Notch1 hyperactivity drives ubiquitination of NOX2 and dysfunction of CD8+ regulatory T cells in patients with systemic lupus erythematosus.

OBJECTIVES: Patients with systemic lupus erythematosus (SLE) display heightened immune activation and elevated IgG autoantibody levels, indicating compromised regulatory T cell (Tregs) function. Our recent findings pinpoint CD8+ Tregs as crucial regulators within secondary lymphoid organs, operating in a NOX2-dependent mechanism. However, the specific involvement of CD8+ Tregs in SLE pathogenesis and the mechanisms underlying their role remain uncertain. METHODS: SLE and healthy individuals were enlisted to assess the quantity and efficacy of Tregs. CD8+CD45RA+CCR7+ Tregs were generated ex vivo, and their suppressive capability was gauged by measuring pZAP70 levels in targeted T cells. Notch1 activity was evaluated by examining activated Notch1 and HES1, with manipulation of Notch1 accomplished with Notch inhibitor DAPT, Notch1 shRNA, and Notch1-ICD. To create humanized SLE chimeras, immune-deficient NSG mice were engrafted with PBMCs from SLE patients. RESULTS: We observed a reduced frequency and impaired functionality of CD8+ Tregs in SLE patients. There was a downregulation of NOX2 in CD8+ Tregs from SLE patients, leading to a dysfunction. Mechanistically, the reduction of NOX2 in SLE CD8+ Tregs occurred at a post-translational level rather than at the transcriptional level. SLE CD8+ Tregs exhibited heightened Notch1 activity, resulting in increased expression of STUB1, an E3 ubiquitin ligase that binds to NOX2 and facilitates its ubiquitination. Consequently, restoring NOX2 levels and inhibiting Notch1 activity could alleviate the severity of the disease in humanized SLE chimeras. CONCLUSION: Notch1 is the cell-intrinsic mechanism underlying NOX2 deficiency and CD8+ Treg dysfunction, serving as a therapeutic target for clinical management of SLE.

Tumor-secreted FGF21 acts as an immune suppressor by rewiring cholesterol metabolism of CD8+T cells.

Tumors employ diverse strategies for immune evasion. Unraveling the mechanisms by which tumors suppress anti-tumor immunity facilitates the development of immunotherapies. Here, we have identified tumor-secreted fibroblast growth factor 21 (FGF21) as a pivotal immune suppressor. FGF21 is upregulated in multiple types of tumors and promotes tumor progression. Tumor-secreted FGF21 significantly disrupts anti-tumor immunity by rewiring cholesterol metabolism of CD8+T cells. Mechanistically, FGF21 sustains the hyperactivation of AKT-mTORC1-sterol regulatory-element-binding protein 1 (SREBP1) signal axis in the activated CD8+T cells, resulting in the augment of cholesterol biosynthesis and T cell exhaustion. FGF21 knockdown or blockade using a neutralizing antibody normalizes AKT-mTORC1 signaling and reduces excessive cholesterol accumulation in CD8+T cells, thus restoring CD8+T cytotoxic function and robustly suppressing tumor growth. Our findings reveal FGF21 as a "secreted immune checkpoint" that hampers anti-tumor immunity, suggesting that inhibiting FGF21 could be a valuable strategy to enhance the cancer immunotherapy efficacy.

Cancer CD39 drives metabolic adaption and mal-differentiation of CD4+ T cells in patients with non-small-cell lung cancer.

While ectonucleotidase CD39 is a cancer therapeutic target in clinical trials, its direct effect on T-cell differentiation in human non-small-cell lung cancer (NSCLC) remains unclear. Herein, we demonstrate that human NSCLC cells, including tumor cell lines and primary tumor cells from clinical patients, efficiently drive the metabolic adaption of human CD4+ T cells, instructing differentiation of regulatory T cells while inhibiting effector T cells. Of importance, NSCLC-induced T-cell mal-differentiation primarily depends on cancer CD39, as this can be fundamentally blocked by genetic depletion of CD39 in NSCLC. Mechanistically, NSCLC cells package CD39 into their exosomes and transfer such CD39-containing exosomes into interacting T cells, resulting in ATP insufficiency and AMPK hyperactivation. Such CD39-dependent NSCLC-T cell interaction holds well in patients-derived primary tumor cells and patient-derived organoids (PDOs). Accordingly, genetic depletion of CD39 alone or in combination with the anti-PD-1 immunotherapy efficiently rescues effector T cell differentiation, instigates anti-tumor T cell immunity, and inhibits tumor growth of PDOs. Together, targeting cancer CD39 can correct the mal-differentiation of CD4+ T cells in human NSCLC, providing in-depth insight into therapeutic CD39 inhibitors.

