Aquaporin 5 polymorphisms and rate of lung function decline in chronic obstructive pulmonary disease

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

dbAQP-SNP: a database of missense single-nucleotide polymorphisms in human aquaporins

Aquaporins and aquaglyceroporins belong to the superfamily of major intrinsic proteins (MIPs), and they transport water and other neutral solutes such as glycerol. These channel proteins are involved in vital physiological processes and are implicated in several human diseases. Experimentally determined structures of MIPs from diverse organisms reveal a unique hour-glass fold with six transmembrane helices and two half-helices. MIP channels have two constrictions formed by Asn-Pro-Ala (NPA) motifs and aromatic/arginine selectivity filters (Ar/R SFs). Several reports have found associations among single-nucleotide polymorphisms (SNPs) in human aquaporins (AQPs) with diseases in specific populations. In this study, we have compiled 2798 SNPs that give rise to missense mutations in 13 human AQPs. To understand the nature of missense substitutions, we have systematically analyzed the pattern of substitutions. We found several examples in which substitutions could be considered as non-conservative that include small to big or hydrophobic to charged residues. We also analyzed these substitutions in the context of structure. We have identified SNPs that occur in NPA motifs or Ar/R SFs, and they will most certainly disrupt the structure and/or transport properties of human AQPs. We found 22 examples in which missense SNP substitutions that are mostly non-conservative in nature have given rise to pathogenic conditions as found in the Online Mendelian Inheritance in Man database. It is most likely that not all missense SNPs in human AQPs will result in diseases. However, understanding the effect of missense SNPs on the structure and function of human AQPs is important. In this direction, we have developed a database dbAQP-SNP that contains information about all 2798 SNPs. This database has several features and search options that can help the user to find SNPs in specific positions of human AQPs including the functionally and/or structurally important regions. dbAQP-SNP (http://bioinfo.iitk.ac.in/dbAQP-SNP) is freely available to the academic community. Database URL http://bioinfo.iitk.ac.in/dbAQP-SNP.

Aquaporin-5 in breast cancer

The water channel aquaporin‐5 (AQP5) is essential in transepithelial water transport in secretory glands. AQP5 is ectopically overexpressed in breast cancer, where expression is associated with lymph node metastasis and poor prognosis. Besides the role in water transport, AQP5 has been found to play a role in cancer metastasis, migration, and proliferation. AQP5 has also been shown to be involved in the dysregulation of epithelial cell–cell adhesion; frequently observed in cancers. Insight into the underlying molecular mechanisms of how AQP5 contributes to cancer development and progression is essential for potentially implementing AQP5 as a prognostic biomarker and to develop targeted intervention strategies for the treatment of breast cancer patients.

Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease

The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.

A Repurposed Drug Screen for Compounds Regulating Aquaporin 5 Stability in Lung Epithelial Cells

Aquaporin 5 (AQP5) is expressed in several cell types in the lung and regulates water transport, which contributes to barrier function during injury and the composition of glandular secretions. Reduced AQP5 expression is associated with barrier dysfunction during acute lung injury, and strategies to enhance its expression are associated with favorable phenotypes. Thus, pharmacologically enhancing AQP5 expression could be beneficial. Here, we optimized a high-throughput assay designed to detect AQP5 abundance using a cell line stably expressing bioluminescent-tagged AQP5. We then screened a library of 1153 compounds composed of FDA-approved drugs for their effects on AQP5 abundance. We show compounds Niclosamide, Panobinostat, and Candesartan Celexitil increased AQP5 abundance, and show that Niclosamide has favorable cellular toxicity profiles. We determine that AQP5 levels are regulated in part by ubiquitination and proteasomal degradation in lung epithelial cells, and mechanistically Niclosamide increases AQP5 levels by reducing AQP5 ubiquitination and proteasomal degradation. Functionally, Niclosamide stabilized AQP5 levels in response to hypotonic stress, a stimulus known to reduce AQP5 levels. In complementary assays, Niclosamide increased endogenous AQP5 in both A549 cells and in primary, polarized human bronchial epithelial cells compared to control-treated cells. Further, we measured rapid cell volume changes in A549 cells in response to osmotic stress, an effect controlled by aquaporin channels. Niclosamide-treated A549 cell volume changes occurred more rapidly compared to control-treated cells, suggesting that increased Niclosamide-mediated increases in AQP5 expression affects functional water transport. Taken together, we describe a strategy to identify repurposed compounds for their effect on AQP5 protein abundance. We validated the effects of Niclosamide on endogenous AQP5 levels and in regulating cell-volume changes in response to tonicity changes. Our findings highlight a unique approach to screen for drug effects on protein abundance, and our workflow can be applied broadly to study compound effects on protein abundance in lung epithelial cells.

