Characterization of CD3+CD4-CD8- (double negative) T cells reconstitution in patients following hematopoietic stem-cell transplantation

Reconstitution of double-negative T cells after cord blood transplantation and its predictive value for acute graft-versus-host disease

BACKGROUND

With an increasing number of patients with hematological malignancies being treated with umbilical cord blood transplantation (UCBT), the correlation between immune reconstitution (IR) after UCBT and graft-versus-host disease (GVHD) has been reported successively, but reports on double-negative T (DNT) cell reconstitution and its association with acute GVHD (aGVHD) after UCBT are lacking.

METHODS

A population-based observational study was conducted among 131 patients with hematological malignancies who underwent single-unit UCBT as their first transplant at the Department of Hematology, the First Affiliated Hospital of USTC, between August 2018 and June 2021. IR differences were compared between the patients with and without aGVHD.

RESULTS

The absolute number of DNT cells in the healthy Chinese population was 109 (70-157)/μL, accounting for 5.82 (3.98-8.19)% of lymphocytes. DNT cells showed delayed recovery and could not reach their normal levels even one year after transplantation. Importantly, the absolute number and percentage of DNT cells were significantly higher in UCBT patients without aGVHD than in those with aGVHD within one year ( F = 4.684, P = 0.039 and F = 5.583, P = 0.026, respectively). In addition, the number of DNT cells in the first month after transplantation decreased significantly with the degree of aGVHD increased, and faster DNT cell reconstitution in the first month after UCBT was an independent protective factor for aGVHD (HR = 0.46, 95% confidence interval [CI]: 0.23-0.93; P = 0.031).

CONCLUSIONS

Compared to the number of DNT cells in Chinese healthy people, the reconstitution of DNT cells in adults with hematological malignancies after UCBT was slow. In addition, the faster reconstitution of DNT cells in the early stage after transplantation was associated with a lower incidence of aGVHD.

Adoptive Cell Therapy for T-Cell Malignancies

T-cell malignancies are often aggressive and associated with poor prognoses. Adoptive cell therapy has recently shown promise as a new line of therapy for patients with hematological malignancies. However, there are currently challenges in applying adoptive cell therapy to T-cell malignancies. Various approaches have been examined in preclinical and clinical studies to overcome these obstacles. This review aims to provide an overview of the recent progress on adoptive cell therapy for T-cell malignancies. The benefits and drawbacks of different types of adoptive cell therapy are discussed. The potential advantages and current applications of innate immune cell-based adoptive cell therapy for T cell malignancies are emphasized.

Double Negative T Regulatory Cells: An Emerging Paradigm Shift in Reproductive Immune Tolerance?

Immune regulation of female reproductive function plays a crucial role in fertility, as alterations in the relationship between immune and reproductive processes result in autoimmune subfertility or infertility. The breakdown of immune tolerance leads to ovulation dysfunction, implantation failure, and pregnancy loss. In this regard, immune cells with regulatory activities are essential to restore self-tolerance. Apart from regulatory T cells, double negative T regulatory cells (DNTregs) characterized by TCRαβ+/γδ+CD3+CD4–CD8– (and negative for natural killer cell markers) are emerging as effector cells capable of mediating immune tolerance in the female reproductive system. DNTregs are present in the female reproductive tract of humans and murine models. However, their full potential as immune regulators is evolving, and studies so far indicate that DNTregs exhibit features that can also maintain tolerance in the female reproductive microenvironment. This review describes recent progress on the presence, role and mechanisms of DNTregs in the female reproductive system immune regulation and tolerance. In addition, we address how DNTregs can potentially provide a paradigm shift from the known roles of conventional regulatory T cells and immune tolerance by maintaining and restoring balance in the reproductive microenvironment of female fertility.