Myocardial Mitochondrial DNA Drives Macrophage Inflammatory Response through STING Signaling in Coxsackievirus B3-Induced Viral Myocarditis.

Coxsackievirus B3 (CVB3), a single-stranded positive RNA virus, primarily infects cardiac myocytes and is a major causative pathogen for viral myocarditis (VMC), driving cardiac inflammation and organ dysfunction. However, whether and how myocardial damage is involved in CVB3-induced VMC remains unclear. Herein, we demonstrate that the CVB3 infection of cardiac myocytes results in the release of mitochondrial DNA (mtDNA), which functions as an important driver of cardiac macrophage inflammation through the stimulator of interferon genes (STING) dependent mechanism. More specifically, the CVB3 infection of cardiac myocytes promotes the accumulation of extracellular mtDNA. Such myocardial mtDNA is indispensable for CVB3-infected myocytes in that it induces a macrophage inflammatory response. Mechanistically, a CVB3 infection upregulates the expression of the classical DNA sensor STING, which is predominantly localized within cardiac macrophages in VMC murine models. Myocardial mtDNA efficiently triggers STING signaling in those macrophages, resulting in strong NF-kB activation when inducing the inflammatory response. Accordingly, STING-deficient mice are able to resist CVB3-induced cardiac inflammation, exhibiting minimal inflammation with regard to their functional cardiac capacities, and they exhibit higher survival rates. Moreover, our findings pinpoint myocardial mtDNA as a central element driving the cardiac inflammation of CVB3-induced VMC, and we consider the DNA sensor, STING, to be a promising therapeutic target for protecting against RNA viral infections.

Low-dose metronomic chemotherapy triggers oxidized mtDNA sensing inside tumor cells to potentiate CD8+T anti-tumor immunity.

Low-dose metronomic (LDM) chemotherapy, the frequent and continuous use of low doses of conventional chemotherapeutics, is emerging as a promising form of chemotherapy utilization. LDM chemotherapy exerts immunomodulatory effects. However, the underlying mechanism is not fully understood. Here we found that suppressing tumor growth by LDM chemotherapy was dependent on the activation of CD8+T cells. LDM chemotherapy potentiated the cytotoxic function of CD8+T cells by stimulating cancer-cell autonomous type I interferon (IFN) induction. Mechanistically, LDM chemotherapy evoked mitochondrial dysfunction and increased reactive oxygen species (ROS) production. ROS triggered the oxidation of cytosolic mtDNA, which was sensed by cGAS-STING, consequently inducing type I IFN production in the cancer cells. Moreover, the cGAS-STING-IFN axis increased PD-L1 expression and predicted favorable clinical responses to chemoimmunotherapy. Antioxidant N-acetylcysteine inhibited oxidized mtDNA-induced type I IFN production and attenuated the efficacy of combination therapy with LDM chemotherapy and PD-L1 blockade. This study elucidates the critical role of intratumoral oxidized mtDNA sensing in LDM chemotherapy-mediated activation of CD8+T cell immune response. These findings may provide new insights for designing combinatorial immunotherapy for cancer patients.

Akkermansia muciniphila: A potential target and pending issues for oncotherapy.

In the wake of the development of metagenomic, metabolomic, and metatranscriptomic approaches, the intricate interactions between the host and various microbes are now being progressively understood. Numerous studies have demonstrated evident changes in gut microbiota during the process of a variety of diseases, such as diabetes, obesity, aging, and cancers. Notably, gut microbiota is viewed as a potential source of novel therapeutics. Currently, Next-generation probiotics (NGPs) are gaining popularity as therapeutic agents that alter the gut microbiota and affect cancer development. Akkermansia muciniphila (A. muciniphila), a representative commensal bacterium, has received substantial attention over the past decade as a promising NGP. The components and metabolites of A. muciniphila can directly or indirectly affect tumorigenesis, in particular through its effects on antitumor immunosurveillance, including the stimulation of pattern recognition receptors (PRRs), which also leads to better outcomes in a variety of situations, including the prevention and curation of cancers. In this article, we systematically summarize the role of A. muciniphila in tumorigenesis (involving gastrointestinal and non-gastrointestinal cancers) and in tumor therapy. In particular, we carefully discuss some critical scientific issues that need to be solved for the future using A. muciniphila as a representative beneficial bacterium in tumor treatment, which might provide bright clues and assistance for the application of drugs targeting A. muciniphila in clinical oncotherapy.

