The thioredoxin (Trx) system comprises Trx, truncated Trx (Trx-80), Trx reductase, and NADPH, besides a natural Trx inhibitor, the thioredoxin-interacting protein (TXNIP). This system is essential for maintaining the balance of the cellular redox status, and it is involved in the regulation of redox signaling. It is also pivotal for growth promotion, neuroprotection, inflammatory modulation, antiapoptosis, immune function, and atherosclerosis. As an ubiquitous and multifunctional protein, Trx is expressed in all forms of life, executing its function through its antioxidative, protein-reducing, and signal-transducing activities. In this review, the biological properties of the Trx system are highlighted, and its implications in several human diseases are discussed, including cardiovascular diseases, heart failure, stroke, inflammation, metabolic syndrome, neurodegenerative diseases, arthritis, and cancer. The last chapter addresses the emerging therapeutic approaches targeting the Trx system in human diseases.

Objective-Oxidative stress is believed to play a key role in cardiovascular disorders. Thioredoxin (Trx) is an oxidative stress-limiting protein with anti-inflammatory and antiapoptotic properties. Here, we analyzed whether Trx-1 might exert atheroprotective effects by promoting macrophage differentiation into the M2 anti-inflammatory phenotype. Methods and Results-Trx-1 at 1 mg/mL induced downregulation of p16INK4a and significantly promoted the polarization of anti-inflammatory M2 macrophages in macrophages exposed to interleukin (IL)-4 at 15 ng/mL or IL-4/IL-13 (10 ng/mL each) in vitro, as evidenced by the expression of the CD206 and IL-10 markers. In addition, Trx-1 induced downregulation of nuclear translocation of activator protein-1 and Ref-1, and significantly reduced the lipopolysaccharide-induced differentiation of inflammatory M1 macrophages, as indicated by the decreased expression of the M1 cytokines, tumor necrosis factor- and monocyte chemoattractant protein-1. Consistently, Trx-1 administered to hyperlipoproteinemic ApoE2.Ki mice at 30 mg/30 g body weight challenged either with lipopolysaccharide at 30 mg/30 g body weight or with IL-4 at 500 ng/30 g body weight significantly induced the M2 phenotype while inhibiting differentiation of macrophages into the M1 phenotype in liver and thymus. ApoE2.Ki mice challenged once weekly with lipopolysaccharide for 5 weeks developed severe atherosclerotic lesions enriched with macrophages expressing predominantly M1 over M2 markers. In contrast, however, daily injections of Trx-1 shifted the phenotype pattern of lesional macrophages in these animals to predominantly M2 over M1, and the aortic lesion area was significantly reduced (from 100%18% to 62.8%9.8%; n58; P0.01). Consistently, Trx-1 colocalized with M2 but not with M1 macrophage markers in human atherosclerotic vessel specimens. Conclusion-The ability of Trx-1 to promote differentiation of macrophages into an alternative, anti-inflammatory phenotype may explain its protective effects in cardiovascular diseases. These data provide novel insight into the link between oxidative stress and cardiovascular diseases.

Background— This study was designed to evaluate the effect of arglabin on the NLRP3 inflammasome inhibition and atherosclerotic lesion in ApoE 2 Ki mice fed a high-fat Western-type diet. Methods and Results— Arglabin was purified, and its chemical identity was confirmed by mass spectrometry. It inhibited, in a concentration-dependent manner, interleukin (IL)-1β and IL-18, but not IL-6 and IL-12, production in lipopolysaccharide and cholesterol crystal–activated cultured mouse peritoneal macrophages, with a maximum effect at ≈50 nmol/L and EC 50 values for both cytokines of ≈ 10 nmol/L. Lipopolysaccharide and cholesterol crystals did not induce IL-1β and IL-18 production in Nlrp3 −/− macrophages. In addition, arglabin activated autophagy as evidenced by the increase in LC3-II protein. Intraperitoneal injection of arglabin (2.5 ng/g body weight twice daily for 13 weeks) into female ApoE 2 .Ki mice fed a high-fat diet resulted in a decreased IL-1β plasma level compared with vehicle-treated mice (5.2±1.0 versus 11.7±1.1 pg/mL). Surprisingly, arglabin also reduced plasma levels of total cholesterol and triglycerides to 41% and 42%, respectively. Moreover, arglabin oriented the proinflammatory M1 macrophages into the anti-inflammatory M2 phenotype in spleen and arterial lesions. Finally, arglabin treatment markedly reduced the median lesion areas in the sinus and whole aorta to 54% ( P =0.02) and 41% ( P =0.02), respectively. Conclusions— Arglabin reduces inflammation and plasma lipids, increases autophagy, and orients tissue macrophages into an anti-inflammatory phenotype in ApoE 2 .Ki mice fed a high-fat diet. Consequently, a marked reduction in atherosclerotic lesions was observed. Thus, arglabin may represent a promising new drug to treat inflammation and atherosclerosis.

