Regulation of memory CD4 T-cell pool size and function by natural killer T cells in vivo

To develop more effective vaccines and strategies to regulate chronic inflammatory diseases, it is important to understand the mechanisms of immunological memory. Factors regulating memory CD4⁺ T helper (Th)-cell pool size and function remain unclear, however. We show that activation of type I invariant natural killer T (iNKT) cells with glycolipid ligands and activation of type II natural killer T (NKT) cells with the endogenous ligand sulfatide induced dramatic proliferation and expansion of memory, but not naïve, CD4 T cells. NKT cell-induced proliferation of memory Th1 and Th2 cells was dependent largely on the production of IL-2, with Th2-cell proliferation also affected by loss of IL-4. Type II NKT cells were also required for efficient maintenance of memory CD4 T cells in vivo. Activation of iNKT cells resulted in up-regulation of IFN-γ expression by memory Th2 cells. These IFN-γ–producing memory Th2 cells showed a decreased capability to induce Th2 cytokines and eosinophilic airway inflammation. Thus, activated NKT cells directly regulate memory CD4 T-cell pool size and function via the production of cytokines in vivo.     

Natural killer T cells and haemopoiesis

Invariant natural killer T (iNKT) cells are a small but powerful subset of regulatory T cells involved in the modulation of a variety of normal and pathological immune responses. In contrast to conventional or other types of regulatory T cells, they are activated by glycolipid and phospholipid ligands that are presented to them by the non-polymorphic, major histocompatibility complex class I-like molecule CD1d. The in-depth understanding of their function has resulted in successful, iNKT cell-centred experimental therapeutic interventions including prevention of graft-versus-host disease and anti-leukaemia effects. Extending these successes into the clinical arena will require better understanding of their contribution to the pathogenesis of human, including haematological, diseases.     

NK T cells provide lipid antigen-specific cognate help for B cells

The mechanisms of T cell help for production of antilipid antibodies are largely unknown. This study shows that invariant NK T cells (iNK T cells) and B cells cooperate in a model of antilipid antigen-specific antibody responses. We use a model haptenated lipid molecule, 4-hydroxy-3-nitrophenyl-alphaGalactosylCeramide (NP-alphaGalCer), to demonstrate that iNK T cells provide cognate help to lipid-antigen-presenting B cells. B cells proliferate and IgG anti-NP is produced from in vivo-immunized mice and in vitro cocultures of B and NK T cells after exposure to NP-alphaGalCer, but not closely related control glycolipids. This B cell response is absent in CD1d(-/-) and Jalpha18(-/-) mice but not CD4(-/-) mice. The antibody response to NP-alphaGalCer is dominated by the IgM, IgG3, and IgG2c isotypes, and marginal zone B cells stimulate better in vitro lipid antigen-driven proliferation than follicular B cells, suggesting an important role for this B cell subset. iNK T cell help for B cells is shown to involve cognate help from CD1d-instructed lipid-specific iNK T cells, with help provided via CD40L, B7-1/B7-2, and IFN-gamma, but not IL-4. This model provides evidence of iNK T cell help for antilipid antibody production, an important aspect of infections, autoimmune diseases, and vaccine development. Our findings also now allow prediction of those microbial antigens that would be expected to elicit cognate iNKT cell help for antibody production, namely those that can stimulate iNKT cells and at the same time have a polar moiety that can be recognized by antibodies.     

自然杀伤T细胞在支气管哮喘中的研究进展

自然杀伤T（NKT）细胞是一类参与先天性免疫与获得性免疫的特殊的T淋巴细胞,近年来研究发现,NKT细胞对哮喘的Th1／Th2失衡以及气道高反应性的产生具有重要作用,因此研究NKT细胞对揭示哮喘的发生机制以及治疗有着积极的意义。     

Highly activated and expanded natural killer cells for multiple myeloma immunotherapy

