The Modulation of Regulatory T Cells via HMGB1/PTEN/β-Catenin Axis in LPS Induced Acute Lung Injury

Regulatory T Cells in Acute Respiratory Distress Syndrome: Current Status and Potential for Future Immunotherapies

This Clinical Focus Review aims to comprehensively assess current knowledge regarding the biology of Tregs and their role in COVID-19–associated and nonassociated ARDS, focusing on their involvement during the acute and resolution phases of the disease. The authors discuss the potential of Treg-based cell therapies and drugs targeting Tregs as therapeutic strategies in ARDS.

Regulation of YAP translocation by myeloid Pten deficiency alleviates acute lung injury via inhibition of oxidative stress and inflammation

BACKGROUND

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is intricately involved in modulating the inflammatory response in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Nevertheless, the myeloid PTEN governing Hippo-YAP pathway mediated oxidative stress and inflammation in lipopolysaccharide (LPS)-induced ALI remains to be elucidate.

METHODS

The floxed Pten (PtenFL/FL) and myeloid-specific Pten knockout (PtenM-KO) mice were intratracheal instill LPS (5 mg/kg) to establish ALI, then Yap siRNA mix with the mannose-conjugated polymers was used to knockdown endogenous macrophage YAP in some PtenM-KO mice before LPS challenged. The bone marrow-derived macrophages (BMMs) from PtenFL/FL and PtenM-KO mice were obtained, and BMMs were transfected with CRISPR/Cas9-mediated glycogen synthase kinase 3 Beta (GSK3β) knockout (KO) or Yes-associated protein (YAP) KO vector subjected to LPS (100 ng/ml) challenged or then cocultured with MLE12 cells.

RESULTS

Here, our findings demonstrate that myeloid-specific PTEN deficiency exerts a protective against LPS-induced oxidative stress and inflammation dysregulated in ALI model. Moreover, ablation of the PTEN-YAP axis in macrophages results in reduced nuclear factor-E2-related factor-2 (NRF2) expression, a decrease in antioxidant gene expression, augmented levels of free radicals, lipid and protein peroxidation, heightened generation of pro-inflammatory cytokines, ultimately leading to increased apoptosis in MLE12 cells. Mechanistically, it is noteworthy that the deletion of myeloid PTEN promotes YAP translocation and regulates NRF2 expression, alleviating LPS-induced ALI via the inhibition of GSK3β and MST1 binding.

CONCLUSIONS

Our study underscores the crucial role of the myeloid PTEN-YAP-NRF2 axis in governing oxidative stress and inflammation dysregulated in ALI, indicating its potential as a therapeutic target for ALI.

Identification of qualitative characteristics of immunosuppression in sepsis based on immune-related genes and immune infiltration features

Objective

Sepsis is linked to high morbidity and mortality rates. Consequently, early diagnosis is crucial for proper treatment, reducing hospitalization, and mortality rates. Additionally, over one-fifth of sepsis patients still face a risk of death. Hence, early diagnosis, and effective treatment play pivotal roles in enhancing the prognosis of patients with sepsis.

Method

The study analyzed whole blood data obtained from patients with sepsis and control samples sourced from three datasets (GSE57065, GSE69528, and GSE28750). Commonly dysregulated immune-related genes (IRGs) among these three datasets were identified. The differential characteristics of these common IRGs in the sepsis and control samples were assessed using the REO-based algorithm. Based on these differential characteristics, samples from eight Gene Expression Omnibus (GEO) databases (GSE57065, GSE69528, GSE28750, GSE65682, GSE69063, GSE95233, GSE131761, and GSE154918), along with three ArrayExpress databases (E-MTAB-4421, E-MTAB-4451, and E-MTAB-7581), were categorized and scored. The effectiveness of these differential characteristics in distinguishing sepsis samples from control samples was evaluated using the AUC value derived from the receiver operating characteristic curve (ROC) curve. Furthermore, the expression of IRGs was validated in peripheral blood samples obtained from patients with sepsis through qRT-PCR.

Results

Among the three training datasets, a total of 84 common dysregulated immune-related genes (IRGs) were identified. Utilizing a within-sample relative expression ordering (REOs)-based algorithm to analyze these common IRGs, differential characteristics were observed in three reverse stable pairs (ELANE-RORA, IL18RAP-CD247, and IL1R1-CD28). In the eight GEO datasets, the expression of ELANE, IL18RAP, and IL1R1 demonstrated significant upregulation, while RORA, CD247, and CD28 expression exhibited notable downregulation during sepsis. These three pairs of immune-related marker genes displayed accuracies of 95.89% and 97.99% in distinguishing sepsis samples among the eight GEO datasets and the three independent ArrayExpress datasets, respectively. The area under the receiver operating characteristic curve ranged from 0.81 to 1.0. Additionally, among these three immune-related marker gene pairs, mRNA expression levels of ELANE and IL1R1 were upregulated, whereas the levels of CD247 and CD28 mRNA were downregulated in blood samples from patients with sepsis compared to normal controls.

Conclusion

These three immune-related marker gene pairs exhibit high predictive performance for blood samples from patients with sepsis. They hold potential as valuable auxiliary clinical blood screening tools for sepsis.

Th17/Treg balance: the bloom and wane in the pathophysiology of sepsis

Sepsis is a multi-organ dysfunction characterized by an unregulated host response to infection. It is associated with high morbidity, rapid disease progression, and high mortality. Current therapies mainly focus on symptomatic treatment, such as blood volume supplementation and antibiotic use, but their effectiveness is limited. Th17/Treg balance, based on its inflammatory property, plays a crucial role in determining the direction of the inflammatory response and the regression of organ damage in sepsis patients. This review provides a summary of the changes in T-helper (Th) 17 cell and regulatory T (Treg) cell differentiation and function during sepsis, the heterogeneity of Th17/Treg balance in the inflammatory response, and the relationship between Th17/Treg balance and organ damage. Th17/Treg balance exerts significant control over the bloom and wanes in host inflammatory response throughout sepsis.

Identification of genetic profile and biomarkers involved in acute respiratory distress syndrome

PURPOSE

The purpose of this study was to profile genetic causal factors of acute respiratory distress syndrome (ARDS) and early predict patients at high ARDS risk.

METHODS

We performed a phenome-wide Mendelian Randomization analysis through summary statistics of an ARDS genome-wide association study (1250 cases and 1583 controls of European ancestry) and 33,150 traits. Transcriptomic data from human blood and lung tissues of a preclinical mouse model were used to validate biomarkers, which were further used to construct a prediction model and nomogram.

RESULTS

A total of 1736 traits, including 1223 blood RNA, 159 plasma proteins, and 354 non-gene phenotypes (classified by Biochemistry, Anthropometry, Disease, Nutrition and Habit, Immunology, and Treatment), exhibited a potentially causal relationship with ARDS development, which were accessible through a user-friendly interface platform called CARDS (Causal traits for Acute Respiratory Distress Syndrome). Regarding candidate blood RNA, four genes were validated, namely TMEM176B, SLC2A5, CDC45, and VSIG8, showing differential expression in blood of ARDS patients compared to controls, as well as dynamic expression in mouse lung tissues. Importantly, the addition of four blood genes and five immune cell proportions significantly improved the prediction performance of ARDS development, with 0.791 of the area under the curve from receiver-operator characteristic, compared to 0.725 for the basic model consisting of Acute Physiology and Chronic Health Evaluation (APACHE) III Score, sex, body mass index, bacteremia, and sepsis. A model-based nomogram was also developed for the clinical practice.

CONCLUSION

This study identifies a wide range of ARDS relevant factors and develops a promising prediction model, enhancing early clinical management and intervention for ARDS development.

CircFLNA/miR-214 modulates regulatory T cells by regulating PD-1 in acute lung injury induced by sepsis

Sepsis-induced acute respiratory distress syndrome (ARDS) remains a major complication of death from bacterial infection. Regulatory T cells (Tregs) are important regulators in addressing lung injury. Considering the extensive research of circular RNAs (circRNAs), the role of circRNA in Treg modulation during ARDS remains unclear. In this study, patients with sepsis-induced ARDS along with non-ARDS controls were obtained, and bronchoalveolar lavage fluid (BALF) was collected as clinical samples. Additionally, cecal ligation and puncture (CLP) was performed to construct a septic ARDS model, and lung tissues as well as peripheral blood were collected. mRNA expressions were measured by RT-qPCR. ELISA was carried out to measure the concentration of inflammatory factors. A combination of online bioinformatics, dual-luciferase reporter, and RND pull-down assays was performed to verify interactions between microRNA (miRNA) and circRNA/mRNA. Tregs were measured by flow cytometry. Our data suggested that circFLNA was aberrantly elevated in ARDS, and depletion of circFLNA upregulated CD4+CD25+Foxp3+ Tregs and decreased inflammatory response. Additionally, miR-214-5p which binds with circFLNA, reversed circFLNA-induced effects in ARDS. Programmed cell death protein 1 (PD-1) is a downstream target gene of miR-214-5p, and abrogated the effects of miR-214-5p on regulating CD4+CD25+Foxp3+ Tregs and inflammatory response. In a word, circFLNA/miR-214-5p/PD-1 signaling is a novel pathway that modulates Tregs in ARDS.

