Neuron specific enolase concentration is increased in serum and decreased in platelets of patients with active systemic sclerosis.

OBJECTIVE

To determine frequency, origin, and clinical associations of elevated serum neuron specific enolase (NSE) in systemic sclerosis (SSc).

METHODS

Serum was obtained from 75 patients with SSc, 20 systemic lupus erythematosus, 8 polymyositis, 10 idiopathic interstitial lung disease, and 10 healthy volunteers. NSE status was determined in serum (in all individuals) and in platelet lysate (in volunteers and 30 patients with SSc).

RESULTS

Elevated serum NSE (mean 22.6 ng/ml, range 12.1-68.2 ng/ml) was observed in 26 patients with SSc (34.6%). Those with diffuse SSc had higher serum NSE than those with limited disease (16.5 +/- 13.4 vs 9.6 +/- 5.0 ng/ml, p = 0.006). No association was found between serum NSE and lung or esophagus involvement. Patients with long-standing disease had lower serum NSE than those with early disease (10.8 +/- 7.3 vs 16.1 +/- 13.6 ng/ml, p = 0.05). Serum NSE was 19.4 +/- 13.0 ng/ml in patients with total skin score (TSS) > 20, 8.3 +/- 2.1 ng/ml in patients with TSS < 5, and 6.0 +/- 3.1 ng/ml in volunteers (p = 0.01). NSE platelet lysate concentration was 3.6 +/- 2.9 ng/ml in patients with TSS > 20, 12.4 +/- 4.1 ng/ml in those with TSS < 5, and 14.1 +/- 6.5 ng/ml in healthy individuals (p < 0.001). Volunteers and SSc patients with low TSS had comparable S/PL-NSE index (serum/platelet lysate NSE concentration) (0.42 +/- 0.16 and 0.75 +/- 0.33, respectively), both lower than SSc patients with high TSS (7.45 +/- 5.57) (p < 0.001).

CONCLUSION

Elevated serum NSE was observed in one-third of SSc patients but not in other autoimmune rheumatic diseases. The inverse relationship between serum and platelet lysate NSE concentration suggests platelet activation as the origin of high serum NSE in SSc. NSE S/PL was the best discriminatory variable between healthy volunteers and SSc patients as well as between patients with high and low TSS. High serum NSE and high NSE-S/PL index seemed to be associated with SSc disease activity. Further work is warranted to investigate a possible role for this marker in assessing disease activity and therapy response.