T cell signaling abnormalities contribute to aberrant immune cell function and autoimmunity

Tofacitinib therapy in systemic lupus erythematosus with arthritis: a retrospective study

OBJECTIVE

To estimate the effectiveness and safety of tofacitinib in treating systemic lupus erythematosus (SLE) patients with arthritis.

METHODS

This research was a retrospective cohort study that focused on SLE patients who had arthritis and were treated with tofacitinib at the Department of Rheumatology and Immunology from January 2020 to January 2022. Clinical outcomes, disease activity, immunological parameters, and adverse events were systematically evaluated pre- and post-treatment at 4, 12, and 24 weeks.

RESULTS

Twenty-two patients were analyzed. At the 4-week mark, 5 (22.7%) patients were partially relieved, and 17 (77.3%) unalleviated. By the 12-week assessment, CR off corticosteroids was observed in four patients (18.2%), and CR on corticosteroids was seen in six patients (27.3%), with an additional six (27.3%) maintaining partial remission. At 24 weeks after treatment, three patients (13.6%) achieved CR off corticosteroids, ten patients (45.5%) achieved CR on corticosteroids, and all patients received remission. Compared to before treatment, The SLEDAI and PGA scores significantly improved. The level of C3 was increased significantly, and the absolute CD3+ T cell count, the 28-tender and the 28-swollen joint count, and the levels of serum IL-6 were significantly decreased at 24 weeks after treatment.

CONCLUSION

Tofacitinib demonstrates significant therapeutic potential in SLE patients with arthritis, with a safety profile, and the therapeutic mechanism of tofacitinib may be related to reducing IL-6 expression and inhibiting T cell activation. Key Points • Tofacitinib demonstrates significant therapeutic potential in SLE patients with arthritis • The therapeutic mechanism of tofacitinib may be related to reducing IL-6 expression and inhibiting T cell activation.

Immunosuppressive alkaloids from Narcissus tazetta subsp. Chinensis and the mechanism of (+)-narciclasine in vitro and in vivo

Three previously undescribed and sixteen known alkaloids were bioguidedly isolated from the bulbs of Narcissus tazetta subsp. chinensis (M.Roem.) Masamura & Yanagih. The structures were elucidated by spectroscopic data, including HRESIMS, NMR, and ECD. Eleven of the isolated alkaloids exhibited immunosuppressive activity on the proliferation of human T cells. (+)-Narciclasine (18) showed the most significantly suppressive activity with an IC50 value of 14 ± 5 nM. In vitro, (+)-narciclasine (18) blocked NF-κB signal transduction, but did not affect PI3K/AKT signal transduction. What was more, (+)-narciclasine significantly reduced ALT and AST levels and alleviated liver damage induced by ConA in AIH mouse model.

The Role of m6A Methylation in Tumor Immunity and Immune-Associated Disorder

N6-methyladenosine (m6A) represents the most prevalent and significant internal modification in mRNA, with its critical role in gene expression regulation and cell fate determination increasingly recognized in recent research. The immune system, essential for defense against infections and maintaining internal stability through interactions with other bodily systems, is significantly influenced by m6A modification. This modification acts as a key post-transcriptional regulator of immune responses, though its effects on different immune cells vary across diseases. This review delineates the impact of m6A modification across major system-related cancers-including those of the respiratory, digestive, endocrine, nervous, urinary reproductive, musculoskeletal system malignancies, as well as acute myeloid leukemia and autoimmune diseases. We explore the pathogenic roles of m6A RNA modifications within the tumor immune microenvironment and the broader immune system, highlighting how RNA modification regulators interact with immune pathways during disease progression. Furthermore, we discuss how the expression patterns of these regulators can influence disease susceptibility to immunotherapy, facilitating the development of diagnostic and prognostic models and pioneering new therapeutic approaches. Overall, this review emphasizes the challenges and prospective directions of m6A-related immune regulation in various systemic diseases throughout the body.

The immunology of systemic lupus erythematosus

Understanding the pathogenesis and clinical manifestations of systemic lupus erythematosus (SLE) has been a great challenge. Reductionist approaches to understand the nature of the disease have identified many pathogenetic contributors that parallel clinical heterogeneity. This Review outlines the immunological control of SLE and looks to experimental tools and approaches that are improving our understanding of the complex contribution of interacting genetics, environment, sex and immunoregulatory factors and their interface with processes inherent to tissue parenchymal cells. Efforts to advance precision medicine in the care of patients with SLE along with treatment strategies to correct the immune system hold hope and are also examined.

The PP2A regulatory subunit PPP2R2A controls NAD+ biosynthesis to regulate T cell subset differentiation in systemic autoimmunity

The protein phosphatase 2A (PP2A) regulatory subunit PPP2R2A is involved in the regulation of immune response. We report that lupus-prone mice with T cells deficient in PPP2R2A display less autoimmunity and nephritis. PPP2R2A deficiency promotes NAD+ biosynthesis through the nicotinamide riboside (NR)-directed salvage pathway in T cells. NR inhibits murine Th17 and promotes Treg cell differentiation, in vitro, by PΑRylating histone H1.2 and causing its reduced occupancy in the Foxp3 loci and increased occupancy in the Il17a loci, leading to increased Foxp3 and decreased Il17a transcription. NR treatment suppresses disease in MRL.lpr mice and restores NAD+-dependent poly [ADP-ribose] polymerase 1 (PARP1) activity in CD4 T cells from patients with systemic lupus erythematosus (SLE), while reducing interferon (IFN)-γ and interleukin (IL)-17 production. We conclude that PPP2R2A controls the level of NAD+ through the NR-directed salvage pathway and promotes systemic autoimmunity. Translationally, NR suppresses lupus nephritis in mice and limits the production of proinflammatory cytokines by SLE T cells.

Mesenchymal stem cells-derived extracellular vesicles ameliorate lupus nephritis by regulating T and B cell responses

BACKGROUND

Human umbilical cord mesenchymal stem cells-derived extracellular vesicles (hUCMSC-EVs) have potent immunomodulatory properties similar to parent cells. This study investigated the therapeutic effects and immunomodulatory mechanisms of hUCMSC-EVs in an experimental lupus nephritis model.

METHODS

The hUCMSC-EVs were isolated by using differential ultracentrifugation. In vivo, the therapeutic effects of hUCMSC-EVs in lupus-prone MRL/lpr mice were investigated, and the mechanisms of treatment were explored according to the abnormal T and B cell responses among both the spleen and kidney.

RESULTS

MRL/lpr mice treated with hUCMSC-EVs reduced proteinuria extent, serum creatinine and renal pathological damage; decreased splenic index and serum anti-dsDNA IgG level; and improved survival rate. hUCMSC-EVs lowered the percentage of T helper (Th)1 cells, double-negative T (DNT) cells, and plasma cells among splenocytes; inhibited the infiltration of Th17 cells but promoted regulatory T (Treg) cells in the kidney, followed by a reduction in pro-inflammatory cytokine levels(IFN-γ, IL-2, IL-6, IL-21, and IL-17 A). In addition, hUCMSC-EVs inhibited the activation of STAT3 and down-regulated IL-17 A protein levels in the kidney.

CONCLUSION

The results of this study demonstrated that hUCMSC-EVs had therapeutic effects on experimental lupus nephritis (LN) by regulating Th1/Th17/Treg imbalance and inhibiting DNT and plasma cells. Additionally, hUCMSC-EVs inhibited Th17 cell differentiation in kidney by regulating the IL-6/STAT3/IL-17 signal pathway, which might be an important mechanism for alleviating renal injury. Taken together, we demonstrated that hUCMSC-EVs regulating T and B cell immune responses might represent a novel mechanism of hUCMSCs in treating LN, thus providing a new strategy for treating LN.

Phosphatidic Acid Promoting the Generation of Interleukin-17A Producing Double-Negative T Cells by Enhancing mTORC1 Signaling in Lupus

OBJECTIVE

The goal was to investigate the role and intracellular regulatory mechanisms of double-negative T (DNT) cells in the pathogenesis of systemic lupus erythematosus (SLE).

METHODS

DNT cells were assessed in murine models, patients with SLE, and controls using flow cytometry (FCM). DNT cells from either resiquimod (R848) or vehicle-treated C57BL/6 (B6) mice were cultured with B cells from R848-treated mice to explore functions. Differential mechanistic target of rapamycin (mTOR) pathway signaling in DNT cells measured using FCM and quantitative polymerase chain reaction was validated by rapamycin inhibition. Candidate lipid metabolites detected using liquid chromatography with electrospray ionization mass spectrometry/mass spectrometry were functionally assessed in DNT cell cultures.

