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Activated CD8 + T cells directly kill target cells. Therefore, the regulation of their function is central to avoiding immunopathology. Mechanisms that curb effector functions in CD4 + and CD8 + T cells are mostly shared, yet important differences occur. Here, we focus on the control of CD8 + T cell activity and discuss the importance of a poorly understood aspect of tolerance that directly impairs engagement of target cells: the downregulation of CD8. We contextualize this process and propose that it represents a key element during CD8 + T cell modulation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Our previous study found that double negative T cells (DNTs) could promote the NLRP3 activation through high expression of TNF-α, thereby leading to hepatic fibrosis progression. We focused on investigating the role and mechanism of DNTs in regulating the Th9 cells differentiation in liver fibrosis. In our results, among patients with liver fibrosis, the proportions of peripheral blood DNTs and Th9 cells were up-regulated and positively correlated. While promoting the progression of liver fibrosis in mice, DNTs could elevate the proportion of Th9 cells and activate the TNFR2-STAT5-NF-κB pathway. The use of IL-9 and TNF-α monoclonal antibodies (mAbs) inhibited the effect of DNTs and lowered the proportion of Th9 cells in tissues. In vitro experiments showed that DNTs could promote the Th9 cells differentiation of Naive T cells, while TNF-α mAbs could inhibit such effect of DNTs to lower the proportion of Th9 cells. We found that DNTs can activate TNFR2-STAT5-NF-κB pathway by secreting TNF-α, thereby promoting the Th9 Cells differentiation to facilitate the progression of liver fibrosis. There is interaction between DNTs and Th9 cells., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dai, Wang, Heid, Eden, Reilly and Ahmed.)

The double negative T cell (DNT) is a unique subset of T cells with potent anti-leukemic potential. Previously, DNT therapy has been shown to effectively target AML cells in patient-derived xenograft (PDX) models. Further, a recently completed phase I/IIa clinical study demonstrated the safety, feasibility, and potential efficacy in AML patients that relapsed after allogeneic hematopoietic stem cell transplantation. However, the persistence and durability of DNT-mediated anti-leukemic response is less well understood. In this study, we characterized the in vivo persistence of DNTs in PDX models. Further, we improved the efficacy and durability of DNT-mediated activity with phosphoinositide 3-kinase delta (PI3Kδ) inhibition. Mechanistically, DNTs treated with the PI3Kδ inhibitor, Idelalisib (Ide), exhibited early memory phenotype with superior viability and proliferative capacity but less cell exhaustion. Collectively, the findings from this study support the use of Ide-treated DNTs to improve its therapeutic outcome.

This study was intended to delineate the profile of double-negative T cells (DNTs) in NOD.Cg-Prkdc scid Il2rg tm1wj /SzJ mice and cytokines released from DNTs in vivo and in vitro. Total 4 × 10 7 cells of RC1012 injection per mice were intravenously infused. IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-6, IL-10 were measured in vivo and in vitro. A quantitative polymerase chain reaction (PCR) was employed to determine the gene copies of Notch2-NLA per DNT cell from collected organs. Cytokines were significantly increased in vitro (4 h) and in vivo (3 h). DNT cells were distributed into the lung, liver, heart, and kidney earlier, and redistributed to lymphocyte homing spleen and bone marrow, which seemed to frame a two-compartment pharmacokinetics (PK) model but more data are needed to confirm this, and the clearance of DNT cells fell into first-order kinetics., (© 2021 John Wiley & Sons Ltd.)

