A mixture of thymol and carvacrol mitigates inflammation and oxidative stress responses in intestinal epithelial cell models

With One Health approach, reducing the use of antibiotics in livestock animal feeds will benefit human and animal health. Among natural alternatives, phytochemicals have beneficial intestinal health promoting values. In vitro models can be employed to better evaluate the biological activities and mode of action of those alternatives prior to in vivo investigations.

Our study aimed at investigating the ability of a mixture of thymol and carvacrol essential oils (TC), the main components of Origanum vulgare, to modulate inflammation and oxidative stress in vitro in intestinal cell lines. Porcine IPEC-J2 cells were used to study cytokine gene expressions in a livestock cell model. Mechanisms underlying such effects were investigated with a human reference cell line (Caco-2) by cell imagery. Oxidative stress mitigation was measured using Caco-2 and CellRox technique by imagery.

In the IPEC-J2 cells, TC (5 to 100 µg/mL) alleviated inflammation by significantly reducing IL-8, TNFα and CCL20 gene expressions compared to the pro-inflammatory group (-4 to -21-fold depending on cytokines and doses; P<0.001). In the Caco-2 cells, TC (5 µg/mL) alleviated inflammation by significantly reducing the % of NF-κB positive nuclei (-46%; P<0.001; [Fig. 1]). TC reduced oxidative stress by reducing oxidised probe quantity (-15% with 10 µg/mL; P<0.01).

Fig. 1 Evaluation of biological properties of a mixture of thymol and carvacrol essential oils (TC) in Caco-2 cells by imagery. Inflammation was evaluated using NF-_KB immunocytochemical labeling in presence of IL-1β at 100 ng/mL (a) or with a pre-incubation of 1h wit TC (5 µg/mL) and then co-incubation of 1h with IL-1β and TC (b). The nuclei are shown in blue and NF-_KB in green. Oxidative stress was evaluated using Deep Red CellROX fluorescent probe after 1h incubation with menadione (50 µM) (c) or after a pre-incubation of 1h with TC (10 µg/mL) and then co-incubation of 1h with menadione and TC (d). Nuclei are shown in blue and Reactive oxygen species in red. The scale bar corresponds to 100 µm.

Using cellular models, these results showed that TC can exert anti-inflammatory effects through the NF-κB pathway and pro-inflammatory cytokine regulation, as well as antioxidant effects in enterocytes. This mixture of thymol and carvacrol is a promising candidate to develop a functional ingredient for livestock animals.

 

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Conflict of Interest

The authors declare no conflict of interest.

Publication History

Article published online:
16 November 2023