Interleukin-11 modulates Th1/Th2 cytokine production from activated CD4+ T cells.

Recombinant human interleukin-11 (rHuIL-11) is a pleiotropic cytokine with effects on multiple cell types. rHuIL-11 reduces activated macrophage activity and downregulates production of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). In vitro and in vivo, rHuIL-11 inhibits production of key immunostimulatory cytokines, including IL-12 and interferon-gamma (IFN-gamma). rHuIL-11 has recently demonstrated immunomodulatory activity to downregulate IFN-gamma production, increase IL-4 production, and reduce inflammatory tissue injury in a human psoriasis clinical trial. The cellular mechanisms of these effects are not fully elucidated. We demonstrate here that expression of gp130 and IL-11 receptor (IL-11R) alpha mRNA, components of the IL-11R complex, are detected in human and murine CD4(+) and CD8(+) lymphocytes, suggesting that rHuIL-11 can directly interact with T cells. In a cell culture model of murine T cell differentiation, rHuIL-11 acts to inhibit IL-2 production as well as IL-12-induced IFN-gamma production and enhances IL-4 and IL-10 production. rHuIL-11 had no effect on T cell proliferation. The ability of rHuIL-11 to modulate cytokine production from activated CD4(+) T cells provides a mechanism through which rHuIL-11 may ameliorate such inflammatory diseases as psoriasis.

Interleukin-11 therapy selectively downregulates type I cytokine proinflammatory pathways in psoriasis lesions.

Psoriasis is a chronic inflammatory skin disease in which epidermal hyperplasia results from skin infiltration by type I T lymphocytes and release of associated cytokines. A multifunctional cytokine, rhIL-11, modulates macrophage and type I T-lymphocyte function in cell culture and shows anti-inflammatory activity in animal models. We are testing subcutaneous delivery of rhIL-11 to patients with psoriasis in a phase 1 open-label dose-escalation clinical trial. Tissue was obtained from lesional and uninvolved skin before and during treatment with rhIL-11 and was examined by histology/immunohistochemistry and quantitative RT-PCR. Expression of over 35 genes was examined in all patients, and multiple genetic markers of psoriasis were identified. Expression of numerous proinflammatory genes was elevated in psoriatic tissue compared with nonlesional skin. Seven of 12 patients responded well to rhIL-11 treatment. Amelioration of disease by rhIL-11, as shown by reduced keratinocyte proliferation and cutaneous inflammation, was associated with decreased expression of products of disease-related genes, including K16, iNOS, IFN-gamma, IL-8, IL-12, TNF-alpha, IL-1beta, and CD8, and with increased expression of endogenous IL-11. We believe that this is the first study in humans to indicate that type I cytokines can be selectively suppressed by an exogenous immune-modifying therapy. The study highlights the utility of pharmacogenomic monitoring to track patient responsiveness and to elucidate anti-inflammatory mechanisms.

Autocrine regulation of IL-12 receptor expression is independent of secondary IFN-gamma secretion and not restricted to T and NK cells.

The biological response to IL-12 is mediated through specific binding to a high affinity receptor complex composed of at least two subunits (designated IL-12Rbeta1 and IL-12Rbeta2) that are expressed on NK cells and activated T cells. The selective loss of IL-12Rbeta2 expression during Th2 T cell differentiation suggests that regulation of this receptor component may govern IL-12 responsiveness. In murine assays, down-regulation of IL-12Rbeta2 expression can be prevented by treatment with IFN-gamma, indicating that receptor expression and hence IL-12 responsiveness may be regulated, at least in part, by the local cytokine milieu. In this study, we report that cellular expression of both IL-12Rbeta1 and beta2 mRNA is increased in the lymph nodes of naive mice following systemic administration of murine rIL-12 (rmIL-12). Changes in IL-12R mRNA were associated with increased IFN-gamma secretion following ex vivo activation of lymph node cells with rmIL-12, indicating the presence of a functional receptor complex. Expression of IL-12R mRNA was not restricted to lymph node T cells, and its autocrine regulation was independent of secondary IFN-gamma secretion. Data from fractionated lymph node cells as well as rmIL-12-treated B cell-deficient mice suggest that IL-12-responsive B cells may represent an alternative cellular source for IFN-gamma production. However, the strength of the biological response to rmIL-12 is not governed solely by receptor expression, as rmIL-12-induced IFN-gamma secretion from cultured lymph node cells is accessory cell dependent and can be partially blocked by inhibition of B7 costimulation.

Interleukin-11 reduces T-cell-dependent experimental liver injury in mice.

Recombinant human interleukin-11 (rhIL-11) is a multifunctional cytokine that can reduce inflammation through the downregulation of multiple pro-inflammatory mediators from activated macrophages. rhIL-11 also inhibits production of several immunostimulatory cytokines such as IL-12 and interferon gamma (IFN-gamma) and has shown biological activity in multiple animal models of inflammatory disease consistent with immunomodulatory effects on macrophages and T cells. To further elucidate the anti-inflammatory activity of rhIL-11 in vivo, the effect of rhIL-11 in a model of Concanavalin A (Con-A)-induced T-cell-mediated hepatotoxicity was examined. Administration of a single dose of rhIL-11 before Con-A administration reduced centrilobular liver necrosis and enhanced survival. A dose-dependent reduction in serum levels of liver enzymes, tumor necrosis factor alpha (TNF-alpha), and IFN-gamma corresponded with this amelioration of liver damage. No significant change in infiltrating lymphocyte populations in the liver was observed following rhIL-11 treatment. Taken together, these results indicate that rhIL-11 ameliorates T-cell-mediated hepatic injury and suggests its therapeutic potential to treat inflammatory liver disease.

