Carbon black nanoparticles induce pulmonary fibrosis through NLRP3 inflammasome pathway modulated by miR-96 targeted FOXO3a

Role of NLRP3 inflammasome in nanoparticle adjuvant-mediated immune response

The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is pivotal in orchestrating the immune response induced by nanoparticle adjuvants. Understanding the intricate mechanisms underlying the activation of NLRP3 inflammasome by these adjuvants is crucial for deciphering their immunomodulatory properties. This review explores the involvement of the NLRP3 inflammasome in mediating immune responses triggered by nanoparticle adjuvants. It delves into the signaling pathways and cellular mechanisms involved in NLRP3 activation, highlighting its significance in modulating the efficacy and safety of nanoparticle-based adjuvants. A comprehensive grasp of the interplay between NLRP3 inflammasome and nanoparticle adjuvants holds promise for optimizing vaccine design and advancing immunotherapeutic strategies.

Epithelium-derived exosomes promote silica nanoparticles-induced pulmonary fibroblast activation and collagen deposition via modulating fibrotic signaling pathways and their epigenetic regulations

BACKGROUND

In the context of increasing exposure to silica nanoparticles (SiNPs) and ensuing respiratory health risks, emerging evidence has suggested that SiNPs can cause a series of pathological lung injuries, including fibrotic lesions. However, the underlying mediators in the lung fibrogenesis caused by SiNPs have not yet been elucidated.

RESULTS

The in vivo investigation verified that long-term inhalation exposure to SiNPs induced fibroblast activation and collagen deposition in the rat lungs. In vitro, the uptake of exosomes derived from SiNPs-stimulated lung epithelial cells (BEAS-2B) by fibroblasts (MRC-5) enhanced its proliferation, adhesion, and activation. In particular, the mechanistic investigation revealed SiNPs stimulated an increase of epithelium-secreted exosomal miR-494-3p and thereby disrupted the TGF-β/BMPR2/Smad pathway in fibroblasts via targeting bone morphogenetic protein receptor 2 (BMPR2), ultimately resulting in fibroblast activation and collagen deposition. Conversely, the inhibitor of exosomes, GW4869, can abolish the induction of upregulated miR-494-3p and fibroblast activation in MRC-5 cells by the SiNPs-treated supernatants of BEAS-2B. Besides, inhibiting miR-494-3p or overexpression of BMPR2 could ameliorate fibroblast activation by interfering with the TGF-β/BMPR2/Smad pathway.

CONCLUSIONS

Our data suggested pulmonary epithelium-derived exosomes serve an essential role in fibroblast activation and collagen deposition in the lungs upon SiNPs stimuli, in particular, attributing to exosomal miR-494-3p targeting BMPR2 to modulate TGF-β/BMPR2/Smad pathway. Hence, strategies targeting exosomes could be a new avenue in developing therapeutics against lung injury elicited by SiNPs.

The interactions of subcellular organelles in pulmonary fibrosis induced by carbon black nanoparticles: a comprehensive review

Owing to the widespread use and improper emissions of carbon black nanoparticles (CBNPs), the adverse effects of CBNPs on human health have attracted much attention. In toxicological research, carbon black is frequently utilized as a negative control because of its low toxicity and poor solubility. However, recent studies have indicated that inhalation exposure to CBNPs could be a risk factor for severe and prolonged pulmonary inflammation and fibrosis. At present, the pathogenesis of pulmonary fibrosis induced by CBNPs is still not fully elucidated, but it is known that with small particle size and large surface area, CBNPs are more easily ingested by cells, leading to organelle damage and abnormal interactions between organelles. Damaged organelle and abnormal organelles interactions lead to cell structure and function disorders, which is one of the important factors in the development and occurrence of various diseases, including pulmonary fibrosis. This review offers a comprehensive analysis of organelle structure, function, and interaction mechanisms, while also summarizing the research advancements in organelles and organelle interactions in CBNPs-induced pulmonary fibrosis.

Fermented lily bulbs by "Jiangshui" probiotics improves lung health in mice

Limited application in protecting lung health is attributed to the low levels of active compounds in lily plant bulbs. This study focused on enhancing the active compounds by fermenting Lilium davidii (Lanzhou Lily) bulbs with Limosilactobacillus fermentum GR-3, isolated from Jiangshui. Lily fermented bulbs with strain GR-3 (LFB+GR-3) increased the bioavailability of hexadecanoic acid methyl ester, 22-tetrahydroxy-5alpha-cholestan-6-one-3-O-beta-d-allopyranoside, 22-O-(6-deoxy-Alpha-l-mannopyranosyl)-3-O-beta-d-glucopyranosyl-pregn-5-en-20-one, 1-O-trans-feruloylglycerol, and 3,4 dihydroxybenzoic acid. LFB+GR-3 fraction was employed to treat the mice model exposed to the carbon black nanoparticles (CBNPs). Immunohistochemical analysis revealed that the deposition of CBNPs and damages in lung tissues were limited in the LFB+GR-3 treatment group, while TNF-α, IL-10, and IL-6 were elevated by 6.9, 4.3, and 7 folds in the CBNP exposure group. In addition, Lactobacillus, Escherichia, Lactococcus, and Muribacter were dominant in the lung microbiota of LFB+GR-3 than the CBNP group. The use of probiotic fermented lily bulbs might be helpful in lung infection treatment.

Updates on the role of epigenetics in familial mediterranean fever (FMF)

Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disease caused by mutations in the MEFV (MEditerranean FeVer) gene that affects people originating from the Mediterranean Sea. The high variability in severity and clinical manifestations observed not only between ethnic groups but also between and within families is mainly related to MEFV allelic heterogeneity and to some modifying genes. In addition to the genetic factors underlying FMF, the environment plays a significant role in the development and manifestation of this disease through various epigenetic mechanisms, including DNA methylation, histone modification, and noncoding RNAs. Indeed, epigenetic events have been identified as an important pathophysiological determinant of FMF and co-factors shaping the clinical picture and outcome of the disease. Therefore, it is essential to better understand the contribution of epigenetic factors to autoinflammatory diseases, namely, FMF, to improve disease prognosis and potentially develop effective targeted therapies. In this review, we highlight the latest updates on the role of epigenetics in FMF.

Linking NLRP3 inflammasome and pulmonary fibrosis: mechanistic insights and promising therapeutic avenues

Pulmonary fibrosis is a devastating disorder distinguished by redundant inflammation and matrix accumulation in the lung interstitium. The early inflammatory cascade coupled with recurring tissue injury orchestrates a set of events marked by perturbed matrix hemostasis, deposition of matrix proteins, and remodeling in lung tissue. Numerous investigations have corroborated a direct correlation between the NLR family pyrin domain-containing 3 (NLRP3) activation and the development of pulmonary fibrosis. Dysregulated activation of NLRP3 within the pulmonary microenvironment exacerbates inflammation and may incite fibrogenic responses. Nevertheless, the precise mechanisms through which the NLRP3 inflammasome elicits pro-fibrogenic responses remain inadequately defined. Contemporary findings suggest that the pro-fibrotic consequences stemming from NLRP3 signaling primarily hinge on the action of interleukin-1β (IL-1β). IL-1β instigates IL-1 receptor signaling, potentiating the activity of transforming growth factor-beta (TGF-β). This signaling cascade, in turn, exerts influence over various transcription factors, including SNAIL, TWIST, and zinc finger E-box-binding homeobox 1 (ZEB 1/2), which collectively foster myofibroblast activation and consequent lung fibrosis. Here, we have connected the dots to illustrate how the NLRP3 inflammasome orchestrates a multitude of signaling events, including the activation of transcription factors that facilitate myofibroblast activation and subsequent lung remodeling. In addition, we have highlighted the prominent role played by various cells in the formation of myofibroblasts, the primary culprit in lung fibrosis. We also provided a concise overview of various compounds that hold the potential to impede NLRP3 inflammasome signaling, thus offering a promising avenue for the treatment of pulmonary fibrosis.

