The role of PLA2-COX2-PGE2 axis on renal epithelial restitution after calcium oxalate damage

SENDYK, DYLAN; MOREL GOMEZ, EMANUEL; FERNÁNDEZ TOME MARÍA C; CASALI, CECILIA IRENE

Ciudad de Mendoza

Congreso; LVIII Reunión de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular- SAIB 2022; 2022

SAIB

The renal inner medulla is responsible for the hydro-saline equilibrium maintenance through water andelectrolyte excretion in urine. The collecting ducts, involved in the urine concentration, are immersed inan extracellular matrix with the highest body osmolarity and are exposed to wastes coming from bloodfiltration. There are several nephrotoxic agents such as antibiotics, diuretics, antineoplastic and cytostaticagents, and renal stones. Calcium oxalate stones are the most common type of kidney stone. The crystalaggregates are harmful to epithelial renal cells and tubular structures, and that damage could lead tothe development of chronic kidney disease. Our previous results showed that renal differentiated cellstreated with oxalate (Ox) for 24 showed a spindle-shaped morphology characteristic of an epithelialmesenchymal transition. After 48 h of Ox, cells started to recover their morphology and after 72 h of Ox,the epithelium is almost restituted. We also observed that Ox treatment modulates mRNA and proteinCyclooxygenase-2 (COX-2) expression and that the inhibition of COX2 with 10 µM NS398 does not allowepithelial restitution. The aim of the present work is to evaluate the role of the PLA2-COX2-PGE2 axis ondamage and the restitution of the renal differentiated epithelial after Ox damage. To do that, the renalepithelial cells MDCK were grown in a hyperosmolar environment (512 mOsm/Kg H2O) for 72 h to get adifferentiated epithelium, and then subjected to 1.5 mM Ox for 24, 48, and 72 h. To inhibit COX2, 10 µM NS398was added 30 min before Ox treatment; and to bypass the inhibition, 10-6 M PGE2 was added 30 min afterOx addition. After treatments, cell number and viability were evaluated, and epithelial morphology wasassessed by fluorescence microscopy. The treatment with 10 µM NS398 + Ox caused a slight decrease incell numbers at 24 h but not at 48 h. 10-6 M PGE2 addition did not affect cell numbers at 24 and 48 h. Cellviability did not change after all treatments. NS398 induced COX2 expression and the addition of PGE2slightly decreased it. Cell treated with 10 µM NS398+Ox showed a cobblestone morphology, but gaps inthe monolayer were observed. PGE2 addition to cells treated 10 µM with NS398 + Ox did not allow the EMTat 24 and 48h. Furthermore, PGE2 treated cells showed a morphology characteristic of renal epithelium(cobblestone). As PGE2 is the final product of PLA2-COX pathway PLA2 expression, COX and PLA2 activitywere evaluated. The levels of PGE2, the main COX product in renal cells, increased significantly after 24 hof Ox treatment. Then, PGE2 levels started to decrease reaching control values at 72 h post Ox. The sameprofile was observed for PLA2 activity. The cPLA2 expression was also modulated by Oxa. The resultsshowed that PLA2-COX2-PGE2 may be implicated in the restitution of the differentiated epitheliadamaged with oxalate, but further experiments are needed to elucidate the molecular mechanismsinvolved.