Inhibited High Mobility Group Box 1 Release Research Articles

MP60-01 MACROPHAGE MIGRATION INHIBITORY FACTOR AND TLR4 SIGNALING ARE INVOLVED IN PAR4-INDUCED PERSISTENT BLADDER PAIN

You have accessJournal of UrologyCME1 Apr 2023MP60-01 MACROPHAGE MIGRATION INHIBITORY FACTOR AND TLR4 SIGNALING ARE INVOLVED IN PAR4-INDUCED PERSISTENT BLADDER PAIN Shaojing Ye, Fei Ma, Dlovan F. D. Mahmood, and Pedro Vera Shaojing YeShaojing Ye More articles by this author , Fei MaFei Ma More articles by this author , Dlovan F. D. MahmoodDlovan F. D. Mahmood More articles by this author , and Pedro VeraPedro Vera More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003318.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Interstitial cystitis/Bladder pain syndrome is a painful condition with unknown etiology. Repeated intravesical PAR4 induced persistent bladder hyperalgesia (BHA) in mice that lasts several days after the last stimulus with little or no evidence of bladder inflammation. Our studies showed that spinal macrophage migration inhibitory factor (MIF) and High Mobility Group Box 1 (HMGB1) are critical causative factors. We aimed to dissect this persistent pain pathway and explore effective targets for treating persistent bladder pain. METHODS: Persistent BHA was induced in female mice (WT, TLR4 null, Trif null) by three intravesical instillations (days 0, 2 and 4) with PAR4 agonist (100 uM; 1hr, scrambled peptide as control) under anesthesia. Lower abdominal hypersensitivity was measured by von Frey filaments on days 0-4 and 7-9. Intraperitoneal treatment was performed on days 2-8 and included: ISO-1 (MIF antagonist); 10% DMSO; ethyl pyruvate (EP; inhibits HMGB1 release); and PBS. Awake micturition parameters (voided volume; frequency) were assessed on day 9. Bladder histology assessed inflammation/edema. R was used for all analyses. RESULTS: Inhibition of MIF activity with ISO-1 robustly reversed the PAR4-induced persistent BHA in WT mice (Figure 1A) while treatment with EP partially reduced BHA (Figure 1B). TLR4 deficiency substantially damped persistent pain (Figure 2A) while lack of Trif did not affect PAR4-induced persistent BHA (Figure 2B). No significant effects were noted on micturition volume, frequency, inflammation, or edema. CONCLUSIONS: MIF, HMGB1, and TLR4 signaling activation are required for PAR4-induced persistent BHA. However, Trif may not be critical for persistent bladder pain. Further dissecting TLR4 downstream signaling pathway is necessary to identify important mediators and whether they act centrally or peripherally. This may lead to the discovery of novel potential therapeutic targets to treat persistent bladder pain. Source of Funding: DK121695 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e842 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shaojing Ye More articles by this author Fei Ma More articles by this author Dlovan F. D. Mahmood More articles by this author Pedro Vera More articles by this author Expand All Advertisement PDF downloadLoading ...

Treatment of Marmoset Intracerebral Hemorrhage with Humanized Anti-HMGB1 mAb.

Intracerebral hemorrhage (ICH) is recognized as a severe clinical problem lacking effective treatment. High mobility group box-1 (HMGB1) exhibits inflammatory cytokine-like activity once released into the extracellular space from the nuclei. We previously demonstrated that intravenous injection of rat anti-HMGB1 monoclonal antibody (mAb) remarkably ameliorated brain injury in a rat ICH model. Therefore, we developed a humanized anti-HMGB1 mAb (OKY001) for clinical use. The present study examined whether and how the humanized anti-HMGB1 mAb ameliorates ICH injury in common marmosets. The results show that administration of humanized anti-HMGB1 mAb inhibited HMGB1 release from the brain into plasma, in association with a decrease of 4-hydroxynonenal (4-HNE) accumulation and a decrease in cerebral iron deposition. In addition, humanized anti-HMGB1 mAb treatment resulted in a reduction in brain injury volume at 12 d after ICH induction. Our in vitro experiment showed that recombinant HMGB1 inhibited hemoglobin uptake by macrophages through CD163 in the presence of haptoglobin, suggesting that the release of excess HMGB1 from the brain may induce a delay in hemoglobin scavenging, thereby allowing the toxic effects of hemoglobin, heme, and Fe2+ to persist. Finally, humanized anti-HMGB1 mAb reduced body weight loss and improved behavioral performance after ICH. Taken together, these results suggest that intravenous injection of humanized anti-HMGB1 mAb has potential as a novel therapeutic strategy for ICH.

