IL-27 subunits and its receptor (WSX-1) mRNAs are markedly up-regulated in inflammatory cells in the CNS during experimental autoimmune encephalomyelitis

https://doi.org/10.1016/j.jns.2004.12.013Get rights and content

Abstract

IL-27 (EBI3p28) is a recently discovered heterodimeric cytokine, which is functionally related to IL-23p40p19 and IL-12p40p35. IL-27 acts in synergy with IL-12 early during Th1 development from naïve T cells. IL-27 functions through the WSX-1 and the gpl30 receptor subunits, which shares homology with the IL-12Rβ2 subunit. We have previously reported that IL-23 is up-regulated in CD11b+ microglia/macrophages in the CNS during the early phase of experimental autoimmune encephalomyelitis (EAE), and thus may contribute to the early induction of EAE. In the present study, we examined the expression of IL-27 and its receptor in the CNS, spleen, and lymph nodes at different stages of EAE actively induced with myelin oligodendrocyte glycoprotein peptide35–55. Our findings show that IL-27 EBI3 and p28 mRNA were up-regulated to a maximum level at the peak of disease in APC from the CNS and lymph nodes, but not in the spleen. Moreover, IL-27 receptor (WSX-1) expression was greatly up-regulated during the early stage of EAE in both the CNS and lymph nodes. Taken together, our data show that subunits of IL-27 and its receptor (WSX-1) mRNAs are markedly up-regulated in inflammatory cells in the CNS at the peak of disease. Thus, IL-27 produced by infiltrating cells in the CNS may regulate in a paracrine manner the Th1 response in EAE.

Introduction

Recently, a novel IL-12 family, composed of IL-12, IL-23, and IL-27 heterodimeric cytokines, has been established [1], [2]. These cytokines, mainly secreted by activated APC, act on CD4+ T cells at different stages to regulate Th1 development. IL-12, formed by p35 and p40 subunits, is the prototypic Th1-inducing and Th1-maintaining molecule [3], [4]. IL-23, formed by the same p40 subunit as in IL-12 but with a unique p19 subunit, is able to activate Th1 memory cells [5], [6]. IL-27, the latest discovered IL-12 family member, is a heterodimeric cytokine composed of EBI3 (an IL-12p40-related protein) and p28 (an IL-12p35-related protein). IL-27 is an early product of activated APC and drives rapid clonal expansion of naive but not memory CD4+ T cells. IL-27 strongly synergizes with IL-12 to trigger IFN-γ production of naive CD4+ T cells [1], [7].

IL-12 and IL-23 function through distinct heterodimeric receptors that share the IL-12Rβ1 subunit [8]. IL-27 mediates its biologic effects through WSX-1 receptor [9], [10], together with a recently described subunit gp130 [11]. Neither of the two subunits itself is sufficient to mediate IL-27-induced signal transduction, but the combination of both is required for this event. WSX-1/TCCR expression is predominantly lymphoid-specific, with the highest levels of expression found in NK cells and resting CD4+ T cells [12]. However, recent studies of expression analysis of WSX-1 and gp130 by quantitative PCR suggest that IL-27 might have a variety of cellular targets besides naive CD4+ T cells. Thus, IL-27 not only contributes to the development of an adaptive immune response through its action on CD4+ T cells, it also directly acts on cells of the innate immune system.

WSX-1-deficient mice have shown greatly diminished in vitro CD4+ T cell IFN-γ production. The IFN-γ production defects in T cells of WSX-1 deficient mice though were limited to the primary response. During secondary responses, the cells recovered the ability to produce IFN-γ [13]. WSX-1-deficient mice have demonstrated markedly increased susceptibility to infection from the intracellular pathogens Leishmania major [13], Toxoplasma gondii [14], and Trypanosoma cruzi [15]. Data from one these studies [14] have indicated that signaling through this receptor is involved in limiting the intensity and the duration of T cell activity during infection. Importantly, a recent study has indicated that the presence of IL-4 regulates the requirement for WSX-1 in Th1 cell development after infection with Leishmania [16]. Taken together, studies using WSX-1-deficient mice suggest that functional IL-27R may play an important role in early Th1 differentiation processes prior to IL-12R complex expression [12].

A critical stage of the Th1 differentiation process of naïve CD4+ T cells occurs with a complex network of intracellular signaling events including expression of T-bet (T-box expressed in T cells), remodeling of the IFN-γ gene, and expression of IL-12Rβ2 [12]. T-bet expression appears to be controlled by both the TCR and the IFN-γR/Stat1 signal transduction pathways [17], [18], and not by the IL-12/Stat4 pathway [17], [18], [19]. Interestingly, IL-27 stimulation in developing murine Th cells and primary NK cells induces the expression of T-bet. Induction of T-bet results in up-regulation of IL-12Rβ2 in naïve T cells [20], [21], [22]. IL-27 induces Stat1 and Stat3 phosphorylation and activation in primary human T cells. Thus, IL-27 may play an important role in the early steps of Th1 commitment by contributing in a paracrine manner to the control of IL-12 responsiveness [20], [21], [22].

