Impact of antiviral therapy on short- and long-term outcomes of patients with chronic obstructive pulmonary disease after influenza infection

Background

Respiratory complications often accompany influenza in patients with chronic obstructive pulmonary disease (COPD). In this retrospective study, we quantified the impact of antiviral therapy on exacerbations, healthcare resource utilization (HRU), and costs in patients with COPD across 5 influenza seasons.

Methods

Using claims data from US MarketScan® databases, we identified patients with COPD who had an influenza diagnosis during the 2012-2016 influenza seasons. Patients who received a neuraminidase inhibitor within 48 h of diagnosis (N = 4134) were identified and propensity score-matched 1:1 to a comparator cohort of untreated patients. We determined COPD- and pneumonia-related HRU and costs during month 1, each subsequent quarter, and months 2-13.

Results

Antiviral-treated patients had a significantly lower frequency of COPD-related outcomes than untreated patients during all periods (exacerbations: 10.4% vs 18.2% [month 1] and 17.7% vs 24.2% [months 2-13]; inpatient visit: 2.5% vs 7.9% [month 1] and 3.8% vs 6.7% [months 2-13]; P < 0.0001, all comparisons). Treated patients also had significantly lower outpatient and emergency department (ED) visits beyond month 1. Pneumonia-related inpatient, ED, and outpatient visits were significantly lower in antiviral-treated patients than in untreated patients over all periods (P < 0.0001, all comparisons). In all HRU categories, COPD- and pneumonia-related costs were significantly lower in treated patients over all periods (month-1 ED visit costs were higher).

Conclusions

Antiviral treatment in patients with COPD and influenza is associated with significantly lower HRU and costs in the postinfection month and for an entire year following infection compared with untreated patients.

Impact of influenza infection on the short- and long-term health of patients with chronic obstructive pulmonary disease

BACKGROUND

Influenza is a common cause of acute respiratory infection that leads to exacerbation of underlying chronic obstructive pulmonary disease (COPD). To elucidate the short- and long-term effects of influenza in patients with COPD, we examined health care resource utilization (HRU) and costs up to 13 months following influenza infection.

METHODS

We conducted a retrospective cohort study using U.S. insurance claims data from MarketScan. Patients with an influenza diagnosis during the 2012-2014 influenza seasons and continuous enrollment in a health plan from 12 months before to 13 months after the index influenza diagnosis were identified and propensity score-matched 1:5 to controls without evidence of influenza. COPD- and pneumonia-related outcomes were assessed over 13 months following influenza diagnosis.

RESULTS

COPD-associated outcomes after diagnosis were significantly worse in patients with influenza (n = 7,087) vs. controls (n = 35,435) during the first month (exacerbation: 16.1 vs. 3.4%; outpatient visits: 57.1 vs. 35.2%; emergency department (ED) visits: 10.5 vs. 1.8%; and inpatient visits: 5.6 vs. 0.7%) and months 2-13 (exacerbation: 25.1 vs. 21.1%; outpatient visits: 86.1 vs. 85.8%; ED visits: 20.0 vs. 15.7%; and inpatient visits: 6.5 vs. 5.3%). COPD- and pneumonia-associated costs for months 1 and 2-13 were higher in patients with influenza.

LIMITATIONS

The study was subject to a residual imbalance between cohorts despite propensity score matching. The use of diagnostic codes to select patients and identify complications could introduce inaccuracies in estimating events.

CONCLUSIONS

HRU and costs were higher in COPD patients with influenza during the first month and over the entire year following infection. This suggests influenza has an impact on respiratory health in patients with COPD that lasts beyond the acute infection.

Revisiting Type 2-high and Type 2-low airway inflammation in asthma: current knowledge and therapeutic implications

Asthma is a complex respiratory disorder characterized by marked heterogeneity in individual patient disease triggers and response to therapy. Several asthma phenotypes have now been identified, each defined by a unique interaction between genetic and environmental factors, including inflammatory, clinical and trigger-related phenotypes. Endotypes further describe the functional or pathophysiologic mechanisms underlying the patient's disease. type 2-driven asthma is an emerging nomenclature for a common subtype of asthma and is characterized by the release of signature cytokines IL-4, IL-5 and IL-13 from cells of both the innate and adaptive immune systems. A number of well-recognized biomarkers have been linked to mechanisms involved in type 2 airway inflammation, including fractional exhaled nitric oxide, serum IgE, periostin, and blood and sputum eosinophils. These type 2 cytokines are targets for pharmaceutical intervention, and a number of therapeutic options are under clinical investigation for the management of patients with uncontrolled severe asthma. Anticipating and understanding the heterogeneity of asthma and subsequent improved characterization of different phenotypes and endotypes must guide the selection of treatment to meet individual patients' needs.

Dipeptidyl peptidase IV (DPPIV/CD26) inhibition does not improve engraftment of unfractionated syngeneic or allogeneic bone marrow after nonmyeloablative conditioning

In order to develop minimally toxic bone marrow transplantation (BMT) protocols suitable for use in a wider range of indications, it is important to identify ways to enhance BM engraftment at a given level of recipient conditioning. CXCL12/stromal cell-derived factor-1α plays a crucial physiological role in homing of hematopoietic stem cells to BM. It is regulated by the ectopeptidase dipeptidyl peptidase IV (DPPIV; DPP4) known as CD26, which cleaves dipeptides from the N-terminus of polypeptide chains. Blocking DPPIV enzymatic activity had a beneficial effect on hematopoietic stem cell engraftment in various but very specific experimental settings. Here we investigated whether inhibition of DPPIV enzymatic activity through Diprotin A or sitagliptin (Januvia) improves BM engraftment in nonmyeloablative murine models of syngeneic (i.e., CD45-congenic) and allogeneic (i.e., Balb/c to B6) BMT (1 Gy total body irradiation, 10–15 × 10⁶ unseparated BM cells/mouse). Neither Diprotin A administered in vivo at the time of BMT and/or used for in vitro pretreatment of BM nor sitagliptin administered in vivo had a detectable effect on the level of multilineage chimerism (follow-up >20 weeks). Similarly, sitagliptin did not enhance chimerism after allogeneic BMT, even though DPPIV enzymatic activity measured in serum was profoundly inhibited (>98% inhibition at peak exposure). Our results provide evidence that DPPIV inhibition via Diprotin A or sitagliptin does not improve engraftment of unseparated BM in a nonmyeloablative BMT setting.

