2-Deoxy-glucose ameliorates the peritoneal mesothelial and endothelial barrier function perturbation occurring due to Peritoneal Dialysis fluids exposure.

Peritoneal dialysis (PD) and prolonged exposure to PD fluids (PDF) induce peritoneal membrane (PM) fibrosis and hypervascularity, leading to functional PM degeneration. 2-deoxy-glucose (2-DG) has shown potential as PM antifibrotic by inhibiting hyper-glycolysis induced mesothelial-to-mesenchymal transition (MMT). We investigated whether administration of 2-DG with several PDF affects the permeability of mesothelial and endothelial barrier of the PM. The antifibrotic effect of 2-DG was confirmed by the gel contraction assay with embedded mesothelial (MeT-5A) or endothelial (EA.hy926) cells cultured in Dianeal® 2.5 % (CPDF), BicaVera® 2.3 % (BPDF), Balance® 2.3 % (LPDF) with/without 2-DG addition (0.2 mM), and qPCR for αSMA, CDH2 genes. Moreover, 2-DG effect was tested on the permeability of monolayers of mesothelial and endothelial cells by monitoring the transmembrane resistance (RTM), FITC-dextran (10, 70 kDa) diffusion and mRNA expression levels of CLDN-1 to -5, ZO1, SGLT1, and SGLT2 genes. Contractility of MeT-5A cells in CPDF/2-DG was decreased, accompanied by αSMA (0.17 ± 0.03) and CDH2 (2.92 ± 0.29) gene expression fold changes. Changes in αSMA, CDH2 were found in EA.hy926 cells, though αSMA also decreased under LPDF/2-DG incubation (0.42 ± 0.02). Overall, 2-DG mitigated the PDF-induced alterations in mesothelial and endothelial barrier function as shown by RTM, dextran transport and expression levels of the CLDN-1 to -5, ZO1, and SGLT2. Thus, supplementation of PDF with 2-DG not only reduces MMT but also improves functional permeability characteristics of the PM mesothelial and endothelial barrier.

Differential effects of biocompatible peritoneal dialysis fluids on human mesothelial and endothelial cells in 2D and 3D phenotypes.

INTRODUCTION: Peritoneal dialysis (PD) is a life maintaining treatment in patients with end-stage renal disease. Its chronic application leads to peritoneal mesothelial layer denudation and fibrotic transformation along with vascular activation of inflammatory pathways. The impact of different PD fluids (PDF) on mesothelial and endothelial cell function and repair mechanisms are not comprehensively described. MATERIALS AND METHODS: Mesothelial (MeT-5A) and endothelial cells (EA.hy926) were cultured in 1:1 ratio with cell medium and different PDF (icodextrin-based, amino acid-based, and glucose-based). Cell adhesion, cell migration, and cell proliferation in 2D and spheroid formation and collagen gel contraction assays in 3D cell cultures were performed. RESULTS: Cell proliferation and cell-mediated gel contraction were both significantly decreased in all conditions. 3D spheroid formation was significantly reduced with icodextrin and amino acid PDF, but unchanged with glucose PDF. Adhesion was significantly increased by amino acid PDF in mesothelial cells and decreased by icodextrin and amino acid PDF in endothelial cells. Migration capacity was significantly decreased in mesothelial cells by all three PDF, while endothelial cells remained unaffected. CONCLUSIONS: In 3D phenotypes the effects of PDF are more uniform in both mesothelial and endothelial cells, mitigating spheroid formation and gel contraction. On the contrary, effects on 2D phenotypes are more uniform in the icodextrin and amino acid PDF as opposed to glucose ones and affect mesothelial cells more variably. 2D and 3D comparative assessments of PDF effects on the main peritoneal membrane cell barriers, the mesothelial and endothelial, could provide useful translational information for PD studies.

Effects of pharmacological primary cilium disturbance in the context of in vitro 2D and 3D malignant pleura mesothelioma.

