Olufemi Akindipe

Pleural mesothelial cell transformation into myofibroblasts and haptotactic migration in response to TGF-β1 in vitro

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology characterized by the development of subpleural foci of myofibroblasts that contribute to the exuberant fibrosis noted in the pulmonary parenchyma. Pleural mesothelial cells (PMC) are metabolically dynamic cells that cover the lung and chest wall as a monolayer and are in intimate proximity to the underlying lung parenchyma. The precise role of PMC in the pathogenesis of pulmonary parenchymal fibrosis remains to be identified. Transforming growth factor (TGF)-beta1, a cytokine known for its capacity to induce proliferative and transformative changes in lung cells, is found in significantly higher quantities in the lungs of patients with IPF. High levels of TGF-beta1 in the subpleural milieu may play a key role in the transition of normal PMC to myofibroblasts. Here we demonstrate that PMC activated by TGF-beta1 undergo epithelial-mesenchymal transition (EMT) and respond with haptotactic migration to a gradient of TGF-beta1 and that the transition of PMC to myofibroblasts is dependent on smad-2 signaling. The EMT of PMC was marked by upregulation of alpha-smooth muscle actin (alpha-SMA), fibroblast specific protein-1 (FSP-1), and collagen type I expression. Cytokeratin-8 and E-cadherin expression decreased whereas vimentin remained unchanged over time in transforming PMC. Knockdown of smad-2 gene by silencing small interfering RNA significantly suppressed the transition of PMC to myofibroblasts and significantly inhibited the PMC haptotaxis. We conclude that PMC undergo EMT when exposed to TGF-beta1, involving smad-2 signaling, and PMC may be a possible source of myofibroblasts in IPF.

Parenchymal trafficking of pleural mesothelial cells in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterised by myofibroblast proliferation leading to architectural destruction. Neither the origin nor the continued proliferation of myofibroblasts is well understood. Explanted human IPF lungs were stained by immunohistochemistry for calretinin, a marker of pleural mesothelial cells (PMCs). Chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) lungs acted as controls. The number of PMCs per 100 nucleated cells and per photomicrograph was estimated along with the Ashcroft score of fibrosis. Mouse PMCs expressing green fluorescent protein (GFP) or labelled with nanoparticles were injected into the pleural space of mice given intranasal transforming growth factor (TGF)-&bgr;1. Mouse lungs were lavaged and examined for the presence of GFP, smooth muscle &agr;-actin (&agr;-SMA) and calretinin. Calretinin-positive PMCs were found throughout IPF lungs, but not in COPD or CF lungs. The number of PMCs correlated with the Ashcroft score. In mice, nanoparticle-laden PMCs were recoverable by bronchoalveolar lavage, depending on the TGF-&bgr;1 dose. Fluorescent staining showed &agr;-SMA expression in GFP-expressing PMCs, with co-localisation of GFP and &agr;-SMA. PMCs can traffic through the lung and show myofibroblast phenotypic markers. PMCs are present in IPF lungs, and their number correlates with IPF severity. Since IPF presumably begins subpleurally, PMCs could play a pathogenetic role via mesothelial–mesenchymal transition.

Prevalence of pulmonary hypertension in end-stage cystic fibrosis and correlation with survival

BACKGROUNDnLimited information is available about the prevalence of pulmonary hypertension diagnosed by right heart catheterization (RHC) in patients with cystic fibrosis being evaluated for lung transplantation. It is unclear whether there are factors that can predict the presence of pulmonary hypertension and whether the presence of pulmonary hypertension influences patient outcomes.nnnMETHODSnThe study included 57 unique and consecutive adult patients (33 women) with cystic fibrosis who underwent lung transplant evaluation at the University of Florida.nnnRESULTSnThe average age at evaluation was 31.8 +/- 10 years. All patients were in New York Heart Association class III. The median (interquartile range) of mean pulmonary artery pressure (PAP) was 26 (24-30) mm Hg. Thirty-six patients (63.2%) had pulmonary hypertension (mean PAP >or= 25 mm Hg) and had a significantly higher degree of hypoxemia and oxygen requirements. Echocardiography evidenced limitations for the diagnosis of pulmonary hypertension. The 5-year mortality rate was similar in patients with or without pulmonary hypertension; however, it was higher in 7 patients identified by cluster analysis and in patients with a left ventricular ejection fraction < 55%.nnnCONCLUSIONSnMore than half of our patients with cystic fibrosis and advanced lung disease have elevation of PAP, usually of mild degree. A lower left ventricular ejection fraction, but not the presence of pulmonary hypertension, was associated with worse outcomes.

