Role of ZIP kinase in development of myofibroblast differentiation from HPMCs.

During the development of pleural fibrosis, pleural mesothelial cells (PMCs) undergo phenotypic switching from differentiated mesothelial cells to mesenchymal cells (MesoMT). Here, we investigated how external stimuli such as TGF-ß induce HPMC-derived myofibroblast differentiation to facilitate the development of pleural fibrosis. TGF-ß significantly increased di-phosphorylation but not mono-phosphorylation of myosin II regulatory light chain (RLC) in HPMCs. An increase in RLC di-phosphorylation was also found at the pleural layer of our carbon black bleomycin (CBB) pleural fibrosis mouse model, where it showed filamentous localization that coincided with alpha smooth muscle actin (αSMA) in the cells in the pleura. Among the protein kinases that can phosphorylate myosin II RLC, ZIPK (zipper-interacting kinase) protein expression was significantly augmented after TGF-ß stimulation. Furthermore, ZIPK gene silencing attenuated RLC di-phosphorylation, suggesting that ZIPK is responsible for di-phosphorylation of myosin II in HPMCs. Although TGF-ß significantly increased the expression of ZIP kinase protein, the change in ZIP kinase mRNA was marginal, suggesting a posttranscriptional mechanism for the regulation of ZIP kinase expression by TGF-ß. ZIPK gene knockdown (KD) also significantly reduced TGF-ß-induced upregulation of αSMA expression. This finding suggests that siZIPK attenuates myofibroblast differentiation of HPMCs. siZIPK diminished TGF-ß-induced contractility of HPMCs consistent with siZIPK-induced decrease in the di-phosphorylation of myosin II RLC. The present results implicate ZIPK in the regulation of the contractility of HPMC-derived myofibroblasts, phenotype switching, and myofibroblast differentiation of HPMCs.NEW & NOTEWORTHY Here, we highlight that ZIP kinase is responsible for di-phosphorylation of myosin light chain, which facilitates stress fiber formation and actomyosin-based cell contraction during mesothelial to mesenchymal transition in human pleural mesothelial cells. This transition has a significant impact on tissue remodeling and subsequent stiffness of the pleura. This study provides insight into a new therapeutic strategy for the treatment of pleural fibrosis.

The Biological Role of Pleural Fluid PAI-1 and Sonographic Septations in Pleural Infection: Analysis of a Prospectively Collected Clinical Outcome Study.

Rationale: Sonographic septations are assumed to be important clinical predictors of outcome in pleural infection, but the evidence for this is sparse. The inflammatory and fibrinolysis-associated intrapleural pathway(s) leading to septation formation have not been studied in a large cohort of pleural fluid (PF) samples with confirmed pleural infection matched with ultrasound and clinical outcome data. Objectives: To assess the presence and severity of septations against baseline PF PAI-1 (Plasminogen-Activator Inhibitor-1) and other inflammatory and fibrinolysis-associated proteins as well as to correlate these with clinically important outcomes. Methods: We analyzed 214 pleural fluid samples from PILOT (Pleural Infection Longitudinal Outcome Study), a prospective observational pleural infection study, for inflammatory and fibrinolysis-associated proteins using the Luminex platform. Multivariate regression analyses were used to assess the association of pleural biological markers with septation presence and severity (on ultrasound) and clinical outcomes. Measurements and Main Results: PF PAI-1 was the only protein independently associated with septation presence (P < 0.001) and septation severity (P = 0.003). PF PAI-1 concentrations were associated with increased length of stay (P = 0.048) and increased 12-month mortality (P = 0.003). Sonographic septations alone had no relation to clinical outcomes. Conclusions: In a large and well-characterized cohort, this is the first study to associate pleural biological parameters with a validated sonographic septation outcome in pleural infection. PF PAI-1 is the first biomarker to demonstrate an independent association with mortality. Although PF PAI-1 plays an integral role in driving septation formation, septations themselves are not associated with clinically important outcomes. These novel findings now require prospective validation.

Splicing factor SRSF6 mediates pleural fibrosis.

