Why do some people get sick more than others?
Epithelial cells vary in their response to the common cold virus, potentially explaining why some people are more susceptible to the virus than others. Why do some people get sick more than others?
A team of researchers from Yale University (CT, USA) has discovered that epithelial cells vary in their response to the common cold virus, depending on their location in the human airway. They believe that this could go some way toward explaining why some people are more prone to become ill than others when exposed to the virus.
Epithelial cells in the naval passage should respond and clear a virus when it enters the airways. However, this is not always the case as some people still get ill from exposure to the virus.
In order to investigate this, the team grew cell cultures of epithelial cells from both the naval passage and lungs and exposed both to rhinovirus – the main culprit behind the common cold. They observed that the nasal cells afforded a better antiviral response.
They then triggered the virus surveillance pathway – also known as the RIG-I pathway – in both cell types. They discovered that both types of cell exhibited a defense response against oxidative stress, as well as an antiviral response. Oxidative stress can occur following exposure to viruses, as well as irritants such as cigarette smoking and pollen.
As would be expected, the epithelial cells from the lungs produced a greater oxidative stress defense response, whilst the nasal passage cells produced a greater antiviral response. The team discovered that these two responses formed a trade-off.
“Your airway lining protects against viruses but also other harmful substances that enter airways. The airway does pretty well if it encounters one stressor at a time. But when there are two different stressors, there’s a tradeoff,” senior author, Ellen Foxman explained. “What we found is that when your airway is trying to deal with another stress type, it can adapt but the cost is susceptibility to rhinovirus infection.”
In order to test this hypothesis, the researchers exposed the epithelial cells from the nasal passage to cigarette smoke to induce oxidative stress before exposing them to the rhinovirus. The nasal passage cells were then much more susceptible to the virus.
The study could provide a link between the common cold and environmental factors, explaining why smokers are often more likely to catch a cold. It is hoped this new research could shed some light on new treatments for respiratory viruses.
