Systemic lupus erythematosus favors the generation of IL-17 producing double negative T cells

An increase in IL-10-producing DNT cells is associated with the pathogenesis of pediatric SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that causes immune system overactivity and organ damage. Among T-cell subsets involved in SLE, CD4 and CD8 double-negative αβT (DNT) cells have attracted attention in recent years, although their role in SLE remains poorly understood. Examining the minute intricacies, particularly signaling pathway modifications is crucial, as it may unveil potential therapeutic targets and lead to the development of more effective treatments. Our study found increased DNT cells in pediatric SLE patients, with elevated IL-10 signaling. These IL-10-producing DNT cells were positively related to disease activity defined by SLE Disease Activity Index (SLEDAI), and were further elevated in patients with lupus nephritis. Additionally, our results indicated that IL-10-producing DNT cells correlated positively with anti-Sm autoantibodies. Collectively, our study revealed that modulation of IL-10 production within DNT-cell subset could affect both immune regulation and autoantibody production, contributing to the immunological dysregulation in SLE.

Biochemical and Molecular Studies on the Role of Celecoxib and Some Related Bipyrazoles in Mitigating Induced Liver Injury in Experimental Animals

Introduction

Liver fibrosis is a life-threatening disease that greatly impacts the morbidity and mortality of hepatic patients worldwide, resulting mainly as a consequence of hepatitis C, alcoholic and non-alcoholic fatty liver. COX-1 and COX-2 isozymes catalyze the synthesis of prostaglandins (PGs) and thromboxanes (TXs) from arachidonic acid causing inflammation. Owing to the scarcity of approved fibrolytic drugs available for human use, celecoxib (a selective COX-2 inhibitor) has been repurposed as a potential antifibrotic and fibrolytic agent in some chronic liver fibrosis models.

Methods

The present study aims to discover a non-invasive treatment for liver fibrosis through investigating the possible ability of three celecoxib-related bipyrazole compounds HR1-3 to reverse chemically induced liver fibrosis in rats using CCl4. This fibrolytic effect was verified by histopathological, immunohistochemical, biochemical and biomolecular assays. In addition, in silico computer-aided evaluation of the compounds' binding mode to certain molecular targets was performed, and the in silico physicochemical properties, drug likeness and pharmacokinetic parameters were predicted using web-based applications.

Results

The analogs HR1-3 could serve as novel therapeutic candidates for the mitigation of liver fibrosis that deserves further derivatizations and investigations. In particular, the fluorinated analog HR3 proved to be the most active member in this study when compared to celecoxib due to its distinguished histopathological and immunohistochemical investigation results, beside its antioxidant potential, as well as its reliable effects against some biomarkers, namely, MMP-9, TGF-β1, TIMP-1, IL-6 and TNF-α.

Conclusion

Based on the obtained results, the fluorinated analog HR3 could serve as a novel therapeutic candidate for the amelioration of liver fibrosis that deserves further derivatizations and investigations.

Proteomic analysis of B cells in peripheral lymphatic system reveals the dynamics during the systemic lupus erythematosus progression

In this study, we conducted a comprehensive proteomic analysis of B cells from the spleen, mesenteric lymph nodes (mLN), and peripheral blood mononuclear cells (PBMC) in a time-course model of systemic lupus erythematosus (SLE) using female MRL/lpr mice. By combining fluorescence-activated cell sorting (FACS) and 4D-Data-Independent Acquisition (4D-DIA) mass spectrometry, we quantified nearly 8000 proteins, identifying significant temporal and tissue-specific proteomic changes during SLE progression. PBMC-derived B cells exhibited early proteomic alterations by Week 9, while spleen-derived B cells showed similar changes by Week 12. We identified key regulatory proteins, including BAFF, BAFFR, and NFKB2, involved in B cell survival and activation, as well as novel markers such as CD11c and CD117, which have previously been associated with other immune cells. The study highlights the dynamic reprogramming of B cell proteomes across different tissues, with distinct contributions to SLE pathogenesis, providing valuable insights into the molecular mechanisms underlying B cell dysregulation in lupus. These findings offer potential therapeutic targets and biomarkers for SLE.

Systemic lupus erythematosus: updated insights on the pathogenesis, diagnosis, prevention and therapeutics

Systemic lupus erythematosus (SLE) is a chronic inflammatory illness with heterogeneous clinical manifestations covering multiple organs. Diversified types of medications have been shown effective for alleviating SLE syndromes, ranging from cytokines, antibodies, hormones, molecular inhibitors or antagonists, to cell transfusion. Drugs developed for treating other diseases may benefit SLE patients, and agents established as SLE therapeutics may be SLE-inductive. Complexities regarding SLE therapeutics render it essential and urgent to identify the mechanisms-of-action and pivotal signaling axis driving SLE pathogenesis, and to establish innovative SLE-targeting approaches with desirable therapeutic outcome and safety. After introducing the research history of SLE and its epidemiology, we categorized primary determinants driving SLE pathogenesis by their mechanisms; combed through current knowledge on SLE diagnosis and grouped them by disease onset, activity and comorbidity; introduced the genetic, epigenetic, hormonal and environmental factors predisposing SLE; and comprehensively categorized preventive strategies and available SLE therapeutics according to their functioning mechanisms. In summary, we proposed three mechanisms with determinant roles on SLE initiation and progression, i.e., attenuating the immune system, restoring the cytokine microenvironment homeostasis, and rescuing the impaired debris clearance machinery; and provided updated insights on current understandings of SLE regarding its pathogenesis, diagnosis, prevention and therapeutics, which may open an innovative avenue in the fields of SLE management.

Characterization and effective expansion of CD4-CD8- TCRαβ+ T cells from individuals living with type 1 diabetes

CD4-CD8- TCRαβ+ (double-negative [DN]) T cells represent a rare T cell population that promotes immunological tolerance through various cytotoxic mechanisms. In mice, autologous transfer of DN T cells has shown protective effects against autoimmune diabetes and graft-versus-host disease. Here, we characterized human DN T cells from people living with type 1 diabetes (PWT1D) and healthy controls. We found that while DN T cells and CD8+ T cells share many similarities, DN T cells are a unique T cell population, both at the transcriptomic and protein levels. We also show that by using various cytokine combinations, human DN T cells can be expanded in vitro up to 1,000-fold (mean >250-fold) and remain functional post-expansion. In addition, we report that DN T cells from PWT1D display a phenotype comparable to that of healthy controls, efficiently expand, and are highly functional. As DN T cells are immunoregulatory and can prevent T1D in various mouse models, these observations suggest that autologous DN T cells may be amenable to therapy for the prevention or treatment of T1D.

Jieduquyuziyin prescription alleviates lupus development via inhibiting neddylation pathway to promote Bim-induced apoptosis of double negative T cells

ETHNOPHARMACOLOGICAL RELEVANCE

Jieduquyuziyin prescription (JP) is an empirical prescription approved for application to treat systemic lupus erythematosus (SLE) in hospital within China. Despite the prominent treatment effect of JP clinically, further investigation is imperative to explore its underlying mechanisms.

AIM OF THE STUDY

We aim to investigate the impact of JP on DN T cell apoptosis in the treatment of SLE and the specific regulation mechanisms.

MATERIALS AND METHODS

Firstly, female MRL/lpr mice were treated with JP and the therapeutic efficacy of JP was evaluated via skin lesions, lymphoid organ enlargement, accumulation of autoantibodies and renal function. Then, flow cytometer analysis was performed to evaluate the proportions and the apoptosis of T cell subpopulations. Based on the above results, double-negative (DN) T cells were subjected to proteomic with subsequent differential screening. The expression of Ube2m and Bim was further validated using real-time PCR and Western blot. Subsequently, DN T cells were incubated with JP-contained serum in vitro, and cell apoptosis was quantified using flow cytometry. Additionally, the expression levels of Ube2m, Bim and other associated proteins were also assessed through western blotting. To further clarify whether Ube2m serves as the key target of JP in regulating DN T cell apoptosis, the mice that Ube2m was specific deleted in T cells with spontaneous lupus (Ube2m-/-lpr) were utilized. JP was administered to WTlpr or Ube2m-/-lpr mice, followed by assessment of the lupus condition and DN T cell apoptosis.