Background Patients with gene expression profiling-defined high-risk myeloma in relapse have poor outcomes with current therapies. We tested whether natural killer cells expanded by co-culture with K562 cells transfected with 41BBL and membrane-bound interleukin-15 could kill myeloma cells with a high-risk gene expression profile in vitro and in a unique model which recapitulates human myeloma. DESIGN AND METHODS: OPM2 and high-risk primary myeloma tumors were grown in human fetal bone implanted into non-obese diabetic severe combined immunodeficiency mice with a deficient interleukin-2 receptor gamma chain. These mice are devoid of endogenous natural killer and T-cell activity and were used to determine whether adoptively transferred expanded natural killer cells could inhibit myeloma growth and myeloma-associated bone destruction. RESULTS: Natural killer cells from healthy donors and myeloma patients expanded a median of 804- and 351-fold, respectively, without significant T-cell expansion. Expanded natural killer cells killed both allogeneic and autologous primary myeloma cells avidly via a perforin-mediated mechanism in which the activating receptor NKG2D, natural cytotoxicity receptors, and DNAX-accessory molecule-1 played a central role. Adoptive transfer of expanded natural killer cells inhibited the growth of established OPM2 and high-risk primary myeloma tumors grown in the murine model. The transferred, expanded natural killer cells proliferated in vivo in an interleukin-2 dose-dependent fashion, persisted up to 4 weeks, were readily detectable in the human bone, inhibited myeloma growth and protected bone from myeloma-induced osteolysis. Conclusions These studies provide the rationale for testing expanded natural killer cells in humans.     

Severe and selective deficiency of interferon-gamma-producing invariant natural killer T cells in patients with myelodysplastic syndromes

Here we show that patients with myelodysplastic syndromes (MDS) have a severe deficiency of glycolipid reactive Valpha24+/Vbeta11+ natural killer T (NKT) cells, but not NK cells or CD4+ or CD8+ T cells. Neither the blood nor marrow of MDS patients had detectable interferon-gamma-producing NKT cells in response to the NKT ligand, alpha-galactosyl ceramide, although influenza-virus-specific effector T-cell function was preserved. This severe and selective deficiency of an important immune regulatory cell may contribute to the pathogenesis of MDS.     

Mesenteric B cells centrally inhibit CD4+ T cell colitis through interaction with regulatory T cell subsets

Inflammatory bowel disease reflects an aberrant mucosal CD4+ T cell response to commensal enteric bacteria. In addition to regulatory T cell subsets, recent studies have revealed a protective role of B cells in murine CD4+ T cell colitis, but the relationship of their action to T cell immunoregulation is unknown. Here we report that mesenteric lymph node (MLN) B cells protect mice from colitis induced by Galphai2-/- CD4+ T cells. Protection required the transfer of both B cells and CD8alpha+ T cells; neither cell type alone was sufficient to inhibit CD4+ T cell-mediated colitis. Similar results were also observed in colitis induced by CD4+CD45RBhi T cells. Immunoregulation was associated with localization of B cells and expansion of CD4-CD8- CD3+NK1.1+ T cells in the secondary lymphoid compartment, as well as expansion of CD4+CD8alpha+ T cells in the intestinal intraepithelial compartment. MLN B cells from Galphai2-/- mice were deficient in a phenotypic subset and failed to provide cotransfer colitis protection. These findings indicate that protective action of B cells is a selective trait of MLN B cells acquired through a Galphai2-dependent developmental process and link B cells with the formation of regulatory T cells associated with mucosal immune homeostasis.     

Adoptive immunotherapy for unresectable or recurrent pancreatic cancer,using lymphokine-activated killer cells or cytotoxic T cells

Adoptive immunotherapy (AIT) has been reported to be effective for malignancies in some cases. We hypothesized that AIT may be effective for the treatment of pancreatic cancer. Seven patients with unresectable or recurrent pancreatic cancer underwent AIT, carried out with lymphokine-activated killer (LAK) cells or cytotoxic T cells (CTLS) and recombinant interleukin-2 (IL-2). The clinical and immunological effects were evaluated. Of four patients who received CTLs, one had a partial response, one had a minor response, and two showed no change. The three patients who received LAK cells had progressive disease. The CTLs had a significantly higher proportion of CD8 positive T cells and cytotoxic T cells than the LAK cells (P < 0.05), while the LAK cells had a significantly higher proportion of NK cells than did the CTLs (84 ± 12% vs 55 ± 15%,P < 0.05). The LAK activity of the CTLs (61 ± 14%) was significantly higher than that of the LAK cells (42 ± 8%,P < 0.05). Seven days after treatment with LAK cells or CTLs, lymphocyte subsets in the peripheral blood were examined. The proportion of CD8-positive T cells after CTL transfer (46 ± 5%) was greater than that before CTL transfer (28 ± 1%,P < 0.05). The proportion of cytotoxic T cells after CTL transfer increased from 23 ± 1% to 37 ± 2% (P < 0.05). However, these changes were not observed during LAK cell transfer. The proportions of suppressor inducer T cells, helper T cells, and suppressor T cells did not change during therapy. These results suggested that AIT, using CTLs, merits further clinical investigation in patients with pancreatic cancer.     