Extracellular HMGB1 as Inflammatory Mediator in the Progression of Mycoplasma Gallisepticum Infection.

High-mobility group box 1 (HMGB1), a member of damage-associated molecular patterns (DAMPs), is involved in the immune regulation of several infectious diseases. Mycoplasma gallisepticum (MG) infection is proved to cause an abnormal immune response, but the role of HMGB1 in MG-induced chronic respiratory disease (CRD) is unclear. In this study, we found that HMGB1 was released from the nucleus to the extracellular in macrophages upon infection with MG. Extracellular HMGB1 bound to TLR2 activating the NF-κB pathway triggering a severe inflammatory storm and promoting the progression of MG infection. More importantly, TLR4 could be activated by HMGB1 to trigger immune disorders after TLR2 was silenced. This disease process could be interrupted by ethyl pyruvate (EP) inhibition of HMGB1 release or glycyrrhizic acid (GA). Furthermore, treatment of MG-infected chickens with GA significantly alleviated immune organ damage. In conclusion, we demonstrate that HMGB1 is secreted extracellularly to form an inflammatory environment upon MG infection, triggering a further cellular inflammatory storm in a positive feedback approach. Blocking MG-induced HMGB1 release or suppression downstream of the HMGB1-TLR2/TLR4 axis may be a promising novel strategy for the treatment of CRD. Furthermore, this study may provide a theoretical reference for understanding non-LPS-activated TLR4 events.

Camel whey protein alleviates heat stress-induced liver injury by activating the Nrf2/HO-1 signaling pathway and inhibiting HMGB1 release.

This study aimed to investigate the mechanism by which camel whey protein (CWP) inhibits the release of high-mobility group box 1 (HMGB1) in heat stress (HS)-stimulated rat liver. Administration of CWP by gavage prior to HS inhibited the cytoplasmic translocation of HMGB1 and consequently reduced the inflammatory response in the rat liver, and downregulated the levels of the NLR pyrin domain containing 3 (NLRP3) inflammasome, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α. The use of N-acetyl-L-cysteine (NAC), an inhibitor of reactive oxygen species (ROS) production, indicated that this downregulation effect may be attributed to the antioxidant activity of CWP. We observed that CWP enhanced nuclear factor erythroid 2-related factor (Nrf)2 and heme-oxygenase (HO)-1 expression, which inhibited ROS production, nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity, and malondialdehyde (MDA) levels, and increased superoxide dismutase 1 (SOD1) activity and reduced glutathione (GSH) content in the HS-treated liver, ultimately increasing the total antioxidant capacity (TAC) in the liver. Administration of Nrf2 or HO-1 inhibitors before HS abolished the protective effects of CWP against oxidative damage in the liver of HS-treated rats, accompanied by increased levels of HMGB1 in the cytoplasm and IL-1β and TNF-α in the serum. In conclusion, our study demonstrated that CWP enhanced the TAC of the rat liver after HS by activating Nrf2/HO-1 signaling, which in turn reduced HMGB1 release from hepatocytes and the subsequent inflammatory response and damage. Furthermore, the combination of CWP and NAC abolished the adverse effects of HS in the rat liver. Therefore, dietary CWP could be an effective adjuvant treatment for HS-induced liver damage.

MP07-05 BLADDER OXIDATIVE STRESS AND ERK SIGNALING CONTRIBUTE TO BLADDER PAIN MEDIATED BY MACROPHAGE MIGRATION INHIBITORY FACTOR AND HIGH MOBILITY GROUP BOX 1

