Adoptive transfer of ex vivo immune-programmed NKT lymphocytes alleviates immune-mediated colitis

Invariant NKT Cells and Rheumatic Disease: Focus on Primary Sjogren Syndrome

Primary Sjogren syndrome (pSS) is a complex autoimmune disease mainly affecting salivary and lacrimal glands. Several factors contribute to pSS pathogenesis; in particular, innate immunity seems to play a key role in disease etiology. Invariant natural killer (NK) T cells (iNKT) are a T-cell subset able to recognize glycolipid antigens. Their function remains unclear, but studies have pointed out their ability to modulate the immune system through the promotion of specific cytokine milieu. In this review, we discussed the possible role of iNKT in pSS development, as well as their implications as future markers of disease activity.

It Takes "Guts" to Cause Joint Inflammation: Role of Innate-Like T Cells

Innate-like T cells such as invariant natural killer T (iNKT) cells and mucosal-associated T (MAIT) cells, characterized by a semi-invariant T cell receptor and restriction toward MHC-like molecules (CD1 and MR1 respectively), are a unique unconventional immune subset acting at the interface of innate and adaptive immunity. Highly represented at barrier sites and capable of rapidly producing substantial amounts of cytokines, they serve a pivotal role as first-line responders against microbial infections. In contrast, it was demonstrated that innate-like T cells can be skewed toward a predominant pro-inflammatory state and are consequently involved in a number of autoimmune and inflammatory diseases like inflammatory bowel diseases and rheumatic disorders, such as spondyloarthritis (SpA) and rheumatoid arthritis. Interestingly, there is link between gut and joint disease as they often co-incide and share certain aspects of the pathogenesis such as established genetic risk factors, a critical role for pro-inflammatory cytokines, such as TNF-α, IL-23, and IL-17 and therapeutic susceptibility. In this regard dysregulated IL-23/IL-17 responses appear to be crucial in both debilitating pathologies and innate-like T cells likely act as key player. In this review, we will explore the remarkable features of iNKT cells and MAIT cells, and discuss their contribution to immunity and combined gut-joint disease.

Old and New Lymphocyte Players in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is a chronic intestinal inflammatory disorder characterized by diffuse accumulation of lymphocytes in the gut mucosa as a consequence of over-expression of endothelial adhesion molecules. The infiltrating lymphocytes have been identified as subsets of T cells, including T helper (Th)1 cells, Th17 cells, and regulatory T cells. The function of these lymphocyte subpopulations in the development of IBD is well-known, since they produce a number of pro-inflammatory cytokines, such as interferon-γ and interleukin-17A, which in turn activate mucosal proteases, thus leading to the development of intestinal lesions, i.e., ulcers, fistulas, abscesses, and strictures. However, the immune mechanisms underlying IBD are not yet fully understood, and knowledge about the function of newly discovered lymphocytes, including Th9 cells, innate lymphoid cells, mucosal-associated invariant T cells, and natural killer T cells, might add new pieces to the complex puzzle of IBD pathogenesis. This review summarizes the recent advances in the understanding of the role of mucosal lymphocytes in chronic intestinal inflammation and deals with the therapeutic potential of lymphocyte-targeting drugs in IBD patients.

Sodium selenite ameliorates dextran sulfate sodium-induced chronic colitis in mice by decreasing Th1, Th17, and γδT and increasing CD4(+)CD25(+) regulatory T-cell responses

AIM

To assess the effect of sodium selenite on the severity of dextran sulfate sodium (DSS)-induced colitis in C57BL/6 mice.

METHODS

Mice were randomly divided into four groups (n = 10/group): normal group, selenium (Se) group, chronic colitis group, and Se + chronic colitis group. The mice were sacrificed on day 26. Survival rates, clinical symptoms, colon length, and histological changes were determined. The percentages and absolute numbers of immune system cells in the lamina propria lymphocytes (LPL) of the colon, the expression of mRNA in colon tissue, and the concentrations of Th1, Th17, and Treg cytokines in LPL from the large intestine, were measured.

