Eomesodermin-expressing T-helper cells are essential for chronic neuroinflammation

Tyzzerella nexilis strains enriched in mobile genetic elements are involved in progressive multiple sclerosis

Multiple sclerosis (MS) is an autoimmune-demyelinating disease with an inflammatory pathology formed by self-reactive lymphocytes with activated glial cells. Progressive MS, characterized by resistance to medications, significantly differs from the non-progressive form in gut microbiome profiles. After confirming an increased abundance of "Tyzzerella nexilis" in various cohorts of progressive MS, we identified a distinct cluster of T. nexilis strains enriched in progressive MS based on long-read metagenomics. The distinct T. nexilis cluster is characterized by a large number of mobile genetic elements (MGEs) and a lack of defense systems against MGEs. Microbial genes for sulfate reduction and flagella formation with pathogenic implications are specific to this cluster. Moreover, these flagellar genes are encoded on MGEs. Mono-colonization with MGE-enriched T. nexilis made germ-free mice more susceptible to experimental autoimmune encephalomyelitis. These results indicate that the progression of MS may be promoted by MGE-enriched T. nexilis with potentially pathogenic properties.

Characterization of a novel functional porcine CD3+CD4lowCD8α+CD8β+ T-helper/memory lymphocyte subset in the respiratory tract lymphoid tissues of swine influenza A virus vaccinated pigs

The pig is emerging as a physiologically relevant biomedical large animal model. Delineating the functional roles of porcine adaptive T-lymphocyte subsets in health and disease is of critical significance, which facilitates mechanistic understanding of antigen-specific immune memory responses. We identified a novel T-helper/memory lymphocyte subset in pigs and performed phenotypic and functional characterization of these cells under steady state and following vaccination and infection with swine influenza A virus (SwIAV). A novel subset of CD3+CD4lowCD8α+CD8β+ memory T-helper cells was identified in the blood of healthy adult pigs under homeostatic conditions. To understand the possible functional role/s of these cells, we characterized the antigen-specific T cell memory responses by multi-color flow cytometry in pigs vaccinated with a whole inactivated SwIAV vaccine, formulated with a phytoglycogen nanoparticle/STING agonist (ADU-S100) adjuvant (NanoS100-SwIAV). As a control, a commercial SwIAV vaccine was included in a heterologous challenge infection trial. The frequencies of antigen-specific IL-17A and IFNγ secreting CD3+CD4lowCD8α+CD8β+ memory T-helper cells were significantly increased in the lung draining tracheobronchial lymph nodes (TBLN) of intradermal, intramuscular and intranasal inoculated NanoS100-SwIAV vaccine and commercial vaccine administered animals. While the frequencies of antigen-specific, IFNγ secreting CD3+CD4lowCD8α+CD8β+ memory T-helper cells were significantly enhanced in the blood of intranasal and intramuscular vaccinates. These observations suggest that the CD3+CD4lowCD8α+CD8β+ T-helper/memory cells in pigs may have a protective and/or regulatory role/s in immune responses against SwIAV infection. These observations highlight the heterogeneity and plasticity of porcine CD4+ T-helper/memory cells in response to respiratory viral infection in pigs. Comprehensive systems immunology studies are needed to further decipher the cellular lineages and functional role/s of this porcine T helper/memory cell subset.

The Current Landscape of Hypotheses Describing the Contribution of CD4+ Heterogeneous Populations to ALS

Amyotrophic Lateral Sclerosis (ALS) is a poorly understood and fatal disease. It has a low prevalence and a 2-4 year survival period. Various theories and hypotheses relating to its development process have been proposed, albeit with no breakthrough in its treatment. Recently, the role of the adaptive immune system in ALS, particularly CD4+ T cells, has begun to be investigated. CD4+ T cells are a heterogeneous group of immune cells. They include highly pro-inflammatory types such as Th1 and Th17, as well as highly anti-inflammatory cells such as Tregs. However, the landscape of the role of CD4+ T cells in ALS is still not clearly understood. This review covers current hypotheses that elucidate how various CD4+ T cells can contribute to ALS development. These hypotheses include the SWITCH model, which suggests that, in the early stages of the disease, Tregs are highly capable of regulating the immune response. However, in the later stages of the disease, it seems that pro-inflammatory cells such as Th1 and Th17 are capable of overwhelming Treg function. The reason why this occurs is not known. Several research groups have proposed that CD4+ T cells as a whole might experience aging. Others have proposed that gamma delta T cells might directly target Tregs. Additionally, other research groups have argued that less well-known CD4+ T cells, such as Emoes+ CD4+ T cells, may be directly responsible for neuron death by producing granzyme B. We propose that the ALS landscape is highly complicated and that there is more than one feasible hypothesis. However, it is critical to take into consideration the differences in the ability of different populations of CD4+ T cells to infiltrate the blood-brain barrier, taking into account the brain region and the time of infiltration. Shedding more light on these still obscure factors can help to create a personalized therapy capable of regaining the balance of power in the battle between the anti-inflammatory and pro-inflammatory cells in the central nervous system of ALS patients.

Characterisation of choroid plexus-infiltrating T cells reveals novel therapeutic targets in murine neuropsychiatric lupus

OBJECTIVE

Diffuse central nervous system manifestations, referred to as neuropsychiatric lupus (NPSLE), are observed in 20-40% of lupus patients and involve complex mechanisms that have not yet been adequately elucidated. In murine NPSLE models, choroid plexus (ChP)-infiltrating T cells have not been fully evaluated as drivers of neuropsychiatric disease.

METHOD

Droplet-based single-cell transcriptomic analysis (single-cell RNA sequencing) and immune T-cell receptor profiling were performed on ChP tissue from MRL/lpr mice, an NPSLE mouse model, at an 'early' and 'late' disease state, to investigate the infiltrating immune cells that accumulate with NPSLE disease progression.

RESULTS

We found 19 unique clusters of stromal and infiltrating cells present in the ChP of NPSLE mice. Higher resolution of the T-cell clusters uncovered multiple T-cell subsets, with increased exhaustion and hypoxia expression profiles. Clonal analysis revealed that the clonal CD8+T cell CDR3 sequence, ASGDALGGYEQY, matched that of a published T-cell receptor sequence with specificity for myelin basic protein. Stromal fibroblasts are likely drivers of T-cell recruitment by upregulating the VCAM signalling pathway. Systemic blockade of VLA-4, the cognate ligand of VCAM, resulted in significant resolution of the ChP immune cell infiltration and attenuation of the depressive phenotype.

CONCLUSION

Our analysis details the dynamic transcriptomic changes associated with murine NPSLE disease progression, and highlights its potential use in identifying prospective lupus brain therapeutic targets.

Exploring the immune characteristions of CRKP pneumonia at single-cell level

The immune dysregulation associated with carbapenem-resistant Klebsiella pneumoniae (CRKP) severity was investigated through single-cell RNA sequencing (scRNA-seq) of 5 peripheral blood samples from 3 patients with moderate and severe CRKP pneumonia. Additionally, scRNA-seq datasets from two individuals with COVID-19 were included for comparative analysis. The dynamic characterization and functional properties of each immune cell type were examined by delineating the transcriptional profiles of immune cells throughout the transition from moderate to severe conditions. Overall, most immune cells in CRKP patients exhibited a robust interferon-α response and inflammatory reaction compared to healthy controls, mirroring observations in COVID-19 patients. Furthermore, cell signatures associated with NK cells, macrophages, and monocytes were identified in CRKP progression including PTPRCAP for NK cells, C1QB for macrophages, and S100A12 for both macrophages and monocytes. In summary, this study offers a comprehensive scRNA-seq resource for illustrating the dynamic immune response patterns during CRKP progression, thereby shedding light on the associations between CRKP and COVID-19.

NF-κB subunits RelA and c-Rel selectively control CD4+ T cell function in multiple sclerosis and cancer

The outcome of cancer and autoimmunity is often dictated by the effector functions of CD4+ conventional T cells (Tconv). Although activation of the NF-κB signaling pathway has long been implicated in Tconv biology, the cell-autonomous roles of the separate NF-κB transcription-factor subunits are unknown. Here, we dissected the contributions of the canonical NF-κB subunits RelA and c-Rel to Tconv function. RelA, rather than c-Rel, regulated Tconv activation and cytokine production at steady-state and was required for polarization toward the TH17 lineage in vitro. Accordingly, RelA-deficient mice were fully protected against neuroinflammation in a model of multiple sclerosis due to defective transition to a pathogenic TH17 gene-expression program. Conversely, Tconv-restricted ablation of c-Rel impaired their function in the microenvironment of transplanted tumors, resulting in enhanced cancer burden. Moreover, Tconv required c-Rel for the response to PD-1-blockade therapy. Our data reveal distinct roles for canonical NF-κB subunits in different disease contexts, paving the way for subunit-targeted immunotherapies.