Application of double-negative T cells in haematological malignancies: recent progress and future directions

Haematologic malignancies account for a large proportion of cancers worldwide. The high occurrence and mortality of haematologic malignancies create a heavy social burden. Allogeneic haematopoietic stem cell transplantation is widely used in the treatment of haematologic malignancies. However, graft-versus-host disease and relapse after allogeneic haematopoietic stem cell transplantation are inevitable. An emerging treatment method, adoptive cellular therapy, has been effectively used in the treatment of haematologic malignancies. T cells, natural killer (NK) cells and tumour-infiltrating lymphocytes (TILs) all have great potential in therapeutic applications, and chimeric antigen receptor T (CAR-T) cell therapy especially has potential, but cytokine release syndrome and off-target effects are common. Efficient anticancer measures are urgently needed. In recent years, double-negative T cells (CD3⁺CD4^-CD8^-) have been found to have great potential in preventing allograft/xenograft rejection and inhibiting graft-versus-host disease. They also have substantial ability to kill various cell lines derived from haematologic malignancies in an MHC-unrestricted manner. In addition, healthy donor expanded double-negative T cells retain their antitumour abilities and ability to inhibit graft-versus-host disease after cryopreservation under good manufacturing practice (GMP) conditions, indicating that double-negative T cells may be able to be used as an off-the-shelf product. In this review, we shed light on the potential therapeutic ability of double-negative T cells in treating haematologic malignancies. We hope to exploit these cells as a novel therapy for haematologic malignancies.

Enhancement of the Tolerogenic Phenotype in the Liver by ImmTOR Nanoparticles

ImmTOR biodegradable nanoparticles encapsulating rapamycin have been shown to induce a durable tolerogenic immune response to co-administered biologics and gene therapy vectors. Prior mechanism of action studies have demonstrated selective biodistribution of ImmTOR to the spleen and liver following intravenous (IV) administration. In the spleen, ImmTOR has been shown to induce tolerogenic dendritic cells and antigen-specific regulatory T cells and inhibit antigen-specific B cell activation. Splenectomy of mice resulted in partial but incomplete abrogation of the tolerogenic immune response induced by ImmTOR. Here we investigated the ability of ImmTOR to enhance the tolerogenic environment in the liver. All the major resident populations of liver cells, including liver sinusoidal endothelial cells (LSECs), Kupffer cells (KC), stellate cells (SC), and hepatocytes, actively took up fluorescent-labeled ImmTOR particles, which resulted in downregulation of MHC class II and co-stimulatory molecules and upregulation of the PD-L1 checkpoint molecule. The LSEC, known to play an important role in hepatic tolerance induction, emerged as a key target cell for ImmTOR. LSEC isolated from ImmTOR treated mice inhibited antigen-specific activation of ovalbumin-specific OT-II T cells. The tolerogenic environment led to a multi-pronged modulation of hepatic T cell populations, resulting in an increase in T cells with a regulatory phenotype, upregulation of PD-1 on CD4⁺ and CD8⁺ T cells, and the emergence of a large population of CD4^–CD8^– (double negative) T cells. ImmTOR treatment protected mice in a concanavalin A-induced model of acute hepatitis, as evidenced by reduced production of inflammatory cytokines, infiltrate of activated leukocytes, and tissue necrosis. Modulation of T cell phenotype was seen to a lesser extent after administration by empty nanoparticles, but not free rapamycin. The upregulation of PD-1, but not the appearance of double negative T cells, was inhibited by antibodies against PD-L1 or CTLA-4. These results suggest that the liver may contribute to the tolerogenic properties of ImmTOR treatment.

B Lymphocyte Chemoattractant (CXCL13) Is an Indicator of Acute Gastrointestinal GVHD in Murine Model