INTRODUCTION: Primary cilium (PC) is a single non-motile antenna-like organelle composed of a microtubule core axon originating from the mother centriole of the centrosome. The PC is universal in all mammalian cells and protrudes to the extracellular environment receiving mechanochemical cues that it transmits in the cell. AIM: To investigate the role of PC in mesothelial malignancy in the context of two-dimensional (2D) and three-dimensional (3D) phenotypes. MATERIALS AND METHODS: The effect of pharmacological deciliation [using ammonium sulphate (AS) or chloral hydrate (CH)] and PC elongation [using lithium chloride (LC)] on cell viability, adhesion, and migration (2D cultures) as well as in mesothelial sphere formation, spheroid invasion and collagen gel contraction (3D cultures) was investigated in benign mesothelial MeT-5A cells and in malignant pleural mesothelioma (MPM) cell lines, M14K (epithelioid) and MSTO (biphasic), and primary malignant pleural mesothelioma cells (pMPM). RESULTS: Pharmacological deciliation or elongation of the PC significantly affected cell viability, adhesion, migration, spheroid formation, spheroid invasion and collagen gel contraction in MeT-5A, M14K, MSTO cell lines and in pMPM cells compared to controls (no drug treatment). CONCLUSIONS: Our findings indicate a pivotal role of the PC in functional phenotypes of benign mesothelial cells and MPM cells.

HΜGB1/sRAGE levels differ significantly between transudates and exudates.

High mobility group box 1(HMGB1) protein operates as an alarmin with multiple roles in immunity and cell homeostasis. It is highly expressed in epithelial barrier sites and acts via the binding to the receptor for advanced glycation end products (RAGE). Production of HMGB1 and soluble RAGE (sRAGE), a decoy receptor for HMGB1, has been implicated in several pulmonary diseases, but both have been scarcely investigated in pleural diseases. The aim of this study was to determine the levels of HMGB1 and sRAGE in transudative, malignant and parapneumonic pleural effusions (PEs) and to investigate the effect of low and high HMGB1 pleural fluid levels on MeT-5A cell adhesion, migration and spheroid formation, in each group. HMGB1 and sRAGE levels were significantly lower and higher in transudative PEs compared to malignant and parapneumonic PEs, respectively. Patients above 65 years of age had significantly lower HMGB1 and higher sRAGE levels compared to patients below 65 years old. Furthermore, incubation of MeT-5A cells with malignant or parapneumonic PEs bearing low or high levels of HMGB1 yielded significant differential effects on MeT-5A cell adhesion, migration and spheroid formation. In all types of effusions, high HMGB1 levels correlated with more adherence compared to low HMGB1 levels. In transudative and malignant PEs high HMGB1 levels correlated with decreased migration of MeT-5A cells while in parapneumonic ones the effect was the opposite. Only samples from parapneumonic PEs high in HMGB1 achieved uniform spheroid formation. These results reveal a clinical context-dependent effect of the HMGB1/sRAGE axis in PEs.

Cell and extracellular matrix interaction models in benign mesothelial and malignant pleural mesothelioma cells in 2D and 3D in-vitro.

Malignant pleural mesothelioma (MPM) is an aggressive tumour that grows in the pleural cavity. MPM spheroids released in the pleural fluid can form new tumour foci. Cell-cell, cell-extracellular matrix (ECM) interactions in 2D and 3D impact malignant cell behaviour during cell adhesion, migration, proliferation and epithelial-mesenchymal transition (EMT). In this study, epithelioid, biphasic and sarcomatoid MPM cell types as well as benign mesothelial cells were tested with regards to the above phenotypes. Fibronectin (FN) and homologous cell-derived extracellular matrix (hcd-ECM) treated substratum differentially affected the above phenotypes. 3D MPM spheroid invasion was higher in FN-collagen matrices in the epithelioid and biphasic cells, while 3D cell cultures of epithelioid and sarcomatoid MPM cells in FN-collagen showed a higher contractility compared to hcd-ECM-collagen. Cell aggregates demonstrated invasive behaviour in hcd-ECM matrices alone. Our results suggest that ECM and the dimensionality affect malignant cell behaviour during cell culture studies.

Malignant mesothelioma cells secrete natriuretic peptides: Data and diagnostic clinical implications.

