Extracellular Human Thioredoxin-1 Inhibits Lipopolysaccharide-induced Interleukin-1β Expression in Human Monocyte-derived Macrophages

Abstract

Oxidative stress plays an important role in atherosclerotic vascular disease, and several recent studies were focused on thioredoxin-1 (Trx-1) and its potential protective role against oxidative stress. Since human monocyte-derived macrophages (HMDM) are important cells in several inflammatory diseases including atherosclerosis, we conducted this study to evaluate the impact of extracellular recombinant human Trx-1 (rhTrx-1) on gene expression in lipopolysaccharide-activated HMDM. Our results showed that rhTrx-1 was capable of reducing interleukin (IL)-1␤ mRNA and protein synthesis in a dose-dependent manner. This effect was partly mediated through a reduction of NF-B activation as analyzed by transient transfection and gel shift assays. In addition, we showed that the attenuation of NF-B activity was the result of the reduction of both p50 and p65 subunit mRNA and protein synthesis on one hand and of the induction of I-B␣ mRNA and protein expression on the other hand. Moreover, inhibition of endogenous Trx-1 mRNA was also observed, suggesting a contribution to the diminution of NF-B activity since endogenous Trx-1, in contrast to the exogenous Trx-1, activates the NF-B system. Finally, H 2 O 2 -oxidized rhTrx-1 reduced IL-1␤ mRNA synthesis in lipopolysaccharide-activated HMDM. This result highly suggested that the rhTrx-1 used in this study could be oxidized in the culture medium and, in turn, reduced IL-1␤ mRNA and protein synthesis. Taken together, these data indicated a potential new mechanism through which extracellular rhTrx-1 exerts an anti-inflammatory function in HMDM.Increasing evidence indicates that oxidative stress plays an important role in atherosclerotic vascular disease (1). However, the protective mechanisms of antioxidants, including dietary antioxidants such as ascorbate (vitamin C) and ␣-tocopherol (vitamin E), have not been well defined (1). Nevertheless, recent attention was focused on thioredoxin-1 (Trx-1) 2 and its potential protective role against oxidative stress (see review (2)). Indeed, Trx-1, a 12-kDa highly conserved protein in almost all species, is the major carrier of redox potential in cells (3). Trx-1 functions by the reversible oxidization of two Trx-specific redoxactive cysteine residues (Cys-32 and Cys-35) to form a disulfide bond that, in turn, can be reduced by the action of Trx-1 reductase and NADPH.Intracellular Trx-1 exerts most of its antioxidant properties through scavenging of reactive oxygen species (4). In addition, it acts as a cofactor for several enzymes such as nucleoside diphosphate reductase (5), T7 DNA polymerase (6), and 3Јphosphoadenosylsulfate reductase (7). Moreover, mammalian Trx-1 plays an important role in the regulation of redox-sensitive transcription factors such as activator protein-1 (AP-1) and nuclear factor-B (NF-B) (8, 9) and in the regulation of glucocorticoid receptor-mediated signal transduction (9 -11).In addition to its intracellular role, intact Trx-1 and its truncated form (Trx-80) can be released by cells and exert both cytokine-like ...

Thioredoxin-1 Attenuates Early Graft Loss after Intraportal Islet Transplantation in Mice

“…Corroborating our findings, Yoshioka et al and Billiet et al have reported that TRX could regulate the activation of NF-kB, followed by the suppression of IL-1b production [17,33]. It has been reported that pancreatic islets are highly sensitive to proinflammatory cytokines such as IL-1b [34][35][36].…”

Unfolding the relationship between secreted molecular chaperones and macrophage activation states

“…Addition of Trx to human macrophages, which have been stimulated by exposure to LPS, reduced both IL-1β messenger RNA (mRNA) levels and IL-1 protein synthesis in a dosedependent manner. This effect was largely mediated through a reduction of NF-κB activation (Billiet et al 2005). Administration of Trx to mice with myosin-induced autoimmune myocarditis (Liu et al 2004) or with experimental ulcerative colitis (Tamaki et al 2006) inhibits inflammation, strongly supporting the hypothesis that Trx is an alternative macrophage activator (Nakamura 2008).…”

“…This response is known to be suppressed in individuals infected with Mtb (Wilsher et al 1999). It has Table 3 Eukaryotic molecular chaperones that modulate macrophage activity Hsp10 (Johnson et al 2005) Inhibits LPS-induced caMØ activation Thioredoxin (Trx)80 (Pekkari et al 2005) Induce novel macrophage activation state Trx (Billiet et al 2005) Inhibits LPS-induced caMØ activation Cyclophilin A (Sherry et al 1992) Induces a caMØ state Peroxiredoxin (Donnelly et al 2005) Induces an aaMØ state Hsp27 (De et al 2000) Induces IL-10 synthesis but not TNF-α presumably an aaMØ state Hsp60 (Maguire et al 2002) a Induces caMØ state Hsp70 (Vabulas et al 2002) Induces caMØ state BiP (Panayi and Corrigall 2008) Inhibits monocyte activation and similar to Hsp27, presumably and aaMØ state Gp96 (Vabulas et al 2002a) Induces caMØ state Clusterin (Xie et al 2005) Induces what appears to be caMØ Haptoglobin (Moestrup and Møller 2004) Induces an aaMØ state caMØ classically activated macrophage, aaMØ alternatively activated macrophage a Mycobacterium tuberculosis Hsp60 induces alternative activation state recently been reported that Mtb Hsp60.1 inhibits the PPDinduced formation of the key cytokine IL-12 p40 subunit. IL-12 is responsible for activating Th1 responses.…”

Redox Regulation in the Extracellular Environment

“…89 Secreted Trx and truncated Trx80 have cytokine-and chemokine-like properties. 81,99 In cell culture systems, extracellular recombinant Trx1 has been shown to modulate inflammatory responses, 100 because the addition of recombinant Trx to lipopolysaccharide-activated human monocytederived macrophages decreased interleukin (IL)-1 mRNA expression and NF B activation. 100 Other roles of Trx in inflammation are induction of the cytokines IL-6 and IL-8.…”