Biochemical and histological alterations in rats after acute nitrogen dioxide intoxication

Early-phase pandemic in Italy: Covid-19 spread determinant factors

Although the Covid-19 pandemic is still ongoing, the environmental factors beyond virus transmission are only partially known. This statistical study has the aim to identify the key factors that have affected the virus spread during the early phase of pandemic in Italy, among a wide set of potential determinants concerning demographics, environmental pollution and climate. Because of its heterogeneity in pollution levels and climate conditions, Italy provides an ideal scenario for an ecological study. Moreover, the selected period excludes important confounding factors, as different virus variants, restriction policies or vaccines. The short-term relationship between the infection maximum increase and demographic, pollution and meteo-climatic parameters was investigated, including both winter-spring and summer 2020 data, also focusing separately on the two seasonal periods and on North vs Centre-South. Among main results, the importance of population size confirmed social distancing as a key management option. The pollution hazardous role undoubtedly emerged, as NO2 affected infection increase in all the studied scenarios, PM2.5 manifested its impact in North of Italy, while O3 always showed a protective action. Whereas higher temperatures were beneficial, especially in the cold season with also wind and relative humidity, solar irradiance was always relevant, revealing several significant interactions with other co-factors. Presented findings address the importance of the environment in Sars-CoV-2 spread and indicated that special carefulness should be taken in crowded areas, especially if they are highly polluted and weakly exposed to sun. The results suggest that containment of future epidemics similar to Covid-19 could be supported by reducing environmental pollution, achieving safer social habits and promoting preventive health care for better immune system response, as an only comprehensive strategy.

COVID-19 in the U.S. during pre-vaccination period: Shifting impact of sociodemographic factors and air pollution

Pandemic "wave" usually refers to the rise and fall of the infections with time, however, for a large country, the variations due to geographical location could be considerable. In this work, we investigated COVID-19 infection and fatality across the U.S. during the pandemic waves in the pre-vaccination period (January 2020-December 2020). Focusing on counties with a population ≥100,000, the data from the entire period were first segmented into two equal phases roughly corresponding to the first pandemic wave and subsequent surge, and each phase was further divided into two zones based on infection rate. We studied the potential influences of six sociodemographic variables (population density, age, poverty, education, and percentage of Hispanic and African American population) and four air pollutants (PM2.5, NO2, SO2, and O3) on the differences in infection and fatality observed among different phases and zones. We noticed a distinct difference in the overall impact of COVID-19 between the two phases of the pre-vaccination period with a substantial decrease in the fatality in the second phase despite an increase in the infection. Analysis using log-linear regression modeling further revealed a shift in the impact of several risk factors considered in this study. For example, population density and lesser education were found to be significant for infection during the first phase of the pandemic alone. Furthermore, population density and lesser education along with poverty and NO2 level had a significant contribution to fatality during the first phase of the pandemic, while age over 65 years was important in both phases. Interestingly, the effects of many of these factors were found to be significant only in the zones with higher infection rates. Our findings indicate that the impacts of several well-known sociodemographic and environmental risk factors for COVID-19 are not constant throughout the course of the pandemic, and therefore, careful considerations should be made about their role when developing preventative and mitigative measures.

Ambient Air Pollutant Exposures and COVID-19 Severity and Mortality in a Cohort of Patients with COVID-19 in Southern California