RESULTS

Se significantly ameliorated the symptoms of colitis and histological injury (P < 0.05 each), increasing the proportions of neutrophils and CD4⁺ CD25⁺ T cells (P < 0.05 each) and decreasing the proportions of γδT cells, CD4⁺, CD4⁺CD44⁺, and CD4⁺ CD69⁺ T cells in LPL (P < 0.05 each). Moreover, Se reduced the expression of IL-6, IFN-γ, IL-17A, IL-21, T-bet, and RORγt (P < 0.05 each), but enhanced the expression of IL-10 and Foxp3 (P < 0.05 each).

CONCLUSION

These results suggest that Se protects against DSS-induced chronic colitis perhaps by increasing the number of CD4(+)CD25(+) Tregs that suppress the secretion of proinflammatory cytokines and populations of Th1, Th17, and γδT cells.

Oral administration of a non-absorbable plant cell-expressed recombinant anti-TNF fusion protein induces immunomodulatory effects and alleviates nonalcoholic steatohepatitis

AIM

To evaluate the immunomodulatory effect of oral administration of PRX-106 in the high-fat diet model.

METHODS

For 22 wk, C57BL/6 HFD-fed mice received daily oral treatments with BY-2 cells expressing recombinant anti-tumor necrosis factor alpha fusion protein (PRX-106). Mice were followed for serum liver enzyme and triglyceride levels, liver histology and intrahepatic and systemic FACS.

RESULTS

The orally administered non-absorbable PRX-106 was biologically active. Altered distribution of CD4+CD25+FoxP3+ between the liver and spleen and an increase in the intrasplenic-to-intrahepatic CD4+CD25+FoxP3+ ratio and a decrease in the intrasplenic-to-intrahepatic CD8+CD25+FoxP3+ ratio were observed. An increase in intrahepatic NKT cells and a decrease in the intrasplenic-to-intrahepatic NKT ratio were noted. Assessment of the CD4-to-CD8 ratios showed sequestration of CD8+ lymphocytes in the liver. These effects were associated with a decrease in serum triglyceride levels, decrease in the aspartate aminotransferase levels, serum glucose levels, and HOMA-IR score. A decrease in hepatic triglycerides content was observed in the high dose-treated mice.

CONCLUSION

Orally administered PRX-106 shows biological activity and exerts an immunomodulatory effect, alleviating liver damage. The data suggest that PRX-106 may provide an oral immunotherapy for nonalcoholic steatohepatitis.

Interleukin 23 in Crohn's disease

: Crohn's disease (CD) is a lifelong inflammatory condition with underlying environmental and genetic components. CD affects multiple parts of the gastrointestinal tract, and it has a growing incidence in Western societies. IL-23 receptor variants have been identified as susceptibility or resistance factors for CD in genome-wide association studies. Accordingly, IL-23 is required for the development of experimental inflammatory bowel disease in many murine models. IL-23 receptor is expressed by both innate and adaptive immune cells, which include Th17, natural killer T, γδ T cells, and RORγt innate lymphoid cells all of which are capable of secreting IL-17A, IL-17F, IL-22, and interferon-γ upon IL-23 stimulation. During the past decade, pathogenic and protective roles have been described for these cytokines in the inflammatory bowel disease pathogenesis. More recently, innate lymphoid cells have been implicated in disease development. In this review, we have summarized and discussed these findings with an emphasis not only on the contribution of Th17 but also on innate lymphoid cells to disease etiology.