Activated Lymphocyte-Derived DNA Drives Glucose Metabolic Adaptation for Inducing Macrophage Inflammatory Response in Systemic Lupus Erythematosus.

Activated lymphocyte-derived DNA (ALD-DNA) has been reported to drive the polarization of macrophages toward M2b, producing inflammatory cytokines and inducing inflammation, correspondingly playing an essential role in the development of systemic lupus erythematosus (SLE). Recently, accumulating evidence has pinpointed metabolic adaptation as the crucial cell-intrinsic determinant for inflammatory response, in which glucose metabolism is the key event. However, whether and how glucose metabolism was involved in ALD-DNA-induced macrophage inflammatory response and SLE development remains unclear. Herein, we performed glucose metabolomic analyses of ALD-DNA-stimulated macrophages and uncovered increased glycolysis and diminished pentose phosphate pathway (PPP), as well as enhanced glycogenesis. In ALD-DNA-stimulated macrophages, increased glycolysis resulted in higher lactate production, whereas diminished PPP efficiently led to lower levels of nicotinamide adenine dinucleotide phosphate (NADPH) with higher levels of reactive oxygen species (ROS). While blockade of lactate generation exerted no significant effect on macrophage inflammation in response to ALD-DNA, scavenging ROS fundamentally inhibited the inflammatory response of ALD-DNA-stimulated macrophages. Further, cyclic adenosine monophosphate (cAMP), a master for regulating glycogen metabolism, was downregulated by ALD-DNA in macrophages, which subsequently imbalanced glycogen metabolism toward glycogenesis but not glycogenolysis. Administration of cAMP effectively restored glycogenolysis and enhanced PPP, which correspondingly reduced ROS levels and inhibited the inflammatory response of ALD-DNA-stimulated macrophages. Finally, blocking glucose metabolism using 2-deoxy-D-glucose (2-DG) efficiently restricted macrophage inflammatory response and alleviated ALD-DNA-induced lupus disease. Together, our findings demonstrate that ALD-DNA drives the adaptation of glucose metabolism for inducing macrophage inflammatory response in SLE, which might further our understanding of disease pathogenesis and provide clues for interventive explorations.

Mitochondrial Control for Healthy and Autoimmune T Cells.

T cells are critical players in adaptive immunity, driving the tissue injury and organ damage of patients with autoimmune diseases. Consequently, investigations on T cell activation, differentiation, and function are valuable in uncovering the disease pathogenesis, thus exploring promising therapeutics for autoimmune diseases. In recent decades, accumulating studies have pinpointed immunometabolism as the fundamental determinant in controlling T cell fate. Specifically, mitochondria, as a hub of intracellular metabolism, connect glucose, lipid, and amino acid metabolic pathways. Herein, we summarize metabolic adaptations of mitochondrial oxidative phosphorylation and the relevant glucose, lipid, and amino acid metabolism during T cell activation, differentiation, and function. Further, we focused on current updates of the molecular bases for metabolic reprogramming in autoimmune T cells and advances in exploring metabolic-targeted therapeutics against autoimmune diseases. This might facilitate the in-depth understanding of autoimmune pathogeneses and the clinical management of autoimmune diseases.

MiRNA-Based Therapies for Lung Cancer: Opportunities and Challenges?

Lung cancer is a commonly diagnosed cancer and the leading cause of cancer-related deaths, posing a serious health risk. Despite new advances in immune checkpoint and targeted therapies in recent years, the prognosis for lung cancer patients, especially those in advanced stages, remains poor. MicroRNAs (miRNAs) have been shown to modulate tumor development at multiple levels, and as such, miRNA mimics and molecules aimed at regulating miRNAs have shown promise in preclinical development. More importantly, miRNA-based therapies can also complement conventional chemoradiotherapy, immunotherapy, and targeted therapies to reverse drug resistance and increase the sensitivity of lung cancer cells. Furthermore, small interfering RNA (siRNA) and miRNA-based therapies have entered clinical trials and have shown favorable development prospects. Therefore, in this paper, we review recent advances in miRNA-based therapies in lung cancer treatment as well as adjuvant therapy and present the current state of clinical lung cancer treatment. We also discuss the challenges facing miRNA-based therapies in the clinical application of lung cancer treatment to provide new ideas for the development of novel lung cancer therapies.