HMGB1/PTEN/PI3K axis participates in the peripheral immune cell differentiation in two representative TCM syndromes of chronic hepatitis B patients

Liver depression and spleen deficiency syndrome (LDSDS) and spleen-gastric damp-heat syndrome (SGDHS) are two major traditional Chinese medicine syndromes observed in chronic hepatitis B (CHB). Both syndromes exhibit significant differences in the pathogenesis and prognosis, and are closely related to the immune system. However, the underlying mechanisms are largely unknown. This study aimed to explore the immunoregulatory mechanisms of the two syndromes and promote the differentiation precision between the two syndromes. Thirty-six patients with CHB (18 LDSDS patients and 18 SGDHS patients) and 14 healthy controls were recruited into this study and blood was collected from all the subjects for testing. We studied the contents of T lymphocytes by flow cytometry and the expression levels of HMGB1/PTEN/PI3K axis proteins by enzyme-linked immunosorbent assay (Elisa). Protein-protein interaction (PPI) networks among HMGB1/PTEN/PI3K axis were constructed for functional enrichment. The correlations between T lymphocytes and proteins were analyzed by constructing multiple regression equations. The results revealed that the CD8+ T cells level in the two syndromes were lower than that in healthy controls, and the levels of Th17, Treg cells, and HMGB1, PI3K, PDK1, Akt were higher than those of the healthy controls (p < 0.05). Moreover, the levels of CD4+ T, Th17 cells, and HMGB1, PTEN, PI3K in LDSDS were higher than SGDHS (p < 0.05). PPI network indicated that HMGB1/PTEN/PI3K axis participated in T cell activation and liver pathology. Our results revealed that HMGB1/PTEN/PI3K axis may play an important role in regulating the formation of peripheral immune differences between the two syndromes. CD4+ T and Th17 are two representative immune cells that may serve as potential biological markers for LDSDS and SGDHS in CHB.

Mechanism of exosomes from adipose-derived mesenchymal stem cells on sepsis-induced acute lung injury by promoting TGF-β secretion in macrophages

OBJECTIVE

Acute lung injury (ALI) caused by sepsis is a life-threatening condition characterized by uncontrollable lung inflammation. The current study sought to investigate the mechanism of adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) in attenuating sepsis-induced ALI through TGF-β secretion in macrophages.

METHODS

Adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) were extracted from ADMSCs and identified. Septic ALI mouse models were established via cecal ligation and puncture (CLP), followed by administration of ADMSC-Exos or sh-TGF-β lentiviral vector. Mouse macrophages (cell line RAW 264.7) were treated with lipopolysaccharide (LPS), co-cultured with Exos and splenic T cells, and transfected with TGF-β siRNA. The lung injury of CLP mice was evaluated, and levels of inflammatory indicators and macrophage markers were measured. The localization of macrophage markers and TGF-β was determined, and the level of TGF-β in lung tissues was measured. The effect of TGF-β knockdown on sepsis-induced ALI in CLP mice was evaluated, and the percentages of CD4+CD25+Foxp3+ Tregs in mononuclear cells/macrophages and Foxp3 levels in lung tissues/co-cultured splenic T cells were examined.

RESULTS

ADMSC-Exos were found to alleviate sepsis-induced ALI, inhibit inflammatory responses, and induce macrophages to secrete TGF-β in CLP mice. TGF-β silencing reversed the alleviating effect of ADMSC-Exos on sepsis-induced ALI. ADMSC-Exos also increased the number of Tregs in the spleen of CLP mice and promoted M2 polarization and TGF-β secretion in LPS-induced macrophages. After knockdown of TGF-β in macrophages in the co-culture system, the number of Tregs decreased, suggesting that ADMSC-Exos increased the Treg number by promoting macrophages to secrete TGF-β.

CONCLUSION

Our findings suggest ADMSC-Exos can effectively alleviate sepsis-induced ALI in CLP mice by promoting TGF-β secretion in macrophages.

Secretome of EMSCs neutralizes LPS‑induced acute lung injury via aerosol administration

Ectodermal mesenchymal stem cells (EMSCs) are cells harvested from the stem cell niche (nasal mucosa) with high therapeutic potential. To the best of our knowledge, however, the anti‑inflammatory properties of these neural crest‑derived EMSCs have been rarely reported. The present study aimed to explore the effects of aerosolized EMSC‑Secretome (EMSC‑Sec) and clarify underlying mechanisms in treating acute lung injury (ALI). EMSCs were isolated by adherent method and identified by immunofluorescence staining. EMSC‑Sec was collected and evaluated using western blotting, BCA and ELISA tests. Then, mouse lung epithelial cells (MLE‑12) were used to mimic inflammatory stimulation with lipopolysaccharide (LPS). After developing an ALI model through intraperitoneal injection of LPS, mice were treated with an EMSC‑Sec spray. The lung in each group underwent an observation and measurement to preliminarily assess the extent of damage. H&E staining, immunohistochemical staining, immunofluorescence and western‑blotting were utilized to further access the impacts of EMSC‑Sec. The results showed that EMSC‑Sec had great anti‑inflammatory potential and was highly successful in vitro and in vivo. EMSC‑Sec mitigated LPS‑induced ALI with low inflammatory cell inflation and mild damage. EMSC‑Sec could regulate inflammation via the NF‑κB(p50/p65)/NLRP3 pathway. Overall, the present study demonstrated that EMSC‑Sec regulated inflammation, hoping to provide a novel strategy for ALI treatment.

Qi-Dong-Huo-Xue-Yin balances the immune microenvironment to protect against LPS induced acute lung injury

COVID-19 induces acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) and leads to severe immunological changes that threatens the lives of COVID-19 victims. Studies have shown that both the regulatory T cells and macrophages were deranged in COVID-19-induced ALI. Herbal drugs have long been utilized to adjust the immune microenvironment in ALI. However, the underlying mechanisms of herbal drug mediated ALI protection are largely unknown. This study aims to understand the cellular mechanism of a traditional Chinese medicine, Qi-Dong-Huo-Xue-Yin (QD), in protecting against LPS induced acute lung injury in mouse models. Our data showed that QD intrinsically promotes Foxp3 transcription via promoting acetylation of the Foxp3 promoter in CD4⁺ T cells and consequently facilitates CD4⁺CD25⁺Foxp3⁺ Tregs development. Extrinsically, QD stabilized β-catenin in macrophages to expedite CD4⁺CD25⁺Foxp3⁺ Tregs development and modulated peripheral blood cytokines. Taken together, our results illustrate that QD promotes CD4⁺CD25⁺Foxp3⁺ Tregs development via intrinsic and extrinsic pathways and balanced cytokines within the lungs to protect against LPS induced ALI. This study suggests a potential application of QD in ALI related diseases.

Identification of potential biomarkers and pathways for sepsis using RNA sequencing technology and bioinformatic analysis

Long non-coding RNAs (lncRNAs) has been proven by many to play a crucial part in the process of sepsis. To obtain a better understanding of sepsis, the molecular biomarkers associated with it, and its possible pathogenesis, we obtained data from RNA-sequencing analysis using serum from three sepsis patients and three healthy controls (HCs). Using edgeR (one of the Bioconductor software package), we identified 1118 differentially expressed mRNAs (DEmRNAs) and 1394 differentially expressed long noncoding RNAs (DElncRNAs) between sepsis patients and HCs. We identified the biological functions of these disordered genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses. The GO analysis showed that the homophilic cell adhesion via plasma membrane adhesion molecules was the most significantly enriched category. The KEGG signaling pathway analysis indicated that the differentially expressed genes (DEGs) were most significantly enriched in retrograde endocannabinoid signaling. Using STRING, a protein-protein interaction network was also created, and Cytohubba was used to determine the top 10 hub genes. To examine the relationship between the hub genes and sepsis, we examined three datasets relevant to sepsis that were found in the gene expression omnibus (GEO) database. PTEN and HIST2H2BE were recognized as hub gene in both GSE4607, GSE26378, and GSE9692 datasets. The receiver operating characteristic (ROC) curves indicate that PTEN and HIST2H2BE have good diagnostic value for sepsis. In conclusion, this two hub genes may be biomarkers for the early diagnosis of sepsis, our findings should deepen our understanding of the pathogenesis of sepsis.