Interleukin-12 is capable of generating an antigen-specific Th1-type response in the presence of an ongoing infection-driven Th2-type response.

Previously we demonstrated that recombinant murine interleukin-12 (rmIL-12) administration can promote a primary Th1 response while suppressing the Th2 response in mice primed with 2,4, 6-trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH). The present studies examined the capacity of rmIL-12 to drive a Th1 response to TNP-KLH in the presence of an ongoing Th2-mediated disease. To establish a distinct Th2 response, we used a murine model of leishmaniasis. Susceptible BALB/c mice produce a strong Th2 response when infected with Leishmania major and develop progressive visceral disease. On day 26 postinfection, when leishmaniasis was well established, groups of mice were immunized with TNP-KLH in the presence or absence of exogenous rmIL-12. Even in the presence of overt infection, TNP-KLH-plus-rmIL-12-immunized mice were still capable of generating KLH-specific gamma interferon (IFN-gamma) as well as corresponding TNP-specific immunoglobulin G2a (IgG2a) titers. In addition, the KLH-specific IL-4 was suppressed in infected mice immunized with rmIL-12. However, parasite-specific IL-4 and IgG1 production with a lack of parasite-specific IFN-gamma secretion were maintained in all infected groups of mice including those immunized with rmIL-12. These data show that despite the ongoing infection-driven Th2 response, rmIL-12 was capable of generating an antigen-specific Th1 response to an independent immunogen. Moreover, rmIL-12 administered with TNP-KLH late in infection did not alter the parasite-specific cytokine or antibody responses.

High level overexpression of glucose transporter-4 driven by an adipose-specific promoter is maintained in transgenic mice on a high fat diet, but does not prevent impaired glucose tolerance.

High fat feeding is associated with impaired insulin action, an obese body composition, and down-regulation of glucose transporter-4 (GLUT4) expression in adipocytes. We recently showed that overexpression of GLUT4 selectively in adipocytes of transgenic mice using the aP2 (fatty acid-binding protein) promoter/enhancer results in enhanced glucose tolerance and adipocyte hyperplasia. Here, we fed these GLUT4-overexpressing transgenic mice a high fat (55%) or a low fat (10%) diet for 13-15 weeks to determine the role of alterations in GLUT4 expression in adipocytes in the development of insulin resistance and obesity, which are characteristic of high fat consumption. In nontransgenic mice, high fat feeding results in 45-50% reduction of GLUT4 levels in white and brown adipose tissue, with a parallel decrease in insulin-stimulated glucose transport. In transgenic mice receiving the low fat diet, GLUT4 is overexpressed 20-fold in white and 4-fold in brown adipose tissue. Glucose transport in epididymal adipocytes is increased 20-fold in the basal state and 6-fold in the insulin-stimulated state. Even after transgenic mice are fed a high fat diet, GLUT4 expression and glucose transport in their adipocytes remains 14- to 30-fold greater than that in nontransgenic mice receiving the same diet. Despite these marked effects at the adipose cell level, glucose tolerance is not improved, probably due to insulin resistance in skeletal muscle and liver, where the transgene is not expressed. During the low fat diet, transgenic mice have 80% more body lipid than nontransgenics. High fat feeding increases body lipid 76% and adipocyte size 65% in nontransgenic mice, but has no effect in transgenic mice. Thus, overexpression of GLUT4 selectively in adipocytes protects against a further increase in adiposity. Furthermore, by using a heterologous promoter, high level overexpression of GLUT4 can be maintained even under metabolic conditions where it is normally down-regulated in adipocytes. This overexpression results in markedly increased glucose transport at the cellular level, but adipose-specific GLUT4 overexpression does not prevent the decrease in glucose tolerance associated with high fat feeding.

Utilization of the mouse large intestine to select an Escherichia coli F-18 DNA sequence that enhances colonizing ability and stimulates synthesis of type 1 fimbriae.

Escherichia coli F-18, a normal human fecal isolate, is an excellent colonizer of the streptomycin-treated mouse large intestine. E. coli F-18 Col-, a derivative of E. coli F-18 which no longer makes the E. coli F-18 colicin, colonizes the large intestine as well as E. coli F-18 when fed to mice alone but is eliminated when fed together with E. coli F-18. Random sequences of E. coli F-18 DNA were cloned into pRLB2, a par-B-stabilized derivative of pHC79. The entire gene library was transformed into E. coli F-18 Col- and fed to streptomycin-treated mice. The mouse large intestine selected a predominant clone which contained a recombinant plasmid (pRLB7) that enhanced E. coli F-18 Col- colonizing ability 100-fold but did not stimulate colicin synthesis. Moreover, pRLB7 simultaneously improved the survival of E. coli F-18 Col- in stationary phase in vitro, utilizing nutrients derived from mouse cecal mucus, and stimulated synthesis of both type 1 fimbriae and three E. coli F-18 Col- outer membrane proteins (74, 71, and 69 kDa). The 6.5-kb E. coli F-18 DNA sequence in pRLB7 does not contain either the fim operon or pilG (hns), both known to be involved in type 1 fimbrial synthesis. The sequence encodes six proteins, all smaller than the three E. coli F-18 Col- outer membrane proteins whose synthesis it stimulates. Collectively, the results suggest that the cloned E. coli F-18 DNA sequence contains one or more regulators of E. coli F-18 Col- operons expressed in the mouse large intestine in vivo and in isolated mouse cecal mucus in vitro.