Increased pulmonary epithelial permeability in systemic sclerosis is associated with enhanced cutaneous nerve growth factor expression

Background: Nerve growth factor (NGF), a neurotrophic factor that indirectly induces fibroblast proliferation and collagen production, has been found to be increased in the affected dermis of patients with systemic sclerosis (SSc). To investigate the possibility of a relationship between cutaneous NGF production and pulmonary damage in SSc, we studied seven non-smoking scleroderma patients. Methods: Abnormalities in lung structure were assessed by radiological lung examination, and pulmonary epithelial permeability (PEP) was determined by ventilation lung scintigraphy. All patients underwent skin punch biopsy with NGF immunohistological staining. Results: A statistically significant correlation was found between the PEP values and the cutaneous NGF staining scores, which were markedly increased in all of the patients examined, irrespective of the age, disease duration, or radiologically defined lung abnormalities. Conclusion: These results support the hypothesis that functional and anatomical changes in SSc target organs may be determined by a local tissue hyperproduction of NGF.