Tracheobronchomalacia (TBM) can be a debilitating disease associated with significant morbidity. Current therapies involve invasive procedures. This study is being conducted to determine whether a fibrotic process is present in this disease and if epithelial mesenchymal transition is a mechanism.
Endobronchial biopsies from 6 patients with severe TBM, who have not had any intervention, underwent immunohistochemical staining for extracellular matrix components (Collagen I, III, and IV) and markers of fibrosis, namely Fibroblast Specific Protein 1 (FSP-1) and alpha Smooth Muscle Actin (αSMA). These were compared with biopsies from 3 patients with no known airway disease. Biopsies were taken from the anterior tracheal wall (ATW), tracheal posterior membrane (TPM), and right mainstem anterior wall (RMA).
4/4 biopsies from the ATW, 2/2 biopsies from the TPM, and 3/4 biopsies from the RMA displayed increased Collagen I expression. 4/5 biopsies from the ATW, 1/1 biopsies from the TPM, and 3/4 biopsies from the RMA demonstrated increased Collagen III expression. 0/4 biopsies from the ATW, 1/2 biopsies from the TPM, and 1/3 biopsies from the RMA revealed increased Collagen IV expression. 0/5 biopsies from the ATW, 0/2 biopsies from the TPM, and 0/4 biopsies from the RMA displayed increased FSP-1 expression. 0/5 biopsies from the ATW, 2/2 biopsies from the TPM, and 1/4 biopsies from the RMA demonstrated increased αSMA expression.
TBM may result from a fibrotic process as evidenced by the increases in Collagens I and III but not IV, as noted in pulmonary fibrosis also. The mechanism is unclear at this time, but may involve epithelial mesenchymal transition.
As more knowledge is gained regarding the underlying histopathology of this disease, more effective and less invasive therapies may be developed.
Dilip Nataraj, No Financial Disclosure Information; No Product/Research Disclosure Information