Lysosomotropic cationic amphiphilic drugs inhibit adipocyte differentiation in 3T3-L1K cells via accumulation in cells and phospholipid membranes, and inhibition of autophagy

Dysregulation of adipogenesis and disrupted lipid metabolism by the antidepressants citalopram and sertraline

Selective Serotonin Reuptake Inhibitors (SSRIs) are widely used medications for the treatment of major depressive disorder. However, long-term SSRI use has been associated with weight gain and altered lipid profiles. These findings suggest that SSRIs may have negative effects on metabolism. Exposure to certain chemicals called 'obesogens' is known to promote lipid accumulation and obesity by modulating adipogenesis. Here, we investigated whether citalopram (CIT) and sertraline (SER) interfere with the process of adipogenesis, using human mesenchymal stem cells (MSCs) in a 2D and a 3D model. Assessment of intracellular lipid accumulation by fluorescence staining was used as a measure for enhanced adipogenesis. To explore possible mechanisms behind SSRIs' effects, receptor mediated activity was studied using responsive cell lines for various nuclear receptors. Furthermore, RNA sequencing was performed in the 3D model, followed by differential gene expression and pathway analysis. A dose dependent increase in lipid accumulation was observed in both models with CIT and SER. For the 3D model, the effect was seen in a range close to reported steady-state plasma concentrations (0.065-0.65 μM for SER and 0.12-0.92 μM for CIT). Pathway analysis revealed unexpected results of downregulation in adipogenesis-related pathways and upregulation in phospholipids and lysosomal pathways. This was confirmed by an observed increase in lysosomes in the 2D model. Our findings suggest lysosomal dysfunction and disrupted lipid metabolism in mature adipocytes, leading to excessive phospholipid synthesis. Moreover, important adipogenic processes are inhibited, potentially leading to dysfunctional adipocytes, which might have implications in the maintenance of a healthy metabolic balance.

Raman and fluorescence imaging of phospholipidosis induced by cationic amphiphilic drugs in endothelial cells

Cationic amphiphilic drugs (CADs) are known from lysosomotropism, drug-induced phospholipidosis (DIPL), activation of autophagy, and decreased cell viability, but the relationship between these events is not clear and little is known about DIPL in the endothelium. In this work, the effects of fluoxetine, amiodarone, clozapine, and risperidone on human microvascular endothelial cells (HMEC-1) were studied using a combined methodology of label-free Raman imaging and fluorescence staining. Raman spectroscopy was applied to characterize biochemical changes in lipid profile and their distribution in the cellular compartments, while fluorescence staining (LysoTracker, LipidTOX, LC3B, and JC-1) was used to analyze lysosome volume expansion, activation of autophagy, lipid accumulation, and mitochondrial membrane depolarization. We demonstrated that fluoxetine, amiodarone, and clozapine, but not risperidone, at non-toxic concentrations induced lipid accumulations in the perinuclear and cytoplasmic regions of endothelial cells. Spectroscopic markers of DIPL included a robust increase in the ratio (lipid/(protein + lipid)), an increase in choline-containing lipid, fatty acids, and the presence of cholesterol esters, while starvation-induced activated autophagy revealed a spectroscopic signature associated with subtle changes in the lipid profile only. Interestingly, lysosomal volume expansion, occurrence of DIPL, and activation of autophagy induced by selected CADs all depended on drug-accumulation in acidic pH of lysosome cellular compartments whereas reduced endothelial viability did not, and was attributed to mitochondrial mechanisms as evidenced by a decreased mitochondrial transmembrane potential. In conclusion, drug-induced phospholipidosis in the endothelium did not reduce endothelial viability per se and can be efficiently assayed by Raman imaging.

The endosomal lipid bis(monoacylglycero) phosphate as a potential key player in the mechanism of action of chloroquine against SARS-COV-2 and other enveloped viruses hijacking the endocytic pathway

