SOCS-1 Suppresses Inflammation Through Inhibition of NALP3 Inflammasome Formation in Smoke Inhalation-Induced Acute Lung Injury

CircRNA-associated ceRNA regulatory networks as emerging mechanisms governing the development and biophysiopathology of epilepsy

The etiology of epilepsy is ascribed to the synchronized aberrant neuronal activity within the brain. Circular RNAs (circRNAs), a class of non-coding RNAs characterized by their circular structures and covalent linkage, exert a substantial influence on this phenomenon. CircRNAs possess stereotyped replication, transience, repetitiveness, and paroxysm. Additionally, MicroRNA (miRNA) plays a crucial role in the regulation of diverse pathological processes, including epilepsy. CircRNA is of particular significance due to its ability to function as a competing endogenous RNA, thereby sequestering or inhibiting miRNA activity through binding to target mRNA. Our review primarily concentrates on elucidating the pathological and functional roles, as well as the underlying mechanisms, of circRNA-miRNA-mRNA networks in epilepsy. Additionally, it explores the potential utility of these networks for early detection and therapeutic intervention.

Suppressor of Cytokine Signaling 1 Haploinsufficiency: A New Driver of Autoimmunity and Immunodysregulation

Suppressor of cytokine signaling 1 (SOCS1) is a negative regulator of cytokine signaling that inhibits the activation of Janus kinases. A human disease caused by SOCS1 haploinsufficiency was first identified in 2020. To date, 18 cases of SOCS1 haploinsufficiency have been described. These patients experience enhanced activation of leukocytes and multiorgan system immunodysregulation, with immune-mediated cytopenia as the most common feature. In this review, the authors provide an overview on the biology of SOCS1 and summarize their knowledge of SOCS1 haploinsufficiency including genetics and clinical manifestations. They discuss the available treatment experience and outline an approach for the evaluation of suspected cases.

SOCS3 Protein Mediates the Therapeutic Efficacy of Mesenchymal Stem Cells against Acute Lung Injury

Mesenchymal stem cells (MSCs) have been studied as novel therapeutic agents because of their immunomodulatory properties in inflammatory diseases. The suppressor of cytokine signaling (SOCS) proteins are key regulators of the immune response and macrophage modulation. In the present study, we hypothesized that SOCS in MCSs might mediate macrophage modulation and tested this in a bacteria-induced acute lung injury (ALI) mouse model. The macrophage phenotype was observed in RAW264.7 alveolar macrophages exposed to lipopolysaccharide (LPS) in an in vitro model, and in the ALI mouse model induced by tracheal administration of Escherichia coli (1 × 10⁷ CFU in 0.05mL PBS). In LPS-exposed RAW264.7 cells, the levels of markers of M1 macrophages, such as CD86 and pro-inflammatory cytokines (IL-1α, IL-1β, IL-6 and TNF-α), significantly increased, but they significantly reduced after MSC treatment. Meanwhile, the levels of markers of M2 macrophages, such as CD204 and anti-inflammatory cytokines (IL-4 and IL-10), increased after LPS exposure, and further significantly increased after MSC treatment. This regulatory effect of MSCs on M1/M2 macrophage polarization was significantly abolished by SOCS3 inhibition. In the E. coli-induced ALI model, tissue injury and inflammation in the mouse lung were significantly attenuated by the transplantation of MSCs, but not by SOCS3-inhibited MSCs. The regulatory effect of MSCs on M1/M2 macrophage polarization was observed in the lung injury model but was significantly abolished by SOCS3 inhibition. Taken together, our findings suggest that SOCS3 is an important mediator for macrophage modulation in anti-inflammatory properties of MSCs.

Cigarette smoke depletes alveolar macrophages and delays clearance of Legionella pneumophila

