RESUMO
Chronic lung allograft dysfunction (CLAD) remains the major obstacle to long-term survival following lung transplantation (LuTx). Morphologically CLAD is defined by obliterative remodelling of the small airways (bronchiolitis obliterans, BO) as well as a more recently described collagenous obliteration of alveoli with elastosis summarised as alveolar fibroelastosis (AFE). Both patterns are not restricted to pulmonary allografts, but have also been reported following haematopoietic stem cell transplantation (HSCT) and radio chemotherapy (RC). In this study we performed compartment-specific morphological and molecular analysis of BO and AFE lesions in human CLAD (n = 22), HSCT (n = 29) and RC (n = 6) lung explants, utilising conventional histopathology, laser-microdissection, PCR techniques and immunohistochemistry to assess fibrosis-associated gene and protein expression. Three key results emerged from our analysis of fibrosis-associated genes: (i) generally speaking, "BO is BO". Despite the varying clinical backgrounds, the molecular characteristics of BO lesions were found to be alike in all groups. (ii) "AFE is AFE". In all groups of patients suffering from restrictive changes to lung physiology due to AFE there were largely - but not absolutely - identical gene expression patterns. iii) BO concomitant to AFE after LuTx is characterised by an AFE-like molecular microenvironment, representing the only exception to (i). Additionally, we describe an evolutionary model for the AFE pattern: a non-specific fibrin-rich reaction to injury pattern triggers a misguided resolution attempt and eventual progression towards manifest AFE. Our data point towards an absence of classical fibrinolytic enzymes and an alternative fibrin degrading mechanism via macrophages, resulting in fibrous remodelling and restrictive functional changes. These data may serve as diagnostic adjuncts and help to predict the clinical course of respiratory dysfunction in LuTx and HSCT patients. Moreover, analysis of the mechanism of fibrinolysis and fibrogenesis may unveil potential therapeutic targets to alter the course of the eventually fatal lung remodelling.
RESUMO
Rare Epstein-Barr virus (EBV)+ smooth muscle tumours (SMT) manifest typically under immunosuppression. Three major subtypes are known: human immunodeficiency virus-associated (HIV-SMT), after transplantation (PTSMT) or associated with congenital immunodeficiency syndromes (CI-SMT). So far, there are no analyses which compare the clinico-pathological characteristics of all three subtypes. Case reports and case series on these three tumour types were collected (1990-2012). Meta-data analysis was performed for identification of similarities and differences. A total of 73 HIV-SMT, 66 PTSMT and 9 CI-SMT were evaluated. There was a slight female predominance (55-67%). Children were affected nearly equally in HIV-SMT (33%) and PTSMT (35%), while all CI-SMT occurred in children. HIV-SMT manifested preferentially in the central nervous system, gut/liver, skin, lungs/larynx/pharynx and adrenal glands. PTSMT were predominantly found in the liver, lungs/larynx/pharynx, gut/spleen and brain. CI-SMT were often found in lungs/larynx, brain, liver, adrenal glands and spleen. Antecedent EBV+ lymphoproliferations manifested more often in PTSMT. In all three tumour subtypes, survival analyses did not show any significant differences regarding surgical therapeutic approaches, the occurrence of multiple tumours, tumour size or sarcoma-like histological features. HIV-SMT had the poorest overall survival, which might be attributed to HIV-associated infectious complications.