Inhibition of CD26/DPP IV attenuates ischemia/reperfusion injury in orthotopic mouse lung transplants: the pivotal role of vasoactive intestinal peptide

The T cell activation Ag CD26/dipeptidylpeptidase IV (DPP IV) combines co-stimulatory and enzymatic properties. Catalytically, it functions as an exopeptidase, modulating biological activity of key chemokines and peptides. Here we investigated the effect of organ-specific inhibition of DPP IV catalytic activity on ischemia/reperfusion injury after extended ischemia in the mouse model of orthotopic single lung transplantation. C57BL/6 mice were syngeneically, transplanted, grafts were perfused and stored in Perfadex with (treated) or without (control) a DPP IV enzymatic activity inhibitor (AB192). Transplantation was performed after 18h cold ischemia time; following 2-h reperfusion, grafts were analyzed for oxygenation, thiobarbituric acid-reactive substances, histomorphology, and immunohistochemistry was performed for leukocyte Ag 6, myeloperoxidase, hemoxygenase 1, vasoactive intestinal protein (VIP), and real-time PCR for VIP. Treatment with the DPP IV inhibitor AB192 resulted in significant improvement of gas exchange, less lipid oxidation, preservation of parenchymal ultrastructure, reduced neutrophil infiltration, reduced myeloperoxidase expression, increased hemoxygenase 1 expression, pronounced expression of VIP in alveolar macrophages and increased mRNA expression of VIP. Inhibition of intragraft DPP IV catalytic activity with AB192 strikingly ameliorates ischemia/reperfusion injury after extended ischemia. Furthermore, preservation of endogenous intragraft VIP levels correlate with maintaining lung function and structural integrity.

A model of chronic lung allograft rejection in the rat

Bronchiolitis obliterans, the pathological hallmark of chronic pulmonary rejection, severely impacts long-term survival following lung transplantation. However, experimental reproduction of this pathophysiological phenomenon has not been achieved with contemporary in vivo models. Here, a model of chronic rejection is described, with sensitised recipients receiving unilateral orthotopic rat lung transplants. Lewis rats, sensitised with skin from brown Norway rats 7 days before receiving left lung transplants from donors that were Lewis x brown Norway F(1) hybrids, were analysed during day 21-84. The development of chronic rejection was modulated by a treatment with rapamycin and cyclosporin, and characterised histologically, immunohistochemically and by reverse transcriptase PCR. Characteristic histopathological changes leading to chronic rejection were induced over time by an initial treatment with cyclosporin in the presence of continuous rapamycin application. At day 84, fibrotic lesions replaced the respiratory epithelium within small bronchioles, with strong expression of smooth muscle alpha-actin and upregulation of mRNA for T-helper cell type-1 cytokines, smooth muscle alpha-actin, transforming growth factor-beta and CC chemokine ligand 5, but decreased forkhead box protein P3 gene expression. A reproducible and clinically relevant experimental set-up for progressive chronic rejection in rat pulmonary allografts is described. This model will permit better understanding of the pathological changes of small airways during the development of bronchiolitis obliterans, and may serve as an in vivo set-up for testing the efficacy of novel therapeutic interventions.

Distribution of macrophages and T cells in syngrafts and allografts after experimental rat lung transplantation

Macrophages and T cells have a pivotal role in orchestrating the acute lung allograft rejection response. We investigated the spatial and temporal distribution of these immune cells and the synthesis patterns of the T(h)1- and T(h)2-cytokine IL-12 and IL-10 during the early course after transplantation (Tx). Orthotopic single-lung Tx was performed in Lewis to Lewis (syngrafts) and Brown Norway/Lewis F(1) hybrid to Lewis (allografts). Naïve lungs, syngrafts after 5 days and allografts after 3 and 5 days were analyzed for CD68+, CD163+ and CD3+ cells by immunohistochemistry and IL-12 and IL-10 were detected by immunofluorescence. CD68+ macrophages increased in number after allogeneic Tx compared to syngeneic Tx on day 5 (P<.001), CD163+ macrophages sequestrated early around veins (day 3) compared to the accumulation around arteries and bronchioles (P<.001) while CD3+ T cells were scarce. There was a predominance of IL-12 over IL-10 on day 5 after allogeneic Tx (P<.001). CD68+ macrophages were the most abundant cells during acute pulmonary rejection and CD163+ macrophages showed a characteristic distribution pattern over time around vessels and bronchioles. The up-regulation of IL-12 reflects an early response after allo-antigen exposure, indicating a strong impact of the initiation of the T(h)1 pathway at an early phase during acute lung rejection.

A mouse model of orthotopic, single-lung transplantation

OBJECTIVES

Progress in studying acute and chronic pulmonary allograft rejection has been hampered by the lack of feasible experimental animal transplantation models. Contemporary approaches are limited by anatomic applicability (heterotopic tracheal implantation) and lack of genetic variability (rat model). To utilize the breadth of available genetic modifications in a physiologic setup, we optimized and validated a procedure of orthotopically transplanted, perfused, and ventilated single pulmonary transplantation in mice.

METHODS

C57BL/6 mice served as recipient, with Balb/c as donor. At time of harvest, explanted lungs were perfused with Perfadex, and the heart-lung block excised. Under 30 to 40x magnification, vessels and bronchus were cuffed. Following left thoracotomy in the recipient, hilar structures were incised and cuff-anastomosed with the corresponding donor parts. Allogeneic and syngeneic transplantations (n = 12/group) were performed with a follow-up period of 5 days and up to 90 days, respectively.

RESULTS

The success rate of lung transplantation in mice was 87.5% (21/24). Mean cold ischemia time was 32.3 +/- 3.7 minutes, and warm ischemia time was 30.8 +/- 9.5 minutes. Deaths were due to bleeding during dissection of the hilus and/or caused by thrombosis postoperatively. Allogeneic grafts were rejected by day 5; syngeneic grafts were slightly congested but mainly unchanged up to day 90 posttransplantation.

