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INTERLEUKIN 15 PREPROPROTEIN
LATEST LITERATURE
1: Experimental parasitology, 2010 Aug 2,
Vaccination of Chickens with DNA Vaccine Encoding Eimeria acervulina 3-1E and Chicken IL-15 Offers Protection Against Homologous Challenge.
[Abstract]Eimeria acervulina 3-1E antigen gene and mature chicken interleukin 15 (mChIL-15) gene were cloned into expression vector pcDNA3.1(+) in different forms, produced DNA vaccine pcDNA3.1-3-1E, and pcDNA3.1-3-1E-linker-mChIL-15 co-expressing E. acervulina 3-1E gene and mChIL-15 gene, respectively. The expression of objective gene in vitro was detected by indirect fluorescent antibody technique and immunohistochemistry. The two DNA vaccines were administered by intramuscular leg injection. An animal challenge experiment was carried out to evaluate the immune protective efficacy of the vaccines. The results indicated that DNA vaccines were successfully constructed and the expression of objective gene could be detected in vitro. The animal experimental results showed that both DNA vaccines could provide partial protection against homologous challenge in chickens. The chimeric DNA vaccine, pcDNA3.1-3-1E-linker-mChIL-15, could significantly increase oocyst decrease ratio, reduce the average lesion score in the duodenum, improve body weight gain, and increase anti-coccidial index (ACI) compared to the DNA vaccine pcDNA3.1-3-1E. Taken together, these results demonstrate ChIL-15 enhance the immunogenicity of 3-1E DNA vaccine, and co-expression of cytokine and optimized surface antigen of Eimeria may be a promising method to enhance immunogenicity of DNA vaccines in poultry.
2: Journal of molecular cell biology, 2010 Aug, 2(4)
IL-15R{alpha}-IgG1-Fc Enhances IL-2 and IL-15 Anti-tumor Action through NK and CD8+ T Cells Proliferation and Activation.
[Abstract]Natural killer (NK) cells-based immunotherapy is one of the most promising treatments for incurable malignant tumors. NK cells in combination with monoclonal antibodies to surface antigens of the tumor cell have been proved to be effective in a number of clinical trials. A limiting step in the development of successful cellular immunotherapy lies in developing an efficient and economic method to expand appropriate amount of NK cells and CD8(+) T cells. In this study, we constructed a humanized IL-15Ralpha-IgG1-Fc, which mimicked IL-15 trans-presentation. The feasibility of expanding populations of the human NK and CD8(+) T cells by IL-15Ralpha-IgG1-Fc complexes was tested. We then measured the cytotoxicity of expanded NK and CD8(+) T cells against tumor cell lines and primary tumor cells. When tested ex vivo, IL-2/IL-15Ralpha-IgG1-Fc complexes significantly enhanced NK and CD8(+) T cells expansion, isolated or non-isolated from PBMCs. The effect of IL-15Ralpha-IgG1-Fc was dependent on the presence of IL-2 or IL-15. IL-15Ralpha-IgG1-Fc complexes increased NK, CD8(+) T and NKT cells ratio in PBMC and BMMC after 14 days incubation. High level of granzyme B expression was observed in the supernatant of the complexes-treated NK cells. Expanded NK and CD8(+) T cell populations had cytotoxic function against the PC3, LNCaP, K562 and chronic lymphocytic leukemia (CLL) patient primary B cell lymphoma. We concluded that IL-2/IL-15Ralpha-IgG1-Fc significantly enhanced NK, CD8(+) T and NKT cells expansion, which possess strong anti-tumor activity. These data support clinical testing IL-2/IL-15Ralpha-IgG1-Fc expanded NK cells in patients with prostate cancer and CLL.
3: Blood, 2010 Jul 14, 185(2)
Transient and persistent effects of IL15 on lymphocyte homeostasis in nonhuman primates.
[Abstract]IL-15 is a cytokine with potential therapeutic application in individuals with cancer or immunodeficiency to promote NK- and T-cell activation and proliferation or in vaccination protocols to generate long-lived memory T-cells. Here we report that 10-50 microg/kg of IL-15 administered intravenously daily for 12 days to rhesus macaques has both short- and long-lasting effects on T-cell homeostasis. Peripheral blood lymphopenia preceded a dramatic expansion of NK-cells and memory CD8 T-cells in the circulation, particularly a fourfold expansion of central memory CD8 T-cells and a sixfold expansion of effector memory CD8 T-cells. This expansion is a consequence of their activation in multiple tissues. A concomitant inverted CD4/CD8 T-cell ratio was observed throughout the body at day 13, a result of preferential CD8 expansion. Expanded T and NK-cell populations declined in the blood soon after IL-15 was stopped, suggesting migration to extralymphoid sites. By day 48, homeostasis appears restored throughout the body with the exception of the maintenance of an inverted CD4/CD8 ratio in lymph nodes. Thus, IL-15 generates a dramatic expansion of short-lived memory CD8 T-cells and NK-cells in immunocompetent macaques and has long-term effects on the balance of CD4(+) and CD8(+) T-cells.
4: Immunobiology, 2010 May 13, 107(20)
Characterization and IL-15 dependence of NK cells in humanized mice.
