Where You Live Shapes Your Immune System More than Your Genes

Cell Press press-release:

Like fingerprints, immune systems vary from person to person. And while we all inherit a unique set of T cells and B cells from our parents, recent studies have found that our environment—like where and with whom we live—is responsible for 60% to 80% of the differences between individual immune systems, while genetics account for the rest. In a Review published September 29 in Trends in Immunology, three immunologists discuss the emerging science of what shapes our immune systems and how it might be applied.

“Just like it took a while to crack the genetic code, we’re finally starting to crack the immune code, and we’re shifting away from the simplistic idea that there is only one type of immune system,” says lead author Adrian Liston, head of the VIB Translational Immunology Laboratory in Belgium. “Diversity isn’t just programmed into our genes-- it’s programmed into how our genes respond to the environment.”

Long-term infections are responsible for most of the differences between individual immune systems. For example, when a person has herpes or shingles, the virus has more opportunities to interact with the immune system. These interactions slowly change the cellular make-up of their immune system and make it more sensitive to that specific virus, but also easier for other infections to slip past its defenses. People without these infections don’t experience these cellular changes, and even with the occasional cold or fever, their immune systems stay relatively stable.

The exception is when a person is elderly. Researchers haven’t determined exactly why age plays a major role in making our individual immune systems more unique, but they have shown that aging changes how our immune system responds to threats. As we get older, an organ called the thymus gradually stops producing T cells, which are made to help to fight off infection. Without new T cells, older people are more likely to get sick and less likely to respond to vaccines.

“A lot of diseases that we associated with aging have an inflammatory component, which suggests there is likely immune involvement,” says Michelle Linterman, a researcher at the Babraham Institute and co-author of the review. “Understanding how the immune system changes with age is going to be hugely important for treating age-related diseases in the future.”

 Differences can be overcome, however; studies of people living together have shown that air quality, food, stress levels, sleep patterns, and lifestyle choices had a strong combined effect on our immune responses. For example, couples who cohabitate have more similar immune systems compared to the general public.

Liston and his collaborators, Linterman and Edward Carr of the Babraham Institute, would next like to explore how changing our environment could purposefully shape our immune system and potentially affect our health. “In order to tinker with the immune code, we first need to really understand the influences that shape the immune system,” says Liston. “That’s why it’s actually great that environment is more important than genetics, because we can play with environment.”

Read: Liston, Carr and Linterman (2016). "Shaping variation in the human immune system". Trends in Immunology. 

Understanding variation in the human immune system

My talk from the recent Eppendorf Young Investigator Award ceremony on variation in the human immune system.

Regulatory T cell mini-symposium

Leuven, October 14 2016

Hosted by the laboratory of Adrian Liston (VIB/KUL)

Regulatory T cells set the threshold between immunity and tolerance. At this mini-symposium, international experts will present the latest research on regulatory T cell biology, and how these cells can manipulate autoimmunity and cancer. 

We will also have Karin Dumstrei, Senior Editor at EMBO for immunology and neuroscience, to give advice to students and post-docs on successful navigation of the publication process.

Abstract submissions are encouraged from students and post-docs. Two will be selected for a short presentation, and the rest will be candidates for the €100 poster prize. Abstract submission is needed by Sept 1!

For information and to register, please visit: http://liston.vib.be/treg-symposium/ 

JACI Editors' Choice

Online here

Promising new insights into ALS

VIB research marks new step in understanding neurodegenerative diseases

Research into amyotrophic lateral sclerosis (ALS) conducted by VIB-KU Leuven has led to interesting and unexpected conclusions. When scientists were investigating the relevance of the higher expression of the IP₃R2 protein in blood of ALS patients, the general expectation was that lowering the expression of this protein would have a protective effect on the affected motor neurons. But the exact opposite was true: IP₃R2 turned out to be a protector against the negative effects of inflammation during ALS. Even more, the same mechanism may also apply to other diseases, such as stroke and multiple sclerosis.