Mechanism of TLR4 mediated immune effect in transfusion-induced acute lung injury based on Slit2/Robo4 signaling pathway

BACKGROUND

Transfusion-related acute lung injury (TRALI) is the infusion of blood or blood system.

OBJECTIVE

To explore the mechanism of TLR4-mediated T cell immune effect in TRALI.

METHODS

In this animal study, a mouse model of LPS-induced TRALI was established. Sixty adult C57/BL6 mice (wild-type, WT) were randomly divided into 5 groups: 1) normal WT type, 2) LPS control group of WT type lipopolysaccharide, 3) WT type TRALI group (LPS + MHC-I mAb), 4) (TLR4 antibody) lipopolysaccharide LPS control group, 5) (TLR4 antibody) TRALI group (LPS + MHC-I mAb). Mice were injected with LPS (0.1 mg/kg) and MHC-I mAb (2 mg/kg) into the tail vein. H&E staining was performed to detect pathological features. The myeloperoxidase (MPO) activity and the level of inflammatory cytokines in lung tissue homogenate supernatant were measured. Blood, spleen single-cell suspension, and bronchoalveolar lavage fluid were collected to detect the ratio of Treg and Th17 cells by flow cytometry. RT-PCR and WB were used to detect mRNA or protein expression.

RESULTS

TLR4 mAb treatment alleviated the pathogenesis of LPS-induced TRALI in vivo, the MPO activity, and the level of proinflammatory factors in lung tissues. TLR4 exerted its function by changing of Treg/Th17 ratio via the SLIT2/ROBO4 signaling pathway and downregulating CDH5 and SETSIP.

CONCLUSION

TLR4 mediates immune response in the LPS-induced TRALI model through the SLIT2/ROBO4 signaling pathway.

Regulatory T cell and macrophage crosstalk in acute lung injury: future perspectives

Acute lung injury (ALI) describes the injury to endothelial cells in the lungs and associated vessels due to various factors. Furthermore, ALI accompanied by inflammation and thrombosis has been reported as a common complication of SARS-COV-2 infection. It is widely accepted that inflammation and the cytokine storm are main causes of ALI. Two classical anti-inflammatory cell types, regulatory T cells (Tregs) and M2 macrophages, are theoretically capable of resisting uncontrolled inflammation. Recent studies have indicated possible crosstalk between Tregs and macrophages involving their mutual activation. In this review, we discuss the current findings related to ALI pathogenesis and the role of Tregs and macrophages. In particular, we review the molecular mechanisms underlying the crosstalk between Tregs and macrophages in ALI pathogenesis. Understanding the role of Tregs and macrophages will provide the potential targets for treating ALI.

The role of lung macrophages in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and diffuse inflammatory lung injury in a short time, one of the common severe manifestations of the respiratory system that endangers human life and health. As an innate immune cell, macrophages play a key role in the inflammatory response. For a long time, the role of pulmonary macrophages in ARDS has tended to revolve around the polarization of M1/M2. However, with the development of single-cell RNA sequencing, fate mapping, metabolomics, and other new technologies, a deeper understanding of the development process, classification, and function of macrophages in the lung are acquired. Here, we discuss the function of pulmonary macrophages in ARDS from the two dimensions of anatomical location and cell origin and describe the effects of cell metabolism and intercellular interaction on the function of macrophages. Besides, we explore the treatments for targeting macrophages, such as enhancing macrophage phagocytosis, regulating macrophage recruitment, and macrophage death. Considering the differences in responsiveness of different research groups to these treatments and the tremendous dynamic changes in the gene expression of monocyte/macrophage, we discussed the possibility of characterizing the gene expression of monocyte/macrophage as the biomarkers. We hope that this review will provide new insight into pulmonary macrophage function and therapeutic targets of ARDS.

Transforming growth factor-β receptor type 2 is required for heparin-binding protein-induced acute lung injury and vascular leakage for transforming growth factor-β/Smad/Rho signaling pathway activation

Heparin-binding protein (HBP), as a granule protein secreted by polymorphonuclear neutrophils, participates in the pathophysiological process of sepsis. It has been reported that HBP is a biomarker of sepsis related to the severity of septic shock and organ dysfunction. HBP binds to vascular endothelial cells as a primary target site. However, it is still unclear whether HBP-binding protein receptors exist on the surface of endothelial cells. The effect of HBP on vascular permeability in sepsis and its mechanism needs to be explored. We conducted in vivo and in vitro studies and demonstrated that HBP binds to transforming growth factor-β receptor type 2 (TGF-β-R2) as a ligand. Glutathione S-transferase pull-down analysis revealed that HBP mainly interacts with the extracellular domain of TGF-β-R2. HBP induces acute lung injury and vascular leakage via activation of the TGF-β/SMAD2/3 signaling pathway. A permeability assay suggested that TGF-β-R2 is necessary for HBP-induced increased permeability. We also defined the role of HBP and its potential membrane receptor TGF-β-R2 in the blood-gas barrier in the pathogenesis of HBP-related acute lung injury.

Potential mouse models of coronavirus-related immune injury

Basic research for prevention and treatment of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues worldwide. In particular, multiple newly reported cases of autoimmune-related diseases after COVID-19 require further research on coronavirus-related immune injury. However, owing to the strong infectivity of SARS-CoV-2 and the high mortality rate, it is difficult to perform relevant research in humans. Here, we reviewed animal models, specifically mice with coronavirus-related immune disorders and immune damage, considering aspects of coronavirus replacement, viral modification, spike protein, and gene fragments. The evaluation of mouse models of coronavirus-related immune injury may help establish a standardised animal model that could be employed in various areas of research, such as disease occurrence and development processes, vaccine effectiveness assessment, and treatments for coronavirus-related immune disorders. COVID-19 is a complex disease and animal models cannot comprehensively summarise the disease process. The application of genetic technology may change this status.

PTEN: An Emerging Potential Target for Therapeutic Intervention in Respiratory Diseases

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a potent tumor suppressor that regulates several key cellular processes, including proliferation, survival, genomic integrity, migration, and invasion, via PI3K-dependent and independent mechanisms. A subtle decrease in PTEN levels or catalytic activity is implicated not only in cancer but also in a wide spectrum of other diseases, including various respiratory diseases. A systemic overview of the advances in the molecular and cellular mechanisms of PTEN involved in the initiation and progression of respiratory diseases may offer novel targets for the development of effective therapeutics for the treatment of respiratory diseases. In the present review, we highlight the novel findings emerging from current research on the role of PTEN expression and regulation in airway pathological conditions such as asthma/allergic airway inflammation, pulmonary hypertension (PAH), chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and other acute lung injuries (ALI). Moreover, we discuss the clinical implications of PTEN alteration and recently suggested therapeutic possibilities for restoration of PTEN expression and function in respiratory diseases.

Morin Inhibits Dox-Induced Vascular Inflammation By Regulating PTEN/AKT/NF-κB Pathway

The side effects of doxorubicin (Dox) may influence the long-term survival of patients with malignancies. Therefore, it is necessary to clarify the mechanisms generating these side effects induced by Dox and identify effective therapeutic strategies. Here, we found that interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-alpha (TNF-α) levels were significantly increased in vascular tissues of Dox-treated mice and Dox-treated vascular smooth muscle cells (VSMCs). Furthermore, we revealed that Dox downregulated the phosphatase and tension homology deleted on chromosome 10 (PTEN) level while upregulated p-AKT and p65 level in VSMCs in vitro. Overexpression of PTEN in VSMCs partly reversed Dox-induced inflammation. Importantly, we demonstrated that Morin could inhibit Dox-induced inflammation by facilitating an increase of PTEN, thus inhibiting the activation of protein kinase B (AKT)/nuclear factor kappa B (NF-κB)/pathway. Additionally, we showed that Morin could reduce the miR-188-5p level, which was increased in Dox-treated VSMCs. Inhibition of miR-188-5p suppressed Dox-induced vascular inflammation in vitro. In conclusion, Morin reduced the Dox-induced vascular inflammatory by moderating the miR-188-5p/PTEN/AKT/NF-κB pathway, indicating that Morin might be a therapeutic agent for overcoming the Dox-induced vascular inflammation.