The anti-malarial drug Chloroquine (CQ) and its derivative hydroxychloroquine have shown antiviral activities in vitro against many viruses, including coronaviruses, dengue virus and the biosafety level 4 Nipah and Hendra paramyxoviruses. The in vivo efficacy of CQ in the treatment of COVID-19 is currently a matter of debate. CQ is a lysosomotrophic compound that accumulates in lysosomes, as well as in food vacuoles of Plasmodium falciparum. In the treatment of malaria, CQ impairs the digestion and growth of the parasite by increasing the pH of the food vacuole. Similarly, it is assumed that the antiviral effects of CQ results from the increase of lysosome pH and the inhibition of acidic proteases involved in the maturation of virus fusion protein. CQ has however other effects, among which phospholipidosis, characterized by the accumulation of multivesicular bodies within the cell. The increase in phospholipid species particularly concerns bis(monoacylglycero)phosphate (BMP), a specific lipid of late endosomes involved in vesicular trafficking and pH-dependent vesicle budding. It was shown previously that drugs like progesterone, the cationic amphiphile U18666A and the phospholipase inhibitor methyl arachidonyl fluoro phosphonate (MAFP) induce the accumulation of BMP in THP-1 cells and decrease cell infection by human immunodeficiency virus. HIV viral particles were found to be retained into large endosomal-type vesicles, preventing virus spreading. Since BMP was also reported to favour virus entry through hijacking of the endocytic pathway, we propose here that BMP could play a dual role in viral infection, with its antiviral effects triggered by lysosomotropic drugs like CQ.

Fatty acids of lipids of blood serum and liver of rats with tetracyclin-induced hepatosis and at correction

Irrational pharmacotherapy with tetracyclines can cause mitochondrial cytopathies of liver cells and the development of toxic dystrophy. The issue of violation of the qualitative and quantitative composition of fatty acids and their functional role in the development of liver dystrophy has not been studied enough. Therefore, the aim of the work was to determine the features of changes in the fatty acid composition of blood serum and liver lipids in rats with tetracycline-induced hepatosis and the corrective efficacy of the phospholipid-acceptable dietary supplement “FLP-MD”. It was experimentally established that, in the composition of blood serum lipids and liver tissue, key changes in modeling tetracycline-induced hepatosis in rats (250 mg/kg for 7 days) are primarily tested for polyene fatty acids (PUFAs). In blood serum this is manifested by a decrease in the level of docosadiienoic (22:2ω6) and docosahexaenoic acid (22:6ω3), as well as the total PUFA content due to representatives of the ω3 family, respectively, by 1.3 times. At the same time, a decrease in the content of eicosapentenoic (20:5ω3), docosapentaenoic (22:5ω3), docosahexaenoic (22:6ω3) acids and the saturated/unsaturated fatty acid (SFA/UFA) and ω3/ω6 PUFA ratios, respectively, are noted in the lipid fraction of the liver, respectively by 1.3 times. In contrast to these animals, the use of reparative action of a phospholipid-acceptable dietary supplement “FLP-MD” (13.5 mg/kg) in sick rats provides a significant increase in the level of these fatty acids both in blood serum and in the liver and the restoration of their profile for other representatives. Thus, the components of the “FLP-MD” dietary supplement show a corrective effect on the fatty acid composition of the lipid component of blood serum and liver tissue of animals with tetracycline-induced hepatosis. Indicators have been experimentally established for the diagnosis of toxic liver damage and preclinical trials of the hepatoprotective efficacy of new drugs, which is a promising area of research in veterinary hepatopathology.

Quantification of Intracellular Accumulation and Retention of Lysosomotropic Macrocyclic Compounds by High-Throughput Imaging of Lysosomal Changes

Many marketed pharmaceuticals reach extremely high tissue concentrations due to accumulation in lysosomes (lysosomotropism). Quantitative prediction of intracellular concentrations of accumulating drugs is challenging, especially for macrocyclic compounds that mainly do not fit in current in silico models. We tested a unique library of 47 compounds (containing 39 macrocycles) specifically designed to cover the entire range of accumulation intensities observed with pharmaceuticals so far. For the first time, we show that intracellular concentration of compounds measured by liquid chromatography with tandem mass spectrometry correlates with the induction of phospholipidosis and inhibition of autophagy, but the highest correlation was observed with the increase of lysosomal volume (R = 0.95), all measured by high-throughput imaging assays. Based only on imaging data, we developed a 5-class in vitro model for the prediction of compound accumulation with the accuracy of 81%. The measured change of total lysosomal volume can thus be used in high-throughput screening for determination of the actual intensity of intracellular accumulation of new macrocyclic compounds. The models are largely based on macrocycles, greatly improving the screening and prediction of intracellular accumulation of this challenging class. However, all tested nonmacrocyclic compounds fitted well in the models, indicating potential use of the models in broader chemical space.