Research Article |
Corresponding author: Stefka Ivanova ( ivanovastefka_pharm@yahoo.com ) Academic editor: Plamen Peikov
© 2022 Petar Atanasov, Maria Moneva-Sakelarieva, Yozlem Kobakova, Danka Obreshkova, Ivaylo Ivanov, Mariya Chaneva, Mihaela Popova, Valentina Petkova, Stefka Ivanova.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Atanasov P, Moneva-Sakelarieva M, Kobakova Y, Obreshkova D, Ivanov I, Chaneva M, Popova M, Petkova V, Ivanova S (2022) Tobacco smokers as target group for complicated coronavirus infection. Pharmacia 69(3): 791-800. https://doi.org/10.3897/pharmacia.69.e91095
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The aim of current study was to determine, retrospectively, possible correlations between smoking and the incidence, course severity, intubation rate, and mortality (by gender and age) in patients treated for complicated coronavirus infection in the internal medicine clinic at UMHATEM ”N. I. Pirogov” Sofia for the period 01.03.2020–31.12.2020. In a prospective study, the recovery period and immunogenesis in smokers and non-smokers within a one-year period after hospital discharge was investigated. The applied methods were: 1) computed tomography and blood gas analysis 2) chemiluminescent immunoassay for the qualitative determination of total IgM, IgA and IgG anti-SARS-CoV2 AB. Results showed that the part of non-smokers with a positive PCR test is significantly higher compared to the group of former and current smokers. The data obtained from the study confirmed that Covid infection is much more severe among smokers and former smokers with a higher levels of inflammatory markers noticed among the smoking group.
complications, Covid-19, endothelial dysfunction, intubation rate, mortality, tobacco smoking
The coronavirus infection (Covid-19) with the etiological agent SARS-CoV-2 has become a serious global health problem, the fight against which is still ongoing. The pandemic caused by the novel human beta-coronavirus strain SARS-CoV-2 has put global healthcare to a serious assessment, forcing almost all countries to respond with adequate anti-epidemic, diagnostic, treatment and prophylactic measures to multiple epidemic peaks.This fight should also be focused on the development of effective measures to optimally reduce the possibility of the emergence of new mutations that would eventually lead to the emergence of a new strain of the Coronavirus family with significant virulence. SARS-CoV-2 is a beta-coronavirus of the Coronaviridae family. Representatives of the family usually cause respiratory complaints resembling the ”common cold”. Considered from the very beginning of the pandemic to the present moment, almost all countries were forced to fight adequately with several epidemic peaks in the evolution of the infection. Leading scientists from all over the world – experts in the field of medicine, and many other fields of science, continue to work diligently to find the answers to the still too many unsolved questions, necessary to find the most effective way to fight the disease caused by the virus, to limit the viral spread, and eradicate the infection. Retrospective observations on the course of the disease in hospitalized patients have a real contribution to the collection of data on the features, characterizing the development and treatment of the infection. This information is a valuable source, able to direct the attention of the scientific community in an unexpected direction and identify a wide range of risk factors contributing to a severe course of the disease and, also, to pay attention to some bad habits and their impact on morbidity, frequency of complications, and mortality in the target groups (
Advanced age, cardiovascular diseases, as well as all concomitant diseases, in the pathology of which existing endothelial dysfunction, plays a major role, predispose to infection with the SARS-CoV-2 virus, and the development of ”Covid-19 disease”. The respiratory epithelium is the main ”portal of entry” for the virus, but the endothelial cells of the pulmonary blood vessels are an equally important element in the development of lung involvement in the disease Covid-19. Endothelial cells and blood vessels are targets, but also a mechanism for the spread of the SARS-CoV-2 virus, and associated tissue changes, as well as for its dissemination to various organs in the patient’s body. Therefore, prior endothelial dysfunction could make endothelial cells more sensitive to the action of the virus, leading to the more severe systemic course of Covid-19 (
The pathophysiological mechanism of SARS-CoV-2 virus infection is a complex process involving the interaction between ”hyperinflammation”, impaired lymphocyte function, endothelial dysfunction, thromboembolic complications, and fibrotic changes in the lung. These processes are not only complex and unpredictable, but show great variability among individual patients, possibly related to the heterogeneous response of the patient’s immune system (