This research was conducted in the VIB Laboratory of Neurobiology, led by professors Ludo Van Den Bosch and Wim Robberecht (VIB-KU Leuven). Other laboratories involved include Adrian Liston’s Translational Immunology laboratory (VIB-KU Leuven), Jo Van Ginderachter’s Inflammation Research Center (VIB-Vrije Universiteit Brussel), UZ Leuven and the Brain Science Institute RIKEN in Japan. The study’s remarkable conclusions are published in the renowned scientific journal Human Molecular Genetics.

Protective receptor

ALS is a fatal and currently incurable neurodegenerative disease caused by the progressive loss of motor neurons and denervation of muscle fibers, resulting in muscle weakness and paralysis. In Europe, 2.7 out of every 100,000 people are diagnosed with ALS on a yearly basis. Around 10% of all cases are hereditary, 20% of which are caused by mutations in the gene encoding superoxide dismutase 1 (SOD1). For this type of ALS, mouse models have been developed and were used in this VIB research project.

Prof. Ludo Van Den Bosch (VIB-KU Leuven): “In blood of sporadic ALS patients, as well as in models of chronic and acute neurodegeneration, there is a significantly higher expression of the intracellular receptor IP₃R2. When we removed the gene encoding IP₃R2, the ALS mice didn’t just die quicker, we also saw systemic inflammation and increased expression of certain cytokines, proteins that plays an important role in the immune system. As a consequence, we conclude that doing the opposite, which is increasing the amount of IP₃R2, is a protective response. Not only for ALS, but also for other neurogenerative diseases.”

An unexpected twist

The research process is a prime example of good science, where no hypothesis whatsoever pre-determines the outcome. Although the scientists expected that deleting the gene encoding IP₃R2 which is responsible for the release of calcium from intracellular calcium stores would have a positive effect on the survival of motor neurons, the study proved the opposite: IP₃R2 deletion had a negative effect on the survival of the ALS mouse model.

Prof. Ludo Van Den Bosch (VIB-KU Leuven): “The negative effects of IP₃R2 removal in other cell types seem to outweigh the potential benefits of removing IP₃R2 in motor neurons. In the case of unexpected findings like this, a researcher has two options: to stop the project, or to dig deeper into the problem. The last strategy is the most challenging one, as the outcome is uncertain. But, in this case, it has yielded interesting new insights, supported by our data.”

Next steps

The VIB lab is currently involved in a new ALS study in collaboration with the Stem Cell Institute Leuven (SCIL) and supported by the Belgian ALS Liga. Focusing on different cell types derived from skin fibroblasts of ALS patients, scientists are looking for aberrations in their calcium metabolism. The research into the role of the IP₃R2 can serve as an important foundation, as it helps to strengthen the scientific community’s understanding of the mechanisms that may protect motor neurons.

Prof. Ludo Van Den Bosch (VIB-KU Leuven): “We have now proven that some aspects of inflammation could play an important role in the disease, which could eventually open new therapeutic options for patients. But if we really want to cure ALS, we need to understand all the ins and outs of ALS on the patient’s cellular level. Studies like ours are crucial pieces of this complex puzzle that we need to solve before we can develop a successful therapy.”

Read more: Staats, et al., Genetic ablation of IP₃ receptor 2 increases cytokines and decreases survival of SOD1^G93A mice. Human Molecular Genetics. 2016.

Journal club: Transmissible cancer may not be so rare

Cancer is a disease of our own cells gone wrong. Normally our cells work in harmony with each other, taking cues from each other as to when to proliferate, when to differentiate and when to die. In cancer, mutation takes away this level of regulation, leaving a "selfish cell" that ignores all of these signals and proliferates uncontrollably, even to the point of killing the host.

There have been a handful of rare cases where cancers can actually physically cross-over from one individual to another, such that the second individual is actually growing cancer cells that are not self, but are fully derived from the original host. This has been seen in a few human cases as well as well-described transmissible cancers in Tasmanian Devils and dogs. There was even a recent case study that suggests a tapeworm cancer crossed over into the host. In general, however, it is thought that this type of event is going to be exceptionally rare. Even ignoring the protective effect of our immune system killing foreign cells, it is not like cells from one individual can just float through the air to colonise another. Except, of course, under the water.