RESULTS

DNT cells were markedly increased in both spontaneous and induced mouse lupus models and in patients with SLE. Expanded DNT cells from R848-treated B6 mice produced elevated interleukin (IL)-17A and IgG with increased germinal center B (GCB) cells. Expansion of DNT cells associated with activation of mTORC1 pathway that both IL-17A levels and the number of DNT cells exhibited dose-dependent reduction with rapamycin treatment. Lipidomics studies revealed differential patterns of lipid metabolites in T cells of R848-treated mice. Among candidate metabolites, elevated phosphatidic acid (PA) that was partially controlled by phospholipase D2 increased the expression of the mTORC1 downstream target p-S6 and positively expanded IL-17A-producing DNT cells. Similarly, elevated proportions of circulating DNT cells in patients with SLE correlated with disease activity and proteinuria, and IL-17A secretion was elevated after in vitro PA stimulation.

CONCLUSION

The accumulation of PA in T cells could activate the mTORC1 pathway, promoting DNT cell expansion and IL-17A secretion, resulting in GCB cell abnormalities in lupus.

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

Roles of IRF4 in various immune cells in systemic lupus erythematosus

Interferon regulatory factor 4 (IRF4) is a member of IRF family of transcription factors which mainly regulates the transcription of IFN. IRF4 is restrictively expressed in immune cells such as T and B cells, macrophages, as well as DC. It is essential for the development and function of these cells. Since these cells take part in the homeostasis of the immune system and dysfunction of them contributes to the initiation and progress of systemic lupus erythematosus (SLE), the roles of IRF4 in the SLE development becomes an important topic. Here we systemically discuss the biological characteristics of IRF4 in various immune cells and analyze the pathologic effects of IRF4 alteration in SLE and the potential targeting therapeutics of SLE.

Novel therapeutic strategies targeting abnormal T-cell signaling in systemic lupus erythematosus

Therapeutic strategies for autoimmune diseases have been based on the use of glucocorticoids and immunosuppressive agents that broadly suppress immune responses. Therefore, organ damage from long-term use and infections due to immunocompromised status have been significant issues. Safer immunosuppressants and biological agents are now available, but there is still an urgent need to develop specific drugs to replace glucocorticoids. T-lymphocytes, central players in immune responses, could be crucial targets in the treatment of autoimmune diseases. Extensive research has been conducted on the phenotypic changes of T-cells in systemic lupus erythematosus, which has led to the discovery of various therapeutic strategies. In this comprehensive review, we discuss novel treatment approaches and target molecules with expected effectiveness in humans and mice, based on research for lymphocytes involved in autoimmune diseases, especially T-cells in SLE.

Ectopic CD4+ T cells in choroid plexus mediate neuropsychiatric lupus symptoms in mice via interferon-γ induced microglia activation

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a disabling and potentially life-threatening complication of SLE. This study aims to investigate whether ectopic CD4+ T cells in the choroid plexus mediate NPSLE in mice. Intracerebroventricular (ICV) injection of anti-CD4 antibody effectively depleted CP-resident CD4+ T cells and alleviated NPSLE-like symptoms in MRL/lpr mice. Following ICV injection, the majority of isolated lupus CD4+ T cells from donor MRL/lpr mice predominantly stayed in the CP for at least 28 days in recipient C57BL/6 mice, while nearly all isolated CD4+ T cells from MRL/MpJ mice disappeared within 7 days. ICV injection of lupus CD4+ T cells resulted in NPSLE-like symptoms, including impaired behavioral performances, increased microglial activation, and abnormal microstructure changes. Flow cytometry analysis revealed that the majority of isolated lupus CD4+ T cells were positive for IFN-γ. Neutralizing intracerebral IFN-γ alleviated NPSLE-like symptoms in MRL/lpr mice. Moreover, ICV injection of anti-IFN-γ antibody or microglial depletion by PLX3397 benefited most NPSLE-like symptoms in lupus CD4+ T-treated mice, while ICV injection of IFN-γ mimicked most NPSLE-like symptoms. In conclusion, CP-resident lupus CD4+ T cells contribute to NPSLE-like symptoms in mice via Interferon-γ induced microglia activation. Depleting CP-resident lupus CD4+ T cells, interferon-γ, or activated microglia may be potential therapeutic targets for NPSLE.

Understanding the pathogenic significance of altered calcium-calmodulin signaling in T cells in autoimmune diseases

Calcium/calmodulin-dependent protein kinase IV (CaMK4) serves as a pivotal mediator in the regulation of gene expression, influencing the activity of transcription factors within a variety of immune cells, including T cells. Altered CaMK4 signaling is implicated in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, which are characterized by dysregulated immune responses and clinical complexity. These conditions share common disturbances in immune cell functionality, cytokine production, and autoantibody generation, all of which are associated with disrupted calcium-calmodulin signaling. This review underscores the consequences of dysregulated CaMK4 signaling across these diseases, with an emphasis on its impact on Th17 differentiation and T cell metabolism-processes central to maintaining immune homeostasis. A comprehensive understanding of roles of CaMK4 in gene regulation across various autoimmune disorders holds promise for the development of targeted therapies, particularly for diseases driven by Th17 cell dysregulation.

Concomitant use of interleukin-2 and tacrolimus suppresses follicular helper T cell proportion and exerts therapeutic effect against lupus nephritis in systemic lupus erythematosus-like chronic graft versus host disease

Introduction

Defective interleukin-2 (IL-2) production contributes to immune system imbalance in patients with systemic erythematosus lupus (SLE). Recent clinical studies suggested that low-dose IL-2 treatment is beneficial for SLE and the therapeutic effect is associated with regulatory T cell (Treg) expansion. Pharmacological calcineurin inhibition induces a reduction in the number of Tregs because they require stimulation of T cell receptor signaling and IL-2 for optimal proliferation. However, the activation of T cell receptor signaling is partially dispensable for the expansion of Tregs, but not for that of conventional T cells if IL-2 is present.

Aim

We examined whether addition of IL-2 restores the Treg proportion even with concurrent use of a calcineurin inhibitor and if the follicular helper T cell (Tfh) proportion is reduced in an SLE-like murine chronic graft versus host disease model.

Methods

Using a parent-into-F1 model, we investigated the effect of IL-2 plus tacrolimus on Treg and Tfh proportions and the therapeutic effect.

Results

Treatment with a combination of IL-2 and tacrolimus significantly delayed the initiation of proteinuria and decreased the urinary protein concentration, whereas tacrolimus or IL-2 monotherapy did not significantly attenuate proteinuria. Phosphorylation of signal transducer and activator of transcription 3, a positive regulator of Tfh differentiation, was reduced by combination treatment, whereas phosphorylation of signal transducer and activator of transcription 5, a negative regulator, was not reduced.

Conclusion

Addition of calcineurin inhibitors as adjunct agents may be beneficial for IL-2-based treatment of lupus nephritis.

ω-3 polyunsaturated fatty acid alleviates systemic lupus erythematosus by suppressing autoimmunity in a murine model

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune inflammatory disease that damages multiple organs by the production of autoantibodies. Numerous research studies have demonstrated the anti-inflammatory effects of ω-3 polyunsaturated fatty acids (PUFAs). A diet rich in ω-3 PUFAs reduces chronic inflammatory and autoimmune conditions. Herein, we investigated the protective effect of ω-3 PUFAs against autoimmune injury in SLE. In a TMPD-induced mouse model of SLE, supplementation with eicosapentaenoic acid (EPA)-rich (97%) fish oil was found to alleviate systemic autoimmune phenotypes such as ascites, lipogranulomas and serum dsDNA levels. In addition, EPA also significantly improved renal manifestations, reducing proteinuria, glomerulonephritis, and immune complex deposition. Mechanistically, ω-3 PUFAs were shown to modulate the differentiation of B lymphocyte subsets of primary splenic lymphocytes in the spontaneous murine lupus model MRL/MpJ-Faslpr in vitro, specifically that both EPA and DHA suppressed the number of total B cells, B1B2 cells and plasma cells. Concurrently, they were also found to promote the secretion of the anti-inflammatory cytokine IL10, mainly produced by Breg and Treg cells. Thus, nutritional supplementation with ω-3 PUFAs can regulate B cell's differentiation and anti-inflammatory function and strongly prevent autoimmune responses and lupus nephritis. The diets balance between ω-6 and ω-3 PUFAs intake may represent a promising treatment strategy to prevent or delay the onset of SLE.

