Pollen exposure and viral respiratory infections

The retrospective study on humans examined nose smears of 20,062 participants, which were taken from 2010 to 2013 at the Sahlgrenska University Hospital in Gothenburg, Sweden. This last cohort included all age groups, including children. The paper provided no further demographic details for these participants.

in-vitro part

For the cell cultural parts of research, primary bronchial epithelial cells were preserved by bronchoscopy from healthy individuals and expanded in suitable growth media and induced for differentiation. Nasal epithelies were also obtained by healthy volunteers who underwent nose operations, or cultivated by nasal brush biopsies and in suitable media.

in-vivo part

In the initial ex-vivo section of the experiments, six weeks old female mice were used.

Study intervention

In the small experimental study in humans, the 18 subjects were subjected to 3 nasal rinses with either a placebo made of saline or birch pollen extract (n = 9). One -sided cureting of the study was taken before and after the study. Eight participants were examined in the same community as the intervention and control cohorts for a continuing environmental exposure to pollen.

in-vitro part

The cultivated bronchial and epithelial tissue were stimulated with pollen extracts and then exposed to human rhinovirus 16 (RV16) virus cultures.

in-vivo part

Six weeks old female mice were infected with the Respiratory Syncytial Virus (RSV) and then ambrosia pollen was exposed to 3 consecutive days.

results

observation group

among the 20,062 participants from Gothenburg occurred during the allergy season over a period of 3 years 5,782 Rhinovirus -positive cases. In these human subjects, nasal symptoms correlated positively with the frequency of birch pollen in the air. Time series analyzes resulted in a significant correlation between rhinovirus -positive cases, air -borne birch pollen concentrations and precipitation ( p = 0.005). There was a positive non-linear relationship between rhinovirus and pollen compared to the RSV cases with pollen numbers, while the association between rhinovirus/pollen and precipitation was negative. (In other words, when it rained and the pollen concentration took, the risk of RSV cases went back than to.)

interventional group

The data of 8 non -allergic volunteers who pursued their symptoms in 2016 were used to determine that their nasal symptoms correlated with the pollen concentrations. The time series analysis resulted in a significant cross correlation between nasal symptoms and birch pollen with a delay effect of up to 9 days, although there was the strongest correlation of the symptoms with the pollen concentrations the previous day. In the 9 volunteers who were provoked directly with birch pollen, the exposure led to a downturning regulation of type i and III interferons in the nasal mucosa compared to those treated with saline solution.

in vitro and in vivo results

In the cultural and exert parts of this study, pollen exposure significantly reduced the interferon-correct and inflammatory chemokine answers from the respiratory pithelia on rhinovirus and viral mimetics and reduced the core translocation of interferon regulation factors. In the case of mice infected with RSV, the simultaneous exposure to pollen weakened the expression of antiviral genes and increased the pulmonary virus virus.

Key point

Nasal symptoms correlated in the air that is not allergic human subjects with the frequency of birch pollen in the air, and a nasal birch pollen pollen led to a reduction in type I and III interferons in their nasal mucosa. In the large patient cohort, the number of rhinovirus-positive cases was correlated with the birch pollen concentrations in the air.

clinical implications

This combination of tissue culture, mouse and human data provides a convincing argument that pollen exposure weakens the innate immune defense against virus infections. It should be emphasized that the participants of this study were not allergy patients - which means that these results apply to everyone, not only for sensitive people. The pollen concentration naturally varies seasonally, and we are generally drawn to these concentrations of people who show symptoms. The pollen concentrations are also carefully monitored by the health authorities, and these values ​​can be easily accessed either by the government or by the government (link removed). The knowledge that rising pollen concentrations may make us more vulnerable to viral infections is of particular importance this year during the Covid 19 pandemic.

A message sent by Radio Sweden on March 29, 2020, quotes one of the authors of this study, Dr. Åslög Dahl, who runs the pollen laboratory at the University of Gothenburg. It has announced preliminary results of a new study. Using COVID-19 data of the World Health Organization, "says Dahl that areas with the highest mortality rates by the coronavirus are demonstrably also the highest pollen values." Although she points out that these results have been hastily put together and have to be examined further, Dahl suggests that everyone - whether they have allergies or not - should currently follow the advice that is sensitive to pollen and allergies.

This can best be summarized in the summary of the paper: "The ability of pollen to suppress innate antiviral immunity regardless of allergies suggests that population groups should avoid extensive activities outdoors if pollen and respiratory virus season collapse."

Even if the observation of Covid-19 rates with pollen counts is still temporary, it is convincing enough with this current study that we should encourage patients to follow her. There is no risk of reducing the pollen.

(link removed) allergyms give this tip:

• stay in the house on dry, windy days. The best time to go outside is after a good rain that helps to remove pollen from the air.
• delegate mowing lawns, weeds and other gardening that cause allergens.
• take off the clothes that you have worn outside and take a shower to rinse pollen from your skin and hair.
• Do not hang out laundry outside - pollen can stick to sheets and towels.
• Wear a pollen mask if you work outdoors.

If the results of this study withstand further validations, the advice for allergy sufferers can apply to everyone, especially during a outbreak of virus infection.