The environment we grow up in plays a critical role in shaping our lifelong health. The exposome refers to the totality of environmental exposures from conception onward, including factors such as air pollution, nutrition, stress, and social context.

While many studies have explored how individual environmental factors affect children’s health, few have examined their shared impact, particularly on immune system regulation, which is a central pathway in the development of chronic diseases such as obesity, diabetes, and respiratory disorders.

According to a new study led by the Barcelona Institute for Global Health (ISGlobal) in collaboration with INSERM—Université Grenoble Alpes, better indoor air quality, proximity to natural spaces, healthy diets, and strong social networks are associated with reduced and better-regulated inflammation in childhood. The findings, published in Environment International, offer new insights into how early-life environmental exposures shape long-term immune function and overall health.

This study is based on the Human Early Life Exposome (HELIX) cohort in the framework of the ATHLETE project, which includes 845 children from six population-based birth cohorts in the UK (BiB), France (EDEN), Spain (INMA), Lithuania (KANC), Norway (MoBa) and Greece (RHEA).

“We investigated how a wide range of pre- and postnatal environmental exposures influence immune function in children and how those immune profiles relate to their cardiometabolic, respiratory/allergic, and neurodevelopmental health,” explains Léa Maitre, coordinator of the Exposome Hub at ISGlobal and last author of the study.

Assessing the impact of early-life environments

The authors examined 91 different environmental exposures occurring during pregnancy and childhood. These were grouped into 13 exposure families, including outdoor exposures, such as air pollution and surrounding green and blue spaces; indoor exposures, including household air pollutants and chemical agents; lifestyle factors, such as diet physical activity, sleep and tobacco exposure; and socioeconomic indicators, like parental education, income and social support.

“To assess immune health, we analyzed blood samples from each child using three biological layers: white blood cell composition, plasma protein concentrations and genome-wide DNA methylation of white blood cells,” says Ines Amine, researcher at INSERM—Grenoble Alpes University and first author of the study.

Advanced statistical models were used to identify immune “signatures”—patterns in the immune system—that were associated with a composite health score combining respiratory, metabolic, and cognitive outcomes.

A high-dimensional reduction algorithm, Regularized Generalized Canonical Correlation Analysis (RGCCA), was utilized for this purpose. RGCCA is particularly well-suited for multi-omics data integration in exposome studies. This work was carried out in collaboration with the University Paris-Saclay, CNRS, CentraleSupélec.

Immune profiles associated with better health scores

The study found three types of immune signatures in children that were linked to better overall health. Two were based on proteins in the blood and showed lower levels of inflammation. The third pattern was based on white blood cells and showed a more balanced and well-regulated immune system.

These beneficial immune signatures were linked to specific environmental exposures during childhood: better indoor air quality, proximity to blue spaces (e.g., lakes, rivers, coastlines), healthier dietary patterns and higher levels of social capital (e.g., social engagement, family and community support).

“Our findings emphasize the importance of these environmental factors in mitigating immunotoxicity related to child health,” concludes Maitre. “Improving indoor air quality, supporting healthy diets, preserving access to natural spaces, and strengthening community support systems are actionable strategies that can promote better key inflammatory processes, which hold significant clinical relevance for cardiometabolic, respiratory and neurodevelopmental health in children.”