Extracellular HMGB1 Impairs Macrophage-Mediated Efferocytosis by Suppressing the Rab43-Controlled Cell Surface Transport of CD91

High-mobility group box 1 (HMGB1) protein can impair phagocyte function by suppressing the macrophage-mediated clearance of apoptotic cells (ACs), thereby delaying inflammation resolution in the lungs and allowing the progression of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). However, the precise mechanism underlying this HMGB1-mediated inhibition of efferocytosis remains unknown. The aim of this study was to determine the effect of HMGB1 on macrophage-mediated efferocytosis. We discovered that HMGB1 prevented efferocytosis by bone marrow-derived macrophages (BMDMs) and suppressed the expression of Ras-related GTP-binding protein 43 (Rab43), a member of the Ras-associated binding (Rab) family. The downregulation of Rab43 expression resulted in impaired clearance of apoptotic thymocytes by BMDMs. Subsequent analysis of HMGB1-treated and Rab43-deficient BMDMs revealed the inhibited transport of cluster of differentiation 91 (CD91), a phagocyte recognition receptor, from the cytoplasm to the cell surface. Notably, Rab43 directly interacted with CD91 to mediate its intercellular trafficking. Furthermore, Rab43 knockout delayed the inflammation resolution and aggravated the lung tissue damage in mice with ALI. Therefore, our results provide evidence that HMGB1 impairs macrophage-mediated efferocytosis and delays inflammation resolution by suppressing the Rab43-regulated anterograde transport of CD91, suggesting that the restoration of Rab43 levels is a promising strategy for attenuating ALI and ARDS in humans.

Research Progress in the Pharmacological Activities, Toxicities, and Pharmacokinetics of Sophoridine and Its Derivatives

Sophoridine is a natural quinolizidine alkaloid and a bioactive ingredient that can be isolated and identified from certain herbs, including Sophora flavescens Alt, Sophora alopecuroides L, and Sophora viciifolia Hance. In recent years, this quinolizidine alkaloid has gained widespread attention because of its unique structure and minimal side effects. Modern pharmacological investigations have uncovered sophoridine's multiple wide range biological activities, such as anti-cancer, anti-inflammatory, anti-viral, anti-arrhythmia, and analgesic functions, among others. These pharmacological activities and beneficial effects point to sophoridine as a strong potential therapeutic candidate for the treatment of various diseases, including several cancer types, hepatitis B virus, enterovirus 71, coxsackievirus B3, cerebral edema, cancer pain, heart failure, acute myocardial ischemia, arrhythmia, inflammation, acute lung injury, and osteoporosis. The data showed that sophoridine had adverse reactions, including hepatotoxicity and neurotoxicity. Additionally, analyses of sophoridine's safety, bioavailability, and pharmacokinetic parameters in animal models of research have been limited, especially in the clinic, as have been investigations on its structure-activity relationship. In this article, we comprehensively summarize the biological activities, toxicity, and pharmacokinetic characteristics of sophoridine and its derivatives, as currently reported in publications, as we attempt to provide an overall perspective on sophoridine analogs and the prospects of its application clinically.

Targeting HMGB1 for the treatment of sepsis and sepsis-induced organ injury

High mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that is present in almost all cells and regulates the activity of innate immune responses in both intracellular and extracellular settings. Current evidence suggests that HMGB1 plays a pivotal role in human pathological and pathophysiological processes such as the inflammatory response, immune reactions, cell migration, aging, and cell death. Sepsis is a systemic inflammatory response syndrome (SIRS) that occurs in hosts in response to microbial infections with a proven or suspected infectious etiology and is the leading cause of death in intensive care units worldwide, particularly in the aging population. Dysregulated systemic inflammation is a classic characteristic of sepsis, and suppression of HMGB1 may ameliorate inflammation and improve patient outcomes. Here, we focus on the latest breakthroughs regarding the roles of HMGB1 in sepsis and sepsis-related organ injury, the ways by which HMGB1 are released, and the signaling pathways and therapeutics associated with HMGB1. This review highlights recent advances related to HMGB1: the regulation of HMBG1 might be helpful for both basic research and drug development for the treatment of sepsis and sepsis-related organ injury.

Regulatory T Cells: Angels or Demons in the Pathophysiology of Sepsis?

Sepsis is a syndrome characterized by life-threatening organ dysfunction caused by the dysregulated host response to an infection. Sepsis, especially septic shock and multiple organ dysfunction is a medical emergency associated with high morbidity, high mortality, and prolonged after-effects. Over the past 20 years, regulatory T cells (Tregs) have been a key topic of focus in all stages of sepsis research. Tregs play a controversial role in sepsis based on their heterogeneous characteristics, complex organ/tissue-specific patterns in the host, the multi-dimensional heterogeneous syndrome of sepsis, the different types of pathogenic microbiology, and even different types of laboratory research models and clinical research methods. In the context of sepsis, Tregs may be considered both angels and demons. We propose that the symptoms and signs of sepsis can be attenuated by regulating Tregs. This review summarizes the controversial roles and Treg checkpoints in sepsis.

Identification of key immune genes for sepsis-induced ARDS based on bioinformatics analysis

Regarding the extremely high mortality caused by sepsis-induced acute respiratory distress syndrome (ARDS), it is urgent to develop new biomarkers of sepsis-induced ARDS for treatment. Here, 532 differential expression genes (DEGs) related to sepsis and 433 DEGs related to sepsis-induced ARDS were screened in the GSE32707 dataset. Compared with sepsis samples, sepsis ARDS samples showed a higher infiltration of activated memory CD4 T cells and naive B cells, but a relatively lower infiltration of CD8 T cells. The pink and green modules which are significantly associated with sepsis-induced ARDS were then screened through co-expression network analysis. Differentially up-regulated GYPE and aberrantly down-regulated HSPB1, were subsequently found in the pink module of ARDS. CD81 and RPL22, two differentially low-expressed genes peculiar to ARDS, were identified in the green module. The function of CD81 was verified at the cellular level, and it was found that the up-regulation of CD81 in A549 could alleviate the LPS-induced injury of A549 cells. More importantly, the overexpressed CD81 can also increase the content of CD4⁺ CD25⁺ Foxp3⁺ Treg in Jurkat cells, and after the co-culture of overexpressed CD81 Jurkat cells with LPS treatment A549 cells, the LPS-induced lung epithelial cell damage can be improved. Overall, four new plasma biomarker candidates were found in sepsis-induced ARDS, and we verified that CD81 may play critical roles in the biological and immunological processes of sepsis-induced ARDS.

Identifying the mechanism underlying antidepressant-like effects of loganin by network pharmacology in combination with experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Loganin, an iridoid glycoside, is one of the quality control indexes of Cornus officinalis Sieb. et Zucc. Increasing evidence emphasize the important role of inflammation in the pathology of depression, which links depression with other chronic diseases. Loganin prevents inflammatory response in multiple diseases and reverses depressive-like behaviors. However, the mechanisms underlying antidepressant-like effects of loganin for the treatment of inflammation-associated depression are not utterly understood.

AIM OF THE STUDY

The present study was designed to predict the potential targets of loganin against inflammation-associated depression using a network pharmacology approach.

MATERIALS AND METHODS

Pharmmapper and Uniport were used to predict loganin-related targets. Targets of inflammation were identified through GeneCards databases and Online Mendelian Inheritance in Man (OMIM). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to identify the potential mechanism. Finally, qRT-PCR and ELISA were used to confirm the role of loganin on these targets.

RESULTS

There were 15 nodes in the loganin-inflammation-depression intersection targets network. In the network, the degree value of CTNNB1 was above 3. Among top ten pathways identified by KEGG analysis, Th1/Th2 cell differentiation and IL-17 signaling pathways were related with both inflammation and depression. As indicated by qRT-PCR results, loganin increased CTNNB1 mRNA level. Moreover, loganin elevated M2 markers of microglia but decreased M1 markers of microglia against lipopolysaccharide (LPS), indicated by qRT-PCR results and ELISA results.

CONCLUSION

CTNNB1 was the main target of loganin. Loganin alleviated LPS-induced inflammation through inhibiting M1 polarization of microglia. Our results provide a better understanding of loganin-induced antidepressant-like effects for the treatment of inflammation-associated depression.

The contribution of neuropilin-1 in the stability of CD4+ CD25+ regulatory T cells through the TGF-β1/Smads signaling pathway in the presence of lipopolysaccharides

Introduction

This study investigates the synergistic effect of TGF‐β1 and Nrp‐1 on CD4⁺CD25⁺ T_regs' stabilization, and the associated pathways of signal transduction, in vitro models in the presence of LPS.

