Interleukin-10 (IL-10) has been utilized as a
neuroprotective agent in experimental models of
spinal cord injury because of its potent anti-inflammatory properties. Previous studies have delivered a single dose (5 microg) of
IL-10 following experimental
spinal cord injury in the rat, and demonstrated various degrees of neuroprotection. However, the role of endogenous production of
IL-10 has not been considered. Therefore, the purpose of the current study was to establish the role of endogenous
IL-10 and demonstrate the true potential of exogenous
IL-10 administration through the use of IL-10((-/-)) mice. Using the
quisqualic acid model of
spinal cord injury, we examined the extent of gray matter damage and onset of injury-induced
pain behaviors at various time points following injury in wild-type vs. IL-10((-/-)) mice. Additionally,
IL-10 was reconstituted in
IL-10 deficient mice by the intraperitoneal administration of 50 ng recombinant murine (rm)
IL-10 30 min following
quisqualic acid injection. Animals were observed daily following injury for the onset of
pain-behaviors. At days 1, 7, and 14 following injection, lesion analysis revealed a greater extent of damage at early time points (1 day, 7 days) following injury in the IL-10((-/-)) animals as compared with wild-type animals. However, by 14 days post-experimental
spinal cord injury, the extent of damage between the two groups was not significant. IL-10((-/-)) animals that received the single (50 ng) rmIL-10 injection following injury displayed gray matter damage patterns similar to wild-type animals. The pronounced early damage noted in the IL-10((-/-)) animals was associated with an approximately two-fold increase in peripheral neutrophils, an index of an innate immune response to injury, compared with wild-type mice. In addition, wild type and IL-10((-/-)) animals receiving rmIL-10 demonstrated a delay in the onset of injury-induced
pain behaviors. However, by 14 days post-experimental
spinal cord injury the overall incidence of
pain behaviors was similar between all treatment groups. Therefore, the absence of
IL-10 expression accelerates the kinetics of lesion expansion, the onset of
pain behaviors, and the peripheral immune response to
spinal cord injury. Endogenous
IL-10 and low doses of exogenous
IL-10 are neuroprotective at 1 and 7 days following injury. Therefore, the results of the current study suggest that low dose
IL-10 administration acutely following
spinal cord injury has potential as a therapeutic agent for limiting tissue loss following injury.