Legionella pneumophila is the main etiological agent of Legionnaires' disease, a severe bacterial pneumonia. L. pneumophila is initially engulfed by alveolar macrophages (AMs) and subvert normal cellular functions to establish a replicative vacuole. Cigarette smokers are particularly susceptible to developing Legionnaires' disease and other pulmonary infections; however, little is known about the cellular mechanisms underlying this susceptibility. To investigate this, we used a mouse model of acute cigarette smoke exposure to examine the immune response to cigarette smoke and subsequent L. pneumophila infection. Contrary to previous reports, we show that cigarette smoke exposure alone causes a significant depletion of AMs using enzymatic digestion to extract cells, or via imaging intact lung lobes by light-sheet microscopy. Furthermore, treatment of mice deficient in specific types of cell death with smoke suggests that NLRP3-driven pyroptosis is a contributor to smoke-induced death of AMs. After infection, smoke-exposed mice displayed increased pulmonary L. pneumophila loads and developed more severe disease compared with air-exposed controls. We tested if depletion of AMs was related to this phenotype by directly depleting them with clodronate liposomes and found that this also resulted in increased L. pneumophila loads. In summary, our results showed that cigarette smoke depleted AMs from the lung and that this likely contributed to more severe Legionnaires' disease. Furthermore, the role of AMs in L. pneumophila infection is more nuanced than simply providing a replicative niche, and our studies suggest they play a major role in bacterial clearance.

IFN- Is Protective in Cytokine Release Syndrome-associated Extrapulmonary Acute Lung Injury

The mechanisms by which excessive systemic activation of adaptive T lymphocytes, as in cytokine release syndrome (CRS), leads to innate immune cell-mediated acute lung injury (ALI) or acute respiratory distress syndrome, often in the absence of any infection, remains unknown. Here, we investigated the roles of IFN-γ and IL-17A, key T-cell cytokines significantly elevated in patients with CRS, in the immunopathogenesis of CRS-induced extrapulmonary ALI. CRS was induced in wild-type (WT), IL-17A- and IFN-γ knockout (KO) human leukocyte antigen-DR3 transgenic mice with 10 μg of the superantigen, staphylococcal enterotoxin B, given intraperitoneally. Several ALI parameters, including gene expression profiling in the lungs, were studied 4, 24, or 48 hours later. Systemic T-cell activation with staphylococcal enterotoxin B resulted in robust upregulation of several chemokines, S100A8/A9, matrix metalloproteases, and other molecules implicated in tissue damage, granulocyte as well as agranulocyte adhesion, and diapedesis in the lungs as early as 4 hours, which was accompanied by subsequent neutrophil/eosinophil lung infiltration and severe ALI in IFN-γ KO mice. These pathways were significantly underexpressed in IL-17A KO mice, which manifested mildest ALI and intermediate in WT mice. Neutralization of IFN-γ worsened ALI in WT and IL-17A KO mice, whereas neutralizing IL-17A did not mitigate lung injury in IFN-γ KO mice, suggesting a dominant protective role for IFN-γ in ALI and that IL-17A is dispensable. Ruxolitinib, a Janus kinase inhibitor, increased ALI severity in WT mice. Thus, our study identified novel mechanisms of ALI in CRS and its differential modulation by IFN-γ and IL-17A.

SOCS1 Haploinsufficiency Presenting as Severe Enthesitis, Bone Marrow Hypocellularity, and Refractory Thrombocytopenia in a Pediatric Patient with Subsequent Response to JAK Inhibition

Haploinsufficiency of suppressor of cytokine signaling 1 (SOCS1) is a recently discovered autoinflammatory disorder with significant rheumatologic, immunologic, and hematologic manifestations. Here we report a case of SOCS1 haploinsufficiency in a 5-year-old child with profound arthralgias and immune-mediated thrombocytopenia unmasked by SARS-CoV-2 infection. Her clinical manifestations were accompanied by excessive B cell activity, eosinophilia, and elevated IgE levels. Uniquely, this is the first report of SOCS1 haploinsufficiency in the setting of a chromosomal deletion resulting in complete loss of a single SOCS1 gene with additional clinical findings of bone marrow hypocellularity and radiologic evidence of severe enthesitis. Immunologic profiling showed a prominent interferon signature in the patient's peripheral blood mononuclear cells, which were also hypersensitive to stimulation by type I and type II interferons. The patient showed excellent clinical and functional laboratory response to tofacitinib, a Janus kinase inhibitor that disrupts interferon signaling. Our case highlights the need to utilize a multidisciplinary diagnostic approach and consider a comprehensive genetic evaluation for inborn errors of immunity in patients with an atypical immune-mediated thrombocytopenia phenotype.

