Expression of High Mobility Group Box Chromosomal Protein 1 and Its Modulating Effects on Downstream Cytokines in Systemic Lupus Erythematosus
ABSTRACT To compare the expression of high mobility group box chromosomal protein 1 (HMGB1) and the modulating effects on its downstream cytokines in patients with systemic lupus erythematosus (SLE) and healthy controls.
HMGB1 concentrations in serum from SLE patients and controls were measured by immunoblot analysis. HMGB1 messenger RNA (mRNA) expression in peripheral blood mononuclear cells (PBMC) was detected by real-time reverse transcription-polymerase chain reaction. Immunofluorescence assay was employed to examine the translocation of HMGB1 in monocytes after endotoxin stimulation. Release of tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) by PBMC after rHMGB1 stimulation was also measured.
Serum HMGB1 levels and HMGB1 mRNA expressions in PBMC were elevated in SLE patients compared with controls. A positive correlation was demonstrated between HMGB1 concentrations and SLE Disease Activity Index. There was an inverse correlation between HMGB1 levels and C4 and C3 concentrations in SLE patients. HMGB1 concentrations were higher in patients with vasculitis and myositis. Lipopolysaccharide stimulated a temporarily elevated release of HMGB1 in SLE patients compared with controls. The pattern and localization of HMGB1 staining in monocytes were similar in both groups. After stimulation with rHMGB1, TNF-alpha level decreased but IL-6 level increased in SLE patients compared with controls.
Our findings suggest that increased serum levels of HMGB1 in SLE may be associated with lupus disease activity. The altered production of TNF-alpha and IL-6 in response to rHMGB1 stimulation may participate in the disruption of cytokine homeostasis in SLE.
Article: HMGB1 in Health and Disease.[Show abstract] [Hide abstract]
ABSTRACT: Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed High-Mobility Group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhbitiors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localizationtion, structure, post-translational modification, and identifccation of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.Molecular Aspects of Medicine 07/2014; DOI:10.1016/j.mam.2014.05.001 · 10.30 Impact Factor
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ABSTRACT: Objectives: To investigate whether serum anti-high mobility group box 1 (anti-HMGB1) antibodies are related to the development of skin lesions in systemic lupus erythematosus (SLE). Method: This study involved 21 SLE patients with skin lesions, 18 without skin lesions, and 22 healthy controls. The presence and serum levels of anti-HMGB1-IgG and -IgM were measured by western blot and enzyme-linked immunosorbent assay (ELISA), respectively. HMGB1 expression and serum antibodies deposited in the skin were visualized by immunofluorescence staining. Results: Using western blot analysis, we detected anti-HMGB1-IgG antibodies in 13 out of 21 SLE patients with skin lesions and 11 out of 18 SLE patients without skin lesions (p > 0.05). Serum levels of anti-HMGB1-IgG measured by ELISA were also comparable between the two groups of SLE patients (p > 0.05) but were higher in patients than in healthy controls (p < 0.05). Similar results were found with serum anti-HMGB1-IgM antibodies. HMGB1 accumulated under the stratum corneum in lupus cutaneous lesions without forming immune complexes with IgG or IgM, which were mainly observed along the epidermal-dermal junction. Furthermore, serum anti-HMGB1-IgM was higher in the group of patients with arthritis than in those without arthritis. Conclusions: Based on the findings of the current study, it is unlikely that anti-HMGB1 antibodies play a role in the development of SLE cutaneous lesions.Scandinavian Journal of Rheumatology 12/2014; 44(2):1-7. DOI:10.3109/03009742.2014.928946 · 2.61 Impact Factor
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ABSTRACT: High mobility group box 1 (HMGB1) was originally defined as a ubiquitous nuclear protein, but it was later determined that the protein has different roles both inside and outside of cells. Nuclear HMGB1 regulates chromatin structure and gene transcription, whereas cytosolic HMGB1 is involved in inflammasome activation and autophagy. Extracellular HMGB1 has drawn attention because it can bind to related cell signalling transduction receptors, such as the receptor for advanced glycation end-products, toll-like receptor (TLR)2, TLR4 and TLR9. It also participates in the development and progression of a variety of diseases. HMGB1 is actively secreted by stimulation of the innate immune system, and it is passively released by ischaemia or cell injury. This review focuses on the important role of HMGB1 in the pathogenesis of acute and chronic sterile inflammatory conditions. Strategies that target HMGB1 have been shown to significantly decrease inflammation in several disease models of sterile inflammation, and this may represent a promising clinical approach for treatment of certain conditions associated with sterile inflammation. This article is protected by copyright. All rights reserved.Journal of Internal Medicine 06/2014; 276(5). DOI:10.1111/joim.12276 · 5.79 Impact Factor