Effects of intrapleural heparin or urokinase on the extent of tetracycline-induced pleural disease

IR808@MnO nano-near infrared fluorescent dye's diagnostic value for malignant pleural effusion

BACKGROUND

Malignant pleural effusion is mostly a complication of advanced malignant tumors. However, the cancer markers such as carbohydrate antigen 125 (CA 125), carbohydrate antigen 15-3 (CA 15-3), carbohydrate antigen 19-9 (CA 19-9), and cytokeratin fragment 21-1 (CYFRA 21-1) have low sensitivity and organ specificity for detecting malignant pleural effusion.

RESEARCH QUESTION

Is IR808@MnO nano-near infrared fluorescent dye worthy for the diagnosis in differentiating benign and malignant pleural effusions.

STUDY DESIGN AND METHODS

This experiment was carried out to design and characterize the materials for in vitro validation of the new dye in malignant tumor cells in the A549 cell line and in patients with adenocarcinoma pleural effusion. The dye was verified to possess tumor- specific targeting capabilities. Subsequently, a prospective hospital-based observational study was conducted, enrolling 106 patients and excluding 28 patients with unknown diagnoses. All patients underwent histopathological analysis of thoracoscopic biopsies, exfoliative cytological analysis of pleural fluid, and analysis involving the new dye. Statistical analyses were performed using Microsoft Excel, GraphPad Prism, and the R language.

RESULTS

The size of IR808@MnO was 136.8 ± 2.9 nm, with peak emission at 808 nm, and it has near-infrared fluorescence properties. Notably, there was a significant difference in fluorescence values between benign and malignant cell lines (p < 0.0001). The malignant cell lines tested comprised CL1-5, A549, MDA-MB-468, U-87MG, MKN-7, and Hela, while benign cell lines were BEAS-2B, HUVEC, HSF, and VE. The most effective duration of action was identified as 30 min at a concentration of 5 μl. This optimal duration of action and concentration were consistent in patients with lung adenocarcinoma accompanied by pleural effusion and 5 μl. Of the 106 patients examined, 28 remained undiagnosed, 39 were diagnosed with malignant pleural effusions, and the remaining 39 with benign pleural effusions. Employing the new IR808@MnO staining method, the sensitivity stood at 74.4%, specificity at 79.5%, a positive predictive value of 69.2%, and a negative predictive value of 82.1%. The area under the ROC curve was recorded as 0.762 (95% CI: 0.652-0.872). The confusion matrix revealed a positive predictive value of 75.7%, a negative predictive value of 75.6%, a false positive rate of 22.5%, and a false negative rate of 26.3%.

INTERPRETATION

The IR808@MnO fluorescent probe represents an efficient, sensitive, and user-friendly diagnostic tool for detecting malignant pleural fluid, underscoring its significant potential for clinical adoption.

Therapy of Pyothorax in Cats via Small-Bore Thoracostomy Tube in Terms of Efficacy, Complications and Outcomes

Simple Summary

With this study we present our therapeutic strategy for cats with purulent fluid accumulation in the thorax. In addition to the systemic administration of antibiotics, the aim of the therapy is always the drainage of the purulent fluid from the thorax. For this purpose, we use a particular small-bore chest drain. The first aim of our study is to assess the efficacy and complication rate of our drainage. The second objective is to evaluate two treatment groups regarding their disease outcomes. We were able to show that our small-bore chest drain is similarly effective to the traditionally used large-bore drains. At the same time, we had a very low drain-associated complication rate. We detected no difference between the treatment groups and, thus, no effect on survival by early placement of bilateral drains into the thoracic cavity or lavage of the thoracic cavity with a heparinised solution. Our study supports the theory that drainage of purulent fluid from the thoracic cavity in cats can be performed with small-bore drains with good results and minimal risk of complications.

Abstract

First-line therapy for cats with pyothorax consists of intravenous antibiotics, drainage of the septic pleural effusion and closed-chest lavage. Large-bore thoracostomy tubes are traditionally used for drainage, but case series indicate a comparable efficacy using small-bore tubes. In this retrospective study, we describe a new technique of sheath-guided small-bore (6 F) thoracostomy tubes in cats with pyothorax and evaluate their efficacy and complications. Additionally, we compare outcomes between two treatment groups. Placement and use of the small-bore thoracostomy tubes described here has a low complication rate of 4% (3/67 tubes), and 53% (24/45) of the cats could be treated with thoracostomy tubes and closed-chest lavage according to the protocol. The success rate is reduced by 18% (8/45) due to deaths caused mainly by sepsis, 16% (7/45) due to structural diseases requiring surgery and a further 14% (6/43) due to lavage failures that could only be cured after additive therapy (thoracotomy or fibrinolysis). The long-term prognosis was very good, with a survival rate one year after discharge of 94% (30/32). We detected no effect on survival by early placement of bilateral thoracostomy tubes or closed-chest lavage with a heparinised solution. In conclusion, therapy of pyothorax with small-bore thoracostomy tubes is as successful as therapy with large- or medium-bore tubes.

Exogenous intrapleural injection of interleukin-27 may improves outcome and prognosis in patients with tuberculous pleural effusion

We hypothesize that exogenous intrapleural injection of interleukin-27 may improve outcome and prognosis in patients with tuberculous pleural effusion (TPE). Studies have found that the balance of Th1/Th2 determines the development trend of TPE. High concentrations of IFN-γ and TNF-α in pleural effusion are associated with pleural adhesion in patients with TPE. Interleukin-27 is a member of the IL-12 family, and IL-27 has a dual regulatory effect on Th1 immunity. On one hand, IL-27 can promote the initial CD4+ T cell proliferation by inducing the expression of T-bet, IL-12Rβ2 and ICAM-1 in the initial CD4+ T cells, and also promote its differentiation into Th1 cells and IFN-γ production in the early infection. On the other hand, in the case of high Th1 polarization, IL-27 induced STAT3 phosphorylation and inhibited TNF and IL-12 production in activated peritoneal macrophages, indicating a novel feedback mechanism by which IL-27 can modulate excessive inflammation, thereby preventing damage to the body caused by excessive immune response. Studies haves confirmed that after stimulation of antigen by mononuclear cells in TPE, the Th1 and Th2 cell subsets and Th1/Th2 ratio markedly increase, and the increase of Th1 is more obvious than that of Th2. Therefore, compared to patients with TPE in the high-level IL-27 group, we hypothesized that pleural effusion is absorbed more slowly, pleural thickening is more obvious, pleural adhesions are more extensive, and the incidence of thoracic collapse is higher in the low-level IL-27 group under the same conditions of anti-tuberculosis treatment. However, exogenous intrapleural injection of IL-27 may induce Stat3 phosphorylation and inhibit TNF and IL-12 production, finally reduces the secretion of IFN-γ and TNF-α. This negative regulation inhibits the excessive inflammatory reaction caused by tuberculosis infection, reduces pleural adhesion, pleural thickening and local pleural tissue damage, thereby improving the prognosis of patients.

