Natural killer T cells: rapid responders controlling immunity and disease

The expression of CD86 in CD3+CD56+ NKT cells is associated with the occurrence and prognosis of sepsis-associated encephalopathy in sepsis patients: a prospective observational cohort study

The role of CD3+CD56+ natural killer T (NKT) cells and its co-signaling molecules in patients with sepsis-associated encephalopathy (SAE) is unknown. In this prospective observational cohort study, we initially recruited 260 septic patients and eventually analyzed 90 patients, of whom 57 were in the SAE group and 37 were in the non-SAE group. Compared to the non-SAE group, 28-day mortality was significantly increased in the SAE group (33.3% vs. 12.1%, p = 0.026), while the mean fluorescence intensity (MFI) of CD86 in CD3+CD56+ NKT cells was significantly lower (2065.8 (1625.5 ~ 3198.8) vs. 3117.8 (2278.1 ~ 5349), p = 0.007). Multivariate analysis showed that MFI of CD86 in NKT cells, APACHE II score, and serum albumin were independent risk factors for SAE. Furthermore, the Kaplan-Meier survival analysis indicated that the mortality rate was significantly higher in the high-risk group than in the low-risk group (χ2 = 14.779, p < 0.001). This study showed that the decreased expression of CD86 in CD3+CD56+ NKT cells is an independent risk factor of SAE; thus, a prediction model including MFI of CD86 in NKT cells, APACHE II score, and serum albumin can be constructed for diagnosing SAE and predicting prognosis.

KRN7000 Reduces Airway Inflammation via Natural Killer T Cells in Obese Asthmatic Mice

Although natural killer T cells (NKT cells) are altered in obese asthmatic mice, their function remains completely unclear. To further explore the potential mechanism of NKT cells in airway inflammation of obesity-associated asthma, we examined the effects of α-galactosylceramide (KRN7000) on airway inflammation in obese asthmatic mice. Male C57BL/6J mice were divided into five groups: (1) control; (2) asthma; (3) A + KRN, asthma with KRN7000; (4) obese asthma; and (5) OA + KRN, obese asthma with KRN7000. Cytometric bead array (CBA) was used to detect interleukin-4 (IL-4), IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in the serum. Flow cytometry was used to detect NKT cells and CD69⁺ NKT cells. Airway inflammation was observed in pathological sections, and calmodulin (CaM) expression was observed by immunohistochemistry in lung tissues. Airway inflammation in the obese asthma group was more severe than that of the asthma group. Airway inflammation of the OA + KRN group was reduced more than that of the A + KRN group. CD69+ NKT cells were only significantly reduced in the OA + KRN group. The levels of serum IFN-γ and TNF-α increased more in the OA + KRN group than in the A + KRN group. CaM is widely expressed in the cytoplasm of the lung tissues and was sharply decreased in the OA + KRN group. KRN7000 can significantly reduce airway inflammation in obesity-associated asthma by regulating NKT cell cytokine secretion and intracellular calcium. These results may contribute to the development of novel therapeutic approaches.

Blockade of CD40L inhibits immunogenic maturation of lung dendritic cells: Implications for the role of lung iNKT cells in mouse models of asthma

Some studies have shown that maturation of dendritic cells (DCs) is modulated directly by pathogen components via pattern recognition receptors such as Toll-like receptors, but also by signal like CD40 ligand (CD40 L or CD154) mediated by activated T cells. Several reports indicate that invariant natural killer T (iNKT) cells up-regulate CD40 L upon stimulation and thereby induce activation and maturation of DCs through crosslink with CD40. Our previous findings indicated that iNKT cells promote Th2 cell responses through the induction of immunogenic maturation of lung DCs (LDCs) in the asthmatic murine, but its mechanism remains unclear. Therefore, we investigated the immunomodulatory effects of blockade of CD40 L using anti-CD40 L treatment on Th2 cell responses and immunogenic maturation of LDCs, and further analyzed whether these influences of blockade of CD40 L were related to lung iNKT cells using iNKT cell-deficient mice and the combination treatment of specific iNKT cell activation with anti-CD40 L treatment in murine models of asthma. Our findings showed that blockade of CD40 L using anti-CD40 L treatment attenuated Th2 cell responses in wild-type (WT) mice, but not in CD1d-deficient mice sensitized and challenged with ovalbumin (OVA) or house dust mite (HDM). Meanwhile, blockade of CD40 L down-regulated immunogenic maturation of LDCs in WT mice, but not in CD1d-deficient mice sensitized and challenged with OVA. Additionally, agonistic anti-CD40 treatment reversed the inhibitory effects of anti-CD40 L treatment on Th2 cell responses and LDC activation in an OVA-induced mouse model of asthma. Furthermore, LDCs from asthmatic mice treated with anti-CD40 L could significantly reduce the influence on Th2 cell responses in vivo and in vitro. Finally, α-Galactosylceramide plus anti-CD40 L treatment stimulated lung iNKT cells, but suppressed Th2 cell responses in the asthmatic mice. Taken together, our data raise an evidence that blockade of CD40 L attenuates Th2 cell responses through the inhibition of immunogenic maturation of LDCs, which may be at least partially related to lung iNKT cells in murine models of asthma.

