The involvement of aquaporin 1 in the hepatopulmonary syndrome rat serum-induced migration of pulmonary arterial smooth muscle cells via the p38-MAPK pathway

A Novel Scoring System for Risk Assessment of Elderly Patients With Cytogenetically Normal Acute Myeloid Leukemia Based on Expression of Three AQP1 DNA Methylation-Associated Genes

Background: Aquaporin 1 (AQP-1), a transmembrane water channel protein, has been proven to involve in many diseases' progression and prognosis. This research aims to explore the prognostic value of AQP-1 in elderly cytogenetically normal acute myeloid leukemia (CN-AML).

Methods: Complete clinical and expression data of 226 elderly patients (aged > 60) with cytogenetically normal acute myeloid leukemia (CN-AML) were downloaded from the databases of The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). We have explored prognostic significance of AQP-1, investigated the underlying mechanism, and developed a novel scoring system for the risk assessment of elderly patients with AML based on AQP1 methylation.

Results: In the first and second independent group, AQP1 shows lower expression in CN-AML than normal people, while high AQP1 expression and AQP1 promoter hypomethylation were related to better overall survival (OS; P < 0.05). To understand the underlying mechanisms, we investigated differentially expressed genes (DEGs), miRNA and lncRNA associated with AQP1 methylation. A three-gene prognostic signature based on AQP1 methylation which was highly correlated with OS was established, and the performance was validated by Permutation Test and Leave-one-out Cross Validation method. Furthermore, an independent cohort was used to verify the prognostic value of this model.

Conclusions: AQP1 methylation could serve as an independent prognostic biomarker in elderly CN-AML, and may provide new insights for the diagnosis and treatment for elderly CN-AML patients.

MiR145-5p inhibits proliferation of PMVECs via PAI-1 in experimental hepatopulmonary syndrome rat pulmonary microvascular hyperplasia

Hepatopulmonary syndrome (HPS) is a triad of advanced liver disease, intrapulmonary vasodilatation and arterial hypoxemia. Increasing evidence shows that HPS is associated with pulmonary microvascular hyperplasia. The aim of this work was to investigate the underlying mechanism of miR-145 in regulating the proliferation of pulmonary microvascular endothelial cells (PMVECs) and angiogenesis in HPS via plasminogen activator inhibitor-1 (PAI-1). To test this, morphology score and number of pulmonary microvascular were assessed in lung tissues from rats with HPS by Hematoxylin and Eosin (H&E) staining. Expression levels of PAI-1 were assessed in lung tissues from HPS rats, as well as in PMVECs treated with HPS rat serum. We also selected the putative microRNA binding site on PAI-1 by bioinformatics analysis. Then, miR145-3p and miR145-5p expression levels in the lungs and PMVECs of rats were detected by qRT-PCR because miR145-5p is a microRNA binding site on PAI-1. In addition, the effects of miR-145-5p regulation on PAI-1 were examined by upregulation and downregulation of miR-145-5p and specific lentivirus transfection was used to overexpress and knockdown PAI-1 to assess PAI-1 function on PMVECs proliferation. Our data showed that levels of PAI-1 expression in lung tissue of rats increased significantly when rats were treated with common bile duct ligation. We found that levels of miR-145-5p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-145-5p dramatically inhibited PMVECs proliferation. We further verified PAI-1 as a novel and direct target of miR-145-5p in HPS. MiR-145-5p inhibits PAI-1 synthesis and the expression changes of PAI-1 directly affect the proliferation of PMVECs. We concluded that miR-145-5p negatively regulates PMVEC proliferation through PAI-1 expression. In addition, overexpression of miR-145-5p may prove beneficial as a therapeutic strategy for HPS treatment.

Summary: Our findings provide proof of principle that microRNAs may be useful for the future development of novel therapeutic strategies in HPS.

Aquaporin-1 attenuates macrophage-mediated inflammatory responses by inhibiting p38 mitogen-activated protein kinase activation in lipopolysaccharide-induced acute kidney injury

Objective

This study was designed to investigate the role of AQP1 in the development of LPS-induced AKI and its potential regulatory mechanisms in the inflammatory responses of macrophages.

Methods

Male Wistar rats were injected intraperitoneally with LPS, and biochemical and histological renal damage was assessed. The levels of inflammatory mediators, macrophage markers and AQP1 in blood and kidney tissues were assessed by ELISA. RTPCR was used to assess changes in the relative levels of AQP1 mRNA induced by LPS. Western blot and immunofluorescence analyses were performed to assay the activation of the p38 MAPK and NF-κB pathways, respectively. The same detection methods were used in vitro to determine the regulatory mechanisms underlying AQP1 function.

