Inhibition of Vascular Endothelial Growth Factor Receptors 1 and 2 Attenuates Natural Killer Cell and Innate Immune Responses in an Experimental Model for Obliterative Bronchiolitis.

Obliterative bronchiolitis (OB) after lung transplantation is a nonreversible, life-threatening complication. Herein, the role of vascular endothelial growth factor receptor (Vegfr)-1 and -2 was investigated in the development of obliterative airway disease (OAD), an experimental model for OB. The nonimmunosuppressed recipients underwent transplantation with fully major histocompatibility complex mismatched heterotopic tracheal allografts and received Vegfr1 and -2-specific monoclonal antibodies either alone or in combination, or rat IgG as a control. The treatment with Vegfr1- or -2-blocking antibody significantly decreased intragraft mRNA expression of natural killer cell activation markers early after transplantation. This was followed by reduced infiltration of Cd11b+ cells and Cd4+ T cells as well as down-regulated mRNA expression of proinflammatory chemokines and profibrotic growth factors. However, blocking of both Vegfr1 and -2 was necessary to reduce luminal occlusion. Furthermore, concomitant inhibition of the calcineurin activation pathway almost totally abolished the development of OAD. This study proposes that blocking of Vegf receptors blunted natural killer cell and innate immune responses early after transplantation and attenuated the development of OAD. The results of this study suggest that further studies on the role of Vegfr1 and -2 blocking in development of obliterative airway lesions might be rewarding.

KIF15 missense variant is associated with the early onset of idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) has an unknown aetiology and limited treatment options. A recent meta-analysis identified three novel causal variants in the TERT, SPDL1, and KIF15 genes. This observational study aimed to investigate whether the aforementioned variants cause clinical phenotypes in a well-characterised IPF cohort. METHODS: The study consisted of 138 patients with IPF who were diagnosed and treated at the Helsinki University Hospital and genotyped in the FinnGen FinnIPF study. Data on > 25 clinical parameters were collected by two pulmonologists who were blinded to the genetic data for patients with TERT loss of function and missense variants, SPDL1 and KIF15 missense variants, and a MUC5B variant commonly present in patients with IPF, or no variants were separately analysed. RESULTS: The KIF15 missense variant is associated with the early onset of the disease, leading to progression to early-age transplantation or death. In patients with the KIF15 variant, the median age at diagnosis was 54.0 years (36.5-69.5 years) compared with 72.0 years (65.8-75.3 years) in the other patients (P = 0.023). The proportion of KIF15 variant carriers was 9- or 3.6-fold higher in patients aged < 55 or 65 years, respectively. The variants for TERT and MUC5B had similar effects on the patient's clinical course, as previously described. No distinct phenotypes were observed in patients with the SPDL1 variant. CONCLUSIONS: Our study indicated the potential of KIF15 to be used in the genetic diagnostics of IPF. Further studies are needed to elucidate the biological mechanisms of KIF15 in IPF.

Neutrophil gelatinase-associated lipocalin associated with irreversibility of pre-liver transplant kidney dysfunction.

Kidney outcomes in early post-liver transplantation (LT) are crucial for long-term prognosis, but difficult to predict. Among 203 adult LT patients, we studied the value of plasma neutrophil gelatinase-associated lipocalin (NGAL) measured pre-LT for predicting acute kidney injury (AKI), kidney-replacement therapy within three months, and kidney dysfunction at three months post-LT. Glomerular filtration rate (GFR) was estimated by creatinine-based and cystatin C-based equations. Highest NGAL levels were among patients on pre-LT kidney-replacement therapy, whereas NGAL exceeded 200 µg/L in only three (2%) patients with pre-LT GFR >60 mL/min. Pre-LT NGAL >260 µg/L predicted GFR <60 mL/min at three months post-LT (OR 17.8, 95% CI 2.1-153) independently of 19 other variables reflecting recipient characteristics, liver and kidney function, perioperative hemodynamic stress, and immunosuppression. Of 81 patients with pre-LT GFR <60 mL/min, 48% had GFR <60 mL/min at three months, and an NGAL level >260 µg/L predicted this outcome with 90% specificity and 46% sensitivity. NGAL failed to predict post-LT AKI or need for temporary kidney-replacement therapy. In conclusion, NGAL independently predicted irreversibility of pre-LT kidney dysfunction and could thus help in optimizing patient care and in the decision to perform combined liver-kidney transplantation. Pre-LT NGAL was not useful in patients with preserved pre-LT kidney function or in predicting post-LT AKI.

