Posts Tagged ‘immune system’




“The textbooks say that immune cells can’t easily get into the healthy brain, and that’s largely true,” said Anne Brunet, Ph.D., professor of genetics and senior author of the study. “But we’ve shown that not only do they get into otherwise healthy aging brains—including human brains—but they reach the very part of the brain where new neurons arise.”

Lead authorship of the study, to be published online July 3 in Nature, is shared by medical student Ben Dulken, Ph.D., graduate student Matthew Buckley and postdoctoral scholar Paloma Navarro Negredo, Ph.D.

The cells that aid memory








Possible brain-based antigens





Single cell analysis reveals T cell infiltration in old neurogenic niches, Nature (2019). DOI: 10.1038/s41586-019-1362-5 ,


By Moises Velasquez-Manoff

The man was 23 when the delusions came on. He became convinced that his thoughts were leaking out of his head and that other people could hear them. When he watched television, he thought the actors were signaling him, trying to communicate. He became irritable and anxious and couldn’t sleep.

Dr. Tsuyoshi Miyaoka, a psychiatrist treating him at the Shimane University School of Medicine in Japan, eventually diagnosed paranoid schizophrenia. He then prescribed a series of antipsychotic drugs. None helped. The man’s symptoms were, in medical parlance, “treatment resistant.”




At first glance, the idea seems bizarre — what does the immune system have to do with the brain? — but it jibes with a growing body of literature suggesting that the immune system is involved in psychiatric disorders from depression to bipolar disorder.

The theory has a long, if somewhat overlooked, history. In the late 19th century, physicians noticed that when infections tore through psychiatric wards, the resulting fevers seemed to cause an improvement in some mentally ill and even catatonic patients.



Modern doctors have also observed that people who suffer from certain autoimmune diseases, like lupus, can develop what looks like psychiatric illness. These symptoms probably result from the immune system attacking the central nervous system or from a more generalized inflammation that affects how the brain works.


Admittedly, these diseases are exceedingly rare, but their existence suggests there could be other immune disorders of the brain and nervous system we don’t know about yet.



Which brings us back to Dr. Miyaoka’s patient. There are other possible explanations for his recovery. Dr. Andrew McKeon, a neurologist at the Mayo Clinic in Rochester, Minn., a center of autoimmune neurology, points out that he could have suffered from a condition called paraneoplastic syndrome. That’s when a cancer patient’s immune system attacks a tumor — in this case, the leukemia — but because some molecule in the central nervous system happens to resemble one on the tumor, the immune system also attacks the brain, causing psychiatric or neurological problems. This condition was important historically because it pushed researchers to consider the immune system as a cause of neurological and psychiatric symptoms. Eventually they discovered that the immune system alone, unprompted by malignancy, could cause psychiatric symptoms.


The bigger question is this: If so many syndromes can produce schizophrenia-like symptoms, should we examine more closely the entity we call schizophrenia?

Some psychiatrists long ago posited that many “schizophrenias” existed — different paths that led to what looked like one disorder. Perhaps one of those paths is autoinflammatory or autoimmune.

If this idea pans out, what can we do about it? Bone marrow transplant is an extreme and risky intervention, and even if the theoretical basis were completely sound — which it’s not yet — it’s unlikely to become a widespread treatment for psychiatric disorders. Dr. Yolken says that for now, doctors treating leukemia patients who also have psychiatric illnesses should monitor their psychiatric progress after transplantation, so that we can learn more.



Dr. Yolken and colleagues recently explored this idea with a different tool: probiotics, microbes thought to improve immune function. He focused on patients with mania, which has a relatively clear immunological signal. During manic episodes, many patients have elevated levels of cytokines, molecules secreted by immune cells. He had 33 mania patients who’d previously been hospitalized take a probiotic prophylactically. Over 24 weeks, patients who took the probiotic (along with their usual medications) were 75 percent less likely to be admitted to the hospital for manic attacks compared with patients who didn’t.


Watershed moments occasionally come along in medical history when previously intractable or even deadly conditions suddenly become treatable or preventable. They are sometimes accompanied by a shift in how scientists understand the disorders in question.

We now seem to have reached such a threshold with certain rare autoimmune diseases of the brain. Not long ago, they could be a death sentence or warrant institutionalization. Now, with aggressive treatment directed at the immune system, patients can recover. Does this group encompass a larger chunk of psychiatric disorders? No one knows the answer yet, but it’s an exciting time to watch the question play out.


Researchers have identified a brand new ‘micro-organ’ inside the immune system of mice and humans – the first discovery of its kind for decades – and it could put scientists on the path to developing more effective vaccines in the future.

Vaccines are based on centuries of research showing that once the body has encountered a specific type of infection, it’s better able to defend against it next time. And this new research suggests this new micro-organ could be key to how our body ‘remembers’ immunity.

The researchers from the Garvan Institute of Medical Research in Australia spotted thin, flat structures on top of the immune system’s lymph nodes in mice, which they’ve dubbed “subcapsular proliferative foci” (or SPFs for short).

These SPFs appear to work like biological headquarters for planning a counter-attack to infection.

Immune cells gathering at the SPF, with the purple band showing the SPF surface.

