1 and 2 years after treatment initiation by different validated criteria.

Results: In total, 27 patients (100% women, mean age 48.9 ± 9.2 years) with PBC were included. Overall response rates to fibrates by each validated criterion varied from 39 to 60% and 39–76% at 12 and 24 months after treatment combination, respectively. Combination therapy resulted in a significant decrease in ALT and ALP only after 2 years, while GGT significantly improved in the first year of treatment. Treatment response rates at 1 and 2 years appear to be comparable between ciprofibrate and bezafibrate using all available criteria.

Conclusion: Our findings endorse the efficacy of fibrate add-on treatment in PBC patients with suboptimal response to UDCA. Ciprofibrate appears to be at least as effective as bezafibrate and should be assessed in large clinical trials as a possibly new, cheaper, and promising option for treatment of UDCA-unresponsive PBC patients.

Withaferin A alleviates ethanol-induced liver injury by inhibiting hepatic lipogenesis

Withaferin A (WA) is a natural steroidal compound with reported hepatoprotective activities against various liver diseases. Whether WA has therapeutic effects on alcoholic liver disease has not been explored. A binge alcoholic liver injury model was employed by feeding C57BL/6J mice an ethanol (EtOH) diet for 10 days followed by an acute dose of EtOH to mimic clinical acute-upon-chronic liver injury. In this binge model, WA significantly reduced the binge EtOH-induced increase of serum aminotransaminase levels and decreased hepatic lipid accumulation. Mechanistically, WA decreased levels of hepatic lipogenesis gene mRNAs in vivo, including Srebp1c, Fasn, Acc1 and Fabp1. In EtOH-treated primary hepatocytes in vitro, WA decreased lipid accumulation by lowering the expression of the lipogenesis gene mRNAs Fasn and Acc1 as well as decreasing hepatocyte death. In the established binge alcoholic liver injury model, WA therapeutically reduced the EtOH-induced increase of serum aminotransaminase levels as well as hepatic lipid accumulation. These results demonstrate that WA reduces EtOH-induced liver injury by inhibiting hepatic lipogenesis, suggesting a potential therapeutic option for treating alcoholic liver injury.

Therapeutic potential of targeting regulatory mechanisms of hepatic stellate cell activation in liver fibrosis

Hepatic fibrosis is a manifestation of different etiologies of liver disease with the involvement of multiple mediators in complex network interactions. Activated hepatic stellate cells (aHSCs) are the central driver of hepatic fibrosis, given their potential to induce connective tissue formation and extracellular matrix (ECM) protein accumulation. Therefore, identifying the cellular and molecular pathways involved in the activation of HSCs is crucial in gaining mechanistic and therapeutic perspectives to more effectively target the disease. In addition to a comprehensive summary of our current understanding of the role of HSCs in liver fibrosis, we also discuss here the proposed therapeutic strategies based on targeting HSCs.