Rationale: Ecological studies have shown air pollution associations with coronavirus disease (COVID-19) outcomes. However, few cohort studies have been conducted. Objectives: To conduct a cohort study investigating the association between air pollution and COVID-19 severity using individual-level data from the electronic medical record. Methods: This cohort included all individuals who received diagnoses of COVID-19 from Kaiser Permanente Southern California between March 1 and August 31, 2020. One-year and 1-month averaged ambient air pollutant (particulate matter ⩽2.5 μm in aerodynamic diameter [PM_2.5], NO₂, and O₃) exposures before COVID-19 diagnosis were estimated on the basis of residential address history. Outcomes included COVID-19-related hospitalizations, intensive respiratory support (IRS), and ICU admissions within 30 days and mortality within 60 days after COVID-19 diagnosis. Covariates included socioeconomic characteristics and comorbidities. Measurements and Main Results: Among 74,915 individuals (mean age, 42.5 years; 54% women; 66% Hispanic), rates of hospitalization, IRS, ICU admission, and mortality were 6.3%, 2.4%, 1.5%, and 1.5%, respectively. Using multipollutant models adjusted for covariates, 1-year PM_2.5 and 1-month NO₂ average exposures were associated with COVID-19 severity. The odds ratios associated with a 1-SD increase in 1-year PM_2.5 (SD, 1.5 μg/m³) were 1.24 (95% confidence interval [CI], 1.16-1.32) for COVID-19-related hospitalization, 1.33 (95% CI, 1.20-1.47) for IRS, and 1.32 (95% CI, 1.16-1.51) for ICU admission; the corresponding odds ratios associated with 1-month NO₂ (SD, 3.3 ppb) were 1.12 (95% CI, 1.06-1.17) for hospitalization, 1.18 (95% CI, 1.10-1.27) for IRS, and 1.21 (95% CI, 1.11-1.33) for ICU admission. The hazard ratios for mortality were 1.14 (95% CI, 1.02-1.27) for 1-year PM_2.5 and 1.07 (95% CI, 0.98-1.16) for 1-month NO₂. No significant interactions with age, sex or ethnicity were observed. Conclusions: Ambient PM_2.5 and NO₂ exposures may affect COVID-19 severity and mortality.

Ambient air pollution and COVID-19 incidence during four 2020-2021 case surges

BACKGROUND

Air pollution exposure may make people more vulnerable to COVID-19 infection. However, previous studies in this area mostly focused on infection before May 2020 and long-term exposure.

OBJECTIVE

To assess both long-term and short-term exposure to air pollution and COVID-19 incidence across four case surges from 03/1/2020 to 02/28/2021.

METHODS

The cohort included 4.6 million members from a large integrated health care system in southern California with comprehensive electronic medical records (EMR). COVID-19 cases were identified from EMR. Incidence of COVID-19 was computed at the census tract-level among members. Prior 1-month and 1-year averaged air pollutant levels (PM_2.5, NO₂, and O₃) at the census tract-level were estimated based on hourly and daily air quality data. Data analyses were conducted by each wave: 3/1/2020-5/31/2020, 6/1/202-9/30/2020, 10/1/2020-12/31/2020, and 1/1/2021-2/28/2021 and pooled across waves using meta-analysis. Generalized linear mixed effects models with Poisson distribution and spatial autocorrelation were used with adjustment for meteorological factors and census tract-level social and health characteristics. Results were expressed as relative risk (RR) per 1 standard deviation.

RESULTS

The cohort included 446,440 COVID-19 cases covering 4609 census tracts. The pooled RRs (95% CI) of COVID-19 incidence associated with 1-year exposures to PM_2.5, NO₂, and O₃ were 1.11 (1.04, 1.18) per 2.3 μg/m³,1.09 (1.02, 1.17) per 3.2 ppb, and 1.06 (1.00, 1.12) per 5.5 ppb respectively. The corresponding RRs (95% CI) associated with prior 1-month exposures were 1.11 (1.03, 1.20) per 5.2 μg/m³ for PM_2.5, 1.09 (1.01, 1.17) per 6.0 ppb for NO₂ and 0.96 (0.85, 1.08) per 12.0 ppb for O₃.

CONCLUSION

Long-term PM_2.5 and NO₂ exposures were associated with increased risk of COVID-19 incidence across all case surges before February 2021. Short-term PM_2.5 and NO₂ exposures were also associated. Our findings suggest that air pollution may play a role in increasing the risk of COVID-19 infection.

