Wnt signaling in the pathogenesis of human HIV-associated pain syndromes

Many synaptic plasticity-related signaling pathways have been identified as important regulators of the pathogenesis of chronic pain in animal models. However, their relevance to human pathological pain is rarely confirmed rigorously. Recent studies suggest that Wnt signaling plays critical roles in synaptic plasticity and is dysregulated in the spinal cord dorsal horn (SDH) of different mouse pain models. In this study, we compared the protein levels of Wnt ligands, Wnt receptors and their downstream effector proteins in the SDH from non-HIV patients, HIV patients who developed chronic pain ('pain-positive' HIV patients), and HIV patients who did not develop chronic pain ('pain-negative' HIV patients). Our results indicate that many Wnt ligands and downstream effector proteins were specifically up-regulated in the SDH of 'pain-positive' HIV patients but not in the 'pain-negative' HIV patients. These findings describe an HIV pain-associated activation of Wnt signaling in the SDH of human patients. Given the established role of Wnt signaling in the regulation of synaptic plasticity, these results suggest that the activated Wnt signaling might contribute to the expression of the synaptic plasticity in the SDH during the pathogenesis of HIV-associated chronic pain.