Researchers have identified specific proteins in the blood plasma of people infected with Covid-19 that may help predict which patients may need to be placed on ventilators to breathe and which are most likely to die of the virus.
The researchers at Washington University School of Medicine in the US studied blood plasma samples from 332 Covid-19 patients. "Identifying harmful proteins may be helpful as we confront not only variants of the virus that causes Covid-19, but also as new viruses emerge in the future," said study principal investigator Carlos Cruchaga.
"We may be able to draw blood from an individual with a Covid infection, check the levels of these key proteins and quickly determine risk for serious outcomes. We then could use that information to determine the best course of treatment," Cruchaga said.
The team studied plasma samples from Covid-19 patients admitted to Barnes-Jewish Hospital in St. Louis, US and compared them to plasma samples from 150 people who had not been infected with SARS-CoV-2, the virus that causes Covid-19.
Because the samples were obtained as patients were being admitted to the hospital, the proteins linked to worse Covid-19 outcomes were identified long before any patients actually were placed on ventilators or died from the virus.
The study, published in the journal iScience, used a technique called high-throughput proteomics to identify overexpression and underexpression—also known as dysregulation—of the proteins. The scientists conducted additional testing to distinguish which of the proteins actually caused severe illness from those that became dysregulated as a result of severe illness.
Although the research team identified a large number of proteins that were altered in patients with Covid-19, they determined that the presence of any of 32 proteins that become dysregulated during Covid infection indicated that patients would require breathing assistance from a ventilator.
They identified another five proteins that, when found to be altered in blood plasma as a result of the virus, indicated likelihood of death for the patient. "Many of the proteins we identified were related to inflammation and to the body's immune response, for example, so it wasn't surprising to find them altered by Covid infection," Cruchaga said.
"But a subset of these proteins raised the likelihood that patients would need ventilation or go on to die. Using these proteomics approaches, we now have a methodology that allows us to predict problems, and that can be very important for clinical practice," the researcher said.
Among the 332 Covid-19 patients studied, those whose blood plasma had any of 32 dysregulated proteins—proteins that indicated they might require ventilation to breathe—eventually did require breathing help, typically about a week after admission to the hospital (82 patients).
Of the 332 patients, only those who had alterations in five proteins the scientists linked to severe illness eventually died due to infection (63 patients), according to the researchers.
They also studied similar proteomics data from 297 Covid-19 patients and 76 controls at Massachusetts General Hospital in Boston and found that the same proteins indicated the eventual need for ventilators and the likelihood of death in both groups of patients.
The research also showed that some of the proteins that were dysregulated during Covid-19 infection were linked to coronary artery disease and Alzheimer's disease pathways, confirming that Covid-19 can increase the risk for these disorders.
"That was a surprising finding, because this project was not focused on those issues," Cruchaga said. "Some of the proteins we identified are causal proteins in Alzheimer's pathology, and others are used as biomarkers for Alzheimer's disease, both in the blood and in the cerebrospinal fluid, " the scientist added.