RESULTS

JP administration effectively ameliorated the lupus phenotype. Then flow cytometry assay showed that JP treatment enhanced DN T cell apoptosis to reduce their accumulation and restored the immune homeostasis. Proteomic analysis revealed a significant inhibition of Ube2m for JP treatment, which is essential for maintaining homeostasis of DN T cells. Further experiments confirmed that JP treatment effectively downregulated the expression of Ube2m and subsequently upregulated the level of pro-apoptotic protein Bim with decreased Bim degradation. In vitro experiments also confirmed that JP-contained serum significantly facilitated DN T cell apoptosis and reduced DN T cell accumulation by inhibiting Ube2m expression. Furthermore, Ube2m-/-lpr mice were utilized and the impact of JP treatment on the apoptosis of DN T cells was found to be minimal in the absence of Ube2m. Mechanistic investigation reveals that JP exerts its effects by suppressing the expression of Ube2m, subsequently inhibiting CRL-dependent degradation of Bim, and ultimately promoting Bim-induced apoptosis in DN T cells. Furthermore, the blockade of Ube2m in T cells effectively prevents JP-induced apoptosis in DN T cells, underscoring Ube2m as one crucial therapeutic target of JP in mediating DN T cell apoptosis and managing SLE.

CONCLUSIONS

Our findings indicate that JP treatment effectively restores the homeostasis of DN T cells in SLE by inhibiting Ube2m expression, thereby reducing Bim ubiquitination degradation. This ultimately enhanced DN T cell apoptosis and alleviated lupus phenotype.

Double negative T cells promote surgery-induced neuroinflammation, microglial engulfment and cognitive dysfunction via the IL-17/CEBPβ/C3 pathway in adult mice

CD3(+) CD4(-) CD8(-) double negative T cells (DNTs) manifest themselves in autoimmune diseases and associated inflammation. In the central nervous system, the increased presence of DNTs is associated with the progression of neurological conditions and brain injury. Active DNTs that produce IL-17 have been regarded as a pro-inflammatory phenotype. The IL-17 signaling pathway mediates neuroinflammatory responses by inducing glial activation and producing inflammatory factors. Neuroinflammation is considered integral to the pathogenesis of perioperative neurocognitive disorders (PNDs), commonly developed after surgery in susceptible patients. We and others have demonstrated a significant role for complement C3 in surgery-induced neuroinflammation and cognitive impairment but the regulatory mechanisms for this remain unexplored. We hypothesized that surgery induces DNT infiltration into the CNS that in turn upregulates complement C3 expression and this causes changes that contribute to cognitive impairment. Using an adult murine abdominal surgery model, we investigated perioperative changes in cognitive performance, quantifying the presence of T cell subsets and phenotype, IL-17 signaling pathway activation, glial cell activation and C3 expression in the brain. Postoperative IL-17 specific inhibitor GSK2981278 administration or preoperatively conditional CEBPβ knock-down by AAV9 viral vector were then applied to evaluate the effect of inhibiting IL-17 signaling pathway on postoperative C3 expression and cognitive performance. The results showed an increased hippocampus infiltration of DNTs with augmented IL-17 production, along with C3 upregulation and cognitive impairment. Both inhibition of IL-17 or knock-down of CEBPβ significantly suppressed C3 expression, synaptic engulfment by microglia and attenuated cognitive impairment. These findings indicate that DNTs promote postoperative neuroinflammation and cognitive impairment via the IL-17/CEBPβ/C3 pathway and targeting this IL-17 axis could be a potential therapeutic strategy to ameliorate postoperative neuroinflammation and cognitive impairment.

Application of deep learning models on single-cell RNA sequencing analysis uncovers novel markers of double negative T cells

Double negative T (DNT) cells are a unique subset of CD3 + TCRαβ + T lymphocytes that lack CD4, CD8, or NK1.1 expression and constitute 3-5% of the total T cell population in C57BL/6 mice. They have increasingly gained recognition for their novel roles in the immune system, especially under autoimmune conditions. Conventional machine learning approaches such as principal component analysis have been employed in single-cell RNA sequencing (scRNA-seq) analysis to characterize DNT cells. However, advanced deep learning models such as Single Cell Variational Inference (scVI) have the capability to capture nonlinear gene expression patterns in the sequencing data. In this study, employing the deep learning methodology, we have revealed novel markers for splenic DNT cells in C57BL/6 mice which were validated with flow cytometry analysis. We classified DNT cells into two subgroups, naïve DNT (nDNT) cells differentiated by the expression of Ly6C and activated DNT (aDNT) cells differentiated by the expression of MHC-II. A prior study had predicted elevated expression of CD137/4-1BB encoded by Tnfrsf9 in nDNT cells; however, our analysis predicted and validated that CD137 was a marker for aDNT cells instead of nDNT cells. Innovatively, our data also identified CD30 encoded by Tnfrsf8 and CD153/CD30L encoded by Tnfsf8 as additional markers for aDNT cells. In addition, we classified three subgroups in nDNT cells and two subgroups in aDNT cells. Our scVI analysis suggested, and flow cytometry analysis confirmed, that Ly49G2 encoded by Slamf7 was a marker for the nDNT0 subgroup. Importantly, we validated that MHC-II was indeed expressed by a subset of human DNT cells suggesting the presence of a human aDNT population. Furthermore, we found increased expression of CD30, CD153, and CD137 on aDNT cells in MRL/lpr mice compared to those in C57BL/6 mice suggesting potential pathogenic roles of these molecules in autoimmunity. Together, our comprehensive analysis has uncovered and validated novel markers for different subpopulations of DNT cells that can be used in the phenotypic and/or functional characterization of these relatively rare cells in health and disease.

Single-Cell Transcriptome Reveals the Heterogeneity of T Cells in Mice with Systemic Lupus Erythematosus and Neuronal Inflammation

Introduction

Systemic lupus erythematosus is a heterogeneous autoimmune disease. A burst of autoimmune reactions in various systems can lead to severe clinical conditions closely associated with mortality. T cells serve as mediators that drive the occurrence and maintenance of inflammatory processes.

Methods

In this work, we employed single-cell transcriptome sequencing (scRNA-seq) involving 27704 cells from the brain and spleen tissues of MRL/lpr mice and 25355 healthy controls from BALB/c mice to explore the heterogeneity of T cells and their migration from the spleen to the brain.

Results

We identified a distinct group of double-negative T cells in systemic lupus erythematosus (SLE) mice that significantly expressed Eomes and other specific markers. We used the analysis of pseudotime trajectory and enrichment to show that double-negative T cells in SLE mice are strongly associated with cellular senescence and exhaustion. Additionally, we focused on the interactions among DNT, astrocytes, and microglia in the mice brain. We observed greater expression of MDK-related ligand‒receptor pairs between astrocytes and double-negative T cells, indicating that MDK may be a therapeutic target for treating neuroinflammation in SLE.

Discussion

This research sheds light on the intricate dynamics of immune responses in mice with SLE, specifically highlighting the role of double-negative T cells and their connection to cellular senescence. The exploration of interactions between T cells, astrocytes, and microglia in the mice brain unveils potential avenues for therapeutic intervention, particularly in addressing neuronal inflammation in SLE.

Causal relationship between inflammatory proteins, immune cells, and gout: a Mendelian randomization study

Prior research has documented the association between certain circulating inflammatory proteins/immune cells and gout. However, the reliability of these associations remains contentious due to the constraints of conventional observational methodologies. This investigation seeks to reassess the causative link between circulating inflammatory proteins/immune cells and gout through the application of Mendelian randomization (MR). The study included 3576 individuals of European ancestry with gout, immune cell data from the GWAS summary of 3757 Sardinians, and circulating inflammatory protein data from 14,824 European ancestry participants for MR analysis. The principal approach employed was inverse variance weighted analysis to investigate the causal relationship between exposure and outcomes. The results indicate that CD28 on CD39+ CD4+ T cells may be associated with a reduced risk of gout. Additionally, CD45RA+ CD28- CD8bright T cells may also be associated with a reduced risk of gout. In contrast, DN (CD4-CD8-) T cells and IL-12β may increase the risk of gout. Some inflammatory proteins and immune cells show potential causal associations with gout. Nevertheless, additional experimental verification is warranted to assess the underlying mechanisms and confirm the causative role of these immune factors in gout pathogenesis.

Double-negative T cells in pediatric rheumatic diseases

Double-negative (CD4-CD8-) T (DNT) cells have been implicated in autoimmune lymphoproliferative syndrome (ALPS), where their expansion inside the circulating pool of T cells represents a diagnostic criterion. Recent experimental evidence has supported the immunomodulatory roles of DNT cells, and studies in adult patients have suggested that they may be altered in some immune-mediated conditions. This study aimed to retrieve available data on circulating DNT cells in pediatric rheumatic disorders that do not arise in the context of ALPS through a systematic literature review of 3 scientific databases (PubMed, Scopus, and Web of Science). The final output of the systematic literature search consisted of 8 manuscripts, including cross-sectional (n=6) and longitudinal (n=2) studies. Overall, the pooled population of patients includes children affected with pediatric systemic lupus erythematosus (n= 104), juvenile idiopathic arthritis (n=92), Behçet's disease (n=15), mixed connective tissue disease (n=8), juvenile dermatomyositis (n=6), and Kawasaki disease/multisystem inflammatory disease in children (n=1 and n=14, respectively); moreover, one study also included 11 children with a high titer of antinuclear antibody but no diagnosis of rheumatic disease. All studies except one included a control group. The number of DNT cells were increased in most studies of children with rheumatic diseases. Even if such a limited number of studies and their great heterogeneity in several methodological aspects do not allow for reliable conclusions about the relevance of DNT cells in specific rheumatic conditions in children, this cell population deserves further investigation in this pathological setting through well-designed clinical studies.

