Virus World

Some of the severe respiratory symptoms of COVID-19 seem to result from the activity of specific immune cells, which can cause long-term inflammation of the lungs. Alexander Misharin at Northwestern University in Evanston, Illinois, and his colleagues examined fluid from the lungs of 88 people with severe pneumonia caused by SARS-CoV-2 infection (R. A. Grant et al. Nature https://doi.org/fqds; 2021). Most of these individuals had high numbers of a certain type of T cell, a class of immune cells, in their lungs. The researchers also found that nearly 70% of alveolar macrophages, a type of immune cell that is located in the tiny air sacs of the lungs, contained SARS-CoV-2. The cells harbouring the virus showed relatively high expression of genes involved in inflammation. The findings suggest that, once the virus reaches the lungs, it can infect macrophages, which respond by producing inflammatory molecules that attract T cells. T cells, in turn, produce a protein that stimulates macrophages to make more inflammatory molecules. This persistent lung inflammation could lead to some of the life-threatening consequences of SARS-CoV-2 infection.

Findings Published in Nature (Jan. 11, 2021):

https://doi.org/10.1038/s41586-020-03148-w 

UK neurologists publish details of mildly affected or recovering patients with serious or potentially fatal brain conditions. Doctors may be missing signs of serious and potentially fatal brain disorders triggered by coronavirus, as they emerge in mildly affected or recovering patients, scientists have warned. The cases, published in the journal Brain, revealed a rise in a life-threatening condition called Acute Disseminated Encephalomyelitis (Adem), as the first wave of infections swept through Britain. At UCL’s Institute of Neurology, Adem cases rose from one a month before the pandemic to two or three per week in April and May. One woman, who was 59, died of the complication.

A dozen patients had inflammation of the central nervous system, 10 had brain disease with delirium or psychosis, eight had strokes and a further eight had peripheral nerve problems, mostly diagnosed as Guillain-Barré syndrome, an immune reaction that attacks the nerves and causes paralysis. It is fatal in 5% of cases. “We’re seeing things in the way Covid-19 affects the brain that we haven’t seen before with other viruses,” said Michael Zandi, a senior author on the study and a consultant at the institute and University College London Hospitals NHS foundation trust. “What we’ve seen with some of these Adem patients, and in other patients, is you can have severe neurology, you can be quite sick, but actually have trivial lung disease,” he added. “Biologically, Adem has some similarities with multiple sclerosis, but it is more severe and usually happens as a one-off. Some patients are left with long-term disability, others can make a good recovery.” The cases add to concerns over the long-term health effects of Covid-19, which have left some patients breathless and fatigued long after they have cleared the virus, and others with numbness, weakness and memory problems...

Original Study Published in Brain (July 8, 2020):

https://doi.org/10.1093/brain/awaa240