Talc-induced expression of C-C and C-X-C chemokines and intercellular adhesion molecule-1 in mesothelial cells

Comparison of the effect of Everolimus, Prednisolone, and a combination of both on experimentally induced peritoneal adhesions in rats

Postoperative intra-abdominal adhesions represent a significant post-surgical problem. Its complications can cause a considerable clinical and cost burden. Herein, our study aimed to investigate the effect of Everolimus on peritoneal adhesion formation after inducing adhesions in rats. In this experimental study, adhesion bands were induced by intraperitoneal injection of 3 ml of 10% sterile talc solution in 64 male albino rats. The first group served as the control group. The second one received oral Prednisolone (1 mg/kg/day), the third received Everolimus (0.1 mg/kg/day), and group four received both drugs with similar dosages for four consecutive weeks. The formation of adhesion bands was qualitatively graded according to the Nair classification. The rats in the control group had extensive adhesions between the abdominal wall and the organs. Regarding substantial adhesion formation, 50% (8/16) of animals in the control group had substantial adhesions, while this rate in the groups receiving Prednisolone, Everolimus, and combination treatment was 31%, 31%, and 31%, respectively. Also, 68.75% (5/11) of the Prednisolone recipients had insubstantial adhesions, the same as Everolimus recipients, while in the combination group, 66.66% (10/15) rats had insubstantial adhesions. Everolimus demonstrated satisfactory results in reducing the rates of induced peritoneal adhesion in an experimental model, similar to Prednisolone and superior to a combination regime.

Inhalation Toxicity of Talc

Respirable talc powder (RTP) is a complex mineral mixture of talc along with accessory minerals, including tremolite, anthophyllite, quartz, magnesite, dolomite, antigorite, lizardite, and chlorite. The industrial mining, milling, and processing of talc ore is associated with elevated incidences of fibrotic and neoplastic diseases, which are also seen among workers exposed to RTP in secondary industries and individuals using processed cosmetic talc for personal use. There is controversial evidence of a link between the talc-induced lung diseases and a potential contamination with asbestos fibers. This controversy is fueled by inadequate exposure data and the complex mineralogy and terminology of the accessory minerals. Talc aerosols exhibit a wide range of mineral habits, including particulates and fibrous structures that have dimensional and compositional characteristics related to the development of asbestos-related lung disease. The inhalation toxicology of RTP is based on the analysis of occupational hygiene and animal inhalation studies conducted between the 1940s and the 1990s and more recent mechanistic studies conducted both in vivo and in vitro. The review of talc toxicity studies reveals that the occupational studies provide only equivocal links between any of the components of the aerosols and the development of pulmonary cancer; however, there is substantial evidence of an association between the aerosols and pleural and pulmonary fibrosis and the development of nonmalignant respiratory disease. The animal inhalation and implantation studies appear to be less than optimal, which also appears to be true for the in vivo and in vitro studies. The mechanistic studies have identified the key pathogenic characteristics of asbestos to be long and thin fibers that are durable in lung tissues and fluids. Talc toxicity studies show that talc particles and fibers are durable and can remain in the lung for up to 40 years after the end of exposure. This extended tissue residence is considered to constitute a continuing tissue exposure that is capable of inducing the documented inflammatory and proliferative response. There is less consensus as to whether there is a threshold fiber length effect, as long, thin fibers (>5 μm) form only a small fraction of talc aerosols and the possible role of fibers >5 μm in the translocation from the lung to the pleura and their association with pleural fibrotic and carcinogenic lesions. Long, thin fibers are preferentially deposited in hot spots in the lung, such as airway bifurcations, areas typically associated with the development of lung cancer. The platy structures typical of talc can form oblate structures behaving more as fibers in the air stream, and these have also been shown to deposit preferentially in such locations. The review of the inhalation toxicity of talc provides a plausible explanation for the carcinogenic potential of RTP.

PI3K Catalytic Subunits α and β Modulate Cell Death and IL-6 Secretion Induced by Talc Particles in Human Lung Carcinoma Cells

Hydrated magnesium silicate (or "talc" particles) is a sclerosis agent commonly used in the management of malignant pleural effusions, a common symptom of metastatic diseases, including lung cancers. However, the direct effects of talc particles to lung carcinoma cells, which can be found in the malignant pleural effusion fluids from patients with lung cancer, are not fully understood. Here, we report a study of the signaling pathways that can modulate the cell death and IL-6 secretion induced by talc particles in human lung carcinoma cells. We found that talc-sensitive cells have higher mRNA and protein expression of PI3K catalytic subunits α and β. Further experiments confirmed that modulation (inhibition or activation) of the PI3K pathway reduces or enhances cellular sensitivity to talc particles, respectively, independent of the inflammasome. By knocking down specific PI3K isoforms, we also confirmed that both PI3Kα and -β mediate the observed talc effects. Our results suggest a novel role of the PI3K pathway in talc-induced cell death and IL-6 secretion in lung carcinoma cells. These cellular events are known to drive fibrosis, and thus further studies of the PI3K pathway may provide a better understanding of the mechanisms of talc sclerosis in the malignant pleural space.

Particle size, distribution, and behavior of talc preparations: within the United States and beyond

PURPOSE OF REVIEW

Talc remains a common sclerosant utilized for pleurodesis. However, the use of talc has documented complications and debate has persisted regarding the safety of talc as well as the differences in talc preparations available throughout the world. We sought to describe an up-to-date review of talc preparations available and the impact these preparations may have on the safety profile of talc.

RECENT FINDINGS

Within laboratory-based examinations, talc particle size available within the United States appears to be more consistent with prior reported 'safe' particle sizes. The presence of talc within protein-based solutions appears to modify the overall milieu of the solution and likely results in particle aggregation.

SUMMARY

The use of talc remains well accepted for pleurodesis as evidenced by inclusion by multiple guidelines. The medical fields' current understanding of talc and its basic interactions within the pleural space remain limited. Multiple questions related to the pleural space and pleurodesis remain unanswered.

Critical review of the association between perineal use of talc powder and risk of ovarian cancer

Over the past four decades, there has been increasing concern that perineal use of talc powder, a commonly used personal care product, might be associated with an increased risk of ovarian cancer.

