Human Plasma Thioredoxin-80 Increases with Age and in apoE-/- Mice Induces Inflammation, Angiogenesis and Atherosclerosis
Background—Thioredoxin-1 (TRX1), a ubiquitous 12 kDa protein, exerts anti-oxidant and anti-inflammatory effects. In contrast, the truncated form, called TRX80, produced by macrophages induces up-regulation of pro-inflammatory cytokines. TRX80 also promotes the differentiation of mouse peritoneal and human macrophages toward a pro-inflammatory M1 phenotype.
Methods—TRX1 and TRX80 plasma levels were determined using specific ELISA. ADAM-17 and ADAM-10 activities were measured using respectively SensoLyte® 520 ADAM10 Activity Assay Kit *Fluorimetric* and InnoZyme™ TACE Activity Kit. Western immunoblots were performed using specific antibodies to ADAM-10 or ADAM-17. Angiogenesis study was evaluated in vitro using Human Microvascular Endothelial Cells-1 and in vivo using the matrigel plug angiogenesis assay in mice. The expression of macrophage phenotype markers were investigated using real-time polymerase chain reaction. Phosphorylation of Akt, mTOR and 70S6K was determined using specific antibodies. The effect of TRX80 on NLRP3 inflammasome activity was evaluated by measuring the level of IL-1β and IL-18 in the supernatants of activated macrophages using ELISA. Hearts were used for lesion surface evaluation and immunohistochemical studies and whole descending aorta were stained with oil-red-O. For transgenic mice generation, the human scavenger receptor (SR-A) promoter/enhancer was used to drive macrophage-specific expression of human TRX80 in mice.
Results—In this study, we observed a significant increase of plasma levels of TRX80 in aged subjects compared to healthy young subjects. In parallel, an increase in expression and activity of ADAM-10 and ADAM-17 in aged peripheral blood mononuclear cells compared to young subjects were observed. Furthermore, TRX80 was found to colocalize with TNF−α, a macrophage M1 marker, in human atherosclerotic plaque. In addition, TRX80 induced the expression of murine M1 macrophages markers through Akt-2/mTOR-C1/70S6K pathway and activated the inflammasome NLRP3, leading to IL-1β and IL-18 release, potent atherogenic cytokines. Moreover, TRX80 exerts a powerful angiogenic effect both in vitro and in vivo mouse studies. Finally, transgenic mice that overexpress human TRX80 specifically in macrophages of apoE-/- mice have a significant increase of aortic atherosclerotic lesions.
Conclusions—TRX80 showed an age-dependent increase in human plasma. In mouse models, TRX80 was associated with a pro-inflammatory status and increased atherosclerosis.
- Received January 27, 2017.
- Revision received April 6, 2017.
- Accepted April 26, 2017.