lncRNA Profiling of Exosomes and Its Communication Role in Regulating Silica-Stimulated Macrophage Apoptosis and Fibroblast Activation.

Long-term silica particle exposure leads to interstitial pulmonary inflammation and fibrosis, called silicosis. Silica-activated macrophages secrete a wide range of cytokines resulting in persistent inflammation. In addition, silica-stimulated activation of fibroblast is another checkpoint in the progression of silicosis. The pathogenesis after silica exposure is complex, involving intercellular communication and intracellular signaling pathway transduction, which was ignored previously. Exosomes are noteworthy because of their crucial role in intercellular communication by delivering bioactive substances, such as lncRNA. However, the expression profile of exosomal lncRNA in silicosis has not been reported yet. In this study, exosomes were isolated from the peripheral serum of silicosis patients or healthy donors. The exosomal lncRNAs were profiled using high-throughput sequencing technology. Target genes were predicted, and functional annotation was performed using differentially expressed lncRNAs. Eight aberrant expressed exosomal lncRNAs were considered to play a key role in the process of silicosis according to the OPLS-DA. Furthermore, the increased expression of lncRNA MSTRG.43085.16 was testified in vitro. Its target gene PARP1 was critical in regulating apoptosis based on bioinformatics analysis. In addition, the effects of exosomes on macrophage apoptosis and fibroblast activation were checked based on a co-cultured system. Our findings suggested that upregulation of lncRNA MSTRG.43085.16 could regulate silica-induced macrophage apoptosis through elevating PARP1 expression, and promote fibroblast activation, implying that the exosomal lncRNA MSTRG.43085.16 might have potential as a biomarker for the early diagnosis of silicosis.

Mechanism of KAT2A regulation of H3K36ac in manganese-induced oxidative damage to mitochondria in the nervous system and intervention by curcumin.

Excessive exposure to manganese in the environment or workplace is strongly linked to neurodegeneration and cognitive impairment, but the precise pathogenic mechanism and preventive measures are still not fully understood. The study aimed to investigate manganese -induced oxidative damage in the nervous system from an epigenetic perspective, focusing on the H3K36ac-dependent antioxidant pathway. Additionally, it sought to examine the potential of curcumin in preventing manganese-induced oxidative damage. Histopathology and transmission electron microscopy revealed that apoptosis and necrosis of neurons and mitochondrial ultrastructure damage were observed in the striatum of manganese-exposed rats. manganese suppressed the expression of mitochondrial antioxidant genes, leading to oxidative damage in the rats' striatum and SH-SY5Y cells. With higher doses of manganese, levels of histone acetyltransferase lysine acetyltransferase 2 A (KAT2A) expression and H3K36ac level decreased. ChIP-qPCR confirmed that H3K36ac enrichment in the promoter regions of antioxidant genes SOD2, PRDX3, and TXN2 was reduced in SH-SY5Y cells after manganese exposure, leading to decreased expression of these genes. Overexpression of KAT2A confirms that it attenuates manganese-induced mitochondrial oxidative damage by regulating H3K36ac levels, which in turn controls the expression of antioxidant genes SOD2, PRDX3, and TXN2 in the manganese-exposed cell model. Furthermore, curcumin might control H3K36ac levels by influencing KAT2A expression, boosting antioxidant genes expression, and reducing manganese-induced mitochondrial oxidative damage. In conclusion, the regulation of mitochondrial oxidative stress by histone acetylation may be an important mechanism of manganese-induced neurotoxicity. This regulation could be achieved by reducing the level of H3K36ac near the promoter region of mitochondrial-associated antioxidant genes via KAT2A. Curcumin mitigates manganese-induced oxidative damage in mitochondria and plays a crucial protective role in manganese-induced oxidative injury in the nervous system.

Identification of histone acetylation modification sites in the striatum of subchronically manganese-exposed rats.