You have accessJournal of UrologyCME1 May 2022MP07-05 BLADDER OXIDATIVE STRESS AND ERK SIGNALING CONTRIBUTE TO BLADDER PAIN MEDIATED BY MACROPHAGE MIGRATION INHIBITORY FACTOR AND HIGH MOBILITY GROUP BOX 1 Shaojing Ye, Fei Ma, Dlovan Mahmood, Katherine Meyer-Siegler, Lin Leng, Richard Bucala, and Pedro Vera Shaojing YeShaojing Ye More articles by this author , Fei MaFei Ma More articles by this author , Dlovan MahmoodDlovan Mahmood More articles by this author , Katherine Meyer-SieglerKatherine Meyer-Siegler More articles by this author , Lin LengLin Leng More articles by this author , Richard BucalaRichard Bucala More articles by this author , and Pedro VeraPedro Vera More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002529.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Intravesical PAR4 induced bladder hyperalgesia (BHA) in mice through release of urothelial macrophage migration inhibitory factor (MIF) and High Mobility Group Box 1 (HMGB1). We aimed to confirm our observations using transgenic strains and examine downstream mechanisms at the level of the bladder involved in BHA. METHODS: BHA was induced in female mice with intravesical PAR4 (100 µM; 1hr; C57BL/6) or di-sulfide HMGB1 (dsHMGB1, 10 μg; 1hr; MIF knockout). Lower abdominal von Frey (VF) mechanical threshold (index of BHA) was measured before and 24 hr after treatment. Intravesical pre-treatments (10 min prior to PAR4 or dsHMGB1) included: PBS; ethyl pyruvate (EP; inhibiting HMGB1 release); N-acetylcysteine amide (NACA; ROS scavenger); FR180204 (FR; selective ERK1/2 inhibitor; methylcellulose as solvent); LY294002 (LY; PI3k inhibitor; DMSO as solvent). Awake micturition parameters (voided volume; frequency) were assessed 24 hr after treatment. Bladder histology assessed inflammation/edema. R was used for all analyses. RESULTS: Scrambled peptide did not induce BHA while intravesical PAR4 induced BHA in WT mice (Fig 1A). Pre-treatment with EP nearly blocked BHA (Fig 1B) while NACA significantly reduced it (Fig 1C) and FR had no effect (Fig 1D). PAR4 did not induce BHA in MIF KO mice (Fig 2A) while intravesical dsHMGB1 elicited BHA (Fig 2B). Pre-treatment with NACA (Fig 2B) and FR (Fig 2C) but not LY (Fig 2D) significantly prevented HMGB1-induced bladder pain in MIF KO mice. No significant effects were noted on micturition volume, frequency, inflammation, or edema. CONCLUSIONS: MIF mediates bladder pain through the release of intravesical (likely urothelial) HMGB1. Downstream of HMGB1, ROS production and ERK1/2 activation at the level of the bladder mediate bladder pain. Further dissecting HMGB1 downstream signaling pathway may lead to novel potential therapeutic strategies to treat non-inflammatory bladder pain. Source of Funding: DK121695 (PLV); AR049610 (RB) © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e116 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shaojing Ye More articles by this author Fei Ma More articles by this author Dlovan Mahmood More articles by this author Katherine Meyer-Siegler More articles by this author Lin Leng More articles by this author Richard Bucala More articles by this author Pedro Vera More articles by this author Expand All Advertisement PDF DownloadLoading ...

Anti-Septic Functions of Cornuside against HMGB1-Mediated Severe Inflammatory Responses.

High mobility group box 1 (HMGB1) is acknowledged to have critical functions; therefore, targeting this protein may have therapeutic effects. One example is potential antiseptic activity obtained by suppressing HMGB1 secretion, leading to the recovery of vascular barrier integrity. Cornuside (CN), which is a product extracted from the fruit of Cornus officinalis Seib, is a natural bis-iridoid glycoside with the therapeutic effects of suppressing inflammation and regulating immune responses. However, the mechanism of action of CN and impact on sepsis is still unclear. We examined if CN could suppress HMGB1-induced excessive permeability and if the reduction of HMGB1 in response to LPS treatment increased the survival rate in a mouse model of sepsis. In human endothelial cells stimulated by LPS and mice with septic symptoms of cecal ligation and puncture (CLP), we examined levels of proinflammatory proteins and biomarkers as an index of tissue damage, along with decreased vascular permeability. In both LPS-treated human umbilical vein endothelial cells (HUVECs) and the CLP-treated mouse model of sepsis, we applied CN after the induction processes were over. CN suppressed excessive permeability and inhibited HMGB1 release, leading to the amelioration of vascular instability, reduced mortality, and improved histological conditions in the CLP-induced septic mouse model. Overall, we conclude that the suppressed release of HMGB1 and the increased survival rate of mice with CLP-induced sepsis caused by CN may be an effective pharmaceutical treatment for sepsis.