OBJECTIVES

To critically review all available human epidemiological data on the relationship between perineal use of talc powder and ovarian cancer, with consideration of other relevant experimental evidence.

METHODOLOGY

We identified 30 human studies for qualitative assessment of evidence, including 27 that were retained for further quantitative analysis.

RESULTS

A positive association between perineal use of talc powder and ovarian cancer was found [OR: 1.28 (95% CI: 1.20-1.37)]. A significant risk was noted in Hispanics and Whites, in women applying talc to underwear, in pre-menopausal women and in post-menopausal women receiving hormonal therapy. A negative association was noted with tubal ligation.

CONCLUSION

Perineal use of talc powder is a possible cause of human ovarian cancer.

Survivin is a negative prognostic factor in malignant pleural effusion

BACKGROUND

Survivin is a well-known member of the inhibitor of apoptosis family, and has been related to increased tumour aggressivity, both in tissue and in pleural fluid.

OBJECTIVES

In patients with malignant pleural effusion, we sought to investigate the changes in pleural fluid survivin concentrations induced by talc instillation into the pleural space. Those changes were also examined in relation to pleurodesis outcome and patient survival.

METHODS

We investigated 84 patients with malignant pleural effusion who underwent talc pleurodesis. Of them, 32 had breast cancer, 25 lung cancer and 27 had mesothelioma. Serial samples of pleural fluid were obtained before thoracoscopy (baseline) and 24 hours thereafter.

RESULTS

Survivin levels were successfully quantified in all pleural fluid samples, and they were significantly higher in samples obtained after thoracoscopic talc poudrage compared with baseline (P < .001). Patients with higher pleural fluid survivin levels at baseline had a significantly poorer pleurodesis outcome (P = .004). A 30 pg/mL cut-off for baseline survivin in pleural fluid predicted failure of pleurodesis with a 54% sensitivity and 79% specificity (P = .009). Moreover, median postpleurodesis survival of patients with baseline survivin levels ≥30 pg/mL was 4 months (range: 0.1-38), compared with 13 months (range: 0.1-259) in patients below that cut-off (P < .001).

CONCLUSION

Elevated pleural fluid survivin concentrations are useful to predict failure of pleurodesis and are associated with shorter survival in patients with malignant pleural effusion.

Modulation of intra-pulmonary TGF-b expression by mycophenolate mofetil in lupus prone MRL/lpr mice

We investigated the expression profile of inflammatory cytokines in the lung of lupus-prone MRL/lpr mice and evaluated the therapeutic potential of mycophenolate mofetil (MMF) in reducing pulmonary cytokines in active lupus. Eight-week old female MRL/lpr mice ( n = 20) were treated with MMF in vehicle by oral gavage. Disease control MRL/lpr mice ( n = 30) or normal control MRL mice ( n = 20) received vehicle alone. The mice were sacrificed after eight or 12 weeks of treatment. Gene expression and protein synthesis of IL-1β, MCP-1 and TGF-β1 in lung tissues were determined. We found an increase in the gene expression of IL-1β, MCP-1 and TGF-β1 in lung tissues of untreated MRL/lpr mice compared with MRL mice at either 16 weeks or 20 weeks of age. MMF treatment significantly prolonged the survival of MRL/lpr mice, down-regulated the gene expression of IL-1β, MCP-1 and TGF-β1 in lung tissues at the end of eight or 12 weeks of treatment. Protein synthesis of TGF-b1 was decreased following eight weeks of MMF treatment. We conclude that MMF treatment can reduce the TGF-b1 gene expression and protein synthesis in lung tissues of lupus-prone mice. Our findings provide experimental data suggesting a beneficial potential of MMF therapy in pulmonary involvement of lupus.

Safety Assessment of Talc as Used in Cosmetics

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of talc for use in cosmetics. The safety of talc has been the subject of much debate through the years, partly because the relationship between talc and asbestos is commonly misunderstood. Industry specifications state that cosmetic-grade talc must contain no detectable fibrous, asbestos minerals. Therefore, the large amount of available animal and clinical data the Panel relied on in assessing the safety of talc only included those studies on talc that did not contain asbestos. The Panel concluded that talc is safe for use in cosmetics in the present practices of use and concentration (some cosmetic products are entirely composed of talc). Talc should not be applied to the skin when the epidermal barrier is missing or significantly disrupted.

Pleural mesothelial cells in pleural and lung diseases

During development, the mesoderm maintains a complex relationship with the developing endoderm giving rise to the mature lung. Pleural mesothelial cells (PMCs) derived from the mesoderm play a key role during the development of the lung. The pleural mesothelium differentiates to give rise to the endothelium and smooth muscle cells via epithelial-to-mesenchymal transition (EMT). An aberrant recapitulation of such developmental pathways can play an important role in the pathogenesis of disease processes such as idiopathic pulmonary fibrosis (IPF). The PMC is the central component of the immune responses of the pleura. When exposed to noxious stimuli, it demonstrates innate immune responses such as Toll-like receptor (TLR) recognition of pathogen associated molecular patterns as well as causes the release of several cytokines to activate adaptive immune responses. Development of pleural effusions occurs due to an imbalance in the dynamic interaction between junctional proteins, n-cadherin and β-catenin, and phosphorylation of adherens junctions between PMCs, which is caused in part by vascular endothelial growth factor (VEGF) released by PMCs. PMCs play an important role in defense mechanisms against bacterial and mycobacterial pleural infections, and in pathogenesis of malignant pleural effusion, asbestos related pleural disease and malignant pleural mesothelioma. PMCs also play a key role in the resolution of inflammation, which can occur with or without fibrosis. Fibrosis occurs as a result of disordered fibrin turnover and due to the effects of cytokines such as transforming growth factor-β, platelet-derived growth factor (PDGF), and basic fibroblast growth factor; which are released by PMCs. Recent studies have demonstrated a role for PMCs in the pathogenesis of IPF suggesting their potential as a cellular biomarker of disease activity and as a possible therapeutic target. Pleural-based therapies targeting PMCs for treatment of IPF and other lung diseases need further exploration.

Clinical importance of angiogenic cytokines, fibrinolytic activity and effusion size in parapneumonic effusions

OBJECTIVE

To investigate the relationship among angiogenic cytokines, fibrinolytic activity and effusion size in parapneumonic effusion (PPE) and their clinical importance.