Granzyme serine proteases in inflammation and rheumatic diseases

Granzymes (granule-secreted enzymes) are a family of serine proteases that have been viewed as redundant cytotoxic enzymes since their discovery more than 30 years ago. Predominantly produced by cytotoxic lymphocytes and natural killer cells, granzymes are delivered into the cytoplasm of target cells through immunological synapses in cooperation with the pore-forming protein perforin. After internalization, granzymes can initiate cell death through the cleavage of intracellular substrates. However, evidence now also demonstrates the existence of non-cytotoxic, pro-inflammatory, intracellular and extracellular functions that are granzyme specific. Under pathological conditions, granzymes can be produced and secreted extracellularly by immune cells as well as by non-immune cells. Depending on the granzyme, accumulation in the extracellular milieu might contribute to inflammation, tissue injury, impaired wound healing, barrier dysfunction, osteoclastogenesis and/or autoantigen generation.

Pathogenic Potential of Eomesodermin-Expressing T-Helper Cells in Neurodegenerative Diseases

Eomesodermin-expressing (Eomes+) T-helper (Th) cells show cytotoxic characteristics in secondary progressive multiple sclerosis. We found that Eomes+ Th cell frequency was increased in the peripheral blood of amyotrophic lateral sclerosis and Alzheimer's disease patients. Furthermore, granzyme B production by Th cells from such patients was high compared with controls. A high frequency of Eomes+ Th cells was observed in the initial (acutely progressive) stage of amyotrophic lateral sclerosis, and a positive correlation between Eomes+ Th cell frequency and cognitive decline was observed in Alzheimer's disease patients. Therefore, Eomes+ Th cells may be involved in the pathology of amyotrophic lateral sclerosis and Alzheimer's disease. ANN NEUROL 2024;95:1093-1098.

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

Eomesodermin expression in CD4+T-cells associated with disease progression in amyotrophic lateral sclerosis

AIM

To clarify the role of Eomesodermin (EOMES) to serve as a disease-relevant biomarker and the intracellular molecules underlying the immunophenotype shifting of CD4+T subsets in amyotrophic lateral sclerosis (ALS).

METHODS

The derivation and validation cohorts included a total of 148 ALS patients and 101 healthy controls (HCs). Clinical data and peripheral blood were collected. T-cell subsets and the EOMES expression were quantified using multicolor flow cytometry. Serum neurofilament light chain (NFL) was measured. In 1-year longitudinal follow-ups, the ALSFRS-R scores and primary endpoint events were further recorded in the ALS patients of the validation cohort.

RESULTS

In the derivation cohort, the CD4+EOMES+T-cell subsets were significantly increased (p < 0.001). EOMES+ subset was positively correlated with increased serum NFL levels in patients with onset longer than 12 months. In the validation cohort, the elevated CD4+EOMES+T-cell proportions and their association with NFL levels were also identified. The longitudinal study revealed that ALS patients with higher EOMES expression were associated with higher progression rates (p = .010) and worse prognosis (p = .003).

CONCLUSIONS

We demonstrated that increased CD4+EOMES+T-cell subsets in ALS were associated with disease progression and poor prognosis. Identifying these associations may contribute to a better understanding of the immunopathological mechanism of ALS.

Terminally differentiated cytotoxic CD4+ T cells were clonally expanded in the brain lesion of radiation-induced brain injury

BACKGROUND

Accumulating evidence supports the involvement of adaptive immunity in the development of radiation-induced brain injury (RIBI). Our previous work has emphasized the cytotoxic function of CD8+ T cells in RIBI. In this study, we aimed to investigate the presence and potential roles of cytotoxic CD4+ T cells (CD4+ CTLs) in RIBI to gain a more comprehensive understanding of adaptive immunity in this context.

MAIN TEXT

Utilizing single-cell RNA sequencing (scRNA-seq), we analyzed 3934 CD4+ T cells from the brain lesions of four RIBI patients and identified six subclusters within this population. A notable subset, the cytotoxic CD4+ T cells (CD4+ CTLs), was marked with high expression of cytotoxicity-related genes (NKG7, GZMH, GNLY, FGFBP2, and GZMB) and several chemokine and chemokine receptors (CCL5, CX3CR1, and CCL4L2). Through in-depth pseudotime analysis, which simulates the development of CD4+ T cells, we observed that the CD4+ CTLs exhibited signatures of terminal differentiation. Their functions were enriched in protein serine/threonine kinase activity, GTPase regulator activity, phosphoprotein phosphatase activity, and cysteine-type endopeptidase activity involved in the apoptotic signaling pathway. Correspondingly, mice subjected to gamma knife irradiation on the brain showed a time-dependent infiltration of CD4+ T cells, an increase of MHCII+ cells, and the existence of CD4+ CTLs in lesions, along with an elevation of apoptotic-related proteins. Finally, and most crucially, single-cell T-cell receptor sequencing (scTCR-seq) analysis at the patient level determined a large clonal expansion of CD4+ CTLs in lesion tissues of RIBI. Transcriptional factor-encoding genes TBX21, RORB, and EOMES showed positive correlations with the cytotoxic functions of CD4+ T cells, suggesting their potential to distinguish RIBI-related CD4+ CTLs from other subsets.

CONCLUSION

The present study enriches the understanding of the transcriptional landscape of adaptive immune cells in RIBI patients. It provides the first description of a clonally expanded CD4+ CTL subset in RIBI lesions, which may illuminate new mechanisms in the development of RIBI and offer potential biomarkers or therapeutic targets for the disease.

Eomes-dependent mitochondrial regulation promotes survival of pathogenic CD4+ T cells during inflammation

The mechanisms whereby Eomes controls tissue accumulation of T cells and strengthens inflammation remain ill-defined. Here, we show that Eomes deletion in antigen-specific CD4+ T cells is sufficient to protect against central nervous system (CNS) inflammation. While Eomes is dispensable for the initial priming of CD4+ T cells, it is required for long-term maintenance of CNS-infiltrating CD4+ T cells. We reveal that the impact of Eomes on effector CD4+ T cell longevity is associated with sustained expression of multiple genes involved in mitochondrial organization and functions. Accordingly, epigenetic studies demonstrate that Eomes supports mitochondrial function by direct binding to either metabolism-associated genes or mitochondrial transcriptional modulators. Besides, the significance of these findings was confirmed in CD4+ T cells from healthy donors and multiple sclerosis patients. Together, our data reveal a new mechanism by which Eomes promotes severity and chronicity of inflammation via the enhancement of CD4+ T cell mitochondrial functions and resistance to stress-induced cell death.

A role of NR4A2 in Graves' disease: regulation of Th17/Treg

PURPOSE

This study aimed to explore the molecular pathogenesis of Graves' disease (GD).

METHODS

The gene expression profile in CD4+ T cells from GD patients and healthy controls were analyzed through mRNA-sequencing. The expression of NR4A2 was determined by quantitative real-time PCR and western blot. The levels of Th17 and Treg were determined by flow cytometry. ELISA was employed to detect the levels of IL-10, IL-17A, IL-17F and IL-22.

RESULTS

In the CD4+ T cells from GD patients, there were 128 up-regulated and 510 down-regulated genes. Subsequently, we focused on the role of nuclear receptor 4 group A member 2 (NR4A2) in GD. NR4A2 was lowly expressed in the CD4+ T cells from GD patients. Its expression was negatively correlated with free triiodothyronine and tetraiodothyronine, but positively correlated with thyroid stimulating hormone. NR4A2 knockdown decreased the percentage of Treg cells, with a decreased IL-10 level. While its over-expression augmented the Treg differentiation, with an elevated IL-10 level. In addition, knockdown or over-expression of NR4A2 showed no significant influence on Th17 differentiation.

CONCLUSION

These results indicate that the low level of NR4A2 in GD patients may suppress Treg differentiation, but have no influence on Th17 differentiation, leading to the imbalance of Th17/Treg and contributing to the development of GD. Revealing the role of NR4A2 in GD provides a novel insight for the treatment of GD.

Differential Runx3, Eomes, and T-bet expression subdivides MS-associated CD4+ T cells with brain-homing capacity

Multiple sclerosis (MS) is a common and devastating chronic inflammatory disease of the CNS. CD4+ T cells are assumed to be the first to cross the blood-central nervous system (CNS) barrier and trigger local inflammation. Here, we explored how pathogenicity-associated effector programs define CD4+ T cell subsets with brain-homing ability in MS. Runx3- and Eomes-, but not T-bet-expressing CD4+ memory cells were diminished in the blood of MS patients. This decline reversed following natalizumab treatment and was supported by a Runx3+ Eomes+ T-bet- enrichment in cerebrospinal fluid samples of treatment-naïve MS patients. This transcription factor profile was associated with high granzyme K (GZMK) and CCR5 levels and was most prominent in Th17.1 cells (CCR6+ CXCR3+ CCR4-/dim ). Previously published CD28- CD4 T cells were characterized by a Runx3+ Eomes- T-bet+ phenotype that coincided with intermediate CCR5 and a higher granzyme B (GZMB) and perforin expression, indicating the presence of two separate subsets. Under steady-state conditions, granzyme Khigh Th17.1 cells spontaneously passed the blood-brain barrier in vitro. This was only found for other subsets including CD28- cells when using inflamed barriers. Altogether, CD4+ T cells contain small fractions with separate pathogenic features, of which Th17.1 seems to breach the blood-brain barrier as a possible early event in MS.

