Host ranges of Sf-rhabdoviruses harbored by lepidopteran insects and insect cell lines

Cell lines derived from Spodoptera frugiperda (Sf), which are the most widely used hosts in the baculovirus-insect cell system, are contaminated with Sf-rhabdoviruses (Sf-RVs). In this study, we identified a closely related virus (Sf-CAT-RV) in the caterpillar species used to isolate the original Sf cell line. We then evaluated the Sf-RV and Sf-CAT-RV host ranges, found Sf-CAT-RV could infect Vero cells, and obtained results suggesting both variants can infect mouse ear fibroblasts. In addition, we found both variants could establish pantropic infections in severely immunocompromised (RAG2/IL2RG-/-) mice. However, both variants were cleared by two weeks post-inoculation and neither produced any symptoms or obvious adverse outcomes in these hosts. We conclude the caterpillars used to isolate Sf21 cells were the most likely source of the Sf-RV contaminant, Sf-RVs and their Sf-CAT-RV progenitor have broader host ranges than expected from previous work, but neither variant poses a serious threat to human health.

A great disturbance in the force: IL-2 receptor defects disrupt immune homeostasis

PURPOSE OF REVIEW

The current review highlights how inborn errors of immunity (IEI) due to IL-2 receptor (IL-2R) subunit defects may result in children presenting with a wide variety of infectious and inflammatory presentations beyond typical X-linked severe combined immune deficiency (X-SCID) associated with IL-2Rγ.

RECENT FINDINGS

Newborn screening has made diagnosis of typical SCID presenting with severe infections less common. Instead, infants are typically diagnosed in the first days of life when they appear healthy. Although earlier diagnosis has improved clinical outcomes for X-SCID, atypical SCID or other IEI not detected on newborn screening may present with more limited infectious presentations and/or profound immune dysregulation. Early management to prevent/control infections and reduce inflammatory complications is important for optimal outcomes of definitive therapies. Hematopoietic stem cell transplant (HSCT) is curative for IL-2Rα, IL-2Rβ, and IL-2Rγ defects, but gene therapy may yield comparable results for X-SCID.

SUMMARY

Defects in IL-2R subunits present with infectious and inflammatory phenotypes that should raise clinician's concern for IEI. Immunophenotyping may support the suspicion for diagnosis, but ultimately genetic studies will confirm the diagnosis and enable family counseling. Management of infectious and inflammatory complications will determine the success of gene therapy or HSCT.

The metalloprotease ADAM10 generates soluble interleukin-2 receptor alpha (sCD25) in vivo

The cytokine interleukin-2 (IL-2) plays a critical role in controlling the immune homeostasis by regulating the proliferation and differentiation of immune cells, especially T cells. IL-2 signaling is mediated via the IL-2 receptor (IL-2R) complex, which consists of the IL-2Rα (CD25), the IL-2Rβ, and the IL-2Rγ. While the latter are required for signal transduction, IL-2Rα controls the ligand-binding affinity of the receptor complex. A soluble form of the IL-2Rα (sIL-2Rα) is found constitutively in human serum, though its levels are increased under various pathophysiological conditions. The sIL-2Rα originates partly from activated T cells through proteolytic cleavage, but neither the responsible proteases nor stimuli that lead to IL-2Rα cleavage are known. Here, we show that the metalloproteases ADAM10 and ADAM17 can cleave the IL-2Rα and generate a soluble ectodomain, which functions as a decoy receptor that inhibits IL-2 signaling in T cells. We demonstrate that ADAM10 is mainly responsible for constitutive shedding of the IL-2Rα, while ADAM17 is involved in IL-2Rα cleavage upon T cell activation. In vivo, we found that mice with a CD4-specific deletion of ADAM10, but not ADAM17, show reduced steady-state sIL-2Rα serum levels. We propose that the identification of proteases involved in sIL-2Rα generation will allow for manipulation of IL-2Rα cleavage, especially as constitutive and induced cleavage of IL-2Rα are executed by different proteases, and thus offer a novel opportunity to alter IL-2 function.

Dynamic transcriptional activity and chromatin remodeling of regulatory T cells after varied duration of interleukin-2 receptor signaling

Regulatory T (Treg) cells require (interleukin-2) IL-2 for their homeostasis by affecting their proliferation, survival and activation. Here we investigated transcriptional and epigenetic changes after acute, periodic and persistent IL-2 receptor (IL-2R) signaling in mouse peripheral Treg cells in vivo using IL-2 or the long-acting IL-2-based biologic mouse IL-2-CD25. We show that initially IL-2R-dependent STAT5 transcription factor-dependent pathways enhanced gene activation, chromatin accessibility and metabolic reprogramming to support Treg cell proliferation. Unexpectedly, at peak proliferation, less accessible chromatin prevailed and was associated with Treg cell contraction. Restimulation of IL-2R signaling after contraction activated signature IL-2-dependent genes and others associated with effector Treg cells, whereas genes associated with signal transduction were downregulated to somewhat temper expansion. Thus, IL-2R-dependent Treg cell homeostasis depends in part on a shift from more accessible chromatin and expansion to less accessible chromatin and contraction. Mouse IL-2-CD25 supported greater expansion and a more extensive transcriptional state than IL-2 in Treg cells, consistent with greater efficacy to control autoimmunity.

Persistence of adoptively transferred T cells with a kinetically engineered IL-2 receptor agonist

Interleukin-2 (IL-2) is a component of most protocols of adoptive cell transfer (ACT) therapy for cancer, but is limited by short exposure and high toxicities. NKTR-214 is a kinetically-engineered IL-2 receptor βγ (IL-2Rβγ)-biased agonist consisting of IL-2 conjugated to multiple releasable polyethylene glycol chains resulting in sustained signaling through IL-2Rβγ. We report that ACT supported by NKTR-214 increases the proliferation, homing and persistence of anti-tumor T cells compared to ACT with IL-2, resulting in superior antitumor activity in a B16-F10 murine melanoma model. The use of NKTR-214 increases the number of polyfunctional T cells in murine spleens and tumors compared to IL-2, and enhances the polyfunctionality of T and NK cells in the peripheral blood of patients receiving NKTR-214 in a phase 1 trial. In conclusion, NKTR-214 may have the potential to improve the antitumor activity of ACT in humans through increased in vivo expansion and polyfunctionality of the adoptively transferred T cells.

Promising preclinical platform for evaluation of immuno-oncology drugs using Hu-PBL-NSG lung cancer models

BACKGROUND

With the advance of immunotherapy, treatment of non-small-cell lung cancer (NSCLC) has revolutionized by having anti-PD-1 therapy in front-line setting. In this era of cancer immunotherapy, humanized mouse models which recapitulate human immune system, are needed for predicting immunotherapy response in patients. We established a Hu-PBL-NSG mouse model which can be used as a preclinical testing platform for assessing efficacy of different immunotherapeutic agents.

MATERIALS AND METHODS

Hu-PBL-NSG mouse model was established by engrafting human peripheral blood mononuclear cells (PBMCs) into NOD/scid/IL-2Rγ^-/- (NSG) mice. Cytokine array was performed to assess serological similarity between patient and the Hu-PBL-NSG mouse, and microscopic immune cell infiltration was observed in various organs mouse model. Human anti-PD-1 therapy was treated for assessing drug efficacy in patient-derived tumor.

RESULTS

hCD3⁺hCD45⁺ T-cells and antigen presenting cells (dendritic cells, macrophages, and MDSC) increased in the serum of Hu-PBL-NSG mouse 24 h after the transfusion of human PBMCs, and CD3 + T cells were observed in lung, liver, kidney, spleen sections. Cytokine arrays of human and Hu-PBL-NSG mouse revealed high similarity of Th1, Th2, Th17-related cytokines. A tumor xenograft was engrafted from an EML4-ALK patient, and Hu-PBL-NSG mouse was sacrificed for histological analyses. hCD3⁺ T cells were infiltrated within the tumor, and CD11c + cells, which represent antigen-presenting capability, were seen in spleen, lung, liver and kidney. When anti-PD-1 Ab was treated intraperitoneally, xenograft tumor showed significant reduction in volume after day 6, and increased expression of immune response-related genes on microarray analysis in the tumor. Mostly IFN-gamma and its related gene sets were significantly changed (FDR < 0.25, GSEA).

