Single-cell analysis of anti-BCMA CAR T cell therapy in patients with central nervous system autoimmunity.

Chimeric antigen receptor (CAR) T cell immunotherapy for the treatment of neurological autoimmune diseases is promising, but CAR T cell kinetics and immune alterations after treatment are poorly understood. Here, we performed single-cell multi-omics sequencing of paired cerebrospinal fluid (CSF) and blood samples from patients with neuromyelitis optica spectrum disorder (NMOSD) treated with anti-B cell maturation antigen (BCMA) CAR T cells. Proliferating cytotoxic-like CD8+ CAR T cell clones were identified as the main effectors in autoimmunity. Anti-BCMA CAR T cells with enhanced features of chemotaxis efficiently crossed the blood-CSF barrier, eliminated plasmablasts and plasma cells in the CSF, and suppressed neuroinflammation. The CD44-expressing early memory phenotype in infusion products was potentially associated with CAR T cell persistence in autoimmunity. Moreover, CAR T cells from patients with NMOSD displayed distinctive features of suppressed cytotoxicity compared with those from hematological malignancies. Thus, we provide mechanistic insights into CAR T cell function in patients with neurological autoimmune disease.

CNS Resident Innate Immune Cells: Guardians of CNS Homeostasis.

Although the CNS has been considered for a long time an immune-privileged organ, it is now well known that both the parenchyma and non-parenchymal tissue (meninges, perivascular space, and choroid plexus) are richly populated in resident immune cells. The advent of more powerful tools for multiplex immunophenotyping, such as single-cell RNA sequencing technique and upscale multiparametric flow and mass spectrometry, helped in discriminating between resident and infiltrating cells and, above all, the different spectrum of phenotypes distinguishing border-associated macrophages. Here, we focus our attention on resident innate immune players and their primary role in both CNS homeostasis and pathological neuroinflammation and neurodegeneration, two key interconnected aspects of the immunopathology of multiple sclerosis.

Will cellular immunotherapies end neurodegenerative diseases?

Neurodegenerative disorders present major challenges to global health, exacerbated by an aging population and the absence of therapies. Despite diverse pathological manifestations, they share a common hallmark, loosely termed 'neuroinflammation'. The prevailing dogma is that the immune system is an active contributor to neurodegeneration; however, recent evidence challenges this. By analogy with road construction, which causes temporary closures and disruptions, the immune system's actions in the central nervous system (CNS) might initially appear destructive, and might even cause harm, while aiming to combat neurodegeneration. We propose that the application of cellular immunotherapies to coordinate the immune response towards remodeling might pave the way for new modes of tackling the roadblocks of neurodegenerative diseases.

Astrocytes ACLYmate to chronic neuroinflammation.

Astrocytes are essential cells of the mammalian central nervous system (CNS), with key roles in development, homeostasis, and disease. Lee and colleagues recently showed that astrocytes can develop epigenetic memory, which enhances proinflammatory responses to subsequent stimulation, potentially driving sustained neurological disease pathology, such as in multiple sclerosis (MS).

The Smoothened agonist SAG Modulates the Male and Female Peripheral Immune Systems Differently in an Immune Model of Central Nervous System Demyelination.

Both Hedgehog and androgen signaling pathways are known to promote myelin regeneration in the central nervous system. Remarkably, the combined administration of agonists of each pathway revealed their functional cooperation towards higher regeneration in demyelination models in males. Since multiple sclerosis, the most common demyelinating disease, predominates in women, and androgen effects were reported to diverge according to sex, it seemed essential to assess the existence of such cooperation in females. Here, we developed an intranasal formulation containing the Hedgehog signaling agonist SAG, either alone or in combination with testosterone. We show that SAG promotes myelin regeneration and presumably a pro-regenerative phenotype of microglia, thus mimicking the effects previously observed in males. However, unlike in males, the combined molecules failed to cooperate in the demyelinated females, as shown by the level of functional improvement observed. Consistent with this observation, SAG administered in the absence of testosterone amplified peripheral inflammation by presumably activating NK cells and thus counteracting a testosterone-induced reduction in Th17 cells when the molecules were combined. Altogether, the data uncover a sex-dependent effect of the Hedgehog signaling agonist SAG on the peripheral innate immune system that conditions its ability to cooperate or not with androgens in the context of demyelination.

Venous-plexus-associated lymphoid hubs support meningeal humoral immunity.