Another essential mechanism in the development of the infection and its complications is the influence on the precise regulation of the coagulation system. Thrombosis is potentiated by hypercoagulable status, endothelial damage, and blood stasis, and exactly these factors are common in severe Covid-19 infection (
Although the initial ”target” of the Covid 19 virus is the epithelium presented in the respiratory system, the high occurrence of vascular complications in the affected patients directs attention to the endothelial cells of the blood vessels, and their key role in the progression and deterioration of the coronavirus disease. SARS-CoV-2 causes endothelial dysfunction and increases the thrombogenic risk by two main mechanisms – by directly infecting the endothelium and compromising its antithrombotic and barrier function, and/or indirectly by inducing a local cytochrome storm, and systemic inflammatory response, which potentiate endothelial dysfunction (
Endothelial cell dysfunction observed in Covid-19 has a complex pathogenesis. On the one hand, cardiovascular comorbidity in older patients with Covid-19 is associated with prior endothelial dysfunction, and ACE2 receptor deficiency. On the other hand, however, the SARS-CoV-2 virus itself could induce changes in endothelial function in different ways, for example: direct viral replication with loss of barrier function; downregulation of ACE2 receptors, and hyperactivation of the body’s immune response leading to cytokine storm and hypercoagulable state. This acute inflammatory reaction, as well as the prothrombotic response to impaired epithelial cell function, lead to deleterious effects: respiratory distress syndrome (ARDS), diffuse microvascular thrombosis and thromboembolism, life-threatening cardiovascular complications, and multiple organ failure. This endothelial dysfunction in patients who have recovered from Covid-19 could be related to the persistence of chronic inflammation and pathologically activated hypercoagulation during the course of the disease (
In addition to concomitant diseases, some of the risk factors also play a role in the development of endothelial dysfunction, the importance of which should not be ignored and needs further evaluation. A major risk factor leading to disruption of the integral function of the vascular endothelium, and of great public importance, due to its prevalence and its effects, is smoking. Tobacco smoking is one of the largest, preventable causes of a number of diseases, increasing the morbidity and mortality of the population worldwide (
A number of other factors associated with smoking enhance endothelial dysfunction – stimulating the production of free radicals, increasing serum glucose, lipids and lipoproteins, as well as activating the enzyme cyclooxygenase 2 and synthesis of inflammatory mediators (
The blood serum of active smokers has the property to activate the production of free radicals in the endothelium through the activation of NADPH oxidase and subsequent induction of COX-2 expression through the p38MARK/Akt chain (
The levels of these cytokines in the serum of smokers are elevated compared to non-smokers, and simultaneous inhibition of their signaling pathways prevents smoking-induced endothelial dysfunction (
Oxidative stress and accelerated vascular aging are implications for cigarette smoking. (
Smoking is a major factor in the pathogenesis of a number of socially significant diseases – neoplasia, lung and cardiovascular diseases, neurological diseases, GIT diseases, etc. It is not so well-known that cigarette smoke affects the functions of the immune system, affecting both the innate and adaptive (acquired) immunity. Smoking has been shown to increase the production of a number of pro-inflammatory cytokines such as TNF-alfa, IL-1, IL-6, IL-8, GM-CSF and decrease the levels of anti-inflammatory cytokines such as IL-10 (
Preliminary data from a number of reports suggest that smokers are less susceptible to infection with the SARS-COV-2 virus. However, once infected, the risk of developing a severe infection increases. The mechanism for the lower susceptibility to infection requires further studies and research (
Compared with patients who had never smoked, current active smokers appeared to have a reduced risk of infection with SARS-CoV-2 virus, while former smokers had a higher risk of hospitalization, more severe disease, and death. These dependencies are still subject to investigation and further studies (
The relation between the development of Covid-19 infection and smoking, as well as the mechanisms of their interaction, remain unknown for now. Nicotine could play a role in these processes (