The prevalence and risk factors for serositis in patients with systemic lupus erythematosus: a cross-sectional study

This study aims to estimate the prevalence of serositis and identify risk factors for serositis in a large cohort of systemic lupus erythematosus (SLE) patients. A cross-sectional study was conducted based on the medical records of patients hospitalized with SLE at the First Affiliated Hospital of Anhui Medical University and Anhui Provincial Hospital. Patients were diagnosed with serositis when they presented with symptoms and signs of pleuritis or/and pericarditis. We explored factors associated with the generation and quantity of serositis by using binary and ordinal logistic regression analysis. Among the 1668 lupus patients, 298 have serositis. Active lupus disease, fever (≥38 °C) and high D-dimer were all significantly associated with the generation and quantity of serositis. Male gender was independent significant risk factor for pleuritis but not for pericarditis, while low complement C4 and high erythrocyte sedimentation rate (ESR) were risk factors for pericarditis rather than for pleuritis. The possible prevalence of serositis in patients with SLE was 17.9%. The significant associations of active lupus disease, fever (≥38 °C) and high D-dimer with serositis suggest that higher disease activity and hypercoagulability may both contribute to the generation and development of serositis in SLE. The risk factors for pleuritis and pericarditis in SLE are similar but not identical.

Pleural fluid osteopontin, vascular endothelial growth factor, and urokinase-type plasminogen activator levels as predictors of pleurodesis outcome and prognosticators in patients with malignant pleural effusion: a prospective cohort study

BACKGROUND

Rapidly growing cancer cells secrete growth-promoting polypeptides and have increased proteolytic activity, contributing to tumor progression and metastasis. Their presentation in malignant pleural effusion (MPE) and their predictive value for the outcome of pleurodesis and survival were studied.

METHODS

Between February 2011 and March 2012, MPE samples were prospectively collected from 61 patients. Twenty-five patients with non-malignant pleural effusion in the same period were included as controls. Pleural fluid osteopontin (OPN), vascular endothelial growth factor (VEGF), and urokinase-type plasminogen activator (uPA) concentrations were measured.

RESULTS

Patients with MPE had higher pleural fluid OPN, VEGF, and uPA concentrations than those with non-malignant pleural effusion, but only differences in VEGF were statistically significant (p = 0.045). Patients with distant metastases had significantly elevated pleural fluid VEGF concentrations than those without (p = 0.004). Pleural fluid OPN, VEGF, and uPA concentrations were positively correlated in most patients. However, there was no significant difference in pleural fluid OPN, VEGF, and uPA concentrations between patients with successful pleurodesis and those without. There was also no significant difference in cancer-specific survival between sub-groups with higher and lower pleural fluid OPN, VEGF, or uPA concentrations. Patients with successful pleurodesis had significantly longer cancer-specific survival than those without (p = 0.015).

CONCLUSIONS

Pleural fluid OPN, VEGF, and uPA concentrations are elevated in MPE but are not satisfactory predictors of pleurodesis outcome or survival. Patients with higher pleural fluid VEGF concentration have higher risk of distant metastasis. Evaluating the benefits of therapy targeting the VEGF pathway in these patients warrants further studies.

Thrombin down-regulates tissue factor pathway inhibitor expression in a PI3K/nuclear factor-κB-dependent manner in human pleural mesothelial cells

Tissue factor pathway inhibitor (TFPI) is the primary inhibitor of the extrinsic coagulation cascade, and its expression is reported to be relatively stable. Various pathophysiologic agents have been shown to influence TFPI activity by regulating its expression or by modifying the protein. It is not clear how TFPI activity is regulated in normal physiology or in injury. Because thrombin and TFPI are locally elaborated in pleural injury, we sought to determine if thrombin could regulate TFPI in human pleural mesothelial cells (HPMCs). Thrombin significantly decreased TFPI mRNA and protein levels by > 70%. Thrombin-mediated down-regulation of TFPI promoted factor X activation by HPMCs. The ability of thrombin to significantly decrease TFPI mRNA and protein levels was maintained at nanomolar concentrations. Protease-activated receptor (PAR)-1, a mediator of thrombin signaling, is detectable in the mesothelium in human and murine pleural injury. PAR-1 silencing blocked thrombin-mediated decrements of TFPI in HPMCs. Thrombin activates PI3K/Akt and nuclear factor κB (NF-κB) signaling in HPMCs. Inhibition of PI3K (by PX-866) and NF-κB (by SN50) prevented thrombin-mediated TFPI mRNA and protein down-regulation. These are the first studies to demonstrate that thrombin decreases TFPI expression in HPMCs. Our findings demonstrate a novel mechanism by which thrombin regulates TFPI expression in HPMCs and promotes an unrestricted procoagulant response, and suggest that interactions between PI3K and NF-κB signaling pathways are linked in HPMCs and control TFPI expression. These findings raise the possibility that targeting this pathway could limit the ability of the mesothelium to support extravascular fibrin deposition and organization associated with pleural injury.

Mesothelial cells in tissue repair and fibrosis

Mesothelial cells are fundamental to the maintenance of serosal integrity and homeostasis and play a critical role in normal serosal repair following injury. However, when normal repair mechanisms breakdown, mesothelial cells take on a profibrotic role, secreting inflammatory, and profibrotic mediators, differentiating and migrating into the injured tissues where they contribute to fibrogenesis. The development of new molecular and cell tracking techniques has made it possible to examine the origin of fibrotic cells within damaged tissues and to elucidate the roles they play in inflammation and fibrosis. In addition to secreting proinflammatory mediators and contributing to both coagulation and fibrinolysis, mesothelial cells undergo mesothelial-to-mesenchymal transition, a process analogous to epithelial-to-mesenchymal transition, and become fibrogenic cells. Fibrogenic mesothelial cells have now been identified in tissues where they have not previously been thought to occur, such as within the parenchyma of the fibrotic lung. These findings show a direct role for mesothelial cells in fibrogenesis and open therapeutic strategies to prevent or reverse the fibrotic process.

A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats

OBJECTIVE

To review the current literature in reference to the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats.

ETIOLOGY

Pyothorax, also known as thoracic empyema, is characterized by the accumulation of septic purulent fluid within the pleural space. While the actual route of pleural infection often remains unknown, the oral cavity and upper respiratory tract appear to be the most common source of microorganisms causing pyothorax in dogs and cats. In human medicine, pyothorax is a common clinical entity associated with bacterial pneumonia and progressive parapneumonic effusion.

DIAGNOSIS

Thoracic imaging can be used to support a diagnosis of pleural effusion, but cytologic examination or bacterial culture of pleural fluid are necessary for a definitive diagnosis of pyothorax.