[Abstract]Natural Killer cells can distinguish between healthy and malignant cells and have the unique ability to lyse tumour cells without prior sensitization. Differences between murine and human NK cells complicate the translation of this knowledge into useful therapeutics. Humanized mouse models that support the development of human leukocytes are a promising avenue of research that aims to address this problem. Here we provide an in-depth phenotypic analysis of human NK cells in Balb/c Rag2(-/-)gamma(c)(-/-) mice reconstituted with human hematopoietic stem cells. We have examined the development of NK cells in bone marrow, thymous, spleen, lymph node (LN) and liver. Interestingly, in naive reconstituted mice, NK cells were found in thymus and LN, but not in bone marrow. These NK cells expressed several inhibitory and activating receptors needed for malignant cell detection. Furthermore, we confirm that administration of recombinant human interleukin-15 (rhIL-15) or Ad-vector expressing hIL-15 is able to significantly enhance NK cell development and maturation, particularly in bone marrow and liver, in this model. Our results suggest that human NK cells developed in mice may have phenotypes and tissue distributions similar to those seen in human.
5: Arthritis and rheumatism, 2010 Jul 8, 185(2)
Inhibition of T cell-dependent and rankl-dependent osteoclastogenic processes associated with high bone mass in IL-15 receptor-deficient mice.
[Abstract]OBJECTIVE:: T-cell production of RANKL, IFN-gamma and other cytokines in inflammatory processes such as rheumatoid arthritis (RA), or secondary to estrogen-deficiency, stimulates osteoclastic activity leading to bone resorption and bone loss. We characterized the effects of interleukin-15 (IL-15), a master T-cell growth factor whose role on bone remodeling remains unknown. METHODS:: By using mice lacking the IL-15 receptor (IL-15Ralpha(-/-)), we investigated the effects of IL-15 on osteoclast (OC) development, T-cell and DC activation in vitro and in vivo, bone mass and microarchitecture in intact and ovariectomized (OVX) mice. RESULTS:: In wild-type (WT) animals, IL-15 and RANKL provided a co-stimulatory signal for OC development. Spleen of IL-15Ralpha(-/-) mice contained few c-Kit(+) OC precursors, and NFATc1 expression and osteoclastogenic response to RANKL were impaired. In addition, the DC- and T cell-dependent mechanisms of OC activation, including RANKL and IFN-gamma production, were impaired in IL-15Ralpha(-/-) mice. In turn, IL-15Ralpha(-/-) T cells failed to stimulate WT OC whilst WT T cells failed to stimulate IL-15Ralpha(-/-) OC. Compared to WT, both intact and OVX IL-15Ralpha(-/-) mice had significantly greater bone mineral density and microarchitecture, including a higher trabecular bone volume fraction (BV/TV) and cortical thickness. Osteoclast number on bone surface and markers of bone turnover were significantly decreased in IL-15Ralpha(-/-) mice. CONCLUSIONS:: In the absence of IL-15 signaling, several converging mechanisms of osteoclastogenesis are inhibited, both directly and indirectly through T cells, leading to a high bone mass phenotype. Targeting the IL-15 pathway may represent a novel therapeutic approach in treating primary and secondary osteoporosis.
6: Vaccine, 2010 Jun 11, 184(12)
BAFF, stimulatory DNA and IL-15 stimulates IgA(+) memory B cells and provides a novel approach for analysis of memory responses to mucosal vaccines.
[Abstract]Assessment of immune responses induced by mucosal vaccines is to a large extent based on measurement of IgA levels in mucosal secretions and detection of short-lived effector IgA-secreting cells circulating in peripheral blood. Since these immunological parameters poorly reflect long-term IgA-mediated responses, we sought to investigate novel approaches that would enable detection of vaccine specific IgA memory B cells. We demonstrate that stimulation of human peripheral blood mononuclear cells in vitro with immunostimulatory DNA in combination with B cell-activating factor (BAFF) and IL-15 promotes differentiation of IgA memory B cells to IgA-secreting cells. By using the inactivated oral cholera vaccine Dukoral((R)) we demonstrate that vaccine specific IgA memory B cells are induced by oral immunization and are circulating for at least 9 months after vaccination. We also show that stimulated IgA memory B cells do not secrete IgA unless they reencounter the specific antigen.
7: Human immunology, 2010 May 24, 41(2)
Effects of IL-15 on human CD3-CD117+CD56-OX40L+ cell differentiation.
[Abstract]Lymphoid tissue inducer (LTi) cells are essential for secondary lymphoid tissue development and recently identified human LTi cells are closely related to natural killer (NK) cells. In this study, we investigate whether human CD3(-)CD117(+)CD56(-) cells that include LTi and immature NK cells respond to IL-15 which is an NK cell growth factor. In the presence of IL-15, CD3(-)CD117(+)CD56(-) cells proliferate and downregulate the expression of OX40L and mRNA for IL-22, lymphotoxin-alpha, and aryl hydrocarbon receptor, but not Id2. To examine whether CD3(-)CD117(+)CD56(-) cells differentiate into CD3(-)CD117(+)CD56(+) NK cells by IL-15, we sorted CD3(-)CD117(+)CD56(-)OX40L(+) cells and cultured with IL-15 for 7 days. ~75% of the cells differentiated into imterferon-gamma-expressing CD56(+) cells and ~25% of the cells did not. In addition, the latter population expressed LTi markers including lymphotoxin-alpha and RORC. These results show that ~25% of CD3(-)CD117(+)CD56(-)OX40L(+) cells are LTi cells and do not differentiate into CD56(+) NK cells by IL-15.
8: The Journal of clinical investigation, 2010 May 3, 41(2)
IL-15 triggers an antiapoptotic pathway in human intraepithelial lymphocytes that is a potential new target in celiac disease-associated inflammation and lymphomagenesis.
