Effects of ozone and sulfur dioxide on virus growth in mice

Stronger susceptibilities to air pollutants of influenza A than B were identified in subtropical Shenzhen, China

Air pollution was indicated to be a key factor contributing to the aggressive spread of influenza viruses, whereas uncertainty still exists regarding to whether distinctions exist between influenza subtypes. Our study quantified the impact of five air pollutants on influenza subtype outbreaks in Shenzhen, China, a densely populated and highly urbanized megacity. Daily influenza outbreak data of laboratory-confirmed positive cases were obtained from the Shenzhen CDC, from May 1, 2013 to Dec 31, 2015. Concentrations of nitrogen dioxide (NO₂), sulfur dioxide (SO₂), particulate matters ≤2.5 μm (PM_2.5), particulate matters ≤10 μm (PM₁₀), and ozone (O₃), were retrieved from the 18 national monitoring stations. The generalized additive model (GAM) and distributed lag non-linear model (DLNM) were used to calculate the concentration-response relationships between environmental inducers and outbreak epidemics, respectively for influenza A (Flu-A) and B (Flu-B). There were 1687 positive specimens were confirmed during the study period. The cold season was restricted from Nov. 4th to Apr. 20th, covering all seasons other than the long-lasting summer. Relatively heavy fine particle matter (PM_2.5) and NO₂ pollution was observed in cold months, with mean concentrations of 46.06 μg/m³ and 40.03 μg/m³, respectively. Time-series analysis indicated that high concentrations of NO₂, PM_2.5, PM₁₀, and O₃ were associated with more influenza outbreaks at short lag periods (0-5 d). Although more Flu-B (679 cases) epidemics occurred than Flu-A (382 cases) in the cold season, Flu-A generally showed higher susceptibility to air pollutants. A 10 μg/m³ increment in concentrations of PM_2.5, PM₁₀, and O₃ at lag 04, was associated with a 2.103 (95%CI: 1.528-2.893), 1.618 (95%CI: 1.311-1.996), and 1.569 (95%CI: 1.214-2.028) of the relative risk (RR) of Flu-A, respectively. A 5 μg/m³ increase in NO₂ was associated with higher risk of Flu-A at lag 03 (RR = 1.646, 95%CI: 1.295-2.092) and of Flu-B at lag 04 (RR = 1.319, 95%CI: 1.095-1.588). Nevertheless, barely significant effect of particulate matters (PM_2.5, PM₁₀) on Flu-B and SO₂ on both subtypes was detected. Further, the effect estimates of NO₂ increased for both subtypes when coexisting with other pollutants. This study provides evidence that declining concentrations of main pollutants including NO₂, O₃, and particulate matters, could substantially decrease influenza risk in subtropical Shenzhen, especially for influenza A.

Impact of air pollutants on influenza-like illness outpatient visits under COVID-19 pandemic in the subcenter of Beijing, China

This study aimed to explore the association between air pollutants and outpatient visits for influenza-like illnesses (ILI) under the coronavirus disease 2019 (COVID-19) stage in the subcenter of Beijing. The data on ILI in the subcenter of Beijing from January 1, 2018 to December 31, 2020 were obtained from the Beijing Influenza Surveillance Network. A generalized additive Poisson model was applied to examine the associations between the concentrations of air pollutants and daily outpatient visits for ILI when controlling meteorological factors and temporal trend. A total of 171 943 ILI patients were included. In the pre-coronavirus disease 2019 (COVID-19) stage, an increased risk of ILI outpatient visits was associated to a high air quality index (AQI) and the high concentrations of particulate matter less than 2.5 (PM_2.5 ), particulate matter 10 (PM₁₀ ), sulphur dioxide (SO₂ ), nitrogen dioxide (NO₂ ), and carbon monoxide (CO), and a low concentration of ozone (O₃ ) on lag0 day and lag1 day, while a higher increased risk of ILI outpatient visits was observed by the air pollutants in the COVID-19 stage on lag0 day. Except for PM₁₀ , the concentrations of other air pollutants on lag1 day were not significantly associated with an increased risk of ILI outpatient visits during the COVID-19 stage. The findings that air pollutants had enhanced immediate effects and diminished lag-effects on the risk of ILI outpatient visits during the COVID-19 pandemic, which is important for the development of public health and environmental governance strategies.

