Protective Effects of Pistacia lentiscus L. fruit extract against calcium oxalate monohydrate induced proximal tubular injury

Ethnopharmacological relevance: The world prevalence of kidney stones is increasing and plants are frequently used to treat urolithiasis. Pistacia lentiscus L, a plant which freely grows around the Mediterranean basin areas, is widely used for various pathologies. P. lentiscus has an important impact as it has economical value on top of its pharmacological interest. Decoctions of its aerial parts and/or resin are used to treat kidney stones. Aim of the study: To in vitro assess the potential nephroprotective effect of Pistacia lentiscus ethanolic fruit extract (PLEF) on proximal tubular cells in response to the adhesion of calcium oxalate monohydrate (COM) crystals. Materials and methods: Human Kidney [HK]-2 cells were incubated with and without COM in the presence or absence of PLEF. Cell viability was measured by the resazurin assay. The expression of E-cadherin was analyzed by PCR. The extracellular production of H2O2 was measured by Amplex (R) Red H2O2 Assay. The numbers of detached or non-adherent COM crystals in the presence of PLEF were microscopically captured and counted using ImageJ software. The interaction of PLEF with COM and the effect of PLEF on crystal size were analyzed by flow cytometry. The spectrophotometric measurement of turbidity was performed for assessing the COM concentration. Results: PLEF incubated with COM was able to increase the cell viability. The decrease of E-cadherin expression after incubation with COM was counteracted by PLEF. Overproduction of H2O2 induced by COM was also inhibited by PLEF. Observations using flow cytometry showed that interactions between PLEF and the COM crystals occurred. PLEF was also effective in reducing the particles size and in lowering COM concentration. Conclusion: Our data show that COM tubulotoxicity can be significantly reversed by PLEF-at least in part- via an inhibition of COM crystals adhesion onto the apical membrane. This early beneficial effect of PLEF needs to be further investigated as a useful strategy in nephrolithiasis prevention.