Deficient leptin receptor signaling in T cells of human SLE.

Background: Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease mainly mediated by IgG autoantibody. While follicular helper T (Tfh) cells are crucial for supporting IgG autoantibody generation in human SLE, underlying mechanisms for Tfh cell mal-differentiation remain unclear. Methods: In total, 129 SLE patients and 37 healthy donors were recruited for this study. Circulating leptin was determined by ELISA from patients with SLE and healthy individuals. CD4 T cells isolated from SLE patients and healthy donors were activated with anti-CD3/CD28 beads under cytokine-unbiased conditions in the presence or absence of recombinant leptin protein, followed by detection for Tfh cell differentiation by quantifying intracellular transcription factor Bcl-6 and cytokine IL-21. AMPK activation was assessed by analyzing phosphor-AMPK using phosflow cytometry and immunoblots. Leptin receptor expression was determined using flow cytometry and its overexpression was achieved by transfection with an expression vector. Humanized SLE chimeras were induced by injecting patients' immune cells into immune-deficient NSG mice and used for translational studies. Results: Circulating leptin was elevated in patients with SLE, inversely associated with disease activity. In healthy individuals, leptin efficiently inhibited Tfh cell differentiation through inducing AMPK activation. Meanwhile, leptin receptor deficiency was a feature of CD4 T cells in SLE patients, impairing the inhibitory effect of leptin on the differentiation of Tfh cells. As a result, we observed the coexistence of high circulating leptin and increased Tfh cell frequencies in SLE patients. Accordingly, overexpression of leptin receptor in SLE CD4 T cells abrogated Tfh cell mal-differentiation and IgG anti-dsDNA generation in humanized lupus chimeras. Conclusion: Leptin receptor deficiency blocks the inhibitory effect of leptin on SLE Tfh cell differentiation, serving as a promising therapeutic target for lupus management.

Lipogenesis promotes mitochondrial fusion and maintains cancer stemness in human NSCLC.

Cancer stem-like cells (CSCs) are critically involved in cancer metastasis and chemoresistance, acting as one major obstacle in clinical practice. While accumulating studies have implicated the metabolic reprogramming of CSCs, mitochondrial dynamics in such cells remain poorly understood. Here we pinpointed OPA1hi with mitochondrial fusion as a metabolic feature of human lung CSCs, licensing their stem-like properties. Specifically, human lung CSCs exerted enhanced lipogenesis, inducing OPA1 expression via transcription factor SAM Pointed Domain containing ETS transcription Factor (SPDEF). In consequence, OPA1hi promoted mitochondrial fusion and stemness of CSCs. Such lipogenesishi, SPDEFhi, and OPA1hi metabolic adaptions were verified with primary CSCs from lung cancer patients. Accordingly, blocking lipogenesis and mitochondrial fusion efficiently impeded CSC expansion and growth of organoids derived from patients with lung cancer. Together, lipogenesis regulates mitochondrial dynamics via OPA1 for controlling CSCs in human lung cancer.

AMPK hyperactivity maintains the survival of vasculogenic T cells in patients with Takayasu's arteritis.

OBJECTIVES: Takayasu's arteritis (TAK) is a progressive autoimmune vasculitis that mainly affects the aorta and its major branches. While recent studies have identified proinflammatory T cells, including Th1 and Th17 cells, as the dominant infiltrates in the arterial adventitia, mechanisms underpinning the maintenance of such vasculogenic T cells remain obscure. METHODS: 75 patients with TAK and 30 age-matched healthy controls were enrolled in this study. CD4 T cells from TAK patients were activated with anti-CD3/CD28 beads to mimic vasculogenic T cells. The survival of T cells was detected by quantifying Annexin-V+7-AAD+ fractions. Expression and activity of AMP-activated protein kinase (AMPK) were determined using phosflow cytometry and immunoblots. Specific inhibitors and shRNA were applied to block the function of AMPK and Notch1, while erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were used to reflect the disease activity of TAK patients. RESULTS: T cells from TAK patients undergo spontaneous differentiation into vasculogenic proinflammatory T cells with prolonged survival capacity. Mechanistic explorations uncover AMPK hyperactivity in such T cells from TAK patients, promoting mitochondrial metabolism and their survival. Such AMPK hyperactivity results from the robust Notch1 activity in TAK T cells. Accordingly, T cell-intrinsic phosphor-AMPK reflects the disease activity in clinical TAK patients. CONCLUSIONS: AMPK hyperactivity is essential for maintaining the vasculogenic proinflammatory T cells in TAK patients, serving as a promising therapeutic target for TAK management.

