Talc and Silver Nitrate Induce Systemic Inflammatory Effects During the Acute Phase of Experimental Pleurodesis in Rabbits

Early Onset of Severe Interstitial Pneumonitis Associated With Anti-PD-1 Immune Checkpoint Antibody After Pleurodesis

We present a case of lung adenocarcinoma with malignant pleural effusion. Nineteen days after pleurodesis using minocycline and OK-432 (picibanil), pembrolizumab monotherapy was initiated. Four days later, the patient experienced a persistent cough. Chest computed tomography showed that ground-glass opacity appeared on the same side as pleurodesis and spread bilaterally thereafter, which was diagnostic of immune checkpoint inhibitors (ICI)-related pneumonitis. As he presented a severe respiratory failure, corticosteroid therapy was administered. Two weeks later, respiratory failure completely resolved and the abnormal shadows dramatically improved. Our results indicate that severe ICI-related pneumonitis can develop within a short period after pleurodesis.

[Analysis of endothelial dysfunction in the context of pleural effusions of various origins using skin thermometry]

OBJECTIVE

To analyze the mechanisms and severity of endothelial dysfunction in patients with pleural effusion of various origins using skin thermometry.

MATERIAL AND METHODS

We studied microcirculation in 135 patients with pleural effusions of various origins. Local skin thermometry and computer wavelet analysis were performed in 3-5 days after thoracoscopy with pleural biopsy using Microtest-100WF device with a temperature measuring resolution of 0.001°C. We estimated endothelial, myogenic and neurogenic indices using spectral analysis of skin temperature fluctuations in a range 0.0095-2 Hz. The control group comprised 40 healthy participants aged 23-36 years.

RESULTS

Three groups of patients were distinguished depending on the cause of effusion: malignant pleural effusions (n=65, 48.1%); inflammatory pleural effusions (para-pneumonic, post-traumatic, pancreatogenic, tuberculous) (n=58, 43%); transudates (hepatogenic, cardiogenic, and nephrogenic) (n=12, 8.9%). There were no significant differences in vascular tone in response to local heating of the second finger of the hand up to 40°C. Measurements were carried out within 10 min in all groups. Patients with diabetes mellitus and cardiovascular diseases (n=48, 35.6%) had significant decrease of thermal vasodilation index in endothelial range up to 2.93±1.77, in the control group - up to 4.21±2.40 (p=0.041).

CONCLUSION

Endothelial dysfunction is a universal non-specific aspect in pathogenesis of various diseases. This process is essential in pleural effusion. Local thermometry and computer wavelet analysis revealed no significant differences between patients with malignant, inflammatory and transudative pleural effusions. Pleural effusions in the context of cardiovascular pathology and/or diabetes mellitus occur due to impaired vasodilatation mechanisms in endothelial range.

Evaluation of cellular alterations and inflammatory profile of mesothelial cells and/or neoplastic cells exposed to talc used for pleurodesis

Introdution: To determine the role of Pleural Mesothelial Cells (PMC) and/or Neoplasic Cells (NC) in the initiation and regulation of acute inflammatory response after exposure to talc for evaluating inflammatory mediators and cellular alterations.

Materials and Methods: PMC cultures, human lung (A549) and breast (MCF7) adenocarcinoma cells were divided in 5 groups: 100% PMC, 100% NC, 25% PMC + 75% NC, 50% of each type and 75% PMC + 25% NC. All groups were exposed to talc and measured IL-6, IL-1β, IL-10, TNF-α, TNFRI, pH, LDH, apoptosis and necrosis. Statistical Analysis: One-way Anova.

Results: High IL-6, IL-1β and TNFRI levels were found in PMC and NC exposed to talc. IL-6 was higher at the points of more confluence of PMC. The highest levels of IL-1β and TNFRI were found in mixed cultures. In pure cultures TNFRI was higher in A549 followed by PMC and MCF7. LDH was higher in A549 than PMC. The lowest pH was found in 100% NC. All cell line exposed to talc reduced viability and increased necrosis. Apoptotic cells exposed to talc were higher in pure cultures of NC than in PMC. Mixed cultures of PMC and A549 showed lower levels of apoptosis in cultures with more NC.

