Spatial and single-cell explorations uncover prognostic significance and immunological functions of mitochondrial calcium uniporter in breast cancer

The mitochondrial calcium uniporter (MCU) is a transmembrane protein facilitating the entry of calcium ions into mitochondria from the cell cytosol. Maintaining calcium balance is crucial for enhancing cellular energy supply and regulating cell death. The interplay of calcium balance through MCU and the sodium-calcium exchanger is known, but its regulation in the breast cancer tumor microenvironment remains elusive. Further investigations are warranted to explore MCU's potential in BRCA clinical pathology, tumor immune microenvironment, and precision oncology. Our study, employing a multi-omics approach, identifies MCU as an independent diagnostic biomarker for breast cancer (BRCA), correlated with advanced clinical status and poor overall survival. Utilizing public datasets from GEO and TCGA, we discern differentially expressed genes in BRCA and examine their associations with immune gene expression, overall survival, tumor stage, gene mutation status, and infiltrating immune cells. Spatial transcriptomics is employed to investigate MCU gene expression in various regions of BRCA, while spatial transcriptomics and single-cell RNA-sequencing methods explore the correlation between MCUs and immune cells. Our findings are validated through the analysis of 59 BRCA patient samples, utilizing immunohistochemistry and bioinformatics to examine the relationship between MCU expression, clinicopathological features, and prognosis. The study uncovers the expression of key gene regulators in BRCA associated with genetic variations, deletions, and the tumor microenvironment. Mutations in these regulators positively correlate with different immune cells in six immune datasets, playing a pivotal role in immune cell infiltration in BRCA. Notably, high MCU performance is linked to CD8 + T cells infiltration in BRCA. Furthermore, pharmacogenomic analysis of BRCA cell lines indicates that MCU inactivation is associated with increased sensitivity to specific small molecule drugs. Our findings suggest that MCU alterations may be linked to BRCA progression, unveiling new diagnostic and prognostic implications for MCU in BRCA. The study underscores MCU's role in the tumor immune microenvironment and cell cycle progression, positioning it as a potential tool for BRCA precision medicine and drug screening.

The Plasticity of Immune Cell Response Complicates Dissecting the Underlying Pathology of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease characterized by the destruction of the myelin sheath of the neuronal axon in the central nervous system. Many risk factors, including environmental, epigenetic, genetic, and lifestyle factors, are responsible for the development of MS. It has long been thought that only adaptive immune cells, especially autoreactive T cells, are responsible for the pathophysiology; however, recent evidence has indicated that innate immune cells are also highly involved in disease initiation and progression. Here, we compile the available data regarding the role immune cells play in MS, drawn from both human and animal research. While T and B lymphocytes, chiefly enhance MS pathology, regulatory T cells (Tregs) may serve a more protective role, as can B cells, depending on context and location. Cells chiefly involved in innate immunity, including macrophages, microglia, astrocytes, dendritic cells, natural killer (NK) cells, eosinophils, and mast cells, play varied roles. In addition, there is evidence regarding the involvement of innate-like immune cells, such as γδ T cells, NKT cells, MAIT cells, and innate-like B cells as crucial contributors to MS pathophysiology. It is unclear which of these cell subsets are involved in the onset or progression of disease or in protective mechanisms due to their plastic nature, which can change their properties and functions depending on microenvironmental exposure and the response of neural networks in damage control. This highlights the need for a multipronged approach, combining stringently designed clinical data with carefully controlled in vitro and in vivo research findings, to identify the underlying mechanisms so that more effective therapeutics can be developed.

Current advances in stem cell therapy in the treatment of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease related to the central nervous system (CNS) with a significant global burden. In this illness, the immune system plays an essential role in its pathophysiology and progression. The currently available treatments are not recognized as curable options and, at best, might slow the progression of MS injuries to the CNS. However, stem cell treatment has provided a new avenue for treating MS. Stem cells may enhance CNS healing and regulate immunological responses. Likewise, stem cells can come from various sources, including adipose, neuronal, bone marrow, and embryonic tissues. Choosing the optimal cell source for stem cell therapy is still a difficult verdict. A type of stem cell known as mesenchymal stem cells (MSCs) is obtainable from different sources and has a strong immunomodulatory impact on the immune system. According to mounting data, the umbilical cord and adipose tissue may serve as appropriate sources for the isolation of MSCs. Human amniotic epithelial cells (hAECs), as novel stem cell sources with immune-regulatory effects, regenerative properties, and decreased antigenicity, can also be thought of as a new upcoming contender for MS treatment. Overall, the administration of stem cells in different sets of animal and clinical trials has shown immunomodulatory and neuroprotective results. Therefore, this review aims to discuss the different types of stem cells by focusing on MSCs and their mechanisms, which can be used to treat and improve the outcomes of MS disease.

Acute Downregulation but Not Genetic Ablation of Murine MCU Impairs Suppressive Capacity of Regulatory CD4 T Cells

By virtue of mitochondrial control of energy production, reactive oxygen species (ROS) generation, and maintenance of Ca²⁺ homeostasis, mitochondria play an essential role in modulating T cell function. The mitochondrial Ca²⁺ uniporter (MCU) is the pore-forming unit in the main protein complex mediating mitochondrial Ca²⁺ uptake. Recently, MCU has been shown to modulate Ca²⁺ signals at subcellular organellar interfaces, thus fine-tuning NFAT translocation and T cell activation. The mechanisms underlying this modulation and whether MCU has additional T cell subpopulation-specific effects remain elusive. However, mice with germline or tissue-specific ablation of Mcu did not show impaired T cell responses in vitro or in vivo, indicating that 'chronic' loss of MCU can be functionally compensated in lymphocytes. The current work aimed to specifically investigate whether and how MCU influences the suppressive potential of regulatory CD4 T cells (Treg). We show that, in contrast to genetic ablation, acute siRNA-mediated downregulation of Mcu in murine Tregs results in a significant reduction both in mitochondrial Ca²⁺ uptake and in the suppressive capacity of Tregs, while the ratios of Treg subpopulations and the expression of hallmark transcription factors were not affected. These findings suggest that permanent genetic inactivation of MCU may result in compensatory adaptive mechanisms, masking the effects on the suppressive capacity of Tregs.