Materials and Methods

Spleen CD4⁺CD25⁺ T_regs cells of mice models in the presence of LPS, were transfected with an shRNA targeting Nrp‐1, Smad2, or Smad3, may or may not be treated with recombinant TGF‐β1. Followed by subsequent determination of cellular proliferation, rate of apoptosis, observation of the Foxp3, CTLA‐4, and TGF‐β1^m+ expression levels, foxp3‐TSDR methylation, secretion levels of the inhibitory cytokines IL‐10 and TGF‐β1, and Smad2/3 of CD4⁺CD25⁺ T_regs expression.

Results

A remarkable stimulation in CD4⁺CD25⁺ T_regs' stability is noted after administering recombinant TGF‐β1 in the presence of LPS, and promoted cellular viability, increased Foxp3, CTLA‐4, and TGF‐β1^m+ expression, and elevated secretion of IL‐10 and TGF‐β1. This also inhibited the apoptosis and methylation of foxp3‐ TSDR of CD4⁺CD25⁺ T_regs. The shRNA transfection silenced Nrp‐1 and Smad3, but not Smad2, resulting in the suppression of the recombinant TGF‐β1‐mediated effects in the presence of LPS.

Conclusions

According to the results, Nrp‐1 mediates TGF‐β1 to improve the stability of regulatory CD4⁺CD25⁺ T cells and maybe a possible therapeutic target with the ability to improve the CD4⁺CD25⁺ T_regs associated negative immunoregulation that is related to the TGF‐β1/Smads cell signaling during sepsis.

Sirt3 Maintains Microvascular Endothelial Adherens Junction Integrity to Alleviate Sepsis-Induced Lung Inflammation by Modulating the Interaction of VE-Cadherin and β-Catenin

Inflammatory injury is a hallmark of sepsis-induced acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). However, the mechanisms underlying inflammatory injury remain obscure. Here, we developed the novel strategy to suppress lung inflammation through maintaining microvascular endothelial barrier integrity. VE-cadherin is the main adherens junction protein that interacts with β-catenin and forms a complex. We found that lung inflammation was accompanied by decreased VE-cadherin expression and increased β-catenin activity in animal models and human pulmonary microvascular endothelial cells (HPMECs), illuminating the relationship among VE-cadherin/β-catenin complex, microvascular endothelial barrier integrity, and inflammation. Furthermore, we showed that the VE-cadherin/β-catenin complex dissociated upon lung inflammation, while Sirt3 promoted the stability of such a complex. Sirt3 was decreased during lung inflammation in vivo and in vitro. Sirt3 deficiency not only led to the downregulation of VE-cadherin but also enhanced the transcriptional activity of β-catenin that further increased β-catenin target gene MMP-7 expression, thereby promoting inflammatory factor COX-2 expression. Sirt3 overexpression promoted VE-cadherin expression, inhibited β-catenin transcriptional activity, strengthened the stability of the VE-cadherin/β-catenin complex, and suppressed inflammation in HPMECs. Notably, Sirt3 deficiency significantly damaged microvascular endothelial barrier integrity and intensified lung inflammation in animal model. These results demonstrated the role of Sirt3 in modulating microvascular endothelial barrier integrity to inhibit inflammation. Therefore, strategies that aim at enhancing the stability of endothelial VE-cadherin/β-catenin complex are potentially beneficial for preventing sepsis-induced lung inflammation.

lncRNA NEAT1 aggravates sepsis-induced lung injury by regulating the miR-27a/PTEN axis

Sepsis is an acute inflammatory reaction and a cause of acute respiratory distress syndrome (ARDS). In the present study, we explored the roles and underlying mechanism of the lncRNA Nuclear enriched abundant transcript 1 (NEAT1) in ARDS. The expression levels of genes, proteins and pro-inflammatory cytokines in patients with ARDS, LPS-stimulated cells and septic mouse models were quantified using qPCR, western blotting and ELISA assays, respectively. The molecular targeting relationship was validated by conducting a dual-luciferase reporter assay. Cell proliferation was assessed using the Cell Counting Kit-8 (CCK-8) assay. The cell cycle phase was determined by flow cytometry assay. The expression levels of NEAT1 and pro-inflammatory cytokines were higher in patients with ARDS and septic models than in controls. Knockdown of NEAT1 significantly increased cell proliferation and cycle progression and prolonged mouse survival in vitro and in vivo. Mechanistically, miR-27a was identified as a downstream target of NEAT1 and directly inhibited PTEN expression. Further rescue experiments revealed that inhibition of miR-27a impeded the promoting effects of NEAT1 silence on cell proliferation and cycle progression, whereas inhibition of PTEN markedly weakened the inhibitory effects of NEAT1 overexpression on cell proliferation and cycle progression. Altogether, our study revealed that NEAT1 plays a promoting role in the progression of ARDS via the NEAT1/miR-27a/PTEN regulatory network, providing new insight into the pathologic mechanism behind ARDS.

Bone marrow-mesenchymal stem cell-derived exosomal microRNA-141 targets PTEN and activates β-catenin to alleviate myocardial injury in septic mice

BACKGROUND

Mesenchymal stem cells (MSCs) and their derived exosomes have shown potentials in the control of myocardial dysfunction. This study aimed to reveal the function of bone marrow (BM)-MSC-derived exosomes in sepsis-induced myocardial injury and the molecular mechanism.

METHODS

BM-MSC-derived exosomes were obtained and identified. A mouse model with sepsis was induced by cecalligation puncture (CLP) and treated with exosomes. The myocardial function of mice, the production of creatine kinase MB (CK-MB) and lactate dehydrogenase (LDH) in serum, the phosphorylation of a key myocardial contractility-related protein phospholamban (PLB), and the pathological changes in the myocardial tissues were examined. A microRNA (miRNA) microarray analysis was performed to examine the candidate miRNAs carried by the exosomes. Rescue experiments were conducted to validate the involvement of miR-141.

RESULTS

CLP treatment led to sepsis and notably reduced the myocardial function in mice. Further treatment of BM-MSC-derived exosomes alleviated the CLP-induced myocardial impairment, production of CK-MB and LDH, and inflammatory infiltration and cell apoptosis in mouse myocardial tissues, and restored the PLB phosphorylation. miR-141 was the most upregulated miRNA in the myocardial tissues after exosome treatment. Downregulation of miR-141 blocked the myocardium-protective functions of the exosomes. miR-141 was found to bind to and suppress PTEN expression, which further enhanced the activity of β-catenin.

CONCLUSION

This study suggested that BM-MSC derived exosomes ameliorates myocardial injury in septic mice through conveying miRNA-141 and regulating the PTEN/β-catenin axis, and exosomes may serve as promising tools for the management of myocardial injury induced by sepsis or other factors.

Baicalin Magnesium Salt Attenuates Lipopolysaccharide-Induced Acute Lung Injury via Inhibiting of TLR4/NF-κB Signaling Pathway

Baicalin (BA) magnesium salt (BA-Mg) is a good water-soluble ingredient extracted from Scutellaria baicalensis Georgi, a commonly used traditional Chinese medicine. This study is aimed at investigating whether BA-Mg could exert a better protective effect on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and illuminate the underlying mechanisms in vivo and in vitro. Mice were intraperitoneally administrated with equimolar BA-Mg, BA, and MgSO₄ before LPS inducing ALI. Lung tissues and bronchoalveolar lavage fluid were collected for lung wet/dry ratio, histological examinations, cell counts, and biochemical analyses at 48 h post-LPS exposure. Meanwhile, the protein expressions of TLR4/NF-κB signaling pathway and proinflammatory cytokines in lung tissues and lung bronchial epithelial cells (BEAS-2B) were detected. The results showed BA-Mg pronouncedly ameliorated LPS-induced inflammatory response and histopathological damages, elevated antioxidant enzyme activity (SOD), and downregulated myeloperoxidase (MPO) and malonaldehyde (MDA) levels through the inhibition of TLR4/NF-κB signaling pathway activation. Moreover, the effect of BA-Mg was significantly better than that of BA and MgSO₄ in ameliorating symptoms. Overall, BA-Mg can effectively relieve inflammatory response and oxidative stress triggered by LPS, indicating it may be a potential therapeutic candidate for treating ALI.

