HMGB1 Knockdown Research Articles

HMGB1 Modulates Macrophage Metabolism and Polarization in Ulcerative Colitis by Inhibiting Cpt1a Expression.

Macrophage polarization is involved in the development of ulcerative colitis (UC). This study investigated the mechanism by which high mobility group box-1 protein (HMGB1) regulates macrophage polarization through metabolic reprogramming, thereby contributing to the pathogenesis of UC. Dextran sulfate sodium (DSS) was used to induce colitis in mice. RAW264.7 cells were polarized to M1 or M2 macrophages in vitro by stimulating with lipopolysaccharide (LPS)/interferon-γ (IFN-γ) or Interleukin-4 (IL-4), respectively. Macrophage infiltration and distribution within colon tissue were assessed by immunohistochemistry and flow cytometry. Glycolysis, fatty acid oxidation (FAO), and inflammatory factors were evaluated using relevant reagent kits. Chromatin Immunoprecipitation (ChIP) and luciferase reporter experiments were performed to study the regulation of Carnitine palmitoyltransferase 1A (Cpt1a) promoter transcriptional activity by HMGB1. The mouse UC model showed upregulated HMGB1 and increased macrophage infiltration. Overexpression of HMGB1 promoted M1 macrophage polarization, increased glycolysis, and reduced FAO, whereas knockdown of HMGB1 promoted M2 macrophage polarization, reduced glycolysis, and increased FAO. HMGB1 negatively regulated Cpt1a expression by inhibiting transcription of the Cpt1a promoter. Knockdown of Cpt1a reversed the effects of small interfering RNA targeting HMGB1 (si-HMGB1) on macrophage metabolism and polarization. Administration of adeno-associated virus (AAV)-shHMGB1 in vivo caused a reduction in UC symptoms and inflammation. HMGB1 modulates macrophage metabolism in UC by inhibiting Cpt1a expression, leading to increased M1 polarization. This provides a theoretical basis for the clinical application of HMGB1 inhibitors in the treatment of UC.

Hepatocyte-specific loss of DDB1 attenuates hepatic steatosis but aggravates liver inflammation and fibrosis in MASH.

MASH is a common clinical disease that can lead to advanced liver conditions, but no approved pharmacotherapies are available due to an incomplete understanding of its pathogenesis. Damaged DNA binding protein 1 (DDB1) participates in lipid metabolism. Nevertheless, the function of DDB1 in MASH is unclear. Clinical liver samples were obtained from patients with MASH and control individuals by liver biopsy. Hepatocyte-specific Ddb1-knockout mice and liver Hmgb1 knockdown mice were fed with a methionine-and choline-deficient diet to induce MASH. We found that the expression of DDB1 in the liver was significantly decreased in MASH models. Hepatocyte-specific ablation of DDB1 markedly alleviated methionine-and choline-deficient diet-induced liver steatosis but unexpectedly exacerbated inflammation and fibrosis. Mechanistically, DDB1 deficiency attenuated hepatic steatosis by downregulating the expression of lipid synthesis and uptake genes. We identified high-mobility group box 1 as a key candidate target for DDB1-mediated liver injury. DDB1 deficiency upregulated the expression and extracellular release of high-mobility group box 1, which further increased macrophage infiltration and activated HSCs, ultimately leading to the exacerbation of liver inflammation and fibrosis. These data demonstrate the independent regulation of hepatic steatosis and injury in MASH. These findings have considerable clinical implications for the development of therapeutic strategies for MASH.

HMGB1 Modulates High Glucose-Induced Erroneous Differentiation of Tendon Stem/Progenitor Cells through RAGE/β-Catenin Pathway.

The association of tendinopathy with diabetes has been well recognized. Tendon stem/progenitor cells (TSPCs) play critical roles in tendon repair, regeneration, and homeostasis maintenance. Diabetic TSPCs exhibit enhanced erroneous differentiation and are involved in the pathogenesis of diabetic tendinopathy, whereas the underlying mechanism of the erroneous differentiation of TSPCs remains unclear. Here, we showed that high glucose treatment promoted the erroneous differentiation of TSPCs with increased osteogenic differentiation capacity and decreased tenogenic differentiation ability, and stimulated the expression and further secretion of HMGB1 in TSPCs and. Functionally, exogenous HMGB1 significantly enhanced the erroneous differentiation of TSPCs, while HMGB1 knockdown mitigated high glucose-promoted erroneous differentiation of TSPCs. Mechanistically, the RAGE/β-catenin signaling was activated in TSPCs under high glucose, and HMGB1 knockdown inhibited the activity of RAGE/β-catenin signaling. Inhibition of RAGE/β-catenin signaling could ameliorate high glucose-induced erroneous differentiation of TSPCs. These results indicated that HMGB1 regulated high glucose-induced erroneous differentiation of TSPCs through the RAGE/β-catenin signaling pathway. Collectively, our findings suggest a novel essential mechanism of the erroneous differentiation of TSPCs, which might contribute to the pathogenesis of diabetic tendinopathy and provide a promising therapeutic target and approach for diabetic tendinopathy.

