# Olive Leaf Extract Added to Losartan Treatment Improved Klotho/Wnt/β-Catenin Signaling in Hypertensive Rats with Focal Segmental Glomerulosclerosis

## TL;DR

Adding olive leaf extract to losartan treatment improved kidney signaling and reduced damage in hypertensive rats with kidney disease.

## Contribution

Combining losartan with olive leaf extract, a natural antioxidant, was shown to improve Klotho/Wnt/β-catenin signaling and reduce fibrosis in a rat model of kidney disease.

## Key findings

- Olive leaf extract combined with losartan improved Klotho levels and reduced β-catenin and fibronectin in hypertensive rats with FSGS.
- The combination treatment reduced proteinuria and renal injury closer to normal levels compared to losartan alone.
- Losartan combined with tempol increased β-catenin levels, while olive leaf extract combination did not have this effect.

## Abstract

The downregulation of Klotho in renal injury predicts the progression of chronic kidney disease (CKD). Klotho acts as an antagonist of the Wnt/β-catenin pathway, which is involved in the pathogenesis of proteinuria, glomerulosclerosis and tubulointerstitial fibrosis. We investigated whether losartan (L, angiotensin II type-1 receptor blocker) alone or combined with synthetic (tempol, T) or natural antioxidants (olive leaf extract, O) could alter Klotho/Wnt4/β-catenin signaling, thus reducing fibrosis and slowing the progression of focal segmental glomerulosclerosis (FSGS) in spontaneously hypertensive rats (SHR). The rats were divided into five groups. The control rats received a vehicle. The other groups received adriamycin (2 mg/kg, i.v., twice in a 3-week interval) for FSGS induction. Treatments with L, L+T and L+O (10, 10 + 100 and 10 + 80 mg/kg/day, respectively) were administered by gavage during six weeks. In the kidneys of model rats, Klotho and Wnt4 were downregulated, whereas β-catenin and fibronectin levels were increased compared with the control group. L+T did not alter Klotho, Wnt4 or fibronectin levels, while it further increased β-catenin. In contrast, L+O improved Klotho, and reduced β-catenin and fibronectin levels, although it increased PAI-1. The L+O combination reduced proteinuria more efficiently than L and decreased renal injury close to control levels. Although these findings indicate that combined treatment of losartan and olive leaf extract is promising in slowing the progression of the experimental FSGS, further clinical studies are needed to confirm its favorable outcomes and safety in CKD patients.