Daphnetin ameliorates PM2.5-induced airway inflammation by inhibiting NLRP3 inflammasome-mediated pyroptosis in CS-exposed mice

Epidemiologic studies have shown that fine particulate matter 2.5 (PM2.5) exaggerates airway inflammation associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Daphnetin (Daph) is a natural compound with a variety of biological activities. At present, there are limited data on whether Daph can protect against cigarette smoke (CS)-induced chronic obstructive pulmonary disease (COPD) and PM2.5-CS-induced AECOPD. Therefore, this study systematically evaluated the effects of Daph on CS-induced COPD and PM2.5-CS-induced AECOPD and determined its mechanism of action. First, in vitro studies showed that PM2.5 exacerbated cytotoxicity and NLRP3 inflammasome-mediated pyroptosis induced by low-dose cigarette smoke extracts (CSE). However, the effect was reversed by si-NLRP3 and MCC950. Similar results were obtained in PM2.5-CS-induced AECOPD mice. The results of the mechanistic studies suggested that blocking NLRP3 abolished PM2.5 combined with cigarette induced cytotoxicity, lung damage, NLRP3 inflammasome activation and pyroptosis in vitro and in vivo. Second, Daph suppressed the expression of NLRP3 inflammasome and pyroptosis in BEAS-2B cells. Third, Daph significantly protected against CS-induced COPD and PM2.5-CS-induced AECOPD by inhibiting the NLRP3 inflammasome and pyroptosis in mice. Our findings identified the NLRP3 inflammasome as a critical contributor to PM2.5-CS-induced airway inflammation, and Daph as a negative regulator of NLRP3-mediated pyroptosis, which has implications for the pathophysiology of AECOPD.

Impact of air pollution on cardiovascular aging

The world population is aging rapidly, and by some estimates, the number of people older than 60 will double in the next 30 years. With the increase in life expectancy, adverse effects of environmental exposures start playing a more prominent role in human health. Air pollution is now widely considered the most detrimental of all environmental risk factors, with some studies estimating that almost 20% of all deaths globally could be attributed to poor air quality. Cardiovascular diseases are the leading cause of death worldwide and will continue to account for the most significant percentage of non-communicable disease burden. Cardiovascular aging with defined pathomechanisms is a major trigger of cardiovascular disease in old age. Effects of environmental risk factors on cardiovascular aging should be considered in order to increase the health span and reduce the burden of cardiovascular disease in older populations. In this review, we explore the effects of air pollution on cardiovascular aging, from the molecular mechanisms to cardiovascular manifestations of aging and, finally, the age-related cardiovascular outcomes. We also explore the distinction between the effects of air pollution on healthy aging and disease progression. Future efforts should focus on extending the health span rather than the lifespan.

Recent advances in nanoparticle applications in respiratory disorders: a review

Various nanoparticles are used in the discovery of new nanomedicine to overcome the shortages of conventional drugs. Therefore, this article presents a comprehensive and up-to-date review of the effects of nanoparticle-based drugs in the treatment of respiratory disorders, including both basic and clinical studies. Databases, including PubMed, Web of Knowledge, and Scopus, were searched until the end of August 2022 regarding the effect of nanoparticles on respiratory diseases. As a new tool, nanomedicine offered promising applications for the treatment of pulmonary diseases. The basic composition and intrinsic characteristics of nanomaterials showed their effectiveness in treating pulmonary diseases. The efficiency of different nanomedicines has been demonstrated in experimental animal models of asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), lung cancer, lung infection, and other lung disorders, confirming their function in the improvement of respiratory disorders. Various types of nanomaterials, such as carbon nanotubes, dendrimers, polymeric nanomaterials, liposomes, quantum dots, and metal and metal oxide nanoparticles, have demonstrated therapeutic effects on respiratory disorders, which may lead to new possible remedies for various respiratory illnesses that could increase drug efficacy and decrease side effects.

Identification of a Gene Signature Predicting (Nano)Particle-Induced Adverse Lung Outcome in Rats

Nanoparticles are extensively used in industrial products or as food additives. However, despite their contribution to improving our quality of life, concerns have been raised regarding their potential impact on occupational and public health. To speed up research assessing nanoparticle-related hazards, this study was undertaken to identify early markers of harmful effects on the lungs. Female Sprague Dawley rats were either exposed to crystalline silica DQ-12 with instillation, or to titanium dioxide P25, carbon black Printex-90, or multi-walled carbon nanotube Mitsui-7 with nose-only inhalation. Tissues were collected at three post-exposure time points to assess short- and long-term effects. All particles induced lung inflammation. Histopathological and biochemical analyses revealed phospholipid accumulation, lipoproteinosis, and interstitial thickening with collagen deposition after exposure to DQ-12. Exposure to the highest dose of Printex-90 and Mitsui-7, but not P25, induced some phospholipid accumulation. Comparable histopathological changes were observed following exposure to P25, Printex-90, and Mitsui-7. Comparison of overall gene expression profiles identified 15 potential early markers of adverse lung outcomes induced by spherical particles. With Mitsui-7, a distinct gene expression signature was observed, suggesting that carbon nanotubes trigger different toxicity mechanisms to spherical particles.

Mechanistic insights into severe pulmonary inflammation caused by silica stimulation: The role of macrophage pyroptosis

Respirable silica dust is a common hazard faced by occupational workers and prolonged exposure to this dust can lead to pulmonary inflammation, fibrosis and, in severe cases, silicosis. However, the underlying mechanism by which silica exposure causes these physical disorders is not yet understood. In this study, we aimed to shed light on this mechanism by establishing in vitro and in vivo silica exposure models from the perspective of macrophages. Our results showed that compared to the control group, silica exposure resulted in an upregulation of the pulmonary expression of P2X7 and Pannexin-1, but this effect was suppressed by treatment with MCC950, a specific inhibitor of NLRP3. Our in vitro studies showed that silica exposure induced mitochondrial depolarization in macrophages, which led to a reduction of intracellular ATP and an influx of Ca²⁺. Furthermore, we found that creating an extracellular high potassium environment by adding KCl to the macrophage medium inhibited the expression of pyroptotic biomarkers and pro-inflammatory cytokines such as NLRP3 and IL-1β. Treatment with BBG, a P2X7 antagonist, also effectively inhibited the expression of P2X7, NLRP3, and IL-1β. On the other hand, treatment with FCF, a Pannexin-1 inhibitor, suppressed the expression of Pannexin-1 but had no effect on the expression of pyroptotic biomarkers such as P2X7, NLRP3, and IL-1β. In conclusion, our findings suggest that silica exposure triggers the opening of P2X7 ion channels, resulting in intracellular K⁺ efflux, extracellular Ca²⁺ influx, and the assembly of the NLRP3 inflammasome, ultimately leading to macrophage pyroptosis and pulmonary inflammation.

Unique regulatory roles of ncRNAs changed by PM2.5 in human diseases

PM_2.5 is a type of particulate matter with an aerodynamic diameter smaller than 2.5 µm, and exposure to PM_2.5 can adversely damage human health. PM_2.5 may impair health through oxidative stress, inflammatory reactions, immune function alterations and chromosome or DNA damage. Through increasing in-depth studies, researchers have found that noncoding RNAs (ncRNAs), particularly microRNAs (miRNAs), circular RNAs (circRNAs) as well as long noncoding RNAs (lncRNAs), might play significant roles in PM_2.5-related human diseases via some of the abovementioned mechanisms. Therefore, in this review, we mainly discuss the regulatory function of ncRNAs altered by PM_2.5 in human diseases and summarize the potential molecular mechanisms. The findings reveal that these ncRNAs might induce or promote diseases via inflammation, the oxidative stress response, cell autophagy, apoptosis, cell junction damage, altered cell proliferation, malignant cell transformation, disruption of synaptic function and abnormalities in the differentiation and status of immune cells. Moreover, according to a bioinformatics analysis, the altered expression of potential genes caused by these ncRNAs might be related to the development of some human diseases. Furthermore, some ncRNAs, including lncRNAs, miRNAs and circRNAs, or processes in which they are involved may be used as biomarkers for relevant diseases and potential targets to prevent these diseases. Additionally, we performed a meta-analysis to identify more promising diagnostic ncRNAs as biomarkers for related diseases.