Commensal microbiota and NKT cells in the control of inflammatory diseases at mucosal surfaces

Natural Killer T (NKT) cells are a phenotypically and functionally diverse subset of T cells, which recognizes self- and microbial lipids in the context of the atypical MHC class I molecule CD1d. NKT cells exhibit potent effector functions and play critical roles in antimicrobial defense, cancer immunosurveillance and the modulation of immune-mediated disorders. Recent evidence has revealed extensive cross-regulation between the mucosal microbiota and CD1d as well as NKT cells. Microbial exposure at mucosal surfaces, particularly during early postnatal development, regulates NKT cell trafficking and function in the intestine and the lung and determines the susceptibility to NKT cell-mediated inflammatory disorders. Conversely, CD1d controls the composition of the intestinal microbiota; perhaps through the regulation of Paneth cell function. Here, we provide an overview of recent findings on the crosstalk between the microbiota and NKT cells and discuss the implication for mucosal homeostasis and its dysregulation in inflammatory disorders.

The functions of type I and type II natural killer T cells in inflammatory bowel diseases

CD1d-restricted natural killer T (NKT) cells are a distinct subset of T cells that rapidly produce an array of cytokines on activation and play a critical role in regulating various immune responses. NKT cells are classified into 2 groups based on differences in T-cell receptor usage. Type I NKT cells have an invariant T-cell receptor α-chain and are readily detectable by α-galactosylceramide (α-GalCer)-loaded CD1d tetramers. Type II NKT cells have a more diverse T-cell receptor repertoire and cannot be directly identified. Both types of NKT cells and multiple CD1d-expressing cell types are present in the intestine, and their interactions are likely to be modulated by pathogenic and commensal microbes, which in turn contribute to the intestinal immune responses in health and disease. Indeed, in several animal models of inflammatory bowel disease, type I NKT cells have been shown to make both protective and pathogenic contributions to disease. In contrast, in patients with ulcerative colitis, and a mouse model in which both CD1d expression and the frequency of type II NKT cells are increased, type II NKT cells seem to promote intestinal inflammation. In this review, we summarize the present knowledge on the antigen recognition, activation, and function of NKT cells with a particular focus on their role in inflammatory bowel disease and discuss factors that may influence the functional outcome of NKT cell responses in intestinal inflammation.

Colonic inflammation in mice is improved by cigarette smoke through iNKT cells recruitment

Cigarette smoke (CS) protects against intestinal inflammation during ulcerative colitis. Immunoregulatory mechanisms sustaining this effect remain unknown. The aim of this study was to assess the effects of CS on experimental colitis and to characterize the intestinal inflammatory response at the cellular and molecular levels. Using the InExpose® System, a smoking device accurately reproducing human smoking habit, we pre-exposed C57BL/6 mice for 2 weeks to CS, and then we induced colitis by administration of dextran sodium sulfate (DSS). This system allowed us to demonstrate that CS exposure improved colonic inflammation (significant decrease in clinical score, body weight loss and weight/length colonic ratio). This improvement was associated with a significant decrease in colonic proinflammatory Th1/Th17 cytokine expression, as compared to unexposed mice (TNF (p=0.0169), IFNγ (p<0.0001), and IL-17 (p=0.0008)). Smoke exposure also induced an increased expression of IL-10 mRNA (p=0.0035) and a marked recruitment of iNKT (invariant Natural Killer T; CD45+ TCRβ+ CD1d tetramer+) cells in the colon of DSS-untreated mice. Demonstration of the role of iNKT cells in CS-dependent colitis improvement was performed using two different strains of NKT cells deficient mice. Indeed, in Jα18KO and CD1dKO animals, CS exposure failed to induce significant regulation of DSS-induced colitis both at the clinical and molecular levels. Thus, our study demonstrates that iNKT cells are pivotal actors in the CS-dependent protection of the colon. These results highlight the role of intestinal iNKT lymphocytes and their responsiveness to environmental stimuli. Targeting iNKT cells would represent a new therapeutic way for inflammatory bowel diseases.