CD56(dim)CD16(high) and CD56(bright)CD16(-) cell percentages associated with maximum knee extensor strength and incidence of death in elderly

Physical fitness is an indicator of systemic well-being in humans. Little is known about the role of physical fitness for maintaining systemic health in the elderly. Here, we study elderly subjects to determine the relationships between physical fitness and CD56 and CD16 surface NK cell markers on peripheral blood lymphocytes, as well as to analyze the relationship between the surface markers and incidence of death. We selected 253 independent elderly subjects (122 female; 131 male) who were 79–80 years old. Subjects having a higher proportion of CD56^dimCD16^high within CD56⁺CD16⁺ cells, or ration of CD56^dimCD16^high and CD56^dimCD16⁻ cells had a significant positive correlation with maximum bilateral knee extensor strength/weight (kg) (r = 0.425; P < 0.0001 or r = 0.323; P < 0.0001). In contrast, an increased proportion of CD56^brightCD16⁻ cells within lymphocyte significantly negatively correlated with the maximum bilateral knee extensor strength/weight (kg) (r = −0.290; P = 0.0004); and these subjects had a significantly lower mortality during the 5 years following measurement of death. Therefore, we found that a synergistic effect of the right and left leg muscle strength was associated with proportion of matured NK and NKT cells and induced a low proportion of CD56^brightCD16⁻ cells within lymphocyte. Moreover, the low proportion of CD56^brightCD16⁻ cells was associated with incidence of death. In conclusion, measurements of physical fitness, the proportion of CD56^dimCD16^high within CD56⁺CD16⁺ cells, the ratio of CD56^dimCD56^high and CD56^dimCD16⁻ cells, and the proportion of CD56^brightC16⁻ cells in lymphocytes are important indicators to check elderly health.

Oxidative stress-mediated iNKT-cell activation is involved in COPD pathogenesis

Chronic obstructive pulmonary disease (COPD) is a major clinical challenge mostly due to cigarette smoke (CS) exposure. Invariant natural killer T (iNKT) cells are potent immunoregulatory cells that have a crucial role in inflammation. In the current study, we investigate the role of iNKT cells in COPD pathogenesis. The frequency of activated NKT cells was found to be increased in peripheral blood of COPD patients relative to controls. In mice chronically exposed to CS, activated iNKT cells accumulated in the lungs and strongly contributed to the pathogenesis. The detrimental role of iNKT cells was confirmed in an acute model of oxidative stress, an effect that depended on interleukin (IL)-17. CS extracts directly activated mouse and human dendritic cells (DC) and airway epithelial cells (AECs) to trigger interferonγ and/or IL-17 production by iNKT cells, an effect ablated by the anti-oxidant N-acetylcystein. In mice, this treatment abrogates iNKT-cell accumulation in the lung and abolished the development of COPD. Together, activation of iNKT cells by oxidative stress in DC and AECs participates in the development of experimental COPD, a finding that might be exploited at a therapeutic level.

Differential expression of natural killer activating and inhibitory receptors in patients with newly diagnosed systemic lupus erythematosus

AIM

Systemic lupus erythematosus (SLE) presents as the abnormal activation and over-proliferation of immune competent cells. Few studies have characterized the role of natural killer (NK) and NK T (NKT) cells in the pathogenesis of SLE, and therefore a consensus has not been reached as yet.

METHOD

Thirty-two patients with new-onset SLE and 15 healthy controls were recruited. Activated and inhibitory NK and NKT cells in peripheral blood were quantified by flow cytometry. The proportions of spontaneous and stimulated interferon (IFN)-γ(+) NK and NKT cells and CD107a(+) NK cells was examined. Finally, the potential relationship between the cell subsets and clinical indexes was analyzed.

RESULTS

The proportions of NK and NKT cells (P = 0.002 and 0.004, respectively) as well as the proportions of NKG2C(+) NK cells, inhibitory NK and NKT cell subsets (P = 0.016, P = 0.019, P = 0.049, and P = 0.028, respectively) in SLE patients were significantly lower than those in controls. In contrast, the proportions of activated NK cells and NKT cell subsets were significantly higher (P = 0.036, P = 0.034, P = 0.005, and P = 0.007, respectively). Moreover, the proportions of stimulated IFN-γ(+) NKT cells were significantly higher than in the controls, and the proportions of stimulated CD107a(+) NKT cells in SLE patients were significantly lower than in the controls (P = 0.032 and P = 0.02, respectively).

CONCLUSION

Lower proportions of NK and NKT cells, higher proportions of activated NK cells and activated NKT cells, lower proportions of inhibitory NK and NKT cells, higher NKT cell activity, and lower NKT cell degranulation may induce the autoimmune reaction involved in the pathogenesis of SLE.

Therapeutic potential of atorvastatin-modified dendritic cells in experimental autoimmune neuritis by decreased Th1/Th17 cytokines and up-regulated T regulatory cells and NKR-P1(+) cells

Statins have pleiotropic effects which include anti-inflammatory and immunomodulatory effects. In the present study, dendritic cells treated with atorvastatin (statin-DCs) could be induced into tolerogenic DCs. Administration of these tolerogenic DCs ameliorated clinical symptoms in experimental autoimmune neuritis (EAN), which was associated with reduced number of inflammatory cells in sciatic nerves, inhibited CD4(+) T cells proliferation, down-regulated expression of co-stimulatory molecules (CD80 and CD86) and MHC class II, decreased levels of IFN-γ, TNF-α and IL-17A, increased number of NKR-P1(+) cells (including NK and NKT cells), up-regulated number of Treg cells in lymph node MNC as well as increased Foxp3 expression in the thymus. These data indicated that statin-DCs could develop as a new therapeutic strategy to GBS in the future.

Blockade of IL-33 ameliorates Con A-induced hepatic injury by reducing NKT cell activation and IFN-γ production in mice

IL-33, a recently described member of the IL-1 family, has been identified as a cytokine endowed with pro-Th2 type functions. To date, there are only limited data on its role in physiological and pathological hepatic immune responses. In this study, we examined the role of IL-33 in immune-mediated liver injury by exploring the model of concanavalin A (Con A)-induced hepatitis. We observed that the level of IL-33 expression in the liver was dramatically increased at 12 h after Con A injection. Meanwhile, ST2L, the receptor of IL-33, was significantly up-regulated in lymphocytes including T and natural killer T (NKT) cells, especially in NKT cells. Moreover, administration of recombinant IL-33 exacerbated Con A-induced hepatitis, while pretreatment of IL-33-blocking antibody or psST2-Fc plasmids showed a protective effect probably by inhibiting the activation of late stage of T cells and NKT cells and also decreasing the production of the cytokine IFN-γ. Furthermore, depletion of NKT cells abolished the protective effect of IL-33-blocking antibody, and IL-33 failed to exacerbate Con A-induced hepatitis in IFN-γ(-/-) mice. These data suggested the critical roles of NKT cells and IFN-γ in the involvement of IL-33 in Con A-induced hepatitis. Blockade of IL-33 may represent a novel therapeutic strategy through IL-33/ST2L signal to prevent immune-mediated liver injury.