There is increasing interest in how immune cells in the meninges-the membranes that surround the brain and spinal cord-contribute to homeostasis and disease in the central nervous system1,2. The outer layer of the meninges, the dura mater, has recently been described to contain both innate and adaptive immune cells, and functions as a site for B cell development3-6. Here we identify organized lymphoid structures that protect fenestrated vasculature in the dura mater. The most elaborate of these dural-associated lymphoid tissues (DALT) surrounded the rostral-rhinal confluence of the sinuses and included lymphatic vessels. We termed this structure, which interfaces with the skull bone marrow and a comparable venous plexus at the skull base, the rostral-rhinal venolymphatic hub. Immune aggregates were present in DALT during homeostasis and expanded with age or after challenge with systemic or nasal antigens. DALT contain germinal centre B cells and support the generation of somatically mutated, antibody-producing cells in response to a nasal pathogen challenge. Inhibition of lymphocyte entry into the rostral-rhinal hub at the time of nasal viral challenge abrogated the generation of germinal centre B cells and class-switched plasma cells, as did perturbation of B-T cell interactions. These data demonstrate a lymphoid structure around vasculature in the dura mater that can sample antigens and rapidly support humoral immune responses after local pathogen challenge.

Quantifying microglial morphology: an insight into function.

Microglia are specialized immune cells unique to the central nervous system (CNS). Microglia have a highly plastic morphology that changes rapidly in response to injury or infection. Qualitative and quantitative measurements of ever-changing microglial morphology are considered a cornerstone of many microglia-centric research studies. The distinctive morphological variations seen in microglia are a useful marker of inflammation and severity of tissue damage. Although a wide array of damage-associated microglial morphologies has been documented, the exact functions of these distinct morphologies are not fully understood. In this review, we discuss how microglia morphology is not synonymous with microglia function, however, morphological outcomes can be used to make inferences about microglial function. For a comprehensive examination of the reactive status of a microglial cell, both histological and genetic approaches should be combined. However, the importance of quality immunohistochemistry-based analyses should not be overlooked as they can succinctly answer many research questions.

Lactate limits CNS autoimmunity by stabilizing HIF-1α in dendritic cells.

Dendritic cells (DCs) have a role in the development and activation of self-reactive pathogenic T cells1,2. Genetic variants that are associated with the function of DCs have been linked to autoimmune disorders3,4, and DCs are therefore attractive therapeutic targets for such diseases. However, developing DC-targeted therapies for autoimmunity requires identification of the mechanisms that regulate DC function. Here, using single-cell and bulk transcriptional and metabolic analyses in combination with cell-specific gene perturbation studies, we identify a regulatory loop of negative feedback that operates in DCs to limit immunopathology. Specifically, we find that lactate, produced by activated DCs and other immune cells, boosts the expression of NDUFA4L2 through a mechanism mediated by hypoxia-inducible factor 1α (HIF-1α). NDUFA4L2 limits the production of mitochondrial reactive oxygen species that activate XBP1-driven transcriptional modules in DCs that are involved in the control of pathogenic autoimmune T cells. We also engineer a probiotic that produces lactate and suppresses T cell autoimmunity through the activation of HIF-1α-NDUFA4L2 signalling in DCs. In summary, we identify an immunometabolic pathway that regulates DC function, and develop a synthetic probiotic for its therapeutic activation.

Dopamine, Immunity, and Disease.

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Immunosuppression by opioids: Mechanisms of action on innate and adaptive immunity.

Opioids are excellent analgesics for the clinical treatment of various types of acute and chronic pain, particularly cancer-related pain. Nevertheless, it is well known that opioids have some nasty side effects, including immunosuppression, which is commonly overlooked. As a result, the incidence of opportunistic bacterial and viral infections increases in patients with long-term opioid use. Nowadays, there are no effective medications to alleviate opioid-induced immunosuppression. Understanding the underlying molecular mechanism of opioids in immunosuppression can enable researchers to devise effective therapeutic interventions. This review comprehensively summarized the exogenous opioids-induced immunosuppressive effects and their underlying mechanisms, the regulatory roles of endogenous opioids on the immune system, the potential link between opioid immunosuppressive effect and the function of the central nervous system (CNS), and the future perspectives in this field.

Characterization of Macrophage-Tropic HIV-1 Infection of Central Nervous System Cells and the Influence of Inflammation.