Pleural fibrosis is defined as an excessive deposition of extracellular matrix that results in destruction of the normal pleural tissue architecture and compromised function. Tuberculous pleurisy, asbestos injury, and rheumatoid pleurisy are main causes of pleural fibrosis. Pleural mesothelial cells (PMCs) play a key role in pleural fibrosis. However, detailed mechanisms are poorly understood. Serine/arginine-rich protein SRSF6 belongs to a family of highly conserved RNA-binding splicing-factor proteins. Based on its known functions, SRSF6 should be expected to play a role in fibrotic diseases. However, the role of SRSF6 in pleural fibrosis remains unknown. In this study, SRSF6 protein was found to be increased in cells of tuberculous pleural effusions (TBPE) from patients, and decellularized TBPE, bleomycin, and TGF-ß1 were confirmed to increase SRSF6 levels in PMCs. In vitro, SRSF6 mediated PMC proliferation and synthesis of the main fibrotic protein COL1A2. In vivo, SRSF6 inhibition prevented mouse experimental pleural fibrosis. Finally, activated SMAD2/3, increased SOX4, and depressed miRNA-506-3p were associated with SRSF6 upregulation in PMCs. These observations support a model in which SRSF6 induces pleural fibrosis through a cluster pathway, including SRSF6/WNT5A and SRSF6/SMAD1/5/9 signaling. In conclusion, we propose inhibition of the splicing factor SRSF6 as a strategy for treatment of pleural fibrosis.

Circulating and local nuclear expression of survivin and fibulin-3 genes in discriminating benign from malignant respiratory diseases: correlation analysis.

Survivin is an inhibitor of apoptosis as well as a promoter of cell proliferation. Fibulin-3 is a matrix glycoprotein that displays potential for tumor suppression or propagation. The present study aimed to validate the expression levels of survivin and fibulin-3 in benign and malignant respiratory diseases. This case-control study included 219 patients categorized into five groups. Group A included 63 patients with lung cancer, group B included 63 patients with various benign lung diseases, group D included 45 patients with malignant pleural mesothelioma (MPM), and group E included 48 patients with various benign pleural diseases. Group C included 60 healthy individuals (control group). Serum survivin and fibulin-3 levels were measured by ELISA, whereas their nuclear expressions in the lung and pleura were assessed via Western blot analysis. The results showed significantly higher survivin serum levels and significantly lower fibulin-3 levels in group A compared with in group B and controls (P<0.001). There were significantly higher serum levels of survivin and fibulin-3 in group D compared with in group E and controls (P<0.001), consistent with observed nuclear survivin and fibulin-3 expression levels. Fibulin-3 was determined to have higher value than survivin in discriminating lung cancer from MPM (P<0.05). Survivin and fibulin-3 could be useful diagnostic markers for lung and pleural cancers, and fibulin-3 expression was particularly useful in differentiating lung cancer from MPM.

Pleura revisited: From histology and pathophysiology to pathology and molecular biology.

Pleural cavity has an interesting physiology that when impaired gives rise to pleural effusions a rather frequent problem in respiratory medicine practice. Their aetiology varies widely producing distinct pathological lesions with different prognosis and treatment. The basic morphological features of pleural diseases, neoplastic and non-neoplastic, will be analysed in this review with an emphasis to their pathophysiology, differential diagnosis and clinicopathological correlations.

Fibrin turnover and pleural organization: bench to bedside.

Recent studies have shed new light on the role of the fibrinolytic system in the pathogenesis of pleural organization, including the mechanisms by which the system regulates mesenchymal transition of mesothelial cells and how that process affects outcomes of pleural injury. The key contribution of plasminogen activator inhibitor-1 to the outcomes of pleural injury is now better understood as is its role in the regulation of intrapleural fibrinolytic therapy. In addition, the mechanisms by which fibrinolysins are processed after intrapleural administration have now been elucidated, informing new candidate diagnostics and therapeutics for pleural loculation and failed drainage. The emergence of new potential interventional targets offers the potential for the development of new and more effective therapeutic candidates.

KIF5A transports collagen vesicles of myofibroblasts during pleural fibrosis.