IL6/adiponectin/HMGB1 feedback loop mediates adipocyte and macrophage crosstalk and M2 polarization after myocardial infarction.

Differences in border zone contribute to different outcomes post-infarction, such as left ventricular aneurysm (LVA) and myocardial infarction (MI). LVA usually forms within 24h of the onset of MI and may cause heart rupture; however, LVA surgery is best performed 3 months after MI. Few studies have investigated the LVA model, the differences in border zones between LVA and MI, and the mechanism in the border zone. The LVA, MI, and SHAM mouse models were used. Echocardiography, Masson's trichrome staining, and immunofluorescence staining were performed, and RNA sequencing of the border zone was conducted. The adipocyte-conditioned medium-treated hypoxic macrophage cell line and LVA and MI mouse models were employed to determine the effects of the hub gene, adiponectin (ADPN), on macrophages. Quantitative polymerase chain reaction (qPCR), Western blot analysis, transmission electron microscopy, and chromatin immunoprecipitation (ChIP) assays were conducted to elucidate the mechanism in the border zone. Human subepicardial adipose tissue and blood samples were collected to validate the effects of ADPN. A novel, simple, consistent, and low-cost LVA mouse model was constructed. LVA caused a greater reduction in contractile functions than MI owing to reduced wall thickness and edema in the border zone. ADPN impeded cardiac edema and promoted lymphangiogenesis by increasing macrophage infiltration post-infarction. Adipocyte-derived ADPN promoted M2 polarization and sustained mitochondrial quality via the ADPN/AdipoR2/HMGB1 axis. Mechanistically, ADPN impeded macrophage HMGB1 inflammation and decreased interleukin-6 (IL6) and HMGB1 secretion. The secretion of IL6 and HMGB1 increased ADPN expression via STAT3 and the co-transcription factor, YAP, in adipocytes. Based on ChIP and Dual-Glo luciferase experiments, STAT3 promoted ADPN transcription by binding to its promoter in adipocytes. In vivo, ADPN promoted lymphangiogenesis and decreased myocardial injury after MI. These phenotypes were rescued by macrophage depletion or HMGB1 knockdown in macrophages. Supplying adipocytes overexpressing STAT3 decreased collagen disposition, increased lymphangiogenesis, and impaired myocardial injury. However, these effects were rescued after HMGB1 knockdown in macrophages. Overall, the IL6/ADPN/HMGB1 axis was validated using human subepicardial tissue and blood samples. This axis could serve as an independent factor in overweight MI patients who need coronary artery bypass grafting (CABG) treatment. The IL6/ADPN/HMGB1 loop between adipocytes and macrophages in the border zone contributes to different clinical outcomes post-infarction. Thus, targeting the IL6/ADPN/HMGB1 loop may be a novel therapeutic approach for cardiac lymphatic regulation and reduction of cell senescence post-infarction.

GATA3 promotes the autophagy and activation of hepatic stellate cell in hepatic fibrosis via regulating miR-370/HMGB1 pathway

BackgroundHepatic fibrosis (HF) is a common result of the repair process of various chronic liver diseases. Hepatic stellate cells (HSCs) activation is the central link in the occurrence of HF. MethodsELISA and histological analysis were performed to detect the pathological changes of liver tissues. In vitro, HSCs were treated with TGF-β1 as HF cell model. Combination of GATA-binding protein 3 (GATA3) and miR-370 gene promoter was ensured by ChIP and luciferase reporter assay. Autophagy was monitored by observing the GFP-LC3 puncta formation. The interaction between miR-370 and high mobility group box 1 protein (HMGB1) was verified by luciferase reporter assay. ResultsCCl4-induced HF mice exhibited an increase of ALT and AST, and severe damage and fibrosis of liver tissues. GATA3 and HMGB1 were up-regulated, and miR-370 was down-regulated in CCl4-induced HF mice and activated HSCs. GATA3 enhanced expression of the autophagy-related proteins and activation markers in the activated HSCs. Inhibition of autophagy partly reversed GATA3-induced activation of HSCs and the promotion of GATA3 to hepatic fibrosis. Moreover, GATA3 suppressed miR-370 expression via binding with its promotor, and enhanced HMGB1 expression in HSCs. Increasing of miR-370 inhibited HMGB1 expression by directly targeting its mRNA 3′-UTR. The promotion of GATA3 to TGF-β1-induced HSCs autophagy and activation was abrogated by miR-370 up-regulation or HMGB1 knockdown. ConclusionsThis work demonstrates that GATA3 promotes autophagy and activation of HSCs by regulating miR-370/HMGB1 signaling pathway, which contributes to accelerate HF. Thus, this work suggests that GATA3 may be a potential target for prevention and treatment of HF.