METHODS

From January 2008 through December 2010, 26 uncomplicated (UPPE) and 38 complicated (CPPE) PPE were studied. Based on chest ultrasonography, there were non-loculated in 30, uni-loculated in 12, and multi-loculated effusions in 22 patients. The effusion size radiological scores, and effusion vascular endothelial growth factor (VEGF), interleukin (IL)-8, plasminogen activator inhibitor type-1 (PAI-1) and tissue type plasminogen activator (tPA) were measured on admission. Treatment outcome and pleural fibrosis, defined as radiological residual pleural thickening (RPT), were assessed at 6-month follow-up.

RESULTS

The effusion size and effusion VEGF, IL-8 and PAI-1/tPA ratio were significantly higher in CPPE than in UPPE, and significantly higher in multi-loculated PPE than in non-locualted and uni-loculated PPE, respectively. VEGF (cutoff value 1975 pg/ml) and IL-8 (cutoff value 1937 pg/ml) seemed best to discriminate between UPPE and CPPE. VEGF, IL-8 and effusion size correlated positively with PAI-1/tPA ratio in both UPPE and CPPE. Moreover, the level of VEGF, but not IL-8, correlated positively with effusion size in all patients (r = 0.79, p<0.001) and in UPPE (r = 0.64, p<0.001) and CPPE (r = 0.71, p<0.001) groups. The patients with higher VEGF or greater effusion were prone to have medical treatment failure (n = 10; VEGF, odds ratio 1.01, p = 0.02; effusion size, odds ratio 1.26, p = 0.01). Additionally, ten patients with RPT had larger effusion size and higher levels of VEGF and PAI-1/tPA ratio than did those without.

CONCLUSIONS

In PPE, VEGF and IL-8 levels are valuable to identify CPPE, and higher VEGF level or larger effusion is associated with decreased fibrinolytic activity, development of pleural loculation and fibrosis, and higher risk of medical treatment failure.

TLR2 in pleural fluid is modulated by talc particles during pleurodesis

The aim of this study was to examine the role of TLR2 molecule in pleural space during thoracoscopic talc pleurodesis period in patients with malignant pleural effusion. We analyzed TLR2 molecule in soluble form as well as on membrane of granulocytes in pleural fluid. Pleural fluid examination was done at three intervals during pleurodesis procedure: 1st—before the thoracoscopic procedure, 2nd—2 hours after the terminating thoracoscopic procedure with talc insufflation, 3rd—24 hours after the thoracoscopic procedure. We reported significant increase of soluble TLR2 molecule in pleural fluid effusion during talc pleurodesis from preoperative value. This increase was approximately 8-fold in the interval of 24 hours. The changes on granulocyte population were quite different. The mean fluorescent intensity of membrane TLR2 molecule examined by flow cytometry on granulocyte population significantly decreased after talc exposure with comparison to prethoracoscopic density. To estimate the prognostic value of TLR2 expression in pleural fluid patients were retrospectively classified into either prognostically favourable or unfavourable groups. Our results proved that patients with favourable prognosis had more than 3-fold higher soluble TLR2 level in pleural fluid early, 2 hours after talc pleurodesis intervention.

The dynamics of selected local inflammatory markers to talc in the treatment of malignant pleural effusions

BACKGROUND

Malignant pleural effusions accumulate in the space between the visceral (inner) layer covering the lungs and the parietal (outer) layer covering the chest wall. Larger effusions compress the pulmonary parenchyma resulting in increasing dyspnoea. Treatment is always local and palliative. Among others, chemical pleurodesis using talc can be performed in selected patients. Talc is hydrated magnesium silicate (chemically H₂Mg₃(SiO₃)₄) and has been used for pleurodesis since 1935. Videothoracoscopic talc powder insufflation (talc poudrage) is the most effective.However, markers of inflammatory reactions to extraneous substances like talc are not fully understood. The aim of this study was to assess the course of local inflammatory changes in the pleural cavity after talc insufflation.

METHODS

The Department of Cardiac Surgery of the Faculty of Medicine and University Hospital in Hradec Kralove, treated 47 patients aged 65 on average; 29 males and 18 females with proven recurrent malignant pleural effusion of various aetiologies from January 2009 to December 2010. They were retrospectively divided into group A (40 patients) without recurring effusion, and group B (7 patients) with recurring effusion and the need for thoracentesis or chest drainage during the 9-month monitoring.

RESULTS

Major findings were made in soluble forms of cell receptors. Group B showed statistically higher levels of the anti-inflammatory form of sCD-163 receptor in pleural fluid before the talc poudrage. This showed limited ability to create an adequate inflammatory response to external stimuli. This group also showed lower levels of the inflammatory form of sTLR-2 receptor immediately after the talc insufflation. This revealed low local reactivity to external stimuli. The effect of the treatment was not influenced by morphologic tumour type. No statistically significant differences in postoperative complications were found. This confirmed the safety of both videothoracoscopy and treatment.

CONCLUSIONS

There was no correlation between the type of malignant affection and the outcome of the chemical pleurodesis. Patients with relapsing effusion have higher values of concentration of anti-inflammatory sCD-163 in pleural fluid even before the application of talc, and lower levels of concentration of inflammatory sTLR-2 immediately after application of talc.

Role of talc modulation on cytokine activation in cancer patients undergoing pleurodesis

We investigate the mechanism of talc pleurodesis (TP) in 20 patients with recurrent malignant pleural effusion and 10 patients with nonmalignant pleural effusions. We measured IL-8 levels before and 6 h after TP and find a significant threefold increase (2.26 ng/mL ± 0.7 to 6.5 ng/mL 0.1), which explains the recruitment of inflammatory cells in these patients. We hypothesize that TP is enable by stimulating the mesothelial cells (MS) to secrete FGF. A significant tenfold increase in FGF-b (0.05 ng/mL ± 0.02 to 0.44 ng/mL 0.6) was seen 24 h after talc instillation (P < 0.04). In order to examine whether FGF-b is secreted by MS cells, MS recovered from CHF patients with recurrent pleural effusions were cultured for 48 h in the presence or absence of increasing concentrations of talc (from 100 ng/mL to 1 mg/mL). They produced significant levels of FGF-b in a dose dependent manner (P < 0.005). We hypothesized that a successful pleurodesis involves an early enhanced recruitment of inflammatory cells through a rise of IL-8 followed by enrollment of fibroblasts from the submesothelial space through increased mesothelial FGF-b production.