Comparing species-different responses in pulmonary fibrosis research: Current understanding of in vitro lung cell models and nanomaterials

Pulmonary fibrosis (PF) is a chronic, irreversible lung disease that is typically fatal and characterized by an abnormal fibrotic response. As a result, vast areas of the lungs are gradually affected, and gas exchange is impaired, making it one of the world's leading causes of death. This can be attributed to a lack of understanding of the onset and progression of the disease, as well as a poor understanding of the mechanism of adverse responses to various factors, such as exposure to allergens, nanomaterials, environmental pollutants, etc. So far, the most frequently used preclinical evaluation paradigm for PF is still animal testing. Nonetheless, there is an urgent need to understand the factors that induce PF and find novel therapeutic targets for PF in humans. In this regard, robust and realistic in vitro fibrosis models are required to understand the mechanism of adverse responses. Over the years, several in vitro and ex vivo models have been developed with the goal of mimicking the biological barriers of the lung as closely as possible. This review summarizes recent progress towards the development of experimental models suitable for predicting fibrotic responses, with an emphasis on cell culture methods, nanomaterials, and a comparison of results from studies using cells from various species.

NAT10 accelerates pulmonary fibrosis through N4-acetylated TGFB1-initiated epithelial-to-mesenchymal transition upon ambient fine particulate matter exposure

Exposure to ambient fine particulate matter (PM_2.5) has been linked to a higher pulmonary fibrosis risk. Dysregulation of the epitranscriptome results in abnormal expression of mRNAs during fibrosis development. N4-acetylcytidine (ac4C) is one of the most frequent RNA epigenetic alterations, however, its function in PM_2.5-triggered fibrosis is yet unknown. In this study, lung epithelial and murine models were established and exposed to PM_2.5 to analyze the function of ac4C alteration in pulmonary fibrosis and underlying mechanisms. Meanwhile, the expression levels of only known ac4C "writer" protein, N-acetyltransferase 10 (NAT10), were significantly induced in pulmonary epithelia, relative to the control. Subsequently, NAT10 enhanced the stability of transforming growth factor beta 1 (TGFB1) mRNA as well as protein levels. As an up-stream driver, TGFB1 accelerated EMT and fibrosis process. Inhibition of NAT10 significantly protected against pulmonary EMT and fibrosis driven by PM_2.5 exposure, whereas TGFB1 overexpression reversed the protective effects of NAT10 inhibition. Thus, NAT10 accelerated PM_2.5-triggered pulmonary fibrosis via increasing TGFB1 mRNA stability in an ac4C-dependent manner. Our results reveal a pivotal role of NAT10-regulated mRNA ac4C acetylation in PM_2.5-triggered pulmonary fibrosis and uncover the potential epitranscriptional mechanism.

miR-155-5p/FOXO3a promotes pulmonary fibrosis in rats by mediating NLRP3 inflammasome activation

OBJECTIVE

Pulmonary fibrosis (PF) is regarded as progressive lung disease. miR-155-5p depletion exerts anti-fibrotic effects in silicotic mice. This study explored the effect and possible mechanism of miR-155-5p in PF rats, hoping to find a new target for PF management.

METHODS

Bleomycin-induced PF rat model was established. Alveolar structure and collagen fiber deposition were observed by HE and Elastica-Masson staining. Alveolitis and PF scores were evaluated using the method of Szapiel. Total collagen content was detected using the Sircol method. PF rats were intraperitoneally injected with NLRP3 inhibitor MCC950 or intravenously injected with miR-155-5p antagomir and si-FOXO3a lentivirus plasmids. Binding sites of miR-155-5p and FOXO3a were predicted using bioinformatics analysis and dual-luciferase reporter assay. The expressions of miR-155-5p, NLRP3, ASC, caspase-1, IL-1β, IL-18, and FOXO3a were detected by RT-qPCR, Western blot, and ELISA.

RESULTS

MCC950 treatment inhibited NLRP3 inflammasome, alleviated alveolar hemorrhage and alveolitis, and reduced blue collagen fiber deposition, scores of alveolitis and PF, and levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in PF rats. miR-155-5p was elevated in lung tissues of PF rats. Inhibition of miR-155-5p downregulated levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in lung tissues of PF rats. miR-155-5p targeted FOXO3a. miR-155-5p inhibition and silencing FOXO3a exacerbated alveolitis and PF in rats and increased levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18.

CONCLUSIONS

miR-155-5p aggravated alveolitis and promoted PF by targeting FOXO3a and prompting the activation of NLRP3 inflammasome and then inducing IL-1β and IL-18 release.

Role of mitochondrial stress and the NLRP3 inflammasome in lung diseases

BACKGROUND

As an organelle essential for intracellular energy supply, mitochondria are involved in intracellular metabolism and inflammation, and cell death. The interaction of mitochondria with the NLRP3 inflammasome in the development of lung diseases has been extensively studied. However, the exact mechanism by which mitochondria mediate the activation of the NLRP3 inflammasome and trigger lung disease is still unclear.

METHODS

The literatures related to mitochondrial stress, NLRP3 inflammasome and lung diseases were searched in PubMed.

RESULTS

This review aims to provide new insights into the recently discovered mitochondrial regulation of the NLRP3 inflammasome in lung diseases. It also describes the crucial roles of mitochondrial autophagy, long noncoding RNA, micro RNA, altered mitochondrial membrane potential, cell membrane receptors, and ion channels in mitochondrial stress and regulation of the NLRP3 inflammasome, in addition to the reduction of mitochondrial stress by nuclear factor erythroid 2-related factor 2 (Nrf2). The effective components of potential drugs for the treatment of lung diseases under this mechanism are also summarized.

CONCLUSION

This review provides a resource for the discovery of new therapeutic mechanisms and suggests ideas for the development of new therapeutic drugs, thus promoting the rapid treatment of lung diseases.

The culprits of superoxide dismutase inactivation under size-dependent stress of ultrafine carbon black: Superoxide anion, genotoxicity and protein corona

As a critical component of atmospheric ultrafine particulates, ultrafine carbon black (UFCB) brings great exposure risk to organisms. At present, the action pathway and activity regulation mechanism of UFCB on functional proteins in vivo are not clear, and the size-dependent effects of UFCB during this process need to be elucidated. Superoxide dismutase (SOD), one of the most applied biomarkers to assess the environmental impact of pollutants, plays crucial roles in resistance to oxidative stress. Here, based on the inactivation of SOD (84.79 %, 86.81 % and 91.70 %) in primary mouse hepatocytes exposed to UFCB (13 nm, 50 nm and 95 nm), oxidative stress, genotoxicity and protein molecular studies were employed to elucidate the inactivation mechanisms. Results showed that inhibition of UFCB-mediated superoxide anion (O₂^-) contributed to a decrease in SOD activity. Furthermore, the significant increase in 8-hydroxy-2-deoxyguanosine content and the comet tail formation indicated the occurrence of DNA damage, supporting that concomitant aberrant transcriptional and protein translational under gene regulation should be responsible for SOD inactivation. At the molecular level, the constricted backbone, reduced content of α-helix and fluorescence sensitization all demonstrated that the attachment-type binding of SOD on UFCB to form the 'protein corona' disrupted protein structure. Enzyme activity assays indicated that SOD backbone tightening and helix decay resulted in decreased activity, which should be another reason for intracellular SOD inactivation. More importantly, the particle sizes of UFCB exert powerful influences on SOD inactivation mechanisms. Smaller UFCB (13 nm) induced more severe O₂^- inhibition and DNA damage, while UFCB_50nm with the best dispersity bound more SOD and induced stronger molecular toxicity, which are their different strengths in stressing SOD inactivation in hepatocytes. Our findings provide novel insights for exploring functional proteins activity and underscore a potentially size-dependent risk of nanoparticles.