CONCLUSION

Hu-PBL-NSG mouse model which highly resembles human immune system was successfully established. This model could be a strong preclinical model for testing efficacy of immunotherapeutic agents, and also for pursuing novel immunotherapy treatment strategies in advanced NSCLC.

A pH-sensitive Macromolecular Prodrug as TLR7/8 Targeting Immune Response Modifier

The chemical synthesis and biological activity of novel functionalized imidazoquinoline derivatives (ImQ) to generate Toll-like receptor (TLR) 7/8 specific prodrugs are presented. In vivo activity of ImQs to induce inflammation was confirmed in zebrafish larvae. After covalent ligation to fully biodegradable polyphosphazenes (ImQ-polymer), the macromolecular prodrugs were designed to undergo intracellular pH-sensitive release of ImQs to induce inflammation through binding to endosomal TLR7/8 (danger signal). We showed ImQ dissociation from prodrugs at a pH 5 pointing towards endosomal prodrug degradability. ImQ-polymers strongly activated ovalbumin-specific T cells in murine splenocytes as shown by increased proliferation and expression of the IL-2 receptor (CD25) on CD8+ T cells accompanied by strong IFN-γ release. ImQ prodrugs presented here are suggested to form the basis of novel nanovaccines, for example, for intravenous or intratumoral cancer immunotherapeutic applications to trigger physiological antitumor immune responses.

Regulatory T-cells Infiltrate Periodontal Disease Tissues

CD4+CD25+ regulatory T (Tr) cells are critical in regulating the immune response and thereby play an important role in the defense against infection and control of autoimmune diseases. Our previous studies demonstrated the involvement of autoimmune responses in periodontitis. The aim of this study was to identify CD4+CD25+ Tr cells in periodontitis tissues and compare them with those in gingivitis tissues. Immunohistological analysis of CD4, CD25, and CTLA-4 and the gene expression analysis of FOXP3, TGF-β1, and IL-10 on gingival biopsies revealed the presence of CD4+CD25+ Tr cells in all tissues. In periodontitis, the percentage of CD4+CD25+ Tr cells increased with increasing proportions of B-cells relative to T-cells. FOXP3, a characteristic marker for CD4+CD25+ Tr cells, TGF-β1 and IL-10 were expressed more highly in periodontitis compared with gingivitis. These findings suggest that CD4+CD25+ Tr cells and possibly other regulatory T-cell populations do exist and may play regulatory roles in periodontal diseases.

Effect of tumor necrosis factor-induced protein 8 on T-cell-mediated immunity in mice after thermal injury

Tumor necrosis factor-induced protein 8(TNFAIP8), the first identified member of the TNFAIP8 family, shares considerable sequence homology with members of this family. It is expressed in a wide variety of human normal tissues, with relatively higher levels in lymphoid tissues and placenta. The present study was designed to examine the effect of TNFAIP8 on T-cell-mediated immunity secondary to burn injury. Sixty male mice were randomly divided into four groups as follows: sham burn group, burn group, burn with TNFAIP8-siRNA transfection group, and burn with negative control transfection group, and they were sacrificed at designated time points. CD4+ T cells were isolated using MACS microbeads. T-Cell proliferation was analyzed with MTT assay, and IL-2, soluble IL-2R, IL-4, interferon-γ (IFN-γ) were determined with enzyme-linked immunosorbent assay kits. It was found that CD4+ T lymphocyte proliferative activity was significantly down-regulated when TNFAIP8 gene was silenced by siRNA in mice at 24 h post burn. Down-regulation of TNFAIP8 can significantly decrease expression levels of IL-2 and soluble IL-2R at 24 h after thermal injury. These results demonstrated that TNFAIP8 appeared to be involved in the immune regulation of CD4+ T lymphocytes, and the decreased expression of TNFAIP8 could affect T lymphocyte functions after thermal injury.

4-1BB Signaling Enhances Primary and Secondary Population Expansion of CD8+ T Cells by Maximizing Autocrine IL-2/IL-2 Receptor Signaling

4-1BB (CD137), a member of the tumor necrosis factor receptor superfamily (TNFRSF), is primarily expressed on activated T cells and is known to enhance proliferation of T cells, prevent activation-induced cell death, and promote memory formation of CD8⁺ T cells. In particular, it is well acknowledged that 4-1BB triggering preferentially enhances the expansion of CD8⁺ T cells rather than CD4⁺ T cells, but the underlying mechanism remains unclear. Here we found that 4-1BB triggering markedly increased IL-2Rα (CD25) and IL-2 expressions of CD8+ T cells but minimally for CD4⁺ T cells. Proliferation of CD8⁺ T cells was moderately enhanced by direct 4-1BB triggering in the absence of signaling through IL-2Rα/IL-2 interactions, but further promoted in the presence of IL-2Rα/IL-2 interactions. Among the TNFRSF members including OX40, GITR, CD30, and CD27, 4-1BB was superior in the ability to induce IL-2Rα expression on CD8+ T cells. When the primary and secondary expansions of CD8⁺ T cells in vivo were examined by adoptively transferring OVA-specific CD8⁺ T cells along with the treatment with agonistic anti-4-1BB and/or antagonistic anti-CD25 F(ab’)₂ mAb, 4-1BB triggering enhanced both primary and secondary expansion of CD8⁺ T cells in vivo, and the 4-1BB effects were moderately suppressed in primary expansion while completely abolished in secondary expansion of OVA-specific CD8⁺ T cells by blocking IL-2Rα. These results suggest that 4-1BB-mediated increases of IL-2Rα and IL-2 prolong the effects of transient TCR- and 4-1BB-mediated signaling in CD8⁺ T cells, and that 4-1BB triggering preferentially enhances the expansion of CD8⁺ T cells through the amplification of autocrine IL-2/IL-2R signaling loop.

Ex vivo expanded human regulatory T cells delay islet allograft rejection via inhibiting islet-derived monocyte chemoattractant protein-1 production in CD34+ stem cells-reconstituted NOD-scid IL2rγnull mice

Type 1 diabetes mellitus (T1DM) is an autoimmune disease caused by immune-mediated destruction of insulin-secreting β cells of the pancreas. Near complete dependence on exogenous insulin makes T1DM very difficult to control, with the result that patients are exposed to high blood glucose and risk of diabetic complications and/or intermittent low blood glucose that can cause unconsciousness, fits and even death. Allograft transplantation of pancreatic islets restores normoglycemia with a low risk of surgical complications. However, although successful immediately after transplantation, islets are progressively lost, with most of the patients requiring exogenous insulin within 2 years post-transplant. Therefore, there is an urgent requirement for the development of new strategies to prevent islet rejection. In this study, we explored the importance of human regulatory T cells in the control of islets allograft rejection. We developed a pre-clinical model of human islet transplantation by reconstituting NOD-scid IL2rγ^null mice with cord blood-derived human CD34⁺ stem cells and demonstrated that although the engrafted human immune system mediated the rejection of human islets, their survival was significantly prolonged following adoptive transfer of ex vivo expanded human T_regs. Mechanistically, T_regs inhibited the infiltration of innate immune cells and CD4⁺ T cells into the graft by down-regulating the islet graft-derived monocyte chemoattractant protein-1. Our findings might contribute to the development of clinical strategies for T_reg therapy to control human islet rejection. We also show for the first time that CD34⁺ cells-reconstituted NOD-scid IL2rγ^null mouse model could be beneficial for investigating human innate immunity in vivo.

Intratibial injection of human multiple myeloma cells in NOD/SCID IL-2Rγ(null) mice mimics human myeloma and serves as a valuable tool for the development of anticancer strategies

BACKGROUND

We systematically analyzed multiple myeloma (MM) cell lines and patient bone marrow cells for their engraftment capacity in immunodeficient mice and validated the response of the resulting xenografts to antimyeloma agents.

DESIGN AND METHODS

Using flow cytometry and near infrared fluorescence in-vivo-imaging, growth kinetics of MM cell lines L363 and RPMI8226 and patient bone marrow cells were investigated with use of a murine subcutaneous bone implant, intratibial and intravenous approach in NOD/SCID, NOD/SCID treated with CD122 antibody and NOD/SCID IL-2Rγ(null) mice (NSG).