Role of toll-like receptor 3, RIG-I, and MDA5 in the expression of mesothelial IL-8 induced by viral RNA

Interleukin-8 (IL-8) is a chemokine that has been shown to be a potent chemoattractant for polymorphonuclear neutrophils from the vascular compartment into the pleural space during infectious pleural effusions. Mesothelial cells express the viral receptors Toll-like receptor 3 (TLR3), RIG-I, and MDA5. Activation of these receptors by viral RNA exemplified by poly (I:C) RNA leads to a time- and dose-dependent increase of mesothelial IL-8 synthesis. To show the specific effect of viral receptors, knockdown experiments with short interfering RNA specific for TLR3, RIG-I and MDA5 were performed. This novel finding of functional expression of these viral sensors on human mesothelial cells may indicate a novel link between viral infections and mesothelial inflammation and indicates a pathophysiologic role of viral receptors in these processes.

Pleural mesothelial cells express both BLT2 and PPARalpha and mount an integrated response to pleural leukotriene B4

Leukotriene B(4) (LTB(4)) plays a crucial role in the recruitment of neutrophils into the pleural space. We identified for the first time the mechanisms by which LTB(4) interacts with mesothelial cells and recruits neutrophils in the pleural compartment. Primary pleural mesothelial cells express both the proinflammatory receptor for LTB(4) BLT2, and the anti-inflammatory receptor for LTB(4), PPARalpha. Parapneumonic pleural effusions highly increase BLT2 expression and, via BLT2 activation, increase the adhesion between mesothelial cells and neutrophils and the expression of ICAM-1 on mesothelial cells. The block of PPARalpha further increases both cell adhesion and ICAM-1 expression. BLT2 activation promotes the activation, on mesothelial cells, of STAT-1 but not the activation of NF-kappaB transcription factor. The increase of ICAM-1 expression is achieved via increased tyrosine phosphorylation activity since herbimycin, a tyrosine kinase inhibitor, reduces and since Na orthovanadate, a tyrosine phosphatase inhibitor, further increases ICAM-1 expression. This study demonstrates that pleural mesothelial cells, expressing both proinflammatory and anti-inflammatory LTB(4) receptors, are able to mount an integrated response to LTB(4) with a prevalence of BLT2 activities in the presence of an inflammatory milieu within the pleura.

Pathophysiology of the pleura

The pleural mesothelial cell is an essential cell in maintaining the normal homeostasis of the pleural space and it is also a central component of the pathophysiologic processes affecting the pleural space. In this review, we will review the defense mechanisms of the pleural mesothelium and changes in pleural physiology as a result of inflammatory, infectious, and malignant conditions with a focus on cytokine and chemokine networks. We will also review the processes involved in the pathogenesis of pleural fibrosis.

Expression of CXC and CC type of chemokines and its receptors in tuberculous and non-tuberculous effusions

Chemokines mediate their biological functions by transmigration of various immune cells to the site of infection. Tuberculous pleurisy provides an effective model to study the role of chemokines in the recruitment of immune cells to the pleura. Our aim was to understand the cumulative effect of chemokines (IP-10, MIG, IL-8, MCP-1, MIP-1alpha and RANTES) and its receptors (CXCR2, CXCR3, CCR1, CCR2, CCR5 and CCR7) in the recruitment of CD4(+) T cells obtained from blood (BL) and pleural fluid (PF) of tuberculous (TB) and non-tuberculous (NTB) patients. We observed significant increase in CD4(+) T cells in TB PF indicating lymphocytic rich effusion. All chemokines except RANTES were significantly high in PF compared to BL in TB group, whereas IL-8 and MCP-1 showed significant increase only in NTB PF. The significantly high levels of IFN-gamma and TauNuF-alpha in TB PF and their positive correlation with IP-10 and MIP-1alpha indicated their synergistic action to elicit a strong protective Th1 response. In spite of high levels of Th1 cytokines and chemokines in TB PF, significantly lower levels of RANTES indicated its limited role at the site. The CXC receptors in PF of both the groups and CC receptors except CCR5 in TB PF were significantly high compared to BL. Only CXCR2, CCR5 and CCR7 showed significant increase in TB compared to NTB. Thus a selective concentration of chemokines, cytokines and abundant expression of chemokine receptors confirm the accumulation of activated and memory T cells at the site of infection and help in polarizing Th1 immune response.

Pleural fibrosis

Pleural fibrosis can result from a variety of inflammatory processes. The response of the pleural mesothelial cell to injury and the ability to maintain its integrity are crucial in determining whether normal healing or pleural fibrosis occurs. The pleural mesothelial cell, various cytokines, and disordered fibrin turnover are involved in the pathogenesis of pleural fibrosis. The roles of these mediators in producing pleural fibrosis are examined. This article reviews the most common clinical conditions associated with the development of pleural fibrosis. Fibrothorax and trapped lung are two unique and uncommon consequences of pleural fibrosis. The management of pleural fibrosis, including fibrothorax and trapped lung, is discussed.

The effects of erythromycin on the viability and the secretion of TNF-alpha and TGF-beta1 and expression of connexin43 by human pleural mesothelial cells

OBJECTIVE

The mechanism by which erythromycin produces pleurodesis remains unknown. The purpose of this study was to investigate the effects of erythromycin on human pleural mesothelial cell (HPMC) viability, the secretion of tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta(1) (TGF-beta(1)) and the level of expression of connexin43.

METHODOLOGY

HPMC were incubated with different concentrations of erythromycin. The inhibitory effects of erythromycin on HPMC growth were measured using a tetrazolium-based colorimetric assay. The levels of TNF-alpha and TGF-beta(1) in supernatants were measured by ELISA and levels of connexin43 were assessed by Western blot.

RESULTS

Erythromycin injured HPMC in a dose and time-dependent manner. The secretion of both TNF-alpha and TGF-beta(1) by HMPC increased significantly when they were incubated with 100 mg/L erythromycin for 3 or 5 days. The levels of connexin43 in HPMC decreased after incubation with 100 mg/L erythromycin and no relationship was observed between the levels and incubation time.