THERAPY

The approach to treatment for pyothorax varies greatly in both human and veterinary medicine and remains controversial. Treatment of pyothorax has classically been divided into medical or surgical therapy and may include administration of antimicrobials, intermittent or continuous thoracic drainage, thoracic lavage, intrapleural fibrinolytic therapy, video-assisted thoracic surgery, and traditional thoracostomy. Despite all of the available options, the optimal treatment to ensure successful short- and long-term outcome, including the avoidance of recurrence, remains unknown.

PROGNOSIS

The prognosis for canine and feline pyothorax is variable but can be good with appropriate treatment. A review of the current veterinary literature revealed an overall reported survival rate of 83% in dogs and 62% in cats. As the clinical presentation of pyothorax in small animals is often delayed and nonspecific, rapid diagnosis and treatment are required to ensure successful outcome.

Proteolytic regulation of epithelial sodium channels by urokinase plasminogen activator: cutting edge and cleavage sites

Plasminogen activator inhibitor 1 (PAI-1) level is extremely elevated in the edematous fluid of acutely injured lungs and pleurae. Elevated PAI-1 specifically inactivates pulmonary urokinase-type (uPA) and tissue-type plasminogen activators (tPA). We hypothesized that plasminogen activation and fibrinolysis may alter epithelial sodium channel (ENaC) activity, a key player in clearing edematous fluid. Two-chain urokinase (tcuPA) has been found to strongly stimulate heterologous human αβγ ENaC activity in a dose- and time-dependent manner. This activity of tcuPA was completely ablated by PAI-1. Furthermore, a mutation (S195A) of the active site of the enzyme also prevented ENaC activation. By comparison, three truncation mutants of the amino-terminal fragment of tcuPA still activated ENaC. uPA enzymatic activity was positively correlated with ENaC current amplitude prior to reaching the maximal level. In sharp contrast to uPA, neither single-chain tPA nor derivatives, including two-chain tPA and tenecteplase, affected ENaC activity. Furthermore, γ but not α subunit of ENaC was proteolytically cleaved at ((177)GR↓KR(180)) by tcuPA. In summary, the underlying mechanisms of urokinase-mediated activation of ENaC include release of self-inhibition, proteolysis of γ ENaC, incremental increase in opening rate, and activation of closed (electrically "silent") channels. This study for the first time demonstrates multifaceted mechanisms for uPA-mediated up-regulation of ENaC, which form the cellular and molecular rationale for the beneficial effects of urokinase in mitigating mortal pulmonary edema and pleural effusions.

Treatment of complicated pleural effusions in 2013

The incidence of pleural infection seems to be increasing worldwide. Despite continued advances in the management of this condition, morbidity and mortality have essentially remained static over the past decade. This article summarizes the current evidence and opinions on the epidemiology, etiology, and management of complicated pleural effusions caused by infection, including empyema. Although many parallels may be drawn between children and adults in such cases, most trials, guidelines, and series regard pediatric patient groups and those more than 18 years of age as separate entities. This review focuses mainly on the treatment of adult disease.

Intrapleural adenoviral delivery of human plasminogen activator inhibitor-1 exacerbates tetracycline-induced pleural injury in rabbits

Elevated concentrations of plasminogen activator inhibitor-1 (PAI-1) are associated with pleural injury, but its effects on pleural organization remain unclear. A method of adenovirus-mediated delivery of genes of interest (expressed under a cytomegalovirus promoter) to rabbit pleura was developed and used with lacZ and human (h) PAI-1. Histology, β-galactosidase staining, Western blotting, enzymatic and immunohistochemical analyses of pleural fluids (PFs), lavages, and pleural mesothelial cells were used to evaluate the efficiency and effects of transduction. Transduction was selective and limited to the pleural mesothelial monolayer. The intrapleural expression of both genes was transient, with their peak expression at 4 to 5 days. On Day 5, hPAI-1 (40-80 and 200-400 nM of active and total hPAI-1 in lavages, respectively) caused no overt pleural injury, effusions, or fibrosis. The adenovirus-mediated delivery of hPAI-1 with subsequent tetracycline-induced pleural injury resulted in a significant exacerbation of the pleural fibrosis observed on Day 5 (P = 0.029 and P = 0.021 versus vehicle and adenoviral control samples, respectively). Intrapleural fibrinolytic therapy (IPFT) with plasminogen activators was effective in both animals overexpressing hPAI-1 and control animals with tetracycline injury alone. An increase in intrapleural active PAI-1 (from 10-15 nM in control animals to 20-40 nM in hPAI-1-overexpressing animals) resulted in the increased formation of PAI-1/plasminogen activator complexes in vivo. The decrease in intrapleural plasminogen-activating activity observed at 10 to 40 minutes after IPFT correlates linearly with the initial concentration of active PAI-1. Therefore, active PAI-1 in PFs affects the outcome of IPFT, and may be both a biomarker of pleural injury and a molecular target for its treatment.

Mechanisms of pleurodesis

Pleurodesis aims to obliterate the pleural space by producing extensive adhesion of the visceral and parietal pleura, in order to control relapse of either pleural effusions (mostly malignant) or pneumothorax. A tight and complete apposition between the two pleural layers is a necessary condition to obtain a successful pleurodesis, but--besides this mechanical aspect--there are many biological mechanisms that appear to be common to most of the sclerosing agents currently used. Following intrapleural application of the sclerosing agent, diffuse inflammation, pleural coagulation-fibrinolysis imbalance (favoring the formation of fibrin adhesions), recruitment and subsequent proliferation of fibroblasts, and collagen production are findings in the pleural space. The pleural mesothelial lining is the primary target for the sclerosant and plays a pivotal role in the whole pleurodesis process, including the release of several mediators like interleukin-8, transforming growth factor-β and basic fibroblast growth factor. When the tumor burden is high, normal mesothelial cells are scarce, and consequently the response to the sclerosing agent is decreased, leading to failure of pleurodesis. Also, the type of tumor in the pleural cavity may also affect the outcome of pleurodesis (diffuse malignant mesothelioma and metastatic lung carcinomas have a poorer response). There is general agreement that talc obtains the best results, and there are also preliminary experimental studies suggesting that it can induce apoptosis in tumor cells and inhibit angiogenesis, thus contributing to a better control of the malignant pleural effusion. There is concern about complications (possibly associated with talc but other agents as well) related to systemic inflammation and possible activation of the coagulation cascade. In order to prevent extrapleural talc dissemination, large-particle talc is recommended. Although it could--to some degree--interfere with the mechanisms leading to pleurodesis and a carefully balanced clinical decision has therefore to be made, prophylactic treatment with subcutaneous heparin is recommended during hospitalization (immediately before and after the pleurodesis procedure).

Prevention of pleural adhesions using a membrane containing polyethylene glycol in rats

BACKGROUND

Recurrent thoracotomies regardless of the cause are not a rare occurrence. However, each thoracotomy results in adhesion to some extent. This adhesions increase morbidity and mortality presents a significant inconvenience for surgeons and prolongs the length of operations.