Malignant T gamma/delta lymphoproliferative disease with natural killer lytic activity.

A 17-year-old girl presented with a lymphoproliferative disease involving the bone marrow, peripheral blood, and liver associated with reactive hyperplasia of the spleen. Neoplastic cells were atypical medium-sized lymphoblasts with convoluted nuclei and nucleoli without features of large granular lymphocytes (LGL). The phenotype was CD3+ CD4- CD8-, TCR alpha/beta-, TCR gamma/delta+, delta TCS1-, and CD16+, and these cells exhibited spontaneous natural killer (NK) activity. DNA analysis showed rearrangement of the TCR gamma gene but not of TCR beta or of Ig mu genes. This unusual lymphoproliferative disease may represent the neoplastic expansion of a minor subset of normal T gamma/delta cells with NK activity.     

Hepatic natural killer and natural killer T cells markedly decreased in two cases of drug-induced fulminant hepatic failure rescued by living donor liver transplantation

The human liver contains significant numbers of innate immune cells, such as natural killer (NK) cells and natural killer T (NKT) cells, which express both T-cell receptors and NK-cell receptors simultaneously. It has been suggested that the innate immune system plays a crucial role in the liver. In this report, the distribution of NK and NKT cells in the liver and peripheral blood of two patients with drug-induced fulminant hepatic failure (FHF) who had undergone living donor liver transplantation was examined. In both the liver and peripheral blood, the proportions of NK and NKT cells markedly decreased compared with those in healthy donors. It was also revealed that, unlike murine NKT cells, human CD56(+) T cells and CD57(+) T cells did not constitutively express CD28, which is one of the important costimulatory molecules on T cells. Additionally, the residual CD56(+) T cells and CD57(+) T cells in the patients expressed more CD28 than in controls. This result suggests that NKT cells might be more activated in FHF. Although the accumulation of further cases is required, it is suggested that both NK and NKT cells might be involved in hepatic injury in FHF.     

Activated natural killer T cells induce liver injury by Fas and tumor necrosis factor-alpha during alcohol consumption

BACKGROUND & AIMS: Chronic alcohol abuse induces liver injury and increases the severity of viral hepatitis, but the precise mechanisms responsible are not well understood. In particular, little is known about the role of natural killer T cells in alcohol-induced liver injury. Natural killer T cells are mediators of important regulator and effector functions making use of Fas and tumor necrosis factor (TNF)-alpha in apoptosis induction. This report analyzes the role of natural killer T cells, Fas, and TNF-alpha in a model of chronic alcohol consumption. METHODS: Mice fed alcohol by intragastric tube were assayed for serum alanine aminotransferase values, liver histology, and liver mononuclear cells before and after activation of natural killer T cells by ligand alpha-galactosylceramide. RESULTS: In alcohol-consuming animals, liver natural killer T cells increase, and further activation by alpha-galactosylceramide causes lethal liver injury. This is explained by alcohol-induced hepatocyte sensitization to cell-mediated lysis, which develops concomitant to increased cytolytic activity of natural killer T cells. Natural killer T cell-mediated apoptosis proceeds by the Fas pathway, and Fas is essential for alcohol-associated liver injury. TNF-alpha plays an additional role as a defect in TNF receptor-1 inhibits alcohol-associated liver injury. Alcohol-fed natural killer T cell-deficient Jalpha281(-/-) mice express a delay in alcohol-induced liver injury. CONCLUSIONS: Alcohol consumption induces an increase of natural killer T cells in the liver and a high sensitivity of hepatocytes to cell-mediated lysis. Stimulation of natural killer T cells during alcohol consumption induces serious liver injury by a mechanism that involves concomitant signals by Fas and tumor necrosis factor receptor-1 on alcohol-stressed hepatocytes.     

