Titanium Dioxide Nanoparticles Modulate Systemic Immune Response and Increase Levels of Reduced Glutathione in Mice after Seven-Week Inhalation

Poor Respiratory Health is a Consequence of Dhaka's Polluted Air: A Bangladeshi Perspective

Dhaka, which is the capital and largest metropolis of Bangladesh, has seen an increase in the number of documented cases of respiratory disorders. Every day in Dhaka city, a remarkable number of patients are being diagnosed with poor respiratory conditions. The majority of these patients have no other severe disease history and mostly need to be exposed to outdoor air to meet their occupational requirements, indicating that the ailment may be associated with polluted air. As this is the most pressing issue that must be addressed in order to safeguard public health, we have made an effort to focus on the current situation surrounding the sources of air pollution in the city. Since this is a viewpoint article, we gathered data from various published articles, national dailies, and international reports generated by WHO, CDC, BBC, or other environmental news/report portals to highlight the public health issue related to respiratory health. Poor respiratory health is one of the main consequences of Dhaka's contaminated air, as determined by our analysis.

Transferability and reproducibility of exposed air-liquid interface co-culture lung models

BACKGROUND

The establishment of reliable and robust in vitro models for hazard assessment, a prerequisite for moving away from animal testing, requires the evaluation of model transferability and reproducibility. Lung models that can be exposed via the air, by means of an air-liquid interface (ALI) are promising in vitro models for evaluating the safety of nanomaterials (NMs) after inhalation exposure. We performed an inter-laboratory comparison study to evaluate the transferability and reproducibility of a lung model consisting of the human bronchial cell line Calu-3 as a monoculture and, to increase the physiologic relevance of the model, also as a co-culture with macrophages (either derived from the THP-1 monocyte cell line or from human blood monocytes). The lung model was exposed to NMs using the VITROCELL® Cloud12 system at physiologically relevant dose levels.

RESULTS

Overall, the results of the 7 participating laboratories are quite similar. After exposing Calu-3 alone and Calu-3 co-cultures with macrophages, no effects of lipopolysaccharide (LPS), quartz (DQ12) or titanium dioxide (TiO2) NM-105 particles on the cell viability and barrier integrity were detected. LPS exposure induced moderate cytokine release in the Calu-3 monoculture, albeit not statistically significant in most labs. In the co-culture models, most laboratories showed that LPS can significantly induce cytokine release (IL-6, IL-8 and TNF-α). The exposure to quartz and TiO2 particles did not induce a statistically significant increase in cytokine release in both cell models probably due to our relatively low deposited doses, which were inspired by in vivo dose levels. The intra- and inter-laboratory comparison study indicated acceptable interlaboratory variation for cell viability/toxicity (WST-1, LDH) and transepithelial electrical resistance, and relatively high inter-laboratory variation for cytokine production.

CONCLUSION

The transferability and reproducibility of a lung co-culture model and its exposure to aerosolized particles at the ALI were evaluated and recommendations were provided for performing inter-laboratory comparison studies. Although the results are promising, optimizations of the lung model (including more sensitive read-outs) and/or selection of higher deposited doses are needed to enhance its predictive value before it may be taken further towards a possible OECD guideline.