Groundbreaking discovery links immune systems and parenting
KU Leuven researchers have found that parenting can have as big an impact on the immune system as 40 years of aging
In sickness and in health
Professor Adrian Liston and his team at the University of Leuven found that the individual immune systems of two parents living together become very similar. The discovery – reported in the journal Nature Immunology – opens up an array of possibilities.
Every person has a different immune system with a unique composition of certain types of cells. “Some people have an immune system with more types of cells that protect them against viruses, while others’ immune systems make them more resistant to bacteria,” explains Liston, who is originally from Australia but has worked in Leuven for seven years. He is also connected to Flanders’ life sciences research institute VIB.
Supported by funding from the European Research Council, Liston’s team spent about four years examining the immune systems of 670 people, looking into the causes of the variation in immune systems. They analysed the effects of age, gender, obesity and depression.
Age was pinpointed as a crucial factor, in line with the knowledge that the aging process reduces the effect of vaccinations and resistance to infections.
Bouncing back
The researchers also examined the effect of flu vaccinations and gastroenteritis, or infectious diarrhoea. The vaccinations were carried out by the British Babraham Institute on 32 volunteers in the UK. All other 638 test subjects were Flemish, with 24 of them providing insights into the consequences of gastroenteritis.
“Flu vaccinations and gastroenteritis only had a temporary effect,” says Liston. “After a few months, the immune systems had bounced back completely.”
The big surprise for the scientists came when they looked at the immune profiles of 70 couples raising a child together in the same household. It turned out that the pairs of parents had immune systems that were 50% more similar to each other’s than to those of randomly selected people. “Parenting seems to have an effect on the immune system equal to that of 40 years of aging,” says Liston.
Couples living together with a baby tend to have a similar diet, sleeping patterns and levels of stress
The reasons for this partial synchronisation are connected to the parents’ lifestyles, which are attuned to each other. “Couples living together with a baby tend to have a similar diet, sleeping patterns and levels of stress,” explains Liston.
As they live together, couples are affected by similar bacteria in the house and transmit millions of bacteria through contact. For example, 80 million bacteria are transmitted through a kiss on the lips. Raising children also involves the changing of nappies, during which masses of bacteria are transmitted.
A consequence of the adaptation of the immune systems is that one parent can become more susceptible to viruses or resistant to bacteria, or vice versa. Two parents will thus get the same diseases, as their vulnerabilities become similar.
According to Liston, the findings raise questions about the susceptibility for illness of elderly people in care homes, who already have weakened immune systems because of their age. As they live in similar conditions, it may well be that they also become more vulnerable to the same diseases, which means one disease can severely affect a large number of people living in the home.
“If so, it would be wise to protect these people by preserving the diversity of immune systems,” says Liston. “This could be achieved by helping people to continue a similar way of life as they had before moving into the care home.”
He hopes to set up a project that investigates this issue, which will become more important as people live longer and fewer elderly people are taken care of by family.
Spectacular results
In general, Liston says, the study shows that the immune system is much more flexible than previously thought. “Which means we might be able to influence it to a large extent,” he says.
About one-quarter of a person’s immune system response is determined by their genes, and the rest by environmental factors like living conditions. “If we can ascertain the exact effects of different factors, we can use this knowledge to boost patients’ resistance by precise adjustments in their diet, for example,” says Liston.
The importance of the immune system is increasingly being recognised, he says. “My team has recently begun working with cancer and neuroscience experts, to find out if we can improve cancer and multiple sclerosis therapies.”
His team also checks the cases of patients who have a disease whose cause cannot be determined, to see if the root of the problem lies in the immune system. “Like Dr House’s team, but working in a less spectacular fashion,” says Liston with a smile, referring to the medical drama series House MD.
Some of his team’s results, however, are nothing less than spectacular. They cured 12 members of the same family of an unknown inflammatory disease that gave them horrible rashes by discovering a defect in the immune system and giving the patients a drug normally used against arthritis.
Photo: An illustration of how the immune systems of two people in a relationship evolve towards each other over time and when they have a child together.
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