The field of developmental immunology is devoted to exploring and gaining an understanding of the multitude of factors that are responsible for the development of the human immune system. It looks at how immune cells are established and how they interact with foreign cells and antigens. This branch of science is vital to furthering our knowledge of how allergies and autoimmune disorders develop and offer an approach to creating new preventative, diagnostic, and therapeutic methods.
Immune System. Image Credit: peterschreiber.media/Shutterstock.com
The immune system develops in infancy
Our immune system is essential to our overall health. It protects us from bacteria, toxins, viruses, and the disease and illnesses they cause. Put simply, the immune system identifies and removes ‘foreign’ bodies and cells from our system. Further to this, the immune system also regulates its response so that it does not react to the body’s own cells, which can lead to self-destruction and chronic illnesses where the body essentially attacks itself.
At birth, the immune system is not fully developed. During the first years of life, the immune system continues maturing, making the first years of life the essential phase for training the human immune system. Failures at this stage have consequences on health that are often irreversible.
Relationship between the gut and the immune system
Recent research has revealed the key role of the gut microbiome in several human functions. Having once been assumed to be passive and merely involved in digestion, this body of research has been revolutionary, highlighting the active and fundamental role of the gut in circadian rhythms, nutritional responses, psychiatric disorders, metabolism, and immunity.
In fact, roughly 70-80% of the body’s immune cells are harbored in the gut, along with the other 100 trillion bacteria that live in the digestive system, making up what is known as the microbiota. Imbalances in the gut microbiota-immunity interactions have been proven to be the underlying cause of the various human functions and illnesses outlined above.
Studies have shown that the microbiome is vital to training and developing the essential components of both innate and adaptive immune systems. Given that the gut is an important point of entry for allergens, pathogens, and toxins, it is rational that the gut plays an active role in the body’s immune response. This highlights the importance of cultivating the gut-microbiota early in life. Research demonstrates that early-life colonization of the mucosal surfaces of the gut is vital to maturing the body’s immune system.
In the first years of life, the composition of gut microbiota is at its highest intra- and inter-individual variability, as the child matures, this variability reduces and establishes an adult-like configuration at around three years old. This presents a window of opportunity to cultivate healthy gut-microbiota to prevent illness and promote overall health.
However, it also presents the same window of opportunity to heightening the infant’s susceptibility to environmental incursions to the microbiota, which can have long-term effects on overall immunity.
The impact of nutrition on immune development
Because the first few years are most important for the development of the immune system and that the gut is intricately involved, receiving the right nutrition during this time is vital. Food intake can positively or negatively impact the gut microbiota, therefore, influencing the development of the immune system. Studies show that making the right nutritional choices over the infant’s first 1,000 days of life can reduce the risk of developing allergies.
Just as good nutrition can strengthen the immune system and prevent illness, poor nutrition or malnutrition can have the opposite effect. Children who unfortunately do not receive adequate nutrients in their first years are at a greater risk of autoimmune and immunodeficiency disorders due to an impairment in the production and activity of cells of the immune system.
In addition to the development of the immune system, nutrition is key to its functioning. Studies show that when the immune system is activated it requires higher levels of energy to function properly.
Correct nutrition provides a vital source of energy and nutrients that are essential to supporting the active immune system to allow it to respond rapidly, avoiding the development of chronic inflammation which can lead to further health problems. This underlines the overall importance of nutrition on immune function, an area of science that is gaining more and more backing.
Summary
Developmental immunology is interested in furthering our understanding of how the immune system is established during infancy and what factors help and hinder it. With this knowledge, scientists can better prevent, diagnose, and treat illnesses that arise from an immune system malfunction.
Currently, the relationship between the gut and the immune system is becoming rapidly better understood, as is the related role of nutrition. With this knowledge, scientists have the opportunity to better educate parents to promote good gut health and the development of a strong immune system.
Sources:
- Childs, Calder and Miles, 2019. Diet and Immune Function. Nutrients, 11(8), p.1933. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723551/
- Rytter, M., Kolte, L., Briend, A., Friis, H. and Christensen, V., 2014. The Immune System in Children with Malnutrition—A Systematic Review. PLoS ONE, 9(8), p.e105017. journals.plos.org/plosone/article?id=10.1371/journal.pone.0105017
- Zheng, D., Liwinski, T. and Elinav, E., 2020. Interaction between microbiota and immunity in health and disease. Cell Research, 30(6), pp.492-506. https://www.nature.com/articles/s41422-020-0332-7#citeas
Further Reading