Natalizumab Treatment of Relapsing Remitting Multiple Sclerosis Has No Long-Term Effects on the Proportion of Circulating Regulatory T Cells

INTRODUCTION

Natalizumab (NTZ), a monoclonal antibody against the integrin α4β1 (VLA-4) found on activated T cells and B cells, blocks the interaction of this integrin with adhesion molecules of central nervous system (CNS) endothelial cells and lymphocyte migration through the blood-brain barrier, effectively preventing new lesion formation and relapses in multiple sclerosis (MS). Whether NTZ treatment has additional effects on the peripheral immune system cells, and how its actions compare with other MS disease-modifying treatments, have not been extensively investigated. In particular, its effect on the proportions of circulating regulatory T cells (Treg) is unclear.

METHODS

In this study, we investigated the effect of NTZ treatment in 12 patients with relapsing MS, at 6 and 12 months after the start of treatment. We evaluated the proportions of regulatory T cells (Treg), defined by flow cytometry as CD4+ CD25++ FoxP3+ cells and CD4+ CD25++ CD127- cells at these intervals. As an exploratory study, we also investigated the NTZ effects on the proportions of bulk T and B lymphocyte populations, and of those expressing novel the markers CD195 (CCR5), CD196 (CCR6), or CD161 (KLRB1), which are involved in MS pathogenesis but have been studied less in the context of MS treatment. The effects of NTZ were compared to those obtained with 11 patients under interferon-beta-1a (IFN-β1a) treatment, and against 9 healthy volunteers.

RESULTS

We observed a transient increment in the proportion of Treg cells at 6 months, which was not sustained at 12 months. We observed a reduction in the proportion of T cells expressing CD195 (CCR5) and CD161 (KLRB1) subsets of T cells.

CONCLUSION

We conclude that NTZ does not have an effect on the proportion of Treg cells over 1 year, but it may affect the expression of molecules important for some aspects MS pathogenesis, in a manner that is not shared with IFN-β1a.

Evaluation of Long Non-coding RNA Expression Profiles in Peripheral Blood Mononuclear Cells of Patients with Parkinson's Disease

As in many biological processes, the long non-coding RNAs (lncRNA) are currently known to have important roles in Parkinson's disease (PD). The aim of the study is to evaluate differentiated expressions of lncRNAs and their target mRNAs in the peripheral blood cells of individuals with Parkinson's disease. The peripheral blood samples were taken from 10 Parkinson's diagnosed people aging 50 years and more and from 10 healthy people as for the control group. Total RNA was isolated from peripheral blood mononuclear cells (PBMC), and a total of 5 samples were selected and evaluated by microarray analysis. lncRNAs with high fold change (fc < 1.5/fc > 1.5) were determined as a result of the analysis. Following this, the expression changes of some lncRNAs and their target mRNAs were examined by quantitative simultaneous polymerase chain reaction (qRT-PCR) in all individuals in the patient and control groups. Also, in order to determine the molecular level basic activities of lncRNAs determined by microarray analysis and which biological process and biochemical pathway they were in, Gene Ontology (GO) analysis ( http://geneontology.org/ ) database was used. Thirteen upregulated and 31 downregulated lncRNAs whose expression changes were determined by microarray analysis and confirmed by qRT-PCR method were found in Parkinson's patients. As they were evaluated by GO analysis, lncRNAs were expressed differently in patient and control groups and they are found to be related with the processes such as macromolecule metabolic processes, immune system, gene expression, cell activation, ATPase activity, DNA packaging complex, signal receptor activity, immune receptor activity, and protein binding were found to be significant.

Nuclear orphan receptors: A novel therapeutic agent in neuroinflammation

Orphan receptors constitute a historically varied subsection of a superfamily of nuclear receptors. Nuclear receptors regulate gene expression in response to ligand signals and are particularly alluring therapeutic targets for chronic illnesses. Neuroinflammation and neurodegenerative diseases have been linked to these orphan nuclear receptors. Preclinical and clinical evidence suggests that orphan receptors could serve as future targets in neuroinflammation, such as Parkinson's disease (PD), Alzheimer's Disease (AD), Huntington's Disease (HD), Multiple Sclerosis (MS), and Cerebral Ischemia. Given the therapeutic relevance of certain orphan receptors in a variety of disorders, their potential in neuroinflammation remains unproven. There is substantial evidence that ligand-activated transcription factors have great promise for preventing neurodegenerative and neurological disorders, with certain orphan nuclear receptors i.e., PPARγ, NR4As, and orphan GPCRs holding particularly high potential. Based on previous findings, we attempted to determine the contribution of PPAR, NR4As, and orphan GPCRs-regulated neuroinflammation to the pathogenesis of these disorders and their potential to become novel therapeutic targets.

The role of CD4+ T cells in tumor and chronic viral immune responses

Immunotherapies are mainly aimed to promote a CD8+ T cell response rather than a CD4+ T cell response as cytotoxic T lymphocytes (CTLs) can directly kill target cells. Recently, CD4+ T cells have received more attention due to their diverse roles in tumors and chronic viral infections. In antitumor and antichronic viral responses, CD4+ T cells relay help signals through dendritic cells to indirectly regulate CD8+ T cell response, interact with B cells or macrophages to indirectly modulate humoral immunity or macrophage polarization, and inhibit tumor blood vessel formation. Additionally, CD4+ T cells can also exhibit direct cytotoxicity toward target cells. However, regulatory T cells exhibit immunosuppression and CD4+ T cells become exhausted, which promote tumor progression and chronic viral persistence. Finally, we also outline immunotherapies based on CD4+ T cells, including adoptive cell transfer, vaccines, and immune checkpoint blockade. Overall, this review summarizes diverse roles of CD4+ T cells in the antitumor or protumor and chronic viral responses, and also highlights the immunotherapies based on CD4+ T cells, giving a better understanding of their roles in tumors and chronic viral infections.

Extremely Differentiated T Cell Subsets Contribute to Tissue Deterioration During Aging

There is a dramatic remodeling of the T cell compartment during aging. The most notorious changes are the reduction of the naive T cell pool and the accumulation of memory-like T cells. Memory-like T cells in older people acquire a phenotype of terminally differentiated cells, lose the expression of costimulatory molecules, and acquire properties of senescent cells. In this review, we focus on the different subsets of age-associated T cells that accumulate during aging. These subsets include extremely cytotoxic T cells with natural killer properties, exhausted T cells with altered cytokine production, and regulatory T cells that gain proinflammatory features. Importantly, all of these subsets lose their lymph node homing capacity and migrate preferentially to nonlymphoid tissues, where they contribute to tissue deterioration and inflammaging.

Biomarkers in autoimmune diseases of the central nervous system

The autoimmune diseases of the central nervous system (CNS) represent individual heterogeneity with different disease entities. Although clinical and imaging features make it possible to characterize larger patient cohorts, they may not provide sufficient evidence to detect disease activity and response to disease modifying drugs. Biomarkers are becoming a powerful tool due to their objectivity and easy access. Biomarkers may indicate various aspects of biological processes in healthy and/or pathological states, or as a response to drug therapy. According to the clinical features described, biomarkers are usually classified into predictive, diagnostic, monitoring and safety biomarkers. Some nerve injury markers, humoral markers, cytokines and immune cells in serum or cerebrospinal fluid have potential roles in disease severity and prognosis in autoimmune diseases occurring in the CNS, which provides a promising approach for clinicians to early intervention and prevention of future disability. Therefore, this review mainly summarizes the potential biomarkers indicated in autoimmune disorders of the CNS.

Pathogenic Microglia Orchestrate Neurotoxic Properties of Eomes-Expressing Helper T Cells

In addition to disease-associated microglia (DAM), microglia with MHC-II and/or IFN-I signatures may form additional pathogenic subsets that are relevant to neurodegeneration. However, the significance of such MHC-II and IFN-I signatures remains elusive. We demonstrate here that these microglial subsets play intrinsic roles in orchestrating neurotoxic properties of neurotoxic Eomes+ Th cells under the neurodegeneration-associated phase of experimental autoimmune encephalomyelitis (EAE) that corresponds to progressive multiple sclerosis (MS). Microglia acquire IFN-signature after sensing ectopically expressed long interspersed nuclear element-1 (L1) gene. Furthermore, ORF1, an L1-encoded protein aberrantly expressed in the diseased central nervous system (CNS), stimulated Eomes+ Th cells after Trem2-dependent ingestion and presentation in MHC-II context by microglia. Interestingly, administration of an L1 inhibitor significantly ameliorated neurodegenerative symptoms of EAE concomitant with reduced accumulation of Eomes+ Th cells in the CNS. Collectively, our data highlight a critical contribution of new microglia subsets as a neuroinflammatory hub in immune-mediated neurodegeneration.