Conclusions: PMC after talc exposure participates in the inflammatory process contributing to production of molecular mediators, necessary for effective pleurodesis. Talc acted in NC causing higher rates of apoptosis, contributing in a modest way to tumoral decrease. Different types of tumor cells may respond differently to exposure to talc.

Impact of systemic steroid treatment on talc pleurodesis: a report of six cases

Background

Instillation of sterile graded talc in the pleural space is performed to prevent reaccumulation of malignant pleural effusion after drainage. Talc is thought to encourage pleural adhesions as part of the repair process by provoking inflammation, suggesting that adhesions are less likely to form in patients taking corticosteroids or other drugs with anti-inflammatory effects. However, the relationship between steroid therapy and pleurodesis efficacy remains unclear.

Case presentation

We report the outcomes of six patients who underwent pleurodesis at Hiroshima University Hospital while being treated with systemic steroid therapy for non-cancer-related illnesses. Talc pleurodesis was successful at the first attempt in five of the six patients. The five successful cases were receiving low-dose oral prednisolone or methyl prednisolone (range, 1-20 mg/day) at the time of pleurodesis and had serum albumin levels ranging from 2.2 to 3.0 g/dL. In contrast, the patient in whom pleurodesis was unsuccessful was receiving a higher dose of prednisolone (40 mg/day) intravenously and had a relatively low serum album level (1.7 g/dL).

Conclusions

The outcome of pleurodesis may be affected by the dose and/or route of systemic steroid therapy. Further analysis with more patients will be necessary to clarify the relationship between steroid dosage and talc pleurodesis success rate.

Anaphylactic Shock Caused by Talc Pleurodesis Performed for Postoperative Air Leakage

Chemical pleurodesis, including talc pleurodesis, has been commonly used to prevent malignant pleural effusions and pneumothorax. This report describes a case of anaphylactic shock caused by talc pleurodesis. A 69-year-old woman who had prolonged air leakage after lobectomy underwent talc pleurodesis. Just after the talc administration, she went into shock. We immediately treated her for anaphylactic shock and simultaneously removed talc from the thoracic cavity through a thoracic tube. She subsequently recovered from shock. She had no further symptoms and was discharged 10 days after pleurodesis. Talc pleurodesis rarely causes severe complications, but it is necessary to treat these appropriately when they occur.

Talc Pleurodesis: A Medical, Medicolegal, and Socioeconomic Review

BACKGROUND

Talcum has been used in pleurodesis for more than 8 decades. Despite a wealth of research, controversy remains over the optimal sclerosant for pneumothorax and pleural effusions. Talc's historical primacy has been challenged because of its potential for pulmonary toxicity, possible carcinogenicity, and recent concerns surrounding availability and legal liability, thus making this an ideal time for a review.

METHODS

This systematic review of the talc literature, focused on publications after the year 2000, evaluated mechanism of action, efficacy, side effect profile, and alternative sclerosants; included is an overview of current socioeconomic and legal controversies.

RESULTS

The data support talc as the most effective agent for pleurodesis. There is evidence to suggest that mean particle size has a direct relationship with the side effect profile and that significant hypoxemic events after talc administration are exceedingly rare when using available graded talc preparations. Concerns regarding the development of malignant diseases after topical talc application remain incompletely resolved but appear related to cosmetic powder preparations that were contaminated with asbestos. Purified talc in the pleural space has not been implicated. Recent difficulties accessing commercial talc preparations have been solved. Although safe and effective talc alternatives do exist, these agents are not as well studied.

CONCLUSIONS

Talc pleurodesis with modern, purified, graded talc preparations is safe and highly effective. Talc is an inexpensive and accessible option that remains appropriate for pleurodesis despite existing controversies.

