Suppressed signal transduction in the bronchial epithelium of patients with systemic sclerosis

Abstract

Systemic sclerosis (SSc) is an autoimmune disorder, which frequently affects the lungs, with manifestations of interstitial lung disease (ILD) with lung fibrosis and of pulmonary hypertension. The pathogenesis remains largely unrecognised. The aim of this study was to elucidate the inflammation in the bronchial mucosa in patients with SSc. Twenty-three subjects diagnosed with SSc participated. Twelve of the SSc patients showed signs of ILD, four were smokers and seven were treated with oral corticosteroids. Seventeen non-smoking, age- and sex-matched healthy subjects served as controls. Bronchoscopy was performed to sample endobronchial mucosal biopsies, which were immunohistochemically stained using a panel of antibodies against inflammatory markers. The number of neutrophils was significantly elevated in the submucosa of SSc patients, regardless of ILD, or whether the subject was smoking or using oral corticosteroids. No up-regulation of neutrophil chemoattractants or cytokines was seen in the bronchial epithelium. The signal transduction pathways and adhesion molecule expression tended to be suppressed or unchanged in SSc patients compared with controls. It is concluded that SSc is associated with a chronic neutrophilic inflammation in the bronchial mucosal, with signs of suppressed signal transduction, regardless of the presence of interstitial lung disease.