Decreased Level of IL-37 Correlates Negatively with Inflammatory Cytokines in Cerebrospinal Fluid of Patients with Neuro-Behcet’s Disease

Behçet's disease (BD) is a systemic inflammatory disease with a chronic, relapsing-remitting course of unknown etiology. Neuro-Behcet’s disease (NBD) induce serious CNS complications and are known to be the main cause of long-term morbidity and mortality. IL‐37 is a natural suppressor of innate inflammation which its role in NBD has not been fully understood.

To determine the expression of IL-37 in cerebrospinal fluid (CSF) and its relationship with other inflammatory cytokines.

Level of IL-37, IL-6, IL-17, IL-21, TSLP and TGF-β were measured in CSF of 22 patients with NBD and 12 non-inflammatory neurological disease (NIND) and 10 headache attributed to Behçet's disease (HaBD) by enzyme‐linked immunosorbent assay (ELISA). In addition, IL-37 mRNA relative expression was detected by quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR).

CSF level and mRNA expression of IL‐37 were elevated in NBD patients compared to those in NIND and HaBD patients. Levels of IL-6, IL-17, IL-21 and TSLP were found to be increased in NBD patients and were inversely associated with IL-37 level. Moreover, TGF-β level in CSF of NBD patients was positively correlated with IL-37 levels. IL-37 increased significantly after treatment and in remission group, but TGF-β was only increased in treatment group.

IL‐37 expression increased in NBD patients, and correlated with disease activity. Our data conclude that IL-37 could be a disease marker in NBD, however it requires further studies.