This article is protected by copyright. All rights reserved. AbstractScope: Formula-derived Dietary Advanced Glycation End products (AGEs) may promote programming of inflammation and oxidative stress in the kidney of intrauterine growth retarded (IUGR) piglets. Methods and results:IUGR piglets received either a Low Temperature Heated Formula (LHF: n=8) or a High Temperature Heated Formula (HHF: n=8) or suckled naturally for 3 weeks postnatally. Then they were fed with normal ad libutum regular diet. Nɛ carboxymethyllysine (CML) was measured in plasma, feces and formula by HPLC/MS-MS.CML was detected by immunofluoresence in kidney cells. Target renin-angiotensin, apoptotic, proinflammatory genes, p62 NF-κB and sRAGE levels were quantified. Compared with that in controls, free CML and plasma urea increased significantly in the HHF fed group at PND36 (P<0.05). CML was detected in nuclei of renal tubular cells of fed formula piglets but not in suckled ones. This presence of CML was associated with the activation of the soluble sRAGE. AT1, AT2, caspase 3, caspase 8, NF-κB, p62 NF-κB and total protein oxidation in kidney were higher in HHF fed group as compared to LHF fed group (P<0.05). Conclusion:Food processes aimed at reducing the concentration of AGEs in infant formula are urgently needed and may be therapeutically relevant for premature and/or IUGR babies.

TRX80 showed an age-dependent increase in human plasma. In mouse models, TRX80 was associated with a proinflammatory status and increased atherosclerosis.

Macrophages play a pivotal role in the pathophysiology of atherosclerosis. These cells express cathepsin L (CatL), a cysteine protease that has been implicated in atherogenesis and the associated arterial remodeling. In addition, macrophages highly express peroxisome proliferator-activated receptor (PPAR) ␥, a transcription factor that regulates numerous genes important for lipid and lipoprotein metabolism, for glucose homeostasis, and inflammation. Hence, PPAR␥ might affect macrophage function in the context of chronic inflammation such as atherogenesis. In the present study, we examined the effect of PPAR␥ activation on the expression of CatL in human monocyte-derived macrophages (HMDM). Activation of PPAR␥ by the specific agonist GW929 concentration-dependently increased the levels of CatL mRNA and protein in HMDM. By promoter analysis, we identified a functional PPAR response element-like sequence that positively regulates CatL expression. In addition, we found that PPAR␥-induced CatL promotes the degradation of Bcl2 without affecting Bax protein levels. Consistently, degradation of Bcl2 could be prevented by a specific CatL inhibitor, confirming the causative role of CatL. PPAR␥-induced CatL was found to decrease autophagy through reduction of beclin 1 and LC3 protein levels. The reduction of these proteins involved in autophagic cell death was antagonized either by the CatL inhibitor or by CatL knockdown. In conclusion, our data show that PPAR␥ can specifically induce CatL, a proatherogenic protease, in HMDM. In turn, CatL inhibits autophagy and induces apoptosis. Thus, the proatherogenic effect of CatL could be neutralized by apoptosis, a beneficial phenomenon, at least in the early stages of atherosclerosis.

