Surfactin from Bacillus subtilis attenuates ambient air particulate matter-promoted human oral cancer cells metastatic potential

The health effects of poor air quality

ABSTRACT

Smoke, particularly from wildfires and other combustion sources, is a significant contributor to air pollution, comprising a complex mixture of particulate matter and gaseous pollutants. Prolonged exposure to smoke can exacerbate respiratory diseases, such as asthma and chronic obstructive pulmonary disease, leading to increased ED visits and hospitalizations. This article examines the significant health risks associated with air pollution, particularly chronic diseases and acute respiratory conditions, and discusses the emergency treatment of acute respiratory distress from exposure.

Air pollution exposure and head and neck cancer incidence

To investigate air pollution's effect in the form of PM2.5 (particulate matter measuring less than 2.5 microns) on head and neck aerodigestive cancer incidence, an epidemiological cohort analysis was performed using data from the Surveillance Epidemiology and End Results national cancer database from the years 2002-2012. The relationship between US county mean PM2.5 levels and head and neck cancer (HNC) incidence rates were examined using a linear mixed model. Lagged effect of the pollutant's effect on HNC incidence was analyzed. Our results showed a significant association between the incidence of HNC and certain subtypes with PM2.5 exposure after controlling for demographic characteristics, smoking and alcohol use. We observed the highest association at a 5-year lag period (β = 0.24, p value < 0.001). We observed significant associations at no lag (β = 0.16, p value = 0.02) and up to a 20-year lag period (β = 0.15, p value < 0.001). PM2.5 exposure is associated with an increased incidence of HNC, with the strongest association at a 5-year lag period. To better understand the relationships between exposure and cancer pathogenesis, further subgroup analysis is needed.

Glucocorticoids alleviate particulate matter-induced COX-2 expression and mitochondrial dysfunction through the Bcl-2/GR complex in A549 cells

Exposure to particulate matter (PM) causes mitochondrial dysfunction and lung inflammation. The cyclooxygenase-2 (COX-2) pathway is important for inflammation and mitochondrial function. However, the mechanisms by which glucocorticoid receptors (GRs) suppress COX-2 expression during PM exposure have not been elucidated yet. Hence, we examined the mechanisms underlying the dexamethasone-mediated suppression of the PM-induced COX-2/prostaglandin E2 (PGE2) pathway in A549 cells. The PM-induced increase in COX-2 protein, mRNA, and promoter activity was suppressed by glucocorticoids; this effect of glucocorticoids was antagonized by the GR antagonist RU486. COX-2 induction was correlated with the ability of PM to increase reactive oxygen species (ROS) levels. Consistent with this, antioxidant treatment significantly abolished COX-2 induction, suggesting that ROS is involved in PM-mediated COX-2 induction. We also observed a low mitochondrial membrane potential in PM-treated A549 cells, which was reversed by dexamethasone. Moreover, glucocorticoids significantly enhanced Bcl-2/GR complex formation in PM-treated A549 cells. Glucocorticoids regulate the PM-exposed induction of COX-2 expression and mitochondrial dysfunction and increase the interaction between GR and Bcl-2. These findings suggest that the COX-2/PGE2 pathway and the interaction between GR and Bcl-2 are potential key therapeutic targets for the suppression of inflammation under PM exposure.

Human microbiomes in cancer development and therapy

Colonies formed by bacteria, archaea, fungi, and viral groups and their genomes, metabolites, and expressed proteins constitute complex human microbiomes. An increasing evidences showed that carcinogenesis and disease progression were link to microbiomes. Different organ sources, their microbial species, and their metabolites are different; the mechanisms of carcinogenic or procancerous are also different. Here, we summarize how microbiomes contribute to carcinogenesis and disease progression in cancers of the skin, mouth, esophagus, lung, gastrointestinal, genital, blood, and lymph malignancy. We also insight into the molecular mechanisms of triggering, promoting, or inhibiting carcinogenesis and disease progress induced by microbiomes or/and their secretions of bioactive metabolites. And then, the strategies of application of microorganisms in cancer treatment were discussed in detail. However, the mechanisms by which human microbiomes function are still poorly understood. The bidirectional interactions between microbiotas and endocrine systems need to be clarified. Probiotics and prebiotics are believed to benefit human health via a variety of mechanisms, in particular, in tumor inhibition. It is largely unknown how microbial agents cause cancer or how cancer progresses. We expect this review may open new perspectives on possible therapeutic approaches of patients with cancer.