CONCLUSIONS

Erythromycin injures HPMC in a dose- and time-dependent manner and results in the secretion of TNF-alpha and TGF-beta(1). This is one possible mechanism of pleurodesis with erythromycin. Furthermore, erythromycin decreased the levels of connexin43 in HPMC, which could possibly affect the response of HPMC to pleurodesis with erythromycin.

Reactive oxygen species mediated calcium oxalate crystal-induced expression of MCP-1 in HK-2 cells

Under severe hyperoxaluric conditions calcium oxalate crystals often deposit in the renal interstitium and produce localized inflammation. We have proposed that renal epithelial cells exposed to CaOx crystals produce chemoattractants such as monocyte chemoattractant protein-1 (MCP-1). MCP-1 synthesis is mediated by reactive oxygen species (ROS). HK-2 cells of human renal epithelial line were exposed to CaOx crystals for different lengths of time. The culture media was tested for cell injury marker LDH, and subjected to enzyme-linked immunosorbent assay to determine the secretion of MCP-1 protein. Cell expression of MCP-1 was assessed by Western blot analysis. Gene expression was determined by reverse transcriptase-polymerase chain reaction. The data clearly showed that the HK-2 cells express MCP-1 gene and protein. The MCP-1 mRNA expression was increased following exposure to CaOx crystals, which was reduced upon treatment with free radical scavengers, catalase and superoxide dismutase. Results indicate that CaOx crystals strongly induce MCP-1 synthesis and secretion by the HK-2 cells and production is mediated by intracellular ROS production. Based on these and other data, antioxidant therapy and blockade of rennin-angiotensin system may prove beneficial for the prevention of end stage renal disease caused by hyperoxaluria and CaOx crystal deposition.

Oxalate induced expression of monocyte chemoattractant protein-1 (MCP-1) in HK-2 cells involves reactive oxygen species

Oxalate is a toxic end product of metabolism largely because of its propensity to crystallize and form calcium oxalate, which is insoluble at physiologic pH and often deposits at very unfortunate sites, notably the kidneys. In the current study, we investigated the oxalate-induced injury and up-regulation of monocyte-chemoattractant protein-1 (MCP-1) in HK-2 cells, a proximal tubular epithelial cell line derived from normal human kidney. The cells were exposed to oxalate ions for different lengths of time. The culture media was tested for LDH release, a cell injury marker. mRNA was isolated from the cells and subjected to reverse transcriptase-polymerase chain reaction. The data showed that oxalate exposure resulted in cell injury in a time and concentration dependent manner. The MCP-1 mRNA increased following exposure to oxalate and was reduced upon treatment with free radical scavengers, catalase and superoxide dismutase. These data support the importance of reactive oxygen species in the induction of expression of MCP-1 in renal epithelial cells. To our knowledge, this is the first report of MCP-1 expression and its upregulation by oxalate exposure in HK-2 cells.

Pathogenesis of pleural fibrosis

Pleural fibrosis resembles fibrosis in other tissues and can be defined as an excessive deposition of matrix components that results in the destruction of normal pleural tissue architecture and compromised function. Pleural fibrosis may be the consequence of an organised haemorrhagic effusion, tuberculous effusion, empyema or asbestos-related pleurisy and can manifest itself as discrete localised lesions (pleural plaques) or diffuse pleural thickening and fibrosis. Although the pathogenesis is unknown, it is likely that the complex interactions between resident and inflammatory cells, profibrotic mediators and coagulation, and fibrinolytic pathways are integral to pleural remodelling and fibrosis. It is generally considered that the primary target cell for pleural fibrosis is the subpleural fibroblast. However, increasing evidence suggests that mesothelial cells may also play a significant role in the pathogenesis of this condition, both by initiating inflammatory responses and producing matrix components. A greater understanding of the interactions between pleural and inflammatory cells, cytokines and growth factors, and blood derived proteins is required before adequate therapies can be developed to prevent pleural fibrosis from occurring.

Talc Pleurodesis

STUDY OBJECTIVES

Patients with recurrent pleural effusions secondary to malignancy are subjected to pleurodesis if clinically indicated. Pleurodesis involves the introduction of a sclerosing agent into the pleural space. Talc is one of the most commonly used sclerosing agents in treating patients with recurrent, symptomatic malignant pleural effusions. However, the mechanisms whereby talc mediates pleural fibrosis remain unclear. We hypothesized that the intrapleural instillation of talc induces the pleural mesothelial production of basic fibroblast growth factor (bFGF), which is responsible for pleural fibrosis.

METHODS

Samples of pleural fluid collected from 23 patients with malignant pleural effusions and 6 patients with congestive heart failure (control group) were included in this study. A tumor grading scale (1 to 9) was used to demonstrate the extent of the tumor. In vitro pleural mesothelial cells (PMCs) were activated with talc, and the conditioned medium was collected to evaluate bFGF levels by enzyme-linked immunosorbent assay. The bFGF-induced proliferation of fibroblasts was studied by [(3)H]thymidine incorporation. The messenger RNA expression of bFGF in talc-activated PMCs was determined by Northern analysis.

RESULTS

In this study, we demonstrated that patients who have undergone successful pleurodesis following intrapleural talc insufflation have significantly higher levels of bFGF in their pleural fluid compared to those who do not respond to pleurodesis. In addition, we found a significant negative correlation between bFGF levels and tumor size. Talc-activated PMCs produce significantly higher levels of bFGF compared to control, which correlates with bFGF messenger RNA expression in PMCs stimulated with talc. The neutralization of pleural fluids and conditioned medium from talc-stimulated PMCs with bFGF antibodies significantly inhibits the bFGF-induced proliferation of pleural fibroblasts.

CONCLUSIONS

An important outcome of this study was the finding that patients with extensive tumor involvement of the pleural mesothelium have a significantly lower pleural fluid bFGF response to talc compared to those who have limited involvement. Patients with limited pleural disease and higher bFGF responses go on to have successful pleurodesis, demonstrating that the presence of a mesothelium that is free of tumor enhances the possibility of success. In vitro PMCs stimulated with talc release biologically active bFGF.