CONCLUSIONS

Unilateral lung transplantation in mice can be performed in a standardized and controlled fashion with low mortality, comparable to the rat. Employing transgenic and knockout mice strains, this procedure holds great promise to advance the understanding of immunologic pathways in acute and chronic rejection in a physiologic model of pulmonary transplantation.

A multicenter, randomized, double-blind trial of everolimus versus azathioprine and placebo to maintain steroid-induced remission in patients with moderate-to-severe active Crohn's disease

OBJECTIVES

A prospective study was undertaken to compare the efficacy of everolimus versus azathioprine or placebo in maintaining steroid-induced remission in active Crohn's disease (CD) and assess the safety and pharmacokinetics of everolimus.

METHODS

This was a randomized, double-blind, placebo-controlled, proof-of-concept study in adults with moderate-to-severe active CD. The patients received oral steroids for a rapid induction of remission plus everolimus 6 mg/day, azathioprine 2.5 mg/kg/day, or placebo as maintenance treatment. The main outcome measure was the treatment success, defined as a steroid-free remission by the end of month 3 and maintained until study cutoff without the use of prohibited efficacy treatments.

RESULTS

Following an interim analysis, the study was terminated before enrollment was completed due to the lack of efficacy. The full intent-to-treat population comprised 138 patients. Only 96 patients who entered the study > or =7 months prior to data cutoff were included in the primary efficacy population. The treatment success was achieved in 13 of 38 everolimus patients, 22 of 36 azathioprine patients, and 8 of 22 placebo patients. Using the Kaplan-Meier estimates at month 7, the incidence of treatment success was 22.0% with everolimus group (95% confidence interval [CI] 6.7-37.3%, P= 0.610 vs placebo), 38.3% with azathioprine group (95% CI 20.6-55.9%, P= 0.500 vs placebo), and 28.8% with placebo group (95% CI 7.7-49.9%). The type and incidence of adverse events in the everolimus cohort were similar to those reported in the approved transplantation indications.

CONCLUSIONS

The safety and tolerability of everolimus (6 mg/day) in patients with active CD were comparable to azathioprine. At this dose, everolimus is not more efficacious in achieving a steroid-free remission in active CD than the comparators.

Simplified rat lung transplantation by using a modified cuff technique

Mizuta's cuff technique in rat lung transplantation (LT) model has some disadvantages, such as twisting of blood vessels or bronchus and being time-consuming, which complicate procedures for anastomosis. This study was performed to investigate the advantage of using a simplified cuff technique in LT. The anastomosis time was compared in two groups. In group I, Mizuta'scuff technique was performed in 50 rat orthotopic left lung transplants. In group II, a simple modified cuff technique was performed in 48 rat orthotopic left lung transplants. The successful rate of the new technique for anastomosis was 100%. No twist of vessels or bronchus and no bleeding or air leakage were observed in group II. The anastomosis time of group II was significantly less than for group I (11.2 +/- 2.1 min vs. 18.1 +/- 3.6 min, mean +/- SD, p < .01). This simple modified cuff technique led to less anastomosis time and avoided potential complications induced by the cuff-tail technique. It has been verified to be a safe, simple, and reproducible technique that can provide us with a more precise assessment in the rat LT model.

Acute allograft rejection and immunosuppression: influence on endogenous melatonin secretion

Melatonin displays a dose-dependent immunoregulatory effect in vitro and in vivo. Exogenous high-dose melatonin therapy exerted an immunosuppressive effect, abrogating acute rejection (AR), significantly prolonging transplant survival. Endogenous melatonin secretion, in response to heterotopic rat cardiac allograft transplantation (Tx), was investigated during the AR response and under standardized immunosuppressive maintenance therapy with cyclosporin A (CsA) and rapamycin (RPM). Recipients of syngeneic transplants, and recipients of allogeneic grafts, either untreated or receiving immunosuppressive therapy constituted the experimental groups. Endogenous circadian melatonin levels were measured at 07:00, 19:00, and 24:00 hr, using a novel radioimmunoassay (RIA) procedure, under standardized 12-hr-light/dark-conditions (light off: 19:00 hr; light on: 07:00 hr), before and after Tx. Neither the operative trauma, nor the challenge with a perfused allograft or the AR response influenced endogenous melatonin peak secretion. Immunosuppressive therapy with CsA led to a significant increase in peak secretion, measured for days 7 (212 +/- 40.7 pg/mL; P < 0.05), 14 (255 +/- 13.9 pg/mL; P < 0.001), and 21 (219 +/- 34 pg/mL; P < 0.01) after Tx, as compared with naïve animals (155 +/- 25.8 pg/mL). In contrast, treatment with RPM significantly decreased the melatonin peak post-Tx up to day 7 (87 +/- 25.2 pg/mL; P < 0.001), compared with naïve animals (155 +/- 25.8 pg/mL). These findings imply a robust nature of the endogenous circadian melatonin secretion kinetics, even against the background of profound allogeneic stimuli. Immunosuppressive maintenance therapy with CsA and RPM modulated early melatonin secretion, indicating a specific secondary action of these drugs. Further studies are necessary to disclose the long-term effect of immunosuppressive therapy on circadian melatonin secretion in transplant recipients.

Intragraft DPP IV Inhibition Attenuates Post-transplant Pulmonary Ischemia/Reperfusion Injury After Extended Ischemia

BACKGROUND

CD26/DPP IV is a T-cell-membrane protein that cleaves dipeptides from extracellular peptides. Inhibition of its enzymatic activity using Pro-Pro-diphenylphosphonate derivatives has been shown to abrogate acute and accelerated rejection in models of cardiac and pulmonary allotransplantation. Here we investigated the effects of enzymatic DPP IV inhibition on ischemia/reperfusion (I/R) injury after extended ischemia before pulmonary transplantation.

METHODS

A syngeneic rat orthotopic left-lung transplantation model was used. Group I donor lungs (controls) were flushed and preserved in Perfadex for 18 hours at 4 degrees C and then transplanted and reperfused for 2 hours. Group II grafts were perfused with and stored in Perfadex + 25 micromol/liter AB192 [bis(4-acetamidophenyl) 1-(S)-prolylpyrrolidine-2(R,S)-phosphonate]. Group III lungs were perfused with Perfadex + AB192, and stored in Perfadex. After 2-hour reperfusion, oxygenation, peak airway pressure (PawP), graft wet/dry (W/D) weight ratio, myeloperoxidase activity, thiobarbituric acid-reactive substances, graft specific DPP IV enzymatic activities and histomorphology were analyzed.

