The Effect of Therapeutic Blockades of Dust Particles-Induced Ca²⁺ Signaling and Proinflammatory Cytokine IL-8 in Human Bronchial Epithelial Cells

TRPM2 exacerbates airway inflammation by regulating oxidized-CaMKⅡ in allergic asthma

Background

Airway epithelial cells play important roles in allergic asthma. Transient receptor potential melastatin-related 2 (TRPM2) and oxidized Ca2+/calmodulin-dependent protein kinase Ⅱ (ox-CaMKⅡ) participate in the airway inflammation. This study aimed to analyze the effects of TRPM2 on ox-CaMKⅡ in the airway epithelial cells during allergic asthma.

Methods

BEAS-2B cells were treated with different dose of IL-13 (0, 5, 10, 20 ng/mL) for 24 h to analyze the changes of TRPM2 and ox-CaMKⅡ protein. Cells expressing different level of TRPM2 were obtained by transfection of TRPM2 siRNA or TRPM2-short cDNA. The transfected cells were treated with 10 ng/mL of IL-13 to analyze the effects of TRPM2 on the ox-CaMKⅡ. A CaMKⅡ inhibitor KN-93 was used to confirm the effects of TRPM2 on levels of ox-CaMKⅡ, p-MEK and p-ERK in the IL-13-treated BEAS-2B cells. Wild-type (WT) mice and TRPM2-knockout (TRPM2-/-) mice were induced by ovalbumin (OVA) to compare the differences of inflammation, levels of ox-CaMKII, p-MEK and p-ERK in airways.

Results

Cell viability was clearly decreased by the 20 ng/mL of IL-13. The levels of TRPM2 and ox-CaMKII protein in cells were increased with increasing doses of IL-13. Transfection of TRPM2 siRNA or TRPM2-short cDNA respectively decreased or increased the levels of ox-CaMKⅡ in the IL-13-stimulated cells. The results of KN-93 treatment were similar to the results of TRPM2 siRNA transfection, that the levels of ox-CaMKⅡ, p-MEK and p-ERK were significantly decreased in the IL-13-treated cells. Compared with the OVA-induced WT mice, levels of inflammation, ox-CaMKⅡ, p-MEK and p-ERK in the airways were significantly weakened in the OVA-induced TRPM2-/- mice.

Conclusions

TRPM2 plays a vital role in regulating ox-CaMKⅡ in airway epithelial cells during allergic asthma.

Particulate matter (PM10) induces in vitro activation of human neutrophils, and lung histopathological alterations in a mouse model

The epidemiological association between exposure to particulate matter (PM₁₀) and various respiratory and cardiovascular problems is well known, but the mechanisms driving these effects remain unclear. Neutrophils play an essential role in immune defense against foreign agents and also participate in the development of inflammatory responses. However, the role of these cells in the PM₁₀ induced inflammatory response is not yet fully established. Thus, this study aims to evaluate the effect of PM₁₀ on the neutrophil-mediated inflammatory response. For this, neutrophils from healthy adult human donors were in vitro exposed to different concentrations of PM₁₀. The cell viability and cytotoxic activity were evaluated by MTT. LDH, propidium iodide and reactive oxygen species (ROS) were quantified by flow cytometry. Interleukin 8 (IL-8) expression, peptidyl arginine deiminase 4 (PAD₄), myeloperoxidase (MPO), and neutrophil elastase (NE) expression were measured by RT-PCR. IL-8 was also quantified by ELISA. Fluorescence microscopy was used to evaluate neutrophil extracellular traps (NETs) release. The in vivo inflammatory responses were assessed in BALB/c mice exposed to PM₁₀ by histopathology and RT-PCR. The analysis shows that PM₁₀ exposure induced a cytotoxic effect on neutrophils, evidenced by necrosis and LDH release at high PM₁₀ concentrations. ROS production, IL-8, MPO, NE expression, and NETs release were increased at all PM₁₀ concentrations assessed. Neutrophil infiltration in bronchoalveolar lavage fluid (BALF), histopathological changes with inflammatory cell infiltration, and CXCL1 expression were observed in PM₁₀-treated mice. The results suggest that lung inflammation in response to PM₁₀ could be mediated by neutrophils activation. In this case, these cells migrate to the lungs and release pro-inflamatory mediators, including ROS, IL-8, and NETs. Thus, contributing to the exacerbation of respiratory pathologies, such as allergies, infectious and obstructive diseases.

Cellular metabolic basis of altered immunity in the lungs of patients with COVID-19

Metabolic pathways drive cellular behavior. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes lung tissue damage directly by targeting cells or indirectly by producing inflammatory cytokines. However, whether functional alterations are related to metabolic changes in lung cells after SARS-CoV-2 infection remains unknown. Here, we analyzed the lung single-nucleus RNA-sequencing (snRNA-seq) data of several deceased COVID-19 patients and focused on changes in transcripts associated with cellular metabolism. We observed upregulated glycolysis and oxidative phosphorylation in alveolar type 2 progenitor cells, which may block alveolar epithelial differentiation and surfactant secretion. Elevated inositol phosphate metabolism in airway progenitor cells may promote neutrophil infiltration and damage the lung barrier. Further, multiple metabolic alterations in the airway goblet cells are associated with impaired muco-ciliary clearance. Increased glycolysis, oxidative phosphorylation, and inositol phosphate metabolism not only enhance macrophage activation but also contribute to SARS-CoV-2 induced lung injury. The cytotoxicity of natural killer cells and CD8⁺ T cells may be enhanced by glycerolipid and inositol phosphate metabolism. Glycolytic activation in fibroblasts is related to myofibroblast differentiation and fibrogenesis. Glycolysis, oxidative phosphorylation, and glutathione metabolism may also boost the aging, apoptosis and proliferation of vascular smooth muscle cells, resulting in pulmonary arterial hypertension. In conclusion, this preliminary study revealed a possible cellular metabolic basis for the altered innate immunity, adaptive immunity, and niche cell function in the lung after SARS-CoV-2 infection. Therefore, patients with COVID-19 may benefit from therapeutic strategies targeting cellular metabolism in future.