Sustained response to interferon-α plus ribavirin therapy for chronic hepatitis C is closely associated with increased dynamism of intrahepatic natural killer and natural killer T cells

Aim:  Previous studies have revealed that functional impairment of innate immune cells, including natural killer (NK) and natural killer T (NKT) cells, might be associated with the persistence of hepatitis C virus (HCV) infection. However, the involvement of innate immune cells, which predominate in the liver, in therapeutic HCV clearance is still unclear.
Methods:  To clarify the role of intrahepatic innate immune cells in the clinical outcome of patients with chronic hepatitis C (CHC) treated with interferon-α plus ribavirin (IFN/RBV), we prospectively investigated the status of NK and NKT cells in paired liver biopsy and peripheral blood (PB) samples obtained from 21 CHC patients before and immediately after IFN/RBV treatment by flow cytometry. Normal liver and PB samples were obtained from 10 healthy donors for living donor liver transplantation.
Results:  Before treatment, intrahepatic NK and NKT cells constituted a significantly lower proportion in CHC patients than in healthy individuals ( P  < 0.05). After IFN/RBV treatment, the proportions and absolute numbers of CD3^-CD161⁺ NK and CD3⁺CD56⁺ NKT cells in the liver, but not in PB, were significantly increased in sustained responders (SR) as compared with poor responders ( P  < 0.05). The proportion of CD3⁺CD161⁺ NKT cells was also increased in the liver of SR after the treatment. Moreover, there was a striking increase of activated CD152⁺ cells among CD3⁺CD56⁺ NKT cells in the liver of SR ( P  = 0.041).
Conclusion:  These findings demonstrate that sustained response to IFN/RBV treatment for patients with CHC is closely associated with increased dynamism of NK and NKT cells in the liver.     

Genetic engineering of hematopoietic stem cells to generate invariant natural killer T cells

Invariant natural killer T (iNKT) cells comprise a small population of αβ T lymphocytes. They bridge the innate and adaptive immune systems and mediate strong and rapid responses to many diseases, including cancer, infections, allergies, and autoimmunity. However, the study of iNKT cell biology and the therapeutic applications of these cells are greatly limited by their small numbers in vivo (∼0.01–1% in mouse and human blood). Here, we report a new method to generate large numbers of iNKT cells in mice through T-cell receptor (TCR) gene engineering of hematopoietic stem cells (HSCs). We showed that iNKT TCR-engineered HSCs could generate a clonal population of iNKT cells. These HSC-engineered iNKT cells displayed the typical iNKT cell phenotype and functionality. They followed a two-stage developmental path, first in thymus and then in the periphery, resembling that of endogenous iNKT cells. When tested in a mouse melanoma lung metastasis model, the HSC-engineered iNKT cells effectively protected mice from tumor metastasis. This method provides a powerful and high-throughput tool to investigate the in vivo development and functionality of clonal iNKT cells in mice. More importantly, this method takes advantage of the self-renewal and longevity of HSCs to generate a long-term supply of engineered iNKT cells, thus opening up a new avenue for iNKT cell-based immunotherapy.Invariant natural killer T (iNKT) cells are a small population of αβ T lymphocytes highly conserved from mice to humans. Like conventional αβ T cells, iNKT cells are derived from hematopoietic stem cells (HSCs) and develop in the thymus. However, they differ from conventional T cells in several important aspects, including their display of NK cell markers, their recognition of glycolipid antigens presented by the nonclassical monomorphic major histocompatibility complex (MHC) molecule CD1d, and their expression of semi-invariant T-cell receptors (identical α chains paired with a limited selection of β chains) (1, 2). Despite their small numbers in vivo (∼0.1–1% in mouse blood and ∼0.01–1% in human blood), iNKT cells have been suggested to play important roles in regulating many diseases, including cancer, infections, allergies, and autoimmunity (3). When stimulated, iNKT cells rapidly release a large amount of effector cytokines like IFN-γ and IL-4, both as a cell population and at the single-cell level. These cytokines then activate various immune effector cells, such as natural killer (NK) cells and dendritic cells (DCs) of the innate immune system, as well as CD4 helper and CD8 cytotoxic conventional αβ T cells of the adaptive immune system via activated DCs (3, 4). Because of their unique activation mechanism, iNKT cells can attack multiple diseases independent of antigen and MHC restrictions, making them attractive universal therapeutic agents (3, 4). Notably, because of the capacity of effector NK cells and conventional αβ T cells to specifically recognize diseased tissue cells, iNKT cell-induced immune reactions result in limited off-target side effects (3, 4).Restricted by their extremely low numbers, both the study of iNKT cells and their clinical applications have been challenging. iNKT T-cell receptor (TCR) transgenic mice (5, 6) and iNKT induced pluripotent stem (iPS) cell-derived transgenic mice (7) provide valuable tools to study iNKT cell biology in mice, but these methods are both costly and time-consuming. In addition, approaches using transgenic mice have no direct clinical application. As an alternative, a TCR-engineered HSC adoptive transfer strategy could overcome these limitations and become clinically applicable. Since its demonstration in mice in the early 2000s, this HSC-engineered T-cell strategy has been widely used to successfully generate both mouse and human antigen-specific conventional αβ T cells in multiple mouse and humanized mouse models (8–13). Human clinical trials testing this strategy for treating melanoma are also ongoing (14). Based on these previous works and the scientific principle that iNKT cells follow a “TCR instruction” development path similar to that of conventional αβ T cells (15), we hypothesized that HSCs could be engineered to express iNKT TCR genes and be programmed to develop into clonal iNKT cells. In the present report, we demonstrated the feasibility of this new HSC-engineered iNKT cell approach in mice and provided evidence to support its therapeutic potential in a mouse melanoma lung metastasis model.     