Effects of a Chinese herbal extract on the intestinal tract and aquaporin in Adriamycin-induced nephropathy

Wuling Decoction is a traditional Chinese medicine that has been used to open knots, benefit water, transform Qi, return fluid, and has a significant effect on strengthening the spleen and removing dampness. To explore the effects of Wuling Decoction on the intestinal tract and aquaporin in Adriamycin-induced nephropathy, 45 specific pathogen free (SPF) Wistar rats were randomly divided into a blank control group (5 rats), Dosing control group (10 rats), Adriamycin nephropathy model group (10 rats), diarrhea group (10 rats), and an Adriamycin nephropathy diarrhea model group (10 rats). The tissue localization of aquaporin (AQP) was determined by immunohistochemistry. The expression of AQP mRNA and protein was measured by RT-PCR and western blot analysis, respectively. The results indicated that Wuling Decoction causes excretion of AQP2 through the urine, regulates AQP2 levels, and exerts diuretic and anti-diarrheal effects. It also regulates the levels of antidiuretic hormone (ADH) and arginine vasopressin (AVP), affects water absorption rate, and reduces the level of cyclic adenosine monophosphate (cAMP) in each tissue, thus reducing the absorption of AQP2 to water. Wuling Decoction promoted AQP2 expression in the nephropathy model group and inhibited AQP2 expression in the diarrhea group. Wuling Decoction increased the expression of aquaporin in the intestinal tract, reduced the water content of stool by promoting the absorption of water in the intestinal tract, inhibited the expression of aquaporin and its regulatory factors in nephridia tissue, and reduced the reabsorption of water to increase urine volume, to decrease the occurrence of diarrhea.

Current Knowledge of Asthma-COPD Overlap (ACO) Genetic Risk Factors, Characteristics, and Prognosis

Asthma-COPD overlap (ACO) is a newly identified phenotype of chronic obstructive airway diseases with shared asthma and COPD features. Patients with ACO are poorly defined, and some evidence suggests that they have worse health outcomes and greater disease burden than patients with COPD or asthma. Generally, there is no evidence-based and universal definition for ACO; several consensus documents have provided various descriptions of the phenotype. In addition, the mechanisms underlying the development of ACO are not fully understood. Whether ACO is a distinct clinical entity with its particular discrete genetic determinant different from asthma and COPD alone or an intermediate phenotype with overlapping genetic markers within asthma and COPD spectrum of obstructive airway disease remains unproven. This review summarizes the current knowledge of the genetic risk factors, characteristics, and prognosis of ACO.

Signatures for chronic obstructive pulmonary disease (COPD) and asthma: a comparative genetic analysis

Background: Chronic obstructive pulmonary disease (COPD) and asthma are obstructive lung diseases which progress in severity with time. Environmental causes and genetic makeup of individuals play important roles in disease manifestation. The aim of present study was to search for diagnostic/prognostic biomarkers to differentiate COPD and asthma.Materials and methods: Seven ADAM33 and two AQP5 single-nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. The association of genotypes, haplotypes and allelic combination of variants in different genes was analyzed in 194 COPD, 150 asthma patients and 220 controls.Results: The genotype frequencies of SNPs V4(C/G), T1(T/C), S2(G/C) of ADAM33 and AQP5 A/G (rs3736309) were associated with COPD and asthma (P=0.038 to P<0.001), while S1(A/G) and F+1(C/T) were associated with asthma (both P<0.001) and V1(G/T) with 20 COPD (P<0.001). The allele frequencies of V4(C/G) (both P<0.001), V1(G/T) (both P<0.05), S2(G/C) (both P<0.01) and S1(A/G) (both P<0.05) were associated with COPD and asthma, while F+1(C/T) was associated only with asthma (P=0.005). Haplotypes of ADAM33 'GGTGGGT' (P=0.027), 'CGTCGGC' (P<0.001) and AQP5 'GA' and 'AG' (both P<0.001) were significant only in COPD.Conclusion: ADAM33 F+1(C/T) variant and allele combination 'GGTGGGTGA' may be specific markers for asthma, while AQP5 'AG' appeared as a haplotype associated only with COPD. These specific genetic biomarkers may be exploited to predict individual predisposition to COPD and asthma.

Deciphering the structure, function, expression and regulation of aquaporin-5 in cancer evolution

In recent years, the morbidity rate resulting from numerous types of malignant tumor has increased annually, and the treatment of tumors has been attracting an increasing amount of attention. A number of recent studies have revealed that the water channel protein aquaporin-5 (AQP5) has become a major player in multiple types of cancer. AQP5 is abnormally expressed in a variety of tumor tissues or cells and has multiple effects on certain biological functions of tumors, such as regulating the proliferation, apoptosis and migration of tumor cells. It has been suggested that AQP5 may play an important role in the process of tumor development, opening up a new field of tumor research. The present review highlighted the structure of AQP5 and its role in tumor progression. Furthermore, the expression of AQP5 in different malignant neoplasms was summarized. In addition, the influence of not only drugs, but also different compounds on AQP5 were summarized. In conclusion, according to the findings in the present review, AQP5 has potential as a novel therapeutic target in human cancer, and other AQPs should be similarly investigated.

