Cerebrospinal Fluid Cytokines Correlate With Aseptic Meningitis and Blood–Brain Barrier Function in Neonatal‐Onset Multisystem Inflammatory Disease: Central Nervous System Biomarkers in Neonatal‐Onset Multisystem Inflammatory Disease Correlate With Central Nervous System Inflammation

Objective To evaluate proinflammatory cytokines and leukocyte subpopulations in the cerebrospinal fluid (CSF) and blood of patients with neonatal‐onset multisystem inflammatory disease (NOMID) after treatment, and to compare inflammatory cytokines in the CSF and blood in 6 patients treated with 2 interleukin‐1 (IL‐1) blockers—anakinra and canakinumab. Methods During routine follow‐up visits between December 2011 and October 2013, we immunophenotyped the CSF of 17 pediatric NOMID patients who were treated with anakinra, and analyzed CSF cytokine levels in samples obtained at baseline and at 3–5‐year follow‐up visits and compared them to samples from healthy controls. Results CSF levels of IL‐6, interferon‐γ–inducible 10‐kd protein (IP‐10/CXCL10), and IL‐18 and monocyte and granulocyte counts significantly decreased with anakinra treatment but did not normalize to levels in the controls, even in patients fulfilling criteria for clinical remission. CSF IL‐6 and IL‐18 levels significantly correlated with measures of blood–brain barrier function, specifically CSF protein (r = 0.75 and r = 0.81, respectively) and albumin quotient (r = 0.79 and r = 0.68, respectively). When patients were treated with canakinumab versus anakinra, median CSF white blood cell counts and IL‐6 levels were significantly higher with canakinumab treatment (10.2 cells/mm3 versus 3.7 cells/mm3 and 150.7 pg/ml versus 28.5 pg/ml, respectively) despite similar serum cytokine levels. Conclusion CSF leukocyte subpopulations and cytokine levels significantly improve with optimized IL‐1 blocking treatment, but do not normalize. The correlation of CSF IL‐6, IP‐10/CXCL10, and IL‐18 levels with clinical laboratory measures of inflammation and blood–brain barrier function suggests that they may have a role as biomarkers in central nervous system (CNS) inflammation. The difference in inhibition of CSF biomarkers between 2 IL‐1 blocking agents, anakinra and canakinumab, suggests differences in efficacy in the intrathecal compartment, with anakinra being more effective. Our data indicate that intrathecal immune responses shape CNS inflammation and should be assessed in addition to blood markers.