BACKGROUND AND OBJECTIVE: Mesothelial cells and cardiomyocytes have shared embryonic mesodermal origin. Cardiomyocytes release BNP under stretch. We searched whether malignant mesothelioma cells also secrete BNP and if so, this has a meaningful impact. METHODS: Part I: Prospectively, patients with pleural lesions on CT having malignant mesothelioma effusions (MME, n = 13) were compared to patients with malignant effusions with pleural lesions (MEa, n = 14). Age-matched patients with ME without pleural lesions (MEb, n = 16) and non-malignant effusions (NME, n = 25) were analysed. Part II: Retrospectively, samples from patients with mesothelioma (n = 14), lung cancer (n = 8) or heart failure (n = 9) were used. BNP was measured in pleural fluid and blood/plasma. Part III: BNP was assessed in the culture supernatants of benign (MeT-5A) and malignant mesothelioma cell lines (M14K-epithelioid, MSTO-biphasic and ZL34-sarcomatoid) (n = 10 per cell line in three different biological replicates). RESULTS: In vitro, BNP concentration was significantly higher in the supernatant of all malignant cell lines than benign ones (P < 0.01), denoting BNP's production from the former. The pleural fluid to blood BNP ratio in MME was extremely high in Part I and Part II subjects (28.3 ± 12.1 and 25.9 ± 8.6, respectively) versus 1.1 ± 0.3 and 0.4 ± 0.1 in Part I ME and NME, respectively (P < 0.0001), and 0.8 ± 0.1 and 0.4 ± 0.1 in Part II ME and NME, respectively (P < 0.0001). BNP ratio ≥2.11 in Part I had 92% sensitivity and 94.5% specificity for MME (P < 0.0001). CONCLUSION: BNP is secreted from malignant mesothelial cells. In clinical practice, the pleural fluid to blood BNP ratio can help in the diagnosis of malignant mesothelioma.

Benign Pleural Mesothelial Cells Have Higher Osmotic Water Permeability than Malignant Pleural Mesothelioma Cells and Differentially Respond to Hyperosmolality.

BACKGROUND/AIMS: Cell volume regulation is a critical mechanism for cell homeostasis and depends on the osmotic water permeability (Pf) of the cell plasma membrane. The Pf of human mesothelial cells is unknown although they contribute to serosal fluid turnover. METHODS: In this study we measured the osmotic water permeability of benign human mesothelial cells (MeT-5A) and of epithelioid (M14K) and sarcomatoid (ZL34) malignant pleural mesothelioma (MPM) cells in response to acute hyperosmotic stress. We also assessed the changes in their Pf after preconditioning with 4% glucose for 24 hours. In both cases we also assessed the role of AQP1 inhibition (0.1 mM HgCl2) on the Pf. Finally, we assessed corresponding changes in the AQP1 plasma membrane availability by immunofluorescence. RESULTS: We report that MeT-5A cells have a significantly higher Pf as compared to M14K and ZL34 MPM cells [4.85E-03±2.37E-03 cm/sec (n=17) versus 2.74E-03±0.74E-03 cm/sec (n=11) and 2.86E-03±0.11E-03 cm/sec (n=11)]. AQP1 inhibition significantly decreased the Pf in all cells lines (p<0.001 in all cases). High glucose preconditioning for 24 hours significantly increased MeT-5A Pf (p<0.001), did not influence M14K Pf (p=0.19) and significantly reduced ZL34 Pf (p=0.02). Comparing cell lines after high glucose preconditioning, MeT-5A Pf was significantly higher than that of M14K and ZL34 MPM cells and the AQP1 inhibition effect was significant in MeT-5A and M14K cells. These results were corroborated by AQP1 immunofluorescence. CONCLUSION: We provide evidence for a differential regulation of Pf in benign and MPM cells that require further mechanistic investigation.

Encapsulating Peritoneal Sclerosis: Pathophysiology and Current Treatment Options.

Encapsulating peritoneal sclerosis (EPS) is a life-threatening complication of long-term peritoneal dialysis (PD), which may even occur after patients have switched to hemodialysis (HD) or undergone kidney transplantation. The incidence of EPS varies across the globe and increases with PD vintage. Causative factors are the chronic exposure to bioincompatible PD solutions, which cause long-term modifications of the peritoneum, a high peritoneal transporter status involving high glucose concentrations, peritonitis episodes, and smoldering peritoneal inflammation. Additional potential causes are predisposing genetic factors and some medications. Clinical symptoms comprise signs of intestinal obstruction and a high peritoneal transporter status with incipient ultrafiltration failure. In radiological, macro-, and microscopic studies, a massively fibrotic and calcified peritoneum enclosed the intestine and parietal wall in such cases. Empirical treatments commonly used are corticosteroids and tamoxifen, which has fibrinolytic properties. Immunosuppressants like azathioprine, mycophenolate mofetil, or mTOR inhibitors may also help with reducing inflammation, fibrin deposition, and collagen synthesis and maturation. In animal studies, N-acetylcysteine, colchicine, rosiglitazone, thalidomide, and renin-angiotensin system (RAS) inhibitors yielded promising results. Surgical treatment has mainly been performed in severe cases of intestinal obstruction, with varying results. Mortality rates are still 25-55% in adults and about 14% in children. To reduce the incidence of EPS and improve the outcome of this devastating complication of chronic PD, vigorous consideration of the risk factors, early diagnosis, and timely discontinuation of PD and therapeutic interventions are mandatory, even though these are merely based on empirical evidence.