[Abstract]Enteropathy-associated T cell lymphoma is a severe complication of celiac disease (CD). One mechanism suggested to underlie its development is chronic exposure of intraepithelial lymphocytes (IELs) to potent antiapoptotic signals initiated by IL-15, a cytokine overexpressed in the enterocytes of individuals with CD. However, the signaling pathway by which IL-15 transmits these antiapoptotic signals has not been firmly established. Here we show that the survival signals delivered by IL-15 to freshly isolated human IELs and to human IEL cell lines derived from CD patients with type II refractory CD (RCDII) - a clinicopathological entity considered an intermediary step between CD and enteropathy-associated T cell lymphoma - depend on the antiapoptotic factors Bcl-2 and/or Bcl-xL. The signals also required IL-15Rbeta, Jak3, and STAT5, but were independent of PI3K, ERK, and STAT3. Consistent with these data, IELs from patients with active CD and RCDII contained increased amounts of Bcl-xL, phospho-Jak3, and phospho-STAT5. Furthermore, incubation of patient duodenal biopsies with a fully humanized human IL-15-specific Ab effectively blocked Jak3 and STAT5 phosphorylation. In addition, treatment with this Ab induced IEL apoptosis and wiped out the massive IEL accumulation in mice overexpressing human IL-15 in their gut epithelium. Together, our results delineate the IL-15-driven survival pathway in human IELs and demonstrate that IL-15 and its downstream effectors are meaningful therapeutic targets in RCDII.
9: Blood, 2010 Apr 29, 38(5)
Virally-infected and matured human dendritic cells activate natural killer cells via cooperative activity of plasma membrane-bound TNF and IL-15.
[Abstract]Recombinant adenovirus-engineered dendritic cells (Ad.DC) are potent immunologic adjuvant of anti-viral and anti-cancer vaccines. The effectiveness of Ad.DC-based vaccines may depend on the ability of Ad.DC to crosstalk with natural killer (NK) cells and to activate, polarize, and bridge innate and adaptive immunity. We investigated for the first time whether and how human Ad.DC activate NK cells, and compared the Ad.DC function with that of immature DC (iDC) and matured DC (mDC). We found that adenovirus transduction and LPS/IFN-gamma-induced maturation increased expression of transmembrane (tm) TNF and trans-presented (trans) IL-15 on DC, leading to enhanced NK cell activation without enhancing DC susceptibility to NK cell-mediated killing. This crosstalk enhanced NK cell CD69 expression, IFN-gamma secretion, proliferation and antitumor activities, with Ad.DC being significantly more effective than iDC, but less effective than mDC. The Ad.DC and mDC crosstalk with NK cells was largely prevented by physical separation of DC and NK cells, and neutralization of total TNF and IL-15, but not by selective sequestration of soluble TNF. These findings demonstrate that both Ad.DC and mDC can efficiently promote innate immune functions by activation of NK cells through the cooperative activities of tmTNF and trans-IL-15 mediated by cell-to-cell contact.
10: Journal of immunology (Baltimore, Md. : 1950), 2010 Apr 28, 38(5)
Cytotoxic Potential of Lung CD8+ T Cells Increases with Chronic Obstructive Pulmonary Disease Severity and with In Vitro Stimulation by IL-18 or IL-15.
[Abstract]Lung CD8(+) T cells might contribute to progression of chronic obstructive pulmonary disease (COPD) indirectly via IFN-gamma production or directly via cytolysis, but evidence for either mechanism is largely circumstantial. To gain insights into these potential mechanisms, we analyzed clinically indicated lung resections from three human cohorts, correlating findings with spirometrically defined disease severity. Expression by lung CD8(+) T cells of IL-18R and CD69 correlated with severity, as did mRNA transcripts for perforin and granzyme B, but not Fas ligand. These correlations persisted after correction for age, smoking history, presence of lung cancer, recent respiratory infection, or inhaled corticosteroid use. Analysis of transcripts for killer cell lectin-like receptor G1, IL-7R, and CD57 implied that lung CD8(+) T cells in COPD do not belong to the terminally differentiated effector populations associated with chronic infections or extreme age. In vitro stimulation of lung CD8(+) T cells with IL-18 plus IL-12 markedly increased production of IFN-gamma and TNF-alpha, whereas IL-15 stimulation induced increased intracellular perforin expression. Both IL-15 and IL-18 protein expression could be measured in whole lung tissue homogenates, but neither correlated in concentration with spirometric severity. Although lung CD8(+) T cell expression of mRNA for both T-box transcription factor expressed in T cells and GATA-binding protein 3 (but not retinoic acid receptor-related orphan receptor gamma or alpha) increased with spirometric severity, stimulation of lung CD8(+) T cells via CD3epsilon-induced secretion of IFN-gamma, TNF-alpha, and GM-CSF, but not IL-5, IL-13, and IL-17A. These findings suggest that the production of proinflammatory cytokines and cytotoxic molecules by lung-resident CD8(+) T cells contributes to COPD pathogenesis.
11: Blood, 2010 Mar 22, 222(2)
c-Myc controls the development of CD8{alpha}{alpha} TCR{alpha}{beta} intestinal intraepithelial lymphocytes from thymic precursors by regulating IL-15-dependent survival.
