Decreased expression of membrane IL-5 receptor alpha on human eosinophils: II. IL-5 down-modulates its receptor via a proteinase-mediated process

In the accompanying study, we demonstrated that following Ag challenge, membrane (m)IL-5Ralpha expression is attenuated on bronchoalveolar lavage eosinophils, soluble (s)IL-5Ralpha is detectable in BAL fluid in the absence of increased steady state levels of sIL-5Ralpha mRNA, and BAL eosinophils become refractory to IL-5 for ex vivo degranulation. We hypothesized that IL-5 regulates its receptor through proteolytic release of mIL-5Ralpha, which in turn contributes to the presence of sIL-5Ralpha. Purified human peripheral blood eosinophils were incubated with IL-5 under various conditions and in the presence of different pharmacological agents. A dose-dependent decrease in mIL-5Ralpha was accompanied by an increase in sIL-5Ralpha in the supernatant. IL-5 had no ligand-specific effect on mIL-5Ralpha or sIL-5Ralpha mRNA levels. The matrix metalloproteinase-specific inhibitors BB-94 and GM6001 and tissue inhibitor of metalloproteinase-3 partially inhibited IL-5-mediated loss of mIL-5Ralpha, suggesting that sIL-5Ralpha may be produced by proteolytic cleavage of mIL-5Ralpha. IL-5 transiently reduced surface expression of beta-chain, but had no effect on the expression of GM-CSFRalpha. Pretreatment of eosinophils with a dose of IL-5 that down-modulated mIL-5Ralpha rendered these cells unable to degranulate in response to further IL-5 stimulation, but they were fully responsive to GM-CSF. These findings suggest that IL-5-activated eosinophils may lose mIL-5Ralpha and release sIL-5Ralpha in vivo, which may limit IL-5-dependent inflammatory events in diseases such as asthma.

[Polymorphism of interleukins and interleukin receptor genes: population distribution and association with atopic bronchial asthma]

Population distribution and pathogenetic significance for bronchial asthma (BA) of the eight polymorphic variants of six interleukin--(IL) and interleukin receptor genes, C-589T, G/C 3'-UTR IL4, C-703T IL5, T113M IL9, Q551R, 150V IL4RA, and G1972A IL5RB, was examined. In the population samples of Russians, Tajiks, Buryats, and Tuvinians racial and ethnic specificity of these polymorphisms was established. These specific features were manifested as population-specific "enetic portraits" in respect of polymorphic allele frequencies. Analysis of the BA patients and their relatives from Tomsk by use of transmission/disequilibrium test (TDT) revealed the presence of a statistically significant association between the C-703 IL5 allele and the disease (P = 0.005). This is the first evidence of an association between the IL5 gene polymorphism and BA.

Expression of interleukin-10 and its receptor is up-regulated in early pregnant versus cycling human endometrium

Previous reports suggest that systemic and/or placental presence of T helper 2-type cytokines would be supportive of normal pregnancy. Among these cytokines, IL-10 is thought to be produced at the feto-maternal interface to control fetal-ablating immune responses. However, expression of IL-10 in nonhemopoietic maternal cells of the human uterus has not been characterized in detail. Thus, we studied the expression and modulation of the cytokine and its receptor in human endometrial cells obtained in different phases of the cycle and in early pregnancy. Both cycling and pregnant endometrium express the genes for IL-10 and its receptor, but secretion of the cytokine was significantly increased in decidual cultures compared with that by endometrial cells in both proliferative and secretory phases of the cycle. Similarly, the expression of IL-10 receptor mRNA was up-regulated in early decidua compared with that in menstrual cycle-dependent endometrium. IL-1beta, but not gonadal steroid hormones, was able to directly increase endometrial/decidual IL-10 production. Based on the activity of IL-10 in other nonhemopoietic cell populations, we also evaluated its potential effects on TNFalpha secretion and proliferation of endometrial/decidual cells, but we were unable to demonstrate any direct role of IL-10 as a regulator of these specific functions. It is evident that IL-10 and its receptor are normal constituents of endometrium and early decidua, and their up-regulation during early pregnancy may participate in the T helper type 2 predominance at the feto-maternal interface. The inability of the cytokine to exert autocrine effects on TNFalpha secretion and proliferation of decidual cells leads to speculation that the cytokine acts mostly as a paracrine mediator able to affect maternal immune responses.

