Urban Air Pollution Particulates Suppress Human T-Cell Responses to Mycobacterium Tuberculosis

Abstract

Tuberculosis (TB) and air pollution both contribute significantly to the global burden of disease. Epidemiological studies show that exposure to household and urban air pollution increase the risk of new infections with Mycobacterium tuberculosis (M.tb) and the development of TB in persons infected with M.tb and alter treatment outcomes. There is increasing evidence that particulate matter (PM) exposure weakens protective antimycobacterial host immunity. Mechanisms by which exposure to urban PM may adversely affect M.tb-specific human T cell functions have not been studied. We, therefore, explored the effects of urban air pollution PM2.5 (aerodynamic diameters ≤2.5µm) on M.tb-specific T cell functions in human peripheral blood mononuclear cells (PBMC). PM2.5 exposure decreased the capacity of PBMC to control the growth of M.tb and the M.tb-induced expression of CD69, an early surface activation marker expressed on CD3+ T cells. PM2.5 exposure also decreased the production of IFN-γ in CD3+, TNF-α in CD3+ and CD14+ M.tb-infected PBMC, and the M.tb-induced expression of T-box transcription factor TBX21 (T-bet). In contrast, PM2.5 exposure increased the expression of anti-inflammatory cytokine IL-10 in CD3+ and CD14+ PBMC. Taken together, PM2.5 exposure of PBMC prior to infection with M.tb impairs critical antimycobacterial T cell immune functions.

Satellite-detected tropospheric nitrogen dioxide and spread of SARS-CoV-2 infection in Northern Italy

“…In this study, we found a positive association between levels of NO 2 levels and subsequence prevalence of SARS-CoV-2 positivity in Northern Italy, though this occurred only at high levels of NO 2 . This relation is consistent with severe outdoor air pollution enhancing the spread of the SARS-CoV-2 virus, possibly by altering the immunological status and thus increasing individual susceptibility to infectious diseases (Ibironke et al, 2019;Marchini et al, 2020;Rivas-Santiago et al, 2015;Williams et al, 2011). The area of the study comprises the densest industrial, trading and agricultural zone in Italy, with an orography that favors the stagnation of pollutants.…”

Associations between mortality from COVID-19 in two Italian regions and outdoor air pollution as assessed through tropospheric nitrogen dioxide

“…Long-term exposure to air pollutant levels has been linked to chronic lung inflammation, thus possibly promoting an increased severity of COVID-19 syndrome (Shi et al, 2020). Air pollutants have also been shown to alter the immunological status and thus increasing individual susceptibility to infectious diseases (Ibironke et al, 2019;Marchini et al, 2020;Rivas-Santiago et al, 2015;Williams et al, 2011). As specifically regards trafficgenerated nitrogen dioxide, it has been shown to be associated with increased risk of rhinitis in adult population (Cesaroni et al, 2008; de Table 1 Cumulative number of total COVID-19 deaths, mortality rate (per 100,000 people) and nitrogen dioxide (NO 2 ) levels (μmol/m 2 ), before the lockdown, on March 8, March 22, and April 5 in Veneto and Emilia-Romagna regions.…”

The Interplay Between Air Pollution and Coronavirus Disease (COVID-19)

“… 7 There is mounting evidence that PM exposure weakens protective antimycobacterial host-immunity; air pollution increases the risk of new infections with Mycobacterium tuberculosis. 33 In this perspective, there are suggestions that BCG vaccines have a protective effect on COVID-19. The BCG vaccination reduces the viremia from viral respiratory tract infections by boosting non-specific Th1 an Th17 response.…”