Search

The article focuses on the role of the calcium channel β3 subunit (CACNB3) in regulating Adenosine Triphosphate (ATP) dependent migration of dendritic cells (DCs). Topics include the exclusive expression of CACNB3 in migratory DCs, its role in ATP-induced calcium release from the endoplasmic reticulum, and how CACNB3 regulates the suppression of adhesion molecules.

Objective: Autologous hematopoietic stem cell transplantation (aHSCT) is increasingly recognized as a potential therapy for patients with highly active multiple sclerosis (MS). This study aims to assess outcome differences in disease activity in MS patients treated either with aHSCT or alemtuzumab. Methods: We conducted a monocentric registry‐based cohort study by recording the clinical course (EDSS and relapses), MRI parameters (new T2 lesions), and neuropsychological assessment in all 19 MS patients receiving aHSCT, and all 21 patients receiving alemtuzumab between 2007 and 2018. We used survival analyses of no evidence of disease activity (NEDA) as the primary objective which was defined by no EDSS progression, no relapse, and no new T2 lesion on MRI. Secondary objectives were EDSS improvement and neurocognitive performance. Results: Both treatment groups were similar in respect of age, gender, disability, and neurocognitive performance except for significantly longer disease duration in the alemtuzumab group. Mean follow‐up was 58.8 [range 29–140] months in the aHSCT group compared to 27.6 [range 11–52] months in the alemtuzumab‐treated group. We observed significantly more patients maintaining NEDA in the aHSCT group (p = 0.048) compared to the alemtuzumab‐treated patients. Furthermore, 37% of the aHSCT patients showed an improvement of EDSS compared to none in the alemtuzumab‐treated group (p = 0.033). It is of note that cognitive function was significantly improved in the aHSCT‐treated patients. Interpretation: aHSCT suppresses inflammatory activity more effectively than alemtuzumab and might enable improvement of overall disability and cognition in MS. [ABSTRACT FROM AUTHOR]

Dendritic cell (DC) vaccination has proven to be an effective and safe adjuvant for cancer immunotherapies. As the presence of DCs within the tumor microenvironment promotes adaptive antitumor immunity, enhancement of DC migration toward the tumor microenvironment following DC vaccination might represent one possible approach to increase its therapeutic efficacy. While recent findings suggest the activity-regulated cytoskeleton-associated protein/activity-regulated gene 3.1 (Arc/Arg3.1) as critical regulator of DC migration in the context of autoimmune diseases, we aimed to investigate the impact of Arc/Arg3.1 expression for DC-based cancer vaccines. To this end, DC migration capacity as well as the induction of T cell-mediated antitumor immunity was assessed in an experimental B16 melanoma model with Arc/Arg3A-/- and Arc/Arg3.1-expressing BMDCs applied as a subcutaneous vaccine. While antigen presentation on DCs was critical for unleashing effective T cell mediated antitumor immune responses, Arc/Arg3.1 expression enhanced DC migration toward the tumor and secondary lymphoid organs. Moreover, Arc/Arg3.1-expressing BMDCs shape the tumor immune microenvironment by facilitating tumor recruitment of antigen-specific effector T cells. Thus, Arc/Arg3.1 may represent a novel therapeutic target in DCs in order to increase the therapeutic efficacy of DC vaccination. [ABSTRACT FROM AUTHOR]

The key function of migratory dendritic cells (migDCs) is to take up antigens in peripheral tissues and migrate to draining lymph nodes (dLN) to initiate immune responses. Recently, we discovered that in the mouse immune system activity‐regulated cytoskeleton associated protein/activity‐regulated gene 3.1 (Arc/Arg3.1) is exclusively expressed by migDCs and is a central driver of fast inflammatory migration. However, the frequency of Arc/Arg3.1‐expressing cells in different migDC subsets and Langerhans cells (LCs), their phylogenetic origin, transcription factor dependency, and functional role remain unclear. Here, we found that Arc/Arg3.1+ migDCs derived from common DC precursors and radio‐resistant LCs. We detected Arc/Arg3.1+ migDCs in varying frequencies within each migDC subset and LCs. Consistently, they showed superiority in inflammatory migration. Arc/Arg3.1 expression was independent of the transcription factors Irf4 or Batf3 in vivo. In intradermal Staphylococcus aureus infection that relies on inflammatory antigen transport, Arc/Arg3.1 deletion reduced T‐cell responses. By contrast, Arc/Arg3.1 deficiency did not hamper the immune response to systemic Listeria monocytogenes infection, which does not require antigen transport. Thus, Arc/Arg3.1 expression is independent of ontogeny and phenotype and although it is restricted to a small fraction within each migDC subset and LCs, Arc/Arg3.1+ migDCs are important to facilitate infectious migration. [ABSTRACT FROM AUTHOR]