Alterations in Lymphocytic Metabolism-An Emerging Hallmark of MS Pathophysiology?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterised by acute inflammation and subsequent neuro-axonal degeneration resulting in progressive neurological impairment. Aberrant immune system activation in the periphery and subsequent lymphocyte migration to the CNS contribute to the pathophysiology. Recent research has identified metabolic dysfunction as an additional feature of MS. It is already well known that energy deficiency in neurons caused by impaired mitochondrial oxidative phosphorylation results in ionic imbalances that trigger degenerative pathways contributing to white and grey matter atrophy. However, metabolic dysfunction in MS appears to be more widespread than the CNS. This review focuses on recent research assessing the metabolism and mitochondrial function in peripheral immune cells of MS patients and lymphocytes isolated from murine models of MS. Emerging evidence suggests that pharmacological modulation of lymphocytic metabolism may regulate their subtype differentiation and rebalance pro- and anti-inflammatory functions. As such, further understanding of MS immunometabolism may aid the identification of novel treatments to specifically target proinflammatory immune responses.

Philosophical Approach to Neural Autoantibodies in Psychiatric Disease-Multi-Systemic Dynamic Continuum from Protective to Harmful Autoimmunity in Neuronal Systems

(1) Background: philosophical views are important to enable a general and multi-systemic view of the potential understanding of autoimmunity in psychiatric disease that is not solely reflected by an immunological viewpoint. (2) Methods: we reviewed current theories of autoimmunity. (3) Results: we propose a novel area view integrating the "self/non-self" and "continuity" model into the expression of varied forms of autoimmunity in psychiatric disease, ranging from protective to harmful autoimmunity consequences framed into micro-systems (nerve cells) and macro-systems (neuronal networks), termed the "multi-systemic dynamic continuum model". (4) Conclusions: autoimmunity's dynamic spectrum is delineated here as something that probably functions as a whole entity to maintain, first of all, human homeostasis in behavior affecting cells or neuronal networks differently, and secondly to prevent psychiatric disease.

The protective role of interaction between vitamin D, sex hormones and calcium in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder that causes disability and paralysis, especially among young adults. Although interactions of several factors, such as viral infections, autoimmunity, genetic and environmental factors, performance a role in the beginning and progression of the disease, the exact cause of MS is unknown to date. Different immune cells such as Th1 and Th17 play an impressive role in the immunopathogenesis of MS, while, regulatory cells such as Th2 and Treg diminish the severity of the illness. Sex hormones have a vital role in many autoimmune disorders, including multiple sclerosis. Testosterone, estrogen and progesterone have various roles in the progress of MS, which higher prevalence of disease in women and more severe in men reveals the importance of sex hormones' role in this disease. Vitamin D after chemical changes in the body, as an active hormone called calcitriol, plays an important role in regulating immune responses and improves MS by modulating the immune system. The optimum level of calcium in the body with vitamin D modulates immune responses and calcium as an essential ion in the body plays a key role in the treatment of autoimmune diseases. The interaction between vitamin D and sex hormones has protective and therapeutic effects against MS and functional synergy between estrogen and calcitriol occurs in disease recovery. Moreover, vitamin D and calcium interact with each other to regulate the immune system and shift them to anti-inflammatory responses.

Increased Intrathecal Activity of Follicular Helper T Cells in Patients With Relapsing-Remitting Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Follicular helper T (Tfh) cells play a critical role in protective immunity helping B cells produce antibodies against foreign pathogens and are likely implicated in the pathogenesis of various autoimmune diseases. The purpose of this study was to investigate the role of Tfh cells in the pathogenesis of multiple sclerosis (MS).

METHODS

Using flow cytometry, we investigated phenotype, prevalence, and function of Tfh cells in blood and CSF from controls and patients with relapsing-remitting MS (RRMS) and primary progressive MS (PPMS). In addition, an in vitro blood-brain barrier coculture assay of primary human astrocytes and brain microvascular endothelial cells grown in a Boyden chamber was used to assess the migratory capacity of peripheral Tfh cells.

RESULTS

This study identified 2 phenotypically and functionally distinct Tfh cell populations: CD25^- Tfh cells (Tfh1-like) and CD25^int Tfh cells (Tfh17-like). Whereas minor differences in Tfh cell populations were found in blood between patients with MS and controls, we observed an increased frequency of CD25^- Tfh cells in CSF of patients with RRMS and PPMS and CD25^int Tfh cells in patients with RRMS, compared with controls. Increasing frequencies of CSF CD25^- Tfh cells and the CD25^- Tfh/Tfr ratio scaled with increasing IgG index in patients with RRMS. Despite an increased prevalence of intrathecal Tfh cells in patients with MS, no difference in the migratory capacity of circulating Tfh cells was observed between controls and patients with MS. Instead, CSF concentrations of CXCL13 scaled with total counts of Tfh and Tfr cell subsets in the CSF.

DISCUSSION

Our study indicates substantial changes in intrathecal Tfh dynamics, particularly in patients with RRMS, and suggests that the intrathecal inflammatory environment in patients with RRMS promotes recruitment of peripheral Tfh cells rather than the Tfh cells having an increased capacity to migrate to CNS.

Influence of Genetic Polymorphisms on Clinical Outcomes of Glatiramer Acetate in Multiple Sclerosis Patients

Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of autoimmune origin, in which inflammation and demyelination lead to neurodegeneration and progressive disability. Treatment is aimed at slowing down the course of the disease and mitigating its symptoms. One of the first-line treatments used in patients with MS is glatiramer acetate (GA). However, in clinical practice, a response rate of between 30% and 55% is observed. This variability in the effectiveness of the medication may be influenced by genetic factors such as polymorphisms in the genes involved in the pathogenesis of MS. Therefore, this review assesses the impact of genetic variants on the response to GA therapy in patients diagnosed with MS. The results suggest that a relationship exists between the effectiveness of the treatment with GA and the presence of polymorphisms in the following genes: CD86, CLEC16A, CTSS, EOMES, MBP, FAS, TRBC1, IL1R1, IL12RB2, IL22RA2, PTPRT, PVT1, ALOX5AP, MAGI2, ZAK, RFPL3, UVRAG, SLC1A4, and HLA-DRB1*1501. Consequently, the identification of polymorphisms in these genes can be used in the future as a predictive marker of the response to GA treatment in patients diagnosed with MS. Nevertheless, there is a lack of evidence for this and more validation studies need to be conducted to apply this information to clinical practice.

