Blood-clotting protein FXIII linked to Raynaud’s in SSc patients

Raynaud's phenomenon is a common systemic sclerosis symptom by Steve Bryson, PhD 

​Elevated activity of a blood-clotting protein called Factor XIII (FXIII) in the bloodstream of adults with systemic sclerosis (SSc) is tied to the presence of Raynaud’s phenomenon, a common SSc symptom, a small study suggests.
While most study participants had FXIII activity levels within the normal range, “patients with higher FXIII activity are more likely to have circulatory disorders in their hands,” the researchers noted.
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The study, “Factor XIII and Endothelial Dysfunction in Patients with Systemic Sclerosis,” was published in the journal Hämostaseologie.

​SSc, also called scleroderma, is an autoimmune disease that affects the skin and potentially internal organs, including the heart and blood vessels, the lungs, stomach, kidneys and joints.

Raynaud’s phenomenon is an SSc symptom characterized by numbness and prickling in the fingers and toes in response to cold temperatures or emotional distress.

FXIII is a blood-clotting protein that helps stabilize clot formation. Given its role in tissue repair, previous studies have evaluated FXIII in patients with SSc, resulting in reduced skin symptoms and joint pain.

Despite these findings, “FXIII administration has so far not been evaluated broadly as a new treatment option,” wrote researchers in Germany.

To support ongoing evaluations, the team investigated the relationship between FXIII activity, the severity of skin involvement, and the dysfunction of endothelial cells, which line blood vessels. A group of 56 SSc patients, ages 25-74 years, were recruited, most of whom were women (89.3%).

“Our study is the first study that focused on the relationship between FXIII, endothelial dysfunction, and cutaneous [skin] manifestations in scleroderma,” the team noted.

VWF-Ag levels elevated in some
​Elevated activity of FXIII, greater than the normal range of 70–140%, were found in the bloodstream of 16 of 56 SSc patients, while only one patient had an FXIII deficiency. A marker for endothelial dysfunction, von Willebrand factor antigen (VWF-Ag), was elevated in 30 participants.

“A reduced FXIII activity in scleroderma patients would have been an explanation why FXIII substitution to patients with scleroderma improved their clinical outcomes,” the researchers wrote. “However, the results of our present study could not establish any evidence of an increased occurrence of FXIII deficiency in scleroderma patients.”

No significant relationships between FXIII activity and several markers of inflammation and endothelial dysfunction were detected. While lower FXIII activity was found in those with elevated VWF-Ag, the difference was not statistically significant.

FXIII activity also was unrelated to modified Rodnan skin scores (mRSS), a measure of overall skin involvement, and activities of daily living, as assessed by the patient-reported Scleroderma Health Assessment Questionnaire (SHAQ).

However, a significantly positive correlation was detected between elevated FXIII activity and Raynaud’s phenomenon. Higher FXIII activity was non-significantly linked with perceived pain.

Elevated VWF-Ag correlated with lung involvement, as indicated by patients, and higher mRSS scores, meaning that “higher WWF-Ag levels come along with more severe skin involvement,” the team wrote.

“Our results confirm that there is no general FXIII deficit in patients with SSc and no correlation between low factor XIII levels and [skin] ulcers,” the researchers concluded. “Further studies are needed, particularly with regard to a substitution therapy of FXIII in SSc aiming to broaden the therapeutic options of the disease.”