OBJECTIVE

We investigated the efficacy of Prevadh®, an anti-adhesion agent to prevent intrapleural adesions following thoracotomy in a rat model.

METHODS

Twenty male adult Wistar Albino rats were divided into a sham group (Group A, n = 4), a control group (Group B, n = 8), and a study group (Group C, n = 8). Only left thoracotomy was performed in Group A. Group B underwent left thoracotomy, induction of adhesion, and 1 ml saline solution was administered to the thoracic cavity. However, in Group C underwent left thoracotomy, induction of adhesion, and Prevadh® was placed between the pleura and the lung. The rats were sacrificed on day 21, and adhesions were analyzed using both macroscopic and histopathological methods. The results were statistically analyzed. A value of P<0.05 was considered statistically significant.

RESULTS

Mean lengths of adhesion differed statistically significantly among all three groups, while mean intensity of adhesion differed between Group A and Group B, and between Group B and Group C (P>0.05). There was also a statistically significant difference between Group A and Group C in mesothelium proliferation score (P>0.05). No statistically significant differences were found among the groups in terms of pleural thickness, macrophage and mononuclear cell infiltration (P>0.05).

CONCLUSIONS

Prevadh® was shown in a rat model to effectively prevent post-thoracotomy adhesions.

The pathogenesis of pleural space loculation and fibrosis

PURPOSE OF REVIEW

Organization of parapneumonic effusions may complicate pneumonia, and, annually, thousands of patients require procedures to treat intrapleural loculation and fibrosis. Surgical procedures are often used for the treatment, as fibrinolytic therapy is now not a routine and is undergoing reassessment. Investigation of mechanisms that underlie intrapleural loculation and fibrosis is therefore timely, as are studies on new strategies to medically address these problems with improved efficacy and safety.

RECENT FINDINGS

Contributions made over the past year include basic and translational studies unified by their broad focus on mechanisms by which the pleural compartment undergoes repair. Intrapleural single-chain urokinase was reported to effectively reverse intrapleural loculation when compared with commercially available agents in rabbits with tetracycline-induced pleurodesis. The ability of exogenous sclerosants to produce intrapleural loculation and fibrosis was compared. Overexpression of transforming growth factor beta in the pleural mesothelium promoted subpleural fibrosis, implicating the mesothelial cell in the pathogenesis of this lesion. A new model of pleurodesis in mice was reported, which could facilitate the use of transgenic animals to study the pathogenesis of pleural injury.

SUMMARY

New findings consolidate and extend the view that common mechanisms by which intrapleural organization occurs can be exploited to either generate pleurodesis or effectively reverse intrapleural loculation and fibrosis.

Intrapleural low-molecular-weight urokinase or tissue plasminogen activator versus single-chain urokinase in tetracycline-induced pleural loculation in rabbits

The authors compared the ability of a single dose of the proenzyme single-chain urokinase (scuPA), low-molecular-weight urokinase, tissue plasminogen activator (tPA), or a mutant site-inactive scuPA to resolve intrapleural loculations at 72 to 96 hours after tetracycline-induced pleural injury in rabbits. Both scuPA and tPA reversed loculations at 96 hours after injury P < or = .001, whereas low-molecular-weight urokinase and the scuPA mutant were ineffective. scuPA and tPA generated inhibitor complexes, induced fibrinolytic activity, and quenched plasminogen activator-1 activity in pleural fluids. The authors conclude that scuPA reverses loculations as effectively as tPA at clinically applied intrapleural doses, whereas low-molecular-weight urokinase was ineffective.

Thrombin-thrombomodulin inhibits prourokinase-mediated pleural mesothelial cell-dependent fibrinolysis

Fibrin deposition is a hallmark of pleural inflammation and loculation but understanding of mechanisms by which mesothelial cells regulate intrapleural fibrinolysins remains incomplete. We speculated that pleural mesothelial cells regulate local fibrinolytic capacity via processing of single chain urokinase type plasminogen activator (scuPA). Pretreatment of human pleural mesothelial (MeT-5A) cells with TGF-beta or thrombin, either alone or in combination, inhibited urokinase (uPA)-mediated fibrinolysis by MeT-5A. Thrombin, unlike TGF-beta, inhibited fibrinolysis without induction of PAI-1, suggesting that thrombin-mediated cleavage of scuPA inhibits the fibrinolytic capacity of MeT-5A cells. Thrombin cleaves both purified scuPA as well as that secreted by MeT-5A cells and cell surface thrombomodulin accelerates thrombin-mediated cleavage of scuPA to inhibit cellular fibrinolytic activity. Molecular dynamics analyses demonstrated that thrombin-cleaved scuPA (uPAt) do not acquire a catalytically active conformation and that secondary plasminogen binding sites of uPA implicated in plasminogen activation are distorted in uPAt, explaining, at least in part, why uPAt is a poor enzyme. uPAt was detectable in transudative and exudative pleural effusions from patients. Intrapleural administration of scuPA generated increased levels of uPAt in PF of rabbits with pleural injury and loculation induced by tetracycline in vivo. This pathway is operative in diverse forms of pleural injury, restricts the urokinase-dependent fibrinolytic capacity of pleural mesothelial cells and contributes to local control of fibrinolytic activity via processing of endogenous or exogenous scuPA within the pleural compartment.

Intrapleural heparin or heparin combined with human recombinant DNase is not effective in the treatment of empyema in a rabbit model

OBJECTIVE AND BACKGROUND

The aim of this study was to investigate the effectiveness of intrapleural heparin or heparin combined with human recombinant DNase in the treatment of empyema.

METHODS

Empyema was induced in rabbits with an intrapleural injection of 10(9)Pasteurella multicoda organisms in infusion agar via a surgically placed chest tube. Once empyema was verified, a blinded investigator administered drugs via the chest tube. There were three treatment groups each with six rabbits. One group was given 1000 IU heparin, a second group was given 1000 IU heparin plus 1 mg of human recombinant DNase via chest tube and the control group received saline. The rabbits received treatment every 12 h for a total of six treatments and the volume of each treatment was 3 mL. The animals were sacrificed at day 10 and the amount of empyema and pleural thickening was scored macroscopically on a scale of 0-6.

RESULTS

The total volume of pleural effusion aspirated was significantly higher in the heparin group (25.8+/-10.7 mL) compared with either saline (8+/-8.9) or heparin plus human recombinant DNase (6.8+/-6.1) groups (P=0.003). The mean empyema and pleural thickening scores did not differ significantly between the groups (P=0.8, P=0.5 respectively). A weak correlation was found between total volume of aspirated pleural fluid and pleural parameters of white blood cell counts and LDH levels (r=0.546 and P=0.02, r=0.631 and P=0.02 respectively).

