ABSTRACT
Lymphangioleiomyomatosis (LAM) is associated with abnormal airway smooth muscle that leads to the characteristic pathology of lung nodule formation and destruction of lung tissue. The current authors have previously identified abnormal behaviour of airway smooth muscle cells from patients with asthma. In this study, cells and tissue sections derived from patients with LAM (n=7), asthma (n=8), and nonasthmatic controls (n=9) were compared. The presence of the antigen human melanosome (HM)B-45 was investigated, along with the proliferation and release of extracellular matrix proteins, release of endogenous prostaglandin E2 (PGE2), vascular endothelial growth factor and connective tissue growth factor, and the expression of integrins. Positive HMB-45 staining was found in all LAM patients and no controls. Proliferation of LAM cells was not different from control cells nor was its inhibition by beta-agonists, corticosteroids, rapamycin or PGE2. However, endogenous PGE2 levels were markedly decreased in LAM cells, and this was associated with decreased expression of the inducible form of cyclooxygenase (COX-2). The increased levels of connective tissue growth factor seen in asthma cells were not observed in LAM. Elastin mRNA in response to transforming growth factor-beta stimulation was markedly lower in LAM cells than either asthma or control cells. In conclusion, lymphangioleiomyomatosis cells exhibit abnormal properties in vitro that may contribute to pathophysiology and symptomatology in patients with lymphangioleiomyomatosis.
Subject(s)
Dinoprostone/biosynthesis , Extracellular Matrix Proteins/biosynthesis , Growth Substances/biosynthesis , Integrins/biosynthesis , Lymphangioleiomyomatosis/metabolism , Neoplasm Proteins/biosynthesis , Adolescent , Adult , Aged , Antigens, Neoplasm , Asthma/metabolism , Asthma/physiopathology , Cells, Cultured , Connective Tissue Growth Factor , Cyclooxygenase 2/biosynthesis , Female , Humans , Immediate-Early Proteins/biosynthesis , Intercellular Signaling Peptides and Proteins/biosynthesis , Lung , Lymphangioleiomyomatosis/physiopathology , Male , Melanoma-Specific Antigens , Middle Aged , Myocytes, Smooth Muscle , Transforming Growth Factor beta , Vascular Endothelial Growth Factor A/biosynthesisABSTRACT
Breathing at volumes lower than functional residual capacity (FRC) can induce changes in nonasthmatic airways consistent with the behaviour of asthmatic airways. This study investigated the chronic effect of breathing at volumes lower than FRC on the contractility of airway smooth muscle and myosin light chain kinase (MLCK) content and activity. Sheep of three age groups (neonate, adolescent and adult) had their FRC reduced by approximately 25%, for 4 weeks using a leather corset. Contractile responses to carbachol were then recorded in isolated tracheal strips and bronchial rings. MLCK content and activity were assessed by immunoblotting. The rate of stress generation increased in the bronchial smooth muscle of both adult and adolescent but not neonatal corseted sheep: adolescent corseted versus control, 65.0 +/- 4.1 versus 103.4 +/- 7.0 s (to reach 50% maximum stress), respectively; and adult corseted versus control, 57.0 +/- 6.4 versus 93.4 +/- 8.2 s, respectively. This was not due to increases in either bronchial or tracheal smooth muscle amount or MLCK content and activity. The present results indicate that chronic breathing at low lung volumes increases the rate of stress generation in airway smooth muscle.