RESULTS

AB192 perfusion significantly reduced DPP IV intragraft enzymatic activity in Groups II and III. Compared with controls, transplants from Groups II and III showed significantly improved oxygenation capacity, PawP and W/D weight ratio, with lower intragraft lipid peroxidation; and preserved histologic structure.

CONCLUSIONS

Targeting intragraft DPP IV enzymatic activity attenuated post-transplantation I/R injury and preserved early graft function after extended ischemia.

Ischemia/Reperfusion Injury: The Role of CD26/Dipeptidyl-Peptidase-IV-Inhibition in Lung Transplantation

CD26/Dipeptidyl peptidase (DPP) IV is an integral membrane protein of lymphocytes that modulates the activities of chemokines, interleukins, and neuropeptides. We investigated the effect of enzymatic DPP IV inhibition on ischemia/reperfusion injury after extended ischemia prior to transplantation.

MATERIALS AND METHODS

We used a syngeneic rat (Lewis) orthotopic left lung transplantation model. In the control group (group I), donor lungs were flushed and preserved in Perfadex for 18 hours at 4 degrees C, then transplanted and reperfused for 2 hours. Group II donor lungs were perfused with and stored in Perfadex +25mol/L AB192 (bis(4-acetamidophenyl) 1-(S)-prolylpyrrolidine-2(R,S)-phosphonate), a small molecular weight DPP IV inhibitor. After 2-hour reperfusion, we measured blood gas, peak airway pressure, and thiobarbituric acid reactive substances.

RESULTS

Grafts from group II versus group I showed a significantly increased oxygenation capacity (II: 298.4 +/- 87.6 mm Hg vs 120.9 +/- 48.0, P < .01), lower peak airway pressure (11.8 +/- 0.9 mm Hg vs 16.0 +/- 1.4, P < .01), and less lipid peroxidation (9.3 +/- 2.0 micromol/L vs 13.8 +/- 1.8, P < .01).

CONCLUSION

Inhibition of intragraft DPP IV enzymatic activity significantly reduced ischemia/reperfusion-associated pulmonary injury, allowing for successful transplantation after 18 hours of ischemia.

CD26/Dipeptidylpeptidase IV–targeted Therapy of Acute Lung Rejection in Rats

BACKGROUND

CD26 is a T-cell co-stimulator, and interacts with adenosine deaminase, human immunodeficiency virus (HIV) Tat-1 protein and extracellular matrix. It possesses dipeptidylpeptidase IV (DPP IV) catalytic activity, which is linked to its co-stimulatory efficacy. We investigated the effect of specific DPP IV systemic activity inhibition on acute pulmonary rejection.

METHODS

Rat single-lung transplantation (Tx) was performed (LBNF1/LEW donor/recipient) in two groups (n = 12). Group I (n = 6) received daily treatment with a Pro-Pro-diphenylphosphonate derivative (AB197), and Group II served as an untreated control. At Day 5 post-Tx, ventilatory parameters, cytotoxicity and mixed lymphocyte reaction were analyzed and staining for ISHLT rejection grade and proliferating cell nuclear antigen (PCNA) was performed.

RESULTS

Treatment with AB192 abrogated acute rejection and preserved pulmonary function up to Day 5 post-Tx for PO2 (Group II: 24.9 +/- 6.9 mm Hg; Group I: 149.5 +/- 24.3 mm Hg; p < 0.001), PCO2 (Group II: 53.3 +/- 13.6 mm Hg; Group I: 39.0 +/- 9.8 mm Hg; p < 0.05) and peak airway pressure (Group II: 50.7 +/- 17.2 mm Hg; Group I: 20.2 +/- 10.0 mm Hg; p < 0.01). Controls showed moderate/severe rejection (ISHLT Grade A2 or 3), grafts from inhibited hosts revealed no/mild rejection (Grade A0 to 2: Group II: 2.8 +/- 0.3; Group I: 1.25 +/- 1.0; p < 0.005). Proliferating cell nuclear antigen (PCNA) staining of rejection-associated cellular infiltrates showed a significant reduction in positivity in perivascular infiltrates (34 +/- 11.5%; p < 0.05) and bronchial surface epithelium (31.7 +/- 10.6%; p < 0.05) in Group I vs Group II (55.9 +/- 8.4% and 57.2 +/- 4.5%).

CONCLUSIONS

Irreversible enzymatic inhibition of DPP IV has been shown to abrogate acute pulmonary rejection, maintain pulmonary function, and preserve histomorphologic architecture. These results extend earlier findings and illustrate the role of CD26/DPP IV in alloantigen-mediated immune responses.

Lung-Volume Reduction Surgery as an Alternative or Bridging Procedure to Lung Transplantation

BACKGROUND

In this study, we prospectively analyzed the functional outcome and the survival after lung-volume reduction surgery (LVRS) in patients with end-stage emphysema who were initially potential candidates for lung transplantation (LTX), and investigated the impact of LVRS on posttransplant course in patients who underwent LTX after LVRS.

METHODS

Of the 216 patients who underwent LVRS between 1994 and 2005, 58 were potential candidates for LTX at the time of LVRS (age 65 years or younger, forced expiratory volume in 1 second 25% of predicted or less; LVRS/LTX group). Lung-volume reduction surgery was performed by means of video-assisted, bilateral stapled resection of target areas. During the same period, 31 patients underwent primary LTX for end-stage emphysema (LTX group). Spirometry, plethysmography, carbon monoxide diffusing capacity, 6-minute walking distance, and dyspnea score were assessed preoperatively and at predetermined times after operation. Survival analysis was performed by use of the Kaplan-Meier method.

RESULTS

All the functional variables significantly improved after LVRS and peaked within the first year. Subjective improvement was observed for up to 5 years after LVRS, and 53% (31 of 58) of the patients were still alive and had not undergone transplantation after a median follow-up of 44 months. Fourteen percent (8 of 58) of the patients underwent secondary LTX because of progressive worsening of the respiratory function after a median bridging time between LVRS and LTX of 33 months. Postoperative recovery after transplantation and median survival time were comparable between the 8 patients of the LVRS/LTX group and the 31 patients of the LTX group (96.5 months versus 118.5 months, p = 0.9).

