STING mediates LPS-induced acute lung injury by regulating ferroptosis.

The pathogenesis of acute lung injury is not fully understood. Stimulator of interferon genes (STING) and ferroptosis have been implicated in various pathological and physiological processes, including acute lung injury (ALI). However, the relationship between STING and ferroptosis in lipopolysaccharide (LPS)-induced ALI is unclear. We found that LPS stimulation activated STING and ferroptosis. Furthermore, STING knockout and ferroptosis inhibitor alleviated lung inflammation and epithelial cell damage. Also, STING knockout reduced inflammation injury and ferroptosis. Notably, the ferroptosis inducer reversed the alleviation of inflammation caused by STING knockout. These results show that STING participates in the inflammation injury of ALI by regulating ferroptosis. Results also showed that p-STAT3 levels increased after STING knockout, suggesting that STING negatively regulates STAT3 activation. Besides, STAT3 inhibitor aggravated ferroptosis after STING knockout, indicating that STING regulates ferroptosis through STAT3 signaling. In conclusion, STING mediates LPS-induced ALI by regulating ferroptosis, indicating that STING and ferroptosis may be new targets for ALI treatment.

Gut Dysbiosis Promotes Preeclampsia by Regulating Macrophages and Trophoblasts.

BACKGROUND: Preeclampsia is one of the leading causes of maternal and perinatal morbidity and is characterized by hypertension, inflammation, and placental dysfunction. Gut microbiota plays key roles in inflammation and hypertension. However, its roles and mechanisms in preeclampsia have not been fully elucidated. METHODS: 16S rRNA gene sequencing and targeted metabolomics were conducted on stool samples from 92 preeclamptic patients and 86 normal late-pregnant women. Then, fecal microbiota transplantation and in vitro and in vivo functional experiments were performed to explore the roles and mechanisms of gut microbiota in preeclampsia development. RESULTS: We revealed the gut microbiota dysbiosis in preeclamptic patients, including significant reductions in short-chain fatty acid-producing bacteria and short-chain fatty acids. The gut microbiota of preeclamptic patients significantly exacerbated pathologies and symptoms of preeclamptic rats, whereas the gut microbiota of healthy pregnant women had significant protective effects. Akkermansia muciniphila, propionate, or butyrate significantly alleviated the symptoms of preeclamptic rats. Mechanistically, they significantly promoted autophagy and M2 polarization of macrophages in placental bed, thereby suppressing inflammation. Propionate also significantly promoted trophoblast invasion, thereby improved spiral arterial remodeling. Additionally, we identified a marker set consisting of Akkermansia, Oscillibacter, and short-chain fatty acids that could accurately diagnose preeclampsia. CONCLUSIONS: Our study revealed that gut microbiota dysbiosis is an important etiology of preeclampsia. Gut microbiota and their active metabolites have great potential for the treatment and diagnosis of preeclampsia. Our findings enrich the gut-placenta axis theory and contribute to the development of microecological products for preeclampsia.

A Narrative Review: The Role of NETs in Acute Respiratory Distress Syndrome/Acute Lung Injury.

Nowadays, acute respiratory distress syndrome (ARDS) still has a high mortality rate, and the alleviation and treatment of ARDS remains a major research focus. There are various causes of ARDS, among which pneumonia and non-pulmonary sepsis are the most common. Trauma and blood transfusion can also cause ARDS. In ARDS, the aggregation and infiltration of neutrophils in the lungs have a great influence on the development of the disease. Neutrophils regulate inflammatory responses through various pathways, and the release of neutrophils through neutrophil extracellular traps (NETs) is considered to be one of the most important mechanisms. NETs are mainly composed of DNA, histones, and granuloproteins, all of which can mediate downstream signaling pathways that can activate inflammatory responses, generate immune clots, and cause damage to surrounding tissues. At the same time, the components of NETs can also promote the formation and release of NETs, thus forming a vicious cycle that continuously aggravates the progression of the disease. NETs are also associated with cytokine storms and immune balance. Since DNA is the main component of NETs, DNase I is considered a viable drug for removing NETs. Other therapeutic methods to inhibit the formation of NETs are also worthy of further exploration. This review discusses the formation and mechanism of NETs in ARDS. Understanding the association between NETs and ARDS may help to develop new perspectives on the treatment of ARDS.