Recent findings indicate a pathogenic involvement of IL-17-producing CD8+ T cells in multiple sclerosis (MS). IL-17 production has been attributed to a subset of CD8+ T cells that belong to the mucosal-associated invariant T (MAIT) cell population. Here, we report a reduction of CD8+ MAIT cells in the blood of MS patients compared with healthy individuals, which significantly correlated with IL-18 serum levels in MS patients. In vitro stimulation of peripheral blood mononuclear cells from healthy individuals and MS patients with IL-18 specifically activated CD8+ MAIT cells. Moreover, IL-18 together with T-cell receptor stimulation induced, specifically on CD8+ MAIT cells, an upregulation of the integrin very late antigen-4 that is essential for the infiltration of CD8+ T cells into the CNS. Notably, we were able to identify CD8+ MAIT cells in MS brain lesions by immunohistochemistry while they were almost absent in the cerebrospinal fluid (CSF). In summary, our findings indicate that an IL-18-driven activation of CD8+ MAIT cells contributes to their CNS infiltration in MS, in turn leading to reduced CD8+ MAIT-cell frequencies in the blood. Therefore, CD8+ MAIT cells seem to play a role in the innate arm of immunopathology in MS. [ABSTRACT FROM AUTHOR]

The voltage-gated proton channel Hv1 regulates proton fluxes across membranes, thereby influencing pH-dependent processes. Plasmacytoid dendritic cells (pDCs) require a particularly tight regulation of endosomal pH to ensure strong type I IFN secretion exclusively during infection, avoiding autoimmunity. However, whether Hv1 is important for pH control in pDCs is presently unknown. In this study, we show that mouse pDCs require Hv1 to achieve potent type I IFN responses after the recognition of foreign DNA by endosomal TLR9. Genetic disruption of Hvcn1, which encodes Hv1, impaired mouse pDC activation by CpG oligonucleotides in vitro and in vivo, reducing IFN-a secretion and the induction of IFN-stimulated genes. Mechanistically, Hvcn1 deficiency delayed endosomal acidification and enhanced intracellular reactive oxygen species production, consequently limiting protease activity and TLR9 signaling. Our study reveals a critical role of Hv1 during innate immune responses and places this channel as a key modulator of type I IFN production, the hallmark function of pDCs, commending Hv1 as an attractive target for modulating type I IFN-driven autoimmunity. [ABSTRACT FROM AUTHOR]

The ability of CD4+ T cells to differentiate into pathogenic Th1 and Th17 or protective T regulatory cells plays a pivotal role in the pathogenesis of autoimmune diseases. Recent data suggest that CD4+ T cell subsets display a considerable plasticity. This plasticity seems to be a critical factor for their pathogenicity, but also for the potential transition of pathogenic effector T cells toward a more tolerogenic phenotype. The aim of the current study was to analyze the plasticity of Th17 cells in a mouse model of acute crescentic glomerulonephritis and in a mouse chronic model of lupus nephritis. By transferring in vitro generated, highly purified Th17 cells and by using IL-17A fate reporter mice, we demonstrate that Th17 cells fail to acquire substantial expression of the Th1 and Th2 signature cytokines IFN-γ and IL-13, respectively, or the T regulatory transcription factor Foxp3 throughout the course of renal inflammation. In an attempt to therapeutically break the stability of the Th17 phenotype in acute glomerulonephritis, we subjected nephritic mice to CD3-specific Ab treatment. Indeed, this treatment induced an immunoregulatory phenotype in Th17 cells, which was marked by high expression of IL-10 and attenuated renal tissue damage in acute glomerulonephritis. In summary, we show that Th17 cells display a minimum of plasticity in acute and chronic experimental glomerulonephritis and introduce anti-CD3 treatment as a tool to induce a regulatory phenotype in Th17 cells in the kidney that may be therapeutically exploited. [ABSTRACT FROM AUTHOR]