Regulatory T cells suppress Th17 cell Ca2+ signaling in the spinal cord during murine autoimmune neuroinflammation

T lymphocyte motility and interaction dynamics with other immune cells are vital determinants of immune responses. Regulatory T (Treg) cells prevent autoimmune disorders by suppressing excessive lymphocyte activity, but how interstitial motility patterns of Treg cells limit neuroinflammation is not well understood. We used two-photon microscopy to elucidate the spatial organization, motility characteristics, and interactions of endogenous Treg and Th17 cells together with antigen-presenting cells (APCs) within the spinal cord leptomeninges in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Th17 cells arrive before the onset of clinical symptoms, distribute uniformly during the peak, and decline in numbers during later stages of EAE. In contrast, Treg cells arrive after Th17 cells and persist during the chronic phase. Th17 cells meander widely, interact with APCs, and exhibit cytosolic Ca²⁺ transients and elevated basal Ca²⁺ levels before the arrival of Treg cells. In contrast, Treg cells adopt a confined, repetitive-scanning motility while contacting APCs. These locally confined but highly motile Treg cells limit Th17 cells from accessing APCs and suppress Th17 cell Ca²⁺ signaling by a mechanism that is upstream of store-operated Ca²⁺ entry. Finally, Treg cell depletion increases APC numbers in the spinal cord and exaggerates ongoing neuroinflammation. Our results point to fundamental differences in motility characteristics between Th17 and Treg cells in the inflamed spinal cord and reveal three potential cellular mechanisms by which Treg cells regulate Th17 cell effector functions: reduction of APC density, limiting access of Th17 cells to APCs, and suppression of Th17 Ca²⁺ signaling.

Interleukin-27 Enforces Regulatory T Cell Functions to Prevent Graft-versus-Host Disease

Graft-versus-host disease (GvHD) remains a significant complication of allogeneic hematopoietic cell transplantation (HCT), associated with significant morbidity and mortality. GvHD is characterized by dysregulated immune responses and resulting tissue damage of target organs. Recent investigations have focused on Foxp3⁺ regulatory T cells (Tregs) as a therapeutic tool, based on its regulatory functions in GvHD pathogenesis and their instrumental role in mitigating GvHD severity while preserving graft-versus-leukemia (GvL) activity. There are several challenges to its clinical application, including their paucity, impaired suppressive activity, and instability in vivo. Herein, we report that IL-27 pre-stimulation enhances suppressive functions of both mouse and human Tregs. In a complete MHC mismatched murine bone marrow transplant model, IL-27 pre-stimulated polyclonal iTregs diminish acute (a)GvHD lethality, while preserving the GvL effect. Allo-antigen specificity further improves suppressive functions when combined with IL-27 pre-stimulation. In a xenogeneic (human to mouse) GvHD model, IL-27 pre-stimulated human iTregs are superior in protecting recipients from GvHD. Lastly, we compared gene expression profiles of circulating Tregs isolated from HCT recipients with and without aGvHD and found that Tregs from aGvHD patients express distinct gene signatures enriched in immune activation and inflammation. Therefore, these results highlight a novel function of IL-27 in enforcing Treg functions to prevent aGvHD mediated lethality, proposing the hypothesis that dysregulated Treg functions may account for the potential mechanisms underlying GvHD development.

Treg Heterogeneity, Function, and Homeostasis

T-regulatory cells (Tregs) represent a unique subpopulation of helper T-cells by maintaining immune equilibrium using various mechanisms. The role of T-cell receptors (TCR) in providing homeostasis and activation of conventional T-cells is well-known; however, for Tregs, this area is understudied. In the last two decades, evidence has accumulated to confirm the importance of the TCR in Treg homeostasis and antigen-specific immune response regulation. In this review, we describe the current view of Treg subset heterogeneity, homeostasis and function in the context of TCR involvement. Recent studies of the TCR repertoire of Tregs, combined with single-cell gene expression analysis, revealed the importance of TCR specificity in shaping Treg phenotype diversity, their functions and homeostatic maintenance in various tissues. We propose that Tregs, like conventional T-helper cells, act to a great extent in an antigen-specific manner, which is provided by a specific distribution of Tregs in niches.

Alemtuzumab in Multiple Sclerosis: Short- and Long-Term Effects of Immunodepletion on the Peripheral Treg Compartment

Treatment with alemtuzumab is followed by an early increase in Treg frequencies. Whether naïve and memory subsets are differentially affected and how depletion influences dysfunctional MS-Treg is unclear. In this study, we analyzed the effect of alemtuzumab on regulatory T-cells (Treg) in patients with multiple sclerosis (MS). For this purpose 182 blood samples from 25 MS patients were taken shortly before treatment and serially for up to 24 months after two alemtuzumab cycles. We studied Treg by flow cytometry (quantitation, phenotypical characterization), real-time polymerase chain reaction (T-cell receptor (TCR) excision circles [TREC] content), CDR3-spectratyping (clonal distribution), and proliferation assays (suppressive function). CD52-mediated cytolysis of Treg and conventional T-cells was determined by a complement-dependent cytolysis assay. Our studies revealed that 1 week post-alemtuzumab, Treg were depicted at constant frequencies among CD4⁺ T-cells. In contrast, Treg frequencies were massively increased at month 1. Post-depletional Treg exhibited a CD45RO⁺ memory phenotype, a skewed TCR repertoire, and contained minimum TREC numbers. Naïve Treg, thymic markers, and TCR-variability commenced to rise after 6 months but did not attain baseline levels. In vitro, Treg exhibited higher susceptibility to lysis than Tcon. Treg suppressive function constantly increased within 1 year when co-cultured with syngeneic T-cells, but remained stable against allogeneic T-cells from normal donors. Our findings suggest that (1) Treg are not spared from alemtuzumab-mediated depletion and thymopoiesis does not considerably contribute to long-term recovery, (2) either homeostatic proliferation and/or conversion from residual Tcon contributes to Treg expansion during the early post-treatment phase (3) the enhanced inhibitory effect of Treg following alemtuzumab is due to altered composition and reactivity of post-depletional Tcon.

The Multiple Roles of B Cells in Multiple Sclerosis and Their Implications in Multiple Sclerosis Therapies

Increasing evidence has suggested that both antibody-dependent and antibody-independent functions of B cells are involved in multiple sclerosis (MS). The contrasting results of distinct B-cell targeting therapies in MS patients underscores the importance of elucidating these multiple B-cell functions. In this review, we discuss the generation of autoreactive B cells, migration of B cells into the central nervous system (CNS), and how different functions of B cells may contribute to MS disease activity and potentially mitigation in both the periphery and CNS compartments. In addition, we propose several future therapeutic strategies that may better target/shape B-cell responses for long-term treatment of MS.