Lymphocytes Change Their Phenotype and Function in Systemic Lupus Erythematosus and Lupus Nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease, characterized by considerable changes in peripheral lymphocyte structure and function, that plays a critical role in commencing and reviving the inflammatory and immune signaling pathways. In healthy individuals, B lymphocytes have a major role in guiding and directing defense mechanisms against pathogens. Certain changes in B lymphocyte phenotype, including alterations in surface and endosomal receptors, occur in the presence of SLE and lead to dysregulation of peripheral B lymphocyte subpopulations. Functional changes are characterized by loss of self-tolerance, intra- and extrafollicular activation, and increased cytokine and autoantibody production. T lymphocytes seem to have a supporting, rather than a leading, role in the disease pathogenesis. Substantial aberrations in peripheral T lymphocyte subsets are evident, and include a reduction of cytotoxic, regulatory, and advanced differentiated subtypes, together with an increase of activated and autoreactive forms and abnormalities in follicular T cells. Up-regulated subpopulations, such as central and effector memory T cells, produce pre-inflammatory cytokines, activate B lymphocytes, and stimulate cell signaling pathways. This review explores the pivotal roles of B and T lymphocytes in the pathogenesis of SLE and Lupus Nephritis, emphasizing the multifaceted mechanisms and interactions and their phenotypic and functional dysregulations.

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.

Double-negative T cells have a reparative role after experimental severe ischemic acute kidney injury

T cells mediate organ injury and repair. A proportion of unconventional kidney T cells called double-negative (DN) T cells (TCR+ CD4- CD8-), with anti-inflammatory properties, were previously demonstrated to protect from early injury in moderate experimental acute kidney injury (AKI). However, their role in repair after AKI has not been studied. We hypothesized that DN T cells mediate repair after severe AKI. C57B6 mice underwent severe (40 min) unilateral ischemia-reperfusion injury (IRI). Kidney DN T cells were studied by flow cytometry and compared with gold-standard anti-inflammatory CD4+ regulatory T cells (Tregs). In vitro effects of DN T cells and Tregs on renal tubular epithelial cell (RTEC) repair after injury were quantified with live-cell analysis. DN T cells, Tregs, CD4, or vehicle were adoptively transferred after severe AKI. Glomerular filtration rate (GFR) was measured using fluorescein isothiocyanate (FITC)-sinistrin. Fibrosis was assessed with Masson's trichrome staining. Profibrotic genes were measured with qRT-PCR. Percentages and the numbers of DN T cells substantially decreased during repair phase after severe AKI, as well as their activation and proliferation. Both DN T cells and Tregs accelerated RTEC cell repair in vitro. Post-AKI transfer of DN T cells reduced kidney fibrosis and improved GFR, as did Treg transfer. DN T cell transfer lowered transforming growth factor (TGF)β1 and α-smooth muscle actin (αSMA) expression. DN T cells reduced effector-memory CD4+ T cells and IL-17 expression. DN T cells undergo quantitative and phenotypical changes after severe AKI, accelerate RTEC repair in vitro as well as improve GFR and renal fibrosis in vivo. DN T cells have potential as immunotherapy to accelerate repair after AKI.NEW & NOTEWORTHY Double-negative (DN) T cells (CD4- CD8-) are unconventional kidney T cells with regulatory abilities. Their role in repair from acute kidney injury (AKI) is unknown. Kidney DN T cell population decreased during repair after ischemic AKI, in contrast to regulatory T cells (Tregs) which increased. DN T cell administration accelerated tubular repair in vitro, while after severe in vivo ischemic injury reduced kidney fibrosis and increased glomerular filtration rate (GFR). DN T cell infusion is a potential therapeutic agent to improve outcome from severe AKI.

Immune profiling analysis of double-negative T cells in patients with systemic sclerosis

OBJECTIVE

To construct a molecular immune map of patients with systemic sclerosis (SSc) by mass flow cytometry, and compare the number and molecular expression of double-negative T (DNT) cell subsets between patients and healthy controls (HC).

METHODS

Peripheral blood mononuclear cells (PBMCs) were extracted from the peripheral blood of 17 SSc patients and 9 HC. A 42-channel panel was set up to perform mass cytometry by time of flight (CyTOF) analysis for DNT subgroups. Flow cytometry was used to validate subpopulation functions. The clinical data of patients were collected for correlation analysis.

RESULTS

Compared with HC, the number of total DNT cells decreased in SSc patients. Six DNT subsets were obtained from CyTOF analysis, in which the proportion of cluster1 increased, while the proportion of cluster3 decreased. Further analysis revealed that cluster1 was characterized by high expression of CD28 and CCR7, and cluster3 was characterized by high expression of CD28 and CCR5. After in vitro stimulation, cluster1 secreted more IL-4 and cluster3 secreted more IL-10 in SSc patients compared to HC. Clinical correlation analysis suggested that cluster1 may play a pathogenic role while cluster3 may play a protective role in SSc. ROC curve analysis further revealed that cluster3 may be a potential indicator for determining disease activity in SSc patients.

CONCLUSION

We found a new CCR5+CD28+ DNT cell subset, which played a protective role in the pathogenesis of SSc. Key Points • The number of DNT cells decreased in SSc patients' peripheral blood. • DNT cells do not infiltrate in the skin but secrete cytokines to participate in the pathogenesis of SSc. • A CCR5+CD28+ DNT cell population may play a protective role in SSc.

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.

Novel mitophagy inducer alleviates lupus nephritis by reducing myeloid cell activation and autoantigen presentation

Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), but its mechanism of onset remains unclear. Since impaired mitophagy has been implicated in multiple organs in SLE, we hypothesized that mitophagy dysfunction is critical in the development of LN and that pharmacologically targeting mitophagy would ameliorate this disease. Therefore, lupus-prone MRL/MpJ-Faslpr (MRL/lpr) and NZBWF1/J mice were treated with a novel mitophagy inducer, UMI-77, during their onset of LN. This treatment effectively mitigated kidney inflammation and damage as assessed by histology and flow cytometry. Furthermore, dendritic cell (DC)-T-cell coculture assay indicated that UMI-77 treatment attenuated DC function that would drive T-cell proliferation but did not directly influence the potent T-cell proliferation in lupus mice. UMI-77 also restored mitochondrial function and attenuated proinflammatory phenotypes in lupus DCs. Adoptive transfer of DCs from MRL/lpr mice augmented serum anti-dsDNA IgG, urine protein and T-cell infiltration of the kidney in MRL/MpJ mice, which could be prevented by either treating lupus donors in vivo or lupus DCs directly with UMI-77. UMI-77 also restored mitochondrial function in myeloid cells from patients with LN in vitro as evidenced by increased ATP levels. Thus, enhancing mitophagy in SLE restrains autoimmunity and limits kidney inflammation for LN development. Hence, our findings suggest targeting mitophagy as a tangible pathway to treat LN.

Kidney double positive T cells have distinct characteristics in normal and diseased kidneys

Multiple types of T cells have been described and assigned pathophysiologic functions in the kidneys. However, the existence and functions of TCR+CD4+CD8+ (double positive; DP) T cells are understudied in normal and diseased murine and human kidneys. We studied kidney DPT cells in mice at baseline and after ischemia reperfusion (IR) and cisplatin injury. Additionally, effects of viral infection and gut microbiota were studied. Human kidneys from patients with renal cell carcinoma were evaluated. Our results demonstrate that DPT cells expressing CD4 and CD8 co-receptors constitute a minor T cell population in mouse kidneys. DPT cells had significant Ki67 and PD1 expression, effector/central memory phenotype, proinflammatory cytokine (IFNγ, TNFα and IL-17) and metabolic marker (GLUT1, HKII, CPT1a and pS6) expression at baseline. IR, cisplatin and viral infection elevated DPT cell proportions, and induced distinct functional and metabolic changes. scRNA-seq analysis showed increased expression of Klf2 and Ccr7 and enrichment of TNFα and oxidative phosphorylation related genes in DPT cells. DPT cells constituted a minor population in both normal and cancer portion of human kidneys. In conclusion, DPT cells constitute a small population of mouse and human kidney T cells with distinct inflammatory and metabolic profile at baseline and following kidney injury.