Dendritic cell (DC) vaccination has proven to be an effective and safe adjuvant for cancer immunotherapies. As the presence of DCs within the tumor microenvironment promotes adaptive antitumor immunity, enhancement of DC migration toward the tumor microenvironment following DC vaccination might represent one possible approach to increase its therapeutic efficacy. While recent findings suggest the activity-regulated cytoskeleton-associated protein/activity-regulated gene 3.1 (Arc/Arg3.1) as critical regulator of DC migration in the context of autoimmune diseases, we aimed to investigate the impact of Arc/Arg3.1 expression for DC-based cancer vaccines. To this end, DC migration capacity as well as the induction of T cell-mediated antitumor immunity was assessed in an experimental B16 melanoma model with Arc/Arg3.1 -/- and Arc/Arg3.1 -expressing BMDCs applied as a subcutaneous vaccine. While antigen presentation on DCs was critical for unleashing effective T cell mediated antitumor immune responses, Arc/Arg3.1 expression enhanced DC migration toward the tumor and secondary lymphoid organs. Moreover, Arc/Arg3.1-expressing BMDCs shape the tumor immune microenvironment by facilitating tumor recruitment of antigen-specific effector T cells. Thus, Arc/Arg3.1 may represent a novel therapeutic target in DCs in order to increase the therapeutic efficacy of DC vaccination., (© 2021 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with continuous neuronal loss. Treatment of clinical progression remains challenging due to lack of insights into inflammation-induced neurodegenerative pathways. Here, we show that an imbalance in the neuronal receptor interactome is driving glutamate excitotoxicity in neurons of MS patients and identify the MS risk-associated metabotropic glutamate receptor 8 (GRM8) as a decisive modulator. Mechanistically, GRM8 activation counteracted neuronal cAMP accumulation, thereby directly desensitizing the inositol 1,4,5-trisphosphate receptor (IP3R). This profoundly limited glutamate-induced calcium release from the endoplasmic reticulum and subsequent cell death. Notably, we found Grm8-deficient neurons to be more prone to glutamate excitotoxicity, whereas pharmacological activation of GRM8 augmented neuroprotection in mouse and human neurons as well as in a preclinical mouse model of MS. Thus, we demonstrate that GRM8 conveys neuronal resilience to CNS inflammation and is a promising neuroprotective target with broad therapeutic implications., Competing Interests: Disclosures:   M.A. Friese reported personal fees from Novartis, personal fees from Roche, personal fees from Merck EMD, and personal fees from Biogen outside the submitted work. No other disclosures were reported., (© 2021 Woo et al.)

Neuropsychiatric complications associated with coronavirus disease 2019 caused by the Coronavirus SARS-CoV-2 (COVID-19) are increasingly appreciated. While most studies have focussed on severely affected individuals during acute infection, it remains unclear whether mild COVID-19 results in neurocognitive deficits in young patients. Here, we established a screening approach to detect cognitive deficiencies in post-COVID-19 patients. In this cross-sectional study, we recruited 18 mostly young patients 20-105 days (median, 85 days) after recovery from mild to moderate disease who visited our outpatient clinic for post-COVID-19 care. Notably, 14 (78%) patients reported sustained mild cognitive deficits and performed worse in the Modified Telephone Interview for Cognitive Status screening test for mild cognitive impairment compared to 10 age-matched healthy controls. While short-term memory, attention and concentration were particularly affected by COVID-19, screening results did not correlate with hospitalization, treatment, viremia or acute inflammation. Additionally, Modified Telephone Interview for Cognitive Status scores did not correlate with depressed mood or fatigue. In two severely affected patients, we excluded structural or other inflammatory causes by magnetic resonance imaging, serum and cerebrospinal fluid analyses. Together, our results demonstrate that sustained sub-clinical cognitive impairments might be a common complication after recovery from COVID-19 in young adults, regardless of clinical course that were unmasked by our diagnostic approach., (© The Author(s) (2020). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Recent findings indicate a pathogenic involvement of IL-17-producing CD8(+) T cells in multiple sclerosis (MS). IL-17 production has been attributed to a subset of CD8(+) T cells that belong to the mucosal-associated invariant T (MAIT) cell population. Here, we report a reduction of CD8(+) MAIT cells in the blood of MS patients compared with healthy individuals, which significantly correlated with IL-18 serum levels in MS patients. In vitro stimulation of peripheral blood mononuclear cells from healthy individuals and MS patients with IL-18 specifically activated CD8(+) MAIT cells. Moreover, IL-18 together with T-cell receptor stimulation induced, specifically on CD8(+) MAIT cells, an upregulation of the integrin very late antigen-4 that is essential for the infiltration of CD8(+) T cells into the CNS. Notably, we were able to identify CD8(+) MAIT cells in MS brain lesions by immunohistochemistry while they were almost absent in the cerebrospinal fluid (CSF). In summary, our findings indicate that an IL-18-driven activation of CD8(+) MAIT cells contributes to their CNS infiltration in MS, in turn leading to reduced CD8(+) MAIT-cell frequencies in the blood. Therefore, CD8(+) MAIT cells seem to play a role in the innate arm of immunopathology in MS., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)