A novel IL‐23p19/Ebi3 (IL‐39) cytokine mediates inflammation in Lupus‐like mice

Abstract

Interleukin-12 family cytokines have emerged as critical regulators of immunity with some members (IL-12, IL-23) associated with disease pathogenesis while others (IL-27sue injury by promoting the expansion of regulatory B and T-cell subsets [2,3].Discovery of IL-23 in 2000 [4] led to the reevaluation of IL-12 and IL-23 in autoimmune diseases. For example, therapeutic targeting of IL-12p40 decreases pathology in many mouse models of autoimmune diseases [5], while disease is exacerbated in IL-12p35-deficient mice [6,7]. Thus, IL-23 rather than IL-12 was * These authors contributed equally to this work as first authors.* * These authors contributed equally to this work as senior authors. Eur. J. Immunol. 2016. 46: 1343-1350 found to be the critical cytokine for autoimmune inflammation including experimental immune-mediated disease [6][7][8][9][10]. Currently, at least ten therapeutic agents targeting IL-23 are being tested in the clinic for more than 17 human immune-mediated diseases [11]. Both IL-27 and IL-35 have immune-suppressive activities and are also cytokines with strikingly diverse influences on the immune response so that viable therapeutic targets may also be exploited for treatment of human inflammatory diseases [12,13]. Thus, understanding immunobiology of IL-12 family cytokines would undoubtedly provide valuable knowledge that can be exploited therapeutically. The IL-12 family cytokines are α/β heterodimers consisting of one α subunit (IL-23p19, IL-27p28, IL-12p35) and one β chain (IL-12p40, Ebi3) [14,15]. Although there are currently four known members in the family, the predictable range of combinations is six and it is conceivable that additional pairings such as IL-23p19/Ebi3 are possible [12,[14][15][16][17]. In this study, we sought to discover additional IL-12 members that might exist in nature. By combining different alpha and beta IL-12 subunit proteins in vitro we detected a novel stable p19/Ebi3 heterodimeric complex by immunoprecipitation. We have characterized the p19/Ebi3 cytokine (IL-39) and demonstrated that it possesses biological activities in vitro and in vivo. Results IL-23p19 (p19) and Ebi3 form a composite factor (IL-39)To examine whether p19 can form a stable complex with Ebi3, we mixed equal amounts of the two proteins and immunoprecipitation (IP)/Western blot analyses revealed formation of a stable human p19/Ebi3 complex (Fig. 1A). We could not detect the p19/Ebi3 following IP with isotype IgG or anti-c-Jun antibody, providing suggestive evidence for potential bona fide p19/Ebi3 cytokine. To confirm our finding in another animal species, we genetically engineered and expressed mouse p19 and Ebi3 subunits in CHO cells (Fig. 1B). IP of supernatants derived from transfectants with anti-p19 mAb and followed by Western blot analysis using anti-Ebi3 mAb confirmed coexpression p19 and Ebi3 and formation of a stable p19/Ebi3 heterodimer (Fig. 1C). We further confirmed this observation by reciprocal IP with anti-Ebi3 mAb and Western blotting with anti-p19 mAb and the p19/Ebi3 comple...

Cytokines in the pathogenesis of rheumatoid arthritis: new players and therapeutic targets

“…The signal is transduced via cytoplasmic myeloid differentiation primary response protein 88 (MyD88) and IL-1R associated kinase 4 (IRAK4), ending up in the activation of transcriptions factors like NF-kB or MAPK [7]. IL-33 (IL-1F11) was identified in high ↑ vs HD, OA and PsA [70][71][72][73] ↑ in RA-ILD [71] ↑ in erosive RA [71] Lower baseline levels predict good response to anti-TNF-α agents [74,75] Detectable levels at baseline predict response to RTX [77] Detectable levels at baseline predict atherosclerotic plaque progression [76] na ↑ vs OA [26] = vs OA [72] Lower baseline levels predict good response to anti-TNF-α agents [74,75] IL-36 IL-36 is upregulated in CIA, CAIA and AIA [122,123] IL-36 blockade does not affect arthritis [122,123] ↑ vs HD [133] n a ↑ vs OA [126] IL-37 Systemic and intra-articular administration of recombinant IL-37 inhibits the development of synovitis in CIA and AIA [146,147] ↑ vs HD [133] ↑ vs HD and OA [147][148][149][150] ↑ in FR + and anti-CCP + patients vs seronegative [150] ↑ in active vs inactive RA [149] ↑ in erosive RA [150] ↑ [150] ↑ [147] IL-38 IL-38 KO mice display more severe AIA [131] IL-38 overexpression attenuates CIA and STIA [132] = vs HD and OA [131] ↑ vs HD [133] na ↑ vs OA [131] Other IL-32 IL-32 administration worsens CIA …”

“…For the sake of completeness, it should be mentioned that very recently another family member, IL-39, has been described. IL-39 is composed of IL-23p19 and EBI3 heterodimer, is secreted by activated B lymphocytes and seems to play a pathogenic role in mouse models of systemic lupus erythematosus [70,71], but no data on RA or other diseases are available so far. These cytokines transduce the signal through unique pairings of 5 receptor chains: IL-12Rβ1, IL-12Rβ2, IL-23R, IL-27Rα (or WSX-1) and gp130.…”

The toll-like receptor 3 pathway in homeostasis, responses to injury and wound repair

“…This suggests that IL-23p19 and EBI3 may function as a novel IL-12 family cytokine. Indeed, these two subunits were very recently reported to form IL-39, which was shown to promote neutrophil expansion in lupus-prone mice [64,65]. Therefore, IL-39 may play a role downstream of TLR3 in wound healing responses in the skin by promoting neutrophil-mediated responses at the site of injury.…”

Innate Immunity in Coronary Disease. The Role of Interleukin-12 Cytokine Family in Atherosclerosis

“…It signals through four receptor complexes: IL-12Rβ2/gp130, IL-12Rβ2/IL12Rβ2, gp130/gp130, and IL-12Rβ2/ WSX-1 15,16 . Recently discovered IL-39 consists of p19 and EBI3 chains and signals through IL-23R/gp130 17 . The heterodimer p28/p40, tentatively called IL-Y, has been demonstrated to antagonize the signaling by IL-12 and IL-27 18 .…”

“…IL-35 is mainly produced by FoxP3+ regulatory T (Treg) cells, but can also be produced by gdT cells, CD8+ T-cells, and placental trophoblast 24 . In addition, it has been demonstrated that activated B cells secrete IL-39 17 .…”