Phosphatase inhibitor PPP1R11 modulates resistance of human T cells toward Treg-mediated suppression of cytokine expression

Regulatory T cells (Tregs) act as indispensable unit for maintaining peripheral immune tolerance mainly by regulating effector T cells. T cells resistant to suppression by Tregs pose therapeutic challenges in the treatment of autoimmune diseases, while augmenting susceptibility to suppression may be desirable for cancer therapy. To understand the cell intrinsic signals in T cells during suppression by Tregs, we have previously performed a global phosphoproteomic characterization. We revealed altered phosphorylation of protein phosphatase 1 regulatory subunit 11 (PPP1R11; Inhibitor‐3) in conventional T cells upon suppression by Tregs. Here, we show that silencing of PPP1R11 renders T cells resistant toward Treg‐mediated suppression of TCR‐induced cytokine expression. Furthermore, whole‐transcriptome sequencing revealed that PPP1R11 differentially regulates not only the expression of specific T cell stimulation‐induced cytokines but also other molecules and pathways in T cells. We further confirmed the target of PPP1R11, PP1, to augment TCR‐induced cytokine expression. In conclusion, we present PPP1R11 as a novel negative regulator of T cell activation‐induced cytokine expression. Targeting PPP1R11 may have therapeutic potential to regulate the T cell activation status including modulating the susceptibility of T cells toward Treg‐mediated suppression, specifically altering the stimulation‐induced T cell cytokine milieu.

Targeting cytokines secreted by CD4+ CD25high CD127low regulatory T cells inhibits ovarian cancer progression

Epithelial ovarian cancer (EOC) is one of the major malignant cancers with high rates of early metastasis in which regulatory T cells (Tregs) play an important role. Tregs suppress immune responses and promote the development of tumours in patients with EOC. However, the underlying mechanisms remain unclear. In this study, we found higher levels of CD4⁺ CD25^high CD127^low Tregs in patients with EOC than in patients with benign ovarian tumours and healthy donors. The immune inhibitory effect of Tregs functions by maintaining high levels of immunosuppressive cytokines in EOC. The high levels of Tregs and related cytokines (TGF-β1 or IL-10) were associated with lymphatic metastasis and FIGO stages of patients with EOC. Expression of matrix metalloproteinase (MMP)-2 and tissue inhibitors of metalloproteinase (TIMP)-2 in EOC cell lines were significantly regulated in the coculture experiment with CD4⁺ CD25^high CD127^low Tregs sorted from EOC patients. Levels of MMP-2 and TIMP-2 conversely changed after blocking IL-10R and TGF-β1R in EOC cells. The invasion ability of EOC cells was also significantly downregulated in this process. The metastasis of EOC cells was correlated with the levels of TGF-β1 or IL-10. These findings suggested that immunosuppressive cytokines secreted by CD4⁺ Tregs could be a novel target for inhibiting EOC progression.

Serotonin decreases the production of Th1/Th17 cytokines and elevates the frequency of regulatory CD4+ T-cell subsets in multiple sclerosis patients

Excessive levels of proinflammatory cytokines in the CNS are associated with reduced serotonin (5-HT) synthesis, a neurotransmitter with diverse immune effects. In this study, we evaluated the ability of exogenous 5-HT to modulate the T-cell behavior of patients with MS, a demyelinating autoimmune disease mediated by Th1 and Th17 cytokines. Here, 5-HT attenuated, in vitro, T-cell proliferation and Th1 and Th17 cytokines production in cell cultures from MS patients. Additionally, 5-HT reduced IFN-γ and IL-17 release by CD8⁺ T cells. By contrast, 5-HT increased IL-10 production by CD4⁺ T cells from MS patients. A more accurate analysis of these IL-10-secreting CD4⁺ T cells revealed that 5-HT favors the expansion of FoxP3⁺ CD39⁺ regulatory T cells (Tregs) and type 1 regulatory T cells. Notably, this neurotransmitter also elevated the frequency of Treg17 cells, a novel regulatory T-cell subset. The effect of 5-HT in upregulating CD39⁺ Treg and Treg17 cells was inversely correlated with the number of active brain lesions. Finally, in addition to directly reducing cytokine production by purified Th1 and Th17 cells, 5-HT enhanced in vitro Treg function. In summary, our data suggest that serotonin may play a protective role in the pathogenesis of MS.

Profiling calcium signals of in vitro polarized human effector CD4+ T cells

Differentiation of naïve CD4⁺ T cells into effector subtypes with distinct cytokine profiles and physiological roles is a tightly regulated process, the imbalance of which can lead to an inadequate immune response or autoimmune disease. The crucial role of Ca²⁺ signals, mainly mediated by the store operated Ca²⁺ entry (SOCE) in shaping the immune response is well described. However, it is unclear if human effector CD4⁺ T cell subsets show differential Ca²⁺ signatures in response to different stimulation methods. Herein, we provide optimized in vitro culture conditions for polarization of human CD4⁺ effector T cells and characterize their SOCE following both pharmacological store depletion and direct T-cell receptor (TCR) activation. Moreover, we measured whole cell Ca²⁺ release activated Ca²⁺ currents (I_CRAC) and investigated whether the observed differences correlate to the expression of CRAC genes. Our results show that Ca²⁺ profiles of helper CD4⁺ Th1, Th2 and Th17 are distinct and in part shaped by the intensity of stimulation. Regulatory T cells (Treg) are unique being the subtype with the most prominent SOCE response. Analysis of in vivo differentiated Treg unraveled the role of differential expression of ORAI2 in fine-tuning signals in Treg vs. conventional CD4⁺ T cells.

Friend or foe: the dichotomous impact of T cells on neuro-de/re-generation during aging

The interaction between T cells and the central nervous system (CNS) in homeostasis and injury has been recognized being both pathogenic (CD4⁺ T-helper 1 - Th1, Th17 and γδT) and ameliorative (Th2 and regulatory T cells - Tregs). However, in-depth studies aimed to elucidate the precise in the aged microenvironment and the dichotomous role of Tregs have just begun and many aspects remain unclear. This is due, not only to a mutual dependency and reciprocal causation of alterations and diseases between the nervous and T cell immune systems, but also to an inconsistent aging of the two systems, which dynamically changes with CNS injury/recovery and/or aging process. Cellular immune system aging, particularly immunosenescence and T cell aging initiated by thymic involution - sources of chronic inflammation in the elderly (termed inflammaging), potentially induces an acceleration of brain aging and memory loss. In turn, aging of the brain via neuro-endocrine-immune network drives total body systemic aging, including that of the immune system. Therefore, immunotherapeutics including vaccination and “protective autoimmunity” provide promising means to rejuvenate neuro-inflammatory disorders and repair CNS acute injury and chronic neuro-degeneration. We review the current understanding and recent discoveries linking the aging immune system with CNS injury and neuro-degeneration. Additionally, we discuss potential recovery and rejuvenation strategies, focusing on targeting the aging T cell immune system in an effort to alleviate acute brain injury and chronic neuro-degeneration during aging, via the “thymus-inflammaging-neurodegeneration axis”.