LncRNA MALAT1 Participates in Protection of High-Molecular-Weight Hyaluronan against Smoke-Induced Acute Lung Injury by Upregulation of SOCS-1

Smoke-induced acute lung injury (ALI) is a grievous disease with high mortality. Despite advances in medical intervention, no drug has yet been approved by the Food and Drug Administration (FDA) for ALI. In this study, we reported that pretreatment with high-molecular-weight hyaluronan (1600 kDa, HA1600) alleviated pulmonary inflammation and injury in mice exposed to smoke and also upregulated long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), as well as suppressor of cytokine signaling-1 (SOCS-1), in the lung tissues. Next, we overexpressed MALAT1 in the lungs by intratracheal administration of adenovirus cloned with MALAT1 cDNA and found that the survival of mice after smoke exposure was improved. Moreover, pulmonary overexpression of MALAT1 ameliorated smoke-induced ALI in mice and elevated the level of SOCS-1 in the lungs. In conclusion, the results pointed out that HA1600 exerted a protective effect against smoke-induced ALI through increasing the MALAT1 level and the subsequent SOCS-1 expression. Our study provides a potential therapeutic approach to smoke-induced ALI and a novel insight into the mechanism of action of HA1600.

Targeting purinergic receptors to suppress the cytokine storm induced by SARS-CoV-2 infection in pulmonary tissue

The etiological agent of coronavirus disease (COVID-19) is the new member of the Coronaviridae family, a severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2), responsible for the pandemic that is plaguing the world. The single-stranded RNA virus is capable of infecting the respiratory tract, by binding the spike (S) protein on its viral surface to receptors for the angiotensin II-converting enzyme (ACE2), highly expressed in the pulmonary tissue, enabling the interaction of the virus with alveolar epithelial cells promoting endocytosis and replication of viral material. The infection triggers the activation of the immune system, increased purinergic signaling, and the release of cytokines as a defense mechanism, but the response can become exaggerated and prompt the so-called “cytokine storm”, developing cases such as severe acute respiratory syndrome (SARS). This is characterized by fever, cough, and difficulty breathing, which can progress to pneumonia, failure of different organs and death. Thus, the present review aims to compile and correlate the mechanisms involved between the immune and purinergic systems with COVID-19, since the modulation of purinergic receptors, such as A2A, A2B, and P2X7 expressed by immune cells, seems to be effective as a promising therapy, to reduce the severity of the disease, as well as aid in the treatment of acute lung diseases and other cases of generalized inflammation.

Roles of Inflammasome in Cigarette Smoke-Related Diseases and Physiopathological Disorders: Mechanisms and Therapeutic Opportunities

Cigarette smoke damages a wide range of immunological functions, including innate and adaptive immune responses. Emerging literature demonstrates that inflammasome constitutes an essential component in innate immune response. In this review, we focus on the cumulative mechanisms of inflammasome in cigarette smoke-related diseases and physiopathological disorders, and summarize potential therapeutic opportunities targeting inflammasome. This review suggests that inflammasomes (NLRP3, NLRP6, NLRP12 and AIM2) are involved in the pathogenesis of several cigarette smoke-related diseases (including COPD, ALI, atherosclerosis, kidney injury, bladder dysfunction, and oral leukoplakia) and physiopathological disorders (macrophage dysfunction, endothelial barrier dysfunction, podocyte injury, and ubiquitin-mediated proteasomal processing). MyD88/NF-κB, HMGB1, production of ROS, endoplasmic reticulum stress and mitochondrial dysfunction, and Ca²⁺ influx are potentially involved in cigarette smoke induced-inflammasome activation. Strategies targeting ROS/NLRP3 inflammasome axis are most widely investigated and show potential therapeutic effects.

Microtubule-dependent mechanism of anti-inflammatory effect of SOCS1 in endothelial dysfunction and lung injury

Suppressors of cytokine signaling (SOCS) provide negative regulation of inflammatory reaction. The role and precise cellular mechanisms of SOCS1 in control of endothelial dysfunction and barrier compromise associated with acute lung injury remain unexplored. Our results show that siRNA-mediated SOCS1 knockdown augmented lipopolysaccharide (LPS)-induced pulmonary endothelial cell (EC) permeability and enhanced inflammatory response. Consistent with in vitro data, EC-specific SOCS1 knockout mice developed more severe lung vascular leak and accumulation of inflammatory cells in bronchoalveolar lavage fluid. SOCS1 overexpression exhibited protective effects against LPS-induced endothelial permeability and inflammation, which were dependent on microtubule (MT) integrity. Biochemical and image analysis of unstimulated EC showed SOCS1 association with the MT, while challenge with LPS or MT depolymerizing agent colchicine impaired this association. SOCS1 directly interacted with N2 domains of MT-associated proteins CLIP-170 and CLASP2. Furthermore, N-terminal region of SOCS1 was indispensable for these interactions and SOCS1-ΔN mutant lacking N-terminal 59 amino acids failed to rescue LPS-induced endothelial dysfunction. Depletion of endogenous CLIP-170 or CLASP2 abolished SOCS1 interaction with Toll-like receptor-4 and Janus kinase-2 leading to impairment of SOCS1 inhibitory effects on LPS-induced inflammation. Altogether, these findings suggest that endothelial barrier protective and anti-inflammatory effects of SOCS1 are critically dependent on its targeting to the MT.