Pleurodesis practice for malignant pleural effusions in five English-speaking countries: survey of pulmonologists

BACKGROUND

Pleurodesis is important in the management of malignant pleural effusions, but no consensus exists on the optimal agent or methods of pleurodesis. How pleurodesis is practiced worldwide has not been studied.

OBJECTIVES

To identify variations in the clinical practice of pleurodesis in major English-speaking countries, and to quantify the experience of pulmonologists on the effectiveness and adverse effects of different pleurodesis agents worldwide.

METHODS

Eight hundred fifty-nine pulmonologists practicing in the United States, United Kingdom, Canada, Australia, and New Zealand participated in a Web-based survey.

RESULTS

The respondents collectively perform > 8,300 pleurodesis annually. Talc was the preferred agent by most respondents (slurry, 56%; poudrage, 12%), followed by tetracycline derivatives (26%), and bleomycin (7%). Differences were seen in pleurodesis practice patterns among practitioners among and within the surveyed countries. Physicians' overall satisfaction with the available pleurodesis agents was modest (5.0 out of 8), and the reported success rate averaged only 66%. Talc (both poudrage and slurry) was perceived as significantly more effective, but was associated with significantly more pain, nausea, and fever (p < 0.05). Respiratory failure occurred more commonly with talc poudrage than with other agents (p < 0.05), and had been observed by 70% and 54% of physicians who used talc poudrage and slurry, respectively.

CONCLUSIONS

Significant variations exist in how pleurodesis is performed worldwide. Pleurodesis agents currently available are perceived as suboptimal. Talc poudrage and slurry were perceived to be more effective, but were associated with more complications, including respiratory failure.

Morphological analysis of leucocyte transmigration in the pleural cavity

The role that pleural mesothelial cells play in leucocyte transmigration into the pleural cavity was investigated in lipopolysaccharide-stimulated mice. Changes in mesothelial cell morphology and changes in expression of adhesion molecules on mesothelial cells and leucocytes were analysed by light microscopy, immunohistochemistry, transmission electron microscopy (TEM) and immuno-scanning electron microscopy (immuno-SEM). After stimulation, the mesothelial cells separated completely from one another before leucocyte penetration across the mesothelial layer occurred. These changes occurred primarily in the immediate vicinity of ribs, where a large number of leucocytes accumulated. Immuno-SEM showed that the expression of intercellular adhesion molecule-1 (ICAM-1) on the parietal pleural mesothelial cells was significantly up-regulated by lipopolysaccharide stimulation, and that of vascular cell adhesion molecule-1 (VCAM-1) was induced. Both were restricted to the microvilli of the mesothelial cells. By contrast, expression of intercellular adhesion molecule-2 (ICAM-2), platelet/endothelial cell adhesion molecule-1 (PECAM-1), mucosal addressin cell adhesion molecule-1 (MAdCAM-1), endothelial leucocyte adhesion molecule-1 (ELAM-1), peripheral node addressin (PNAd) and fibronectin were not detected. Lymphocyte function associated antigen-1 (LFA-1), macrophage-1 molecule (Mac-1) and very late appearing antigen-4 (VLA-4), all ligands of ICAM-1 and VCAM-1, were present on the transmigrated neutrophils and macrophages. These findings demonstrate that the immediate vicinity of ribs is a source of leucocyte migration into the pleural space.

Increased expression of monocyte chemoattractant protein-1 (MCP-1) by renal epithelial cells in culture on exposure to calcium oxalate, phosphate and uric acid crystals

BACKGROUND

During the development of non-infectious kidney stones, crystals form and deposit in the kidneys and become surrounded by monocytes/macrophages (M/M). We have proposed that in response to crystal exposure renal epithelial cells produce chemokines, which attract the M/M to the sites of crystal deposition. We investigated the expression of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein by NRK52E rat renal tubular epithelial cells exposed to calcium oxalate (CaOx), brushite (Br, a calcium phosphate) and uric acid (UA) crystals.

METHODS

Confluent cultures of NRK52E cells were exposed to CaOx, Br or UA at a concentration of 250 micro g/ml (66.7 micro g/cm(2)). They were exposed for 1, 3, 6, 12, 24 and 48 h for isolation of mRNA and 24 h for ELISA to determine the secretion of protein into the culture medium. Since cells are known to produce free radicals on exposure to CaOx crystals we also investigated the effect of free radical scavenger catalase on the crystal induced expression of MCP-1 mRNA and protein.

RESULTS

Exposure of NRK52E cells to the crystals resulted in increased expression of MCP-1 mRNA and production of the chemoattractant. CaOx crystals were most provocative while UA the least. Treatment with catalase had a negative effect on the increased expression of both MCP-1 mRNA and protein, which indicates the involvement of free radicals in up-regulation of MCP-1 production.

CONCLUSION

Exposure to both CaOx and calcium phosphate crystals stimulates increased production of MCP-1. Free radicals appear to be involved in this up-regulation. Results indicate that MCP-1, which is often associated with localized inflammation, may be one of the chemokine mediators associated with the deposition of various urinary crystals in the kidneys during kidney stone formation. Because of the small number of experiments performed here, results must be confirmed by more extensive studies with larger sample size.

Distribution of calibrated talc after intrapleural administration: an experimental study in rats

STUDY OBJECTIVE

Many reports have shown that talc is the most effective and least expensive agent for the creation of a pleural symphysis. However, its use still remains controversial due to severe acute respiratory side effects possibly related to the systemic dissemination of talc particles. The purpose of this study was to assess the distribution of calibrated talc after intrapleural administration in rats. MATERIAL AMD METHODS: Thirty-seven Wistar male rats were randomly assigned to undergo pleurodesis by talc slurry (33 rats) or by simple chest tube drainage (control group; 4 rats). Forty milligrams of calibrated talc suspended in 1 mL sterile saline solution was injected into rats in the treated group. The animals were randomly assigned for autopsy at 24 or 72 h after pleural injection. Lungs, parietal pleura, diaphragm, liver, kidneys, spleen, pericardium, brain, and blood were assessed by polarized light for birefringent talc particle detection and counting.

