Abstract Neuroimmune signals regulate neuronal function and survival. We have strong evidence indicating that activation of the heterodimeric interleukin-13 receptor alpha 1/interleukin-4 receptor alpha (IL-13Rα1/IL-4Rα) complex in midbrain dopaminergic (DA) neurons affects their viability. In the brain, IL-13Rα1/IL-4Rα is uniquely expressed on the neurons of the substantia nigra pars compacta (SNc) that are lost in Parkinson’s disease (PD). We also showed that interleukin 13 (IL-13), produced during neuroinflammation by microglia and neurons, can modulate the activity of dopaminergic cells and increase their susceptibility to oxidative damage. To date, there is a gap in understanding how neuroinflammation contributes to the selective loss of DA neurons in PD. Having established that activation of IL-13Rα1 signaling can affect the survival of dopaminergic neurons during neuroinflammation, in the present application we wish to address this gap. Specifically, we wish to test the hypothesis that IL-13 and neuronal IL-13Rα1 cause damage by stimulating a regulated cell death pathway called ferroptosis. We also wish to determine to what extent IL-13 and IL-13Rα1 contribute to neurodegeneration in a mouse model of alpha- synucleinopathy (α-Syn), a hallmark trait of PD that is associated with neuroinflammation and oxidative damage. This will help us determine whether targeting IL-13Rα1 signaling might be a viable approach to slow neurodegeneration in humans affected by α-synucleinopathy such as PD. The ability of ruxolitinib, an FDA- approved drug that inhibits IL-13Rα1 signaling and that of the novel ferroptosis inhibitor CMS121, to reduce IL- 13-mediated damage in vivo will also be tested. Finally, we propose in vivo experiments un a novel mouse model to test the hypothesis that a rare genetic variant of IL-13 found in individuals diagnosed with early-onset PD can contribute to more rapid loss of dopaminergic neurons in a mouse with the homologue of this mutation. If successful, these experiments will provide strong support for the hypothesis that IL-13 and IL-13Rα1 are novel targets for preventing PD or slowing its progression, at least in a sub-set of PD patients.

Narrative Neuroinflammation is believed to contribute to the onset and/or progression of neurodegenerative diseases. We propose experiments to test the hypothesis that during neuroinflammation, the cytokine IL-13 contributes to the loss of dopaminergic neurons, which express its receptor, IL-13Rα1. The originality and significance of this work lie in the hypothesis that an anti-inflammatory cytokine can contribute to neurodegeneration. This represents a paradigm shift from the current view that anti-inflammatory cytokines are invariably neuroprotective and provide a mechanism that explains the selective loss of dopaminergic neurons in PD. The data collected may also open novel therapeutic strategies. If successful, these experiments will make a significant contribution to the field of neurodegenerative disorders by showing IL-13, IL-13Rα1 and their signaling are potential novel targets for preventing Parkinson’s disease or slowing its progression, at least in a subset of patients.