David A. Zisman

A controlled trial of sildenafil in advanced idiopathic pulmonary fibrosis.

BACKGROUND Sildenafil, a phosphodiesterase-5 inhibitor, may preferentially improve blood flow to well-ventilated regions of the lung in patients with advanced idiopathic pulmonary fibrosis, which could result in improvements in gas exchange. We tested the hypothesis that treatment with sildenafil would improve walk distance, dyspnea, and quality of life in patients with advanced idiopathic pulmonary fibrosis, defined as a carbon monoxide diffusion capacity of less than 35% of the predicted value. METHODS We conducted a double-blind, randomized, placebo-controlled trial of sildenafil in two periods. The first period consisted of 12 weeks of a double-blind comparison between sildenafil and a placebo control. The primary outcome was the proportion of patients with an increase in the 6-minute walk distance of 20% or more. Key secondary outcomes included changes in oxygenation, degree of dyspnea, and quality of life. The second period was a 12-week open-label evaluation involving all patients receiving sildenafil. RESULTS A total of 180 patients were enrolled in the study. The difference in the primary outcome was not significant, with 9 of 89 patients (10%) in the sildenafil group and 6 of 91 (7%) in the placebo group having an improvement of 20% or more in the 6-minute walk distance (P=0.39). There were small but significant differences in arterial oxygenation, carbon monoxide diffusion capacity, degree of dyspnea, and quality of life favoring the sildenafil group. Serious adverse events were similar in the two study groups. CONCLUSIONS This study did not show a benefit for sildenafil for the primary outcome. The presence of some positive secondary outcomes creates clinical equipoise for further research. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00517933.)

MCP-1 protects mice in lethal endotoxemia.

The overzealous production of proinflammatory cytokines in sepsis can result in shock, multiorgan dysfunction, and even death. In this study, we assessed the role of monocyte chemoattractant protein-1 (MCP-1) as a mediator of sepsis in endotoxin-challenged mice. Intraperitoneal administration of LPS to CD-1 mice induced a substantial time-dependent increase in MCP-1 in plasma, lung, and liver. The passive immunization of mice with rabbit antimurine MCP-1 antiserum 2 h before endotoxin administration resulted in a striking increase in LPS-induced mortality from 10% in control animals to 65% in anti-MCP-1-treated animals. Importantly, the administration of anti-MCP-1 antibodies to endotoxin-challenged mice resulted in increases in peak TNF-alpha and IL-12 levels, and also in a trend toward decreased serum levels of IL-10. Conversely, the administration of recombinant murine MCP-1 intraperitoneally significantly protected mice from endotoxin-induced lethality, and resulted in an increase in IL-10 levels, a decrease in IL-12 levels, and a trend toward decreased levels of TNF. In conclusion, our findings indicate that MCP-1 is a protective cytokine expressed in murine endotoxemia, and does so by shifting the balance in favor of antiinflammatory cytokine expression in endotoxin-challenged animals.

Idiopathic pulmonary fibrosis - Pathogenesis and therapeutic approaches

Idiopathic pulmonary fibrosis (IPF), also termed cryptogenic fibrosing alveolitis, is a clinicopathological syndrome characterised by cough, exertional dyspneoa, basilar crackles, a restrictive defect on pulmonary function tests, honeycombing on high-resolution, thin-section computed tomographic scans and the histological diagnosis of usual interstitial pneumonia on lung biopsy. The course is usually indolent but inexorable. Most patients die of progressive respiratory failure within 3–8 years of the onset of symptoms. Current therapies are of unproven benefit. Although the pathogenesis of IPF has not been elucidated, early concepts focused on lung injury leading to a cycle of chronic alveolar inflammation eventuating in fibrosis and destruction of the lung architecture. Anti-inflammatory therapies employing corticosteroids or immunosuppressive or cytotoxic agents have been disappointing. More recent hypotheses acknowledge that sequential alveolar epithelial cell injury is likely to be a key event in the pathogenesis of IPF, but the cardinal event is an aberrant host response to wound healing. In this context, abnormal epithelial-mesenchymal interactions, altered fibroblast phenotypes, exaggerated fibroblast proliferation, and excessive deposition of collagen and extracellular matrix are pivotal to the fibrotic process.Several clinical trials are currently underway or in the planning stages, and include drugs such as interferon-γ 1b, pirfenidone, acetylcysteine, etanercept (a tumor necrosis factor-α antagonist), bosentan (an endothelin-1 receptor antagonist) and zileuton (a 5-lypoxygenase inhibitor). Future therapeutic strategies should be focused on alveolar epithelial cells aimed at enhancing re-epithelialisation and on fibroblastic/myofibroblastic foci, which play an essential role in the development of IPF. Stem cell progenitors of the alveolar epithelial cells and genetic and epigenetic therapies are attractive future approaches for this and other fibrotic lung disorders.