Host stimulator of interferon genes is essential for the efficacy of anti-programmed cell death protein 1 inhibitors in non-small cell lung cancer.

The stimulator of interferon genes (STING) pathway is important for anticancer immune responses. However, the relative contributions of host and tumour STING in anti-programmed cell death protein 1 (anti-PD-1) inhibitor responses in non-small cell lung cancer (NSCLC) are unknown. STING expression in tumour and blood was associated with anti-PD-1 therapy in NSCLC patients; Moreover, loss of PD-1 inhibitor therapeutic potency was demonstrated in STING KO (knock out) splenocytes and STING KO mice. STING knock-down in tumour cells had no effect. STING on CD8+ T cells and host cells, not tumour cells, correlated with clinical effect of anti-PD-1 therapy in NSCLC patients. Finally, adoptive transfer of CD8+ T cells restored PD-1 inhibitor anticancer effects. STING in host cells but not in tumour cells mediates anti-PD-1 inhibitor responses in cancer immunotherapy and could be used to select advantageous NSCLC patients from immunotherapy.

Intestinal Flora Modulates Blood Pressure by Regulating the Synthesis of Intestinal-Derived Corticosterone in High Salt-Induced Hypertension.

RATIONALE: High-salt diet is one of the most important risk factors for hypertension. Intestinal flora has been reported to be associated with high salt-induced hypertension (hSIH). However, the detailed roles of intestinal flora in hSIH pathogenesis have not yet been fully elucidated. OBJECTIVE: To reveal the roles and mechanisms of intestinal flora in hSIH development. METHODS AND RESULTS: The abovementioned issues were investigated using various techniques including 16S rRNA gene sequencing, untargeted metabolomics, selective bacterial culture, and fecal microbiota transplantation. We found that high-salt diet induced hypertension in Wistar rats. The fecal microbiota of healthy rats could dramatically lower blood pressure (BP) of hypertensive rats, whereas the fecal microbiota of hSIH rats had opposite effects. The composition, metabolism, and interrelationship of intestinal flora in hSIH rats were considerably reshaped, including the increased corticosterone level and reduced Bacteroides and arachidonic acid levels, which tightly correlated with BP. The serum corticosterone level was also significantly increased in rats with hSIH. Furthermore, the above abnormalities were confirmed in patients with hypertension. The intestinal Bacteroides fragilis could inhibit the production of intestinal-derived corticosterone induced by high-salt diet through its metabolite arachidonic acid. CONCLUSIONS: hSIH could be transferred by fecal microbiota transplantation, indicating the pivotal roles of intestinal flora in hSIH development. High-salt diet reduced the levels of B fragilis and arachidonic acid in the intestine, which increased intestinal-derived corticosterone production and corticosterone levels in serum and intestine, thereby promoting BP elevation. This study revealed a novel mechanism different from inflammation/immunity by which intestinal flora regulated BP, namely intestinal flora could modulate BP by affecting steroid hormone levels. These findings enriched the understanding of the function of intestinal flora and its effects on hypertension.

Geranylgeranyl diphosphate synthase deficiency hyperactivates macrophages and aggravates lipopolysaccharide-induced acute lung injury.

Macrophage activation is a key contributing factor for excessive inflammatory responses of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Geranylgeranyl diphosphate synthase (GGPPS) plays a key role in the development of inflammatory diseases. Our group previously showed that GGPPS in alveolar epithelium have deleterious effects on acute lung injury induced by LPS or mechanical ventilation. Herein, we examined the role of GGPPS in modulating macrophage activation in ALI/ARDS. We found significant increased GGPPS expression in alveolar macrophages in patients with ARDS compared with healthy volunteers and in ALI mice induced by LPS. GGPPS-floxed control (GGPPSfl/fl) and myeloid-selective knockout (GGPPSfl/flLysMcre) mice were then generated. Interestingly, using an LPS-induced ALI mouse model, we showed that myeloid-specific GGPPS knockout significantly increased mortality, aggravated lung injury, and increased the accumulation of inflammatory cells, total protein, and inflammatory cytokines in BALF. In vitro, GGPPS deficiency upregulated the production of LPS-induced IL-6, IL-1ß, and TNF-α in alveolar macrophages, bone marrow-derived macrophages (BMDMs), and THP-1 cells. Mechanistically, GGPPS knockout increased phosphorylation and nuclear translocation of NF-κB p65 induced by LPS. In addition, GGPPS deficiency increased the level of GTP-Rac1, which was responsible for NF-κB activation. In conclusion, decreased expression of GGPPS in macrophages aggravates lung injury and inflammation in ARDS, at least partly by regulating Rac1-dependent NF-κB signaling. GGPPS in macrophages may represent a novel therapeutic target in ARDS.