TCR repertoire landscape reveals macrophage-mediated clone deletion in endotoxin tolerance.

BACKGROUND: Endotoxin tolerance (ET) is a protective mechanism in the process of sepsis, septic shock, and their sequelae including uncontrolled inflammation. Accumulating evidence has shown that peripheral T cells contribute to the induction of ET. However, what and how T-cell development contributes to ET inductions remain unclear. METHODS: Mice were intraperitoneally injected with LPS at a concentration of 5 mg/kg to establish an LPS tolerance model and were divided into two groups: a group examined 72 h after LPS injection (72-h group) and a group examined 8 days after LPS injection (8-day group). Injection of PBS was used as a control. We performed high-throughput sequencing to analyze the characteristics and changes of CD4+SP TCRß CDR3 repertoires with respect to V direct to J rearrangement during the ET induction. Moreover, the proportion and proliferation, as well as surface molecules such as CD80 and CD86, of F4/80+ macrophages were analyzed using FCM. Furthermore, ACT assay was designed and administered by the tail vein into murine LPS-induced mouse model to evaluate the role of F4/80+ macrophages on the development of CD4+SP thymocytes in ET condition. RESULTS: We found that the frequency and characteristics of the TCRß chain CDR3 changed obviously under condition of ET, indicating the occurrence of TCR rearrangement and thymocyte diversification. Moreover, the absolute numbers of F4/80+ macrophages, but not other APCs, were increased in thymic medulla at 72-h group, accompanied by the elevated function-related molecules of F4/80+ macrophages. Furthermore, adoptively transferred OVA332-339 peptide-loaded macrophages into Rag-1-/- mice induced the clone deletion of OVA-specific CD4+SP, thereby ameliorating the pathology in lung tissue in LPS challenge. CONCLUSIONS: These data reveal that the frequency and characteristics of the TCRß chain CDR3 undergo dynamic programming under conditions of LPS tolerance. Furthermore, the peripheral macrophages may be a key factor which carry peripheral antigen to thymic medulla and affect the negative selection of T-cell population, thereby contributing to the formation of ET. These results suggest that the clone selection in thymus in ET may confer protection against microbial sepsis.

Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells.

While previous studies have identified cancer stem-like cells (CSCs) as a crucial driver for chemoresistance and tumor recurrence, the underlying mechanisms for populating the CSC pool remain unclear. Here, we identify hypermitophagy as a feature of human lung CSCs, promoting metabolic adaption via the Notch1-AMPK axis to drive CSC expansion. Specifically, mitophagy is highly active in CSCs, resulting in increased mitochondrial DNA (mtDNA) content in the lysosome. Lysosomal mtDNA acts as an endogenous ligand for Toll-like receptor 9 (TLR9) that promotes Notch1 activity. Notch1 interacts with AMPK to drive lysosomal AMPK activation by inducing metabolic stress and LKB1 phosphorylation. This TLR9-Notch1-AMPK axis supports mitochondrial metabolism to fuel CSC expansion. In patient-derived xenograft chimeras, targeting mitophagy and TLR9-dependent Notch1-AMPK pathway restricts tumor growth and CSC expansion. Taken together, mitochondrial hemostasis is interlinked with innate immune sensing and Notch1-AMPK activity to increase the CSC pool of human lung cancer.

Critical Role of Notch-1 in Mechanistic Target of Rapamycin Hyperactivity and Vascular Inflammation in Patients With Takayasu Arteritis.