Aspergillus Colonization of the Lung Allograft Is a Risk Factor for Bronchiolitis Obliterans Syndrome

Multiple infections have been linked with the development of bronchiolitis obliterans syndrome (BOS) post‐lung transplantation. Lung allograft airway colonization by Aspergillus species is common among lung transplant recipients. We hypothesized that Aspergillus colonization may promote the development of BOS and may decrease survival post‐lung transplantation. We reviewed all lung transplant recipients transplanted in our center between January 2000 and June 2006. Bronchoscopy was performed according to a surveillance protocol and when clinically indicated. Aspergillus colonization was defined as a positive culture from bronchoalveolar lavage or two sputum cultures positive for the same Aspergillus species, in the absence of invasive pulmonary Aspergillosis. We found that Aspergillus colonization was strongly associated with BOS and BOS related mortality in Cox regression analyses. Aspergillus colonization typically preceded the development of BOS by a median of 261 days (95% CI 87–520). Furthermore, in a multivariate Cox regression model, Aspergillus colonization was a distinct risk factor for BOS, independent of acute rejection. These data suggest a potential causative role for Aspergillus colonization in the development of BOS post‐lung transplantation and raise the possibility that strategies aimed to prevent Aspergillus colonization may help delay or reduce the incidence of BOS.

Role of CXCL9/CXCR3 Chemokine Biology during Pathogenesis of Acute Lung Allograft Rejection

Acute allograft rejection is a major complication postlung transplantation and is the main risk factor for the development of bronchiolitis obliterans syndrome. Acute rejection is characterized by intragraft infiltration of activated mononuclear cells. The ELR-negative CXC chemokines CXCL9, CXCL10, and CXCL11) are potent chemoattractants for mononuclear cells and act through their shared receptor, CXCR3. Elevated levels of these chemokines in bronchoalveolar lavage fluid have been associated with human acute lung allograft rejection. This led to the hypothesis that the expression of these chemokines during an allogeneic response promotes the recruitment of mononuclear cells, leading to acute lung allograft rejection. We performed studies in a rat orthotopic lung transplantation model of acute rejection, and demonstrated increased expression of CXCL9 and CXCL10 paralleling the recruitment of mononuclear cells and cells expressing CXCR3 to the allograft. However, CXCL9 levels were 15-fold greater than CXCL10 during maximal rejection. Inhibition of CXCL9 decreased intragraft recruitment of mononuclear cells and cellular expression of CXCR3, resulting in lower acute lung allograft rejection scores. Furthermore, the combination of low dose cyclosporin A with anti-CXCL9 therapy had more profound effects on intragraft leukocyte infiltration and in reducing acute allograft rejection scores. This supports the notion that CXCL9 interaction with cells expressing CXCR3 has an important role in the recruitment of mononuclear cells, a pivotal event in the pathogenesis of acute lung allograft rejection.

Anti-interleukin-12 therapy protects mice in lethal endotoxemia but impairs bacterial clearance in murine Escherichia coli peritoneal sepsis

The overzealous production of proinflammatory cytokines in sepsis can result in shock, multiorgan dysfunction, and even death. In this study we assessed the role of endogenously produced interleukin (IL)-12 in murine models of endotoxemia and Gram-negative peritoneal sepsis. Initial studies indicated that intraperitoneal lipopolysaccharide (LPS) administration to mice induced a significant time-dependent increase in plasma, lung, and liver IL-12 levels. Passive immunization with anti-IL-12 serum intraperitoneally before LPS resulted in a marked reduction in plasma levels of tumor necrosis factor and interferon-γ. Furthermore, we observed an increase in endotoxin-induced mortality in mice transiently overexpressing murine IL-12 using a recombinant adenoviral vector (Ad5 mIL-12) administered intraperitoneally. Neutralization of tumor necrosis factor or interferon-γ in animals overexpressing IL-12 resulted in significant reductions in LPS-induced mortality, suggesting that the mechanism whereby IL-12 increases LPS-induced mortality is primarily mediated by the enhancement of these cytokines. In contrast, we observed no survival benefit in animals passively immunized with anti-IL-12 serum before the intraperitoneal administration of 2 x 108 live Escherichia coli. Interestingly, there was an approximately 70-fold increase in peritoneal fluid E. coli colony-forming units and the early onset of bacteremia in animals treated with anti-IL-12 serum, as compared with control animals. These results indicate that IL-12 is produced in response to LPS exposure, and the neutralization of this cytokine improves survival in endotoxin-challenged animals. However, IL-12 represents an essential component of antibacterial host defense, as anti-IL-12 therapy results in significant impairment in the hosts ability to clear Gram-negative bacterial infection.