Changes in immune cell frequencies after cyclophosphamide or mycophenolate mofetil treatments in patients with systemic lupus erythematosus

This study was designed to explore the profile of immune cell subsets, including T, B, natural killer (NK), and NKT cells, in systemic lupus erythematosus (SLE) patients, and to determine their relationships with the clinical index and the effects of cyclophosphamide (CYC) and mycophenolate mofetil (MMF) treatment. SLE patients (n = 28) and age/sex-matched healthy controls (n = 28) were evaluated. The patients were equally divided into two treatment groups: intravenous drip (IVD) with CYC and prednisolone, and oral MMF and IVD with prednisolone. SLE peripheral blood samples were taken immediately prior to treatment and after 4 weeks of drug treatment. T, B, NK, and NKT cell subsets were measured by flow cytometry. Double-stranded DNA antibody and Sm antibody were detected by indirect immunofluorescence. Serum C3, C4, and C-reactive protein were determined by scatter turbidimetry. The percentages of CD3+CD4+ T, CD3-CD16CD56+ NK, and CD3+CD16CD56+ NKT cells and the CD4+/CD8+ ratio were significantly lower in SLE patients, while CD3+CD8+ T and CD3-CD19+ B cells were higher than the controls. The lymphocyte subsets were significantly correlated with the SLE disease activity index (SLEDAI) and complement factors (C3, C4). Four weeks of CYC or MMF treatment led to a significant increase in CD3+CD4+ T cells (P < 0.05). In addition, both CYC and MMF treatments led to increases in CD3+ T and CD3-CD16CD56+NKT cells and decreases in CD3-CD16CD56+ NK and CD3+CD8+ T cells, but these changes were not obvious. The significant correlation that exists between lymphocytes subsets and SLEDAI activity scores suggests that the lymphocyte subsets may reflect SLE severity. Our results indicate that both the traditional cyclophosphamide agent and the new mycophenolate mofetil agent can regulate the lymphocyte subsets and consequent abnormal immunity, suggesting that MMF, which is known to produce less side-effects than CYC, may be used as an effective treatment of SLE.

Targeting dendritic cells with nano-particulate PLGA cancer vaccine formulations

Development of safe and effective cancer vaccine formulation is a primary focus in the field of cancer immunotherapy. The recognition of the crucial role of dendritic cells (DCs) in initiating anti-tumor immunity has led to the development of several strategies that target vaccine antigens to DCs as an attempt for developing potent, specific and lasting anti-tumor T cell responses. The main objective of this review is to provide an overview on the application of poly (d,l-lactic-co-glycolic acid) nanoparticles (PLGA-NPs) as cancer vaccine delivery system and highlight their potential in the development of future therapeutic cancer vaccines. PLGA-NPs containing antigens along with immunostimulatory molecules (adjuvants) can not only target antigen actively to DCs, but also provide immune activation and rescue impaired DCs from tumor-induced immuosupression.

Imunopatologia da dermatite de contato alérgica

A dermatite de contato alérgica é consequência de uma reação imune mediada por células T contra químicos de baixo peso molecular, denominados haptenos. É uma condição frequente que ocorre em todas as raças e faixas etárias e afeta a qualidade de vida de seus portadores. O mecanismo imunológico desta doença vem sendo revisto nas últimas décadas com significativo avanço no seu entendimento. A metabolização e o caminho dos haptenos, bem como a formação e o mecanismo de ação das células responsáveis tanto pela reação quanto pelo seu término, são discutidos neste artigo

CD1d-independent activation of invariant natural killer T cells by staphylococcal enterotoxin B through major histocompatibility complex class II/T cell receptor interaction results in acute lung injury

There are two important mechanisms of activation of invariant natural killer T cells (iNKT cells) by microbes: direct activation of the invariant T-cell receptor (TCR) by microbial glycolipids presented by CD1d and indirect activation, mediated by the responses of antigen-presenting cells to microbes. In this study, we provide evidence for a novel CD1d-independent direct activation of iNKT cells involving a microbial protein superantigen presented in the context of major histocompatibility complex class II (MHC-II), which plays a critical role in pathogenesis, thereby redefining the role of iNKT cells. Intranasal exposure to staphylococcal enterotoxin B (SEB) in C57BL/6 wild-type mice caused acute lung injury (ALI) characterized by vascular leak, cytokine storm, and infiltration of mononuclear cells in the lungs. In contrast, the vascular leak and inflammation were decreased by ~50% in NKT cell-deficient Jα18(-/-) and CD1d(-/-) mice following SEB exposure, which was reversed following adoptive transfer of iNKT cells into CD1d(-/-) mice. In vitro, SEB could directly stimulate iNKT cells in a CD1d-independent manner via MHC-II/TCR interaction, specifically involving Vβ8. These studies not only demonstrate that iNKT cells can be activated directly by a bacterial protein superantigen independent of CD1d but also indicate that in addition to the conventional T cells, iNKT cells play a critical role in SEB-mediated ALI.

Glucose metabolism disorders and the risk of cancer

Diabetes and cancer are diseases which take the size of an epidemic spread across the globe. Those diseases are influenced by many factors, both genetic and environmental. Precise knowledge of the complex relationships and interactions between these two conditions is of great importance for their prevention and treatment. Many epidemiological studies have shown that certain types of cancer, especially gastrointestinal cancers (pancreas, liver, colon) and also the urinary and reproductive system cancers in women are more common in patients with diabetes or related metabolic disorders. There are also studies showing the inverse relationship between diabetes and cancer, or the lack of it, but they are less numerous and relate mainly to prostate cancer or squamous cell carcinoma of the esophagus. Epidemiological studies, however, do not say anything about the mechanisms of these dependencies. For this purpose, molecular research is needed on the metabolism of cells (including tumor cells) and on metabolic dysfunctions that arise due to changes in the cell environment taking place in the sick, as well as in the intensely treated human organism.