A critical role for IL-21 in regulating immunoglobulin production

The cytokine interleukin-21 (IL-21) is closely related to IL-2 and IL-15, and their receptors all share the common cytokine receptor gamma chain, gammac, which is mutated in humans with X-linked severe combined immunodeficiency disease (XSCID). We demonstrate that, although mice deficient in the receptor for IL-21 (IL-21R) have normal lymphoid development, after immunization, these animals have higher production of the immunoglobulin IgE, but lower IgG1, than wild-type animals. Mice lacking both IL-4 and IL-21R exhibited a significantly more pronounced phenotype, with dysgammaglobulinemia, characterized primarily by a severely impaired IgG response. Thus, IL-21 has a significant influence on the regulation of B cell function in vivo and cooperates with IL-4. This suggests that these gammac-dependent cytokines may be those whose inactivation is primarily responsible for the B cell defect in humans with XSCID.

Elevated production of interleukin-18 is associated with renal disease in patients with systemic lupus erythematosus

To investigate the production mechanism and proinflammatory role of the cytokine interleukin (IL-18) in lupus nephritis, we investigated the plasma concentrations of IL-18 and nitric oxide (NO) and the release of IL-18 and NO from mitogen-activated peripheral blood monomuclear cells (PBMC), in 35 SLE patients with renal disease (RSLE), 37 patients without renal disease (SLE) and 28 sex- and age-matched healthy control subjects (NC). IL-18 and NO concentrations were measured by ELISA and colourimetric non-enzymatic assay, respectively. Gene expressions of IL-18 and IL-18 receptor were analysed by RT-PCR. Plasma IL-18 and NO concentrations were significantly higher in RSLE than NC (both P < 0.01). Elevation of plasma IL-18 in RSLE correlated positively and significantly with SLE -disease activity index and plasma NO concentration (r = 0.623, P < 0.0001 and r = 0.455, P = 0.017, respectively), and the latter also showed a positive and significant correlation with plasma creatinine (r = 0.410, P = 0.034) and urea (r = 0.685, P < 0.0001). There was no significant difference in gene expressions of IL-18 and IL-18 receptor in PBMC among RSLE, SLE and NC. Percentage increase in culture supernatant IL-18 concentration was significantly higher in RSLE than SLE and NC (both P < 0.05). The basal NO release was significantly higher in RSLE than that in SLE and NC (both P < 0.005). IL-18 is therefore suggested to play a crucial role in the inflammatory processes of renal disease in SLE.

Interleukin-13 receptor in psoriatic keratinocytes: overexpression of the mRNA and underexpression of the protein

Although several cytokines and their receptors have been involved in the development of psoriasis, the etiology is still unknown. In this study we looked for genes possibly involved in the disease by the reverse transcription-polymerase chain reaction differential display technique in lesional and nonlesional skin biopsies from psoriatic patients. We found the mRNA of the alpha1 chain of the interleukin-13 receptor expressed differentially in psoriatic biopsies. By reverse transcription-polymerase chain reaction, we confirmed an overexpression of the alpha1 chain of the IL-13 receptor and alpha chain of the interleukin-4 receptor mRNA in lesional skin psoriatic biopsies, when compared with skin biopsies from healthy subjects (p<0.01). The nonlesional skin obtained from a region close to a lesional zone in psoriatic patients presented also an overexpression of these mRNA in 50% of the samples. Interleukin-13 and interleukin-4 were not detected either as mRNA or as the proteins in any of the biopsies from psoriatic patients or healthy subjects. A monoclonal antibody to the alpha1 chain of the interleukin-13 receptor detected the receptor in the epidermal keratinocytes of psoriatic patients and of healthy subjects; however, the positive antibody reaction was stronger in skin tissue from healthy subjects than in psoriatic lesional skin tissue (p<0.01), although the mRNA was overexpressed. As interleukin-13 is a pleiotropic immunoregulatory cytokine with a variety of effects on different cell types, including monocytes, B lymphocytes, mast cells, and keratinocytes, we suggest, based on our results, that the interleukin-13 receptor possibly plays an important part in the early inflammatory process of psoriasis; however, its function is lost in the psoriatic keratinocytes.