HIV-1 infection within the central nervous system (CNS) includes evolution of the virus, damaging inflammatory cascades, and the involvement of multiple cell types; however, our understanding of how Env tropism and inflammation can influence CNS infectivity is incomplete. In this study, we utilize macrophage-tropic and T cell-tropic HIV-1 Env proteins to establish accurate infection profiles for multiple CNS cells under basal and interferon alpha (IFN-α) or lipopolysaccharide (LPS)-induced inflammatory states. We found that macrophage-tropic viruses confer entry advantages in primary myeloid cells, including monocyte-derived macrophage, microglia, and induced pluripotent stem cell (iPSC)-derived microglia. However, neither macrophage-tropic or T cell-tropic HIV-1 Env proteins could mediate infection of astrocytes or neurons, and infection was not potentiated by induction of an inflammatory state in these cells. Additionally, we found that IFN-α and LPS restricted replication in myeloid cells, and IFN-α treatment prior to infection with vesicular stomatitis virus G protein (VSV G) Envs resulted in a conserved antiviral response across all CNS cell types. Further, using RNA sequencing (RNA-seq), we found that only myeloid cells express HIV-1 entry receptor/coreceptor transcripts at a significant level and that these transcripts in select cell types responded only modestly to inflammatory signals. We profiled the transcriptional response of multiple CNS cells to inflammation and found 57 IFN-induced genes that were differentially expressed across all cell types. Taken together, these data focus attention on the cells in the CNS that are truly permissive to HIV-1, further highlight the role of HIV-1 Env evolution in mediating infection in the CNS, and point to limitations in using model cell types versus primary cells to explore features of virus-host interaction. IMPORTANCE The major feature of HIV-1 pathogenesis is the induction of an immunodeficient state in the face of an enhanced state of inflammation. However, for many of those infected, there can be an impact on the central nervous system (CNS) resulting in a wide range of neurocognitive defects. Here, we use a highly sensitive and quantitative assay for viral infectivity to explore primary and model cell types of the brain for their susceptibility to infection using viral entry proteins derived from the CNS. In addition, we examine the ability of an inflammatory state to alter infectivity of these cells. We find that myeloid cells are the only cell types in the CNS that can be infected and that induction of an inflammatory state negatively impacts viral infection across all cell types.

NFIL3 deficiency alleviates EAE through regulating different immune cell subsets.

INTRODUCTION: The transcription factor NFIL3 exerts comprehensive effects on the immune system. Previous studies revealed that NFIL3 is related to the function and development of different immune cell subsets. Experimental autoimmune encephalomyelitis (EAE) is mediated by immune cells which results in inflammatory demyelination in the central nervous system (CNS). However, how NFIL3 affects EAE has not been thoroughly studied. OBJECTIVES: The current study aimed to investigate how NFIL3 affects EAE, especially the changes of T cells and dendritic cells as well as the crosstalk between them. METHODS: We used NFIL3-/- mice and C57BL/6J mice (wildtype) to establish MOG35-55-induced EAE. The clinical scores were recorded daily. The immune cells within and outside the CNS of EAE mice were analyzed by flow cytometry. Histology was used to evaluated the neuroinflammation and demyelination in the CNS. Besides, CD11c+ dendritic cells (DCs) were cocultured with T cells and the interplay was measured. RESULTS: At the peak of EAE, Th17 cells decreased within the CNS accompanying with lower clinical scores and milder neuroinflammation and demyelination in NFIL3 knockout EAE mice. Outside the CNS, PD-1 and ICOS on CD4+T cells increased, whereas Th2, Th9, CD8+CD103+T cells and GM-CSF+CD4+T cells decreased. Besides, the pro-inflammatory capacity of NFIL3-/- CD11c+ dendritic cells was impaired while the anti-inflammatory capacity was promoted. CONCLUSIONS: This study suggests that NFIL3 deficiency could alleviate MOG35-55-induced EAE through regulating different immune cell subsets, which is not only related with adaptive immunity and innate immunity, but also related with the cross-talk between them, especially CD4+ T cells and CD11c+ dendritic cells.

Specification of CNS macrophage subsets occurs postnatally in defined niches.