Autoimmunity in multiple sclerosis: role of sphingolipids, invariant NKT cells and other immune elements in control of inflammation and neurodegeneration

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is classified as being an autoimmune response in the genetically susceptible individual to a persistent but unidentified antigen(s). Both the adaptive and the innate immune systems are likely to contribute significantly to MS pathogenesis. This review summarizes current understanding of the characteristics of MS autoimmunity in the initiation and progression of the disease. In particular we find it timely to classify the autoimmune responses by focusing on the immunogenic features of myelin-derived lipids in MS including molecular mimicry; on alterations of bioactive sphingolipids mediators in MS; and on functional roles for regulatory effector cells, including innate lymphocyte populations, like the invariant NKT (iNKT) cells which bridge adaptive and innate immune systems. Recent progress in identifying the nature of sphingolipids recognition for iNKT cells in immunity and the functional consequences of the lipid-CD1d interaction opens new avenues of access to the pathogenesis of demyelination in MS as well as design of lipid antigen-specific therapeutics.

Phosphoproteomics Reveals Regulatory T Cell-Mediated DEF6 Dephosphorylation That Affects Cytokine Expression in Human Conventional T Cells

Regulatory T cells (Tregs) control key events of immune tolerance, primarily by suppression of effector T cells. We previously revealed that Tregs rapidly suppress T cell receptor (TCR)-induced calcium store depletion in conventional CD4⁺CD25⁻ T cells (Tcons) independently of IP₃ levels, consequently inhibiting NFAT signaling and effector cytokine expression. Here, we study Treg suppression mechanisms through unbiased phosphoproteomics of primary human Tcons upon TCR stimulation and Treg-mediated suppression, respectively. Tregs induced a state of overall decreased phosphorylation as opposed to TCR stimulation. We discovered novel phosphosites (T595_S597) in the DEF6 (SLAT) protein that were phosphorylated upon TCR stimulation and conversely dephosphorylated upon coculture with Tregs. Mutation of these DEF6 phosphosites abrogated interaction of DEF6 with the IP₃ receptor and affected NFAT activation and cytokine transcription in primary Tcons. This novel mechanism and phosphoproteomics data resource may aid in modifying sensitivity of Tcons to Treg-mediated suppression in autoimmune disease or cancer.

Thymic function in the regulation of T cells, and molecular mechanisms underlying the modulation of cytokines and stress signaling (Review)

The thymus is critical in establishing and maintaining the appropriate microenvironment for promoting the development and selection of T cells. The function and structure of the thymus gland has been extensively studied, particularly as the thymus serves an important physiological role in the lymphatic system. Numerous studies have investigated the morphological features of thymic involution. Recently, research attention has increasingly been focused on thymic proteins as targets for drug intervention. Omics approaches have yielded novel insights into the thymus and possible drug targets. The present review addresses the signaling and transcriptional functions of the thymus, including the molecular mechanisms underlying the regulatory functions of T cells and their role in the immune system. In addition, the levels of cytokines secreted in the thymus have a significant effect on thymic functions, including thymocyte migration and development, thymic atrophy and thymic recovery. Furthermore, the regulation and molecular mechanisms of stress-mediated thymic atrophy and involution were investigated, with particular emphasis on thymic function as a potential target for drug development and discovery using proteomics.

Impact of aging immune system on neurodegeneration and potential immunotherapies

The interaction between the nervous and immune systems during aging is an area of avid interest, but many aspects remain unclear. This is due, not only to the complexity of the aging process, but also to a mutual dependency and reciprocal causation of alterations and diseases between both the nervous and immune systems. Aging of the brain drives whole body systemic aging, including aging-related changes of the immune system. In turn, the immune system aging, particularly immunosenescence and T cell aging initiated by thymic involution that are sources of chronic inflammation in the elderly (termed inflammaging), potentially induces brain aging and memory loss in a reciprocal manner. Therefore, immunotherapeutics including modulation of inflammation, vaccination, cellular immune therapies and "protective autoimmunity" provide promising approaches to rejuvenate neuroinflammatory disorders and repair brain injury. In this review, we summarize recent discoveries linking the aging immune system with the development of neurodegeneration. Additionally, we discuss potential rejuvenation strategies, focusing aimed at targeting the aging immune system in an effort to prevent acute brain injury and chronic neurodegeneration during aging.

Peripherally Induced Regulatory T Cells: Recruited Protectors of the Central Nervous System against Autoimmune Neuroinflammation

Defects in regulatory T cells (Treg cells) aggravate multiple sclerosis (MS) after its onset and the absence of Treg cell functions can also exacerbate the course of disease in an animal model of MS. However, autoimmune neuroinflammation in many MS models can be acutely provoked in healthy animals leading to an activation of encephalitogenic T cells despite the induction of immune tolerance in the thymus including thymically produced (t)Treg cells. In contrast, neuroinflammation can be ameliorated or even completely prevented by the antigen-specific Treg cells formed extrathymically in the peripheral immune system (pTreg cells) during tolerogenic responses to relevant neuronal antigens. This review discusses the specific roles of Treg cells in blocking neuroinflammation, examines the impact of peripheral tolerance and dendritic cells on a relevant regulation of neuroinflammation, and explores some of the most recent advances in elucidation of specific mechanisms of the conversion and function of pTreg cells including the roles of CD5 and Hopx in these processes.

Sequential monitoring of lymphocyte subsets and of T-and-B cell neogenesis indexes to identify time-varying immunologic profiles in relation to graft-versus-host disease and relapse after allogeneic stem cell transplantation

T and B lymphocyte subsets have been not univocally associated to Graft-versus-host disease (GVHD) and relapse of hematological malignancies after stem cell transplantation (SCT). Their sequential assessment together with B and T cell neogenesis indexes has been not thoroughly analysed in relation to these changing and interrelated immunologic/clinic events yet.