Phospholipase Cε Regulates Prostate Cancer Lipid Metabolism and Proliferation by Targeting AMP-Activated Protein Kinase (AMPK)/Sterol Regulatory Element-Binding Protein 1 (SREBP-1) Signaling Pathway.

BACKGROUND Metabolic reprogramming is a common characteristic of numerous kinds of tumors, including prostate cancer (PCa). Tumor metabolism such as lipid metabolism provides sufficient lipids for tumor cell division and rapid growing as well as a vital source for formation of new cellular membranes. Phospholipase Cε (PLCε) is an oncogene that can drive proliferation, progression, and lipid metabolism of tumors, but its effect in lipid metabolism of PCa is not clear. MATERIAL AND METHODS Benign prostatic hyperplasia (BPH) and PCa tissue specimens were assessed for SREBP-1, FASN, and PLCε by immunohistochemistry, and PLCε was knocked-down by a lentiviral short hairpin RNA. The mRNA and protein level expression of related factors were tested by qPCR and Western blot analyses. Cell proliferation was assessed by clone formation, CCK-8, and Ki-67 assays. Nile red and oil red O staining were performed to detect endogenous lipid levels. Immunofluorescence was used to localize the protein of SREBP-1. Finally, a tumor xenograft assay of nude mice was performed to assess the role of PLCε in prostate tumor generation. RESULTS We found that overexpression of PLCε indicates low PFS in PCa and is involved in metastasis of PCa, and that the PLCε/AMPK/SREBP-1 signaling network promotes the progression of PCa through lipid metabolism in vivo and in vitro. CONCLUSIONS This study is the first to discover the lethal role of PLCε in lipid metabolism and malignant behavior of PCa, elucidation PCa occurrence and progression.

Inhibition of GGPPS1 attenuated LPS-induced acute lung injury and was associated with NLRP3 inflammasome suppression.

Inhibition of the mevalonate pathway using statins has been shown to be beneficial in the treatment of acute lung injury (ALI). Here, we investigated whether partial inhibition of this pathway by targeting geranylgeranyl pyrophosphate synthase large subunit 1 (GGPPS1), a catalase downstream of the mevalonate pathway, was effective at treating lung inflammation in ALI. Lipopolysaccharide (LPS) was intratracheally instilled to induce ALI in lung-specific GGPPS1-knockout and wild-type mice. Expression of GGPPS1 in lung tissues and alveolar epithelial cells was examined. The severity of lung injury and inflammation was determined in lung-specific GGPPS1 knockout and wild-type mice by measuring alveolar exudate, neutrophil infiltration, lung injury, and cell death. Change in global gene expression in response to GGPPS1 depletion was measured using mRNA microarray and verified in vivo and in vitro. We found that GGPPS1 levels increased significantly in lung tissues and alveolar epithelial cells in LPS-induced ALI mice. Compared with wild-type and simvastatin treated mice, the specific deletion of pulmonary GGPPS1 attenuated the severity of lung injury by inhibiting apoptosis of AECs. Furthermore, deletion of GGPPS1 inhibited LPS-induced inflammasome activation, in terms of IL-1ß release and pyroptosis, by downregulating NLRP3 expression. Finally, downregulation of GGPPS1 reduced the membrane expression of Ras-related protein Rab10 and Toll-like receptor 4 (TLR4) and inhibited the phosphonation of IκB. This effect might be attributed to the downregulation of GGPP levels. Our results suggested that inhibition of pulmonary GGPPS1 attenuated LPS-induced ALI predominantly by suppressing the NLRP3 inflammasome through Rab10-mediated TLR4 replenishment.

Geranylgeranyl diphosphate synthase deficiency aggravates lung fibrosis in mice by modulating TGF-ß1/BMP-4 signaling.