On the footsteps of Hippocrates, Sanctorius and Harvey to better understand the influence of cold on the occurrence of COVID-19 in European countries in 2020

COVID-19 pandemic has been characterized by a pattern of consecutive declines and regrowth in European countries in 2020. After being partially regressed during the summer, the reappearance of the infection during fall 2020 in many temperate countries strongly suggests that temperature and cold may play a role in influencing the infectivity and virulence of SARS-CoV-2. While promoting medicine as an art, Hippocrates interpreted with logical reasoning the occurrence of diseases such as epidemics, as a consequence of environmental factors, in particular climatic variations. During the Renaissance, Sanctorius was one of the first to perform quantitative measurements, and Harvey discovered the circulation of blood by performing experimental procedures in animals. We think that a reasoning mixing various observations, measurements and experiments is fundamental to understand how cold increases infectivity and virulence of SARS-CoV-2. By this review, we provide evidence linking cold, angiotensin-II, vasoconstriction, hypoxia and aerobic glycolysis (the Warburg effect) to explain how cold affects the epidemiology of COVID-19. Also, a low humidity increases virus transmissibility, while a warm atmosphere, a moderate airway humidity, and the production of vasodilator angiotensin 1-7 by ACE2 are less favorable to the virus entry and/or its development. The meteorological and environmental parameters impacting COVID-19 pandemic should be reintegrated into a whole perspective by taking into account the different factors influencing transmissibility, infectivity and virulence of SARS-CoV-2. To understand the modern enigma represented by COVID-19, an interdisciplinary approach is surely essential.

Emerging role of air pollution and meteorological parameters in COVID-19

Exposure to air pollutants has been associated with respiratory viral infections. Epidemiological studies have shown that air pollution exposure is related to increased cases of SARS-COV-2 infection and COVID-19-associated mortality. In addition, the changes of meteorological parameters have also been implicated in the occurrence and development of COVID-19. However, the molecular mechanisms by which pollutant exposure and changes of meteorological parameters affects COVID-19 remains unknown. This review summarizes the biology of COVID-19 and the route of viral transmission, and elaborates on the relationship between air pollution and climate indicators and COVID-19. Finally, we envisaged the potential roles of air pollution and meteorological parameters in COVID-19.

Air pollution by NO2 and PM2.5 explains COVID-19 infection severity by overexpression of angiotensin-converting enzyme 2 in respiratory cells: a review

Many major cities that witnessed heavy air pollution by nitrogen dioxide (NO2) and particulate matter (PM) have experienced a high rate of infection and severity of the coronavirus disease pandemic (COVID-19). This phenomenon could be explained by the overexpression of the angiotensin converting enzyme 2 (ACE-2) on epithelial cell surfaces of the respiratory tract. Indeed, ACE-2 is a receptor for coronaviruses including the severe acute respiratory syndrome coronavirus 1 and 2 (SARS-CoV), and ACE-2 is overexpressed under chronic exposure to air pollution such as NO2 and PM2.5. In this review, we explain that ACE-2 acts as the sole receptor for the attachment of the SARS-CoV-2 via its spike protein. The fact that respiratory and vascular epithelial cells express ACE-2 has been previously observed during the 2003 epidemic of the SARS-CoV-1 in China, and during the 2012 Middle East respiratory syndrome in Saudi Arabia. High ACE-2 expression in respiratory epithelial cells under air pollution explains the positive correlation between the severity in COVID-19 patients and elevated air pollution, notably high NO2 and PM2.5 levels. Specific areas in India, China, Italy, Russia, Chile and Qatar that experience heavy air pollution also show high rates of COVID-19 infection and severity. Overall, we demonstrate a link between NO2 emissions, PM2.5 levels, ACE-2 expression and COVID-19 infection severity. Therefore, air pollution should be reduced in places where confirmed cases of COVID-19 are unexpectedly high.

Two important controversial risk factors in SARS-CoV-2 infection: Obesity and smoking

The effects of obesity and smoking in the coronavirus disease 2019 (COVID-19) pandemic remain controversial. Angiotensin converting enzyme 2 (ACE2), a component of the renin-angiotensin system (RAS), is the human cell receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. ACE2 expression increases on lung alveolar epithelial cells and adipose tissue due to obesity, smoking and air pollution. A significant relationship exists between air pollution and SARS-CoV-2 infection, as more severe COVID-19 symptoms occur in smokers; comorbid conditions due to obesity or excess ectopic fat accumulation as underlying risk factors for severe COVID-19 strongly encourage the virus/ACE2 receptor-ligand interaction concept. Indeed, obesity, air pollution and smoking associated risk factors share underlying pathophysiologies that are related to the Renin-Angiotensin-System in SARS-CoV-2 infection. The aim of this review is to emphasize the mechanism of receptor-ligand interaction and its impact on the enhanced risk of death due to SARS-CoV-2 infection.