Microplastics exposure induced and exacerbated the development of systemic lupus erythematosus in mice

Environmental exposure may function as a contributing risk factor in the development of systemic lupus erythematosus (SLE). Recently, the global issue of microplastics (MPs) pollution has garnered increasing concern, yet its potential impact on SLE remains unexplored. This study seeks to elucidate the ramifications of MPs exposure on lupus manifestations in spontaneous lupus MRL/lpr mice and normal C57L/6 mice. MPs exposure demonstrated the capacity to induce lupus-like symptoms in C57BL/6 mice and exacerbate lupus symptoms in MRL/lpr mice. This was manifested by MPs triggering abnormal elevation of spleen DN T, plasma cells, serum anti-dsDNA, ANA, IL-6, and TNF-α, coupled with a reduction in spleen CD4+/CD8+ cell ratio, and impairment in renal pathology. Moreover, a 4D-DIA quantitative proteomic analysis was employed to unveil substantial alterations in renal proteins attributed to MPs exposure. The findings indicated that the KEGG pathways significantly enriched by MPs-associated different proteins in C57BL/6 mice were closely aligned with the enriched KEGG pathways associated with lupus. Unlike C57BL/6 mice, there were no significantly enriched KEGG pathways identified among the MPs-associated different proteins in MRL/lpr mice. In addition, proteins related to the SLE pathway illuminated that MPs exposure induced renal damage through activation of MHCII and histone H3, culminating in the production of MAC in both C57BL/6 and MRL/lpr mice. However, a specific elevation in cathepsin and elastase caused by MPs was observed in C57BL/6 mice but not in MRL/lpr mice. This study represents a significant stride in bridging the existing knowledge gap pertaining to the intricate relationship between MPs exposure and the development of SLE.

Neddylation is a novel therapeutic target for lupus by regulating double negative T cell homeostasis

Systemic lupus erythematosus (SLE), a severe autoimmune disorder, is characterized by systemic inflammatory response, autoantibody accumulation and damage to organs. The dysregulation of double-negative (DN) T cells is considered as a crucial commander during SLE. Neddylation, a significant type of protein post-translational modification (PTM), has been well-proved to regulate T cell-mediated immune response. However, the function of neddylation in SLE is still unknown. Here, we reported that neddylation inactivation with MLN4924, a specific inhibitor of NEDD8-activating enzyme E1 (NAE1), or genetic abrogation of Ube2m in T cells decreased DN T cell accumulation and attenuated murine lupus development. Further investigations revealed that inactivation of neddylation blocked Bim ubiquitination degradation and maintained Bim level in DN T cells, contributing to the apoptosis of the accumulated DN T cells in lupus mice. Then double knockout (KO) lupus-prone mice (Ube2m-/-Bim-/-lpr) were generated and results showed that loss of Bim reduced Ube2m deficiency-induced apoptosis in DN T cells and reversed the alleviated lupus progression. Our findings identified that neddylation inactivation promoted Bim-mediated DN T cell apoptosis and attenuated lupus progression. Clinically, we also found that in SLE patients, the proportion of DN T cells was raised and their apoptosis was reduced. Moreover, compared to healthy groups, SLE patients exhibited decreased Bim levels and elevated Cullin1 neddylation levels. Meantime, the inhibition of neddylation induced Bim-dependent apoptosis of DN T cells isolated from SLE patients. Altogether, our findings provide the direct evidence about the function of neddylation during lupus, suggesting a promising therapeutic approach for this disease.

Double-Negative T (DNT) Cells in Patients with Systemic Lupus Erythematosus

Double-negative T (DNT) cells are a rare and unconventional T-lymphocyte subpopulation lacking both CD4 and CD8 markers. Their immunopathological roles and clinical relevance have yet to be elucidated. Beyond autoimmune lymphoproliferative syndrome (ALPS), these cells may also play a role in rheumatic disorders, including systemic lupus erythematosus (SLE); indeed, these two diseases share several autoimmune manifestations (including nephritis). Moreover, one of the main experimental murine models used to investigate lupus, namely the MRL/lpr mouse, is characterized by an expansion of DNT cells, which can support the production of pathogenic autoantibodies and/or modulate the immune response in this context. However, lupus murine models are not completely consistent with their human SLE counterpart, of course. In this mini review, we summarize and analyze the most relevant clinical studies investigating the DNT cell population in SLE patients. Overall, based on the present literature review and analysis, DNT cell homeostasis seems to be altered in patients with SLE. Indeed, most of the available clinical studies (which include both adults and children) reported an increased DNT cell percentage in SLE patients, especially during the active phases, even though no clear correlation with disease activity and/or inflammatory parameters has been clearly established. Well-designed, standardized, and longitudinal clinical studies focused on DNT cell population are needed, in order to further elucidate the actual contribution of these cells in SLE pathogenesis and their interactions with other immune cells (also implicated and/or altered in SLE, such as basophils), and clarify whether their expansion and/or immunophenotypic aspects may have any immunopathological relevance (and, then, represent potential disease markers and, in perspective, even therapeutic targets) or are just an unspecific epiphenomenon of 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.

Elevated TCR-αβ+ double-negative T cells in pediatric patients with acquired aplastic anemia

BACKGROUND AND AIMS

The pathophysiology of acquired aplastic anemia (aAA) is most associated with T cell mediated immune dysfunction, but the role of CD4- CD8- double negative T cells (DNTs) in pediatric patients with aAA is unclear. In this study, we aimed to investigate the proportion of TCR-αβ+ DNTs in pediatric patients with aAA and correlation with the response to immunosuppressive therapy (IST).

MATERIALS AND METHODS

Assessment of DNTs from peripheral blood was done by sensitive multi-color flow cytometry. The potential clinical value of TCR-αβ+ DNTs was then assessed by the receiver operating characteristic (ROC) curves.

RESULTS

The retrospective study evaluated 164 pediatric patients with aAA and 105 healthy donors (HD). Our data showed higher proportion of TCR-αβ+ DNTs in total lymphocytes [1.04% (0.79%-1.40%) vs 0.69% (0.47%-0.87%), p < 0.001] and CD3+ T cells [1.52% (1.10%-1.96%) vs 1.10% (0.70%-1.40%), p < 0.001] in aAA compared to HD. Patients with SAA/VSAA achieving complete response (CR) after IST had a higher proportion of TCR-αβ+ DNTs at initial diagnosis, than those not achieving CR for total (1.21%±0.39 vs 0.78%±0.38, p < 0.05) and CD3+ T cells (1.74%±0.53 vs 1.15%±0.59, p < 0.05). The ROC analysis showed areas under the curves (AUCs) for TCR-αβ+ DNT proportion in lymphocytes and CD3+ T cells were 0.756 (cutoff value 1.33, p < 0.05) and 0.758 (cutoff value 1.38, p < 0.05), respectively. And the complete response rate was higher in TCR-αβ+ DNT proportion high group than in TCR-αβ+ DNT proportion low group at baseline (p < 0.001).

CONCLUSION

Our observations suggest that elevated TCR-αβ+ DNTs seems to play a role in the pathogenesis of aAA, and it was involve in immune response to IST.

Decipher the Immunopathological Mechanisms and Set Up Potential Therapeutic Strategies for Patients with Lupus Nephritis

Lupus nephritis (LN) is one of the most severe complications in patients with systemic lupus erythematosus (SLE). Traditionally, LN is regarded as an immune complex (IC) deposition disease led by dsDNA-anti-dsDNA-complement interactions in the subendothelial and/or subepithelial basement membrane of glomeruli to cause inflammation. The activated complements in the IC act as chemoattractants to chemically attract both innate and adaptive immune cells to the kidney tissues, causing inflammatory reactions. However, recent investigations have unveiled that not only the infiltrating immune-related cells, but resident kidney cells, including glomerular mesangial cells, podocytes, macrophage-like cells, tubular epithelial cells and endothelial cells, may also actively participate in the inflammatory and immunological reactions in the kidney. Furthermore, the adaptive immune cells that are infiltrated are genetically restricted to autoimmune predilection. The autoantibodies commonly found in SLE, including anti-dsDNA, are cross-reacting with not only a broad spectrum of chromatin substances, but also extracellular matrix components, including α-actinin, annexin II, laminin, collagen III and IV, and heparan sulfate proteoglycan. Besides, the glycosylation on the Fab portion of IgG anti-dsDNA antibodies can also affect the pathogenic properties of the autoantibodies in that α-2,6-sialylation alleviates, whereas fucosylation aggravates their nephritogenic activity. Some of the coexisting autoantibodies, including anti-cardiolipin, anti-C1q, anti-ribosomal P autoantibodies, may also enhance the pathogenic role of anti-dsDNA antibodies. In clinical practice, the identification of useful biomarkers for diagnosing, monitoring, and following up on LN is quite important for its treatments. The development of a more specific therapeutic strategy to target the pathogenic factors of LN is also critical. We will discuss these issues in detail in the present article.

