Common Cold Links To Asthma Exacerbations

I am sure we have all heard it, lived it, or told someone about how a cold was connected to an asthma exacerbation. I have loosely understood why this is the case, although I have not fully delved into this. I set on a quest to do just this.

A study on cold links to exacerbations

In a recent study by the University of Wisconsin, this study examined the pattern of gene expression that progresses to asthma exacerbation. This included the examination of clinical symptoms that led to systemic corticosteroid use within 10 days of cold symptoms. This was examined alongside events that resolved without systemic corticosteroid treatment.¹

What they identified was that there were differences in demographics, nasal, or blood cell differentials. They also identified that there were no differences in virus frequency or type of virus when look at the two groups side by side.¹

In the group that had progression to exacerbation, they experienced a significant decline in FEV1 (forced expiratory volume) in 1 FEV1 to forced vital capacity (FEV1/FVC) ratio. These events confirmed the pathophysiological measures of lung function associated with exacerbation.¹

What are the underlying immune responses in asthma exacerbations?

The study examined four significant nasal gene expression modules that contribute to exacerbation, in comparison to those that do not lead to an exacerbation. The modules studied included the “upregulation of multiple respiratory epithelia–, squamous–, and eosinophil–associated responses and downregulation of lymphocyte-associated responses as molecular mechanisms in events that lead to asthma."¹

An interesting finding was that the absence of type 2 inflammation in the airways corresponded with a viral cold resolving without the development of an asthma exacerbation. There is a distinct set of respiratory epithelium and inflammatory cell pathways involved in virus-associated epithelium and inflammatory cell pathways involved in virus-associated exacerbations in contrast to the predominantly squamous cell pathways underlying nonviral exacerbations.¹

Other fun facts

The study also looks at the expression of these modules being expressed in the absence of viral triggers.

They demonstrated that high type 2 inflammation and low type I IFN response gene expression in nasal samples at baseline predicts short-term exacerbation risk, building on previous results showing that nasal IL13 expression is associated with exacerbation likelihood.²

What has been your experience with colds and exacerbations been? Have you always had one that led to the other? I would love to hear about your experience.