Crocidolite asbestos and SV40 are cocarcinogens in human mesothelial cells and in causing mesothelioma in hamsters

Only a fraction of subjects exposed to asbestos develop malignant mesothelioma (MM), suggesting that additional factors may render some individuals more susceptible. We tested the hypothesis that asbestos and Simian virus (SV40) are cocarcinogens. Asbestos and SV40 in combination had a costimulatory effect in inducing ERK1/2 phosphorylation and activator protein-1 (AP-1) activity in both primary Syrian hamster mesothelial cells (SHM) and primary human mesothelial cells (HM). Ap-1 activity caused the expression and activation of matrix metalloprotease (MMP)-1 and MMP-9, which in turn led to cell invasion. Experiments using siRNA and chemical inhibitors confirmed the specificity of these results. The same effects were observed in HM and SHM. Experiments in hamsters showed strong cocarcinogenesis between asbestos and SV40: SV40 did not cause MM, asbestos caused MM in 20% of hamsters, and asbestos and SV40 together caused MM in 90% of hamsters. Significantly lower amounts of asbestos were sufficient to cause MM in animals infected with SV40. Our results indicate that mineral fibers and viruses can be cocarcinogens and suggest that lower amounts of asbestos may be sufficient to cause MM in individuals infected with SV40.

Cell signaling and transcription factor activation by asbestos in lung injury and disease

Signaling pathways initiated at the external cell surface or within the cytoplasm regulate transactivation of transcription factors and gene expression that are causally related to a number of critical cellular outcomes including proliferation, apoptosis, cell survival, and production of inflammatory cytokines. Asbestos, a ubiquitous pathogenic group of mineral fibers, can stimulate gene expression in a variety of cell types in the lung via intracellular signaling pathways. These cell signaling cascades may be initiated through receptor-mediated events or integrins. Alternatively, they may be stimulated by oxidants generated both during phagocytosis of minerals and/or by redox reactions on the mineral surface. Once initiated, these pathways can lead to promotion of gene expression critical to cellular injury, proliferation and inflammation-events leading to the development of fibroproliferative diseases of the lung and pleura. The elucidation and relevance of critical signaling cascades to lung injury or repair following asbestos exposure could aid in developing strategies to prevent or treat asbestos-associated lung and pleural diseases.

Gene expression profiles reveal increased mClca3 (Gob5) expression and mucin production in a murine model of asbestos-induced fibrogenesis

To elucidate genes important in development or repair of asbestos-induced lung diseases, gene expression was examined in mice after inhalation of chrysotile asbestos for 3, 9, and 40 days. We identified changes in the expression of genes linked to proliferation (cyclin B2, CDC20, and CDC28 protein kinase regulatory subunit 2), inflammation (CCL9, CCL6, complement component 1, chitinase3-like 3, TNF superfamily member 10, and IL-1B), and matrix remodeling (MMP12, MMP3, integrin alphaX, and cathepsins K, Z, B, and S). The most highly induced gene at all time points was mclca3 (gob5), a putative calcium-activated chloride channel involved in the regulation of mucus production and/or secretion. Using histochemistry, we demonstrated accumulation of mucus and increased mClca3 protein in the bronchiolar epithelium of asbestos-exposed mice at all time points but peaking at 9 days. Cytokine levels (interleukin-1beta, interleukin-4, interleukin-6) in bronchoalveolar lavage fluid also increased at 9 days, suggesting Th2-mediated immunity may play a role in asbestos-induced mucus production. In contrast, levels of cathepsin K, a potent elastase, increased between 3 and 40 days at both the mRNA and protein levels, localizing primarily in CD45-positive leukocytes and interstitial cells. Identification of genes involved in lung injury and remodeling after asbestos exposure could aid in defining mechanisms of airborne particulate-induced disease and in developing therapeutic strategies.

Comparison of virus concentration methods for the reverse-transcriptase quantitative PCR (RT-qPCR)-based detection of bacteriophage Φ6, an enveloped virus surrogate for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA, from untreated wastewater at St. George’s University (SGU), Grenada

Introduction/Objective

With the ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the consequent opening of borders, it is of paramount importance to monitor communities for the presence of potential COVID-19 clusters. Wastewater-based epidemiology (WBE) is an effective way to monitor community spread of pathogens and has been implemented in many countries to identify potential outbreaks. Most standardized methodologies used in WBE for the detection of viruses have been validated for non-enveloped viruses; therefore, there is a need for the creation of a standardized method for the detection of enveloped viruses, such as SARS-CoV-2.

Methods/Case Report

Wastewater seeded with a Pseudomonas syringae bacteriophage (Φ6) was used to test the efficiency of five wastewater virus concentration methods. Two methods were based on AlCl3 flocculation with different pH adjustments. The other methods utilized membrane filtration followed by beef elution: one added a pretreatment with HCl; another added a pretreatment with MgCl2; and finally, an untreated control. A known amount of Bacteriophage Φ6 was used for all methods, and detection was quantified by reverse-transcription quantitative polymerase chain reaction.

Results (if a Case Study enter NA)

The Cq values for each method, ranging from 24.38–38.6, were compared. The highest recovery of Φ6 was obtained with the AlCl3 flocculation method with an adjusted pH of 6, followed in descending order by MgCl2-pretreated sample with beef elution; HCl-pretreated sample with beef elution, the untreated sample, and AlCl3 flocculation method with an adjusted pH of 3.5.

Conclusion

The results suggest that AlCl3 flocculation with an adjusted pH of 6 may be a quick and cost-effective methodology for the detection of enveloped viruses in WBE. This can facilitate the implementation of WBE at SGU, Grenada, as a useful tool to conduct active surveillance and track outbreaks of enveloped viral diseases, such as SARS-CoV-2.