Association of psoriasin (S100A7) with clinical manifestations of systemic sclerosis: is its presence in whole saliva a potential predictor of pulmonary involvement?

OBJECTIVE

To evaluate psoriasin (S100A7) expression in whole saliva (WS) of patients with diffuse systemic sclerosis (dSSc) and limited SSc (lSSc), and to correlate its presence with the different clinical manifestations of the disease.

METHODS

Forty-four patients with limited or diffuse SSc were enrolled for study. WS proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and psoriasin was identified by Western blot analysis using a specific polyclonal antibody. Patients with other rheumatic diseases with and without lung involvement were enrolled as pathological controls. Statistical analysis was performed to correlate each clinical manifestation with the presence of psoriasin.

RESULTS

Three bands of 12, 24, and 50 kDa corresponding to monomeric and dimeric/multimeric forms of psoriasin were evidenced by immunoblot analysis in WS of 31 out of 44 patients with SSc (70.4%). In the other 13 WS samples, the 12 kDa band was totally absent, while the dimeric and multimeric bands were expressed at optical intensity (OD) levels comparable to the other samples. From a clinical point of view, the presence of 12 kDa monomeric psoriasin was significantly associated with SSc pulmonary involvement and with anti-Scl-70 antibody positivity. No control showed the psoriasin 12 kDa band.

CONCLUSION

Our results identified salivary 12 kDa psoriasin as a potential predictor of pulmonary involvement in SSc. Thus, a psoriasin assay might be considered as a rapid, noninvasive, useful salivary biomarker for the detection of pulmonary involvement in SSc.