On the Need for Human Studies of PM Exposure Activation of the NLRP3 Inflammasome

Particulate matter air pollution is associated with blood inflammatory biomarkers, however, the biological pathways from exposure to periferal inflammation are not well understood. We propose that the NLRP3 inflammasome is likely stimulated by ambient particulate matter, as it is by some other particles and call for more research into this pathway.

Potential targeted therapy based on deep insight into the relationship between the pulmonary microbiota and immune regulation in lung fibrosis

Pulmonary fibrosis is an irreversible disease, and its mechanism is unclear. The lung is a vital organ connecting the respiratory tract and the outside world. The changes in lung microbiota affect the progress of lung fibrosis. The latest research showed that lung microbiota differs in healthy people, including idiopathic pulmonary fibrosis (IPF) and acute exacerbation-idiopathic pulmonary fibrosis (AE-IPF). How to regulate the lung microbiota and whether the potential regulatory mechanism can become a necessary targeted treatment of IPF are unclear. Some studies showed that immune response and lung microbiota balance and maintain lung homeostasis. However, unbalanced lung homeostasis stimulates the immune response. The subsequent biological effects are closely related to lung fibrosis. Core fucosylation (CF), a significant protein functional modification, affects the lung microbiota. CF regulates immune protein modifications by regulating key inflammatory factors and signaling pathways generated after immune response. The treatment of immune regulation, such as antibiotic treatment, vitamin D supplementation, and exosome micro-RNAs, has achieved an initial effect in clearing the inflammatory storm induced by an immune response. Based on the above, the highlight of this review is clarifying the relationship between pulmonary microbiota and immune regulation and identifying the correlation between the two, the impact on pulmonary fibrosis, and potential therapeutic targets.

The Effects and Pathogenesis of PM2.5 and Its Components on Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a heterogeneous disease, is the leading cause of death worldwide. In recent years, air pollution, especially particulate matter (PM), has been widely studied as a contributing factor to COPD. As an essential component of PM, PM2.5 is associated with COPD prevalence, morbidity, and acute exacerbations. However, the specific pathogenic mechanisms were still unclear and deserve further research. The diversity and complexity of PM2.5 components make it challenging to get its accurate effects and mechanisms for COPD. It has been determined that the most toxic PM2.5 components are metals, polycyclic aromatic hydrocarbons (PAHs), carbonaceous particles (CPs), and other organic compounds. PM2.5-induced cytokine release and oxidative stress are the main mechanisms reported leading to COPD. Nonnegligibly, the microorganism in PM 2.5 may directly cause mononuclear inflammation or break the microorganism balance contributing to the development and exacerbation of COPD. This review focuses on the pathophysiology and consequences of PM2.5 and its components on COPD.

Diverse Pathways of Engineered Nanoparticle-Induced NLRP3 Inflammasome Activation

With the rapid development of engineered nanomaterials (ENMs) in biomedical applications, their biocompatibility and cytotoxicity need to be evaluated properly. Recently, it has been demonstrated that inflammasome activation may be a vital contributing factor for the development of biological responses induced by ENMs. Among the inflammasome family, NLRP3 inflammasome has received the most attention because it directly interacts with ENMs to cause the inflammatory effects. However, the pathways that link ENMs to NLRP3 inflammasome have not been thoroughly summarized. Thus, we reviewed recent findings on the role of major ENMs properties in modulating NLRP3 inflammasome activation, both in vitro and in vivo, to provide a better understanding of the underlying mechanisms. In addition, the interactions between ENMs and NLRP3 inflammasome activation are summarized, which may advance our understanding of safer designs of nanomaterials and ENM-induced adverse health effects.

Assessment of primary and inflammation-driven genotoxicity of carbon black nanoparticles in vitro and in vivo

Carbon black nanoparticles (CBNPs) have a large surface area/volume ratio and are known to generate oxidative stress and inflammation that may result in genotoxicity and cancer. Here, we evaluated the primary and inflammatory response-driven (i.e. secondary) genotoxicity of two CBNPs, Flammruss101 (FL101) and PrintexXE2B (XE2B) that differ in size and specific surface area (SSA), and cause different amounts of reactive oxygen species. Three doses (low, medium and high) of FL101 and XE2B were assessed in vitro in the lung epithelial (A549) and activated THP-1 (THP-1a) monocytic cells exposed in submerged conditions for 6 and 24 h, and in C57BL/6 mice at day 1, 28 and 90 following intratracheal instillation. In vitro, we assessed pro-inflammatory response as IL-8 and IL-1β gene expression, and in vivo, inflammation was determined as inflammatory cell infiltrates in bronchial lavage (BAL) fluid and as histological changes in lung tissue. DNA damage was quantified in vitro and in vivo as DNA strand breaks levels by the alkaline comet assay. Inflammatory responses in vitro and in vivo correlated with dosed CBNPs SSA. Both materials induced DNA damage in THP-1a (correlated with dosed mass), and only XE2B in A549 cells. Non-statistically significant increase in DNA damage in vivo was observed in BAL cells. In conclusion, this study shows dosed SSA predicted inflammation both in vivo and in vitro, whereas dosed mass predicted genotoxicity in vitro in THP-1a cells. The observed lack of correlation between CBNP surface area and genotoxicity provides little evidence of inflammation-driven genotoxicity in vivo and in vitro.

Ubiquitination as a key regulatory mechanism for O3-induced cutaneous redox inflammasome activation

NLRP1 is one of the major inflammasomes modulating the cutaneous inflammatory responses and therefore linked to a variety of cutaneous conditions. Although NLRP1 has been the first inflammasome to be discovered, only in the past years a significant progress was achieved in understanding the molecular mechanism and the stimuli behind its activation. In the past decades a crescent number of studies have highlighted the role of air pollutants as Particulate Matter (PM), Cigarette Smoke (CS) and Ozone (O₃) as trigger stimuli for inflammasomes activation, especially via Reactive Oxygen Species (ROS) mediators. However, whether NLRP1 can be modulated by air pollutants via oxidative stress and the mechanism behind its activation is still poorly understood. Here we report for the first time that O₃, one of the most toxic pollutants, activates the NLRP1 inflammasome in human keratinocytes via oxidative stress mediators as hydrogen peroxide (H₂O₂) and 4-hydroxy-nonenal (4HNE). Our data suggest that NLRP1 represents a target protein for 4HNE adduction that possibly leads to its proteasomal degradation and activation via the possible involvement of E3 ubiquitin ligase UBR2. Of note, Catalase (Cat) treatment prevented inflammasome assemble and inflammatory cytokines release as well as NLRP1 ubiquitination in human keratinocytes upon O₃ exposure. The present work is a mechanistic study that follows our previous work where we have showed the ability of O₃ to induce cutaneous inflammasome activation in humans exposed to this pollutant. In conclusion, our results suggest that O₃ triggers the cutaneous NLRP1 inflammasome activation by ubiquitination and redox mechanism.