Lymphocyte subsets in peripheral blood (PB) and B and T cell neogenesis indexes were analysed together at different time points in a prospective study of 50 patients. Principal component analysis (PCA) was used as first step of multivariate analysis to address issues related to a high number of variables versus a relatively low number of patients. Multivariate analysis was completed by Fine-Gray proportional hazard regression model. PCA identified 3 clusters of variables (PC1-3), which correlated with acute GVHD: PC1 (pre-SCT: KRECs≥6608/ml, unswitched memory B <2.4%, CD4+T_CM cells <45%; HR 0.5, p = 0.001); PC2 (at aGVHD onset: CD4+>44%, CD8+T_CM cells>4%; HR 1.9, p = 0.01), and PC3 (at aGVHD onset: CD4+TEM_RA<1, total Treg<4, Treg_EM <2 cells/μl; HR 0.5, p = 0.002). Chronic GVHD was associated with one PC (Treg_EM <2 cells/μl at day+28, CD8+TEM_RA<43% at day+90, immature B cells<6 cells/μl and KRECs<11710/ml at day+180; HR 0.4, P = 0.001). Two PC correlated with relapse: PC1 (pre-SCT: CD4+ <269, CD4+T_CM <120, total Treg <18, Treg_CM <8 cells/μl; HR 4.0, p = 0.02); PC2 (pre-SCT mature CD19+ >69%, switched memory CD19+ = 0 cells and KRECs<6614/ml at +90; HR 0.1, p = 0.008). All these immunologic parameters were independent indicators of chronic GVHD and relapse, also considering the possible effect of previous steroid-therapy for acute GVHD. Specific time-varying immunologic profiles were associated to GVHD and relapse. Pre-SCT host immune-microenvironment and changes of B cell homeostasis could influence GVH- and Graft-versus-Tumor reactions. The paradoxical increase of EM Treg in PB of patients with GVHD could be explained by their compartmentalization outside lymphoid tissues, which are of critical relevance for regulation of GVH reactions.

Effects of storage time on the motility, mortality and calcium levels of Atlantic salmon Salmo salar spermatozoa

This study estimates spermatozoa mortality, morphology, motility and intracellular calcium levels in Atlantic salmon Salmo salar milt after prolonged storage. Milt samples were preserved at 4° C for 25 days and then evaluated for mortality. Motility remained high for the first 3 days and the mortality was low during the first 5 days of storage. A decrease of >50% in calcium content was observed after 5 days of storage. When spermatozoa were activated, calcium levels increased >200% in relative fluorescence units (RFU); this rate of increase was lost when the samples were stored for extended periods of time and was only partially manifested in a zero calcium solution. The results suggest that in vitro storage of S. salar spermatozoa at 4° C for a period of 3 days preserves motility and limits mortality to levels similar to those of fresh spermatozoa. This method also maintains intracellular calcium storage critical for spermatozoa performance.

Quantifying in vivo murine antigen-specific T cell responses without requirement for prior knowledge of antigen identity

Extracorporeal Photochemotherapy (ECP) is a widely applied anti-cancer immunotherapy for patients with cutaneous T cell lymphoma (CTCL). By using apoptotic malignant cells as a source of patient-specific tumor antigen, it enables clinically relevant and curative anti-CTCL immunity, with potential efficacy in other tumors. Currentmethods to track patient-specific responses are tedious, and new methods are needed to assess putative global immunity. We developed a clinically practical method to assess antigen-specific T cell activation that does not rely on knowledge of the particular antigen, thereby eliminating the requirement for patient-specific reagents. In the OT-I transgenic murine system, we quantified calcium flux to reveal early T cell engagement by antigen presenting cells constitutively displaying a model antigenic peptide, ovalbumin (OVA)-derived SIINFEKL. We detected calcium flux in OVA-specific T cells, triggered by specific T cell receptor engagement by SIINFEKL peptide-loaded DC. This approach led to sensitive detection of antigen-specific calcium flux (ACF) down to a peptide-loading concentration of ∼10^-3uM and at a frequency of ∼0.1% OT-I cells among wild-type (WT), non-responding cells. Antigen-specific T cells were detected in spleen, lymph nodes, and peripheral blood after adoptive transfer into control recipient mice. Methods like this for assessing therapeutic response are lacking in patients currently on immune-based therapies, such as ECP, where assessment of clinical response is made by delayed measurement of the size of the malignant clone. These findings suggest an early, practical way to measure therapeutically-induced anti-tumor responses in ECP-treated patients that have been immunized against their malignant cells.

Myeloid dendritic cells exhibit defects in activation and function in patients with multiple sclerosis

BACKGROUND

Regulatory T cells (Tregs) are functionally defective in patients with multiple sclerosis (MS) and this dysfunction is related to an imbalanced composition of naïve and memory Treg subtypes. Several lines of evidence indicate that these abnormalities might result from a premature decline in thymic-dependent Treg neogenesis. Myeloid dendritic cells (mDCs) critically determine Treg differentiation in the thymus, and thymic stromal lymphopoietin receptor (TSLPR) expressed on mDCs is a key component of the signaling pathways involved in this process. TSLPR-expression on mDCs was previously shown to be decreased in MS. We hypothesized that functional alterations in mDCs contribute to aberrant Treg neogenesis and, in turn, to altered Treg homeostasis and function in MS.

METHODS

We recruited blood samples from 20 MS patients and 20 healthy controls to assess TSLPR expression on mDCs ex vivo by flow cytometry and by activating mDCs induced by recombinant TSLP (rhTSLP) in vitro. As previous studies documented normalization of both function and homeostasis of Tregs under immunomodulatory (IM) therapy with interferon-beta (IFN-beta) and glatiramer acetate (GA), we also tested phenotypes and function of mDCs obtained from IM-treated patients (IFN-beta: n=20, GA: n=20).

RESULTS

We found that TSLP-induced mDC activation and effector function in vitro was reduced in MS and correlated with TSLPR-expression levels on mDCs. IM treatment prompted upregulation of TSLPR on mDCs and an increase in TSLP-induced activation of mDCs together with a normalization of Treg homeostasis.

CONCLUSION

The decreased TSLP-induced activation of MS-derived mDCs in vitro, together with the reduced density of TSLPR on the cell surface of mDCs corroborates the hypothesis of mDCs being critically involved in impairing Treg development in MS.

Advances in the immunopathogenesis of multiple sclerosis

PURPOSE OF REVIEW

Recent studies indicate a role for immune dysregulation in the pathogenesis of multiple sclerosis, an inflammatory demyelinating and degenerative disease of the central nervous system. This review addresses the current mechanisms of immune dysregulation in the development of multiple sclerosis, including the impact of environmental risk factors on immunity in both multiple sclerosis and its animal models.