Aquaporins in lung health and disease: Emerging roles, regulation, and clinical implications

Aquaporins (AQPs) aka water channels are a family of conserved transmembrane proteins (~30 kDa monomers) expressed in various organ systems. Of the 13 AQPs (AQP0 through AQP12) in the human body, four (AQPs 1, 3, 4, and 5) are expressed in the respiratory system. These channels are conventionally known for mediating transcellular fluid movements. Certain AQPs (aquaglyceroporins) have the capability to transport glycerol and potentially other solutes. There is an emerging body of literature unveiling the non-conventional roles of AQPs such as in cell proliferation and migration, gas permeation, signal potentiation, etc. Initial gene knock-out studies established a physiological role for lung AQPs, particularly AQP5, in maintaining homeostasis, by mediating fluid secretion from submucosal glands onto the airway surface liquid (ASL) lining. Subsequent studies have highlighted the functional significance of AQPs, particularly AQP1 and AQP5 in lung pathophysiology and diseases, including but not limited to chronic and acute lung injury, chronic obstructive pulmonary disease (COPD), other inflammatory lung conditions, and lung cancer. AQP1 has been suggested as a potential prognostic marker for malignant mesothelioma. Recent efforts are directed toward exploiting AQPs as targets for diagnosis, prevention, intervention, and/or treatment of various lung conditions. Emerging information on regulatory pathways and directed mechanistic research are posited to unravel novel strategies for these clinical implications. Future considerations should focus on development of AQP inhibitors, blockers, and modulators for therapeutic needs, and better understanding the role of lung-specific AQPs in inter-individual susceptibility to chronic lung diseases such as COPD and cancer.

Sevoflurane modulates AQPs (1,5) expression and endoplasmic reticulum stress in mice lung with allergic airway inflammation

Sevoflurane was found to show protective roles in mice with asthma, however, the mechanism of which needs further exploring. Aquaporins (AQPs) have been demonstrated to be involved in the pathogenesis of asthma, while endoplasmic reticulum stress has been reported to be related to many inflammatory diseases and involved in protein processing, including AQPs. The present study aimed to determine the role of sevoflurane in AQPs (AQP1,3,4,5) expression in mice with allergic airway inflammation and the probable mechanism. The increased number of inflammatory cells infiltrating the lung tissue, and the elevated levels of tumor necrosis factor-α (TNF-α) and interleukin (IL) 13 (IL-13) were all decreased after sevoflurane treatment (all P<0.05). Meanwhile, mRNA levels of AQP1 and AQP5 but not AQP3 and AQP4 were decreased in ovalbumin (OVA)-induced allergic mice lung. Both the decreased mRNA expression and protein levels of AQP1 and AQP5 in allergic lung tissues were reversed by sevoflurane treatment. Furthermore, we established that sevoflurane inhibited the OVA-induced protein increase in the endoplasmic reticulum (ER) stress markers BiP and C/EBP homologous protein (CHOP). Collectively, these findings suggested that sevoflurane modulated the expression and protein level of AOPs (AQP1, AQP5) as well as inhibited ER stress response in OVA-induced allergic airway inflammation of mice.

Aquaporins in health and disease

Aquaporins (AQPs) are transmembrane channel proteins that mainly facilitate the water translocation through the plasma cell membrane. For several years these proteins have been extensively examined for their biologic role in health and their potential implication in different diseases. Technological improvements associated with the methods employed to evaluate the functions of the AQPs have provided us with significant new knowledge. In this chapter, we will examine the role of AQPs in health and disease based on the latest currently available evidence.

Comparison and development of machine learning tools for the prediction of chronic obstructive pulmonary disease in the Chinese population

Background

Chronic obstructive pulmonary disease (COPD) is a major public health problem and cause of mortality worldwide. However, COPD in the early stage is usually not recognized and diagnosed. It is necessary to establish a risk model to predict COPD development.

Methods

A total of 441 COPD patients and 192 control subjects were recruited, and 101 single-nucleotide polymorphisms (SNPs) were determined using the MassArray assay. With 5 clinical features as well as SNPs, 6 predictive models were established and evaluated in the training set and test set by the confusion matrix AU-ROC, AU-PRC, sensitivity (recall), specificity, accuracy, F1 score, MCC, PPV (precision) and NPV. The selected features were ranked.