Negative Feedback of the cAMP/PKA Pathway Regulates the Effects of Endoplasmic Reticulum Stress-Induced NLRP3 Inflammasome Activation on Type II Alveolar Epithelial Cell Pyroptosis as a Novel Mechanism of BLM-Induced Pulmonary Fibrosis

Endoplasmic reticulum stress (ER stress) contributes to the development of pulmonary fibrosis, especially in type II alveolar epithelial cells (AECs) apoptosis. ER stress also promotes NLRP3 inflammasome activation which is inhibited by upregulation of cAMP/PKA pathway. However, it is confused whether ER stress-induced NLRP3 inflammasome activation and pyroptosis in type II alveolar epithelial cells which exacerbates pulmonary fibrosis via a mechanism that is suppressed by cAMP/PKA pathway. In our research, we explored that potential links among NLRP3 inflammasome, ER stress, and cAMP/PKA pathway in type II AECs to explain the new mechanisms of pulmonary fibrosis. We found that in vivo, ER stress, NLRP3 inflammasome, and PKA upregulated in the alveolar epithelial area in animal models of pulmonary fibrosis. In addition, immunofluorescence staining further confirmed that ER stress, NLRP3 inflammasome, and cAMP/PKA had potential links on type II AECs in BLM group. In vitro, ER stress stimulated NLRP3 inflammasome activation, promoted pyroptosis, and also upregulated cAMP/PKA pathway. Upregulation of cAMP/PKA pathway inhibited ER stress-induced pyroptosis of A549 cells and vice versa. These results initially supported conclusion that ER stress may stimulate NLRP3 inflammasome activation and pyroptosis in type II AECs, which exacerbated pulmonary fibrosis, and cAMP/PKA pathway may act as a feedback regulator.

Carbon nanostructures: a comprehensive review of potential applications and toxic effects

There is no doubt that nanotechnology has revolutionized our life since the 1970s when it was first introduced. Nanomaterials have helped us to improve the current products and services we use. Among the different types of nanomaterials, the application of carbon-based nanomaterials in every aspect of our lives has rapidly grown over recent decades. This review discusses recent advances of those applications in distinct categories, including medical, industrial, and environmental applications. The first main section introduces nanomaterials, especially carbon-based nanomaterials. In the first section, we discussed medical applications, including medical biosensors, drug and gene delivery, cell and tissue labeling and imaging, tissue engineering, and the fight against bacterial and fungal infections. The next section discusses industrial applications, including agriculture, plastic, electronic, energy, and food industries. In addition, the environmental applications, including detection of air and water pollutions and removal of environmental pollutants, were vastly reviewed in the last section. In the conclusion section, we discussed challenges and future perspectives.

Maternal Ethanol Exposure-Induced Cardiac Fibrosis is Associated with Changes in TGF-β and SIRT1/FOXO3a Signaling in Male Rat Offspring: A Three-Month Follow-up Study

Ethanol exposure during pregnancy induces cardiac fibrosis in the fetal heart. However, the mechanisms by which consumption of ethanol induces fibrotic changes are not known. Pregnant rats were received ethanol 4.5 g/kg BW once per day from the 7th day of pregnancy (GD7) throughout lactation. Our findings demonstrated that, area of fibrosis increased in cardiac tissue in the pups on both postnatal day twenty one (PN21) and postnatal day ninety (PN90) after prenatal and early postnatal period ethanol treatment compared with the controls. It was accompanied by a decline in the expression of SIRT1 protein along with the elevation of FOXO3a and TGF-β protein expressions which were determined by western blot. Overall, our data reveal that prenatal alcohol usage increase in fibrotic regions in the pup hearts possibly by regulating TGF-β, FOXO3a and SIRT1 protein levels. These are potential therapeutic molecular targets that can be modulated to protect heart against maternal ethanol exposure.

Genetic instability of lung induced by carbon black nanoparticles is related with Plk1 signals changes

As a possible carcinogen, carbon black has threatened public health. However, the evidences are insufficient and the mechanism of carcinogenesis is still not specified. Thirty rats were randomly divided into 3 groups, namely 0, 5 and 30 mg/m3 Carbon Black nanoparticles (CBNPs) groups, respectively. Rats were treated with CBNPs by nose-only inhalation for 28 days, 6 h/day. The human bronchial epithelial (16HBE) cells were treated with 0, 50, 100 and 200 μg/mL CBNPs for 24 h. Polo-like kinase 1 (PLK1) overexpression cell line was established by pcDNA3.1-PLK1 stable transfection. Our results showed that CBNPs exposure could induce DNA damage and genetic changes as well as apoptosis in vivo and in vitro. The DNA repair ability increased after CBNPs exposure. Cell cycle process was retarded at the G2/M phases in 16HBE cells after CBNPs treatment. The PLK1, ChK2 GADD45α and XRCC1 expression levels changed in rat lung and 16HBE cells after CBNPs treatment. Compared with NC 16HBE cells, DNA damage and repair, numbers of apoptotic cells and micronucleus (MN) rates, as well as the ChK2, GADD45α, XRCC1 expression levels decreased, whereas cytokinesis block proliferation index (CBPI) and replicative index (RI) increase in PLK overexpression (PLK+/+) cells after CBNPs treatment. This study highlighted that PLK1 related with the genetic toxicity of CBNPs in vitro and in vivo. Our results provided evidences supporting reclassification of carbon black as a human possible carcinogen.

Current and prospective applications of exosomal microRNAs in pulmonary fibrosis (Review)

Pulmonary fibrosis (PF) is a chronic, progressive, irreversible and life‑threatening lung disease. However, the pathogenesis and molecular mechanisms of this condition remain unclear. Extracellular vesicles (EVs) are structures derived from the plasma membrane, with a diameter ranging from 30 nm to 5 µm, that play an important role in cell‑to‑cell communications in lung disease, particularly between epithelial cells and the pulmonary microenvironment. In particular, exosomes are a type of EV that can deliver cargo molecules, including endogenous proteins, lipids and nucleic acids, such as microRNAs (miRNAs/miRs). These cargo molecules are encapsulated in lipid bilayers through target cell internalization, receptor‑ligand interactions or lipid membrane fusion. miRNAs are single‑stranded RNA molecules that regulate cell differentiation, proliferation and apoptosis by degrading target mRNAs or inhibiting translation to modulate gene expression. The aim of the present review was to discuss the current knowledge available on exosome biogenesis, composition and isolation methods. The role of miRNAs in the pathogenesis of PF was also reviewed. In addition, emerging diagnostic and therapeutic properties of exosomes and exosomal miRNAs in PF were described, in order to highlight the potential applications of exosomal miRNAs in PF.

MicroRNAs: Potential mediators between particulate matter 2.5 and Th17/Treg immune disorder in primary membranous nephropathy

Primary membranous nephropathy (PMN), is an autoimmune glomerular disease and the main reason of nephrotic syndrome in adults. Studies have confirmed that the incidence of PMN increases yearly and is related to fine air pollutants particulate matter 2.5 (PM2.5) exposure. These imply that PM2.5 may be associated with exposure to PMN-specific autoantigens, such as the M-type receptor for secretory phospholipase A2 (PLA2R1). Emerging evidence indicates that Th17/Treg turns to imbalance under PM2.5 exposure, but the molecular mechanism of this process in PMN has not been elucidated. As an important indicator of immune activity in multiple diseases, Th17/Treg immune balance is sensitive to antigens and cellular microenvironment changes. These immune pathways play an essential role in the disease progression of PMN. Also, microRNAs (miRNAs) are susceptible to external environmental stimulation and play link role between the environment and immunity. The contribution of PM2.5 to PMN may induce Th17/Treg imbalance through miRNAs and then produce epigenetic affection. We summarize the pathways by which PM2.5 interferes with Th17/Treg immune balance and attempt to explore the intermediary roles of miRNAs, with a particular focus on the changes in PMN. Meanwhile, the mechanism of PM2.5 promoting PLA2R1 exposure is discussed. This review aims to clarify the potential mechanism of PM2.5 on the pathogenesis and progression of PMN and provide new insights for the prevention and treatment of the disease.

Non-Coding RNAs: Master Regulators of Inflammasomes in Inflammatory Diseases

Emerging data indicates that non-coding RNAs (ncRNAs) represent more than just “junk sequences” of the genome and have been found to be involved in multiple diseases by regulating various biological process, including the activation of inflammasomes. As an important aspect of innate immunity, inflammasomes are large immune multiprotein complexes that tightly regulate the production of pro-inflammatory cytokines and mediate pyroptosis; the activation of the inflammasomes is a vital biological process in inflammatory diseases. Recent studies have emphasized the function of ncRNAs in the fine control of inflammasomes activation either by directly targeting components of the inflammasomes or by controlling the activity of various factors that control the activation of inflammasomes; consequently, ncRNAs may represent potential therapeutic targets for inflammatory diseases. Understanding the precise role of ncRNAs in controlling the activation of inflammasomes will help us to design targeted therapies for multiple inflammatory diseases. In this review, we summarize the regulatory role and therapeutic potential of ncRNAs in the activation of inflammasomes by focusing on a range of inflammatory diseases, including microbial infection, sterile inflammatory diseases, and fibrosis-related diseases. Our goal is to provide new ideas and perspectives for future research.