Interleukin-21 and the IL-21 receptor: novel effectors of NK and T cell responses

Interleukin (IL)-21 was recently discovered using a functional cloning approach based on expression of its receptor. It is similar in domain organization and primary sequence to IL-2 and IL-15. Like these cytokines, IL-21 uses the common gamma chain of the IL-2/15 receptor, which forms a heterodimeric receptor complex with IL-21R. IL-21 is produced by activated T cells, and it influences proliferation of T and B cells and cytolytic activity of natural killer cells. The elucidation of the unique biological effects of IL-21 represents an intense area of interest in current cytokine biology.

Comparison of interleukin-22 and interleukin-10 soluble receptor complexes

Interleukin-22 (IL-22) is a cellular homolog of IL-10 that stimulates the production of acute-phase reactants. IL-22 and IL-10 require different ligand-specific receptor chains (IL-22R and IL-10R1) but share a second receptor chain (IL-10R2) to initiate cellular responses. The quaternary structures and the ability of IL-22 and IL-10 to engage soluble (s) IL-10R1, IL-22R, IL-10R2 receptor chains were analyzed using size exclusion chromatography and surface plasmon resonance techniques. In contrast to IL-10, which is a homodimer, IL-22 is a monomer in solution that forms a 1:1 interaction with sIL-22R. Kinetic binding data reveal sIL-22R and sIL-10R1 exhibit specific nanomolar binding constants for IL-22 (k(on)/k(off) = 14.9 nM) and a monomeric isomer of IL-10 (IL-10M1) (k(on)/k(off) = 0.7 nM), respectively. In contrast, IL-10R2 exhibits essentially no affinity for IL-22 (K(eq) approximately 1 mM) or IL-10M1 (K(eq) approximately 2 mM) alone but displays a substantial increase in affinity for the IL-10/sIL-10R1 (K(eq) approximately 350 microM) and IL-22/sIL-22R (K(eq) approximately 45 microM) complexes. Three-dimensional models of IL-22 and IL-10 receptor complexes suggest two receptor residues (Gly-44 and Arg-96) are largely responsible for the marked differences in ligand affinity observed for sIL-10R1 and sIL-22R vs. sIL-10R2.

Gene therapy of X-linked severe combined immunodeficiency

Severe combined immunodeficiency (SCID) conditions appear to be the best possible candidates for a gene therapy approach. Transgene expression by lymphocyte precursors should confer to these cells a selective growth advantage that gives rise to long-lived T-lymphocytes. This rationale was used as a basis for a clinical trial of the SCID-X1 disorder caused by common gamma (gamma c) gene mutations. This trial consists of ex vivo retroviral-mediated (MFG-B2 gamma c vector) gammac gene transfer into marrow CD34+ cells in CH-296 fibronectin fragment-coated bags. Up to now, 9 patients with typical SCID-X1 diagnosed within the first year of life and lacking an HLA-identical donor have been enrolled. More than 2 years' assessment of 5 patients and more than 1 year for 7 patients provide evidence for full development of functional, mature T-cells in the absence of any adverse effects. Functional transduced natural killer cells are also detectable, although in low numbers. All but 1 patient with T-cell immunity have also developed immunoglobulin production, which has alleviated the need for intravenous immunoglobulin substitution despite a low detection frequency of transduced B-cells. These 8 patients are doing well and living in a normal environment. This yet successful gene therapy demonstrates that in a setting where transgene expression provides a selective advantage, a clinical benefit can be expected.

IL-22, in contrast to IL-10, does not induce Ig production, due to absence of a functional IL-22 receptor on activated human B cells

IL-22 is an IL-10 homologue that binds to and signals via the class II cytokine receptor (R) heterodimer IL-22RA1/CFR2-4 (IL-10R2), the latter chain being part of the IL-10R complex. Here, we report that, despite its structural similarity with IL-10, as well as its use of the common IL-10R2 chain, IL-22, in contrast to IL-10, is unable to induce Ig production by activated human B cells. Whereas culture of anti-CD40 mAb-stimulated splenic or tonsillar B cells in the presence of rIL-10 resulted in the production of IgG, IgG1, IgG3 and IgA, rIL-22, at concentrations ranging from 4 to 100 ng/ml, did not induce the production of any of these isotypes. Moreover, unlike rIL-10 which enhanced rIL-4-induced IgG4 and IgE production, rIL-22 was ineffective. Although activated B cells expressed transcripts for a soluble IL-22-binding protein (IL-22RA2), no mRNA for a transmembrane IL-22R (IL-22RA1) could be detected. The latter result was confirmed by the demonstration that rIL-22 failed to induce activation of STAT-3 and -5 in resting or activated B cells. Together, these data show that IL-22, in contrast to its homologue IL-10, is not involved in the immunological activity of B cells, which is due to the absence of a functional IL-22R at the surface of these cells.