[Abstract]The murine gut epithelium contains a large population of thymus derived intraepithelial lymphocytes (IEL) including both conventional CD4(+) and CD8alphabeta(+) T cells (expressing TCRalphabeta) and unconventional CD8alphaalpha(+) T cells (expressing either TCRalphabeta or TCRgammadelta). Whereas conventional IEL are widely accepted to arise from recirculation of activated CD4(+) and CD8alphabeta(+) T cells from the secondary lymphoid organs to the gut the origin and developmental pathway of unconventional CD8alphaalpha IEL remains controversial. We show here that CD4-Cre-mediated inactivation of c-Myc, a broadly expressed transcription factor with a wide range of biological activities, selectively impairs the development of CD8alphaalpha TCRalphabeta IEL. In the absence of c-Myc, CD4(-) CD8(-) TCRalphabeta(+) thymic precursors of CD8alphaalpha TCRalphabeta IEL are present but fail to develop upon adoptive transfer in immunoincompetent hosts. Residual c-Myc-deficient CD8alphaalpha TCRalphabeta IEL display reduced proliferation and increased apoptosis which correlate with significantly decreased expression of interleukin-15 receptor (IL-15R) subunits and lower levels of the anti-apoptotic protein Bcl-2. Transgenic overexpression of human BCL-2 resulted in a pronounced rescue of CD8alphaalpha TCRalphabeta IEL in c-Myc-deficient mice. Taken together our data support a model in which c-Myc controls the development of CD8alphaalpha TCRalphabeta IEL from thymic precursors by regulating IL-15R expression and consequently Bcl-2-dependent survival.
12: European journal of immunology, 2010 Mar 8, 28(12)
IL-18, but not IL-15, contributes to the IL-12-dependent induction of NK cell effector functions by Leishmania infantum in vivo.
[Abstract]Activation of NK cells is a hallmark of infections with intracellular pathogens. We previously showed that the protozoan parasite Leishmania infantum triggered a rapid NK cell response in mice that required TLR9-positive myeloid DC and IL-12, but no IFN-alpha/beta. Here, we investigated whether IL-15 or IL-18 mediate the activity of IL-12 or function as independent activators of NK cells. In contrast to earlier studies that described IL-15 as crucial for NK cell priming in response to TLR ligands, the expression of IFN-gamma, FasL, perforin and granzyme B by NK cells in L. infantum-infected mice was completely preserved in the absence of IL-15, whereas the proliferative capacity of NK cells was lower than in WT mice. IFN-gamma secretion, cytotoxicity and FasL expression of NK cells from infected IL-18(-/-) mice were significantly reduced compared to controls, but, unlike IL-12, IL-18 was not essential for NK cell effector functions. Part of the NK cell-stimulatory effect of IL-12 was dependent on IL-18. We conclude that IL-15 is not functioning as a universal NK cell priming signal and that IL-18 contributes to the NK cell response in visceral leishmaniasis. The cytokine requirements for NK cell activation appear to differ contingent upon the infectious pathogen.
13: The Journal of experimental medicine, 2010 Mar 8, 28(12)
IL-15 trans-presentation by pulmonary dendritic cells promotes effector CD8 T cell survival during influenza virus infection.
[Abstract]We have recently demonstrated that peripheral CD8 T cells require two separate activation hits to accumulate to high numbers in the lungs after influenza virus infection: a primary interaction with mature, antigen-bearing dendritic cells (DCs) in the lymph node, and a second, previously unrecognized interaction with MHC I-viral antigen-bearing pulmonary DCs in the lungs. We demonstrate that in the absence of lung-resident DC subsets, virus-specific CD8 T cells undergo significantly increased levels of apoptosis in the lungs; however, reconstitution with pulmonary plasmacytoid DCs and CD8alpha(+) DCs promotes increased T cell survival and accumulation in the lungs. Further, our results show that the absence of DCs after influenza virus infection results in significantly reduced levels of IL-15 in the lungs and that pulmonary DC-mediated rescue of virus-specific CD8 T cell responses in the lungs requires trans-presentation of IL-15 via DC-expressed IL-15Ralpha. This study demonstrates a key, novel requirement for DC trans-presented IL-15 in promoting effector CD8 T cell survival in the respiratory tract after virus infection, and suggests that this trans-presentation could be an important target for the development of unique antiviral therapies and more effective vaccine strategies.
14: Vaccine, 2010 Jan 8, 58(3)
An IL-15 adjuvant enhances the efficacy of a combined DNA vaccine against Brucella by increasing the CD8(+) cytotoxic T cell response.
[Abstract]We investigated whether a combined DNA vaccine delivered together with the IL-15 gene (DNA-IL-15(+)) enhanced the immune response against Brucella abortus in mice. Mice vaccinated with DNA-IL-15(+) developed a robust humoral response; Brucella-specific antibodies exhibited a dominance of immunoglobulin G2a (IgG2a) over IgG1. Splenocytes from DNA-IL-15(+)-vaccinated mice induced significantly higher levels of IFN-gamma (P<0.01) and CD8(+) T cell response (P<0.01), suggesting induction of a T-helper-1-dominated immune response. In a specific cytotoxic-T-lymphocyte activity assay, DNA-IL-15(+) immunization elicited mainly CD8(+) T cells, which mediate cytotoxicity, but also CD4(+) T cells. In vivo depletion of T cell subsets showed that the DNA-IL-15(+)-induced protection against Brucella infection is mediated predominantly by CD8(+) T cells, although CD4(+) T cells also contribute. These data indicate that plasmid-delivered IL-15 increases the efficacy of the Brucella DNA vaccine.
15: Journal of molecular neuroscience : MN, 2009 Dec 10, 183(12)
IL-15 Receptor Deletion Results in Circadian Changes of Locomotor and Metabolic Activity.
