Tocilizumab use in giant cell arteritis: comparing Pharmaceutical Benefits Scheme eligible and ineligible cases in South Australia.

Tocilizumab (TCZ) is increasingly used as a steroid-sparing agent in giant cell arteritis (GCA), but there are strict Pharmaceutical Benefits Scheme (PBS) restrictions for its use in Australia. Patients who do not meet the PBS criteria can obtain TCZ through public hospital individual patient use (IPU) schemes which may not be universally accessible. We compared patients receiving IPU-approved TCZ with patients receiving PBS-subsidised TCZ and found IPU approvals were granted mainly for visual loss, a serious complication of GCA, in patients who otherwise failed to meet PBS criteria. Further studies demonstrating that TCZ is comparatively more effective than prednisolone monotherapy, as well as cost-effective, are needed to substantiate the rationale for expanding PBS approval criteria.

Impact of the COVID-19 Pandemic on Health Care Access and Diagnosis of Pulmonary Arterial Hypertension Among Patients With Systemic Sclerosis.

OBJECTIVE: Regular clinical assessment for complications of systemic sclerosis (SSc) such as pulmonary arterial hypertension (PAH) is essential for early institution of therapy and improved outcomes. The objective of this study was to determine the impact of COVID-19 pandemic-related restrictions on health care access of patients with SSc, including screening for PAH. METHODS: South Australian and Victorian patients enrolled in the Australian Scleroderma Cohort Study were surveyed about their perceptions of the impact of the pandemic on mental well-being, access to medications, investigations, and management of SSc. Frequency of annual rheumatology assessments, pulmonary function tests (PFT), and transthoracic echocardiography (TTE) to screen for PAH were compared with rates from before the pandemic. RESULTS: A total of 312 of 810 patients with SSc responded (38.5% response); 273 were female (87.5%), the median age was 64.7 years, 77.2% had limited disease, the median illness duration was 15.6 years, 15.7% were immunosuppressed, 32.1% had interstitial lung disease, and 6.4% had PAH. A total of 65.7% of consultations were by telehealth, of which 81.2% were by telephone. Compared with respondents in South Australia (n = 109), Victorian respondents (n = 203) experiencing prolonged lockdown, reported reduced access to their rheumatologist (49.3% vs 27.9%; P = 0.004), greater use of consultation by video (17.3% vs 2.1%; P = 0.008), greater health care disruption (49.0% vs 23.2%; P < 0.001), and worse mental health (P = 0.002). Respondents reported reduced access to PFT and TTE (31.7% and 22.5%, respectively). Annual visits, PFT, TTE, and new diagnoses of PAH were reduced in 2020 to 2022 compared with 2011 to 2019. CONCLUSION: The COVID-19 pandemic-related disruption to health care for patients with SSc was associated with worse mental health and reduced screening and diagnosis of PAH, which may impact long-term outcomes.

Systemic Markers of Monocyte Activation in Acute Pulmonary Oedema.

BACKGROUND: Hydrostatic lung injury followed by pulmonary remodelling variably complicates cardiogenic acute pulmonary oedema (APO). Pulmonary remodelling may be regulated by the balance between distinct phenotypes of pulmonary macrophages; activated/inflammatory (M1), and reparative/anti-inflammatory (M2), derived from circulating monocyte populations. The aim of this study was to identify biomarkers in peripheral blood that are consistent with hydrostatic lung injury and pulmonary remodelling in APO and which follow the variable clinical course. METHODS: To examine peripheral markers of lung inflammation, resolution and remodelling, 18 patients, admitted to the intensive care unit (ICU) with a clinical diagnosis of APO, were enrolled. Admission, 12- and 24-hour post-admission bloods were assayed for cytokines by ELISA (R&D Systems, Minneapolis, MN, USA) and leukocyte surface markers by flow cytometry. RESULTS: Admission PaO2 to FiO2 ratio was positively correlated with Mon 2 (intermediate) monocyte prevalence, through increasing ratio of CD16+ monocytes to CD11b+ and CD40+ monocytes, and negatively correlated with Mon 1 (classical) monocyte prevalence, through decreasing ratio of CD16+ monocytes to CD62L+. Secondary cohort analysis compared 10 APO patients with established chronic heart failure (CHF) to eight without CHF. An increase in monocyte chemotactic peptide (MCP)-1, monocyte prevalence, and CD16-CD62L+ monocytes with CHF, all characteristic of monocyte activation to a Mon 1 phenotype, were found in the CHF APO patients. CONCLUSIONS: Increased systemic monocyte prevalence and expression of cell surface markers suggest a Mon 1 profile in CHF patients during episodes of APO. Future studies should define the role of systemic monocyte prevalence and activation in decompensated CHF.

