Social position crucial for the immune system?

Social rank determines the resistance of rhesus monkeys

04/12/2012

Social status obviously has a significant impact on the immune system. This is the finding of US researchers led by Jenny Tung of the University of Chicago's Department of Human Genetics, studying possible associations between the social rank of rhesus monkey females and their immune system.

As the US scientists report in the journal "Proceedings of the National Academy of Sciences" (PNAS), there is a direct correlation between the rank of rhesus monkey females and their immune system. At first glance, the conclusion is that simply the females with the best immune system took the highest rank. But the researchers around Jenny Tung could prove that changing the social rank automatically changes the immune system. Thus, the social position actually has direct effects on the immune system. "Our findings indicate that the social environment interferes with genes and their activity," the US scientists report.

Unfavorable social environment increases disease risk
Researchers at the Institute of Human Genetics at the University of Chicago found that with increasing numbers of rhesus females, immunogenicity activity also increased. Conversely, this means that an "unfavorable social environment often leads to permanent physiological pressures," the US scientists report. According to Jenny Tung and colleagues, the underlying "biological mechanisms are of great interest, both for understanding the evolutionary effects of social behavior and in the context of human health". To test the impact of rank on the immune system, the researchers divided 49 rhesus female females into 10 social groups "in which each individual social status could be experimentally controlled." In parallel, they studied the activity of certain genes in the animal's organism in the laboratory , Tung and colleagues found that there was a strong causal relationship between social rank and gene regulation in primates. This relationship was so clear that the state of the immune system makes it possible to make a relatively accurate statement about the social status of the animals, the US researchers write. With 80% accuracy, the rank of the animals could be determined solely on the basis of genetic expression, according to the statement of Jenny Tung and colleagues.

Different gene activity depending on social rank
To check whether the social rank determines the gene activity or the performance of the immune system, and not vice versa, the gene activity on the social rank, the US researchers in the experimental period, the Rhesus monkeys females repeatedly exchanged between the groups, which also their changed social position. This change in social status was accompanied by immediate adaptation of gene activity, Tung and colleagues report. "These shifts were short-term enough to read females' rank changes over time," the researchers write. Thus, the social position was clearly the trigger for these changes in the immune system, so the statement of the experts. The gene activity determined by means of blood tests differed between the lower-ranked and higher-ranked rhesus monkey females in 987 genes, with the better-ranked females having a higher activity in 535 genes. These were primarily genes responsible for the production of T cells and other immune-enhancing processes, Tung and colleagues report. The lower-ranked rhesus monkeys showed increased activity, especially in the genes that weaken the immune system, according to the US scientists. They produced fewer T cells and were significantly more susceptible to inflammation and infection, the researchers report.

Low social status means stress and weakens the immune system
According to their own statements, the US scientists found a clear link between the social status and the physiology of the rhesus monkey females, which could help explain how social effects under the skin go, "said Jenny Tung. The researchers also deciphered how the altered gene activity is caused. It has been shown that in monkey females with lower social status certain areas of the genome were blocked by hydrocarbon groups, making reading for the cell machinery was difficult or prevented. This process, also referred to as methylation, is thought to act as one of the key mechanisms of environmental influences on gene activity (epigenetic effect), write the US researchers. For animals with low social status, living in a hierarchy with little social support means chronic stress and sustained weakening of the immune system. There is much to suggest that "the burden of social subordination alone triggers a physiological reaction," which causes a higher risk of disease, report Jenny Tung and colleagues. The associated biological mechanisms are also of great interest to human medicine, as conclusions about human health and social behavior are made possible, the conclusion of the US scientists in the article "Social environment is associated with gene regulatory variation in the rhesus macaque immune system ". (fp)

Also read:
Strengthen the immune system
In case of cold strengthen immune defense