Faslpr gene dosage tunes the extent of lymphoproliferation and T cell differentiation in lupus

Sle1 and Faslpr are two lupus susceptibility loci that lead to manifestations of systemic lupus erythematosus. To evaluate the dosage effects of Faslpr in determining cellular and serological phenotypes associated with lupus, we developed a new C57BL/6 (B6) congenic lupus strain, B6.Sle1/Sle1.Faslpr/+ (Sle1homo.lprhet) and compared it with B6.Faslpr/lpr (lprhomo), B6.Sle1/Sle1 (Sle1homo), and B6.Sle1/Sle1.Faslpr/lpr (Sle1homo.lprhomo) strains. Whereas Sle1homo.lprhomo mice exhibited profound lymphoproliferation and early mortality, Sle1homo.lprhet mice had a lifespan comparable to B6 mice, with no evidence of splenomegaly or lymphadenopathy. Compared to B6 monogenic lupus strains, Sle1homo.lprhet mice exhibited significantly elevated serum ANA antibodies and increased proteinuria. Additionally, Sle1homo.lprhet T cells had an increased propensity to differentiate into Th1 cells. Gene dose effects of Faslpr were noted in upregulating serum IL-1⍺, IL-2, and IL-27. Taken together, Sle1homo.lprhet strain is a new C57BL/6-based model of lupus, ideal for genetic studies, autoantibody repertoire investigation, and for exploring Th1 effector cell skewing without early-age lymphoproliferative autoimmunity.

Helios as a Potential Biomarker in Systemic Lupus Erythematosus and New Therapies Based on Immunosuppressive Cells

The Helios protein (encoded by the IKZF2 gene) is a member of the Ikaros transcription family and it has recently been proposed as a promising biomarker for systemic lupus erythematosus (SLE) disease progression in both mouse models and patients. Helios is beginning to be studied extensively for its influence on the T regulatory (Treg) compartment, both CD4+ Tregs and KIR+/Ly49+ CD8+ Tregs, with alterations to the number and function of these cells correlated to the autoimmune phenomenon. This review analyzes the most recent research on Helios expression in relation to the main immune cell populations and its role in SLE immune homeostasis, specifically focusing on the interaction between T cells and tolerogenic dendritic cells (tolDCs). This information could be potentially useful in the design of new therapies, with a particular focus on transfer therapies using immunosuppressive cells. Finally, we will discuss the possibility of using nanotechnology for magnetic targeting to overcome some of the obstacles related to these therapeutic approaches.

Diagnostic Values of METTL1-Related Genes and Immune Characteristics in Systemic Lupus Erythematosus

Purpose

Methyltransferase like 1 (METTL1) regulates epitranscriptomes via the m7G modification in mammalian mRNA and microRNA. Systemic lupus erythematosus (SLE) is caused by abnormal immune reactivity and has diverse clinical manifestations. RNA methylation as a mechanism to regulate gene expression is widely implicated in immune regulation. However, the role of m7G in immune response of SLE has not been extensively studied.

Patients and Methods

Expression of METTL1 was identified in the public dataset GSE122459 and validated in an independent cohort of SLE patients. We investigated the association between METTL1-expression and clinical manifestations of SLE. Subsequently, differentially expressed genes (DEG) that were correlated with METTL1-expression in GSE122459 were used for functional enrichment analysis. The correlation between infiltrating immune cells and METTL1, as well as candidate biomarkers identified to be correlated with either METTL1 or immune cell infiltration were assessed by single-sample GSEA. Potential mechanisms were explored with Gene ontology and KEGG pathway enrichment. Diagnostic performances of candidate biomarkers in SLE were analyzed.

Results

The mRNA and protein expression of METTL1 in SLE patients were significantly decreased in both datasets. METTL1-coexpressed DEGs were enriched in several key immune-related pathways. Activated CD8 T cells, activated CD4 T cells, memory B cells and type 2 helper T cells were different between patients with high and low METTL1 expression. Further, activated CD8 T-cells, activated CD4 T-cells, memory B-cells were correlated with METTL1. The genes of LAMP3, CD83, PDCD1LG2, IGKVD3D-20, IGKV5-2, IGKV2D-30, IGLV3-19 and IGLV4-60 were identified as candidate targets that were correlated with immune cell proportion. Moreover, LAMP3, CD83, and PDCD1LG2 expression were of diagnostic value in SLE as indicated by ROC analysis.

Conclusion

Our findings suggested that METTL1 and its candidate targets LAMP3, CD83, PDCD1LG2 may be used for diagnosing SLE and could be explored for developing targeted molecular therapy for SLE.

Coordinated Priming of NKG2D Pathway by IL-15 Enhanced Functional Properties of Cytotoxic CD4+CD28- T Cells Expanded in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder, and numerous aberrations of T cell responses have been reported and were implicated in its pathophysiology. Recently, CD4-positive T cells with cytotoxic potential were shown to be involved in autoimmune disease progression and tissue damage. However, the effector functions of this cell type and their potential molecular mechanisms in SLE patients remain to be elucidated. In this study, we find that cytotoxic CD4+CD28- T cells are expanded in SLE patients with flow cytometry analysis, and the percentage of CD4+CD28- T cells positively correlates with the Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI). Furthermore, our study suggests that interleukin-15 (IL-15) promotes the expansion, proliferation, and cytotoxic function of CD4+CD28- T cells in SLE patients through activation of the Janus kinase3-STAT5 pathway. Further study indicates that IL-15 not only mediates the upregulation of NKG2D, but also cooperates with the NKG2D pathway to regulate the activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway. Together, our study demonstrated that proinflammatory and cytolytic CD4+CD28- T cells expand in SLE patients. The pathogenic potential of these CD4+CD28- T cells is driven by the coupling of the IL-15/IL-15R signaling pathway and the NKG2D/DAP10 signaling pathway, which may open new avenues for therapeutic intervention to prevent SLE progression.

From systemic lupus erythematosus to lupus nephritis: The evolving road to targeted therapies

Systemic lupus erythematosus is a chronic autoimmune disease characterized by loss of tolerance against nuclear and cytoplasmic self-antigens, induction of immunity and tissue inflammation. Lupus nephritis (LN), the most important predictor of morbidity in SLE, develops in almost 30% of SLE patients at disease onset and in up to 50-60% within the first 10 years. Firstly, in this review, we put the pathogenic mechanisms of the disease into a conceptual frame, giving emphasis to the role of the innate immune system in this loss of self-tolerance and the induction of the adaptive immune response. In this aspect, many mechanisms have been described such as dysregulation and acceleration of cell-death pathways, an aberrant clearance and overload of immunogenic acid-nucleic-containing debris and IC, and the involvement of antigen-presenting cells and other innate immune cells in the induction of this adaptive immune response. This result in a clonal expansion of autoreactive lymphocytes with generation of effector T-cells, memory B-cells and plasma cells that produce autoantibodies that will cause kidney damage. Secondly, we review the immunological pathways of damage in the kidney parenchyma, initiated by autoantibody binding and immune complex deposition, and followed by complement-mediated microvascular injury, activation of kidney stromal cells and the recruitment of leukocytes. Finally, we summarize the rationale for the treatment of LN, from conventional to new targeted therapies, focusing on their systemic immunologic effects and the minimization of podocytary damage.

Mechanical Properties Affect Primary T Cell Activation in 3D Bioprinted Hydrogels

T cells play a critical role in the adaptive immune response of the body, especially against intracellular pathogens and cancer. In vitro, T cell activation studies typically employ planar (two-dimensional, 2D) culture systems that do not mimic native cell-to-extracellular matrix (ECM) interactions, which influence activation. The goal of this work was to study T cell responses in a cell line (EL4) and primary mouse T cells in three-dimensional (3D) bioprinted matrices of varied stiffness. Cell-laden hydrogels were 3D bioprinted from gelatin methacryloyl (GelMA) using a digital light processing (DLP)-based 3D bioprinter operated with visible light (405 nm). Mechanical characterization revealed that the hydrogels had pathophysiologically relevant stiffnesses for a lymph node-mimetic tissue construct. EL4, a mouse T cell lymphoma line, or primary mouse T cells were 3D bioprinted and activated using a combination of 10 ng/mL of phorbol myristate acetate (PMA) and 0.1 μM of ionomycin. Cellular responses revealed differences between 2D and 3D cultures and that the biomechanical properties of the 3D bioprinted hydrogel influence T cell activation. Cellular responses of the 2D and 3D cultures in a soft matrix (19.83 ± 2.36 kPa) were comparable; however, they differed in a stiff matrix (52.95 ± 1.36 kPa). The fraction of viable EL4 cells was 1.3-fold higher in the soft matrix than in the stiff matrix. Furthermore, primary mouse T cells activated with PMA and ionomycin showed 1.35-fold higher viable cells in the soft matrix than in the stiff matrix. T cells bioprinted in a soft matrix and a stiff matrix released 7.4-fold and 5.9-fold higher amounts of interleukin-2 (IL-2) than 2D cultured cells, respectively. Overall, the study demonstrates the changes in the response of T cells in 3D bioprinted scaffolds toward engineering an ex vivo lymphoid tissue-mimetic system that can faithfully recapitulate T cell activation and unravel pathophysiological characteristics of T cells in infectious biology, autoimmunity, and cancers.