SARS-CoV-2, ACE2, and Hydroxychloroquine: Cardiovascular Complications, Therapeutics, and Clinical Readouts in the Current Settings

The rapidly evolving coronavirus disease 2019 (COVID-19, caused by severe acute respiratory syndrome coronavirus 2- SARS-CoV-2), has greatly burdened the global healthcare system and led it into crisis in several countries. Lack of targeted therapeutics led to the idea of repurposing broad-spectrum drugs for viral intervention. In vitro analyses of hydroxychloroquine (HCQ)'s anecdotal benefits prompted its widespread clinical repurposing globally. Reports of emerging cardiovascular complications due to its clinical prescription are revealing the crucial role of angiotensin-converting enzyme 2 (ACE2), which serves as a target receptor for SARS-CoV-2. In the present settings, a clear understanding of these targets, their functional aspects and physiological impact on cardiovascular function are critical. In an up-to-date format, we shed light on HCQ's anecdotal function in stalling SARS-CoV-2 replication and immunomodulatory activities. While starting with the crucial role of ACE2, we here discuss the impact of HCQ on systemic cardiovascular function, its associated risks, and the scope of HCQ-based regimes in current clinical settings. Citing the extent of HCQ efficacy, the key considerations and recommendations for the use of HCQ in clinics are further discussed. Taken together, this review provides crucial insights into the role of ACE2 in SARS-CoV-2-led cardiovascular activity, and concurrently assesses the efficacy of HCQ in contemporary clinical settings.

Renin-angiotensin system at the heart of COVID-19 pandemic

Significant aspects of COVID-19 pandemic remain obscure. Angiotensin converting enzyme 2 (ACE2), a component of the renin-angiotensin system, whose expression dominates on lung alveolar epithelial cells, is the human cell receptor of SARS-CoV-2, the causative agent of COVID-19. We strongly encourage the concept that thorough considerations of receptor-ligand interactions should be kept at the heart of scientific debate on infection. In this idea, the whole renin-angiotensin system has to be evaluated. We hypothesize that factors related to ethnicity, environment, behaviors, associated illness, and medications involving this complex system are probably responsible for situations regarded as anomalous from both an epidemiological and a clinical point of view, but, taken together, such factors may explain most of the aspects of current outbreak. We decided to use the analogy of a play and speculate about the possible impact in this tragedy of 1) air pollution via the interference of nitrogen dioxide on ACE2 expression; 2) the dual role of nicotine; 3) the hypothetical involvement of ACE2 polymorphisms, the relationships of which with ethnic factors and susceptibility to cardiovascular disease seems intriguing; 4) the impact on the severity of infection of hypertension and related medications acting on the renin/angiotensin system, and, finally, 5) the possible helpful role of chloroquine, thanks to its capacity of modifying ACE2 affinity to the viral spike protein by altering glycosylation. This hypothesis paper is an urgent call for the development of research programs that aim at questioning whether the putative protagonists of this tragedy are real-life actors in COVID-19.

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Significant aspects of COVID-19 pandemic remain obscure.

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Angiotensin converting enzyme 2 (ACE2) is the human cell receptor of SARS-CoV-2.

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Receptor-ligand interactions, should be kept at the heart of scientific debate.

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Ethnicity, environment, and behaviors factors interfere with these interactions.

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Associated illness, and medications also interfere in a possibly dual manner.

