Significance: Neuroinflammation is a hallmark of multiple sclerosis and is linked to neurodegeneration. This study provides pathophysiological insights into the cross-dependency between neuroinflammation and choroid plexus characteristics in both mice and humans. Our work relates an enlargement of choroid plexus volume to ongoing neuroinflammation and emerging clinical disability in two large cohorts of multiple sclerosis patients as well as in two mouse models, the cuprizone diet-related demyelination and the experimental autoimmune encephalomyelitis. Choroid plexus characterization as measured by high-resolution MRI thus represents a reliable and translatable interspecies marker for the quantification of neuroinflammation and disease trajectories that is strongly associated with functional outcomes.

Physical exercise is an effective therapy for improving stroke recovery. However, the exact underlying molecular mechanisms of exercise-enhanced neuronal repair remain unclear. As exercise affects the immune system in healthy individuals, and the immune system in turn influences recovery after stroke, we hypothesized that immune mechanisms play a role in exercise-induced neurological recovery. Using a model of ischemic stroke in adult male mice, we here show that the presence of regulatory T cells (Treg) within the ischemic brain is a prerequisite for exercise-enhanced functional and structural recovery. Treg prevent excessive and sustained hyperexcitability of periinfarct neurons via IL-10 signaling. This reduced hyperexcitability precedes alterations in neuronal connectivity, which underlie functional improvement. Together, we delineate the interaction of exercise-therapy, the immune system and functional recovery after ischemic stroke. Our findings can have translational relevance for further development of immune-targeted therapies.

Introduction: The efficacy of anti-CD20 antibodies has significantly contributed to advancing our understanding of disease pathogenesis and improved treatment outcomes in relapsing-remitting multiple sclerosis (RRMS). A comprehensive analysis of the peripheral immune cell profile, combined with prospective clinical characterization, of RRMS patients treated with ocrelizumab (OCR) or ofatumumab (OFA) was performed to further understand immune reconstitution following B-cell depletion. Methods: REBELLION-MS is a longitudinal analysis of RRMS patients treated with either OCR (n = 34) or OFA (n = 25). Analysis of B, T, natural killer (NK) and natural killer T (NKT) cells at baseline, month 1, and 12 was performed by multidimensional flow cytometry. Data were analyzed by conventional gating and unsupervised computational approaches. In parallel, different clinical parameters were longitudinally assessed. Twenty treatment-naïve age/sex-matched RRMS patients were included as the control cohort. Results: B-cell depletion by OCR and OFA resulted in significant reductions in CD20⁺ T and B cells as well as B-cell subsets, alongside an expansion of CD5⁺CD19⁺CD20⁻ B cells, while also elevating exhaustion markers (CTLA-4, PD-1, TIGIT, TIM-3) across T, B, NK, and NKT cells. Additionally, regulatory T-cell (T_REG) numbers increased, especially in OCR-treated patients, and reductions in double-negative (CD3⁺CD4⁻CD8⁻) T cells (DN T cells) were observed, with these DN T cells having higher CD20 expression compared to CD4 or CD8 positive T cells. These immune profile changes correlated with clinical parameters, suggesting pathophysiological relevance in RRMS. Conclusions: Our interim data add weight to the argumentation that the exhaustion/activation markers, notably TIGIT, may be relevant to the pathogenesis of MS. In addition, we identify a potentially interesting increase in the expression of CD5+ on B cells. Finally, we identified a population of double-negative T cells (KLRG1+HLADR+, in particular) that is associated with MS activity and decreased with CD20 depletion.

K_2P2.1 (gene: Kcnk2), a two-pore-domain potassium channel, regulates leukocyte transmigration across the blood-brain barrier by a yet unknown mechanism. We demonstrate that Kcnk2 ^−/− mouse brain microvascular endothelial cells (MBMECs) exhibit an altered cytoskeletal structure and surface morphology with increased formation of membrane protrusions. Cell adhesion molecules cluster on those protrusions and facilitate leukocyte adhesion and migration in vitro and in vivo. We observe downregulation of K_2P2.1 and activation of actin modulating proteins (cofilin 1, Arp2/3) in inflamed wildtype MBMECs. In the mechanosensitive conformation, K_2P2.1 shields the phospholipid PI(4,5)P₂ from interaction with other actin regulatory proteins, especially cofilin 1. Consequently, after stimulus-related K_2P2.1 downregulation and dislocation from PI(4,5)P₂, actin rearrangements are induced. Thus, K_2P2.1-mediated regulatory processes are essential for actin dynamics, fast, reversible, and pharmacologically targetable.

Osteal macrophages (“osteomacs”) are resident bone macrophages that support osteoblast differentiation and bone formation. Despite their importance in bone homeostasis, their function in human bone metabolism and osteoporosis remains poorly understood, largely due to the lack of a standardized isolation protocol. Here, we present a protocol for isolating primary human osteomacs from femoral head specimens obtained during arthroplasty. After the removal of bone marrow to minimize contamination with marrow-derived macrophages, bone fragments were enzymatically digested and osteomacs were isolated using CD14-based MACS^® or CD14/CD45/ALP-based FACS. Immunofluorescence confirmed macrophage identity and revealed expression of markers associated with both M1-like and M2-like activation states. Isolated cells displayed heterogeneous morphology and could be maintained in culture. This protocol enables reproducible isolation of human osteomacs and provides a foundation for translational studies investigating osteoimmune interactions in bone disease and osteoporosis.

The chapter deals with the conceptual foundations around causation in Germany, such as philosophical and theoretical principles informing the law, i.e. theories of causation, including the influence of feminist and queer theory. It explains the differences between factual and so-called legal causation, i.e. the basic principles of the “but for” test or conditio sine qua non, including its application to omission liability. Legal causation covers, inter alia, issues such as novus actus interveniens, contributory acts of the victim in particular, alternative and cumulative causes, lack of creation of a legally relevant danger, risk diminishment, hypothetical identical causation of result by third-party intervention, autonomous self-endangerment and decisions made by committee. The interplay with the mens rea of the defendant will be studied at the example of the correspondence principle, the so-called thin skull rule, general mistakes about the imagined chain of causation and antecedent fault or actio libera in causa. <!----> <!----> <!----> <!---->