Humans and their pathogens interact in a complex way, resulting in disease and health. Genetic factors that influence host defenses can vary significantly between individuals and populations.
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This is demonstrated by researchers from the Netherlands, Tanzania, and India in a paper published in the American Journal of Human Genetics. Further genetic and immunological study in non-European populations will have a more detailed picture of the human immune system’s operation.
Humans never get sick on their own. It is always a mixture of host and guest, such as a human infected with a virus. The progression of such an infection can be quite variable. A flu virus can cause serious illness in one person while causing no symptoms in another.
How exactly does that work? What causes one person to recover quickly from a viral infection while another becomes critically ill? To a great extent, the explanation is found in our immune system, which varies greatly from person to person. However, there can be substantial differences in the immune system between various populations.
Immune response regulators
Collins Boahen of Radboudumc and his colleagues focused their study on the role of genetic factors in controlling cytokine production to gain a better understanding of these discrepancies. Cytokines play a significant and initial role in immune response coordination. They, like directors, instruct the immune system’s response to invading pathogens. Interferons, interleukins, chemokines, and tumor necrosis factors are all examples of cytokines.
All of these various factors combine to create a complex cytokine response that varies widely from person to person and population to population.
Variations in the cytokine response determine not only the risk of infectious disease, but also, for example, susceptibility to inflammation and autoimmune disease.”
Collins Boahen, Radboud University Medical Center
Many studies have been conducted on cytokine responses in the Western European population (Caucasian race). Records on cytokine responses in populations from other geographical areas are particularly scarce.
Boahen examined how these responses happen in healthy Tanzanian adults of East African descent. The research was done in collaboration with Blandina T Mmbaga, director of the Kilimanjaro Clinical Research Institute in Tanzania, and her colleagues Godfrey Temba and VeslaKullaya.
In doing so, we also looked at the underlying genetic variations that may influence cytokine responses. In other words, are there genetic differences between populations that cause some to respond differently to infection than others?”
Blandina T Mmbaga, Director, Kilimanjaro Clinical Research Institute
Genetic and immunological differences
The study is part of the Human Functional Genomics Project (HFGP), which looks into how genetic variation in human DNA impacts physiological functions, with a strong focus on the immune system in health and disease.
Boahen stated, “The research shows that both genetically and immunologically, there are clear differences between the European and African populations. Genetically, for example, we see small variations—called SNPs—between the two groups that affect the production of cytokines. Put more simply, we see significant differences in the genetic basis for cytokine production in people from Tanzania in East Africa and Western Europe.”
More focus on non-European populations
The findings of this study indicate the need for additional research in non-European populations. That would be the only way to fully comprehend the variability of the human immune system. As a result, Vinod Kumar, the article’s final author, contends for the integration of underrepresented populations in genetic research to make new discoveries about disparities in health and disease between populations and individuals.
Boahen, C. K. et al. (2022) A functional genomics approach in Tanzanian population identifies distinct genetic regulators of cytokine production compared to European population. American Journal of Human Genetics. doi.org/10.1016/j.ajhg.2022.01.014.