Identification of proteinase 3 autoreactive CD4+T cells and their T-cell receptor repertoires in antineutrophil cytoplasmic antibody-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune disease involving autoreactivity to proteinase 3 (PR3) as demonstrated by presence of ANCAs. While autoantibodies are screened for diagnosis, autoreactive T cells and their features are less well-studied. Here, we investigated PR3-specific CD4+T cell responses and features of autoreactive T cells in patients with PR3-AAV, using a cohort of 72 patients with either active or inactive disease. Autoreactive PR3-specific CD4+T cells producing interferon γ in response to protein stimulation were found to express the G-protein coupled receptor 56 (GPR56), a cell surface marker that distinguishes T cells with cytotoxic capacity. GPR56+CD4+T cells were significantly more prominent in the blood of patients with inactive as compared to active disease, suggesting that these cells were affected by immunosuppression and/or that they migrated from the circulation to sites of organ involvement. Indeed, GPR56+CD4+T cells were identified in T-cell infiltrates of affected kidneys and an association with immunosuppressive therapy was found. Moreover, distinct TCR gene segment usage and shared (public) T cell clones were found for the PR3-reactive TCRs. Shared T cell clones were found in different patients with AAV carrying the disease-associated HLA-DP allele, demonstrating convergence of the autoreactive T cell repertoire. Thus, we identified a CD4+T cell signature in blood and in affected kidneys that display PR3 autoreactivity and associates with T cell cytotoxicity. Our data provide a basis for novel rationales for both immune monitoring and future therapeutic intervention in PR3-AAV.

Chemokine positioning determines mutually exclusive roles for their receptors in extravasation of pathogenic human T cells

Pro-inflammatory T cells co-express multiple chemokine receptors, but the distinct functions of individual receptors on these cells are largely unknown. Human Th17 cells uniformly express the chemokine receptor CCR6, and we discovered that the subgroup of CD4+CCR6+ cells that co-express CCR2 possess a pathogenic Th17 signature, can produce inflammatory cytokines independent of TCR activation, and are unusually efficient at transendothelial migration (TEM). The ligand for CCR6, CCL20, was capable of binding to activated endothelial cells (ECs) and inducing firm arrest of CCR6+CCR2+ cells under conditions of flow - but CCR6 could not mediate TEM. By contrast, CCL2 and other ligands for CCR2, despite being secreted from both luminal and basal sides of ECs, failed to bind to the EC surfaces - and CCR2 could not mediate arrest. Nonetheless, CCR2 was required for TEM. To understand if CCR2's inability to mediate arrest was due solely to an absence of EC-bound ligands, we generated a CCL2-CXCL9 chimeric chemokine that could bind to the EC surface. Although display of CCL2 on the ECs did indeed lead to CCR2-mediated arrest of CCR6+CCR2+ cells, activating CCR2 with surface-bound CCL2 blocked TEM. We conclude that mediating arrest and TEM are mutually exclusive activities of chemokine receptors and/or their ligands that depend, respectively, on chemokines that bind to the EC luminal surfaces versus non-binding chemokines that form transendothelial gradients under conditions of flow. Our findings provide fundamental insights into mechanisms of lymphocyte extravasation and may lead to novel strategies to block or enhance their migration into tissue.

Eomes is sufficient to regulate IL-10 expression and cytotoxic effector molecules in murine CD4+ T cells

The T-box transcription factors T-bet and Eomesodermin regulate type 1 immune responses in innate and adaptive lymphocytes. T-bet is widely expressed in the immune system but was initially identified as the lineage-specifying transcription factor of Th1 CD4⁺ T cells, where it governs expression of the signature cytokine IFN- γ and represses alternative cell fates like Th2 and Th17. T-bet's paralog Eomes is less abundantly expressed and Eomes⁺ CD4⁺ T cells are mostly found in the context of persistent antigen exposure, like bone marrow transplantation, chronic infection or inflammation as well as malignant disorders. However, it has remained unresolved whether Eomes executes similar transcriptional activities as T-bet in CD4⁺ T cells. Here we use a novel genetic approach to show that Eomes expression in CD4⁺ T cells drives a distinct transcriptional program that shows only partial overlap with T-bet. We found that Eomes is sufficient to induce the expression of the immunoregulatory cytokine IL-10 and, together with T-bet, promotes a cytotoxic effector profile, including Prf1, Gzmb, Gzmk, Nkg7 and Ccl5, while repressing alternative cell fates. Our results demonstrate that Eomes⁺ CD4⁺ T cells, which are often found in the context of chronic antigen stimulation, are likely to be a unique CD4⁺ T cell subset that limits inflammation and immunopathology as well as eliminates antigen-presenting and malignant cells.

CD4+ conventional T cells-related genes signature is a prognostic indicator for ovarian cancer

Introduction

It is believed that ovarian cancer (OC) is the most deadly form of gynecological cancer despite its infrequent occurrence, which makes it one of the most salient public health concerns. Clinical and preclinical studies have revealed that intratumoral CD4+ T cells possess cytotoxic capabilities and were capable of directly killing cancer cells. This study aimed to identify the CD4+ conventional T cells-related genes (CD4TGs) with respect to the prognosis in OC.

Methods

We obtained the transcriptome and clinical data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. CD4TGs were first identified from single-cell datasets, then univariate Cox regression was used to screen prognosis-related genes, LASSO was conducted to remove genes with coefficient zero, and multivariate Cox regression was used to calculate riskscore and to construct the CD4TGs risk signature. Kaplan-Meier analysis, univariate Cox regression, multivariate Cox regression, time-dependent receiver operating characteristics (ROC), decision curve analysis (DCA), nomogram, and calibration were made to verify and evaluate the risk signature. Gene set enrichment analyses (GSEA) in risk groups were conducted to explore the tightly correlated pathways with the risk group. The role of riskscore has been further explored in the tumor microenvironment (TME), immunotherapy, and chemotherapy. A risk signature with 11 CD4TGs in OC was finally established in the TCGA database and furtherly validated in several GEO cohorts.

Results

High riskscore was significantly associated with a poorer prognosis and proven to be an independent prognostic biomarker by multivariate Cox regression. The 1-, 3-, and 5-year ROC values, DCA curve, nomogram, and calibration results confirmed the excellent prediction power of this model. Compared with the reported risk models, our model showed better performance. The patients were grouped into high-risk and low-risk subgroups according to the riskscore by the median value. The low-risk group patients tended to exhibit a higher immune infiltration, immune-related gene expression and were more sensitive to immunotherapy and chemotherapy.

Discussion

Collectively, our findings of the prognostic value of CD4TGs in prognosis and immune response, provided valuable insights into the molecular mechanisms and clinical management of OC.

Phenotypic Profile of Mycobacterium tuberculosis-Specific CD4 T-Cell Responses in People With Advanced Human Immunodeficiency Virus Who Develop Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome

Background

Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a frequent complication of cotreatment for TB and human immunodeficiency virus (HIV)-1. We characterized Mycobacterium tuberculosis (Mtb)-specific CD4 T-cell phenotype and transcription factor profile associated with the development of TB-IRIS.

Methods

We examined the role of CD4 T-cell transcription factors in a murine model of mycobacterial IRIS. In humans, we used a longitudinal study design to compare the magnitude of antiretroviral therapy, activation, transcription factor profile, and cytotoxic potential of Mtb-specific CD4 T cells between TB-IRIS (n = 25) and appropriate non-IRIS control patients (n = 18) using flow cytometry.

Results

In the murine model, CD4 T-cell expression of Eomesodermin (Eomes), but not Tbet, was associated with experimentally induced IRIS. In patients, TB-IRIS onset was associated with the expansion of Mtb-specific IFNγ⁺CD4 T cells (P = .039). Patients with TB-IRIS had higher HLA-DR expression (P = .016), but no differences in the expression of T-bet or Eomes were observed. At TB-IRIS onset, Eomes⁺Tbet⁺Mtb-specific IFNγ⁺CD4⁺ T cells showed higher expression of granzyme B in patients with TB-IRIS (P = .026).

Conclusions

Although the murine model of Mycobacterium avium complex-IRIS suggests that Eomes⁺CD4 T cells underly IRIS, TB-IRIS was not associated with Eomes expression in patients. Mycobacterium tuberculosis-specific IFNγ⁺CD4 T-cell responses in TB-IRIS patients are differentiated, highly activated, and potentially cytotoxic.