[Abstract]Interleukin-15 (IL-15) is a cytokine produced in the normal brain that acts on its specific receptor IL-15Ralpha and co-receptors IL-2Rbeta and IL-2Rgamma in neuronal cells. The functions of the cerebral IL-15 system, however, are not yet clear. To test the hypothesis that IL-15Ralpha regulates metabolic activity and body temperature, we quantified the specific metabolic phenotype of IL-15Ralpha knockout mice. These normal-appearing mice were leaner with lower fat composition. During the entire circadian cycle, the knockout mice had a significantly higher acrophase in locomotor activity and heat dissipation. During the light phase, there was significantly greater food intake, oxygen consumption, and carbon dioxide production. The difference in the dark and light phases suggests that IL-15Ralpha participates in circadian rhythm regulation. The higher oxygen consumption in the light phase indicates adaptive thermogenesis in the knockout mice. The body temperature of the receptor knockout mice was significantly higher than the control in the light phase, and this was mainly caused by a large difference occurring between 0600 and 0900 h. In addition to the metabolic chamber studies and circadian rhythm analyses, qPCR of hypothalamic homogenates indicated higher mRNA expression of orexin and transient receptor potential vanilloid 4 cation channels. Consistent with a direct role of IL-15Ralpha in the hypothalamus, IL-15 treatment of the wild-type mice induced c-Fos expression in the preoptic area. We conclude that activation of hypothalamic neurons by IL-15 in mice contributes to thermoregulation and modifies the metabolic phenotype.
16: Journal of immunology (Baltimore, Md. : 1950), 2009 Dec 15, 183(12)
A Dual Action of Rheumatoid Arthritis Synovial Fibroblast IL-15 Expression on the Equilibrium between CD4+CD25+ Regulatory T Cells and CD4+CD25- Responder T Cells.
[Abstract]We previously described that fibroblast-like cells from the synovium of rheumatoid arthritis patients (RASFib) constitutively express intracellular and surface IL-15, which induces activation of cocultured T cells. Our objective was to study the effect of RASFib IL-15 expression on the function of human CD4(+)CD25(+) regulatory T cells (Treg). RASFib, through their constitutive IL-15 expression, were able to induce the proliferation of human Tregs stimulated through their TCR, and at the same time potentiated their suppressive action on the cytokine secretion of CD4(+)CD25(-) responder T cells (Tresp). In parallel, constitutive RASFib IL-15 expression mediated an up-regulated response of Tresp. Subsequently, total CD4(+) T cells, containing natural proportions of Treg and Tresp, secreted an increased amount of pathogenic cytokines when cocultured with RASFib despite the presence of proliferating Treg with superior regulatory potency. In summary, RASFib IL-15 exerts a dual action on the equilibrium between Treg and Tresp by potentiating the suppressive effect of Treg while augmenting the proinflammatory action of Tresp; the result is a shift of the Treg/Tresp balance toward a proinflammatory state. This alteration of the Treg/Tresp equilibrium is not observed in the presence of osteoarthritis synovial fibroblasts or dermal fibroblasts, which do not constitutively express surface IL-15. Additionally, Treg with superior suppressive potency were present in the peripheral blood and the synovial fluid of RA patients, but this enhanced immunoregulatory activity was not able to overcome the increased secretion of pathogenic cytokines by RA-Tresp, indicating that rheumatoid arthritis patients demonstrate an altered Treg/Tresp equilibrium in vivo.
17: Immunology and cell biology, 2009 Dec 1,
Evidence of STAT5-dependent and -independent routes to CD8 memory formation and a preferential role for IL-7 over IL-15 in STAT5 activation.
[Abstract]Interleukin (IL)-7 and IL-15 have non-redundant roles in promoting development of memory CD8(+) T cells. STAT5 is activated by receptors of both cytokines and has also been implicated as a requirement for generation of memory. To determine whether STAT5 activity was required for IL-7 and IL-15-mediated generation of memory, we expressed either wild type (WT) or constitutively active (CA) forms of STAT5a in normal effector cells and then observed their ability to form memory in cytokine replete or deficient hosts. Receptor-independent CA-STAT5a significantly enhanced memory formation in the absence of either cytokine but did not mediate complete rescue. Interestingly, WT-STAT5a expression enhanced memory formation in a strictly IL-7-dependent manner, suggesting that IL-7 is a more potent activator of STAT5 than IL-15 in vivo. These data suggest that the non-redundant requirement for IL-7 and IL-15 is mediated through differential activation of both STAT5-dependent and STAT5-independent pathways.Immunology and Cell Biology advance online publication, 1 December 2009; doi:10.1038/icb.2009.95.
18: Journal of immunology (Baltimore, Md. : 1950), 2009 Nov 30,
IL-15 Regulates Both Quantitative and Qualitative Features of the Memory CD8 T Cell Pool.
[Abstract]Memory T cells are critical for immunity to various intracellular pathogens. Recent studies have indicated that CD8 secondary memory cells, induced by prime-boost approaches, show enhanced protective function compared with primary memory cells and exhibit phenotypic and functional characteristics that distinguish them from primary memory cells. However, little is known about the cytokine requirements for generation and maintenance of boosted memory CD8 T cells. We studied the role of IL-15 in determining the size and composition of the secondary (2 degrees ) memory CD8 T cell pool induced by Listeria monocytogenes infection in mice. Following boosting, IL-15-deficient animals failed to generate a subset of CD8 effector memory cells, including a population of IL-7Ralpha(low) cells, which were prominent among secondary memory cells in normal mice. IL-15 deficiency also resulted in changes within the IL-7Ralpha(high)CD62L(low) subset of 2 degrees memory CD8 T cells, which expressed high levels of CD27 but minimal granzyme B. In addition to these qualitative changes, IL-15 deficiency resulted in reduced cell cycle and impaired Bcl-2 expression by 2 degrees memory CD8 T cells, suggesting a role for IL-15 in supporting both basal proliferation and survival of the pool. Analogous qualitative differences in memory CD8 T cell populations were observed following a primary response to Sendai virus in IL-15(-/-) animals. Collectively, these findings demonstrate that IL-15 plays an important role in dictating the composition rather than simply the maintenance of the CD8 memory pool.
