RESUMO
Glanzmann thrombasthenia (GT) is a rare autosomal recessive bleeding disorder characterized by impaired platelet aggregation due to defects in integrin αIIbß3, a fibrinogen receptor. Platelet phenotypes and allelic variations in 28 Turkish GT patients are reported. Platelets αIIbß3 expression was evaluated by flow cytometry. Sequence analyzes of ITGA2B and ITGB3 genes allowed identifying nine variants. Non-sense variation effect on αIIbß3 expression was studied by using transfected cell lines. 3D molecular dynamics (MDs) simulations allowed characterizing structural alterations. Five new alleles were described. αIIb:p.Gly423Asp, p.Asp560Ala and p.Tyr784Cys substitutions impaired αIIbß3 expression. The αIIb:p.Gly128Val substitution allowed normal expression; however, the corresponding NM_000419.3:c.476G>T variation would create a cryptic donor splicing site altering mRNA processing. The ß3:p.Gly540Asp substitution allowed αIIbß3 expression in HEK-293 cells but induced its constitutive activation likely by impairing αIIb and ß3 legs interaction. The substitution alters the ß3 I-EGF-3 domain flexibility as shown by MDs simulations. GT variations are mostly unique although the NM_000419.3:c.1752 + 2 T > C and NM_000212.2:c.1697 G > A variations identified in 4 and 8 families, respectively, might be a current cause of GT in Turkey. MD simulations suggested how some subtle structural variations in the ß3 I-EGF domains might induce constitutive activation of αIIbß3 without altering the global domain structure.
Assuntos
Integrina alfa2 , Integrina beta3 , Complexo Glicoproteico GPIIb-IIIa de Plaquetas , Trombastenia , Fator de Crescimento Epidérmico , Células HEK293 , Humanos , Integrina alfa2/genética , Integrina beta3/genética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Trombastenia/genética , Trombastenia/metabolismo , TurquiaRESUMO
BACKGROUND: Lipoxins could be potential modulators of inflammation in the lungs. To our knowledge, the role of exhaled breath condensate (EBC) lipoxin A4 (LXA4) in asthmatic children with exercise-induced bronchoconstriction (EIB) has not been investigated. OBJECTIVE: The aim of our study was to determine the involvement of EBC LXA4 in EIB. METHODS: Forty-five patients aged between 5 and 17 years were included in the study. Patients were divided into 2 groups: asthmatic children with a positive response to exercise (n = 17) and asthmatic children with a negative response to exercise (n = 28). Levels of LXA4 were determined in EBC before and immediately after the exercise challenge using ELISA. RESULTS: EBC LXA4 levels were significantly increased immediately after exercise in asthmatic children with a positive response to the exercise challenge (P = .05). No significant differences were observed in children with a negative response to exercise (P > .05). There was an inverse correlation between LXA4 levels and the percent degree of reduction in forced expiratory volume in the first second (FEV1%) postexercise in children with a positive exercise challenge (P = .05, r = -0.50). No significant differences were observed in LXA4 levels between atopic and nonatopic asthmatics (P > .05, Mann-Whitney U test). CONCLUSIONS: Levels of EBC LXA4 increased immediately after exercise in asthmatic children with a positive exercise challenge response. We hypothesize that airway LXA4 levels increase to compensate bronchoconstriction and suppress acute inflammation, and that spontaneous bronchodilatation after EIB may be due to LXA4.
Assuntos
Asma Induzida por Exercício/metabolismo , Testes Respiratórios , Broncoconstrição , Expiração , Mediadores da Inflamação/metabolismo , Lipoxinas/metabolismo , Pulmão/metabolismo , Adolescente , Fatores Etários , Asma Induzida por Exercício/diagnóstico , Asma Induzida por Exercício/fisiopatologia , Biomarcadores/metabolismo , Estudos de Casos e Controles , Criança , Pré-Escolar , Ensaio de Imunoadsorção Enzimática , Teste de Esforço , Feminino , Volume Expiratório Forçado , Humanos , Pulmão/fisiopatologia , Masculino , Valor Preditivo dos Testes , Estudos Prospectivos , Regulação para CimaRESUMO
BACKGROUND AND OBJECTIVE: The pathogenesis of exercise-induced bronchoconstriction (EIB) in asthma is incompletely understood. The role of exhaled breath condensate (EBC) annexin A5, which is an anti-inflammatory mediator, has not been investigated. The purpose of this study is to evaluate EBC annexin A5 levels in EIB in asthmatic children. METHODS: Two groups of children were enrolled in this study: asthmatic children with positive (n=11) and negative (n=7) responses to exercise. The levels of pre- and post-exercise EBC annexin A5 were determined with using enzyme-linked immunosorbent assay (ELISA). RESULTS: We observed significant higher pre-exercise EBC annexin A5 levels in the challenge test negative children than in the challenge test positive children (p<0.05). No significant difference was observed in the post-exercise EBC annexin A5 levels between the groups (p>0.05). Also, no significant difference was observed between pre- and post-exercise EBC annexin A5 levels within each group (p>0.05). There was an inverse correlation between annexin A5 levels and a reduction in forced expiratory volume at one second percent (FEV1%) (p=0.009, r=-0.598). CONCLUSIONS: Our preliminary study showed that EBC annexin A5 may have a possible preventive role in EIB in asthma. Annexin A5 and related compounds may provide novel therapeutic approaches to the treatment of EIB in asthma.