Results

Nine SNPs were significantly associated with COPD. Among them, 6 SNPs (rs1007052, OR = 1.671, P = 0.010; rs2910164, OR = 1.416, P < 0.037; rs473892, OR = 1.473, P < 0.044; rs161976, OR = 1.594, P < 0.044; rs159497, OR = 1.445, P < 0.045; and rs9296092, OR = 1.832, P < 0.045) were risk factors for COPD, while 3 SNPs (rs8192288, OR = 0.593, P < 0.015; rs20541, OR = 0.669, P < 0.018; and rs12922394, OR = 0.651, P < 0.022) were protective factors for COPD development. In the training set, KNN, LR, SVM, DT and XGboost obtained AU-ROC values above 0.82 and AU-PRC values above 0.92. Among these models, XGboost obtained the highest AU-ROC (0.94), AU-PRC (0.97), accuracy (0.91), precision (0.95), F1 score (0.94), MCC (0.77) and specificity (0.85), while MLP obtained the highest sensitivity (recall) (0.99) and NPV (0.87). In the validation set, KNN, LR and XGboost obtained AU-ROC and AU-PRC values above 0.80 and 0.85, respectively. KNN had the highest precision (0.82), both KNN and LR obtained the same highest accuracy (0.81), and KNN and LR had the same highest F1 score (0.86). Both DT and MLP obtained sensitivity (recall) and NPV values above 0.94 and 0.84, respectively. In the feature importance analyses, we identified that AQCI, age, and BMI had the greatest impact on the predictive abilities of the models, while SNPs, sex and smoking were less important.

Conclusions

The KNN, LR and XGboost models showed excellent overall predictive power, and the use of machine learning tools combining both clinical and SNP features was suitable for predicting the risk of COPD development.

Ovatodiolide suppresses inflammatory response in BEAS-2B cells by regulating the CREB/AQP5 pathway, and sensitizes nasopharyngeal carcinoma cells to radiation therapy

Due to the radiosensitivity of the airway epithelium, radiation-induced sinusitis or bronchitis is not uncommon, and makes mitigation of resulting inflammatory airway diseases a principal goal of many investigations. This study examined whether Ovatodiolide (Ova) sensitizes the human metastatic nasopharyngeal cancer (NPC) cell line, NPC-BM2, to irradiation using viability, clonogenicity and Western blot assays. Concurrently, we used varying concentrations of histamine and/or Ova to determine the anti-inflammatory potential of Ovatodiolide on normal bronchus epithelial BEAS-2B cells, as well as on the subcellular distribution of Aquaporin 5 (AQP5) and expression levels of p-CREB, AQP5, p38 MAPK, NF-κB, PI3K, Akt and ERK proteins. We demonstrated that Ova in synergism with irradiation inhibited NPC-BM2 cell viability and suppressed their clonogenicity. Immunofluorescence analysis revealed low-dose (≤ 2.5 μM) Ova reversed histamine-induced suppression of AQP5 expression, and abrogated histamine-enhanced NF-κB nuclear translocation, indicating Ova modulates the p38 MAPK/NF-κB signaling pathway and elicits p-CREB/AQP5-mediated antihistamine effects. Similarly, Ova deregulates the PI3K/Akt/ERK signaling in BEAS-2B cells, suggesting its cytoprotective potential. In conclusion, this study highlights the radio-sensitizing anticancer efficacy of Ova in human metastatic NPC cells, as well as its putative cytoprotective role in normal bronchial cells, for airway surface liquid maintenance and homeostasis during or after radiotherapy.

Aquaporins in the lung

The lung is the interface between air and blood where the exchange of oxygen and carbon dioxide occurs. The surface liquid that is directly exposed to the gaseous compartment covers both conducting airways and respiratory zone and forms the air-liquid interface. The barrier that separates this lining fluid of the airways and alveoli from the extracellular compartment is the pulmonary epithelium. The volume of the lining fluid must be kept in a range that guarantees an appropriate gas exchange and other functions, such as mucociliary clearance. It is generally accepted that this is maintained by balancing resorptive and secretory fluid transport across the pulmonary epithelium. Whereas osmosis is considered as the exclusive principle of fluid transport in the airways, filtration may contribute to alveolar fluid accumulation under pathologic conditions. Aquaporins (AQP) facilitate water flux across cell membranes, and as such, they provide a transcellular route for water transport across epithelia. However, their contribution to near-isosmolar fluid conditions in the lung still remains elusive. Herein, we discuss the role of AQPs in the lung with regard to fluid homeostasis across the respiratory epithelium.

Indirect Proton MR Imaging and Kinetic Analysis of 17O-Labeled Water Tracer in the Brain

Purpose:

The feasibility of steady-state sequences for ¹⁷O imaging was evaluated based on a kinetic analysis of the brain parenchyma and cerebrospinal fluid (CSF).

Materials and Methods:

The institutional review board approved this prospective study with written informed consent. Dynamic 2D or 3D steady-state sequences were performed in five and nine participants, respectively, with different parameters using a 3T scanner. During two consecutive dynamic scans, saline was intravenously administered for control purposes in the first scan, and 20% ¹⁷O-labeled water (1 mL/Kg) was administered in the second scan. Signal changes relative to the baseline were calculated, and kinetic analyses of the curves were conducted for all voxels. Region of interest analysis was performed in the brain parenchyma, choroid plexus, and CSF spaces.