Limited effect of recombinant porcine interleukin-12 on porcine lymphocytes due to a low level of IL-12 beta2 receptor

The cytokine interleukin-12 (IL-12) is a key molecule in the regulation of CD4 + T cell development and specifically potentiates T helper 1 responses in mouse and man. However, biological effects mediated by IL-12 have not been well defined in pigs. Herein, recombinant porcine IL-12 (rPoIL-12) was expressed in a swine poxvirus system as a biologically active heterodimer and used to stimulate bovine or swine lymphoblast cells. After 3 days of incubation, only bovine blasts were responsive to the rPoIL-12 treatment as monitored by cell proliferation in several independent trials. Similarly, i.m. administration of rPoIL-12 in the hind leg of 3-week-old pigs indicated a reduction in the number of interferon-gamma (IFN-gamma) producing lymphocytes isolated from inguinal lymph nodes. The porcine IL-12R beta2 (IL-12Rbeta2) sequence was cloned and results generated by reverse transcriptase polymerase chain reaction (RT-PCR) demonstrated that the expression of IL-12R on porcine blasts as measured by the relative levels of IL-12Rbeta2 mRNA was less than that in bovine blasts and are in agreement with the reduced proliferation response of swine blast cells to rPoIL-12 treatment. Real time PCR analysis demonstrated that after PBMC stimulation, bovine blasts had an 11-fold increase in IL-12Rbeta2 mRNA levels while porcine blasts had almost no change. These data support a mechanism for IL-12 stimulation in swine inconsistent with that observed in conventional models.

SATB1 targets chromatin remodelling to regulate genes over long distances

Eukaryotic chromosomes are organized inside the nucleus in such a way that only a subset of the genome is expressed in any given cell type, but the details of this organization are largely unknown. SATB1 ('special AT-rich sequence binding 1'), a protein found predominantly in thymocytes, regulates genes by folding chromatin into loop domains, tethering specialized DNA elements to an SATB1 network structure. Ablation of SATB1 by gene targeting results in temporal and spatial mis-expression of numerous genes and arrested T-cell development, suggesting that SATB1 is a cell-type specific global gene regulator. Here we show that SATB1 targets chromatin remodelling to the IL-2Ralpha ('interleukin-2 receptor alpha') gene, which is ectopically transcribed in SATB1 null thymocytes. SATB1 recruits the histone deacetylase contained in the NURD chromatin remodelling complex to a SATB1-bound site in the IL-2Ralpha locus, and mediates the specific deacetylation of histones in a large domain within the locus. SATB1 also targets ACF1 and ISWI, subunits of CHRAC and ACF nucleosome mobilizing complexes, to this specific site and regulates nucleosome positioning over seven kilobases. SATB1 defines a class of transcriptional regulators that function as a 'landing platform' for several chromatin remodelling enzymes and hence regulate large chromatin domains.

Expression and regulation of interleukin-10 and interleukin-10 receptor in rat astroglial and microglial cells

Activated glial cells crucially contribute to brain inflammatory responses. Interleukin-10 (IL-10) is an important modulator of glial cell responses in the brain. In the present study we describe the expression of IL-10 and the IL-10 receptor (IL-10R1) in primary cocultures of rat microglial and astroglial cells. Using quantitative RT-PCR and ELISA, we show that IL-10 mRNA expression and subsequent IL-10 secretion is time-dependently induced by lipopolysaccharide (LPS). IL-10R1, however, is constitutively expressed in glial cell cocultures, as shown by RT-PCR and immunocytochemistry. Radioligand binding studies using 125I-IL-10 reveal that rat glial cells express a single binding site with an apparent affinity of approximately 600 pm for human IL-10. Observations in enriched cultures of either microglial or astroglial cells indicate that both cell types express IL-10 mRNA and are capable of secreting IL-10. Both cell types also express IL-10R1 mRNA and protein. However, in glial cell cocultures immunoreactive IL-10R1 protein is predominantly observed in astrocytes, suggesting that microglial expression of IL-10R1 in cocultures is suppressed by astrocytes. In addition, exogenous IL-10 is highly potent in down-regulating LPS-induced IL-1beta and IL-10 mRNA, and, at a higher dose, IL-10R1 mRNA in untreated and LPS-treated cultures, suggesting that IL-10 autoregulates its expression and inhibits that of IL-1beta at the transcriptional level. Together the findings support the concept that IL-10, produced by activated microglial and astroglial cells, modulates glia-mediated inflammatory responses through high-affinity IL-10 receptors via paracrine and autocrine interactions.