All tissue-resident macrophages of the central nervous system (CNS)-including parenchymal microglia, as well as CNS-associated macrophages (CAMs1) such as meningeal and perivascular macrophages2-7-are part of the CNS endogenous innate immune system that acts as the first line of defence during infections or trauma2,8-10. It has been suggested that microglia and all subsets of CAMs are derived from prenatal cellular sources in the yolk sac that were defined as early erythromyeloid progenitors11-15. However, the precise ontogenetic relationships, the underlying transcriptional programs and the molecular signals that drive the development of distinct CAM subsets in situ are poorly understood. Here we show, using fate-mapping systems, single-cell profiling and cell-specific mutants, that only meningeal macrophages and microglia share a common prenatal progenitor. By contrast, perivascular macrophages originate from perinatal meningeal macrophages only after birth in an integrin-dependent manner. The establishment of perivascular macrophages critically requires the presence of arterial vascular smooth muscle cells. Together, our data reveal a precisely timed process in distinct anatomical niches for the establishment of macrophage subsets in the CNS.

CSF-1 maintains pathogenic but not homeostatic myeloid cells in the central nervous system during autoimmune neuroinflammation.

The receptor for colony stimulating factor 1 (CSF-1R) is important for the survival and function of myeloid cells that mediate pathology during experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). CSF-1 and IL-34, the ligands of CSF-1R, have similar bioactivities but distinct tissue and context-dependent expression patterns, suggesting that they have different roles. This could be the case in EAE, given that CSF-1 expression is up-regulated in the CNS, while IL-34 remains constitutively expressed. We found that targeting CSF-1 with neutralizing antibody halted ongoing EAE, with efficacy superior to CSF-1R inhibitor BLZ945, whereas IL-34 neutralization had no effect, suggesting that pathogenic myeloid cells were maintained by CSF-1. Both anti­CSF-1 and BLZ945 treatment greatly reduced the number of monocyte-derived cells and microglia in the CNS. However, anti­CSF-1 selectively depleted inflammatory microglia and monocytes in inflamed CNS areas, whereas BLZ945 depleted virtually all myeloid cells, including quiescent microglia, throughout the CNS. Anti­CSF-1 treatment reduced the size of demyelinated lesions and microglial activation in the gray matter. Lastly, we found that bone marrow­derived immune cells were the major mediators of CSF-1R­dependent pathology, while microglia played a lesser role. Our findings suggest that targeting CSF-1 could be effective in ameliorating MS pathology, while preserving the homeostatic functions of myeloid cells, thereby minimizing risks associated with ablation of CSF-1R­dependent cells.

Innate Lymphoid Cells in the Central Nervous System.

Immune cells are present within the central nervous system and play important roles in neurological inflammation and disease. As relatively new described immune cell population, Innate Lymphoid Cells are now increasingly recognized within the central nervous system and associated diseases. Innate Lymphoid Cells are generally regarded as tissue resident and early responders, while conversely within the central nervous system at steady-state their presence is limited. This review describes the current understandings on Innate Lymphoid Cells in the central nervous system at steady-state and its borders plus their involvement in major neurological diseases like ischemic stroke, Alzheimer's disease and Multiple Sclerosis.

Ionic mitigation of CD4+ T cell metabolic fitness, Th1 central nervous system autoimmunity and Th2 asthmatic airway inflammation by therapeutic zinc.

T helper (Th) cells provide immunity to pathogens but also contribute to detrimental immune responses during allergy and autoimmunity. Th2 cells mediate asthmatic airway inflammation and Th1 cells are involved in the pathogenesis of multiple sclerosis. T cell activation involves complex transcriptional networks and metabolic reprogramming, which enable proliferation and differentiation into Th1 and Th2 cells. The essential trace element zinc has reported immunomodulatory capacity and high zinc concentrations interfere with T cell function. However, how high doses of zinc affect T cell gene networks and metabolism remained so far elusive. Herein, we demonstrate by means of transcriptomic analysis that zinc aspartate (UNIZINK), a registered pharmaceutical infusion solution with high bioavailability, negatively regulates gene networks controlling DNA replication and the energy metabolism of murine CD3/CD28-activated CD4+ T cells. Specifically, in the presence of zinc, CD4+ T cells show impaired expression of cell cycle, glycolytic and tricarboxylic acid cycle genes, which functionally cumulates in reduced glycolysis, oxidative phosphorylation, metabolic fitness and viability. Moreover, high zinc concentrations impaired nuclear expression of the metabolic transcription factor MYC, prevented Th1 and Th2 differentiation in vitro and reduced Th1 autoimmune central nervous system (CNS) inflammation and Th2 asthmatic airway inflammation induced by house dust mites in vivo. Together, we find that higher zinc doses impair the metabolic fitness of CD4+ T cells and prevent Th1 CNS autoimmunity and Th2 allergy.

Sex differences regulate immune responses in experimental autoimmune encephalomyelitis and multiple sclerosis.