Description of Particle Size, Distribution, and Behavior of Talc Preparations Commercially Available Within the United States

BACKGROUND

Widespread use of talc pleurodesis remains controversial for many providers concerned by adverse events such as respiratory failure, which are sometimes fatal. Particle talc size has been implicated in these adverse effects, mainly on the basis of animal studies utilizing large amounts of talc or in observational studies performed on different continents with different talc preparations and doses. Our aim was to determine the particle size and distribution of only the commercially available US-talc preparations and whether the fluid content can affect this distribution.

METHODS

Commercially available US talc was evaluated under scanning electron microscopy and dynamic light scattering (DLS). Distribution of talc particle size was obtained in saline and various protein-based solutions.

RESULTS

Talc particle size by DLS was performed with commercially available Sterile Talc Powder and Sclerosol Intrapleural Aerosol. Sterile Talc Powder demonstrated a median diameter of 26.57 μm with a range of particle sizes from 0.399 μm to 100.237 μm. Sclerosol demonstrated a median diameter of 24.49 μm with a range of particle sizes from 0.224 μm to 100.237 μm. The exposure of talc to a protein rich environment (bovine serum albumin and human pleural fluid) led to the development of measureable, new, larger aggregated particle (>100 μm).

CONCLUSIONS

Currently available US talc seems to have size characteristics similar to previous described "graded" talc preparations. The exposure of talc to a protein rich environment seems to modify the overall distribution of talc particle size when examined by DLS.

Severe interstitial pneumonia associated with anti-PD-1 immune checkpoint antibody after talc slurry pleurodesis

A 70-year-old Japanese man with recurrent squamous cell carcinoma of the head and neck presented with severe interstitial pneumonia associated with nivolumab, after talc slurry pleurodesis. Following the development of malignant pleural effusion, he underwent chest drainage and was administered intrathoracic talc as a pleurodesis. Two weeks later, we administered nivolumab (3mg/kg) to be repeated every 2 weeks. However, on day 12, chest computed tomography scan demonstrated diffuse non-segmental ground-glass opacity and mild bronchiectasis. We diagnosed interstitial pneumonia associated with nivolumab. Although corticosteroid pulse therapy was initiated, the patient died of respiratory failure on day 14.

Local and systemic effects of fibrin and cyanoacrylate adhesives on lung lesions in rabbits

OBJECTIVES

Tissue adhesives can be used to prevent pulmonary air leaks, which frequently occur after lung interventions. The objective of this study is to evaluate local and systemic effects of fibrin and cyanoacrylate tissue adhesives on lung lesions in rabbits.

METHODS

Eighteen rabbits were submitted to videothoracoscopy + lung incision alone (control) or videothoracoscopy + lung incision + local application of fibrin or cyanoacrylate adhesive. Blood samples were collected and assessed for leukocyte, neutrophil and lymphocyte counts and interleukin-8 levels preoperatively and at 48 hours and 28 days post-operatively. After 28 days, the animals were euthanized for gross examination of the lung surface, and lung fragments were excised for histopathological analysis.

RESULTS

Fibrin and cyanoacrylate produced similar adhesion scores of the lung to the parietal pleura. Microscopic analysis revealed uniform low-cellular tissue infiltration in the fibrin group and an intense tissue reaction characterized by dense inflammatory infiltration of granulocytes, giant cells and necrosis in the cyanoacrylate group. No changes were detected in the leukocyte, neutrophil or lymphocyte count at any time-point, while the interleukin-8 levels were increased in the fibrin and cyanoacrylate groups after 48 hours compared with the pre-operative control levels (p<0.01).

CONCLUSION

Both adhesive agents promoted normal tissue healing, with a more pronounced local inflammatory reaction observed for cyanoacrylate. Among the serum markers of inflammation, only the interleukin-8 levels changed post-operatively, increasing after 48 hours and decreasing after 28 days to levels similar to those of the control group in both the fibrin and cyanoacrylate groups.