Nanoparticle-Based Drug Delivery System: The Magic Bullet for the Treatment of Chronic Pulmonary Diseases

Chronic pulmonary diseases encompass different persistent and lethal diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), cystic fibrosis (CF), asthma, and lung cancers that affect millions of people globally. Traditional pharmacotherapeutic treatment approaches (i.e., bronchodilators, corticosteroids, chemotherapeutics, peptide-based agents, etc.) are not satisfactory to cure or impede diseases. With the advent of nanotechnology, drug delivery to an intended site is still difficult, but the nanoparticle's physicochemical properties can accomplish targeted therapeutic delivery. Based on their surface, size, density, and physical-chemical properties, nanoparticles have demonstrated enhanced pharmacokinetics of actives, achieving the spotlight in the drug delivery research field. In this review, the authors have highlighted different nanoparticle-based therapeutic delivery approaches to treat chronic pulmonary diseases along with the preparation techniques. The authors have remarked the nanosuspension delivery via nebulization and dry powder carrier is further effective in the lung delivery system since the particles released from these systems are innumerable to composite nanoparticles. The authors have also outlined the inhaled particle's toxicity, patented nanoparticle-based pulmonary formulations, and commercial pulmonary drug delivery devices (PDD) in other sections. Recently advanced formulations employing nanoparticles as therapeutic carriers for the efficient treatment of chronic pulmonary diseases are also canvassed.

Knockdown of long noncoding RNA growth arrest-specific transcript 5 regulates forkhead box O3 to inhibit lipopolysaccharide-induced human bronchial epithelial cell pyroptosis

Pyroptosis is a novel proinflammatory programmed cell death process. This study was designed to investigate the functional mechanisms of long noncoding RNA growth arrest-specific transcript 5 (lncRNA GAS5) on lipopolysaccharide (LPS)-induced human bronchial epithelial cell (HBEC) pyroptosis. LPS was used to induce pyroptosis in HBECs, followed by the detection of the expression of GAS5, forkhead box O3 (FOXO3), and nuclear factor E2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling pathway-related factors. Cell viability was evaluated using CCK-8 assay, lactate dehydrogenase (LDH) release was assessed by LDH assay kit and caspase-1 activity by flow cytometry. Furthermore, expression of NOD-like receptor family pyrin domain containing 3 and pyroptosis-related proteins was evaluated using Western blot analysis, while enzyme-linked immunosorbent assay was used to determine the levels of inflammatory factors. The interaction between GAS5 and FOXO3 was confirmed using bioinformatic prediction, RNA immunoprecipitation assay, RNA pull-down, and dual-luciferase reporter gene assay. Treatment of HBECs with LPS upregulated the expression of GAS5 and FOXO3, resulting in the inactivation of the Nrf2/HO-1 signaling pathway. On the other hand, inhibition of both GAS5 and FOXO3 promoted cell viability, reduced LDH release, pyroptosis, and inflammatory response in LPS-induced HBECs. Furthermore, FOXO3 could interact with GAS5, while FOXO3 overexpression reversed the inhibitory effect of GAS5 knockdown on cell pyroptosis. Thus, mechanistically, inhibition of FOXO3 activates the Nrf2/HO-1 pathway to suppress LPS-induced pyroptosis in HBECs. This study revealed that GAS5 knockdown attenuates FOXO3 expression thereby activating the Nrf2/HO-1 pathway to inhibit LPS-induced pyroptosis in HBECs. These findings may contribute to identifying novel targets that inhibit pyroptosis in HBECs.

Long-term carbon black inhalation induced the inflammation and autophagy of cerebellum in rats

Carbon black (CB) has been demonstrated to have adverse effects on the lung tissue. Few studies explored the effects of CB on the cerebellum, widely recognized to contribute to gait and balance coordination and timing in the motor domain. Some studies have reported that inflammatory response and damaged autophagy are important mechanisms of CB toxicity and can be repaired after the recovery. The present study aimed to determine whether long-term CB exposure could induce the inflammation and damaged autophagy of the cerebellum. The rats were randomly divided into four groups. The control group received the filtered air for 90 days; the carbon black (CB) group received CB particles for 90 days; the recovery (R) group received CB for 90 days and recovered for another 14 days; the recovery control (RC) group received filtered air for 104 days. The purpose of the R group was to test whether neuroinflammation and autophagy could be repaired after short-term recovery. The western blot and immunohistochemistry revealed that long-term CB exposure induced augmented level of pro-inflammatory cytokines (Interleukin-1β, IL-1β; Interleukin-6, IL-6; and Tumor Necrosis Factor-α, TNF-α) and anti-inflammatory cytokine (Interleukin-10, IL-10). The autophagic markers (Beclin1 and LC3) were increased in both CB group and R group. These findings clearly demonstrated that long-term CB exposure induced inflammation and autophagy in the cerebellum, which were not obviously improved after short-term recovery.

Exosomal Micro-RNA-96 Derived From Bone Marrow Mesenchymal Stem Cells Inhibits Doxorubicin-Induced Myocardial Toxicity by Inhibiting the Rac1/Nuclear Factor-κB Signaling Pathway

Background

Exosomes are small membranous structures released from cells into the blood, regulating various biological processes. However, the role of exosomes in cardiotoxicity remains largely unclear. This study investigated the functional mechanism of exosomal microRNA‐96 (miR‐96) derived from bone marrow mesenchymal stem cells (BMSCs) in myocardial toxicity induced by doxorubicin.

Methods and Results

BMSCs were transfected with miR‐96 mimic, miR‐96 inhibitor, or the negative control before exosome isolation. The functional mechanism of BMSC‐derived exosomal miR‐96 was investigated in doxorubicin‐induced cell and rat models. The cardiac function, histological morphology, and fiber content of myocardium were examined. The expression levels of the following biomarkers were measured for assessment of cardiac injury: creatine kinase isoenzyme MB, cardiac troponin I, brain natriuretic peptide, soluble suppression of tumorigenesis‐2, tumor necrosis factor‐α, interleukin‐1β, interleukin‐6, superoxide dismutase, glutathione peroxidase, and malondialdehyde. Cell Counting Kit‐8 assay was used to measure the survival rate of cardiomyocytes. The expressions of miR‐96, Rac1, p‐IKKα/IKKα, p‐IKKβ/IKKβ, p‐IκBα/IκBα and p‐p65/p65 in myocardium and cardiomyocytes were also assessed. The targeting relationship between miR‐96 and Rac1 was verified by dual‐luciferase reporter assay. miR‐96 was downregulated, Rac1 was upregulated and the nuclear factor‐κB signaling pathway was activated in doxorubicin‐induced cell and animal models. Doxorubicin decreased antioxidative enzymes (superoxide dismutase and glutathione peroxidase) and increased myocardial injury biomarkers (creatine kinase isoenzyme MB, cardiac troponin I, and brain natriuretic peptide), proinflammatory cytokines (tumor necrosis factor‐α, interleukin‐1β, and interleukin‐6), malondialdehyde, and myocardial fibers. Exosomes derived from BMSCs ameliorated doxorubicin‐induced myocardial injuries. Overexpression of miR‐96 in exosomes derived from BMSCs further enhanced the protection of myocardium and cardiomyocytes against doxorubicin‐induced toxicity while miR‐96 knockdown abolished the protective effects of exosomes derived from BMSCs. Rac1 was a target gene of miR‐96. Rac1 inhibition could downregulate the expression of the nuclear factor‐κB signaling and further reverse the promotion of miR‐96 knockdown on doxorubicin‐induced myocardial toxicity.