Inflammatory Caspases Drive Pyroptosis in Acute Lung Injury

Acute lung injury (ALI), a critical respiratory disorder that causes diffuse alveolar injury leads to high mortality rates with no effective treatment. ALI is characterized by varying degrees of ventilation/perfusion mismatch, severe hypoxemia, and poor pulmonary compliance. The diffuse injury to cells is one of most important pathological characteristics of ALI. Pyroptosis is a form of programmed cell death distinguished from apoptosis induced by inflammatory caspases, which can release inflammatory cytokines to clear cells infected by pathogens and promote monocytes to reassemble at the site of injury. And pyroptosis not only promotes inflammation in certain cell types, but also regulates many downstream pathways to perform different functions. There is increasing evidence that pyroptosis and its related inflammatory caspases play an important role in the development of acute lung injury. The main modes of activation of pyroptosis is not consistent among different types of cells in lung tissue. Meanwhile, inhibition of inflammasome, the key to initiating pyroptosis is currently the main way to treat acute lung injury. The review summarizes the relationship among inflammatory caspases, pyroptosis and acute lung injury and provides general directions and strategies to conduct further research.

Gryllus bimaculatus extract protects against lipopolysaccharide and palmitate-induced production of proinflammatory cytokines and inflammasome formation

Inflammation and the inflammasome complex formation are associated with numerous diseases, and palmitates or lipopolysaccharides (LPS) have been identified as potential links between these disorders. Recently, edible insects such as the Gryllus bimaculatus (GB) and the larva of Tenebrio molitor have emerged as alternative food sources. In the present study, the effect of GB on LPS- or palmitate-induced production of inflammatory cytokines, the formation of the inflammasome complex, reactive oxygen species (ROS) generation, endoplasmic reticulum (ER) stress and cell death was investigated in RAW264.7 cells. The results revealed that GB extract downregulated the production of inflammatory cytokines (such as TNF-α, IL-1β and IL-6). Since the role of the MAP kinase and NF-κB signalling pathways in the production of inflammatory cytokines is well established, the translocation of p65 into the nucleus and the phosphorylation of IκB and MAP kinases were further examined. Both these processes were upregulated following LPS and palmitate treatment, but they were inhibited by the GB extract. Moreover, GB extract decreased LPS/palmitate-induced inflammasome complex formation (assessed via analysing the levels of the apoptosis-associated speck-like protein containing a caspase-recruitment domain, NOD-like receptor family pyrin domain containing 3, cleaved caspase-1 and IL-1β), the generation of ROS, ER stress and cell death. Treatment with SB203580 (a p38 inhibitor), SP600125 (a JNK inhibitor) and pyrrolidinedithiocarbamate ammonium (an NF-κB inhibitor) decreased the production of inflammatory cytokines, as well as helped in the recovery of LPS/palmitate-induced cell death. Overall, GB extract served an inhibitory role in LPS/palmitate-induced inflammation via inhibiting the MAP kinase and NF-κB signalling pathways, inflammasome complex formation, ROS generation, ER stress and cell death.

P2 Purinergic Signaling in the Distal Lung in Health and Disease

The distal lung provides an intricate structure for gas exchange in mammalian lungs. Efficient gas exchange depends on the functional integrity of lung alveoli. The cells in the alveolar tissue serve various functions to maintain alveolar structure, integrity and homeostasis. Alveolar epithelial cells secrete pulmonary surfactant, regulate the alveolar surface liquid (ASL) volume and, together with resident and infiltrating immune cells, provide a powerful host-defense system against a multitude of particles, microbes and toxicants. It is well established that all of these cells express purinergic P2 receptors and that purinergic signaling plays important roles in maintaining alveolar homeostasis. Therefore, it is not surprising that purinergic signaling also contributes to development and progression of severe pathological conditions like pulmonary inflammation, acute lung injury/acute respiratory distress syndrome (ALI/ARDS) and pulmonary fibrosis. Within this review we focus on the role of P2 purinergic signaling in the distal lung in health and disease. We recapitulate the expression of P2 receptors within the cells in the alveoli, the possible sources of ATP (adenosine triphosphate) within alveoli and the contribution of purinergic signaling to regulation of surfactant secretion, ASL volume and composition, as well as immune homeostasis. Finally, we summarize current knowledge of the role for P2 signaling in infectious pneumonia, ALI/ARDS and idiopathic pulmonary fibrosis (IPF).