IL-9-producing invariant NKT cells protect against DSS-induced colitis in an IL-4-dependent manner

Although the T-helper type 9 (Th9) subset has recently been revisited, interleukin (IL)-9-producing invariant natural killer T (iNKT) cells remain poorly characterized. Moreover, whether IL-9-producing iNKT cells regulate colitis is unknown. Here, we investigated functions of IL-9-producing iNKT cells in dextran sulfate sodium (DSS)-induced colitis. Wild-type (WT) mice attenuated colitis compared to Jα18(-/-) mice, which were restored by the adoptive transfer of WT, but not IL-4-deficient iNKT cells. IL-4-deficient iNKT cells failed to produce IL-9, which was reversed by recombinant IL-4. Furthermore, iNKT cells, pre-incubated with anti-CD3+CD28 monoclonal antibodies and IL-4+tumor growth factor (TGF)-β (IL-9(+) iNKT), suppressed colitis in Jα18(-/-) mice, whereas pre-incubated IL-4-deficient iNKT cells did not. IL-9 blockade reversed IL-9(+) iNKT cell-mediated colitis by increasing colonic IL-17A and interferon (IFN)-γ transcripts, but decreasing IL-9, IL-10, TGF-β, PU.1, IFN regulatory factor 4, and signal transducer and activator of transcription 5 in Jα18(-/-) mice. In conclusion, IL-9-producing iNKT cells protect against DSS-induced colitis through IFN-γ and IL-17A suppression, but IL-10 and TGF-β enhancement, depending on the IL-4 production by iNKT cells.

Oral administration of Alequel, a mixture of autologous colon-extracted proteins for the treatment of Crohn's disease

The pathogenesis of Crohn's disease involves an immune-mediated damage to the gut mucosa. Current developed therapies are based on the use of immunosuppressive drugs that can lead to significant drug-related adverse responses. There is a need for a therapeutic strategy that is more specific and less global in its effect on the immune system. Oral tolerance is an active process wherein oral administration of antigens is associated with the induction of regulatory cells and the suppression of effector cells directed toward specific and nonspecific antigens. Studies in animal models of experimental colitis suggest that oral administration of proteins extracted from the gut can induce tolerance and alleviate the disease symptoms. Recent clinical trials showed that oral administration of Alequel, an autologous protein-containing colon extract, to patients with Crohn's disease is safe and may be effective as a therapeutic modality for treating the disease. This treatment was associated with disease-associated antigen alterations of the immune response in the patients. Oral administration of Alequel could provide a patient-tailored approach that is side-effect-free for the treatment of patients with Crohn's disease.

Oral tolerance: can we make it work?

Mucosal tolerance remains an attractive approach for the treatment of autoimmune and inflammatory diseases. The agents used in these treatments lack toxicity, can be easily administered, and enable the promotion of antigen-specific immune responses. The limited success of clinical trials over the past 2 decades has led to the fear that the beneficial effect observed in animal models cannot be repeated in humans. Successful application of mucosal tolerance for the treatment of human diseases will depend on strategies that target the correct cells in the gut-liver axis, improve antigen presentation, alter the administered dose and formulations, utilize potent mucosal adjuvants, develop immune biomarkers enabling follow-up of the effect, utilize combination therapies with other immune modulatory agents, and target the right patient populations. Here, we discuss 12 of the major questions related to oral tolerance and its clinical application to humans with immune-mediated disorders.

Glucocerebroside: an evolutionary advantage for patients with Gaucher disease and a new immunomodulatory agent

Gaucher disease (GD) is caused by the reduced activity of a lysosomal enzyme, glucocerebrosidase, leading to the accumulation of glucocerebroside (GC). The relatively high prevalence of this disease within an ethnic group is believed to reflect a selective advantage. Treatment with enzyme replacement therapy (ERT) is safe and effective in ameliorating the primary symptoms of the disease, yet there have been reports that some patients on ERT have developed type 2 diabetes or metabolic syndrome, malignancies and central nervous system disorders. A series of animal studies suggest that these complications may be related to the reduction of GC levels by the enzyme administered. GC has been shown to have an immunomodulatory effect through the promotion of dendritic cells, natural killer T cells, and regulatory T cells. The break down of GC to ceramide can underline part of these findings. Clinical trials suggested a beneficial effect of GC in type 2 diabetes or nonalcoholic steatohepatitis. This review of the data from animal models and humans proposes that the increased level of GC may provide an evolutionary advantage for patients with GD. Indirectly, these data support treating symptomatic patients with mild/moderate GD with low-dose ERT and re-evaluating the use of ERT in asymptomatic patients.