Serum neutrophil gelatinase-associated lipocalin and recovery of kidney graft function after transplantation.

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) is a marker for acute kidney injury. We studied whether serum NGAL predicts delayed graft function (DGF) and recovery of kidney function after transplantation. METHODS: Serum NGAL was analyzed using commercial ELISA and point-of-care (POC) (Triage®, Biosite) methods. Serum samples were collected from 176 consecutive, deceased-donor kidney recipients just before transplant surgery and on day 1 and 14 after transplantation. The first 132 samples were analyzed with both methods and the remaining samples with the POC method. RESULTS: The correlation between the ELISA and POC methods was 0.89, p < 0.0001 and hence the POC method was used for the remaining analyses. DGF was seen in 66/176 patients. Day 1 sNGAL was significantly higher in DGF (588 ng/ml, SD 189.6) compared to early graft function (355 ng/ml, SD 166.2, p < 0.0001) and this difference persisted on day 14. Day 1 sNGAL predicted DGF with an area under the curve (AUC) of 0.853 (CI 0.792-0.914, p < 0.0001). At the optimal cutoff level of 423 ng/ml the sensitivity was 87% and the specificity 77%. In a multivariate analysis, day 1 sNGAL emerged as an independent predictor of DGF. The sNGAL also predicted DGF lasting longer than 14 days with an AUC of 0.825 (CI 0.751-0.899, p < 0.0001). At the optimal cutoff level of 486 ng/ml, the sensitivity was 80% and specificity 75%. CONCLUSION: Serum NGAL predicts clinically significant DGF and is useful in the care of kidney transplant recipients.

NGAL-Siderocalin in kidney disease.

Kidney damage induces the expression of a myriad of proteins in the serum and in the urine. The function of these proteins in the sequence of damage and repair is now being studied in genetic models and by novel imaging techniques. One of the most intensely expressed proteins is lipocalin2, also called NGAL or Siderocalin. While this protein has been best studied by clinical scientists, only a few labs study its underlying metabolism and function in tissue damage. Structure-function studies, imaging studies and clinical studies have revealed that NGAL-Siderocalin is an endogenous antimicrobial with iron scavenging activity. This review discusses the "iron problem" of kidney damage, the tight linkage between kidney damage and NGAL-Siderocalin expression and the potential roles that NGAL-Siderocalin may serve in the defense of the urogenital system. This article is part of a Special Issue entitled: Cell Biology of Metals.

Virtual communication is commonly used in Finnish interstitial lung disease multidisciplinary meetings.

Multidisciplinary meeting (MDM) is a core element in the diagnosis of interstitial lung diseases (ILD). The aim of the study was to investigate the implementation and key elements related to ILD MDMs in Finnish specialized care, which is characterized by long travel distances and a large number of small centers treating patients suffering from ILDs. An electronic questionnaire was sent to ILD experts working at five academic centers of Finland regarding the implementation of ILD MDMs with the focus on utilization of virtual communication. Responses were received from all academic centers of Finland (n = 5) whose catchment areas cover all of Finland. ILD MDMs were organized in each center approximately every two weeks and the core participants included a radiologist, respiratory physicians, junior staff, pathologist and a rheumatologist. All non-academic centers could refer their patients to be evaluated in ILD MDM of an academic center. Virtual communication was utilized by all academic centers in the implementation of ILD MDMs, being most common among small centers located in Eastern and Northern Finland. Virtual access to ILD MDM of an academic center was available in most parts of Finland, enabling small centers to benefit from the ILD expertise of academic centers.

