IL-4 confers resistance to IL-27–mediated suppression on CD4+ T cells by impairing signal transducer and activator of transcription 1 signaling

Abstract

Background Th2 cells play a critical role in the pathogenesis of allergic asthma. Established Th2 cells have been shown to resist reprogramming into Th1 cells. The inherent stability of Th2 cells poses a significant barrier to treating allergic diseases. Objective We sought to understand the mechanisms by which CD4+ T cells from asthmatic patients resist the IL-27-mediated inhibition. Methods We isolated and cultured CD4+ T cells from both healthy individuals and allergic asthmatic patients in order to test whether IL-27 can inhibit IL-4 production by the cultured CD4+ T cells using ELISA. Culturing conditions that resulted in resistance to IL-27 were determined using both murine and human CD4+ T cell culture systems. STAT1 phosphorylation was analyzed by Western blot and flow cytometry. Suppressor of cytokine signaling (Socs) mRNA expression was measured by quantitative PCR. The small interfering RNA method was used to knockdown the expression of Socs3 mRNA. Main Results We demonstrated that CD4+ T cells from asthmatic patients resisted the suppression of IL-4 production mediated by IL-27. We observed that repeated exposure to Th2-inducing conditions rendered healthy human CD4+ T cells resistant to IL-27-mediated inhibition. Using an in vitro murine culture system, we further demonstrated that repeated or higher doses of IL-4 stimulation, but not IL-2 stimulation, upregulated Socs3 mRNA expression and impaired IL-27-induced STAT1 phosphorylation. The Knockdown of Socs3 mRNA expression restored IL-27-induced STAT1 phosphorylation and IL-27-mediated inhibition of IL-4-production. Conclusions Our findings demonstrate that differentiated Th2 cells can resist IL-27-induced reprogramming toward Th1 cells by downregulating STAT1 phosphorylation and likely explain why the CD4+ T cells of asthmatic patients are resistant to IL-27-mediated inhibition.

Boswellic acid attenuates asthma phenotype by downregulation of GATA3 via nhibition of PSTAT6

“…In particular, GATA3 expression was positively correlated with pSTAT6, which indicated a certain regulatory relationship between pSTAT6 and GATA3. As we know, pSTAT6 can be regulated by many factors in the body and change in pSTAT6 correlates with many diseases (Batra et al, 2004;Thunberg et al, 2010;Chen et al, 2013;Yao et al, 2013;Irvin et al, 2014). Our present results prove that after boswellic acid treatment, GATA3 is downregulated following a decrease in pSTAT6, which indicates that boswellic acid may improve the asthma phenotype by inhibiting pSTAT6 and thus influencing GATA3 expression (Tachdjian et al, 2010).…”

Preventative tracheal administration of interleukin‐27 attenuates allergic asthma by improving the lung Th1 microenvironment

“…Previous in vitro studies have suggested that STAT1 and STAT3 are the main signaling pathways controlling the effects of IL‐27 on epithelial cells (Diegelmann, Olszak, Goke, Blumberg, & Brand, ). The STAT1 pathway is critical for IL‐27 signaling, which can upregulate ICAM‐1 and T‐bet expression in naive CD4+ T cells leading to Th1 differentiation and inhibition of Th2 differentiation (Z. Chen et al, , ; Kamiya et al, ; Owaki et al, ; Takeda et al, ). In addition, JAK/STAT independent, p38/MAPK signaling by IL‐27 has been reported, which ultimately leads to IFN‐γ secretion by activating T‐bet.…”

IL-27 attenuates airway inflammation in a mouse asthma model via the STAT1 and GADD45γ/p38 MAPK pathways

“…Of note, recent research has indicated that IL-27 can’t inhibit already differentiated Th17 cells [ 12 ], and our previous study indicated CD4 + T cells from asthmatic patients resisted IL-27-mediated suppression of IL-4 production [ 13 , 14 ].…”