Ubiquitination of cytoplasmic HMGB1 by RNF186 regulates hepatic lipophagy in non-alcoholic fatty liver disease

BackgroundLipophagy is a vital biological process that maintains the balance of intracellular lipid metabolism in nonalcoholic fatty liver disease (NAFLD). However, the precise regulatory mechanism of RNF186 in hepatic lipophagy is still unclear. This study investigates the roles and mechanisms of RNF186 in the regulation of lipophagy during the development of NAFLD. MethodsIn this study, we employed RNF186 knockout mice as well as human liver cells and mouse primary hepatocytes (MPHs) to investigate the role and mechanisms of RNF186 in lipophagy during the progression of NAFLD. Additionally, liver specimens from individuals with NAFLD were examined to assess the expression of RNF186 and its associated factors. ResultsHere, we provide evidence that depletion of RNF186 enhances lipophagy in hepatocytes of a NAFLD model. Mechanistically, RNF186 acts as an E3 ubiquitin ligase that targets cytoplasmic HMGB1 for lysine 48 (K48)- and K63-linked ubiquitination, leading to its subsequent proteasomal degradation. Importantly, the translocation of HMGB1 from the nucleus to the cytoplasm is responsible for inducing lipophagy in NAFLD samples. Knockdown of HMGB1 significantly reduces the activation of lipophagy and mediates the decrease in lipid accumulation caused by RNF186 depletion in hepatocytes. Furthermore, we find that maintaining the nuclear HMGB1 level and inhibiting its nuclear-cytoplasmic shuttling are critical for the proper function of RNF186 in NAFLD. Additionally, the expression of RNF186 and HMGB1 in human NAFLD samples, along with factors related to lipophagy, suggest that RNF186 may play a similar role in the pathogenesis of human fatty liver. ConclusionRNF186 deficiency accelerates hepatic lipophagy in NAFLD through the inhibition of ubiquitination and degradation of cytoplasmic HMGB1. Consequently, targeting the RNF186-HMGB1 axis may offer a promising strategy for the prevention and treatment of NAFLD.

Acupressure bladder meridian alleviates anxiety disorder via HMGB1

The aim of this study was to investigate the effects of acupressure bladder meridian (ABM) on anxiety in rats with chronic stress.Methods: The sugar water preference (SPF), tail suspension time (TST) and forced swimming time (FST) of rats were measured. The levels of reactive oxygen species (ROS), myeloperoxidase (MPO) in hippocampus tissue, oxidative stress parameters and inflammatory cytokines were detected. Underlying mechanisms of ABM on anxiety were detected. lipopolysaccharide (LPS) stimulated PC12 cells were adopted in vitro. HMGB1 knockdown were used in PC12 cells, and related signaling was further detected.Results: ABM significantly increased SPF, decreased TST and FST. ABM decreased ROS, MPO levels, decreased the levels of inflammatory cytokines. Furthermore, ABM decreased the levels of oxidative stress index. ABM reduced the expression of inflammation-related proteins mediated by HMGB1, increased nuclear factor erythroid2-related factor 2 (Nrf-2) and hemeoxygenase-1 (HO-1). In vitro PC12 cells, Rat serum (RS-ABM) treated with ABM significantly decreased LPS induced inflammation-related proteins and increased Nrf-2/HO-1 pathway. HMGB1 knockdown inhibited LPS-induced PC12 cell inflammatory signaling pathway and increased Nrf-2/HO-1 pathway.Conclusion: Our results demonstrated that ROS-dependent HMGB1 plays an important role in anxiety, and ABM exhibits inhibited inflammation in anxiety.

Effects of Isoflurane on the Cell Pyroptosis in the Lung Cancer Through the HMGB1/RAGE Pathway.

There are many common malignant tumors in clinic. Among them, lung cancer is caused by the failure of suction system, which seriously threatens the life safety of patients. Recent studies have found that anesthetics have achieved certain efficacy in many cancers. Isoflurane, an inhaled anesthetic, is used in this study to explore whether it can prevent the lung cancer development.The A549 and H1299 were purchased. Cell viability was tested by CCK-8 experiment. Cell death and pyroptosis were analyzed by PI staining as well as flow cytometry. HMGB1 as well as RAGE protein levels were tested by Western blot. The same is true of pyroxin-related proteins. The HMGB1 as well as RAGE levels in the lung cancer tissues were determined by Western blot along with immunohistochemistry.Isoflurane treatment can reduce cell viability and promote cell pyroptosis. Additionally, the protein levels of cleaved caspase-1, IL-1β, GSDMD-N, NLRP3, HMGB1, and RAGE were dramatically up-regulated in the lung cancer after isoflurane treatment. Down-regulated proteins in lung cancer tissues include HMGB1 and RAGE proteins. After HMGB1 knockdown or FPS-ZM1 treatment, the role of isoflurane in the lung cancer was neutralized.This study demonstrated that isoflurane induced the cell pyroptosis in the lung cancer through activating the HMGB1/RAGE pathway.

