Harish Seethamraju

Blockade of IL-6 Trans Signaling Attenuates Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease with progressive fibrosis and death within 2–3 y of diagnosis. IPF incidence and prevalence rates are increasing annually with few effective treatments available. Inhibition of IL-6 results in the attenuation of pulmonary fibrosis in mice. It is unclear whether this is due to blockade of classical signaling, mediated by membrane-bound IL-6Rα, or trans signaling, mediated by soluble IL-6Rα (sIL-6Rα). Our study assessed the role of sIL-6Rα in IPF. We demonstrated elevations of sIL-6Rα in IPF patients and in mice during the onset and progression of fibrosis. We demonstrated that protease-mediated cleavage from lung macrophages was important in production of sIL-6Rα. In vivo neutralization of sIL-6Rα attenuated pulmonary fibrosis in mice as seen by reductions in myofibroblasts, fibronectin, and collagen in the lung. In vitro activation of IL-6 trans signaling enhanced fibroblast proliferation and extracellular matrix protein production, effects relevant in the progression of pulmonary fibrosis. Taken together, these findings demonstrate that the production of sIL-6Rα from macrophages in the diseased lung contributes to IL-6 trans signaling that in turn influences events crucial in pulmonary fibrosis.

Comparison of Sirolimus with Azathioprine in a Tacrolimus-based Immunosuppressive Regimen in Lung Transplantation

RATIONALE Lung transplantation has evolved into a life-saving therapy for select patients with end-stage lung diseases. However, long-term survival remains limited because of chronic rejection. Sirolimus is beneficial in preventing cardiac rejection and may decrease rejection after lung transplantation. OBJECTIVES To determine the potential benefit versus risk of sirolimus in lung transplantation. METHODS We conducted a multicenter randomized, open label controlled trial comparing sirolimus (SIR) with azathioprine (AZA) in a tacrolimus-based immunosuppressive regimen in lung transplantation. The primary end point was the incidence of acute rejection at 1 year after transplantation between the two study groups. MEASUREMENTS AND MAIN RESULTS One hundred eighty-one patients were randomized to be included in this study. At 1 year after transplantation, there was no significant difference in the incidence of grade A acute rejection between the two study groups. Similarly, the incidence of chronic rejection and graft survival was no different between the two study groups. Cytomegalovirus infection was decreased in the SIR arm compared with the AZA arm (relative risk, 0.67 [95% confidence interval, 0.55, 0.82]; P < 0.01). There was a higher rate of adverse events leading to early discontinuation of SIR (64%) compared with AZA (49%) during the course of this study. CONCLUSIONS Sirolimus, an mTOR inhibitor, did not decrease the incidence of acute rejection at 1 year compared with azathioprine in lung transplantation. These results differ from previous results in cardiac and renal transplantation and emphasize the need for multicenter randomized controlled trials in lung transplantation. Clinical trial registered with www.clinicaltrials.gov (NCT 00321906).

Treatment of hyperacute antibody-mediated lung allograft rejection with eculizumab