RESULTS

No deaths were observed. The autopsies showed no pleurodesis at 24 and 72 h. Despite high doses of talc (extrapolated from the dose of 10 g in a 70-kg adult man), few talc particles were found in the liver of two rats, in the spleen of one rat, and only one particle of talc was observed at the brain surface of the rat studied by scanning electron microscopy. No particles were found in the other organs, in particular in the contralateral lung and blood, contrasting with previously published results using noncalibrated talc particles.

CONCLUSIONS

The lack of systemic dispersion of talc particles, with the packaging talc we currently use in our clinical practice, is probably due to the size of the talc particles, which are larger than the other talc preparations. Calibrated talc is required in case of intrapleural administration for pleurodesis to avoid systemic dissemination and potential secondary acute respiratory failures.

Mesothelial cells: their structure, function and role in serosal repair

The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities and internal organs. Traditionally, this layer was thought to be a simple tissue with the sole function of providing a slippery, non-adhesive and protective surface to facilitate intracoelomic movement. However, with the gradual accumulation of information about serosal tissues over the years, the mesothelium is now recognized as a dynamic cellular membrane with many important functions. These include transport and movement of fluid and particulate matter across the serosal cavities, leucocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix proteins to aid in serosal repair, release of factors to promote both the deposition and clearance of fibrin, and antigen presentation. Furthermore, the secretion of molecules, such as glycosaminoglycans and lubricants, not only protects tissues from abrasion, but also from infection and possibly tumour dissemination. Mesothelium is also unlike other epithelial-like surfaces because healing appears diffusely across the denuded surface, whereas in true epithelia, healing occurs solely at the wound edges as sheets of cells. Although controversial, recent studies have begun to shed light on the mechanisms involved in mesothelial regeneration. In the present review, the current understanding of the structure and function of the mesothelium and the biology of mesothelial cells is discussed, together with recent insights into the mechanisms regulating its repair.

Influence of particle size on extrapleural talc dissemination after talc slurry pleurodesis

BACKGROUND

Cases of acute respiratory failure reported after talc pleurodesis have raised concerns about its safety. It has been speculated that this pulmonary inflammatory syndrome is secondary to the extrapleural dissemination of the talc particles.

STUDY OBJECTIVES

To test the hypothesis that particle size influences extrapleural talc deposition and pleural inflammation after talc slurry pleurodesis.

DESIGN

Thirty rabbits underwent pleurodesis as follows: 10 rabbits received 200 mg/kg of the talc used for human pleurodesis, normal talc (NT); 10 rabbits received 200 mg/kg of talc with particles of larger size, large talc (LT); and 10 rabbits received saline solution. Samples from the ipsilateral lung, chest wall, diaphragm, mediastinal pleura, heart, liver, spleen, and right kidney were obtained at 24 h and 7 days and processed for optic and electron microscopy and energy-dispersive x-ray analysis.

RESULTS

Visceral pleural thickening was greater with NT than with LT, but no differences were observed in the macroscopic score of adhesions. There was more talc in the lungs of the rabbits that received NT than in those that received LT. Talc particles were detected in mediastinum (100%) and pericardium (20%), irrespective of the talc used. Three animals, all receiving NT, had talc particles in the liver.

CONCLUSIONS

Our study shows that while both talcs were equally effective in achieving pleurodesis, the intrapleural injection of NT elicits greater pulmonary and systemic talc particle deposition than LT. Moreover, pleural inflammation was greater with NT than with LT.

Induction of MCP-1 expression in airway epithelial cells: role of CCR2 receptor in airway epithelial injury

The repair of an injured bronchial epithelial cell (BEC) monolayer requires proliferation and migration of BECs into the injured area. We hypothesized that BEC monolayer injury results in monocyte chemoattractant protein-1 (MCP-1) production, which initiates the repair process. BECs (BEAS-2B from ATCC) were utilized in this study. MCP-1 interacts with CCR2B receptor (CCR2B), resulting in cell proliferation, haptotaxis, and healing of the monolayer. Reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to verify the presence of CCR2B. CCR2B was not merely present but also inducible by interleukin-2 (IL-2) and lipopolysaccharide (LPS). We demonstrated by immunohistochemistry that BECs express MCP-1 after injury and that receptor expression can be regulated by exposure to IL-2 and LPS. Haptotactic migration of cells was enhanced in the presence of MCP-1 and reduced in the presence of CCR2B antibody. This enhanced or depressed ability of the BECs to perform haptotactic migration was shown to be statistically significant (P < 0.05) when compared to controls. Finally, BECs proliferate in response to MCP-1 as proven by electric cell-substrate impedance sensing (ECIS) technology. MCP-1-specific antibodies were shown to neutralize the MCP-1-mediated BEC proliferation. This cascade of events following injury to the bronchial epithelium may provide insight into the mechanism of the repair process.

Inflammatory cytokines mediate C-C (monocyte chemotactic protein 1) and C-X-C (interleukin 8) chemokine expression in human pleural fibroblasts

Current knowledge implicates pleural mesothelial cells as mainly responsible for inflammatory responses in the pleural space. However, a vast body of recent evidence underscores the important role of fibroblasts in the process of inflammation in several types of tissues. We hypothesize that HPFBs (human pleural fibroblasts) play an important role in pleural responses and also when activated by bacterial endotoxin LPS (lipopolysaccharide), IL-1 beta (interleukin-1 beta), or TNF-alpha (tumor necrosis factor-alpha) release of C-C and C-X-C chemokines-specifically, MCP-1 and IL-8. Our results show that pleural fluid-isolated human fibroblasts release IL-8 and MCP-1 upon stimulation with IL-1 beta, TNF-alpha, and LPS in both a concentration- and time-dependent manner. RT-PCR (reverse-transcriptase-polymerase chain reaction) studies have also confirmed IL-8- and MCP-1-specific mRNA expression in activated pleural fibroblasts. On the time-dependent response curve, IL-8 was found in maximum concentrations at 144 hr, whereas MCP-1 continued to increase even after 196 hr following stimulation. IL-1 beta induced the maximum release of IL-8 (800-fold) and MCP-1 (164-fold), as compared to the controls. TNF-alpha induced a 95-fold increase in IL-8 and an 84-fold increase in MCP-1 levels, as compared to the controls. Collectively, our results show that human pleural fibroblasts contribute to the inflammatory cascade in the pleural space.