Mesothelioma Mortality Rates in Greece for the Period 2005-2015 Is Increased Compared to Previous Decades.

Background and Objective: To present summary statistics regarding malignant mesothelioma (MM) mortality in Greece during the period 2005-2015 and compare it with previous decades, along with gender, age and geographical area analysis. Materials and Methods: The Hellenic Statistical Authority provided the data, which included all deaths for the period 1983 to 2015 that mentioned MM as the death cause in the corresponding death certificate. MM mortality rates have been calculated with respect to gender, age, and geographical location in Greece. Furthermore, a comparison analysis was made among three eleven consecutive year periods, in order to assess potential changes in the mortality rates. Results: The MM mortality rate has significantly increased during the period 2005-2015 both in males and females compared to earlier decades. The maximum number of MM deaths has shifted to an older age group of 70-80 years during the 2005-2015 period as compared to that of 1983-2004 in both genders. Additionally, MM mortality rates have significantly increased in all geographical areas except for the Epirus Prefecture. Conclusions: Our results demonstrate an increased MM mortality rate in Greece for the decade 2005-2015 as compared to the two previous decades. This increase is possibly due to the fact that the peak in asbestos production and use in Greece was in mid 1990s, while the asbestos ban came in effect in 2005. Based on these findings the MM epidemic in Greece has not yet peaked, therefore it is important to implement screening strategies for early MM detection.

Influence of AQP1 on cell adhesion, migration, and tumor sphere formation in malignant pleural mesothelioma is substratum- and histological-type dependent.

Malignant pleural mesothelioma (MPM) is an aggressive cancer. MPM cells express aquaporin-1 (AQP1) that in other cancers has been shown to participate in the tumor metastasis processes. However, in MPM patients AQP1 overexpression is an independent prognostic factor favoring survival. In this study we aimed at evaluating the role of AQP1 in cell adhesion, migration, and tumor sphere formation in nonmalignant mesothelial cells (MeT-5A) and in epithelioid (M14K) and sarcomatoid (ZL34) MPM cell lines. We used fibronectin (FN) or homologous cell-derived extracellular martrix (ECM) substratum to investigate the role of AQP1 in these experimental phenotypes, inhibiting AQP1 by 10(-5) M mercury chloride (MC). Deposited ECM during cell culture exhibited significant concentration differences among cell types. ZL34 cell adhesion was significantly higher than MeT-5A or M14K cells on FN and ECM. MeT-5A and M14K cell adhesion on FN was sensitive to AQP1 inhibition, whereas AQP1 inhibition on ECM was limited to M14K cells. Wound healing in ZL34 cells was significantly higher than MeT-5A and M14K cells on FN and ECM. AQP1 inhibition significantly lowered cell migration in ZL34 cells on FN and ECM. Sphere formation was not dependent on FN or ECM in the media. AQP1 inhibition in FN media reduced sphere formation in M14K cells, whereas, in ECM, all three cell types were sensitive to AQP1 inhibition.

Pleural mesothelial cell differentiation and invasion in fibrogenic lung injury.