HMGB1/STAT3/p65 axis drives microglial activation and autophagy exert a crucial role in chronic Stress-Induced major depressive disorder

IntroductionNeuroinflammation and autophagy are implicated in stress-related major depressive disorder (MDD), but the underlying molecular mechanisms remain largely unknown. ObjectivesHere, we identified that MDD regulated by HMGB1/STAT3/p65 axis mediated microglial activation and autophagy for the first time. Further investigations were performed to uncover the effects of this axis on MDD in vivo and in vitro. MethodsBioinformatics analyses were used to re-analysis the transcriptome data from the dorsolateral prefrontal cortex (dlPFC) of post-mortem male MDD patients. The expression level of HMGB1 and its correlation with depression symptoms were explored in MDD clinical patients and chronic social defeat stress (CSDS)-induced depression model mice. Specific adeno-associated virus and recombinant (r)HMGB1 injection into the medial PFC (mPFC) of mice, and pharmacological inhibitors with rHMGB1 in two microglial cell lines exposed to lipopolysaccharide were used to analyze the effects of HMGB1/STAT3/p65 axis on MDD. ResultsThe differential expression of genes from MDD patients implicated in microglial activation and autophagy regulated by HMGB1/STAT3/p65 axis. Serum HMGB1 level was elevated in MDD patients and positively correlated with symptom severity. CSDS not only induced depression-like states in mice, but also enhanced microglial reactivity, autophagy as well as activation of the HMGB1/STAT3/p65 axis in mPFC. The expression level of HMGB1 was mainly increased in the microglial cells of CSDS-susceptible mice, which also correlated with depressive-like behaviors. Specific HMGB1 knockdown produced a depression-resilient phenotype and suppressed the associated microglial activation and autophagy effects of CSDS-induced. The effects induced by CSDS were mimicked by exogenous administration of rHMGB1 or specific overexpression of HMGB1, while blocked by STAT3 inhibitor or p65 knockdown. In vitro, inhibition of HMGB1/STAT3/p65 axis prevented lipopolysaccharide-induced microglial activation and autophagy, while rHMGB1 reversed these changes. ConclusionOur study established the role of microglial HMGB1/STAT3/p65 axis in mPFC in mediating microglial activation and autophagy in MDD.

GATA3 promotes the autophagy and activation of hepatic stellate cell in hepatic fibrosis via regulating miR-370/HMGB1 pathway

BackgroundHepatic fibrosis (HF) is a common result of the repair process of various chronic liver diseases. Hepatic stellate cells (HSCs) activation is the central link in the occurrence of HF. MethodsELISA and histological analysis were performed to detect the pathological changes of liver tissues. In vitro, HSCs were treated with TGF-β1 as HF cell model. Combination of GATA-binding protein 3 (GATA3) and miR-370 gene promoter was ensured by ChIP and luciferase reporter assay. Autophagy was monitored by observing the GFP-LC3 puncta formation. The interaction between miR-370 and high mobility group box 1 protein (HMGB1) was verified by luciferase reporter assay. ResultsCCl4-induced HF mice exhibited an increase of ALT and AST, and severe damage and fibrosis of liver tissues. GATA3 and HMGB1 were up-regulated, and miR-370 was down-regulated in CCl4-induced HF mice and activated HSCs. GATA3 enhanced expression of the autophagy-related proteins and activation markers in the activated HSCs. Inhibition of autophagy partly reversed GATA3-induced activation of HSCs and the promotion of GATA3 to hepatic fibrosis. Moreover, GATA3 suppressed miR-370 expression via binding with its promotor, and enhanced HMGB1 expression in HSCs. Increasing of miR-370 inhibited HMGB1 expression by directly targeting its mRNA 3′-UTR. The promotion of GATA3 to TGF-β1-induced HSCs autophagy and activation was abrogated by miR-370 up-regulation or HMGB1 knockdown. ConclusionsThis work demonstrates that GATA3 promotes autophagy and activation of HSCs by regulating miR-370/HMGB1 signaling pathway, which contributes to accelerate HF. Thus, this work suggests that GATA3 may be a potential target for prevention and treatment of HF.