CONCLUSION

The intrapleural administration of 1000 IU heparin alone or in combination with 1 mg of human recombinant DNase is no more effective than saline in the treatment of empyema in rabbits. Intrapleural heparin significantly increased the drainage of pleural fluid compared with the combination and saline group.

Intrapleural activation, processing, efficacy, and duration of protection of single-chain urokinase in evolving tetracycline-induced pleural injury in rabbits

Intrapleural fibrinolysins have been used to treat pleural loculations. However, the efficacy of clinically available agents has recently been questioned, providing a rationale for investigation of new interventions. Single-chain urokinase plasminogen activator resists inhibition by serpins, and repeated, daily intrapleural administration of this agent prevents intrapleural loculation more effectively than complexes of this proenzyme with its receptor (Idell S, Mazar A, Cines D, Kuo A, Parry G, Gawlak S, Juarez J, Koenig K, Azghani A, Hadden W, McLarty J, Miller E. Am J Respir Crit Care Med 166: 920-926, 2002). Understanding of the protective mechanism and intrapleural processing remains unclear. We speculated that single-chain urokinase could induce sustained local fibrinolysis and protection by selective administration either before, during, or following loculation after pleural injury induced by tetracycline in rabbits. Enzymography, immunoassays, histology, immunohistochemistry, morphology, and morphometry were used to test the efficacy, duration of protective effect, and processing of single-chain urokinase. Intrapleural single chain urokinase prevented loculation at 72 h after injury (P < 0.01) if given either before or during adhesion formation and was converted to two-chain high-molecular-weight urokinase, which remained active for at least 24 h within pleural fluids. The effect was dose dependent, and established loculations at 72 h after tetracycline-induced injury were reversed at 96 h by single-dose treatment. Single-chain urokinase bound and saturated intrapleural plasminogen activator inhibitory (PAI)-1-like activity and urokinase-related immunoreactivity of the mesothelium was comparable in treatment or vehicle-control groups. Adhesions recurred by 2 wk after treatment with recurrence of excess local PAI activity. Single-chain urokinase induces sustained local fibrinolysis and reversibly prevents pleural loculation for up to 48 h after intrapleural administration after tetracycline-induced injury.

Activation and degradation of protein C by primary rabbit pleural mesothelial cells

The protein C (PC) anticoagulant pathway is the major mechanism that controls thrombin generation in vivo and may thereby influence pathophysiologic fibrin turnover associated with intrapleural inflammation. We hypothesized that pleural mesothelial cells could regulate local expression of PC in evolving pleurodesis where inflammation and thrombosis play an important role. To test this hypothesis, we determined the ability of rabbit pleural mesothelial cells (RPMC) to support the activation of PC as well as its binding, internalization, and degradation. Lung fibroblasts were also assessed to test the specificity of the responses. We found that both cell types could support thrombin-dependent activation of PC in vitro. Both cell types were capable of binding, internalizing, and degrading 125I-PC. Degradation of 125I-PC by these cells was prevented by the lysosomal inhibitor chloroquine but not the proteasomal inhibitor lactacystin, supporting involvement of a lysosomal mechanism of PC degradation. During evolving tetracycline (TCN)-induced pleural injury in rabbits, PC levels in pleural fluids were sustained, exhibited a trend toward progressive decline, and were temporally correlated with pleural adhesion formation in vivo. These observations indicate that sustained expression of PC during evolving pleurodesis induced by TCN is subject to regulation by resident pleural cells: both RPMC and lung fibroblasts. Both cell types support local generation of APC. Internalization and degradation of PC by RPMC and fibroblasts may regulate its intrapleural expression and influence remodeling of extravascular fibrin in the setting of evolving pleurodesis induced by TCN.

Polidocanol at Different Concentrations for Pleurodesis in Rats

PURPOSE

We previously found that 0.5% polidocanol was more effective than tetracycline for pleurodesis in rats. Thus, we conducted the present study to evaluate the efficacy of different concentrations of polidocanol for pleurodesis in rats.

METHODS

We divided 54 albino Wistar rats into six groups. Groups 1, 2, and 3 were given isotonic saline, 35 mg/kg tetracycline, and 0.6 mg of diluted polidocanol, respectively, being the daily recommended dose for humans. Groups 4, 5, and 6 were given 0.5%, 1%, and 2% polidocanol, respectively. All solutions were given intrapleurally in a volume of 0.5 ml. We examined the rats for macroscopic pleural adhesions and compared the mean values of macroscopic scoring among the six groups.

RESULTS

The rats given polidocanol and tetracycline had significantly more adhesions than the control group, and polidocanol at concentrations of 0.5%, 1%, and 2% was more effective for pleurodesis than tetracycline. The diluted polidocanol was not more effective than tetracycline. There was no difference between the effects of the 0.5% and 1% concentrations, but the 2% polidocanol group had significantly more adhesions than the other groups.

CONCLUSIONS

Polidocanol at concentrations of 0.5%, 1%, and 2% was a more effective sclerosing agent than tetracycline for pleurodesis. While 2% polidocanol was the most efficient sclerosing agent, the daily maximum recommended dose of polidocanol for humans was not more effective than tetracycline.

The efficacy of fibrin tissue adhesives in pleurodesis in rats

In search for a new sclerosing agent for pleurodesis, fibrin tissue adhesive is compared to tetracycline for its efficacy in rats. Twenty-four albino Wistar rats were divided into 3 groups. Groups 1, 2, and 3 were given intrapleural isotonic saline, 35 mg/kg tetracycline, and fibrin tissue adhesive with fibrinogen and thrombin concentrations of 30 mg/mL and 10 U/mL, respectively. Rats were evaluated for macroscopic pleural adhesions and mean values of macroscopic scoring were compared among the groups. Fibrin tissue adhesive- and tetracycline-treated rats had significantly more adhesions compared to the control group, whereas fibrin tissue adhesive was more effective for pleurodesis than tetracycline and no deaths or major side effects were observed in any rat. Thus, fibrin tissue adhesive was found as a more effective sclerosing agent than tetracycline for pleurodesis in rats.

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.

Management of malignant pleural effusions

Malignant pleural effusion is a common clinical problem. Evacuation of the pleural fluid and prevention of its reaccumulation are the main aims of management. Pleurodesis should be attempted early, although considerable practice variations exist in the way it is performed. There is a lack of consensus among respiratory physicians worldwide on the optimal method and agent for pleurodesis. Talc remains the most commonly used pleurodesing compound in most countries. While talc produces a higher success rate than other compounds, it generates more side-effects. The association between talc and ARDS continues to be debated. Ambulatory small-bore pleural catheter drainage followed by intrapleural instillation of a pleurodesing agent is increasingly accepted as an alternative to conventional in-patient pleurodesis. Development of novel methods to control pleural fluid formation should be made a high priority in future pleural research.