Impact of air pollutants on influenza-like illness outpatient visits under urbanization process in the sub-center of Beijing, China

Air pollutants can cause serious harm to human health and a variety of respiratory diseases. This study aimed to explore the associations between air pollutants and outpatient visits for influenza-like illness (ILI) under urbanization process in the sub-center of Beijing. The data of ILI in sub-center of Beijing from April 1, 2014 to December 31, 2020 were obtained from Beijing Influenza Surveillance Network. A generalized additive Poisson model was applied to examine the associations between the concentrations of air pollutants and daily outpatient visits for ILI when controlling meteorological factors and holidays. A total of 322,559 patients with ILI were included. The results showed that in the early urbanization period, the effects of PM_2.5, PM₁₀, SO₂, O₃, and CO on lag0 day, and PM_2.5, PM₁₀, O₃, and CO on lag1 day were not significant. In the later urbanization period, AQI and the concentrations of PM_2.5, PM₁₀, SO₂, NO₂ and CO on lag1 day were all significantly associated with an increased risk of outpatient visits for ILI, which increased by 0.34% (95%CI 0.23%, 0.45%), 0.42% (95%CI 0.29%, 0.56%), 0.44% (95%CI 0.33%, 0.55%), 0.36% (95%CI 0.24%, 0.49%), 0.91% (95%CI 0.62%, 1.21%) and 0.38% (95%CI 0.26%, 0.49%). The concentration of O₃ on lag1 day was significantly associated with a decreased risk of outpatient visits for ILI, which decreased by 0.21% (95%CI 0.04%, 0.39%). We found that the urbanization process had significantly aggravated the impact of air pollutants on ILI outpatient visits. These findings expand the current knowledge of ILI outpatient visits correlated with air pollutants under urbanization process.

Epidemiology of influenza in hospitalized children with respiratory tract infection in Suzhou area from 2016 to 2019

Influenza is a contagious respiratory disease and risks public health in China, and it has caused wide public concern in recent years. Immunocompromised patients, such as children and elderly people, suffer more severe influenza complication and some extreme cases are even life threatening. To identify the influenza characteristics and its correlation with various climatic and environmental pollution factors, we collected the reported influenza epidemic of hospitalized children in Children's Hospital of Soochow University from 2016 to 2019. Our results show that the main influenza virus subtypes are A/H1N1, A/H3N2, B/BV, and B/BY. We also identified the characteristics of the prevalent influenza virus subtypes in different months, seasons, years, and patients' age. Of all the influenza infected patients, the most susceptible groups are children over 3 to 5 years of age, and more cases are reported in winter than other seasons. We also found that influenza is also highly correlated with climatic and environmental pollution factors, and the autoregressive integrated moving average model is employed for the short-term influenza prediction in Suzhou city, which can provide scientific basis for the prevention and control of influenza and public health decision-making.

The short-term effects of air pollutants on influenza-like illness in Jinan, China

Background

There is valid evidence that air pollution is associated with respiratory disease. However, few studies have quantified the short-term effects of six air pollutants on influenza-like illness (ILI). This study explores the potential relationship between air pollutants and ILI in Jinan, China.

Methods

Daily data on the concentration of particulate matters < 2.5 μm (PM 2.5), particulate matters < 10 μm (PM10), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃) and ILI counts from 2016 to 2017 were retrieved. The wavelet coherence analysis and generalized poisson additive regression model were employed to qualify the relationship between air pollutants and ILI risk. The effects of air pollutants on different age groups were investigated.

Results

A total of 81,459 ILI counts were collected, and the average concentrations of PM2.5, PM10, O₃, CO, SO₂ and NO₂ were 67.8 μg/m³, 131.76 μg/ m³, 109.85 μg/ m³, 1133 μg/ m³, 33.06 μg/ m³ and 44.38 μg/ m³, respectively. A 10 μg/ m³ increase in concentration of PM2.5, PM10, CO at lag0 and SO₂ at lag01, was positively associated with a 1.0137 (95% confidence interval (CI): 1.0083–1.0192), 1.0074 (95% CI: 1.0041–1.0107), 1.0288 (95% CI: 1.0127–1.0451), and 1.0008 (95% CI: 1.0003–1.0012) of the relative risk (RR) of ILI, respectively. While, O3 (lag5) was negatively associated with ILI (RR 0.9863; 95%CI: 0.9787–0.9939), and no significant association was observed with NO₂, which can increase the incidence of ILI in the two-pollutant model. A short-term delayed impact of PM2.5, PM10, SO2 at lag02 and CO, O3 at lag05 was also observed. People aged 25–59, 5–14 and 0–4 were found to be significantly susceptible to PM2.5, PM10, CO; and all age groups were significantly susceptible to SO₂; People aged ≥60 year, 5–14 and 0–4 were found to be significantly negative associations with O₃.