Activation of the NLRP3 inflammasome by HMGB1 through inhibition of the Nrf2/HO-1 pathway promotes bleomycin-induced pulmonary fibrosis after acute lung injury in rats.

Acute lung injury (ALI) is a common complication of critical diseases with high morbidity and mortality. This study explored the regulatory role and mechanism of high mobility histone box 1 protein (HMGB1) on pulmonary fibrosis (PF) after ALI in rats through nucleotide oligomerization domain-like receptor protein-3 (NLRP3) inflammasome. PF rat models after ALI were established by induction of bleomycin. Degree of fibrosis was assessed by Masson staining and Ashcroft scoring. Hydroxyproline (Hyp) contents in lung tissues and rat lung tissue morphology were detected by enzyme-linked-immunosorbent serologic assay (ELISA) and hematoxylin and eosin staining. The levels of NLRP3, major proteins of NLRP3 inflammasome (NLRP3/ASC/caspase-1), and downstream inflammatory cytokines interleukin (IL)-1 and IL-18 were determined using immunohistochemistry, Western blotting analysis, and ELISA. The nuclear/cytoplasmic nuclear factor erythroid 2-related factor 2 (Nrf2) levels and HO-1 levels were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis. Rats was injected with lentivirus carrying short hairpin (sh)-HMGB1 and zinc protoporphyria (ZNPP) (HO-1 inhibitor) to assess the effects of HMGB1 and HO-1 on PF and NLRP3 inflammasome activation. Bleomycin induced PF after ALI in rats, manifested as patchy fibrosis, atelectasis, and excessive expansion, and increased Aschcroft score and Hyp content. Bleomycin treatment enhanced levels of NLRP3, ASC, caspase-1, IL-1, and IL-18 in rat lung tissues, which promoted activation of NLRP3 inflammasome. HMGB1 was up-regulated in bleomycin-induced rats. HMGB1 knockdown partially reversed NLRP3 inflammasome activation and PF progression. HMGB1 knockdown promoted Nrf2 nuclear translocation and up-regulated HO-1. Suppression of HO-1 partially reversed inhibition of HMGB1 knockdown on NLRP3 inflammasome activation and PF. HMGB1 can activate NLRP3 inflammasomes and promote PF by inhibiting the Nrf2/HO-1 pathway.

The Nrf2/HMGB1/NF-κB axis modulates chondrocyte apoptosis and extracellular matrix degradation in osteoarthritis.

Osteoarthritis (OA) is a degenerative or posttraumatic condition of the joints. In OA chondrocytes, Nrf2 functions as a stress response regulator with antioxidant and anti-inflammatory effects. This study aims to investigate the role of Nrf2 and its downstream pathway in the development of osteoarthritis. IL-1β treatment suppresses Nrf2, aggrecan, and COL2A1 levels and cell viability but promotes apoptosis in chondrocytes. IL-1β stimulation induces cell apoptosis, upregulates the mRNA expression of inflammatory factors, decreases aggrecan, COL2A1, and Bcl-2 levels but increases ADAMTS-5, ADAMTS-4, MMP13, cleaved caspase 3, and BAX levels, and promotes p65 phosphorylation. Nrf2 overexpression exerts opposite effects on IL-1β-treated chondrocytes, as demonstrated by the significant attenuation of IL-1β-induced changes in chondrocytes. By binding to the HMGB1 promoter region, Nrf2 suppresses HMGB1 expression. Similar to Nrf2 overexpression, HMGB1 knockdown also attenuates IL-1β-induced changes in chondrocytes. Notably, under IL-1β stimulation, the effects of Nrf2 overexpression or tert-butylhydroquinone (TBHQ, an activator of Nrf2) on apoptosis, inflammatory factor expression, ECM and apoptosis, and NF-κB pathway activity in chondrocytes are remarkably reversed by HMGB1 overexpression or recombinant HMGB1 (rHMGB1). Similarly, rHMGB1 could partially counteract the curative effect of TBHQ on OA damage in mice. In OA cartilage tissue samples, the level of Nrf2 is lower, while the levels of HMGB1, apoptotic, and inflammatory factors are increased compared to normal cartilage tissue samples. In conclusion, for the first time, the Nrf2/HMGB1 axis was found to modulate apoptosis, ECM degradation, inflammation and activation of NF-κB signaling in chondrocytes and OA mice.

Rosuvastatin suppresses TNF-α-induced matrix catabolism, pyroptosis and senescence via the HMGB1/NF-κB signaling pathway in nucleus pulposus cells.