Body traffic: ecology, genetics, and immunity in inflammatory bowel disease

The abundant bacteria and other microbial residents of the human intestine play important roles in nutrient absorption, energy metabolism, and defense against microbial pathogens. The mutually beneficial relationship of host and commensal microbiota represents an ancient and major coevolution in composition and mutual regulation of the human mucosa and the resident microbial community. Inflammatory bowel disease (IBD) is a set of chronic, relapsing inflammatory intestinal diseases in which rules of normal host-microbial interaction have been violated. This review considers the components of this host-microbial mutualism and the ways in which it is undermined by pathogenic microbial traits and by host immune and epithelial functions that confer to them susceptibility in patients with IBD. Recent advances in understanding the genetics of IBD and the immunology of host-microbial interaction are opening new strategies for treatments that target host susceptibility, candidate microbial pathogens, and intestinal ecology.

beta-Glycosphingolipids as immune modulators

beta-Glycosphingolipids have emerged as a family of potential ligands for natural killer T (NKT)-regulatory lymphocytes. This subset of regulatory lymphocytes has been implicated in the regulation of autoimmune processes. The major histocompatibility complex (MHC) Class I-like CD1d glycoprotein is a member of the CD1 family of antigen-presenting molecules and is responsible for selection of NKT cells. beta-Glycolipids have been shown to alter immune responses in the opposing settings of autoimmune diseases or cancer. In this review, we discuss the potential use of beta-glycoshpingolipids for NKT-based immunotherapy.

Potential role of NKT regulatory cell ligands for the treatment of immune mediated colitis

Natural killer T lymphocytes (NKT) have been implicated in the regulation of autoimmune processes in both mice and humans. In response to stimuli, this subset of cells rapidly produces large amounts of cytokines thereby provoking immune responses, including protection against autoimmune diseases. NKT cells are present in all lymphoid compartments, but are most abundant in the liver and bone marrow. They are activated by interaction of their T-cell receptor with glycolipids presented by CD1d, a nonpolymorphic, major histocompatibility complex class I-like molecule expressed by antigen presenting cells. Several possible ligands for NKT cells have recently been suggested. β-glucosylceramide, a naturally occurring glycolipid, is a metabolic intermediate in the anabolic and catabolic pathways of complex glycosphingolipids. Like other β-glycolipids, β-glucosylceramide has an immunomodulatory effect in several immune mediated disorders, including immune mediated colitis. Due to the broad impact that NKT cells have on the immune system, there is intense interest in understanding how NKT cells are stimulated and the extent to which NKT cell responses can be controlled. These novel ligands are currently being evaluated in animal models of colitis. Here, we discuss strategies to alter NKT lymphocyte function in various settings and the potential clinical applications of natural glycolipids.

High-fat diet modulates non-CD1d-restricted natural killer T cells and regulatory T cells in mouse colon and exacerbates experimental colitis