CD4 and CD8 coreceptor double negative TCRαβ + T (DNT) cells are increasingly being recognized for their critical and diverse roles in the immune system. However, their molecular and functional signatures remain poorly understood and controversial. Moreover, the majority of studies are descriptive because of the relative low frequency of cells and non-standardized definition of this lineage. In this study, we performed single-cell RNA sequencing on 28,835 single immune cells isolated from mixed splenocytes of male C57BL/6 mice using strict fluorescence-activated cell sorting. The data was replicated in a subsequent study. Our analysis revealed five transcriptionally distinct naïve DNT cell clusters, which expressed unique sets of genes and primarily performed T helper, cytotoxic and innate immune functions. Anti-CD3/CD28 activation enhanced their T helper and cytotoxic functions. Moreover, in comparison with CD4 + , CD8 + T cells and NK cells, Ikzf2 was highly expressed by both naïve and activated cytotoxic DNT cells. In conclusion, we provide a map of the heterogeneity in naïve and active DNT cells, addresses the controversy about DNT cells, and provides potential transcription signatures of DNT cells. The landscape approach herein will eventually become more feasible through newer high throughput methods and will enable clustering data to be fed into a systems analysis approach. Thus the approach should become the "backdrop" of similar studies in the myriad murine models of autoimmunity, potentially highlighting the importance of DNT cells and other minor lineage of cells in immune homeostasis. The clear characterization of functional DNT subsets into helper DNT, cytotoxic DNT and innate DNT will help to better understand the intrinsic roles of different functional DNT subsets in the development and progression of autoimmune diseases and transplant rejection, and thereby may facilitate diagnosis and therapy., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Activation of self-reactive CD8 + T cells induces a peripheral tolerance mechanism that involves loss of CD8 expression. Because genetic deficiency of Fas and Fasl causes the accumulation of double-negative (DN; CD3 + TCR-αβ + CD4 - CD8 - ) T cells that have been proposed to derive from CD8 + cells, we decided to explore the role of Fas and FasL in self-antigen-induced CD8 downregulation. To this end, we quantified Fas and FasL induction by different stimuli and analyzed the effects of Fas/FasL deficiency during a protective immune response and after exposure to self-antigens. Our data describes how Fas and FasL upregulation differs depending on the setting of CD8 T cell activation and demonstrates that Fas/FasL signaling maintains CD8 expression during repetitive antigen stimulation and following self-antigen encounter. Together, our results reveal an unexpected role of Fas/FasL signaling and offer a new insight into the role of these molecules in the regulation of immune tolerance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Flores-Mendoza, Rodríguez-Rodríguez, Rubio, Madera-Salcedo, Rosetti and Crispín.)

Collapsing glomerulopathy has multiple associations, including viral infections, medications like bisphosphonates and interferon, autoimmune diseases, and genetic predisposition. We report a case of collapsing focal segmental glomerulosclerosis associated with persistently high levels of interferon gamma produced by T-cell receptor αβ (+), CD4- CD8- (double negative) T lymphocytes that progressed despite treatment and improvement of other cytokine levels. Double negative T cells are elevated and activated in autoimmune lymphoproliferative syndrome (ALPS). Production of elevated interferon gamma levels from double negative T cells in ALPS despite treatment provides insight to the pathophysiology of collapsing glomerulopathy, guiding future research for collapsing glomerulopathy., (© 2020 S. Karger AG, Basel.)

Systemic lupus erythematosus (SLE) is an autoimmune disease of uncertain etiology that affects multiple tissues and organs. Tetra-arsenic tetra-sulfide (As 4 S 4 ), a traditional Chinese medicine, is effective on acute promyelocytic leukemia with mild side effects. In our previous study, BXSB lupus-prone mice treated with As 4 S 4 has showed improved monocytosis, decreased serum interleukin (IL)-6 and suppressed skin, liver and renal lesions with well-tolerance. In this study, we explored the effect and mechanism of As 4 S 4 on the MRL/lpr mice. MRL/lpr and wild MRL/MpJ mice were divided into control and As 4 S 4 treatment groups and dosed with As 4 S 4 or placebo for 8 weeks. We found that As 4 S 4 prevented the skin, renal and lung lesions of MRL/lpr mice. As 4 S 4 significantly decreased the double negative T (DN T) cells and reduced the serum levels of IL-17, IL-10, and antinuclear antibodies titer. Further results revealed that the FasL was decreased, and activated caspases elevated in DN T cells in As 4 S 4 treated MRL/lpr mice. Taken together, As 4 S 4 could selectively suppresses DN T cells by inducing apoptosis. It also reduced inflammatory cytokines IL-17, which may be produced by DN T cells. As 4 S 4 may represent a new therapy for SLE., (© 2019 Wiley Periodicals, Inc.)