ICOS gene polymorphisms in systemic lupus erythematosus: A case-control study

The inducible T-cell costimulator (ICOS) may play an important role in adaptive immunity by regulating the interaction between T cells and antigen-presenting cells. Disruption of this molecule can lead to autoimmune diseases, in particular systemic lupus erythematosus (SLE). In this study, we aimed to explore the possible association between ICOS gene polymorphisms and SLE as well as their influence on disease susceptibility and clinical outcomes. A further objective was to assess the potential impact of these polymorphisms on RNA expression. A case-control study, including 151 patients with SLE, and 291 unrelated healthy controls (HC) matched in gender, and geographical origin, was performed to genotype two polymorphisms located in the ICOS gene: rs11889031 (-693 G/A) and rs10932029 (IVS1 + 173 T/C); using the polymerase chain reaction (PCR)-restriction fragment length polymorphism method. The different genotypes were validated by direct sequencing. The expression level of ICOS mRNA was assessed by quantitative PCR in peripheral blood mononuclear cells of SLE patients and HC. The results were analysed using Shesis and spss.20. Our results revealed a significant association between ICOS gene rs11889031 > CC genotype and SLE disease (codominant genetic model 1, (C/C vs. C/T), p = .001, odds ratio [OR] = 2.18 IC [1.36-3.49]); codominant genetic model 2, (C/C vs. T/T) p = .007, OR = 15.29 IC [1.97-118.5]); dominant genetic model, (C/C vs. C/T + T/T) p = .0001, OR = 2.44 IC [1.53-3.9]). Besides, there was a marginal association between rs11889031 > TT genotype and T allele with a protective role from SLE (recessive genetic model, p = .016, OR = 0.08 IC [0.01-0.63] and p = 7.6904E - 05, OR = 0.43 IC = [0.28-0.66], respectively). Moreover, statistical analysis indicated that the rs11889031 > CC genotype was linked with clinical and serological manifestations of SLE, including blood pressure, and anti-SSA antibodies production in SLE patients. However, the ICOS gene rs10932029 polymorphism was not associated with susceptibility to SLE. On the other side, we did not note any effect of the two selected polymorphisms on the level of ICOS mRNA gene expression. The study showed a significant predisposing association of the ICOS rs11889031 > CC genotype with SLE, in contrast to a protective effect of rs11889031 > TT genotype in Tunisian patients. Our results suggest that ICOS rs11889031 may act as a risk factor for SLE and could be used as a genetic susceptibility biomarker.

Decoding the crosstalk between mevalonate metabolism and T cell function

The mevalonate pathway is an essential metabolic pathway in T cells regulating development, proliferation, survival, differentiation, and effector functions. The mevalonate pathway is a complex, branched pathway composed of many enzymes that ultimately generate cholesterol and nonsterol isoprenoids. T cells must tightly control metabolic flux through the branches of the mevalonate pathway to ensure sufficient isoprenoids and cholesterol are available to meet cellular demands. Unbalanced metabolite flux through the sterol or the nonsterol isoprenoid branch is metabolically inefficient and can have deleterious consequences for T cell fate and function. Accordingly, there is tight regulatory control over metabolic flux through the branches of this essential lipid synthetic pathway. In this review we provide an overview of how the branches of the mevalonate pathway are regulated in T cells and discuss our current understanding of the relationship between mevalonate metabolism, cholesterol homeostasis and T cell function.

Poor immunogenicity upon SARS-CoV-2 mRNA vaccinations in autoimmune SLE patients is associated with pronounced EF-mediated responses and anti-BAFF/Belimumab treatment

Novel mRNA vaccines have resulted in a reduced number of SARS-CoV-2 infections and hospitalizations. Yet, there is a paucity of studies regarding their effectiveness on immunocompromised autoimmune subjects. In this study, we enrolled subjects naïve to SARS-CoV-2 infections from two cohorts of healthy donors (HD, n=56) and systemic lupus erythematosus (SLE, n=69). Serological assessments of their circulating antibodies revealed a significant reduction of potency and breadth of neutralization in the SLE group, only partially rescued by a 3rd booster dose. Immunological memory responses in the SLE cohort were characterized by a reduced magnitude of spike-reactive B and T cell responses that were strongly associated with poor seroconversion. Vaccinated SLE subjects were defined by a distinct expansion and persistence of a DN2 spike-reactive memory B cell pool and a contraction of spike-specific memory cTfh cells, contrasting with the sustained germinal center (GC)-driven activity mediated by mRNA vaccination in the healthy population. Among the SLE-associated factors that dampened the vaccine responses, treatment with the monoclonal antibody anti-BAFF/Belimumab (a lupus FDA-approved B cell targeting agent) profoundly affected the vaccine responsiveness by restricting the de novo B cell responses and promoting stronger extra-follicular (EF)-mediated responses that were associated with poor immunogenicity and impaired immunological memory. In summary, this study interrogates antigen-specific responses and characterized the immune cell landscape associated with mRNA vaccination in SLE. The identification of factors associated with reduced vaccine efficacy illustrates the impact of SLE B cell biology on mRNA vaccine responses and provides guidance for the management of boosters and recall vaccinations in SLE patients according to their disease endotype and modality of treatment.

Co-expression of Foxp3 and Helios facilitates the identification of human T regulatory cells in health and disease

Foxp3 is regarded as the major transcription factor for T regulatory (Treg) cells and expression of Foxp3 is used to identify and quantitate Treg cells in mouse models. However, several studies have demonstrated that human CD4+ T conventional (Tconv) cells activated in vitro by T cell receptor (TCR) stimulation can express Foxp3. This observation has raised doubt as to the suitability of Foxp3 as a Treg marker in man. Helios, a member of the Ikaros gene family, has been shown to be expressed by 80-90% of human Foxp3+ Treg cells and can potentially serve as a marker of human Treg. Here, we confirm that Foxp3 expression is readily upregulated by Tconv upon TCR stimulation in vitro, while Helios expression is not altered. More importantly, we show that Foxp3 expression is not elevated by stimulation of hTconv in a humanized mouse model of graft versus host disease (GVHD) and in patients with a wide variety of acute and chronic inflammatory diseases including sickle cell disease, acute and chronic GVHD, systemic lupus erythematosus, as well as critical COVID-19. In all patients studied, an excellent correlation was observed between the percentage of CD4+ T cells expressing Foxp3 and the percentage expressing Helios. Taken together, these studies demonstrate that Foxp3 is not induced upon Tconv cell activation in vivo and that Foxp3 expression alone can be used to quantitate Treg cells in humans. Nevertheless, the combined use of Foxp3 and Helios expression provides a more reliable approach for the characterization of Treg in humans.