Dichotomic nature of atopic dermatitis reflected by combined analysis of monocyte immunophenotyping and single nucleotide polymorphisms of the interleukin-4/interleukin-13 receptor gene: the dichotomy of extrinsic and intrinsic atopic dermatitis

Patients with atopic dermatitis display substantial immunologic abnormalities, among which elevated total IgE is considered as a hallmark; however, a subgroup of atopic dermatitis patients exhibits normal IgE levels, but mechanisms contributing to the so-called "intrinsic" or "nonallergic" form of atopic dermatitis are obscure. In order to unravel similarities and differences of both atopic dermatitis subtypes, the phenotype of monocytes, total serum IgE levels, and serum levels of cytokines regulating the IgE production from nonatopic individuals and patients with allergic rhinitis, and extrinsic and intrinsic atopic dermatitis were measured. Concomitantly, genomic DNA probes of all subjects were analyzed for single nucleotide polymorphisms of candidate genes of structures involved in the regulation of the IgE synthesis, such as interleukin-4 and the interleukin-4R/interleukin-13R. Our data show that the surface expression of the high- and low-affinity receptor for IgE (FcepsilonRI and FcepsilonRII/CD23) and the interleukin-4Ralpha chain were significantly elevated in monocytes from patients with extrinsic atopic dermatitis. Furthermore, serum levels of interleukin-13 were significantly increased in patients with intrinsic atopic dermatitis. In addition, the frequency of the interleukin-4Ralpha polymorphism C3223T and the interleukin-4 polymorphism C590T tended to be higher in extrinsic atopic dermatitis than in intrinsic atopic dermatitis. Altogether our findings indicate that intrinsic atopic dermatitis patients exhibit phenotypic and immunologic features, which differ from those of patients with extrinsic atopic dermatitis or other atopic disorders.

Molecular basis of the synergistic production of IL-1 receptor antagonist by human neutrophils stimulated with IL-4 and IL-10

In this study, we report that the release of IL-1 receptor antagonist (IL-1ra) from IL-4-stimulated neutrophils is markedly enhanced in the presence of IL-10. We also show that up-regulation of IL-1ra release by IL-10 in IL-4-stimulated neutrophils takes place through IL-1ra mRNA stabilization and enhancement of IL-1ra de novo synthesis. Furthermore, we report that the ability of IL-10 to up-regulate IL-1ra mRNA expression in IL-4-treated neutrophils requires 5-6 h and it is preceded by the acquisition of the capacity to activate Stat3 tyrosine phosphorylation. This latter response to IL-10 was strictly dependent on the levels of expression of IL-10R1, which were in fact significantly increased by IL-4 in cultured neutrophils via a signaling pathway sensitive to the serine/threonine kinase inhibitor H-7. Collectively, our data emphasize the central role of IL-10R1 expression in regulating cell responsiveness to IL-10. In addition, the fact that IL-10 strongly up-regulates IL-1ra production in IL-4-activated neutrophils uncovers a novel mechanism whereby IL-10 and IL-4 cooperate to negatively modulate the inflammatory responses.

Interleukin-10 polymorphisms in Spanish multiple sclerosis patients

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that may be an important regulator in multiple sclerosis (MS) pathogenesis. IL-10 gene contains three single nucleotide polymorphisms (SNPs) and two polymorphic microsatellites in the 5'-flanking region. Our aim was to ascertain if any of these polymorphic markers is associated or linked to MS among Spanish patients. We have genotyped 300 patients and 357 ethnically matched controls for the microsatellites, and most of them also for the promoter SNPs. We included in this study the parents of 63 patients in order to perform a TDT analysis as well. IL-10G12 allele was significantly increased in MS patients (17% versus 11% in controls; p=0.004; p(c)<0.05). No other allele showed a significant difference between patients and controls, and the TDT analysis yielded negative results. The data indicate that IL-10 is not a major susceptibility locus in MS, but in our population it might, however, have a minor role.