Conclusions

BMSC‐derived exosomal miR‐96 protects myocardium against doxorubicin‐induced toxicity by inhibiting the Rac/nuclear factor‐κB signaling pathway.

Role of miRNA and lncRNAs in organ fibrosis and aging

Fibrosis is the endpoint of pathological remodeling. This process contributes to the pathogenesis of several chronic disorders and aging-associated organ damage. Different molecular cascades contribute to this process. TGF-β, WNT, and YAP/TAZ signaling pathways have prominent roles in this process. A number of long non-coding RNAs and microRNAs have been found to regulate organ fibrosis through modulation of the activity of related signaling pathways. miR-144-3p, miR-451, miR-200b, and miR-328 are among microRNAs that participate in the pathology of cardiac fibrosis. Meanwhile, miR-34a, miR-17-5p, miR-122, miR-146a, and miR-350 contribute to liver fibrosis in different situations. PVT1, MALAT1, GAS5, NRON, PFL, MIAT, HULC, ANRIL, and H19 are among long non-coding RNAs that participate in organ fibrosis. We review the impact of long non-coding RNAs and microRNAs in organ fibrosis and aging-related pathologies.

ROCK inhibitor attenuates carbon blacks-induced pulmonary fibrosis in mice via Rho/ROCK/NF-kappa B pathway

Exposure to carbon blacks (CBs) has been associated with the progression of pulmonary fibrosis, whereas the mechanism is still not clear. We therefore aimed to investigate the effect of RhoA/ROCK pathway on pulmonary fibrosis caused by CBs exposure. Western blot analysis indicated that CBs could promote the activation of RhoA/ROCK pathway and phosphorylation of p65 and IκBα in mice lung. However, ROCK inhibitor Y-27632 could attenuate phosphorylation levels of p65 and IκBα and restore histopathological changes of the lung tissue. Then, we evaluated the effect of RhoA/ROCK pathway on pulmonary fibrosis by detecting the expression levels of α-SMA, vimentin, and Collagen type-I (Col-I), which could be partly inhibited by Y-27632. It was assumed that inhibition of ROCK could be a promising therapeutic candidate for CBs-induced pulmonary fibrosis, which possibly through the blockage of RhoA/ROCK/NF-κB pathway.

Sevoflurane alleviates hepatic ischaemia/reperfusion injury by up-regulating miR-96 and down-regulating FOXO4

Hepatic ischaemia/reperfusion (I/R) injury represents an event characterized by anoxic cell death and an inflammatory response, that can limit the treatment efficacy of liver surgery. Ischaemic preconditioning agents such as sevoflurane (Sevo) have been highlighted to play protective roles in hepatic I/R injury. The current study aimed to investigate the molecular mechanism underlying the effects associated with Sevo in hepatic I/R injury. Initially, mouse hepatic I/R injury models were established via occlusion of the hepatic portal vein and subsequent reperfusion. The expression of forkhead box protein O4 (FOXO4) was detected using reverse transcription quantitative polymerase chain reaction and Western blot analysis from clinical liver tissue samples obtained from patients who had previously undergone liver transplantation, mouse I/R models and oxygen-deprived hepatocytes. The morphology of the liver tissues was analysed using haematoxylin-eosin (HE) staining, with apoptosis detected via TUNEL staining. Immunohistochemistry methods were employed to identify the FOXO4-positive cells. Mice with knocked out FOXO4 (FOXO4-KO mice) were subjected to I/R. In this study, we found FOXO4 was highly expressed following hepatic I/R injury. After treatment with Sevo, I/R modelled mice exhibited an alleviated degree of liver injury, fewer apoptotic cells and FOXO4-positive cells. FOXO4 was a target gene of miR-96. Knockdown of FOXO4 could alleviate hepatic I/R injury and decrease cell apoptosis. Taken together, the key observations of our study suggest that Sevo alleviates hepatic I/R injury by means of promoting the expression of miR-96 while inhibiting FOXO4 expression. This study highlights the molecular mechanism mediated by Sevo in hepatic I/R injury.

Inflammasome Activation in Pollution-Induced Skin Conditions

SUMMARY

Exposure to air pollutants has been now associated with detrimental effects on a variety of organs, including the heart, lungs, GI tract, and brain. However, recently it has become clear that pollutant exposure can also promote the development/exacerbation of a variety of skin conditions, including premature aging, psoriasis, acne, and atopic dermatitis. Although the molecular mechanisms by which pollutant exposure results in these cutaneous pathological manifestations, it has been noticed that an inflammatory status is a common denominator of all those skin conditions. For this reason, recently, the activation of a cytosolic multiprotein complex involved in inflammatory responses (the inflammasome) that could promote the maturation of proinflammatory cytokines interleukin-1β and interleukin-18 has been hypothesized to play a key role in pollution-induced skin damage. In this review, we summarize and propose the cutaneous inflammasome as a novel target of pollutant exposure and the eventual usage of inflammasome inhibitor as new technologies to counteract pollution-induced skin damage. Possibly, the ability to inhibit the inflammasome activation could prevent cutaneous inflammaging and ameliorate the health and appearance of the skin.

Perfluoroalkyl substance pollutants activate the innate immune system through the AIM2 inflammasome

Perfluoroalkyl substances (PFAS) are widely used in various manufacturing processes. Accumulation of these chemicals has adverse effects on human health, including inflammation in multiple organs, yet how PFAS are sensed by host cells, and how tissue inflammation eventually incurs, is still unclear. Here, we show that the double-stranded DNA receptor AIM2 is able to recognize perfluorooctane sulfonate (PFOS), a common form of PFAS, to trigger IL-1β secretion and pyroptosis. Mechanistically, PFOS activates the AIM2 inflammasome in a process involving mitochondrial DNA release through the Ca2+-PKC-NF-κB/JNK-BAX/BAK axis. Accordingly, Aim2-/- mice have reduced PFOS-induced inflammation, as well as tissue damage in the lungs, livers, and kidneys in both their basic condition and in an asthmatic exacerbation model. Our results thus suggest a function of AIM2 in PFOS-mediated tissue inflammation, and identify AIM2 as a major pattern recognition receptor in response to the environmental organic pollutants.

Adverse Outcome Pathway Development for Assessment of Lung Carcinogenicity by Nanoparticles

Lung cancer, one of the most common and deadly forms of cancer, is in some cases associated with exposure to certain types of particles. With the rise of nanotechnology, there is concern that some engineered nanoparticles may be among such particles. In the absence of epidemiological evidence, assessment of nanoparticle carcinogenicity is currently performed on a time-consuming case-by-case basis, relying mainly on animal experiments. Non-animal alternatives exist, including a few validated cell-based methods accepted for regulatory risk assessment of nanoparticles. Furthermore, new approach methodologies (NAMs), focused on carcinogenic mechanisms and capable of handling the increasing numbers of nanoparticles, have been developed. However, such alternative methods are mainly applied as weight-of-evidence linked to generally required animal data, since challenges remain regarding interpretation of the results. These challenges may be more easily overcome by the novel Adverse Outcome Pathway (AOP) framework, which provides a basis for validation and uptake of alternative mechanism-focused methods in risk assessment. Here, we propose an AOP for lung cancer induced by nanosized foreign matter, anchored to a selection of 18 standardized methods and NAMs for in silico- and in vitro-based integrated assessment of lung carcinogenicity. The potential for further refinement of the AOP and its components is discussed in relation to available nanosafety knowledge and data. Overall, this perspective provides a basis for development of AOP-aligned alternative methods-based integrated testing strategies for assessment of nanoparticle-induced lung cancer.