Conclusion

Air pollutants, especially PM2.5, PM10, CO and SO₂, can increase the risk of ILI in Jinan. The government should create regulatory policies to reduce the level of air pollutants and remind people to practice preventative and control measures to decrease the incidence of ILI on pollution days.

Effects of air pollutants on occurrences of influenza-like illness and laboratory-confirmed influenza in Hefei, China

Accumulating evidence suggests that air pollution is a risk factor for adverse respiratory and cardiovascular health outcomes. However, the different impacts of exposure to air pollutants on influenza virus activity and influenza-like illness (ILI) have not been well documented in epidemiological studies. We examined the association between air pollutants of particular matters < 2.5 μm (PM_2.5), particular matters < 10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and influenza occurrences in Hefei, China, from December 2013 to December 2015 by generalized Poisson additive regression models. The result suggested that PM_2.5 and PM₁₀ had similar effects on clinical ILI and influenza incidence. PM₁₀ was negatively associated with clinical ILI (relative risk (RR) 0.980, 95% confidence interval (CI) 0.974-0.987), while PM_2.5 were positively associated with clinical ILI (RR 1.040; 95% CI 1.032-1.049). RRs for the laboratory-confirmed cases of influenza were 0.813 (95% CI, 0.755-0.875) for PM₁₀ and 1.216 (95% CI, 1.134-1.304) for PM_2.5. Nevertheless, the impacts of SO₂ and NO₂ on ILI and influenza were distinct. SO₂ had significant influence on laboratory-confirmed influenza and had no significant linear relationship with ILI. NO₂ was negatively correlated with influenza but had no obvious effect on clinical ILI cases. The present study contributes novel evidence on understanding of the effects of various air pollutants on influenza activities, and these findings can be useful and important for the development of influenza surveillance and early warning systems.

Modification by influenza on health effects of air pollution in Hong Kong

BACKGROUND

Both influenza viruses and air pollutants have been well documented as major hazards to human health, but few epidemiologic studies have assessed effect modification of influenza on health effects of ambient air pollutants.

OBJECTIVES

We aimed to assess modifying effects of influenza on health effects of ambient air pollutants.

METHODS

We applied Poisson regression to daily numbers of hospitalizations and mortality to develop core models after adjustment for potential time-varying confounding variables. We assessed modification of influenza by adding variables for concentrations of single ambient air pollutants and proportions of influenza-positive specimens (influenza intensity) and their cross-product terms.

RESULTS

We found significant effect modification of influenza (p < 0.05) for effects of ozone. When influenza intensity is assumed to increase from 0% to 10%, the excess risks per 10-microg/m(3) increase in concentration of O(3) increased 0.24% and 0.40% for hospitalization of respiratory disease in the all-ages group and >or= 65 year age group, respectively; 0.46% for hospitalization of acute respiratory disease in the all-ages group; and 0.40% for hospitalization of chronic obstructive pulmonary disease in the >or= 65 group. The estimated increases in the excess risks for mortality of respiratory disease and chronic obstructive pulmonary disease in the all-ages group were 0.59% and 1.05%, respectively. We found no significant modification of influenza on effects of other pollutants in most disease outcomes under study.

CONCLUSIONS

Influenza activity could be an effect modifier for the health effects of air pollutants particularly for O(3) and should be considered in the studies for short-term effects of air pollutants on health.

Effect of ozone on susceptibility to respiratory viral infection and virus-induced cytokine secretion

Airway epithelium is the primary target tissue for respiratory viruses as well as an important target of ozone (O(3)) toxicity. A change in the severity of viral airway infection may result from changes in epithelial cell susceptibility to infection, metabolic interference with viral replication, or altered production of immune regulatory molecules by the infected cells as a result of exposure to O(3). In this study we have investigated whether O(3) exposure alters the susceptibility of human airway epithelial cells to respiratory syncytial virus (RSV) infection, the production of infectious virus, and/or release of virus-induced cytokines IL-6 and IL-8. The epithelial cell line BEAS-2B grown on collagen-impregnated filters was exposed to O(3) (0.5 ppm for 60 min) or filtered air immediately before or 24 h after infection with RSV. Cells exposed to O(3) before RSV infection released 44% less virus over 4 days of infection while O(3) exposure post RSV infection had no effect on virus production. O(3) exposure preceding RSV infection showed short term additive effects of these treatments on epithelial cell IL-6 and IL-8 production, a decrease in cytokines at 48 h, but did not affect long term cytokine production by RSV-infected cells. Furthermore, O(3) exposure did not affect long term cytokine production by cells with an established RSV infection at the time of exposure. These data suggest that O(3) does not adversely affect viral airway infection, at least not on the level of the host cell for viral replication.