Gastrointestinal acute graft-vs.-host disease (GI aGVHD) remains a significant obstacle to the success of allogeneic hematopoietic cell transplantation and is a major cause of morbidity and mortality. In addition, GI aGVHD is often clinically indistinguishable from other causes of GI dysfunction such as conditioning regimen toxicity, infections, or medications, which complicates the diagnosis. Thus, specific biomarkers are needed to help improve diagnosis and obtain a deeper understanding of the cytokine changes in GI aGVHD. An MHC-mismatched model of aGVHD was established by transplanting 1 × 10⁷ bone marrow nuclear cells and 3 × 10⁷ spleen cells from C57/Bl6 mice or from BALB/c mice into lethally irradiated BALB/c recipients. The mice in the allogeneic transplantation group were intraperitoneally treated with 20 mg kg^-1 day^-1 cyclosporin A after aGVHD developed. Five micrograms of lipopolysaccharide were administered intraperitoneally daily to syngeneic recipients at day 11 to imitate infection; the same volume of phosphate-buffered saline was administered to control mice. The mice were killed at the indicated time points. Forty molecules derived from the GI tract were screened cytokine array. The data demonstrated that the expression of B lymphocyte chemoattractant (CXCL13) was increased by ~10-, 12-, and 16-fold upon the occurrence of aGVHD compared with infection, aGVHD after treatment, and the syngeneic control group, respectively. Thus, the elevation of BLC (CXCL13) is an indicator of acute GI GVHD.

Infusion of ex-vivo expanded human TCR-αβ+ double-negative regulatory T cells delays onset of xenogeneic graft-versus-host disease

Despite the demonstration of potent immunosuppressive function of T cell receptor (TCR)-αβ⁺ double-negative regulatory T cells (DN T_regs ), scarce numbers and lack of effective expansion method limit their clinical applications. Here we describe an approach that allows for ∼3500-fold ex-vivo expansion of human DN T_regs within 3 weeks with > 97% purity. Ex-vivo-expanded DN T_regs suppress proliferation of polyclonally stimulated autologous T and B cells in vitro through direct cell-to-cell contact. In vivo, we demonstrate for the first time that infusion of human DN T_regs delayed an onset of xenogeneic graft-versus-host disease (GVHD) significantly in a humanized mouse model. Furthermore, preincubation of ex-vivo-expanded DN T_regs with a mechanistic target of rapamycin (mTOR) inhibitor rapamycin enhanced their immune regulatory function further. Taken together, this study demonstrates that human DN T_regs can be expanded ex vivo to therapeutic numbers. The expanded DN T_regs can suppress proliferation of T and B cells and attenuate GVHD, highlighting the potential clinical use of DN T_regs to mitigate GVHD.

The impact of donor characteristics on the immune cell composition of mixture allografts of granulocyte-colony-stimulating factor-mobilized marrow harvests and peripheral blood harvests

BACKGROUND

The association of donor characteristics with immune cell composition in allografts remains poorly understood. In this retrospective study, the effects of donor characteristics on immune cell composition in allografts were investigated.

STUDY DESIGN AND METHODS

The correlations of donor characteristics with the immune cell composition in mixture allografts of granulocyte-colony-stimulating factor-mobilized marrow harvests and peripheral blood harvests of 390 healthy donors (male, 240; female, 150; median age, 40 years old) were analyzed.

RESULTS

The median doses of CD3+ T cells, CD4+ T cells, CD8+ T cells, CD3+CD4-CD8- T cells, and monocytes in mixture allografts were 160.57 × 10(6), 89.29 × 10(6), 56.16 × 10(6), 10.87 × 10(6), and 137.94 × 10(6)/kg, respectively. Multivariate analysis showed that younger donor age was associated with a higher dose of CD3+ T cells (p = 0.006), CD3+CD8+ T cells (p < 0.001), CD3+CD4-CD8- T cells (p = 0.004), and monocytes (p = 0.014), as well as a higher ratio of CD3+CD4-CD8- T cells/CD3+ T cells (p < 0.001) in the mixture allografts. A negative association of donor weight with CD3+ T cells (p < 0.001), CD4+ T cells (p = 0.002), CD8+ T cells (p < 0.001), and CD3+CD4-CD8- T cells (p = 0.044) was observed. The count of peripheral blood lymphocyte pre-peripheral blood apheresis was correlated with the yield of CD3+ T cells (p < 0.001) and CD4+ T cells (p = 0.001). The peripheral blood monocyte count before marrow harvest predicted the monocyte dose (p = 0.002).

CONCLUSION

The results suggested that older and overweight donors should not be chosen. The monocyte and lymphocyte counts before harvest could predict the yield of immune cells in allografts.