Geranylgeranyl diphosphate synthase (GGPPS) is an enzyme that catalyzes the synthesis of geranylgeranyl pyrophosphate (GGPP). GGPPS is implicated in many disorders, but its role in idiopathic pulmonary fibrosis (IPF) remains unclear. This study aimed to investigate the role of GGPPS in IPF. We established bleomycin-induced lung injury in a lung-specific GGPPS-deficient mouse (GGPPS-/-) and detected GGPPS expression in lung tissues by Western blot and immunohistochemistry analysis. We found that GGPPS expression increased during lung injury and fibrosis in mice induced by bleomycin, and GGPPS deficiency augmented lung fibrosis. GGPPS deficiency activated lung fibroblast by facilitating transforming growth factor ß1 while antagonizing bone morphogenetic protein 4 signaling. Notably, the supplementation of exogenous GGPP mitigated lung fibrosis in GGPPS-/- mice induced by bleomycin. In conclusion, our findings suggest that GGPPS provides protection against pulmonary fibrosis and that the restoration of protein geranylgeranylation may benefit statin-induced lung injury.

Topotecan Alleviates Lipopolysaccharide-Mediated Acute Lung Injury Via the NF-κB Signaling Pathway.

BACKGROUND: The topoisomerase 1 (Top1) inhibitor has been reported to inhibit inflammatory genes induced by virus and protect mice from sepsis. Its role in acute lung injury (ALI) remains unknown. This study aimed to explore the effects of topotecan (TPT), a Top 1 inhibitor, in lipopolysaccharide (LPS)-ALI. MATERIALS AND METHODS: THP-1 cells were stimulated with LPS and then treated with or without TPT. Inflammatory cytokines expression was measured by ELISA. In vivo, we also detected the effect of TPT in LPS-induced ALI mouse model through hematoxylin-eosin staining of lung tissue and the quantification of total protein, total cell count, and cytokines in bronchoalveolar lavage fluid. To investigate the effect of TPT on transcriptome levels, microarray analyses were performed. KEGG analysis was applied to determine potential pathways modified by TPT. Microarray results were confirmed by real-time PCR and Western blot. RESULTS: TPT significantly decreased the expression of TNF-α and IL-1ß induced by LPS in THP-1 cells. In an LPS-induced ALI mouse model, TPT significantly attenuated lung injury and decreased the levels of total protein, total cell count, and inflammatory cytokine expression in bronchoalveolar lavage fluid. Microarray results showed that TPT significantly increased expression of 958 genes and decreased expression of 1400 genes in THP-1 cells upon LPS stimulation. KEGG analysis demonstrated that differentially expressed genes function in multiple signaling pathways, including the nuclear factor (NF)-κB signaling pathway. The downstream gene of NF-κB, including c-IAP1/2, c-FLIP, Bcl-2, IL-8, and VCAM-1, and the phosphorylation of NF-κB p105, p65, and IκB-α were significantly decreased after TPT administration in THP-1 cells. CONCLUSIONS: In conclusion, TPT attenuates LPS-induced ALI through inhibiting the NF-κB signaling pathway, suggesting that TPT might serve as a useful therapeutic for ALI. Thus, our study has provided new insight for current ALI treatment.

Overexpression of geranylgeranyl diphosphate synthase contributes to tumour metastasis and correlates with poor prognosis of lung adenocarcinoma.

This study aimed to evaluate the biological role of geranylgeranyl diphosphate synthase (GGPPS) in the progression of lung adenocarcinoma. GGPPS expression was detected in lung adenocarcinoma tissues by qRT-PCR, tissue microarray (TMA) and western blotting. The relationships between GGPPS expression and the clinicopathological characteristics and prognosis of lung adenocarcinoma patients were assessed. GGPPS was down-regulated in SPCA-1, PC9 and A549 cells using siRNA and up-regulated in A549 cells using an adenoviral vector. The biological roles of GGPPS in cell proliferation, apoptosis, migration and invasion were determined by MTT and colony formation assays, flow cytometry, and transwell and wound-healing assays, respectively. In addition, the regulatory roles of GGPPS on the expression of several epithelial-mesenchymal transition (EMT) markers were determined. Furthermore, the Rac1/Cdc42 prenylation was detected after knockdown of GGPPS in SPCA-1 and PC9 cells. GGPPS expression was significantly increased in lung adenocarcinoma tissues compared to that in adjacent normal tissues. Overexpression of GGPPS was correlated with large tumours, high TNM stage, lymph node metastasis and poor prognosis in patients. Knockdown of GGPPS inhibited the migration and invasion of lung adenocarcinoma cells, but did not affect cell proliferation and apoptosis. Meanwhile, GGPPS inhibition significantly increased the expression of E-cadherin and reduced the expression of N-cadherin and vimentin in lung adenocarcinoma cells. In addition, the Rac1/Cdc42 geranylgeranylation was reduced by GGPPS knockdown. Overexpression of GGPPS correlates with poor prognosis of lung adenocarcinoma and contributes to metastasis through regulating EMT.