I-PreFer Study: A Discrete Choice Experiment to Explore Patient, Caregiver and Pulmonologist Preferences of Idiopathic Pulmonary Fibrosis Pharmacological Treatment Options.

Purpose: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and ultimately fatal lung disease that, while rare, has seen incidence rise over time. There is no cure for IPF other than a lung transplant, though two antifibrotic (AF) drugs do exist to slow disease progression. While these drugs are efficacious, they are both associated with differing profiles of adverse events. This study aimed to elicit patient, caregiver and pulmonologist preferences on the treatment profiles of AFs via a discrete choice experiment (DCE). Patients and Methods: The DCE and associated survey were distributed across 7 European countries, and bespoke DCEs were developed for patients/caregivers and pulmonologists. After collaboration with European Pulmonary Fibrosis & Related Disorders Federation (EU-PFF) and expert pulmonologists, respectively, a patient/caregiver DCE with 5 attributes and a pulmonologist DCE with 6 attributes were finalized. The DCEs had a blocked approach to reduce participant burden and were distributed on an online survey platform. Preferences were estimated through conditional multinomial logit regression analysis. Results: Ninety-five patients, 22 caregivers and 115 pulmonologists fully completed their respective DCEs. Overall, patients and caregivers preferred management of treatment-related adverse events over both survival benefits and disease progression. Nearly all preference levels were found to be significantly different from their reference level. In contrast, pulmonologists showed a greater preference for control of lung function and exacerbations over adverse events. Although there were relative differences between the univariate subgroups in terms of the preference weights, most of these were not statistically significant. Conclusion: The outcomes from this study suggest that while patients and caregivers had similar preferences for characteristics of IPF treatments, pulmonologists did not share those same preferences. Patients and caregivers preferred safety, while pulmonologists preferred efficacy. These differences should be considered by clinicians to better involve the patient in treatment decision-making for IPF.

I-PreFer Study: A Questionnaire to Explore Patient, Caregiver and Pulmonologist Preferences of Idiopathic Pulmonary Fibrosis Treatment Options.

Introduction: Idiopathic Pulmonary Fibrosis (IPF) is a rare disease that causes shortness of breath, dry cough, and tiredness. While there is no cure for IPF, current therapeutic treatments aim to slow lung degeneration while managing side effects. There is little known about patient experience and attitude with regards to their disease and medication. Purpose: To understand the perceptions, behaviors and drivers of treatment decision-making among patients, caregivers and pulmonologists in IPF. Patients and Methods: Online surveys to patients with IPF, caregivers and pulmonologists were developed and administered in Belgium, Finland, France, Greece (pulmonologists only), the Netherlands, Ireland and the United Kingdom between November 2021 and January 2022. Results: A total of 111 patients, 22 caregivers and 140 pulmonologists participated. Half (47%) of patients rated their disease as "severe", while pulmonologists reported that a quarter of their patients had a low Forced Vital Capacity (FVC) (below 50% of the predicted value). Between 21% and 42% of the patients do not take an IPF medication (patients' perception) or antifibrotic (physicians' perception). Pulmonologists reported that a total of 58% of their patients were receiving antifibrotic medication, any IPF medication, while around 53%, 55%, 35% and 73% of the patients limited their exposure (sometimes or often) to the sun due to IPF, considered taking medication against diarrhea, nausea/vomiting and heartburn, respectively. Treatment adherence was relatively high (81%), in line with the caregivers' view and the pulmonologists' expectations. Overall, cultural, clinical or socio-demographic factors impacted patients' perceptions or behaviors. Conclusion: This study shows there is a significant proportion of IPF patients who remain untreated, a misalignment of disease severity between patients and their physicians and patient background impacts behavior. Overall, more in-depth patient-physician communication is needed to improve treatment experience.

Dyspnea Associates With a Widely Impaired Quality of Life in Idiopathic Pulmonary Fibrosis Patients: A Longitudinal Study Using 15D.