Clinical Experience With a New Removable Tracheobronchial Stent in the Management of Airway Complications After Lung Transplantation

BACKGROUNDnAirway complications are among the most challenging problems after lung transplantation. This article describes the use of a new tracheobronchial stent that can be placed and removed easily by flexible bronchoscopy.nnnMETHODSnA retrospective review was done of 24 consecutive patients requiring tracheobronchial stent placement after lung transplantation. A new self-expanding hybrid nitinol stent was used, and changes in airway diameter and spirometry were assessed. Stent related complications were recorded.nnnRESULTSnBetween February 2007 and April 2008, 24 patients underwent stent placement, and 49 stents were placed for 36 anastomoses at risk. Indications included bronchial stenosis in 12, bronchomalacia in 12, bronchial stenosis plus bronchomalacia in 20, and partial bronchial dehiscence in 5. Adjunctive procedures included electrocautery in 1, balloon dilatation in 7, and electrocautery plus balloon dilatation in 4. The average degree of stenosis decreased from 80% to 20%. After stent placement, the average increase was 0.28 liters in forced vital capacity and 0.44 liters in forced expiratory volume in 1 second. Complications included granulation tissue formation in 10 stents, migration in 9, thick mucus formation in 2, and fracture in 3.nnnCONCLUSIONnAirway complications in lung transplant patients were effectively palliated. Our complication rate with this new stent is comparable with other airway stents. This stent has the advantage of easy removability during flexible bronchoscopy if complications from the stent outweigh the benefits of palliation.

Quantification of cytotoxic T-cell gene transcripts in human lung transplantation.

BACKGROUNDnDifferentiating between acute rejection and cytomegalovirus (CMV) infection is one of the major challenges of lung transplantation. The aims of this study were to: (1) quantify the transcription of the cytotoxic T lymphocyte (CTL) effector molecules in the bronchoalveolar lavage (BAL) of lung transplant recipients and (2) evaluate the clinical usefulness of this technique.nnnMETHODSnSixty-six single-lung, double-lung, or heart-lung transplant patients were prospectively enrolled in the study. BAL was performed either for routine surveillance or for acute graft dysfunction. RNA was extracted from BAL cell pellets and underwent competitive reverse transcription-assisted polymerase chain reaction (RT-PCR) for perforin, granzyme B, granulysin, and Fas ligand. Gene transcript analysis was compared to clinical diagnosis established by conventional methods [BAL microbiological and transbronchial biopsy (TBB) analyses].nnnRESULTSnAfter exclusion of several BAL according to the study criteria, 62 BAL were submitted for data analysis. Significantly higher expression of all the analyzed transcripts was found during CMV infection, compared with each of the other defined diagnostic categories, namely nonsignificant pathology, acute rejection, and nonviral pulmonary infection.nnnCONCLUSIONnQuantification by competitive RT-PCR of the CTL effector molecule transcripts (perforin, granzyme B, granulysin, and Fas ligand) could represent a valuable tool for the differential diagnosis of graft dysfunction in lung transplantation.

Tratamiento de complicaciones en la vía aérea postrasplante pulmonar

OBJECTIVEnTo describe our experience in airway complications following lung transplant and to suggest a management algorithm, using different tools from the Interventional Pulmonology armamentarium.nnnMETHODnRetrospective chart review of all airway complications following lung transplant from January 1999 to July 2007.nnnRESULTSnDuring that period 223 patients underwent lung transplantation, with a total of 345 anastomoses in the airway. Seventy anastomoses (20.23%) had complications requiring endoscopic treatment. The total number of endoscopic interventions were 631 in 52 patients. Thirty three patients had a combination of bronchial stenosis and bronchomalacia. Eighteen patients had bronchial stenosis only and 1 patient had dehiscence of the anastomosis. Balloon dilation was most commonly transiently effective and ultimately 47 patients required stent placement. The most common complication associated with the use of stent was granulation tissue formation, seen in 57.3% of patients. After stent placement, the forced expiratory volume in 1(st) second (FEV(1)) improved significantly.nnnCONCLUSIONnAirway complications after lung transplant are frequent. Balloon dilation was effective only in a few patients with bronchial stenosis, although the majority ultimately needed a stent. Airway repermeabilization after stent placement improved FEV(1). Based on our experience, we propose a management algorithm for airway complications after lung transplant.