First-in-human clinical trial of the NKT cell-stimulatory glycolipid OCH in multiple sclerosis

Background

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system that causes the damage to the myelin sheath as well as axonal degeneration. Individuals with MS appear to have changes in the numbers and functions of T-cell subsets, leading to an immunological imbalance accompanied by enhanced autoreactivity. In previous preclinical studies, (2 S,3 S,4R)-1-O-(α-D-Galactopyranosyl)-N-tetracosanoyl-2-amino-1,3,4-nonanetriol (OCH), a synthetic analog of α-galactosylceramide stimulatory for invariant NKT (iNKT) cells, has shown therapeutic or disease-preventive immunoregulatory effects in autoimmune disease models such as experimental autoimmune encephalomyelitis (EAE).

Objectives

This study is the first-in-human study of oral OCH to evaluate the pharmacokinetics and to examine the effects on immune cells as well as related gene expression profiles.

Methods

Fifteen healthy volunteers and 13 MS patients who met the study criteria were enrolled. They were divided into five cohorts and received oral administration of various doses of granulated powder of OCH (0.3-30 mg), once per week for 4 or 13 weeks. Plasma OCH concentrations were measured by high-performance liquid chromatography. Frequencies of lymphocyte subsets in peripheral blood were evaluated by flow cytometry, and microarray analysis was performed to determine OCH-induced changes in gene expression.

Results

Oral OCH was well tolerated, and its bioavailability was found to be sufficient. Six hours after a single dose of OCH, increased frequencies of Foxp3⁺ regulatory T-cells were observed in some cohorts of healthy subjects and MS patients. Furthermore, gene expression analysis demonstrated an upregulation of several immunoregulatory genes and downregulation of pro-inflammatory genes following OCH administration.

Conclusion

This study has demonstrated immunomodulatory effects of the iNKT cell-stimulatory drug OCH in human. Safety profiles together with the presumed anti-inflammatory effects of oral OCH encouraged us to conduct a phase II trial.

T cell responses at diagnosis of amyotrophic lateral sclerosis predict disease progression

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, involving neuroinflammation and T cell infiltration in the central nervous system. However, the contribution of T cell responses to the pathology of the disease is not fully understood. Here we show, by flow cytometric analysis of blood and cerebrospinal fluid (CSF) samples of a cohort of 89 newly diagnosed ALS patients in Stockholm, Sweden, that T cell phenotypes at the time of diagnosis are good predictors of disease outcome. High frequency of CD4+FOXP3- effector T cells in blood and CSF is associated with poor survival, whereas high frequency of activated regulatory T (Treg) cells and high ratio between activated and resting Treg cells in blood are associated with better survival. Besides survival, phenotypic profiling of T cells could also predict disease progression rate. Single cell transcriptomics analysis of CSF samples shows clonally expanded CD4+ and CD8+ T cells in CSF, with characteristic gene expression patterns. In summary, T cell responses associate with and likely contribute to disease progression in ALS, supporting modulation of adaptive immunity as a viable therapeutic option.

Noncytotoxic Roles of Granzymes in Health and Disease

Granzymes are serine proteases previously believed to play exclusive and somewhat redundant roles in lymphocyte-mediated target cell death. However, recent studies have challenged this paradigm. Distinct substrate profiles and functions have since emerged for each granzyme while their dysregulated proteolytic activities have been linked to diverse pathologies.

Regulation of CD4 T Cell Responses by the Transcription Factor Eomesodermin

Central to the impacts of CD4 T cells, both positive in settings of infectious disease and cancer and negative in the settings of autoimmunity and allergy, is their ability to differentiate into distinct effector subsets with specialized functions. The programming required to support such responses is largely dictated by lineage-specifying transcription factors, often called ‘master regulators’. However, it is increasingly clear that many aspects of CD4 T cell immunobiology that can determine the outcomes of disease states involve a broader transcriptional network. Eomesodermin (Eomes) is emerging as an important member of this class of transcription factors. While best studied in CD8 T cells and NK cells, an increasing body of work has focused on impacts of Eomes expression in CD4 T cell responses in an array of different settings. Here, we focus on the varied impacts reported in these studies that, together, indicate the potential of targeting Eomes expression in CD4 T cells as a strategy to improve a variety of clinical outcomes.

Multiple Sclerosis CSF Is Enriched With Follicular T Cells Displaying a Th1/Eomes Signature

BACKGROUND AND OBJECTIVES

Tertiary lymphoid structures and aggregates are reported in the meninges of patients with multiple sclerosis (MS), especially at the progressive stage, and are strongly associated with cortical lesions and disability. Besides B cells, these structures comprise follicular helper T (Tfh) cells that are crucial to support B-cell differentiation. Tfh cells play a pivotal role in amplifying autoreactive B cells and promoting autoantibody production in several autoimmune diseases, but very few are known in MS. In this study, we examined the phenotype, frequency, and transcriptome of circulating cTfh cells in the blood and CSF of patients with relapsing-remitting MS (RRMS).

METHODS

The phenotype and frequency of cTfh cells were analyzed in the blood of 39 healthy controls and 41 untreated patients with RRMS and in the CSF and paired blood of 10 patients with drug-naive RRMS at diagnosis by flow cytometry. Using an in vitro model of blood-brain barrier, we assessed the transendothelial migratory abilities of the different cTfh-cell subsets. Finally, we performed an RNA sequencing analysis of paired CSF cTfh cells and blood cTfh cells in 8 patients sampled at their first demyelinating event.

RESULTS

The blood phenotype and frequency of cTfh cells were not significantly modified in patients with RRMS. In the CSF, we found an important infiltration of Tfh1 cells, with a high proportion of activated PD1⁺ cells. We demonstrated that the specific subset of Tfh1 cells presents increased migration abilities to cross an in vitro model of blood-brain barrier. Of interest, even at the first demyelinating event, cTfh cells in the CSF display specific characteristics with upregulation of EOMES gene and proinflammatory/cytotoxic transcriptomic signature able to efficiently distinguish cTfh cells from the CSF and blood. Finally, interactome analysis revealed potential strong cross talk between pathogenic B cells and CSF cTfh cells, pointing out the CSF as opportune supportive compartment and highlighting the very early implication of B-cell helper T cells in MS pathogenesis.

DISCUSSION

Overall, CSF enrichment in activated Tfh1 as soon as disease diagnosis, associated with high expression of EOMES, and a predicted high propensity to interact with CSF B cells suggest that these cells probably contribute to disease onset and/or activity.

CD4 + Cytotoxic T Lymphocytes in Cancer Immunity and Immunotherapy

CD4⁺ T cells have the ability to differentiate into relatively specialized effector subsets after exposure to innate immune signals. The remarkable plasticity of CD4⁺ T cells is required to achieve immune responses in different tissues and against various pathogens. Numerous studies have shown that CD4⁺ T cells can play direct and indispensable roles in protective immunity by killing infected or transformed cells. Although the lineage decision of commitment to the CD4⁺ or CD8⁺ cell lineage is once thought to be inflexible, the identification of antigen-experienced CD4⁺ T cells with cytotoxic activity suggests the existence of unexpected plasticity for these cells. The recognition of CD4⁺ cytotoxic T lymphocytes (CTLs) and the mechanisms driving the differentiation of this particular cell subset create opportunities to explore the roles of these effector cells in protective immunity and immune-related pathology. CD4⁺ CTLs are proven to play a protective role in antiviral immunity. Here, the latest investigations on the phenotypic and functional features of CD4⁺ CTLs and their roles in antitumor immunity and immunotherapy are briefly reviewed.

Highly tailorable gellan gum nanoparticles as a platform for the development of T cell activator systems

Background

T cell priming has been shown to be a powerful immunotherapeutic approach for cancer treatment in terms of efficacy and relatively weak side effects. Systems that optimize the stimulation of T cells to improve therapeutic efficacy are therefore in constant demand. A way to achieve this is through artificial antigen presenting cells that are complexes between vehicles and key molecules that target relevant T cell subpopulations, eliciting antigen-specific T cell priming. In such T cell activator systems, the vehicles chosen to deliver and present the key molecules to the targeted cell populations are of extreme importance. In this work, a new platform for the creation of T cell activator systems based on highly tailorable nanoparticles made from the natural polymer gellan gum (GG) was developed and validated.

Methods

GG nanoparticles were produced by a water in oil emulsion procedure, and characterized by dynamic light scattering, high resolution scanning electronic microscopy and water uptake. Their biocompatibility with cultured cells was assessed by a metabolic activity assay. Surface functionalization was performed with anti-CD3/CD28 antibodies via EDC/NHS or NeutrAvidin/Biotin linkage. Functionalized particles were tested for their capacity to stimulate CD4⁺ T cells and trigger T cell cytotoxic responses.

