Rapid and Efficient Gene Editing for Direct Transplantation of Naive Murine Cas9+ T Cells.

Gene editing of primary T cells is a difficult task. However, it is important for research and especially for clinical T-cell transfers. CRISPR/Cas9 is the most powerful gene-editing technique. It has to be applied to cells by either retroviral transduction or electroporation of ribonucleoprotein complexes. Only the latter is possible with resting T cells. Here, we make use of Cas9 transgenic mice and demonstrate nucleofection of pre-stimulated and, importantly, of naive CD3+ T cells with guideRNA only. This proved to be rapid and efficient with no need of further selection. In the mixture of Cas9+CD3+ T cells, CD4+ and CD8+ conventional as well as regulatory T cells were targeted concurrently. IL-7 supported survival and naivety in vitro, but T cells were also transplantable immediately after nucleofection and elicited their function like unprocessed T cells. Accordingly, metabolic reprogramming reached normal levels within days. In a major mismatch model of GvHD, not only ablation of NFATc1 and/or NFATc2, but also of the NFAT-target gene IRF4 in naïve primary murine Cas9+CD3+ T cells by gRNA-only nucleofection ameliorated GvHD. However, pre-activated murine T cells could not achieve long-term protection from GvHD upon single NFATc1 or NFATc2 knockout. This emphasizes the necessity of gene-editing and transferring unstimulated human T cells during allogenic hematopoietic stem cell transplantation.

Bone marrow-derived myeloid progenitors in the leptomeninges of adult mice.

Although the bone marrow contains most hematopoietic activity during adulthood, hematopoietic stem and progenitor cells can be recovered from various extramedullary sites. Cells with hematopoietic progenitor properties have even been reported in the adult brain under steady-state conditions, but their nature and localization remain insufficiently defined. Here, we describe a heterogeneous population of myeloid progenitors in the leptomeninges of adult C57BL/6 mice. This cell pool included common myeloid, granulocyte/macrophage, and megakaryocyte/erythrocyte progenitors. Accordingly, it gave rise to all major myelo-erythroid lineages in clonogenic culture assays. Brain-associated progenitors persisted after tissue perfusion and were partially inaccessible to intravenous antibodies, suggesting their localization behind continuous blood vessel endothelium such as the blood-arachnoid barrier. Flt3Cre lineage tracing and bone marrow transplantation showed that the precursors were derived from adult hematopoietic stem cells and were most likely continuously replaced via cell trafficking. Importantly, their occurrence was tied to the immunologic state of the central nervous system (CNS) and was diminished in the context of neuroinflammation and ischemic stroke. Our findings confirm the presence of myeloid progenitors at the meningeal border of the brain and lay the foundation to unravel their possible functions in CNS surveillance and local immune cell production.

The mere physical presence of another person reduces human autonomic responses to aversive sounds.

Social animals show reduced physiological responses to aversive events if a conspecific is physically present. Although humans are innately social, it is unclear whether the mere physical presence of another person is sufficient to reduce human autonomic responses to aversive events. In our study, participants experienced aversive and neutral sounds alone (alone treatment) or with an unknown person that was physically present without providing active support. The present person was a member of the participants' ethnical group (ingroup treatment) or a different ethnical group (outgroup treatment), inspired by studies that have found an impact of similarity on social modulation effects. We measured skin conductance responses (SCRs) and collected subjective similarity and affect ratings. The mere presence of an ingroup or outgroup person significantly reduced SCRs to the aversive sounds compared with the alone condition, in particular in participants with high situational anxiety. Moreover, the effect was stronger if participants perceived the ingroup or outgroup person as dissimilar to themselves. Our results indicate that the mere presence of another person was sufficient to diminish autonomic responses to aversive events in humans, and thus verify the translational validity of basic social modulation effects across different species.

Characterization of blood-brain barrier integrity in a B-cell-dependent mouse model of multiple sclerosis.

Recent studies with B-cell-depleting antibodies have demonstrated clinical success in the treatment of multiple sclerosis (MS) patients. While these antibodies efficiently target B cells in the blood, it is unclear how effective they are in the central nervous system (CNS), especially in the context of limited blood-brain barrier (BBB) permeability and the ongoing discussion on the relevance of B-cell aggregate formation in the brains of SP-MS patients. The aim of this study was to evaluate BBB integrity in the context of B-cell-dependent neuroinflammation in a mouse model of MS. C57BL/6 mice were actively immunized with either myelin oligodendrocyte glycoprotein peptide 35-55 to induce T-cell-dependent experimental autoimmune encephalomyelitis (EAE), or with the myelin basic protein-proteolipid protein fusion protein MP4 for additional B-cell dependence. BBB integrity was assessed using Evans Blue or fluorescein isothiocyanate-dextran injection, respectively, in combination with immunofluorescence staining for key components of the BBB. In both EAE models, tracer leakage into the CNS parenchyma was observed indicating BBB leakiness. Yet, intensity and distribution patterns of leakage differed between the two models. There was no difference in the severity of BBB damage comparing acute and chronic MP4-induced EAE, but the formation of B-cell aggregates was associated with local BBB impairment in this model. This study underscores that a leaky BBB is a characteristic feature of EAE, but it also suggests that extent and region specificity of BBB damage differs between individual EAE models that vary in the underlying immunopathology.

Lymphoid Aggregates in the CNS of Progressive Multiple Sclerosis Patients Lack Regulatory T Cells.

In gray matter pathology of multiple sclerosis, neurodegeneration associates with a high degree of meningeal inflammatory activity. Importantly, ectopic lymphoid follicles (eLFs) were identified at the inflamed meninges of patients with progressive multiple sclerosis. Besides T lymphocytes, they comprise B cells and might elicit germinal center (GC)-like reactions. GC reactions are controlled by FOXP3+ T-follicular regulatory cells (TFR), but it is unknown if they participate in autoantibody production in eLFs. Receiving human post-mortem material, gathered from autopsies of progressive multiple sclerosis patients, indeed, distinct inflammatory infiltrates enriched with B cells could be detected in perivascular areas and deep sulci. CD35+ cells, parafollicular CD138+ plasma cells, and abundant expression of the homing receptor for GCs, CXCR5, on lymphocytes defined some of them as eLFs. However, they resembled GCs only in varying extent, as T cells did not express PD-1, only few cells were positive for the key transcriptional regulator BCL-6 and ongoing proliferation, whereas a substantial number of T cells expressed high NFATc1 like GC-follicular T cells. Then again, predominant cytoplasmic NFATc1 and an enrichment with CD3+CD27+ memory and CD4+CD69+ tissue-resident cells implied a chronic state, very much in line with PD-1 and BCL-6 downregulation. Intriguingly, FOXP3+ cells were almost absent in the whole brain sections and CD3+FOXP3+ TFRs were never found in the lymphoid aggregates. This also points to less controlled humoral immune responses in those lymphoid aggregates possibly enabling the occurrence of CNS-specific autoantibodies in multiple sclerosis patients.