19: Gene therapy, 2009 Oct 29, 68(1)
Proliferating NK cells in response to IL-15 do not upregulate surface B220 in vivo.
[Abstract]The physiological activities of Interleukin-15 (IL-15) suggest that it could be useful as an immunomodulator to activate the innate immune system, however, the expression and purification yields of recombinant mature IL-15 have typically been low. In this report, a method was optimised to generate milligram quantities of this cytokine. Human IL-15 with an N-terminal (His)(6)-tag was expressed in Escherichia coli as an insoluble protein. The IL-15 material was purified from other cellular proteins by dissolution in 6M guanidine HCl, followed by Ni-NTA chromatography in a buffer containing 8M urea. Use of a multi-component screen identified the optimal conditions for folding (His)(6)-tagged human IL-15 and the method was scaled up to produce milligram quantities of folded material in its native conformation, with two intra-molecular disulphides as determined by electrospray mass spectrometry. Mature IL-15 was generated by cleavage with recombinant enterokinase, which was subsequently removed by Ni-NTA chromatography. Identical methods were used to produce mature cynomolgus monkey (Macaca fascicularis) IL-15 in similar quantities. Human and cynomolgus IL-15 were both active in two IL-15 dependent assays; mouse CTLL2 cell proliferation and human and cynomolgus CD69 upregulation on CD3(-) CD8+ lymphocytes in whole blood. Despite being 96% identical at the amino acid level the human IL-15 was 10-fold more potent than the cynomolgus IL-15 in both assays. The methods described here are useful for producing both mature IL-15 proteins in sufficient quantity for in vivo and in vitro studies, including X-ray crystallography.
20: Proceedings of the National Academy of Sciences of the United States of America, 2009 Sep 15, 106(37)
Antibody-mediated blockade of IL-15 reverses the autoimmune intestinal damage in transgenic mice that overexpress IL-15 in enterocytes.
[Abstract]Celiac disease (CD) is an autoimmune inflammatory disease with a relatively high prevalence especially in the western hemisphere. A strong genetic component is involved in the pathogenesis of CD with virtually all individuals that develop the disease carrying HLA-DQ alleles that encode specific HLA-DQ2 or HLA-DQ8 heterodimers. Consumption of cereals rich in gluten triggers a chronic intestinal inflammation in genetically susceptible individuals leading to the development of CD. Emerging evidence has implicated a central role for IL-15 in the orchestration and perpetuation of inflammation and tissue destruction in CD. Therefore, IL-15 represents an attractive target for development of new therapies for CD. Transgenic mice that express human IL-15 specifically in enterocytes (T3(b)-hIL-15 Tg mice) develop villous atrophy and severe duodeno-jejunal inflammation with massive accumulation of NK-like CD8(+) lymphocytes in the affected mucosa. We used these mice to demonstrate that blockade of IL-15 signaling with an antibody (TM-beta1) that binds to murine IL-2/IL-15Rbeta (CD122) leads to a reversal of the autoimmune intestinal damage. The present study, along with work of others, provides the rationale to explore IL-15 blockade as a test of the hypothesis that uncontrolled expression of IL-15 is critical in the pathogenesis and maintenance of refractory CD.
21: Calcified tissue international, 2009 Sep 11, 106(37)
Association of IL-15 Polymorphisms with Bone Mineral Density in Postmenopausal Korean Women.
[Abstract]Interleukin-15 (IL-15) has been suggested to participate in bone metabolism by stimulating osteoclast differentiation and mediating inflammatory bone loss. This study investigated the effect of IL-15 gene polymorphisms on the bone mineral density (BMD) and bone fracture rates of postmenopausal women. Sequencing of the IL-15 gene in 24 Koreans revealed 16 single-nucleotide polymorphisms (SNPs), of which five were selected for further study. Postmenopausal Korean women (n = 844) were genotyped for these SNPs, and their BMDs and risk of fractures were assessed. It was found that the +20A > G, +13467C > A, +13653A > T, and +13815A > T IL-15 gene polymorphisms were significantly associated with the BMD of the lumbar spine and femoral neck and that their effects were gene-dose dependent. BMD was reduced when the minor allele of +13467A and +13653T or the common allele of +20A and +13815A was present. Haplotype (ht) analyses revealed that ht1 (GCAT) and ht2 (AATA) were associated with BMD of the lumbar spine and femoral neck. However, there was no association between the risk of fracture and IL-15 SNPs or hts. These results suggest that the +20A > G, +13467C > A, +13653A > T, and +13815A > T SNPs in the IL-15 gene affect BMD and, thus, could be genetic markers of osteoporosis.
22: Journal of immunology (Baltimore, Md. : 1950), 2009 Sep 15, 183(6)
Cutting edge: TGF-beta1 and IL-15 Induce FOXP3+ gammadelta regulatory T cells in the presence of antigen stimulation.