STAT4 serine phosphorylation is critical for IL-12-induced IFN-gamma production but not for cell proliferation

T helper 1 (T(H)1) differentiation and IFN-gamma production are crucial in cell-mediated immune responses. IL-12 is an important regulator of this process and mediates its effects through signal transducer and activator of transcription 4 (STAT4). IFN-gamma production is also regulated by the p38 mitogen-activated kinase pathway, although the mechanisms are ill-defined. We show here that GADD45-beta and GADD45-gamma can induce STAT4 S721 phosphorylation via the MKK6/p38 pathway. Thus, STAT4 could be a target that accounts for the defects in cell-mediated immunity associated with perturbations in the p38 pathway. To investigate the biological significance of STAT4 S721 phosphorylation, we reconstituted primary spleen cells from STAT4-deficient mice with wild-type and mutated STAT4, by using a retroviral gene transduction. We demonstrated that expression of wild-type STAT4, but not the S721A mutant, restored normal T(H)1 differentiation and IFN-gamma synthesis. The inability of STAT4 S721 to restore IFN-gamma production was not caused by decreased IL-12R expression because the STAT4 S721 mutant also failed to restore IFN-gamma production in STAT4-deficient IL-12Rbeta2 transgenic cells. Importantly, STAT4 S721A-transduced cells showed normal proliferative response to IL-12, illustrating that serine phosphorylation is not required for IL-12-induced proliferation. Additionally, the results imply the existence of STAT4 serine phosphorylation-dependent and -independent target genes. We conclude that phosphorylation of STAT4 on both tyrosine and serine residues is important in promoting normal T(H)1 differentiation and IFN-gamma secretion.

Mutation and functional analysis of IL-13 receptors in human malignant glioma cells

We have previously demonstrated that human brain tumor cells, in particular glioblastoma multiforme (GBM), express abundant receptors for interleukin-13 on the cell surface. These receptors are composed of IL-13 receptor (IL-13R)alpha1, IL-13Ralpha2, and IL-4Ralpha chains. The significance of overexpression of IL-13R on tumor cells is not known. Because expression of IL-13R on glioma cells is an unexpected phenomenon, we examined whether these receptors are polymorphic. Therefore, we analyzed cDNA for IL-13Ralpha1 and IL-13Ralpha2 chain genes by PCR-based single-strand conformation polymorphism and direct sequencing techniques for a possible polymorphism in 19 GBM, one normal human astrocyte, and two fibroblast cell lines. All analyzed samples except normal astrocytes overexpressed IL-13Ralpha2; however, none of these cell lines showed a mutation in cDNA for IL-13Ralpha2 chain. In contrast, all GBM samples, normal astrocytes, and fibroblasts expressed mRNA for IL-13Ralpha1 with apparent single nucleotide polymorphism in the transmembrane domain. To study the function of IL-13R on brain tumor cells, we investigated the regulation of adhesion molecules by IL-13 as assessed by flow cytometric analysis. A172 cell line expressed a low level of vascular cell adhesion molecule-1 (VCAM-1), while U251 and LA1-5g cell lines expressed intercellular adhesion molecule-1 (ICAM-1). On the other hand E-selectin was not expressed in any cell lines. Interestingly, IL-13 increased the expression level of VCAM-1 in A172 cell line in a dose- and time-dependent manner. However, IL-13 did not modulate any other adhesion molecules. These results suggest that IL-13R on GBM cells are not rearranged but appear to be functional.

Gene transfer of CD154 and IL12 cDNA induces an anti-leukemic immunity in a murine model of acute leukemia