Background: Research on health-related quality of life (HRQoL) is crucial for developing comprehensive palliative care in idiopathic pulmonary fibrosis (IPF). Objectives: To study IPF patients' HRQoL compared with general population and its association with dyspnea in a longitudinal follow-up. Design: Assessment of IPF patients' HRQoL by a generic tool. Comparison of baseline data with the general population and a 30-month follow-up with 6 months intervals. Setting/Subjects: In total, 246 IPF patients were recruited from the Finnish nationwide real-life study, FinnishIPF. Measurements: Modified Medical Research Council (MMRC) dyspnea scale for dyspnea and the generic HRQoL tool 15D for the total and dimensional HRQoL were used. Results: At baseline, the mean 15D total score was lower (0.786, standard deviation [SD] 0.116) in IPF patients than in the general population (0.871, SD 0.043) (p < 0.001) and among the IPF patients with MMRC ≥2 compared with those with MMRC <2 (p < 0.001). In patients with MMRC ≥2, significant impairment compared with general population existed in 11 dimensions of HRQoL, such as breathing, usual activities, and sexual activity, whereas this was true in only 4 dimensions in MMRC <2 category. Mental function was not impaired in either group. During the follow-up, 15D total score decreased in both MMRC categories (p < 0.001) but stayed constantly worse in the MMRC ≥2 group. Seven and two dimensions of HRQoL significantly declined in the categories of MMRC <2 and MMRC ≥2, respectively. Conclusions: Patients with IPF, especially if dyspnea limits everyday life, suffer from widely impaired HRQoL, although self-assessed mental capability is preserved. Integrated palliative care is supported to face the multiple needs of IPF patients.

Migraine may disturb sleep perception during sleep onset: a retrospective data analysis.

STUDY OBJECTIVES: As sleep latency is an important factor in the diagnosis of many disorders, it is important to know whether the patient's self-reported evaluation of sleep latency corresponds with an objectively measured evaluation. Some studies indicate that patients usually overestimate their sleep latency. We sought to determine how comorbidities affect the patient's ability to assess their sleep latency. METHODS: This was a retrospective study of 240 patients who had a polysomnography recorded at our sleep unit or at home in 2017-2020. Data on comorbidities were collected from hospital records. RESULTS: Mean objective sleep latency (29.5 minutes, standard deviation [SD] 35.5) was significantly lower than self-reported sleep (37.4 minutes, SD 41.6) (P < .001). The patients who overestimated their sleep latency had higher mean apnea-hypopnea index (18.8 events/h, SD 21.6, vs 13.4 events/h, SD 12.8; P = .04) and higher mean sleep efficiency (81.7%, SD 13.6%, vs 75.2%, SD 13.9%; P = .004) than those who underestimated their sleep latency. There were significantly more patients with migraine in the overestimation group than in the underestimation group (20/159 patients vs 3/81 patients; P = .035). This difference was not observed in patients with headache without migraine (P = 1.000). CONCLUSIONS: We hypothesize that migraine is markedly associated with overestimation of sleep latency. This overestimation was not observed in patients with other headache types. Further studies are needed to explore the relation between migraine and sleep onset misperception. CITATION: Rantanen O, Hollmen M, Bachour A. Migraine may disturb sleep perception during sleep onset: a retrospective data analysis. J Clin Sleep Med. 2022;18(9):2113-2117.

Urine neutrophil gelatinase-associated lipocalin is a marker of graft recovery after kidney transplantation.

Delayed graft function (DGF), especially long-lasting DGF, complicates kidney transplant outcome. Neutrophil gelatinase-associated lipocalin (NGAL) is an acute kidney injury marker; therefore, we tested whether urine NGAL could predict DGF, prolonged DGF (lasting over 14 days), or the quality of kidney function in transplant recipients without DGF (non-DGF). We collected urine samples from 176 recipients transplanted with deceased donor kidneys before and various days after transplantation. A total of 70 transplantations had DGF, of which 26 were prolonged. Patients who developed DGF had a significantly slower decrease in urinary NGAL compared with those without DGF, such that day 1 NGAL predicted DGF (area under the curve (AUC) 0.75) and predicted DGF in 15 of 112 cases with day 1 urine output over 1 l (AUC 0.70) and in 19 of 86 cases with a day 1 decrease in creatinine over 50 µmol/l (AUC 0.74). The urinary NGAL level on day 1 predicted prolonged DGF (AUC 0.75), which had significantly worse 1-year graft survival (73%), compared with shorter DGF (100%). In non-DGF, high day 3 NGAL (greater than the mean) was associated with significantly worse kidney function at 3 weeks compared with low NGAL, but not at 3 months and 1 year. NGAL did not correlate with long-term function in DGF. Hence, day 1 urinary NGAL predicted DGF even when it was not clinically expected early on, and importantly, it predicted prolonged DGF that led to worse graft survival.

