Immune system mutiny: mast cells and the mystery of the long COVID



A Year before pandemic, I was diagnosed with a condition called mast cell activation syndrome (MCAS). A hallmark of the syndrome is hypersensitivity in more than one organ system: food and other triggers can give me abdominal pain and severe diarrhea; my nose is swelling and I am sneezing and wheezing. It sounds like allergies, but I have never tested positive for an allergy test.

Mast cells are part of the immune system’s first line of defense. They are abundant in parts of the body that are in close contact with the outside world, including the skin, respiratory tract, and intestines. Mast cells that go bad cause allergic symptoms, secreting histamine and causing itchy eyes, hives and rashes. Their role in modulating the responses of other immune cells is less well understood. Before the pandemic, researchers had suggested that mast cell dysfunction could explain severe cases of the flu – and highlighted the role of cells in stopping inflammation in various situations. In my case, probably because of a genetic peculiarity, my mast cells overreact.

I was pretty stable on my meds, then I got sick with Covid-19. Months after the virus passed and I had no more pneumonia, I was still struggling with fatigue and shortness of breath. My symptoms also flared up erratically. Some mornings, for example, the oatmeal I had relied on for years could cause me abdominal pain. “Once the mast cell response is increased, it doesn’t stop just because the infection is gone,” explained my doctor, Leo Galland, a New York internist specializing in difficult cases.

MCAS often seems to emerge after a virus. Could this explain one of the symptoms of the growing group of patients with long Covid? Congress has now spent more than $ 1 billion on research into why so many post-Covid patients – about a quarter, more often women – still feel sick long after their infection. In Facebook groups and elsewhere, people with plausible symptoms – for example, severe persistent rashes and months of hives – exchanged information about remedies for the disease. Severe fatigue after exercise has suggested myalgic encephalomyelitis / chronic fatigue syndrome, which some say is linked to MCAS. Others became dizzy when they stood up, which could mean they were suffering from Postural Orthostatic Tachycardia Syndrome (POTS). Spend an hour searching online, and you’ll find articles saying that POTS, too, can be a manifestation of MCAS.

But getting a checkup for the syndrome can be a long ordeal. The full range of tests and treatments are not routinely covered by insurance, forcing some patients to pay thousands of dollars out of pocket. Before you go, you need to find an understanding doctor: researchers disagree on whether the disease is rare or fairly common.

I was lucky; Galland hired me in the 1980s. Long before the microbiome hit the news, he diagnosed me with gut dysbiosis – a disturbed gut. We’re not sure why I got sick when I did, but when I showed up in Galland’s office, I was a ridiculously restricted young lady with a myriad of fluctuating symptoms. On a trip to Tucson, for example, my face and arms swelled up and then shrunk on the plane back. I had been exposed to a fungus in the desert. My grandmother sympathized; when her face swelled up, her doctors in Antwerp in the 1930s pulled out all her teeth. She had no explanation.

Interestingly, bowel disorders can be linked to severe Covid-19, and correcting them a possible path to health for people with long-term Covid. Mast cells may have a unique role in communicating with gut bacteria. In my forties, I fit the profile of irritable bowel syndrome (IBS), abdominal pain, often accompanied by diarrhea or constipation, which affects up to 20% of the population and often sets in after a virus. Desperate, in 2018 I had just finished a hypnotherapy trial for IBS when my digestion took an awkward turn, with taxi crashes, and I could no longer eat outside of my home.

A new dietician, Tamara Duker Freuman, author of “The Bloated Belly Whisperer,” helped me identify the worst offenders: foods rich in histamine, which can be found in everything from alcohol to avocados. After further testing, Galland put me on a diet: an arsenal of mast cell modulators and antihistamines, including Pepcid, which also blocks histamine.

And I got better.

* * *

Mast cells were first named in 1878 by a German Jewish Nobel laureate, Paul Ehrlich, a father of modern immunology who is best known for discovering the cure for syphilis. At the turn of the century, scientists discovered anaphylaxis, the classic allergic reaction of mast cells. The word comes from the Greek ana (against) and phylaxis (protection). The idea that an immune response could actually hurt us, rather than protect us, came as a shock. Current research on the gut and immunity could once again change the paradigm.

