Myriocin modulates the altered lipid metabolism and storage in cystic fibrosis

Changes in microbial and metabolic profiles of mice fed with long-term high salt diet

PURPOSE

High salt diet (HSD) has been considered as a risk factor for the development of metabolic disorders. However, less is known about long-term implications of HSD. Therefore, the aim of this study was to conduct a preliminary investigation into the effects of mice feeding with long-term HSD on gut microbial and metabolic profiles.

METHODS

In this study, C57BL/6 J mice were fed with HSD for 22 weeks, after which fat and feces were collected. The composition of fecal microbiota was determined using 16S rRNA gene sequencing. Fecal metabolic profiling of mice was identified through untargeted ultrahigh-performance liquid chromatography-mass spectrometry. In addition, the serum levels of adipocytokines, including fibroblast growth factor 21 (FGF21) and adiponectin (APN), were measured.

RESULTS

Long-term HSD disrupted the growth performance of mice. Compared to those fed a normal salt diet, mice on a long-term HSD showed slower weight gain, as well as lower fat accumulation and serum levels of APN, while experiencing elevated blood pressure and levels of serum FGF21 and glucose. The 16S rRNA sequencing revealed changes in community richness and diversity, with long-term HSD affecting the abundance of certain gut microbiota, including Firmicutes, Christensenella, Barnesiella, and Lactococcus. Fecal metabolomic analysis also uncovered alterations in metabolites, such as myriocin, cerulenin, norcholic acid, 7-ketocholesterol, and prostaglandins B2. Further analysis indicated that these gut and microbiota and metabolites are predominantly involved in the lipid metabolism of the organism. Importantly, variations in these gut metabolites and microbiota were significantly correlated with body weight, fat accumulation, and the levels of FGF21 and APN.

CONCLUSION

Long-term HSD affects physiological traits, alters gut metabolites profiles, and impacts the composition and function of gut microbiota, thus causes a certain impact on lipid metabolism.

How Effectively Can Oxidative Stress and Inflammation Be Reversed When CFTR Function Is Pharmacologically Improved?

A critical challenge in the age of advanced modulator therapies is to understand and determine how effectively chronic oxidative stress and oxidative stress-induced inflammation can be reversed and physiological balance restored when CFTR function is pharmacologically improved. The triple therapy with elexacaftor-tezacaftor-ivacaftor (ETI) suggests that CFTR activity in individuals with at least one F508del mutation can be partially restored to about 50% of normal levels. Although incomplete, the partial recovery of CFTR function has been shown to drastically lower sputum pathogen content, enhance microbiome diversity, and lower inflammation markers within the first year of treatment in adolescents and adults with cystic fibrosis. However, despite these advancements, residual airway infection, oxidative stress and inflammation persist, with levels similar to other chronic lung conditions, like non-CF bronchiectasis. This persistence highlights the necessity for innovative antioxidant and anti-inflammatory treatments, in particular for individuals with advanced lung disease. To address this issue, emerging multi-omics technologies offer valuable tools to investigate the impact of modulator therapies on various molecular pathways. By analyzing changes in gene expression, epigenetic modifications, protein profiles and metabolic processes in airway-derived samples, it could be possible to uncover the mechanisms driving persistent oxidative stress and inflammation. These insights could pave the way for identifying new therapeutic targets to fully restore airway health and overall physiological balance.

Acid Sphingomyelinase Regulates AdipoRon-Induced Differentiation of Arterial Smooth Muscle Cells via TFEB Activation