RESULTS

Myeloma growth was significantly increased in the absence of natural killer cell activity (NSG or αCD122-treated NOD/SCID). Comparison of NSG and αCD122-treated NOD/SCID revealed enhanced growth kinetics in the former, especially with respect to metastatic tumor sites which were exclusively observed therein. In NSG, MM cells were more tumorigenic when injected intratibially than intravenously. In NOD/SCID in contrast, the use of juvenile long bone implants was superior to intratibial or intravenous cancer cell injection. Using the intratibial NSG model, mice developed typical disease symptoms exclusively when implanted with human MM cell lines or patient-derived bone marrow cells, but not with healthy bone marrow cells nor in mock-injected animals. Bortezomib and dexamethasone delayed myeloma progression in L363- as well as patient-derived MM cell bearing NSG. Antitumor activity could be quantified via flow cytometry and in vivo imaging analyses.

CONCLUSIONS

Our results suggest that the intratibial NSG MM model mimics the clinical situation of the disseminated disease and serves as a valuable tool in the development of novel anticancer strategies.

Differential post-surgical metastasis and survival in SCID, NOD-SCID and NOD-SCID-IL-2Rγ(null) mice with parental and subline variants of human breast cancer: implications for host defense mechanisms regulating metastasis

We compare for the first time, the metastatic aggressiveness of the parental MDA-MB-231 breast cancer cell line and two luciferase-tagged in vivo-derived and selected pro-metastatic variants (LM2-4/luc⁺ and 164/8-1B/luc⁺) in SCID, NOD-SCID and NOD-SCID-IL-2Rγ^null (NSG) mice following orthotopic implantation and primary tumour resection. The variants are known to be more aggressively metastatic in SCID mice, compared to the parental line which has limited spontaneous metastatic competence in these mice. When 2×10⁶ cells were injected into the mammary fat pad, the growth of the resultant primary tumours was identical for the various cell lines in the three strains of mice. However, metastatic spread of all three cell lines, including the MDA-MB-231 parental cell line, was strikingly more aggressive in the highly immunocompromised NSG mice compared to both NOD-SCID and SCID mice, resulting in extensive multi-organ metastases and a significant reduction in overall survival. While these studies were facilitated by monitoring post-surgical spontaneous metastases using whole body bioluminescence imaging, we observed that the luciferase-tagged parental line showed altered growth and diminished metastatic properties compared to its untagged counterpart. Our results are the first to show that host immunity can have a profound impact on the spread of spontaneous visceral metastases and survival following resection of a primary tumour in circumstances where the growth of primary tumours is not similarly affected; as such they highlight the importance of immunity in the metastatic process, and by extension, suggest certain therapeutic strategies that may have a significant impact on reducing metastasis.

Central role for interleukin-2 in type 1 diabetes

Type 1 diabetes presents clinically with overt hyperglycemia resulting from progressive immune-mediated destruction of pancreatic β-cells and associated metabolic dysfunction. Combined genetic and immunological studies now highlight deficiencies in both the interleukin-2 (IL-2) receptor and its downstream signaling pathway as a central defect in the pathogenesis of type 1 diabetes. Prior intervention studies in animal models indicate that augmenting IL-2 signaling can prevent and reverse disease, with protection conferred primarily by restoration of regulatory T-cell (Treg) function. In this article, we will focus on studies of type 1 diabetes noting deficient IL-2 signaling and build what we believe forms the molecular framework for their contribution to the disease. This activity results in the identification of a series of potentially novel therapeutic targets that could restore proper immune regulation in type 1 diabetes by augmenting the IL-2 pathway.

Increased resting energy expenditure is associated with failure to thrive in infants with severe combined immunodeficiency

OBJECTIVES

To measure resting energy expenditure (REE) and determine whether increased REE (hypermetabolism) is associated with failure to thrive (FTT) in patients with severe combined immunodeficiency (SCID) at diagnosis.

STUDY DESIGN

REE was measured in 26 patients with SCID in a single transplant center. Predicted REE was determined with World Health Organization standards. Measured REE >110% of predicted REE was classified as hypermetabolism. Other data collected included FTT status, infections, genotype, phenotype, and the feeding methods used.

RESULTS

Fifteen of 26 patients (57.7%) had FTT, and 18 of 26 patients (69.2%) were hypermetabolic. Hypermetabolism occured in 14 of 15 patients (93%) with FTT, and only 4 of 11 patients (36%) without FTT had hypermetabolism (P = .003). There was a significant difference between the measured REE (71.75 ± 16.6 kcal/kg) and the predicted REE (52.85 ± 2.8 kcal/kg; P < .0001). Eleven of 17 patients (65%) required nasogastric feeding, parenteral nutrition, or both to meet their energy needs.

CONCLUSIONS

Hypermetabolism is common in patients with SCID and may contribute to the development of FTT. The hypermetabolism in these patients may necessitate intensive nutrition support.

Signalling through the IL-2 receptor γ(c) peptide (CD132) is essential for the expression of immunity to Plasmodium chabaudi adami blood-stage malaria

A genetic dissection approach was employed to determine whether the IL-2 receptor complex (IL-2R) comprised of α, β and γ chains is required for the suppression of Plasmodium chabaudi adami parasitemia. Blood-stage infections in IL-2Rγ(c)(-/y) mice failed to cure with parasitemia remaining elevated for > 50 days indicating the IL-2Rγ(c) through which all members of the γ(c) family of cytokines signal has an essential role in protective immunity against blood-stage malarial parasites. In contrast, the curing of parasitemia in IL-2/15Rβ⁻/⁻ mice, deficient in both IL-2 and IL-15 signalling was significantly delayed but did occur, indicating that neither cytokine plays an essential role in parasite clearance. Moreover, the observation that the time course of parasitemia in IL-15⁻/⁻ mice was nearly identical to that seen in controls suggests that the parasitemia-suppressing role of stimulating through the IL-2/15Rβ chain is owing to IL-2 signalling and not a redundant function of IL-15.

Defects in the Bcl-2-regulated apoptotic pathway lead to preferential increase of CD25 low Foxp3+ anergic CD4+ T cells

Defects in the Bcl-2-regulated apoptotic pathway inhibit the deletion of self-reactive T cells. What is unresolved, however, is the nature and fate of such self-reactive T cells escaping deletion. In this study, we report that mice with such defects contained increased numbers of CD25(low)Foxp3(+) cells in the thymus and peripheral lymph tissues. The increased CD25(low)Foxp3(+) population contained a large fraction of cells bearing self-reactive TCRs, evident from a prominent increase in self-superantigen-specific Foxp3(+)Vβ5(+)CD4(+) T cells in BALB/c Bim(-/-) mice compared with control animals. The survival rate of the expanded CD25(low)Foxp3(+) cells was similar to that of CD25(high)Foxp3(+) CD4 T cells in vitro and in vivo. IL-2R stimulation, but not TCR ligation, upregulated CD25 on CD25(low)Foxp3(+)CD4(+) T cells in vitro and in vivo. The expanded CD25(low)Foxp3(+)CD4(+) T cells from Bim(-/-) mice were anergic but also had weaker regulatory function than CD25(high)Foxp3(+) CD4(+) T cells from the same mice. Analysis of Bim(-/-) mice that also lacked Fas showed that the peripheral homeostasis of this expanded population was in part regulated by this death receptor. In conclusion, these results show that self-reactive T cell escapes from thymic deletion in mice defective in the Bcl-2-regulated apoptotic pathway upregulate Foxp3 and become unresponsive upon encountering self-Ag without necessarily gaining potent regulatory function. This clonal functional diversion may help to curtail autoaggressiveness of escaped self-reactive CD4(+) T cells and thereby safeguard immunological tolerance.