The origin of the myofibroblast in fibrotic lung disease is uncertain, and no effective medical therapy for fibrosis exists. We have previously demonstrated that transforming growth factor-ß1 (TGF-ß1) induces pleural mesothelial cell (PMC) transformation into myofibroblasts and haptotactic migration in vitro. Whether PMC differentiation and migration occurs in vivo, and whether this response can be modulated for therapeutic benefit, is unknown. Here, using mice recombinant for green fluorescent protein (GFP) driven by the Wilms tumor-1 (WT-1) promoter, we demonstrate PMC trafficking into the lung and differentiation into myofibroblasts. Carbon monoxide or the induction of heme oxygenase-1 (HO-1) inhibited the expression of myofibroblast markers, contractility, and haptotaxis in PMCs treated with TGF-ß1. Intrapleural HO-1 induction inhibited PMC migration after intratracheal fibrogenic injury. PMCs from patients with idiopathic pulmonary fibrosis (IPF) exhibited increased expression of myofibroblast markers and enhanced contractility and haptotaxis, compared with normal PMCs. Carbon monoxide reversed this IPF PMC profibrotic phenotype. WT-1-expressing cells were present within fibrotic regions of the lungs in IPF subjects, supporting a role for PMC differentiation and trafficking as contributors to the myofibroblast population in lung fibrosis. Our findings also support a potential role for pleural-based therapies to modulate pleural mesothelial activation and parenchymal fibrosis progression.

VEGF increases the permeability of sheep pleura ex vivo through VEGFR2 stimulation.

Vascular endothelial growth factor (VEGF), a cytokine that increases vascular permeability to water and proteins and induces angiogenesis, has been implicated in the development of pleural effusions. Inflammatory and malignant pleural effusions are rich in VEGF content while mesothelial cells produce and excrete VEGF. In this report we aimed at investigating by means of electrophysiology the direct effects of VEGF on the parietal and visceral sheep pleura as well as the type of receptors that mediate this effect. Our findings show that VEGF has a direct effect on the pleural mesothelium rendering it more permeable and this effect is mediated through the stimulation of VEGF receptor 2. Our findings shed more light to the role of VEGF in the pathogenesis of pleural effusions and provide functional evidence for a role of VEGFR2 on the pleural mesothelium that has never been studied before.

Pleural Fluid-to-Blood BNP Ratio May Contribute to Prognosis in Malignant Pleural Mesothelioma.

BACKGROUND: Brain natriuretic peptide (BNP) seems to be produced from malignant mesothelial cells other than cardiomyocytes. We aimed to evaluate whether an increased pleural fluid-to-blood BNP ratio in patients with malignant pleural mesothelioma (MPM) could facilitate prognosis beyond diagnosis. MATERIALS AND METHODS: Patients with MPM were included (observational study). One- and two-year survival and factors affecting it were tested. To evaluate the prognostic significance of the natriuretic peptide precursor B (NPPB) gene expression in MPM, we constructed a survival curve from data derived from The Cancer Genome Atlas. RESULTS: Nineteen consecutive patients with MPM were included (age: 67 (61, 80), male 78.9%). One- and two-year survival were 52.6% and 31.6%, respectively. Age, performance status, and the other variables tested did not differ between survivors and non-survivors. Non-survivors presented higher pleural fluid BNP in two years (699 (210, 5000) vs. 379.5 (5, 567), p = 0.036) and BNP ratios than survivors (1-year: 28.75 (4.05, 150.24) vs. 3.49 (0.3, 26) p = 0.001, 2-years: 22.8 (2.42, 150.24) vs. 3.49 (0.3, 7.76), p = 0.001). One- and two-year survival rates in patients with BNP ratios above/equal to the median value (8.82) were 20% and 0%, and 88.9% and 66.7%, respectively, in patients with BNP ratios below 8.82 (p = 0.006 and p = 0.002, respectively). MPM patients with low NPPB expression presented significantly higher survival rates compared to patients with higher expressions (p = 0.032). CONCLUSION: A high pleural fluid/blood BNP ratio, an easily performed in everyday practice, costless biomarker seems to predict poorer survival better than the commonly reported prognostic factors in MPM.

The effect of cigarette smoke extract exposure on the size and sexual behaviour of Drosophila melanogaster.

Drosophila melanogaster is a widely used animal model in human diseases and to date it has not been applied to the study of the impact of tobacco use on human sexual function. Hence, this report examines the effects of different concentrations of cigarette smoke extract (CSE) exposure on the size and sexual behavior of D. melanogaster. Wild-type flies were held in vials containing CSE-infused culture media at concentrations of 10%, 25%, and 50% for three days, and their offspring were reared under the same conditions before measuring their body size and mating behavior. CSE exposure during development reduced the tibia length and body mass of emerging adult flies and prolonged the time required for successful courtship copulation success, while courtship behaviors (wing extension, tapping, abdomen bending, attempted copulation) remained largely unchanged. Our findings indicate that CSE exposure negatively affects the development of flies and their subsequent reproductive success. Future experiments should investigate the CSE effect on male female fertility.