Exosomes Derived From Alveolar Epithelial Cells Promote Alveolar Macrophage Activation Mediated by miR-92a-3p in Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) induced by sepsis is characterized by disruption of the epithelial barrier and activation of alveolar macrophages (AMs), which leads to uncontrolled pulmonary inflammation. However, effective treatments for ALI are unavailable. The exact mechanism by which the initial mediator of alveolar epithelial cells (AECs) induces inflammation remains elusive. Here we investigated the roles of AEC-derived exosomes in AM activation and sepsis-induced ALI in vivo and in vitro. Cecal ligation and puncture (CLP) was utilized to establish septic lung injury model in rats. The effect of exosomal inhibition by intratracheal GW4869 administration on lung injury was investigated. To assess the effects of AEC-derived exosomes on ALI, we treated the rat alveolar epithelial cell line RLE-6TN with LPS to induce cell damage. Exosomes from conditioned medium of LPS-treated AECs (LPS-Exos) were isolated by ultracentrifugation. The miRNAs in LPS-Exos were screened by miRNA expression profile analysis. The effects of miR-92a-3p on the function of AMs were studied. We found that intratracheal GW4869 administration ameliorated lung injury following CLP-induced ALI. LPS-Exos were taken up by AMs and activated these cells. Consistently, administration of LPS-Exos in rats significantly aggravated pulmonary inflammation and alveolar permeability. Moreover, miR-92a-3p was enriched in LPS-Exos and could be delivered to AMs. Inhibition of miR-92a-3p in AECs diminished the proinflammatory effects of LPS-Exos in vivo and in vitro. Mechanistically, miR-92a-3p activates AMs along with pulmonary inflammation. This process results in activation of the NF-κB pathway and downregulation of PTEN expression, which was confirmed by a luciferase reporter assay. In conclusion, AEC-derived exosomes activate AMs and induce pulmonary inflammation mediated by miR-92a-3p in ALI. The present findings revealed a previously unidentified role of exosomal miR-92a-3p in mediating the crosstalk between injured AEC and AMs. miR-92a-3p in AEC exosomes might represent a novel diagnostic biomarker for ALI, which may lead to a new therapeutic approach.

The Effect and Regulatory Mechanism of High Mobility Group Box-1 Protein on Immune Cells in Inflammatory Diseases

High mobility group box-1 protein (HMGB1), a member of the high mobility group protein superfamily, is an abundant and ubiquitously expressed nuclear protein. Intracellular HMGB1 is released by immune and necrotic cells and secreted HMGB1 activates a range of immune cells, contributing to the excessive release of inflammatory cytokines and promoting processes such as cell migration and adhesion. Moreover, HMGB1 is a typical damage-associated molecular pattern molecule that participates in various inflammatory and immune responses. In these ways, it plays a critical role in the pathophysiology of inflammatory diseases. Herein, we review the effects of HMGB1 on various immune cell types and describe the molecular mechanisms by which it contributes to the development of inflammatory disorders. Finally, we address the therapeutic potential of targeting HMGB1.

HMGB1/TLR4 Signaling Affects Regulatory T Cells in Acute Lung Injury

Background

High-mobility group box-1 protein (HMGB1) serves as the prototypic damage-associated molecular pattern molecule, and TLR4 is considered a receptor for HMGB1. Regulatory T cells (Tregs) play a crucial role in infectious diseases. The role of HMGB1 in the modulation of Tregs is of great interest.

Methods

Serum HMGB1 and Treg proportions were detected in 58 patients with acute lung injury (ALI) and 36 healthy volunteers. The correlations of these parameters with disease severity were analyzed. The WT and TLR4^-/- mice were administered HMGB1 by intratracheal injection. After 48 h, the mice were sacrificed. The morphological changes and wet/dry ratio of the lung were measured. Spleen CD4⁺CD25⁺ Tregs were sorted from spleen cells, the expression of FOXP3 and CTLA-4, and releasing of cytokines was detected. CD4⁺CD25⁺ Tregs were cocultured with effector T cells, the inhibitory effect, and release of cytokines was detected.

Results

Significantly increased plasma levels of HMGB1 and reduced CD4⁺CD25⁺CD127^low Tregs were detected in ALI patients. In the mouse model, lung injury was significantly increased after HMGB1 instillation in the WT and TLR4^-/- groups compared with control group. The lung wet/dry ratio and the TNF-α and IL-1β contents in BALF were significantly increased, and the severity of WT mice was higher than that of TLR4^-/- mice. The expression of FOXP3 and CTLA-4 in TLR4^-/- mice was significantly increased compared with that in WT mice and was associated with a similar trend of IL-10 and TGF-β levels (p<0.05). In coculture with effector T cells, Tregs isolated from TLR4^-/- mice exhibited decreased IL-2 and IFN-γ and increased IL-4 levels compared with Tregs from WT mice. Increased polarization of TLR4^-/- CD4⁺CD25⁺ Treg cells to Th2 cells was observed.

Conclusion

In HMGB1-induced lung injury, HMGB1 affects the expression of FOXP3 and CTLA-4 through TLR4, thus reducing the immunosuppressive function of Treg cells.

MiR-22-3p suppresses sepsis-induced acute kidney injury by targeting PTEN

Background: Septic acute kidney injury is considered as a severe and frequent complication that occurs during sepsis. The present study was performed to understand the role of miR-22-3p and its underlying mechanism in sepsis-induced acute kidney injury.

Methods: Rats were injected with adenovirus carrying miR-22-3p or miR-NC in the caudal vein before cecal ligation. Meanwhile, HK-2 cells were transfected with the above adenovirus following LPS stimulation. We measured the markers of renal injury (blood urea nitrogen (BUN), serum creatinine (SCR)). Histological changes in kidney tissues were examined by hematoxylin and eosin (H&E), Masson staining, periodic acid Schiff staining and TUNEL staining. The levels of IL-1β, IL-6, TNF-α and NO were determined by ELISA assay. Using TargetScan prediction and luciferase reporter assay, we predicted and validated the association between PTEN and miR-22-3p.

Results: Our data showed that miR-22-3p was significantly down-regulated in a rat model of sepsis-induced acute kidney injury, in vivo and LPS-induced sepsis model in HK-2 cells, in vitro. Overexpression of miR-22-3p remarkably suppressed the inflammatory response and apoptosis via down-regulating HMGB1, p-p65, TLR4 and pro-inflammatory factors (IL-1β, IL-6, TNF-α and NO), both in vivo and in vitro. Moreover, PTEN was identified as a target of miR-22-3p. Furthermore, PTEN knockdown augmented, while overexpression reversed the suppressive role of miR-22-3p in LPS-induced inflammatory response.

Conclusions: Our results showed that miR-22-3p induced protective role in sepsis-induced acute kidney injury may rely on the repression of PTEN.

Exosomes with high level of miR-181c from bone marrow-derived mesenchymal stem cells inhibit inflammation and apoptosis to alleviate spinal cord injury

Stem cell transplantation is a promising method in the treatment of spinal cord injury (SCI). Researches have shown that stem cell-derived exosomes as well as its contents such as microRNAs contribute to the protective effects of stem cell against SCI. However, the effects of exosomes derived from bone marrow stem cells on SCI and the underlying mechanisms remain unknown. In this study, we collected bone marrow stem cells derived exosomes (BMSCs-exo) to deal with SCI rats and LPS induced microglia to explore the possible mechanisms. We found that BMSCs-exo showed significant effects on decreasing pro-inflammatory cytokines as well as increasing Basso-Beattie-Bresnahan score after acute SCI. MicroRNA-181c levels in tissue were elevated with the use of BMSCs-exo. Then we verified the effect in vitro and found that in LPS induced microglia, the administration of BMSCs-exo could inhibit the expression of pro-inflammatory cytokines, and the phosphorylation of NF-κB signal was also suppressed. During which, the expression of microRNA-181c in microglia was elevated. When LPS induced microglia were treated with BMSCs-exo over-expressing microRNA-181c, the levels of pro-inflammatory cytokines decreased. Then bioinformatics techniques were used to detect the possible target gene of microRNA-181c and then PTEN was found as a candidate. Further experiments showed that the protection effects of BMSCs-exo over-expressing microRNA-181c could be antagonized by the elevation of PTEN expression both in vitro and in vivo. In conclusion, we verified that BMSCs-exo could protect against SCI through its content microRNA-181c which suppressed the inflammation in microglia and spinal cord. It was related to the inhibition of PTEN and the suppression of NF-κB signal, and finally decreasing inflammation and apoptosis in spinal cord and improved SCI.