IL12 is an essential cytokine for the generation of T helper 1 response, natural killer (NK) cells and cytotoxic T lymphocyte (CTL) stimulation. CD154 triggers CD40 on antigen-presenting cells, thus inducing antigen presentation to the immune system and production of IL12. As IL12 and CD154 share several pathways mediating immune response, we investigated in an aggressive murine model of acute leukemia the relative antileukemic efficiency of IL12, CD154 and IL12 + CD154 gene transfer. Live leukemic cells transduced by IL12, CD154, and IL12 + CD154 showed reduced leukemogenicity but CD154 protective effect was reduced when 10(6) leukemic cells were injected. Vaccines with lethally irradiated IL12-transduced cells were able to cure mice previously injected with 10(4) leukemic cells and adoptive transfer of IL12-induced antileukemic immunity protected recipient mice. NK cytotoxicity was enhanced in mice vaccinated with leukemic cells transduced by IL12, CD154, and CD154 + IL12. IL12 transduced cells induced IFN-gamma mRNA in CD4(+) and CD8(+) T cells isolated from the spleen of vaccinated animals, however, in vivo depletion experiments showed that IL12 vaccine effect was CD4(+) but not CD8(+) T cell dependent. We conclude that IL12 gene is a more potent candidate than CD154 for gene therapy of acute leukemia.

IL-13Ralpha2 is a glioma-restricted receptor for interleukin-13

We have found that binding sites for interleukin-13 (IL-13) are overexpressed in a vast majority of high-grade astrocytomas (HGAs). These binding sites for IL-13 are distinct from the physiological receptor in that it does not bind IL-4. We also demonstrated that IL-13 receptor alpha 2 protein chain (IL-13Ralpha2), an IL-4-independent receptor for IL-13, is abundant among HGAs, but not in normal organs. To examine if IL-13Ralpha2 is the tumor-associated site for IL-13, we stably transfected normal Chinese hamster ovary (CHO) cells and glioma G-26 cells to express either human (h) or murine (m) IL-13Ralpha2. CHO-hIL-13Ralpha2(+) cells and G-26-h/mIL-13Ralpha2(+) cells, and not CHO and G-26 parental or mock-transfected cells, specifically bound IL-13 in an IL-4-independent manner. The IL-13Ralpha2(+) cells also became highly susceptible to the killing by an IL-13-based cytotoxic fusion protein. In loss of function studies, a HGA cell line, SNB-19, was transfected with antisense (as) hIL-13Ralpha2. as-SNB-19-hIL-13Ralpha2(+) cells lost their natural affinity towards IL-13 and became resistant to IL-13-based cytotoxins. The fact, that IL-13Ralpha2-positive cells bind IL-13 independent of IL-4, become susceptible to IL-13 cytotoxins, and cells deprived of IL-13Ralpha2 receptor lose these features, demonstrates that IL-13Ralpha2 is the brain tumor-associated receptor for IL-13.

Human lung myofibroblasts as effectors of the inflammatory process: the common receptor gamma chain is induced by Th2 cytokines, and CD40 ligand is induced by lipopolysaccharide, thrombin and TNF-alpha

The common gamma (gamma c) chain, shared by Th1 and Th2 cytokines, is fundamental for the activation of hematopoietic cells, but its role in non-hematopoietic tissues has not been explored. Here we show that in normal lung fibroblasts IL-4 and IL-13 induce the expression of the gamma c chain and its association with Janus kinase (JAK) 3, while lung myofibroblasts constitutively express a gamma c chain displaying a limited association with JAK3. In the latter cells, without exogenous cytokines, gamma c/JAK3 controls, through autocrine loops, tyrosine kinase (TYK) 2 phosphorylation and the balance between functional (IL-4Ralpha, IL-13Ralpha 1) and decoy (IL-13Ralpha 2) high-affinity receptors. Moreover, JAK3 is also associated with a pre-phosphorylated IL-4Ralpha and CD40. This novel "heterotrimer" (p-IL-4Ralpha, CD40/JAK3) is functional and controls STAT3 phosphorylation and CD40 expression, as shown by use of the specific JAK3 inhibitor WHI-P31. In basal culture conditions, CD40 signaling could be induced by the transient establishment of inter-fibroblastic CD40/CD40 ligand (CD40L) functional bridges. Indeed, powerful pro-inflammatory stimuli such as lipopolysaccharide and thrombin can rapidly mobilize CD40L at the surface of lung myofibroblasts. These interactions are modified by IL-13, which triggers the formation of a new type of functional receptor (p-IL-4Ralpha /IL-13Ralpha 1/gamma c) and also the recruitment and the phosphorylation of JAK3. Treatment with JAK3 inhibitors blocks IL-13-induced phosphorylation of JAK2, TYK2 and STAT3, but not of JAK1 and STAT6. These data underline (1) the pivotal role of the gamma c chain, CD40/CD40L, JAK3 and IL-13 in the inflammatory-like activation of lung myofibroblasts, (2) the cell-type restraint effects of IL-13 on these cells, and (3) the potential usefulness of JAK3 inhibitors in the treatment of asthma.