Changes in expression of mesothelial BBS genes in 2D and 3D after lithium chloride and ammonium sulphate induction of primary cilium disturbance: a pilot study.

BACKGROUND: Malignant pleural mesothelioma (MPM), a rare and aggressive pleural tumor, has significant histological and molecular heterogeneity. Primary Cilium (PC), an organelle of emerging importance in malignancies, has been scarcely investigated in MPM. A critical molecular complex for the PC function is the BBSome and here we aimed at assessing its expression patterns in ordinary 2D and spheroid 3D cell cultures. METHODS: A human benign mesothelial cell line (MeT-5A), MPM cell lines (M14K, epithelioid MPM; MSTO, biphasic MPM), and primary MPM cells (pMPM) were used. Primers specific for the human BBS1, 2, 4, 5, 7, 9, 18 transcripts were designed, and quantitative real-time PCR (qRT-PCR) was done with ß-actin as the gene of reference. The relative gene expression across 2D and 3D cultures was analyzed by the expression factor (mean of 1/ΔCt values). With the 2-∆∆Ct method the gene expression fold changes were assessed from qRT-PCR data. Molecular changes using the PC-modulating drugs ammonium sulfate (AS) and lithium chloride (LC) were also determined. RESULTS: PC was present in all cells used in the study at approximately 15% of the observed area. BBSome transcripts were differentially expressed in different dimensions of cell culture (2D vs. 3D) in all cell lines and pMPM. Treatment with AS and LC affected the expression of the ciliary BBS2 and BBS18 genes in the benign as well as in the MPM cells. CONCLUSIONS: These data indicate distinct BBSome molecular profiles in human benign and MPM cells cultured in 2D and 3D dimensions and support the notion that PC genes should be investigated as potential MPM therapeutic targets.

Reversible differentiation of myofibroblasts by MyoD.

Myofibroblasts participate in tissue repair processes in diverse mammalian organ systems. The deactivation of myofibroblasts is critical for termination of the reparative response and restoration of tissue structure and function. The current paradigm on normal tissue repair is the apoptotic clearance of terminally differentiated myofibroblasts; while, the accumulation of activated myofibroblasts is associated with progressive human fibrotic disorders. The capacity of myofibroblasts to undergo de-differentiation as a potential mechanism for myofibroblast deactivation has not been examined. In this report, we have uncovered a role for MyoD in the induction of myofibroblast differentiation by transforming growth factor-ß1 (TGF-ß1). Myofibroblasts demonstrate the capacity for de-differentiation and proliferation by modulation of endogenous levels of MyoD. We propose a model of reciprocal signaling between TGF-ß1/ALK5/MyoD and mitogen(s)/ERK-MAPK/CDKs that regulate myofibroblast differentiation and de-differentiation, respectively. Our studies provide the first evidence for MyoD in controlling myofibroblast activation and deactivation. Restricted capacity for de-differentiation of myofibroblasts may underlie the progressive nature of recalcitrant human fibrotic disorders.

Glutathione S-transferase gene polymorphism and asthma: a case-control study in a pediatric population.

Aim: To carry out a case-control study of the association of GST gene polymorphisms in pediatric asthma-related oxidative stress. Materials & methods: Asthma patients (n = 250) and age-matched healthy subjects (n = 250) DNA were genotyped for GSTM1/GSTT1 (+/+, +/-, -/+ and -/-) frequencies using multiplex-PCR and plasma oxidative stress markers (examined spectrophotometrically). Results: Asthma patients had significantly more common null-genotype GSTM1-/GSTT1- (10.4%; p = 0.002) and elevated levels of malondialdehyde, protein carbonyl and 8-hydroxy-2-deoxyguanosine as compared with controls. In addition, the level of plasma glutathione, GST activity and ferric-reducing ability were significantly decreased as compared with controls. Conclusion: Our data revealed significant associations between GSTM1-/GSTT1- genotype and oxidative stress markers in asthmatic children, which may very likely contribute to increased incidence of bronchial asthma.

Evaluation of Sirtuin 1 Levels in Peripheral Blood Mononuclear Cells of Patients With Idiopathic Pulmonary Fibrosis.