CX3CR1 modulates SLE-associated glomerulonephritis and cardiovascular disease in MRL/lpr mice

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) often develop multi-organ damages including heart and kidney complications. We sought to better define the underlying mechanisms with a focus on the chemokine receptor CX3CR1.

METHODS

We generated Cx3cr1-deficient MRL/lpr lupus-prone mice through backcrossing. We then employed heterozygous intercross to generate MRL/lpr littermates that were either sufficient or deficient of CX3CR1. The mice were also treated with either Lactobacillus spp. or a high-fat diet (HFD) followed by assessments of the kidney and heart, respectively.

RESULTS

Cx3cr1-/- MRL/lpr mice exhibited a distinct phenotype of exacerbated glomerulonephritis compared to Cx3cr1+/+ littermates, which was associated with a decrease of spleen tolerogenic marginal zone macrophages and an increase of double-negative T cells. Interestingly, upon correction of the gut microbiota with Lactobacillus administration, the phenotype of exacerbated glomerulonephritis was reversed, suggesting that CX3CR1 controls glomerulonephritis in MRL/lpr mice through a gut microbiota-dependent mechanism. Upon treatment with HFD, Cx3cr1-/- MRL/lpr mice developed significantly more atherosclerotic plaques that were promoted by Ly6C+ monocytes. Activated monocytes expressed ICOS-L that interacted with ICOS-expressing follicular T-helper cells, which in turn facilitated a germinal center reaction to produce more autoantibodies. Through a positive feedback mechanism, the increased circulatory autoantibodies further promoted the activation of Ly6C+ monocytes and their display of ICOS-L.

CONCLUSIONS

We uncovered novel, Cx3cr1 deficiency-mediated pathogenic mechanisms contributing to SLE-associated glomerulonephritis and cardiovascular disease.

Labour promotes systemic mobilisation of monocytes, T cell activation and local secretion of chemotactic factors in the intervillous space of the placenta

During pregnancy, maternal blood circulates through the intervillous space of the placenta and the reciprocal interactions between foetal tissues and maternal immune cells makes the intervillous space a unique immunological niche. Labour is characterised by a proinflammatory response in the myometrium, but the relationship between local and systemic changes during the onset of labour remains elusive. We here aimed to investigate how the systemic and intervillous circulatory systems are affected during labour from an immunological point of view. We report that the proportion of monocytes is dramatically higher in peripheral (PB), intervillous blood (IVB) and decidua in labouring (n = 14) compared to non-labouring women (n = 15), suggesting that labour leads to both a systemic and local mobilisation of monocytes. Labour was associated with a relative increase of effector memory T cells in the intervillous space compared to the periphery, and MAIT cells and T cells showed an elevated expression of activation markers both in PB and IVB. Intervillous monocytes consisted to a higher degree of CD14+CD16+ intermediate monocytes compared to peripheral monocytes, independently of mode of delivery, and displayed an altered phenotypic expression pattern. A proximity extension assay analysis of 168 proteins revealed that several proteins associated to myeloid cell migration and function, including CCL2 and M-CSF, were upregulated in IVB plasma in labouring women. Thus, the intervillous space could be a bridging site for the communication between the placenta and the periphery, which contribute to monocyte mobilisation and generation of inflammatory reactions during spontaneous labour.

Pathogenesis of lupus nephritis: the contribution of immune and kidney resident cells

PURPOSE OF REVIEW

Lupus nephritis is associated with significant mortality and morbidity. We lack effective therapeutics and biomarkers mostly because of our limited understanding of its complex pathogenesis. We aim to present an overview of the recent advances in the field to gain a deeper understanding of the underlying cellular and molecular mechanisms involved in lupus nephritis pathogenesis.

RECENT FINDINGS

Recent studies have identified distinct roles for each resident kidney cell in the pathogenesis of lupus nephritis. Podocytes share many elements of innate and adaptive immune cells and they can present antigens and participate in the formation of crescents in coordination with parietal epithelial cells. Mesangial cells produce pro-inflammatory cytokines and secrete extracellular matrix contributing to glomerular fibrosis. Tubular epithelial cells modulate the milieu of the interstitium to promote T cell infiltration and formation of tertiary lymphoid organs. Modulation of specific genes in kidney resident cells can ward off the effectors of the autoimmune response including autoantibodies, cytokines and immune cells.

SUMMARY

The development of lupus nephritis is multifactorial involving genetic susceptibility, environmental triggers and systemic inflammation. However, the role of resident kidney cells in the development of lupus nephritis is becoming more defined and distinct. More recent studies point to the restoration of kidney resident cell function using cell targeted approaches to prevent and treat lupus nephritis.

Interrelation of T cell cytokines and autoantibodies in systemic lupus erythematosus: A cross-sectional study

T-helper cytokines interferon gamma (IFNɣ), interleukin 17 (IL-17) and IL-10 impact systemic lupus erythematosus (SLE) directly and indirectly via modulation of autoAb production. We determined the separate and combined effects on clinical manifestations of SLE (N = 62). IFNɣ, IL-17 but not IL-10 were significantly elevated in patients with SLE. IFNɣ positively correlated with anti-DNA and anti-SSA. IL-17 positively correlated with anti-SSA and was significantly higher in patients with discoid rash and class V LN. IL-10 did not correlate with circulating autoantibodies but was significantly elevated in patients with LN. Patients with LN had elevated plasma levels of anti-DNA and anti-Sm/ribonuclear protein (RNP). Anti-Sm/RNP levels were decreased in patients with acute mucocutaneous manifestations, including photosensitivity and/or malar rash. The study provides critical insights into pathological mechanisms of LN, which could help guide future diagnoses and therapies.

Decoding systems immunological model of sphingolipids with IL-6/IL-17/IL-23 axes in L. major infection

IL-6, IL-17, IL-23 and IL-1β are the crucial cytokines controlling inflammatory and immune response during L. major infection. During cutaneous leishmaniasis, an important T helper cell type CD4⁺ Th17 subset plays a deterministic role in lesion formation through channelling infected macrophages and production of IL-1β, IL-6, IL-23 and IFN-γ. Ceramide derived sphingosine precursors may assist in pro-inflammatory cytokine response. However, the role of these metabolites in inflammation with pleiotropic pro-inflammatory cytokines in L. major infection is unknown. The present study indicates IL-6/IL-17/IL-23 and SPHK1-S1P-S1PRs signaling axes with the overexpression of SATB1 aiding in disease progression. Targeting SATB1 might modulate the secretion of pro-inflammatory cytokines and abnormal immune functioning, thereby killing the intracellular parasite. Systems immunological methods assisted in a step towards identifying the key to the mystery of crucial components and serving as an approach for therapeutic intervention in L. major infection.

The star target in SLE: IL-17

PURPOSE

The purpose of this review is to discuss the significance of IL-17 in SLE and the potential of IL-17-targeted therapy.

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect many organs and tissues throughout the body. It is characterized by overactive B and T cells and loss of immune tolerance to autoantigens. Interleukin-17 (IL-17) is a cytokine that promotes inflammation and has been implicated in the pathogenesis of several autoimmune diseases as well as inflammatory diseases. In in vitro cellular experiments in lupus susceptible mice or SLE patients, there is substantial evidence that IL-17 is a highly promising therapeutic target.

METHODS

We searched papers from PubMed database using the search terms, such as interleukin-17, systemic lupus erythematosus, treatment targets, T cells, lupus nephritis, and other relevant terms.

RESULTS

We discuss in this paper the molecular mechanisms of IL-17 expression, Th17 cell proliferation, and the relationship between IL-17 and Th17. The significance of IL-17 in SLE and the potential of IL-17-targeted therapy are further discussed in detail.

CONCLUSION

IL-17 has a very high potential for the development as a star target in SLE.