Topotecan alleviates ventilator-induced lung injury via NF-κB pathway inhibition.

OBJECTIVE: We investigated the effect of topotecan on injury and inflammation in a model of ventilator-inducedlunginjury (VILI). METHODS: Acute lung injury (ALI) was induced in mice by high-tidal volume ventilation, and the mice were then treated with topotecan or PBS. Lung tissue and bronchoalveolar lavage fluid were collected to assess pulmonary vascular leaks, inflammation, and cell apoptosis. RESULTS: Compared to PBS treatment, topotecan significantly decreased the ALI score, myeloperoxidase (MPO) content, total protein concentration, and presence of inflammatory cells and inflammatory cytokines in bronchoalveolar lavage fluid. Topotecan also reduced caspase-3 activation and type Ⅱ alveolar epithelial cell apoptosis. Moreover, topotecan inhibited NF-κB expression and activation in the VILI model. CONCLUSION: Topotecan alleviates acute lung injury in the model of VILI through the inhibition of the NF-κB pathway.

NCAPG2 promotes tumour proliferation by regulating G2/M phase and associates with poor prognosis in lung adenocarcinoma.

NCAPG2 is a component of the condensin II complex and contributes to chromosome segregation via microtubule-kinetochore attachment during mitosis. It is well known that NCAPG2 plays a critical role in cell mitosis; however, the role of altered NCAPG2 expression and its transcriptional regulatory function in cancer development remains mostly unknown. Here, for the first time we reported that NCAPG2 was evidently increased in non-small cell lung cancer tissues compared to adjacent normal lung tissues. Clinicopathological data analysis showed that NCAPG2 overexpression was significantly correlated with lymph node metastasis and pathologic-Tumour Nodes Metastasen stages, and was an independent prognostic factor in lung adenocarcinoma patients. Moreover, siRNA-mediated knockdown of NCAPG2 could inhibit tumour cell growth of lung adenocarcinoma cells (A549 and H1299) in vitro and could significantly lead to cell cycle arrest in the G2 phase. Furthermore, we found that NCAPG2 silencing significantly decreased the expression levels of G2/M phase cell cycle-related protein expressions (Cyclin B1, Cdc2) and increased the expression levels of p27 and p21 through Western blot analysis. Taken together, we demonstrated that increased NCAPG2 expression could regulate cell proliferation and identified as a poor prognostic biomarker in lung adenocarcinoma.

PRC1 contributes to tumorigenesis of lung adenocarcinoma in association with the Wnt/ß-catenin signaling pathway.

BACKGROUND: Protein regulator of cytokinesis-1 (PRC1) belongs to the microtubule-associated proteins (MAPs) family, and is involved in cytokinesis. Recent investigations suggest PRC1 involvement in human carcinogenesis, including breast carcinoma, hepatocellular carcinoma and etc. However, whether PRC1 contributes to lung adenocarcinoma tumorigenesis remains unknown. METHODS: Quantitative reverse-transcription polymerase chain reaction (qRT-PCR), Western blotting and Immunohistochemical staining (IHC) were used to evaluate and contrast the PRC1 expression profile in lung adenocarcinoma and adjacent normal lung tissues. We examined the clinical use of PRC1 in lung adenocarcinoma prognosis. Additionally, the tumorigenesis impact of PRC1 in lung adenocarcinoma cells was verified via in vitro and in vivo metastasis and tumorigenesis assays. Notably, Next Generation Sequencing (NGS) was performed to investigate the molecular mechanism underlying the oncogenic role of PRC1 in lung adenocarcinoma. RESULTS: PRC1 mRNA and protein expressions were upregulated in lung adenocarcinoma tissues compared to adjacent normal lung tissues. PRC1 protein overexpression correlated with lymph node metastasis and was an independent poor prognostic factor for lung adenocarcinoma patients. Our data implied that PRC1 depletion limited the proliferation and invasion of lung adenocarcinoma cells in vitro and lowered tumor development and lung metastasis in vivo. Remarkably, limiting PRC1 substantially prompted G2/M phase cell cycle arrest and apoptosis. Mechanistically, by conducting NGS on PRC1-depleted A549 cells and control cells, we discovered that PRC1 expression was significantly correlated with the Wnt signaling pathway. CONCLUSIONS: This investigation offers confirmation that PRC1 is a prognostic and promising therapeutic biomarker for people with lung adenocarcinoma and takes on a key part in the activation of the Wnt/ß-catenin pathway in lung adenocarcinoma development.

