The effect of HMGB1 A box on lung injury in mice with acute pancreatitis

Cytokines and inflammatory mediators: Markers involved in interstitial damage to the pancreas in two dengue fever cases associated with acute pancreatitis

Dengue viral (DENV) infections can lead to acute pancreatitis and associated tissue damage. This study examined the pancreas from two fatal cases of DENV for histopathological changes as well as for the detection of cytokines, and other inflammatory mediators. Tissue sections were prepared for examination by ultrastructural and histopathological techniques. Sections from the pancreas of non-infected individuals were prepared in parallel as a control. The presence of viral replication in macrophages was detected by co-staining for the proteins NS3 and CD68 by immunofluorescence. Immunohistochemistry was used to detect cells that expressed cytokines and inflammatory mediators to characterize the inflammatory response. Edema, acinar necrosis and fibrosis areas associated with a mononuclear infiltrate were found in infected tissues. The major site of virus replication appeared to be macrophages based on their exclusive presentation of the viral protein NS3. Pancreatic tissues from the infected individuals also displayed increased levels of high mobility group box-1, caspase-3, gelatinase B and tumor necrosis factor alpha compared to controls. The presence of virus replicating macrophages in the pancreas was associated with multiple changes in tissue structure that included elevated levels of cytokines and inflammatory markers that may differentiate acute pancreatitis due to DENV infections from other causes.

High-mobility group box 1 protein and its role in severe acute pancreatitis

The high mobility group box 1 (HMGB1), which belongs to the subfamily of HMG-1/-2, is a highly conserved single peptide chain consisting of 215 amino acid residues with a molecular weight of approximately 24894 Da. HMGB1 is a ubiquitous nuclear protein in mammals and plays a vital role in inflammatory diseases. Acute pancreatitis is one of the most common causes of acute abdominal pain with a poor prognosis. Acute pancreatitis is an acute inflammatory process of the pancreas (duration of less than six months), for which the severe form is called severe acute pancreatitis (SAP). More and more studies have shown that HMGB1 has a bidirectional effect in the pathogenesis of SAP. Extracellular HMGB1 can aggravate the pancreatic inflammatory process, whereas intracellular HMGB1 has a protective effect against pancreatitis. The mechanism of HMGB1 is multiple, mainly through the nuclear factor-κB pathway. Receptors for advanced glycation end-products and toll-like receptors (TLR), especially TLR-2 and TLR-4, are two major types of receptors mediating the inflammatory process triggered by HMGB1 and may be also the main mediators in the pathogenesis of SAP. HMGB1 inhibitors, such as ethyl pyruvate, pyrrolidine dithiocarbamate and Scolopendra subspinipes mutilans, can decrease the level of extracellular HMGB1 and are the promising targets in the treatment of SAP.

Sodium butyrate protects against severe burn-induced remote acute lung injury in rats

High-mobility group box 1 protein (HMGB1), a ubiquitous nuclear protein, drives proinflammatory responses when released extracellularly. It plays a key role as a distal mediator in the development of acute lung injury (ALI). Sodium butyrate, an inhibitor of histone deacetylase, has been demonstrated to inhibit HMGB1 expression. This study investigates the effect of sodium butyrate on burn-induced lung injury. Sprague-Dawley rats were divided into three groups: 1) sham group, sham burn treatment; 2) burn group, third-degree burns over 30% total body surface area (TBSA) with lactated Ringer's solution for resuscitation; 3) burn plus sodium butyrate group, third-degree burns over 30% TBSA with lactated Ringer's solution containing sodium butyrate for resuscitation. The burned animals were sacrificed at 12, 24, and 48 h after burn injury. Lung injury was assessed in terms of histologic changes and wet weight to dry weight (W/D) ratio. Tumor necrosis factor (TNF)-α and interleukin (IL)-8 protein concentrations in bronchoalveolar lavage fluid (BALF) and serum were measured by enzyme-linked immunosorbent assay, and HMGB1 expression in the lung was determined by Western blot analysis. Pulmonary myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were measured to reflect neutrophil infiltration and oxidative stress in the lung, respectively. As a result, sodium butyrate significantly inhibited the HMGB1 expressions in the lungs, reduced the lung W/D ratio, and improved the pulmonary histologic changes induced by burn trauma. Furthermore, sodium butyrate administration decreased the TNF-α and IL-8 concentrations in BALF and serum, suppressed MPO activity, and reduced the MDA content in the lungs after severe burn. These results suggest that sodium butyrate attenuates inflammatory responses, neutrophil infiltration, and oxidative stress in the lungs, and protects against remote ALI induced by severe burn, which is associated with inhibiting HMGB1 expression.

Danger-associated molecular patterns (DAMPs) in acute lung injury

Danger-associated molecular patterns (DAMPs) are host-derived molecules that can function to regulate the activation of pathogen recognition receptors (PRRs). These molecules play a critical role in modulating the lung injury response. DAMPs originate from multiple sources, including injured and dying cells, the extracellular matrix, or exist as immunomodulatory proteins within the airspace and interstitium. DAMPs can function as either toll-like receptor (TLR) agonists or antagonists, and can modulate both TLR and nod-like receptor (NLR) signalling cascades. Collectively, this diverse group of molecules may represent important therapeutic targets in the prevention and/or treatment of acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS).

High-mobility-group box protein 1A box reduces development of sodium laurate-induced thromboangiitis obliterans in rats

OBJECTIVE

High-mobility-group box protein 1 (HMGB1), as a late mediator of inflammation, plays a key role in inflammatory responses by inducing and extending the production of proinflammatory cytokines. The effect of HGMB1 in the inflammatory disease thromboangiitis obliterans (TAO) is unknown. We aimed to investigate the role of HMGB1 in sodium laurate-induced TAO in rats.

METHODS

Male Wistar rats were randomly divided into five groups (n=8 each) for treatment: normal, sham-operated, TAO model, and low-dose (15 mg/kg) or high-dose (30 mg/kg) recombinant A box (rA box) infection (administered intraperitoneally once daily for 15 days). The TAO model was induced by sodium laurate and graded by gross appearance on day 15 after femoral artery injection. Histologic changes were measured by histopathology in rat femoral arteries. Plasma levels of HMGB1, thromboxane B2, 6-keto-prostaglandin F1-α, and blood cell counts and blood coagulation levels were measured. Expression of HMGB1, receptor for advanced glycation end-products (RAGE), interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was assessed by immunohistochemistry and immunofluorescence, Western blot analysis, and quantitative reverse-transcription polymerase chain reaction.

RESULTS

The typical signs and symptoms of TAO were observed on day 15 after sodium laurate injection. The expression of HMGB1, RAGE, interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was markedly increased in rat femoral arteries. Plasma levels of HMGB1 and thromboxane B2 were elevated, but the level of 6-keto-prostaglandin F1-α was decreased. Blood was in a hypercoagulable state, and prothrombin, thrombin, and activated partial thromboplastin times were all significantly shortened, whereas fibrinogen level was increased in TAO rats compared with sham-operated rats. These effects were terminated by the HMGB1 antagonist rA box.

CONCLUSIONS

HMGB1 is involved in the inflammatory state in a model of TAO induced by sodium laurate in rats, probably via its receptor RAGE. As the antagonist of HMGB1, rA box can attenuate the development of TAO, which may be a potential therapeutic target for the treatment of TAO.