Influence of a low dose of silver nanoparticles on cerebral myelin and behavior of adult rats

Nanoscale particles have large surface to volume ratio that significantly enhances their chemical and biological reactivity. Although general toxicity of nano silver (nanoAg) has been intensively studied in both in vitro and in vivo models, its neurotoxic effects are poorly known, especially those of low-dose exposure. In the present study we assess whether oral administration of nanoAg influences behavior of exposed rats and induces changes in cerebral myelin. We examine the effect of prolonged exposure of adult rats to small (10nm) citrate-stabilized nanoAg particles at a low dose of 0.2mg/kg b.w. (as opposed to the ionic silver) in a comprehensive behavioral analysis. Myelin ultrastructure and the expression of myelin-specific proteins are also investigated. The present study reveals slight differences with respect to behavioral effects of Ag(+)- but not nanoAg-treated rats. A weak depressive effect and hyperalgesia were observed after Ag(+) exposure whereas administration of nanoAg was found to specifically increase body weight and body temperature of animals. Both nanoAg and Ag(+) induce morphological disturbances in myelin sheaths and alter the expression of myelin-specific proteins CNP, MAG and MOG. These results suggest that the CNS may be a target of low-level toxicity of nanoAg.

Abrasion Plus Local Fibrin Sealant Instillation Produces Pleurodesis Similar to Pleurectomy in Rabbits

BACKGROUND

Pleurodesis performed either by pleurectomy or pleural abrasion is recommended in the approach to primary spontaneous pneumothorax to avoid recurrence. However, the efficacy of parietal pleural abrasion in producing pleurodesis is questioned. This study aims to determine the efficacy of apical abrasion alone, abrasion plus fibrin sealant application, and pleurectomy in producing pleurodesis in rabbits.

METHODS

Rabbits were subjected to video-assisted thoracic surgery alone (control) or to video-assisted thoracic surgery with apical gauze abrasion, abrasion plus fibrin sealant instillation, or apical pleurectomy. Blood samples were collected preoperatively and 48 h and 28 days postoperatively to measure total leukocytes (white blood cell count), neutrophil counts, and serum interleukin (IL)-8 levels. After 28 days the animals were sacrificed for macroscopic evaluation of the degree of apical pleurodesis and microscopic evaluation of local pleural fibrosis and collagen deposition.

RESULTS

White blood cell and neutrophil counts were similar in all groups, whereas the serum IL-8 level peaked at 48 h in all groups and decreased after 28 days, except in the pleurectomy group. After 28 days the abrasion plus fibrin sealant and pleurectomy groups had significantly more pleural adhesions, pleural fibrosis, and collagen deposition than the abrasion alone group, mainly due to thick mature fibers.

CONCLUSIONS

Abrasion with local fibrin sealant instillation is as effective as pleurectomy in producing pleurodesis in rabbits. Apical pleurectomy elicits a more persistent elevation of serum IL-8 levels than apical abrasion alone or abrasion plus fibrin adhesive instillation.

Effectiveness and safety of iodopovidone in an experimental pleurodesis model

OBJECTIVES

Chemical pleurodesis is an important therapeutic tool to control recurrent malignant pleural effusion. Among the various sclerosing agents, iodopovidone is considered effective and safe. However, in a recent study, ocular changes were described after iodopovidone was used in recurrent pneumothorax. The aim of the study was to evaluate the efficacy and morbidity of iodopovidone pleurodesis in an experimental model.

METHODS

New Zealand rabbits were submitted to intrapleural injection of iodopovidone at concentrations of 2%, 4% and 10%. Biochemical (lactic dehydrogenase, proteins, triiodothyronine, free thyroxine, urea and creatinine) and immunological (Interleukin-8 [IL-8], VEGF and TGFβ) parameters were measured in the pleural fluid and blood. After 1, 3, 7, 14 and 28 days, groups of animals were euthanized, and macro- (pleura) and microscopic (pleura and retina) analyses were performed.

RESULTS

An early pleural inflammatory response with low systemic repercussion was observed without corresponding changes in thyroid or renal function. The higher concentrations (4% and 10%) correlated with greater initial exudation, and maximum pleural thickening was observed after 28 days. No changes were observed in the retinal pigment epithelium of the rabbits.

CONCLUSION

Iodopovidone is considered to be an effective and safe sclerosing agent in this animal model. However, its efficacy, tolerance and safety in humans should be further evaluated.