A novel technique to explore the functions of bronchial mucosal T cells in chronic obstructive pulmonary disease: application to cytotoxicity and cytokine immunoreactivity

Bronchial mucosal CD8(+) cells are implicated in chronic obstructive pulmonary disease (COPD) pathogenesis, but there are few data on their functional properties. We have developed a novel technique to outgrow these cells from COPD patients in sufficient numbers to examine effector functions. Endobronchial biopsies from 15 COPD smokers and 12 ex-smokers, 11 control smokers and 10 non-smokers were cultured with anti-CD3/interleukin (IL)-2 ± IL-15. Outgrown CD3(+) T cells were characterized in terms of phenotype (expression of CD4, 8, 25, 28, 69 and 56), cytotoxicity and expression of COPD-related cytokines. Compared with IL-2 alone, additional IL-15 increased the yield and viability of biopsy-derived CD3(+) T cells (12-16-day culture without restimulation) without alteration of CD4(+) /CD8(+) ratios or expression of accessory/activation molecules. Biopsy-derived T cells, principally CD8(+)/CD56(+) cells, exhibited statistically significantly greater cytotoxic activity in current or ex-smokers with COPD compared with controls (P < 0·01). Elevated percentages of CD8(+) T cells expressed interferon (IFN)-γ, tumour necrosis factor (TNF)-α and IL-13 (P < 0·01) in current COPD smokers compared with all comparison groups. It is possible to perform functional studies on bronchial mucosal T cells in COPD. We demonstrate increased CD8(+)CD56(+) T cell cytotoxic activity and expression of remodelling cytokines in smokers who develop COPD.

Distinct abnormalities in the innate immune system of children with Down syndrome

OBJECTIVE

To analyze the frequency and phenotype of cells of the innate immune system in the peripheral blood of children with Down syndrome (DS).

STUDY DESIGN

Flow cytometric analysis of expression of cell surface markers was performed in children with DS (n = 41) and healthy age-matched controls (n = 41).

RESULTS

Compared with controls, children with DS had significantly lower absolute total leukocyte counts, lymphocytes, monocytes, and granulocytes, but 1.5-times higher absolute numbers of CD14(dim)CD16(+) monocytes (147 x 10(6)/L vs 93 x 10(6)/L; P = .02). This difference is fully explained by a higher percentage of CD14(dim)CD16(+) monocytes within the monocyte compartment (28.7% vs 13.4%; P <.001). The absolute numbers of myeloid dendritic cells were lower in DS (13.8 x 10(6)/L vs 22.7 x 10(6)/L; P <.001). The numbers of plasmacytoid dendritic cells and natural killer cells were normal. Absolute numbers of invariant natural killer T cells were very low overall, but significantly lower in children with DS than in controls (1.2 x 10(6)/L vs 3.7 x 10(6)/L; P = .01).

CONCLUSIONS

Children with DS exhibited distinct abnormalities in cells of the innate immune system. Most strikingly, they had a high number of proinflammatory CD14(dim)CD16(+) monocytes. This elevated level of CD14(dim)CD16(+) monocytes may play an important role in the onset and maintenance of chronic inflammatory disease in DS.

Decreased expression of T lymphocyte co-stimulatory molecule CD26 on invariant natural killer T cells in systemic lupus erythematosus

CD26, a T cell co-stimulatory molecule and dipeptidyl peptidase IV for the degradation of interferon-gamma-induced chemokine, participates in multiple immunopathological roles in leukocyte homing and inflammation. Decreased circulating concentration of soluble (s)CD26 in patients with systemic lupus erythematosus (SLE), rheumatoid arthritis and murine model of arthritis and encephalomyelitis have been reported. In the present study, the plasma concentration of sCD26 and chemokines, and cell surface expression of CD26 on monocytes, CD4+T lymphocytes, CD8+T lymphocytes, CD19+B lymphocytes and invariant natural killer T (iNKT) lymphocytes were analyzed using ELISA and flow cytometry, respectively, in 23 SLE patients and 14 sex- and age-matched control subjects. Although there was no significant difference between plasma concentrations of soluble CD26 in SLE patients with controls (p > 0.05), there was significant elevated Th1 chemokines CXCL10 and CXCL9 but not Th2 chemokine CCL2, and down-regulation in iNKT lymphocytes number and cell surface expression of CD26 on CD4+T and iNKT lymphocytes of SLE patients compared with controls (all p < 0.05). Decreased circulating number of iNKT cells and CD26 on iNKT cells can be important for the immunopathogenesis by exacerbating Th1-related inflammation in SLE.

Assay of T- and NK-cell subsets and the expression of NKG2A and NKG2D in patients with new-onset systemic lupus erythematosus