AdipoRon is a selective adiponectin receptor agonist that inhibits vascular remodeling by promoting the differentiation of arterial smooth muscle cells (SMCs). Our recent studies have demonstrated that activation of TFEB and its downstream autophagy-lysosomal signaling contribute to adipoRon-induced differentiation of SMCs. The present study was designed to examine whether acid sphingomyelinase (ASM; gene symbol Smpd1) is involved in mediating adipoRon-induced activation of TFEB-autophagy signaling and inhibition of proliferation/migration in arterial SMCs. Our results showed that adipoRon induced ASM expression and ceramide production in Smpd1+/+ SMCs, which were abolished in Smpd1-/- SMCs. Compared to Smpd1+/+ SMCs, Smpd1-/- SMCs exhibited less TFEB nuclear translocation and activation of autophagy signaling induced by adipoRon stimulation. SMC differentiation was further characterized by retarded wound healing, reduced proliferation, F-actin reorganization, and MMP downregulation. The results showed that Smpd1-/- SMCs were less responsive to adipoRon-induced differentiation than Smpd1+/+ SMCs. Mechanistically, adipoRon increased the expression of protein phosphatases such as calcineurin and PP2A in Smpd1+/+ SMCs. The calcineurin inhibitor FK506/cyclosporin A or PP2A inhibitor okadaic acid significantly attenuated adipoRon-induced activation of TFEB-autophagy signaling. In addition, adipoRon-induced expressions of calcineurin and PP2A were not observed in Smpd1-/- SMCs. However, activation of calcineurin by lysosomal TRPML1-Ca2+ channel agonist ML-SA1 rescued the activation of TFEB-autophagy signaling and the effects of adipoRon on cell differentiation in Smpd1-/- SMCs. Taken together, these data suggested that ASM regulates adipoRon-induced SMC differentiation through TFEB activation. This study provided novel mechanistic insights into the therapeutic effects of adipoRon on TFEB signaling and pathological vascular remodeling.

Use of Myriocin as co-adjuvant in glaucoma surgery: An in vitro study

Mitomycin C as well as other antiproliferative drugs are off-label agents widely used to prevent the failure of glaucoma surgery due to activation of Tenon's fibroblasts and the ensuing excessive subconjunctival scarring. Though efficacious, these treatments are associated with some severe long-term complications, so it is crucial to investigate less cytotoxic compounds as adjuvant therapy in glaucoma surgery. The aim of this study was to evaluate the effect and potential cytotoxicity of Myriocin, a natural sphingolipid synthesis inhibitor, on TGF-β1-induced myofibroblasts transformation of human dermal fibroblasts. We found that myriocin significantly attenuated the transcript levels of αSMA, CTGF, and MMP9 which are involved in the fibrosis process. Mitomycin C poorly affects the same pro-fibrotic markers while reducing fibroblasts motility as much as myriocin. At similar doses, five minutes of mitomycin C treatment consistently affects human dermal fibroblast viability and proliferation compared to prolonged myriocin application, strengthening already published data on the good tolerability of this natural compound. Our results draw attention to the use of myriocin as an adjuvant in glaucoma surgery due to the effectiveness in reducing fibroblasts to myofibroblasts transformation and the low cytotoxicity.

Understanding the molecular regulatory mechanisms of autophagy in lung disease pathogenesis

Lung disease development involves multiple cellular processes, including inflammation, cell death, and proliferation. Research increasingly indicates that autophagy and its regulatory proteins can influence inflammation, programmed cell death, cell proliferation, and innate immune responses. Autophagy plays a vital role in the maintenance of homeostasis and the adaptation of eukaryotic cells to stress by enabling the chelation, transport, and degradation of subcellular components, including proteins and organelles. This process is essential for sustaining cellular balance and ensuring the health of the mitochondrial population. Recent studies have begun to explore the connection between autophagy and the development of different lung diseases. This article reviews the latest findings on the molecular regulatory mechanisms of autophagy in lung diseases, with an emphasis on potential targeted therapies for autophagy.

New Therapeutic Options in Pulmonal Diseases: Sphingolipids and Modulation of Sphingolipid Metabolism

Sphingolipids are crucial molecules in the respiratory airways. As in most other tissues and organs, in the lung sphingolipids play an essential role as structural constituents as they regulate barrier function and fluidity of cell membranes. A lung-specific feature is the occurrence of sphingolipids as minor structural components in the surfactant. However, sphingolipids are also key signaling molecules involved in airway cell signaling and their dynamical formation and metabolism are important for normal lung physiology. Dysregulation of sphingolipid metabolism and signaling is involved in altering lung tissue and initiates inflammatory processes promoting the pathogenesis of pulmonal diseases including cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and asthma.In the present review, the important role of specific sphingolipid species in pulmonal diseases will be discussed. Only such an understanding opens up the possibility of developing new therapeutic strategies with the aim of correcting the imbalance in sphingolipid metabolism and signaling. Such delivery strategies have already been studied in animal models of these lung diseases, demonstrating that targeting the sphingolipid profile represents new therapeutic opportunities for lung disorders.