We and others have previously shown that IL-23, not IL-12, is the critical cytokine for induction of experimental autoimmune encephalomyelitis (EAE), a Th1 cell-mediated autoimmune inflammatory disease of the CNS. Additionally, it has been reported that IL-23 produced by CNS APC (CD11b+ microglia/macrophages) during the early phase of EAE may contribute to the pathogenesis of the disease [23], [24]. The role of IL-27 and its receptor WSX-1 in Th1 response induction has been studied in murine infection models [7], [9]. However, changes in expression of IL-27 and its receptor in the CNS during autoimmune diseases have not been elucidated.

The goal of the present study was to analyze the expression of IL-27 and its receptor in CNS APC at different stages of EAE actively induced with MOG35–55 peptide, and to compare it with expressions by spleen and lymph node macrophages. Our findings indicate that IL-27 EBI3 and p28 mRNA were co-expressed in parallel at maximum levels at the peak of disease in APC from the CNS and lymph nodes. Moreover, an early peak of IL-27 receptor (WSX-1) mRNA expression was observed in infiltrating CD4+ T cells in the CNS. Out data suggest that IL-27 produced by infiltrating cells in the CNS may regulate in a paracrine manner the Th1 response in EAE.

Section snippets

Mice and EAE induction

Eight-to 10-week-old C57BL/6 mice were purchased from The Jackson Laboratory (Bar Harbor, ME). To induce EAE, mice were each injected subcutaneously with 300 μg of myelin oligodendrocyte glycoprotein (MOG) peptide 35–55 (MOG35–55) in CFA containing 4 mg/ml Mycobacterium tuberculosis H37Ra (Difco, Detroit, MI) over two sites at the back. Pertussis toxin (200 ng) was given i.p. on days 0 and 2 postimmunization (p.i.) as previously described [24]. EAE was scored according to a 0–5 scale [25] as

Clinical course of EAE

MOG35-55-immunized C57BL/6 mice exhibited limp tail as first clinical sign of disease. More than 80% of animals developed a progressive paralysis, which peaked at days 3–5 after onset, and then exhibited a chronic disease with a partial clinical recovery (Fig. 1).

Kinetics of expression of mRNA for IL-27 subunits and its receptor in CD11b+ microglia and/or macrophages

To study the expression of IL-27 and its receptor in vivo during the course of EAE, we measured the kinetics of expression of mRNA for IL-27 subunits EBI3 and p28 and its receptor WSX-1 in CD11b+ microglia and/or macrophages. As shown

Discussion

The goal of this study was to analyze the expression of IL-27 subunits and its receptor in CNS microglia/macrophages during EAE actively induced by immunodominant peptide MOG35–55 in C57BL/6 mice. This is of interest because of the important role of IL-12 family, IL-12, IL-23, and IL-27 in Th1-induced autoimmune pathology [3], [23], [28]. We have previously described the differential expression and regulation of IL-23 and IL-12 in adult mouse microglia, and we suggested that IL-23 produced by

References (36)

  • D.S. Robinson et al.

    Further checkpoints in Th1 development

    Immunity

    (2002)
  • O. Devergne et al.

    Expression of Epstein–Barr virus-induced gene 3, an interleukin-12 p40-related molecule, throughout human pregnancy: involvement of syncytiotrophoblasts and extravillous trophoblasts

    Am J Pathol

    (2001)
  • D.S. Robinson et al.

    Asthma: T-bet—a master controller?

    Curr Biol

    (2002)
  • B. Gran et al.

    Early administration of IL-12 suppresses EAE through induction of interferon

    J Neuroimmunol

    (2004)
  • A. Giulietti et al.

    An overview of real-time quantitative PCR: applications to quantify cytokine gene expression

    Methods

    (2001)
  • G. Trinchieri

    Interleukin-12 and the regulation of innate resistance and adaptive immunity

    Nat Rev Immunol

    (2003)
  • M.L. Belladonna et al.

    IL-23 and IL-12 have overlapping, but distinct, effects on murine dendritic cells

    J Immunol

    (2002)
  • C. Parham et al.

    A receptor for the heterodimeric cytokine IL-23 is composed of IL-12Rbeta1 and a novel cytokine receptor subunit, IL-23R

    J Immunol

    (2002)
  • Cited by (69)

    View all citing articles on Scopus
    View full text