Fig. 4

CRP upregulated HIF1α to interfered Leflunomide-AHR-CRP signaling in vitro. a Levels of CRP and HIF1α in hepatocytes from non-immunized (NI) rats, CRP^H and CRP^L CIA rats. n = 9 for each group. b Level of HIF1α in human normal hepatocytes (THLE-2 cells) transfected with vehicle, CRP siRNA and negative control siRNA (NC siRNA), respectively. c Level of ARNT binding with HIF1α in THLE-2 cells after the transfection. d Level of HIF1α in THLE-2 cells transfected with vehicle, empty vector and CRP overexpressing vector, respectively. THLE-2 cells incubated in hypoxia were used as a positive control. e Level of ARNT binding with HIF1α in THLE-2 cells after the transfection. f Level of ARNT binding with HIF1α or AHR in THLE-2 cells transfected with CRP siRNA in the presence of Leflunomide (LEF). g Level of ARNT binding with HIF1α or AHR in THLE-2 cells transfected with CRP overexpressing vector in the presence of Leflunomide (LEF). h Proposed mechanism underlying the dysfunction of Leflunomide-AHR-CRP signaling in CRP^H RA. Briefly, high level of CRP could trigger upregulation of HIF1α, which competes with AHR for ARNT association, leading to the dysfunction of Leflunomide-AHR-CRP signaling in CRP^H RA. i Level of ARNT binding with HIF1α in IL-6-pretreated THLE-2 cells transfected with HIF1α siRNA and NC siRNA, respectively. Pretreatment of IL-6 induced the overexpression of CRP in THLE-2 cells. j Level of ARNT binding with AHR in IL-6-pretreated THLE-2 cells transfected with HIF1α siRNA in the presence of Leflunomide (LEF). k Relative CRP mRNA (left) and CRP release (right) in IL-6-pretreated THLE-2 cells after the treatment. *P < 0.05 as determined by one-way ANOVA with a post hoc test. Each experiment was repeated three times. Source data are provided as a Source Data file