CIRM-funded study shows how cigarette smoke can worsen COVID-19 infection in the airways

Microscopic images of human stem cell–derived airway tissue models with cell nuclei (blue) and SARS-CoV-2 virus infected cells (green); tissue exposed to cigarette smoke (right) had 2 to 3 times more infected cells than non-exposed tissue (left).
Image Credit: UCLA Broad Stem Cell Research Center/Cell Stem Cell

In the middle of a pandemic, stress can run really high and you might be tempted to light up a cigarette to decompress from the world around you. However, a CIRM-funded study revealed that you might want to think twice before lighting up.

It is already known that cigarette smoke is one of the most common causes of lung diseases, including lung cancer, but Dr. Brigitte Gomperts and Vaithilingaraja Arumugaswami at UCLA have pinpointed how smoking cigarettes may worsen infection by SARS-CoV-2, the virus that causes COVID-19, in the airways of the lungs.

The team used airway stem cells from the lungs of healthy non-smoking donors to create a tissue model that replicates the way that airways behave and function in humans. The researchers then exposed these newly created airways to cigarette smoke to mimic the effects of smoking.

Next, the team infected the airway tissue exposed with cigarette smoke with SARS-CoV-2 and also infected tissue not exposed to cigarette smoke. In the tissue model exposed to smoke, the researchers saw between two and three times more infected cells.

The UCLA team determined that smoking resulted in more severe SARS-CoV-2 infection. This was due to the smoke blocking the activity of immune system messenger proteins called interferons, which play an important role in the body’s early immune response. They trigger infected cells to produce proteins to attack the virus, summon additional support from the immune system, and alert uninfected cells to prepare to fight the virus. Cigarette smoke is known to reduce the interferon response in the airways.

In a UCLA news release, Dr. Gomperts explains the results with a simple analogy.

“If you think of the airways like the high walls that protect a castle, smoking cigarettes is like creating holes in these walls. Smoking reduces the natural defenses and that allows the virus to set in.” 

The hope is that these findings will help researchers better understand COVID-19 risks for smokers and could inform the development of new therapeutic strategies to help reduce smokers’ chances of developing severe disease.

The full results to this study were published in Cell Stem Cell.

One thought on “CIRM-funded study shows how cigarette smoke can worsen COVID-19 infection in the airways

  1. The alveoli consists of a layer of simple squamous epithelium, which is thin and flattered cells. The cells are connected with extracellular matrix and surrounded by blood capillaries. This epithelial lining forms part of the alveolar membrane or respiratory membrane that allows the exchange of gasses.

    Recently, investigation showed that cigarette smokers are vulnerable to Covid-19 infection than nonsmoker. Smoke of cigarettes contain a mixture of toxic compounds which are carcinogenic. When the cells expose to carcinogenic substances, many keys of cellular biologic pathways have been altered and cause changes in cytogenetic. For instance, cytochrome P-450 enzymes of cell catalyzed and convert the carcinogens to covalently bind DNA and form DNA addact. Persistent of DNA addact can cause miscoding of DNA sequence (insertion of wrong base) during replication of DNA, when DNA polimerase process the addacts incorrectly and cause genetic damage. The cells with DNA damage loss their integrity of cell structure and proliferation of cells becoming unregulated. The weaken cell structure may open the opportunity for Covid-19 to easily assess into cell and cause infection. The carcinogens of smoke can even block the genetic of immune system to inhibit the activity of messenger process for interferon.

    Similarly, the issue of environment pollution cause the poor public health and Covid-19 infection rates become skyrocketed. Environment pollutants contain many substances which are toxic and mutagenic. The mutagens are key factor to cause mutation in cell, microganims, bacteria and viruses. The possibility of environment factor cause mutation of Covid-19 to change their host adaptation from animals to human cannot be entirely rule out. Thus, environment pollution in the world is a major contributing factor for climate change. Therefore, the unsettled issues of environment factors in the world for today cause a host of many disasters in the world.

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