CONCLUSIONS

Lung-volume reduction surgery can significantly improve symptoms and lung function in selected patients who are initially potential candidates for LTX. Lung-volume reduction surgery can allow the postponement of LTX for up to 4 to 5 years and does not impair the chances for a subsequent successful LTX.

Sildenafil extends survival and graft function in a large animal lung transplantation model☆

OBJECTIVE

Restoring intracellular cGMP and inducing NO-synthesis attenuates ischemia-associated early pulmonary allograft dysfunction. Phosphodiesterase-5 (PDE), predominantly expressed in lung tissue, plays a pivotal role in modulating the cGMP/NO-synthase pathway in endothelial and epithelial cells. In this study, we evaluate the effect of employing sildenafil (Viagra), a specific inhibitor of PDE-5, to counteract ischemia/reperfusion (I/R) injury in a single lung transplantation model of extended ischemia.

METHODS

Donor animals (weight matched outbred pigs, 28-35 kg) in the treatment group (I) (n=5) were injected with 0.7 mg sildenafil/kg into the pulmonary artery (PA) prior to inflow occlusion. For perfusion, Perfadex, containing 0.7 mg sildenafil/l was used, and the graft stored at 1 degrees C in the perfusion solution. After 24h ischemia, unilateral left lung transplantation was performed. Starting at reperfusion, group I received continuous sildenafil (0.7 mg sildenafil/kg), over 6h. Except for the sildenafil application, the control group (II) (n=4) was treated identically (PGE1 was injected into the PA). One hour after reperfusion, the right main bronchus (MB) and right PA were occluded. Over the next 5h, cardiopulmonary parameters (systemic atrial, PA, central venous, left atrial pressure, pCO(2), pO(2)) were measured, including extravascular lung water (EVLW). Thiobarbituric acid-reactive substance assay (TBARS) and myeloperoxidase (MPO) analysis from lung tissue were run.

RESULTS

All recipients of group I survived the 6-h reperfusion period; in contrast, all control animals died within 1-2h after occlusion of the right side. In comparison to a marked rise in pulmonary vascular resistance (PVR) in group II (>1000 dynescm(-5)), PVR in group I remained stable, moderately elevated from baseline (baseline: 150-180 dynescm(-5) vs endpoint: 1000 dynescm(-5)). EVLW in group I did not increase during reperfusion (baseline: 6.75+/-1.4 mg/kg vs endpoint: 6.7+/-1.0mg/kg), in contrast to group II, where pulmonary edema at 2-h reperfusion preceded terminal graft failure (group I: 9.7+/-0.1mg/kg vs group II: 6.48+/-1.8 mg/kg). Tissue reactive free radicals at endpoint measurement in group I did not differ significantly from native tissue. Yet, when compared to specimen taken from group II at time of terminal graft failure, a significant increase in free radicals was noted (group I: 13.8+/-1.6 pmol/g vs group II: 18.5+/-3.0 pmol/g, p<0.05).

CONCLUSION

Sildenafil treatment prevents terminal early graft failure, allowing lung transplantation after 24-h ischemia time. Reperfusion edema was strikingly diminished, preserving pulmonary structural and functional integrity while prolonging graft ischemia time. Employing the established PDE-5 inhibitor sildenafil during lung perfusion, storage, and implantation, ischemic tolerance may be extended and early graft function improved.

Surgery for non-localized bronchiectasis

Background

Resection for localized bronchiectasis is a well established therapy. However, there is little information on the role of surgery in non-localized bronchiectasis.

Methods

Between January 1992 and April 2001, 55 patients without cystic fibrosis underwent resection. Forty-eight patients (mean age 45 (range 23–74) years; 32 women) were available for long-term follow-up. Twenty-five patients underwent resection for localized disease (group 1) and 23 had bronchiectasis in at least two different lobes (group 2).

Results

Thirty-one of the 48 patients were treated by Video Assisted Thoracoscopic Surgery (VATS) resection. There was no 30-day mortality. Mean duration of hospital stay was 10·9 (range 6–31) days in group 1 and 11·1 (range 5–19) days in group 2. Three of 25 patients in group 1 required reoperation. Only minor complications occurred in group 2 (three patients). Mean follow-up for both groups was 37 (range 6–97) months. Twenty-three of 25 patients in group 1 and 16 of 23 in group 2 reported satisfaction at 6 months after the operation. Recurrent infection was noted in three patients in each group. Haemoptysis recurred in only one patient in group 2.

Conclusion

The surgical treatment of selected patients with non-localized bronchiectasis was safe and most patients were satisfied with the outcome.

Catamenial pneumothorax revisited: Clinical approach and systematic review of the literature

BACKGROUND

Catamenial pneumothorax is a rare entity of spontaneous, recurring pneumothorax in women. It has been associated with thoracic endometriosis, yet varying clinical courses and the lack of consistent intraoperative findings have led to conflicting etiologic theories.

METHODS

We discuss etiology, clinical course, and surgical treatment of 3 women with catamenial pneumothorax. In addition, the world literature since the first description is reviewed.

RESULTS

Three women (31, 32, and 39 years old) had recurrent, menses-associated, right-sided spontaneous pneumothoraces. They had undergone video-assisted thoracoscopic surgery previously, with various unsuccessful procedures. Finally, with video-assisted thoracoscopic surgery multiple small perforations in the tendinous part of the right diaphragm with adjacent endometrial implants were detected. After plication of the involved area, 2 patients have been free of recurrence for 22 and 13 months, respectively. Laparoscopic evaluation in 1 woman with a further recurrence revealed asymptomatic pelvic endometriosis. This patient has been free of recurrence since initiation of luteinizing hormone-releasing hormone analog therapy for 17 months. In a review of 229 cases of catamenial pneumothorax in the literature, adequate information was given for 195 patients (85.2%). One hundred fifty-four (79%) were treated surgically, with detailed findings reported for 140 (91%). Thoracic endometriosis was diagnosed in 73 patients (52.1%), and 54 (38.8%) showed diaphragmatic lesions. Pleurodesis, with or without diaphragmatic repair or wedge resection, was performed in 81.7% of the cases.

