The Biological Mechanism Explaining Why We Suffer from Nasal Congestion During Colds and Weather Changes

Rhinitis, commonly referred to as a runny or blocked nose, is a significant symptom frequently associated with the common cold. This symptom can be particularly persistent during colder weather or when there is a change in temperature. But why does this symptom occur? To understand this, we need to delve into the biological mechanisms underlying the onset of rhinovirus infections and why they are more prevalent during colder weather.

Understanding Rhinovirus Infections and Nasal Congestion

When we suffer from a cold, it is often due to a rhinovirus infection of the nasal mucosa. Rhinoviruses are the most common cause of the common cold, making up about 30% of all colds. These viruses infect the lining of the nasal passages and can also affect the throat, leading to symptoms such as a runny nose, sneezing, and a sore throat.

The Role of Temperature in Viral Infections

A recent study published in PLoS Pathogens (temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells) highlighted the role of temperature in the innate immune response against rhinovirus infections. The study showed that lowering the nasal temperature by just 9°F or 5°C can negatively impact the nasal defenses against virus infection. Here is why:

Biological Mechanisms Involved

The primary defense mechanism against rhinovirus infections is the production of interferon, a protein that blocks the virus from spreading to other healthy cells. However, the production of interferon is temperature-dependent. When the nasal temperature is lowered, the genes responsible for producing interferon become less active. This reduced activity results in a weaker immune response, making the individual more susceptible to rhinovirus infection.

Reduced Sensitivity and Interferon Production

The detection of the virus by the cells and the subsequent production of interferon is dependent on the sensitivity of molecules within the cells. When the nasal temperature decreases, these molecules become less sensitive. This reduced sensitivity not only affects the production of interferon but also the production of other proteins that are crucial in combating the virus. Specifically, these proteins include those that:

Chop up viral genes Block the release of the virus Kill virus-infected cells

The net result is a weakened defense mechanism that allows the rhinovirus to replicate more easily, leading to nasal congestion and other cold symptoms.

Impact of Cold Weather and Weather Changes

Cold weather and significant changes in temperature can further exacerbate the problem. During cold weather, the nasal passage is more prone to drying out, leading to a reduced mucus production. Mucus plays a crucial role in trapping particles and pathogens, such as viruses, before they can infect the body. Without adequate mucus, the nasal passages become more vulnerable to viral infections, leading to congestion and other cold-related symptoms.

Moreover, changes in temperature can disrupt the optimal conditions for the production of protective cytokines and the overall effectiveness of the immune system. These factors can further contribute to the persistence of nasal congestion during colder weather or when the temperature fluctuates rapidly.

Conclusion

The biological mechanisms that make us more susceptible to rhinovirus infections during colder weather or when there is a change in temperature are complex but fascinating. Understanding these mechanisms can help us better manage and prevent symptoms of the common cold. Whether through lifestyle adjustments, proper hydration, or preventive measures, educating ourselves about these mechanisms can aid in mitigating the discomfort and inconvenience of nasal congestion during colds and weather changes.