Nicotine could be considered as a potential factor for the prevention against Covid-19 infection. Both epidemiological, clinical and in silico models offer evidence that Covid-19 is an acetylcholine receptor (nAChR) disease and can be prevented and controlled by nicotine (
Smoking has an extremely serious impact on human health and remains a serious threat to public health. According to some studies, however, under strict control, nicotine derivatives can be used to treat acute infection with Covid-19 (
Conducted studies prove that patients with respiratory diseases, in the ehiology of which smoking plays an important role, have an increased risk of developing a severe Covid-19 infection. Patients who smoke and have comorbidities are at increased risk for infection with Covid-19, and have a worse prognosis both for the course of the viral infection and for complications of their comorbidities (
Smoking deteriorates the lung’s immune defense and impairs the upper respiratory tract, thus increasing the risk of infection and more severe infectious diseases. That is why smoking is an independent risk factor for the progression of Covid-19 and for increased mortality. These effects appear to be more pronounced in young patients. Smoking prevention and cessation should remain a major goal for society, physicians, and health care in general, especially during the Covid-19 pandemic (
Active smoking and a history of previous long-term smoking are definitely factors associated with the risk of a severe form of coronavirus infection (
The discussion of these actual problems in parallel with the analysis of the results of the present study aims to establish whether there is a causal relation between smoking and infection with the SARS-CoV-2 virus as well as between the course of the disease in complicated coronavirus infection, for the patients treated at the Internal Medicine Clinic at UMHATEM ”N. I. Pirogov”, Sofia, for the period 01.03.2020 - 31.12.2020.
The study included 2,073 patients out of a total of 2,090 patients diagnosed and treated in the internal medicine clinic for complicated coronavirus infection, in the period from 01.03.2020 - 31.12.2020. 17 patients under the age of 18 were excluded. The studied patients were over 18 years of age with main complication ”viral pneumonia”, and a positive result for the presence of the SARS-CoV2 causative agent using the diagnostic method RT-PCR from nasopharyngeal swab and mandatory serum RT PCR. The group includes 895 women and 1178 men. Only patients with more than 5 pack-years (PY) (≥ 20 cigarettes smoked per day) were included in the group of smokers. All patients at hospitalization had moderate to severe pneumonia. Defined as moderately severe pneumonia, according to the CT-score, is whenever 25% to 50% of the lung parenchyma is involved. Defined as severe pneumonia by the CT-score involves more than 50% of the lung parenchyma.
The monitoring of pulmonary changes was carried out based on diagnostic imaging by computed tomography and assessment of gas exchange by blood gas analysis.
Immunogenesis was monitored by determining Anti-SARS-CoV2 AB. The measurements were performed based on a chemiluminescent immunoassay with Micro Well technology. The test is ”semi-quantitative” and is designed for the qualitative determination of total IgM, IgA and IgG anti-SARS-CoV2 AB. In the present study, Total anti-SARS-CoV2 AB and IgG anti-SARS-CoV2 AB were monitored in each included patient.
For the indicated period, there was a total of 2,073 patients who were diagnosed and treated for complicated coronavirus pneumonia at the Internal Medicine Clinic. Viremia was demonstrated in each of the patients. The study group included 895 women and 1178 men. Only patients with more than 5 pack-year (PY) (with more than 20 cigarettes smoked per day) were included in the group of smokers.
Our study consists of two stages – retrospective and prospective:
1) Retrospective:
2) Prospective:
According to their smoking experience, the studied patients were divided into three age groups, and for each age group the frequency of active smokers, non-smokers and former smokers was determined. The first group included 576 patients between the ages of 18 and 49, 1300 patients between the ages of 50 and 79 are included in the second group, and above 80 years were 197 patients (Table
Distribution of men and women in age groups, according to their smoking status.
Males | Females | Total | Males | Females | Total | Males | Females | Total | |
---|---|---|---|---|---|---|---|---|---|
18 - 49 years | 50 - 79 years | Above 80 years | |||||||
Smokers | 17 | 10 | 27 | 67 | 36 | 103 | 4 | 1 | 5 |
Former smokers | 62 | 26 | 88 | 132 | 118 | 250 | 23 | 25 | 48 |
Former smokers + smokers | 79 | 36 | 115 | 199 | 154 | 353 | 27 | 26 | 53 |
Non-smokers | 283 | 178 | 461 | 516 | 431 | 947 | 74 | 70 | 144 |
Total | 362 | 214 | 576 | 715 | 585 | 1300 | 101 | 96 | 197 |
The Fig.