Reduced Surfactant Contributes to Increased Lung Stiffness Induced by Rapid Inspiratory Flow.

INTRODUCTION: The mechanism of fast inspiratory flow rate (VI') induced lung injury is unclear. As fast VI' increases hysteresis, a measure of surface tension at the air-liquid interface, surfactant release or function may be important. This experimental study examines the contribution of impaired surfactant release or function to dynamic-VILI. METHODS: Isolated perfused lungs from male Sprague Dawley rats were randomly allocated to four groups: a long or short inspiratory time (Ti = 0.5 s; slow VI' or Ti = 0.1 s; fast VI') at PEEP of 2 or 10 cmH2O. Tidal volume was constant (7 ml/kg), with f = 60 breath/min. Forced impedance mechanics (tissue elastance (Htis), tissue resistance (Gtis) and airway resistance (Raw) were measured at 30, 60 and 90 min following which the lung was lavaged for surfactant phospholipids (PL) and disaturated PL (DSP). RESULTS: Fast VI' resulted in a stiffer lung. Concurrently, PL and DSP were decreased in both tubular myelin rich and poor fractions. Phospholipid decreases were similar with PEEP. In a subsequent cohort, laser confocal microscopy-based assessment demonstrated increased cellular injury with increased VI' at both 30 and 90 min ventilation. CONCLUSION: Rapid VI' may contribute to ventilator induced lung injury (VILI) through reduced surfactant release and/or more rapid reuptake despite unchanged tidal stretch.

When RON MET TAM in Mesothelioma: All Druggable for One, and One Drug for All?

Malignant pleural mesothelioma (MPM) is an aggressive inflammatory cancer with a poor survival rate. Treatment options are limited at best and drug resistance is common. Thus, there is an urgent need to identify novel therapeutic targets in this disease in order to improve patient outcomes and survival times. MST1R (RON) is a trans-membrane receptor tyrosine kinase (RTK), which is part of the c-MET proto-oncogene family. The only ligand recognized to bind MST1R (RON) is Macrophage Stimulating 1 (MST1), also known as Macrophage Stimulating Protein (MSP) or Hepatocyte Growth Factor-Like Protein (HGFL). In this study, we demonstrate that the MST1-MST1R (RON) signaling axis is active in MPM. Targeting this pathway with a small molecule inhibitor, LCRF-0004, resulted in decreased proliferation with a concomitant increase in apoptosis. Cell cycle progression was also affected. Recombinant MST1 treatment was unable to overcome the effect of LCRF-0004 in terms of either proliferation or apoptosis. Subsequently, the effect of an additional small molecular inhibitor, BMS-777607 (which targets MST1R (RON), MET, Tyro3, and Axl) also resulted in a decreased proliferative capacity of MPM cells. In a cohort of MPM patient samples, high positivity for total MST1R by IHC was an independent predictor of favorable prognosis. Additionally, elevated expression levels of MST1 also correlated with better survival. This study also determined the efficacy of LCRF-0004 and BMS-777607 in xenograft MPM models. Both LCRF-0004 and BMS-777607 demonstrated significant anti-tumor efficacy in vitro, however BMS-777607 was far superior to LCRF-0004. The in vivo and in vitro data generated by this study indicates that a multi-TKI, targeting the MST1R/MET/TAM signaling pathways, may provide a more effective therapeutic strategy for the treatment of MPM as opposed to targeting MST1R alone.

Geriatric Nursing Sensitive Indicators and quality nursing care for the older person: a scoping review protocol.

REVIEW QUESTION: The objective of the scoping review is to locate and describe the international literature relating to Nursing Sensitive Indicators (NSIs) and their use in evaluating geriatric care. Specifically the review question is: What definitions and key concepts of NSIs are identified in the current literature that are relevant in evaluating nursing care of the older person?Findings from the review will inform future research and health care responses to support the provision of quality nursing care to the older person.

Novel protein constituents of pathological ocular pseudoexfoliation syndrome deposits identified with mass spectrometry.