[Abstract]Several subsets of alphabeta regulatory T cells (Tregs) have been described and studied intensively, but the potential regulatory role of gammadelta T cells remains largely unclear. Lymphocytes expressing gammadelta TCR are involved in both innate and adaptive immune responses, and their major adult human peripheral blood subset (Vgamma9Vdelta2) displays a broad reactivity against microbial agents and tumors. In this study we report that gammadelta T lymphocytes with regulatory functions (Vdelta2 Tregs) are induced in vitro in the presence of specific Ag stimulation and cytokines (TGF-beta1 and IL-15). These cells express FOXP3 and, similarly as alphabeta Tregs, suppress the proliferation of anti-CD3/anti-CD28 stimulated-PBMC. Phenotypic and functional analyses of Vdelta2 Tregs will very likely improve our understanding about the role of gammadelta T cells in the pathogenesis of autoimmune, infectious, and neoplastic diseases.
23: Glia, 2010 Feb, 58(3)
Blockade of IL-15 activity inhibits microglial activation through the NFkappaB, p38, and ERK1/2 pathways, reducing cytokine and chemokine release.
[Abstract]Reactive glia formation is one of the hallmarks of damage to the CNS, but little information exists on the signals that direct its activation. Microglial cells are the main regulators of both innate and adaptative immune responses in the CNS. The proinflammatory cytokine IL-15 is involved in regulating the response of T and B cells, playing a key role in regulating nervous system inflammatory events. We have used a microglial culture model of inflammation induced by LPS and IFNgamma to evaluate the role of IL-15 in the proinflammatory response. Our results indicate that IL-15 is necessary for the reactive response, its deficiency (IL-15-/-) leading to the development of a defective proinflammatory response. Blockade of IL-15, both with blocking antibodies or with the ganglioside Neurostatin, inhibited the activation of the NFkappaB pathway, decreasing iNOS expression and NO production. Inhibiting IL-15 signaling also blocked the activation of the mitogen-activated protein kinase (MAPK) pathways ERK1/2 and p38. The major consequence of these inhibitory effects, analyzed using cytokine antibody arrays, was a severe decrease in the production of chemokines, cytokines and growth factors, like CCL17, CCL19, IL-12, or TIMP-1, that are essential for the development of the phenotypic changes of glial activation. In conclusion, activation of the IL-15 system seems a necessarystep for the development of glial reactivity and the regulation of the physiology of glial cells. Modulating IL-15 activity opens the possibility of developing new strategies to control gliotic events upon inflammatory stimulation. (c) 2009 Wiley-Liss, Inc.
24: Blood, 2009 Sep 17, 114(12)
Safety and immunologic effects of IL-15 administration in nonhuman primates.
[Abstract]The administration of cytokines that modulate endogenous or transferred T-cell immunity could improve current approaches to clinical immunotherapy. Interleukin-2 (IL-2) is used most commonly for this purpose, but causes systemic toxicity and preferentially drives the expansion of CD4(+)CD25(+)Foxp3(+) regulatory T cells, which can inhibit antitumor immunity. IL-15 belongs to the gamma(c) cytokine family and possesses similar properties to IL-2, including the ability to induce T-cell proliferation. Whereas IL-2 promotes apoptosis and limits the survival of CD8(+) memory T cells, IL-15 is required for the establishment and maintenance of CD8(+) T-cell memory. However, limited data are available to guide the clinical use of IL-15. Here, we demonstrate in nonhuman primates that IL-15 administration expands memory CD8(+) and CD4(+) T cells, and natural killer (NK) cells in the peripheral blood, with minimal increases in CD4(+)CD25(+)Foxp3(+) regulatory T cells. Daily administration of IL-15 resulted in persistently elevated plasma IL-15 levels and transient toxicity. Intermittent administration of IL-15 allowed clearance of IL-15 between doses and was safe for more than 3 weeks. These findings demonstrate that IL-15 has profound immunomodulatory properties distinct from those described for IL-2, and suggest that intermittent administration of IL-15 should be considered in clinical studies.
25: Biochemical and biophysical research communications, 2009 Sep 4, 386(4)
Tumor necrosis factor-alpha enhances IL-15-induced natural killer cell differentiation.
[Abstract]The differentiation of natural killer (NK) cells is regulated by various factors including soluble growth factors and transcription factors. Here, we have demonstrated that tumor necrosis factor-alpha (TNF-alpha) is a positive regulator of NK cell differentiation. TNF-alpha augmented the IL-15-induced expression of NK1.1 and CD122 in mature NK cells, and TNF-alpha alone also induced NK cell maturation as well as IL-15. TNF-alpha also increased IFN-gamma production in NK cells in the presence of IL-15. Meanwhile, mRNA expression of several transcription factors, including T-bet and GATA-3, was increased by the addition of TNF-alpha and IL-15. In addition, TNF-alpha increased nuclear factor-kappa B (NF-kappaB) activity in NK cells and inhibition of NF-kappaB impeded TNF-alpha-enhanced NK cell maturation. Overall, these data suggest that TNF-alpha significantly increased IL-15-driven NK cell differentiation by increasing the expression of transcription factors that play crucial roles in NK cell maturation and inducing the NF-kappaB activity.
