Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
Department of Biological Sciences, University of Denver (currently at Entos Pharmaceuticals), Denver, CO 80210, USA.
Neuropharmacology. 2024 Dec 1;260:110136. doi: 10.1016/j.neuropharm.2024.110136. Epub 2024 Aug 30.
HIV associated neuropathic pain (HANP) is a common complication of AIDS. Intrathecal injection of recombinant HIV-1 gp120 in mice is a well-known model. Previous RNA sequencing revealed spinal TLR2 acts as a differentially expressed gene in HANP mice. The spinal TLR2 is involved in HANP, but its role and underlying mechanism remains unclear. In this study the transcription, expression and distribution characteristics of TLR2 in the spinal cord of HANP male mice have been analyzed by qRT-PCR, Western blotting, and immunofluorescent staining. We found that TLR2 expression was upregulated in the spinal dorsal horn and mainly distributed in microglial cells, and blocking TLR2 relieved pain of HANP mice. Following stimulation by gp120 microglial cells upregulate TLR2 expression and become activated. The activation stimulates their differentiation into the M1 type, increasing IL-1β and TNF-α expression while inhibiting IL-10 expression. Silencing the Tlr2 gene slows down the activation, polarization, and secretion of pro-inflammatory factors in microglial cells induced by gp120, and enhances the expression of anti-inflammatory factors. Further analysis of the impact of gp120 on downstream signaling pathways of TLR2 in microglial cells, including NF-κB, MAPK (p38MAPK, ERK, and JNK) and PI3K/AKT, revealed that TLR2-NF-κB signaling plays a crucial role in the activation and polarization of microglial cells by gp120. Activation of NF-κB signaling aggravates pain in HANP mice, while blocking it lightens pain. This data indicates that gp120, through the TLR2-NF-κB signaling, activates spinal microglial cells, promotes the secretion of inflammatory cytokines, leading to HANP. This provides new targets to develop drugs for HANP.
人类免疫缺陷病毒相关神经病理性疼痛（HANP）是艾滋病的一种常见并发症。在小鼠中鞘内注射重组 HIV-1 gp120 是一种众所周知的模型。先前的 RNA 测序显示，脊髓 TLR2 作为 HANP 小鼠中差异表达的基因。脊髓 TLR2 参与 HANP，但作用及其潜在机制尚不清楚。在这项研究中，通过 qRT-PCR、Western blot 和免疫荧光染色分析了 HANP 雄性小鼠脊髓中 TLR2 的转录、表达和分布特征。我们发现 TLR2 表达在上角上调，主要分布在小胶质细胞中，阻断 TLR2 可缓解 HANP 小鼠的疼痛。gp120 刺激后，TLR2 表达上调，小胶质细胞被激活。这种激活刺激它们分化为 M1 型，增加 IL-1β 和 TNF-α 的表达，同时抑制 IL-10 的表达。沉默 Tlr2 基因会减缓 gp120 诱导的小胶质细胞中促炎因子的激活、极化和分泌，并增强抗炎因子的表达。进一步分析 gp120 对小胶质细胞中 TLR2 下游信号通路的影响，包括 NF-κB、MAPK（p38MAPK、ERK 和 JNK）和 PI3K/AKT，发现 TLR2-NF-κB 信号在 gp120 激活和小胶质细胞极化中起着至关重要的作用。NF-κB 信号的激活加重了 HANP 小鼠的疼痛，而阻断它则减轻了疼痛。这表明 gp120 通过 TLR2-NF-κB 信号激活脊髓小胶质细胞，促进炎症细胞因子的分泌，导致 HANP。这为开发 HANP 药物提供了新的靶点。