HMGB1 suppress the expression of IL-35 by regulating Naïve CD4+ T cell differentiation and aggravating Caspase-11-dependent pyroptosis in acute lung injury

OBJECTIVES

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a severe form of inflammatory lung disease. Its development and progression are regulated by cytokines. The purpose of this study was to determine the effects of HMGB1 involved in the regulation of Treg cells and IL-35.

METHODS

A cecal ligation and puncture (CLP)-induced ALI model was used to investigate the changes in IL-35, Tregs, and the expression of RAGE and caspase-11 after HMGB1 inhibition (glycyrrhizin was used as an inhibitor of HMGB1). CD4+ naïve T cells sorted from C57BL/6 mice spleens were cultured to explore the role of HMGB1 in the differentiation from CD4+ naïve T cells to Tregs.

RESULTS

HMGB1 promoted lung injury and uncontrolled inflammation in the CLP mouse model. HMGB1, NF-κB p65, RAGE, and caspase-11 expression in the lungs of CLP mice decreased significantly after pretreatment with glycyrrhizin. We found that the Treg proportion and IL-35 expression were upregulated in the serum and lung of CLP mice after inhibiting HMGB1. In our in vitro experiments, we found that recombinant HMGB1 significantly suppressed the proportion of CD4+CD25+FOXP3+Tregs differentiated from CD4+ naïve T cells.

CONCLUSIONS

The inhibition of HMGB1 increased the proportion of Treg and expression of IL-35 and alleviated lung injury in the CLP-induced ALI model. Furthermore, inhibition of HMGB1 reduced caspase-11-dependent pyroptosis in the lungs of the CLP-induced ALI model.

Combination Effect of Three Main Constituents From Sarcandra glabra Inhibits Oxidative Stress in the Mice Following Acute Lung Injury: A Role of MAPK-NF-κB Pathway

Caffeoylquinic acids, coumarins and dicaffeoyl derivatives are considered to be three kinds of the most abundant bioactive components in Sarcandra glabra, an anti-inflammatory herb mainly found in Southern Asia. The combined anti-inflammatory effect of three typical constituents C + R + I (chlorogenic acid + rosmarinic acid + isofraxidin) from this plant has been investigated. The result implies that targeting the MAPK-NF-κB pathway would be one of the major mechanisms involved, using LPS stimulated RAW 264.7 cells as in vitro model and LPS-induced acute lung injury in mice as in vivo model. C + R + I can significantly suppress the levels of nitric oxide (NO), pro-inflammatory cytokines, and inhibit iNOS and COX-2 expression in LPS-treated RAW264.7 macrophage cells. Western blot analysis showed that C + R + I suppressed phosphorylation of NF-κB and MAPK, including phosphorylation of p65-NF-κB, IKB, ERK, JNK and P38. Besides, C + R + I suppressed MPO protein expression, but promoted SOD and HO-1 expression, and the related targets for C, R, and I were also predicted by molecular docking. This indicated that C + R + I could alleviate oxidative stress induced by LPS, which were further verified in the in vivo model of mice with acute lung injury through the measurement of corresponding inflammatory mediators and the analysis of immunehistochemistry.

Bone marrow mesenchymal stem cell-derived exosomes alleviate hyperoxia-induced lung injury via the manipulation of microRNA-425

BACKGROUND

Hyperoxia-induced lung injury (HILI) is an acute lung injury (LI) induced by extended periods of exposure to hyperoxia. Alleviating LI by bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos) and microRNAs (miRs) has been previously reported. This study is devised to probe the interaction between BMSCs-Exos and miR-425 in HILI.

METHODS

Firstly, BMSCs-Exos were isolated and identified. Then, HILI rat models and RLE-6TN cell models were successfully established and treated by BMSCs-Exos. Afterwards, functional assays were conducted to explore cell biological behaviors in models, with miR-425 expression detected. Then, the target relation between miR-425 and PTEN was clarified by luciferase reporter assay. Eventually, expression of PTEN and the PI3K/Akt axis was assessed by Western blotting and qRT-PCR.

RESULTS

BMSCs-Exos promoted miR-425 expression and attenuated HILI and H₂O₂ induced RLE-6TN cell injury as evidence by alleviated lung cell injury, decreased TUNEL-positive cells, induced cell viability and declined apoptosis (all p < 0.05). Besides, when miR-425 was knocked-down, the protective role of BMSCs-Exos in HILI was also reduced (all p < 0.05). miR-425 targeted PTEN mRNA, whose upregulation reversed the protective role of BMSCs-Exos in HILI (all p < 0.05). BMSCs-Exos improved the quenched levels of the PI3K/AKT axis in HILI (all p < 0.05).

CONCLUSION

Our data supported that miR-425 in BMSCs-Exos inhibits HILI by targeting PTEN and upregulating the PI3K/AKT axis. This study may provide personalized interventions for HILI remedy.

Contribution of Connexin Hemichannels to the Pathogenesis of Acute Lung Injury

Connexin (Cx) family members form hemichannels (HCs) and gap junctions (GJs). Biological functions of Cx HCs have not been adequately characterized due to the inability to selectively target HCs or GJs. Recently, we developed a 6-mer peptide mimetic (P5) of the first extracellular loop of Cx43 and showed that it can block the permeability of HCs but not GJs formed by Cx43. In this study, we further characterized the HC blocking property of P5 and investigated the role of Cx HCs in acute lung injury (ALI). We found that P5 administration decreased HC permeability, in pulmonary microvascular endothelial cells, HepG2 cells, and even Cx43-deficient astrocytes, which express different sets of Cxs, suggesting that P5 is a broad spectrum Cx HC blocker. In addition, P5 reduced HC permeability of alveolar cells in vivo. Moreover, P5 decreased endotoxin-induced release, by vascular endothelial cells in vitro, of high mobility group box protein 1 (HMGB1), a critical mediator of acute lung injury (ALI), and reduced HMGB1 accumulation in bronchoalveolar lavage fluid (BALF) of mice subjected to intratracheal endotoxin instillation. Furthermore, P5 administration resulted in a significant decrease in the concentrations of ALT, AST, and LDH in the BALF, the accumulation of leukocytes in alveoli, and the mortality rate of mice subjected to ALI. Wright-Giemsa staining showed that P5 caused similar reductions of both neutrophils and monocytes in BALF of ALI mice. Together, these results suggest that Cx HCs mediate HMGB1 release, augment leukocyte recruitment, and contribute to ALI pathology.

Quietness of circular RNA circ_0054633 alleviates the inflammation and proliferation in lipopolysaccharides-induced acute lung injury model through NF-κB signaling pathway

AIM

Acute lung injury (ALI) is the mild form of acute respiratory distress syndrome (ARDS) which is a common lung disease with a high incidence and mortality rate. Recent studies manifested that some circular RNAs were associated with ALI. In this study, we aimed to uncover the effect of circular RNA circ_0054633 on ALI initiation and progression and proposed a new mechanism related to ALI.

METHODS

The lipopolysaccharides (LPS)-induced acute lung injury model were build both in vivo of rat and in vitro of primary murine pulmonary microvascular endothelial cells (MPVECs). Hematoxylin and eosin (H&E) was employed to observe the tissue morphology and estimate the degree of lung damage. We used real-time quantitative polymerase chain reaction (RT-qPCR) to measure the expression level of circ_0054633. The expression levels of inflammatory cytokines IL-17A and tumor necrosis factor-α (TNF-α) were detected by ELISA. The effects of circ_0054633 on MPVECs proliferation and apoptosis were detected with the help of CCK-8 and apoptosis assay, separately. The expression level of NF-κB p65 protein was measured by Western blot.

RESULTS

circ_0054633, IL-17A, TNF-α and NF-κB p65 were all overexpressed in LPS-treated rat and MPVECs, and LPS enhanced the proliferation and apoptosis of MPVECs. While circ_0054633 silencing reversed the above promotion effects of LPS on IL-17A, TNF-α expression and MPVECs proliferation and apoptosis.

CONCLUSIONS

Quietness of circ_0054633 alleviated LPS-induced ALI via NF-κB signaling pathway, implicating circ_0054633 may be a potential biomarker for diagnose and therapy of ALI.