Regulation of CD8 T cell by B-cells: A narrative review

Activation of CD4 T cells by B cells has been extensively studied, but B cell-regulated priming, proliferation, and survival of CD8 T cells remains controversial. B cells express high levels of MHC class I molecules and can potentially act as antigen-presenting cells (APCs) for CD8 T cells. Several in vivo studies in mice and humans demonstrate the role of B cells as modulators of CD8 T cell function in the context of viral infections, autoimmune diseases, cancer and allograft rejection. In addition, B-cell depletion therapies can lead to impaired CD8 T-cell responses. In this review, we attempt to answer 2 important questions: 1. the role of B cell antigen presentation and cytokine production in the regulation of CD8 T cell survival and cell fate determination, and 2. The role of B cells in the formation and maintenance of CD8 T cell memory.

Metabolism-dependent ferroptosis promotes mitochondrial dysfunction and inflammation in CD4+ T lymphocytes in HIV-infected immune non-responders

BACKGROUND

HIV immune non-responders (INRs) are described as a failure to reestablish a pool of CD4⁺ T lymphocytes (CD4 cells) after antiretroviral therapy (ART), which is related to poor clinical results. Ferroptosis is a newly discovered form of cell death characterised by iron-dependent lipid peroxidation and the accumulation of reactive oxygen species (ROS). The mechanism of unrecoverable CD4 cells in INRs and whether ferroptosis plays a role are not fully understood.

METHODS

Ninety-two people living with HIV (PLHIVs) who experienced four-year ART with sustained viral suppression, including 27 INRs, 34 partial responders (PRs), and 31 complete responders (CRs); and 26 uninfected control participants (UCs) were analysed for 16 immune parameters with flow cytometry. Then plasma lipid, iron and oxidation, and antioxidant indicators were detected by ELISA, and CD4 cells were sorted out and visualised under transmission electron microscopy. Finally, ferroptosis inhibitors were added, and alterations in CD4 cell phenotype and function were observed.

FINDINGS

We found decreased recent thymic emigrants (RTE), over-activation and over-proliferation phenotypes, diminished killing function, decreased IL-7R and more severe inflammation; increased lipid peroxidation in the mitochondria and disruptions of the mitochondrial structure, showing typical features of ferroptosis in CD4 cells in INRs. Additionally, ferroptosis inhibitors could reduce inflammation and repair mitochondrial damage. Meanwhile, ELISA results showed increased plasma free fatty acids (FFA) and an imbalance of oxidative and antioxidant systems in INRs. Flow cytometry results displayed alterations of both transferrin receptor (CD71) and lipid transporter (CD36) expressions on the surface of CD4 cells. Mechanistically, there was a stronger correlation between CD36 expression and mitochondrial lipid peroxidation production, ferroptosis makers, and inflammation indicators; while amino acid transporter (CD98) was more related to killing functions; and CD71 was more closely related to activation status in CD4 cells.

INTERPRETATION

Cellular metabolism was closely correlated with its diverse functions in INRs. Ferroptosis was observed in CD4 cells of INRs, and inhibiting ferroptosis through modulating mitochondrial disorders and inflammation may offer an alternative immunological strategy for reinvigorating CD4 cells in INRs.

FUNDING

This research was supported by the 13th Five-year Plan, Ministry of Science and Technology of China (2018ZX10302-102), Beijing Municipal Administration of Hospitals' Ascent Plan (DFL20191802), and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX202126).

Different Types of Chronic Inflammation Engender Distinctive Immunosenescent Profiles in Affected Patients

Immunosenescence encompasses a spectrum of lymphocyte phenotypic alterations. The aim of the study was to evaluate immunosenescent effect of two different forms of chronic inflammation, Systemic Lupus Erythematosous (SLE), a systemic autoimmune disease, and End-Stage Kidney Disease (ESKD), a chronic inflammatory disorder. Certain lymphocyte surface molecules, including CD31, CD45RA, CCR7, CD28, CD57, for T, and IgD, CD27 for B lymphocytes, were analyzed by flow cytometry in 30 SLE and 53 ESKD patients on hemodialysis (HD), and results were compared to 31 healthy controls (HC) of similar age, gender, and nationality. Significant Lymphopenia was evident in both SLE and ESKD-HD patients, compared to HC, affecting B cells 75.4 (14.4−520.8), 97 (32−341), and 214 (84−576) cells/μL, respectively, p < 0.0001, and CD4 cells 651.2 (71.1−1478.2), 713 (234−1509), and 986 (344−1591) cells/μL, respectively, p < 0.0001. The allocation of B cell subpopulations was remarkably different between SLE and ESKD-HD patients. SLE showed a clear shift to senescence (CD19IgD-CD27−) cells, compared to ESKD-HD and HC, 11.75 (10)% vs. 8 (6) vs. 8.1 (10), respectively. Regarding T lymphocytes, Central Memory CD8 cells predominated in both SLE and ESKD-HD patients compared to HC, 53 (50)%, 52 (63), and 24 (64)%, respectively, while ESKD-HD but not SLE patients also had increased expression of CD4CD28− and CD8CD28− cells. In conclusion, both diseases are followed by significant lymphopenia; however, the senescent phenomenon affects the B lymphocyte compartment in SLE patients and T lymphocytes in ESKD-HD patients.

P2X7 purinergic receptor plays a critical role in maintaining T-cell homeostasis and preventing lupus pathogenesis

The severe lymphoproliferative and lupus diseases developed by MRL/lpr mice depend on interactions between the Fas^lpr mutation and MRL genetic background. Thus, the Fas^lpr mutation causes limited disease in C57BL/6 mice. We previously found that accumulating B220⁺ CD4^–CD8^– double negative (DN) T cells in MRL/lpr mice show defective P2X7 receptor ( P2X7)-induced cellular functions, suggesting that P2X7 contributes to T-cell homeostasis, along with Fas. Therefore, we generated a B6/lpr mouse strain (called B6/lpr-p2x7KO) carrying homozygous P2X7 knockout alleles. B6/lpr-p2x7KO mice accumulated high numbers of FasL-expressing B220⁺ DN T cells of CD45RB^highCD44^high effector/memory CD8⁺ T-cell origin and developed severe lupus, characterized by leukocyte infiltration into the tissues, high levels of IgG anti-dsDNA and rheumatoid factor autoantibodies, and marked cytokine network dysregulation. B6/lpr-p2x7KO mice also exhibited a considerably reduced lifespan. P2X7 is therefore a novel regulator of T-cell homeostasis, of which cooperation with Fas is critical to prevent lymphoaccumulation and autoimmunity.

Lactobacillus spp. act in synergy to attenuate splenomegaly and lymphadenopathy in lupus-prone MRL/lpr mice

Commensal bacteria and the immune system have a close and strong relationship that maintains a balance to control inflammation. Alterations of the microbiota, known as dysbiosis, can direct reactivity to self-antigens not only in the intestinal mucosa but also at the systemic level. Our laboratory previously reported gut dysbiosis, particularly lower abundance of bacteria in the family Lactobacillaceae, in lupus-prone MRL/lpr mice, a model of systemic autoimmunity. Restoring the microbiota with a mix of 5 different Lactobacillus species (spp.), L. reuteri, L. oris, L. johnsonii, L. gasseri and L. rhamnosus, attenuated lupus-liked clinical signs, including splenomegaly and lymphadenopathy. However, our understanding of the mechanism was limited. In this study, we first investigated the effects of individual species. Surprisingly, none of the species individually recapitulated the benefits of the mix. Instead, Lactobacillus spp. acted synergistically to attenuate splenomegaly and renal lymphadenopathy through secreted factors and a CX3CR1-dependent mechanism. Interestingly, oral administration of MRS broth exerted the same benefits likely through increasing the relative abundance of endogenous Lactobacillus spp. Mechanistically, we found increased percentages of FOXP3-negative type 1 regulatory T cells with administration of the mix in both spleen and mesenteric lymph nodes. In addition, oral gavage of Lactobacillus spp. decreased the percentage of central memory T cells while increasing that of effector memory T cells in the lymphoid organs. Furthermore, a decreased percentage of double negative T cells was observed in the spleen with the mix. These results suggest that Lactobacillus spp. might act on T cells to attenuate splenomegaly and lymphadenopathy. Together, this study advances our understanding of how Lactobacillus spp. attenuate lupus in MRL/lpr mice. The synergistic action of these bacteria suggests that multiple probiotic bacteria in combination may dampen systemic autoimmunity and benefit lupus patients.

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.

Autoantibodies in systemic lupus erythematosus: From immunopathology to therapeutic target

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organ inflammatory damage and wide spectrum of autoantibodies. The autoantibodies, especially anti-dsDNA and anti-Sm autoantibodies are highly specific to SLE, and participate in the immune complex formation and inflammatory damage on multiple end-organs such as kidney, skin, and central nervous system (CNS). However, the underlying mechanisms of autoantibody-induced tissue damage and systemic inflammation are still not fully understood. Single cell analysis of autoreactive B cells and monoclonal antibody screening from patients with active SLE has improved our understanding on the origin of autoreactive B cells and the antigen targets of the pathogenic autoantibodies. B cell depletion therapies have been widely studied in the clinics, but the development of more specific therapies against the pathogenic B cell subset and autoantibodies with improved efficacy and safety still remain a big challenge. A more comprehensive autoantibody profiling combined with functional characterization of autoantibodies in diseases development will shed new insights on the etiology and pathogenesis of SLE and guide a specific treatment to individual SLE patients.