Specific inhibition of protein kinase Cbeta expression by antisense RNA affects the activation of Jurkat T lymphoma cells

Antisense RNA technology was employed to specifically inhibit the expression of the protein kinase Cbeta (PKCbeta) isoform in Jurkat cells, to explore its influence on the expression of surface antigens (CD69) and the cytokines interleukin-8 (IL-8), tumour necrosis factor (TNF)-alpha and beta, and to characterise its controversial involvement in the expression of IL-2 and its receptor (IL-2R). Transfection of cells with an antisense PKCbeta construct (as-PKCbeta-pREP3) significantly increased IL-2R/CD25 expression in phorbol 12-myristate 13-acetate (PMA)-stimulated as-PKCbeta-pREP3 transfectants, in contrast to Jurkat cells transfected with a control as-PKCalpha-pREP3 plasmid. IL-2 production, in contrast, was strongly inhibited in both transfectant populations stimulated by PMA plus the calcium ionophore ionomycin. Three clones (asb1/asb2/asb3), selected from as-PKCbeta-pREP3 transfectants, showed decreased PKCbeta protein levels (40 percent, 50 percent and 60 percent, respectively, as determined by western blotting) and mRNA levels. The specific inhibition was confirmed in immunoblots for other PKC (alpha, delta, epsilon, gamma, theta, and lambda lambda/tau) isoforms and in immunoprecipitates from representative (c2/asb2) clones. Stimulation of PKCbeta-depleted clones significantly increased CD25 expression but decreased IL-2 production (similarly to as-PKCbeta-pREP3 transfectants) and IL-2 message levels. CD69 expression and IL-8 secretion were significantly decreased, but TNFbeta message levels were highly increased in asb2/asb3 clones, without affecting TNFalpha secretion. Analysis of the mitogen-activated protein kinase (MAP Kinase) signalling pathway showed unaltered extracellular signal regulated kinase 1/2 (ERK1/2) and p38 phosphorylation but increased activation of c-Jun N-terminal kinase (JNK1) and its substrate, the transcription factor ATF-2 (activated transcription factor-2), which are involved in IL-2 gene expression. Our results revealed new PKCbeta functions, affecting CD69 expression and IL-8 production, and support the requirement for PKCbeta in IL-2 secretion/transcription and IL-2R regulation.

Dietary selenium modulates activation and differentiation of CD4+ T cells in mice through a mechanism involving cellular free thiols

The immune-enhancing effects of selenium (Se) supplementation make it a promising complementary and alternative medicine modality for boosting immunity, although mechanisms by which Se influences immunity are unclear. Mice fed low (0.08 mg/kg), medium (0.25 mg/kg), or high (1.0 mg/kg) Se diets for 8 wk were challenged with peptide/adjuvant. Antigen-specific CD4(+) T cell responses were increased in the high Se group compared with the low and medium Se groups. T cell receptor signaling in ex vivo CD4(+) T cells increased with increasing dietary Se, with all 3 groups differing from one another in terms of calcium mobilization, oxidative burst, translocation of nuclear factor of activated T cells, and proliferation. The high Se diet increased expression of interleukin (IL)-2 and the high affinity chain of the IL-2 receptor compared with the low and medium Se diets. The high Se diet skewed the T helper (Th)1/Th2 balance toward a Th1 phenotype, leading to higher interferon-gamma and CD40 ligand levels compared with the low and medium Se diets. Prior to CD4(+) T cell activation, levels of reactive oxygen species did not differ among the groups, but the low Se diet decreased free thiols compared with the medium and high Se diets. Addition of exogenous free thiols eliminated differences in CD4(+) T cell activation among the dietary groups. Overall, these data suggest that dietary Se levels modulate free thiol levels and specific signaling events during CD4(+) T cell activation, which influence their proliferation and differentiation.

[Study of signal transduction mediated by integrin alphaIIbbeta3 using a dominant negative model]

This study was purposed to investigate the role of integrin beta3 cytoplasmic domain in signal transduction mediated by integrin alphaIIbbeta3 and to explore the effect of integrin beta3 on signal transduction and specificity in condition without alphaIIb subunit. The fusion protein (Tac/beta3) was stably expressed in CHO cell line expressing GPIbIX, integrin alphaIIbbeta3 (IbIX/IIbIIIa-CHO cell line) by combining extracellular and transmembrane domains (Tac) of IL-2 receptor with integrin beta3 cytoplasmic domain (beta3) for formation of fusion protein (Tac/beta3). Then a series of tests were performed, including spreading and stable adhesion of IbIX/IIbIIIa-CHO cell line in solid phase fibrinogen (Fg), fibrin clot restriction and soluble fibrinogen binding, which represent outside-in and inside-out signal transduction events. The results showed that the bidirectional signal transduction mediated by alphaIIbbeta3 in IbIX/IIbIIIa-CHO/Tac-762 cells stably expressing Tac/beta3 was seriously inhibited. It is concluded that the Tac/beta3 can play a significant role in IbIX/IIbIIIa-CHO/Tac-762 cells through a dominant negative mode, the independent presence of beta3 subunit cytoplasmic domain can regulate the bidirectional signal transduction mediated by integrin alphaIIbbeta3.

The genetics of autoimmune thyroid disease

Recent studies have confirmed that polymorphisms in several genes confer susceptibility for the development of autoimmune thyroid disease, and that of these HLA-DR alleles, and the genes encoding CTLA-4, PTPN22, FCRL3, and probably the IL-2 receptor all have associations with other autoimmune disorders, indicating that they provide a lowering of the background threshold for the development of autoimmunity. Other factors (the TSHR and possibly Tg genes, HLA-C alleles, and environmental factors) determine that the type of disease which results from this background propensity specifically targets the thyroid. We also now appreciate much better how complex these disorders are in their pathogenesis: multiple genes influencing multiple immunological pathways are involved in pathogenesis, but are not involved in every patient. Any individual patient with thyroid autoimmunity has their own cluster of genetic (and environmental) susceptibility factors, only very partially shared with other patients who have the same diagnostic and clinical label. The interplay of forces that cause autoimmune thyroid disease in an individual patient are more subtle than previously imagined and there is at present no obvious upper limit on the number of genes which may be involved.

Variation in the IL7RA and IL2RA genes in German multiple sclerosis patients

Variation in the genes encoding the interleukin (IL) 7 and IL2 receptor alpha chains (IL7RA, IL2RA) was recently found associated with multiple sclerosis (MS). We evaluated the role of these two genes in a large German MS case-control cohort. Five single nucleotide polymorphisms (SNPs) in IL7RA and four in IL2RA were genotyped in 1319 MS patients and 908 controls by means of restriction enzyme digestion or TaqMan assays and subsequently evaluated for association with MS. IL7RA expression was measured via quantitative real time PCR in 24 subjects. We replicated the association of exon 6 variation (rs6897932) in IL7RA with MS. Yet, this association was only found in patients with primary progressive (pp) or secondary progressive (sp) disease course (p=0.0004). Expression analysis did not show differences in IL7RA expression depending on genotypes at this locus, while reduced expression of the soluble receptor was observed in patients with pp and sp MS irrespective of genotype. In the IL2RA gene, significant associations of SNPs in introns 3 and 7 with MS subtypes were obvious. Together these results confirm involvement of polymorphisms in the IL7RA and IL2RA genes in MS pathogenesis and suggest that IL7RA variation may primarily affect chronic disease courses.

CD4+CD25+ regulatory cells from human peripheral blood express very high levels of CD25 ex vivo

Selective isolation of only those CD4+ T cells that display the highest levels of CD25 by FACS results in a highly homogeneous regulatory population as defined by functional activity and the expression of multiple surface antigens. Thus greater than 98% of CD4+CD25high cells express CD45RO in the absence of CD45RA expression. Upon TCR stimulation CD4+CD25high cells are both anergic and tolerogenic as they inhibit proliferation and cytokine secretion by activated CD4+CD25- responder T cells in a contact-dependent manner. In contrast, CD4+ cells that express lower levels of CD25 are more heterogeneous in their levels of expression of CD45RO, HLA-DR and CD122, and do not exhibit anergic or suppressive characteristics. Providing either CD28 co-stimulation or IL2 to a maximal anti-CD3 stimulus results in a modest induction of proliferation and the loss of observable suppression by CD4+CD25high regulatory cells. Unlike CTLA4 blockade, blocking the interaction of PD-1 with its ligand PD-L1 affects the level of suppression. However, since this reduction in suppression by alphaPD-L1 can be overcome by increasing the number of CD4+CD25high T cells in the co-culture assay, the mechanism of CD4-CD25high regulation can proceed in the absence of PD-1/PD-L1 interactions, although it is not as efficient.