CONCLUSIONS

Catamenial pneumothorax may be suspected in ovulating women with spontaneous pneumothorax, even in the absence of symptoms associated with pelvic endometriosis. During video-assisted thoracoscopic surgery, inspection of the diaphragmatic surface is paramount. Plication of the involved area alone can be successful. In complicated cases, hormonal suppression therapy is a helpful adjunct.

Melatonin in vivo prolongs cardiac allograft survival in rats

Melatonin, secreted by the pineal gland, is a multifunctional agent which (i) protects tissues from damage through free radical scavenging and attenuates ischemia/reperfusion injury in organ grafts; (ii) acts synergistically with cellular antioxidants; and (iii) displays complex, dose-dependent immunoenhancing and suppressing effects in vitro and in vivo. We analyzed the immunomodulatory effect of melatonin on acute allograft rejection. Cardiac grafts were transplanted from LBNF1 to LEW rats and anastomosed to the abdominal great vessels. The effect of low-dose (LD; 20 mg/kg/day) and high-dose (HD; 200 mg/kg/day) melatonin treatment in recipients compared with untreated controls was investigated. HD melatonin therapy abrogated acute rejection, significantly prolonging allograft survival (mean survival: 12.3 +/- 1 days S.D., n = 8, P < 0.0001) compared with untreated controls, which rapidly reject the transplant (6.3 +/- 1 days n = 12). LD therapy did not extend survival significantly (7.3 +/- 1.1 days, n = 12). Allospecific IgM showed a significant decrease in animals receiving HD therapy versus untreated recipients at days 10 and 14 post-transplantation (P < 0.01), whereas in the LD group at day 10, a significant increase in allospecific IgM (P < 0.01) over the HD cohort was demonstrated. HD treatment markedly reduced lymphocyte proliferative capacity compared with controls and the LD group. HD melatonin treatment abrogated acute allograft rejection and significantly prolonged graft survival. Our results suggest an involvement of melatonin in humoral and cellular immune pathways following perfused organ transplantation. These findings may indicate a novel therapeutic approach, based on modulation of the neuroendocrine/immune axis through melatonin as a possible future immunosuppressant in organ transplantation.

Tissue engineered cartilage generated from human trachea using DegraPol scaffold

OBJECTIVE

To date numerous attempts have been undertaken to conquer the challenging problem of reconstructing long segmental tracheal defects, as yet without lasting success. Recently, employing concepts of tissue engineering in animals, cartilage-like constructs were transplanted in vivo. However, both the feasibility of fabricating tracheal replacements and the use of human tracheal chondrocytes (HTC) for tissue engineering are still under investigation. In this study, we optimized isolation and cultivation techniques for human tracheal cartilage, assessing the feasibility of seeding these cells onto a novel, three-dimensional (3-D) polyester-urethane polymer (DegraPol).

METHODS

Human tracheal cartilage was harvested from the trachea of lung donors, digested in 0.3% collagenase II, and the condrocytes serially passaged every 7-9 days. Cells were also cultivated over agar plate during the total 6-8 weeks expansion phase. Thereafter, chondrocytes were seeded onto DegraPol (pore sizes 150-200 microm) with a seeding density of 2.4 x 10(7)/ml, and chondrocyte-polymer constructs maintained during in vitro static culture.

RESULTS

HTC displayed stable proliferation kinetics in monolayer culture with positive expression of collagen type II. Following polymer seeding, both cellular proliferation and extracellular matrix (ECM) production, as measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and glycosaminoglycan assays, continued over extended culture. Active growth of HTC on DegraPol was further demonstrated by Alcian blue staining, with the histomorphological appearance of the construct resembling that of native cartilage. Scanning electron microscopy showed chondrocyte growth and ECM synthesis both on the surface and inside the porous scaffold, with a dense cell layer on the surface of the scaffold and a lower cell distribution in the scaffold's interior.

CONCLUSIONS

The harvested chondrocytes from human trachea cartilage expand well in vitro and possess the ability to form new cartilage-like tissue when seeded onto DegraPol matrix. However, improved culture conditions are needed to permit cellular growth throughout cell-polymer constructs.

CD26/DPP IV in experimental and clinical organ transplantation

The T-cell activation-Ag CD26 possesses dipeptidyl peptidase IV (DPP IV) enzymatic activity. Costimulatory efficacy and immunocompetence are associated with the enzymatic activity.

GOALS

In models of experimental cardiac allograft transplantation (HTx), we analyzed the role of CD26/DPP IV during organ rejection. Also, we investigated CD26 enzymatic and cellular expression in human recipients of kidney transplants (Tx).

MATERIAL AND METHODS

Heterotopic HTx in rats, models of acute and accelerated rejection. Monitoring of DPP IV serum levels and humoral immunity. Propro-diphenyl phosphonate was employed to inhibit DPP IV activity during rejection. In a prospective study, surface expression of CD26, 3, 4, 8, 45, 122 and ADA on PBL and DPP IV serum activity were measured in kidney recipients for 24 months post-transplantation.

RESULTS

Acute rejection was . associated with increased serum DPP IV activity (p < 0.005). Specific inhibition abrogated acute (p < 0.0001) and accelerated (p < 0.01) rejection, impairing cytotoxicity and allospecific Ig-synthesis. Kidney recipients displayed a significant drop in CD26 expression on PBL for up to 18 months postoperatively (p < 0.001). CD4, 8, 45, 122 and ADA expression kinetics were only briefly affected. DPP IV enzymic activity stayed depressed for at least 12 months (p < 0.001).

CONCLUSION

CD26/DPP IV is pivotal in T-cell mediated immune responses toward allo-Ag. In clinical transplantation, engraftment/immunosuppression are reflected by CD26 cellular and enzymatic expression posttransplantation and may serve as an indicator for immunomodulation.

The influence of the rapamycin-derivate SDZ RAD on the healing of airway anastomoses

OBJECTIVE

Among the many immunosuppressive effects of SDZ RAD (40-0(2-hydroxyethyl)-rapamycin), a rapamycin derivative, is the inhibition of fibroblast proliferation. Since the long-term success of lung transplantation is limited by the development of bronchiolitis obliterans, a fibroblast-associated progressive luminal obstruction of the terminal bronchioli, the use of SDZ RAD as immunosuppressive in pulmonary graft recipients may counteract this process. However, reduction of fibroblast activity, posttransplant, may impair the healing of the bronchial anastomoses.