Results:

Average signal drops were significantly larger in the ¹⁷O group than in the controls for most of the imaging parameters. Different kinetic parameters were observed between the brain parenchyma and CSF spaces. Average and maximum signal drops were significantly larger in the CSF spaces and choroid plexus than in the brain parenchyma. Bolus arrival, time to peak, and the first moment of dynamic curves of ¹⁷O in the CSF space were delayed compared to that in the brain parenchyma. Significant differences between the ventricle and subarachnoid space were also noted.

Conclusion:

Steady-state sequences are feasible for indirect ¹⁷O imaging with reasonable temporal resolution; this result is potentially important for the analysis of water kinetics and aquaporin function for several disorders.

Aquaporin-1 expression as an indicator in evaluating the efficacy of meloxicam in the treatment of ankylosing spondylitis: A comparative study

OBJECTIVE

The key objective of the study was to investigate the correlation between the expression of aquaporin-1 (AQP1) and the efficacy of meloxicam and expressions of pro-inflammatory cytokines in ankylosing spondylitis (AS).

METHODS

40 AS patients whom had received meloxicam were recruited and subsequently placed into the experiment, while 40 healthy individuals were recruited as control group. Clinical indicators were detected before treatment (0 week), and at 2, 4, 6, 8, 10 and 12 week intervals after treatment, which included various assessments including Ankylosing Spondylitis 20% (ASAS20) response, Bath ankylosing spondylitis disease activity index (BASDAI), visual analog scale (VAS) for back pain, duration of morning stiffness, Bath ankylosing spondylitis functional index (BASFI), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels. Healthy volunteers were examined for ESR and CRP levels. The mRNA and protein expressions of AQP1 and pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2), in peripheral blood mononuclear cells (PBMCs) were detected 6 and 12 weeks after treatment using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Correlation of expressions of AQP1, efficacy of meloxicam and expression of pro-inflammatory cytokines were determined via Pearson correlation analysis.

RESULTS

Following 12 weeks of meloxicam treatment, the ASAS20 response reached 93.7±3.61%. 6 weeks after treatment, BASDAI, VAS for back pain, duration of morning stiffness, BASFI, ESR, and CRP levels all exhibited considerably reduced levels compared to the initial levels observed prior to the commencement of treatment. Compared with before treatment, the expressions of TNF-α, IL-2 and AQP1 mRNA and protein all displayed decreases in the experiment group after both 6 and 12-week periods of treatment. Pre and post treatment levels of TNF-α, IL-2 and AQP1 mRNA and protein expressions were higher than those in the control group. The expressions of AQP1 mRNA and protein in the experiment group were positively correlated with clinical indicators and expressions of pro-inflammatory cytokines.

CONCLUSION

Our findings indicated that AQP1 was both highly expressed and positively correlated with the efficacy of meloxicam and expressions of pro-inflammatory cytokines in AS patients, thereby highlighting the promise of meloxicam as a potential indicator in predicting the efficacy in the treatment of AS.

Effect of Abnormal Savda Munziq, a Traditional Uighur Herbal Medicine, on Pulmonary Function and Aquaporins of COPD Rat Model with Abnormal Savda Syndrome

OBJECTIVE

To investigate the effect of abnormal savda munziq (ASM) on the pulmonary function and expression of lung-specific aquaporins in the rat model of chronic obstructive pulmonary disease with abnormal savda syndrome (ASSCOPD).

METHODS

Eighty male rats were randomized into ASSCOPD, COPD, and control groups. ASSCOPD was further categorized into ASM and non-ASM groups. COPD model was established by combining fumigation with airway instillation of elastase; ASSCOPD model was developed based on COPD by induction with dry cold diet, cold dry environment, and plantar electric stimulation. ASM was administered twice daily. The pulmonary function was evaluated based on respiration. The mRNA and protein levels of AQPs were estimated by real-time PCR and Western blot, respectively.

RESULTS

MV, TV, the mRNA level of AQP5, and the protein expression of AQP1, AQP4, and AQP5 were increased in ASMCOPD compared to ASSCOPD.

CONCLUSION

The pulmonary function was impaired in ASSCOPD group; the expression of AQP1, AQP4, and AQP5 was decreased at protein and mRNA levels in ASSCOPD group. ASM can improve the pulmonary function in ASSCOPD for MV and TV. ASM could elevate the protein expression of AQP1, AQP4, and AQP5 and the mRNA level of AQP5 in lung tissue.

Genetic variants of CDH13 determine the susceptibility to chronic obstructive pulmonary disease in a Chinese population

AIM

Adiponectin has been implicated in the development of chronic obstructive pulmonary disease (COPD). The CDH13 gene encodes T-cadherin that is an adiponectin receptor, and genetic variants of CDH13 determine blood adiponectin levels. The aim of this study was to investigate the effects of CDH13 variants on COPD susceptibility in a Chinese population.

