Vascular Arginase Is a Relevant Target to Improve Cerebrovascular Endothelial Dysfunction in Rheumatoid Arthritis: Evidence from the Model of Adjuvant-Induced Arthritis

{Emerging data revealed that rheumatoid arthritis (RA) is associated with higher risk of cerebrovascular diseases. Whereas cerebral endothelial dysfunction is acknowledged as a critical aspect of cerebrovascular diseases, its presence in RA and the mechanisms involved are currently unknown. By using the model of rat adjuvant-induced arthritis (AIA), the present study investigated cerebrovascular reactivity in pressurized middle cerebral arteries (MCA) on day 33 post-immunization. The results revealed that arthritis induced a dramatic decrease in the vasodilatory response to acetylcholine (ACh), ADP, and bradykinin (n = 7-9 arteries, p < 0.0001). By using nor-NOHA, L-NAME, BH4, and Tempol, the results showed that the reduced response to ACh relied on arginase overactivation (n = 8), low NOS activity (n = 8), BH4 deficiency (n = 9), and excessive superoxide production (n = 9). Immunohistological analysis revealed an endothelial upregulation of arginase 2 (p < 0.05