Cerebral pseudoinfarction due to venoarterial extracorporeal membrane oxygenation: A case report.

BACKGROUND: Neurological complications are common in the management of venoarterial extracorporeal membrane oxygenation (VA-ECMO), with most patients requiring sedation and intubation, limiting the assessment of neurological function. There-fore, we must rely on advanced neuroimaging techniques, such as computed tomography angiography (CTA) and computed tomography perfusion (CTP). Because ECMO changes the normal blood flow pattern, it may interfere with the contrast medium in some special cases, leading to artifacts and ultimately mis-leading clinical decisions. CASE SUMMARY: A 61-year-old man presented to a local hospital with chest tightness and pain 1 d prior to presentation. The patient was treated with VA-ECMO after sudden car-diac and respiratory arrest at a local hospital. For further treatment, the patient was transferred to our hospital. The initial consciousness assessment was not clear, and routine CTP was performed to understand the intracranial changes, which suggested a large area of cerebral infarction on the right side; however, the cerebral oxygen was not consistent with the CTP results, and the reexamination of CTA still suggested a right cerebral infarction. To identify this difference, bedside transcranial Doppler was performed, and the blood flow on both sides was different. By reducing the ECMO flow, CTP reexamination showed that the results were normal and consistent with the clinical results. On day 3, the patient was alert and showed good limb movements. CONCLUSION: In patients with peripheral VA-ECMO, cerebral perfusion confirmed by CTP and CTA may lead to false cerebral infarction.

Intestinal flora and pregnancy complications: Current insights and future prospects.

Numerous studies have demonstrated the pivotal roles of intestinal microbiota in many physiopathological processes through complex interactions with the host. As a unique period in a woman's lifespan, pregnancy is characterized by changes in hormones, immunity, and metabolism. The gut microbiota also changes during this period and plays a crucial role in maintaining a healthy pregnancy. Consequently, anomalies in the composition and function of the gut microbiota, namely, gut microbiota dysbiosis, can predispose individuals to various pregnancy complications, posing substantial risks to both maternal and neonatal health. However, there are still many controversies in this field, such as "sterile womb" versus "in utero colonization." Therefore, a thorough understanding of the roles and mechanisms of gut microbiota in pregnancy and its complications is essential to safeguard the health of both mother and child. This review provides a comprehensive overview of the changes in gut microbiota during pregnancy, its abnormalities in common pregnancy complications, and potential etiological implications. It also explores the potential of gut microbiota in diagnosing and treating pregnancy complications and examines the possibility of gut-derived bacteria residing in the uterus/placenta. Our aim is to expand knowledge in maternal and infant health from the gut microbiota perspective, aiding in developing new preventive and therapeutic strategies for pregnancy complications based on intestinal microecology.

Fibroblast Growth Factor 21 Relieves Lipopolysaccharide-Induced Acute Lung Injury by Suppressing JAK2/STAT3 Signaling Pathway.

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a life-threatening disease without an effective drug at present. Fibroblast growth factor 21 (FGF21) was reported to be protective against inflammation in metabolic disease in recent studies. However, the role of FGF21 in ALI has been rarely investigated. In this study, it was found that the expression of FGF21 was markedly increased in lung tissue under lipopolysaccharide (LPS) stimulation in vivo, whereas it was decreased in lung epithelial cells under LPS stimulation in vitro. Therefore, our research aimed to elucidate the potential role of FGF21 in LPS-induced ALI and to detect possible underlying mechanisms. The results revealed that the deficiency of FGF21 aggravated pathological damage, inflammatory infiltration, and pulmonary function in LPS-induced ALI, while exogenous administration of FGF21 improved these manifestations. Moreover, through RNA sequencing and enrichment analysis, it was unveiled that FGF21 might play a protective role in LPS-induced ALI via JAK2/STAT3 signaling pathway. The therapeutic effect of FGF21 was weakened after additional usage of JAK2 activator in vivo. Further investigation revealed that FGF21 significantly inhibited STAT3 phosphorylation and impaired the nuclear translocation of STAT3 in vitro. In addition, the aggravation of inflammation caused by silencing FGF21 can be alleviated by JAK2 inhibitor in vitro. Collectively, these findings unveil a potent protective effect of FGF21 against LPS-induced ALI by inhibiting the JAK2/STAT3 pathway, implying that FGF21 might be a novel and effective therapy for ALI.