Aim: To explore the specific histone acetylation sites and oxidative stress-related genes that are associated with the pathogenesis of manganese toxicity. Methods: We employed liquid chromatography-tandem mass spectrometry and bioinformatics analysis to identify acetylated proteins in the striatum of subchronic manganese-intoxicated rats. Results: We identified a total of 12 differentially modified histone acetylation sites: H3K9ac, H3K14ac, H3K18ac, H3K56ac and H3K79ac were upregulated and H3K27ac, H3K36ac, H4K91ac, H4K79ac, H4K31ac, H2BK16ac and H2BK20ac were downregulated. Additionally, we found that CAT, SOD1 and SOD2 might be epigenetically regulated and involved in the pathogenesis of manganism. Conclusion: This study identified histone acetylation sites and oxidative stress-related genes associated with the pathogenesis of manganese toxicity, and these findings are useful in the search for potential epigenetic targets for manganese toxicity.

Manganese induces oxidative damage in the hippocampus by regulating the expression of oxidative stress-related genes via modulation of H3K18 acetylation.

Prolonged exposure to manganese (Mn) contributes to hippocampal Mn accumulation, which leads to neurodegenerative diseases called manganese poisoning. However, the underlying molecular mechanisms remain unclear and there are no ideal biomarkers. Oxidative stress is the essential mechanisms of Mn-related neurotoxicity. Furthermore, histone acetylation has been identified as being engaged in the onset and development of neurodegenerative diseases. Therefore, the work aims to understand the molecular mechanisms of oxidative damage in the hippocampus due to Mn exposure from the aspect of histone acetylation modification and to assess whether H3K18 acetylation (H3K18ac) modification level in peripheral blood reflect Mn-induced oxidative damage in the hippocampus. Here, we randomly divided 60 male rats into four groups and injected them intraperitoneally with sterile pure water and MnCl2 ⋅4H2 O (5, 10, and 15 mg/kg) for 16 weeks, 5 days a week, once a day. The data confirmed that Mn exposure down-regulated superoxide dismutase activity and glutathione level as well as up-regulated malondialdehyde level in the hippocampus and plasma, and that there was a positive correlation between these indicators in the hippocampus and plasma. Besides, we noted that Mn treatment upregulated H3K18ac modification levels in the hippocampus and peripheral blood and that H3K18ac modification levels correlated with oxidative stress. Further studies demonstrated that Mn treatment decreased the amounts of H3K18ac enrichment in the manganese superoxide dismutase (SOD2) and glutathione transferase omega 1 (GSTO1) gene promoter regions, contributing to oxidative damage in the hippocampus. In short, our results demonstrate that Mn induces oxidative damage in the hippocampus by inhibiting the expression of SOD2 and GSTO1 genes via modulation of H3K18ac. In assessing Mn-induced hippocampal neurotoxicity, oxidative damage in plasma may reflect hippocampal oxidative damage in Mn-exposed groups.

Mechanism by which HDAC3 regulates manganese induced H3K27ac in SH-SY5Y cells and intervention by curcumin.

Long-term excessive exposure to manganese can impair neuronal function in the brain, but the underlying pathological mechanism remains unclear. Oxidative stress plays a central role in manganese-induced neurotoxicity. Numerous studies have established a strong link between abnormal histone acetylation levels and the onset of various diseases. Histone deacetylase inhibitors and activators, such as TSA and ITSA-1, are often used to investigate the intricate mechanisms of histone acetylation in disease. In addition, recent experiments have provided substantial evidence demonstrating that curcumin (Cur) can act as an epigenetic regulator. Given these findings, this study aims to investigate the mechanisms underlying oxidative damage in SH-SY5Y cells exposed to MnCl2·4H2O, with a particular focus on histone acetylation, and to assess the potential therapeutic efficacy of Cur. In this study, SH-SY5Y cells were exposed to manganese for 24 h, were treated with TSA or ITSA-1, and were treated with or without Cur. The results suggested that manganese exposure, which leads to increased expression of HDAC3, induced H3K27 hypoacetylation, inhibited the transcription of antioxidant genes, decreased antioxidant enzyme activities, and induced oxidative damage in cells. Pretreatment with an HDAC3 inhibitor (TSA) increased the acetylation of H3K27 and the transcription of antioxidant genes and thus slowed manganese exposure-induced cellular oxidative damage. In contrast, an HDAC3 activator (ITSA-1) partially increased manganese-induced cellular oxidative damage, while Cur prevented manganese-induced oxidative damage. In summary, these findings suggest that inhibiting H3K27ac is a possible mechanism for ameliorating manganese-induced damage to dopaminergic neurons and that Cur exerts a certain protective effect against manganese-induced damage to dopaminergic neurons.

