IL-27 structural analysis demonstrates similarities with ciliary neurotrophic factor (CNTF) and leads to the identification of antagonistic variants

Abstract

IL-27, consisting of the subunits IL-27p28 and Epstein–Barr virus-induced gene 3 (EBI3), is a heterodimeric cytokine belonging to the IL-6/IL-12 family of cytokines. IL-27p28 is a four-helical cytokine requiring association with the soluble receptor EBI3 to be efficiently secreted and functionally active. Computational and biological analyses of the IL-27 binding site 1 to its receptor revealed important structural proximities with the ciliary neurotrophic factor group of cytokines and highlighted the contribution of p28 Trp 97 , as well as of EBI3 Phe 97 , Asp 210 , and Glu 159 , as key residues in the interactions between both cytokine subunits. WSX-1 (IL-27R) and gp130 compose the IL-27 receptor-signaling complex, recruiting the STAT-1 and STAT-3 pathways. A study of IL-27 binding site 3 showed that Trp 197 was crucial for the cytokine's interaction with gp130, but that the mutated cytokine still recognized IL-27R on the cell surface. IL-27 exerts both pro- and anti-inflammatory functions, promoting proliferation and differentiation of Th1 and inhibiting Th17 differentiation. Our results led us to develop mutated forms of human and mouse IL-27 with antagonistic activities. Using an in vivo mouse model of concanavalin A-induced Th1-cell–mediated hepatitis, we showed that the murine IL-27 antagonist W195A decreased liver inflammation by downregulating the synthesis of CXCR3 ligands and several acute phase proteins. Together, these data suggest that IL-27 antagonism could be of interest in down-modulating acute IL-27–driven Th1-cell–mediated immune response.

Interleukin-27 and IFNγ regulate the expression of CXCL9, CXCL10, and CXCL11 in hepatitis

“…IL-27 dimeric receptor is expressed by CD4 + T lymphocytes, NK cells, and hepatocytes [5,7,8,25]. IL-27 was previously reported to be associated in liver disease including hepatocellular carcinoma [43], hepatitis B virus (HBV) infection [24,26,44], in disseminated neuroblastoma metastasis in the liver [45,46], in Leishmania donovani infection [16] and in T cellmediated hepatitis [22,23,47,48]. The present study aimed to investigate the role of IL-27 during liver inflammation and its effects on orchestration of CXCR3 ligands (CXCL9, CXCL10, and CXCL11 chemokines) in hepatic cells both in vitro and in vivo studies.…”

“…In liver pathology, IL-27 was shown to play a pathogenic role during T cell-mediated hepatitis in mice [22] with an increase in IFNγ level as we described previously [23]. The dendritic cell-derived IL-27p28 has been shown to regulate IFNγ production by CD4 + T cells, and IL-27p28 deficiency in mice led to more severe liver injury [24].…”

“…The increased level of IL-27 was associated with HBV infection in human patients and in vitro studies [26], and IL-27 directly activated the anti-viral/tumor NK and NKT cells [27]. We previously demonstrated the involvement of IL-27 in T cell-mediated hepatitis induced by concanavalin A (ConA) [23] in which liver injury is mediated by NK and T/NKT cells with over-expression of different inflammatory cytokines and chemokines [28][29][30][31].…”

Distinct subunit pairing criteria within the heterodimeric IL-12 cytokine family

“…It is not known if this is a feature common to all IL-12 family members, or unique to the p40 subunit. There is no crystal structure of IL-27, however, a recent mutagenesis study on human IL-27 identified a conserved tryptophan residue in the p28 subunit, as well as two acidic Ebi3 residues that are involved in the IL-27 dimer interface (Rousseau et al, 2010). …”

Impact of p38 mitogen-activated protein kinase inhibition on immunostimulatory properties of human 6-sulfo LacNAc dendritic cells

“…On the other hand, the effect of IR did not extend to the other IL-12 family member, IL-27. IL-27 comprises the IL-27p28 subunit and Epstein-Barr virus-induced gene 3 (EBI3) which are related to p35 and p40 respectively [51]. Those findings demonstrate the highly selective effect of IR on DC functions with prevalence to inhibit Th17 responses.…”