Stem cells in the lung

The lung is composed of two major anatomically distinct regions-the conducting airways and gas-exchanging airspaces. From a cell biology standpoint, the conducting airways can be further divided into two major compartments, the tracheobronchial and bronchiolar airways, while the alveolar regions of the lung make up the gas-exchanging airspaces. Each of these regions consists of distinct epithelial cell types with unique cellular physiologies and stem cell compartments. This chapter focuses on model systems with which to study stem cells in the adult tracheobronchial airways, also referred to as the proximal airway of the lung. Important in such models is an appreciation for the diversity of stem cell niches in the conducting airways that provide localized environmental signals to both maintain and mobilize stem cells in the setting of airway injury and normal cellular turnover. Because cellular turnover in airways is relatively slow, methods for analysis of stem cells in vivo have required prior injury to the lung. In contrast, ex vivo and in vitro models for analysis of airway stem cells have used genetic markers to track lineage relationships together with reconstitution systems that mimic airway biology. Over the past decades, several widely acceptable methods have been developed and used in the characterization of adult airway stem/progenitor cells. These include localization of label-retaining cells (LRCs), retroviral tagging of epithelial cells seeded into xenografts, air-liquid interface cultures to track clonal proliferative potential, and multiple transgenic mouse models. This chapter reviews the biologic context and use of these models while providing detailed methods for several of the more broadly useful models for studying adult airway stem/progenitor cell types.

Development of a rabbit model to investigate the effects of acute nitrogen dioxide intoxication

1. In previous studies a rat inhalation model was developed to investigate the effects of intervention after acute NO2 exposure. The object of the present study was to investigate whether acute NO2 intoxication induced comparable effects in rabbits as it does in rats. Where the effects of intervention in both species are similar, then the conclusions drawn from these studies may have more relevance for the treatment of man. 2. Biochemical variables in bronchoalveolar lavage and supernatant from lung homogenate, which may be relevant for the evaluation of lung injury and repair, were investigated and compared with histology. 3. After NO2 exposure for 10 min, the pulmonary effects observed became more pronounced with increasing NO2 concentrations (0, 125, 175, 250, 400, 600 or 800 ppm) [1 ppm NO2 is 1.88 mg m-3]. The effects in rabbits were found to be broadly comparable with those in rats. 4. To achieve severe lung injury in rabbits without mortality, enabling investigations of the effects of intervention over several days, exposure to a NO2 concentration of 600 ppm for 10 min was most appropriate, while a concentration of 175 ppm NO2 was needed to attain comparable effects in rats. 5. The repair phase starts later, namely at 3 days after exposure in rats, compared to 5 days in rabbits.

No beneficial effect of N-acetylcysteine treatment on broncho-alveolar lavage fluid variables in acute nitrogen dioxide intoxicated rats

1. In previous studies a rat inhalation model was developed to investigate the efficacy of treatment in acute NO2 intoxication. 2. N-acetylcysteine (NAC) was administered intravenously to study its effect on biochemical variables in broncho-alveolar lavage fluid in acute NO2 intoxicated rats. It was decided to start the intravenous administration of NAC 24 h before the exposure to NO2 to induce higher intracellular glutathione (GSH) levels in lung cells of NAC-treated rats compared to not NAC-treated rats. Because, on theoretical grounds, the therapeutic effect of NAC may be expected to be especially marked during the first 24 h after exposure, the rats were observed for a period of 24 h and were then killed for investigation. A loading dose of 85 mg kg-1 h-1 or 170 mg kg-1 h-1 was followed by a continuous infusion (until autopsy) with a dose of 225 mg kg-1 24 h-1 or 450 mg kg-1 24 h-1 respectively. 3. Twenty four hours after exposure to 175 ppm NO2 (1 ppm is 1.88 mg m-3) for 10 min, NAC did not reduce the increase of variables in broncho-alveolar lavage fluid which reflect the severity of lung damage. 4. The protein and albumin concentration and the activities of angiotensin converting enzyme and alkaline phosphatase in broncho-alveolar lavage fluid after NO2 exposure were even more increased in the NAC-treated than in the saline-treated rats, but none of the differences was statistically significant. 5. In sham exposed rats no effect of NAC was observed.

Desferrioxamine treatment reduces histological evidence of lung damage in rats after acute nitrogen dioxide (NO2) intoxication

1. In previous studies a rat inhalation model was developed to investigate the efficacy of treatment in acute NO2 intoxication. 2. Desferrioxamine was administered intravenously to study its effect on histological alterations in lung tissue in rats after acute NO2 exposure. 3. Twenty four hours after exposure to 175 ppm NO2 for 10 minutes the lung injury observed by light microscopy in the desferrioxamine treated rats was less pronounced than in the saline treated rats. 4. Desferrioxamine appeared to provide more protection with a dose of 100 mg kg-1 24 h-1 than with 200 mg kg-1 24 h-1.