Fibrosis involves the production of extracellular matrix proteins in tissues and is often preceded by injury or trauma. In pleural fibrosis excess collagen deposition results in pleural thickening, increased stiffness and impaired lung function. Myofibroblasts are responsible for increased collagen deposition, however the molecular mechanism of transportation of procollagen containing vesicles for secretion is unknown. Here, we studied the role of kinesin on collagen-1 (Col-1) containing vesicle transportation in human pleural mesothelial cells (HPMCs). Among a number of cargo transporting kinesins, KIF5A was notably upregulated during TGF-ß induced mesothelial-mesenchymal transition (MesoMT). Using superresolution structured illumination microscopy and the DUO-Link technique, we found that KIF5A colocalized with Col-1 containing vesicles. KIF5A knock-down significantly reduced Col-1 secretion and attenuated TGF-ß induced increment in Col-1 localization at cell peripheries. Live cell imaging revealed that GFP-KIF5A and mCherry-Col-1 containing vesicles moved together. Kymography showed that these molecules continuously move with a mean velocity of 0.56 µm/sec, suggesting that the movement is directional but not diffusion limited process. Moreover, KIF5A was notably upregulated along with Col-1 and α-smooth muscle actin in pleural thickening in the carbon-black bleomycin mouse model. These results support our hypothesis that KIF5A is responsible for collagen transportation and secretion from HPMCs.

Utility of CEA and CA 15-3 measurements in non-purulent pleural exudates in the diagnosis of malignancy: A single-center experience. / Utilidad de la medición de CEA y CA 15-3 en los exudados pleurales no purulentos para diagnosticar malignidad: experiencia de un único centro.

OBJECTIVE: To establish the diagnostic accuracy of pleural fluid (PF) CEA and CA 15-3 in identifying malignancy, and to determine the additional value of these markers in patients with malignant pleural effusions (MPEs) with false negative results from cytological fluid examination. METHODS: PF concentrations of CEA and/or CA 15-3 were determined in 1,575 patients with non-purulent exudates, 549 of whom had confirmed MPEs, 284 probable MPEs, and 742 benign effusions. Tumor marker cut-off points were set to ensure 100% specificity for malignant effusion. RESULTS: The 41, 40 and 60% of MPE patients had high PF levels of CEA (>45ng/mL), CA 15-3 (>77 UI/l) or both, respectively. These percentages were 30, 19 and 41% in MPEs with positive pleural biopsy and negative PF cytology; and 24, 13 and 35% in clinical MPEs without histocytological confirmation. Tumor markers were of no value in lymphomas and mesotheliomas. The area-under-the-curve for CEA was 0.819 (95% CI: 0,793-0,845) and for CA 15-3, it was 0.822 (95% CI: 0,796-0,847). The use of tumor markers compared to cytology alone, increased the diagnosis of malignancy by 14%. CONCLUSIONS: Measurements of PF CEA and CA 15-3 may complement pleural cytology in the identification of MPEs.

Libby amphibole-induced mesothelial cell autoantibodies promote collagen deposition in mice.

Libby amphibole (LA) causes a unique progressive lamellar pleural fibrosis (LPF) that is associated with pulmonary function decline. Pleural fibrosis among the LA-exposed population of Libby, MT, has been associated with the production of anti-mesothelial cell autoantibodies (MCAA), which induce collagen production from cultured human mesothelial cells. We hypothesized that the progressive nature of LPF could be at least partially attributed to an autoimmune process and sought to demonstrate that LA-induced MCAA trigger collagen deposition in vivo. C57BL/6 mice were exposed to LA for 7 mo, and serum was tested for MCAA by cell-based ELISA on primary mouse mesothelial cells. When treated in vitro with serum from mice exposed to LA, mesothelial cells upregulated collagen matrix production. This effect was lost when the serum was cleared of IgG using protein G beads, implicating IgG autoantibodies. Using the peritoneal cavity as a surrogate for the pleural cavity, groups of naïve (non-asbestos-exposed) mice were injected intraperitoneally with 1) control serum, 2) one dose of serum from LA-exposed mice (LA serum), 3) two doses of LA serum, or 4) two doses of LA serum cleared of IgG. After 1 mo, analysis of collagen in peritoneal walls using two-photon confocal microscopy (SHG analysis) and a hydroxyproline assay demonstrated significant increases in collagen by LA serum but not control or cleared serum. These data support the hypothesis that MCAA in LA-exposed mice induce fibrotic responses in vivo, demonstrating that an autoimmune component may be contributing to the progressive pleural fibrosis seen in LA-exposed patients.

Thorax: normal and benign pathologic patterns in FDG-PET/CT imaging.