This study aims to explore the percentage of T-cell and NK-cell subsets, the expression of NKG2A and NKG2D on CD3+ T cells and CD3-CD56+ NK cells on the total lymphocytes in new-onset systemic lupus erythematosus (SLE) patients, and explore clinical significance of these cell subsets. Thirty-two SLE patients and 32 normal controls were enrolled. Flow cytometry was used to count T- and NK-cell subsets and to detect the expression of NKG2A and NKG2D on CD3+ T cells and CD3-CD56+ NK cells in patients with new-onset SLE. Results show that CD4+ T (t = 2.04, P < 0.05), CD4+/CD8+ T cell (t = 2.66, P < 0.05), CD4+ CD25+ T (t = 2.48, P < 0.05), CD3+CD56+ natural killer T (NKT) (t = 40.05, P < 0.01), CD3-CD56+CD16+ NK-cell subsets (t = 3.50, P < 0.01) were significantly decreased, CD8+ T-cell subsets was significantly increased in patients with new-onset SLE (t = 3.80, P < 0.01), as compared with healthy controls. CD8+ T-cell subset was significantly increased in patients with vasculitis (t = 2.47, P < 0.05), and CD3-CD56+CD16+ NK was increased in patients with arthritis (t = 3.21, P < 0.01). However, no statistically significant correlation was found among different PBMC subsets and SLEDAI activity scores. Patients with SLE had a lower expression of NKG2A (U = 2.42, P < 0.05) as well as NKG2A/NKG2D ratio (t = 2.61, P < 0.05) and a higher expression of NKG2D (t = 2.21, P < 0.05) on CD3+ T cells, compared with normal controls. However, they had a higher expression of NKG2A (t = 2.59, P < 0.05) as well as NKG2A/NKG2D ratio (t = 49.45, P < 0.01) and a lower expression of NKG2D (t = 3.05, P < 0.01) on CD3-CD56+ NK cells. Taken together, the findings indicate the decreased CD4+ T-cell, CD4+/CD8+ T-cell, CD4+CD25+ T-cell, CD3+CD56+ NKT-, and CD3-CD56+CD16+ NK-cell subsets, increased CD8+ T-cell subsets as well as the abnormal expression of NKG2A and NKG2D on CD3+ T and CD3-CD56 + NK cells may play a role in the etiology of SLE.

Distinct contributions of CD4+ T cell subsets in hepatic ischemia/reperfusion injury

Helper T cells are known to mediate hepatic ischemia/reperfusion (I/R) injury. However, the precise mechanisms and subsets of CD4(+) T cells that contribute to this injury are still controversial. Therefore, we sought to determine the contributions of different CD4(+) T cell subsets during hepatic I/R injury. Wild-type, OT-II, or T cell receptor (TCR)-delta-deficient mice were subjected to 90 min of partial hepatic ischemia followed by 8 h of reperfusion. Additionally, wild-type mice were pretreated with anti-CD1d, -NK1.1, or -IL-2R-alpha antibodies before I/R injury. OT-II mice had diminished liver injury compared with wild-type mice, implicating that antigen-dependent activation of CD4(+) T cells through TCRs is involved in hepatic I/R injury. TCR-delta knockout mice had decreased hepatic neutrophil accumulation, suggesting that gammadelta T cells regulate neutrophil recruitment. We found that natural killer T (NKT) cells, but not NK cells, contribute to hepatic I/R injury via CD1d-dependent activation of their TCRs, as depletion of NKT cells by anti-CD1d antibody or depletion of both NKT cells and NK cells by anti-NK1.1 attenuated liver injury. Although regulatory T cells (Treg) are known to suppress T cell-dependent inflammation, depletion of Treg cells had little effect on hepatic I/R injury. The data suggest that antigen-dependent activation of CD4(+) T cells contributes to hepatic I/R injury. Among the subsets of CD4(+) T cells, it appears that gammadelta T cells contribute to neutrophil recruitment and that NKT cells directly injure the liver. In contrast, NK cells and Treg have little effects on hepatic I/R injury.

Statins impair CD1d-mediated antigen presentation through the inhibition of prenylation

Statins are widely used as cholesterol-lowering agents that also decrease inflammation and target enzymes essential for prenylation, an important process in the activation and intracellular transport of proteins vital for a wide variety of cellular functions. Here, we report that statins impair a critical component of the innate immune response, CD1d-mediated Ag presentation. The addition of specific intermediates in the isoprenylation pathway reversed this effect, whereas specific targeting of enzymes responsible for prenylation mimicked the inhibitory effects of statins on Ag presentation by CD1d as well as MHC class II molecules. This study demonstrates the importance of isoprenylation in the regulation of Ag presentation and suggests a mechanism by which statins reduce inflammatory responses.

Natural killer T cells: an unconventional T-cell subset with diverse effector and regulatory functions

Natural killer T (NKT) cells are a unique subset of lymphocytes that express NK cell markers such as CD161 and CD94, as well as a T-cell receptor (TCR) alpha/beta, with a restricted repertoire, which distinguishes them from NK cells, which lack a TCR. In contrast to conventional T-lymphocytes, the TCR of NKT cells does not interact with that of peptide antigens presented by classical major histocompatibility complex-encoded class I or II molecules. Instead, this TCR recognizes glycolipids presented by CD1d, a non-classical antigen-presenting molecule. The rapid response of NKT cells to their cognate antigens is characteristic of an innate immune response, and allows the polarizing cytokines (IFN-gamma and/or IL-4) to regulate adaptive immunity. NKT cells have been found to be critical in the immune response against viral infections and malaria, as well as in tumor immunity, and certain autoimmune diseases. NKT cells have been assessed to represent the "trait d'union" between innate and adaptive immunity. They play an active role in skin diseases, such as contact sensitivity, which have been implicated in UV-induced immunosuppression and psoriasis. Thus, NKT-cells are emerging as an important subset of lymphocytes, with a protective role in host defense and a pathogenic role in certain immune-mediated disease states.

Administration of beta-glycolipids overcomes an unfavorable nutritional dependent host milieu: a role for a soy-free diet and natural ligands in intrahepatic CD8+ lymphocyte trapping and NKT cell redistribution

Soy-based diets are a major source of sphingolipids and play a complicated role in various aspects of the immune system. Administration of beta-glycolipids, including beta-glucosylceramide (GC), beta-lactosylceramide (LC) and a 1:1 combination of GC and LC (IGL) were shown to exert immune-modulatory effects.

AIM

To examine the effects of a soy-free diet, and several beta-glycolipids on concanavalin A (ConA)-induced hepatitis in the presence of an altered host glycolipid milieu.

METHODS

ConA hepatitis was induced in C57BL/6 mice that were fed a soy-free diet (glycolipid content 200 micromol/kg). Two hours prior to administration of ConA, animals were injected IP with GC, LC, IGL or PBS. Animals were sacrificed 6 h after ConA administration.