BMSC-derived exosomes alleviate smoke inhalation lung injury through blockade of the HMGB1/NF-κB pathway

AIMS

To investigate the role of bone marrow mesenchymal stem cell (BMSC)-derived exosomes in smoke inhalation lung injury.

MAIN METHODS

In this study, we initially isolated exosomes from BMSCs and identified them by western blot and transmission electron microscopy. BMSC-derived exosomes were then used to treat in vitro and in vivo models of smoke inhalation lung injury. Pathologic alterations in lung tissue, the levels of inflammatory factors and apoptosis-related factors, and the expression of HMGB1 and NF-κB were determined to evaluate the therapeutic effect of BMSC-derived exosomes.

KEY FINDINGS

We found that BMSC-derived exosomes could alleviate the injury caused by smoke inhalation. Smoke inhalation increased the levels of inflammatory factors and apoptosis-related factors and the expression of HMGB1 and NF-κB, and these increases were reversed by BMSC-derived exosomes. HMGB1 overexpression abrogated the exosome-induced decreases in inflammatory factors, apoptosis-related factors and NF-κB.

SIGNIFICANCE

Collectively, these results indicate that BMSC-derived exosomes can effectively alleviate smoke inhalation lung injury by inhibiting the HMGB1/NF-κB pathway, suggesting that exosome, a noncellular therapy, is a potential therapeutic strategy for inhalation lung injury.

Trichostatin A alleviated ovarian tissue damage caused by cigarette smoke exposure

Cigarette smoke (CS) has a negative impact on women's health and fertility. Studies have shown that histone deacetylases 1 and 2 (HDAC1/2) were involved in oocyte development. However, the roles of HDAC1/2 in ovarian toxicity caused by CS exposure and the therapeutic potential of trichostatin A (TSA, a HDAC inhibitor) for ovarian tissue damage have not been investigated. In this study, Female C57BL/6 mice were exposed to CS from six cigarettes mixed with indoor air for 120 min (one cigarette for 20 min) using a whole-body mainstream smoke exposure system twice daily for 30 days. TSA (0.6 mg/kg body weight) was injected intraperitoneally into mice in the Control + TSA group and CS + TSA group every two days for 30 days. We found that exposure to CS resulted in ovarian tissue damage and HDAC1/2 over-expression. TSA alleviated the structural changes of ovarian tissue induced by smoking and prevented the activation of HDAC1/2. Exposure to CS caused autophagy inhibition and pyroptosis activation. TSA treatment restored the expression of autophagy-associated proteins and decreased the levels of pyroptosis-related proteins induced by CS exposure. The TSA effect may be mediated by inhibition of HDAC1/2 involved in autophagy and pyroptosis process.

Emerging therapies for smoke inhalation injury: a review

Background

Smoke inhalation injury increases overall burn mortality by up to 20 times. Current therapy remains supportive with a failure to identify an optimal or targeted treatment protocol for smoke inhalation injury. The goal of this review is to describe emerging therapies that are being developed to treat the pulmonary pathology induced by smoke inhalation injury with or without concurrent burn injury.

Main body

A comprehensive literature search was performed using PubMed (1995–present) for therapies not approved by the U.S. Food and Drug Administration (FDA) for smoke inhalation injury with or without concurrent burn injury. Therapies were divided based on therapeutic strategy. Models included inhalation alone with or without concurrent burn injury. Specific animal model, mechanism of action of medication, route of administration, therapeutic benefit, safety, mortality benefit, and efficacy were reviewed. Multiple potential therapies for smoke inhalation injury with or without burn injury are currently under investigation. These include stem cell therapy, anticoagulation therapy, selectin inhibition, inflammatory pathway modulation, superoxide and peroxynitrite decomposition, selective nitric oxide synthase inhibition, hydrogen sulfide, HMG-CoA reductase inhibition, proton pump inhibition, and targeted nanotherapies. While each of these approaches shows a potential therapeutic benefit to treating inhalation injury in animal models, further research including mortality benefit is needed to ensure safety and efficacy in humans.