This article describes the normal patterns of thoracic (18)F-fluorodeoxyglucose (FDG) biodistribution, and expands on the role of FDG-PET/computed tomography (CT) for the evaluation of patients suffering from a spectrum of benign pathologic conditions that affect the chest. The discussion addresses the applications of FDG-PET/CT imaging in a wide variety of chest-related disorders. Familiarity with the normal thoracic biodistribution of FDG, coupled with knowledge of the potential nonmalignant causes of increased FDG uptake in the chest, is essential to minimize the incidence of incorrect interpretation of FDG-PET images in daily clinical practice.

Genes involved in innate immunity associated with asbestos-related fibrotic changes.

OBJECTIVES: To determine whether genetic polymorphisms in several candidate genes related to innate immunity and protease-antiprotease balance modify individual susceptibility to develop asbestos-related fibrotic pleuropulmonary changes. METHODS: Sixteen polymorphisms from nine genes (NLRP3, CARD8, TNF, TGFB1, GC, MMP1, MMP9, MMP12 and TIMP2) were genotyped from 951 Finnish asbestos-exposed workers. The genotype/haplotype data were compared to signs of fibrosis and pleural thickenings using linear and logistic regression analysis adjusted for potential confounders. RESULTS: A functional polymorphism (Q705K; rs35829419) in the NLRP3 gene was associated with interstitial lung fibrosis (p=0.013), and the TGFB1 rs2241718 SNP with visceral pleural fibrosis (VPF) (p=0.044). In stratified analysis, the carriage of at least one NLRP3 variant allele conferred a 2.5-fold increased risk for pathological interstitial lung fibrosis (OR 2.44, 95% CI 0.97 to 6.14). Conversely, the carriage of at least one TGFB1 rs2241718 variant allele protected against VPF (OR 0.62, 95% CI 0.39 to 0.98). The TIMP2 rs2277698 SNP and a haplotype consisting of the TGFB1 rs1800469 and rs1800470 SNPs were associated with the degree of pleural thickening calcification (p=0.037 and p=0.035), and the CARD8 rs2043211 SNP with the greatest thickness of pleural plaques (p=0.015). CONCLUSIONS: Our results support the hypothesis that the NLRP3 inflammasome is important in the development of fibrotic lung disease by associating the NLRP3 rs35829419 variant allele with increased risk of asbestos-related interstitial lung fibrosis, and the TGFB1 rs2241718 variant allele with decreased risk of asbestos-related VPF. Polymorphisms in CARD8 and TIMP2 are proposed to modify the development and/or calcification of pleural thickenings.

Restrictive allograft syndrome post lung transplantation is characterized by pleuroparenchymal fibroelastosis.

We previously described restrictive allograft syndrome as a form of chronic lung allograft dysfunction, demonstrating restrictive pulmonary function decline. However, the histopathological correlates of restrictive allograft syndrome have yet to be satisfactorily described. We hypothesized that pulmonary pleuroparenchymal fibroelastosis, as has recently been described in bone marrow transplant recipients, may also be present in the lungs of patients with restrictive allograft syndrome. Retrospective review of 493 patients who underwent lung transplantation between 1 January 1996 and 30 June 2009, was conducted. Out of 47 patients with clinical features of restrictive allograft syndrome, 16 had wedge biopsy, re-transplant lung explant, or autopsy lung specimens available for review. All lungs showed varying degrees of pleural fibrosis. Fifteen of 16 showed parenchymal fibroelastosis, characterized by hypocellular collagen deposition with preservation and thickening of the underlying alveolar septal elastic network. The fibroelastosis was predominantly subpleural in distribution, with some cases also showing centrilobular and paraseptal distribution. A sharp demarcation was often seen between areas of fibroelastosis and unaffected lung parenchyma, with fibroblastic foci often present at this interface. Concurrent features of obliterative bronchiolitis were present in 14 cases. Another common finding was the presence of diffuse alveolar damage (13 cases), usually in specimens obtained <1 year after clinical onset of restrictive allograft syndrome. The single specimen in which fibroelastosis was not identified was obtained before the clinical onset of chronic lung allograft dysfunction, and showed features of diffuse alveolar damage. In conclusion, pleuroparenchymal fibroelastosis is a major histopathologic correlate of restrictive allograft syndrome, and was often found concurrently with diffuse alveolar damage. Our findings support a temporal sequence of diffuse alveolar damage followed by the development of pleuroparenchymal fibroelastosis in the histopathologic evolution of restrictive allograft syndrome.

