Immune

Immune and hormonal features of Long COVID

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At a Glance

  • Researchers found several immune and hormonal differences between people with Long COVID and those without.
  • The findings shed light on possible causes of Long COVID and could eventually lead to more sensitive testing and personalized treatments.

Tired woman lying on sofa.

Researchers are making progress in understanding the underlying causes of Long COVID. ShowRecMedia / Shutterstock

Some people may experience chronic symptoms for months or years after an acute viral infection. Long COVID, a syndrome that develops in some people after an acute SARS-CoV-2 infection, is a prominent recent example. More than 200 Long COVID symptoms have been documented. Typical ones include extreme fatigue, cognitive impairment, post-exertional malaise, and respiratory problems. Research suggests that about one in eight people who survive an acute SARS-CoV-2 infection go on to have persistent symptoms. The processes that give rise to Long COVID remain unclear.

To shed light on the biology underlying Long COVID, a research team with NIH funding, partly through the RECOVER(link is external) Initiative, conducted a study of more than 250 people. The participants included people who had been infected with SARS-CoV-2 and uninfected people. Among those who had been infected, some had Long COVID and some did not. The researchers measured levels of various immune cells and markers in the participants’ blood. They also measured antibody responses to SARS-CoV-2 and a range of other viruses. The results appeared in Nature on September 25, 2023.

The team found significant differences in the immune cells of participants with and without Long COVID. Those with Long COVID had higher levels of cells called non-conventional monocytes and activated B lymphocytes. They had lower levels of type 1 conventional dendritic cells and central memory T cells. These differences did not depend on age, sex, or body mass index. Participants with Long COVID also had different levels of immune signaling molecules.

Participants with Long COVID had much stronger antibody responses against the SARS-CoV-2 spike protein than those without Long COVID. They also had much stronger responses to an unrelated virus, Epstein-Barr virus (EBV). EBV is a common herpesvirus that causes mononucleosis. After infection, it remains latent in the body and can sometimes reactivate. The higher levels of antibodies to EBV suggest recent reactivation of this virus.

When the researchers used machine learning to identify which features could best predict Long COVID status, they found that the strongest predictor was the stress hormone cortisol. People with Long COVID had much lower cortisol levels than those without. Other strong predictors of Long COVID included elevated levels of a protein called galectin-1, elevated antibodies against EBV, and reduced levels of certain immune cells. 

These findings identify potential biomarkers that could help with diagnosing Long COVID. They also suggest possible mechanisms that contribute to Long COVID. These include a lingering presence of SARS-CoV-2 components in the body, reactivation of latent EBV, and chronic inflammation.

“These findings are important,” says Dr. David Putrino of the Icahn School of Medicine at Mount Sinai, one of the senior authors. “They can inform more sensitive testing for Long COVID patients and personalized treatments for Long COVID that have, until now, not had a proven scientific rationale. This is a decisive step forward in the development of valid and reliable blood testing protocols for Long COVID.”

Dr. Akiko Iwasaki of the Yale University School of Medicine, another senior author, says,  “These findings tell us something about the underlying disease pathogenesis of Long COVID and suggest potential paths for therapy.”

Maximize Your Probiotics for Immune Health

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(nata_vkusidey/iStock)

(nata_vkusidey/iStock)

Recent concerns about immune health have prompted many people to want to know how to boost their immune systems in the best ways possible. One of those ways is with good bacteria, or probiotics—but not just any probiotics. The big questions are: How effective are probiotics for immune health, and how can you be sure to get the most bang for your buck when taking beneficial bacteria supplements?

Probiotics can boost immune function if you find quality sources and don’t let them spoil.

What Are Probiotics?

Probiotics are also commonly referred to as good or beneficial bacteria, but the term also includes some beneficial yeasts as well. These substances are called “good” and “beneficial” because they play a vital role in keeping your gut and entire body healthy. That’s because you’re a vessel of both good and not-so-good bacteria that are associated with disease and other health hazards. Taking probiotic supplements and eating foods rich in beneficial bacteria can help you keep the balance of bacteria in the healthy zone.

Probiotics fall into two general categories:

  • Lactobacillus, which is found in some yogurts, kefir, and other fermented foods. Dozens of strains of this bacteria can assist with digestion, diarrhea, and immune health.
  • Bifidobacterium, which is common in dairy products such as milk, yogurt, and cheese. This genus of bacteria can help with irritable bowel syndrome and other conditions, as well as help with immune system function.

In the yeast category, we have Saccharomyces cerevisiae var. boulardii, which may help with diarrhea and other issues associated with digestion.

What Are Probiotics Good For?

Probiotics have a number of health advantages. For example, you might try probiotics for problems affecting your digestive tract, such as irritable bowel syndrome, diarrhea, urinary tract infection, and inflammatory bowel disease.

Numerous studies have also found that probiotics can be helpful in supporting immune health functions and issues.

Probiotics and Immune System Function

Dozens of studies have demonstrated that various probiotics have the ability to boost immune functions or reduce symptoms associated with immune-related conditions. Here are a few highlighted examples.

A 2019 article review published in the Annals of Nutrition and Metabolism looked at several previous studies and reported that probiotics “improve the behavior of the immune system and the host’s health.”

In a 2017 study, investigators reported that “there is high-quality evidence the probiotics are effective for acute infectious diarrhea, antibiotic-associated diarrhea, Clostridium difficile-associated diarrhea, irritable bowel syndrome, functional gastrointestinal disorders.”

Which Probiotics Are the Most Effective?

If you want to get the most from your probiotic supplement, then you need to choose ones that meet certain criteria. Taking the wrong probiotic is like flour through a sieve: It’s going to pass on through and leave little to nothing behind.

Your probiotic should be refrigerated. All probiotic strains are susceptible to heat, especially those in the genus Bifidobacterium. According to Consumer Labs, and independent test lab, “Many probiotic bacteria are naturally sensitive to heat and moisture. Heat can kill organisms and moisture can activate them within pills, only to die due to lack of nutrients and a proper environment.” Therefore, be sure to put your probiotic supplement in your fridge.

An enemy of all probiotics is stomach acid (aka, gastric acid). The job of this acid is to break down food, but it also destroys bacteria, both good and bad. To protect against the destruction of your supplement, be sure to buy those that have an enteric coating. The probiotic supplement should have been tested to guarantee the beneficial bacteria capsules will survive and make their way to your intestinal tract, where they can release their contents and aid the healing process.

Bottom Line

Probiotics can be a potent management and treatment tool when you want to support and enhance your immune system function. Be sure to choose a probiotic supplement that will provide the most benefit for the buck.