Particulate matter 2.5 exposure induces epithelial-mesenchymal transition via PI3K/AKT/mTOR pathway in human retinal pigment epithelial ARPE-19 cells

Exposure to particulate matter 2.5 (PM2.5) has been linked to ocular surface diseases, yet knowledge of the molecular mechanism impacted on retina pathogenesis is limited. Therefore, the purpose of this study was to explore the effects and involved factors of PM2.5 exposure in human retinal pigment epithelial APRE-19 cells. Our data revealed a decreased cell viability and an increased migratory ability in APRE-19 cells after PM2.5 stimulation. The MMP-2 and MMP-9 protein levels were markedly increased while the MMPs regulators TIMP-1 and TIMP-2 were significantly reduced in PM2.5-exposed APRE-19 cells. PM2.5 also increased pro-MMP-2 expression in the cell culture supernatants. Additionally, PM2.5 promoted the EMT markers through the activation of PI3K/AKT/mTOR pathway. Moreover, the ICAM-1 production was also remarkably increased by PM2.5 but reduced by PI3K/AKT inhibitor LY294002 in APRE-19 cells. Taken together, these results suggest that PM2.5 promotes EMT in a PI3K/AKT/mTOR-dependent manner in the retinal pigment epithelium.

Itraconazole for Topical Treatment of Skin Carcinogenesis: Efficacy Enhancement by Lipid Nanocapsule Formulations

Itraconazole (ITC), an antifungal drug with anticancer activity, shows potential for oral treatment of skin cancer. There is clinical need for topical ITC for treating low-risk skin carcinogenesis. Our objective was to develop ITC nanoformulations with enhanced anticancer efficacy. Lipid nanocapsules (LNC), either unmodified (ITC/LNC) or modified with the amphiphiles miltefosine (ITC/MF-LNC) or the lipopeptide biosurfactant surfactin (ITC/SF-LNC) as bioactive additives were developed. LNC formulations showed high ITC entrapment efficiency (>98%), small diameter (42-45 nm) and sustained ITC release. Cytotoxicity studies using malignant SCC 9 cells and normal human fibroblasts (NHF) demonstrated significant enhancement of ITC anticancer activity and selectivity for cancer cells by the LNC formulations and a synergistic ITC-amphiphile interaction improving the combination performance. Treatment of intradermal tumor-bearing mice with the ITC nanoformulation gels compared with ITC and 5-FU gels achieved significant tumor growth inhibition that was remarkably enhanced by ITC/MF-LNC and ITC/SF-LNC as well as recovery of skin architecture. Molecularly, tumoral expression of Ki-67 and cytokeratin proliferative proteins was significantly suppressed by LNC formulations, the suppressive effect on cytokeratins was superior to that of 5-FU. These findings provide new evidence for effective topical treatment of low-risk skin carcinogenesis utilizing multiple approaches that involve drug repurposing, nanotechnology, and bioactive amphiphiles as formulation enhancing additives.

Surfactin reduces particulate matter-induced VCAM-1-dependent monocyte adhesion in human gingival fibroblasts by increasing Nrf2-dependent HO-1 expression

BACKGROUND AND OBJECTIVES

The mechanisms of particulate matter (PM) toxicity involve the generation of ROS and upregulation of proinflammatory molecules. Nrf2 is a multifunctional cytoprotective transcription factor that regulates the expression of various antioxidant, anti-inflammatory, and detoxifying molecules, such as HO-1. As surfactin has potential to induce Nrf2 activation and HO-1 expression, this study aimed to investigate the anti-inflammatory effects of surfactin on PM-exposed human gingival fibroblasts (HGFs) and signaling pathways engaged by surfactin.

