18 June, 2020
Neuroimmunology elucidate Huntington (Basic Research)
CREATIO CONTINUES TO ADVANCE IN THE FIELD OF NEUROIMMUNOLOGY TO ELUCIDATE THE PATHOPHYSIOLOGY OF HUNTINGTON’S DISEASE
The central aim of all Creatio’s research efforts has always been to elucidate pathophysiology of Huntington’s disease (HD) in order to generate a cure. Current available medications can only help manage the symptoms of HD but can’t prevent the physical, mental and behavioral decline associated with the condition.
After showing the impact of dysregulation in the off-signaling between neurons and microglia through alterations in the temporal expression pattern of CD200-CD200R1, Creatio’s scientists have uncovered the potential implication of another molecular axis linking the immune system to HD. The results have just been published in Frontiers in Cellular Neuroscience. In the healthy brain, microglia, the resident immune cells of the central nervous system, is in a constant surveillant state, continuously scanning the brain environment. This surveillant state is maintained through the interplay between neuron-released ligand fraktaline (FKN) and microglia-expressed receptor CX3CR1. In the brain of HD patients, it is widely known that microglia is activated years before clinical manifestations appear although the nature of such activation and potential beneficial or detrimental impact is still elusive. In the article, Creatio shows that FKN levels are down-regulated levels in the putamen of HD patients, in HD patients-derived hiPSCs and in the striatum of HD mouse models R6/1. Further, automated cell morphology analysis using two-photon confocal microscopy and 3DMorph software allowed to show a non-inflammatory ramified microglial morphology in the striatum of R6/1 mice. These results point toward an abnormal increase in microglial synaptic engulfment in pre-symptomatic HD animals that could contribute to the progressive loss of synapses and striatal dysfunction. Moreover, morphological analysis was complemented by electrophysiological field recordings which demonstrated that a lack of FKN is involved in the striatal synaptic plasticity dysfunction in pre-symptomatic R6/1 mice. Taken together, the results published by Creatio reveal a key role for FKN-CX3CR1 signaling in the pathophysiology of HD : FKN-CX3CR1 signaling deficits in HD lead to abnormal neuron-microglia interactions, which may contribute to the early striatal synaptic plasticity dysfunction characteristic of this neurological disease. Interestingly, increased microglia-mediated engulfment of synaptic material has been described in mouse models of other neurological diseases such as Alzheimer’s, schizophrenia and Rett syndrome. Our results strengthen the idea that excessive microglia-mediated synaptic engulfment leading to synaptic dysfunction could constitute a common pathological mechanism.
Creatio will continue to explore the intricate roles that microglia have in the pathophysiology of HD and other neurological diseases, allowing the exploration of new therapeutic approaches.