Correlation of serum level of homing cell adhesion molecule [HCAM, sCD44] with clinical features and prognosis in systemic sclerosis

To evaluate the level of Homing Cell Adhesion molecule [H-CAM, sCD44] in the sera of systemic sclerosis [SSc] patients and to investigate its relationship to clinical and prognostic features of the disease. This prospective study was conducted on 30 SSc patients; 18 with limited cutaneous SSc [lSSc] and 12 with diffuse cutaneous SSc [dSSc]. Twenty apparently healthy subjects participated to the study as controls. Clinical evaluation and pulmonary function tests were done for all of them. Laboratory investigations and serum levels of soluble CD44 [sCD44] were determined using specific enzyme-linked immunosorbent assay [ELISA] for all patients and controls. Serum concentration of sCD44 was significantly elevated in SSc patients as compared with controls [1.89 +/- 0.72 vs. 1.42 +/- 0.33 ng/ml, p<0.001]. This elevation was observed in 43% of SSc patients; in 50% with lSSc patients but only 33% in dSSc patients. In addition, serum sCD44 levels were significantly elevated in patients with lSSc when compared with those with dSSc patients and both were significantly higher than controls [2.06 +/- 0.62 vs. 1.67 +/- 0.25 ng/ml, p < 0.001 and p < 0.02 respectively]. A significant correlation was found between elevated sCD44 levels and the extent of skin sclerosis as determined with Modified Rodnan Skin Score [r=0.670 and p<0.001]. It was also found that the prevalence of pulmonary fibrosis and decreased FVC% and FEV1% in SSc patients with elevated sCD44 levels were significantly lower than in those with normal sCD44 levels [15 vs. 51%, p <0.001; 16 vs. 56%, p <0.001 and 28 vs. 64%, p<0.001 respectively]. Furthermore, the prevalence of pulmonary fibrosis was significantly lower in ISSc with elevated sCD44 levels than in those with normal levels [22% vs. 56%, p<0.001]. Although the disease duration was similar for SSc patients with elevated sCD44 levels and those with normal levels, the disease duration in ISSc patients with elevated sCD44 levels was significantly shorter than in patients with normal sCD44 levels [4.1 +/- 6.6 vs. 7.1 +/- 9.4 yrs; p<0.01]. Elevation of serum concentration of sCD44 and its prevalence was more in the limited form of SSc [ISSc]. This elevation correlated significantly with the shorter disease duration in patients with ISSc. Furthermore, elevated sCD44 levels were also associated with lower prevalence of pulmonary involvement and better pulmonary function in SSc patients. This was observed even in patients with ISSc. Taken together, these results suggest that the elevation of sCD44 may be a prognostic marker and protective factor for the development of skin sclerosis and pulmonary fibrosis in SSc