Single-Cell Landscape and a Macrophage Subset Enhancing Brown Adipocyte Function in Diabetes.

BACKGRUOUND: Metabolic dysregulation is a hallmark of type 2 diabetes mellitus (T2DM), in which the abnormalities in brown adipose tissue (BAT) play important roles. However, the cellular composition and function of BAT as well as its pathological significance in diabetes remain incompletely understood. Our objective is to delineate the single-cell landscape of BAT-derived stromal vascular fraction (SVF) and their characteristic alterations in T2DM rats. METHODS: T2DM was induced in rats by intraperitoneal injection of low-dose streptozotocin and high-fat diet feeding. Single-cell mRNA sequencing was then performed on BAT samples and compared to normal rats to characterize changes in T2DM rats. Subsequently, the importance of key cell subsets in T2DM was elucidated using various functional studies. RESULTS: Almost all cell types in the BAT-derived SVF of T2DM rats exhibited enhanced inflammatory responses, increased angiogenesis, and disordered glucose and lipid metabolism. The multidirectional differentiation potential of adipose tissue-derived stem cells was also reduced. Moreover, macrophages played a pivotal role in intercellular crosstalk of BAT-derived SVF. A novel Rarres2+macrophage subset promoted the differentiation and metabolic function of brown adipocytes via adipose-immune crosstalk. CONCLUSION: BAT SVF exhibited strong heterogeneity in cellular composition and function and contributed to T2DM as a significant inflammation source, in which a novel macrophage subset was identified that can promote brown adipocyte function.

Corrigendum: Clinical value of metagenomic next-generation sequencing by Illumina and Nanopore for the detection of pathogens in bronchoalveolar lavage fluid in suspected community-acquired pneumonia patients.

[This corrects the article DOI: 10.3389/fcimb.2022.1021320.].

GGPPS Negatively Regulates the Formation of Neutrophil Extracellular Traps in Lipopolysaccharide-Induced Acute Lung Injury.

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are life-threatening diseases. Neutrophil extracellular traps (NETs) play a key role in lung damage. Geranylgeranyl diphosphate synthase (GGPPS) is associated with the development of inflammatory diseases. We aimed to explore the role of GGPPS in NETs formation in ARDS/ALI. First, lung pathological changes in lipopolysaccharide (LPS)-induced ALI mice after myeloid-specific GGPPS deletion were evaluated. The level of NETs formation was analyzed by immunofluorescence, PicoGreen assay and Western blotting. Next, we determined the role of GGPPS in NETs formation and underlying mechanisms using immunofluorescence, flow cytometry, DCFH-DA, and SYTOX GREEN staining in vitro. Finally, the correlation between GGPPS expression incirculating neutrophils and dsDNA levels in plasma was evaluated. Myeloid-specific GGPPS deletion mice showed increased NETs deposition in lung tissue and aggravated histopathological damage of lung tissue. In vitro, GGPPS deficiency in neutrophils resulted in increased NETs formation by Phorbol-12-myristate-13-acetate (PMA), which was reversed by Geranylgeranyl diphosphate (GGPP). In addition, inhibitors blocking protein kinase C (PKC) and NADPH-oxidase (NOX) decreased NETs formation induced by GGPPS deletion. Importantly, GGPPS expression in circulating neutrophils was decreased in ARDS patients compared with the healthy control, and the level of dsDNA in plasma of ARDS patients was negatively correlated with the GGPPS expression. Taken together, GGPPS deficiency in neutrophils aggravates LPS-induced lung injury by promoting NETs formation via PKC/NOX signaling. Thus, neutrophil GGPPS could be a key therapeutic target for ARDS.