Deceased donor neutrophil gelatinase-associated lipocalin and delayed graft function after kidney transplantation: a prospective study.

INTRODUCTION: Expanding the criteria for deceased organ donors increases the risk of delayed graft function (DGF) and complicates kidney transplant outcome. We studied whether donor neutrophil gelatinase-associated lipocalin (NGAL), a novel biomarker for acute kidney injury, could predict DGF after transplantation. METHODS: We included 99 consecutive, deceased donors and their 176 kidney recipients. For NGAL detection, donor serum and urine samples were collected before the donor operation. The samples were analyzed using a commercial enzyme-linked immunosorbent assay kit (serum) and the ARCHITECT method (urine). RESULTS: Mean donor serum NGAL (S-NGAL) concentration was 218 ng/mL (range 27 to 658, standard deviation (SD) 145.1) and mean donor urine NGAL (U-NGAL) concentration was 18 ng/mL (range 0 to 177, SD 27.1). Donor S-NGAL and U-NGAL concentrations correlated directly with donor plasma creatinine levels and indirectly with estimated glomerular filtration rate (eGFR) calculated using the modification of diet in renal disease equation for glomerular filtration rate. In transplantations with high (greater than the mean) donor U-NGAL concentrations, prolonged DGF lasting longer than 14 days occurred more often than in transplantations with low (less than the mean) U-NGAL concentration (23% vs. 11%, P = 0.028), and 1-year graft survival was worse (90.3% vs. 97.4%, P = 0.048). High U-NGAL concentration was also associated with significantly more histological changes in the donor kidney biopsies than the low U-NGAL concentration. In a multivariate analysis, U-NGAL, expanded criteria donor status and eGFR emerged as independent risk factors for prolonged DGF. U-NGAL concentration failed to predict DGF on the basis of receiver operating characteristic curve analysis. CONCLUSIONS: This first report on S-NGAL and U-NGAL levels in deceased donors shows that donor U-NGAL, but not donor S-NGAL, measurements give added value when evaluating the suitability of a potential deceased kidney donor.

Evaluation of CPAP mask performance during 3 years of mask usage: time for reconsideration of renewal policies?

BACKGROUND: Continuous positive airway pressure (CPAP) mask renewal policies vary inside and between countries. There are no independent studies on the optimal mask renewal frequency. We aimed to evaluate CPAP mask function over time in a real-life clinical setting, and to compare the results against current renewal policies. METHODS: Daily performance data of 1846 CPAP masks (65% nasal, 22% nasal pillows, 12% oronasal) were recorded from 450 participants (68% male, mean age 59 years) with obstructive sleep apnoea. The unintentional leak, Apnoea-Hypopnoea Index (CPAP-AHI) and usage data were exported from the CPAP device. RESULTS: Of 656 324 nights of CPAP usage, the mean renewal time was 497 days (SD 327), mean leak 5.7 L/min (SD 8.1) and CPAP-AHI 3.8 events/h (SD 3.6). The difference in mean leak between one (5.2 L/min, SD 7.5), 12 (6.0 L/min, SD 10.2) and 24 months (5.8 L/min, SD 7.5) was minimal (p=0.59). Mean CPAP-AHI remained normal and unchanged in nasal masks and pillows up to 30 months, and was highest in oronasal masks. Different mask manufacturers performed similarly. Masks' daily or total usage did not affect the results. Shifting the mask renewal policy to 24 months could reduce the mask-related cost up to 50%-88%. CONCLUSIONS: Nasal masks and pillows could be used at least 2 years without significant changes in unintentional leak and CPAP-AHI. We suggest updating the mask renewal policies of nasal masks and pillows; results on oronasal masks and other manufacturers CPAP devices need further verification.

