# Mild Ozone-Induced Oxidative Stress Modulates the Activity and Viability of Porcine Neutrophils and Monocytes

## TL;DR

This study shows that ozone exposure affects pig immune cells differently depending on the dose, with low doses activating them and high doses harming them.

## Contribution

The study provides new insights into the dose-dependent effects of ozone on porcine immune cells within a One Health framework.

## Key findings

- Low-dose ozone induces mild activation of porcine neutrophils without reducing viability.
- High-dose ozone causes oxidative stress, enzyme release, and significant loss of neutrophil viability.
- Monocytes are more resistant to ozone damage but still show functional impairment at high doses.

## Abstract

Ozone is a reactive gas capable of modifying immune cell behaviour and is widely used in human and veterinary medicine. In this study, we examined how two ozone exposure regimens affected porcine neutrophils and monocytes obtained from peripheral blood. A lower dose (30 µg/mL for 10 min) induced mild oxidative activation without compromising cell viability, while a higher dose (90 µg/mL for 30 min) caused marked oxidative stress, increased release of inflammatory enzymes, and substantial loss of neutrophil viability. Monocytes were more resistant to oxidative injury, although they also showed impaired function at the higher dose. These findings demonstrate that ozone evokes dose-dependent and cell-type-specific responses, ranging from moderate immune modulation to cytotoxic effects. Because ozone is both an environmental pollutant and a medical agent, understanding its biological impact in animal models strengthens the One Health perspective, which recognises the interconnectedness of human, animal, and environmental health. Our results emphasise that careful control of ozone dose and exposure time is essential for ensuring safety and achieving the desired therapeutic effects across different species.

Ozone (O3) is a reactive oxidant increasingly applied in biomedical settings, yet its dose-dependent effects on innate immune cells, particularly those from non-human species, remain insufficiently defined. Within a One Health framework, this study examined how two clinically relevant O3 exposure regimens (30 µg/mL and 90 µg/mL) affect porcine neutrophils and monocytes isolated from peripheral blood. Cell viability, reactive oxygen and nitrogen species (RONS) production, and the activity of key enzymes (myeloperoxidase, elastase, alkaline phosphatase, arginase) were assessed at 1 h and 24 h post-exposure. The lower dose induced mild functional activation without compromising viability, whereas the higher dose triggered pronounced oxidative stress, enhanced degranulation, and reduced neutrophil viability by more than 60%. Neutrophils exhibited a stronger and more dynamic response than monocytes, which retained viability and differentiation capacity at 30 µg/mL but showed impaired function at 90 µg/mL. These findings highlight the dual nature of O3, where controlled exposure may support immunomodulation, while excessive dosing disrupts cell function. Defining safe and effective therapeutic windows remains critical for future applications.