MS is an autoimmune disease of the CNS that afflicts over 2.5 million people worldwide. There are striking sex differences in the susceptibility to and progression of this disease in humans. Females are twice as likely to develop MS than males, whereas disease progression and disability is more rapid in males compared with females; however, the latter is still controversial. There is growing evidence, mainly from animal models, that innate and adaptive immune responses are different in males and females, and that this can influence the outcome of a range of diseases including infection, cancer, and autoimmunity. Since MS is an immune-mediated disease, sex differences in pathogenic immune responses may account for some of the differences in susceptibility to and progression seen in men versus women. Indeed, data from the mouse model of MS, EAE, have already provided some evidence that female mice have earlier disease onset associated with stronger Th17 responses. This review will discuss the possible immunological basis of sex differences in susceptibility and disease outcome in EAE and MS and how a better understanding of sex differences in the responses to disease-modifying therapies may lead to improved patient treatment.

Microglia Do Not Restrict SARS-CoV-2 Replication following Infection of the Central Nervous System of K18-Human ACE2 Transgenic Mice.

Unlike SARS-CoV-1 and MERS-CoV, infection with SARS-CoV-2, the viral pathogen responsible for COVID-19, is often associated with neurologic symptoms that range from mild to severe, yet increasing evidence argues the virus does not exhibit extensive neuroinvasive properties. We demonstrate SARS-CoV-2 can infect and replicate in human iPSC-derived neurons and that infection shows limited antiviral and inflammatory responses but increased activation of EIF2 signaling following infection as determined by RNA sequencing. Intranasal infection of K18 human ACE2 transgenic mice (K18-hACE2) with SARS-CoV-2 resulted in lung pathology associated with viral replication and immune cell infiltration. In addition, ∼50% of infected mice exhibited CNS infection characterized by wide-spread viral replication in neurons accompanied by increased expression of chemokine (Cxcl9, Cxcl10, Ccl2, Ccl5 and Ccl19) and cytokine (Ifn-λ and Tnf-α) transcripts associated with microgliosis and a neuroinflammatory response consisting primarily of monocytes/macrophages. Microglia depletion via administration of colony-stimulating factor 1 receptor inhibitor, PLX5622, in SARS-CoV-2 infected mice did not affect survival or viral replication but did result in dampened expression of proinflammatory cytokine/chemokine transcripts and a reduction in monocyte/macrophage infiltration. These results argue that microglia are dispensable in terms of controlling SARS-CoV-2 replication in in the K18-hACE2 model but do contribute to an inflammatory response through expression of pro-inflammatory genes. Collectively, these findings contribute to previous work demonstrating the ability of SARS-CoV-2 to infect neurons as well as emphasizing the potential use of the K18-hACE2 model to study immunological and neuropathological aspects related to SARS-CoV-2-induced neurologic disease. IMPORTANCE Understanding the immunological mechanisms contributing to both host defense and disease following viral infection of the CNS is of critical importance given the increasing number of viruses that are capable of infecting and replicating within the nervous system. With this in mind, the present study was undertaken to evaluate the role of microglia in aiding in host defense following experimental infection of the central nervous system (CNS) of K18-hACE2 with SARS-CoV-2, the causative agent of COVID-19. Neurologic symptoms that range in severity are common in COVID-19 patients and understanding immune responses that contribute to restricting neurologic disease can provide important insight into better understanding consequences associated with SARS-CoV-2 infection of the CNS.

Acute central nervous system graft-versus-host-disease after liver transplantation.

Acute Central Nervous System (CNS) Graft Versus Host Disease (GvHD) is a rare form of GvHD, only described in case reports. Knowledge about this condition is extrapolated from chronic CNS GvHD cases occurring mostly after hematopoietic stem cell transplantation. GvHD following solid organ transplantation is an unexpected complication. GvHD after liver transplantation has a poor prognosis, and the optimal management is not yet known. Here we describe the case of a 63-year-old man who underwent deceased donor liver transplantation and subsequently developed skin rash, colitis and pancytopenia followed by refractory status epilepticus. Following the identification of lymphocytes of donor origin in the cerebrospinal fluid of the patient, he was diagnosed with acute CNS GvHD. He was treated with an intensive immunosuppressive regimen, but care was withdrawn due to lack of improvement and worsening neurologic prognosis. It is the second known case of acute CNS GvHD following liver transplantation. Clinicians should be aware of this possible, although rare, complication of liver transplantation, especially when there is refractory status epilepticus of unknown origin.