Conclusions

Multiple novel therapies currently under active investigation to treat smoke inhalation injury show promising results. Much research remains to be conducted before these emerging therapies can be translated to the clinical arena.

MicroRNA-155 Participates in Smoke-Inhalation-Induced Acute Lung Injury through Inhibition of SOCS-1

Smoke inhalation causes acute lung injury (ALI), a severe clinical disease with high mortality. Accumulating evidence indicates that microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS-1), as mediators of inflammatory response, are involved in the pathogenesis of ALI. In this paper, we explored the proinflammatory mechanism of miR-155 in smoke-inhalation-induced ALI. Our data revealed that smoke inhalation induces miR-155 expression, and miR-155 knockout (KO) significantly ameliorates smoke-inhalation-induced lung injury in mice. Neutrophil infiltration and myeloperoxidase (MPO), macrophage inflammatory protein 2 (MIP-2) and keratinocyte chemoattractant (KC) expressions were decreased in miR-155^–/– mice after smoke inhalation as well. Real-time RT-PCR and immunoblotting results showed that SOCS-1 level was remarkably increased in miR-155^–/– mice after smoke exposure. Furthermore, the experiments performed in isolated miR-155 KO pulmonary neutrophils demonstrated that the lack of SOCS-1 enhanced inflammatory cytokines (MIP-2 and KC) secretion in response to smoke stimulation. In conclusion, smoke induces increased expression of miR-155, and miR-155 is involved in inflammatory response to smoke-inhalation-induced lung injury by inhibiting the expression of SOCS-1.

[Effect of asiaticoside on hyperoxia-induced bronchopulmonary dysplasia in neonatal rats and related mechanism]

OBJECTIVE

To study the protective effect of asiaticoside against hyperoxia-induced bronchopulmonary dysplasia in neonatal rats based on the microRNA-155 (miR-155)/suppressor of cytokine signaling-1 (SOCS1) axis.

METHODS

Neonatal rats were randomly divided into a control group, a model group, a low-dose asiaticoside group (10 mg/kg), a middle-dose asiaticoside group (25 mg/kg), a high-dose asiaticoside group (50 mg/kg), and a budesonide group (1.5 mg/kg), with 12 rats in each group. All rats except those in the control group were exposed to a high concentration of oxygen for 14 days to establish a neonatal rat model of bronchopulmonary dysplasia. The low-, middle-, and high-dose asiaticoside groups were given asiaticoside at different doses by gavage, and those in the budesonide group were given budesonide aerosol treatment. Hematoxylin and eosin staining was used to observe lung tissue development and measure radial alveolar count (RAC) and mean linear intercept (MLI). Superoxide dismutase (SOD) and malondialdehyde (MDA) detection kits were used to measure the levels of SOD and MDA in lung tissue. ELISA was used to measure the serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Quantitative real-time PCR was used to measure the mRNA expression of miR-155 and SOCS1 in lung tissue. Western blotting was used to measure the protein expression of SOCS1 in lung tissue.

RESULTS

Compared with the control group, the model group had the symptoms of bronchopulmonary dysplasia such as a disordered structure of lung tissue, enlargement of alveolar fusion, uneven alveolar septa, enlargement of average alveolar space, and a reduction in alveolar number. The model group also had significant increases in MLI, MDA level in lung tissue, serum levels of IL-6 and TNF-α, and miR-155 level in lung tissue (P<0.05) and significant reductions in RAC, SOD level, and mRNA and protein expression of SOCS1 in lung tissue (P<0.05). Compared with the model group, the low-, middle-, and high-dose asiaticoside groups and the budesonide group had significant improvement in the above symptoms of bronchopulmonary dysplasia, significant reductions in MLI, MDA level in lung tissue, serum levels of IL-6 and TNF-α, and miR-155 level in lung tissue (P<0.05), and significant increases in RAC, SOD level, and mRNA and protein expression of SOCS1 in lung tissue (P<0.05). Asiaticoside improved the above symptoms and indices in a dose-dependent manner. There were no significant differences in the above indices between the high-dose asiaticoside and budesonide groups (P>0.05).