Results

AQP1 mRNA levels were dramatically decreased in AKI rats following the increased expression of inflammatory factors. In vitro experiments demonstrated that silencing the AQP1 gene increased inflammatory mediator secretion, altered the classical activation of macrophages, greatly enhanced the phosphorylation of p38 and accelerated the translocation of NF-κB. Furthermore, these results were blocked by doramapimod, a p38 inhibitor. Therefore, these effects were mediated by the increased phosphorylation of p38 MAPK.

Conclusion

Our results suggest that altered AQP1 expression may be associated with the development of inflammation in AKI. AQP1 plays a protective role in modulating acute renal injury and can attenuate macrophage-mediated inflammatory responses by downregulating p38 MAPK activity in LPS-induced RAW264.7 cells. The pharmacological targeting of AQP1-mediated p38 MAPK signalling may provide a novel treatment approach for AKI.

Loss of cell polarity regulated by PTEN/Cdc42 enrolled in the process of Hepatopulmonary Syndrome

One central factor in hepatopulmonary syndrome (HPS) pathogenesis is pulmonary vascular remodelling (PVR) which involves dysregulation of proliferation and migration in pulmonary microvascular endothelial cells (PMVECs). Growing evidence suggests that Apical/basolateral polarity plays an important role in cell proliferation, migration, adhesion and differentiation. In this study, we explored whether cell polarity is involved and critical in experimental HPS rats that are induced by common bile duct ligation (CBDL). Cell polarity related proteins were analysed in CBDL rats lung and PMVECs under the HPS serum stimulation by immunofluorescence assay. Cdc42/PTEN activity, cell proliferation and migration and Annexin A2 (AX2) in PMVECs were determined, respectively. Cell polarity related proteins, lost their specialized luminal localization in PMVECs of the CBDL rat. The loss of cell polarity was induced by abnormal activity of Cdc42, which was strongly enhanced by the interaction between p‐PTEN and Annexin A2 in PMVECs, after treatment with serum from CBDL rats. It led to over‐proliferation and high migration ability of PMVECs. Down‐regulation of PTEN‐Cdc42 activity in PMVECs restored cell polarity and thus reduced their ability of migration and proliferation. Our study suggested that the loss of cell polarity plays a critical role in the pathogenesis of HPS‐associated PVR and may become a potentially effective therapeutic target.

Hepatopulmonary syndrome: What we know and what we would like to know

Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage. Knowledge about the subject is still only partial. The majority of the information about the etiopathogenesis of HPS has been obtained through experiments on animals. Reported prevalence in patients who are candidates for a liver transplantation (LT) varies between 4% and 32%, with a predominance of mild or moderate cases. Although it is generally asymptomatic it does have an impact on their quality of life and survival. The diagnosis requires taking an arterial blood gas sample of a seated patient with alveolar-arterial oxygen gradient (AaO₂) ≥ 15 mm Hg, or ≥ 20 mm Hg in those over 64 years of age. The IPVD are identified through a transthoracic contrast echocardiography or a macroaggregated albumin lung perfusion scan (^99mTc-MAA). There is currently no effective medical treatment. LT has been shown to reverse the syndrome and improve survival rates, even in severe cases. Therefore the policy of prioritizing LT would appear to increase survival rates. This paper takes a critical and clinical look at the current understanding of HPS, as well as the controversies surrounding it and possible future research.

Identification of downstream target genes regulated by the nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate signal pathway in pulmonary hypertension

Objective

To investigate the downstream target genes regulated by the nitric oxide–soluble guanylate cyclase–cyclic guanosine monophosphate (NO-sGC-cGMP) signal pathway and their possible roles in the pathogenesis of pulmonary hypertension (PH).

Methods

Digital gene expression tag profiling was performed to identify genes that are differentially expressed after activation of the NO-sGC-cGMP signal pathway in human pulmonary artery smooth muscles cells using 8-bromo-cyclic guanosine monophosphate, BAY 41-2272 and BAY 60-2770. Results were confirmed using real-time polymerase chain reaction. Gene ontology and signal transduction network analyses were also performed.

Results

A number of genes were differentially expressed, including MMP1, SERPINB2, GREM1 and IL8. A total of 68 gene ontology terms and seven pathways were found to be associated with these genes. Most of these genes are involved in cell proliferation, cell migration and apoptosis, which may contribute to the pathological pulmonary vascular remodelling in PH.

Conclusion

These results may provide new insights into the molecular mechanisms of PH.