Nav: Home

A major role for a small organ in the immune response during pregnancy

November 08, 2018

The immune system of a pregnant woman is altered during pregnancy, but not in the way previously believed, according to results from a study at Linköping University, Sweden. This study, published in the Journal of Allergy and Clinical Immunology, shows that the thymus, an organ of the immune system located close to the heart, plays an important role during a normal pregnancy in ensuring that the mother's immune system protects against infection while at the same time tolerating the fetus.

Researchers have questioned for many decades how the body manages the paradox that arises when a female becomes pregnant. On the one hand, the immune system of the mother must be adapted such that it does not react strongly and reject the fetus (half of whose genes come from the father, thus making it a partially foreign object). On the other hand, the immune system must provide effective protection against infection.

Researchers at Linköping University have studied how the immune system of a pregnant woman changes during a normal pregnancy. They have studied in particular the role played by a small organ, the thymus, in immune regulation. The thymus plays a central role in the development of a very important group of cells in the immune system, the T cells (where the "T" indicates that these cells are produced in the thymus). T cells act as an orchestral conductor, and determine how the immune system reacts. The body's own cells must be tolerated, while foreign objects such as bacteria and viruses must be attacked.

Despite the central role of the thymus in the immune system in general, we do not know whether its function changes during pregnancy. Most of what we currently know about the thymus comes from studies in mice. It is generally believed, based on studies in animals, that the thymus becomes smaller during pregnancy and that its output falls, with fewer T cells being released. In animals, a decrease in the number of T cells causes a weakening of the immune defence, which means that the fetus can be tolerated. But does the same thing happen in humans? In order to answer this question, researchers investigated the output of different types of T cells in the blood of 56 pregnant and 30 non-pregnant women. They were particularly interested in one type of T cell, known as regulatory T cells, since these can interact with other cells of the immune system and prevent them attacking the body's own tissue.

"We have shown that the output of T cells from the thymus does not change in pregnancy. We have also shown that the output of regulatory T cells, which can weaken the immune response, seems to increase in pregnancy. These results may explain how the mother can not only tolerate the fetus but also maintain her defence against infection", says Sandra Hellberg, doctoral student in the Department of Clinical and Experimental Medicine at Linköping University, and one of the authors of the study.

The discovery may also be important in understanding certain autoimmune diseases, in which the body's immune system starts to attack the body's own cells. Several autoimmune diseases are connected to the function of the thymus: one example is multiple sclerosis (MS), in which the brain and spinal cord are damaged by the immune system.

"Previous research into MS has shown that the function of the thymus is impaired in the disease, and the output of T cells is lower. This could explain why the symptoms of women with MS often improve during pregnancy", says Professor Jan Ernerudh, principal investigator of the study.

The research group is now planning to investigate the function of the thymus in women with MS, and examine patients before, during and after pregnancy. They will in this way determine whether changes in the balance between different types of T cell contribute to the improvement often seen in women with MS during pregnancy.
-end-
The study has been performed in collaboration with Linköping University Hospital, the maternity clinic at Vrinnevi Hospital in Norrköping and Karolinska Institutet in Stockholm. The research was financed with support from, among other sources, the Swedish Research Council and the Medical Research Council of Southeast Sweden, FORSS.

The article: "Maintained thymic output of conventional and regulatory T cells during human pregnancy", Sandra Hellberg, Ratnesh B. Mehta, Anna Forsberg, Göran Berg, Jan Brynhildsen, Ola Winqvist, Maria C. Jenmalm and Jan Ernerudh, (2018), Journal of Allergy and Clinical Immunology, published online on 9 October 2018, doi: 10.1016/j.jaci.2018.09.023

Linköping University

Related Immune System Articles:

The immune system may explain skepticism towards immigrants
There is a strong correlation between our fear of infection and our skepticism towards immigrants.
New insights on how pathogens escape the immune system
The bacterium Salmonella enterica causes gastroenteritis in humans and is one of the leading causes of food-borne infectious diseases.
Understanding how HIV evades the immune system
Monash University (Australia) and Cardiff University (UK) researchers have come a step further in understanding how the human immunodeficiency virus (HIV) evades the immune system.
Carbs during workouts help immune system recovery
Eating carbohydrates during intense exercise helps to minimise exercise-induced immune disturbances and can aid the body's recovery, QUT research has found.
A new model for activation of the immune system
By studying a large protein (the C1 protein) with X-rays and electron microscopy, researchers from Aarhus University in Denmark have established a new model for how an important part of the innate immune system is activated.
Guards of the human immune system unraveled
Dendritic cells represent an important component of the immune system: they recognize and engulf invaders, which subsequently triggers a pathogen-specific immune response.
How our immune system targets TB
Researchers have seen, for the very first time, how the human immune system recognizes tuberculosis (TB).
How a fungus inhibits the immune system of plants
A newly discovered protein from a fungus is able to suppress the innate immune system of plants.
A new view of the immune system
Pathogen epitopes are fragments of bacterial or viral proteins. Nearly a third of all existing human epitopes consist of two different fragments.
TB tricks the body's immune system to allow it to spread
Tuberculosis tricks the immune system into attacking the body's lung tissue so the bacteria are allowed to spread to other people, new research from the University of Southampton suggests.

Related Immune System Reading:

The Immune System, 4th Edition
by Peter Parham (Author)

How the Immune System Works (The How it Works Series)
by Lauren M. Sompayrac (Author)

Basic Immunology: Functions and Disorders of the Immune System
by Abul K. Abbas MBBS (Author), Andrew H. H. Lichtman MD PhD (Author), Shiv Pillai MBBS PhD (Author)

The Immune System Recovery Plan: A Doctor's 4-Step Program to Treat Autoimmune Disease
by Susan Blum (Author), Mark Hyman (Foreword), Michele Bender (Foreword)

The Immune System: A Very Short Introduction (Very Short Introductions)
by Paul Klenerman (Author)

The Immune System, 3rd Edition
by Peter Parham (Author)

The Complete Anti-Inflammatory Diet for Beginners: A No-Stress Meal Plan with Easy Recipes to Heal the Immune System
by Dorothy Calimeris (Author), Lulu Cook (Author)

A Guide to Transfer Factors and Immune System Health: 2nd edition, Helping the body heal itself by strengthening cell-mediated immunity
by Aaron White PhD (Author)

The Immune System Cure: Optimize Your Immune System in 30 Days-The Natural Way!
by Lorna Vanderheaghe (Author)

Boost Your Immune System: 7 Steps You Can Start TODAY To Regain Your Health and Prevent Disease (Book 1)
by InterConnections, LLC

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Where Joy Hides
When we focus so much on achievement and success, it's easy to lose sight of joy. This hour, TED speakers search for joy in unexpected places, and explain why it's crucial to a fulfilling life. Speakers include inventor Simone Giertz, designer Ingrid Fetell Lee, journalist David Baron, and musician Meklit Hadero.
Now Playing: Science for the People

#500 500th Episode
This week we turn 500! To celebrate, we're taking the opportunity to go off format, talk about the journey through 500 episodes, and answer questions from our lovely listeners. Join hosts Bethany Brookshire and Rachelle Saunders as we talk through the show's history, how we've grown and changed, and what we love about the Science for the People. Here's to 500 more episodes!