CONCLUSIONS

Asiaticoside can alleviate inflammation injury induced by hyperoxia in neonatal rats and improve the symptoms of bronchopulmonary dysplasia in a dose-dependent manner, possibly by down-regulating the expression of miR-155 and up-regulating the expression of SOCS1.

[Effect of asiaticoside on hyperoxia-induced bronchopulmonary dysplasia in neonatal rats and related mechanism]

OBJECTIVE

To study the protective effect of asiaticoside against hyperoxia-induced bronchopulmonary dysplasia in neonatal rats based on the microRNA-155 (miR-155)/suppressor of cytokine signaling-1 (SOCS1) axis.

METHODS

Neonatal rats were randomly divided into a control group, a model group, a low-dose asiaticoside group (10 mg/kg), a middle-dose asiaticoside group (25 mg/kg), a high-dose asiaticoside group (50 mg/kg), and a budesonide group (1.5 mg/kg), with 12 rats in each group. All rats except those in the control group were exposed to a high concentration of oxygen for 14 days to establish a neonatal rat model of bronchopulmonary dysplasia. The low-, middle-, and high-dose asiaticoside groups were given asiaticoside at different doses by gavage, and those in the budesonide group were given budesonide aerosol treatment. Hematoxylin and eosin staining was used to observe lung tissue development and measure radial alveolar count (RAC) and mean linear intercept (MLI). Superoxide dismutase (SOD) and malondialdehyde (MDA) detection kits were used to measure the levels of SOD and MDA in lung tissue. ELISA was used to measure the serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Quantitative real-time PCR was used to measure the mRNA expression of miR-155 and SOCS1 in lung tissue. Western blotting was used to measure the protein expression of SOCS1 in lung tissue.

RESULTS

Compared with the control group, the model group had the symptoms of bronchopulmonary dysplasia such as a disordered structure of lung tissue, enlargement of alveolar fusion, uneven alveolar septa, enlargement of average alveolar space, and a reduction in alveolar number. The model group also had significant increases in MLI, MDA level in lung tissue, serum levels of IL-6 and TNF-α, and miR-155 level in lung tissue (P<0.05) and significant reductions in RAC, SOD level, and mRNA and protein expression of SOCS1 in lung tissue (P<0.05). Compared with the model group, the low-, middle-, and high-dose asiaticoside groups and the budesonide group had significant improvement in the above symptoms of bronchopulmonary dysplasia, significant reductions in MLI, MDA level in lung tissue, serum levels of IL-6 and TNF-α, and miR-155 level in lung tissue (P<0.05), and significant increases in RAC, SOD level, and mRNA and protein expression of SOCS1 in lung tissue (P<0.05). Asiaticoside improved the above symptoms and indices in a dose-dependent manner. There were no significant differences in the above indices between the high-dose asiaticoside and budesonide groups (P>0.05).

CONCLUSIONS

Asiaticoside can alleviate inflammation injury induced by hyperoxia in neonatal rats and improve the symptoms of bronchopulmonary dysplasia in a dose-dependent manner, possibly by down-regulating the expression of miR-155 and up-regulating the expression of SOCS1.

AEG-1 aggravates inflammation via promoting NALP3 inflammasome formation in murine endometriosis lesions

Endometriosis (EMs) is one of the most common gynaecological diseases in women of childbearing age. Astrocyte elevated gene-1 (AEG-1) is associated with the invasion, migration, apoptosis and prognosis of various cancers. However, the roles of AEG-1 in EMs and its corresponding molecular mechanism are still unknown. In this study, animal models of EMs were established and mice were divided into two groups (n = 10): Sham group and EMs group. The EMs cells were isolated from EMs model. The AEG-1 gene was knocked down by shRNA, while the SOCS1 gene was knocked down by siRNA. Histological changes, AEG-1 expression in tissues and inflammatory factors level were detected by H&E staining, immunohistochemistry and ELISA, respectively. RT-qPCR and western blotting were used to determine the expression level of related proteins. The present study found AEG-1 was up-regulated in the EMs model. Enhanced AEG-1 promoted inflammatory cell infiltration, and elevated the levels of IL-1β, IL-6, and TNF-α in EM group (p < 0.05). Besides, AEG-1 overexpression promoted the expression of NALP3, ASC and Cleaved-caspase-1, while decreased SOCS1 level (p < 0.05). Decrease of SOCS1 further promoted the formation of NALP3 inflammasome. The inhibitory effect of AEG-1 on SOCS1 was weakened after the addition of MG-132 (p < 0.01). Furthermore, silencing AEG-1 alone increased SOCS1 level, decreased the levels of inflammatory cytokines, thereby inhibited the formation of NALP3 inflammasome. All these results demonstrated that AEG-1 aggravated inflammation via promoting NALP3 inflammasome formation in murine endometriosis lesions.

