Cationic amphiphilic drug induced phospholipidosis and lysosomal dysgenesis during in vitro adipogenesis

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' are 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 maintenance of a healthy metabolic balance.