Fine tuning by human CD1e of lipid-specific immune responses

CD1e is a member of the CD1 family that participates in lipid antigen presentation without interacting with the T-cell receptor. It binds lipids in lysosomes and facilitates processing of complex glycolipids, thus promoting editing of lipid antigens. We find that CD1e may positively or negatively affect lipid presentation by CD1b, CD1c, and CD1d. This effect is caused by the capacity of CD1e to facilitate rapid formation of CD1-lipid complexes, as shown for CD1d, and also to accelerate their turnover. Similar results were obtained with antigen-presenting cells from CD1e transgenic mice in which lipid complexes are assembled more efficiently and show faster turnover than in WT antigen-presenting cells. These effects maximize and temporally narrow CD1-restricted responses, as shown by reactivity to Sphingomonas paucimobilis-derived lipid antigens. CD1e is therefore an important modulator of both group 1 and group 2 CD1-restricted responses influencing the lipid antigen availability as well as the generation and persistence of CD1-lipid complexes.     

非酒精性脂肪性肝病患者外周血恒定自然杀伤T细胞和CD4+/CD8+T细胞活化差异研究*

目的 分析不同非酒精性脂肪性肝病(NAFLD)患者外周血恒定自然杀伤T细胞(iNKT)、CD4⁺和CD8⁺ T细胞活化标记物(CD69、CD25、HLA-DR和NKG2D)的表达差异。方法 2020年1月～2022年7月我院诊治的NAFLD患者64例和同期健康体检者50例,对NAFLD患者行肝穿刺活检,使用流式细胞仪检测外周血iNKT、CD4⁺和CD8⁺T细胞CD69、CD25、HLA-DR和NKG2D表达。结果 在64例NAFLD患者中,经组织病理学检查,诊断NAFL 37例和NASH 27例;健康对照者、NAFL和NASH患者健康对照者、NAFL和NASH患者外周血CD69⁺iNKT细胞百分比分别为(10.1±1.7)%、(6.1±1.3)%和(26.7±3.6)%(P<0.05),CD25⁺iNKT细胞百分比分别为(83.0±5.9)%、(94.1±8.0)%和(90.8±7.5)%(P<0.05),HLA-DR⁺iNKT细胞百分比分别为(15.3±1.7)%、(15.8±2.0)%和(22.3±2.0)%(P>0.05),NKG2D⁺iNKT细胞百分比分别为(44.5±3.5)%、(59.7±4.0)%和(71.3±6.0)%(P<0.05);外周血CD69⁺CD4⁺ T细胞百分比分别为(0.7±0.2)%、(0.4±0.1)%和(0.5±0.1)%(P>0.05),CD25⁺CD4⁺ T细胞百分比分别为(1.4±0.6)%、(3.0±1.3)%和(1.5±0.7)%(P>0.05),HLA-DR⁺CD4⁺ T细胞百分比分别为(2.7±0.7)%、(4.1±1.0)%和(3.9±1.0)%(P<0.05),NKG2D⁺CD4⁺ T细胞百分比分别为(1.6±0.5)%、(0.6±0.2)%和(0.9±0.2)%(P<0.05);外周血CD69⁺CD8⁺ T细胞百分比分别为(2.0±0.4)%、(1.6±0.3)%和(2.1±0.6)%(P>0.05),CD25⁺CD8⁺ T细胞百分比分别为(1.3±0.3)%、(1.1±0.2)%和(1.0±0.2)%(P>0.05),HLA-DR⁺CD8⁺ T细胞百分比分别为(5.0±0.7)%、(6.5±1.0)%和(9.6±1.4)%(P<0.05),NKG2D⁺CD8⁺ T细胞百分比分别为(0.6±0.1)%、(0.5±0.1)%和(0.9±0.2)%(P<0.05)。结论 本研究发现NAFL与NASH患者可能存在外周血iNKT细胞、CD4⁺和CD8⁺ T细胞活化的免疫表型差异,显示NASH患者CD69⁺iNK T细胞百分比增高,可能对诊断有帮助,值得进一步研究。     

