High-mobility group box 1 (HMGB1) protein: friend and foe.
ABSTRACT HMGB1 was originally identified as a DNA-binding protein that functions as a structural co-factor critical for proper transcriptional regulation in somatic cells. Recent studies indicate that HMGB1 can be "passively released" into the extracellular milieu by necrotic and damaged somatic cells. Extracellular HMGB1 represents an optimal "necrotic marker" selected by the innate immune system to recognize tissue damage and initiate reparative responses. HMGB1 in the extracellular milieu promotes maturation of myeloid and plasmacytoid dendritic cells, and induces myocardial regeneration after infarction. However, extracellular HMGB1 also acts as a potent pro-inflammatory cytokine that contributes to the pathogenesis of diverse inflammatory and infectious disorders. A growing number of studies indicate that HMGB1 is a successful therapeutic target in experimental models of ischemia/reperfusion, acute respiratory distress syndrome, rheumatoid arthritis, sepsis, and cancer. From a clinical perspective, HMGB1 represents a current challenge that can be exploited orchestrate reparative responses while preventing its pathological potential. This article focus on the immuno-regulatory role of HMGB1 and its contribution to infectious and inflammatory disorders.
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ABSTRACT: Background High mobility group box-1 (HMGB1), a proinflammatory cytokine, plays a pivotal role in tissue remodeling and angiogenesis, both of which are crucial for the pathogenesis of pulmonary arterial hypertension. In this study, we explored the relationship between HMGB1 and pulmonary hypertension and whether glycyrrhizin, an inhibitor of HMGB1, attenuates disease progression in an animal model of pulmonary hypertension induced by monocrotaline sodium (MCT).Methods After inducing pulmonary hypertension through a single subcutaneous injection of MCT (60 mg/kg) to Sprague¿Dawley rats, we administered daily intraperitoneal injections of either glycyrrhizin (GLY, 50 mg/kg), an inhibitor of HMGB1, or saline (control) for either 4 or 6 weeks.ResultsExpression levels of HMGB1 in serum increased from the second week after MCT injection and remained elevated throughout the experiment periods. Lung tissue levels of HMGB1 assessed by immunohistochemical staining at 4 weeks after MCT injection also increased. Chronic inhibition of HMGB1 by GLY treatment reduced the MCT-induced increase in right ventricular (RV) systolic pressure, RV hypertrophy (ratio of RV to [left ventricle¿+¿septum]), and pulmonary inflammation. MCT-induced muscularization of the pulmonary artery was also attenuated in the GLY-treated group. As assessed 6 weeks after MCT injection, the GLY-treated group exhibited increased survival (90% [18 of 20]) when compared with the control group (60% [12 of 20]; p =0.0027).Conclusions Glycyrrhizin, an inhibitor of HMGB1, attenuates pulmonary hypertension progression and pulmonary vascular remodeling in the MCT-induced pulmonary hypertension rat model. Further studies are needed to confirm the potential of HMGB1 as a novel therapeutic target for pulmonary hypertension.Respiratory Research 11/2014; 15(1):148. DOI:10.1186/s12931-014-0148-4 · 3.13 Impact Factor
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ABSTRACT: Hemorrhagic shock causes more circulatory disturbances and mortality in hypertensive than normotensive subjects. In the late phase of hemorrhagic shock, nitric oxide (NO) overproduction leads to vascular decompensation. In this study, we evaluated the effect of inducible NO synthase (iNOS) inhibitor, aminoguanidine (AG), on hemodynamic parameters and serum nitrite concentration in decompensated hemorrhagic shock model in normotensive and hypertensive male rats. Twenty-four male rats were divided into hypertensive and normotensive groups (n = 12 each). Hypertension was induced by subcutaneous injection of deoxycorticoesterone acetate (DOCA), 30 mg/kg in uninephrectomized rats. Decompensated hemorrhagic shock was induced by withdrawing blood until the mean arterial pressure (MAP) reached 40 mmHg. After 120 min, each group was assigned to aminguanidine (100 mg/kg) and control group. Hemodynamic parameters were monitored for next 60 min. Blood samples were taken before and after shock period and 60 min after treatment. Survival rate was monitored for 72 h. Infusion of AG in normotensive animals caused a transient increase in MAP and increase of heart rate, whereas it did not affect those parameters in hypertensive animals. Hemorrhagic shock caused a significant rise in serum nitrite concentration in normotensive and hypertensive rats and infusion of AG did not significantly change it in both groups. No significant differences observed in survival rate between AG-treated and not treated groups. It seems that inhibition of iNOS with AG does not have beneficial effects on hemodynamatic parameters and survival rate during decompensated hemorrhagic shock in normotensive and hypertensive animals.01/2015; 5(1):12-7. DOI:10.4103/2229-516X.149222
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ABSTRACT: The present study was designed to evaluate the effect of sodium butyrate on pancreas damage and to investigate the role of high-mobility group box-1 (HMGB1) and nuclear factor-κB (NF-κB) in the development of severe acute pancreatitis (SAP) in a mouse model. The SAP model was established by intraperitoneal injection of two doses of 20 % L-2 arginine (200 mg/g). Female Sprague-Dawley mice were randomly allocated into three groups (n = 48/group): the control, untreated SAP, and sodium butyrate-treated SAP groups. The animals were euthanized at 0, 12, 24, and 48 h after the establishment of the SAP. Histopathology of the pancreas was performed, and the NF-κB levels were determined by immunohistochemistry. The serum levels of tumor necrosis factor (TNFα), interleukin-6 (IL-6), and HMGB1 were measured by ELISA. The HMGB1 mRNA levels were determined by qRT-PCR. The sodium butyrate-treated SAP animals showed significantly improved pancreas histopathology and lower serum amylase levels than the untreated SAP animals. In the SAP group, the mRNA levels of HMGB1 were remarkably increased at the 12 h, peaked at 24 h, and remained at a high level up to 48 h after L-2 arginine injection. The levels of TNFα and IL-6 were decreased at 48 h. Treatment with sodium butyrate reduced the pathological lesions, the serum levels of HMGB1, TNFα, and IL-6, the HMGB1 mRNA levels, and NF-κB activity. Sodium butyrate inhibits the NF-κB activation and reduces pancreas injury in SAP through the modulation of HMGB1 and other inflammatory cytokine responses.Digestive Diseases and Sciences 02/2015; DOI:10.1007/s10620-015-3586-z · 2.26 Impact Factor