26: Sichuan da xue xue bao. Yi xue ban = Journal of Sichuan University. Medical science edition, 2008 Nov, 39(6)
[In vivo effect of recombined IL-15/Fc fusion protein on EAU]
[Abstract]OBJECTIVE: To test the effect of recombined IL-15/Fc on experimental autoimmune uveitis (EAU) in mice. METHODS: EAU were induced in C57 mice by transferring activated T cells specific to the interphotoreceptor-binding protein (IRBP) 1-20 peptide. The mice were then treated with recombine IL-15/Fc fusion protein or IgG as controls. The severity of EAU were graded on a scale of 0 to 4 with half-point increment based on the type, number, and size of the lesions detected by funduscopic and HE staining. The IRBP1-20 sensitive CD8+T cells were isolated from the IRBP1-20 immune mice with auto-MACS. The in vitro effect of IL-15/Fc fusion protein on the proliferation, differentiation, expansion and production of inflammatory cytokines of the purified IRBP1-20 sensitive CD8+T cells were analyzed with 3HTdR, FACS and ELISA. RESULTS: IL-15/Fc fusion protein inhibited the activation, proliferation, expansion and production of inflammatory cytokines of the IRBP1-20 specific CD8+T cells, down regulated CD44(high)CD62L(low) effect and CD8+ CD62L(low) activated T cell subsets, and consequently decreased the severity of EAU. CONCLUSION: IL-15/Fc fusion proteins decrease the severity of EAU through inhibiting the proliferation, expansion, differentiation and production of inflammatory cytokines of CD8+ T cells.
27: Journal of leukocyte biology, 2009 Feb 23,
Retention of viability, cytotoxicity, and response to IL-2, IL-15, or IFN-{alpha} by human NK cells after CD107a degranulation.
[Abstract]NK cells represent a critical component of the host innate immune response to viral infection and tumor transformation. Nevertheless, the fate of recently degranulated NK cells subsequent to a primary target cell interaction remains largely unexplored. Here, we investigated the long-term viability and killing potential of human NK cells following target cell lysis using live-sorting of CD107a-degranulated NK cells. We observed that sorted CD107a+ NK cells exhibited continued lytic potential against a wide variety of target cells, including tumor and virally infected target cells. CD107a-positive- and CD107a-negative-sorted NK cells displayed similar long-term viability, killing potential, and response to inflammatory cytokines such as IL-2, IL-15, and IFN-alpha. Interestingly, we observed that the CD107a signature is remarkably stable over time and that recently degranulated NK cells exhibit an amplification of CD107 expression immediately following a target cell interaction. Together, our data expand previous data showing that NK cells retain the capacity to kill multiple target cells in succession and reveal that NK viability, cytotoxicity, and response to inflammatory cytokines are not altered following a primary target cell interaction. Overall, our data argue for the strength of the NK cell compartment in the continuous surveillance of tumor and virally infected cells in the body and highlight the use of using CD107a expression as a stable marker for NK cytotoxicity.
28: The Journal of experimental medicine, 2009 Feb 23,
Cytosolic PLA2 is required for CTL-mediated immunopathology of celiac disease via NKG2D and IL-15.
[Abstract]IL-15 and NKG2D promote autoimmunity and celiac disease by arming cytotoxic T lymphocytes (CTLs) to cause tissue destruction. However, the downstream signaling events underlying these functional properties remain unclear. Here, we identify cytosolic phospholipase A(2) (cPLA(2)) as a central molecule in NKG2D-mediated cytolysis in CTLs. Furthermore, we report that NKG2D induces, upon recognition of MIC(+) target cells, the release of arachidonic acid (AA) by CTLs to promote tissue inflammation in association with target killing. Interestingly, IL-15, which licenses NKG2D-mediated lymphokine killer activity in CTLs, cooperates with NKG2D to induce cPLA(2) activation and AA release. Finally, cPLA(2) activation in intraepithelial CTLs of celiac patients provides an in vivo pathophysiological dimension to cPLA(2) activation in CTLs. These results reveal an unrecognized link between NKG2D and tissue inflammation, which may underlie the emerging role of NKG2D in various immunopathological conditions and define new therapeutic targets.
29: Journal of immunology (Baltimore, Md. : 1950), 2009 Mar 1, 182(5)
Vaccinia virus-based multivalent H5N1 avian influenza vaccines adjuvanted with IL-15 confer sterile cross-clade protection in mice.
[Abstract]The potential for a global influenza pandemic remains significant with epidemiologic and ecologic indicators revealing the entrenchment of the highly pathogenic avian influenza A H5N1 in both wild bird populations and domestic poultry flocks in Asia and in many African and European countries. Indisputably, the single most effective public health intervention in mitigating the devastation such a pandemic could unleash is the availability of a safe and effective vaccine that can be rapidly deployed for pre-exposure vaccination of millions of people. We have developed two vaccinia-based influenza vaccines that are molecularly adjuvanted with the immune stimulatory cytokine IL-15. The pentavalent Wyeth/IL-15/5Flu vaccine expresses the hemagglutinin, neuraminidase, and nucleoprotein derived from the H5N1 influenza virus A/Vietnam/1203/2004 and the matrix proteins M1 and M2 from the H5N1 A/CK/Indonesia/PA/2003 virus on the backbone of a currently licensed smallpox vaccine. The bivalent MVA/IL-15/HA/NA vaccine expresses only the H5 hemagglutinin and N1 neuraminidase on the modified vaccinia virus Ankara (MVA) backbone. Both vaccines induced cross-neutralizing Abs and robust cellular immune responses in vaccinated mice and conferred sterile cross-clade protection when challenged with the H5N1 virus of a different clade. In addition to having potential as a universal influenza vaccine, in the event of an impending pandemic the Wyeth/IL-15/5Flu is also readily amenable to bulk production to cover the global population. For those individuals for whom the use of the Wyeth vaccine is contraindicated, our MVA/IL-15/HA/NA offers a substitute or a prevaccine to be used in a mass vaccination campaign similar to the smallpox eradication campaigns of few decades ago.