Reducing Cholesterol Level in Live Macrophages Improves Delivery Performance by Enhancing Blood Shear Stress Adaptation.

In recent years, live-cell-based drug delivery systems have gained considerable attention. However, shear stress, which accompanies blood flow, may cause cell death and weaken the delivery performance. In this study, we found that reducing cholesterol in macrophage plasma membranes enhanced their tumor targeting ability by more than 2-fold. Our study demonstrates that the reduced cholesterol level deactivated the mammalian target of rapamycin (mTOR) and consequently promoted the nuclear translocation of transcription factor EB (TFEB), which in turn enhanced the expression of superoxide dismutase (SOD) to reduce reactive oxygen species (ROS) induced by shear stress. A proof-of-concept system using low cholesterol macrophages attached to MXene (e.g., l-RX) was fabricated. In a melanoma mouse model, l-RX and laser irradiation treatments eliminated tumors with no recurrences observed in mice. Therefore, cholesterol reduction is a simple and effective way to enhance the targeting performance of macrophage-based drug delivery systems.

Benzo[b]fluoranthene induced oxidative stress and apoptosis in human airway epithelial cells via mitochondrial disruption.

Benzo[b]fluoranthene (BbF) is a common constituent of polycyclic aromatic hydrocarbons (PAHs). While numerous studies revealed adverse effects of PAHs on human health, the health effects of individual PAHs differ, and few investigations were performed on BbF. Therefore, the present study established cytotoxicity models of human lung epithelial cells (BEAS-2B cells) and bronchial epithelial cells (16HBE cells) exposed to BbF (10, 20, and 40 µM) for 24 h to reveal the mechanisms. Results from cytotoxicity and proliferation studies demonstrated that BbF inhibited cell growth in a dose-dependent manner. Flow cytometric analysis showed that BbF induced the appearance of a sub G1 peak, S-phased arrest, and apoptosis in both cells. Mechanistic investigations illustrated that BbF promoted reactive oxygen species (ROS) production, altered the expression of oxidative stress indicators, and decreased mitochondrial membrane potential. BbF also interfered with the expression of regulators associated with mitochondria disruption pathway. Taken together, these results strongly suggested that BbF inhibited cell growth and induced apoptosis in human airway epithelial cells via ROS-mediated mitochondria disruption.

Human antigen R affects the migration and invasion of human lung cancer A549 cells via regulating E-cadherin suppressor Snail.

Recent studies demonstrated that the progression and metastasis of lung cancer were associated with human antigen R (HuR), a post-transcriptional RNA-binding protein that stabilize and regulate the expression of many tumor-related genes. Although HuR was shown to affect the expressions of epithelial cadherin (E-cadherin), a tumor migration suppressor, in airway epithelial cells, esophageal squamous and colon cancer cells, direct evaluation for the effect and mechanism of HuR on the migration and invasion of lung cancer cells is not documented. In this study, HuR was knocked down via RNA interference and overexpressed using recombinant plasmid in adenocarcinomic human alveolar basal epithelial A549 cells. No apparent inhibition of cell viability was observed. HuR knocked down significantly suppressed A549 migration and invasion in scratch wound healing and transwell assays, with an increase in E-cadherin expression, while the overexpression of HuR notably facilitated A549 migration and invasion, with a decrease in E-cadherin level. In addition, immunoprecipitation study showed that HuR directly interacted with Snail, a repressor of E-cadherin, and upregulated the expression of Snail in A549 cells. These combined results suggested that the effect of HuR on A549 migration and invasion was realized by stabilizing and increasing the expression of Snail, which in-turn interfered with the expression of E-cadherin. The finding of this study revealed direct evidence that HuR affected the migration and invasion of lung cancer cells via regulating E-cadherin and Snail, providing an additional reference and mechanistic clue for further researches and therapeutic strategies in treating lung cancer.

Targeting progranulin alleviated silica particles-induced pulmonary inflammation and fibrosis via decreasing Il-6 and Tgf-ß1/Smad.

Long term exposure to silica particles leads to various diseases, among which silicosis is of great concern. Silicosis is an interstitial lung disease caused by inhalation of silica particles in production environments. However, the mechanisms underlying silicosis remains unclear. Our previous studies revealed that progranulin (Pgrn) promoted the expression of pro-inflammatory factors in alveolar macrophages treated with silica particles and the secretion of extracellular matrix of pulmonary fibroblasts. Nevertheless, the role of Pgrn in silica particles-induced silicosis in vivo was unknown. This study found that silica particles increased Pgrn expression in silicosis patients. Pgrn deficiency reduced lung inflammation and fibrosis in silica particles-induced silicosis mouse models. Subsequently, based on transcriptional sequencing and interleukin (Il) -6 knockout mouse models, results demonstrated that Pgrn deficiency might decrease silicosis inflammation by reducing the production of Il-6, thereby modulating pulmonary fibrosis in the early stage of silicosis mouse models. Furthermore, another mechanism through which Pgrn deficiency reduced fibrosis in silicosis mouse models was the regulation of the transforming growth factor (Tgf) -ß1/Smad signaling pathway. Conclusively, Pgrn contributed to silicosis inflammation and fibrosis induced by silica particles, indicating that Pgrn could be a promising therapeutic target.

Benzo[b]fluoranthene (B[b]F) affects apoptosis, oxidative stress, mitochondrial membrane potential and expressions of blood-brain barrier markers in microvascular endothelial cells.