Ceramide present in cholangiocarcinoma-derived extracellular vesicle induces a pro-inflammatory state in monocytes

Cholangiocarcinoma (CCA) is a rare cancer characterized by a global increasing incidence. Extracellular vesicles (EV) contribute to many of the hallmarks of cancer through transfer of their cargo molecules. The sphingolipid (SPL) profile of intrahepatic CCA (iCCA)-derived EVs was characterized by liquid chromatography-tandem mass spectrometry analysis. The effect of iCCA-derived EVs as mediators of inflammation was assessed on monocytes by flow cytometry. iCCA-derived EVs showed downregulation of all SPL species. Of note, poorly-differentiated iCCA-derived EVs showed a higher ceramide and dihydroceramide content compared with moderately-differentiated iCCA-derived EVs. Of note, higher dihydroceramide content was associated with vascular invasion. Cancer-derived EVs induced the release of pro-inflammatory cytokines in monocytes. Inhibition of synthesis of ceramide with Myriocin, a specific inhibitor of the serine palmitoyl transferase, reduced the pro-inflammatory activity of iCCA-derived EVs, demonstrating a role for ceramide as mediator of inflammation in iCCA. In conclusion, iCCA-derived EVs may promote iCCA progression by exporting the excess of pro-apoptotic and pro-inflammatory ceramides.

Gemfibrozil-Induced Intracellular Triglyceride Increase in SH-SY5Y, HEK and Calu-3 Cells

Gemfibrozil is a drug that has been used for over 40 years to lower triglycerides in blood. As a ligand for peroxisome proliferative-activated receptor-alpha (PPARα), which is expressed in many tissues, it induces the transcription of numerous genes for carbohydrate and lipid-metabolism. However, nothing is known about how intracellular lipid-homeostasis and, in particular, triglycerides are affected. As triglycerides are stored in lipid-droplets, which are known to be associated with many diseases, such as Alzheimer's disease, cancer, fatty liver disease and type-2 diabetes, treatment with gemfibrozil could adversely affect these diseases. To address the question whether gemfibrozil also affects intracellular lipid-levels, SH-SY5Y, HEK and Calu-3 cells, representing three different metabolically active organs (brain, lung and kidney), were incubated with gemfibrozil and subsequently analyzed semi-quantitatively by mass-spectrometry. Importantly, all cells showed a strong increase in intracellular triglycerides (SH-SY5Y: 170.3%; HEK: 272.1%; Calu-3: 448.1%), suggesting that the decreased triglyceride-levels might be due to an enhanced cellular uptake. Besides the common intracellular triglyceride increase, a cell-line specific alteration in acylcarnitines are found, suggesting that especially in neuronal cell lines gemfibrozil increases the transport of fatty acids to mitochondria and therefore increases the turnover of fatty acids for the benefit of additional energy supply, which could be important in diseases, such as Alzheimer's disease.

Bromelain Ameliorates Atherosclerosis by Activating the TFEB-Mediated Autophagy and Antioxidant Pathways

Bromelain, a cysteine protease found in pineapple, has beneficial effects in the treatment of inflammatory diseases; however, its effects in cardiovascular pathophysiology are not fully understood. We investigated the effect of bromelain on atherosclerosis and its regulatory mechanisms in hyperlipidemia and atheroprone apolipoprotein E-null (apoe-/-) mice. Bromelain was orally administered to 16-week-old male apoe-/- mice for four weeks. Daily bromelain administration decreased hyperlipidemia and aortic inflammation, leading to atherosclerosis retardation in apoe-/- mice. Moreover, hepatic lipid accumulation was decreased by the promotion of cholesteryl ester hydrolysis and autophagy through the AMP-activated protein kinase (AMPK)/transcription factor EB (TFEB)-mediated upregulation of autophagy- and antioxidant-related proteins. Moreover, bromelain decreased oxidative stress by increasing the antioxidant capacity and protein expression of antioxidant proteins while downregulating the protein expression of NADPH oxidases and decreasing the production of reactive oxygen species. Therefore, AMPK/TFEB signaling may be crucial in bromelain-mediated anti-hyperlipidemia, antioxidant, and anti-inflammatory effects, effecting the amelioration of atherosclerosis.