Purpose: Pseudoexfoliation (PEX) syndrome is an age-related progressive disease of the extracellular matrix with ocular manifestations. PEX is clinically diagnosed by the presence of extracellular exfoliative deposits on the anterior surface of the ocular lens. PEX syndrome is a major risk factor for developing glaucoma, the leading cause of irreversible blindness in the world, and is often associated with the development of cataract. PEX reportedly coexists with Alzheimer disease and increases the risk of heart disease and stroke. PEX material deposited on the anterior surface of the ocular lens is highly proteinaceous, complex, and insoluble, making deciphering the protein composition of the material challenging. Thus, to date, only a small proportion of the protein composition of PEX material is known. The aim of this study was to decipher the protein composition of pathological PEX material deposited on the ocular lens in patients and advance the understanding of pathophysiology of PEX syndrome. Methods: Liquid-chromatography and tandem mass spectrometry (LC-MS/MS) was employed to discover novel proteins in extracts of neat PEX material surgically isolated from patients (n = 4) with PEX syndrome undergoing cataract surgery. A sub-set of the identified proteins was validated with immunohistochemistry using lens capsule specimens from independent patients (n=3); lens capsules from patients with cataract but without PEX syndrome were used as controls (n=4). Expression of transcripts of the validated proteins in the human lens epithelium was analyzed with reverse transcription PCR (RT-PCR). Functional relationships among the proteins identified in this study and genes and proteins previously implicated in the disease were bioinformatically determined using InnateDB. Results: Peptides corresponding to 66 proteins, including ten proteins previously known to be present in PEX material, were identified. Thirteen newly identified proteins were chosen for validation. Of those proteins, 12 were found to be genuine components of the material. The novel protein constituents include apolipoproteins (APOA1 and APOA4), stress response proteins (CRYAA and PRDX2), and blood-related proteins (fibrinogen and hemoglobin subunits), including iron-free hemoglobin. The gene expression data suggest that the identified stress-response proteins and hemoglobin are contributed by the lens epithelium and apolipoproteins and fibrinogen by the aqueous humor to the PEX material. Pathway analysis of the identified novel protein constituents and genes or proteins previously implicated in the disease reiterated the involvement of extracellular matrix organization and degradation, elastic fiber formation, and complement cascade in PEX syndrome. Network analysis suggested a central role of fibronectin in the pathophysiology of the disease. The identified novel protein constituents of PEX material also shed light on the molecular basis of the association of PEX syndrome with heart disease, stroke, and Alzheimer disease. Conclusions: This study expands the understanding of the protein composition of pathological PEX material deposited on the ocular lens in patients with PEX syndrome and provides useful insights into the pathophysiology of this disease. This study together with the previous study by our group (Sharma et al. Experimental Eye Research 2009;89(4):479-85) demonstrate that using neat PEX material, devoid of the underlying lens capsule, for proteomics analysis is an effective approach for deciphering the protein composition of complex and highly insoluble extracellular pathological ocular deposits present in patients with PEX syndrome.

The Effect of Aquaporin 1-Inhibition on Vasculogenic Mimicry in Malignant Mesothelioma.

Malignant mesothelioma (MM) is an aggressive malignancy of the serosal membranes, with poor overall survival and quality of life. Limited targeted treatment strategies exist due to restricted knowledge of pathogenic pathways. Vasculogenic mimicry (VM) is a newly described phenomenon associated with increased aggressiveness in other malignancies, and has been characterized in MM. Normal mesothelium expresses aquaporin 1 (AQP1) and retained expression has been associated with improved survival in MM. AQP1 is expressed by normal vascular endothelium and is involved in mediating MM cell motility and proliferation. We investigated the role of AQP1 in VM, and its interaction with the pro-angiogenic factor vascular endothelial growth factor A (VEGFA), which is variably expressed in MM. Matrigel VM assays were performed using NCI-H226 and NCI-H28 MM cell lines and primary cells in hypoxia and normoxia. The synthetic blocker AqB050 and siRNA were used to inhibit AQP1, and bevacizumab was used to inhibit VEGF. Inhibition of AQP1 resulted in increased VEGFA secretion by MM cells and reduced VM in MM cell lines in hypoxia but not normoxia. No change in VM was seen in MM primary cells. Combined inhibition of AQP1 and VEGF had no effect on VM in normoxia. In a heterotopic xenograft mouse model, AqB050 treatment did not alter vessel formation. AQP1 may interact with VEGFA and play a role in VM, especially under hypoxic conditions, but the heterogeneity of MM cells may result in different dominant pathways between patients.

Vasculogenic mimicry in malignant mesothelioma: an experimental and immunohistochemical analysis.

