Involvement of mast cells in clinical features of scleroderma

Sonosuke Yukawa1), Norifumi Sawamukai1), Kunihiro Yamaoka1), Kazuyoshi Saito1),Kazuhisa Nakano, Shohei Shimajiri2), Yasuyuki Sasaguri2), Yoshiya Tanaka1)
1)The First Department of Internal Medicine, School of Medicine 2) The Department of Second Pathology and Cell Biology, School of Medicine, University of Occupational and Environmental Health, Japan

The animal model of scleroderma, the tight-skin mouse, develops many pathological features seen in human scleroderma with increased number of mast cells (MCs) in skin. To clarify the involvement of MCs in human scleroderma pathology, we have evaluated skin biopsy specimens from SSc patients (41 cases). Number of MCs (mast cells/㎟) in each specimen was detected with NanoZoomer Digital Pathology after staining with toluidine blue and c-kit. Significantly increased number of MCs was observed in SSc compared with non- SSc specimens (20.6 vs 12.9, P=0.000). An increased trend of MCs in specimens from finger was observed with patients with higher total skin score (TSS) of 11. In addition, patients positive for anti-Scl-70 antibody had higher MC number compared with negative patients (29.9 vs 20.1, P=0.026). Surprisingly, MC was increased in cases with pulmonary hypertension (26.8 vs 19.8, p=0.046), and showed strong relation with mean pulmonary arterial pressure (PAP) measured by cardiac ultrasound (R=0.522). We conclude here that MCs are increased in skin biopsy specimen from SSc patients especially with pulmonary hypertension and its density was related with the level of mean PAP. Therefore, we suggest the involvement of MCs in the pathogenesis of pulmonary hypertension in SSc.