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Severe acute pancreatitis (SAP) is an extremely dangerous acute abdominal disorder which causes multiple complications and has a high mortality rate. Previous research has suggested that high-mobility group box 1 (HMGB1) plays an important role in the pathogenesis of SAP; however, the mechanisms underlying this strong correlation remain unclear. In this study, to further investigate whether HMGB1 acts as a stimulating factor, and whether Toll-like receptor 4 (TLR4) acts as its major mediator in the development of pancreatic injury during SAP, recombinant human HMGB1 (rhHMGB1) and TLR4-deficient mice were used. We found that HMGB1 and TLR4 were highly expressed, and nuclear factor-κB (NF-κB) was activated in our mouse model of SAP. We noted that the rhHMGB1 pancreas-targeted injection activated the TLR4-mediated NF-κB signaling pathway and induced pancreatic injury in wild-type mice. In TLR4-deficient mice, the rhHMGB1-induced activation of NF-κB and pathological changes in the pancreas were less evident than in wild-type mice. Therefore, this study provides evidence that HMGB1 promotes the pathogenesis of pancreatitis, and its downstream TLR4-mediated NF-κB signaling pathway is a potential important mediator in the development of this form of pancreatic injury.

Lung diseases remain a serious problem for public health. The immune status of the body is considered to be the main influencing factor for the progression of lung diseases. HMGB1 (high‐mobility group box 1) emerges as an important molecule of the body immune network. Accumulating data have demonstrated that HMGB1 is crucially implicated in lung diseases and acts as independent biomarker and therapeutic target for related lung diseases. This review provides an overview of updated understanding of HMGB1 structure, release styles, receptors and function. Furthermore, we discuss the potential role of HMGB1 in a variety of lung diseases. Further exploration of molecular mechanisms underlying the function of HMGB1 in lung diseases will provide novel preventive and therapeutic strategies for lung diseases.

High‐mobility group box 1 (HMGB1) shows pro‐inflammatory activity in various inflammatory diseases and has been found up‐regulated in chronic obstructive pulmonary disease (COPD). Lung macrophages play an important role in airway inflammation and lung destruction in COPD, yet whether HMGB1 is involved in cigarette smoke (CS)‐induced lung macrophage dysfunction is unknown. We sought to evaluate the intracellular localization and release of HMGB1 in lung macrophages from COPD patients and CS‐exposed mice, and to investigate the role of HMGB1 in regulating autophagy in CS extract (CSE)‐treated lung macrophages (MH‐S cells). Our results showed that HMGB1 was highly expressed in lung tissues and sera of COPD patients and CS‐exposed mice, along with predominantly cytoplasmic exporting from nuclei in lung macrophages. In vitro experiments revealed that CSE promoted the expression, nucleocytoplasmic translocation and release of HMGB1 partly via the nicotinic acetylcholine receptor (nAChR). Blockade of HMGB1 with chicken anti‐HMGB1 polyclonal antibody (anti‐HMGB1) or glycyrrhizin (Gly) attenuated the increase of LC3B‐II and Beclin1, migration and p65 phosphorylation, suggesting the involvement of HMGB1 in autophagy, migration and NF‐κB activation of lung macrophages. Hydroxychloroquine (CQ), an autophagy inhibitor, enhanced the increase of LC3B‐II but not Beclin1 in CSE or rHMGB1‐treated MH‐S cells, and inhibition of autophagy by CQ and 3‐methyladenine (3‐MA) abrogated the migration and p65 phosphorylation of CSE‐treated cells. These results indicate that CS‐induced HMGB1 translocation and release contribute to migration and NF‐κB activation through inducing autophagy in lung macrophages, providing novel evidence for HMGB1 as a potential target of intervention in COPD.

Acute pancreatitis (AP) is a serious condition carrying a mortality of 25–40%. Extracellular vesicles (EVs) have reported to exert potential functions in cell‐to‐cell communication in diseases such as pancreatitis. Thus, we aimed at investigating the mechanisms by which EV‐encapsulated metastasis‐associated lung adenocarcinoma transcript‐1 (MALAT1) might mediate the M1 polarization of macrophages in AP. Expression patterns of MALAT1, microRNA‐181a‐5p (miR‐181a‐5p) and high‐mobility group box 1 protein (HMGB1) in serum of AP patients were determined. EVs were isolated from serum and pancreatic cells. The binding affinity among miR‐181a‐5p, MALAT1 and HMGB1 was identified. AP cells were co‐cultured with EVs from caerulein‐treated MPC‐83 cells to determine the levels of M1/2 polarization markers and TLR4, NF‐κB and IKBa. Finally, AP mouse models were established to study the effects of EV‐encapsulated MALAT1 on the M1 polarization of macrophages in AP in vivo. MALAT1 was transferred into MPC‐83 cells via EVs, which promoted M1 polarization of macrophages in AP. MALAT1 competitively bound to miR‐181a‐5p, which targeted HMGB1. Moreover, MALAT1 activated the TLR4 signalling pathway by regulating HMGB1. EV‐encapsulated MALAT1 competitively bound to miR‐181a‐5p to upregulate the levels of IL‐6 and TNF‐α by regulating HMGB1 via activation of the TLR4 signalling pathway, thereby inducing M1 polarization of macrophages in AP. In vivo experimental results also confirmed that MALAT1 shuttled by EVs promoted M1 polarization of macrophages in AP via the miR‐181a‐5p/HMGB1/TLR4 axis. Overall, EV‐loaded MALAT1 facilitated M1 polarization of macrophages in AP via miR‐181a‐5p/HMGB1/TLR4, highlighting a potential target for treating AP.