In response to the letter of Drs Takahashi and Karasawa, we thought it might be of interest to open the debate about the mechanism by which arglabin, a natural compound isolated from Artemisia glabella, inhibits cholesterol crystal-induced activation of the NLRP3 inflammasome in murine macrophages. In the March 2015 online issue of Circulation 1 we evaluated the impact of arglabin on cholesterol crystal-mediated NLRP3 activation in cultured murine macrophages and in ApoE2.Ki mice fed a high-fat diet.We showed that both Nlrp3 knockout and inhibition of NLRP3 activation by the compound arglabin significantly decreased the size of atherosclerotic lesions in ApoE 2 .Ki mice fed a high-fat diet. At the molecular level, arglabin inhibited the activity of the NLRP3 inflammasome and significantly reduced the subsequent production of interleukin 1β (IL-1β) and interleukin 18 in vitro and of IL-1β in vivo. In addition, we found that arglabin induces LC3-II formation, but does not inhibit the final step of autophagy, the fusion of autophagosomes with lysosomes and the generation of autolysosomes. Moreover, arglabin reduced total plasma cholesterol and triglyceride levels along with the reduction of all lipoprotein subfractions leaving unaffected hepatic low-density lipoprotein receptor expression. It also reduced the plasma levels of antibodies against oxidized low-density lipoprotein and the number of proinflammatory M1 macrophages, as well, in arterial lesions in ApoE 2 .Ki mice fed a high-fat diet. Besides, arglabin increased the polarization of macrophages into the anti-inflammatory M2 phenotype in this mouse model.Because our study has shown that arglabin, on the one hand, reduced the level of pro-IL-1β and the Nlrp3 protein (Figure 2 1 ) and, on the other hand, induced autophagy in macrophages ( Figure 3 1 ), we hypothesized that the protein decrease could be attributed to enhanced protein degradation by autophagy. Indeed, such a hypothesis is supported by the findings of Razani et al, 2 referred to by Karasawa and Takahashi, and others.3,4 Razani et al 2 have shown that autophagy, particularly in macrophages, degrades both Nlrp3 and pro-IL-1β and removes damaged mitochondria, thereby preventing the release of mitochondrial oxygen species and DNA known to activate inflammasomes, 4 which is in line with an antiatherogenic role of autophagy. Because we have observed profound degradation of Nlrp3 and pro-IL-1β proteins in cells treated with arglabin (Figure 2 1 ), we favor the view that arglabin, by increasing autophagy, promotes primarily the degradation of Nlrp3 and pro-IL-1β proteins and, to a lesser extent, the inhibition of the NRLP3 activation by increased mitophagy.Decreased levels of Nlrp3 protein are also expected not only to decrease atherogenesis, as we have shown in ApoE 2 .Ki mice fed a high-fat diet, but also any other sterile inflammation including hepatic ischemia-reperfusion injury, which is seemingly independent of the inflammasome formation yet dependent on the Nlrp3 protein, 5 as it was discussed by...

Vascular cells are particularly susceptible to oxidative stress that is believed to play a key role in the pathogenesis of cardiovascular disorders. Thioredoxin-1 (Trx-1) is an oxidative stress-limiting protein with anti-inflammatory and anti-apoptotic properties. In contrast, its truncated form (Trx-80) exerts pro-inflammatory effects. Here we analyzed whether Trx-80 might exert atherogenic effects by promoting macrophage differentiation into the M1 pro-inflammatory phenotype. Trx-80 at 1 µg/ml significantly attenuated the polarization of anti-inflammatory M2 macrophages induced by exposure to either IL-4 at 15 ng/ml or IL-4/IL-13 (10 ng/ml each) in vitro, as evidenced by the expression of the characteristic markers, CD206 and IL-10. By contrast, in LPS-challenged macrophages, Trx-80 significantly potentiated the differentiation into inflammatory M1 macrophages as indicated by the expression of the M1 cytokines, TNF-α and MCP-1. When Trx-80 was administered to hyperlipoproteinemic ApoE2.Ki mice at 30 µg/g body weight (b.w.) challenged either with LPS at 30 µg/30 g (b.w.) or IL-4 at 500 ng/30 g (b.w.), it significantly induced the M1 phenotype but inhibited differentiation of M2 macrophages in thymus and liver. When ApoE2.Ki mice were challenged once weekly with LPS for 5 weeks, they showed severe atherosclerotic lesions enriched with macrophages expressing predominantly M1 over M2 markers. Such effect was potentiated when mice received daily, in addition to LPS, the Trx-80. Moreover, the Trx-80 treatment led to a significantly increased aortic lesion area. The ability of Trx-80 to promote differentiation of macrophages into the classical proinflammatory phenotype may explain its atherogenic effects in cardiovascular diseases.