蠕虫来源的免疫调控性糖分子LNFPⅢ抑制周围性神经病理性疼痛及其细胞分子机制研究

Peripheral inflammation and immunity is critically involved in acute induction and chronic transition of peripheral neuropathic pain (PNP). However, due to the lack of the ideal approaches to modulate peripheral inflammation and immunity for PNP treatment, the resulting analgesic effects and the underlying mechanisms for this kind of PNP interventions remain largely unclear. Recent studies indicated that helminth-derived immunomodulatory glycan Lacto-N-fucopentaose III (LNFPIII) can significantly inhibit the inflammatory activation of hematogenous macrophages and shift subset differentiation of CD4+ T from inflammatory subsets Th1 and Th17 to anti-inflammatory subsets Th2 and Treg. In our preliminary experiments, we found, for the first time, that early systematic administration of LNFPIII significantly impaired acute induction and chronic transition of PNP after adult rat tibial nerve permanent transection. Therefore, the specific aims of this study are: Aim 1: To confirm the impairment of PNP by early systematic administration of LNFPIII after adult rat tibial nerve permanent transection; Aim 2: To show the changes of peripheral inflammation and immunity after early systematic administration of LNFPIII; Aim 3: To elucidate the changes of pain-associated activation of glial cells after early systematic administration of LNFPIII. This study will develop the idea that peripheral inflammation and immunity is a novel potential target in therapeutic development for PNP. In addition, this study will provide a novel lead compound for drug development of PNP and a new pattern for drug discovery based on helminth infection and immunity.

外周炎症和免疫反应参与周围性神经病理性疼痛的急性诱发和慢性转化，但是如何调节外周炎症和免疫反应以镇痛及其效果和机制目前尚不清楚。有研究发现蠕虫来源的免疫调控糖分子Lacto-N-fucopentaose III （LNFPⅢ）具有强烈的免疫调控作用，能抑制血源性巨噬细胞的炎性活化，促进CD4+ T细胞分化成Th2和Treg抗炎性亚型。预实验中我们首次发现早期系统性给予LNFPIII会强烈抑制成年大鼠胫神经永久性横断伤后神经病理性疼痛的急性诱发和慢性转化。为此本项目拟进行：（1）确证早期系统性给予LNFPⅢ的镇痛作用和药物的量效关系；（2）研究早期系统性给予LNFPⅢ对外周炎症和免疫反应的调节作用；（3）揭示早期LNFPⅢ系统性给予对脊髓背角胶质细胞活化的影响。本研究将提示外周炎症和免疫反应是周围性神经病理性疼痛治疗的新型潜在靶点，可望为其药物研发提供理论和实验依据。

神经损伤引起的慢性疼痛是目前公共卫生和临床实践中亟待解决的问题。外周炎症和免疫反应参与神经损伤后神经病理性疼痛的病理发生，但是如何调节外周炎症和免疫反应以防痛及其效果和机制目前尚不清楚。新近研究发现：蠕虫来源的免疫调控糖分子Lacto-N-fucopentaose III （LNFPⅢ）具有强烈的免疫调控作用，矫正树突状细胞的炎性活化，抑制辅助性T（T helper, Th）细胞的炎性活化。在本项目执行过程中我们发现：（1）成年雄、雌大鼠胫神经横断伤后，脾脏和腰部淋巴结中依赖于树突状细胞活化的Th1细胞感觉模式特异性地参与神经损伤后静态和动态触痛的慢性转归。（2）亚急性期系统性给予不可跨血脑屏障的LNFPIII-BSA结合物（损伤后5天，单次，50μg）即可通过LNFPⅢ本身抑制成年雄、雌大鼠胫神经横断伤后静态和动态触痛的慢性转归及脊髓背角胶质细胞（特别是星形胶质细胞）的活化。（3）Th1细胞(即IFNγ+PLZF-CD4+CD8- αβ T细胞)通过选择性浸润背根柔膜参与神经损伤后触痛的慢性转归。（4）亚急性期系统性给予LNFPIII-BSA结合物通过减少脾脏和腰部淋巴结Th1细胞活化和背根柔膜Th1细胞浸润从而抑制神经损伤后触痛的慢性转归。（5）LNFPIII-BSA结合物矫正神经损伤后树突状细胞的炎性活化，可能通过驯化的树突状细胞来源的IL-10和PD-L1减少脾脏和腰部淋巴结Th1细胞活化和背根柔膜Th1细胞浸润，继而抑制神经损伤后触痛的慢性转归。本项目的研究结果揭示了起源于外周免疫器官而后选择性浸润背根柔膜的Th1细胞可作为神经损伤后触痛慢性转归精准预防的潜在靶点及LNFPIII作为其可能的靶向方式，为后续研究奠定了基础。