How environmental factors affect the immune system

Contaminants such as per- and polyfluoroalkyl substances (PFAS), phthalates, and bisphenol A can generally weaken the immune response, including the response to vaccinations, and increase susceptibility to infections. Stress factors such as social inequality, unfavourable living environments, psychosocial stress, and climate change can also impair immune system function. Environmental pollution, antibiotics, and an unhealthy diet can also have adverse effects on the microbiome (i.e. the community of microorganisms in the human body). The combined effects of these processes on vulnerable population groups over long periods of time have rarely been studied to date. “Although pregnant women as well as children and adolescents are a central focus of One Health research, they are often underrepresented in studies”, says Dr Gunda Herberth, a biologist at the UFZ and EMVIC coordinator. One Health means that environmental, animal, and human health are considered together. This interdisciplinary project focuses on the relationship between the environment and humans and brings together expertise from environmental exposure, virology, immunology, microbiome science, and epidemiology.

The focus of Early-Life Environmental Exposures, Microbiome, and Immune Development: A One Health Perspective on Viral Infections in Children (EMVIC) is on three key pathogens that are highly relevant to public health and the immune system: the measles virus, Epstein-Barr virus (EBV) and SARS-CoV-2 (coronavirus). Both measles and SARS-CoV-2 cause acute infections, for which vaccines are available. However, altered immune responses and long-term post-vaccination outcomes have not yet been sufficiently studied. Currently, there is no approved vaccine against EBV. Once the initial infection has occurred, the virus remains in the body for life, usually in a latent form within the B cells of the immune system. EBV has been linked to various conditions, including certain types of lymphoma, tumours and autoimmune diseases. Experimental and epidemiological studies show that gut bacteria and their metabolic products can influence the immune response to measles and SARS-CoV-2. Nevertheless, their impact on the immune response to EBV remains largely unexplored. Environmental factors such as exposure to chemicals can directly affect the microbiome. “However, the interactions between environmental factors, the structure and functions of the microbiome, viral infections, and immune responses are still not well understood”, says Herberth. 

For the investigation, the researchers are using the Lifestyle and environmental factors and their influence on Newborns’ Allergy risk (LiNA) mother-child cohort, which was established at the UFZ. The LiNA cohort provides detailed long-term data collected annually from several hundred mother–child pairs from the time of pregnancy until the children reach adolescence. It explores how environmental factors, such as chemicals, lifestyle and exposure to air pollutants during pregnancy and early childhood, influence immune system development and the risk of allergies. “We want to combine and expand these data with data from the EMVIC project on viral infections, immune responses, the composition and function of the microbiota, and vaccinations in childhood and adolescence”, says Herberth, who also leads the LiNA study. This will result in a dataset that will be available for future One Health research projects.

As part of the Vacc@EMVIC subproject, the Helmholtz Centre for Infection Research (HZI) is investigating how environmental and lifestyle factors influence the immune response to vaccinations in children and adolescents. The focus is on measles and other components of the MMRV vaccine (measles, mumps, rubella, and varicella). The goal is to better understand why vaccine responses vary widely among individual children and what role early environmental influences play in the strength and duration of vaccine protection. 

To this end, researchers at the HZI are analyzing longitudinal blood samples from the LiNA cohort and, using state-of-the-art multiplex serology, tracking the development of antibody responses from birth through adolescence. The immunity data obtained are then linked to extensive information on environmental exposures, lifestyle factors, infections, and other One Health-relevant factors. 

The subproject is led by Dr. Carolina J. Klett-Tammen and Dr. Vanessa Melhorn from the HZI department “Epidemiology”. Carolina J. Klett-Tammen brings several years of expertise in vaccination epidemiology and population-based cohort research. As co-principal investigator of the NAKO Health Study and head of the Vaccination Data Competence Unit, she has been investigating factors that influence vaccine protection and vaccine coverage at the population level for many years. Vanessa Melhorn leads the team “Adaptive Infectious Disease Diagnostics” at the HZI and develops innovative serological methods for cohort research. Her work focuses on high-throughput multiplex assays and the integration of immunological measurement data with omics and cohort data. Together, the HZI is thus making a decisive contribution to deciphering the biological and environmental causes of varying vaccine responses and laying the scientific groundwork for future, target-group-specific vaccination strategies.

The project EMVIC aims to provide a scientific foundation for recommendations on prevention, vaccination strategies and environmental health assessment. This will support evidence-based decision-making in public health. For instance, the findings could inform recommendations regarding vaccination strategies for groups at risk of an impaired immune response due to environmental or psychosocial factors. Furthermore, these findings could inform health regulations issued by the Federal Environment Agency or the Federal Institute for Risk Assessment regarding the impact of chemical exposure on the immune resilience of children and adolescents.