Serotonergic dysfunction impairs locomotor coordination in spinal muscular atrophy.

Neuromodulation by serotonin regulates the activity of neuronal networks responsible for a wide variety of essential behaviours. Serotonin (or 5-HT) typically activates metabotropic G protein-coupled receptors, which in turn initiate second messenger signalling cascades and induce short and long-lasting behavioural effects. Serotonin is intricately involved in the production of locomotor activity and gait control for different motor behaviours. Although dysfunction of serotonergic neurotransmission has been associated with mood disorders and spasticity after spinal cord injury, whether and to what extent such dysregulation is implicated in movement disorders has not been firmly established. Here, we investigated whether serotonergic neuromodulation is affected in spinal muscular atrophy (SMA), a neurodegenerative disease caused by ubiquitous deficiency of the SMN protein. The hallmarks of SMA are death of spinal motor neurons, muscle atrophy and impaired motor control, both in human patients and mouse models of disease. We used a severe mouse model of SMA, that closely recapitulates the severe symptoms exhibited by type I SMA patients, the most common and most severe form of the disease. Together, with mouse genetics, optogenetics, physiology, morphology and behavioural analysis, we report severe dysfunction of serotonergic neurotransmission in the spinal cord of SMA mice, both at early and late stages of the disease. This dysfunction is followed by reduction of 5-HT synapses on vulnerable motor neurons. We demonstrate that motor neurons innervating axial and trunk musculature are preferentially affected, suggesting a possible cause for the proximo-distal progression of disease, and raising the possibility that it may underlie scoliosis in SMA patients. We also demonstrate that the 5-HT dysfunction is caused by SMN deficiency in serotonergic neurons in the raphe nuclei of the brainstem. The behavioural significance of the dysfunction in serotonergic neuromodulation is underlined by inter-limb discoordination in SMA mice, which is ameliorated when selective restoration of SMN in 5-HT neurons is achieved by genetic means. Our study uncovers an unexpected dysfunction of serotonergic neuromodulation in SMA and indicates that, if normal function is to be restored under disease conditions, 5-HT neuromodulation should be a key target for therapeutic approaches.

Impact of the first wave of the COVID-19 pandemic on systemic lupus erythematosus patients: Results from a multi-center prospective cohort.

OBJECTIVE: The aim of this study was to evaluate the initial impact of the COVID-19 pandemic on individuals with systemic lupus erythematosus (SLE). METHODS: Patients with SLE participating in a multi-center longitudinal cohort study in New York and Boston were invited to complete a supplemental web-based questionnaire in the summer of 2020. Participants completed standardized patient-reported outcome (PRO) measures and a combination of Likert scale and open-ended questions exploring the impact of the COVID-19 pandemic on their health and access to health care. Changes in PROs were evaluated with paired t-tests and frequencies of worsened symptoms were calculated. A thematic qualitative analysis was conducted on free text responses. RESULTS: Of 97 patients invited, 63 (65%) completed a supplemental questionnaire. Nearly 50% of respondents exhibited increases in anxiety (47.5%) and depression (48.3%) and over 40% scored worse in measures of pain interference, fatigue, and cognitive abilities. Respondents with pre-existing diagnoses of anxiety did not differ from other participants in PRO scores, but were more than three times as likely to report worsened health status. Patients denied difficulties accessing medications (85%) or medical care (84%) and over 50% participated in telehealth visits. Anxiety and increased health risks due to immunosuppression were recurring themes in free text responses. CONCLUSIONS: SLE patients experienced a significant physical and emotional toll in the initial months of the COVID-19 pandemic. Comprehensive patient-centered care, including monitoring and addressing anxiety and health-related quality of life, is critical to improving health outcomes in this population during the ongoing health crisis.