RESULTS

Both a soy-free diet and administration of beta-glycolipids were associated with significant alterations in the distribution of NKT cells. Specifically, there was a decrease in intrahepatic and an increase in intrasplenic NKT lymphocytes. beta-glycolipids prevented the ConA-induced intrahepatic CD8 lymphocyte trapping, not seen in mice with only a soy-free diet. Both a soy-free diet and beta-glycolipids alleviated ConA-induced hepatitis by inhibiting IL10 secretion and increasing IL12 serum levels. The effect of IGL was clinically and immunological superior to that of either glycolipid alone.

CONCLUSIONS

Both a soy-free diet and beta-glycolipids can overcome the unfavorable host milieu in the setting of ConA hepatitis. The host glycolipid milieu profoundly influenced the immune and clinical effects of various insults, and suggests that alteration of the glycolipid background of the host can serve as a novel therapeutic tool.

Naive and innate memory phenotype CD4+ T cells have different requirements for active Itk for their development

The Tec family kinase Itk regulates the development of conventional and innate CD8(+) T cells. However, little is known about the role of Itk in the development of CD4(+) T cell lineages, although the role of Itk in the T cell activation and function is well defined. We show in this study that Itk null mice have increased percentage of CD62L(low)CD44(high) memory phenotype CD4(+) T cells compared with wild-type mice. These cells arise directly in the thymus, express high levels of transcripts for the T-bet and IFN-gamma and are able to produce IFN-gamma directly ex vivo in response to stimulation. Itk deficiency greatly decreases the number of CD4(+) T cells with CD62L(high)CD44(low) naive phenotype, but has no effect on the number of memory phenotype CD4(+) T cells, indicating that the development of memory phenotype CD4(+) T cells is Itk-independent. We further show that the development of the naive phenotype CD4(+) T cells is dependent on active Itk signals and can be rescued by expression of Itk specifically in T cells. Our data also show that Itk is required for functional TCR signaling in these cells, but not for the innate function in response to IL-12/IL-18 or Listeria monocytogenes stimulation. These results indicate that CD62L(high)CD44(low) "naive" CD4(+) and CD62L(low)CD44(high) "innate memory phenotype" CD4(+) T cells may be independent populations that differ in their requirement for Itk signals for development. Our data also suggest that CD4(+)CD62L(low)CD44(high) memory phenotype T cells have innate immune function.

OX40 ligand expressed by DCs costimulates NKT and CD4+ Th cell antitumor immunity in mice

The exceptional immunostimulatory capacity of DCs makes them potential targets for investigation of cancer immunotherapeutics. We show here in mice that TNF-alpha-stimulated DC maturation was accompanied by increased expression of OX40 ligand (OX40L), the lack of which resulted in an inability of mature DCs to generate cellular antitumor immunity. Furthermore, intratumoral administration of DCs modified to express OX40L suppressed tumor growth through the generation of tumor-specific cytolytic T cell responses, which were mediated by CD4+ T cells and NKT cells. In the tumors treated with OX40L-expressing DCs, the NKT cell population significantly increased and exhibited a substantial level of IFN-gamma production essential for antitumor immunity. Additional studies evaluating NKT cell activation status, in terms of IFN-gamma production and CD69 expression, indicated that NKT cell activation by DCs presenting alpha-galactosylceramide in the context of CD1d was potentiated by OX40 expression on NKT cells. These results show a critical role for OX40L on DCs, via binding to OX40 on NKT cells and CD4+ T cells, in the induction of antitumor immunity in tumor-bearing mice.

Ozone exposure in a mouse model induces airway hyperreactivity that requires the presence of natural killer T cells and IL-17

Exposure to ozone, which is a major component of air pollution, induces a form of asthma that occurs in the absence of adaptive immunity. Although ozone-induced asthma is characterized by airway neutrophilia, and not eosinophilia, it is nevertheless associated with airway hyperreactivity (AHR), which is a cardinal feature of asthma. Because AHR induced by allergens requires the presence of natural killer T (NKT) cells, we asked whether ozone-induced AHR had similar requirements. We found that repeated exposure of wild-type (WT) mice to ozone induced severe AHR associated with an increase in airway NKT cells, neutrophils, and macrophages. Surprisingly, NKT cell-deficient (CD1d(-/-) and Jalpha18(-/-)) mice failed to develop ozone-induced AHR. Further, treatment of WT mice with an anti-CD1d mAb blocked NKT cell activation and prevented ozone-induced AHR. Moreover, ozone-induced, but not allergen-induced, AHR was associated with NKT cells producing interleukin (IL)-17, and failed to occur in IL-17(-/-) mice nor in WT mice treated with anti-IL-17 mAb. Thus, ozone exposure induces AHR that requires the presence of NKT cells and IL-17 production. Because NKT cells are required for the development of two very disparate forms of AHR (ozone- and allergen-induced), our results strongly suggest that NKT cells mediate a unifying pathogenic mechanism for several distinct forms of asthma, and represent a unique target for effective asthma therapy.

Inhibition of apoptosis, activation of NKT cell and upregulation of CD40 and CD40L mediated by M. leprae antigen(s) combined with Murabutide and Trat peptide in leprosy patients

Protective immunity against intracellular pathogen Mycobacterium leprae is dependent on the activation of T cells. Repeated stimulation of T cells by M. leprae antigens MLCwA (M. leprae total cell wall antigen) and ManLAM (mannose-capped lipoarabinomannan), may lead to apoptosis in leprosy patients. In the present study, inhibition of the Fas-induced apoptosis of peripheral blood mononuclear cells of leprosy patients was investigated using above M. leprae antigen(s), in combination with immunomodulators murabutide (MB) and a Trat peptide in particulate form (liposome). Incubation of the cells with antigen containing the two immunomodulators in particulate form (liposomes) led to decrease in percentage of propidium iodide positive cells and T cells expressing Fas-FasL as well as decreased caspase-8/-3 activities in lepromatous patients, thereby inhibiting apoptosis, while converse was true upon stimulation with soluble antigen. Concurrently, there was an upregulation of antiapoptotic protein Bcl-xL in lepromatous patients, leading to the inhibition of apoptosis. It was also observed that same formulation upregulated the expression of CD40 on B cells and monocytes-macrophages and CD40L on T cells of lepromatous leprosy patients. The same liposomal formulation significantly increased the expression of CD1b and CD1d on monocytes-macrophages as well as percentage of NKT cells secreting IFN-gamma in lepromatous leprosy patients. Thus, the liposomal formulation of antigen with the immunomodulators in vitro promoted the activation of CD40:CD40L pathways and NKT cell function involved in providing cell-mediated immunity to these patients. The same formulation also caused reversal of T cell anergy by inhibiting apoptosis through decreased expression of death receptors (Fas-FasL) and caspase activities (3 and 8) and increased expression of antiapoptotic protein Bcl-xL in these patients.