Benefit of serum-effusion albumin gradient in congestive heart failure patients.

OBJECTIVE: To compare between light's criteria and serum-effusion (S-E) albumin gradient in diagnosis of transudate effusion in congestive heart failure (CHF) patients. MATERIAL AND METHOD: Eighty-six patients who had pleural effusion and suspected CHF were enrolled in the present study between October 2008- September 2010. Suspected CHF was defined by clinical or echocardiography. Inform consents were given by all volunteers. Exclusion criteria was previous thoracotomy or coronary bypass graft 3 months before present study. Thoracocentesis was done to evaluate transudate effusion by light's criteria and S-E albumin gradient > 1.2 mg/dl. RESULTS: 12 (13.95%), 56 (65.11%), 17 (19.76%) of all were pure pleural disease, pure CHF, combination of pleural disease and CHF. Sensitivity/specificity/accuracy of S-E albumin gradients and light's criteria in diagnosis of CHF (both pure and combined) were 90.1/33.3/80.2%, 64.7/80.0/67.4%. No correlation between amount of diuretic drug and "exudate" criteria from lights' (p = 0. 66). 25 (27.2%) patients were previous post thoracotomy or coronary bypass graft. 7 of 25 patients had loculated effusion. There was correlation between previous surgery with loculated effusion and effusion from combination of pleural disease and CHF (p = 0.22). CONCLUSION: There is benefit to use S-E albumin gradient > 1.2 mg/dl to diagnosis patients who were suspected CHF with or without pleural disease. The authors recommended to use S-E albumin gradients combined with Light's criteria in suspected CHF patients.

Monoclonal antibodies anti-TGFß1 and anti-VEGF inhibit the experimental pleurodesis induced by silver nitrate.

BACKGROUND: The mechanisms underlying pleural inflammation and pleurodesis are poorly understood. We hypothesized that the cytokines transforming growth factor ß (TGFß1) and vascular endothelial growth factor (VEGF) play a major role in pleurodesis after intrapleural silver nitrate (SN) injection. METHOD: Forty rabbits received intrapleurally 0.5% SN alone or 0.5% SN + anti-TGFß1, anti-IL-8, or anti-VEGF. After 28 days, the animals were euthanized and macroscopic pleural adhesions, microscopic pleural fibrosis, and collagen deposition were analyzed for characterization of the degree of pleurodesis (scores 0-4). RESULTS: Scores of pleural adhesions, pleural fibrosis, total collagen, and thin collagen fibers deposition after 28 days were significantly lower for 0.5% SN + anti-TGFß1 and 0.5% SN + anti-VEGF. Significant correlations were found between macroscopic adhesion and microscopic pleural fibrosis with total collagen and thin collagen fibers. CONCLUSIONS: We conclude that both TGFß1 and VEGF, but not IL-8, mediate the pleural inflammatory response and pleurodesis induced by SN.

Levels of YKL-40 in pleural effusions and blood from patients with pulmonary or pleural disease.

BACKGROUND: YKL-40 (a chitinase-like protein) is an inflammatory biomarker that is associated with lung injury pathogenesis. We aimed to identify the diagnostic values of YKL-40 in pleural effusions and to evaluate circulating YKL-40 levels during multiple etiological pulmonary/pleural diseases and the role of YKL-40 as a monitoring marker of inflammatory pulmonary disease. METHODS: Pleural YKL-40 (n=197), YKL-39 (the most homologous chitinase-like protein to human YKL-40), and conventional pleural marker levels were measured in patients with pulmonary/pleural disease. Additionally, serum YKL-40 and YKL-39 levels were analyzed in both patients and controls (n=432) and serially monitored in patients with asthma (n=27) or pneumonia (n=22). RESULTS: Pleural YKL-40 levels were higher than those in the serum and highest in tuberculous pleural effusions (TPEs; 1181 ng/mL), followed by parapneumonic, malignant, and cardiogenic effusions (560 ng/mL). The diagnostic accuracy of pleural YKL-40 (0.78) for discriminating between tuberculous and malignant effusion was comparable to or greater than those of YKL-39, total protein, C-reactive protein and CYFRA 21-1, and lower than those of adenosine deaminase (p<0.05) and carcinoembriogenic antigen (p=0.05). Serum YKL-40 levels were higher in the pneumonia group than in the cancer, asthma, or control groups. Following treatment, serum YKL-40 levels were more greatly reduced in pneumonia patients than in asthma patients. Serum YKL-39 levels did not differ between patients and controls. CONCLUSIONS: Pleural YKL-40 levels are elevated in TPEs and have fairly good diagnostic efficacy for detecting TPEs. However, adenosine deaminase is more efficient for detecting TPEs than pleural YKL-40. Serum YKL-40 levels are highest during pneumonia compared to common pulmonary/pleural diseases and are more useful for monitoring pneumonia than asthma.

