Coronavirus Deranges The Immune System In Complex And Deadly Ways

Ring said he’d like to study patients over time to see if specific symptoms might be explained by lingering autoantibodies.

“We need to look at the same patients a half-year later and see which antibodies they do or don’t have,” he said. If autoantibodies are to blame for long COVID-19, they could “represent an unfortunate legacy after the virus is gone.”

Widening the investigation Scientists say the coronavirus could undermine the immune system in several ways.

For example, it’s possible that immune cells become confused because some viral proteins resemble proteins found on human cells, Luning Prak said. It’s also possible that the coronavirus lurks in the body at very low levels even after patients recover from their initial infection.

“We’re still at the very beginning stages of this,” said Luning Prak, director of Penn Medicine’s Human Immunology Core Facility.

Dr. Shiv Pillai, a Harvard Medical School professor, notes that autoantibodies aren’t uncommon. Many healthy people walk around with dormant autoantibodies that never cause harm.

For reasons scientists don’t completely understand, viral infections appear able to tip the scales, triggering autoantibodies to attack, said Dr. Judith James, vice president of clinical affairs at the Oklahoma Medical Research Foundation and a co-author of Luning Prak’s study.

For example, the Epstein-Barr virus, best known for causing mononucleosis, has been linked to lupus and other autoimmune diseases. The bacteria that cause strep throat can lead to rheumatic fever, an inflammatory disease that can cause permanent heart damage. Doctors also know that influenza can trigger an autoimmune blood-clotting disorder, called thrombocytopenia.

Researchers are now investigating whether autoantibodies are involved in other illnesses — a possibility scientists rarely considered in the past. Doctors have long wondered, for example, why a small number of people — mostly older adults — develop serious, even life-threatening reactions to the yellow fever vaccine. Three or four out of every 1 million people who receive this vaccine — made with a live, weakened virus — develop yellow fever because their immune systems don’t respond as expected, and the weakened virus multiplies and causes disease.

In a new paper in the Journal of Experimental Medicine, Rockefeller University’s Casanova has found that autoantibodies to interferon are once again to blame.

Casanova led a team that found three of the eight patients studied who experienced a dangerous vaccine reaction had autoantibodies that disabled interferon. Two other patients in the study had genes that disabled interferon.

“If you have these autoantibodies and you are vaccinated against yellow fever, you may end up in the ICU,” Casanova said.

Casanova’s lab is now investigating whether autoantibodies cause critical illness from influenza or herpes simplex virus, which can cause a rare brain inflammation called encephalitis.

Calming the autoimmune storm Researchers are looking for ways to treat patients who have interferon deficiencies — a group at risk for severe COVID-19 complications.

In a small study published in February in the Lancet Respiratory Medicine, doctors tested an injectable type of interferon — called peginterferon-lambda — in patients with early COVID-19 infections.

People randomly assigned to receive an interferon injection were four times more likely to have cleared their infections within seven days than the placebo group. The treatment, which used a type of interferon not targeted by the autoantibodies Casanova discovered, had the most dramatic benefits in patients with the highest viral loads.

Lowering the amount of virus in a patient may help them avoid becoming seriously ill, said Dr. Jordan Feld, lead author of the 60-person study and research director at the Toronto Centre for Liver Disease in Canada. In his study, four of the placebo patients went to the emergency room because of breathing issues, compared with only one who received interferon. “If we can bring the viral levels down quickly, they might be less infectious,” Feld said.

Feld, a liver specialist, notes that doctors have long studied this type of interferon to treat other viral infections, such as hepatitis. This type of interferon causes fewer side effects than other varieties. In the trial, those treated with interferon had similar side effects to those who received a placebo.

Doctors could potentially treat patients with a single injection with a small needle — like those used to administer insulin — in outpatient clinics, Feld said. That would make treatment much easier to administer than other therapies for COVID-19, which require patients to receive lengthy infusions in specialized settings.

Many questions remain. Dr. Nathan Peiffer-Smadja, a researcher at the Imperial College London, said it’s unclear whether this type of interferon does improve symptoms.

Similar studies have failed to show any benefit to treating patients with interferon, and Feld acknowledged that his results need to be confirmed in a larger study. Ideally, Feld said, he would like to test interferon in older patients to see whether it can reduce hospitalizations.

“We’d like to look at long haulers, to see if clearing the virus quickly could lead to less immune dysregulation,” Feld said. “People have said to me, ‘Do we really need new treatments now that vaccines are rolling out?’ Unfortunately, we do.” ——— (Kaiser Health News (KHN) is a national health policy news service. It is an editorially independent program of the Henry J. Kaiser Family Foundation which is not affiliated with Kaiser Permanente.) (c)2021 Kaiser Health News Distributed by Tribune Content Agency, LLC

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