Effect of different source of Squalene on in vivo podocyte damage

Objective: Podocytes are visceral epithelial cells of glomeruli and have important roles in filter function. Podocyte damage is the main mechanism for proteinuric glomerulopathies such as minimal change disease, focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy. Among the most common causes of primary glomerular disease and nephrotic syndrome in Turkey; after membranous nephritis, FSGS takes the second place. In FSGS treatment, there is no treatment regimen that can provide remission in all patients, and the rate of recurrence can be up to 40% in patients with remission. Squalene is an isoprenoid compound, the main sources of which are shark liver and olive oil. Studies related to squalene are focused on antioxidant and antitumoral effects. Squalene is used as an adjuvant in vaccines, because of its protective and preventive effects in some diseases, and also in various fields as a drug and gene carrier. This study aims to investigate the effects of shark liver and olive oil-based squalene on podocyte damage in experimental animal model. Materials and methods: Six experimental Wistar rat groups with similar weights (300-350 g) were created, with control, adriamycin (ADR), olive oil-derived squalene (SQ-Z), shark-derived squalene (SQ-KK), SQ-Z with ADR, and SQ-KK with ADR. Squalene (from olive oil or shark) was administered at a total dose of 0.4 ml / day for a total of 14 days to rats. One week after the start of SQ application to rats, intravenous ADR (7.5 mg / kg) was started. The day of the application of ADR was accepted as the first day of the experiment. Urine proteinuria, creatinine and urea values were analyzed by collecting 24-hour urine on the 14th day and 1 day before sacrification. Creatinine, blood urea nitrogen (BUN), total protein and albumin values were analyzed in blood samples taken during sacrifization. Rats were sacrificed on the 23rd day. Sections obtained from the kidney tissues of rats were evaluated by light microscopy in hematoxylin eosin (H&E), Periodic acid schiff (PAS), Masson Trichrome, Silver metanamine (PAMS) histochemistry and Wilms tumor 1 protein (WT-1) immunhistochemistry stains. All glomeruli were examined, and the mean segmental sclerosis score, the highest segmental sclerosis score values, tubular atrophy, interstitial fibrosis and inflammation, tubular damage findings, TMA findings, mean number of WT-1 positive glomerular cells, the highest / lowest WT-1 values were investigated. Bowman and glomerular tuft area measurements of 50 glomeruli were measured with morphometric analysis program, and the average values of 25% glomeruli with the highest area were calculated. The inter-group results were evaluated statistically and the significance level was accepted as p <0.05. Results: When SQ-KK and SQ-Z added to Adriyamycin application, it was observed that the severity and duration of the diarrhea findings of the rats decreased, their general condition improved and their mobility increased. In rats supplemented with SQ, serum creatinine and urinary proteinuria decreased (more pronounced with olive oil-derived SQ), urine and creatinine excretion increased in urine, glomerular segmental sclerosis severity / extensiveness, tubular damage and interstitial inflammation findings / severity, and the amount of shrinkage in Bowman and glomerular tuft areas decreased. An increase in the number of WT-1 positive cells, which is a podocyte differentiation marker in glomeruli, has been shown in two different source squalene applications added to the Adriyamycin application. This increase was significant with olive oil-derived squalene (p = 0.031). In addition, tubular atrophy and interstitial fibrosis were observed in a smaller number of rats in SQ- supplemented groups. Widespread and severe acute TMA findings and early death were noted in half of the rats in which Adriyamycin and SQ-KK were administered together. Conclusion: In our study, significant improvement in biochemical and histopathological kidney damage findings was found in rats treated with shark and olive oil-derived squalene forms. In addition, in parallel with the studies focused on podocyte differentiation and protection in FSGS, where podocytopathy is the main damage mechanism, the fact that a significant excess in the number of WT-1 positive cells, which is a specific podocyte marker, has been found in our current study supports that squalene may reduce podocyte damage.