IL-13 signal transduction in human monocytes: phosphorylation of receptor components, association with Jaks, and phosphorylation/activation of Stats

Interleukin (IL)-13 regulates monocyte function and is a potent stimulator of 15-lipoxygenase expression. In different cell types, the functional IL-13 receptor complex can be comprised of variable protein components and has not been thoroughly examined in human monocytes. Here, we identify the receptor components and upstream signaling events initiated by IL-13 in primary human blood monocytes. The expression, phosphorylation and associated Jak kinases of the known, variable receptor components, IL-4R(alpha), IL-2Rgammac, IL-13R(alpha)1 and IL-13R(alpha)2, were examined. We determined that IL-4R(alpha) and IL13R(alpha)1 are phosphorylated upon exposure to IL-13. Although IL-2Rgammac is also expressed, it is not phosphorylated upon exposure to IL-13. Evaluation of the presence of IL-13R(alpha)2 failed to reveal significant mRNA or protein expression. Earlier, our laboratory showed that IL-13 induced the phosphorylation of Jak2 and Tyk2 in monocytes and that expression of both Jaks was essential for downstream signaling by IL-13. Here, we report that Jak2 is associated with IL-4R(alpha), and Tyk2 is associated with the IL-13R(alpha)1 component of the IL-13 receptor complex. Additionally, Stat proteins 1alpha, 3, 5A, 5B, and 6 are phosphorylated in response to IL-13. Further, the nuclear translocation and DNA binding of each of these Stats were induced by IL-13. These data represent the first complete report of the functional IL-13 receptor complex and early signaling events in human monocytes. This information is critical for understanding the IL-13 response of monocytes in inflammation.

Cloning, expression analyses, and chromosomal location of porcine interleukin-18 receptor alpha chain (IL-18Ralpha)

We cloned and sequenced a cDNA that contains the coding sequence of the porcine interleukin-18 receptor alpha chain (PoIL-18Ralpha). Based on the conserved nucleotide sequences between human (HuIL-18Ralpha) and murine IL-18Ralpha (MuIL-18Ralpha), we performed reverse transcription-polymerase chain reaction (RT-PCR) with total RNA prepared from porcine peripheral blood lymphocytes (PBLs) stimulated with PoIL-12 to clone the cDNA of PoIL-18Ralpha. The open reading frame (ORF) of the PoIL-18Ralpha cDNA is 1620 base pairs (bp) in length and encodes 539 amino acids. The predicted amino acid sequence showed 68.2% and 50.2% identity to the human and murine amino acid sequences, respectively. Stimulation with concanavalin A (ConA) and IL-12, but not with IL-4, was shown to upregulate the expression of IL-18Ralpha mRNA in pig PBLs by RT-PCR analysis. Flow cytometric analysis also demonstrated that IL-18Ralpha was constitutively expressed on PoPBLs, and this expression was augmented by ConA stimulation. Furthermore, the PoIL-18Ralpha gene was mapped by fluorescence in situ hybridization (FISH) to porcine chromosome 3 (3q13-q14), near the location at which the IL-1beta gene had already been mapped. The present results will be helpful for understanding PoIL-18 and interferon gamma (IFN-gamma)-mediated T helper 1 (Th1) cell development.

Genetics, cytokines and human infectious disease: lessons from weakly pathogenic mycobacteria and salmonellae

Host genetic factors are important in determining the outcome of infections caused by intracellular pathogens, including mycobacteria and salmonellae, but until now have been poorly characterized. Recently, some individuals with severe infections due to otherwise weakly pathogenic mycobacteria (non-tuberculous mycobacteria or Mycobacterium bovis bacille Calmette-Guérin) or Salmonella species have been shown to be unable to produce or respond to interferon-gamma. This inability results from mutations in any of five genes encoding essential proteins of the type 1 cytokine cascade: interleukin-12p40, interleukin-12R beta 1, interferon-gamma R1, interferon-gamma R2 or STAT1. Ten syndromes have thus far been identified. Recent insights in genetically controlled host defense and susceptibility to mycobacterial disease are discussed.