Role of T cells in the pathogenesis of systemic lupus erythematous: Focus on immunometabolism dysfunctions

Evidence demonstrates that T cells are implicated in developing SLE, and each of them dominantly uses distinct metabolic pathways. Indeed, intracellular enzymes and availability of specific nutrients orchestrate fate of T cells and lead to differentiation of regulatory T cells (Treg), memory T cells, helper T cells, and effector T cells. The function of T cells in inflammatory and autoimmune responses is determined by metabolic processes and activity of their enzymes. Several studies were conducted to determine metabolic abnormalities in SLE patients and clarify how these modifications could control the functions of the involved T cells. Metabolic pathways such as glycolysis, mitochondrial pathways, oxidative stress, mTOR pathway, fatty acid and amino acid metabolisms are dysregulated in SLE T cells. Moreover, immunosuppressive drugs used in treating autoimmune diseases, including SLE, could affect immunometabolism. Developing drugs to regulate autoreactive T cell metabolism could be a promising therapeutic approach for SLE treatment. Accordingly, increased knowledge about metabolic processes paves the way to understanding SLE pathogenesis better and introduces novel therapeutic options for SLE treatment. Although monotherapy with metabolic pathways modulators might not be sufficient to prevent autoimmune disease, they may be an ideal adjuvant to reduce administration doses of immunosuppressive drugs, thus reducing drug-associated adverse effects. This review summarized emerging data about T cells that are involved in SLE pathogenesis, focusing on immunometabolism dysregulation and how these modifications could affect the disease development.

m6A methyltransferase METTL3 programs CD4+ T-cell activation and effector T-cell differentiation in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disorder in which excessive CD4⁺ T-cell activation and imbalanced effector T-cell differentiation play critical roles. Recent studies have implied a potential association between posttranscriptional N6-methyladenosine (m⁶A) modification and CD4⁺ T-cell-mediated humoral immunity. However, how this biological process contributes to lupus is not well understood. In this work, we investigated the role of the m⁶A methyltransferase like 3 (METTL3) in CD4⁺ T-cell activation, differentiation, and SLE pathogenesis both in vitro and in vivo.

METHODS

The expression of METTL3 was knocked down and METTL3 enzyme activity was inhibited using siRNA and catalytic inhibitor, respectively. In vivo evaluation of METTL3 inhibition on CD4⁺ T-cell activation, effector T-cell differentiation, and SLE pathogenesis was achieved using a sheep red blood cell (SRBC)-immunized mouse model and a chronic graft versus host disease (cGVHD) mouse model. RNA-seq was performed to identify pathways and gene signatures targeted by METTL3. m⁶A RNA-immunoprecipitation qPCR was applied to confirm the m⁶A modification of METTL3 targets.

RESULTS

METTL3 was defective in the CD4⁺ T cells of SLE patients. METTL3 expression varied following CD4⁺ T-cell activation and effector T-cell differentiation in vitro. Pharmacological inhibition of METTL3 promoted the activation of CD4⁺ T cells and influenced the differentiation of effector T cells, predominantly Treg cells, in vivo. Moreover, METTL3 inhibition increased antibody production and aggravated the lupus-like phenotype in cGVHD mice. Further investigation revealed that catalytic inhibition of METTL3 reduced Foxp3 expression by enhancing Foxp3 mRNA decay in a m⁶A-dependent manner, hence suppressing Treg cell differentiation.

CONCLUSION

In summary, our findings demonstrated that METTL3 was required for stabilizing Foxp3 mRNA via m⁶A modification to maintain the Treg differentiation program. METTL3 inhibition contributed to the pathogenesis of SLE by participating in the activation of CD4⁺ T cells and imbalance of effector T-cell differentiation, which could serve as a potential target for therapeutic intervention in SLE.

AHR/TET2/NT5E axis downregulation is associated with the risk of systemic lupus erythematosus and its progression

The prognosis of systemic lupus erythematosus (SLE) is unpredictable. This study aimed to examine the regulatory mechanism of the AHR/TET2/NT5E pathway during SLE progression. The AHR, TET2 and NT5E expression levels were examined in T regulatory cells (Tregs) of patients with SLE. The correlation of AHR, TET2 or NT5E expression levels with the immunosuppressive functions of Tregs was analysed. In patients with SLE, the number of CD4⁺ IL2RA^- FOXP3⁺ T cell subset was positively correlated with the SLE disease activity index value and negatively correlated with the AHR and TET2 expression levels in CD4⁺ IL2RA⁺ FOXP3⁺ Tregs. Transcriptional profiles of 79 patients with SLE obtained from the Gene Expression Omnibus database (GSE61635 dataset) revealed a significant positive correlation between the mRNA expression levels of AHR and TET2. In silico analysis predicted that the TET2 promoter comprises an AHR-binding site. Kynurenine (KYN) promoted the binding of AHR to the TET2 promoter in Tregs of patients with SLE and Jurkat T cell lines. Furthermore, NT5E expression was significantly downregulated in Tregs of patients with SLE, which can be attributed to the dysregulation of NT5E promoter methylation status induced by downregulated TET2 activity. Furthermore, the Treg immunosuppressive activity, which is mediated through the TET2 and A2AR-adenosine pathways, in the KYN-treated group was approximately two-fold higher than that in the control group. The AHR/TET2/NT5E axis mediates the Treg immunosuppressive activity. These findings provide novel insights for the development of therapeutic approaches for SLE and related autoimmune diseases.

Analysis of microRNA-199a-3p expression in CD4+ T cells of systemic lupus erythematosus

OBJECTIVES

Accumulating evidence have suggested microRNAs (miRNAs) play important roles in the pathogenesis of systemic lupus erythematosus (SLE). Here we aimed to explore aberrant expression of miRNAs in CD4⁺ T cells from SLE patients and their potential function in SLE pathogenesis.

METHODS

First, next-generation sequencing was performed on CD4⁺ T cells from four SLE patients and three healthy controls (HCs). Candidate miRNAs were then validated in CD4⁺ T cells from 97 patients with SLE, 16 patients with rheumatoid arthritis, and 12 HCs using qRT-PCR. Then the relationship between the candidate miRNA and clinical characteristics was analyzed. Bioinformatics analysis and validation of the target genes of the candidate miRNA were performed.

RESULTS

A total of 66 upregulated miRNAs and 70 downregulated miRNAs were found between SLE and normal CD4⁺ T cells samples. miR-199a-3p was identified significant upregulation in the CD4⁺ T cells of lupus patients. High expression of miR-199a-3p was correlated with several clinical characteristics including low C3 level, positive anti-dsDNA antibody, high ESR level, active lupus nephritis, and active disease activity. When distinguishing active LN from non-LN or active lupus from stable lupus, the AUCs of miR-199a-3p were 0.68 and 0.70, respectively. And the expression of miR-199a-3p, involved in JAK-STAT signaling pathway, was negatively correlated with the STAM expression in CD4⁺ T cells of SLE.

CONCLUSION

Our study suggested a novel and promising role of miR-199a-3p in CD4⁺ T cells for SLE. Further studies are needed to precisely determine the function of miR-199a-3p in this disease. Key Points • Aberrant expression of miRNAs in CD4⁺ T cells and their potential function in SLE pathogenesis remained unclear. • miR-199a-3p in CD4+ T cells plays a novel role in the pathogenesis of SLE and serves as a potential target for SLE.

Elevated transferrin receptor impairs T cell metabolism and function in systemic lupus erythematosus

T cells in systemic lupus erythematosus (SLE) exhibit multiple metabolic abnormalities. Excess iron can impair mitochondria and may contribute to SLE. To gain insights into this potential role of iron in SLE, we performed a CRISPR screen of iron handling genes on T cells. Transferrin receptor (CD71) was identified as differentially critical for TH1 and inhibitory for induced regulatory T cells (iTregs). Activated T cells induced CD71 and iron uptake, which was exaggerated in SLE-prone T cells. Cell surface CD71 was enhanced in SLE-prone T cells by increased endosomal recycling. Blocking CD71 reduced intracellular iron and mTORC1 signaling, which inhibited TH1 and TH17 cells yet enhanced iTregs. In vivo treatment reduced kidney pathology and increased CD4 T cell production of IL-10 in SLE-prone mice. Disease severity correlated with CD71 expression on TH17 cells from patients with SLE, and blocking CD71 in vitro enhanced IL-10 secretion. T cell iron uptake via CD71 thus contributes to T cell dysfunction and can be targeted to limit SLE-associated pathology.

Reprogramming of IL-12 secretion in the PDCD1 locus improves the anti-tumor activity of NY-ESO-1 TCR-T cells

Introduction

Although the engineering of T cells to co-express immunostimulatory cytokines has been shown to enhance the therapeutic efficacy of adoptive T cell therapy, the uncontrolled systemic release of potent cytokines can lead to severe adverse effects. To address this, we site-specifically inserted the interleukin-12 (IL-12) gene into the PDCD1 locus in T cells using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-based genome editing to achieve T-cell activation-dependent expression of IL-12 while ablating the expression of inhibitory PD-1.

Methods

New York esophageal squamous cell carcinoma 1(NY-ESO-1)-specific TCR-T cells was investigated as a model system. We generated ΔPD-1-IL-12 -edited NY-ESO-1 TCR-T cells by sequential lentiviral transduction and CRISPR knock-in into activated human primary T cells.