TCR+CD4-CD8- T cells in antigen-specific MHC class I-restricted T-cell responses after allogeneic hematopoietic stem cell transplantation

Human TCRαβ(+) CD4(-)CD8(-) double-negative (DN) T cells represent a minor subset in peripheral blood, yet are important in infectious diseases and autoimmune responses. We examined the frequency of DN T cells in 17 patients after allogeneic hematopoietic stem cell transplantation (aHSCT) at 1, 2, 3, 6, and 12 months post-aHSCT and show that these cells increase early after aHSCT and decrease with time after aHSCT. DN T cells reside in the terminally differentiated effector (CD45RA(+)CCR7(-)) T-cell population and are polyclonal, determined by T-cell receptor Vβ CDR3 analysis. Gene expression analysis of ex vivo sorted DN T cells showed a distinct set of gene expression, including interleukin-8, as compared with CD4(+) or CD8(+) T cells. DN T cells contributed to MHC class I-restricted EBV-directed immune responses, defined by antigen-specific cytokine production and by detection of HLA-A*02:01-restricted EBV BMLF-1 (GLCTLVAML), LMP-2A (CLGGLLTMV), and HLA-A*24:02-restricted EBV BRLF-1 (DYCNVLNKEF) and EBNA3 (RYSIFFDY)-specific T cells. We created retroviral-transfected Jurkat cell lines with a Melan-A/MART-1-specific TCR(+) and the CD8α chain to study TCR(+) DN T cells in response to their nominal MHC class I/peptide ligand. We show that DN T cells exhibit increased TCRζ chain phosphorylation as compared with the TCR(+)CD8(+) transgenic T-cell line. DN T cells contribute to antigen-specific T-cell responses and represent an effector T-cell population that may be explored in immunotherapeutic approaches against viral infections or transformed cells.

Increased IL-17 and IL-21 producing TCRαβ+CD4−CD8− T cells in Chinese systemic lupus erythematosus patients

Background: Increased numbers of TCRαβ+CD4−CD8− T cells in the peripheral blood of systemic lupus erythematosus (SLE) patients in the United States and United Kingdom have been reported. However, the proportions of TCRαβ+CD4−CD8− T cells and their involvement in the pathogenesis of SLE in Chinese populations are yet to be determined. Methods: A total of 120 SLE patients, 38 rheumatoid arthritis (RA) patients and 43 normal control subjects were examined. The proportion of TCRαβ+CD4−CD8− T cells in the peripheral blood, Fas expression on these cells, and intracellular cytokine levels in these cells were assessed using flow cytometry. Plasma cytokine concentrations were measured using enzyme-linked immunosorbent assay. Results: The percentages of TCRαβ+CD4−CD8− T cells were increased in Chinese SLE patients, particularly in active SLE patients, correlated with decreased Fas expression on these cells. IL-17 and IL-21 levels in the blood and in TCRαβ+CD4−CD8− T cells from SLE patients were increased. Moreover, a positive correlation was evident between IL-17- and IL-21-producing TCRαβ+CD4−CD8− T cells. Conclusions: Increased TCRαβ+CD4−CD8− T cells expressing inflammatory cytokines, such as IL-17 and IL-21, may be implicated in the pathogenesis of SLE in patients. Appropriate IL-17- and/or IL-21 blockage may be utilized as a novel immunotherapeutic strategy for SLE patients.

Immunoregulatory CD4(-)CD8(-) T cells as a potential therapeutic tool for transplantation, autoimmunity, and cancer

A central objective in organ transplantation and the treatment or prevention of autoimmune disease is the achievement of antigen-specific immune tolerance. An additional challenge in bone marrow transplantation for the treatment of hematological malignancies is the prevention of graft-vs-host disease (GVHD) while maintaining graft-vs-tumor activity. Interestingly, CD4^-CD8^- (double negative, DN) T cells, which exhibit a unique antigen-specific immunoregulatory potential, appear to exhibit all of the properties to respond to these challenges. Herein, we review the therapeutic potential of immunoregulatory DN T cells in various immunopathological settings, including graft tolerance, GVHD, cancer, and autoimmunity.