Environmental factors such as diet are known to play important roles in inflammatory bowel disease (IBD). Epidemiological studies have indicated that a high-fat diet is a risk factor for IBD. In addition, the balance between effector T cells (T(eff)) and regulatory T cells (T(reg)) contributes to the pathogenesis of mucosal inflammation. The aim of this study was to understand the mechanisms by which a high-fat diet can regulate susceptibility to intestinal inflammation. Wild-type C57BL/6 mice were fed either a commercial high-fat diet or a normal diet, then exposed to dextran sulphate sodium (DSS) to induce colonic inflammation. Intraepithelial lymphocytes (IEL) were isolated from the colon, and their phenotype and cytokine profile were analysed by flow cytometry. Mice receiving the high-fat diet were more susceptible to DSS-induced colitis. They had higher numbers of non-CD1d-restricted natural killer (NK) T cells in the colonic IEL, when compared to mice fed a normal diet. These cells expressed tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, which are up-regulated by high-fat diets. Mice fed the high-fat diet also had decreased levels of colonic T(reg). Depletion of colonic NK T cells or adoptive transfer of T(reg) reduced the DSS colitis in these mice, and reduced the colonic expression of TNF-alpha and IFN-gamma. We conclude that a high-fat diet can increase non-CD1d-restricted NK T cells and decrease T(reg) in the colonic IEL population. This altered colonic IEL population leads to increased susceptibility to DSS-induced colitis. This effect may help to explain how environmental factors can increase the susceptibility to IBD.

Activation of invariant NK T cells protects against experimental rheumatoid arthritis by an IL-10-dependent pathway

Invariant natural killer T (iNKT) cells are a unique lymphocyte subtype implicated in the regulation of autoimmunity and a good source of protective Th2 cytokines. Agonist alpha-galactosylceramide (alpha-GalCer) of iNKT cells exert a therapeutical effect in type 1 diabetes. We investigated whether iNKT activation with alpha-GalCer was protective in collagen-induced arthritis (CIA) in DBA/1 mice, a standard model of rheumatoid arthritis. Here, we have shown that in vivo iNKT cell function was altered in DBA/1 mice since stimulation with alpha-GalCer led to decreased IL-4 and IFN-gamma levels in sera, as compared with C57BL/6 mice. alpha-GalCer induced a clear-cut diminution of clinical and histological arthritides. An anti-IL-10 receptor antibody abrogated the protective effect of alpha-GalCer, suggesting a key role for IL-10 in the protection against CIA by activated iNKT cells. Confirming these data, disease protection conferred by alpha-GalCer correlated with the ability of LN CD4+ cells to secrete larger amounts of IL-10. These findings suggest that in CIA susceptibility to autoimmunity is associated with dysfunctions of iNKT cells. Our demonstration that iNKT cell activation by alpha-GalCer remains efficient in CIA-prone DBA/1 mice to provide protective IL-10 suggests that this could be used therapeutically to treat autoimmune arthritis.

Amelioration of experimental colitis by Copaxone is associated with class-II-restricted CD4 immune blocking

Copaxone modifies TH1 immune response in multiple sclerosis. As Crohn's disease shares TH1 predominance, this study came to investigate the anti-inflammatory response of Copaxone in animal model of colitis.

METHODS

Colitis was induced by intra-rectal instillation of TNBS in 2 animal groups; one of them was daily treated intraperitoneally by 300 mug Copaxone starting 48 h post-colitis induction. Both colitis groups were compared to naive group. Eight male C57Bl6 mice were used in each group. At day 12, distal colon was excised for standard scoring, splenocytes were isolated for FACS and serum cytokines were assessed. Splenocytes were in-vitro-stimulated with colitis protein extracts in the presence or absence of Copaxone. Lymphocytes were blocked by either MHC anti-class I or anti-class II antibodies prior to Copaxone administration.

RESULTS

Copaxone markedly alleviated macro/microscopic colitis scoring as they decreased from 2.9 +/- 1.1/2.6 +/- 0.8 in colitis group to 1.7 +/- 1/1.5 +/- 0.5 in Copaxone-treated mice (P = 0.03/P = 0.008, respectively) compared to 0 +/- 0/1 +/- 0 in naives (P < 0.001/P < 0.01, respectively). CD4 subsets significantly decreased following Copaxone administration as compared to naive mice (P = 0.05). Although Copaxone-treated mice manifested a block of both serum TH1/TH2 responses, only interferon gamma secreting CD4 cells significantly decreased. NK cells tend to increase following colitis induction (P = 0.08), however, they significantly decreased in Copaxone-treated animals (P = 0.006). NK-T followed NK pattern. Using in vitro studies, Copaxone showed amelioration of T-cell proliferation that was significantly blocked when cells were pre-incubated with anti-MHC class II but not class I antibodies.