Downregulation of calcium-regulated heat stable protein 1 expression by low-temperature stimulation causes reduction of interferon-β expression and sensitivity to influenza viral infection

Influenza is prevalent in temperate countries during winter when the environment is dry and cold; however, in tropical and subtropical countries, it is prevalent during the hot, humid rainy season. Thus, temperature and humidity conditions affect influenza outbreaks in different climates. Although the reason for this may be related to host conditions and the conditions under which the virus can survive, it is difficult to analyze changes in host viral responses owing to environmental changes at the cellular level. In the current study, to find candidate genes related with temperature, we analyzed the effects of low-temperature stimulation on influenza virus infection using immortalized respiratory cell lines with the same genetic background established in our laboratory. Although two cell lines with different immune response strengths exhibited enhancement of influenza virus replication following low-temperature stimulation, the mechanisms and degrees were different. In cell lines that showed greater changes, promotion of viral replication was found to involve genes related to temperature, including TRPM2 and CARHSP1. In particular, CARHSP1 expression was decreased by low-temperature stimulation in several respiratory cell lines. In knockdown experiments, because reduction of interferon-β production and sensitivity were observed, the decline may create an environment in which the initial infection cannot be controlled. This procedure may be effective for identifying candidate genes related to the host/viral responses to changes in temperature, and these results can help elucidate the relationships of temperature, humidity, and host responses with viral infection.

Biological effect of PM10 on airway epithelium-focus on obstructive lung diseases

Recently, a continuous increase in environmental pollution has been observed. Despite wide-scale efforts to reduce air pollutant emissions, the problem is still relevant. Exposure to elevated levels of airborne particles increased the incidence of respiratory diseases. PM₁₀ constitute the largest fraction of air pollutants, containing particles with a diameter of less than 10 μm, metals, pollens, mineral dust and remnant material from anthropogenic activity. The natural airway defensive mechanisms against inhaled material, such as mucus layer, ciliary clearance and macrophage phagocytic activity, may be insufficient for proper respiratory function. The epithelium layer can be disrupted by ongoing oxidative stress and inflammatory processes induced by exposure to large amounts of inhaled particles as well as promote the development and exacerbation of obstructive lung diseases. This review draws attention to the current state of knowledge about the physical features of PM₁₀ and its impact on airway epithelial cells, and obstructive pulmonary diseases.

Similarities between the effect of SARS-CoV-2 and HCV on the cellular level, and the possible role of ion channels in COVID19 progression: a review of potential targets for diagnosis and treatment

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted an urgent need to identify effective medicines for the prevention and treatment of the disease. A comparative analysis between SARS-CoV-2 and Hepatitis C Virus (HCV) can expand the available knowledge regarding the virology and potential drug targets against these viruses. Interestingly, comparing HCV with SARS-CoV-2 reveals major similarities between them, ranging from the ion channels that are utilized, to the symptoms that are exhibited by patients. Via this comparative analysis, and from what is known about HCV, the most promising treatments for COVID-19 can focus on the reduction of viral load, treatment of pulmonary system damages, and reduction of inflammation. In particular, the drugs that show most potential in this regard include ritonavir, a combination of peg-IFN, and lumacaftor-ivacaftor. This review anaylses SARS-CoV-2 from the perspective of the role of ion homeostasis and channels in viral pathomechanism. We also highlight other novel treatment approaches that can be used for both treatment and prevention of COVID-19. The relevance of this review is to offer high-quality evidence that can be used as the basis for the identification of potential solutions to the COVID-19 pandemic.

Silica nanoparticles induce lung inflammation in mice via ROS/PARP/TRPM2 signaling-mediated lysosome impairment and autophagy dysfunction

Background

Wide applications of nanoparticles (NPs) have raised increasing concerns about safety to humans. Oxidative stress and inflammation are extensively investigated as mechanisms for NPs-induced toxicity. Autophagy and lysosomal dysfunction are emerging molecular mechanisms. Inhalation is one of the main pathways of exposing humans to NPs, which has been reported to induce severe pulmonary inflammation. However, the underlying mechanisms and, more specifically, the interplays of above-mentioned mechanisms in NPs-induced pulmonary inflammation are still largely obscure. Considered that NPs exposure in modern society is often unavoidable, it is highly desirable to develop effective strategies that could help to prevent nanomaterials-induced pulmonary inflammation.

Results

Pulmonary inflammation induced by intratracheal instillation of silica nanoparticles (SiNPs) in C57BL/6 mice was prevented by PJ34, a poly (ADP-ribose) polymerase (PARP) inhibitor. In human lung bronchial epithelial (BEAS-2B) cells, exposure to SiNPs reduced cell viability, and induced ROS generation, impairment in lysosome function and autophagic flux. Inhibition of ROS generation, PARP and TRPM2 channel suppressed SiNPs-induced lysosome impairment and autophagy dysfunction and consequent inflammatory responses. Consistently, SiNPs-induced pulmonary inflammation was prevented in TRPM2 deficient mice.

Conclusion

The ROS/PARP/TRPM2 signaling is critical in SiNPs-induced pulmonary inflammation, providing novel mechanistic insights into NPs-induced lung injury. Our study identifies TRPM2 channel as a new target for the development of preventive and therapeutic strategies to mitigate nanomaterials-induced lung inflammation.

Graphical abstract