Advances in the study of silica nanoparticles in lung diseases.

Silicon dioxide nanoparticles (SiNPs) are one of the major forms of silicon dioxide and are composed of the most-abundant compounds on earth. Based on their excellent properties, SiNPs are widely used in food production, synthetic processes, medical diagnostics, drug delivery, and other fields. The mass production and wide application of SiNPs increases the risk of human exposure to SiNPs. In the workplace and environment, SiNPs mainly enter the human body through the respiratory tract and reach the lungs; therefore, the lungs are the most important and most toxicologically affected target organ of SiNPs. An increasing number of studies have shown that SiNP exposure can cause severe lung toxicity. However, studies on the toxicity of SiNPs in ex vivo and in vivo settings are still in the exploratory phase. The molecular mechanisms underlying the lung toxicity of SiNPs are varied and not yet fully understood. As a result, this review summarizes the possible mechanisms of SiNP-induced lung toxicity, such as oxidative stress, endoplasmic reticulum stress, mitochondrial damage, and cell death. Moreover, this study provides a summary of the progression of diseases caused by SiNPs, thereby establishing a theoretical basis for future studies on the mechanisms of SiNP-induced lung toxicity.

The therapeutic effect of exosomal lncRNA MSTRG.91634.7 on mitochondrial dysfunction during SiO2-induced lung fibrosis.

Long-term silica (SiO2) exposure led to irreversible lung fibrosis, in which epithelial-mesenchymal transition (EMT) played an essential role. A novel lncRNA MSTRG.91634.7 in the peripheral exosomes of silicosis patients was reported in our previous study, which could remold the pathological process of silicosis. However, whether its regulatory role on the development of silicosis was related to EMT process is unclear, and its mechanism remains to be further studied. In this study, up-regulating lncRNA MSTRG91634.7 restricted SiO2-activated EMT and restored mitochondrial homeostasis binding to PINK1 in vitro. Moreover, overexpressing PINK1 could inhibit SiO2-activated EMT in pulmonary inflammation and fibrosis in mice. Meanwhile, PINK1 contributed to restoring the SiO2-induced mitochondrial dysfunction in mice lung. Our results revealed that exosomal lncRNA MSTRG.91634.7 from macrophages could restore mitochondrial homeostasis to restrict the SiO2-activated EMT by binding to PINK1 during pulmonary inflammation and fibrosis due to SiO2 exposure.

Crystalline silica-induced macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis.

Environmental exposure to crystalline silica (CS) can lead to silicosis. Alveolar macrophages (AMs) play a crucial role in the pathogenesis of silicosis. Previously, we demonstrated that enhancing AMs mitophagy exerted protective effects on silicosis with a restrained inflammatory response. However, the exact molecular mechanisms are elusive. Pyroptosis and mitophagy are two different biological processes that determine cell fate. Exploring whether there were interactions or balances between these two processes in AMs would provide new insight into treating silicosis. Here we reported that crystalline silica induced pyroptosis in silicotic lungs and AMs with apparent mitochondria injury. Notably, we identified a reciprocal inhibitory effect between mitophagy and pyroptosis cascades in AMs. By enhancing or diminishing mitophagy, we demonstrated that PINK1-mediated mitophagy helped clear damaged mitochondria to negatively regulate CS-induced pyroptosis. While constraining pyroptosis cascades by NLRP3, Caspase1, and GSDMD inhibitors, respectively, displayed enhanced PINK1-dependent mitophagy with lessened CS-injured mitochondria. These observed effects were echoed in the mice with enhanced mitophagy. Therapeutically, we demonstrated abolishing GSDMD-dependent pyroptosis by disulfiram attenuated CS-induced silicosis. Collectively, our data demonstrated that macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis, which may provide potential therapeutic targets.

The aggravate role of exosomal circRNA11:120406118|12040782 on macrophage pyroptosis through miR-30b-5p/NLRP3 axis in silica-induced lung fibrosis.

