Knockdown of interleukin-1 receptor type-1 on endothelial cells attenuated stress-induced neuroinflammation and prevented anxiety-like behavior

• Published in: The Journal of neuroscience Vol. 34; no. 7; pp. 2583 - 2591
• Main Authors: Wohleb, Eric S, Patterson, Jenna M, Sharma, Vikram, Quan, Ning, Godbout, Jonathan P, Sheridan, John F
• Format: Journal Article
• Language: English
• Published: United States Society for Neuroscience 12.02.2014
• Subjects: Animals; Anxiety - metabolism; Behavior, Animal - physiology; Brain - metabolism; Brain - pathology; Chemotaxis, Leukocyte - physiology; Endothelial Cells - metabolism; Flow Cytometry; Fluorescent Antibody Technique; Interleukin-1 - metabolism; Macrophages - metabolism; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Real-Time Polymerase Chain Reaction; Receptors, Interleukin-1 Type I - deficiency; Receptors, Interleukin-1 Type I - metabolism; Signal Transduction - physiology; Stress, Psychological - metabolism; blood-brain barrier; anxiety; stress; interleukin-1; neuroinflammation; microglia
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/jneurosci.3723-13.2014

Interleukin-1β (IL-1β) is an inflammatory cytokine that plays a prominent role in stress-induced behavioral changes. In a model of repeated social defeat (RSD), elevated IL-1β expression in the brain was associated with recruitment of primed macrophages that were necessary for development of anxiety-like behavior. Moreover, microglia activation and anxiety-like behavior associated with RSD did not occur in IL-1 receptor type-1 knock-out (IL-1R1(KO)) mice. Therefore, the objective of this study was to examine the role of IL-1 signaling in RSD-induced macrophage trafficking to the brain and anxiety-like behavior. Initial studies revealed that RSD did not increase circulating myeloid cells in IL-1R1(KO) mice, resulting in limited macrophage trafficking to the brain. In addition, IL-1R1(KO) bone marrow-chimera mice showed that IL-1R1 expression was essential for macrophage trafficking into the brain. To differentiate cellular mediators of stress-induced IL-1 signaling, endothelial-specific IL-1R1 knock-down (eIL-1R1kd) mice were used. Both wild-type (WT) and eIL-1R1kd mice had increased circulating monocytes, recruitment of macrophages to the brain, and altered microglia activation after RSD. Nonetheless, RSD-induced expression of IL-1β, TNF-α, and IL-6 mRNA in brain CD11b(+) cells was attenuated in eIL-1R1kd mice compared with WT. Moreover, anxiety-like behavior did not develop in eIL-1R1kd mice. Collectively, these findings demonstrated that there was limited RSD-induced priming of myeloid cells in IL-1R1(KO) mice and disrupted propagation of neuroinflammatory signals in the brain of eIL-1R1kd mice. Furthermore, these data showed that transduction of IL-1 signaling by endothelial cells potentiates stress-induced neuroinflammation and promotes anxiety-like behavior.