A New Radiologic Appearance of Pulmonary Thromboembolism

The objective of this study was to describe the clinical course and response to treatment of five patients who developed loculated pleural effusions as complications of pulmonary thromboembolism (PTE). The clinical charts of five patients who had loculated pleural effusions in the course of their PTE were reviewed, with special attention paid to the duration of symptoms before diagnosis, the pleural fluid analysis findings, and the response of the loculations to anticoagulant therapy. In a tertiary care academic medical center, the five patients described in the present study had multiple locules of pleural fluid seen on chest radiographs and thoracic CT scans. In all cases, the diagnosis of PTE had been delayed for at least 2 weeks after symptoms developed. The loculated pleural fluid had led to the mistaken diagnosis of empyema in three cases. The pleural fluid in all cases was exudative, with a predominance of lymphocytes. With anticoagulant therapy, the loculations largely disappeared within the first few days of therapy. Although most pleural effusions secondary to PTE are relatively small and free-flowing, this study demonstrates that PTE can lead to loculated pleural effusions. The loculations occurred in patients who had been symptomatic from their PTE for > 2 weeks. In each instance, the pleural fluid was a lymphocytic exudate. The effusions rapidly resolved with the institution of anticoagulant therapy. PTE should be included in the differential diagnosis of a loculated pleural effusion, particularly if the pleural fluid contains predominantly lymphocytes.

Reduction in fibrotic tissue formation in mice genetically deficient in plasminogen activator inhibitor-1

Mice with homozygous deletion of the plasminogen activator inhibitor-1 gene (PAI-1(-/-)) are relatively protected from bleomycin-induced pulmonary fibrosis. At least part of the protective effect appears to occur during the latter stages of the pathological process when fibrotic tissue is being deposited. To investigate the effect of PAI-1 deficiency on fibrosis, we studied the accumulation of fibrotic tissue within subcutaneously implanted polyvinyl alcohol sponges. Similar to the effect of PAI-1 deficiency on bleomycin-induced pulmonary fibrosis, the accumulation of fibrotic tissue within implanted sponges occurred more slowly in PAI-1(-/-) compared to wild-type mice. Another striking difference observed in the PAI-1(-/-) mice was the rapid removal of a fibrin-rich matrix that formed within the sponges by 1 day after implantation in both wild-type and PAI-1(-/-) mice. The pattern of connective tissue invasion also differed: cells in wild-type mice infiltrated as individually penetrating cells whereas in PAI-1(-/-) mice they did so as a well-demarcated advancing front. Providing an alternative provisional matrix by impregnating sponges with a low concentration of collagen before implantation corrected the changes induced by PAI-1 deficiency. In conclusion, PAI-1 deficiency appears to affect fibrotic tissue formation in part by altering the provisional matrix that forms soon after tissue injury.

Coagulation, fibrinolysis, and fibrin deposition in acute lung injury

OBJECTIVES

To review: a) the role of extravascular fibrin deposition in the pathogenesis of acute lung injury; b) the abnormalities in the coagulation and fibrinolysis pathways that promote fibrin deposition in the acutely injured lung; and c) the pathways that contribute to the regulation of the fibrinolytic system via the lung epithelium, including newly recognized posttranscriptional and urokinase-dependent pathways. Another objective was to determine how novel anticoagulant or fibrinolytic strategies may be used to protect against acute inflammation or accelerated fibrosis in acute lung injury.

DATA SOURCES

Published medical literature.

DATA SUMMARY

Alveolar fibrin deposition is characteristic of diverse forms of acute lung injury. Intravascular thrombosis or disseminated intravascular coagulation can also occur in the acutely injured lung. Extravascular fibrin deposition promotes lung dysfunction and the acute inflammatory response. In addition, transitional fibrin in the alveolar compartment undergoes remodeling leading to accelerated pulmonary fibrosis similar to the events associated with wound healing, or desmoplasia associated with solid neoplasms. In acute lung injury, alveolar fibrin deposition is potentiated by consistent changes in endogenous coagulation and fibrinolytic pathways. Procoagulant activity is increased in conjunction with depression of fibrinolytic activity in the alveolar compartment. Initiation of the procoagulant response occurs as a result of local overexpression of tissue factor associated with factor VII. Depression of fibrinolytic activity occurs as a result of inhibition of urokinase plasminogen activator (uPA) by plasminogen activators, or series inhibition of plasmin by antiplasmins. Locally increased amplification of plasminogen activator inhibitor-1 (PAI-1) is largely responsible for this fibrinolytic defect. Newly described pathways by which lung epithelial cells regulate expression of uPA, its receptor uPAR, and PAI-1 at the posttranscriptional level have been identified. These pathways operate by cis-trans interactions between mRNA binding proteins; regulatory sequences within these mRNAs control their stability. The regulatory mechanisms seem to involve multiple protein-mRNA interactions, and the phosphorylation state of the proteins appears to determine whether complex formation of, or dissociation from, the regulatory sequences occurs. uPA is capable of inducing its own expression in lung epithelial cells as well as that of uPAR and PAI-1-the effects involve posttranscriptional regulatory components. These and related observations have led to the implementation of anticoagulant or fibrinolytic strategies to protect the lung against acute lung injury. The success of new fibrinolytic strategies to block pleural loculation suggests that a similar approach might be used to prevent accelerated pulmonary fibrosis, which can occur in association with many forms of acute lung injury.

CONCLUSIONS

Disordered coagulation and fibrinolysis promote extravascular fibrin deposition in acute lung injury. It is this deposition that characterizes acute lung injury and repair. Expression of uPA, uPAR, and PAI-1 by the lung epithelium, as well as the ability of uPA to induce other components of the fibrinolytic system, involves posttranscriptional regulation. These pathways may contribute to disordered fibrin turnover in the injured lung. The success of anticoagulant or fibrinolytic strategies designed to reverse the abnormalities of local fibrin turnover in acute lung injury supports the inference that abnormalities of coagulation, fibrinolysis, and fibrin deposition have a critical role in the pathogenesis of acute lung injury.

Single-chain urokinase alone or complexed to its receptor in tetracycline-induced pleuritis in rabbits

Intrapleural loculation can increase morbidity in hemothoraces or parapneumonic effusions. Intrapleural fibrin precedes visceral-parietal pleural adhesions. We speculated that single-chain urokinase plasminogen activator alone or bound to its receptor could prevent these adhesions by their relative resistance to local inhibition by plasminogen activator inhibitors. We found that recombinant human single-chain urokinase-bound rabbit pleural mesothelial cells or lung fibroblasts with kinetics similar to that reported for human cells (kD of approximately 5 nM). The receptor-bound fibrinolysin maintained in vitro fibrinolytic activity in the presence of pleural fluids from rabbits with tetracycline-induced pleural injury over 24 hours. In rabbits given intrapleural single-chain urokinase 24 and 48 hours after intrapleural tetracycline (n = 10 animals), adhesions were prevented, whereas the receptor-complexed form (n = 12) attenuated adhesions versus vehicle/tetracycline-treated rabbits (n = 22, p <or= 0.005 in both cases). There were more adhesions in the complex than the single-chain urokinase group (p = 0.02). Residual antigenic but not functional evidence of the interventional agents remained in pleural fluids at 72 hours after tetracycline. No local or systemic bleeding occurred because of either interventional agent. The data demonstrate that single-chain urokinase inhibits, whereas lysin-receptor complexes attenuate, adhesion formation in tetracycline-induced pleural injury in rabbits.