Results

We showed that the endogenous PDCD1 regulatory elements can tightly control the secretion of recombinant IL-12 in a target cell-dependent manner, at an expression level that is more moderate than that obtained using a synthetic NFAT-responsive promoter. The inducible expression of IL-12 from the PDCD1 locus was sufficient to enhance the effector function of NY-ESO-1 TCR-T cells, as determined by upregulation of effector molecules, increased cytotoxic activity, and enhanced expansion upon repeated antigen stimulation in vitro. Mouse xenograft studies also revealed that PD-1-edited IL-12-secreting NY-ESO-1 TCR-T cells could eliminate established tumors and showed significantly greater in vivo expansion capacity than control TCR-T cells.

Discussion

Our approach may provide a way to safely harness the therapeutic potential of potent immunostimulatory cytokines for the development of effective adoptive T cell therapies against solid tumors.

Hypovitaminosis A Drives the Progression of Tubulointerstitial Lupus Nephritis through Potentiating Predisease Cellular Autoreactivity

Vitamin A (VA) deficiency (VAD) is observed in both humans and mice with lupus nephritis. However, whether VAD is a driving factor for accelerated progression of lupus nephritis is unclear. In this study, we investigated the effect of VAD on the progression of lupus nephritis in a lupus-prone mouse model, MRL/lpr. We initiated VAD either during gestation or after weaning to reveal a potential time-dependent effect. We found exacerbated lupus nephritis at ∼15 wk of age with both types of VAD that provoked tubulointerstitial nephritis leading to renal failure. This was concomitant with significantly higher mortality in all VAD mice. Importantly, restoration of VA levels after weaning reversed VAD-induced mortality. These results suggest VAD-driven acceleration of tubulointerstitial lupus nephritis. Mechanistically, at the earlier time point of 7 wk of age and before the onset of clinical lupus nephritis, continued VAD (from gestation until postweaning) enhanced plasma cell activation and augmented their autoantibody production, while also increasing the expansion of T lymphocytes that could promote plasma cell autoreactivity. Moreover, continued VAD increased the renal infiltration of plasmacytoid dendritic cells. VAD initiated after weaning, in contrast, showed modest effects on autoantibodies and renal plasmacytoid dendritic cells that were not statistically significant. Remarkably, analysis of gene expression in human kidney revealed that the retinoic acid pathway was decreased in the tubulointerstitial region of lupus nephritis, supporting our findings in MRL/lpr mice. Future studies will elucidate the underlying mechanisms of how VAD modulates cellular functions to exacerbate tubulointerstitial lupus nephritis.

The mapping of mRNA alterations elucidates the etiology of radiation-induced pulmonary fibrosis

The etiology of radiation-induced pulmonary fibrosis is not clearly understood yet, and effective interventions are still lacking. This study aimed to identify genes responsive to irradiation and compare the genome expression between the normal lung tissues and irradiated ones, using a radiation-induced pulmonary fibrosis mouse model. We also aimed to map the mRNA alterations as a predictive model and a potential mode of intervention for radiation-induced pulmonary fibrosis. Thirty C57BL/6 mice were exposed to a single dose of 16 Gy or 20 Gy thoracic irradiation, to establish a mouse model of radiation-induced pulmonary fibrosis. Lung tissues were harvested at 3 and 6 months after irradiation, for histological identification. Global gene expression in lung tissues was assessed by RNA sequencing. Differentially expressed genes were identified and subjected to functional and pathway enrichment analysis. Immune cell infiltration was evaluated using the CIBERSORT software. Three months after irradiation, 317 mRNAs were upregulated and 254 mRNAs were downregulated significantly in the low-dose irradiation (16 Gy) group. In total, 203 mRNAs were upregulated and 149 were downregulated significantly in the high-dose irradiation (20 Gy) group. Six months after radiation, 651 mRNAs were upregulated and 131 were downregulated significantly in the low-dose irradiation group. A total of 106 mRNAs were upregulated and 4 downregulated significantly in the high-dose irradiation group. Several functions and pathways, including angiogenesis, epithelial cell proliferation, extracellular matrix, complement and coagulation cascades, cellular senescence, myeloid leukocyte activation, regulation of lymphocyte activation, mononuclear cell proliferation, immunoglobulin binding, and the TNF, NOD-like receptor, and HIF-1 signaling pathways were significantly enriched in the irradiation groups, based on the differentially expressed genes. Irradiation-responsive genes were identified. The differentially expressed genes were mainly associated with cellular metabolism, epithelial cell proliferation, cell injury, and immune cell activation and regulation.

Regulation of autoimmune disease progression by Pik3ip1 through metabolic reprogramming in T cells and therapeutic implications

Metabolic alterations could profoundly affect immune functions and influence the progression and outcome of autoimmune diseases. However, the detailed mechanisms and their therapeutic potential remain to be defined. Here, we show that phosphatidylinositide 3-kinase interacting protein 1 (Pik3ip1), a newly identified negative immune regulator, is notably down-regulated in several major autoimmune diseases through a previously unidentified mechanism mediated by interleukin-21/p38 mitogen-activated protein kinase/a disintegrin and metalloprotease-17 (ADAM17) pathway. Down-regulation of Pik3ip1 in T cells causes a major metabolic shift from oxidative phosphorylation toward aerobic glycolysis, leading to their overactivation and aggressive disease progression in experimental autoimmune encephalomyelitis (EAE) mouse model. Suppression of hypoxia-inducible factor 1α (Hif1α) or pharmacologic inhibition of glycolysis could reverse these phenotypes and largely mitigate EAE severity. Our study reveals a previously unrecognized role of Pik3ip1 in metabolic regulation that substantially affects the inflammatory loop in the autoimmune setting and identifies the Pik3ip1/Hif1α/glycolysis axis as a potential therapeutic target for treatment of autoimmune diseases.

Lupus nephritis: The regulatory interplay between epigenetic and MicroRNAs

MicroRNAs (miRNAs) are endogenous, small, non-coding RNA molecules that act as epigenetic modifiers to regulate the protein levels of target messenger RNAs without altering their genetic sequences. The highly complex role of miRNAs in the epigenetics of lupus nephritis (LN) is increasingly being recognized. DNA methylation and histone modifications are focal points of epigenetic research. miRNAs play a critical role in renal development and physiology, and dysregulation may result in abnormal renal cell proliferation, inflammation, and fibrosis of the kidneys in LN. However, epigenetic and miRNA-mediated regulation are not mutually exclusive. Further research has established a link between miRNA expression and epigenetic regulation in various disorders, including LN. This review summarizes the most recent evidence regarding the interaction between miRNAs and epigenetics in LN and highlights potential therapeutic and diagnostic targets.

Investigation of the association between the genetic polymorphisms of the co-stimulatory system and systemic lupus erythematosus

Human leukocyte antigen genes have been shown to have the strongest association with autoimmune disease (AD). However, non-HLA genes would be risk factors of AD. Many genes encoding proteins that are related to T- and B-cell function have been identified as susceptibility genes of systemic lupus erythematosus (SLE). In this study, we explored the correlation between SLE and the genetic polymorphisms of co-stimulatory/co-inhibitory molecules, including CTLA4, CD28, ICOS, PDCD1, and TNFSF4. We found that there were nine single-nucleotide polymorphisms (SNPs) associated with SLE, namely, rs11571315 (TT vs. CT vs. CC: p < 0.001; TT vs. CT: p = 0.001; p = 0.005; TT vs. CT +CC: p < 0.001; TT+CT vs. CC: p = 0.032), rs733618 (CC vs. CT vs. TT: p = 0.002; CC vs. CT: p = 0.001; CC vs. TT: p = 0.018; CC vs. CT + TT: p = 0.001), rs4553808 (AA vs. AG: p < 0.001), rs62182595 (GG vs. AG vs. AA: p < 0.001; GG vs. AG: p < 0.001; GG vs. AG+AA: p < 0.001), rs16840252 (CC vs. CT vs. TT: p < 0.001; CC vs. CT: p < 0.001; CC vs. CT + TT: p < 0.001), rs5742909 (CC vs. CT: p = 0.027; CC vs. CT + TT: p = 0.044), rs11571319 (GG vs. AG vs. AA: p < 0.001, GG vs. AG: p < 0.001; GG vs. AG+AA: p < 0.001), rs36084323 (CC vs. CT vs. TT: p = 0.013, CC vs. TT: p = 0.004; CC vs. CT + TT: p = 0.015; CC +CT vs. TT: p = 0.015), and rs1234314 (CC vs. CG vs. GG: p = 0.005; GG vs. CC: p = 0.004; GG+ CG vs. CC: p = 0.001), but not in CD28 and ICOS by using the chi-square test. Additionally, rs62182595 and rs16840252 of CTLA and rs1234314 and rs45454293 of TNFSF4 were also associated with SLE in haplotypes. These SLE-related SNPs also had an association with several diseases. It was indicated that these SNPs may play an important role in immune regulation and pathogenic mechanisms.

