Background: One of the major challenges in addressing multiple sclerosis is to understand its progression trajectory. The pathological process transitions from acute phases predominantly driven by inflammation to progressive clinical profiles where neurodegeneration takes precedence. It is known that sex plays a crucial role in this heterogeneity; females are two to three times more likely to suffer from multiple sclerosis, while males suffer from more rapid neurodegeneration with greater severity. Results: To gain insight into the sex-based molecular differences, we processed single cell datasets from the central nervous system and the peripheral blood, covering the different courses of multiple sclerosis. We generated cell-type specific landscapes, including gene signatures from differentially expressed genes, functional profiling, pathway activation, and cell-cell communication networks for females, males, and their sex differential profiles. Among our findings, we revealed that female neurons may exhibit protective mechanisms against neurodegeneration. In the inflammatory-predominant forms, female immune cells present an inflammatory core driven by the AP-1 transcription factor, while male adaptive immune cells exhibit higher mitochondrial impairment. Conversely, larger differences are reported in CD8+ T cells progressive forms, with males exhibiting cytolytic profiles that may promote neurodegeneration. Complete results can be explored in the interactive webtool https://bioinfo.cipf.es/cbl-atlas-ms/ . Conclusions: We identified cell-type specific sex differences in brain and immune cells that vary in the spectrum of multiple sclerosis. We consider this molecular description a valuable resource to promote future targeted approaches considering the sex of the individual.

This article summarizes the case of 30-year-old male diagnosed with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and its longitudinal follow-up, which provided a secondary diagnosis of Multiple Sclerosis (MS) eight years later. The most impactful result was his response to rituximab treatment after the systematic failure of prior treatments. Although the expression of endogenous retroviral proteins has been associated with autoimmunity, the patient did not show increased expression of the toxic protein HERV (human endogenous retrovirus)-W ENV, a target of the ongoing clinical trials with temelimab in MS and long COVID-19 cases. However, genome-wide HERV transcriptome analysis by high density microarrays clearly revealed a distinct profile in the patient’s blood supportive of an altered immune system. Limitations of the study include sub-optimal frequency of magnetic resonance imaging to monitor lesion progression, and similarly for reassessment of HERV profiles after rituximab. Overall, the coincidence of HERV alterations and the impactful response to rituximab presents the possibility of additional, more specific, therapeutic targets encoded by other HERV elements yet to be discovered.

Neurological disorders often originate from progressive brain network dysfunctions that start years before symptoms appear. How these changes emerge in the developing human brain remains elusive due to a lack of tractable model systems. Here, we show a cerebral organoid model of Tuberous Sclerosis Complex (TSC) that recapitulates hallmarks of epileptogenesis in vitro. We compare extracellular recordings of TSC organoids with intraoperative electrocorticography from TSC patients to reveal striking functional similarities, including high-frequency oscillations - an electrical biomarker for epileptogenic tissue. In TSC, a human-specific interneuron sub-type derived from the caudal ganglionic eminence drives network hyper-synchronization through increased spontaneous firing and altered excitability. Inhibiting overproliferation of its progenitors via long-term epidermal growth factor receptor inhibition prevented the onset of this pathological phenotype at functional and morphological levels. Our work shows that organoids allow mechanistic analysis of emerging neural network phenotypes, enabling anti-epileptogenic drug testing in a human brain development model.

This case report describes a 38-year-old female patient with a 3-year history of multiple sclerosis who developed rituximab-induced pancolitis, possibly representing a new onset of inflammatory bowel disease. The patient presented with bloody diarrhea, epigastric pain, fever, and general malaise. Laboratory testing revealed elevated acute inflammation markers, and endoscopy showed deep ulcerations and severe perianal disease. The patient was treated effectively with corticosteroids. Monthly doses of ustekinumab have been administered during follow-up due to perianal disease that has remitted. Rituximab was discontinued and ozanimod was initiated with clinical and analytical stability to date.

This article summarizes the case of 30-year-old male diagnosed with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and its longitudinal follow up that provided a secondary diagnosis of Multiple Sclerosis (MS) eight years after. The most impactful result being his response to rituximab treatment after the systematic failure of prior treatments. Although the expression of endogenous retroviral proteins has been associated with autoimmunity, the patient did not show increased expression of the toxic protein HERV (human endogenous retrovirus)-W ENV, a target of the ongoing clinical trials with temelimab in MS and long COVID-19 cases. However, genome-wide HERV transcriptome analysis by high density microarrays clearly revealed a distinct profile in patient´s blood supportive of an altered immune system. Limitations of the study include MRI imaging follow up to monitor lesion progression and reassessment of HERV profiles after rituximab. As an overall, the coincidence of HERV alterations and the impactful response to rituximab presents the possibility of additional, more specific, therapeutic targets encoded by other HERV elements yet to be discovered.