High‐mobility group box 1 (HMGB1) is 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 from necrotic cells or actively secreted into the extracellular milieu under appropriate signal stimulation. Extracellular HMGB1 is a multifunctional cytokine that contributes to the process of infection, injury, inflammation, apoptosis, and immune responses by binding to specific cell‐surface receptors. Recently, emerging studies indicate that HMGB1 is closely involved in fibrotic disorders including cystic fibrosis, liver fibrosis and pulmonary fibrosis, while HMGB1 signal inhibitions protect against the experimental models of fibrotic diseases. From a clinical perspective, HMGB1 represents a current challenge that can be exploited orchestrate reparative responses. This review focuses on the crucial role of HMGB1 in the pathogenesis of fibrotic diseases and inhibition of which may represent a promising clinical approach for treating tissue fibrosis.

The current anti-cancer treatments are not enough to eradicate tumors, and therefore, new modalities and strategies are still needed. Most tumors generate an inflammatory tumor microenvironment (TME) and maintain the niche for their development. Because of the critical role of inflammation via high-mobility group box 1 (HMGB1)–receptor for advanced glycation end-products (RAGE) signaling pathway in the TME, a novel compound possessing both anti-cancer and anti-inflammatory activities by suppressing the HMGB1-RAGE axis provides an effective strategy for cancer treatment. A recent work of our group found that some anti-cancer 3-styrylchromones have weak anti-inflammatory activities via the suppression of this axis. In this direction, we searched such anti-cancer molecules possessing potent anti-inflammatory activities and discovered 7-methoxy-3-hydroxy-styrylchromone (C6) having dual suppressive activities. Mechanism-of-action studies revealed that C6 inhibited the increased phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) under the stimulation of HMGB1-RAGE signaling and thereby suppressed cytokine production in macrophage-like RAW264.7 cells. On the other hand, in colorectal cancer HCT116 cells, C6 inhibited the activation of ERK1/2, cyclin-dependent kinase 1, and AKT, down-regulated the protein level of XIAP, and up-regulated pro-apoptotic Bax and caspase-3/7 expression. These alterations are suggested to be involved in the C6-induced suppression of cell cycle/proliferation and initiation of apoptosis in the cancer cells. More importantly, in cancer cells, the treatment of C6 potentiates the anti-cancer effects of DNA-damaging agents. Thus, C6 may be a promising lead for the generation of a novel class of cancer therapeutics.

We measured the levels of High‐Mobility Group Box 1 (HMGB1), Receptor for Advanced Glycation Endproducts (RAGE), T Helper 17 cells (Th17), Regulatory T cells (Treg), and related cytokines in the peripheral blood of patients with severe preeclampsia (SPE) complicated with acute heart failure (AHF) to explore the expression changes in these indicators. In total, 96 patients with SPE admitted to Gansu Provincial Maternity and Child‐care Hospital between June 2020 and June 2022 were included in the study. The patients were divided into SPE+AHF (40 patients) and SPE (56 patients) groups based on whether they suffered from AHF. Additionally, 56 healthy pregnant women who either received prenatal examinations or were admitted to our hospital for delivery during the same period were selected as the healthy control group. An enzyme‐linked immunosorbent assay was performed to detect the expression levels of HMGB1, RAGE, interleukin (IL)‐17, IL‐6, transforming growth factor β (TGF‐β), IL‐10, and NT‐proBNP in plasma. Flow cytometry was employed to determine the percentages of Th17 and Treg cells. Compared to the healthy control group, the SPE+AHF and SPE groups had higher plasma levels of HMGB1 and RAGE expression, higher Th17 percentage and Th17/Treg ratio, and lower Treg percentage. Compared to the SPE group, the SPE+AHF group had higher plasma levels of HMGB1 and RAGE expression, higher Th17 percentage and Th17/Treg ratio, and lower Treg percentage ( P  < .05). In patients with SPE with AHF, plasma HMGB1 was positively correlated with RAGE, Th17, Th17/Treg, IL‐17, and IL‐6 and was negatively correlated with TGF‐β and IL‐10 ( P  < .05). Our findings revealed that patients with SPE with AHF had elevated levels of HMGB1 and RAGE while exhibiting Th17/Treg immune imbalance, suggesting that the abnormal expression of these indicators may be involved in the pathogenesis of SPE with AHF.