Heme oxygenase-1 gene delivery for altering high mobility group box-1 protein in pancreatic islet

Pancreatic islet transplantation is a promising strategy for the treatment of type I diabetes. High-mobility group box-1 (HMGB1), highly expressed in islet cells, is a potent immune stimulator in immune rejection. Heme oxygenase-1 (HO1) gene therapy can modulate the release of HMGB1 by altering intracellular molecules for successful cell transplantation. After delivery of the heme oxygenase-1 (HO1) gene to islet cells using an adeno-associated viral vector (AAV), it was evaluated the changes in cytoplasmic Ca2+ ions and calcineurin activity as well as histone acetyltransferase (HAT) and Poly(ADP) ribose polymerase-1 (PARP-1). Inhibition of HMGB1 release was evaluated through altering these intracellular molecules. Then, after transplantation of HO1-transduced islets, the therapeutic effect of them was evaluated through measuring blood glucose level to diabetic mice and through immunohistochemical analysis. The transduced HO1 gene significantly inhibited HMGB1 release in islets that was under the cell damage by hypoxia exposure. It was confirmed that this result was initially due to the decrease in cytoplasmic Ca2+ ion concentration and calcineurin activity. In addition, the delivered HO1 gene simultaneously reduced the activity of HAT and PARP-1, which are involved in the translocation of HMGB1 from the nucleus to the cytoplasm. As a result, when the HO1 gene-transduced islets were transplanted into diabetic mice, the treatment efficiency of diabetes was effectively improved by increasing the survival rate of the islets. Collectively, these results suggest that HO1 gene transfer can be used for successful islet transplantation by altering the activity of intracellular signal molecules and reducing HMGB1 release.

TLR4-Dependent DUOX2 Activation Triggered Oxidative Stress and Promoted HMGB1 Release in Dry Eye.

Dry eye disease (DED) is one of the most common ocular surface diseases worldwide. DED has been characterized by excessive accumulation of reactive oxygen species (ROS), following significant corneal epithelial cell death and ocular surface inflammation. However, the key regulatory factor remains unclear. In this study, we tended to explore whether DUOX2 contributed to DED development and the underlying mechanism. Human corneal epithelial (HCE) cells were treated with hyperosmolarity, C57BL/6 mice were injected of subcutaneous scopolamine to imitate DED. Expression of mRNA was investigated by RNA sequencing (RNA-seq) and quantitative real-time PCR (qPCR). Protein changes and distribution of DUOX2, high mobility group box 1 (HMGB1), Toll-like receptor 4 (TLR4), and 4-hydroxynonenal (4-HNE) were evaluated by western blot assays and immunofluorescence. Cell death was assessed by Cell Counting Kit-8 (CCK8), lactate dehydrogenase (LDH) release, and propidium iodide (PI) staining. Cellular ROS levels and mitochondrial membrane potential (MMP) were analyzed by flow cytometry. RNA-seq and western blot assay indicated a significant increase of DUOX2 dependent of TLR4 activation in DED both in vitro and in vivo. Immunofluorescence revealed significant translocation of HMGB1 within corneal epithelial cells under hyperosmolar stress. Interestingly, after ablated DUOX2 expression by siRNA, we found a remarkable decrease of ROS level and recovered MMP in HCE cells. Moreover, knockdown of DUOX2 greatly inhibited HMGB1 release, protected cell viability and abolished inflammatory activation. Taken together, our data here suggest that upregulation of DUOX2 plays a crucial role in ROS production, thereafter, induce HMGB1 release and cell death, which triggers ocular surface inflammation in DED.

Suppressive activity of RGX-365 on HMGB1-mediated septic responses

RGX-365 is the main fraction of black ginseng conmprising protopanaxatriol (PPT)-type rare ginsenosides (ginsenosides Rg4, Rg6, Rh4, Rh1, and Rg2). No studies on the antiseptic activity of RGX-365 have been reported. High mobility group box 1 (HMGB1) is recognized as a late mediator of sepsis, and the inhibition of HMGB1 release and recovery of vascular barrier integrity have emerged as attractive therapeutic strategies for the management of sepsis. In this study, we examined the effects of RGX-365 on HMGB1-mediated septic responses and survival rate in a mouse sepsis model. RGX-365 was administered to the mice after HMGB1 challenge. The antiseptic activity of RGX-365 was assessed based on the production of HMGB1, measurement of permeability, and septic mouse mortality using a cecal ligation and puncture (CLP)-induced sepsis mouse model and HMGB1-activated human umbilical vein endothelial cells (HUVECs). We found that RGX-365 significantly reduced HMGB1 release from LPS- activated HUVECs and CLP-induced release of HMGB1 in mice. RGX-365 also restored HMGB1-mediated vascular disruption and inhibited hyperpermeability in the mice. In addition, treatment with RGX-365 reduced sepsis-related mortality in vivo. Our results suggest that RGX- 365 reduces HMGB1 release and septic mortality in vivo, indicating that it is useful in the treatment of sepsis.