Pleuroparenchymal fibroelastosis in patients with pulmonary disease secondary to bone marrow transplantation.

This study presents four patients who underwent bone marrow transplantation and subsequently developed pleuroparenchymal fibroelastosis, hitherto reported as an idiopathic condition. All presented clinically with pneumothorax and subpleural fibrosis on high-resolution computed tomography. In addition to the expected obliterative bronchiolitis, histopathology showed coexistent subpleural changes, and the relationship of pathology in multiple anatomic compartments in post bone marrow transplantation pulmonary disease is discussed.

Non-neoplastic and neoplastic pleural endpoints following fiber exposure.

Exposure to asbestos fibers is associated with non-neoplastic pleural diseases including plaques, fibrosis, and benign effusions, as well as with diffuse malignant pleural mesothelioma. Translocation and retention of fibers are fundamental processes in understanding the interactions between the dose and dimensions of fibers retained at this anatomic site and the subsequent pathological reactions. The initial interaction of fibers with target cells in the pleura has been studied in cellular models in vitro and in experimental studies in vivo. The proposed biological mechanisms responsible for non-neoplastic and neoplastic pleural diseases and the physical and chemical properties of asbestos fibers relevant to these mechanisms are critically reviewed. Understanding mechanisms of asbestos fiber toxicity may help us anticipate the problems from future exposures both to asbestos and to novel fibrous materials such as nanotubes. Gaps in our understanding have been outlined as guides for future research.

Role of mutagenicity in asbestos fiber-induced carcinogenicity and other diseases.

The cellular and molecular mechanisms of how asbestos fibers induce cancers and other diseases are not well understood. Both serpentine and amphibole asbestos fibers have been shown to induce oxidative stress, inflammatory responses, cellular toxicity and tissue injuries, genetic changes, and epigenetic alterations in target cells in vitro and tissues in vivo. Most of these mechanisms are believe to be shared by both fiber-induced cancers and noncancerous diseases. This article summarizes the findings from existing literature with a focus on genetic changes, specifically, mutagenicity of asbestos fibers. Thus far, experimental evidence suggesting the involvement of mutagenesis in asbestos carcinogenicity is more convincing than asbestos-induced fibrotic diseases. The potential contributions of mutagenicity to asbestos-induced diseases, with an emphasis on carcinogenicity, are reviewed from five aspects: (1) whether there is a mutagenic mode of action (MOA) in fiber-induced carcinogenesis; (2) mutagenicity/carcinogenicity at low dose; (3) biological activities that contribute to mutagenicity and impact of target tissue/cell type; (4) health endpoints with or without mutagenicity as a key event; and finally, (5) determinant factors of toxicity in mutagenicity. At the end of this review, a consensus statement of what is known, what is believed to be factual but requires confirmation, and existing data gaps, as well as future research needs and directions, is provided.

[PET-CT in thoracic disease]. / TEP-TDM et thorax.

PET-CT imaging merges metabolic data obtained after injection of a tracer labelled with a positron emitter, with CT anatomical data. This whole-body technique provides (i) an improved spatial resolution and (ii) when the tracer is ¹8FDG, quantification of tissue glucose metabolism. In thoracic oncology, ¹8FDG PET-CT imaging allows diagnosis, staging, follow-up of treatment efficiency, and detection of recurrence. Furthermore, its potential usefulness in inflammatory and infectious diseases should be emphasized. Its main contra-indication is pregnancy, and a good knowledge of its technical procedure is mandatory. The most currently used quantification index is the standardized uptake value (SUV), whose interpretation requires caution.