Bleomycin-induced pulmonary fibrosis in fibrinogen-null mice

Mice deleted for the plasminogen activator inhibitor-1 (PAI-1) gene are relatively protected from developing pulmonary fibrosis induced by bleomycin. We hypothesized that PAI-1 deficiency reduces fibrosis by promoting plasminogen activation and accelerating the clearance of fibrin matrices that accumulate within the damaged lung. In support of this hypothesis, we found that the lungs of PAI-1(-/-) mice accumulated less fibrin after injury than wild-type mice, due in part to enhanced fibrinolytic activity. To further substantiate the importance of fibrin removal as the mechanism by which PAI-1 deficiency limited bleomycin-induced fibrosis, bleomycin was administered to mice deficient in the gene for the Aalpha-chain of fibrinogen (fib). Contrary to our expectation, fib(-/-) mice developed pulmonary fibrosis to a degree similar to fib(+/-) littermate controls, which have a plasma fibrinogen level that is 70% of that of wild-type mice. Although elimination of fibrin from the lung was not in itself protective, the beneficial effect of PAI-1 deficiency was still associated with proteolytic activity of the plasminogen activation system. In particular, inhibition of plasmin activation and/or activity by tranexamic acid reversed both the accelerated fibrin clearance and the protective effect of PAI-1 deficiency. We conclude that protection from fibrosis by PAI-1 deficiency is dependent upon increased proteolytic activity of the plasminogen activation system; however, complete removal of fibrin is not sufficient to protect the lung.

Treatment of complicated pleural effusion with intracavitary urokinase in children

Intrapleural administration of fibrinolytic agents such as urokinase (UK) has been advocated as an alternative method to manage complicated pleural effusion (CPE). Despite the increasing number of empyemas successfully treated with UK in adults, the experience in children is limited to a few cases. We report the results of image-guided catheter drainage (IGCD) with intracavitary instillation of UK in six children with CPE. Urokinase (25,000-100, 000 IU) was diluted in 20 mL of normal saline and instilled into the pleural cavity via a percutaneously placed drainage catheter. After 4 hr, the clamped catheter was released and connected to water-seal suction at a negative pressure of 20 cm H(2)O. UK instillation was repeated daily until no further drainage occurred. During IGCD, repeated radiographic and ultrasound imaging determined the location and amount of any remaining pleural fluid. Mean duration of hospital stay before initiating UK therapy was 4.3 days. Mean duration of catheter drainage before initiating UK therapy was 3.5 days, and the mean total drainage was 86 mL. All patients had an increase in chest tube drainage within 24 hr after the first instillation of UK. The mean net total drainage after UK instillation was 281 mL, most of the drainage being occurring in the first 2 days of treatment. Mean hospital stay following UK treatment was 5.8 days, and the average total duration of hospital stay was 13.8 days. No complications and no adverse events occurred during treatment with UK. Complete resolution of the consequences of the pleural effusion was observed in all patients at follow-up. Our results suggest that IGCD with adjunctive UK therapy is a reliable, simple, and safe approach to treat CPE, and it can reduce the risks associated with thoracotomy and decortication.

Intrapleural urokinase versus normal saline in the treatment of complicated parapneumonic effusions and empyema. A randomized, double-blind study

Intrapleural administration of fibrinolytic agents has been shown to be effective and safe in the treatment of loculated parapneumonic pleural effusions. However, controlled studies of the possible role of the activity of urokinase (UK) through the volume effect are lacking. We therefore investigated the hypothesis that UK is effective through the lysis of pleural adhesions and not through the volume effect. Thirty-one consecutive patients with multiloculated pleural effusions were randomly assigned to receive either intrapleural UK (15 patients) or normal saline (NS) (16 patients) for 3 d, in a double-blind manner. All patients had inadequate drainage through a chest tube (< 70 ml/24 h). UK was given daily through the chest tube in a dose of 100.000 IU diluted in 100 ml of NS. Controls were given the same volume of NS intrapleurally. Response was assessed by clinical outcome, fluid drainage, chest radiography, pleural ultrasonography (US) and/or computed tomography (CT). Clinical and radiographic improvement was noted in all but two patients in the UK group but in only four in the control group. The net mean volume drained during the 3-d treatment period was significantly greater in the UK group (970 +/- 75 ml versus 280 +/- 55 ml, p < 0.001). Pleural fluid drainage was complete in 13 (86.5%) patients in the UK group (two patients were treated through video-assisted thoracoscopy) but in only four (25%) in the control group. Twelve patients in the control group were subsequently treated with UK and six of them had complete drainage; the remaining six patients had complete drainage after video-assisted thoracoscopy. Our results suggest that UK is effective in the treatment of loculated pleural effusions through the lysis of pleural adhesions and not through the volume effect.

Doxycycline pleurodesis in rabbits: comparison of results with and without chest tube

We have reported previously that there is a high incidence of hemothorax and substantial mortality in rabbits that are given tetracycline derivatives intrapleurally. However, such complications have not been reported in humans when pleurodesis is attempted with tetracycline derivatives. One primary difference in the two situations is that a chest tube is placed only in humans. The objective of this study was to evaluate the hypothesis that chest tube placement would prevent the development of hemothoraces and lead to better pleurodesis in rabbits given doxycycline intrapleurally. Eighty New Zealand White male rabbits received doxycycline, 20 mg/kg, in a total volume of 2 mL. One half of the rabbits were randomized to receive a chest tube at the time of the injection and were subjected to pleural fluid aspiration twice daily. The remaining rabbits (control group) received no chest tube and no aspiration. Ten rabbits from each group were killed on days 4, 7, 14, and 28. The intrapleural injection of doxycycline induced the production of large exudative effusions. The insertion of chest tubes prevented the development of hemothorax (0/20 in chest tube group, 15/20 in control group, p<0.001). The insertion of chest tubes was also associated with a significant reduction in mortality and a significant improvement in pleurodesis. When pleurodesis is attempted in rabbits with intrapleural doxycycline, the insertion of a chest tube will prevent hemothorax and lead to a better pleurodesis.

Randomised controlled trial of intrapleural streptokinase in community acquired pleural infection

BACKGROUND

Standard treatment for pleural infection includes catheter drainage and antibiotics. Tube drainage often fails if the fluid is loculated by fibrinous adhesions when surgical drainage is needed. Streptokinase may aid the process of pleural drainage, but there have been no controlled trials to assess its efficacy.