Vasculogenic mimicry, the process in which cancer cells form angiomatoid structures independent of or in addition to host angiogenesis has been recorded in several otherwise non-endothelial malignant neoplasms. This study describes evidence of routine vascular mimicry by human mesothelioma cell lines in vitro, when the cell lines are cultured alone or co-cultured with human umbilical vascular endothelial cells, with the formation of angiomatoid tubular networks. Vasculogenic mimicry is also supported by immunohistochemical demonstration of human-specific anti-mitochondria antibody labelling of tumour-associated vasculature of human mesothelioma cells xenotransplanted into nude mice, and by evidence of vascular mimicry in some biopsy samples of human malignant mesotheliomas. These studies show mosaic interlacing of cells that co-label or label individually for immunohistochemical markers of endothelial and mesothelial differentiation. If vascular mimicry in mesothelioma can be characterised more fully, this may facilitate identification of more specific and targeted therapeutic approaches such as anti-angiogenesis in combination with chemotherapy and immunotherapy or other therapeutic approaches.

Usefulness of Aquaporin 1 as a Prognostic Marker in a Prospective Cohort of Malignant Mesotheliomas.

(1) BACKGROUND: Malignant mesothelioma (MM) is an aggressive tumour of the serosal membranes, associated with exposure to asbestos. Survival is generally poor, but prognostication for individual patients is difficult. We recently described Aquaporin 1 (AQP1) as independent prognostic factor in two separate retrospective cohorts of MM patients. Here we assess the usefulness of AQP1 prospectively, and determine the inter-observer agreement in assessing AQP1 scores; (2) METHODS: A total of 104 consecutive cases of MM were included. Sufficient tissue for immunohistochemistry was available for 100 cases, and these cases were labelled for AQP1. Labelling was assessed by two pathologists. Complete clinical information and follow up was available for 91 cases; (3) RESULTS: Labelling of ≥50% of tumour cells for AQP indicated improved prognosis in a univariate model (median survival 13 versus 8 months, p = 0.008), but the significance was decreased in a multivariate analysis. Scoring for AQP1 was robust, with an inter-observer kappa value of 0.722, indicating substantial agreement between observers; (4) CONCLUSION: AQP1 is a useful prognostic marker that can be easily incorporated in existing diagnostic immunohistochemical panels and which can be reliably interpreted by different pathologists.

Fibulin-3 levels in malignant pleural mesothelioma are associated with prognosis but not diagnosis.

BACKGROUND: Fibulin-3 (FBLN3) was recently presented as a promising novel biomarker for malignant pleural mesothelioma (MPM), warranting independent validation studies. METHODS: ELISA was used to measure cellular and secreted FBLN3 in cell lines, in plasma of xenograft tumour-bearing mice, in plasma from two independent series of MPM and non-MPM patients and in pleural fluid from a third series. Diagnostic and prognostic potential of FBLN3 was assessed by receiver operating characteristics curve analysis and Kaplan-Meier method, respectively. RESULTS: FBLN3 was expressed in all MPM and benign mesothelial cell lines tested, and a correlation was observed between cellular protein expression and secreted levels. Human FBLN3 was detectable in plasma of tumour-bearing mice, suggesting that MPM cells contribute to levels of circulating FBLN3. Plasma FBLN3 was significantly elevated in MPM patients from the Sydney cohort, but not the Vienna cohort, but the diagnostic accuracy was low (63%, (95% CI: 50.1-76.4) and 56% (95% CI: 41.5-71.0), respectively). Although FBLN3 levels in pleural effusions were not significantly different between cases and controls, FBLN3 levels in pleural effusion fluid were found to be independently associated with prognosis (hazard ratio of 9.92 (95% CI: 2.14-45.93)). CONCLUSIONS: These data confirm the potential prognostic value of pleural effusion FBLN3, but question the diagnostic value of this protein in MPM patients.

Blockade of aquaporin 1 inhibits proliferation, motility, and metastatic potential of mesothelioma in vitro but not in an in vivo model.

