Fig. 4.

Interleukin-11 counteracted TNF-α involvement in cold preconditioning neuroprotection. (a) Pre-conditioning with IL-11, an anti-inflammatory cytokine that inhibits TNF-α, at 1000 (n = 4), 100 (n = 14), 10 (n = 16), 1 (n = 10), and 0.1 (n = 8) ng/mL for 24 h did not significantly protect against subsequent NMDA injury versus control (n = 16). (b) Furthermore, cold pre-conditioning (CP; 30°C for 90 min) with IL-11 (CP + IL-11; 100 ng/mL; n = 21) abrogated the otherwise significant (p = 0.002) neuroprotection from CP (n = 22) versus control (n = 24). (c) In contrast, cold pre-conditioning plus blockade of IL-11 signaling (CP + anti-IL-11; n = 17) by pre-treatment for 24 h with anti-IL-11 neutralizing antibody (100 µg/mL) significantly (p < 0.001) enhanced neuroprotection from cold pre-conditioning alone (n = 13) with both conditions providing significant (p < 0.001) protection over control (n = 25). Finally, the specificity of this IL-11 blocking effect was confirmed by comparison to the effect of cold pre-conditioning plus an isotype, but otherwise non-specific, antibody (CP + IgG2A; 100 µg/ mL; n = 9), which did not significantly (p = 0.401) enhance neuroprotection from cold pre-conditioning alone.