Monoclonal antibodies anti-TGFβ1 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 β (TGFβ1) 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-TGFβ1, 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-TGFβ1 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 TGFβ1 and VEGF, but not IL-8, mediate the pleural inflammatory response and pleurodesis induced by SN.

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.

Blockage of vascular endothelial growth factor (VEGF) reduces experimental pleurodesis

BACKGROUND AND OBJECTIVE

Chemical pleurodesis controls recurrent malignant pleural effusion. The mechanism that determines pleural symphysis involves the action of vascular endothelial growth factor (VEGF). We assessed the influence of the anti-VEGF antibody (bevacizumab) on pleurodesis induced by talc or silver nitrate and analyzed the temporal development of pleural angiogenesis.

METHODS

Sixty New Zealand rabbits received intrapleural injection (2mL) of talc (400mg/kg) or 0.5% silver nitrate. In each group, half of the animals received an intravenous injection of bevacizumab 30min before the sclerosing agent. Five animals from each group were euthanized 7, 14, or 28 days after the procedure. Adhesions and inflammation (scores: 0-4), thickness (μm), vascular density (vessels/field), and collagen fibers (μm(2)) were evaluated in the visceral pleura.

RESULTS

Antibody anti-VEGF interferes in pleurodesis induced by talc or silver nitrate. Pleural inflammation was discreet with no difference between the groups, regardless the anti-VEGF treatment. Concerning the vascular density of the visceral pleura, a smaller number of neoformed vessels was noted in the animals that received bevacizumab. In the animals receiving silver nitrate, the decrement in adhesions and vascular density was associated with reduced thick and thin collagen fibers, resulting in less pleural thickness.

CONCLUSION

The anti-VEGF antibody inhibits adhesions between pleural layers. Despite being an experimental study in animals with normal pleura, the results call attention to a likely lack of success in pleurodesis when VEGF blockers are used.

Comparison of side effects of oxytetracycline and talc pleurodesis: an experimental study

BACKGROUND

Chemical pleurodesis is widely recommended in the treatment of refractory pleural effusion or pulmonary air leak of different etiologies. Although several agents have been used, many questions have remained unanswered about their toxicity. Talc is the most commonly used agent for the treatment, with rare, serious complications reported. Oxytetracycline pleurodesis in clinical practice has been described in a few studies, but literature reveals no experimental studies using this agent. We performed a prospective, randomized, observer-blinded, controlled study to evaluate the changes in lung histology and systemic response to pleurodesis with oxytetracycline and talc in acute and subacute phases in a rat model.

METHODS

Forty-two male albino Wistar rats were divided into three groups and 3 subgroups with 7 animals in each. Group 1 was given oxytetracycline, 35 mg/kg; Group 2 was given talc slurry, 60 mg/kg in 0.5 mL saline solution, and Group 3 was given only 0.5 mL saline intrapleurally. In subgroups "a" the nimls were sacrificed at the postoperative 72nd hour and, in subgroups "b", on the postoperative day 7. The surfaces were graded by microscopic examination.

RESULTS

Oxytetracycline produced alveolar collapse, hemorrhage, edema, inflammation at the postoperative 72nd hour and hemorrhage on the postoperative day 7, while talc produced significant edema, inflammation, proliferation, fibrosis at the postoperative 72nd hour and hemorrhage, edema, inflammation, proliferation, and fibrosis on the postoperative day 7 (p < 0.0042). Talc produced significant edema compared to oxytetracycline on the postoperative day 7. On contralateral side, oxytetracycline and talc produced significant hemorrhage on the postoperative day 7 (p < 0.0042).

CONCLUSIONS

Both agents were shown to produce pulmonary lesions. In acute phase, the pulmonary side effects of oxytetracycline were more pronounced, whereas the side effects of talc were prolonged to subacute phase. We propose that the occasional side effects in humans may be related to these changes as were observed in our rat model, and like talc, oxytetracycline must be used cautiously in patients with limited respiratory function.