OBJECTIVE: Takayasu arteritis (TA) is a major type of large vessel vasculitis characterized by progressive inflammation in vascular layers. In our recent study we identified a central role of mechanistic target of rapamycin (mTOR) hyperactivity in proinflammatory T cell differentiation in TA. This study was undertaken to explore potential mechanisms underpinning T cell-intrinsic mTOR hyperactivity and vascular inflammation in TA, with a focus on Notch-1. METHODS: Notch-1 expression and activity was determined according to Notch-1, activated Notch-1, and HES-1 levels. We detected mTOR activity with intracellular expression of phosphorylated ribosomal protein S6. Differentiation of proinflammatory T cells was analyzed by detecting Th1 and Th17 lineage-determining transcription factors. The function of Notch-1 was evaluated using γ-secretase inhibitor DAPT and gene knockdown using a short hairpin RNA (shRNA) strategy. We performed our translational study using humanized NSG mouse chimeras in which human vasculitis was induced using immune cells from TA patients. RESULTS: CD4+ T cells from TA patients exerted Notch-1high , leading to mTOR hyperactivity and spontaneous maldifferentiation of Th1 cells and Th17 cells. Blockade of Notch-1 using DAPT and Notch-1 shRNA efficiently abrogated mTOR complex 1 (mTORC1) activation and proinflammatory T cell differentiation. Mechanistically, Notch-1 promoted mTOR expression, interacted with mTOR, and was associated with lysosomal localization of mTOR. Accordingly, systemic administration of DAPT and CD4+ T cell-specific gene knockdown of Notch-1 could alleviate vascular inflammation in humanized TA chimeras. CONCLUSION: Expression of Notch-1 is elevated in CD4+ T cells from TA patients, resulting in mTORC1 hyperactivity and proinflammatory T cell differentiation. Targeting Notch-1 is a promising therapeutic strategy for the clinical management of TA.

Mesangial cell: A hub in lupus nephritis.

Lupus nephritis (LN) is a severe renal disease caused by the massive deposition of the immune complexes (ICs) in renal tissue, acting as one of the significant organ manifestations of systemic lupus erythematosus (SLE) and a substantial cause of death in clinical patients. As mesangium is one of the primary sites for IC deposition, mesangial cells (MCs) constantly undergo severe damage, resulting in excessive proliferation and increased extracellular matrix (ECM) production. In addition to playing a role in organizational structure, MCs are closely related to in situ immunomodulation by phagocytosis, antigen-presenting function, and inflammatory effects, aberrantly participating in the tissue-resident immune responses and leading to immune-mediated renal lesions. Notably, such renal-resident immune responses drive a second wave of MC damage, accelerating the development of LN. This review summarized the damage mechanisms and the in situ immune regulation of MCs in LN, facilitating the current drug research for exploring clinical treatment strategies.

Retinoic Acid Receptor-Related Orphan Nuclear Receptor γt Licenses the Differentiation and Function of a Unique Subset of Follicular Helper T Cells in Response to Immunogenic Self-DNA in Systemic Lupus Erythematosus.

OBJECTIVE: Accumulating studies have identified self-DNA as driving IgG anti-double-stranded DNA (anti-dsDNA) in lupus, though the underpinning mechanisms of this process remain largely undefined. Here, we explored the activity of transcription factor retinoic acid receptor-related orphan nuclear receptor γt (RORγt) in the differentiation and function of self-DNA-specific follicular helper T (Tfh) cells in lupus. METHODS: B6, TCRα-/- , CD4-/- , RORγtfl/fl CD4Cre, RORγt+/+ CD4Cre, Bcl-6fl/fl CD4Cre, Bcl-6+/+ CD4Cre, IL-17-/- , and ICOS-/- mice were immunized with normal self-DNA, immunogenic self-DNA, and pathogen DNA to induce the production of Tfh cells and IgG anti-dsDNA. Tfh cells with or without interleukin-17 (IL-17) were evaluated for their role in supporting the generation of IgG. NSG mice were reconstituted with immune cells and circulating DNA from human subjects for translational studies. IL-17-positive Tfh cells were analyzed for their correlation with IgG anti-dsDNA levels as well as their response to circulating self-DNA in lupus patients. RESULTS: Unlike normal self-DNA, immunogenic self-DNA and pathogen DNA efficiently induced IgG responses. Immunogenic self-DNA induced IgG in a CD4+ T cell-dependent manner, which was abrogated by RORγt deficiency. In contrast, RORγt was not required for the generation of pathogen DNA-induced IgG. Further analyses identified RORγt as essential for the differentiation and function of Tfh cells in response to immunogenic self-DNA, assigning IL-17 as a feature cytokine. These IL-17-positive Tfh cells functioned independent of inducible costimulator (ICOS), critically supporting IgG generation. Targeting immunogenic self-DNA-specific Tfh cells by RORγ knockdown and IL-17 blockade ameliorated IgG response and lupus nephritis in a humanized mouse model. The presence of IL-17-positive Tfh cells was associated with IgG anti-dsDNA levels and were expanded by circulating immunogenic self-DNA in lupus patients. CONCLUSION: Immunogenic self-DNA instructs ICOS-dispensable IL-17-positive Tfh cells via RORγt to produce an IgG anti-dsDNA response. As such, IL-17-positive Tfh cells are a promising therapeutic target for lupus patients.