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Gut Bacteria May Cause Antiphospholipid Syndrome, LRA-Funded Study Shows


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Gut Bacteria May Cause Antiphospholipid Syndrome, LRA-Funded Study Shows


June 18, 2019

A common type of bacteria living in the gut may spark a common lupus complication called antiphospholipid syndrome, a study partly funded by the Lupus Research Alliance shows. Antiphospholipid syndrome can lead to blood clots and miscarriages.  Led by Dr. Martin Alexander Kriegel of Yale School of Medicine, the research may also help explain why patients’ symptoms recur.

The immune system makes a mistake in lupus and produces proteins called antibodies that damage the kidneys, joints, and other parts of the body. Close to half of people with lupus have antiphospholipid antibodies that target molecules in the outer layer of the body’s cells.

Researchers think that in patients with lupus, the immune system tries to destroy molecules from healthy cells because they look like molecules from bacteria. Dr. Kriegel and colleagues found that a tiny organism called Roseburia intestinalis, which is one of the most common bacteria in the intestines, may cause some of these attacks. The researchers found that these bacteria contain parts of molecules that are very much like the parts of a blood protein targeted in patients with antiphospholipid syndrome. They discovered that patients with antiphospholipid syndrome make antibodies that hone in on the same piece of the bacterium as in the blood protein and that these antibodies correlate with each other. When the scientists gave the bacterium to mice prone to lupus, the animals showed signs of antiphospholipid syndrome.

“Our results suggest that Roseburia intestinalis may be a chronic trigger for antiphospholipid syndrome,” says Dr. Kriegel. “Because the bacteria are so common and stable in the human gut, they may keep sparking attacks by the immune system and cause patients’ symptoms to return again and again. Dr. Kriegel and his colleagues revealed their findings in the journal Cell Host & Microbe.

“The microbiome is of great interest in lupus, and we are excited to see Dr. Kriegel’s results fulfill the promise of his LRA grant,” noted Kenneth M. Farber, President and CEO, Lupus Research Alliance. “This work points to a new approach to treating antiphospholipid syndrome, a dangerous complication of lupus.”


Full Press Release from Yale University:

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A severe autoimmune condition may be triggered by 'good' gut bacteria


HEALTH 18 June 2019

Source: https://www.newscientist.com/article/2206861-a-severe-autoimmune-condition-may-be-triggered-by-good-gut-bacteria/

gut microbes
Sometimes ‘good’ gut microbes can turn bad


By Jessica Hamzelou

The billions of bacteria that line our guts have evolved with us, and play a crucial role in our digestion, physical and mental health. But bacteria that seem beneficial for most people can cause harm in others: they can trigger an autoimmune disease in vulnerable people.

That’s what Martin Kriegel, an immunologist at Yale University, and his colleagues found when they studied people with antiphospholipid syndrome (APS), an autoimmune disorder in which a person’s own immune system attacks a protein that plays a key role in blood thinning. People with the syndrome are at risk of clots, strokes and miscarriages, and it can be fatal. “Young people can suddenly die if they have this,” says Kriegel.

He wondered if, by chance, any gut bacteria might express a protein similar to the one that can trigger APS, and so be attacked by the immune system of people with the syndrome.



When his team screened microbiome databases they found a match: Roseburia intestinalis, a species of bacteria that is thought to improve gut health.

“It’s probably random due to the sheer number of molecules in the microbiome,” says Kriegel.

The team then looked at immune system activity in the gut of people with APS and people without the condition. While R. intestinalis was present at similar levels in the guts of all people examined, the bacteria seemed to be causing inflammation in people with APS. These individuals also made antibodies to attack the bacteria – which looked very similar to the antibodies they made to attack their own proteins.

In experiments with mice, Kriegel’s team also found that, in animals genetically prone to developing APS, a dose of R. intestinalis could trigger the syndrome, with lethal outcomes. This all suggests that R. intestinalis can inadvertently trigger APS in people genetically predisposed to develop the syndrome, says Kriegel.

“It could be that a bug that is beneficial for one disease is detrimental for another,” says Kriegel. A person’s genes and lifestyle could potentially influence which way the relationship will go.

Kriegel hopes that the microbiome could offer new treatment approaches for people with autoimmune diseases like APS. Theoretically, once a person has been diagnosed with the disease, removing the microbe from their gut microbiome might help prevent future clots, he says.

Journal reference: Cell Host & Microbe , DOI: 10.1016/j.chom.2019.05.003

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