Five decades later, in 1949, scientists described a rare genetic disease called mastocytosis, in which mast cells produce clones, accumulating in the skin, bones, and other organs. It wasn’t until the 1980s that researchers began to notice that mast cells could become hyper-reactive or over-activated without cloning.

On a separate track, since the 1990s, researchers have explored mast cell activity in IBS. (A clinical trial of Pepcid and Zyrtec for difficult cases of IBS is currently underway at the University of Cincinnati.) Kyle Staller, director of the gastrointestinal motility lab at Massachusetts General Hospital, now sometimes prescribes Pepcid if he sees other signs, such as hives, in patients who ask her to consider a problem with histamine or MCAS. “I think anyone who follows the science closely has to start asking, ‘How much of a role could this play in this IBS patient who is before us on any given day?’ He told me. said.

Competing proposals for diagnostic criteria appeared after 2010. Both proposals state that physicians should rule out other explanations for a person’s symptoms and that symptoms should appear in at least two organ systems (in my case this affects my gut, nose and skin). Both proposals require lab testing – but they disagree on what tests are needed and what ranges would indicate a person has MCAS, as well as other details. Because lab results are elusive, Galland and other doctors instead rely on a medical history.

The disagreement led to two camps. In camp one, the condition is rare; in camp 2, it affects up to 17 percent of the adult population. Camp 1 specialists say patients are being misled: “More and more patients are being told that they may have [mast cell activation syndrome] without having carried out a thorough medical evaluation “, wrote in April 2019 an international group of 24 authors, led by Peter Valent, hematologist and stem cell researcher at the University of Medicine of Vienna, in the Journal of Allergy and Clinical Immunology .

A year later, a largely American group of 43 authors led by Lawrence Afrin, one of the first mast cell activation researchers, retorted in the journal Diagnosis that patients suffer and even die from underdiagnosis. By then, the pandemic had arrived and Afrin suggested that some patients with long Covid could suffer from MCAS.

Patients also saw links. For example, the distinct POTS symptom of extreme dizziness, once often dismissed as a problem of anxious young women, has emerged as one of the strangest long-term symptoms of Covid. POTS, which has been reported by patients who have suffered from Lyme and other infections, may involve histamine and several other chemicals released by mast cells. He is known to overlap with MCAS.

Last fall, when the Centers for Disease Control and Prevention reported on what they called multisystem inflammatory syndrome (MIS), the name rang: MCAS is clearly a multisystem inflammatory syndrome. Theoharis Theoharides, professor of immunology at Tufts University who has studied mast cells for over 40 years, wrote that MIS patients should be evaluated for MCAS.

Mariana Castells, director of the Mastocytosis Center at Brigham and Women’s Hospital in Boston, told me in an email that she had not seen any data showing that long-standing Covid patients have the required diagnostic markers of MCAS.

Observers agree that the Covid Long group likely includes people with different vulnerabilities. It would be truly wonderful if, one day, we found just one powerful concept for understanding post-viral disease.

In the meantime, you may not need to meet either group’s criteria for MCAS, a difficult, chronic disease, to sometimes feel the betrayal of your mast cells. “Like many, many conditions, over time we [may] learn that there is a spectrum of disease, ”Staller said. “It’s not an all-or-nothing phenomenon.

Even the group that considers MCAS rare recognizes the existence of a milder form of mast cell activation that does not meet the criteria for MCAS. Theoharides detailed several categories of the disease. He told me he would guess that half of the patients diagnosed with IBS might have mast cell activation of some sort.

If mast cell dysfunction is really common, I trust the buzz online to help us find out. Crowdsourcing on patient forums is here to stay. And it’s good, after all, that sick people have shared information, found support, and made Covid an ontological “thing” for a long time.

Growing up, I wondered if my grandmother’s multiple “allergies” were real. We didn’t laugh, but we didn’t really believe her. Then it happened to me.

* * *

Temma Ehrenfeld is a New York writer and Negro drawn to philosophy and psychiatry. His most recent book is “Morgan: The Wizard of Kew Gardens”.

This article originally appeared on Undark. Read the original article.


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