Biapenem reduces sepsis mortality via barrier protective pathways against HMGB1-mediated septic responses.

As a late mediator of sepsis, the role of high mobility group box 1 (HMGB1) has been recognized as important, and suppression of HMGB1 release and restoration of vascular barrier integrity are regarded as potentially promising therapeutic strategies for sepsis. For repositioning of previously FDA-approved drugs to develop new therapies for human diseases, screening of chemical compound libraries, biological active, is an efficient method. Our study illustrates an example of drug repositioning of Biapenem (BIPM), a carbapenem antibiotic, for the modulation of HMGB1-induced septic responses. We tested our hypothesis that BIPM inhibits HMGB1-induced vascular hyperpermeability and thereby increases the survival of septic mouse model from suppression of HMGB1 release upon lipopolysaccharide (LPS)-stimulation. In LPS-activated human umbilical vein endothelial cells (HUVECs) and a cecal ligation and puncture (CLP)-induced sepsis mouse model, antiseptic activity of BIPM was investigated from suppression of vascular permeability, pro-inflammatory proteins, and markers for tissue injury. BIPM significantly suppressed release of HMGB1 both in LPS-activated HUVECs (upto 60%) and the CLP-induced sepsis mouse model (upto 54%). BIPM inhibited hyperpermeability (upto 59%) and reduced HMGB1-mediated vascular disruptions (upto 62%), mortality (upto 50%), and also tissue injury including lung, liver, and kidney in mice. Reduction of HMGB1 release and septic mortality by BIPM (in vitro, from 5 to 15μM for 6h; in vivo, from 0.37 to 1.1mg/kg, 24h) indicate a possibility of successful repositioning of BIPM for the treatment of sepsis.

Targeted temperature management at 33°C or 36℃ induces equivalent myocardial protection by inhibiting HMGB1 release in myocardial ischemia/reperfusion injury.

Acute myocardial infarction (AMI) is lethal and causes myocardial necrosis via time-dependent ischemia due to prolonged occlusion of the infarct-related artery. No effective therapy or potential therapeutic targets can prevent myocardial ischemia/reperfusion (I/R) injury. Targeted temperature management (TTM) may reduce peri-infarct regions by inhibiting the extracellular release of high mobility group box-1 (HMGB1) as a primary mediator of the innate immune response. We used a rat left anterior descending (LAD) coronary artery ligation model to determine if TTM at 33°C and 36°C had similar myocardial protective effects. Rats were divided into sham, LAD I/R+37°C normothermia, LAD I/R+33°C TTM, and LAD I/R+36°C TTM groups (n = 5 per group). To verify the cardioprotective effect of TTM by specifically inhibiting HMGB1, rats were assigned to sham, LAD I/R, and LAD I/R after pre-treatment with glycyrrhizin (known as a pharmacological inhibitor of HMGB1) groups (n = 5 per group). Different target temperatures of 33°C and 36°C caused equivalent reductions in infarct volume after myocardial I/R, inhibited the extracellular release of HMGB1 from infarct tissue, and suppressed the expression of inflammatory cytokines from peri-infarct regions. TTM at 33°C and 36°C significantly attenuated the elevation of cardiac troponin, a sensitive and specific marker of heart muscle damage, after injury. Similarly, glycyrrhizin alleviated myocardial damage by suppressing the extracellular release of HMGB1. TTM at 33°C and 36°C had equivalent myocardial protective effects by similar inhibiting HMGB1 release against myocardial I/R injury. This is the first study to suggest that a target core temperature of 36°C is applicable for cardioprotection.

