Polarization of Helper T Lymphocytes Maybe Involved in the Pathogenesis of Lumbar Disc Herniation

This study aimed to explore the expression of T helper type 1 (Th1)/T helper type 2 (Th2) in herniated nucleus pulposus (NP) and determine their association with sciatic pain. NP was collected from 12 patients with lumbar disc herniation (LDH) (extrusion group) and 6 patients with a vertebral fracture (control group). The expression of Th1/Th2 and related cytokines in the NP was examined by flow cytometry, Western blot, and immunofluorescent staining. Subsequently, an LDH model was established in male Sprague–Dawley rats, and behavioral testings were carried out. The expression of Th1/Th2 and related cytokines in rat NP and the expression of macrophages in the dorsal root ganglia (DRG) were also examined. The number of Th1 cells in rat NP dramatically increased on day 14 after the surgery, but significantly decreased on day 28. The number of Th2 cells increased on day 28. Chemokine ligand 3(CCL3) and CD86 proteins (M1-specific molecules) were expressed at a relatively low level in naive DRG, markedly increased on day 14 after the surgery, and decreased on day 28. Arg1 and CD206 protein (M2-specific molecules) were expressed at a relatively low level in naive DRG and markedly increased on day 28. The mechanical allodynia and heat hyperalgesia developed after NP application and finally partially alleviated. The results suggested that the polarization of Th cells might be involved in the pathogenesis of LDH, and this might be achieved via the phenotypic shift of macrophages.