RECENT FINDINGS

CD4 T-helper (Th) cells have long been implicated as the main drivers of pathogenesis of multiple sclerosis. However, current studies indicate that multiple sclerosis is largely a heterogeneous disease process, which involves both innate and adaptive immune-mediated inflammatory mechanisms that ultimately contribute to demyelination and neurodegeneration. Therefore, B cells, CD8 T cells, and microglia/macrophages can also play an important role in the immunopathogenesis of multiple sclerosis apart from proinflammatory CD4 Th1/Th17 cell subsets. Furthermore, increasing evidence indicates that environmental risk factors, such as Vitamin D deficiency, Epstein-Barr virus, smoking, Western diet, and the commensal microbiota, influence the development of multiple sclerosis through interactions with genetic variants of multiple sclerosis, thus leading to the dysregulation of immune responses.

SUMMARY

A better understanding of immune-mediated mechanisms in the pathogenesis of multiple sclerosis and the contribution of environmental risk factors toward the development of multiple sclerosis will help further improve therapeutic approaches to prevent disease progression.

Functional and homeostatic defects of regulatory T cells in patients with coronary artery disease

OBJECTIVE

Regulatory T cells (Tregs) are considered atheroprotective, and low levels have been associated with the acute coronary syndrome (ACS), particularly non-ST elevation (NSTE)-ACS. However, the functional properties as well as homeostasis of Tregs are mainly unknown in coronary artery disease (CAD). Here, we investigated the composition and functional properties of naïve (n) and memory (m)Tregs in patients with NSTE-ACS and in patients 6-12 months post-ACS.

METHODS

Based on the expression of CD25, FOXP3, CD127, CD45RA, CD39 and CTLA-4, Treg subsets were defined by flow cytometry in whole blood or isolated CD4(+) T cells. The functional properties of nTregs and mTregs were examined in terms of proliferative capacity and modulation of cytokine secretion. To understand the potential consequences of Treg defects, we also investigated correlations with lipopolysaccharide (LPS)-induced cytokine secretion and ultrasound-defined carotid atherosclerosis.

RESULTS

Both NSTE-ACS and post-ACS patients exhibited reduced levels of nTregs (P < 0.001) compared with healthy control subjects, but without compensatory increases in mTregs. Both nTregs and mTregs from patients showed significantly lower replicative rates and impaired capacity to modulate T-cell proliferation and secretion of interferon-gamma and IL-10. The Treg defect was also associated with LPS-induced cytokine secretion and increased burden of carotid atherosclerosis.

CONCLUSION

Our results demonstrate a functional and homeostatic Treg defect in patients with NSTE-ACS and also in stabilized patients 6-12 months after ACS. Moreover, this defect was associated with a subclinical proinflammatory and atherogenic state. We believe that the failure to preserve Treg function and homeostasis reflects a need for immune-restoring strategies in CAD.

Human regulatory T cells control TCR signaling and susceptibility to suppression in CD4+ T cells

Human CD4(+)CD25(hi)FOXP3(+) regulatory T cells maintain immunologic tolerance and prevent autoimmune and inflammatory immune responses. Regulatory T cells undergo a similar activation cycle as conventional CD4(+) T cells upon antigen stimulation. Here, we demonstrate that T cell receptors and costimulation are required to activate the regulatory T cell suppressive function. Regulatory T cells suppressed the T cell receptor signaling in effector T cells in a time-dependent manner that corresponded with inhibition of cytokine production and proliferation. Modulation of the activation level and thereby the suppressive capacity of regulatory T cells imposed distinct T cell receptor signaling signatures and hyporesponsiveness in suppressed and proliferating effector T cells and established a threshold for effector T cell proliferation. The immune suppression of effector T cells was completely reversible upon removal of regulatory T cells. However, the strength of prior immune suppression by regulatory T cells and corresponding T cell receptor signaling in effector T cells determined the susceptibility to suppression upon later reexposure to regulatory T cells. These findings demonstrate how the strength of the regulatory T cell suppressive function determines intracellular signaling, immune responsiveness, and the later susceptibility of effector T cells to immune suppression and contribute to unveiling the complex interactions between regulatory T cells and effector T cells.

Dimethyl fumarate treatment alters circulating T helper cell subsets in multiple sclerosis

Objective:

To evaluate the effect of dimethyl fumarate (DMF; Tecfidera, Biogen, Weston, MA) on CD4⁺ and CD8⁺ T cell subsets in patients with multiple sclerosis (MS).

Methods:

Peripheral lymphocyte subsets, including CD4⁺ and CD8⁺ memory cells and T helper (T_H) cells T_H1, T_H2, T_H17, and peripheral regulatory T cell (pT_reg) subpopulations were analyzed before and 6 months after onset of DMF treatment.

Results:

CD4⁺ and CD8⁺ memory T cells were preferentially decreased compared to naive CD4⁺ and CD8⁺ T cell populations. Within the CD4⁺ memory T cell population, frequencies of T_H1 cells were decreased, whereas those of T_H2 cells were increased and those of T_H17 cells remained unaltered. Accordingly, we observed decreased production of interferon γ, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor α, and interleukin (IL)-22 by CD4⁺ T cells under DMF treatment, whereas the frequency of IL-4- and IL-17A-producing CD4⁺ T cells remained unchanged. With regard to regulatory T cells, proportions of pT_reg increased following DMF treatment.

Conclusion:

Our data demonstrate that DMF treatment of patients with MS affects predominantly memory T cells accompanied by a shift in T_H cell populations, resulting in a shift toward anti-inflammatory responses. These findings indicate that monitoring of memory subsets might enhance vigilance of impaired antiviral immunity and that patients with T_H1-driven disease might preferentially benefit from DMF treatment.

Classification of Evidence:

This study provides Class IV evidence that DMF might preferentially reduce CD4⁺ and CD8⁺ memory T cells in MS.

The T cell-selective IL-2 mutant AIC284 mediates protection in a rat model of Multiple Sclerosis

Targeting regulatory T cells (Treg cells) with interleukin-2 (IL-2) constitutes a novel therapeutic approach for autoimmunity. As anti-cancer therapy with IL-2 has revealed substantial toxicities a mutated human IL-2 molecule, termed AIC284 (formerly BAY 50-4798), has been developed to reduce these side effects. To assess whether AIC284 is efficacious in autoimmunity, we studied its therapeutic potential in an animal model for Multiple Sclerosis. Treatment of Lewis rats with AIC284 increased Treg cell numbers and protected the rats from Experimental Autoimmune Encephalomyelitis (EAE). AIC284 might, thus, also efficiently prevent progression of autoimmune diseases in humans.