Monoclonal anti-vascular endothelial growth factor antibody reduces fluid volume in an experimental model of inflammatory pleural effusion

BACKGROUND AND OBJECTIVE

Vascular endothelial growth factor (VEGF) is known to increase vascular permeability and promote angiogenesis. It is expressed in most types of pleural effusions. However, the exact role of VEGF in the development of pleural effusions has yet to be determined. The anti-VEGF mAb, bevacizumab, has been used in the treatment of cancer to reduce local angiogenesis and tumour progression. This study describes the acute effects of VEGF blockade on the expression of inflammatory cytokines and pleural fluid accumulation.

METHODS

One hundred and twelve New Zealand rabbits received intrapleural injections of either talc or silver nitrate. In each group, half the animals received an intravenous injection of bevacizumab, 30 min before the intrapleural agent was administered. Five animals from each subgroup were sacrificed 1, 2, 3, 4 or 7 days after the procedure. Twelve rabbits were used to evaluate vascular permeability using Evans's blue dye. Pleural fluid volume and cytokines were quantified.

RESULTS

Animals pretreated with anti-VEGF antibody showed significant reductions in pleural fluid volumes after talc or silver nitrate injection. IL-8 levels, vascular permeability and macroscopic pleural adhesion scores were also reduced in the groups that received bevacizumab.

CONCLUSIONS

This study showed that bevacizumab interferes in the acute phase of pleural inflammation induced by silver nitrate or talc, reinforcing the role of VEGF as a key mediator in the production of pleural effusions. The results also suggest that bevacizumab should probably be avoided in patients requiring pleurodesis.

Talc pleurodesis: evidence of systemic inflammatory response to small size talc particles

The mechanisms of the systemic response associated with talc-induced pleurodesis are poorly understood. The aim of this study was to assess the acute inflammatory response and migration of talc of small size particles injected in the pleural space. Rabbits were injected intrapleurally with talc solution containing small or mixed particles and blood and pleural fluid samples were collected after 6, 24 or 48 h and assayed for leukocytes, neutrophils, lactate dehydrogenase, IL-8, VEGF, and TGF-beta. The lungs, spleen, liver and kidneys were assessed to study deposit of talc particles. Both types of talc produced an acute serum inflammatory response, more pronounced in the small particles group. Pleural fluid IL-8 and VEGF levels were higher in the small particle talc group. Correlation between pleural VEFG and TGF-beta levels was observed for both groups. Although talc particles were demonstrated in the organs of both groups, they were more pronounced in the small talc group. In conclusion, intrapleural injection of talc of small size particles produced a more pronounced acute systemic response and a greater deposition in organs than talc of mixed particles.

Pleural mesothelial cells mediate inflammatory and profibrotic responses in talc-induced pleurodesis

Intrapleural talc is used to produce pleurodesis in malignant pleural effusions. Prior in vivo studies have documented an acute inflammatory response to talc in the pleural space but the cellular source of cytokines has not been identified. The aim of this study was to investigate the acute response of rabbit pleural mesothelial cells challenged with talc used for pleurodesis and compare it to prior studies of the response to talc in the rabbit pleural space. Cultured rabbit pleural mesothelial cells (PMC) were exposed to talc (25 mug/cm(2)) for 6, 24, or 48 h and assessed for viability, necrosis, and apoptosis by flow cytometry, Trypan Blue exclusion, and immunocytochemistry, and for the production of interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and transforming growth factor-beta(1) (TGF-beta(1)) by ELISA. More than 50% of the PMC remained viable 48 h after talc stimulation. The PMC that were nonviable were identified as either apoptotic or necrotic, with roughly 20% in each category over the 48 h. At 6 h, the IL-8, VEGF, and TGF-beta(1) levels produced by talc-exposed PMC increased significantly and remained elevated for up to 48 h. These cytokine levels rose at similar times and at the same or higher levels than have been measured in the rabbit pleural space in prior studies. We report that viable, talc-exposed, pleural mesothelial cells may actively mediate the primary inflammatory pleural response in talc-induced pleurodesis.