These SPFs only appear when the mice immune systems are fighting off infections that have been encountered before.

What’s more, the researchers detected SPFs in human lymph nodes too, suggesting our bodies react in the same way.

“When you’re fighting bacteria that can double in number every 20 to 30 minutes, every moment matters,” says senior researcher Tri Phan. “To put it bluntly, if your immune system takes too long to assemble the tools to fight the infection, you die.”

“This is why vaccines are so important. Vaccination trains the immune system, so that it can make antibodies very rapidly when an infection reappears. Until now we didn’t know how and where this happened.”

Traditional microscopy approaches analyse thin 2D slices of tissue, and the researchers think that’s why SPFs haven’t been spotted before – they themselves are very thin, and they only appear temporarily.

In this case the team made the equivalent of a 3D movie of the immune system in action, which revealed the collection of many different types of immune cell in these SPFs. The researchers describe them as a “one-stop shop” for fighting off remembered infections, and fighting them quickly.

Crucially, the collection of immune cells spotted by the researchers included Memory B type cells – cells which tell the immune system how to fight off a particular infection. Memory B cells then turn into plasma cells to produce antibodies and do the actual work of tackling the threat.

“It was exciting to see the memory B cells being activated and clustering in this new structure that had never been seen before,” says one of the team, Imogen Moran.


According to the researchers, the positioning of the SPF structures on top of lymph nodes makes them perfectly positioned for fighting off infections – and fast.

They’re strategically placed at points where bacteria would invade, and contain all the ingredients required to keep the infection at bay.

Now we know how the body does it, we might be able to improve vaccine techniques – vaccines currently focus on making memory B cells, but this study suggests the process could be made more efficient by also looking at how they transform into plasma cells through the inner workings of an SPF.

“So this is a structure that’s been there all along, but no one’s actually seen it yet, because they haven’t had the right tools,” says Phan.

“It’s a remarkable reminder that there are still mysteries hidden within the body – even though we scientists have been looking at the body’s tissues through the microscope for over 300 years.”

The research has been published in Nature Communications.
















by Laura Elizabeth Lansdowne

Researchers have gained a new understanding of the link between obesity and cancer. In the presence of excess fat, the immune surveillance system fails due to an obesity-fueled lipid accumulation in natural killer (NK) cells, preventing their cellular metabolism and trafficking. The new findings were published in Nature Immunology.1

More than 1.9 billion adults are either overweight or obese and a growing amount of evidence proposes that numerous cancer types (including liver, kidney, endometrial and pancreatic cancers)2 are more common in overweight or obese people. Cancer risk is increased in those with higher body fat, with up to 49% of certain types attributed to obesity.3

Previous findings from the GLOBOCAN project indicate that, in 2012 in the United States, approximately 28,000 new cases of cancer in men and approximately 72,000 in women were associated with being obese or overweight.4

The 2018 study1 investigated the effect of obesity on the cellular metabolism, gene expression, and function of NK cells, and its influence on cancer development.

NK cells are cells of the innate immune system that limit the spread of tumors – numerous in vitro models have shown that tumor cells are recognized as ‘targets’ by NK cells.5 These cells destroy their targets by secreting lytic granules containing perforin and apoptosis-inducing granzymes. NK cells require a greater amount of energy to support their anti-tumor activity, therefore they switch their metabolic activity from oxidative phosphorylation (OXPHOS) to glycolysis to meet the increased demand for ATP.1

The researchers discovered that NK cells in an ‘obese environment’ display increased lipid accumulation which affects their cellular bioenergetics, resulting in ‘metabolic paralysis’. This lipid-induced metabolic paralysis led to loss of anti-tumor activity both in vitro and in vivo models. They were able to mimic obesity through fatty-acid administration and by using PPARα/δ agonists, which inhibited mechanistic target of rapamycin (mTOR)-mediated glycolysis.1

However, the researchers also discovered that it was possible to reverse the metabolic paralysis by either inhibiting PPARα/δ or by blocking lipid transport, suggesting that metabolic reprogramming of NK cells could restore their anti-tumor activity in human obesity.1

Corresponding author of the study, Lydia Lynch commented on the importance of the findings in a recent press release: “Despite increased public awareness, the prevalence of obesity and related diseases continue. Therefore, there is increased urgency to understand the pathways whereby obesity causes cancer and leads to other diseases, and to develop new strategies to prevent their progression.”


1. Michelet, X., et al. Metabolic reprogramming of natural killer cells in obesity limits antitumor responses. Nature Immunology. (2018)
2. Mason, L. E., The Link Between Cancer and Obesity. Technology Networks. Available at: Accessed: November 12, 2018
3. Renehan, A. G., et al. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet. (2008) 371, 569–578
4. Arnold, M., et al. Global burden of cancer attributable to high body-mass index in 2012: a population-based study. Lancet Oncol. (2015) 16(1): 36–46
5. Vivier, E., et al. Functions of natural killer cells. Nature Immunology. (2008) 9, 503–510–8ZbNt7sDLF6bujB3qX9CeJA-hpSQwPHeSLoR5Ju1WYXA6SnOEepdO0o-J7qw_1aGB3nfwldpf30hV3pAvVi7SzJa8fw&_hsmi=68543465