Biological properties of interleukin 2 and its role in pathogenesis of selected diseases--a review

Interleukin 2 (IL-2), or T-cell growth factor (TCGF), represents the first identified, fully-characterized, purified human interleukin. It is produced mainly by T helper (CD4+) lymphocytes, stimulates cell-mediated immune responses, controls growth and differentiation of B lymphocytes, and intensifies proliferation and activity of all cytotoxic cell clones. IL-2 is a growth factor in vitro and a mediator of self-tolerance in vivo, and therefore interests tumor immunotherapy investigators. The role of IL-2 in the cell cycle of neoplastic cells remains unclear. IL-2 inhibits growth of certain human tumor cells while proliferation of other cells remains intact or is even stimulated. Decreased IL-2 production is often observed in the more advanced clinical stages of human tumors, which provides rational for inclusion of recombinant IL-2 in the immunotherapy for some tumors. On the other hand, tumor cells themselves may produce IL-2 and promote tumor growth. This article summarizes the current physiological role of IL-2 and its role in the pathogenesis of select human diseases. Many papers (including reviews) pertain to the IL-2R receptor. The soluble form of the alpha subunit of the IL-2 receptor (sIL-2Ralpha) is elevated in most proliferative disturbances of the hematopoietic system and in many solid tumors. Special reference to the most important discoveries and our own experience in intracellular detection of IL-2 and IL-2Ralpha are included. IL-2 properties, cellular sources, and targets, including data on its expression in pathological conditions, continue to be supplemented. Attempts to treat tumors are also discussed, using modified varieties of therapy that use IL-2 itself and/or its receptor.

Targeted Receptor Trafficking Affects the Efficiency of Retrovirus Transduction

We describe the development of an experimental system to test the hypothesis that the efficiency of retrovirus transduction is dependent on the pathway of virus entry into the host cell and the intracellular trafficking itinerary of the cellular receptor with which it interacts. The experimental system consists of three model target cell lines, derived from HeLa cells, that stably express one of three interleukin-2 receptor alpha chain (CD25) chimeras, TAC, TAC-CD16, and TAC-DKQTLL, which have identical extracellular domains but different intracellular trafficking itineraries, and a targeted amphotropic murine leukemia retrovirus whose envelope proteins were modified to include a binding site for TAC at their N-termini. We found that the efficiency of retrovirus transduction was affected by the distribution and trafficking itinerary of the TAC receptors. Transduction of cells that expressed TAC-DKQTLL was nearly 4-fold lower than transduction of control cells that did not express any of the TAC receptors. In contrast, transduction of cells that expressed TAC was 1.6-fold higher than transduction of control cells, whereas transduction was not significantly affected by the expression of TAC-CD16. Our results suggest that in the course of designing a targeted retrovirus it may be prudent to target only those receptors that internalize retroviruses via pathways that most efficiently support post-binding steps of infection.

Insertional oncogenesis in 4 patients after retrovirus-mediated gene therapy of SCID-X1

Previously, several individuals with X-linked SCID (SCID-X1) were treated by gene therapy to restore the missing IL-2 receptor gamma (IL2RG) gene to CD34+ BM precursor cells using gammaretroviral vectors. While 9 of 10 patients were successfully treated, 4 of the 9 developed T cell leukemia 31-68 months after gene therapy. In 2 of these cases, blast cells contained activating vector insertions near the LIM domain-only 2 (LMO2) proto-oncogene. Here, we report data on the 2 most recent adverse events, which occurred in patients 7 and 10. In patient 10, blast cells contained an integrated vector near LMO2 and a second integrated vector near the proto-oncogene BMI1. In patient 7, blast cells contained an integrated vector near a third proto-oncogene,CCND2. Additional genetic abnormalities in the patients' blast cells included chromosomal translocations, gain-of-function mutations activating NOTCH1, and copy number changes, including deletion of tumor suppressor gene CDKN2A, 6q interstitial losses, and SIL-TAL1 rearrangement. These findings functionally specify a genetic network that controls growth in T cell progenitors. Chemotherapy led to sustained remission in 3 of the 4 cases of T cell leukemia, but failed in the fourth. Successful chemotherapy was associated with restoration of polyclonal transduced T cell populations. As a result, the treated patients continued to benefit from therapeutic gene transfer.

A new immunodeficient hyperglycaemic mouse model based on the Ins2Akita mutation for analyses of human islet and beta stem and progenitor cell function

AIMS/HYPOTHESIS

To develop and validate a new immunodeficient mouse strain that spontaneously develops a non-autoimmune hyperglycaemia to serve as a diabetic host for human islets and human beta stem and progenitor cells without the need for induction of hyperglycaemia by toxic chemicals with their associated side effects.

METHODS

We generated and characterised a new strain of immunodeficient spontaneously hyperglycaemic mice, the NOD-Rag1null Prf1null Ins2Akita strain and compared this strain with the NOD-scid Il2rgammanull (also known as Il2rg) immunodeficient strain rendered hyperglycaemic by administration of a single dose of streptozotocin. Hyperglycaemic mice were transplanted with human islets ranging from 1,000 to 4,000 islet equivalents (IEQ) and were monitored for normalisation of blood glucose levels.

RESULTS

NOD-Rag1null Prf1null Ins2Akita mice developed spontaneous hyperglycaemia, similar to Ins2Akita-harbouring strains of immunocompetent mice. Histological examination of islets in the host pancreas validated the spontaneous loss of beta cell mass in the absence of mononuclear cell infiltration. Human islets transplanted into spontaneously diabetic NOD-Rag1null Prf1null Ins2Akita and chemically diabetic NOD-scid Il2rgammanull mice resulted in a return to euglycaemia that occurred with transplantation of similar beta cell masses.

CONCLUSIONS/INTERPRETATION

The NOD-Rag1null Prf1null Ins2Akita mouse is the first immunodeficient, spontaneously hyperglycaemic mouse strain described that is based on the Ins2Akita mutation. This strain is suitable as hosts for human islet and human beta stem and progenitor cell transplantation in the absence of the need for pharmacological induction of diabetes. This strain of mice also has low levels of innate immunity and can be engrafted with a human immune system for the study of human islet allograft rejection.

The molecular genetics of type 1 diabetes: new genes and emerging mechanisms

Susceptibility to type 1 diabetes (T1D) is determined by complex interactions between several genetic loci and environmental factors. Alleles at the human leukocyte antigen (HLA) locus explain up to 50% of the familial clustering of T1D, and the remainder is contributed to by multiple loci, of which only four were known until recently. First-stage results of genome-wide association (GWA) studies performed with high-density genotyping arrays have already produced four novel loci and the promise that, with the completion of the second stage of the GWA studies, most of the genetic basis of T1D will be known. We will review what is known to date about the mechanisms of genetic susceptibility to T1D, with special emphasis on possible diagnostic and therapeutic applications of these recent genetic findings.

Liver metastasis models of colon cancer for evaluation of drug efficacy using NOD/Shi-scid IL2Rgammanull (NOG) mice

To examine the drug efficacy of a novel farnesyltransferase inhibitor (FTI), CH4512600, in vivo, we developed a reliable liver metastasis model of human colon cancer using NOD/Shi-scid IL2Rgamma(null) (NOG) mice. Eleven human colon cancer cell lines were examined for their ability to form diverse metastatic foci in the livers of NOG mice. When inoculated with 10(4) COLO320DM, HCT 116, HT-29, WiDr, LoVo and LS174T cells, liver metastasis was evident in 100% (6/6), 100% (6/6), 88.9% (8/9), 87.5% (7/8), 83.3% (5/6) and 50.0% (3/6) of the NOG mice, respectively. CaCo2, COLO201, LS123, SW48 and SW1417 showed no metastasis when seeded at 10(4) cells even in NOG mice. The mRNA expression levels and genetic mutations of N, H and K-RAS genes, which directly affect the levels of cellular RAS protein that would be molecular target for FTI, were also examined in these six metastatic human colon cancer cell lines for molecular biological and genotypic characteristics. Only three cell lines had a point mutation in the RAS oncogene. LS174T cell line had a point mutation of the K-RAS gene at codon 12 (gly12 --> asp; G12D), and HCT 116 and LoVo cell lines had a point mutation of the K-RAS gene at codon 13 (gly13 --> asp; G13D). Relative gene expression levels of N, H and K-RAS genes in the HCT 116 cell line were 2.6-5.0-fold lower than that of LS174T and LoVo cell lines. We selected HCT 116 cell line from our liver metastasis model for evaluation of FTI CH4512600 efficacy in vivo. Using the NOG mouse liver metastasis model, we demonstrated the effectiveness of FTI CH4512600 to suppress tumor growth in vivo and to prolong mouse survival significantly from 36.9+/-2.9 to 50.3+/-9.4 days.