We report the case of a highly sensitized (cPRA 99%, Class II) 56-year-old white female with a lung allocation score of 38, who underwent double lung transplantation for pulmonary fibrosis and pulmonary hypertension. Pre-transplant desensitization with multiple courses of plasma exchange (PE) and intravenous immunoglobulin (IVIg) was largely unsuccessful. The surgical operation was uneventful; however, the patient was found to have a positive prospective B-cell crossmatch according to both anti-human globulincomplement-dependent cytotoxicity and flow cytometry studies. At the time of transplant, the recipient had the following donor-specific antibodies (DSAs): DR8 (15,000 MFI); DR14 (14,000 MFI); DR52 (15,000 MFI); and DQ7 (3,800 MFI). PE was performed on post-operative days (PODs) 1, 0 and 1, and IVIg was given along with rituximab and bortezomib due to the positive B-cell crossmatch. Repeat DSAs post-implantation/PE were initially negative; however, the patient subsequently developed acute graft dysfunction (Figure 1) and, by POD 2, the P/F ratio had fallen from 106 to 33 and she was initiated on extracorporeal membrane oxygenation (ECMO), nitric oxide, multiple pressors and renal replacement therapy. An open-lung biopsy was performed showing neutrophilic capillaritis and C4d positivity suggestive of antibody-mediated rejection (AMR). An ensuing set of DSAs showed the antibodies against DR8, DR14, DR52 and DQ7 were again present. On POD 2, the decision was made to hold PE and give the anti-C5 antibody, eculizumab, which dramatically halted the disease progression. Extracorporeal membrane oxygenation (ECMO) was discontinued after 3 days and the chest X-ray gradually improved. After the initial 1,200-mg dose, 600 mg of eculizumab was again given on PODs 6, 8 and 9, for a cumulative dose of 3,000 mg, along with 4 doses of bortezomib 1.3 mg/m, 2 doses of rituximab 375 mg/m, 160 g of IVIg and 3 PEs post-transplant (Figure 2). After weaning off ventilator support and hemodialysis, the patient was discharged on POD 47. The 1-month biopsy was 15% positive for C4d, and the 3-month biopsy was unremarkable. The patient is now alive and well at 1 year post-transplant with no re-hospitalizations, infectious complications or

Increased risk of venous thromboembolism with a sirolimus-based immunosuppression regimen in lung transplantation

BACKGROUND Sirolimus (rapamycin) is a potent anti-proliferative agent with immunosuppressive properties that is increasingly being used in solid-organ and hematopoietic stem cell transplantation. In addition, this drug is being investigated for treatment of a broad range of disorders, including cardiovascular disease, malignancies, tuberous sclerosis, and lymphangeioleiomyomatosis. In this study, we found an increased risk of venous thromboembolism (VTE) in lung transplant recipients treated with a sirolimus (SIR)-based immunosuppressive regimen. METHODS One hundred eighty-one lung transplant recipients were enrolled in a prospective, multicenter, randomized, open-label trial comparing a tacrolimus (TAC)/SIR/prednisone immunosuppression regimen with a TAC/azathioprine (AZA)/prednisone immunosuppressive regimen. The differences in rates of VTE were examined. RESULTS There was a significantly higher occurrence of VTE in the SIR cohort [15 of 87 (17.2%)] compared with the AZA cohort [3 of 94 (3.2%)] (stratified log-rank statistic = 7.44, p < 0.01). When adjusted for pre-transplant diagnosis and stratified by transplant center, this difference remained essentially unchanged (hazard ratio for SIR vs AZA = 5.2, 95% confidence interval 1.4 to 19.5, p = 0.01). CONCLUSION Clinicians prescribing SIR should maintain a high level of vigilance for VTE, particularly among patients with other risk factors for this complication.

Adenosine A2B receptor and hyaluronan modulate pulmonary hypertension associated with Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide. The development of pulmonary hypertension (PH) in patients with COPD is strongly associated with increased mortality. Chronic inflammation and changes to the lung extracellular matrix (ECM) have been implicated in the pathogenesis of COPD, yet the mechanisms that lead to PH secondary to COPD remain unknown. Our experiments using human lung tissue show increased expression levels of the adenosine A2B receptor (ADORA2B) and a heightened deposition of hyaluronan (HA; a component of the ECM) in remodeled vessels of patients with PH associated with COPD. We also demonstrate that the expression of HA synthase 2 correlates with mean pulmonary arterial pressures in patients with COPD, with and without a secondary diagnosis of PH. Using an animal model of airspace enlargement and PH, we show that the blockade of ADORA2B is able to attenuate the development of a PH phenotype that correlates with reduced levels of HA deposition in the vessels and the down-regulation of genes involved in the synthesis of HA.