VEGFR-1 and -2 regulate inflammation, myocardial angiogenesis, and arteriosclerosis in chronically rejecting cardiac allografts.

OBJECTIVE: Interplay between inflammation and angiogenesis is important in pathological reparative processes such as arteriosclerosis. We investigated how the two vascular endothelial growth factor receptors VEGFR-1 and -2 regulate these events in chronically rejecting cardiac allografts. METHODS AND RESULTS: Chronic rejection in mouse cardiac allografts induced primitive myocardial, adventitial, and intimal angiogenesis with endothelial expression of CD31, stem cell marker c-kit, and VEGFR-2. Experiments using marker gene mice or rats as cardiac allograft recipients revealed that replacement of cardiac allograft endothelial cells with recipient bone marrow- or non-bone marrow-derived cells was rare and restricted only to sites with severe injury. Targeting VEGFR-1 with neutralizing antibodies in mice reduced allograft CD11b+ myelomonocyte infiltration and allograft arteriosclerosis. VEGFR-2 inhibition prevented myocardial c-kit+ and CD31+ angiogenesis in the allograft, and decreased allograft inflammation and arteriosclerosis. CONCLUSIONS: These results suggest interplay of inflammation, primitive donor-derived myocardial angiogenesis, and arteriosclerosis in transplanted hearts, and that targeting VEGFR-1 and -2 differentially regulate these pathological reparative processes.

Disposal of iron by a mutant form of lipocalin 2.

Iron overload damages many organs. Unfortunately, therapeutic iron chelators also have undesired toxicity and may deliver iron to microbes. Here we show that a mutant form (K3Cys) of endogenous lipocalin 2 (LCN2) is filtered by the kidney but can bypass sites of megalin-dependent recapture, resulting in urinary excretion. Because K3Cys maintains recognition of its cognate ligand, the iron siderophore enterochelin, this protein can capture and transport iron even in the acidic conditions of urine. Mutant LCN2 strips iron from transferrin and citrate, and delivers it into the urine. In addition, it removes iron from iron overloaded mice, including models of acquired (iron-dextran or stored red blood cells) and primary (Hfe-/-) iron overload. In each case, the mutants reduce redox activity typical of non-transferrin-bound iron. In summary, we present a non-toxic strategy for iron chelation and urinary elimination, based on manipulating an endogenous protein:siderophore:iron clearance pathway.

Effect of simvastatin on development of obliterative airway disease: an experimental study.

BACKGROUND: Obliterative bronchiolitis after lung transplantation is characterized by airway inflammation leading to obliteration of small airways. Statins are known to have lipid-independent immunomodulatory properties. We investigated the effect of simvastatin treatment on innate and adaptive immune responses and the development of obliterative airway disease (OAD). METHODS: In fully MHC-mismatched rat tracheal allograft recipients, we used simvastatin at different doses (0.1 to 20 mg/kg/day orally) to assess its effect on OAD development. No immunosuppressive treatment was administered. Histologic, immunohistochemical and real-time RT-PCR analyses were performed 3, 10 and 30 days after transplantation. RESULTS: Simvastatin treatment with doses ranging from 0.5 to 20 mg/kg/day significantly enhanced early epithelial recovery and reduced the development of OAD. No dose response was observed. Simvastatin treatment markedly reduced IL-23 mRNA and lymphocyte chemokine CCL20 production, and the infiltration of CD4(+) and CD8(+) T cells into allografts already at 3 days. At 10 days, simvastatin significantly attenuated the production of pro-inflammatory cytokines, IL-1ß, TNF-α, MCP-1 and IP-10, and Th17-polarizing cytokines, IL-6 and IL-17e, and inhibited allograft infiltration by inflammatory cells. The protective effects of simvastatin on inflammation and OAD were partially mediated through nitric oxide synthase. CONCLUSIONS: Simvastatin treatment inhibited adaptive T-cell alloimmune activation as depicted by reduced expression of lymphocyte chemokine and pro-inflammatory cytokine mRNA and reduced allograft infiltration by inflammatory cells. Importantly, simvastatin inhibits the development of OAD and this effect is partially mediated by increased nitric oxide activity. These results suggest a role for simvastatin in the prevention of obliterative bronchiolitis.