β-catenin regulates myocardial ischemia/reperfusion injury following heterotopic heart transplantation in mice by modulating PTEN pathways

Ischemia reperfusion (I/R) injury, an inevitable event accompanying heart transplantation, is the primary factor leading to organ failure and graft rejection. In order to prevent I/R injury, we established murine heart transplantation model with I/R and cell culture system to determine whether β-catenin is a mediate factor in preventing I/R injury in heart transplantation. After successfully established heterotopic heart transplantation mice model, the I/R injury was induced, and two dynamic temporal were studied during different I/R phases. With the increase of ischemia and reperfusion time, heart damage was more severe. In the initial study, we observed that β-catenin was significantly decreased, while ROCK1 and PTEN increased during the perfusion phase from day 0 to day 1, and remain the same level until 3 days later. The similar pattern that β-catenin was down-regulated while ROCK1 and PTEN were up-regulated was also observed in the dynamic temporal ischemia study. To further investigate the role of β-catenin signaling in I/R injury in vitro, β-catenin over-expressing plasmid was transfected into HL-1 cells, a cardiac cell line. We noted that β-catenin over-expressing cardiomyocytes showed decreased ROCK1/PTEN expression both at mRNA and protein levels. In addition, cobalt dichloride (CoCl₂) -induced oxidative stress model was further established to mimic cardiac I/R injury. We observed that CoCl₂-induced activation of ROCK1/PTEN signaling pathway were attenuated by transient transfection of a β-catenin over-expressing plasmid. Taken together, our results suggest that cardiac transplant induced IR injury is closely associated with the down-regulation of β-catenin and up-regulation of ROCK1 and PTEN expression.

HMGB1 aggravates lipopolysaccharide-induced acute lung injury through suppressing the activity and function of Tregs

BACKGROUND

CD4⁺CD25⁺FoxP3⁺ T helper cells (Tregs), a subgroup of CD4⁺ T helper cells, are critical effectors that protect against acute lung injury (ALI) by contact-dependent suppression or releasing anti-inflammatory cytokines including interleukin-10 (IL-10), and transforming growth factor (TGF-β). HMGB1 (High mobility group box 1 protein) was identified as a nuclear non-histone DNA-binding chromosomal protein, which participates in the regulation of lung inflammatory response and pathological processes in ALI. Previous studies have suggested that Tregs overexpresses the HMGB1-recognizing receptor. However, the interaction of HMGB1 with Tregs in ALI is still unclear.

OBJECTIVE

To investigate whether HMGB1 aggravates ALI by suppressing immunosuppressive function of Tregs.

METHODS

Anti-HMGB1 antibody and recombinant mouse HMGB1 (rHMGB1) were administered in lipopolysaccharide (LPS)-induced ALI mice and polarized LPS-primed Tregs in vitro. The Tregs pre-stimulated with or without rHMGB1 were adoptively transferred to ALI mice and depleted by Diphtheria toxin (DT). For coculture experiment, isolated Tregs were first pre-stimulated with or without rHMGB1 or anti-HMGB1 antibody, then they were cocultured with bone marrow-derived macrophages (BMMs) under LPS stimulation.

RESULTS

Tregs protected against acute lung pathological injury. HMGB1 modulated the suppressive function of Tregs as follows: reduction in the number of the cells and the activity of Tregs, the secretion of anti-inflammatory cytokines (IL-10, TGF-β) from Tregs, the production of IL-2 from CD4⁺ T cells and CD11c⁺ DCs, and the M2 polarization of macrophages, as well as inducing proinflammatory response of macrophages.

CONCLUSIONS

HMGB1 could aggravate LPS induced-ALI through suppressing the activity and function of Tregs.

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.

Histone Deacetylation Inhibitors as Modulators of Regulatory T Cells

Regulatory T cells (T_regs) are important mediators of immunological self-tolerance and homeostasis. Being cluster of differentiation 4⁺Forkhead box protein3⁺ (CD4⁺FOXP3⁺), these cells are a subset of CD4⁺ T lymphocytes and can originate from the thymus (tT_regs) or from the periphery (pT_regs). The malfunction of CD4⁺ T_regs is associated with autoimmune responses such as rheumatoid arthritis (RA), multiple sclerosis (MS), type 1 diabetes (T1D), inflammatory bowel diseases (IBD), psoriasis, systemic lupus erythematosus (SLE), and transplant rejection. Recent evidence supports an opposed role in sepsis. Therefore, maintaining functional T_regs is considered as a therapy regimen to prevent autoimmunity and allograft rejection, whereas blocking T_reg differentiation might be favorable in sepsis patients. It has been shown that T_regs can be generated from conventional naïve T cells, called iT_regs, due to their induced differentiation. Moreover, T_regs can be effectively expanded in vitro based on blood-derived tT_regs. Taking into consideration that the suppressive role of T_regs has been mainly attributed to the expression and function of the transcription factor Foxp3, modulating its expression and binding to the promoter regions of target genes by altering the chromatin histone acetylation state may turn out beneficial. Hence, we discuss the role of histone deacetylation inhibitors as epigenetic modulators of T_regs in this review in detail.

Mesenchymal stem cells regulate the Th17/Treg cell balance partly through hepatocyte growth factor in vitro

Introduction

Mesenchymal stem cells (MSCs) exert immunomodulatory functions by inducing the development and differentiation of naive T cells into T cells with an anti-inflammatory regulatory T cell (Treg) phenotype. Our previous study showed that hepatocyte growth factor (HGF) secreted by MSCs had immunomodulatory effects in the context of lipopolysaccharide (LPS) stimulation. We hypothesized that HGF is a key factor in the MSC-mediated regulation of the T helper 17 (Th17) cell/regulatory T (Treg) cell balance.

Methods

We investigated the effects of MSCs on the differentiation of CD4+ T cells and the functions of Th17/Treg cells in response to LPS stimulation by performing in vitro coculture experiments. MSCs were added to the upper chambers of cell culture inserts, and CD4+ T cells were plated in the lower chambers, followed by treatment with LPS or an anti-HGF antibody. Th17 (CD4+CD3+RORrt+) and Treg (CD4+CD25+Foxp3+) cell frequencies were analysed by flow cytometry, and the expression of Th17 cell- and Treg cell-related cytokines in the CD4+ T cells or culture medium was measured by quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Neutrophil functions were determined by flow cytometry after a coculture with Th17/Treg cells.

Results

The percentage of CD4+CD25+Foxp3+ cells was significantly increased in the CD4+ T cell population, while the percentage of CD4+CD3+RORrt+ cells was significantly decreased after MSC coculture. However, the MSC-induced effect was significantly inhibited by the anti-HGF antibody (p < 0.05). Furthermore, MSCs significantly inhibited the CD4+ T cell expression of IL-17 and IL-6 but increased the expression of IL-10 (p < 0.05 or p < 0.01); these effects were inhibited by the anti-HGF antibody (p < 0.05). In addition, CD4+ T cells cocultured with MSCs significantly inhibited neutrophil phagocytic and oxidative burst activities (p < 0.05 or p < 0.01); however, these MSC-induced effects were inhibited by the anti-HGF antibody (p < 0.05).

Conclusion

These data suggested that MSCs induced the conversion of fully differentiated Th17 cells into functional Treg cells and thereby modulated the Th17/Treg cell balance in the CD4+ T cell population, which was partly attributed to HGF secreted by the MSCs.

Saikosaponin-d attenuated lipopolysaccharide-induced depressive-like behaviors via inhibiting microglia activation and neuroinflammation

Saikosaponin-d (SSd), a triterpenoid saponins compound extracted from Radix Bupleuri, has been demonstrated to effectively alleviate chronic mild stress-induced depressive behaviors in rats, but the underlying molecular mechanisms are still uncertain. Increasing evidence indicated that microglia activation and inflammatory responses were involved in the pathogenesis of depression. Thus, we desired to induce inflammation-related depressive-like behaviors in mice by injecting lipopolysaccharide (LPS) to investigate whether the antidepressant effect of SSd is related to inhibiting inflammation. The results of behavioral tests showed that SSd administration ameliorated LPS-induced depressive-like behaviors, as shown by increased sucrose consumption in the sucrose preference test and decreased immobility time in the tail suspension test and forced swimming test. Furthermore, immunostaining results showed that SSd pretreatment inhibited LPS-induced microglia activation in the hippocampus of mice and primary microglia cells. Enzyme-linked immunosorbent assay (ELISA) results showed that SSd pretreatment suppressed LPS-induced overexpression of inflammatory factors such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α both in vivo and in vitro. Immunostaining and western blot analysis results demonstrated that SSd pretreatment also inhibited LPS-induced HMGB1 translocation from nuclear to extracellular and decreased the protein levels of TLR4, p-IκB-α, NF-κBp65. These results suggested that SSd effectively improved LPS-induced inflammation-related depressive-like behaviors by inhibiting LPS-induced microglia activation and neuroinflammation, and the possible mechanism might associate with the regulation of the HMGB1/TLR4/NF-κB signaling pathway.