Effectiveness of a Blend Composed of Live and Inactivated Probiotic Microorganisms, Pro-post Blend, in Mitigating Early Biological Effects of Air Pollution in Healthy Subjects

Improving air quality in urban areas represents a major public health challenge. In regions such as the Po Valley, airborne particulate matter (PM₁₀ and PM₂.₅) concentrations frequently exceed World Health Organization limits, contributing to an increased incidence of respiratory, cardiovascular, and also gastrointestinal diseases.

Fine particulate matter can carry toxic compounds, including polycyclic aromatic hydrocarbons such as 1-nitropyrene (1-NP) and platinum group elements (PGE) released from catalytic converter abrasion. Due to their small size, these particles can penetrate the respiratory and gastrointestinal tracts, triggering pro-inflammatory responses and oxidative stress.

This study aims to evaluate whether a probiotic dietary supplement (pro-post blend) can mitigate air-pollution-induced inflammatory responses in healthy subjects by enhancing intestinal barrier function and modulating the gut-lung axis. The study is designed as a randomised, placebo-controlled interventional trial lasting 20 months (October 2025-June 2027, with the start of participant sampling scheduled for September 2026), involving 70 street market vendors working in highly-polluted areas of Turin.

Participants will undergo pre- and post-intervention assessments, including the measurement of plasma inflammatory markers (e.g. CRP, IL-6, IL-8, IL-1β, TNF-α, IFN-γ), blood PGE levels, urinary biomarkers of diesel exposure, DNA damage in peripheral lymphocytes assessed by the comet assay, and metagenomic analysis of the gut microbiome. Evaluations will be performed at baseline (T0), after 2 months (T1, medical follow-up only), 4 months of continuous daily supplementation (T2), and 2 months after treatment discontinuation (T3, medical follow-up only).

Overall, this study aims to provide experimental evidence on the potential protective role of a pro-postbiotic formulation against the adverse biological effects of air pollution, supporting the development of a complementary preventive strategy that complement emission-reduction policies.