Results

Nanoparticles were approximately 150 nm in size, with a stable structure and no detectable cytotoxicity. Water uptake originated a weight gain of up to 3200%. The functional antibodies did efficiently bind to the nanoparticles, as confirmed by SDS-PAGE, which then targeted the desired CD4⁺ populations, as confirmed by confocal microscopy. The developed system presented a more sustained T cell activation over time when compared to commercial alternatives. Concurrently, the expression of higher levels of key cytotoxic pathway molecules granzyme B/perforin was induced, suggesting a greater cytotoxic potential for future application in adoptive cancer therapy.

Conclusions

Our results show that GG nanoparticles were successfully used as a highly tailorable T cell activator system platform capable of T cell expansion and re-education.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00297-z.

Neuropilin-1 (NRP1) expression distinguishes self-reactive helper T cells in systemic autoimmune disease

Pathogenic T helper cells (Th cells) that respond to self-antigen cannot be easily distinguished from beneficial Th cells. These cells can generate systemic autoimmune disease in response to widely expressed self-antigens. In this study, we have identified neuropilin-1 (NRP1) as a cell surface marker of self-reactive Th cells. NRP1⁺ Th cells, absent in non-regulatory T cell subsets in normal mice, appeared in models of systemic autoimmune disease and strongly correlated with disease symptoms. NRP1⁺ Th cells were greatly reduced in Nr4a2 cKO mice, which have reduced self-reactive responses but showed normal responses against exogenous antigens. Transfer of NRP1⁺ Th cells was sufficient to initiate or accelerate systemic autoimmune disease, and targeting NRP1-expressing Th cells therapeutically ameliorated SLE-like autoimmune symptoms in BXSB-Yaa mice. Peripheral NRP1⁺ Th cells were significantly increased in human SLE patients. Our data suggest that self-reactive Th cells can be phenotypically distinguished within the Th cell pool. These findings offer a novel approach to identify self-reactive Th cells and target them to treat systemic autoimmune disease.

CD4+CD8+ T follicular helper cells regulate humoral immunity in chronic inflammatory lesions

T follicular helper (Tfh) cells drive humoral immunity by facilitating B cell responses at the initial and recall phases. Recent studies have indicated the possible involvement of Tfh cells in the process of chronic inflammation. However, the functional role of Tfh cells in persistent immune settings remains unclear. Here, we report that CD4⁺CD8⁺ (double-positive, DP; CD3⁺CD4⁺CD8⁺CXCR5^hiPD-1^hi) Tfh cells, a subset of germinal-center-type Tfh cells, were abundantly present in the fibroinflammatory lesions of patients with immunoglobulin G4-related disease (IgG4-RD). Transcriptome analyses showed that these DP-Tfh cells in the lesions of IgG4-RD preferentially expressed signature genes characteristic of cytotoxic CD8⁺ T cells, such as Eomes, CRTAM, GPR56, and granzymes, in addition to CD70. Scatter diagram analyses to examine the relationships between tissue-resident lymphocytes and various clinical parameters revealed that the levels of DP-Tfh cells were inversely correlated to the levels of serum IgG4 and local IgG4-expressing (IgG4⁺) memory B cells (CD19⁺CD27⁺IgD^-) in patients with IgG4-RD. Cell culture experiments using autologous tonsillar lymphocytes further suggested that DP-Tfh cells possess a poor B-cell helper function and instead regulate memory B cells. Since CD4⁺ (single positive, SP; CD3⁺CD4⁺CD8^-CXCR5^hiPD-1^hi) Tfh cells differentiated into DP-Tfh cells under stimulation with IL-2 and IL-7 as assessed by in vitro experiments, these data imply that SP-Tfh cells are a possible origin of DP-Tfh cells under persistent inflammation. These findings highlight the potential feedback loop mechanism of Tfh cells in immune tolerance under chronic inflammatory conditions. Further studies on DP-Tfh cells may facilitate control of unresolved humoral responses in IgG4-RD pathological inflammation.

Concomitant Cytotoxic Effector Differentiation of CD4+ and CD8+ T Cells in Response to EBV-Infected B Cells

Simple Summary

The Epstein–Barr virus (EBV) is a γ-herpes virus that primarily infects human B cells, and more than 90% of adults have experienced infection. EBV⁺ B cells express several viral proteins, transmitting signals important for the transformation and tumorigenesis of the infected B cells. Immune surveillance by the host immune system is important to suppress such abnormal expansion of EBV-infected B cells. Here we found that both CD4⁺ T cells and CD8⁺ T cells show similar gene expression patterns relating to cytotoxicity towards EBV-infected B cells. EBV-specific cytotoxic CD4⁺ T cells markedly expressed T-bet, Granzyme B, and Perforin alongside killing activity, which could reflect mechanisms shared with cytotoxic CD8⁺ T cells. Our findings support the concept that, upon EBV and perhaps other viral infections, T cells of different subsets can be drawn into common pathways mediating immune surveillance through cytotoxicity.

Abstract

Most people infected by EBV acquire specific immunity, which then controls latent infection throughout their life. Immune surveillance of EBV-infected cells by cytotoxic CD4⁺ T cells has been recognized; however, the molecular mechanism of generating cytotoxic effector T cells of the CD4⁺ subset remains poorly understood. Here we compared phenotypic features and the transcriptome of EBV-specific effector-memory CD4⁺ T cells and CD8⁺ T cells in mice and found that both T cell types show cytotoxicity and, to our surprise, widely similar gene expression patterns relating to cytotoxicity. Similar to cytotoxic CD8⁺ T cells, EBV-specific cytotoxic CD4⁺ T cells from human peripheral blood expressed T-bet, Granzyme B, and Perforin and upregulated the degranulation marker, CD107a, immediately after restimulation. Furthermore, T-bet expression in cytotoxic CD4⁺ T cells was highly correlated with Granzyme B and Perforin expression at the protein level. Thus, differentiation of EBV-specific cytotoxic CD4⁺ T cells is possibly controlled by mechanisms shared by cytotoxic CD8⁺ T cells. T-bet-mediated transcriptional regulation may explain the similarity of cytotoxic effector differentiation between CD4⁺ T cells and CD8⁺ T cells, implicating that this differentiation pathway may be directed by environmental input rather than T cell subset.

Immune aging in multiple sclerosis is characterized by abnormal CD4 T cell activation and increased frequencies of cytotoxic CD4 T cells with advancing age

BACKGROUND

Immunosenescence (ISC) describes age-related changes in immune-system composition and function. Multiple sclerosis (MS) is a lifelong inflammatory condition involving effector and regulatory T-cell imbalance, yet little is known about T-cell ISC in MS. We examined age-associated changes in circulating T cells in MS compared to normal controls (NC).

METHODS

Forty untreated MS (Mean Age 43·3, Range 18-72) and 49 NC (Mean Age 48·6, Range 20-84) without inflammatory conditions were included in cross-sectional design. T-cell subsets were phenotypically and functionally characterized using validated multiparametric flow cytometry. Their aging trajectories, and differences between MS and NC, were determined using linear mixed-effects models.

FINDINGS

MS patients demonstrated early and persistent redistribution of naïve and memory CD4 T-cell compartments. While most CD4 and CD8 T-cell aging trajectories were similar between groups, MS patients exhibited abnormal age-associated increases of activated (HLA-DR+CD38+; (P = 0·013) and cytotoxic CD4 T cells, particularly in patients >60 (EOMES: P < 0·001). Aging MS patients also failed to upregulate CTLA-4 expression on both CD4 (P = 0·014) and CD8 (P = 0·009) T cells, coupled with abnormal age-associated increases in frequencies of B cells expressing costimulatory molecules.

INTERPRETATION

While many aspects of T-cell aging in MS are conserved, the older MS patients harbour abnormally increased frequencies of CD4 T cells with activated and cytotoxic effector profiles. Age-related decreased expression of T-cell co-inhibitory receptor CTLA-4, and increased B-cell costimulatory molecule expression, may provide a mechanism that drives aberrant activation of effector CD4 T cells that have been implicated in progressive disease.

FUNDING

Stated in Acknowledgements section of manuscript.

Single cell sequencing identifies clonally expanded synovial CD4+ TPH cells expressing GPR56 in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease affecting synovial joints where different CD4⁺ T cell subsets may contribute to pathology. Here, we perform single cell sequencing on synovial CD4⁺ T cells from anti-citrullinated protein antibodies (ACPA)+ and ACPA- RA patients and identify two peripheral helper T cell (T_PH) states and a cytotoxic CD4⁺ T cell subset. We show that the adhesion G-protein coupled receptor 56 (GPR56) delineates synovial CXCL13^high T_PH CD4⁺ T cells expressing LAG-3 and the tissue-resident memory receptors CXCR6 and CD69. In ACPA- SF, T_PH cells display lower levels of GPR56 and LAG-3. Further, most expanded T cell clones in the joint are within CXCL13^high T_PH CD4⁺ T cells. Finally, RNA-velocity analyses suggest a common differentiation pathway between the two T_PH clusters and effector CD4⁺ T cells. Our study provides comprehensive immunoprofiling of the synovial CD4⁺ T cell subsets in ACPA+ and ACPA- RA.

