Increased angiopoietin-1 improves nailfold capillary morphology in patients with systemic sclerosis

Raynaud's phenomenon is a common symptom of systemic sclerosis. We previously reported that elbow heating increases angiopoietin-1 in the fingertips and alleviates Raynaud's phenomenon. Angiopoietin-1 levels decrease in patients with systemic sclerosis with severe capillary damage. We aimed to conduct a prospective study to confirm whether the increase in angiopoietin-1 caused by heating modifies capillary morphology.

The left ring fingers of 19 patients with systemic sclerosis were monitored six times at 4-week intervals using capillaroscopy, during which both elbows were heated using disposable heating pads for 8 weeks. Blood samples were collected from the same fingertips four times-before heating, twice during heating, and once after heating-to measure angiopoietin-1.

In six patients, the peak increase in angiopoietin-1 occurred 4 weeks after the start of heating, whereas in seven patients, the peak value was observed 4 weeks after the termination thereof. No change in the density of the front-row capillaries was observed by capillaroscopy. The proportion of hairpin-shaped capillaries increased from 20.2 % during the preheating period to 26.6 % during the heating period (p = 0.00107). When a correlation coefficient of 0.6 or higher was set as significant, there was a strong correlation between changes in fingertip angiopoietin-1 levels and changes in the proportion of hairpin-shaped capillaries in six patients.

Increased angiopoietin-1 levels in the fingertip due to elbow heating may improve the peripheral capillary morphology in patients with systemic sclerosis.