MATERIALS AND METHODS

The cervical trachea in pigs was denuded, divided and re-anastomosed with Prolene 4-0 single stitches. Control animals (group 1, n=4) were without, and study animals (group 2, n=6) were with SDZ RAD therapy (1.25 mg/kg/day, p.o., 14 days). After 14 days, the pigs were sacrificed. The anastomoses were examined histologically, and breaking strength of tracheal strips of 5-mm width was measured.

RESULTS

All animals survived without complications. Serum levels of SDZ RAD were 30.9+/-8.7 ng/ml (recommended level 20-40 ng/ml). All anastomoses healed macroscopically without difference between the two groups. Breaking strength was significantly lower in the treated animals (group 1 vs. group 2: 11.75+/-0.35 vs. 7.69+/-1.39 N, P=0.01). Histology did not show a significant change in histoarchitecture between the groups.

CONCLUSIONS

Although SDZ RAD significantly reduced the breaking strength of the tracheal anastomosis, no obvious histological differences between treated and untreated animals could be detected. Since this model does not reflect the clinical situation, further investigations are necessary to reveal the effect of SDZ RAD on airway wound healing in concert with a contemporary clinically used multidrug immunosuppressive regimen in allograft recipients.

Staging of non-small-cell lung cancer with integrated positron-emission tomography and computed tomography

BACKGROUND

We compared the diagnostic accuracy of integrated positron-emission tomography (PET) and computed tomography (CT) with that of CT alone, that of PET alone, and that of conventional visual correlation of PET and CT in determining the stage of disease in non-small-cell lung cancer.

METHODS

In a prospective study, integrated PET-CT was performed in 50 patients with proven or suspected non-small-cell lung cancer. CT and PET alone, visually correlated PET and CT, and integrated PET-CT were evaluated separately, and a tumor-node-metastasis (TNM) stage was assigned on the basis of image analysis. Nodal stations were identified according to the mapping system of the American Thoracic Society. The standard of reference was histopathological assessment of tumor stage and node stage. Extrathoracic metastases were confirmed histopathologically or by at least one other imaging method. A paired sign test was used to compare integrated PET-CT with the other imaging methods.

RESULTS

Integrated PET-CT provided additional information in 20 of 49 patients (41 percent), beyond that provided by conventional visual correlation of PET and CT. Integrated PET-CT had better diagnostic accuracy than the other imaging methods. Tumor staging was significantly more accurate with integrated PET-CT than with CT alone (P=0.001), PET alone (P<0.001), or visual correlation of PET and CT (P=0.013); node staging was also significantly more accurate with integrated PET-CT than with PET alone (P=0.013). In metastasis staging, integrated PET-CT increased the diagnostic certainty in two of eight patients.

CONCLUSIONS

Integrated PET-CT improves the diagnostic accuracy of the staging of non-small-cell lung cancer.

Prevention of recurrent empyema after pneumonectomy for chronic infection

OBJECTIVES

Pneumonectomy in chronic pulmonary infection with empyema is associated with a high mortality rate and an increased risk of recurrent empyema. The surgical resection is technically demanding, and successful management continues to be a challenge.

METHODS

We evaluated a concept which combines (pleuro-)pneumonectomy or completion pneumonectomy with surgical debridement of the pleural cavity and packing with povidine-iodine soaked dressings. The debridement and packing is repeated in the operating theater after 48 h until the chest cavity is macroscopically clean. Finally, the pleural space is obliterated with antibiotic solution.

RESULTS

Between February 1997 and October 2000, 11 patients (average age of 59 years, ranging from 25 to 84) with destroyed lung caused by tuberculosis (six), aspergilloma (two), bronchiectasis (one), esophago-pleural fistula (one) or broncho-pleural fistula after lobectomy for bronchial carcinoma (one) and ongoing chronic infection with acute empyema (ten) (25-2500 days between first and definitive therapy) were treated. Pleural culture findings showed Aspergillus in four, Mycobacterium in two, Enterococcus in two, Candida in one and Staphylococcus in one, respectively. The mean number of interventions was 2.9 (2-4). The chest was definitively closed in all patients within 1 week. The mean hospitalization time was 19 days (9-31 days). In the follow-up (10-54 months), there was no recurrence of empyema. One patient (84 years) died at day 31, due to sepsis.

CONCLUSIONS

Pneumonectomy combined with repeated surgical debridement and antimicrobial therapy enables the successful treatment of chronic pulmonary infection with empyema within a short time period.

Accelerated treatment for early and late postpneumonectomy empyema

BACKGROUND

Postpneumonectomy empyema is a rare but serious complication of pneumonectomy. Despite use of various therapeutic approaches and techniques during the last five decades, successful therapy remains difficult and is often associated with high morbidity and prolonged hospitalization.

METHODS

We evaluated a concept for accelerated treatment, which consists of radical debridement of the pleural cavity and packing with wet dressings of povidoneiodine. This was repeated in the operating theater every second day, until the chest cavity was macroscopically clean. If present, bronchial stump insufficiency was closed and secured by omentopexy. Finally, the pleural space was obliterated with antibiotic solution.

RESULTS

Twenty patients, 13 with early postpneumonectomy empyema (10 to 89 days; mean, 37 days) and 7 with late postpneumonectomy empyema (124 to 7,200 days; mean, 1,126 days) were treated. Fifteen patients presented with bronchopleural fistula (11 right, 4 left), which developed after chemotherapy (n = 6) or after radiotherapy (n = 3) (unknown cause in 4 patients). Six patients were referred after previously unsuccessful surgical attempts. Pleural cultures were positive in 17 cases for one or several bacteria including fungoides (n = 2). The average number of interventions was 3.5 (3 to 5). The chest was definitively closed in all patients within 8 days. Mean hospitalization time was 17 days (7 to 35 days). During the same hospitalization, 2 patients needed reoperation because of an undetected bronchopleural fistula. Postpneumonectomy empyema was successfully treated in all patients. There was no in-hospital or 3-month postoperative mortality.