Inflammation and clinical repercussions of pleurodesis induced by intrapleural talc administration

Although reports on pleurodesis date back to the beginning of the 20th century, the search for the ideal sclerosing agent is ongoing. Several agents have been studied and used, but talc continues to be the most popular. However, potentially harmful systemic side effects have been associated with talc pleurodesis. In this article we discuss the likely mechanisms of pleural inflammation and pleurodesis with emphasis on the systemic response due to the instillation of talc into the pleural space.

Pleurodesis: A novel experimental model

BACKGROUND AND OBJECTIVE

The experimental model of pleurodesis in rabbits has been useful in understanding the pathophysiology of the pleural inflammatory injury induced by several sclerosing agents. However, restrictions on the use of rabbits in laboratory investigation are making this model less accessible. The aim of this study was to present a new experimental model of pleurodesis in mice using talc or silver nitrate.

METHODS

Four groups of 10 C57BL/6 mice received talc 2 or 4 mg/g in 0.5 mL saline, or 0.025% or 0.05% silver nitrate in 0.5 mL H(2)O. After 28 days the animals were sacrificed, and the pleural cavity was opened and evaluated for evidence of macroscopic pleural adhesions and haemothorax (scores 0-4), atelectasis (scores 0-2), and microscopic pleural and alveolar inflammation and fibrosis (scores 0-4). Statistical analysis used ANOVA.

RESULTS

Silver nitrate 0.05% produced a more effective pleurodesis in mice than did 0.025% silver nitrate or talc 4 mg/g, with significant higher scores for pleural adhesions, microscopic pleural inflammation and fibrosis. Haemothorax, atelectasis, and microscopic alveolar inflammation and fibrosis were negligible in both groups.

CONCLUSIONS

Both talc 4 mg/g and 0.05% silver nitrate produced an efficient pleurodesis in this experimental model in mice. This new model may overcome the restrictions on the use of large- and medium-sized animals in laboratory investigation and may open new fields of investigation with knockout mice.

Systemic Inflammatory Reaction After Thoracoscopic Talc Poudrage

BACKGROUND

Recent studies have reported fever as a side effect of talc poudrage during thoracoscopic pleurodesis. However, thoracoscopy itself is likely to induce systemic inflammatory reaction, as it is an interventional procedure. The aim of the study was to investigate whether systemic inflammatory response is due to talc poudrage or to thoracoscopy.

METHODS

We prospectively studied two groups of patients. The first group (18 patients) underwent thoracoscopic talc poudrage, and the second group (17 patients) underwent only diagnostic thoracoscopy. We measured body temperature, as well as WBC count and C-reactive protein (CRP) levels before the procedure (baseline), and at 24 and 48 h after the procedure. No antiinflammatory medication was permitted to be used before, during, or after the procedure. All patients had a 3-month follow-up.

RESULTS

The baseline patient characteristics were similar in both groups. Temperature increased significantly in the thoracoscopic talc poudrage group (overall comparison, p = 0.005) especially at 9, 12, and 24 h after the procedure. Overall, the WBC count (p = 0.004), percentage of neutrophils (p = 0.03), and CRP levels (p < 0.0001) were significantly increased in the group of patients who underwent thoracoscopic talc poudrage. On the contrary, lymphocytes were significantly decreased (overall comparison, p = 0.01) in the thoracoscopic talc poudrage group during the same period. Mild side effects, such as pain during and after thoracoscopy and subcutaneous emphysema, were noted. No severe complication, such as infection or acute respiratory failure, was noted in either group during the hospitalization or during the follow-up period.

CONCLUSION

According to our results, fever and systemic inflammatory reaction is due to talc poudrage and not to thoracoscopy.

Influence of antiinflammatory drugs (methylprednisolone and diclofenac sodium) on experimental pleurodesis induced by silver nitrate or talc

STUDY OBJECTIVE

To determine whether the administration of antiinflammatory drugs interferes with experimental pleurodesis induced by silver nitrate or talc.