METHODS

Ten single-nucleotide polymorphisms (SNP) in CDH13 were screened using the SNaPshot method in 279 COPD patients and 367 control subjects. Association of genotypes or haplotypes constructed from these loci with COPD was analyzed in different genetic models.

RESULTS

Among the 10 SNPs tested, rs4783244 and rs12922394 exhibited significant differences in allele or genotype frequencies between COPD patients and control subjects, whereas 8 other SNPs did not. The minor allele T was associated with decreased risk of COPD in the recessive model at rs4783244 (OR=0.42, P=0.023) and in the dominant model at rs12922394 (OR=0.70, P=0.022). The genotype TT at either rs4783244 or rs12922394 was associated with a significantly low level of plasma adiponectin when compared to genotypes GG and CC (P<0.05). Haplotypes GC in block 1 (rs4783244-rs12922394) as well as GTAC and ATGT in block 3 (rs4783266-rs11640522-rs11646849-rs11860282) significantly increased the risk of COPD, whereas haplotypes TT in block 1, TG in block 2 (rs11646011- rs11640875) and ATGC in block 3 were protective against COPD.

CONCLUSION

CDH13 genetic variants determine Chinese individuals' susceptibility to COPD and thus are efficient genetic biomarkers for early detection of COPD.

Effects of hydrogen-rich saline on aquaporin 1, 5 in septic rat lungs

Aquaporin 1(AQP1) and AQP5 have an important role in eliminating extravascular lung water, an increase of which contributes to lung injury in patients with sepsis and its consequent mortality. It has been reported that hydrogen-rich saline (HRS) has protective effects against sepsis-related lung injury. In this study, we hypothesized that the protective effect occurred by preserving the expression of AQP1 and AQP5. To test this hypothesis, male Sprague-Dawley rats received intratracheal administration of lipopolysaccharide (LPS) followed by intraperitoneal injection of HRS. Lung function, wet-to-dry weight ratio, and histopathology scores were determined. The expression of AQP1 and AQP5 at the messenger RNA and protein levels, as well as the involved pathways, was explored by quantitative polymerase chain reaction and Western blot. LPS significantly impaired lung function and downregulated the expression of AQP1 and AQP5 in the rat lung, all of which were attenuated by HRS treatment. Moreover, HRS treatment inhibited LPS-induced activation of p38 mitogen-activated protein kinase and jun N-terminal kinase, which is associated with LPS-induced downregulation of AQP1 and AQP5.

Expression of aquaporins in bronchial tissue and lung parenchyma of patients with chronic obstructive pulmonary disease

Background

Aquaporins AQP1 and AQP5 are highly expressed in the lung. Recent studies have shown that the expression of these proteins may be mechanistically involved in the airway inflammation and in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the expression of AQP1 and AQP5 in the bronchial tissue and the lung parenchyma of patients with COPD and COPD-resistant smokers.

Methods

Using a case–control design, we selected a group of 15 subjects with COPD and 15 resistant smokers (smokers without COPD) as a control, all of whom were undergoing lung resection surgery due to a lung neoplasm. We studied the expression of AQP1 and AQP5 in the bronchial tissue and the lung parenchyma by means of immunohistochemistry and reverse-transcription real-time polymerase chain reaction. Tissue expression of AQP1 and AQP5 was semi-quantitatively assessed in terms of intensity and expression by immunohistochemistry using a 4-point scale ranging from 0 (none) to 3 (maximum).

Results

There were no significant differences in gene expression between COPD patients and resistant smokers both in the bronchial tissue and in the lung parenchyma. However, AQP1 gene expression was 2.41-fold higher in the parenchyma of smokers with COPD compared to controls, whereas the AQP5 gene showed the opposite pattern, with a 7.75-fold higher expression in the bronchus of smokers with COPD compared with controls. AQP1 and AQP5 proteins were preferentially expressed in endothelial cells, showing a higher intensity for AQP1 (66.7% of cases with an intensity of 3, and 93.3% of subjects with an extension of 3 among patients with COPD). Subtle interstitial disease was associated with type II pneumocyte hyperplasia and an increased expression of AQP1.

Conclusions

This study provides pilot observations on the differences in AQP1 and AQP5 expression between COPD patients and COPD-resistant smokers. Our findings suggest a potential role for AQP1 in the pathogenesis of COPD.