A paper just published in Nature looks for transmissible cancers in mussels and clams and finds three examples of cancer cells from one individual clam or mussels infecting and growing in other indiviudals of the same, or even different, species. With high population densities and water flow acting to directly transfer cancer cells, it is probably that transmissible cancers are actually a common feature in many marine environments.

Nature 2016, in press. Widespread transmission of independent cancer lineages within multiple bivalve species. Metzger, Villalba, Carballal, Iglesias, Sherry, Reinisch, Muttray, Baldwin, Goff.

EU-LIFE Science Newsletter

Collaboration news from VIB & Babraham Institute

Enormous diversity is observed in the human immune system, the majority of which is non-genetic in origin. In a collaboration between the VIB and the Babraham Institute, Adrian Liston and Michelle Linterman dissect the causes of immune variation and find age and cohabitation to be the principle drivers.

Read more...

Three major breakthroughs in the immunology field

New insights into Multiple Sclerosis treatments

Multiple Sclerosis is the most common neurodegenerative disease of young adults, affecting 2.3 million people. MS is insidious. It can lie dormant for years, controlled well by treatment, but there is no cure and patients always live with the threat of another attack that takes away more of their function. One of the frustrating aspects of MS is that we have treatments, but we don't really understand them. There are plenty of drugs that work to control MS, but it is impossible to predict which drug will work well for which patient, or how long that drug will work. We don't even really understand the way that the different drugs function - essentially, it is a guessing game to find which treatment will work best in which patient; a guessing game that dangerously chews up time as the disease progresses.

In a major new study just released, the Translational Immunology laboratory teamed up with the Neuroimmunology laboratory (led by Prof An Goris) and performed the first large-scale in-depth immunological analysis of multiple MS treatments. We profiled the immune systems of 245 individuals, including untreated MS patients and MS patients being treated with four standard treatments - interferon-beta, glatiramer acetate, natalizumab, or fingolimod. Since all the treatments are effective in at least some patients, we had expected to find that each treatment ould have a similar impact on the immune system. Instead, the results were surprising - each of the treatments did something different to the immune system. 

In fact, the only common response we found to MS treatment was an increase in the serum cytokine BAFF. The confusing part is that BAFF was thought to be detrimental during MS - several mouse trials found that increased BAFF drives more severe disease, while inhibiting BAFF cured disease. These mouse results were strong enough that two clinical trials had started injecting anti-BAFF antibodies into MS patients in the hope of stopping disease progress. And yet, we found that BAFF was going up in patients that were given multiple different effective MS treatments! Our model suggests that increased BAFF may actually be a protective part of MS treatment, so is it wise to give MS patients anti-BAFF? Unfortunately, our model appears to be correct, as the two trials of BAFF in MS have now been prematurally stopped, due to excessive adverse events.

There are three major lessons to be learned from our study:

First, we should look at testing drugs that increase BAFF rather than decreasing BAFF. This may be a promising avenue for treating MS in patients that do not respond to existing drugs.

Second, we should stop assuming that we understand how existing drugs work. Every drug that we give has multiple impacts on the body, and we should not assume that we know which of these impacts are the protective ones. By identifying which particular impacts are shared across multiple effective drugs, then we are more likely to be looking at the protective effects. If our study had been performed earlier, then I doubt anyone would have gone ahead and given anti-BAFF antibodies to MS patients, and these adverse events could have been avoided.

Third, further large-scale immune analyses such as ours may allow us to predict which patients will respond to which drugs best. In MS this is critical - time spent on an ineffective drug means function is lost that will not be regained - patients need the right drug as soon as possible.

You can read more about our study at Neurology: Neuroimmunology & Neuroinflammation:

Dooley*, Pauwels*, Franckaert, Smets, Garcia-Perez, Hilven, Danso-Abeam, Terbeek, Nguyen, De Muynck, Decallonne, Dubois, Liston* and Goris*. 'Immunologic profiles of multiple sclerosis treatments reveal shared early B cell alterations'. 2016 vol. 3 no. 4 e240

Activating inflammation

My recent seminar at the Cold Spring Harbor Laboratory: