UC San Diego

It is appreciated that in certain conditions, the acute wounding can lead to a chronic pain state. The principal focus of this dissertation is to address the innate and adaptive immune signaling in the primary afferent and dorsal root ganglion. In addition, this work pointed to the importance of dorsal root ganglion (DRG) macrophages, to which I developed novel approaches to assess macrophage function. Finally, these studies aimed towards development of therapeutics with spinal and DRG action, which elucidated the importance of the spinal route of delivery and the current problems presented in his approach. With regard to the initiating aim, the studies contained herein point to the ability of TLR4 to drive the upregulation of Fc gamma receptors in the DRG. This work identified interferon regulatory factor 7 (Irf7) as an important link between TLR4 activation and the expression Fcgr1. The results presented here indicate that Irf7 may represent a potential therapeutic target for preventing/treating painful autoimmune conditions. In the second phase, the importance of DRG macrophages, led to the development of new techniques to study and quantify them in the DRG. I show the power of our techniques with two proof of principle experiments in which we observe macrophage activation in the DRG following intrathecal LPS and following treatment with a chemotherapeutic (cisplatin) that leads to a painful polyneuropathy. Here, I show that we can classify and study novel sub-populations of macrophages in-situ, which coupled to an artificial intelligence learning algorithm permitted systematic 3D analysis of macrophages, revealing a potent activation by innate immune signaling. These techniques enable rapid data acquisition with reduced user input. Finally, in order to address the problems associated with driving intrathecal drug distribution, a problem faced by the implementation of intrathecal therapeutics such as viral vector mediated therapeutics, we developed a novel intrathecal catheter delivery system, the paired multi-valve catheter (PMVC), with which we can increase the regional rostrocaudal distribution of intrathecal injectate through a multiple valve system. I show here that using the PMVC over traditional catheters enables us to use up to 100 fold lower titer of viral vector (AAV9), while achieving better distribution throughout the entire neuraxis. In short, these three linked sets of studies point to novel therapeutic targets (Irf7), the role of innate and adaptive immune signaling in the DRG macrophages and an approach by which such intrathecal therapeutics may be more homogenously delivered along the neuraxis.