STUDY DESIGN

Two groups of 30 white New Zealand rabbits were scheduled to receive an intrapleural injection of 0.5% silver nitrate or 400 mg/kg of talc. Each group was further classified into three subgroups (10 animals each), which received the following: (subgroup 1) the sclerosing agent only, (subgroup 2) the sclerosing agent plus 1 mg/kg of methylprednisolone, and (subgroup 3) the sclerosing agent plus 1.1 mg/kg of diclofenac sodium. The antiinflammatory agents were administered IM 24 h before the sclerosing agent and daily during the first week, followed by once-weekly injections until death at 28 days. At this time, the pleural cavity was macroscopically evaluated, and samples of pleura and lungs were collected for further microscopic examination.

MEASUREMENTS AND RESULTS

The degree of pleural adhesions was higher after silver nitrate administration (p = 0.019). No reduction in the adhesions was observed after administering antiinflammatory drugs to this group (p > 0.05). Conversely, the adhesion score was significantly reduced after administration of both prednisolone (p = 0.028) and diclofenac (p = 0.032) to the animals that received talc. Administration of the antiinflammatory agents did not influence microscopic pleural or lung changes induced by silver nitrate or talc.

CONCLUSION

These results show that the sustained systemic administration of antiinflammatory agents (steroidal or nonsteroidal) reduces the degree of pleural adhesions in animals with talc-induced pleurodesis but does not affect silver nitrate-induced pleurodesis. Extrapolation of these results to humans suggests that the use of antiinflammatory drugs should be avoided in patients with talc-induced pleurodesis and that appropriate clinical studies with silver nitrate should be conducted in patients chronically treated with these antiinflammatory agents.

Alternative widely available, inexpensive agents for pleurodesis

PURPOSE OF REVIEW

Pleurodesis is the one of the best options for the management of symptomatic patients with malignant pleural effusion, recurrent benign pleural effusion, and recurrent pneumothorax. Although talc, parenteral tetracycline derivatives, and bleomycin are the most commonly used agents for pleurodesis, parenteral tetracycline derivatives are not available worldwide, bleomycin is expensive, and concerns about the side effects of talc are growing. The purpose of this review is to provide information about other widely available agents for pleurodesis.

RECENT FINDINGS

It has recently been shown that oral tetracycline/doxycycline is as effective and safe as parenteral doxycycline in producing pleurodesis in rabbits.

SUMMARY

Oral forms of tetracycline derivatives, quinacrine, silver nitrate, iodopovidone, and other talc preparations such as facial talc can be used to create pleurodesis when commonly used agents are not available.

Intrapleural Low-Dose Silver Nitrate Elicits More Pleural Inflammation and Less Systemic Inflammation Than Low-Dose Talc

STUDY OBJECTIVES

Several systemic effects have been described after talc pleurodesis. The aim of this study was to assess the systemic response induced by low, nonpleurodesis-inducing doses of talc and silver nitrate in an experimental model in rabbits.

DESIGN

Groups of six rabbits were injected intrapleurally with talc, 100 mg/kg or 400 mg/kg, and silver nitrate, 0.1% or 0.5%. After 6, 24, or 48 h, samples of blood and pleural fluid were collected and assayed for leukocytes, percentage of neutrophils, lactate dehydrogenase, interleukin-8, and vascular endothelial growth factor (VEGF) levels. Preinjection blood samples were used as normal blood controls.

MEASUREMENTS AND RESULTS

Silver nitrate 0.1% induced a more intense pleural inflammation than that produced by talc 100 mg/kg. In contrast, talc 100 mg/kg induced a more pronounced acute systemic response with higher values of WBCs and neutrophils, whereas silver nitrate 0.1% produced no significant increases in leukocytes or neutrophils. The serum interleukin-8 and VEGF levels increased in all groups, and decreased with time only in the silver nitrate 0.1% group. The highest serum VEGF levels were observed in the talc 100 mg/kg group.

CONCLUSIONS

In conclusion, 0.1% silver nitrate produced an intense pleural inflammatory response with a less evident systemic response in comparison to 0.5% silver nitrate and talc 100 mg/kg or 400 mg/kg.