BACKGROUND: Malignant mesothelioma (MM) is an aggressive tumor of the serosal membranes, mostly the pleura. It is related to asbestos exposure and has a poor prognosis. MM has a long latency period, and incidence is predicted to remain stable or increase until 2020. Currently, no biomarkers for a specific targeted therapy are available. Previously, we observed that expression of aquaporin 1 (AQP1) was an indicator of prognosis in two independent cohorts. Here we determine whether AQP1 inhibition has therapeutic potential in the treatment of MM. METHODS: Functional studies were performed with H226 cells and primary MM cells harvested from pleural effusions. AQP1 expression and mesothelial phenotype was determined by immunohistochemistry. AQP1 function was inhibited by a pharmacological blocker (AqB050) or AQP1-specific siRNA. Cell proliferation, migration, and anchorage-independent cell growth were assessed. A nude mouse heterotopic xenograft model of MM was utilised for the in vivo studies. RESULTS: Inhibition of AQP1 significantly decreases cell proliferation, metastatic potential, and motility without inducing nonspecific cytotoxicity or increasing apoptosis. In vivo blockade of AQP1 had no biologically significant effect on growth of established tumours. CONCLUSIONS: Targeted blockade of AQP1 restricts MM growth and migration in vitro. Further work is warranted to fully evaluate treatment potential in vivo.

Pulmonary effects of chronic elevation in microvascular pressure differ between hypertension and myocardial infarct induced heart failure.

BACKGROUND: Chronic heart failure (CHF) following coronary artery ligation and myocardial infarction in the rat leads to a homeostatic reduction in surface tension with associated alveolar type II cell hyperplasia and increased surfactant content, which functionally compensates for pulmonary collagen deposition and increased tissue stiffness. To differentiate the effects on lung remodelling of the sudden rise in pulmonary microvascular pressure (Pmv) with myocardial infarction from its consequent chronic elevation, we examined a hypertensive model of CHF. METHODS: Cardiopulmonary outcomes due to chronic pulmonary capillary hypertension were assessed at six and 15 weeks following abdominal aortic banding (AAB) in the rat. RESULTS: At six weeks post-surgery, despite significantly elevated left ventricular end-diastolic pressure, myocardial hypertrophy and increased left ventricular internal circumference in AAB rats compared with sham operated controls (p≤0.003), lung weights and tissue composition remained unchanged, and lung compliance was normal. At 15 weeks post-surgery increased lung oedema was evident in AAB rats (p=0.002) without decreased lung compliance or evidence of tissue remodelling. CONCLUSION: Despite chronically elevated Pmv, comparable to that resulting from past myocardial infarction (LVEDP>19mmHg), there is no evidence of pulmonary remodelling in the AAB model of CHF.

Chronic elevation of pulmonary microvascular pressure in chronic heart failure reduces bi-directional pulmonary fluid flux.

AIMS: Chronic heart failure leads to pulmonary vascular remodelling and thickening of the alveolar-capillary barrier. We examined whether this protective effect may slow resolution of pulmonary oedema consistent with decreased bi-directional fluid flux. METHODS AND RESULTS: Seven weeks following left coronary artery ligation, we measured both fluid flux during an acute rise in left atrial pressure (n = 29) and intrinsic alveolar fluid clearance (n = 45) in the isolated rat lung. Chronic elevation of pulmonary microvascular pressure prevented pulmonary oedema and decreased lung compliance when left atrial pressure was raised to 20 cmH2O, and was associated with reduced expression of endothelial aquaporin 1 (P = 0.03). However, no other changes were found in mediators of fluid flux or cellular fluid channels. In isolated rat lungs, chronic LV dysfunction (LV end-diastolic pressure and infarct circumference) was also inversely related to alveolar fluid clearance (P ≤ 0.001). The rate of pulmonary oedema reabsorption was estimated by plasma volume expansion in eight patients with a previous clinical history of chronic heart failure and eight without, who presented with acute pulmonary oedema. Plasma volume expansion was reduced at 24 h in those with chronic heart failure (P = 0.03). CONCLUSIONS: Chronic elevation of pulmonary microvascular pressure in CHF leads to decreased intrinsic bi-directional fluid flux at the alveolar-capillary barrier. This adaptive response defends against alveolar flooding, but may delay resolution of alveolar oedema.

Association of genetic variants in the TMCO1 gene with clinical parameters related to glaucoma and characterization of the protein in the eye.