MATERIALS AND METHODS

Human gingival fibroblasts were challenged by PM with or without surfactin pretreatment. The expression of Nrf2, HO-1, VCAM-1, and other molecules was determined by western blot, real-time PCR, or ELISA. Human monocytic THP-1 cells labeled with fluorescent reagent were added to HGFs, and the cell adhesion was assessed. ROS generation and NADPH oxidase activity were also measured. The involvement of Nrf2/HO-1 and ROS signaling pathways was investigated by treating HGFs with specific pathway interventions, genetically or pharmacologically. One dose of surfactin was given to mice before PM treatment to explore its in vivo effect on VCAM-1 expression in gingival tissues.

RESULTS

Particulate matter led to VCAM-1-dependent monocyte adhesion in HGFs, which was regulated by PKCα/NADPH oxidase/ROS/STAT1/IL-6 pathway. Surfactin could attenuate monocyte adhesion by disrupting this VCAM-1-dependent pathway. Additionally, surfactin promoted Nrf2-dependent HO-1 expression in HGFs, mitigating VCAM-1 expression. PM-treated mice exhibited the lower expression of IL-6 and VCAM-1 in gingival tissues if they previously received surfactin.

CONCLUSION

Surfactin exerts anti-inflammatory effects against PM-induced inflammatory responses in HGFs by inhibiting VCAM-1-dependent pathway and inducing Nrf2/HO-1 axis.

Surfactin attenuates particulate matter-induced COX-2-dependent PGE2 production in human gingival fibroblasts by inhibiting TLR2 and TLR4/MyD88/NADPH oxidase/ROS/PI3K/Akt/NF-κB signaling pathway

OBJECTIVE

To evaluate the anti-inflammatory effects of surfactin and underlying mechanisms against particulate matter (PM)-induced inflammatory responses in human gingival fibroblasts (HGFs).

BACKGROUND

PM, a major air pollutant, may associate with certain oral diseases possibly by inducing inflammation and oxidative stress. Surfactin, a potent biosurfactant, possesses various biological properties including anti-inflammatory activity. However, the underlying mechanisms are unclear. Also, there is no study investigating the effects of surfactin on PM-induced oral inflammatory responses. As an essential constituent of human periodontal connective tissues which involves immune-inflammatory responses, HGFs serve as useful study models.

METHODS

HGFs were pretreated with surfactin prior to PM incubation. The PGE₂ production was determined by ELISA, while the protein expression and mRNA levels of COX-2 and upstream regulators were measured using Western blot and real-time PCR, respectively. The transcriptional activity of COX-2 and NF-κB were determined using promoter assay. ROS generation and NADPH oxidase activity were identified by specific assays. Co-immunoprecipitation assay, pharmacologic inhibitors, and siRNA transfection were applied to explore the interplay of molecules. Mice were given one dose of surfactin or different pharmacologic inhibitors, then PM was delivered into the gingiva for three consecutive days. Gingival tissues were obtained for analyzing COX-2 expression.

RESULTS

PM-treated HGFs released significantly higher COX-2-dependent PGE₂ , which were regulated by TLR2 and TLR4/MyD88/NADPH oxidase/ROS/PI3K/Akt/NF-κB pathway. PM-induced COX-2/PGE₂ increase was effectively reversed by surfactin through the disruption of regulatory pathway. Similar inhibitory effects of surfactin was observed in mice.

CONCLUSION

Surfactin may elicit anti-inflammatory effects against PM-induced oral inflammatory responses.

