Novel expression of MHC class II on DRG neurons can directly activate CD4+ T cells contributing to the resolution of neuropathic pain

由于出现衰弱和疼痛的神经病变，化疗药物通常是剂量有限的，这对成功治疗癌症构成了重大挑战。最近的报道表明，缺乏T细胞的雄性小鼠在紫杉醇（PTX）治疗后出现了延长的机械超敏反应，并且只有静脉注射CD8+而不是CD4+ T细胞才能减少超敏反应。我们的初步体内数据表明，雌性小鼠DRG中的CD4+ T细胞比雄性和去卵巢（OVX）雌性小鼠多2倍，并且PTX诱导的神经元损伤仅在雌激素能力强的雌性小鼠中显著增加DRG中的抗炎CD4+ T细胞。PTX前雌性小鼠CD4+ T细胞耗竭导致PTX后3天机械超敏反应增加。我们的研究结果表明，CD4+ T细胞的激素和性别差异与化疗诱导的周围神经病变（CIPN）的严重程度有关。PTX主要用于治疗绝经后CIPN风险增加的卵巢癌、乳腺癌和非小细胞肺癌患者；因此，预防措施对妇女是非常宝贵的。CD4+ T细胞降低PIPN严重程度的机制尚不清楚。在我们的初步研究中，雌性小鼠的DRG神经元具有激活CD4+ T细胞分泌抗炎细胞因子的能力。已发表的DRG神经元RNA-seq数据集显示，DRG神经元表达MHCII，一种直接参与T细胞活化的蛋白质。我们的中心假设是，雌性小鼠给予PTX增加感觉神经元上的MHCII，刺激常驻CD4+ T细胞分泌抗炎细胞因子以抑制CIPN。在Aim 1中，我们将确定雌激素驱动的CD4+ T细胞在多大程度上降低ptx诱导的周围神经病变的严重程度。已知雌激素可诱导血液CD4+ T细胞增殖，但尚不清楚这是否发生在DRG中。我们预测CD4+ T细胞中的雌激素信号会增加DRG中常驻CD4+ T细胞的数量，以分泌抗炎细胞因子来响应PTX。我们期望CD4+ T细胞能改善雌性小鼠的CIPN，而不是雄性小鼠。在Aim 2中，我们将量化PTX增强DRG神经元上的MHCII以诱导抗炎CD4+ T细胞细胞因子产生的程度。我们预测ptx诱导的炎症会增加神经元MHCII，从而引发雌性小鼠DRG中的抗炎CD4+ T细胞反应，而雄性小鼠则不会。在Aim 3中，我们将确定神经保护性CD4+ T细胞在体内激活的程度，以减轻和逆转ptx诱导的周围神经病变。我们预测，激活的CD4+ T细胞会抑制和逆转雌性小鼠的CIPN，而不是雄性小鼠，除非预先用雌激素治疗。这些目标的完成将提供令人信服的证据，证明女性DRG中的CD4+ T细胞具有神经保护和抗伤害性，可以用来预防或解决CIPN。神经元mhcii依赖的CD4+ T细胞激活代表了一种新的神经免疫通讯机制，可用于治疗干预。

Chemotherapeutic agents are often dose limiting due to the emergence of a debilitating and painful neuropathy, posing a major challenge to the successful treatment of cancer. Recent reports demonstrate that male mice lacking T cells have prolonged mechanical hypersensitivity after treatment with paclitaxel (PTX), and only the intravenous transfer of CD8+, but not CD4+, T cells reduced the hypersensitivity. Our preliminary in vivo data demonstrates female mice have 2-fold more CD4+ T cells in the DRG than male and ovariectomized (OVX) female mice, and neuronal injury induced by PTX robustly increases antinflammatory CD4+ T cells in the DRG only in estrogen-competent female mice. CD4+ T cell depletion in female mice prior to PTX results in an increase in mechanical hypersensitivity 3 days post-PTX. Our results suggest a previously unexplored hormone and sex difference in CD4+ T cells and the severity of chemotherapy-induced peripheral neuropathy (CIPN). PTX is primarily used to treat ovarian, breast, and non-small cell lung cancer with post-menopausal patients at an increased risk of CIPN; therefore, preventative measures would be invaluable for women. The mechanism by which CD4+ T cells reduce the severity of PIPN is unknown. In our preliminary studies, DRG neurons from female mice have the capacity to activate CD4+ T cells to secrete anti-inflammatory cytokines. Published RNA-seq datasets of DRG neurons show that DRG neurons express MHCII, a protein directly involved in T cell activation. Our central hypothesis is that PTX administration in female mice increases MHCII on sensory neurons to stimulate the paracrine release of anti-inflammatory cytokines by resident CD4+ T cells to suppress CIPN. In Aim 1, we will determine the extent to which estrogen-driven CD4+ T cells reduce the severity of PTX-induced peripheral neuropathy. Estrogen is known to induce proliferation of blood CD4+ T cells, but it is unknown if this occurs in the DRG. We predict that estrogen signaling in CD4+ T cells will increase the number of resident CD4+ T cells in the DRG to secrete anti-inflammatory cytokines in response to PTX. We expect CD4+ T cells to ameliorate CIPN in female, but not male mice. In Aim 2, we will quantify the extent PTX can enhance MHCII on DRG neurons to induce anti-inflammatory CD4+ T cell cytokine production. We predict PTX-induced inflammation will increase neuronal MHCII to elicit an anti-inflammatory CD4+ T cell response in the DRG of female, but not male mice. In Aim 3, we will determine the degree in vivo activation of neuroprotective CD4+ T cells can reduce and reverse PTX-induced peripheral neuropathy. We predict that activated CD4+ T cells will dampen and reverse CIPN in female, but not male mice, unless pre-treated with estrogen. Completion of these aims will provide compelling evidence that CD4+ T cells in the DRG of females are neuroprotective and anti-nociceptive, and can be exploited to prevent or resolve CIPN. Neuronal MHCII-dependent activation of CD4+ T cells represents a novel mechanism for neuro-immune communication that could be utilized for therapeutic intervention.