AIM: Idiopathic pulmonary fibrosis (IPF) is a devastating lung disorder that is characterized by aggressive and dysbalanced wound healing. IPF is mainly a disease of the elderly and thus is likely to share common pathophysiologic mechanisms with other more age-related diseases. Emerging evidence has linked disturbance of sirtuin-1 (SIRT1) expression and activity with aging and diseases of the elderly. In the present study, we aimed to evaluate SIRT1 expression in the peripheral blood mononuclear cells (PBMCs) of patients with IPF given the lack of studies in the literature. METHODS: We enrolled 34 IPF patients and 22 healthy volunteers (age and sex-matched). In both groups, SIRT1 levels were assessed in plasma, cell pellets of PBMCs, and supernatant from PBMCs' culture with and without the addition of 10% human serum. We also measured transforming growth factor ß1 (TGF-ß1) concentration in plasma from IPF patients and controls. RESULTS: The mean (SD) age (years) of the healthy volunteers was 68.57±6.97 and of the IPF patients was 71.28±5.39 years (p>0.05). The mean SIRT1 concentration was found significantly decreased in the supernatant of PBMCs culture (without the addition of serum) in IPF subjects versus controls (1.97±0.59 ng/ml versus 2.40±0.74 ng/ml, respectively, p=0.047). No significant differences were observed between the two groups in the SIRT1 concentration of all the other materials. TGFß1 concentration of IPF subjects was significantly increased when compared to controls (1281.38±2742.74 versus 131.11±156.06 ng/ml, respectively, p=0.032). Decreased SIRT1 levels in no-serum supernatant were predictive of IPF, after adjustment for age and sex (p=0.014, OR=0.124 [95%CI: 0.023-0.653]). CONCLUSION: The findings of decreased concentration of SIRT1 in PBMCs supernatant and increased concentration of TGFß1 in plasma in IPF patients versus controls provide important insights into the role of SIRT1 in IPF and could serve as a tool for the diagnosis and evaluation of patients with IPF.

Efferocytosis fuels malignant pleural effusion through TIMP1.

Malignant pleural effusion (MPE) results from the capacity of several human cancers to metastasize to the pleural cavity. No effective treatments are currently available, reflecting our insufficient understanding of the basic mechanisms leading to MPE progression. Here, we found that efferocytosis through the receptor tyrosine kinases AXL and MERTK led to the production of interleukin-10 (IL-10) by four distinct pleural cavity macrophage (Mφ) subpopulations characterized by different metabolic states and cell chemotaxis properties. In turn, IL-10 acts on dendritic cells (DCs) inducing the production of tissue inhibitor of metalloproteinases 1 (TIMP1). Genetic ablation of Axl and Mertk in Mφs or IL-10 receptor in DCs or Timp1 substantially reduced MPE progression. Our results delineate an inflammatory cascade-from the clearance of apoptotic cells by Mφs, to production of IL-10, to induction of TIMP1 in DCs-that facilitates MPE progression. This inflammatory cascade offers a series of therapeutic targets for MPE.

Rap1 activation is required for Fc gamma receptor-dependent phagocytosis.

Phagocytosis of IgG-opsonized microbes via the Fc gamma receptor (Fc gammaR) requires the precise coordination of a number of signaling molecules, including the low-molecular mass GTPases. Little is known about the Ras-family GTPase Rap1 in this process. We therefore investigated its importance in mediating Fc gammaR-dependent phagocytosis in NR8383 rat alveolar macrophages. Pulldown of active Rap1 and fluorescence microscopic analysis of GFP-RalGDS (Ral guanine dissociation stimulator)-transfected macrophages revealed that Rap1 is indeed activated by Fc gammaR crosslinking. Inhibition of Rap1 activity, both by Rap1GAP (GTPase-activating protein) expression and liposome-delivered blocking Ab, severely impaired the ability of cells to ingest IgG-opsonized targets. Fc gammaR-induced Rap1 activation was found to be independent of both cAMP and Ca(2+), suggesting a role for the second messenger-independent guanosine exchange factor, C3G. This was supported by the facts that 1) liposome-delivered blocking Ab against C3G inhibited both Fc gammaR-dependent phagocytosis and Rap1 activation, and 2) both active Rap1GTP and C3G were found to translocate to the phagosome. Taken together, our data demonstrate a novel role for Rap1 and its exchange factor C3G in mediating Fc gammaR-dependent phagocytosis.