A new study has found that people with age-related macular degeneration (AMD) are at greater risk of developing severe complications and dying from COVID-19.
The association between the eye disorder and COVID mortality was established after a study in the journal Nature Medicine found one of the immune system’s oldest branches – called complement – may be influencing the severity of the disease.
According to the study, conducted by researchers at the Vagelos College of Physicians and Surgeons at Columbia University Irving Medical Center, macular degeneration is a proxy for complement-activation disorders.
Study lead Professor Sagi Shapira said if complement and coagulation influence severity of COVID-19, then people with pre-existing hyperactive complement or coagulation disorders – such as AMD – should be more susceptible to the virus.
Among 11,116 COVID-19 patients who came to Columbia University Irving Medical Center with suspected virus infection, the researchers found more than 25% of those with AMD died, compared with the average mortality rate of 8.5%. Roughly 20% required intubation.
“The greater mortality and intubation rates could not be explained by differences in the age or sex of the patients,” Shapira said.
“Complement is also more active in obesity and diabetes and may help explain, at least in part, why people with those conditions also have a greater mortality risk from COVID.”
The researchers say their findings suggest existing drugs that inhibit the complement system could help treat patients with severe COVID-19.
Findings stem from coronavirus mimicry
Shapira said the decision to investigate the role of coagulation and complement in COVID-19 began with a sweeping survey of viral mimicry across all viruses on Earth, which total more than 7,000.
He said viruses have proteins that can mimic certain host proteins to trick the host’s cells into aiding the virus with completing its life cycle.
“Beyond the fundamental biological questions that we were interested in addressing, based on our previous work and the work of others, we suspected that identifying those mimics could provide clues about how viruses cause disease,” he said.
Coronaviruses, the survey found, are masters of mimicry, particularly with proteins involved in coagulation and proteins that make up complement.
Complement proteins are said to work like antibodies and help eliminate pathogens by sticking to viruses and bacteria and marking them for destruction. Complement can also increase coagulation and inflammation in the body.
“Unchecked, these systems can also be quite detrimental,” Shapria added. “The new coronavirus – by mimicking complement or coagulation proteins – might drive both systems into a hyperactive state.”