The distribution of men and women in other age groups is illustrated on Fig.
In these two age groups, the same correlation is preserved as in the first age group.
Another important thing, analyzed in this study, is the severity of disease progression in smokers and patients who had never smoked. Unsatisfactory results of non-invasive ventilation methods – persistent hypoxemia, respiratory distress, and the need for intubation and mechanical ventilation are considered as indicators of severe course of coronavirus pneumonia. To this purpose, the intubation rate in patients from the group of smokers and former smokers was determined and compared with the rate of intubation in the group of non-smokers (Table
Intubation rate in males and females from the group of smokers, former smokers and non-smokers (Table
Males | Females | Total | Intubated | Non-intubated | |||||
---|---|---|---|---|---|---|---|---|---|
% from total in group | % from total intuba- ted | % from total in group | % from total non-intuba- ted | ||||||
Former smokers | 217 | 169 | 386 | 121 | 31.35 | 36.45 | 265 | 68.65 | 15.22 |
Smokers | 88 | 47 | 135 | 78 | 57.78 | 23.49 | 57 | 42.22 | 3.28 |
Former smokers + smokers | 305 | 216 | 521 | 199 | 38.20 | 59.94 | 322 | 61.80 | 18.50 |
Non-smokers | 873 | 679 | 1552 | 133 | 8.57 | 40.06 | 1419 | 91.43 | 81.50 |
Total | 1178 | 895 | 2073 | 332 | 16.02 | 100 | 1741 | 83.98 | 100 |
The presented diagrams demonstrate as follows: 1) the percentage of intubated patients to the total number included in the study (Fig.
The results of our study correspond with most of the results of the world statistics and confirm the theory that Covid infection is much more severe among smokers and former smokers. The most likely reason for this fact is the occurring endothelial dysfunction with different clinical manifestations, including concomitant lung and cardiovascular diseases, a consequence of long-term smoking.
The condition of the patients was followed by a standard package of examinations on the first, sixth month and after one year from the day of their hospital discharge. These follow-up tests include computed tomography, laboratory blood tests – Full blood count (FBC), biochemistry, coagulation, inflammatory markers, blood gas analysis and anti-SARS-CoV-2 antibody level. Higher levels of inflammatory markers were noticed as a trend among the smoking group. Resorption and reversal of inflammatory changes in the lung parenchyma, assessed by computed tomography follow-up in the target period, were also delayed.
Immunogenesis was monitored by determining Anti-SARS-CoV2 AB antibodies. The measurements were performed based on a chemiluminescent immunoassay with Micro Well technology. The test is “semi-quantitative” and is designed for the qualitative determination of total IgM, Ig A and IgG anti-SARS-CoV2 AB. In the present study, anti-SARS-CoV2-total AB and anti-SARS-CoV2-IgG AB were tracked in each enrolled patient. No difference was observed regarding the presence or absence of antibodies among those who recovered from the infection.All our patients had anti-SARS-CoV-2 AB. The amount of IgG antibodies slightly decreases, while the amount of Ig Total sensitively (often times) increases within the one-year period during which the patients were followed.
Advanced age, cardiovascular diseases, as well as all concomitant diseases, in the pathology of which endothelial dysfunction plays a major role, predispose to a more severe course of the Covid-19 infection. One of the socially significant bad habits that directly affects the health status and mortality of people, having a direct role in the development of endothelial dysfunction, is smoking. The fact that smoking potentiates serious complications in the course of coronavirus pneumonia is undeniable. This is also confirmed by our observations for the specified period. These results prove the need for comprehensive study and monitoring of pandemic processes and the impact of lifestyle and risk factors on the course of Covid-19. The phenomenon remains unclear – why non-smokers are more susceptible to infection (contagion) with the SARS-CoV-2 virus and is there a possibility that the answer to this question will open new doors for the prevention of Covid-19?!
Graphical abstract
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Explanation note: Graphical abstract