Tacrolimus treatment effectively inhibits progression of obliterative airway disease even at later stages of disease development.

BACKGROUND: Obliterative bronchiolitis (OB) is the most prominent cause of morbidity and mortality among lung transplant patients. No effective treatment for OB exists, but preliminary clinical studies have suggested that a calcineurin inhibitor, tacrolimus, may delay the development of OB when compared with standard cyclosporine-based immunosuppression. METHODS: Using a murine tracheal transplantation model, we examined the effects of tacrolimus prophylaxis and treatment on the development of obliterative airway disease (OAD). Tracheal allografts were transplanted heterotopically from BALB/c to C57 black mice into a subcutaneous pouch. The mice received different doses of tacrolimus monotherapy, ranging from 0 to 3 mg/kg/day, subcutaneously initiated at 0 (prophylaxis), 7 (early treatment) or 14 (late treatment) days. We harvested the grafts 30 days after transplantation for histologic and immunohistochemical analyses. RESULTS: We found that tacrolimus prophylaxis dose-dependently inhibited OAD, and that early treatment halts OAD progression and that late treatment delays progression. Syngeneic grafts showed no obliterative changes. Tacrolimus prophylaxis was associated with inhibition of recruitment of CD4+, CD8+ and interleukin-2R+ inflammatory cells into the allografts, suggesting a central role for interleukin-2 in the development of OAD. In addition, a dose-dependent correlation between epithelial necrosis and tracheal occlusion was observed, suggesting that epithelial injury is required for the development of OAD. When tacrolimus treatment was initiated at the time the obliterative lesion had already started to develop, it inhibited the progression of OAD significantly. CONCLUSIONS: The findings from this study suggest that tacrolimus therapy is effective during the early stages of clinical OB.

Role of platelet-derived growth factor and vascular endothelial growth factor in obliterative airway disease.

RATIONALE: Platelet-derived growth factor (PDGF) is an important smooth muscle cell mitogen, and vascular endothelial growth factor (VEGF) is a known angiogenic and proinflammatory growth factor. We hypothesized that specific therapy aimed at these growth factors might inhibit the development of experimental obliterative airway disease (OAD). METHODS: In fully mismatched rat tracheal allografts, we used imatinib and PTK/ZK, either alone or in combination, to block PDGF and VEGF receptor protein tyrosine kinase (RTK) action, respectively. Prophylaxis was initiated at the time of transplantation. Early treatment was commenced on Day 7 during the inflammatory phase and late treatment on Day 14 during the fibroproliferative phase of OAD. No immunosuppression was administered. MEASUREMENTS AND MAIN RESULTS: Prophylaxis with either PTK/ZK or imatinib alone significantly reduced OAD, and combined prophylaxis completely prevented its development. Early treatment with PTK/ZK and imatinib also effectively reduced the development of OAD. Late treatment failed to show significant efficacy. Blocking VEGF RTK action with PTK/ZK reduced the activation of allograft blood vessels and the number of lymph vessels in the allograft airway wall, and significantly diminished allograft inflammation, whereas PDGF blockade with imatinib inhibited the growth of smooth muscle cells in the proliferating lesion. CONCLUSIONS: Combined prophylactic PDGF and VEGF RTK blockade completely prevents the development of OAD. Also, when early treatment with PTK/ZK and imatinib is commenced during the inflammatory phase of OAD development, it significantly attenuates the development of tracheal occlusion, suggesting that these drugs could potentially be used to treat bronchiolitis obliterans syndrome in its early phase.