Decreased frequency and proliferative response of invariant Valpha24Vbeta11 natural killer T (iNKT) cells in healthy elderly

Invariant natural killer T (iNKT) cells represent a well-established T cell lineage characterised in humans by TCR consisting of an invariant alpha chain encoded by Valpha24-JalphaQ genes, paired preferentially with a Vbeta11 chain. iNKT cells also share some characteristics with NK cells, such as the expression of the NK-associated receptor CD161 in humans. The T cell immune response is the most dramatically affected by ageing, although age-associated alterations in the phenotype and function of other cells of the immune system have been demonstrated. Despite the importance of iNKT cells in the regulation of the immune response, there are a limited number of studies on the effect of ageing on peripheral blood iNKT cells. Thus, in this work we analyse the effect of ageing on peripheral blood Valpha24(+)Vbeta11(+) iNKT cells by studying their frequency, phenotype and proliferative function in elderly individuals fulfilling the SENIEUR criteria of healthy ageing compared with healthy young donors. Our results demonstrated a significant decrease of the percentage of Valpha24(+)Vbeta11(+) iNKT cells in elderly donors. No significant differences were found in the expression of CD27, CD28, CD45RO, CD45RA(bright), CD161, CD94 and NKG2D on iNKT cells from young and elderly individuals. Proliferation of Valpha24(+)Vbeta11(+) iNKT cells in response to alpha-GalCer and IL2 was analysed by calculating the cumulative population doubling (PD) after 14 days of culture. The PD levels were lower in the elderly indicating that Valpha24(+)Vbeta11(+) iNKT cells from healthy elderly subjects had an impaired proliferative capacity. These results indicate that ageing associates with a significant decline in the percentage and proliferative response of peripheral blood iNKT cells. Given the important immunoregulatory role of iNKT cells, these alterations in their number and function could contribute to the deleterious immune response in the elderly.

Increased expression of plasma and CD4+ T lymphocyte costimulatory molecule CD26 in adult patients with allergic asthma

CD26, which is a costimulatory molecule and peptidase, is responsible for the degradation of interferon (IFN)-gamma-induced chemokines. To elucidate the immunopathological role of CD26 in allergic asthma, we investigated plasma soluble CD26 (sCD26) concentration and its cell surface expression on lymphocytes, monocytes, CD4+ T helper, CD8+ T suppressor plus cytotoxic T, invariant natural killer T (iNKT), and CD19+ B lymphocytes in allergic asthmatic patients. Plasma sCD26 was significantly elevated in asthmatic patients regardless of inhaled corticosteroid treatment (all P < 0.05). Cell surface expression of CD26 was significantly up-regulated on lymphocytes, especially on CD4+ and iNKT lymphocytes (all P < 0.05), but not on other cell types. Significant positive correlations were found between sCD26 and the percentage of eosinophils, Th2-related chemokines CCL5 and CCL22, and costimulatory molecule sCTLA-4 (all P < 0.05). In conclusion, the aberrant expression of CD26 may contribute to the inflammatory process and Th2 predominance in the immunopathogenesis of allergic asthma.

Peripheral blood CD161+ T cells from asthmatic patients are activated during asthma attack and predominantly produce IFN-gamma

In humans, T cells expressing the CD161 molecule NKR-P1A constitute around 20% of the circulating CD3(+) cells and are potentially immunoregulatory in several diseases. Their role in asthma is not well known, but they could participate in asthma attacks. To determinate whether activation of CD161(+) T cells and their cytokine production correlate with clinical status of asthma, we analysed blood samples from asthma attack patients (AAP) and stable asthma patients (SAP) in comparison with healthy non-atopic controls (HC). There was a significant higher baseline expression of CD69 on T cells from AAP and the difference was more notorious on CD161(+) T cells; upregulation of CD69 was observed on both CD161(-) and CD161(+) T cells driven by Dermatophagoides pteronyssinus crude extract, whereas polyclonal stimulation with phorbol 12-myristate 13-acetate plus ionomycin predominantly induced IFN-gamma but no IL-4, IL-5 and IL-13 by CD161(+) T cells in all groups; upon polyclonal stimulation, there were more CD161(+) T cells producing IFN-gamma and less CD161(-) T cells producing this cytokine, contrasting with the opposite results observed in SAP and HC groups. Our results indicate that, during asthma attack, CD161(+) T cells are activated and are able to produce predominantly IFN-gamma but no Th2 cytokines. We hypothesize that during an asthma attack, IFN-gamma produced by CD161(+) T cells could help to reestablish the Th1/Th2 equilibrium. These observations may contribute to the understanding of the immune mechanisms involved in asthma attacks.