Antibodies against citrullinated proteins (ACPA) can divide rheumatoid arthritis patients but the difference in immune phenotype is not clear. Here the authors characterise T peripheral helper cells in arthritic joints comparing ACPA+ and ACPA- patients showing changes in immune cell phenotype and surface molecules.

CD4+ Cytotoxic T cells - Phenotype, Function and Transcriptional Networks Controlling Their Differentiation Pathways

The two major subsets of peripheral T cells are classically divided into the CD4⁺ T helper cells and the cytotoxic CD8⁺ T cell lineage. However, the appearance of some effector CD4⁺ T cell populations displaying cytotoxic activity, in particular during viral infections, has been observed, thus breaking the functional dichotomy of CD4⁺ and CD8⁺ T lymphocytes. The strong association of the appearance of CD4⁺ cytotoxic T lymphocytes (CD4 CTLs) with viral infections suggests an important role of this subset in antiviral immunity by controlling viral replication and infection. Moreover, CD4 CTLs have been linked with anti-tumor activity and might also cause immunopathology in autoimmune diseases. This raises interest into the molecular mechanisms regulating CD4 CTL differentiation, which are poorly understood in comparison to differentiation pathways of other Th subsets. In this review, we provide a brief overview about key features of CD4 CTLs, including their role in viral infections and cancer immunity, and about the link between CD4 CTLs and immune-mediated diseases. Subsequently, we will discuss the current knowledge about transcriptional and epigenetic networks controlling CD4 CTL differentiation and highlight recent data suggesting a role for histone deacetylases in the generation of CD4 CTLs.

Immune-mediated neurodegenerative trait provoked by multimodal derepression of long-interspersed nuclear element-1

Neurodegeneration is a process involving both cell autonomous and non-cell autonomous neuron loss, followed by a collapse of neural networks, but its pathogenesis is poorly understood. We have previously demonstrated that Eomes-positive helper T (Eomes + Th) cells recognizing LINE-1(L1)-derived prototypic antigen ORF1 mediate neurotoxicity associated with the neurodegenerative pathology of experimental autoimmune encephalomyelitis (EAE). Here, we show that Eomes + Th cells accumulate in the CNS of mouse models of authentic neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), and secrete the neurotoxic granzyme B after encounter with ORF1 antigen. Multimodal derepression of neuronal L1 transcription is observed in EAE and ALS/AD models during neurodegeneration in active and cell cycle-mediated manner, respectively. These data suggest that the adventitious concurrence of immune-mediated neurodegenerative traits by Eomes + Th cells and ectopic expression of L1-derived antigen(s) in the inflamed CNS may materialize a communal and previously unappreciated pathogenesis of neurodegeneration.

•

Eomes + Th cells accumulate in the CNS with undergoing neurodegeneration in common

•

Multimodal L1 derepression is emerged in neuron cells under neurodegeneration

•

Eomes + Th cells recognize L1-ORF1 antigen to exert neurotoxicity via granzyme B

•

Immune-mediated neurotoxicity may embody a novel pathogenesis of neurodegeneration

Bona Fide Th17 Cells without Th1 Functional Plasticity Protect against Influenza

Optimal transcriptional programming needed for CD4 T cells to protect against influenza A virus (IAV) is unclear. Most IAV-primed CD4 T cells fit Th1 criteria. However, cells deficient for the Th1 "master regulator," T-bet, although marked by reduced Th1 identity, retain robust protective capacity. In this study, we show that T-bet's paralog, Eomesodermin (Eomes), is largely redundant in the presence of T-bet but is essential for the residual Th1 attributes of T-bet-deficient cells. Cells lacking both T-bet and Eomes instead develop concurrent Th17 and Th2 responses driven by specific inflammatory signals in the infected lung. Furthermore, the transfer of T-bet- and Eomes-deficient Th17, but not Th2, effector cells protects mice from lethal IAV infection. Importantly, these polyfunctional Th17 effectors do not display functional plasticity in vivo promoting gain of Th1 attributes seen in wild-type Th17 cells, which has clouded evaluation of the protective nature of Th17 programming in many studies. Finally, we show that primary and heterosubtypic IAV challenge is efficiently cleared in T-bet- and Eomes double-deficient mice without enhanced morbidity despite a strongly Th17-biased inflammatory response. Our studies thus demonstrate unexpectedly potent antiviral capacity of unadulterated Th17 responses against IAV, with important implications for vaccine design.

Tissue-resident memory CD8+ T cells cooperate with CD4+ T cells to drive compartmentalized immunopathology in the CNS

In chronic inflammatory diseases of the central nervous system (CNS), immune cells persisting behind the blood-brain barrier are supposed to promulgate local tissue destruction. The drivers of such compartmentalized inflammation remain unclear, but tissue-resident memory T cells (T_RM) represent a potentially important cellular player in this process. Here, we investigated whether resting CD8⁺ T_RM persisting after cleared infection with attenuated lymphocytic choriomeningitis virus (LCMV) can initiate immune responses directed against cognate self-antigen in the CNS. We demonstrated that time-delayed conditional expression of the LCMV glycoprotein as neo-self-antigen by glia cells reactivated CD8⁺ T_RM. Subsequently, CD8⁺ T_RM expanded and initiated CNS inflammation and immunopathology in an organ-autonomous manner independently of circulating CD8⁺ T cells. However, in the absence of CD4⁺ T cells, TCF-1⁺ CD8⁺ T_RM failed to expand and differentiate into terminal effectors. Similarly, in human demyelinating CNS autoimmune lesions, we found CD8⁺ T cells expressing TCF-1 that predominantly exhibited a T_RM-like phenotype. Together, our study provides evidence for CD8⁺ T_RM-driven CNS immunopathology and sheds light on why inflammatory processes may evade current immunomodulatory treatments in chronic autoimmune CNS conditions.

Cytotoxicity-Related Gene Expression and Chromatin Accessibility Define a Subset of CD4+ T Cells That Mark Progression to Type 1 Diabetes

Type 1 diabetes in children is heralded by a preclinical phase defined by circulating autoantibodies to pancreatic islet antigens. How islet autoimmunity is initiated and then progresses to clinical diabetes remains poorly understood. Only one study has reported gene expression in specific immune cells of children at risk associated with progression to islet autoimmunity. We analyzed gene expression with RNA sequencing in CD4+ and CD8+ T cells, natural killer (NK) cells, and B cells, and chromatin accessibility by assay for transposase-accessible chromatin sequencing (ATAC-seq) in CD4+ T cells, in five genetically at risk children with islet autoantibodies who progressed to diabetes over a median of 3 years ("progressors") compared with five children matched for sex, age, and HLA-DR who had not progressed ("nonprogressors"). In progressors, differentially expressed genes (DEGs) were largely confined to CD4+ T cells and enriched for cytotoxicity-related genes/pathways. Several top-ranked DEGs were validated in a semi-independent cohort of 13 progressors and 11 nonprogressors. Flow cytometry confirmed that progression was associated with expansion of CD4+ cells with a cytotoxic phenotype. By ATAC-seq, progression was associated with reconfiguration of regulatory chromatin regions in CD4+ cells, some linked to differentially expressed cytotoxicity-related genes. Our findings suggest that cytotoxic CD4+ T cells play a role in promoting progression to type 1 diabetes.

Interactomic inhibition of Eomes in the nucleus alleviates EAE via blocking the conversion of Th17 cells into non-classic Th1 cells

Th17 cells are implicated in the pathogenesis of several autoimmune diseases. During the inflammation, Th17 cells exposed to IL-12 can shift towards the Th1 phenotype. These shifted cells are defined as 'non-classic Th1 cells'. Th17-derived non-classic Th1 cells play a critical role in late-onset chronic inflammatory diseases and are more pathogenic than the unshifted Th17 cells. Eomes is a transcription factor highly expressed in non-classic Th1 cells. To study the functional role of Eomes without genetic alteration, novel recombinant protein, ntEomes-TMD, was generated by fusing TMD of Eomes and Hph-1-PTD that facilitate intracellular delivery of its cargo molecule. ntEomes-TMD was delivered into the nucleus of the cells without influencing the T cell activation and cytotoxicity. ntEomes-TMD specifically inhibited the Eomes- and ROR-γt-mediated transcription and suppressed the Th1 and Th17 differentiation. Interestingly, ntEomes-TMD blocked the generation of non-classic Th1 cells from Th17 cells, leading to the inhibition of IFN-γ and GM-CSF secretion. In EAE, ntEomes-TMD alleviated the symptoms of EAE, and the combination treatment using ntEomes-TMD and anti-IL-17 mAb together showed better therapeutic efficacy than anti-IL-17 mAb treatment. The results suggest that ntEomes-TMD can be a new therapeutic reagent for treating chronic inflammatory diseases associated with non-classic Th1 cells.