Intervertebral disc degeneration is mainly caused by irregular matrix metabolism in nucleus pulposus cells and involves inflammatory factors such as TNF-α. Rosuvastatin, which is widely used in the clinic to reduce cholesterol levels, exerts anti-inflammatory effects, but whether rosuvastatin participates in IDD remains unclear. The current study aims to investigate the regulatory effect of rosuvastatin on IDD and the potential mechanism. In vitro experiments demonstrate that rosuvastatin promotes matrix anabolism and suppresses catabolism in response to TNF-α stimulation. In addition, rosuvastatin inhibits cell pyroptosis and senescence induced by TNF-α. These results demonstrate the therapeutic effect of rosuvastatin on IDD. We further find that HMGB1, a gene closely related to cholesterol metabolism and the inflammatory response, is upregulated in response to TNF-α stimulation. HMGB1 inhibition or knockdown successfully alleviates TNF-α-induced ECM degradation, senescence and pyroptosis. Subsequently, we find that HMGB1 is regulated by rosuvastatin and that its overexpression abrogates the protective effect of rosuvastatin. We then verify that the NF-κB pathway is the underlying pathway regulated by rosuvastatin and HMGB1. In vivo experiments also reveal that rosuvastatin inhibits IDD progression by alleviating pyroptosis and senescence and downregulating HMGB1 and p65. This study might provide new insight into therapeutic strategies for IDD.

Glutathione S-transferase zeta 1 alters the HMGB1/GPX4 axis to drive ferroptosis in bladder cancer cells.

The ability of glutathione S-transferase zeta 1 (GSTZ1) to modulate homeostasis of cellular redox and induce ferroptosis was explored in bladder cancer cells, and the involvement of the high mobility group protein 1/glutathione peroxidase 4 (HMGB1/GPX4) in these effects was studied. BIU-87 cells stably overexpressing GSTZ1 were transfected with appropriate plasmids to deplete HMGB1 or overexpress GPX4, then treated with deferoxamine and ferrostatin-1. Antiproliferative effects were assessed by quantifying levels of ferroptosis markers, such as iron, glutathione (GSH), malondialdehyde (MDA), reactive oxygen species (ROS), GPX4, transferrin, and ferritin. GSTZ1 was significantly downregulated in bladder cancer cells. GSTZ1 overexpression downregulated GPX4 and GSH, while greatly increasing levels of iron, MDA, ROS, and transferrin. GSTZ1 overexpression also decreased proliferation of BIU-87 cells and activated HMGB1/GPX4 signaling. The effects of GSTZ1 on ferroptosis and proliferation were antagonized by HMGB1 knockdown or GPX4 overexpression. GSTZ1 induces ferroptotic cell death and alters cellular redox homeostasis in bladder cancer cells, and these effects involve activation of the HMGB1/GPX4 axis.

The STAT1/HMGB1/NF-κB pathway in chronic inflammation and kidney injury after cisplatin exposure.

Rationale: Cisplatin, a potent chemotherapeutic drug, induces side effects in normal tissues including the kidney. To reduce the side effects, repeated low-dose cisplatin (RLDC) is commonly used in clinical setting. While RLDC reduces acute nephrotoxicity to certain extents, a significant portion of patients later develop chronic kidney problems, underscoring the need for novel therapeutics to alleviate the long-term sequelae of RLDC therapy. Methods: In vivo, the role of HMGB1 was examined by testing HMGB1 neutralizing antibodies in RLDC mice. In vitro, the effects of HMGB1 knockdown on RLDC-induced nuclear factor-κB (NF-κB) activation and fibrotic phenotype changes were tested in proximal tubular cells. To study signal transducer and activator of transcription 1 (STAT1), siRNA knockdown and its pharmacological inhibitor Fludarabine were used. We also searched the Gene Expression Omnibus (GEO) database for transcriptional expression profiles and evaluated kidney biopsy samples from CKD patients to verify the STAT1/HMGB1/NF-κB signaling axis. Results: We found that RLDC induced kidney tubule damage, interstitial inflammation, and fibrosis in mice, accompanied by up-regulation of HMGB1. Blockage of HMGB1with neutralizing antibodies and Glycyrrhizin suppressed NF-κB activation and associated production of pro-inflammatory cytokines, reduced tubular injury and renal fibrosis, and improved renal function after RLDC treatment. Consistently, knockdown of HMGB1 decreased NF-κB activation and prevented the fibrotic phenotype in RLDC-treated renal tubular cells. At the upstream, knockdown of STAT1 suppressed HMGB1 transcription and cytoplasmic accumulation in renal tubular cells, suggesting a critical role of STAT1 in HMGB1 activation. Upregulation of STAT1/HMGB1/NF-κB along with inflammatory cytokines was also verified in kidney tissues of CKD patients. Conclusion: These results unravel the STAT1/HMGB1/NF-κB pathway that contributes to persistent inflammation and chronic kidney problems after cisplatin nephrotoxicity, suggesting new therapeutic targets for kidney protection in cancer patients receiving cisplatin chemotherapy.

