Mechanisms of Pain and Immune Processes

概述：这个转化研究项目涉及与神经性疼痛相关的病理生理过程，慢性疼痛、自身免疫、传染病的潜在融合，以及它们在人类患者中的交叉。慢性神经性疼痛可影响身体的任何部位，可由各种损伤、感染、自身免疫或代谢紊乱（如糖尿病周围神经病变）引起。我们正在验证这样一种假设，即在一些患者中，慢性疼痛是由与周围神经或雪旺细胞或中枢神经系统可能组成部分的蛋白质产生的自身抗体相关的免疫病理过程引发和/或维持的。已知自身抗体是某些大纤维副肿瘤周围神经病变的罪魁祸首，大纤维也可导致神经性感觉障碍。如果疼痛是一个组成部分，我们假设存在针对小直径痛觉（伤害性）C-或a - δ神经纤维产生的神经末梢蛋白质的自身抗体。为了验证疼痛性神经性疾病与自身免疫性成分有关的假设，我们建立了一种灵敏、定量的液相发光试验，使用重组蛋白抗原-荧光素酶融合物作为在哺乳动物细胞中表达后获得的示踪剂。这项研究的目标是了解(a)潜在的人类慢性疼痛疾病的分子和细胞生物学机制，以及(b)利用这些知识来设计新的治疗方法和诊断方法，以适应疼痛和其他疾病。

Overview: This translational research program addresses pathophysiological processes related to neuropathic pain and the potential confluence of chronic pain, autoimmunity, infectious diseases, and their intersection in human patients. Chronic neuropathic pain can affect any part of the body and can occur due to a variety of insults, infections, autoimmune or metabolic disorders (e.g., diabetic peripheral neuropathy). We are testing the hypothesis that, in some patients, chronic pain is initiated and/or maintained by immunopathological processes related to autoantibodies generated against proteins in peripheral nerve or Schwann cells or possibly components of the central nervous system. Autoantibodies are known culprits in certain large fiber paraneoplastic peripheral neuropathies and large fibers can also contribute to neuropathic dysesthesias. Where pain is a component, we hypothesize the presence of autoantibodies to proteins found in nerve endings arising from small diameter pain-sensing (nociceptive) C- or A-delta nerve fibers. To test the hypothesis that painful neuropathic conditions have an autoimmune component, we established a sensitive, quantitative, liquid phase luminescence assay that uses recombinant protein antigen-luciferase fusions as tracers obtained after expression in mammalian cells. The goals of this research are to understand (a) potential molecular and cell biological mechanisms underlying human chronic pain disorders, and (b) to use this knowledge to devise new treatments and diagnostics for pain and other disorders to which it can be adapted. The methodology we established, the luciferase immunoprecipitation systems (LIPS) assay, robustly and sensitively detects antibodies in serum, plasma, cerebrospinal fluid, or saliva. Our early investigations evaluated a range of diseases and disorders that antibodies play a role in, including viral and bacterial infections with and without nervous system involvement and autoimmune disorders that have nervous system symptomology in subsets of patients. In many neural autoimmune disorders, the major autoantigens are frequently plasma membrane receptors or ion channels (Burbelo et al., 2016). Our aim is to determine if the LIPS assay can detect auto-antibodies to these proteins in appropriate chronic pain patients. For example, we completed a study on shingles (herpes zoster) and patients in which shingles evolved into a painful neurological disorder called post-herpetic neuralgia (PHN). We detected some neutralizing anti-cytokine autoantibodies in a subpopulation of Zoster patients, and, interestingly, all of the patients with antibodies had PHN. This is important because it suggests that some patients with PHN may require additional intervention to control the disorder other than just analgesic medications. In a recent publication we demonstrated both HSV1 transcripts and HSV1 antibodies in post-mortem human trigeminal ganglion and whole blood, respectively. The correspondence between titer and transcript was 100%. The fact that we used RNA-seq allowed us to align the HSV1 reads to the HSV1 genome and all of the transcripts aligned with the HSV1 latency associated transcript (LAT), indicating that none of the subjects had viral re-activation at the time of death. We can use this approach as a component in a larger study of headache and migraine. One of the most compelling aspects of this project is its broad applicability and the progressive layering and evolution of the datasets. As we increase the number of test antigens, and assay across conditions and diseases, we assemble comprehensive evaluations of immune and autoimmune responses. This is accomplished by determination of (a) the extent and specificity of immune response to orthologous proteins and protein fragments, (b) overlap in antigen profiles indicative of common denominators or general mechanisms, and (c) antigenicity within an entire signaling pathway involved in inter- or intracellular communication. Eventually, full multiple antigen profiling can be implemented to obtain a deeper level of understanding of the immune component of many complex human disease states. Our recent review summarizes our current thinking on pathogenic autoantibodies. Nearly all autoimmune disorders for which the autoantibody has a pathogenic action show that the antibodies target either a secreted peptide or protein or the extracellular domain of an integral plasma membrane protein. The latter are usually transmembrane signaling proteins. We can now focus on the extracellular domains of transmembrane ion channels and receptors and enzymes in the search for antigenic targets. This concept greatly simplifies the search for antigens that may participate in generating or sustaining a chronic neuropathic pain condition.