Sis-25, a meroditerpenoid derivative with a cyclobutane scaffold, inhibits activated T cell proliferation by targeting GSK3β in vitro and in vivo

A series of novel scopariusicide derivatives were designed and synthesized starting from the main diterpenoid from the aerial parts of Isodon scoparius. Sis-25 was the most effective compound among them. The potential mechanism(s) of its immunosuppressive activity in vitro, as well as its effects on delayed type hypersensitivity (DTH) reaction and imiquimod-induced dermatitis in vivo were investigated in this study. Sis-25 inhibited anti-CD3/anti-CD28 mAbs, PHA or alloantigen-induced T cell proliferation without obvious cytotoxicity. Sis-25 was a highly selective inhibitor of GSK3-β and inhibited the mTOR/p70S6K pathway but not the PI3K/Akt, p38 MAPK/ERK 1/2 and JAK3/STAT5 pathways. Furthermore, Sis-25 significantly inhibited IFN-γ, IL-6 and IL-17 expression but not IL-10 expression in activated T cells. Finally, Sis-25 treatment mitigated the DNFB-induced DTH reaction and ameliorated imiquimod-induced dermatitis. In summary, Sis-25 exerted significant immunosuppressive activity by targeting GSK3β in vitro and in vivo. Sis-25 may guide the design of new drugs for more effective and safer treatments of autoimmune diseases and provide new insight into developing utilizations of Isodon scoparius.

Correlation between peripheral blood lymphocyte subpopulations and primary systemic lupus erythematosus

This study explored the correlation between peripheral blood CD3＋, CD3＋/CD4＋, CD3+/CD8+, CD4＋/CD8＋, CD3-/CD16+ CD56+, and CD3-CD19+ and disease activity of different subtypes of systemic lupus erythematosus (SLE). The percentages of CD3+, CD3+/CD4+, CD3+/CD8+, CD4+/CD8+, CD3-/CD16+ CD56+, and CD3-CD19+ in the peripheral blood of patients (n = 80) classified into lupus nephritis, blood involvement, and joint involvement and SLE in different active stages were detected by flow cytometry. Their correlations with baseline clinical experimental indicators of SLE patients' SLE disease activity index score (SLEDAI) and complement C3 were analyzed. The results showed that CD3+, CD3+/CD4+, and CD3+/CD8+ at baseline level were negatively correlated with SLEDAI scores. These were positively correlated with C3. In conclusion, T-lymphocyte subpopulations are closely related to SLE activity and can be used as reference indicators to evaluate the SLE activity.

Apoptotic vesicles ameliorate lupus and arthritis via phosphatidylserine-mediated modulation of T cell receptor signaling

Mesenchymal stem cells (MSCs) influence T cells in health, disease and therapy through messengers of intercellular communication including extracellular vesicles (EVs). Apoptosis is a mode of cell death that tends to promote immune tolerance, and a large number of apoptotic vesicles (apoVs) are generated from MSCs during apoptosis. In an effort to characterize these apoVs and explore their immunomodulatory potential, here we show that after replenishing them systemically, the apoV deficiency in Fas mutant mice and pathological lymphoproliferation were rescued, leading to the amelioration of inflammation and lupus activity. ApoVs directly interacted with CD4⁺ T cells and inhibited CD25 expression and IL-2 production in a dose-dependent manner. A broad range of Th1/2/17 subsets and cytokines including IFNγ, IL17A and IL-10 were suppressed while Foxp3⁺ cells were maintained. Mechanistically, exposed phosphatidylserine (PtdSer/PS) on apoVs mediated the interaction with T cells to disrupt proximal T cell receptor signaling transduction. Remarkably, administration of apoVs prevented Th17 differentiation and memory formation, and ameliorated inflammation and joint erosion in murine arthritis. Collectively, our findings unveil a previously unrecognized crosstalk between MSC apoVs and CD4⁺ T cells and suggest a promising therapeutic use of apoVs for autoimmune diseases.

Abnormalities of T cells in systemic lupus erythematosus: new insights in pathogenesis and therapeutic strategies

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by loss of immune tolerance and sustained production of autoantibodies. Multiple and profound T cell abnormalities in SLE are intertwined with disease expression. Both numerical and functional disturbances have been reported in main CD4⁺ T helper cell subsets including Th1, Th2, Th17, regulatory, and follicular helper cells. SLE CD4⁺ T cells are known to provide help to B cells, produce excessive IL-17 but insufficient IL-2, and infiltrate tissues. In the absence of sufficient amounts of IL-2, regulatory T cells, do not function properly to constrain inflammation. A complicated series of early signaling defects and aberrant activation of kinases and phosphatases result in complex cell phenotypes by altering the metabolic profile and the epigenetic landscape. All main metabolic pathways including glycolysis, glutaminolysis and oxidative phosphorylation are altered in T cells from lupus prone mice and patients with SLE. SLE CD8⁺ cytotoxic T cells display reduced cytolytic activity which accounts for higher rates of infection and the sustenance of autoimmunity. Further, CD8⁺ T cells in the context of rheumatic diseases lose the expression of CD8, acquire IL-17⁺CD4^-CD8^- double negative T (DNT) cell phenotype and infiltrate tissues. Herein we present an update on these T cell abnormalities along with underlying mechanisms and discuss how these advances can be exploited therapeutically. Novel strategies to correct these aberrations in T cells show promise for SLE treatment.

Phenotypical changes and clinical significance of CD4+/CD8+ T cells in SLE

OBJECTIVE

T cells display significant phenotypical changes and play multiple roles in promoting the immune response in SLE. The frequencies of T cell subpopulations in SLE are still not well understood. To better understanding the phenotypic abnormalities of T cells in SLE will help us to clarify disease immunopathology and to find promising biomarkers for disease monitoring and control.

METHODS

Peripheral blood CD4⁺ and CD8⁺ T cells and their subsets were determined by flow cytometry. Forty-one active SLE patients were selected, including 28 new-onset patients and 13 relapsing patients. One hundred healthy controls (HCs) were enrolled as the control group. The percentages of these cell subsets between patients with SLE and HCs and their relationships with disease activity and autoantibody titers were analysed. Thirteen of 28 new-onset SLE patients were assessed before and after treatment. The changes in the frequencies of these cell subsets and their relationships with renal response were analysed.

RESULTS

There was a broad range of anomalies in the proportion of T cell subsets in patients with SLE compared with that of the HCs. Compared with the HCs, a higher frequency of memory T cells and a lower frequency of naïve T cells were noted in patients with SLE. In addition, an imbalance of CD28⁺ and CD28^- cells in CD4⁺ T cells was observed in patients with SLE. We found that the expanded CD4⁺CD28^- T cells did not decrease after treatment in patients who had impaired renal responses. It was very interesting to exhibit a negative correlation in the frequency between the CD4⁺CD28^- T cells and T regulatory (Treg) cells and a positive correlation between the frequency of CD4⁺CD28⁺ T cells and Treg cells in this study. Increased CD8⁺HLADR⁺ T cell and CD8⁺CD38⁺HLADR⁺ T cell counts were observed in patients with SLE, suggesting an impaired cytotoxic capacity of CD8⁺ T cells in SLE. Additionally, we found that CD8⁺CD38⁺HLADR⁺ T cells were closely associated with disease activity, autoantibody titres and renal prognosis. CD4⁺ CXCR5^-PD1⁺ T cells were expanded in patients with SLE in this study and were associated with disease activity in SLE. Th1 (T helper type 1) cells and Treg cells were decreased, but frequencies of T follicular helper (Tfh) cells, Th2 cells, Th17 cells and Tfh17 cells were increased. A strong correlation between Th17 cells and Tregs with renal involvement was observed in this study.

CONCLUSION

The proportions of CD4⁺CD28^- T cells, CD4⁺CXCR5^-PD1⁺ T cells, CD8⁺HLADR⁺ T cells and CD8⁺CD38⁺HLADR⁺ T cells increased in patients with SLE and could be associated with disease activity and renal prognosis.