Histone lactylation promotes cell proliferation, migration and invasion through targeting HMGB1 in endometriosis.

Endometriosis is defined as a condition with endometrium-like tissues migrating outside of the pelvic cavity. However, the mechanism of endometriosis is still unclear. Lactate can be covalently modified to lysine residues of histones and other proteins, which is called lactylation. The results showed that the higher level of lactate and lactate dehydrogenase A enhanced the histone H3 lysine 18 lactylation (H3K18lac) in ectopic endometrial tissues and ectopic endometrial stromal cells than that in normal endometrial tissues and normal endometrial stromal cells. Lactate promoted cell proliferation, migration, and invasion in endometriosis. Mechanistically, lactate induced H3K18lac to promote the expression of high-mobility group box 1 (HMGB1) in endometriosis, and HMGB1 knockdown significantly reduced the cell proliferation, migration, and invasion of the lactate-treated cells through the phosphorylation of AKT. In conclusion, lactate could induce histone lactylation to promote endometriosis progression by upregulating the expression of HMGB1, which may provide a novel target for the prevention and treatment of endometriosis.

Oncogenic Role of HMGB1 as An Alarming in Robust Prediction of Immunotherapy Response in Colorectal Cancer.

Simple SummaryThe high mobility group box1 (HMGB1) protein operates as an alarm for danger. We explore the correlation between HMGB1 expression and the clinical survival status of patients receiving antitumor immunotherapy toward assessing the prognostic value in a multicancer context. We further conducted screening and identified four interacting genes that are targeted for binding by HMGB1-proteins and validate and contextualize the results in vitro. Additionally, HMGB1 function is also remarkably related to the tumor immune microenvironment and immune infiltration, especially regarding the high purity of stromal and immune cells in the tumor microenvironment (TME). In multicancer analysis, HMGB1 is also found linked with frequently genetic mutations and deletions, including in TMB and MSI which lead to resistance against antitumor immunotherapy and worse clinical prognosis among patients. The combination of HMGB1 expression with immune checkpoint molecules (ICPs), such as PD-L1, might present a novel immunology-based antitumor immunotherapy strategy.Objective: To assess the correlation between HMGB1 expression and the patient prognosis in a multicancer context. Methods: The potential oncogenic role of HMGB1 was explored in forty tumors through the TCGA, GEO, and Oncomine datasets. We analyzed the clinical prognostic value and antitumor immunotherapy of HMGB1 in a multicancer context using GEO (GSE111636). Results: High expression of HMGB1 is present in multicancer cases, and its low expression is closely associated with the prognostic survival of patients, in terms of both overall and disease-free survival in ACC and LUAD. Further investigation revealed that the high expression of gastric and lung cancer is closely associated with low risk and better prognosis of patients based on COX and Kaplan–Meier analysis of OS, FP and PPS. HMGB1 expression was found to be significantly correlated with cancer-associated fibroblast and CD8+ T cell infiltration in the TME. The analysis of GO functional annotation/KEGG pathways indicates that HMGB1 may regulate tumor immunity-related pathways, such as the tumor immunotherapy response in colorectal cancer. The function of four genes as hubs are confirmed by in vitro HMGB1 knockdown which led to inhibition of cell proliferation and metastasis in SW620 and SW480 cells. Conclusion: HMGB1 is a potential novel biomarker for improving clinical prognosis and antitumor immunotherapy efficacy. CDK1, HMGB2, SSRP1, and H2AFV may serve as key nodes for HMGB1 in colorectal cancer.

High-mobility group box chromosomal protein-1 deletion alleviates osteoporosis in OVX rat model via suppressing the osteoclastogenesis and inflammation

