Anti-TNF, Pan-JAK, and JAK1-Selective Inhibition Differentially Alter Mechanisms of Flow-Mediated Dilation in Human Microvessels

Patients with chronic inflammatory disorders, including inflammatory bowel disease (IBD), carry an increased risk of cardiovascular disease. The 2022 ORAL Surveillance study reported that the pan-selective Janus kinase inhibitor (JAKi) tofacitinib was associated with increased risk of major adverse cardiovascular events (MACE) among patients with rheumatoid arthritis compared to anti–tumor necrosis factor (anti-TNF) therapy. This prompted guideline changes regarding the use of all JAKis, including upadacitinib, a JAK1-selective drug approved for use in chronic inflammatory conditions, including IBD. However, the mechanism underlying JAKi-related MACE outcomes and the significance of JAK selectivity relative to TNF inhibition remain unclear. Microvascular dysfunction (MVD) is a predictor of MACE. Flow-mediated dilation (FMD) is a measure of MVD. Using an established ex vivo model of resistance arterioles isolated from adipose tissue, we performed the first mechanistic comparison of anti–tumor necrosis factor (anti-TNF; infliximab), pan-JAK inhibitor (tofacitinib), and JAK1-selective (upadacitinib) therapies on human microvascular endothelial function. Arterioles were obtained from low-cardiovascular-risk subjects of both sexes. Isolated microvessels were incubated with drugs of interest. Flow-mediated dilation (FMD), an assessment of MVD, was measured before and after nitric oxide (NO) synthase inhibition or hydrogen peroxide (H₂O₂) scavenging. No therapy statistically altered FMD magnitude, yet underlying mechanisms differed. Control and infliximab-treated vessels maintained physiologic NO-mediated dilation. Tofacitinib induced a shift toward pathologic H₂O₂-mediated dilation. Upadacitinib impaired NO-dependent dilation without evidence of compensatory H₂O₂ signaling. In summary, anti-TNF therapy and selective versus non-selective JAKi differentially modulate endothelial mechanisms of vasodilation, suggesting unique microvascular phenotypes with potential implications for cardiovascular risk.