PM2.5-induced pulmonary inflammation via activating of the NLRP3/caspase-1 signaling pathway

Particulate matter 2.5 (PM2.5)-induced pulmonary inflammation has become a public concern in recent years. In which, the activation of the NLRP3/caspase-1 pathway was closely related to the inflammatory response of various diseases. However, the promotion effect of the NLRP3/caspase-1 pathway on PM2.5-induced pulmonary inflammation remains largely unclear. Here, our data showed that PM2.5 exposure caused lung injury in the mice by which inflammatory cell infiltration occurred in lung and alveolar structure disorder. Meanwhile, the exposure of human bronchial epithelial cells (16HBE) to PM2.5 resulted in suppressed cell viability, as well as elevated cell apoptosis. Moreover, a higher level of inflammatory cytokine and activation of the NLRP3/caspase-1 pathway in PM2.5-induced inflammation mice models and 16HBE cells. Mechanistically, pretreatment with MCC950, a NLRP3/caspase-1 pathway inhibitor, prevented PM2.5-induced lung injury, inflammatory response, and the number of inflammatory cells in BALFs, as well as promoted cell viability and decreased inflammatory cytokine secretion. Collectively, our findings indicated that the NLRP3/caspase-1 pathway serves a vital role in the pathological changes of pulmonary inflammation caused by PM2.5 exposure. MCC950 was expected to be the therapeutic target of PM2.5 inhalation mediated inflammatory diseases.

NLRP3 inflammasome activation in alveolar epithelial cells promotes myofibroblast differentiation of lung-resident mesenchymal stem cells during pulmonary fibrogenesis

Idiopathic pulmonary fibrosis (IPF) is a lethal and agnogenic interstitial lung disease, which has limited therapeutic options. Recently, the NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome has been demonstrated as an important contributor to various fibrotic diseases following its persistent activation. However, the role of NLRP3 inflammasome in pulmonary fibrogenesis still needs to be further clarified. Here, we found that the activation of the NLRP3 inflammasome was raised in fibrotic lungs. In addition, the NLRP3 inflammasome was found to be activated in alveolar epithelial cells (AECs) in the lung tissue of both IPF patients and pulmonary fibrosis mouse models. Further research revealed that epithelial cells, following activation of the NLRP3 inflammasome, could induce the myofibroblast differentiation of lung-resident mesenchymal stem cells (LR-MSCs). In addition, inhibiting the activation of the NLRP3 inflammasome in epithelial cells promoted the expression of dickkopf-1 (DKK1), a secreted Wnt antagonist. DKK1 was capable of suppressing the profibrogenic differentiation of LR-MSCs and bleomycin-induced pulmonary fibrosis. In conclusion, this study not only provides a further in-depth understanding of the pathogenesis of pulmonary fibrosis, but also reveals a potential therapeutic strategy for disorders associated with pulmonary fibrosis.

Long noncoding RNA-SNHG20 promotes silica-induced pulmonary fibrosis by miR-490-3p/TGFBR1 axis

Silicosis is a universal occupational disease, which is caused by long-term crystalline silica exposure. Recent studies have shown that noncoding RNAs participate in diverse pathological cellular pathways. However, the precise regulation mechanism remains limited in silicosis. Here, we established a silica-induced mouse fibrosis model (all mice received a one-time intratracheal instillation with 50 mg/kg of silica in 0.05 mL sterile saline). MiR-490-3p was significantly downregulated in silica-induced fibrotic mouse lung tissues and TGF-β1 treated fibroblasts. Moreover, overexpressed miR-490-3p could relieve silica-induced lung fibrosis in vivo, and prevent the process of fibroblast-to-myofibroblast transition(FMT)in vitro. Mechanistically, TGFBR1 was one of the major target genes of miR-490-3p, and tightly associated with the process of fibroblasts activation. SNHG20, as opposed to miR-490-3p expression, was elevated in TGF-β1-treated fibroblast cell lines and contributed to decreased levels of miR-490-3p. Taken together, these data indicated that miR-490-3p plays a key role in silica-induced pulmonary fibrosis. Our results suggested that SNHG20/miR-490-3p/TGFBR1 axis may provide a new treatment target of pulmonary fibrosis.

Combined In Vitro and In Vivo Approaches to Propose a Putative Adverse Outcome Pathway for Acute Lung Inflammation Induced by Nanoparticles: A Study on Carbon Dots

With the growth of nanotechnologies, concerns raised regarding the potential adverse effects of nanoparticles (NPs), especially on the respiratory tract. Adverse outcome pathways (AOP) have become recently the subject of intensive studies in order to get a better understanding of the mechanisms of NP toxicity, and hence hopefully predict the health risks associated with NP exposure. Herein, we propose a putative AOP for the lung toxicity of NPs using emerging nanomaterials called carbon dots (CDs), and in vivo and in vitro experimental approaches. We first investigated the effect of a single administration of CDs on mouse airways. We showed that CDs induce an acute lung inflammation and identified airway macrophages as target cells of CDs. Then, we studied the cellular responses induced by CDs in an in vitro model of macrophages. We observed that CDs are internalized by these cells (molecular initial event) and induce a series of key events, including loss of lysosomal integrity and mitochondrial disruption (organelle responses), as well as oxidative stress, inflammasome activation, inflammatory cytokine upregulation and macrophage death (cellular responses). All these effects triggering lung inflammation as tissular response may lead to acute lung injury.

NLRP3 Inflammasome: A Potential Therapeutic Target in Fine Particulate Matter-Induced Neuroinflammation in Alzheimer's Disease

As one of the most harmful air pollutants, fine particulate matter (PM2.5) has been implicated as a risk factor for multiple diseases, which has generated widespread public concern. Accordingly, a growing literature links PM2.5 exposure with Alzheimer's disease (AD). A critical gap in our understanding of the adverse effects of PM2.5 on AD is the mechanism triggered by PM2.5 that contributes to disease progression. Recent evidence has demonstrated that PM2.5 can activate NLRP3 inflammasome-mediated neuroinflammation. In this review, we highlight the novel evidence between PM2.5 exposure and AD incidence, which is collected and summarized from neuropathological, epidemiological, and neuroimaging studies to in-depth deciphering molecular mechanisms. First, neuropathological, epidemiological, and neuroimaging studies will be summarized. Then, the transport pathway for central nervous system delivery of PM2.5 will be presented. Finally, the role of NLRP3 inflammasome-mediated neuroinflammation in PM2.5 induced-effects on AD will be recapitulated.

The contribution of animal models to understanding the role of the immune system in human idiopathic pulmonary fibrosis

Pulmonary fibrosis occurs in a heterogeneous group of lung disorders and is characterised by an excessive deposition of extracellular matrix proteins within the pulmonary interstitium, leading to impaired gas transfer and a loss of lung function. In the past 10 years, there has been a dramatic increase in our understanding of the immune system and how it contributes to fibrogenic processes within the lung. This review will compare some of the models used to investigate the pathogenesis and treatment of pulmonary fibrosis, in particular those used to study immune cell pathogenicity in idiopathic pulmonary fibrosis, highlighting their advantages and disadvantages in dissecting human disease.

Advances in the molecular mechanisms of NLRP3 inflammasome activators and inactivators

NLRP3 inflammasome is an intracellular protein complex that initiates cellular injury via assembly of NLRP3, ASC and caspase-1 in response to microbial infection and sterile stressors. The importance of NLRP3 inflammasome in immunity and human diseases has been well documented. Up to now, targeted inhibition of the assembly of NLRP3 inflammasome complex and of its activation was thought to be therapeutic strategy for associated diseases. Recent studies show that a host of molecules such as NIMA-related kinase 7 (Nek7) and DEAD-box helicase 3 X-linked (DDX3X) and a large number of biological mediators including cytokines, microRNAs, nitric oxide, carbon monoxide, nuclear factor erythroid-2 related factor 2 (Nrf2) and cellular autophagy participate in the activation and inactivation of NLRP3 inflammasome. This review summarizes current understanding of the molecular basis of NLRP3 inflammasome activation and inactivation. This knowledge may lead to development of new therapies directed at NLRP3 inflammasome related diseases.