Beneficial potential of intravenously administered IL-6 in improving outcome after murine experimental stroke

Authors
M.H. Grønhøj, B.H. Clausen, C.D. Fenger, K.L. Lambertsen, B. Finsen

Lab
University of Southern Denmark, Odense, Denmark

Journal
Brain, Behavior, and Immunity

Abstract
Interleukin-6 (IL-6) is a pleiotropic cytokine with neuroprotective properties. Still, the therapeutic potential of IL-6 after experimental stroke has not yet been investigated in a clinically relevant way. Here, we investigated the therapeutic use of intravenously administered IL-6 and the soluble IL-6 receptor (sIL-6R) alone or in combination, early after permanent middle cerebral artery occlusion (pMCAo) in mice. IL-6 did not affect the infarct volume in C57BL/6 mice, at neither 24 nor 72 h after pMCAo but reduced the infarct volume in IL-6 knockout mice at 24 h after pMCAo. Assessment of post-stroke behavior showed an improved grip strength after a single IL-6 injection and also improved rotarod endurance after two injections, in C57BL/6 mice at 24 h. An improved grip strength and a better preservation of sensory functions was also observed in IL-6 treated IL-6 knockout mice 24 h after pMCAo. Co-administration of IL-6 and sIL-6R increased the infarct volume, the number of infiltrating polymorphonuclear leukocytes and impaired the rotarod endurance of C57BL/6 mice 24 h after pMCAo. IL-6 administration to naïve C57BL/6 mice lead after 45 min to increased plasma-levels of CXCL1 and IL-10, whereas IL-6 administration to C57BL/6 mice lead to a reduction in the ischemia-induced increase in IL-6 and CXCL1 at both mRNA and protein level in brain, and of IL-6 and CXCL1 in serum. We also investigated the expression of IL-6 and IL-6R after pMCAo and found that cortical neurons upregulated IL-6 mRNA and protein, and upregulated IL-6R after pMCAo. In conclusion, the results show a complex but potentially beneficial effect of intravenously administered IL-6 in experimental stroke.

BIOSEB Instruments Used:
Grip strength test (BIO-GS3)