Critical role of aquaporins in interleukin 1β (IL-1β)-induced inflammation

Rapid changes in cell volume characterize macrophage activation, but the role of water channels in inflammation remains unclear. We show here that, in vitro, aquaporin (AQP) blockade or deficiency results in reduced IL-1β release by macrophages activated with a variety of NLRP3 activators. Inhibition of AQP specifically during the regulatory volume decrease process is sufficient to limit IL-1β release by macrophages through the NLRP3 inflammasome axis. The immune-related activity of AQP was confirmed in vivo in a model of acute lung inflammation induced by crystals. AQP1 deficiency is associated with a marked reduction of both lung IL-1β release and neutrophilic inflammation. We conclude that AQP-mediated water transport in macrophages constitutes a general danger signal required for NLRP3-related inflammation. Our findings reveal a new function of AQP in the inflammatory process and suggest a novel therapeutic target for anti-inflammatory therapy.

Water permeability of the mammalian cochlea: functional features of an aquaporin-facilitated water shunt at the perilymph-endolymph barrier

The cochlear duct epithelium (CDE) constitutes a tight barrier that effectively separates the inner ear fluids, endolymph and perilymph, thereby maintaining distinct ionic and osmotic gradients that are essential for auditory function. However, in vivo experiments have demonstrated that the CDE allows for rapid water exchange between fluid compartments. The molecular mechanism governing water permeation across the CDE remains elusive. We computationally determined the diffusional (PD) and osmotic (Pf) water permeability coefficients for the mammalian CDE based on in silico simulations of cochlear water dynamics integrating previously derived in vivo experimental data on fluid flow with expression sites of molecular water channels (aquaporins, AQPs). The PD of the entire CDE (PD = 8.18 × 10(-5) cm s(-1)) and its individual partitions including Reissner's membrane (PD = 12.06 × 10(-5) cm s(-1)) and the organ of Corti (PD = 10.2 × 10(-5) cm s(-1)) were similar to other epithelia with AQP-facilitated water permeation. The Pf of the CDE (Pf = 6.15 × 10(-4) cm s(-1)) was also in the range of other epithelia while an exceptionally high Pf was determined for an epithelial subdomain of outer sulcus cells in the cochlear apex co-expressing AQP4 and AQP5 (OSCs; Pf = 156.90 × 10(-3) cm s(-1)). The Pf/PD ratios of the CDE (Pf/PD = 7.52) and OSCs (Pf/PD = 242.02) indicate an aqueous pore-facilitated water exchange and reveal a high-transfer region or "water shunt" in the cochlear apex. This "water shunt" explains experimentally determined phenomena of endolymphatic longitudinal flow towards the cochlear apex. The water permeability coefficients of the CDE emphasise the physiological and pathophysiological relevance of water dynamics in the cochlea in particular for endolymphatic hydrops and Ménière's disease.

Mutations in AQP5, encoding a water-channel protein, cause autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma

Autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma is characterized by the adoption of a white, spongy appearance of affected areas upon exposure to water. After exome sequencing, missense mutations were identified in AQP5, encoding water-channel protein aquaporin-5 (AQP5). Protein-structure analysis indicates that these AQP5 variants have the potential to elicit an effect on normal channel regulation. Immunofluorescence data reveal the presence of AQP5 at the plasma membrane in the stratum granulosum of both normal and affected palmar epidermis, indicating that the altered AQP5 proteins are trafficked in the normal manner. We demonstrate here a role for AQP5 in the palmoplantar epidermis and propose that the altered AQP5 proteins retain the ability to form open channels in the cell membrane and conduct water.

Aquaporin 5 regulates cigarette smoke induced emphysema by modulating barrier and immune properties of the epithelium

Chronic obstructive pulmonary disease (COPD) causes significant morbidity and mortality. Cigarette smoke, the most common risk factor for COPD, induces airway and alveolar epithelial barrier permeability and initiates an innate immune response. Changes in abundance of aquaporin 5 (AQP5), a water channel, can affect epithelial permeability and immune response after cigarette smoke exposure. To determine how AQP5-derived epithelial barrier modulation affects epithelial immune response to cigarette smoke and development of emphysema, WT and AQP5^−/− mice were exposed to cigarette smoke (CS). We measured alveolar cell counts and differentials, and assessed histology, mean-linear intercept (MLI), and surface-to-volume ratio (S/V) to determine severity of emphysema. We quantified epithelial-derived signaling proteins for neutrophil trafficking, and manipulated AQP5 levels in an alveolar epithelial cell line to determine specific effects on neutrophil transmigration after CS exposure. We assessed paracellular permeability and epithelial turnover in response to CS. In contrast to WT mice, AQP5^−/− mice exposed to 6 months of CS did not demonstrate a significant increase in MLI or a significant decrease in S/V compared with air-exposed mice, conferring protection against emphysema. After sub-acute (4 weeks) and chronic (6 mo) CS exposure, AQP5^−/− mice had fewer alveolar neutrophil but similar lung neutrophil numbers as WT mice. The presence of AQP5 in A549 cells, an alveolar epithelial cell line, was associated with increase neutrophil migration after CS exposure. Compared with CS-exposed WT mice, neutrophil ligand (CD11b) and epithelial receptor (ICAM-1) expression were reduced in CS-exposed AQP5^−/− mice, as was secreted LPS-induced chemokine (LIX), an epithelial-derived neutrophil chemoattractant. CS-exposed AQP5^−/− mice demonstrated decreased type I pneumocytes and increased type II pneumocytes compared with CS-exposed WT mice suggestive of enhanced epithelial repair. Absence of AQP5 protected against CS-induced emphysema with reduced epithelial permeability, neutrophil migration, and altered epithelial cell turnover which may enhance repair.