Interleukin-2 receptor signaling in regulatory T cell development and homeostasis

Interleukin-2 (IL2) was initially identified from supernatants of activated lymphocytes over 30 years ago. In the ensuing 15 years, the cDNAs for both IL2 and the three chains of the interleukin-2 receptor (IL2R) were cloned. Subsequently, many of the downstream biochemical pathways activated by the IL2 receptor complex were identified and the structure of IL2 bound to this tripartite receptor complex was solved. Thus, we now have a very good understanding of how each chain contributes to high affinity IL2 binding and signal transduction. In contrast, over the past 30 years the role that IL2 plays in regulating lymphocyte function has involved many surprising twists and turns. For example, IL2 has been shown, paradoxically, to regulate both lymphocyte proliferation and lymphocyte death. In this review, we briefly outline the original findings suggesting a role for IL2 as a T cell growth factor, as well as subsequent studies pointing to its function as an initiator of activation-induced cell death, but then focus on the newly appreciated role for IL2 and IL2R signaling in the development and homeostasis of regulatory T cells.

Interleukin 15 and its receptor

Interleukin 15 (IL-15) is a member of the four-helix bundle cytokine family that shares many in vitro biological activities with IL-2. Previous work demonstrated that IL-15 utilizes the beta and gamma chains of the IL-2 receptor (IL-2R), and that these are essential for IL-15-mediated signal transduction. However, several lines of evidence indicated the existence of an additional, IL-15-specific receptor component. An IL-15 binding chain was identified on a murine T cell clone, and direct expression cloning was used to isolate the corresponding cDNA. The predicted structure of this protein shows sequence similarity to the IL-2R alpha chain. Transfection of this cDNA into a murine, IL-3-dependent myeloid cell line, 32D-01, conferred IL-15 binding and, together with transfection of the IL-2R beta chain, rendered the cells responsive to IL-15 stimulation. This experiment confirmed that the IL-15 binding chain is part of the IL-15 receptor, and it is designated as the IL-15R alpha subunit. The expression pattern of the IL-15R alpha mRNA is distinct from that of IL-2R alpha mRNA. Recombinant expression of a soluble form of IL-15R alpha demonstrated that it is a potent inhibitor of IL-15 biological activity.

OX40-mediated differentiation to effector function requires IL-2 receptor signaling but not CD28, CD40, IL-12Rbeta2, or T-bet

Ag-specific CD4 T cells transferred into unirradiated Ag-bearing recipients proliferate, but survival and accumulation of proliferating cells is not extensive and the donor cells do not acquire effector functions. We previously showed that a single costimulatory signal delivered by an agonist Ab to OX40 (CD134) promotes accumulation of proliferating cells and promotes differentiation to effector CD4 T cells capable of secreting IFN-gamma. In this study, we determined whether OX40 costimulation requires supporting costimulatory or differentiation signals to drive acquisition of effector T cell function. We report that OX40 engagement drives effector T cell differentiation in the absence of CD28 and CD40 signals. Two important regulators of Th1 differentiation, IL-12R and T-bet, also are not required for acquisition of effector function in CD4 T cells responsive to OX40 stimulation. Finally, we show that CD25-deficient CD4 T cells produce little IFN-gamma in the presence of OX40 costimulation compared with wild type, suggesting that IL-2R signaling is required for efficient OX40-mediated differentiation to IFN-gamma secretion.

Sorting by the cytoplasmic domain of the amyloid precursor protein binding receptor SorLA

SorLA/LR11 (250 kDa) is the largest and most composite member of the Vps10p-domain receptors, a family of type 1 proteins preferentially expressed in neuronal tissue. SorLA binds several ligands, including neurotensin, platelet-derived growth factor-bb, and lipoprotein lipase, and via complex-formation with the amyloid precursor protein it downregulates generation of Alzheimer's disease-associated Abeta-peptide. The receptor is mainly located in vesicles, suggesting a function in protein sorting and transport. Here we examined SorLA's trafficking using full-length and chimeric receptors and find that its cytoplasmic tail mediates efficient Golgi body-endosome transport, as well as AP-2 complex-dependent endocytosis. Functional sorting sites were mapped to an acidic cluster-dileucine-like motif and to a GGA binding site in the C terminus. Experiments in permanently or transiently AP-1 mu1-chain-deficient cells established that the AP-1 adaptor complex is essential to SorLA's transport between Golgi membranes and endosomes. Our results further implicate the GGA proteins in SorLA trafficking and provide evidence that SNX1 and Vps35, as parts of the retromer complex or possibly in a separate context, are engaged in retraction of the receptor from endosomes.

Crystal structure of the IL-15-IL-15Ralpha complex, a cytokine-receptor unit presented in trans

Interleukin 15 (IL-15) and IL-2, which promote the survival of memory CD8(+) T cells and regulatory T cells, respectively, bind receptor complexes that share beta- and gamma-signaling subunits. Receptor specificity is provided by unique, nonsignaling alpha-subunits. Whereas IL-2 receptor-alpha (IL-2Ralpha) is expressed together in cis with the beta- and gamma-subunits on T cells and B cells, IL-15Ralpha is expressed in trans on antigen-presenting cells. Here we present a 1.85-A crystal structure of the human IL-15-IL-15Ralpha complex. The structure provides insight into the molecular basis of the specificity of cytokine recognition and emphasizes the importance of water in generating this very high-affinity complex. Despite very low IL-15-IL-2 sequence homology and distinct receptor architecture, the topologies of the IL-15-IL-15Ralpha and IL-2-IL-2Ralpha complexes are very similar. Our data raise the possibility that IL-2, like IL-15, might be capable of being presented in trans in the context of its unique receptor alpha-chain.

Differential role of IL-2R signaling for CD8+ T cell responses in acute and chronic viral infections

IL-2 is a cytokine with multiple and even divergent functions; it has been described as a key cytokine for in vitro T cell proliferation but is also essential for down-regulating T cell responses by inducing activation-induced cell death as well as regulatory T cells. The in vivo analysis of IL-2 function in regulating specific T cell responses has been hampered by the fact that mice deficient in IL-2 or its receptors develop lymphoproliferative diseases and/or autoimmunity. Here we generated chimeric mice harboring both IL-2R-competent and IL-2R-deficient T cells and assessed CD8+ T cell induction, function and maintenance after acute or persistent viral infections. Induction and maintenance of CD8+ T cells were relatively independent of IL-2R signaling during acute/resolved viral infection. In marked contrast, IL-2 was crucial for secondary expansion of memory CD8+ T cells and for the maintenance of virus-specific CD8+ T cells during persistent viral infections. Thus, depending on the chronicity of antigen exposure, IL-2R signaling is either essential or largely dispensable for induction and maintenance of virus-specific CD8+ T cell responses.

Function of the IL-2R for Thymic and Peripheral CD4+CD25+ Foxp3+ T Regulatory Cells

IL-2 contributes to the production, function, and homeostasis of CD4+CD25+ T(reg) cells. However, it remains uncertain whether IL-2 is essential for the development of T(reg) cells in the thymus, their homeostasis in the periphery, or both. The present study was undertaken to investigate the contribution of IL-2 during thymic T(reg) cell development and its maintenance in peripheral immune tissue. Relying on genetic mouse models where IL-2R signaling was either completely blocked or selectively inhibited in peripheral CD4+CD25+ T(reg) cells, we show that the IL-2/IL-2R interaction is active in the thymus at the earliest stage of the development of T(reg) cells to promote their expansion and to up-regulate Foxp3 and CD25 to normal levels. Furthermore, CD4+CD25+Foxp3+ T(reg) cells with impaired IL-2-induced signaling persist in the periphery and control autoimmunity without constant thymic output. These peripheral T(reg) cells with poor responsiveness to IL-2 exhibited slower growth and extended survival in vivo, somewhat lower suppressive activity, and poor IL-2-dependent survival in vitro. Mixed thymic and bone marrow chimeric mice showed that wild-type-derived T(reg) cells were substantially more effective in populating peripheral immune tissue than T(reg) cells with impaired IL-2 signaling. Collectively, these data support the notion that normally IL-2 is a dominant mechanism controlling the number of thymic and peripheral T(reg) cells.