Passive Transfer of Experimental Autoimmune Neuritis by IL-12 and IL-18 Synergistically Potentiated Lymphoid Cells is Regulated by NKR-P1+ Cells

The aim of this study was to investigate the roles and mechanism of interleukin-12 (IL-12) and interleukin-18 (IL-18) in potentiating the autoreactivity of lymphoid cells specific for P2 53-78 peptide. P2 53-78-specific lymphoid cells in the presence of IL-12 or IL-18 alone passive transferred only moderate experimental autoimmune neuritis (EAN) into a low percentage of recipients. However, lymphoid cells co-cultured with both cytokines transferred aggressive clinical and histological EAN into all recipients. NKR-P1+ cells (including NK and NKT cells) played an immunosuppressive function in passive transfer EAN and depletion of NKR-P1+ cells by anti-NKR-P1 Ab and complement induced a more serious form of EAN. Nevertheless, lymphoid cells co-cultured with both IL-12 and IL-18 induced high levels of interferon-gamma (IFN-gamma) and promoted Th1 differentiation partially through NKR-P1+ cells and to some extent, NKR-P1+ cell depletion inhibited the auto-reactivity of lymphoid cells treated with IL-12 and IL-18.

Reduced CD4+ subset and Th1 bias of the human iNKT cells in Type 1 diabetes mellitus

Invariant NKT (iNKT) cells are considered to be important in some autoimmune diseases including Type 1 diabetes mellitus (T1DM). So far, the published data are contradictory in regard to the role of iNKT cells in T1DM. We aimed to study iNKT cell frequency and the function of different iNKT cell subgroups in T1DM. We compared the results of four subject groups: healthy (H), long-term T2DM (ltT2DM; more than 1 year), newly diagnosed T1DM (ndT1DM; less than 3 months), and ltT1DM (more than 1 year) individuals. We measured the iNKT cell frequencies by costaining for the invariant TCR alpha-chain with 6B11-FITC and Valpha24-PE. After sorting the Valpha24+6B11+ cells, the generated iNKT clones were characterized. We tested CD4, CD8, and CD161 expression and IL-4 and IFN-gamma production on TCR stimulation. The CD4+ population among the iNKT cells was decreased significantly in ltT1DM versus ndT1DM, ltT2DM, or H individuals. The T1DM iNKT cell cytokine profile markedly shifted to the Th1 direction. There was no difference in the frequency of iNKT cells in PBMC among the different patient groups. The decrease in the CD4+ population among the iNKT cells and their Th1 shift indicates dysfunction of these potentially important regulatory cells in T1DM.

Adenosine A2A receptor activation reduces hepatic ischemia reperfusion injury by inhibiting CD1d-dependent NKT cell activation

Ischemia reperfusion injury results from tissue damage during ischemia and ongoing inflammation and injury during reperfusion. Liver reperfusion injury is reduced by lymphocyte depletion or activation of adenosine A_2A receptors (A_2ARs) with the selective agonist 4- {3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]- prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester (ATL146e). We show that NKT cells are stimulated to produce interferon (IFN)-γ by 2 h after the initiation of reperfusion, and the use of antibodies to deplete NK1.1-positive cells (NK and NKT) or to block CD1d-mediated glycolipid presentation to NKT cells replicates, but is not additive to, the protection afforded by ATL146e, as assessed by serum alanine aminotransferase elevation, histological necrosis, neutrophil accumulation, and serum IFN-γ elevation. Reduced reperfusion injury observed in RAG-1 knockout (KO) mice is restored to the wild-type (WT) level by adoptive transfer of NKT cells purified from WT or A_2AR KO mice but not IFN-γ KO mice. Additionally, animals with transferred A_2AR^−/− NKT cells are not protected from hepatic reperfusion injury by ATL146e. In vitro, ATL146e potently inhibits both anti-CD3 and α-galactosylceramide–triggered production of IFN-γ by NKT cells. These findings suggest that hepatic reperfusion injury is initiated by the CD1d-dependent activation of NKT cells, and the activation of these cells is inhibited by A_2AR activation.

Plasma IL-2, NK, IFN-γ, and C3 in male workers exposed to traffic pollutants

The aim of the study is to evaluate if the occupational exposure to urban stressors could cause alterations in interleukin-2 (IL-2), NK, interferon-γ (IFN-γ) and C3 plasma levels in male traffic police officers compared to controls. After excluding the principal confounding factors, 108 traffic police officers were matched with 108 controls by age, working life, habitual consumption of alcohol and spirits. IL-2 mean levels were significantly higher in traffic police officers compared to controls (p=0.04). The distribution of IL-2 values in traffic police officers and in controls was significant (p=0.01). The distribution of NK value percentage in traffic police officers and in controls was significant (p=0.000). IFN-γ and C3 mean levels were not significant in traffic police officers compared to controls. Our results suggest that the occupational chronic exposure to low doses of urban stressors could affect NK and IL-2 plasma concentrations in traffic police officers of male sex.

Differential regulation of cytokine production by CD1d-restricted NKT cells in response to superantigen staphylococcal enterotoxin B exposure

NKT cells are a heterogeneous population characterized by the ability to rapidly produce cytokines, such as interleukin 2 (IL-2), IL-4, and gamma interferon (IFN-gamma) in response to infections by viruses, bacteria, and parasites. The bacterial superantigen staphylococcal enterotoxin B (SEB) interacts with T cells bearing the Vbeta3, -7, or -8 T-cell receptors, inducing their expansion and cytokine secretion, leading to death in some cases due to cytokine poisoning. The majority of NKT cells bear the Vbeta7 or -8 T-cell receptor, suggesting that they may play a role in regulating this response. Using mice lacking NKT cells (CD1d(-/-) and Jalpha18(-/-) mice), we set out to identify the role of these cells in T-cell expansion, cytokine secretion, and toxicity induced by exposure to SEB. We find that Vbeta8(+) CD4(+) T-cell populations similarly expand in wild-type (WT) and NKT cell-null mice and that NKT cells did not regulate the secretion of IL-2. By contrast, these cells positively regulated the secretion of IL-4 and IFN-gamma production and negatively regulated the secretion of tumor necrosis factor alpha (TNF-alpha). However, this negative regulation of TNF-alpha secretion by NKT cells provides only a minor protective effect on SEB-mediated shock in WT mice compared to mice lacking NKT cells. These data suggest that NKT cells may regulate the nature of the cytokine response to exposure to the superantigen SEB and may act as regulatory T cells during exposure to this superantigen.