IL-13 Is Pivotal in the Fibro-Obliterative Process of Bronchiolitis Obliterans Syndrome

Acute allograft rejection is considered to be a predominately type 1 immune mediated response to the donor alloantigen. However, the type 2 immune mediated response has been implicated in multiple fibroproliferative diseases. Based on the fibro-obliterative lesion found during bronchiolitis obliterans syndrome (BOS), we hypothesized that the type 2 immune mediated response is involved in chronic lung allograft rejection. Specifically, whereas acute rejection is, in part, a type 1 immune response, chronic rejection is, in part, a type 2 immune response. We found the type 2 cytokine, IL-13, to be elevated and biologically active in human bronchoalveolar lavage fluid during BOS. Translational studies using a murine model of BOS demonstrated increased expression of IL-13 and its receptors that paralleled fibro-obliteration. In addition, in vivo neutralization of IL-13 reduced airway allograft matrix deposition and murine BOS, by a mechanism that was independent of IL-4. Furthermore, using IL-13Rα2−/− mice, we found increased fibro-obliteration. Moreover, anti-IL-13 therapy in combination with cyclosporin A had profound effects on reducing murine BOS. This supports the notion that IL-13 biological axis plays an important role during the pathogenesis of BOS independent of the IL-4 biological axis.

Validation of a Method To Screen for Pulmonary Hypertension in Advanced Idiopathic Pulmonary Fibrosis

BACKGROUND We have developed a method to screen for pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) patients, based on a formula to predict mean pulmonary artery pressure (MPAP) from standard lung function measurements. The objective of this study was to validate this method in a separate group of IPF patients. METHODS Cross-sectional study of 60 IPF patients from two institutions. The accuracy of the MPAP estimation was assessed by examining the correlation between the predicted and measured MPAPs and the magnitude of the estimation error. The discriminatory ability of the method for PH was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS There was strong correlation in the expected direction between the predicted and measured MPAPs (r = 0.72; p < 0.0001). The estimated MPAP was within 5 mm Hg of the measured MPAP 72% of the time. The AUC for predicting PH was 0.85, and did not differ by institution. A formula-predicted MPAP > 21 mm Hg was associated with a sensitivity, specificity, positive predictive value, and negative predictive value of 95%, 58%, 51%, and 96%, respectively, for PH defined as MPAP from right-heart catheterization > 25 mm Hg. CONCLUSIONS A prediction formula for MPAP using standard lung function measurements can be used to screen for PH in IPF patients.

Altered Levels of CC Chemokines During Pulmonary CMV Predict BOS and Mortality Post-Lung Transplantation

Pulmonary CMV infection (CMVI) and disease (CMVD) is associated with reduced long‐term survival post‐lung transplantation, however, the specific biologic mechanisms remain unclear. We have demonstrated a role of CC chemokines during lung allograft dysfunction. Based on these findings, we hypothesized that pulmonary CMV upregulates the expression of multiple CC chemokines that leads to allograft dysfunction and decreased long‐term survival.

Retrospective Study of Pulmonary Function Tests in Patients Presenting With Isolated Reduction in Single-Breath Diffusion Capacity: Implications for the Diagnosis of Combined Obstructive and Restrictive Lung Disease

OBJECTIVE To examine the frequency and spectrum of diseases associated with isolated reduction in the diffusing capacity of lung for carbon monoxide (D(Lco)). PATIENTS AND METHODS We retrospectively identified all potentially dyspneic patients who had pulmonary function tests (PFTs) performed at the Mayo Clinic in Jacksonville, Fla, between January 1, 1990, and June 30, 2000, that showed reduced D(Lco) (< 70% of predicted), normal lung volumes (total lung capacity and residual volume > 80% and < 120% of predicted, respectively), and airflow variables (forced expiratory volume in 1 second and forced vital capacity values > 80% of predicted and forced expiratory volume in 1 second/forced vital capacity ratio > 70% of predicted). Only patients who had also undergone chest computed tomography (CT) and echocardiography within 1 month of PFTs were studied. RESULTS Of the 38,095 patients who underwent PFTs during the study period, 179 (0.47%; 95% confidence interval [CI], 0.40%-0.54%) had isolated D(Lco) abnormalities. The 27 patients (15.1%; 95% CI, 10.2%-21.2%) who had also undergone chest CT and echocardiography within 1 month of PFTs form the study cohort reported herein. Their mean D(Lco) was 50% +/- 15% (95% CI, 45%-56%) with average normal pulse oxygen saturation at rest and mild hypoxemia with activity. Thirteen of the 27 patients (48%; 95% CI, 28.7%-68.1%) had underlying emphysema evident on CT. Eleven of these 13 patients had emphysema associated with a restrictive lung process. The 14 patients without emphysema had interstitial lung disease, pulmonary vascular disease, and other isolated findings. Six patients with combined emphysema and idiopathic pulmonary fibrosis accounted for the largest percentage (22%) of patients with Isolated D(Lco) reduction. The mean +/- SD smoking history of the 27 patients in the study cohort was 36 +/- 33 pack-years (range, 0-116 pack-years). CONCLUSION Dyspneic patients with respiratory symptoms and normal lung volumes and airflows associated with Isolated reduction in D(Lco) should be evaluated for underlying diseases such as emphysema, with or without a concomitant restrictive process, and pulmonary vascular disease.