Tea Tree Oil Mediates Antioxidant Factors Relish and Nrf2-Autophagy Axis Regulating the Lipid Metabolism of Macrobrachium rosenbergii

Both oxidative stress and autophagy refer to regulating fat metabolism, and the former affects autophagy, but the role and mechanism of the antioxidant-autophagy axis in regulating lipid metabolism remains unclear. As an antioxidant, tea tree oil (TTO) has little research on the regulatory mechanism of lipid metabolism in crustaceans. This study investigated whether TTO could alter hepatopancreatic lipid metabolism by affecting the antioxidant-autophagy axis. Feed Macrobrachium rosenbergii with three different levels of TTO diets for 8 weeks: CT (0 mg/kg TTO), 100TTO (100 mg/kg TTO), and 1000TTO (1000 mg/kg TTO). The results showed that 100TTO treatment reduced the hemolymph lipids level and hepatopancreatic lipid deposition compared to CT. In contrast, 1000TTO treatment increased hepatopancreatic lipid deposition, damaging both morphology and function in the hepatopancreas. The 100TTO treatment promoted lipolysis and reduced liposynthesis at the transcriptional level compared to the CT group. Meanwhile, it improved the hepatopancreas antioxidant capacity and maintained mitochondrial structural and ROS homeostasis. In addition, it simultaneously activated the expression of transcription factors Keap1-Nrf2 and Imd-Relish. By contrast, the 1000TTO group significantly enhanced the ROS level, which considerably activated the Keap1-Nrf2 signaling expression but had no significant effects on the expression of Imd-Relish. The 100TTO group supplementation significantly enhanced lipid droplet breakdown and autophagy-related genes and protein expression. On the contrary, the 1000TTO group significantly inhibited the expression of genes and proteins related to autophagy. Pearson analysis revealed that Nrf2 has a positive correlation to lipid anabolism-related genes (Fasn, Srebp1, Pparγ) and autophagy regulators (mtor, akt, p62), and were negatively correlated with lipolysis-related genes (Cpt1, Hsl, Ampkα) and autophagy markers (Ulk1, Lc3). Relish was positively correlated with Atgl, Cpt1, Ampkα, Ulk1, and Lc3, and negatively correlated with Pparγ and p62. Moreover, Keap1 and Imd were negatively correlated with p62 and mtor, respectively. In sum, 100 mg/kg TTO enhanced antioxidant activity and increased autophagy intensity through the Relish-Imd pathway to enhance lipid droplet breakdown, while 1000 mg/kg TTO overexpressed Nrf2, thus inhibiting autophagy and ultimately causing excessive lipid deposition and peroxidation. Our study gives a fresh perspective for deciphering the bidirectional regulation mechanism of lipid metabolism by different doses of TTO based on the antioxidant-autophagy axis.

Cystic Fibrosis and Oxidative Stress: The Role of CFTR

There is substantial evidence in the literature that patients with cystic fibrosis (CF) have higher oxidative stress than patients with other diseases or healthy subjects. This results in an increase in reactive oxygen species (ROS) and in a deficit of antioxidant molecules and plays a fundamental role in the progression of chronic lung damage. Although it is known that recurrent infection-inflammation cycles in CF patients generate a highly oxidative environment, numerous clinical and preclinical studies suggest that the airways of a patient with CF present an inherently abnormal proinflammatory milieu due to elevated oxidative stress and abnormal lipid metabolism even before they become infected. This could be directly related to cystic fibrosis transmembrane conductance regulator (CFTR) deficiency, which appears to produce a redox imbalance in epithelial cells and extracellular fluids. This review aims to summarize the main mechanism by which CFTR deficiency is intrinsically responsible for the proinflammatory environment that characterizes the lung of a patient with CF.