Brain Barriers and Multiple Sclerosis: Novel Treatment Approaches from a Brain Barriers Perspective

Multiple sclerosis (MS) is considered a prototypic organ specific autoimmune disease targeting the central nervous system (CNS). Blood-brain barrier (BBB) breakdown and enhanced immune cell infiltration into the CNS parenchyma are early hallmarks of CNS lesion formation. Therapeutic targeting of immune cell trafficking across the BBB has proven a successful therapy for the treatment of MS, but comes with side effects and is no longer effective once patients have entered the progressive phase of the disease. Beyond the endothelial BBB, epithelial and glial brain barriers establish compartments in the CNS that differ in their accessibility to the immune system. There is increasing evidence that brain barrier abnormalities persist during the progressive stages of MS. Here, we summarize the role of endothelial, epithelial, and glial brain barriers in maintaining CNS immune privilege and our current knowledge on how impairment of these barriers contributes to MS pathogenesis. We discuss how therapeutic stabilization of brain barriers integrity may improve the safety of current therapeutic regimes for treating MS. This may also allow for the development of entirely novel therapeutic approaches aiming to restore brain barriers integrity and thus CNS homeostasis, which may be specifically beneficial for the treatment of progressive MS.

Cytotoxic CD4+ T cells in cancer: Expanding the immune effector toolbox

Cytotoxic T cells are important effectors of anti-tumor immunity. While tumor killing is ascribed to CD8⁺ T cell function, pre-clinical and clinical studies have identified intra-tumoral CD4⁺ T cells that possess cytotoxic programs and can directly kill cancer cells. Cytotoxic CD4⁺ T cells are found in other disease settings including infection and autoimmunity. Here, we review the phenotypic and functional characteristics of cytotoxic CD4⁺ T cells in non-cancer and cancer contexts. We conduct a comparative examination of cytolytic mechanisms of cytotoxic CD4⁺ T cells across disease states and synthesize features that define these cells independent of context. We discuss regulatory mechanisms driving ontogeny and effector function and evidence for the clinical relevance of cytotoxic CD4⁺ T cells in cancer. In this context, we highlight important gaps in understanding in the biology of cytotoxic CD4⁺ T cells as well as the potential use of these cells in immunotherapies for specific cancers.

Insights into T-cell dysfunction in Alzheimer's disease

T cells, the critical immune cells of the adaptive immune system, are often dysfunctional in Alzheimer's disease (AD) and are involved in AD pathology. Reports highlight neuroinflammation as a crucial modulator of AD pathogenesis, and aberrant T cells indirectly contribute to neuroinflammation by secreting proinflammatory mediators via direct crosstalk with glial cells infiltrating the brain. However, the mechanisms underlying T‐cell abnormalities in AD appear multifactorial. Risk factors for AD and pathological hallmarks of AD have been tightly linked with immune responses, implying the potential regulatory effects of these factors on T cells. In this review, we discuss how the risk factors for AD, particularly Apolipoprotein E (ApoE), Aβ, α‐secretase, β‐secretase, γ‐secretase, Tau, and neuroinflammation, modulate T‐cell activation and the association between T cells and pathological AD hallmarks. Understanding these associations is critical to provide a comprehensive view of appropriate therapeutic strategies for AD.

STAT3-Specific Single Domain Nanobody Inhibits Expansion of Pathogenic Th17 Responses and Suppresses Uveitis in Mice

STAT3 activates transcription of genes that regulate cell growth, differentiation, and survival of mammalian cells. Genetic deletion of Stat3 in T cells has been shown to abrogate Th17 differentiation, suggesting that STAT3 is a potential therapeutic target for Th17-mediated diseases. However, a major impediment to therapeutic targeting of intracellular proteins such as STAT3 is the lack of efficient methods for delivering STAT3 inhibitors into cells. In this study, we developed a novel antibody (SBT-100) comprised of the variable (V) region of a STAT3-specific heavy chain molecule and demonstrate that this 15 kDa STAT3-specific nanobody enters human and mouse cells, and induced suppression of STAT3 activation and lymphocyte proliferation in a concentration-dependent manner. To investigate whether SBT-100 would be effective in suppressing inflammation in vivo, we induced experimental autoimmune uveitis (EAU) in C57BL/6J mice by active immunization with peptide from the ocular autoantigen, interphotoreceptor retinoid binding protein (IRBP_651-670). Analysis of the retina by fundoscopy, histological examination, or optical coherence tomography showed that treatment of the mice with SBT-100 suppressed uveitis by inhibiting expansion of pathogenic Th17 cells that mediate EAU. Electroretinographic (ERG) recordings of dark and light adapted a- and b-waves showed that SBT-100 treatment rescued mice from developing significant visual impairment observed in untreated EAU mice. Adoptive transfer of activated IRBP-specific T cells from untreated EAU mice induced EAU, while EAU was significantly attenuated in mice that received IRBP-specific T cells from SBT-100 treated mice. Taken together, these results demonstrate efficacy of SBT-100 in mice and suggests its therapeutic potential for human autoimmune diseases.

CD4+ T cells are essential for the development of destructive thyroiditis induced by anti-PD-1 antibody in thyroglobulin-immunized mice

Immune-related adverse events induced by anti-programmed cell death-1 antibodies (PD-1-Ab), including destructive thyroiditis (thyroid-irAE), are thought to be caused by activated T cells. However, the T cell subsets that are directly responsible for damaging self-organs remain unclear. To clarify which T cell subsets are involved in the development of thyroid-irAE, a mouse model of thyroid-irAE was analyzed. PD-1-Ab administration 2.5 months after immunization with thyroglobulin caused destructive thyroiditis. Thyroiditis was completely prevented by previous depletion of CD4⁺ T cells and partially prevented by depleting CD8⁺ T cells. The frequencies of central and effector memory CD4⁺ T cell subsets and the secretion of interferon-γ after stimulation with thyroglobulin were increased in the cervical lymph nodes of mice with thyroid-irAE compared with controls. Histopathological analysis revealed infiltration of CD4⁺ T cells expressing granzyme B in thyroid glands and major histocompatibility complex class II expression on thyrocytes in mice with thyroid-irAE. Adoptive transfer of CD4⁺ T cells from cervical lymph nodes in mice with thyroid-irAE caused destruction of thyroid follicular architecture in the irradiated recipient mice. Flow cytometric analyses showed that the frequencies of central and effector memory CD4⁺ T cells expressing the cytotoxic marker CD27 were higher in peripheral blood mononuclear cells collected from patients with thyroid-irAE induced by PD-1-Ab versus those without. These data suggest a critical role for cytotoxic memory CD4⁺ T cells activated by PD-1-Ab in the pathogenesis of thyroid-irAE.

Involvement of cytotoxic Eomes-expressing CD4+ T cells in secondary progressive multiple sclerosis

Multiple sclerosis (MS), a putative autoimmune disease of the central nervous system (CNS), commonly presents as relapsing-remitting MS (RRMS), characterized by recurrent episodes of peripheral disabling symptoms resulting from inflammatory CNS damage. Many RRMS patients transition to a chronic disease course with progressive neurological dysfunctions (secondary progressive MS, SPMS), with the progression rate varying between patients and over time. SPMS pathogenesis is now linked to immune-cell-mediated processes, although the mechanisms driving SPMS transition and progression remain elusive, and SPMS lacks biomarkers and effective treatments. We report the crucial involvement of cytotoxic CD4⁺ T cells expressing Eomes (Eomes⁺ Th cells) in SPMS pathogenesis-a Th cell subset previously identified in a mouse model of late/chronic autoimmune CNS inflammation. Few Eomes⁺ Th cells circulate in RRMS patient peripheral blood (n = 44), primary progressive MS (PPMS) patients (n = 25), or healthy controls (n = 42), but Eomes⁺ Th cells were significantly increased in SPMS (n = 105, P < 0.0001). Strikingly, lymphocytes isolated from SPMS autopsy brain samples revealed CD4⁺ T cells infiltrating CNS that coexpressed Eomes and the cytotoxic molecule granzyme B. In particular, the Eomes⁺ Th cell levels were increased in SPMS patients in progressive disease phases versus SPMS patients without current disability increases (P < 0.0001). Moreover, Eomes level acted as a biomarker to predict SPMS patients at risk of disease worsening with over 80% accuracy (ROC-AUC = 0.8276). Overall, our results indicate that granzyme B-expressing Eomes⁺ T helper cells are involved in the pathogenesis of SPMS, with significant implications for SPMS biomarkers and therapeutic targets.