CONCLUSIONS

Copaxone had class-II-restricted anti-inflammatory effect in our animal colitis model associated with CD4/NK/NKT/TH1/TH2 suppression.

A Case for Regulatory B Cells

B cells are typically characterized by their ability to produce Abs, including autoantibodies. However, B cells possess additional immune functions, including the production of cytokines and the ability to function as a secondary APC. As with T cells, the B cell population contains functionally distinct subsets capable of performing both pathogenic and regulatory functions. Recent studies indicate that regulatory B cells develop in several murine models of chronic inflammation, including inflammatory bowel disease, rheumatoid arthritis, and experimental autoimmune encephalomyelitis. The regulatory function may be directly accomplished by the production of regulatory cytokines IL-10 and TGF-beta and/or by the ability of B cells to interact with pathogenic T cells to dampen harmful immune responses. In this review, we make a case for the existence of regulatory B cells and discuss the possible developmental pathways and functional mechanisms of these B cells.

Immunoregulation of Autoimmunity by Natural Killer T Cells

Natural killer T (NKT) cells are a conserved subpopulation of lymphocytes that recognize glycolipid antigens in a CD1d context. Upon activation through their semi-invariant T cell receptor, these cells rapidly release large amounts of immunomodulating Th1 and Th2 cytokines. NKT cells have therefore been implicated in immune responses controlling various diseases, including infection, cancer, transplantation, and autoimmunity. Stimulation of the immunoregulatory capacity of NKT cells by the prototypical antigen alpha-galactosylceramide results in amelioration of disease in several animal models. This review will focus on the current knowledge of human NKT cells and their role in autoimmune diseases. The features of these cells and their importance in regulation of autoimmunity suggest that NKT cell-based therapies might be an interesting approach for the treatment of autoimmune diseases.

Suppression of hepatocellular carcinoma by transplantation of ex-vivo immune-modulated NKT lymphocytes

NKT cells are a regulatory subset of T lymphocytes with immune modulatory effects and an important role in anti-tumor immunity. The feasibility of "ex-vivo education" of NKT cells has recently been demonstrated. To evaluate the anti-tumor effect of ex-vivo immune-modulated NKT lymphocytes in a murine model of hepatocellular carcinoma. Athymic Balb/C mice were sublethally irradiated and transplanted with human Hep3B HCC. NKT cells prepared from immunocompetent Balb/C mice were pulsed ex vivo with HCC-derived antigens (Group A), Hep3B cells (group B) or BSA (group C), and adoptively transferred into HCC harboring mice (1 x 0(6) NKT cells per mouse). Group D mice did not undergo NKT cell transplantation. Group E mice were transplanted with 1 x 10(6) NKT cells from HBV-immunized donors. Mice were followed for tumor size and weight. To determine the mechanism of the anti-tumor effect, intrasplenic lymphocyte populations were analyzed by FACS for NKT, CD4+ and CD8+ lymphocyte subpopulations; STAT 1, 4 and 6 expression in splenocytes was assessed by Western blot, and serum cytokine levels were measured by ELISA. Adoptive transfer of NKT cells pulsed with HCC-derived antigens (group A) and NKT cells from immunized donors (group E) resulted in complete disappearance of tumors within 4 weeks and attenuated weight loss (6.5% and 7% in groups A and E, respectively). In contrast, mice in groups B, C, and D developed large, necrotic tumors and severe weight loss (21%, 17% and 23% weight loss in groups B, C, and D, respectively). NKT/CD4 and CD8/CD4 ratios were significantly increased in groups A and E (12.3 and 17.6 in groups A and D, respectively, compared to 6.4, 4.8 and 5.6 in groups B, C and D, respectively, for the NKT/CD4 ratio; 41 and 19.8 in groups A and E, respectively, compared to 6.5, 11.8 and 3.2 in groups B, C, and D, respectively, for the CD8/CD4 ratio). Expression of the transcription factor STAT4 was evident in group A, but not in groups B-D. Serum IFNgamma, IL12 and IL4 levels were increased in groups A and E. Adoptive transfer of NKT lymphocytes exposed ex vivo by HCC-derived antigens loaded on dendritic cells and NKT cells from immunized donors led to suppression of HCC in mice. NKT-mediated anti-tumor activity was associated increased NKT and CD8+ T lymphocyte numbers, increased expression of STAT4, a marker for IL-12 activity and elevated serum levels of the proinflammatory cytokines IFNgamma and IL12, and of IL4. Ex-vivo modulation of NKT lymphocytes holds promise as a novel mode of immune therapy for HCC.

