- Johns Hopkins scientists have found a new way to stop COVID-19 infections from progressing and prevent severe complications.
- The researchers discovered one way the coronavirus causes an overreaction from the immune system, potentially damaging the lungs and other healthy tissue in the process.
- By blocking a specific protein, scientists may have found a way to prevent the damage caused by COVID-19.
The COVID-19 death rate has declined compared to the early months of the pandemic, as doctors have devised some therapies that work and can save lives. No cure can save everyone who gets infected, and there’s certainly no over-the-counter treatment that would help us tame the threat from the novel coronavirus. But more progress is made with each day that passes, and researchers from Johns Hopkins think they’ve identified a new way to prevent COVID-19 illness.
Doctors helping COVID-19 patients strive to achieve two conflicting goals. They want to support the immune system and help it mount a defense that can ultimately clear the virus, but they do not want the immune response to get out of hand and overwhelm the body. The inflammatory response must be kept in check with COVID-19 to prevent the so-called cytokine storms that attack healthy tissue alongside infected cells, ultimately leading to organ failure or death. Researchers think they’ve found an explanation for that exacerbated immune response, as well as a solution to prevent it.
Published in Blood magazine (via Knowridge), the Johns Hopkins study details another way the virus messes with the immune system, possibly enabling the exacerbated immune response that appears in severe COVID-19 cases.
Before linking to the ACE2 receptors found on lung cells, components of the coronavirus’s spike protein will link up to heparan sulfate. This sugar molecule is found outside the surface of lung cells, blood vessels, and smooth muscle in most organs. It’s this binding to heparan sulfate that then allows the virus to link up to the ACE2 receptor and get inside the cell, where it starts replicating.
By “stealing” the heparan sulfate available, the virus blocks a protein called factor H from using it to bind to cells. Factor H is the name of a glycoprotein that circulates in human plasma, and its purpose is to make sure that the immune system attacks only pathogens and not healthy tissue.
Without protection from factor H, the immune system may end up harming healthy cells alongside cells that the virus already infected. This continued destruction of healthy tissue leads to organ failure and death in severe COVID-19 cases.
Factor H is a component of the complement system, which is part of the innate immune system that doesn’t adapt. The complement system is involved in clearing foreign and damaged material from the human body.
The complement system is made up of several proteins, including factor H and factor D. The Johns Hopkins experiments showed that by blocking factor D, which is upstream in the pathway from factor H, the chain of events triggered by the virus can be stopped. Drugs that can prevent a worsening immune response after exposure to the novel coronavirus might save many lives, especially in at-risk categories. It might even prevent infections altogether.
As with other studies, more research should further explain the effects of SARS-CoV-2 on the complement system. The full study is available at this link.