Talc preparations used for pleurodesis vary markedly from one preparation to another

BACKGROUND

At the present time, talc is the one of the agents most commonly used for the production of a pleurodesis. However, there have been several recent reports of acute pneumonitis developing after the intrapleural administration of talc. The incidence of pneumonitis has varied markedly from center to center.

OBJECTIVE

To compare the physical characteristics of talc used for the production of pleurodesis in various localities.

DESIGN

Eight talc preparations (four from the United States, and one each from Brazil, France, Spain, and Taiwan) were analyzed for the distribution of the particle size and the type and amount of impurities.

MEASUREMENTS

The physical characteristics of the talc specimens were determined using radiograph diffraction and scanning electron microscopy.

RESULTS

The mean and median particle size varied by more than a factor of three among the eight different talc preparations. In addition, the impurities of the different talc preparations were quite varied.

CONCLUSIONS

We conclude that there is marked variation in the physical characteristics of the talc preparations used intrapleurally for the production of a pleurodesis. We speculate that different incidences of acute pneumonitis at various centers after intrapleural administration of talc may be due to differences in the physical characteristics of the talc preparations used for pleurodesis.

MCP-1 in pleural injury: CCR2 mediates haptotaxis of pleural mesothelial cells

Pleural injury results in the death of mesothelial cells and denudation of the mesothelial basement membrane. Repair of the mesothelium without fibrosis requires proliferation and migration of mesothelial cells into the injured area. We hypothesized that monocyte chemoattractant protein-1 (MCP-1) induces proliferative and haptotactic responses in pleural mesothelial cells (PMCs) and that the MCP-1 binding receptor CCR2 mediates the pleural repair process. We demonstrate that PMCs exhibited MCP-1-specific immunostaining on injury. MCP-1 induced proliferative and haptotactic responses in PMCs. PMCs express CCR2 in a time-dependent manner. Fluorescence-activated cell sorting analysis demonstrated that interleukin (IL)-2 upregulated CCR2 protein expression in PMCs, whereas lipopolysaccharide (LPS) downregulated the response at the initial period compared with that in resting PMCs. However, the inhibitory potential of LPS was lost after 12 h and showed a similar response at 24 and 48 h. Haptotactic migration was upregulated in PMCs that were cultured in the presence of IL-2. The increased haptotactic capacity of mesothelial cells in the presence of IL-2 correlated with increased CCR2 mRNA expression. PMCs cultured in the presence of LPS showed decreased haptotactic activity to MCP-1. Blocking the CCR2 with neutralizing antibodies decreased the haptotactic response of PMCs to MCP-1. These results suggest that the haptotactic migration of mesothelial cells in response to MCP-1 are mediated through CCR2, which may play a crucial role in reepithelialization of the denuded basement membrane at the site of pleural injury and may thus contribute to the regeneration of the mesothelium during the process of pleural repair.

Time-course analysis of type II cell hyperplasia and alveolar bronchiolization in rats treated with different particulates

In this study, we compared the morphological reaction patterns in rat lungs following a single intratracheal instillation of 20 mg quartz, 20 mg coal mine dust (15.3% quartz), or 25 mg talc. Control animals received a single dose of 0.5 ml saline solution intratracheally. Investigations by light microscopy, morphometry, and DNA image cytometry were carried out 3, 6, 12, and 18 mo after dust administration. During the investigation period, we observed a temporary increase in the number, area, and proliferative activity of the type II cells, which differed in intensity among the three dusts. After 18 mo, however, type II cells in treated animals did not differ from control animals. On the other hand, the expansion of a multifocal alveolar bronchiolization as putative preneoplastic lesion had progressed enormously by the end of the test (1-3% of the investigated lung area). Consistent with this, the proliferative activity of the epithelial cells in terminal bronchi of the coal mine dust- and quartz-treated animals was enhanced by the end of the 18-mo investigation period, while the reaction to talc was minimal (0.2% of totally investigated lung area). Our data suggest that in bronchiolo-alveolar regions, especially in the epithelium of terminal bronchi, there is an overshoot regeneration after cell damage that leads to an alveolar bronchiolization.

Helper T cell type 1 and 2 cytokines regulate C-C chemokine expression in mouse pleural mesothelial cells

The recruitment of leukocytes to an area of injury or inflammation site is one of the most fundamental host defenses. Pulmonary tuberculosis is characterized by granulomatous inflammation with an extensive infiltration of mononuclear cells. In tuberculous pleurisy pleural mesothelial cells are exposed to mycobacteria in the pleural space. In this study we demonstrate that mouse pleural mesothelial cells (PMCs), when stimulated with BCG or IFN-gamma, produced MIP-1alpha and MCP-1 in vitro. IFN-gamma enhanced the BCG-mediated MIP-1alpha and MCP-1 expression in a concentration-dependent manner. The RT-PCR studies also confirmed that both BCG and IFN-gamma induce chemokine expression. IL-4 inhibited the BCG-mediated MIP-1alpha and MCP-1 expression in a concentration-dependent manner. The lower concentrations of IL-4 were ineffective; however, at higher concentrations, the inhibitory effect of IL-4 persisted for 24 h and decreased thereafter. BCG stimulation resulted in an increase of IFN-gamma and IL-4 receptors on PMCs. Our results demonstrate that Th1 and Th2 cytokines may regulate the C-C chemokine expression in PMCs and thus play a biologically important role in mononuclear cell recruitment to the pleural space.

Respiratory failure following talc pleurodesis

BACKGROUND

Sterile talc is currently the agent of choice for pleurodesis. Its success rate is excellent, and talc is generally well tolerated. However, a recent experience with fulminant pneumonitis following talc pleurodesis prompted a review of our experience.

METHODS

A retrospective review of patients undergoing talc pleurodesis at our institution between December 1993 and December 1997 was performed, documenting respiratory and other complications. Statistical analysis was performed using Student's t test and Pearson correlations.

RESULTS

Seventy-eight patients received 89 talc pleurodesis procedures. Respiratory complications or death occurred in 33%; 9% of patients developed adult respiratory distress syndrome. There was no statistical difference in outcomes between patient groups, methods of application, or talc dosages utilized.

CONCLUSIONS

This series revealed a significantly higher rate of serious complications than that reported in the current literature, without implicating a clear reason for these outcomes. Our data raise questions about the safety of talc pleurodesis.