Robot-Assisted Stenting of a High-Grade Anastomotic Pulmonary Artery Stenosis Following Single Lung Transplantation

Purpose: To report robot-assisted stenting of a stenosis at the pulmonary artery anastomosis following lung transplantation, a rare complication that conveys poor prognosis even after surgical correction. Technique: The technique is illustrated in a 72-year-old man with end-stage lung disease who received a left single lung transplant. On postoperative day 54, he was evaluated for recurrent dyspnea on exertion that was due to a severe stenosis at the site of the pulmonary artery anastomosis. Balloon angioplasty was performed, and a 10-mm stent was deployed, with marked clinical improvement. Fourteen months later, he presented with recurrent symptoms due to in-stent restenosis. Multiple attempts at catheterization and balloon angioplasty of the stent failed. Due to the technical difficulty involved in maneuvering the balloon while maintaining stability, it was decided to repeat the angioplasty with the assistance of a Hansen Sensei remote robotic navigation system. The robotic arm markedly enhanced stability and facilitated successful navigation of the stented site. A 16-mm-diameter Wallstent was placed through the previously placed balloon-expandable stent and postdilated. Conclusion: A remote robotic catheter navigation system was able to assist stenting of an anastomotic pulmonary artery stenosis following failure of conventional interventional techniques.

Interobserver Variability in Grading Transbronchial Lung Biopsy Specimens After Lung Transplantation

BACKGROUND Acute rejection remains a major source of morbidity after lung transplantation. Given the importance of this diagnosis, an international grading system was developed to standardize the diagnosis of acute lung-allograft rejection. The reliability of this grading system has not been adequately assessed by previous studies. METHODS We examined the level of agreement in grading transbronchial biopsy specimens obtained from a large multicenter study (AIRSAC [Comparison of a Tacrolimus/Sirolimus/Prednisone Regimen vs Tacrolimus/Azathioprine/Prednisone Immunosuppressive Regimen in Lung Transplantation] trial). Biopsy specimens were initially graded for acute rejection and lymphocytic bronchiolitis by the site pathologist and subsequently graded by a central pathologist. Reliability of interobserver grading was evaluated using Cohen κ coefficients. RESULTS A total of 481 transbronchial biopsy specimens were graded by both the site and central pathologists. The overall concordance rates were 74% and 89% for grade A and grade B biopsy specimens, respectively. When samples from biopsies performed at different time points after transplantation were assessed, there was a higher level of agreement early (≤ 6 weeks) after transplant compared with later time points for acute rejection. However, there was still only moderate agreement for both grade A (κ score 0.479; 95% CI, 0.29-0.67) and grade B (κ score 0.465; 95% CI, 0.08-0.85) rejection. CONCLUSIONS These results expand upon previous reports of interobserver variability in grading transbronchial biopsy specimens after lung transplantation. Given the variability in grading these specimens, we advocate further education of the histopathologic findings in lung transplant biopsy specimens, as well as revisiting the current criteria for grading transbronchial biopsy specimens to improve concordance among lung transplant pathologists. TRIAL REGISTRY ClinicalTrials.gov; No. NCT00321906; URL: www.clinicaltrials.gov.

Decreased incidence of cytomegalovirus infection with sirolimus in a post hoc randomized, multicenter study in lung transplantation

BACKGROUND Cytomegalovirus (CMV) is the most common opportunistic infection in lung transplantation. A recent multicenter, randomized trial (the AIRSAC study) comparing sirolimus to azathioprine in lung transplant recipients showed a decreased incidence of CMV events in the sirolimus cohort. To better characterize this relationship of decreased incidence of CMV events with sirolimus, we examined known risk factors and characteristics of CMV events from the AIRSAC database. METHODS The AIRSAC database included 181 lung transplant patients from 8 U.S.-based lung transplant centers that were randomized to sirolimus or azathioprine at 3 months post-transplantation. CMV incidence, prophylaxis, diagnosis and treatment data were all prospectively collected. Prophylaxis and treatment of CMV were at the discretion of each institution. RESULTS The overall incidence of any CMV event was decreased in the sirolimus arm when compared with the azathioprine arm at 1 year after lung transplantation (relative risk [RR] = 0.67, confidence interval [CI] 0.55 to 0.82, p < 0.01). This decreased incidence of CMV events with sirolimus remained significant after adjusting for confounding factors of CMV serostatus and CMV prophylaxis. CONCLUSIONS These data support results from other solid-organ transplantation studies and suggest further investigation of this agent in the treatment of lung transplant recipients at high risk for CMV events.