CONCLUSIONS

Repeated surgical debridement combined with closure of bronchopleural fistula and antimicrobial therapy enables successful treatment of early and late postpneumonectomy empyema within a short period and is a well-tolerated concept.

Evidence against a pivotal role of preformed antibodies in delayed rejection of a guinea pig-to-rat heart xenograft

INTRODUCTION

Whereas the involvement of elicited xenoantibodies in delayed xenograft rejection is currently being substantiated, this study focuses on the role of the preformed fraction of xenoantibodies.

METHODS

To check the influence of the latter, we combined pretransplant complement inactivation (cobra venom factor) and antibody reduction (plasmapheresis) in a guinea pig-to-rat heart transplant model.

RESULTS

Antibody reduction on plasmapheresis before xenografting did not prolong delayed xenorejection in decomplemented rats, although the immunohistologic pattern lacked the immunoglobulin deposits along endothelial walls found in xenografts of merely decomplemented recipients. Astonishingly, plasmapheresis, if carried out 2 days before transplantation, almost tripled xenograft survival, although preformed antibody levels were completely restored and even rebounding at the time of grafting. The pattern and number of infiltrating cells did not differ in dependence of the timing of plasmapheresis nor did the proliferative response of lymphocytes in the mixed lymphocyte reaction differ. However, plasmapheresis led to a retarded decrease of the mononuclear cell tumor necrosis factor alpha secretory potential, which correlated well with a diminished immunohistologic staining of tumor necrosis factor alpha secreted by graft-infiltrating mononuclear cells.

CONCLUSION

These findings argue against a pivotal role of preformed xenoantibodies in the pathomechanistic process of delayed xenograft rejection and challenge the therapeutic strategy to reduce preformed xenoantibody levels before xenotransplantation in complement-inactivated recipients.

CD26, let it cut or cut it down

The costimulatory properties of CD26 have been studied extensively and significant progress has been made in unravelling the complex nature of this molecule. Here, we summarize recent findings on molecular and functional characteristics of CD26. We argue that a multidisciplinary approach might reveal the molecular events underlying the role of CD26 in HIV infection and immune, inflammatory and endocrine responses.

Blockade of very late antigen-4 integrin binding to fibronectin in allograft recipients. II. Treatment with connecting segment-1 peptides prevents chronic rejection by attenuating arteriosclerotic development and suppressing intragraft T cell and macrophage activation

BACKGROUND

Chronic rejection remains the leading obstacle to long-term allograft survival. We have shown that treatment of sensitized rats with rapamycin (RPM) does not prevent progressive chronic-type cardiac allograft failure. Having documented the role of fibronectin (FN) in the allograft rejection cascade, we hypothesized that treatment with synthetic peptides that specifically block adhesive interactions between the connecting segment-1 (CS1)-binding domain of FN and alpha4beta1 integrin on circulating cells may prevent the development of chronic rejection in transplant recipients.

METHODS AND RESULTS

Lewis rats were sensitized with Brown Norway skin grafts (day -7), followed by transplantation of LBNF1 hearts (day 0). Experimental animals were treated with RPM (day -7 to -1; 0.25 mg/kg/day i.p.), or RPM + CS1 peptides (day +7 to +13; 4 mg/kg/day i.v.), and euthanized at day 60. Unlike cardiac allografts in rats undergoing RPM monotherapy, those after adjunctive CS1 peptides had well preserved myocardial architecture and were free of arteriosclerotic lesions. Moreover, reverse transcription-polymerase chain reaction-based intragraft expression of transcripts for CD3, interferon-gamma, interleukin-12, monocyte chemoattractant protein-1, and transforming growth factor-beta were diminished in the CS1 group when compared with levels in the RPM group. The corresponding expression of cytokine proteins, as determined by immunoperoxidase labeling, was also depressed and correlated with decreased infiltration by T cells and macrophages.

CONCLUSION

CS1 peptide-facilitated blockage of alpha4beta1-FN interactions prevents the development of chronic rejection and depresses the expression of key T cell- and macrophage-associated cytokines/chemoattractants. Hence, local synthesis of FN is an ongoing feature of, and adhesive FN-alpha4beta1 associations are critical for, the development of chronic transplant rejection.

Blockade of very late antigen-4 integrin binding to fibronectin in allograft recipients: I. Treatment with connecting segment-1 peptides prevents acute rejection by suppressing intragraft mononuclear cell accumulation, endothelial activation, and cytokine expression

BACKGROUND

Allograft rejection is associated with infiltration of inflammatory cells and local deposition of fibronectin (FN). This study was carried out to examine the hypothesis that peptides known to specifically block adhesive interactions between the connecting segment-1 (CS1)-binding domain of FN and alpha4beta1 integrin on circulating cells may interfere with the immune cascade, which would lead to acute rejection in transplant recipients.

METHODS AND RESULTS

Cardiac allografts from Lewis x Brown Norway F1 hybrids were rejected in 7+/-1 days in Lewis rats. Treatment with bioactive CS1 peptides (4 mg/kg/day i.v. for 7 days) abrogated acute rejection and prolonged cardiac allograft survival to 13+/-1 days (P<0.001). This effect correlated with decreased expression of total fibronectin and cell adhesion molecules, such as alpha4beta1, vascular cell adhesion molecule-1, intercellular adhesion molecule-1, as well as reduced infiltration by CD4+ and CD8+ T cells at the graft site. Treatment with CS1 peptides decreased alloantigen activation, as evidenced by decreased intragraft infiltration by CD25+ cells, and diminished expression of mRNA coding for Th1 (interleukin [IL]-2, interferon-gamma)- and Th2 (IL-4, IL-5, IL-6)-type cytokines. CS1-mediated immunosuppressive effects could be reversed and acute rejection recreated after adjunctive treatment of rats with recombinant IL-2.

CONCLUSION

Our data are consistent with the model in which in vivo interaction between the alpha4beta1 integrin receptor and the cell-associated CS1 motif of FN is critical for rejection cascade. The novel therapeutic approach of selectively blocking the alpha4beta1-FN activation pathway with CS1 peptides prevents acute allograft rejection by inhibiting expansion of antigen-specific T cells and inducing a transient state of cytokine-responsive anergy in the residual T-cell population.