Increased serum production of soluble CD163 and CXCL5 in patients with moyamoya disease: Involvement of intrinsic immune reaction in its pathogenesis

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by a progressive stenosis at the terminal portion of the internal carotid artery and an abnormal vascular network at the base of the brain. Although its etiology is still unknown, intrinsic immune reactions such as autoimmune response has been implicated in the pathogenesis of MMD. Recently, the RING finger protein 213 (RNF213) was found to be an important risk gene for MMD, and is predominantly expressed in blood cells and the spleen. Thus, we hypothesized that patients with MMD represent an intrinsic autoimmune status mediated by M2-polarized macrophages, which play an important role in tissue remodeling and angiogenesis. We compared the serum level of soluble (s)CD163, an activating marker for CD163+ M2-polarized macrophages that has been implicated in a variety of autoimmune disorders, between MMD patients and healthy controls. We also analyzed serum levels of CXCL5, an augmented cytokines that has been correlated with the severity of autoimmune diseases. As a result, the serum sCD163 levels of MMD patients (281,465 pg/ml) were significantly higher than those of healthy controls (174,842 pg/ml) (p = .004). The serum CXCL5 levels of MMD patients (679.02 pg/ml) were significantly higher than those of healthy controls (401.79 pg/ml) (p = .046). There were no differences in the serum sCD163 and CXCL5 levels between each genotype of the RNF213 polymorphism (wild-type or variant) among MMD patients. Although this is a pilot study and further validation with larger number of samples is necessary, our results indicate that patients with MMD may have increased autoimmune activity, and our results shed light on the pathogenesis of MMD via CD163+ M2-polarized macrophages.