Induction of immune tolerance: a role for Natural killer T lymphocytes?

The ability of the immune system to distinguish between harmful and harmless antigens is essential for mounting protective immune responses and preventing the induction of pathology. Tolerance is a mechanism that prevents or suppresses potentially injurious immune responses. Natural killer T (NKT) lymphocytes, a subset of regulatory T lymphocytes, can induce pro-inflammatory or anti-inflammatory immune responses. This subset of cells appears to be crucial for induction of tolerance by several immune-modulatory interventions; these include immune manipulations in the setting of transplantation, induction of tolerance by introduction of antigen into immune-privileged sites, and oral administration of disease-associated-antigen. The ability to predict whether tolerance or immunity will be generated in a given situation is essential for development of NKT lymphocyte-based immune-modulatory treatments. The role of NKT lymphocytes in these settings, and the requirements for development of tolerance, rather than immunity, are discussed.

Adoptive transfer of NK 1.1+ lymphocytes in immune-mediated colitis: a pro-inflammatory or a tolerizing subgroup of cells?

T lymphocytes expressing NK1.1 marker (NKT) have been suggested to play crucial roles in immune modulation.

AIM

To determine the role of NK1.1+ cells in induction and maintenance of pro-inflammatory and/or tolerizing responses.

METHODS

Colitis was induced in C57/B6 donor mice by intracolonic instillation of trinitrobenzenesulfonic acid (TNBS). Donor mice received five oral doses of colonic proteins extracted from TNBS-colitis colonic wall. Depletion of NK1.1+ lymphocytes was performed before lymphocyte harvesting. Splenocytes were harvested and separated into T-cell subpopulations, and transplanted into recipient mice before intracolonic instillation of TNBS. Standard clinical, macroscopic, and microscopic scores, and intracellular staining, flow cytometry, and cytotoxicity assays were performed.

RESULTS

The adoptive transfer of CD4+ and NK1.1+ cells harvested from tolerized mice markedly ameliorated the colitis in recipient mice. In contrast, the adoptive transfer of CD8+ and double negative lymphocytes failed to transfer the tolerance. Recipients of splenocytes from tolerized mice exhibited an increase in CD4+ IL4+/CD4+ IFNgamma+ ratio. In contrast, recipients of splenocytes from NK1.1-depleted-tolerized mice exhibited severe colitis with a significant decrease of the CD4+ IL4+/CD4+ IFNgamma+ ratio. However adoptive transfer of splenocytes from non-tolerized NKT-depleted mice led to an alleviation of colitis with a relative increase of the CD4+ IL4+/CD4+ IFNgamma+ ratio.

CONCLUSIONS

NK1.1+ lymphocytes play a critical role in immune regulation. They may be accountable for an alteration of the inflammatory response and the CD4+ IL4+/CD4+ IFNgamma ratio immune-mediated colitis and in peripheral tolerance induction.