Tumor necrosis factor α acceleration of inflammatory responses by down‐regulating heme oxygenase 1 in human peripheral monocytes

Abstract

Objective. To examine the interaction between heme oxygenase 1 (HO-1), a stress-induced antiinflammatory protein, and tumor necrosis factor ␣ (TNF␣) in human peripheral blood monocytes. Heme oxygenase (HO) is an enzyme that converts heme into carbon monoxide, Fe 2ϩ , and biliverdin (1,2). HO-1, an inducible isozyme of HO, is a 32-kd heat-shock protein that is expressed in response to a variety of noxious stimuli, including heavy metals, hyperoxia, hypoxia, endotoxins, and hydrogen peroxide (1,2). Evidence suggests that increased expression of HO-1 is beneficial in a variety of pathologic conditions (1,2). For example, HO-1 gene therapy has been successfully used to treat various lung diseases in animals (3-7), and chemical induction of HO-1 expression has been shown to improve lupus nephritis in MRL/lpr mice (8). In contrast, a deficiency of HO-1 expression is associated with severe chronic inflammation, as shown in studies of HO-1-knockout mice (9) and in a patient with HO-1 deficiency (10). These findings are consistent with a physiologic role of HO-1 in protection against inflammation. Methods. Peripheral blood mononuclear cells (PBMCs

Expression of heme oxygenase‐1 in human leukemic cells and its regulation by transcriptional repressor Bach1

“…We further studied the transcription activity for HO-1 expression in PMA-treated U937 cells that had been transfected with a luciferase-expressing plasmid encoding the MARE EN1 region (pHO-1(-4.5k)) or with a plasmid lacking the MARE site (pHO-1(-4.0k)). (21) LPS attenuated luciferase activity in cells transfected with pHO-1 (-4.5k) but not in cells transfected with pHO-1(-4.0k), suggesting that the effect of LPS depended on the MARE (Fig. 4C).…”

“…Protein expression levels were determined by SDS-PAGE and subsequent immunoblotting as previously described. (21) For several experiments, cytoplasmic and nuclear extracts were prepared from cells with NE-PER Nuclear and Cytoplasmic Extraction Reagents (Pierce Biotechnology, Rockford, IL, USA).…”

Carbon monoxide donors or heme oxygenase-1 (HO-1) overexpression blocks interleukin-18-mediated NF-κB–PTEN-dependent human cardiac endothelial cell death

“…TNF-α, a proinflammatory and pro-apoptotic cytokine, has been shown to modulate HO-1 expression. In a recent study, Kirino et al have demonstrated that TNF-α suppresses HO-1 expression in human peripheral monocytes via increased mRNA degradation [27]. Since reduced HO-1 expression is associated with increased cell death, we investigated whether IL-18 modulates HO-1 expression in EC.…”

“…A 4.5 kb of the 5'-flanking region of human HO-1 was amplified from human genomic DNA using the sense primer 5′-ggt acc TTG GGC TTG TCT TCC TTG CT-3′ and the antisense primer 5′-ctc gag CATCCGGCCGGTGCTGGGCTCGT-3′ and cloned into the pCR2.1-TOPO vector, digested with Kpn I and Xho I, and subcloned into the pGL3-Basic reporter vector (pHO-1-Luc) as previously described [27]. EC were transiently transfected with pHO-1-Luc (2 µg), and 24 h later, treated with IL-18 for 12 hours.…”

Auranofin Downregulates Nuclear Factor-κB Activation via Nrf2-Independent Mechanism

“…The thiol-reactive auranofin modifies Cys-179 in beta subunit of inhibitory κB kinase (IKK), which results in the blockade of inhibitory κB-α (IκB-α) phosphorylation and degradation [6,7]. Consequently, auranofin attenuates the transcriptional activity of NF-κB and downregulates the expression of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β).Heme oxygenase-1 (HO-1), which suppresses an inflammatory response, is also associated with the pharmacological property of auranofin in rheumatoid arthritis [14,16]. In the previous study, we found that auranofin induced HO-1 via the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in human synovial cells and THP-1 monocytic cells.…”