Delineating the role of E-selectin in vincristine-induced peripheral neuropathy

Abstract

Chemotherapy-induced peripheral neuropathy (CIPN) is a prevalent and debilitating adverse effect of cancer treatment, affecting a substantial proportion of patients undergoing chemotherapy. Vincristine, a widely used drug in the treatment of haematological and brain malignancies, is particularly associated with high rates of neuropathy, especially in children. The resulting sensory, motor and autonomic disturbances substantially impair patient quality of life and frequently necessitate dose reduction or discontinuation of chemotherapy, thereby compromising treatment outcomes. Despite its prevalence and impact, vincristine-induced peripheral neuropathy (VIPN) remains without effective preventive or therapeutic strategies, largely due to limited understanding of the underlying mechanisms. Traditionally, VIPN has been regarded as a neuron-centric disorder, arising from direct neurotoxicity caused by disruption of microtubule dynamics and axonal transport. More recent work, however, highlights the importance of neuroimmune and neurovascular mechanisms. In particular, immune cell infiltration into dorsal root ganglia (DRG) and peripheral nerves, coupled with activation of inflammatory pathways such as the NLRP3 inflammasome, have emerged as a key driver of this condition. Endothelial adhesion molecules are increasingly recognised as upstream regulators of these processes, orchestrating leukocyte recruitment across the blood–nerve barrier. Interestingly, preliminary data from our laboratory demonstrated that genetic deletion of endothelial E-selectin, an inducible adhesion molecule, abolishes VIPN in mice, strongly implicating E-selectin in macrophage-driven neuroinflammation. The present thesis was therefore designed to delineate the role of E-selectin in VIPN pathogenesis, with a particular focus on its contribution to immune cell recruitment, activation and the development of hypersensitivity. Accordingly, I employed a set of complementary studies spanning methodological development, functional testing and mechanistic investigation. First, a reproducible method for DRG immunohistochemistry was optimised, enabling accurate quantification of immune cell accumulation and supporting subsequent mechanistic investigations (‎Chapter 2). Then, blocking antibodies and knockout models revealed E-selectin as a key mediator of vincristine-induced hypersensitivity and macrophage accumulation at peripheral nerves (‎Chapter 3). Building on this, a novel intraplantar E-selectin injection model demonstrated that local administration of recombinant E-selectin was sufficient to induce macrophage-dependent allodynia, providing direct evidence that E-selectin initiates pro-nociceptive immune responses in vivo (‎Chapter 4). Finally, mechanistic studies showed that E-selectin engagement promotes macrophage adhesion, potentiates NLRP3 inflammasome activation and increases interleukin-1β (IL-1β) release (‎Chapter 5). Collectively, the findings presented here establish E-selectin as a previously unrecognised driver of vincristine-induced neuroinflammation. Rather than acting solely as an adhesion molecule, E-selectin is shown to orchestrate macrophage recruitment while simultaneously amplifying their pro-inflammatory activity, thereby linking vascular activation to nociceptor sensitisation. This work therefore reframes VIPN as not only a consequence of direct axonal toxicity, but also as a pathology rooted in endothelial–immune interactions and provides the first mechanistic evidence that E-selectin contributes directly to its development. More broadly, this work highlights E-selectin as a novel regulator of endothelial–immune communication in the peripheral nervous system. While the studies herein focus on VIPN, the implications extend to other neuropathic conditions in which macrophage recruitment and vascular activation are implicated. Importantly, the identification of E-selectin as a mechanistic driver of macrophage-mediated hypersensitivity provides a foundation for future studies to explore context-dependent roles of E-selectin and assess the therapeutic potential of targeting E-selectin in neuropathic pain.