METHODS

Twenty four patients with infected community acquired parapneumonic effusions were studied. All had either frankly purulent/culture or Gram stain positive pleural fluid (13 cases; 54%) or fluid which fulfilled the biochemical criteria for pleural infection. Fluid was drained with a 14F catheter. The antibiotics used were cefuroxime and metronidazole or were guided by culture. Subjects were randomly assigned to receive intrapleural streptokinase, 250,000 i.u. daily, or control saline flushes for three days. The primary end points related to the efficacy of pleural drainage--namely, the volume of pleural fluid drained and the chest radiographic response to treatment. Other end points were the number of pleural procedures needed and blood indices of inflammation.

RESULTS

The streptokinase group drained more pleural fluid both during the days of streptokinase/control treatment (mean (SD) 391 (200) ml versus 124 (44) ml; difference 267 ml, 95% confidence interval (CI) 144 to 390; p < .001) and overall (2564 (1663) ml, 95% CI 465 to 2545; p < 0.01). They showed greater improvement on the chest radiograph at discharge, measured as the fall in the maximum dimension of the pleural collection (6.0 (2.7) cm versus 3.4 (2.7) cm; difference 2.9 cm, 95% CI 0.3 to 4.4; p < 0.05) and the overall reduction in pleural fluid collection size (p < 0.05, two-tailed Fisher's exact test). Systemic fibrinolysis and bleeding complications did not occur. Surgery was required by three control patients but none in the streptokinase group.

CONCLUSIONS

Intrapleural streptokinase probably aids the treatment of pleural infections by improving pleural drainage without causing systemic fibrinolysis or local haemorrhage.

Controlled trial of intrapleural streptokinase in the treatment of pleural empyema and complicated parapneumonic effusions

OBJECTIVE

To compare the efficacy of adjunctive intrapleural streptokinase (SK) with simple closed chest tube drainage (Drain) in the treatment of empyemas and complicated parapneumonic effusions.

METHOD

This was a controlled study of 52 patients (mean age, 57 years; 41 men) with pleura space sepsis. Forty patients (77%) had empyema and 12 had complicated parapneumonic effusions. Twenty-nine patients were treated with Drain only while 23 received, in addition, repeated daily SK, 250,000 U in saline solution (mean, 5.3 days).

RESULTS

The two groups of patients had comparable degrees of peripheral blood leukocytosis, frequency of loculated effusions, pleural fluid pH, and lactate dehydrogenase levels. Infective organisms were isolated in 54% of which 32% were anaerobic and 21% were polymicrobial infections. The incidence of surgical decortication was 17% and mortality was 15%. A significantly larger volume of pleural fluid was drained from patients in the SK treatment group (2.0 [1.5] L) than those in the Drain treatment group (1.0 [1.01] L). There were no significant differences, however, between the two treatment groups in terms of duration before defervescence, duration of hospital stay, the need for surgical intervention, or mortality rates.

CONCLUSION

We conclude that thrombolytic therapy increased the volume of fluid drained from pleural empyemas but did not markedly reduce morbidity and mortality.

Pleural macrophages differentially alter pleural mesothelial cell glycosaminoglycan production

Glycosaminoglycans are produced in abundance by the pleural mesothelium and likely participate in the inflammatory response to pleural injury. Because intrapleural tetracycline (TCN) results in pleural macrophage influx and pleural fibrosis, this study attempted to define the role of pleural macrophage products on mesothelial glycosaminoglycan (GAG) production. Pleural macrophages were isolated 72 h after intrapleural TCN or intrapleural carrageenan (CAR), a substance that recruits pleural macrophages without producing pleural fibrosis. Macrophage cultured for 24 h produced a conditioned medium that was added to pleural mesothelial cell culture containing [3H]-glucosamine and was compared to control cultures treated with RPMI culture media alone or with the addition of TCN or CAR. After 72 h, GAGs were isolated by pronase digestion, cetyl pyridinium precipitation, and MgCl2 and ethanol extraction. The majority of GAGs were found in the culture media as compared to the combined mesothelial cell and basement membrane fractions of control mesothelial cells (883 +/- 33 vs. 216 +/- 16, cpm, counts per minute), TCN-treated (792 +/- 48 vs. 204 +/- 18 cpm), CAR-treated (849 +/- 45 vs. 223 +/- 13 cpm), and macrophage-conditioned media-treated mesothelial cells (TCN macrophage-conditioned media: 1420 +/- 42 vs. 356 +/- 11 cpm; CAR macrophage-conditioned media: 1241 +/- 38 vs. 339 +/- 10 cpm) (all p < .05). Media samples were enzymatically digested and individual GAG species were separated by Sephadex G-50 column chromatography. TCN macrophage-conditioned media induced more GAG production by the mesothelial cell into the cell media (1420 +/- 42 cpm) than CAR macrophage-conditioned media (1241 +/- 38 cpm) (p < .05), which was predominantly a difference in hyaluronate production (342 +/- 53 cpm vs. 186 +/- 7 cpm) (P. < .05). The results show that pleural macrophages modulate mesothelial GAG production during tetracycline pleural injury. Increases in mesothelial cell hyaluronate production may be important in the fibrotic response to chemical pleural injury.

Regulation of mesothelial cell mitogenesis by antisense oligonucleotides for the urokinase receptor

The association of urokinase-type plasminogen activator (uPA) with its receptor (uPAR) influences various biologic functions, including cell migration, angiogenesis, differentiation, and wound healing. Expression of uPAR at the mesothelial surface could, therefore, influence cellular responses in the pleural space. We found that a line of cultured human mesothelial cells (MeT5A) expressed specific and saturable binding sites for uPA that increased on stimulation with PMA. Ligand blotting studies showed that the mesothelial receptor is a 50 kD protein similar to that in other cell lines. Binding of active and intact, but not amino terminal or low molecular weight fragment, uPA to mesothelial cells enhanced DNA synthesis and cell proliferation, and antibodies against either the active site of uPA or uPAR abrogated this effect. We reasoned that regulation of uPAR expression could control uPA-induced mitogenesis and tested this hypothesis with antisense oligonucleotides complementary to uPAR mRNA. Phosphorothioate-modified antisense oligonucleotides inhibited uPA-mediated mesothelial cell proliferation in a concentration-dependent manner. These effects were associated with decreased binding of 125I-uPA and reduced expression of the uPAR gene product. The results indicate that uPAR is involved in signal transduction pathways that control uPA-mediated mesothelial cell proliferation, a process implicated in the pathogenesis of mesothelial inflammation and pleural neoplasia. Antisense oligonucleotides to uPAR suppress mesothelial cell mitogenesis in vitro and offer a potential means of regulating the process in vivo.