PURPOSE: Glaucoma is the leading cause of irreversible blindness worldwide. Primary open angle glaucoma (POAG) is the most common subtype. We recently reported association of genetic variants at chromosomal loci, 1q24 and 9p21, with POAG. In this study, we determined association of the most significantly associated single nucleotide polymorphism (SNP) rs4656461, at 1q24 near the TMCO1 gene, with the clinical parameters related to glaucoma risk and diagnosis, and determined ocular expression and subcellular localization of the human TMCO1 protein to understand the mechanism of its involvement in POAG. METHODS: Association of SNP rs4656461 with five clinical parameters was assessed in 1420 POAG cases using linear regression. The TMCO1 gene was screened for mutations in 95 cases with a strong family history and advanced disease. Ocular expression and subcellular localization of the TMCO1 protein were determined by immunolabeling and as GFP-fusion. RESULTS: The data suggest that individuals homozygous for the rs4656461 risk allele (GG) are 4 to 5 years younger at diagnosis than noncarriers of this allele. Our data demonstrate expression of the TMCO1 protein in most tissues in the human eye, including the trabecular meshwork and retina. However, the subcellular localization differs from that reported in other studies. We demonstrate that the endogenous protein localizes to the cytoplasm and nucleus in vivo and ex vivo. In the nucleus, the protein localizes to the nucleoli. CONCLUSIONS: This study shows a relationship between genetic variation in and around TMCO1 with age at diagnosis of POAG and provides clues to the potential cellular function/s of this gene.

Association of TCF4 and CLU polymorphisms with Fuchs' endothelial dystrophy and implication of CLU and TGFBI proteins in the disease process.

Fuchs' endothelial dystrophy (FED) is a disease affecting the corneal endothelium. Recent studies reported significant association of polymorphisms in the TCF4 (transcription factor 4) gene, and a borderline association of PTPRG (protein tyrosine phosphatase, receptor type, G) variants with late-onset FED in Caucasians from the United States. Association of TCF4 has also been reported in the Chinese population. We aimed to determine association of the reported polymorphisms in TCF4 and PTPRG, and association of polymorphisms in the candidate genes ZEB1 (zinc-finger E-box binding homoebox 1), COL8A2 (collagen, type VIII, alpha 2), TGFBI (transforming growth factor, ß-induced) and CLU (clusterin) in Australian cases. We also compared the expression of TGFBI and CLU proteins between FED and normal whole corneas. In all, 30 single-nucleotide polymorphisms (SNPs) from the candidate genes were genotyped in 103 cases and 275 controls. Each SNP and haplotype was assessed for association with the disease. SNP analysis identified an association of TCF4 (rs613872 (P=5.25 × 10(-15), OR=4.05), rs9954153 (P=3.37 × 10(-7), OR=2.58), rs2286812 (P=4.23 × 10(-6), OR=2.55) and rs17595731 (P=3.57 × 10(-5), OR=3.79)), CLU (rs17466684; P=0.003, OR=1.85) and one haplotype of TGFBI SNPs (P=0.011, OR=2.29) with FED in Caucasian Australians. No evidence for genetic association of PTPRG, ZEB1 and COL8A2 was found. Immunohistochemistry showed differential expression of CLU and TGFBI proteins in FED-affected compared with normal corneas. In conclusion, variation in TCF4, CLU and TGFBI, but not PTPRG, ZEB1 and COL8A2 genes are associated with FED in Caucasian Australian cases. Differential expression of CLU and TGFBI proteins in FED-affected corneas provides novel insights into the disease mechanism.

Aquaporin 1 is an independent prognostic factor in pleural malignant mesothelioma.

BACKGROUND: Malignant mesothelioma (MM) is an aggressive cancer of serosal membranes, mostly pleura. It is related to asbestos exposure and its incidence in most industrialized countries is projected to remain stable or to increase until 2020. Prognosis remains poor. Clinical prognostic scoring systems lack precision. No prognostic tissue markers are available. Aquaporin 1 (AQP1) is a cell membrane channel involved in water transport, cell motility, and proliferation. A blocker and an agonist are available. METHODS: Two independent cohorts of MM were studied. Cohort 1 consisted of 80 consecutive patients who underwent radical surgery (extrapleural pneumonectomy [EPP]). Cohort 2 included 56 conservatively managed patients from another institution. Clinical information was obtained from files. Diagnoses were histologically verified. Immunohistochemical labeling for AQP1 was performed on tumor tissue and the percentage of positive cells was scored. RESULTS: We demonstrated expression of AQP1 in normal and neoplastic mesothelium at the apical aspect of the cell, in keeping with a role in water transport. For both cohorts, expression of AQP1 by ≥50% of tumor cells was associated with significantly enhanced survival (9.4 months vs 30.4 months in EPP patients and 5 months vs 15 months in conservatively treated patients). This was independent of established prognostic factors, including histologic subtype, pathologic stage, sex, and age at time of diagnosis. CONCLUSION: Expression of AQP1 correlated significantly with prognosis in MM, irrespective of treatment or established prognostic factors. Immunohistochemical labeling for AQP1 should be included in the routine histopathologic workup. An agonist or blocker may become useful for treatment.