Gene therapy improves immune function in preadolescents with X-linked severe combined immunodeficiency

Retroviral gene therapy can restore immunity to infants with X-linked severe combined immunodeficiency (XSCID) caused by mutations in the IL2RG gene encoding the common gamma chain (gammac) of receptors for interleukins 2 (IL-2), -4, -7, -9, -15, and -21. We investigated the safety and efficacy of gene therapy as salvage treatment for older XSCID children with inadequate immune reconstitution despite prior bone marrow transplant from a parent. Subjects received retrovirus-transduced autologous peripherally mobilized CD34(+) hematopoietic cells. T-cell function significantly improved in the youngest subject (age 10 years), and multilineage retroviral marking occurred in all 3 children.

Ectopic retroviral expression of LMO2, but not IL2Rgamma, blocks human T-cell development from CD34+ cells: implications for leukemogenesis in gene therapy

The occurrence of leukemia in a gene therapy trial for SCID-X1 has highlighted insertional mutagenesis as an adverse effect. Although retroviral integration near the T-cell acute lymphoblastic leukemia (T-ALL) oncogene LIM-only protein 2 (LMO2) appears to be a common event, it is unclear why LMO2 was preferentially targeted. We show that of classical T-ALL oncogenes, LMO2 is most highly transcribed in CD34+ progenitor cells. Upon stimulation with growth factors typically used in gene therapy protocols transcription of LMO2, LYL1, TAL1 and TAN1 is most prominent. Therefore, these oncogenes may be susceptible to viral integration. The interleukin-2 receptor gamma chain (IL2Rgamma), which is mutated in SCID-X1, has been proposed as a cooperating oncogene to LMO2. However, we found that overexpressing IL2Rgamma had no effect on T-cell development. In contrast, retroviral overexpression of LMO2 in CD34+ cells caused severe abnormalities in T-cell development, but B-cell and myeloid development remained unaffected. Our data help explain why LMO2 was preferentially targeted over many of the other known T-ALL oncogenes. Furthermore, during T-cell development retrovirus-mediated expression of IL2Rgamma may not be directly oncogenic. Instead, restoration of normal IL7-receptor signaling may allow progression of T-cell development to stages where ectopic LMO2 expression causes aberrant thymocyte growth.

In vivo efficacy of systemic tumor targeting of a viral RNA vector with oncolytic properties using a bispecific adapter protein

The aim of the study was: i) to specifically target tumor tissue by Newcastle disease virus (NDV) with oncolytic properties, ii) to improve the delivery system for systemic application of NDV via a bispecific adapter protein and iii) to investigate anti-tumor activity and side-effects. We selected two oncolytic virus strains, one native and the other recombinant, which showed multicyclic replication patterns in tumor cells. In order to reduce normal cell binding, they were modified by preincubation with a recombinant bispecific protein which blocks the viral native cell binding site and introduces a new binding site for a tumor-associated target (in this study, the interleukin-2-receptor, IL-2R). After intravenous transfer to mice, uptake of modified NDV in liver, spleen, kidney and lung was greatly reduced in comparison to unmodified NDV as determined by RRT-PCR of viral M gene copies. In IL-2R+ tumor bearing mice, the same assay revealed a high replication efficiency of the modified virus in the tumor tissue. Tumor therapy experiments showed that the side-effects induced by systemic application were greatly reduced by the adapter protein and that the anti-tumor effects were mostly undiminished. The demonstration of significant systemic anti-tumor activity of this viral vector suggests potential for augmentation by inclusion of one or more therapeutic genes.

Elevated levels of interferon ?-inducible protein-10 and epithelial neutrophil-activating peptide-78 in patients with pulmonary sarcoidosis

OBJECTIVE AND BACKGROUND

Interferon gamma-inducible protein (IP)-10 and epithelial neutrophil-activating peptide (ENA)-78 belong to the CXC chemokine family and are important factors in inflammatory lung diseases. In sarcoidosis, the potential role of IP-10 to regulate the migration and activation of T-cells towards sites of sarcoid activity has been suggested.

METHODS

In this study, the concentrations of IP-10 and ENA-78 in the serum and BAL fluid of patients with different stages of active pulmonary sarcoidosis (n=41) and healthy subjects (n=12) were measured by enzyme-linked immunosorbent assay to evaluate the contribution of these CXC chemokines to this disease.

RESULTS

Serum and BAL fluid concentrations of IP-10 and BAL fluid levels of ENA-78 in patients with sarcoidosis were significantly higher than those in control subjects. The serum levels of IP-10 were significantly increased only in patients with stages I and II sarcoidosis, while BAL fluid levels of ENA-78 were increased only in stage III sarcoidosis. In addition, serum concentrations of IP-10 were elevated in patients with extrapulmonary lesions compared with those without such lesions. In patients with sarcoidosis, IP-10 concentrations in BAL fluid correlated with lymphocyte proportions in BAL fluid.

CONCLUSION

IP-10 may play an important role in regulating lymphocytes into the lung and that ENA-78 may be associated with lung parenchymal disease in pulmonary sarcoidosis.

The common gamma chain cytokines interleukin (IL)-2 and IL-7 indirectly modulate blood fluke development via effects on CD4+ T cells

The human pathogen Schistosoma mansoni exhibits a highly evolved and intricate relationship with its host, evading immune destruction while co-opting CD4(+) T cell-driven mechanisms to facilitate parasite development and egg excretion. Because the common gamma ( gamma (c)) chain cytokine interleukin (IL)-7 is also implicated in modulating schistosome development, we investigated whether this effect is mediated indirectly through the essential role that IL-7 plays in CD4(+) T cell growth and survival. We demonstrate that attenuated schistosome development in the absence of IL-7 results from dysregulated T cell homeostasis and not from disruption of direct interactions between schistosomes and IL-7. We also identify an indirect role that another gamma (c) chain cytokine plays in schistosome development, demonstrating that IL-2 expression by CD4(+) T cells is essential for normal parasite development. Thus, cytokines critical for CD4(+) T cell survival and function can mediate indirect but potent effects on developing schistosomes and underscore the importance of CD4(+) T cells in facilitating schistosome development.

Immunogenetics of CD4 Lymphocyte Count Recovery during Antiretroviral Therapy: An AIDS Clinical Trials Group Study

During antiretroviral therapy, CD4 lymphocyte count increases are modest in some patients despite virologic control. We explored whether polymorphisms in genes important for T cell expansion, survival, and apoptosis are associated with the magnitude of CD4 lymphocyte count recovery during antiretroviral therapy. We studied treatment-naive individuals who achieved sustained control of plasma viremia (<400 HIV-1 RNA copies/mL) for at least 48 weeks after initiation of antiretroviral therapy and compared genotypes among individuals who had an increase of either <200 or > or =200 CD4 cells/mm3 from baseline. A total of 137 single-nucleotide polymorphisms across 17 genes were characterized in 873 study participants. In multivariate analyses that controlled for clinical variables, polymorphisms in genes encoding tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), TNF- alpha , Bcl-2-interacting molecule (Bim), interleukin (IL)-15, and IL-15 receptor alpha chain (IL-15R alpha ) were associated with the magnitude of the increase in CD4 lymphocyte count, as were haplotypes in genes encoding interferon- alpha , IL-2, and IL-15R alpha (P < .05, for each). Multifactor dimensionality reduction identified a gene-gene interaction between IL-2/IL-15 receptor common beta chain and IL-2/IL-7/IL-15 receptor common gamma chain. Immune recovery during antiretroviral therapy is a complex phenotype that is influenced by multiple genetic variants. Future studies should validate these tentative associations and define underlying mechanisms.

X-SCID transgene leukaemogenicity

Gene therapy has been remarkably effective for the immunological reconstitution of patients with severe combined immune deficiency, but the occurrence of leukaemia in a few patients has stimulated debate about the safety of the procedure and the mechanisms of leukaemogenesis. Woods et al. forced high expression of the corrective therapeutic gene IL2RG, which encodes the gamma-chain of the interleukin-2 receptor, in a mouse model of the disease and found that tumours appeared in a proportion of cases. Here we show that transgenic IL2RG does not necessarily have potent intrinsic oncogenic properties, and argue that the interpretation of this observation with respect to human trials is overstated.

