The cytokine storm has captured the attention of the public and the scientific community alike, and while the general notion of an excessive or uncontrolled release of proinflammatory cytokines is well known, the concept of a cytokine storm and the biological consequences of cytokine overproduction are not clearly defined. Cytokine storms are associated with a wide variety of infectious and noninfectious diseases.
It can both sicken and kill patients who are infected with certain strains of flu virus. A cytokine storm is an overproduction of immune cells and their activating compounds (cytokines), which, in a flu infection, is often associated with a surge of activated immune cells into the lungs. The resulting lung inflammation and fluid buildup can lead to respiratory distress and can be contaminated by a secondary bacterial pneumonia -- often enhancing the mortality in patients.
cytokine storm syndrome may be at work in the current COVID-19 pandemic and how it can be detected and possibly treated. Here is an excerpt:
Q. What host reaction do you think may be a cause of death in COVID-19 cases?
Cron: "From reading the literature primarily out of China, many of the severely ill coronavirus-infected patients appear to have clinical and laboratory features of a cytokine storm syndrome, or CSS, which is frequently fatal."
Q. Are there treatments for CSS?
Cron: "Although we don’t know what specifically will benefit CSS associated with COVID-19, we have experience with treatments for other CSS cases. While we are attempting to develop vaccines for COVID-19 and are trialing novel or re-purposed anti-viral therapies for COVID-19, let us also not forget to treat the patient with all we have to offer to help save lives. We need to address the immediate needs for the significant numbers of patients becoming critically ill in the current pandemic. As rheumatologists, we have much to offer on the front lines of helping to recognize and treat these critically ill individuals with complications of hyper-inflammation."
Emerging data as well as knowledge from the SARS and MERS coronavirus outbreaks yield some clues as to why SARS-CoV-2 affects some people worse than others. like many other respiratory conditions, COVID-19 can vary widely among patients. The vast majority of confirmed cases are considered mild, involving mostly cold-like symptoms to mild pneumonia.
Fourteen percent of confirmed cases have been “severe,” involving serious pneumonia and shortness of breath. Another 5 percent of patients confirmed to have the disease developed respiratory failure.
what the agency calls “critical cases” potentially resulting in death. Roughly 2.3 percent of confirmed cases did result in death.
Scientists are working to understand why some people suffer more from the virus than others. It is also unclear why the new coronavirus—like its cousins SARS and MERS—appears to be more deadly than other coronaviruses that regularly circulate among people each winter and typically cause cold symptoms.
The latest data from China stem from an analysis of nearly 45,000 confirmed cases, and on the whole suggest that the people most likely to develop severe forms of COVID-19 are those with pre-existing illnesses and the elderly.
While less than 1 percent of people who were otherwise healthy died from the disease, the fatality rate for people with cardiovascular disease was 10.5 percent.
Scientists don’t know what exactly happens in older age groups. But based on research on other respiratory viruses, experts theorize that whether a coronavirus infection takes a turn for the worse depends on a person’s immune response. “The virus matters, but the host response matters at least as much, and probably more.
For reasons that aren’t entirely clear, some people—especially the elderly and sick—may have dysfunctional immune systems that fail to keep the response to particular pathogens in check. This could cause an uncontrolled immune response, triggering an overproduction of immune cells and their signaling molecules and leading to a cytokine storm often associated with a flood of immune cells into the lung.
Local inflammation can turn into widespread inflammation of the lungs, which then has ripple effects across all organs of the body. This could also happen if the virus replicates faster than the immune system can respond, so that it then has to play catch-up to contain the pathogen—a situation that could also cause the immune defense to spiral out of control.
It’s harder to explain why young, healthy people also sometimes die from the disease. And An intriguing finding in the new data released last week is that although similar numbers of men and women have contracted SARS-CoV-2, more men are dying from the disease.
Although the case fatality rate of COVID-19 is lower, the virus has already killed more people than the other two outbreaks combined, which some have attributed to the pathogen’s fast transmission.
To understand these questions fully will take time, research, and consistent funding for long-term studies.
it will be really apparent to everybody in the world that we need to be funding this type of basic science, fundamental science, to understand these mechanisms of disease. Otherwise, we’re going to be in the same situation when the next outbreak happens—whether it’s a coronavirus or something else