Treatment of Airway Complications Following Lung Transplantation

Abstract Objective To describe our experience in airway complications following lung transplantation and to suggest a management strategy using different interventional bronchoscopic techniques. Method Retrospective analysis of all airway complications following lung transplantation from January 1999 to July 2007. Results During this period, 223 patients underwent lung transplantation, with a total of 345 airway anastomoses. In 70 (20.23%), there were complications requiring endoscopic intervention. A total of 631 procedures were carried out in 52 patients. Thirty-three patients presented a combination of bronchial stenosis and bronchomalacia, 18 patients had bronchial stenosis alone and 1 patient presented dehiscence of the anastomosis. In most cases, pneumatic balloon dilatation was effective, although temporarily, and ultimately 47 patients required endobronchial stent placement. The most common complication associated with the use of stents was granulation tissue formation, seen in 57.3% of patients. After stent placement, forced expiratory volume in one second (FEV 1 ) improved significantly. Conclusion Airway complications after lung transplantation are frequent. Balloon dilatation was effective in only a few patients with bronchial stenosis, requiring stent placement in most. Airway permeabilization after endobronchial stent placement improved FEV 1 in these patients. Based on our experience, we propose a management strategy for airway complications after lung transplantation.

Heart-lung versus double-lung transplantation for suppurative lung disease.

OBJECTIVEnThe purpose of this study was to compare outcomes after heart-lung or double-lung transplantation in patients undergoing transplantation because of end-stage suppurative lung disease.nnnMETHODSnWe reviewed our experience in patients with cystic fibrosis or bronchiectasis who had heart-lung or double-lung transplantation between January 1988 and September 1997. Twenty-three patients (14 male, 21 cystic fibrosis) had heart-lung transplantation and 24 patients (8 male, 19 cystic fibrosis) had double-lung transplantation. There were no statistically significant differences between the groups in age, weight, preoperative creatinine level, cytomegalovirus status, maintenance immunosuppression, or donor demographics. Patients received induction therapy with monoclonal (OKT3) or polyclonal (rabbit anti-thymocyte globulin) antibody.nnnRESULTSnSixteen of 24 patients had double-lung transplantation after 1994 whereas 13 of 22 patients had heart-lung transplantation before 1991, allowing longer follow-up for the heart-lung group. Mean waiting times for transplantation were 270 +/- 245 days (heart-lung) and 361 +/- 229 days (double-lung; P =.20). The 1-, 3-, and 5-year actuarial survival figures were respectively 86%, 82%, and 65% (heart-lung) and 96%, 75%, and unavailable (double-lung; P = no significant difference). The 1-, 3-, and 5-year rates of freedom from obliterative bronchiolitis were respectively 77%, 61%, and 45% (heart-lung) and 86%, 78%, and unavailable (double-lung; P = no significant difference). Linearized overall infection rates (events/100 patient-days) were 2.05 +/- 0.33 (heart-lung) and 2.34 +/- 0.34 (double-lung; P = NS) at 3 months. Thirty-day survival was 100% (heart-lung) and 96% (double-lung). There were 7 late deaths among heart-lung recipients (3 obliterative bronchiolitis, 2 infection, 0 graft coronary artery disease, 2 other) whereas 2 late deaths related to obliterative bronchiolitis occurred in double-lung recipients. Graft coronary artery disease (all stenoses < 50%) affected 15% of heart-lung survivors, whereas 3 double-lung recipients (12.5%) required either bronchial dilatation or stenting.nnnCONCLUSIONnHeart-lung and double-lung transplantation provide similar palliation for patients with end-stage suppurative lung disease. Therefore double-lung transplantation should be the preferred operation for most patients with end-stage suppurative lung disease.

Recurrent pneumocystis carinii colonization in a heart-lung transplant recipient on long-term trimethoprim-sulfamethoxazole prophylaxis

INTRODUCTIONnIn the setting of organ transplantation, prior to prophylaxis, Pneumocystis carinii pneumonia (PCP) had been a common clinical problem, particularly in heart-lung and lung recipients who receive long-term immunosuppressive therapy to prevent allograft rejection. Continuous oral trimethoprim-sulfamethoxazole (TMP-SMX) has been highly effective in preventing PCP in these patients.nnnREPORTnIn this paper we report a case of recurrent Pneumocystis carinii infection in a chronic (> 15 years) heart-lung allograft recipient on long-term TMP-SMX prophylaxis. Twice, in 1995 and again in 1998, Pneumocystis carinii infection was diagnosed by bronchoalveolar lavage (BAL), in the same patient, despite continued oral TMP-SMX (960 mg TMP/4800 mg SMX per week) prophylaxis. The subject was not lymphopenic (his CD4 count was 569/mm3) and there was no associated deterioration in pulmonary function, nor evidence of hypoxemia.nnnCONCLUSIONnThis case demonstrates that asymptomatic Pneumocystis carinii lung infections may recur in chronic heart-lung transplant recipients who take standard oral PCP prophylaxis.

Invasive Fungal Infections in Lung Transplant Recipients Not Receiving Routine Systemic Antifungal Prophylaxis: 12‐Year Experience at a University Lung Transplant Center

Study Objective. To determine the rate of invasive fungal infection among the lung transplant population at a center that does not provide routine systemic antifungal prophylaxis, and to compare that rate with rates currently reported in the literature.