Inhalation of diesel exhaust enhances antigen-specific IgE antibody production in mice

To examine the effects of diesel exhaust (DE) inhalation on IgE antibody production, BALB/c mice were exposed to 0 (control), 3.0 and 6.0 mg/m3 DE inhalation for 3 weeks. Intranasal sensitization with ovalbumin (OA) three times at intervals of 3 weeks was conducted immediately before, immediately after and 3 weeks after DE inhalation. Body weight and thymus weight for the DE-exposed and control mice were essentially the same but spleen weight in mice exposed to 6 mg/m3 significantly increased. Anti-OA IgE antibody titers in the sera of mice exposed to 6 mg/m3 was significantly higher than the control. Total IgE and anti-OA IgG in sera for DE-exposed and control mice remained basically the same. To investigate cytokine production in mice exposed to 6 mg/m3, spleen cells from DE-exposed and control mice were stimulated with OA in vitro and cytokine production in the culture supernatants was measured by ELISA. In vitro antigen-stimulated interleukin-4 (IL-4) and -10 (IL-10) production in spleen cells of exposed mice significantly increased compared to the control. In vitro interferon (IFN)-gamma production in spleen cells of exposed mice markedly decreased. DE inhalation is thus shown to have adverse effect on antigen-specific IgE antibody production in mice through alteration of the cytokine network.

Factors that influence the suppression of pulmonary antibacterial defenses in mice exposed to ozone

Exposure to ozone (O3) has been shown to increase susceptibility of mice to bacterial infection; however, the underlying mechanism has not been well elucidated. This study investigated the effect of O3 exposure on the ability of mice to combat an infectious challenge of Streptococcus zooepidemicus. Following a 3-h exposure to either air, 0.4 ppm O3, or 0.8 ppm O3, 5- and 9-week-old mice received an aerosol infection of bacteria. Intrapulmonary killing of the bacteria was impaired in the O3-exposed mice. The effect was most severe at the higher dose of O3 in the younger mice, and showed good correlation to subsequent mortality assessed over a 20-day period. Alveolar macrophages (AM) from O3-exposed mice had an impaired ability to phagocytose the bacteria. Additionally, prostaglandin E2 (PGE2) levels, which are known to depress AM function, were increased in the bronchoalveolar lavage fluid of the younger mice following exposure to O3, while pretreatment with indomethacin in the drinking water blunted the increased of PGE2 and reduced O3 enhanced mortality from 53 to 33%. The data show that O3 inhalation can reduce the defensive capability of the murine lung and that this is associated with a reduction in AM phagocytosis. The defect is more marked in young mice, suggesting that they may be more susceptible to oxidant exposure. Further studies are required to distinguish between direct toxicity of O3 on the AM and indirect suppression due to modulation of pharmacologic or inflammatory mediators.

Reduction of influenza virus pathogenesis by exposure to 0.5 ppm ozone

Continuous exposure to 0.5 ppm ozone during the course of murine influenza A/PR8/34 virus infection reduced the severity of the disease as quantitated by histologic (morphometric), biochemical (serum albumin in lavage fluid), and gravimetric (lung wt/dry weight ratios) parameters of lung injury. The ozone-mediated abatement of the lung injury was independent of peak pulmonary virus titers. However, determination of the sites of virus multiplication indicated that exposure to ozone resulted in a less widespread infection of the lung parenchyma. Furthermore, ozone exposure reduced the antiviral immune response as shown by reduced numbers of phenotypically quantitated T- and B-lymphocytes recovered from lung tissues and reduction of serum antibody titers. Since the pathogenesis of influenza virus infection depends on both the site of viral replication and the antiviral immune response, these studies suggest that redistribution of virus growth in murine lungs and immunosuppressive mechanisms are factors in the ozone-reduced disease severity.

Exposure to ozone reduces influenza disease severity and alters distribution of influenza viral antigens in murine lungs

Exposure to ambient levels of ozone (0.5 ppm) was shown to alter the pathogenesis of respiratory infection after aerosol infection of mice with influenza A virus. A semiquantitative method for determination of the sites of virus replication by direct immunofluorescence indicated that exposure to ozone reduced the involvement of respiratory epithelium in the infectious process and resulted in a less widespread infection of the alveolar parenchyma. Furthermore, the ozone-mediated alteration in viral antigen distribution was consistent with significantly reduced influenza disease mortality and prolonged survival time, but only when the oxidant was present during the course of infection. Reduced disease severity in ozone-exposed animals appeared to be independent of peak pulmonary virus titers, pulmonary interferon titers, and pulmonary and serum-neutralizing antibody titers. These studies suggested that the distribution of influenza virus in the murine lung was a key factor in disease severity.