Comprehensive phenotyping of regulatory T cells after liver transplantation

Regulatory T cells (Tregs) play an important role in controlling alloreactivity after solid organ transplantation, but they may also impair antiviral immunity. We hypothesized that the Treg frequency and the Treg phenotype are altered in hepatitis C virus (HCV)-infected recipients of liver transplantation (LT) with possible prognostic implications. Tregs from 141 individuals, including healthy individuals, LT recipients with or without persistent HCV infections, and nontransplant patients with chronic HCV, were studied. A comprehensive phenotypic analysis was performed with multicolor flow cytometry, which included standard Treg markers [CD4(+), CD25(hi), CD127(-), and FoxP3(+) in addition to HLA DR, CCR7, CD45RA, CD62L, CD49d, CD39, ICOS and LAP-TGFβ stainings. Healthy individuals and LT patients displayed similar Treg frequencies and largely comparable Treg phenotypes, which were stable over time after transplantation. In contrast, Tregs with a CD45RA(-) CCR7(-) effector phenotype were enriched in LT recipients with chronic HCV versus HCV-negative transplant patients. HCV infection, rather than LT, altered the expression of functional markers on Tregs. A principal component analysis revealed distinct Treg phenotypes in HCV-infected LT recipients with rejection and patients with recurrent graft HCV. In conclusion, Treg phenotypes are altered in HCV-infected LT patients. An investigation of Tregs may possibly help to distinguish recurrent HCV from graft rejection. Further functional studies are needed to define the role of Tregs in determining the balance between antiviral and allogenic immunity.

Fingolimod does not impair T-cell release from the thymus and beneficially affects Treg function in patients with multiple sclerosis

Background:

In multiple sclerosis (MS), disturbed T-cell homeostasis affects both conventional CD4+ T cells (Tcon) and regulatory T cells (Treg). Functionally, this is linked to a loss of Treg-suppressive properties. Concerns exist as to whether fingolimod might further aggravate Treg dysfunction by inhibiting thymic egress and, thus, promoting premature immunosenescence.

Objective:

The objective of this paper is to investigate whether fingolimod, by sequestration of developing cells in the thymus, might deteriorate numeric and/or functional disequilibrium of T-cell subtypes.

Methods:

We assessed numbers and phenotypes of blood Tcon and Treg in 74 MS patients treated with fingolimod and in 37 healthy donors. Treg and Tcon were also analyzed for immunoreactivity, suppressive function, sphingosine-1-phosphate-triggered (S1P) trafficking, and S1P-receptor expression. This was complemented by assessing surrogate markers of thymic T-cell development, including frequencies of cells expressing T-cell receptors (TCR) of dual specificity, and TCR diversity in Treg.

Results:

Fingolimod did not negatively affect naive T-cell phenotypes or markers of thymic T-cell development. By reducing CCR7-expressing Tcon, fingolimod increased relative proportions of Treg. As a result of this shift, fewer proliferative CCR7− Tcon became enriched and Treg-dysfunction was indirectly reversed.

Conclusion:

These observations argue against harmful interference of fingolimod with thymic T-cell output that, particularly in pediatric MS, might possibly counteract its beneficial effects.

Regulatory T cells in autoimmune neuroinflammation

Regulatory T cells are the central element for the maintenance of peripheral tolerance. Several subtypes of regulatory T (Treg) cells have been described, and most of them belong to the CD4(+) T-helper (Th) cell lineage. These specific subtypes can be discriminated according to phenotype and function. Forkhead box protein 3 (FoxP3)-expressing natural Treg cells (Tregs) and IL-10-producing, T-regulatory type 1 cells (Tr1) are the best-studied types of CD4(+) regulatory T cells in humans and experimental animal models. It was shown that they play a crucial role during autoimmune neuroinflammation. Both cells types seem to be particularly important for multiple sclerosis (MS). Here, we discuss the role of CD4(+) regulatory T cells in autoimmune neuroinflammation with an emphasis on Tregs and Tr1 cells in MS.

Dysfunction of neuronal calcium signalling in neuroinflammation and neurodegeneration

Neurodegeneration has been increasingly recognised as the leading structural correlate of disability progression in autoimmune diseases such as multiple sclerosis. Since calcium signalling is known to regulate the development of degenerative processes in many cell types, it is believed to play significant roles in mediating neurodegeneration. Because of its function as a major juncture linking various insults and injuries associated with inflammatory attack on neuronal cell bodies and axons, it provides potential for the development of neuroprotective strategies. This is of great significance because of the lack of neuroprotective agents presently available to supplement the current array of immunomodulatory treatments. In this review, we summarise the role that various calcium channels and pumps have been shown to play in the development of neurodegeneration under inflammatory autoimmune conditions. The identification of suitable targets might also provide insights into applications in non-inflammatory neurodegenerative diseases.

GM-CSF induces neuroprotective and anti-inflammatory responses in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxicated mice

Innate and adaptive immune responses can speed nigrostriatal neurodegeneration in Parkinson's disease (PD). We posit that GM-CSF can attenuate such responses. In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mice, GM-CSF given prior to MPTP protected nigral dopaminergic neurons coincident with altered microglial morphologies and regulatory T cell (Treg) induction. Adoptive transfer of GM-CSF-induced Treg to MPTP mice protected nigral neurons. Gene expression analyses revealed novel immune-based neuronal protection pathways linked to the upregulation of IL-27. The results provide evidence that GM-CSF modulation of immunity could be of clinical benefit for PD.

The Involvement of Calpain in CD4+ T Helper Cell Bias in Multple Sclerosis

The pathogenesis of multiple sclerosis (MS) is mediated by massive infiltration of myelin-specific T cells into the central nervous system (CNS). Self-reactive CD4⁺ T helper (Th) cells, specifically Th1 and Th17 cells, are hallmarks of active disease in progression, whereas Th2 cells are predominately in remission stages. Calpain has been shown to be upregulated in the CNS of MS patients and inhibition of calpain has been shown previously to decrease disease in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We investigated calpain involvement in Thcell bias. Here, we show that calpain inhibition in primary myelin basic protein (MBP) Ac1-11-specific T cells and MBP-specific T cell line cultures increase Th2 proliferation, cytokine profile, and transcription and signaling molecules. We also show a relative decrease in Th1 inflammatory factors in these same categories and a relative decrease in Th17 proliferation. These studies provide insight into the various roles that calpain plays in Th cell bias and proliferation and increases our understanding of the role that T cells play in the pathophysiology of EAE and MS. Results also indicate the mechanisms involved by which calpain inhibitor decreases the disease signs of EAE, suggesting that calpain inhibitor can be a possible therapeutic agent for the treatment of EAE and MS.