TLR7 Activation Accelerates Cardiovascular Pathology in a Mouse Model of Lupus

We report a novel model of lupus-associated cardiovascular pathology accelerated by the TLR7 agonist R848 in lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice. R848-treated TC mice but not non-autoimmune C57BL/6 (B6) controls developed microvascular inflammation and myocytolysis with intracellular vacuolization. This histopathology was similar to antibody-mediated rejection after heart transplant, although it did not involve complement. The TC or B6 recipients of serum or splenocytes from R848-treated TC mice developed a reactive cardiomyocyte hypertrophy, which also presents spontaneously in old TC mice as well as in TC.Rag-/- mice that lack B and T cells. Each of these cardiovascular lesions correspond to abnormalities that have been reported in lupus patients. Lymphoid and non-lymphoid immune cells as well as soluble factors contribute to lupus-associated cardiovascular lesions in TC mice, which can now be dissected using this model with and without R848 treatment.

Specific in situ inflammatory states associate with progression to renal failure in lupus nephritis

BACKGROUNDIn human lupus nephritis (LN), tubulointerstitial inflammation (TII) on biopsy predicts progression to end-stage renal disease (ESRD). However, only about half of patients with moderate-to-severe TII develop ESRD. We hypothesized that this heterogeneity in outcome reflects different underlying inflammatory states. Therefore, we interrogated renal biopsies from LN longitudinal and cross-sectional cohorts.METHODSData were acquired using conventional and highly multiplexed confocal microscopy. To accurately segment cells across whole biopsies, and to understand their spatial relationships, we developed computational pipelines by training and implementing several deep-learning models and other computer vision techniques.RESULTSHigh B cell densities were associated with protection from ESRD. In contrast, high densities of CD8+, γδ, and other CD4-CD8- T cells were associated with both acute renal failure and progression to ESRD. B cells were often organized into large periglomerular neighborhoods with Tfh cells, while CD4- T cells formed small neighborhoods in the tubulointerstitium, with frequency that predicted progression to ESRD.CONCLUSIONThese data reveal that specific in situ inflammatory states are associated with refractory and progressive renal disease.FUNDINGThis study was funded by the NIH Autoimmunity Centers of Excellence (AI082724), Department of Defense (LRI180083), Alliance for Lupus Research, and NIH awards (S10-OD025081, S10-RR021039, and P30-CA14599).

Lymphocytes in the neighborhood: good or bad for the kidney?

Lupus nephritis (LN) is common in people with systemic lupus erythematosus (SLE) and advances, almost invariably, to end-stage renal disease (ESRD). In this issue of the JCI, Abraham, Durkee, et al. presented a large-scale immune cell landscape of kidney biopsies from patients with LN by combining multiplexed confocal microscopy imaging with customized computer vision and quantification. The presence of diverse CD4^– T cells in small neighborhoods, but not of B cells or CD4⁺ T cells in large neighborhoods, is linked to the development of ESRD. Unexpectedly, B cells in the kidney heralded a good prognosis. The precise location of different types of immune cells allows inference on possible interactions between different immune cells and also between immune and kidney-resident cells. The data have important implications on the development of prognostic tools and effective targeted therapies in patients with LN.

A Tissue-Tended Mycophenolate-Modified Nanoparticle Alleviates Systemic Lupus Erythematosus in MRL/Lpr Mouse Model Mainly by Promoting Local M2-Like Macrophagocytes Polarization

Background

Mycophenolate mofetil (MMF), for which the bioactive metabolite is mycophenolic acid (MPA), is a frequently used immunosuppressant for systemic lupus erythematosus (SLE). However, its short half-life and poor biodistribution into cells and tissues hinder its clinical efficacy. Our dextran mycophenolate-based nanoparticles (MPA@Dex-MPA NPs) have greatly improved the pharmacokinetics of MMF/MPA. We here tested the therapeutic efficacy of MPA@Dex-MPA NPs against SLE and investigated the underlying mechanism.

Methods

The tissue and immune cell biodistributions of MPA@Dex-MPA NPs were traced using live fluorescence imaging system and flow cytometry, respectively. Serological proinflammatory mediators and kidney damage were detected to assess the efficacy of MPA@Dex-MPA NPs treatments of MRL/lpr lupus-prone mice. Immune cell changes in the kidney and spleen were further analyzed post-treatment via flow cytometry. Bone marrow-derived macrophages were used to investigate the potential mechanism.

Results

MPA@Dex-MPA NPs exhibited superior therapeutic efficacy and safety in the MRL/lpr mice using significantly lower administration dosage (one-fifth) and frequency (once/3 days) compared to MMF/MPA used in ordinary practice. The overall prognosis of the mice was improved as they showed lower levels of serological proinflammatory mediators. Moreover, kidney injury was alleviated with reduced pathological signs and decreased urine protein-creatinine ratio. Further investigations of the underlying mechanism revealed a preferential penetration and persistent retention of MPA@Dex-MPA NPs in the spleen and kidney, where they were mostly phagocytosed by macrophages. The macrophages were found to be polarized towards a CD206⁺ M2-like phenotype, with a downregulation of surface CD80 and CD40, and reduced TNF-α production in the spleen and kidney and in vitro. The expansion of T cells was also significantly inhibited in these two organs.

Conclusion

Our research improved the efficacy of MPA for MRL/lpr mice through synthesizing MPA@Dex-MPA NPs to enhance its tissue biodistribution and explored the possible mechanism, providing a promising strategy for SLE therapy.

Helios Expression Is Downregulated on CD8+ Treg in Two Mouse Models of Lupus During Disease Progression

T-cell–mediated autoimmunity reflects an imbalance in this compartment that is not restored by tolerogenic immune cells, e.g., regulatory T cells or tolerogenic dendritic cells (tolDCs). Although studies into T-cell equilibrium have mainly focused on regulatory CD4⁺FoxP3⁺ T cells (CD4⁺ Tregs), recent findings on the lesser known CD8⁺ Tregs (CD44⁺CD122⁺Ly49⁺) have highlighted their non-redundant role in regulating lupus-like disease and their regulatory phenotype facilitated by the transcription factor Helios in mice and humans. However, there are still remaining questions about Helios regulation and dynamics in different autoimmune contexts. Here, we show the absence of CD8⁺ Tregs in two lupus-prone murine models: MRL/MPJ and MRL/lpr, in comparison with a non-prone mouse strain like C57BL/6. We observed that all MRL animals showed a dramatically reduced population of CD8⁺ Tregs and a greater Helios downregulation on diseased mice. Helios induction was detected preferentially on CD8⁺ T cells from OT-I mice co-cultured with tolDCs from C57BL/6 but not in MRL animals. Furthermore, the Helios profile was also altered in other relevant T-cell populations implicated in lupus, such as CD4⁺ Tregs, conventional CD4⁺, and double-negative T cells. Together, these findings could make Helios a versatile maker across the T-cell repertoire that is capable of differentiating lupus disease states.

EGR2 Deletion Suppresses Anti-DsDNA Autoantibody and IL-17 Production in Autoimmune-Prone B6/lpr Mice: A Differential Immune Regulatory Role of EGR2 in B6/lpr Versus Normal B6 Mice

Previous studies have reported that deletion of the transcription factor, early growth response protein 2 (EGR2), in normal C57BL/6 (B6) resulted in the development of lupus-like autoimmune disease. However, increased EGR2 expression has been noted in human and murine lupus, which challenges the notion of the autoimmune suppressive role of EGR2 in B6 mice. In this study, we derived both conditional EGR2^-/-B6/lpr and EGR2^-/-B6 mice to elucidate the immune and autoimmune regulatory roles of EGR2 in autoinflammation (B6/lpr) versus physiologically normal (B6) conditions. We found that conditional EGR2 deletion increased spleen weight, enhanced T cell activation and IFNγ production, and promoted germinal center B cells and LAG3⁺ regulatory T cells development in both B6/lpr and B6 mice. Nevertheless, EGR2 deletion also showed strikingly differential effects in these two strains on T lymphocyte subsets profile, Foxp3⁺ Tregs and plasma cell differentiation, anti-dsDNA autoantibodies and immunoglobulins production, and on the induction of IL-17 in in vitro activated splenocytes. Specifically, EGR2 deletion in B6/lpr mice significantly decreased serum levels of anti-dsDNA autoantibodies, total IgG, IgM, IgG1, and IgG2a with reduced plasma cells differentiation. Furthermore, EGR2 deletion in B6/lpr mice had no obvious effect on IgG immunocomplex deposition, medium caliber vessel, and glomeruli inflammation but increased complement C3 immunocomplex deposition and large caliber vessel inflammation in the kidneys. Importantly, we demonstrated that EGR2 deletion in B6/lpr mice significantly reduced pathogenic CD4^-CD8^-CD3⁺B220⁺ double negative T cells, which correlated with the reduced anti-dsDNA autoantibodies in serum and decreased IL-17 production in splenocytes of EGR2^-/-B6/lpr mice. Together, our data strongly suggest that the role of EGR2 is complex. The immunoregulatory role of EGR2 varies at normal or autoinflammation conditions and should not be generalized in differential experimental settings.