Combined lung and liver transplantation

Patients with end‐stage lung disease complicated by cirrhosis are not expected to survive lung transplantation alone. Such patients are potential candidates for combined lung‐liver transplantation (CLLT), however few reports document the indications and outcomes after CLLT. This is a review of a large single‐center CLLT series. Eight consecutive CLLT performed during 2009‐2012 were retrospectively reviewed. One patient received a third simultaneous heart transplant. Mean age was 42.5 ± 11.5 years. Pulmonary indications included cystic fibrosis (CF) (n = 3), idiopathic pulmonary fibrosis (n = 2), α1‐antitrypsin deficiency (AATD) (n = 1) and pulmonary hypertension (n = 2). Liver indications were CF (n = 3), hepatitis C (n = 2), AATD (n = 1), cryptogenic (n = 1), and cardiac/congestive (n = 1). Urgency was reflected by median lung allocation score (LAS) of 41 (36.0‐89.0) and median predicted FEV1 of 25.7%. Median donor age was 25 (20‐58) years with median cold ischemia times of 147 minutes and 6.1 hours for lung and liver, respectively. Overall patient survival at 30 days, 90 days and 1 year was 87.5%, 75.0% and 71.4% respectively. One patient had evidence of acute lung rejection, and no patients had liver allograft rejection. Early postoperative mortalities (90 days) were caused by sepsis in 2 recipients who exhibited the highest LAS of 69.9 and 89.0. The remaining recipients had a median LAS of 39.5 and 100% survival at 1‐year. Median length of stay was 25 days (7‐181). Complications requiring operative intervention included bile duct ischemia (n = 1) and bile leak (n = 1), ischemia of the bronchial anastomosis (n = 1), and necrotizing pancreatitis with duodenal perforation (n = 1). This series reflects a large single‐center CLLT experience. Sepsis is the most common cause of death. The procedure should be considered for candidates with LAS < 50. Liver Transpl 20:46–53, 2014.

Atrial arrhythmias after lung transplant: Underlying mechanisms, risk factors, and prognosis

BACKGROUND Atrial arrhythmias (AAs) early after lung transplant are frequent and have a significant impact on morbidity and mortality. However, the pathogenesis of AAs after lung transplant remains incompletely understood. In this study we aimed to determine the prevalence of atrial fibrillation (AF) and other AAs, as well as risk factors, clinical outcomes and possible underlying mechanisms associated with AAs after lung transplant. METHODS A retrospective analysis was performed on 382 patients who underwent lung transplantation from 2000 to 2010. A 12-lead electrocardiogram (ECG) was obtained and AAs classified as AF and other AAs (atrial flutter [AFL] and supraventricular tachycardia [SVT]). Multivariate logistic regression analysis was performed to determine predictors, and Kaplan-Meier survival curves were constructed. RESULTS The incidence of AAs was 25%; 17.8% developed AF and 7.6% other AAs (AFL/SVT). The major indication for transplant was idiopathic pulmonary fibrosis (IPF, 35%). Significant predictors of AF were as follows: age; IPF; left atrial enlargement; diastolic dysfunction; and history of coronary artery disease (CAD). Risk factors for other AAs (AFL/SVT) were: age; right ventricle dysfunction; right ventricular enlargement; and elevated right atrial pressure (RAP). One-year mortality was higher in the arrhythmia group (21.5% arrhythmia vs 15.7% no-arrhythmia group; p < 0.05). In addition, patients treated with anti-arrhythmic medications had higher mortality (p < 0.05). CONCLUSIONS AAs are common after lung transplantation. Risk factors for developing either AF or other AAs (AFL/SVT) are different. The development of early AAs post-transplant is associated with prolonged post-operative stay and increased mortality. A rate-control strategy should be used as first-line therapy and anti-arrhythmic agents reserved for those patients who do not respond to the initial treatment.