Exposure to polycyclic aromatic hydrocarbons (PAHs) contributes to the damage of blood-brain barrier. While a number of studies were focused on benzo[a]pyrene, direct effects and mechanisms of benzo[b]fluoranthene (B[b]F), another main component of PAHs, on blood-brain barrier (BBB) are not documented. Here, we investigated if B[b]F at concentrations of environmental relevance could affect apoptosis, oxidative stress, mitochondrial membrane potential (MMP) and BBB marker expression in mouse brain microvascular endothelial (bEnd.3) cells, an in vitro model typically used to study BBB toxicology. Cells were treated with varying concentrations of B[b]F (0, 10, 20 and 40 µM) for 48 h. Cell proliferation, cell cycle, apoptosis, oxidative stress, MMP and BBB marker expressions were evaluated by label-free real-time cell analysis, flow cytometry, immunofluorescence and Western-blot. The proliferation of bEnd.3 cells was inhibited by B[b]F in a concentration dependent manner. B[b]F treatment significantly affected cell cycle, induced apoptosis, increased levels of reactive oxygen species (ROS) and disputed MMP. Expressions of BBB marker Occludin and Claudin-5 were decreased in the presence of 40 µM B[b]F. In conclusion, B[b]F might damage BBB by affecting proliferation, apoptosis, ROS level and Occludin and Claudin-5 expressions in microvascular endothelial cells.

Cholesterol removal improves performance of a model biomimetic system to co-deliver a photothermal agent and a STING agonist for cancer immunotherapy.

Biological membranes often play important functional roles in biomimetic drug delivery systems. We discover that the circulation time and targeting capability of biological membrane coated nanovehicles can be significantly improved by reducing cholesterol level in the coating membrane. A proof-of-concept system using cholesterol-reduced and PD-1-overexpressed T cell membrane to deliver a photothermal agent and a STING agonist is thus fabricated. Comparing with normal membrane, this engineered membrane increases tumor accumulation by ~2-fold. In a melanoma model in male mice, tumors are eliminated with no recurrence in >80% mice after intravenous injection and laser irradiation; while in a colon cancer model in male mice, ~40% mice are cured without laser irradiation. Data suggest that the engineered membranes escape immune surveillance to avoid blood clearance while keeping functional surface molecules exposed. In summary, we develop a simple, effective, safe and widely-applicable biological membrane modification strategy. This "subtractive" strategy displays some advantages and is worth further development.

Alveolar macrophage-derived progranulin mediated pro-inflammatory Il-6 expression via regulating Creb1 in silicosis model.

Progranulin (PGRN) is a secreted factor involved in inflammatory diseases. However, the function of PGRN in silica-induced lung inflammation has not been elucidated. In this study, we demonstrated that PGRN in serum and lung tissues was markedly increased in silicosis mouse model. And immunohistochemistry results showed that PGRN was mainly expressed in alveolar macrophages, which was further confirmed in silica-treated alvelar macrophages cell line (MH-S) in vitro. PGRN promoted pro-inflammatory cytokines transcription such as interleukin (Il)-6, tumor necrosis factor-α (Tnf-α) and Il-1ß in MH-S cells, and the increasing of Il-6 was most obvious. Knockdown of PGRN blocked the silica-induced elevation of intracellular Il-6 in MH-S cells. Furthermore, we also found that PGRN could increase the phosphorylation of Cyclic AMP-responsive element-binding protein 1 (Creb1), a transcriptional regulator of Il-6. Inhibition of p-Creb1 by the phosphorylation inhibitor of Creb1 (666-15) decreased PGRN-induced intracellular Il-6 production in MH-S cells. In conclusion, PGRN was highly increased in silicosis mouse model and upregulated inflammatory cytokines expression. These findings suggested that PGRN might be a key mediator in silica-induced inflammation and provided a new clue for the diagnosis and drug therapy of silicosis.

Nicotinamide Mononucleotide Ameliorates Silica-Induced Lung Injury through the Nrf2-Regulated Glutathione Metabolism Pathway in Mice.

Nicotinamide mononucleotide (NMN) is a natural antioxidant approved as a nutritional supplement and food ingredient, but its protective role in silicosis characterized by oxidative damage remains unknown. In this study, we generated a silicosis model by intratracheal instillation of silica, and then performed histopathological, biochemical, and transcriptomic analysis to evaluate the role of NMN in silicosis. We found that NMN mitigated lung damage at 7 and 28 days, manifested as a decreasing coefficient of lung weight and histological changes, and alleviated oxidative damage by reducing levels of reactive oxygen species and increasing glutathione. Meanwhile, NMN treatment also reduced the recruitment of inflammatory cells and inflammatory infiltration in lung tissue. Transcriptomic analysis showed that NMN treatment mainly regulated immune response and glutathione metabolism pathways. Additionally, NMN upregulated the expression of antioxidant genes Gstm1, Gstm2, and Mgst1 by promoting the expression and nuclear translocation of nuclear factor-erythroid 2 related factor 2 (Nrf2). Gene interaction analysis showed that Nrf2 interacted with Gstm1 and Mgst1 through Gtsm2. Promisingly, oxidative damage mediated by these genes occurred mainly in fibroblasts. In summary, NMN alleviates silica-induced oxidative stress and lung injury by regulating the endogenous glutathione metabolism pathways. This study reveals that NMN supplementation might be a promising strategy for mitigating oxidative stress and inflammation in silicosis.