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.

An experimental approach toward chronic pulmonary allograft rejection: Orthotopic lung versus heterotopic tracheal segment transplantation in rats.

BACKGROUND: Despite the impact of chronic rejection (CR) on long-term outcomes, clinically relevant experimental models are sparse, often including a design of subcutaneous implantation of tracheal segments. However, this latter site lacks anatomic correlation, adequate perfusion, and ventilatory function. In this study, we compared the spatial and sequential course of CR in models of orthotopic single lung transplantation (LT) versus heterotopically implanted tracheal segments in rats. METHODS: We performed 30 orthotopic left single LTs from Fisher 344 (F344) to Wistar Kyoto (WKY) rats for comparison with the outcomes of 3 tracheal segments implanted subcutaneously in every recipient. As a control group, 3 syngeneic tracheal segments were implanted into 12 WKY rats. For histopathologic examinations, tracheal segments and pulmonary allografts were harvested between days 1 and 112 and between weeks 4 and 18, respectively. RESULTS: Allogeneic tracheal segments showed rapid fragmentation of the respiratory epithelium, with complete luminal occlusion by week 4, whereas the lumen in isografts remained unobstructed. In contrast, bronchioles from orthotopically transplanted lungs did not show epithelial changes before week 14. However, marked lymphocytic sequestration into bronchioles occurred by week 8 with sequential destruction of all layers of the small airways, with loss of respiratory epithelium by week 16. CONCLUSIONS: Based on the different histomorphologic dynamics of CR, direct comparison between those 2 models is limited. When investigating CR in future studies, initial findings based on tracheal implantation experiments should be expanded in the site of orthotopic pulmonary transplantation.

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.

Increased T-bet to GATA-3 ratio during acute allograft rejection in the rat lung.

Acute allograft rejection (AR) remains a major problem in solid organ transplantation. The pivotal mechanism hinges on alloantigen recognition by recipient T helper (T(h)) cells that differentiate into T(h)1 and T(h)2. This study investigated the association of mRNA levels of the transcription factors T-box expressed in T cells and GATA-binding protein 3 with the development of T(h)1/T(h)2-directed immune responses. We investigated the expression of T-bet and GATA-3 mRNA levels and the protein levels of their marker cytokines interleukin (IL)-2 and IL-4 in orthotopically transplanted rat lungs during AR. We observed a nonsignificant increase in T-bet expression following allografting at days 3 and 5 but there was a significant reduction in GATA-3 expression on day 5 compared with controls. The ratio of T-bet to GATA-3 expression showed a trend to increase at day 3 following allografting reaching significance at 5 days. These changes were associated with a significant increase in the expression of IL-2 over IL-4 on days 3 and 5. This study suggests that T(h)1 responses play a major role during AR in the rat lung, and that this differentiation can be monitored by measuring mRNA levels of T-bet and GATA-3.

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.

Ischemia/reperfusion injury: The role of CD26/dipeptidyl-peptidase-IV-inhibition in lung transplantation.

UNLABELLED: 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.

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.

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: 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.

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.