Targeting of gallbladder megalin receptors with DHA-conjugated limonene albumin nanoparticles

Gallbladder stones are a major pathogenic factor leading to cholecystitis, and it is increasingly important to explore innovative drug delivery methods for gallstones. In the present study, docosahexaenoic acid-coupled limonene bovine serum albumin nanoparticles (LIM-DHA-BSA-NPs) were constructed. The LIM-DHA-BSA-NPs are spherical structures, and the distribution was relatively uniform, and, more importantly, it has low cytotoxicity and good safety. The LIM-DHA-BSA-NPs solution shows higher uptake rates by RAW264.7 cells when compared with free limonene (LIM). The fluorescence intensity of FITC-modified BSA NPs was significantly higher than that of free FITC, which further indicated that the uptake of DHA-conjugated BSA NPs by RAW264.7 cells was stronger than that of the free drugs. Moreover, the in vivo distribution experiment showed that the enrichment of DiD-loaded BSA NPs in the gallbladder was significantly enhanced when compared with that of free DiD. The semi-quantitative fluorescence intensity results showed that the uptake of DiD-DHA-BSA-NPs was 4.5 times higher when compared with the free DiD. It is preliminarily shown that the DHA-conjugated BSA NPs that were constructed, have an ability to target the gallbladder. Furthermore, the Pearson colocalization coefficient Rcoloc from in vivo colocalization results indicates that the DHA-BSA-NPs had a good colocalization effect on the gallbladder epithelial cells (GBECs). In addition, the LIM-DHA-BSA-NPs solution not only significantly reduced the concentration of nitric oxide (NO) secreted by inflammatory model cells and the number of peripheral blood leukocytes in guinea pigs with cholecystitis, but also significantly decreased the activities of the aspartate transaminase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), glutamyl endopeptidase (GGT), total bile acid (TBA), and total bilirubin (TBIL) enzymes. Collectively, the LIM-DHA-BSA-NPs could be used as an effective anti-inflammatory agent at the cellular and animal levels. This experiment, for the first time, showed that DHA-conjugated BSA NPs could be absorbed into GBECs by megalin receptor-mediated endocytosis and then they exert an anti-cholecystitis effect because of the LIM. The active uptake of DHA-conjugated BSA NPs by the megalin receptors of the GBECs is expected to become an effective therapeutic strategy for cholecystolithiasis.

Inhibition of Ceramide Synthesis Reduces α-Synuclein Proteinopathy in a Cellular Model of Parkinson's Disease

Parkinson’s disease (PD) is a proteinopathy associated with the aggregation of α-synuclein and the formation of lipid–protein cellular inclusions, named Lewy bodies (LBs). LB formation results in impaired neurotransmitter release and uptake, which involve membrane traffic and require lipid synthesis and metabolism. Lipids, particularly ceramides, are accumulated in postmortem PD brains and altered in the plasma of PD patients. Autophagy is impaired in PD, reducing the ability of neurons to clear protein aggregates, thus worsening stress conditions and inducing neuronal death. The inhibition of ceramide synthesis by myriocin (Myr) in SH-SY5Y neuronal cells treated with preformed α-synuclein fibrils reduced intracellular aggregates, favoring their sequestration into lysosomes. This was associated with TFEB activation, increased expression of TFEB and LAMP2, and the cytosolic accumulation of LC3II, indicating that Myr promotes autophagy. Myr significantly reduces the fibril-related production of inflammatory mediators and lipid peroxidation and activates NRF2, which is downregulated in PD. Finally, Myr enhances the expression of genes that control neurotransmitter transport (SNARE complex, VMAT2, and DAT), whose progressive deficiency occurs in PD neurodegeneration. The present study suggests that counteracting the accumulation of inflammatory lipids could represent a possible therapeutic strategy for PD.