Silica dust inhalation could lead to silicosis, and there is no specific biomarker for its early diagnosis and no effective treatment due to the lack of research on its pathogenesis. The homeostasis of macrophages was considered to be crucial during the development of silicosis from persistent chronic inflammation to irreversible fibrosis. However, its regulatory mechanism and the communication between macrophages and others are still not clear. Exosomal circRNAs emerge as favorable candidates for cellular communication. Therefore, our study aimed to illustrate the regulatory mechanism of silicosis from the view of exosomal circRNAs. Our study identified a novel exosomal circRNA, circRNA11:120406118|12040782, in the peripheral serum of silicosis patients. Furthermore, the detailed role of circRNA11:120406118|12040782 was investigated both in silicosis mouse model and in silica-stimulated macrophages and fibroblasts. On the one hand, circRNA11:120406118|12040782 was shown to regulate silica-stimulated macrophage pyroptosis through circRNA11:120406118|12040782/miR-30b-5p/NLRP3 network. And this macrophage-derived cirRNA could promote the activation of fibroblasts. On the other hand, overexpressing miR-30b-5p, the crucial component of circRNA11:120406118|12040782/miR-30b-5p/NLRP3 regulatory network, could inhibit pyroptosis and attenuate silica-induced lung inflammation and fibrosis in mice. Our findings suggested that exosomal circRNA11:120406118|12040782 could aggravate NLRP3-mediated macrophages pyroptosis through sponging miR-30b-5p in silicosis development, which provide an experimental basis and shed light on the early diagnosis and treatment of silicosis.

Macrophage-derived exosomal lncRNA MSTRG.91634.7 inhibits fibroblasts activation by targeting PINK1 in silica-induced lung fibrosis.

Silicosis is a fibrotic lung disease caused by the inhalation of free crystalline silica. Its pathogenesis is extremely complex and involves a variety of cells. Exosomes emerge as a favorable candidate for communication between cells. LncRNA is a major component transported by exosomes in many inflammatory diseases. However, the role of exosomal lncRNA in the pathogenesis of silicosis is still unclear. In this study, the decreased expression of a novel exosomal lncRNA MSTRG.91634.7 in silicosis patients was identified according to high-throughput sequencing. Then, this macrophage-derived exosomal lncRNA MSTRG.91634.7 could regulate the fibroblast's activation by targeting PINK1 in a co-culture system of THP-1 and MRC-5. Finally, the mouse was exposed to 3 mg/50 µL silica to set up the silicosis model. AAV-ov-Pink1 was intratracheally injected to overexpress PINK1 in mice lungs. Our results suggested that PINK1, the target protein of lncRNA MSTRG.91634.7, participated in restricting the silica-induced lung inflammation and fibrosis in mice.

Trehalose Alleviates Crystalline Silica-Induced Pulmonary Fibrosis via Activation of the TFEB-Mediated Autophagy-Lysosomal System in Alveolar Macrophages.

Silicosis is an occupational lung disease characterized by persistent inflammation and irreversible fibrosis. Crystalline silica (CS) particles are mainly phagocytized by alveolar macrophages (AMs), which trigger apoptosis, inflammation, and pulmonary fibrosis. Previously, we found that autophagy-lysosomal system dysfunction in AMs was involved in CS-induced inflammation and fibrosis. Induction of autophagy and lysosomal biogenesis by transcription factor EB (TFEB) nuclear translocation can rescue fibrotic diseases. However, the role of TFEB in silicosis is unknown. In this study, we found that CS induced TFEB nuclear localization and increased TFEB expression in macrophages both in vivo and in vitro. However, TFEB overexpression or treatment with the TFEB activator trehalose (Tre) alleviated lysosomal dysfunction and enhanced autophagic flux. It also reduced apoptosis, inflammatory cytokine levels, and fibrosis. Both pharmacologically inhibition of autophagy and TFEB knockdown in macrophages significantly abolished the antiapoptotic and anti-inflammatory effects elicited by either TFEB overexpression or Tre treatment. In conclusion, these results uncover a protective role of TFEB-mediated autophagy in silicosis. Our study suggests that restoration of autophagy-lysosomal function by Tre-induced TFEB activation may be a novel strategy for the treatment of silicosis.