Ischaemia‐reperfusion injury (I/RI) is a common cause of acute kidney injury (AKI). The molecular basis underlying I/RI‐induced renal pathogenesis and measures to prevent or reverse this pathologic process remains to be resolved. Basic fibroblast growth factor (FGF2) is reported to have protective roles of myocardial infarction as well as in several other I/R related disorders. Herein we present evidence that FGF2 exhibits robust protective effect against renal histological and functional damages in a rat I/RI model. FGF2 treatment greatly alleviated I/R‐induced acute renal dysfunction and largely blunted I/R‐induced elevation in serum creatinine and blood urea nitrogen, and also the number of TUNEL‐positive tubular cells in the kidney. Mechanistically, FGF2 substantially ameliorated renal I/RI by mitigating several mitochondria damaging parameters including pro‐apoptotic alteration of Bcl2/Bax expression, caspase‐3 activation, loss of mitochondrial membrane potential and KATP channel integrity. Of note, the protective effect of FGF2 was significantly compromised by the KATP channel blocker 5‐HD. Interestingly, I/RI alone resulted in mild activation of FGFR, whereas FGF2 treatment led to more robust receptor activation. More significantly, post‐I/RI administration of FGF2 also exhibited robust protection against I/RI by reducing cell apoptosis, inhibiting the release of damage‐associated molecular pattern molecule HMBG1 and activation of its downstream inflammatory cytokines such as IL‐1α, IL‐6 and TNF α. Taken together, our data suggest that FGF2 offers effective protection against I/RI and improves animal survival by attenuating mitochondrial damage and HMGB1‐mediated inflammatory response. Therefore, FGF2 has the potential to be used for the prevention and treatment of I/RI‐induced AKI.

Hepatitis B virus (HBV) X (HBx) protein is a pivotal regulator of HBV‐triggered autophagy. However, the role of HBx‐induced epigenetic changes in autophagy remains largely unknown. The cytoplasmic (Cyt) high‐mobility group box 1 (HMGB1) has been identified as a positive regulator of autophagy, and its Cyt translocation is closely associated with its acetylation status. Here, we evaluated the function of HMGB1 in HBx‐mediated autophagy and its association with histone deacetylase (HDAC). Using cell lines with enforced expression of HBx, we demonstrated that HBx upregulated the expression of HMGB1 and promoted its Cyt translocation by acetylation to facilitate autophagy. We further identified the underlying mechanism by which decreased nuclear HDAC activity and expression levels contribute to the HBx‐promoted hyperacetylation and subsequent translocation of HMGB1. We also identified the HDAC1 isoform as a critical factor in regulating this phenomenon. In addition, HBx bound to HMGB1 in the cytoplasm, which triggered autophagy in hepatocytes. Pharmacological inhibition of HMGB1 Cyt translocation with ethyl pyruvate prevented HBx‐induced autophagy. These results demonstrate a novel function of acetylated HMGB1 in HBx‐mediated autophagy in hepatocytes. Here, we show that hepatitis B virus X (HBx) contributes to high‐mobility group box 1 (HMGB1) cytoplasmic translocation via histone deacetylase (HDAC) inhibition in the setting of hepatitis B virus (HBV) infection. HDACs tilt the acetylation/deacetylation balance of HMGB1 in response to HBx. HBx contributes to the interaction between HMGB1 and Beclin1 to induce autophagy, which participates in the pathological process of HBV replication and hepatocellular carcinoma development.

Myeloid-derived suppressor cells (MDSCs) are notable contributors to the immunosuppressive tumor microenvironment (TME) and are closely associated with tumor progression; in addition, MDSCs are present in most patients with cancer. However, the molecular mechanisms that regulate MDSCs in the etiopathogenesis of human tumor immunity remain unclear. The secreted alarmin high mobility group box 1 (HMGB1) is a proinflammatory factor and inducer of many inflammatory molecules during MDSC development. In this review, we detail the currently reported characteristics of MDSCs in tumor immune escape and the regulatory role of secreted HMGB1 in MDSC differentiation, proliferation, activity and survival. Notably, different posttranslational modifications of HMGB1 may have various effects on MDSCs, and these effects need further identification. Moreover, exosome-derived HMGB1 is speculated to exert a regulatory effect on MDSCs, but no report has confirmed this hypothesis. Therefore, the effects of HMGB1 on MDSCs need more research attention, and additional investigations should be conducted.