BackgroundOsteoporosis is a skeletal metabolic disease that constitutes a great threaten to human health. However, there is currently no gold standard for its treatment. High-mobility group box chromosomal protein-1 (HMGB-1) has been reported to play an important role in various orthopedic diseases. Till now, its role in osteoporosis remains elusive.MethodsRats underwent ovariectomy (OVX) were used to construct a postmenopausal model of osteoporosis. Then, rats were divided into sham groups without OVX surgery, OVX model group, HMGB-1 knockdown (HMGB-1 KD) OVX model groups. The expression of HMGB1 was evaluated by qRT-PCR and western blotting. Subsequently, the changes of trabeculae were evaluated by micro-computed tomography (CT) assay. Skeletal necrosis and metabolism were further analyzed by hematoxylin–eosin (HE) staining, Alcian blue staining and Masson’s trichrome staining. The contents of serum alkaline phosphatase (ALP) and osteocalcin were detected by ELISA assay. Expression of osteoclast-associated receptor (OSCAR) and tartrate-resistant acid phosphatase (TRAP) were determined to investigate the effects of HMGB-1 loss on osteoclastogenesis.ResultsSingle HMGB-1 deletion exerted no significant effect on rat trabeculae, serum ALP and osteocalcin. Noticeably, HMGB1 knockdown dramatically ameliorated OVX-induced changes in above indexes. Trabeculae structures of OVX rats were sparse with disorder arrangement, which were greatly recovered after HMGB-1 deletion. Enhanced osteoclastogenesis was observed in OVX rats by increasing number of TRAP + cells and expression of TRAP and OSCAR, and loss of HMGB1 ameliorated osteoclastogenesis in OVA rats. Moreover, HMGB-1 deletion antagonized OVX-evoked downregulation of osteoblast activity markers osterix (OSX), collagen type I alpha 1(COL1A1) and distal-less homeobox 2 (DLX2) protein. Furthermore, loss of HMGB-1 attenuated fluctuation of inflammatory factors in OVX rats. Additionally, HMGB-1 deficiency inhibited OVX-evoked activation of the Toll-like receptor (TLR) 4/NF-κB signaling pathway. Moreover, reactivating the TLR4 signaling further aggravated OVX-induced osteoporosis, which was reversed by HMGB1 knockdown.ConclusionHMGB-1 deletion alleviated OVX-triggered osteoporosis by suppressing osteoclastogenesis and inflammatory disorder via the inhibition of the TLR4 signaling. Therefore, HMGB-1 may be a promising therapeutic target for osteoporosis.

HMGB1-mediated autophagy promotes gefitinib resistance in human non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) ranks the first in incidence and mortality among malignant tumors in China. Molecular targeted therapies such as gefitinib, an oral inhibitor of the epidermal growth factor receptor tyrosine kinase, have shown significant benefits in patients with advanced NSCLC. However, most patients have unsatisfactory outcomes due to the development of drug resistance, and there is an urgent need to better understand the pathways involved in the resistance mechanisms. In this study, we found that HMGB1 is highly expressed in drug-resistant cells and confers to gefitinib resistance in NSCLC cells via activating autophagy process. Gefitinib upregulates HMGB1 expression in time-dependent and dose-dependent manners in human NSCLC cells. RNA interference-mediated knockdown of HMGB1 reduces PC9GR cell viability, induces apoptosis, and partially restores gefitinib sensitivity. Mechanistic analyses indicate that elevated HMGB1 expression contributes to gefitinib resistance by inducing autophagy. Thus, our results suggest that HMGB1 is an autophagy regulator and plays a key role in gefitinib resistance of NSCLC.

Inhibition of HMGB1/TLR4 Signaling Pathway by Digitoflavone: A Potential Therapeutic Role in Alcohol-Associated Liver Disease.

Digitoflavone (DG) is a natural flavonoid abundant in many fruits, vegetables, and medicinal plants. We investigated whether DG inhibits lipid accumulation and inflammatory responses in alcoholic liver disease (ALD) in vivo and in vitro. The mouse ALD model was established by chronically feeding male C57BL/6 mice an ethanol-containing Lieber-DeCarli liquid diet. In vitro, mouse peritoneal macrophages (MPMs) and mouse bone marrow-derived macrophages (BMDMs) were stimulated with LPS/ATP, whereas HepG2 cells and mouse primary hepatocytes were treated with ethanol. DG reduced the serum levels of transaminase and serum and hepatic levels of triglycerides and malondialdehyde in ALD mice. DG downregulated SREBP1 and its target genes and upregulated PPARα and its target genes in the liver of mice with ALD. DG inhibited TLR4-mediated NLRP3 inflammasome activation, consequently reversing the inflammatory response, including the production of HMGB1, IL-1β, and IL-36γ, as well as the infiltration of macrophages and neutrophils. DG blocked NLRP3/ASC/caspase-1 inflammasome activation and HMGB1 release in LPS/ATP-stimulated MPMs. When Tlr4 was knocked in LPS/ATP-stimulated BMDMs, HMGB1 production and release were blocked, and NLRP3-mediated cleavage and release of IL-1β was suppressed in Hmgb1-silenced BMDMs. DG amplified these inhibitory effects in Tlr4 or Hmgb1 knockdown BMDMs. In ethanol-exposed hepatocytes, DG reduced lipogenesis and promoted lipid oxidation by inhibiting the HMGB1-TLR4 signaling pathway while suppressing the inflammatory response induced by ethanol exposure. Our data demonstrated that DG inhibited the occurrence of lipid accumulation and the inflammatory response via the HMGB1-TLR4 axis, underscoring a promising approach and utility of DG for the treatment of ALD.