Contribution of spinal galectin-3 to acute herpetic allodynia in mice

To identify endogenous factors involved in herpetic pain, we performed genome-wide microarray analysis of the spinal cord of mice that suffered from herpetic allodynia induced by inoculation with herpes simplex virus type 1, which revealed marked induction of galectin-3, a β-galactoside-binding lectin. Therefore, we investigated the role of galectin-3 in herpetic allodynia. The expression levels of galectin-3 mRNA and protein were increased with a temporal pattern similar to that of herpetic allodynia. Galectin-3-expressing cells were mainly localized in the superficial dorsal horn, round in shape, and positive for the macrophage/microglia markers Iba-1 and F4/80. In the deep dorsal horn, there were Iba-1-positive cells with ramified and stout processes, which were negative for galectin-3. In the superficial dorsal horn, there were many CD3-positive T cells, but most of the galectin-3-expressing cells were negative for CD3. Galectin-3-expressing cells were negative for the neuronal marker NeuN and the astrocyte marker glial fibrillary acidic protein antibody. Deficiency in galectin-3 markedly reduced herpetic allodynia, without showing an effect on herpes zoster-like skin lesions. Intrathecal injection of galectin-3 produced mechanical allodynia in naive mice, and intrathecal injections of anti-galectin-3 antibodies significantly reduced herpetic allodynia. The present results suggest that galectin-3 in infiltrating macrophages and/or resident microglia in the spinal dorsal horn contributes to herpetic allodynia. Galectin-3 may be a new therapeutic target for the treatment of herpes zoster-associated pain.