The deacetylase SIRT2 contributes to autoimmune disease pathogenesis by modulating IL-17A and IL-2 transcription

Aberrant IL-17A expression together with reduced IL-2 production by effector CD4⁺ T cells contributes to the pathogenesis of systemic lupus erythematosus (SLE). Here, we report that Sirtuin 2 (SIRT2), a member of the family of NAD⁺-dependent histone deacetylases, suppresses IL-2 production by CD4⁺ T cells while promoting their differentiation into Th17 cells. Mechanistically, we show that SIRT2 is responsible for the deacetylation of p70S6K, activation of the mTORC1/HIF-1α/RORγt pathway and induction of Th17-cell differentiation. Additionally, SIRT2 was shown to be responsible for the deacetylation of c-Jun and histones at the Il-2 gene, resulting in decreased IL-2 production. We found that the transcription factor inducible cAMP early repressor (ICER), which is overexpressed in T cells from people with SLE and lupus-prone mice, bound directly to the Sirt2 promoter and promoted its transcription. AK-7, a SIRT2 inhibitor, limited the ability of adoptively transferred antigen-specific CD4⁺ T cells to cause autoimmune encephalomyelitis in mice and limited disease in lupus-prone MRL/lpr mice. Finally, CD4⁺ T cells from SLE patients exhibited increased expression of SIRT2, and pharmacological inhibition of SIRT2 in primary CD4⁺ T cells from patients with SLE attenuated the ability of these cells to differentiate into Th17 cells and promoted the generation of IL-2-producing T cells. Collectively, these results suggest that SIRT2-mediated deacetylation is essential in the aberrant expression of IL-17A and IL-2 and that SIRT2 may be a promising molecular target for new SLE therapies.

Lupus Susceptibility Loci Predispose Mice to Clonal Lymphocytic Responses and Myeloid Expansion

Lupus susceptibility results from the combined effects of numerous genetic loci, but the contribution of these loci to disease pathogenesis has been difficult to study due to the large cellular heterogeneity of the autoimmune immune response. We performed single-cell RNA, BCR, and TCR sequencing of splenocytes from mice with multiple polymorphic lupus susceptibility loci. We not only observed lymphocyte and myeloid expansion, but we also characterized changes in subset frequencies and gene expression, such as decreased CD8 and marginal zone B cells and increased Fcrl5- and Cd5l-expressing macrophages. Clonotypic analyses revealed expansion of B and CD4 clones, and TCR repertoires from lupus-prone mice were distinguishable by algorithmic specificity prediction and unsupervised machine learning classification. Myeloid differential gene expression, metabolism, and altered ligand-receptor interaction were associated with decreased Ag presentation. This dataset provides novel mechanistic insight into the pathophysiology of a spontaneous model of lupus, highlighting potential therapeutic targets for autoantibody-mediated disease.

Cholesterol inhibits TCR signaling by directly restricting TCR-CD3 core tunnel motility

Cholesterol molecules specifically bind to the resting αβTCR to inhibit cytoplasmic CD3ζ ITAM phosphorylation through sequestering the TCR-CD3 complex in an inactive conformation. The mechanisms of cholesterol-mediated inhibition of TCR-CD3 and its activation remain unclear. Here, we present cryoelectron microscopy structures of cholesterol- and cholesterol sulfate (CS)-inhibited TCR-CD3 complexes and an auto-active TCR-CD3 variant. The structures reveal that cholesterol molecules act like a latch to lock CD3ζ into an inactive conformation in the membrane. Mutations impairing binding of cholesterol molecules to the tunnel result in the movement of the proximal C terminus of the CD3ζ transmembrane helix, thereby activating the TCR-CD3 complex in human cells. Together, our data reveal the structural basis of TCR inhibition by cholesterol, illustrate how the cholesterol-binding tunnel is allosterically coupled to TCR triggering, and lay a foundation for the development of immunotherapies through directly targeting the TCR-CD3 complex.

The tangled web of autoreactive B cells in malaria immunity and autoimmune disease

Two seminal observations suggest that the African genome contains genes selected by malaria that protect against systemic lupus erythematosus (SLE) in individuals chronically exposed to malaria, but which in the absence of malaria, are risk factors for SLE. First, Brian Greenwood observed that SLE was rare in Africa and that malaria prevented SLE-like disease in susceptible mice. Second, African-Americans, as compared with individuals of European descent, are at higher risk of SLE. Understanding that antibodies play central roles in malaria immunity and SLE, we discuss how autoreactive B cells contribute to malaria immunity but promote SLE pathology in the absence of malaria. Testing this model may provide insights into the regulation of autoreactivity and identify new therapeutic targets for SLE.

Splicing factor SRSF1 controls distinct molecular programs in regulatory and effector T cells implicated in systemic autoimmune disease

Systemic autoimmune diseases are characterized by hyperactive effector T cells (Teffs), aberrant cytokines and chemokines, and dysfunctional regulatory T cells (Tregs). We previously uncovered new roles for serine/arginine-rich splicing factor 1 (SRSF1) in the control of genes involved in T cell signaling and cytokine production in human T cells. SRSF1 levels are decreased in T cells from patients with systemic lupus erythematosus (SLE), and low levels correlate with severe disease. Moreover, T cell-conditional Srsf1-deficient mice recapitulate the autoimmune phenotype, exhibiting CD4 T cell hyperactivity, dysfunctional Tregs, systemic autoimmunity, and tissue inflammation. However, the role of SRSF1 in controlling molecular programs in Teffs and Tregs and how these pathways are implicated in autoimmunity is not known. Here, by comparative bioinformatics analysis, we demonstrate that SRSF1 controls largely distinct gene programs in Tregs and Teffs in vivo. SRSF1 regulates 189 differentially expressed genes (DEGs) unique to Tregs, 582 DEGs unique to Teffs, and 29 DEGs shared between both. Shared genes included IL-17A, IL-17F, CSF1, CXCL10, and CXCR4, and were highly enriched for inflammatory response and cytokine-cytokine receptor interaction pathways. SRSF1 controls distinct pathways in Tregs, which include chemokine signaling and immune cell differentiation, compared with pathways in Teffs, which include cytokine production, T cell homeostasis, and activation. We identified putative mRNA binding targets of SRSF1 which include CSF1, CXCL10, and IL-17F. Finally, comparisons with transcriptomics profiles from lupus-prone MRL/lpr mice reveal that SRSF1 controls genes and pathways implicated in autoimmune disease. The target genes of SRSF1 and putative binding targets we discovered, have known roles in systemic autoimmunity. Our findings suggest that SRSF1 controls distinct molecular pathways in Tregs and Teffs and aberrant SRSF1 levels may contribute to their dysfunction and immunopathogenesis of systemic autoimmune disease.

The role of IL-17 and anti-IL-17 agents in the immunopathogenesis and management of autoimmune and inflammatory diseases

Interleukin-17 (IL-17) is a proinflammatory cytokine involved in chronic inflammation occurring during the pathogenesis of allergy, malignancy, and autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and psoriasis. IL-17 is produced by multiple cell types of adaptive and innate immunity, including T helper 17 cells, CD8 + T cells, γδ T cells, natural killer T cells, and innate lymphoid cells. Monoclonal antibodies (mAbs) targeting IL-17 and/or IL-17R would be a potential approach to study this therapeutic tool for these diseases. In the current review, we aimed to highlight the characteristics of IL-17 and its important role in the pathogenesis of related diseases. Critical evaluation of the mAbs targeting IL-17A and IL-17 receptors (e.g., Ixekizumab, Secukinumab, and Brodalumab) in various immune-mediated diseases will be provided, and finally, their clinical efficacy and safety will be reported.

Contribution of Dysregulated DNA Methylation to Autoimmunity

Epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs are known regulators of gene expression and genomic stability in cell growth, development, and differentiation. Because epigenetic mechanisms can regulate several immune system elements, epigenetic alterations have been found in several autoimmune diseases. The purpose of this review is to discuss the epigenetic modifications, mainly DNA methylation, involved in autoimmune diseases in which T cells play a significant role. For example, Rheumatoid Arthritis and Systemic Lupus Erythematosus display differential gene methylation, mostly hypomethylated 5′-C-phosphate-G-3′ (CpG) sites that may associate with disease activity. However, a clear association between DNA methylation, gene expression, and disease pathogenesis must be demonstrated. A better understanding of the impact of epigenetic modifications on the onset of autoimmunity will contribute to the design of novel therapeutic approaches for these diseases.