Suppressive Effects of Rosmarinic Acid Rich Fraction from Perilla on Oxidative Stress, Inflammation and Metastasis Ability in A549 Cells Exposed to PM via C-Jun, P-65-Nf-Κb and Akt Signaling Pathways

Particulate matter from forest fires (PMFF) is an environmental pollutant causing oxidative stress, inflammation, and cancer cell metastasis due to the presence of polycyclic aromatic hydrocarbons (PAHs). Perilla seed meal contains high levels of polyphenols, including rosmarinic acid (RA). The aim of this study is to determine the anti-oxidative stress, anti-inflammation, and anti-metastasis actions of rosmarinic acid rich fraction (RA-RF) from perilla seed meal and its underlying molecular mechanisms in A549 cells exposed to PMFF. PMFF samples were collected via the air sampler at the University of Phayao, Thailand, and their PAH content were analyzed using GC-MS. Fifteen PAH compounds were detected in PMFF. The PMFF significantly induced intracellular reactive oxygen species (ROS) production, the mRNA expression of pro-inflammatory cytokines, MMP-9 activity, invasion, migration, the overexpression of c-Jun and p-65-NF-κB, and Akt phosphorylation. Additionally, the RA-RF significantly reduced ROS production, IL-6, IL-8, TNF-α, and COX-2. RA-RF could also suppress MMP-9 activity, migration, invasion, and the phosphorylation activity of c-Jun, p-65-NF-κB, and Akt. Our findings revealed that RA-RF has antioxidant, anti-inflammatory, and anti-metastasis properties via c-Jun, p-65-NF-κB, and Akt signaling pathways. RA-RF may be further developed as an inhalation agent for the prevention of lung inflammation and cancer metastasis induced by PM exposure.

Carbon Monoxide-Releasing Molecule-2 Ameliorates Particulate Matter-Induced Aorta Inflammation via Toll-Like Receptor/NADPH Oxidase/ROS/NF-κB/IL-6 Inhibition

Particulate matter (PM), a major air pollutant, may be associated with adverse cardiovascular effects. Reactive oxygen species- (ROS-) dependent proinflammatory cytokine production, such as interleukin-6 (IL-6), is a possible underlying mechanism. Carbon monoxide- (CO-) releasing molecule-2 (CORM-2) which liberates exogenous CO can exert many beneficial effects, particularly anti-inflammation and antioxidant effects. The purpose of this study was to explore the protective effects and underpinning mechanisms of CORM-2 on PM-induced aorta inflammation. Here, human aortic vascular smooth muscle cells (HASMCs) were utilized as in vitro models for the assessment of signaling pathways behind CORM-2 activities against PM-induced inflammatory responses, including Toll-like receptors (TLRs), NADPH oxidase, ROS, nuclear factor-kappa B (NF-κB), and IL-6. The modulation of monocyte adherence and HASMC migration, that are two critical cellular events of inflammatory process, along with their regulators, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and matrix metalloproteinase-2 (MMP-2) and MMP-9, in response to PM by CORM-2, were further evaluated. Finally, mice experiments under different conditions were conducted for the in vivo evaluation of CORM-2 benefits on the expression of inflammatory molecules including IL-6, ICAM-1, VCAM-1, MMP-2, and MMP-9. Our results found that PM could induce aorta inflammation in vitro and in vivo, as evidenced by the increase of IL-6 expression that was regulated by the TLR2 and TLR4/NADPH oxidase/ROS/NF-κB signaling pathway, thereby promoting ICAM-1- and VCAM-1-dependent monocyte adhesion and MMP-2- and MMP-9-dependent HASMC migration. Importantly, our experimental models demonstrated that CORM-2-liberated CO effectively inhibited the whole identified PM-induced inflammatory cascade in HASMCs and tissues. In conclusion, CORM-2 treatment may elicit multiple beneficial effects on inflammatory responses of aorta due to PM exposure, thereby providing therapeutic value in the context of inflammatory diseases of the cardiovascular system.