Aqueous leaf extract of Vitex negundo modulates M1-M2 phenotypic switch and functional changes in human macrophages in an in vitro model of hypertension

Abstract

Background

Inflammation and oxidative stress are key drivers of hypertension. Vitex negundo L. is a medicinal plant used in Ayurveda and has potential anti-inflammatory effects.

Objectives

This study aims to assess the immunomodulatory effects of aqueous mature leaf extract (ALE) of V. negundo in an in vitro model of hypertension.

Materials and methods

Non-toxic concentrations of ALE were selected using SRB and MTT assays. Quantitative NBT and Griess assays were done to assess the effect of the ALE on Ang-II-induced production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) respectively. The effect of ALE of V. negundo on the expression of tumor necrosis factor-alpha, interleukin 6, interleukin 1 beta and nuclear factor kappa B were assessed using RT-qPCR. Expression of M0, M1 and M2 surface markers were assessed using flow cytometry.

Results

ALE of V. negundo inhibited the production ROS and RNS in a dose-dependent manner comparable with Telmisartan drug control (p < 0.0001). Ang-II activated, THP-1 derived macrophages expressed high levels of M1 markers. Interestingly, the pre-treatment of Ang-II-activated, THP-1 derived macrophages with ALE of V. negundo increased the expression of M2 marker as CD206^high (89.63%) but no increase in CD163-moderate (27.1%). Both ALE of V. negundo and Telmisartan down-regulated the expression of the pro-inflammatory cytokines in the hypertension model (p < 0.0001).

Conclusions

The results suggest the potential of ALE of V. negundo in exerting immunomodulatory effects in an in vitro model of angiotensin II-mediated hypertension mainly by modulating M1-M2 macrophage switch and limiting inflammation and production of pro-oxidants.