Is IL2RG oncogenic in T-cell development?

The gene IL2RG encodes the gamma-chain of the interleukin-2 receptor and is mutated in patients with X-linked severe combined immune deficiency (X-SCID). Woods et al. report the development of thymus tumours in a mouse model of X-SCID after correction by lentiviral overexpression of IL2RG and claim that these were caused by IL2RG itself. Here we find that retroviral overexpression of IL2RG in human CD34+ cells has no effect on T-cell development, whereas overexpression of the T-cell acute lymphoblastic leukaemia (T-ALL) oncogene LMO2 leads to severe abnormalities. Retroviral expression of IL2RG may therefore not be directly oncogenic--rather, the restoration of normal signalling by the interleukin-7 receptor to X-SCID precursor cells allows progression of T-cell development to stages that are permissive for the pro-leukaemic effects of ectopic LMO2.

FOXP3 controls regulatory T cell function through cooperation with NFAT

Antigen stimulation of immune cells activates the transcription factor NFAT, a key regulator of T cell activation and anergy. NFAT forms cooperative complexes with the AP-1 family of transcription factors and regulates T cell activation-associated genes. Here we show that regulatory T cell (Treg) function is mediated by an analogous cooperative complex of NFAT with the forkhead transcription factor FOXP3, a lineage specification factor for Tregs. The crystal structure of an NFAT:FOXP2:DNA complex reveals an extensive protein-protein interaction interface between NFAT and FOXP2. Structure-guided mutations of FOXP3, predicted to progressively disrupt its interaction with NFAT, interfere in a graded manner with the ability of FOXP3 to repress expression of the cytokine IL2, upregulate expression of the Treg markers CTLA4 and CD25, and confer suppressor function in a murine model of autoimmune diabetes. Thus by switching transcriptional partners, NFAT converts the acute T cell activation program into the suppressor program of Tregs.

Both integrated and differential regulation of components of the IL-2/IL-2 receptor system

Interleukin-2 was discovered in 1976 as a T-cell growth factor. It was the first type I cytokine cloned and the first for which a receptor component was cloned. Its importance includes its multiple actions, therapeutic potential, and lessons for receptor biology, with three components differentially combining to form high, intermediate, and low-affinity receptors. IL-2Ralpha and IL-2Rbeta, respectively, are markers for double-negative thymocytes and regulatory T-cells versus memory cells. gamma(c), which is shared by six cytokines, is mutated in patients with X-linked severe-combined immunodeficiency. We now cover an under-reviewed area-the regulation of genes encoding IL-2 and IL-2R components, with an effort to integrate/explain this knowledge.

Circulating gamma delta T cells in response to Salmonella enterica serovar enteritidis exposure in chickens

gammadelta T cells are considered crucial to the outcome of various infectious diseases. The present study was undertaken to characterize gammadelta (T-cell receptor 1(+) [TCR1(+)]) T cells phenotypically and functionally in avian immune response. Day-old chicks were orally immunized with Salmonella enterica serovar Enteritidis live vaccine or S. enterica serovar Enteritidis wild-type strain and infected using the S. enterica serovar Enteritidis wild-type strain on day 44 of life. Between days 3 and 71, peripheral blood was examined flow cytometrically for the occurrence of gammadelta T-cell subpopulations differentiated by the expression of T-cell antigens. Three different TCR1(+) cell populations were found to display considerable variation regarding CD8alpha antigen expression: (i) CD8alpha(+high) TCR1(+) cells, (ii) CD8alpha(+dim) TCR1(+) cells, and (iii) CD8alpha(-) TCR1(+) cells. While most of the CD8alpha(+high) TCR1(+) cells expressed the CD8alphabeta heterodimeric antigen, the majority of the CD8alpha(+dim) TCR1(+) cells were found to express the CD8alphaalpha homodimeric form. After immunization, a significant increase of CD8alphaalpha(+high) gammadelta T cells was observed within the CD8alpha(+high) TCR1(+) cell population. Quantitative reverse transcription-PCR revealed reduced interleukin-7 receptor alpha (IL-7Ralpha) and Bcl-x expression and elevated IL-2Ralpha mRNA expression of the CD8alphaalpha(+high) gammadelta T cells. Immunohistochemical analysis demonstrated a significant increase of CD8alpha(+) and TCR1(+) cells in the cecum and spleen and a decreased percentage of CD8beta(+) T cells in the spleen after Salmonella immunization. After infection of immunized animals, immune reactions were restricted to intestinal tissue. The study showed that Salmonella immunization of very young chicks is accompanied by an increase of CD8alphaalpha(+high) gammadelta T cells in peripheral blood, which are probably activated, and thus represent an important factor for the development of a protective immune response to Salmonella organisms in chickens.

G protein-coupled receptor 83 overexpression in naive CD4+CD25- T cells leads to the induction of Foxp3+ regulatory T cells in vivo

Foxp3 functions as a lineage specification factor for the development of naturally occurring thymus-derived CD4+CD25+ regulatory T (Treg) cells. Recent evidence suggests that naive Foxp3-CD4+CD25- T cells can be converted in the periphery into Foxp3+ Treg cells. In this study, we have identified the G protein-coupled receptor (GPR)83 to be selectively up-regulated by CD4+CD25+ Treg cells of both murine and human origin in contrast to naive CD4+CD25- or recently activated T cells. Furthermore, GPR83 was induced upon overexpression of Foxp3 in naive CD4+CD25- T cells. Transduction of naive CD4+CD25- T cells with GPR83-encoding retroviruses did not confer in vitro suppressive activity. Nevertheless, GPR83-transduced T cells were able to inhibit the effector phase of a severe contact hypersensitivity reaction of the skin, indicating that GPR83 itself or GPR83-mediated signals conferred suppressive activity to conventional CD4+ T cells in vivo. Most strikingly, this in vivo acquisition of suppressive activity was associated with the induction of Foxp3 expression in GPR83-transduced CD4+ T cells under inflammatory conditions. Our results suggest that GPR83 might be critically involved in the peripheral generation of Foxp3+ Treg cells in vivo.

Age-related accumulation of a novel CD44 + CD25lowgammadelta T-cell population in hematopoietic organs of the mouse

We discovered a novel population of gammadelta T cells in the mouse that accumulates with age in hematopoietic organs, but not in epithelia. These cells are CD25low (an unusual phenotype for gammadelta T cells in the mouse); express higher levels of TCRgammadelta and CD44 than do CD25- gammadelta T cells; mainly express Vgamma2, Vgamma3, and Vgamma4 chains; and are largely quiescent. A very similar cell population appears in the late stages of fetal thymus organ cultures, suggesting that the accumulation of CD44 + CD25lowTCRgammadelta + cells is a response to stress induced by aging in vivo or by culture in vitro. The precursors of CD44 + CD25lowTCRgammadelta + cells are generated during fetal or very young adult life, as this population was undetectable in aged recipients of bone marrow from old or young donors. CD44 + CD25lowTCRgammadelta + cells may be a biomarker of aging, but could also play a role in the inflammatory changes that accompany aging.

Interleukin-2 signals during priming are required for secondary expansion of CD8+ memory T cells

Although interleukin-2 (IL-2) was initially characterized as the primary T-cell growth factor following in vitro activation, less is known about its role in shaping T-cell responses to acute infections in vivo. The use of IL-2- or IL-2-receptor-deficient mice is problematic owing to their early development of autoimmunity, attributable to the central role of IL-2 in the generation, maintenance and function of CD4+CD25+ regulatory T cells. To bypass these inherent difficulties, we have studied the effect of IL-2 on T-cell responses to acute infections by adopting a mixed chimaera strategy in which T cells lacking the high-affinity IL-2 receptor could be studied in an otherwise healthy mouse containing a full complement of regulatory T cells. Here we show that although IL-2 signalling to pathogen-specific CD8+ T cells affects the number of developing effector and memory cells very little, it is required for the generation of robust secondary responses. This is not due to an altered T-cell-receptor repertoire development or selection, and does not reflect an acute requirement for IL-2 during secondary activation and expansion. Rather, we demonstrate a previously unappreciated role for IL-2 during primary infection in programming the development of CD8+ memory T cells capable of full secondary expansion. These results have important implications for the development of vaccination or immunotherapeutic strategies aimed at boosting memory T-cell function.