MicroRNA Let-7f-1-3p attenuates smoke-induced apoptosis in bronchial and alveolar epithelial cells in vitro by targeting FOXO1

Bronchial and alveolar epithelial cell apoptosis is a vital step in smoke-induced lung injury. We investigated whether and how microRNA (miRNA) Let-7f-1-3p would regulate smoke-induced apoptosis in bronchial and alveolar epithelial cells. Human small airway epithelial cells (HSAEC) and human pulmonary alveolar epithelial cells (HPAEpiC) were cultured using an air-liquid interface cell culture system. These cells were treated with Let-7f-1-3p agomir or antagomir for 24 h before smoke exposure or sham operation, after which the cells were rinsed and cultured for 24 h before cell viability, apoptosis, cytolysis, Caspase-9/8/3 activity assays, quantitative real-time polymerase chain reaction and Western blot. Bioinformatic and luciferase reporter assays were performed to predict or verify the target gene of Let-7f-1-3p. We found that smoke exposure significantly reduced Let-7f-1-3p expression level in HSAEC and HPAEpiC. Let-7f-1-3p agomir significantly attenuated cell apoptosis, cytolysis and Caspase-3, -8 and -9 activation while rescuing cell viability of smoke-exposed HSAEC and HPAEpiC. Let-7f-1-3p agomir downregulated tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), Fas ligand (FasL) and B-cell lymphoma-2 (Bcl2)-like protein 11 (Bim) protein level in HSAEC and HPAEpiC. Forkhead box-O1 (FOXO1) was verified as a putative regulatory target of Let-7f-1-3p. Smoke exposure increased FOXO1 mRNA and protein level in HSAEC and HPAEpiC, which was attenuated by Let-7f-1-3p agomir treatment. FOXO1 inhibition by small-molecule drug partially attenuated the increase in smoke-exposed HSAEC and HPAEpiC apoptosis, cytolysis and the decrease in cell viability caused by Let-7f-1-3p antagomir treatment. We concluded Let-7f-1-3p attenuated smoke-induced apoptosis in HSAEC and HPAEpiC by targeting FOXO1.

Identification of miRNA-rich vesicles in bronchoalveolar lavage fluid: Insights into the function and heterogeneity of extracellular vesicles

Despite emerging interest in the role of extracellular vesicle (EV)-containing microRNAs (EV-miRNAs), the existence of functional EV-miRNAs under patho-physiological conditions has been viewed with skepticism. Due to the heterogenicity of EVs, several barriers related to EV-miRNA research are to be explored before the in vivo function of EV-miRNAs can be thoroughly delineated. For example, it has been reported that far less than one copy of a given miRNA can be detected per exosome. In this study, we demonstrated that miRNA-rich-EVs exist and can be consistently isolated using differential centrifugation & density-gradient fractionation from bronchoalveolar lavage fluid (BALF) in vivo. The absolute number of this 'miRNA-rich'-EV population is only about 7.05 × 10⁹ per mouse (6% of total EVs). However, the RNA amount detected in this population of EVs represents approximately 39% of the total EV RNAs in the BALF. In contrast, the remaining populations of BALF EVs (76% of total EVs) contain extremely low concentrations of RNAs and miRNAs. The miRNA-rich-EVs in BALF are likely derived from alveolar epithelial type-I cells (ATIs). Notably, caveolin-1, a lipid raft protein, is exclusively detected in the miRNA-rich-EVs, suggesting the lipid raft protein as a biomarker of EV-miRNA enrichment. We further demonstrated that miRNAs contained in the ATI-EVs are actively delivered into alveolar macrophages, subsequently promoting inflammasome activation, neutrophil recruitment, and M1-macrophage polarization in response to P. aeruginosa pneumonia in vitro and in vivo. Collectively, we are the first to identify and characterize the miRNA-rich-EVs in BALF. These miRNA-rich EVs endorse pro-inflammatory responses in bacterial lung infection. Our study provides a novel insight into the development of biomarkers, therapeutic strategies and underlying mechanisms for lung pathology.