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.

Novel immunoprofiling method for diagnosing SLE and evaluating therapeutic response

Objective

Diagnosis of SLE is based on clinical manifestations but is heterogeneous in early onset. Hence, we aimed to evaluate the feature of the immunoprofiling in patients with SLE and apply it to develop an immune signature algorithm for supporting SLE diagnosis.

Methods

We enrolled 13 newly diagnosed patients with SLE and 9 healthy controls (HCs) followed by analysing their immunoprofilings within their peripheral blood mononuclear cells (PBMCs) through flow cytometry. The immunoprofiling from the patients with SLE and HCs were ranked and formed an immune signature score. Besides, we enrolled four patients with SLE and monitored the changes in their immunoprofilings after immunosuppressant treatment.

Results

Among 93 immune cell subsets, 29 differed significantly between patients with SLE and HCs, and lower dendritic and natural killer cell percentages and a higher CD8⁺ T-cell percentage were identified in patients with SLE. In an investigation of immune-tolerant-related cell subsets, higher concentrations of CD8⁺ regulatory natural killer T cells, programmed cell death 1 (PD-1)⁺ T cells, and lower concentrations of programmed cell death ligand 1 (PD-L1)⁺ PBMCs were observed in the SLE group. The immune signature score from patients with SLE was significantly different from that from the HCs. After treatment, the disease activity of the four patients were tended to stable and percentages of PD-L1⁺ monocytes, PD-1⁺ CD4 T and CD8 T cells in patients with SLE exhibited positively and negatively correlation with the SLEDAI-2K (Systemic Lupus Erythematosus Disease Activity Index 2000) score, which might associate with the remission of SLE.

Conclusions

The comparison of immunprofiling between patients with SLE and HCs exhibited a distinct pattern. This difference and its application to immune signature algorithm shed light on the studies of SLE pathogenesis and immune-based diagnostic tool development in the future.

A Mechanistic Insight into the Pathogenic Role of Interleukin 17A in Systemic Autoimmune Diseases

Interleukin 17A (IL-17A) has been put forward as a strong ally in our fight against invading pathogens across exposed epithelial surfaces by serving an antimicrobial immunosurveillance role in these tissues to protect the barrier integrity. Amongst other mechanisms that prevent tissue injury mediated by potential microbial threats and promote restoration of epithelial homeostasis, IL-17A attracts effector cells to the site of inflammation and support the host response by driving the development of ectopic lymphoid structures. Accumulating evidence now underscores an integral role of IL-17A in driving the pathophysiology and clinical manifestations in three potentially life-threatening autoimmune diseases, namely, systemic lupus erythematosus, Sjögren’s syndrome, and systemic sclerosis. Available studies provide convincing evidence that the abundance of IL-17A in target tissues and its prime source, which is T helper 17 cells (Th17) and double negative T cells (DNT), is not an innocent bystander but in fact seems to be prerequisite for organ pathology. In this regard, IL-17A has been directly implicated in critical steps of autoimmunity. This review reports on the synergistic interactions of IL-17A with other critical determinants such as B cells, neutrophils, stromal cells, and the vasculature that promote the characteristic immunopathology of these autoimmune diseases. The summary of observations provided by this review may have empowering implications for IL-17A-based strategies to prevent clinical manifestations in a broad spectrum of autoimmune conditions.

CD3+CD4-CD8- (Double-Negative) T Cells in Inflammation, Immune Disorders and Cancer

The crucial role of CD4⁺ and CD8⁺ T cells in shaping and controlling immune responses during immune disease and cancer development has been well established and used to achieve marked clinical benefits. CD3⁺CD4^-CD8^- double-negative (DN) T cells, although constituting a rare subset of peripheral T cells, are gaining interest for their roles in inflammation, immune disease and cancer. Herein, we comprehensively review the origin, distribution and functions of this unique T cell subgroup. First, we focused on characterizing multifunctional DN T cells in various immune responses. DN regulatory T cells have the capacity to prevent graft-versus-host disease and have therapeutic value for autoimmune disease. T helper-like DN T cells protect against or promote inflammation and virus infection depending on the specific settings and promote certain autoimmune disease. Notably, we clarified the role of DN tumor-infiltrating lymphocytes and outlined the potential for malignant proliferation of DN T cells. Finally, we reviewed the recent advances in the applications of DN T cell-based therapy for cancer. In conclusion, a better understanding of the heterogeneity and functions of DN T cells may help to develop DN T cells as a potential therapeutic tool for inflammation, immune disorders and cancer.

Double-negative T cells: Setting the stage for disease control or progression

Double-negative (DN) T cells are present at relatively low frequencies in human peripheral blood, and are characterized as expressing the alpha-beta or gamma-delta T-cell receptor (TCR), but not the CD4 nor the CD8 co-receptors. Despite their low frequencies, these cells are potent producers of cytokines and, thus, are key orchestrators of immune responses. DN T cells were initially associated with induction of peripheral immunological tolerance and immunomodulatory activities related to disease prevention. However, other studies demonstrated that these cells can also display effector functions associated with pathology development. This apparent contradiction highlighted the heterogeneity of the DN T-cell population. Here, we review phenotypic and functional characteristics of DN T cells, emphasizing their role in human diseases. The need for developing biomarkers to facilitate the translation of studies from animal models to humans will also be discussed. Finally, we will examine DN T cells as promising therapeutic targets to prevent or inhibit human disease development.

The Critical and Diverse Roles of CD4-CD8- Double Negative T Cells in Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

Hepatic inflammation is a hallmark of nonalcoholic fatty liver disease (NAFLD). Double negative T (DNT) cells are a unique subset of T lymphocytes that do not express CD4, CD8, or natural killer cell markers, and studies have suggested that DNT cells play critical and diverse roles in the immune system. However, the role of intrahepatic DNT cells in NAFLD is largely unknown.

METHODS

The proportions and RNA transcription profiling of intrahepatic DNT cells were compared between C57BL/6 mice fed with control diet or methionine-choline-deficient diet for 5 weeks. The functions of DNT cells were tested in vitro and in vivo.

RESULTS

The proportion of intrahepatic DNT cells was significantly increased in mice with diet-induced NAFLD. In NAFLD mice, the proportion of intrahepatic TCRγδ⁺ DNT cells was increased along with elevated interleukin (IL) 17A; in contrast, the percentage of TCRαβ⁺ DNT cells was decreased, accompanied by reduced granzyme B (GZMB). TCRγδ⁺ DNT cell depletion resulted in lowered liver IL17A levels and significantly alleviated NAFLD. Adoptive transfer of intrahepatic TCRαβ⁺ DNT cells from control mice increased intrahepatic CD4 and CD8 T cell apoptosis and inhibited NAFLD progression. Furthermore, we revealed that adrenic acid and arachidonic acid, harmful fatty acids that were enriched in the liver of the mice with NAFLD, could induce apoptosis of TCRαβ⁺ DNT cells and inhibit their immunosuppressive function and nuclear factor kappa B (NF-κB) or AKT signaling pathway activity. However, arachidonic acid facilitated IL17A secretion by TCRγδ⁺ DNT cells, and the NF-κB signaling pathway was involved. Finally, we also confirmed the variation of intrahepatic TCRαβ⁺ DNT cells and TCRγδ⁺ DNT cells in humans.

CONCLUSIONS

During NAFLD progression, TCRγδ⁺ DNT cells enhance IL17A secretion and aggravate liver inflammation, whereas TCRαβ⁺ DNT cells decrease GZMB production and lead to weakened immunoregulatory function. Shifting of balance from TCRγδ⁺ DNT cell response to one that favors TCRαβ⁺ DNT regulation would be beneficial for the prevention and treatment of NAFLD.