Genome-wide study identifies two loci associated with lung function decline in mild to moderate COPD

Accelerated lung function decline is a key COPD phenotype; however, its genetic control remains largely unknown. We performed a genome-wide association study using the Illumina Human660W-Quad v.1_A BeadChip. Generalized estimation equations were used to assess genetic contributions to lung function decline over a 5-year period in 4,048 European American Lung Health Study participants with largely mild COPD. Genotype imputation was performed using reference HapMap II data. To validate regions meeting genome-wide significance, replication of top SNPs was attempted in independent cohorts. Three genes (TMEM26, ANK3 and FOXA1) within the regions of interest were selected for tissue expression studies using immunohistochemistry. Two intergenic SNPs (rs10761570, rs7911302) on chromosome 10 and one SNP on chromosome 14 (rs177852) met genome-wide significance after Bonferroni. Further support for the chromosome 10 region was obtained by imputation, the most significantly associated imputed SNPs (rs10761571, rs7896712) being flanked by observed markers rs10761570 and rs7911302. Results were not replicated in four general population cohorts or a smaller cohort of subjects with moderate to severe COPD; however, we show novel expression of genes near regions of significantly associated SNPS, including TMEM26 and FOXA1 in airway epithelium and lung parenchyma, and ANK3 in alveolar macrophages. Levels of expression were associated with lung function and COPD status. We identified two novel regions associated with lung function decline in mild COPD. Genes within these regions were expressed in relevant lung cells and their expression related to airflow limitation suggesting they may represent novel candidate genes for COPD susceptibility.

Salubrinal protects against cigarette smoke extract-induced HBEpC apoptosis likely via regulating the activity of PERK-eIF2α signaling pathway

BACKGROUND AND AIMS

Endoplasmic reticulum (ER) stress plays an important role in cigarette smoke extract (CSE)-induced apoptotic cell death, which is an important pathogenic factor of chronic obstructive pulmonary disease (COPD). The aim of this study was to explore the role of the PERK-eIF2 pathway in CSE-induced human bronchial epithelial (HBE) cell apoptosis and to evaluate the protective effects and possible mechanism of salubrinal (Sal) on CSE-induced HBE cell apoptosis.

METHODS

Normal human bronchial epithelial cells (HBEpC) were cultured and then treated with CSE alone or together with Sal or preincubated with or without PERK siRNA. Expressions of p-PERK/PERK, p-eIF2α/eIF2α, and caspase 3 and 4 were detected with PCR, Western blot, and immunofluorescence. Apoptosis was detected using AnnexinV-PI flow cytometry.

RESULTS

CSE induced apoptotic cell death and caused a dynamic change in PERK-eIF2α pathway activity following the course of CSE exposure. The knockdown of PERK suppressed the expression of both PERK and p-eIF2a and caused a great increase in cell apoptosis. Sal could eliminate the effects of PERK knockdown, protecting the cells against the CSE insult, and this protection was accomplished through maintaining the homeostasis of PERK- eIF2α pathway.

CONCLUSIONS

PERK-eIF2α pathway mediates the CSE-induced HBE cell apoptosis. The intactness of PERK-eIF2α pathway is crucial for HBE cell survival under CSE insult. Sal can protect against CSE-induced HBE cell apoptosis, and this effect is likely achieved through maintaining the homeostasis of PERK- eIF2α pathway.

Updates on the COPD gene list

A genetic contribution to develop chronic obstructive pulmonary disease (COPD) is well established. However, the specific genes responsible for enhanced risk or host differences in susceptibility to smoke exposure remain poorly understood. The goal of this review is to provide a comprehensive literature overview on the genetics of COPD, highlight the most promising findings during the last few years, and ultimately provide an updated COPD gene list. Candidate gene studies on COPD and related phenotypes indexed in PubMed before January 5, 2012 are tabulated. An exhaustive list of publications for any given gene was looked for. This well-documented COPD candidate-gene list is expected to serve many purposes for future replication studies and meta-analyses as well as for reanalyzing collected genomic data in the field. In addition, this review summarizes recent genetic loci identified by genome-wide association studies on COPD, lung function, and related complications. Assembling resources, integrative genomic approaches, and large sample sizes of well-phenotyped subjects is part of the path forward to elucidate the genetic basis of this debilitating disease.