Full-body scans reveal long-term effects on immune system : ScienceAlert

Long COVID is a serious illness with no known mechanism or cure. Far from psychosomatic in natureA new study underscores the idea that this misunderstood disease is largely biological.

The continuing toll that the SARS-CoV-2 virus takes on the immune system is widespread and hide in plain sight, argue researchers from the University of California, San Francisco, CellSight Technologies and Kaiser Permanente South San Francisco Medical Center.

When 24 patients who had recovered from COVID-19 had whole-body PET (positron emission tomography) scans, their insides lit up like Christmas trees.

A radioactive drug, called a tracer, showed abnormal T-cell activity in the brain stem, spinal cord, bone marrow, nose, throat, some lymph nodes, heart and lung tissue. And the intestinal wall, compared to full-body scans from before the pandemic.

This widespread effect was seen in the 18 participants with long-term COVID symptoms and the six participants who had fully recovered from the acute phase of COVID-19.

Immune T cell activation in some tissues, such as the spinal cord and intestinal wall, was higher in patients who reported long-COVID symptoms compared with those who fully recovered. Participants with persistent respiratory problems also showed increased uptake of the PET tracer in their lungs and pulmonary artery walls.

That said, even those who fully recovered from COVID-19 still showed persistent changes in their T cell activity across numerous organs compared to pre-pandemic controls, in some cases as long as two and a half years after they were first infected with the virus.

“In some individuals, this activity may persist for years after the onset of COVID-19 and may be associated with systemic changes in immune activation and the presence of [long COVID] symptoms,” UCSF researchers conclude.

“These observations suggest that even a clinically mild infection can have long-term consequences for immune homeostasis in tissues and potentially lead to an active viral reservoir in deeper tissues.”

PET tracer shows increased T cell activation throughout the body in people who contracted COVID-19 27 days before and as many as 654 days before. (UCSF)

The findings are only correlational, but they provide compelling evidence that long-term COVID is linked to the persistence of the SARS-CoV-2 virus in the body and abnormal immune activity.

Long COVID is currently defined by a series of unexplained symptoms that occur after a SARS-Cov-2 infection. These symptoms can last for months or even years and have no other known cause.

The diagnosis is extremely difficult, because there more than 200 symptomswhich are often associated with other conditions, such as brain fog, post-exertional malaise, fatigue, memory loss, or diarrhea.

Research shows that long haulers can suffer from persistent problems in their heart, brain, lungs, skin, kidneys, liver, spleen, intestine, thyroidAnd ovaries.

One explanation for this widespread effect has to do with immune system activity.scientists have found it Biomarkers of inflammation and immune activation are often present in a patient’s blood after the acute phase of a viral infection.

COVID autopsies too show evidence that the SARS-CoV-2 virus persists throughout the period the body, including the colon, chest, muscles, nerves, reproductive system and eye. In some cases, remnants of the virus were found in the brains of deceased patients 230 days after the first symptoms.

Some to research even suggest that infection with the SARS-CoV-2 virus can ‘reawaken’ other dormant viruses in the body, such as the Epstein-Barr virus, which is linked to chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME).

CFS/ME shares many of the same symptoms as long COVID, and some scientists suspect they may be the same. Brain scans have found that long-term COVID changes in the brain parallel the effects of CFS/ME, and reA groundbreaking study recently confirmed that ME/CFS is “unambiguously biological” and that multiple organ systems are affected.

Today, there is increasing recognition that long COVID has a neurological cause. The recent discovery of T cell abnormalities in the spinal cord and brainstem suggests that these overactive immune cells are being ‘translocated’ to tissues of the central nervous system.

“Taken together, these observations challenge the paradigm that COVID-19 is a transient acute infection, building on recent observations in blood,” the UCSF team concludes.

The findings need to be confirmed in larger cohorts, as this new technique for mapping the immune effects of long-term COVID in the body shows so much promise.

The research was published in Science Translational Medicine.

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