Heme oxygenase‐1 directly binds STAT3 to control the generation of pathogenic Th17 cells during neutrophilic airway inflammation

• DOI: 10.1111/all.13216
• Publication Date: 2017-06-05T05:42:45Z
• Authors: X. L. Lin; J. J. Lv; J. Lv; C. X. Di; Y. J. Zhang; T. Zhou; J. L. Liu; Z. W. Xia
• Keywords: Inflammation; 0301 basic medicine; Interleukin-6; Neutrophils; Respiratory Tract Diseases; Immunity; Gene Expression; Nuclear Receptor Subfamily 1, Group F, Member 3; Cell Line; 3. Good health; Disease Models, Animal; Mice; 03 medical and health sciences; Neutrophil Infiltration; Animals; Humans; Female; Phosphorylation; RNA, Small Interfering; Heme Oxygenase-1; Janus Kinases; Plasmids; Protein Binding

AbstractBackgroundSpecific JAK/STAT pathways play a critical role in the functional differentiation of distinct Th subsets. Previously, we showed that HO‐1, a stress‐inducible protein, inhibits Th17 cell differentiation and alleviates neutrophilic airway inflammation, but the responsible molecular basis remains unclear.MethodsWe employed Th17‐skewing differentiation and NEA mouse models to study the role of HO‐1 in regulating IL‐6‐STAT3‐RORγt/SOCS3 signaling pathway to control Th17 cell‐mediated neutrophilic airway inflammation. The levels of cytokines and expressions of relative signaling molecules were measured by ELISA, western blot, and qPCR, respectively. Frequency of CD4+IL‐17A+, CD4+IL‐6R+, and CD4+IL‐23R+ cells was analyzed by FCM. The interaction between HO‐1 and signaling pathway‐related proteins was determined by co‐immunoprecipitation and western blot.ResultsHere, we show that hemin‐induced HO‐1 overexpression is required to mediate this process. Specifically, HO‐1 decreased STAT3 phosphorylation but not IL‐6R/IL‐23R expression or JAK1/JAK2 activation in CD4+ T cells. The effect was accompanied by co‐inhibition of SOCS3, a negative feedback factor of STAT3 activation. HO‐1 bound to three domains on STAT3 (DNA‐binding, linker, and transactivation domains) to directly regulate STAT3 activation. Conversely, either forced expression of a constitutively active STAT3 mutant or application of small‐interfering RNA (siRNA) for HO‐1 reversed these effects.ConclusionsOur data suggest that HO‐1 exerts its inhibitory effect on Th17 cell differentiation by directly associating and blocking STAT3 phosphorylation. We speculate that hemin may be a potential therapeutic candidate for the treatment of other types of immune and pulmonary inflammatory‐related diseases.