Enhanced cytotoxic function of natural killer and natural killer T‐like cells associated with decreased CD94 (Kp43) in the chronic obstructive pulmonary disease airway

Background and objective: Natural killer (NK) and natural killer T (NKT)‐like cells represent a small but important proportion of effector lymphocytes that we have previously shown to be major sources of pro‐inflammatory cytokines and granzymes. We hypothesized that these cells would be increased in the airway in chronic obstructive pulmonary disease (COPD), accompanied by reduced expression of the inhibitory receptor CD94 (Kp43) and increased expression of cytotoxic mediators granzyme B and perforin. Methods: We measured NK and NKT‐like cells and their expression of CD94 in the blood of COPD patients (n = 71; 30 current and 41 ex‐smokers), smokers (16) and healthy controls (25), and bronchoalveolar lavage fluid (BALF) from a cohort of subjects (19 controls, 12 smokers, 33 COPD). Activation was assessed by measuring CD69 in blood and the cytotoxic potential of NK cells by measuring granzymes A and B, and using a cytotoxicity assay in blood and BALF. Results: In blood in COPD, there were no significant changes in the proportion of NK or NKT‐like cells or expression of granzyme A or NK cytotoxic potential versus controls. There was, however, increased expression of granzyme B and decreased expression of CD94 by both cell types versus controls. The proportion of NK and NKT‐like cells were increased in BALF in COPD, associated with increased NK cytotoxicity, increased expression of granzyme B and decreased expression of the inhibitory receptor CD94 by both cell types. Conclusions: Treatment strategies that target NK and NKT‐like cells, their cytotoxicity and production of inflammatory mediators in the airway may improve COPD morbidity.     

Increased natural killer T-like cells are a major source of pro-inflammatory cytokines and granzymes in lung transplant recipients

Background and objective: Natural killer T (NKT)‐like cells are a small but significant population of T lymphocytes; however, their role in lung transplant and the effect of current immunosuppressive agents on their function is largely unknown. We have previously shown lung transplant rejection was associated with an increase in peripheral blood T cell γ‐interferon (IFN‐γ), tumour necrosis factor‐α (TNF‐α) and granzyme B. NKT‐like cells are a source of these pro‐inflammatory mediators and as such may be involved in lung transplant pathology. Methods: We analysed NKT‐like cell numbers and cytokine and granzyme profiles in peripheral blood from a group of stable lung transplant patients and control subjects using multiparameter flow cytometry. Results: There was a significant increase in NKT‐like cells in transplant patients compared with control subjects (6.8 ± 4.9 vs 0.8 ± 0.2% lymphocytes respectively). There was an increase in the numbers of NKT‐like cells producing IFN‐γ, TNF‐α, IL‐2 IL‐17, granzyme and perforin in transplant patients compared with controls. Immunosuppressant drugs were less effective at inhibiting IFN‐γ and TNF‐α production by T and NKT‐like cells than NK cells in vitro. Conclusions: Current therapeutics is inadequate at suppressing NKT‐like cell numbers and their production of pro‐inflammatory mediators known to be associated with graft rejection. Alternative therapies that specifically target NKT‐like cells may improve patient morbidity.