Barrier protective functions of hederacolchiside-E against HMGB1-mediated septic responses

The role of high mobility group box 1 (HMGB1) has been recognized as important, and suppression of HMGB1 release and restoration of vascular barrier integrity are regarded as potentially promising therapeutic strategies against sepsis. Hederacolchiside-E (HCE), namely 3-O-{α-L-rhamnopyranosyl (1→2)-[β-D-glucopyranosyl(1→4)]-α-L-arabinopyranosyl}-28-O-[α-L-rhamnopyranosyl (1→4)-β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl ester, is a bidesmosidic oleanane saponin first isolated in 1970 from the leaves of Hedera colchica. We tested our hypothesis that HCE inhibits HMGB1-induced vascular hyperpermeability and thereby increases the survival of septic mouse model from suppression of HMGB1 release upon lipopolysaccharide (LPS)-stimulation. In LPS-activated human endothelial cells and a sepsis mouse model by cecal ligation and puncture (CLP), antiseptic activity of HCE was investigated from suppression of vascular permeability, pro-inflammatory proteins, and tissue injury markers. Post-treatment of HCE significantly suppressed HMGB1 release both in LPS-activated human endothelial cells and the CLP-induced sepsis mouse model. HCE inhibited hyperpermeability and alleviated HMGB1-mediated vascular disruptions, and reduced sepsis-related mortality and tissue injury in mice. Our results suggest that reduction of HMGB1 release and septic mortality by HCE may be useful for the drug candidate of sepsis, indicating a possibility of successful repositioning of HCE.

Effect of Metformin on Development of Tendinopathy Due to Mechanical Overloading in an Animal Model.

Tendinopathy is a debilitating tendon disorder that affects millions of Americans and costs billions of health care dollars every year. High mobility group box 1 (HMGB1), a known tissue damage signaling molecule, has been identified as a mediator in the development of tendinopathy due to mechanical overloading of tendons in mice. Metformin (Met), a drug approved by the Food and Drug Administration used for the treatment of type 2 diabetes, specifically inhibits HMGB1. This study tested the hypothesis that Met would prevent mechanical overloading-induced tendinopathy in a mouse model of tendinopathy created by intensive treadmill running (ITR). C57BL/6J mice (female, 3 months old) were equally separated into 4 groups and treated for 24 weeks as follows: group 1 had cage control activities, group 2 received a single intraperitoneal injection of Met (50 mg/kg body weight) daily, group 3 underwent ITR to induce tendinopathy, and group 4 received daily Met injection along with ITR to inhibit HMGB1. Tendinopathic changes were assessed in Achilles tendons of all mice using histology, immunohistochemistry, and enzyme-linked immunosorbent assays. ITR induced HMGB1 release into the tendon matrix and developed characteristics of tendinopathy as evidenced by the expression of macrophage marker CD68, proinflammatory molecules (COX-2, PGE2), cell morphological changes from normal elongated cells to round cells, high levels of expression of chondrogenic markers (SOX-9, collagen type II), and accumulation of proteoglycans in tendinopathic tendons. Daily injection of Met inhibited HMGB1 release and decreased these degenerative changes in ITR tendons. Inhibition of HMGB1 by injections of Met prevented tendinopathy development due to mechanical overloading in the Achilles tendon in mice. Met may be able to be repurposed as a therapeutic option for preventing the development of tendinopathy in high-risk patients.

2020 J. Leonard Goldner Award Winner: Inhibition of HMGB1 by Metformin Prevents Mechanical Overloading-Induced Tendinopathy

Category:Basic Sciences/Biologics; SportsIntroduction/Purpose:Tendinopathy is a debilitating tendon disorder that affects millions of Americans and costs billions of healthcare dollars every year. Mechanical overloading is considered to cause the development of tendinopathy, but the underlying molecular mechanisms of tendinopathy remain unclear. High mobility group box-1 (HMGB1), an upstream potent inflammatory mediator, has been identified in high levels in early stage tendinopathy patients [1]. However, whether HMGB1 mediates tendinopathy development due to mechanical overloading is completely unknown. Metformin (Met), a hypoglycemic drug commonly used for the treatment of type II diabetes, has shown to inhibit the activity of HMGB1 via binding the acidic tail of HMGB1 [2]. In this study, we tested the hypothesis that Met prevents mechanical overloading-induced tendinopathy by inhibiting HMGB1.Methods:A total of 24 mice were divided into 4 groups and treated for 24 weeks as follows: Group 1 (Cage) with cage activities; Group 2 (Met) received daily IP injection of metformin (50 mg/kg body weight); Group 3 (ITR) ran on treadmill at 15 meters/min for 3 h/ day, 5 days a week; Group 4 (ITR+Met) ran the same protocol as that of ITR group but with daily IP injection of metformin. Six mice/group were sacrificed at 24 weeks and the Achilles and patellar tendon tissues were harvested. The tendons from the left legs were used for histochemical staining and the right for immunostaining.Results:We found that mechanical overloading induced HMGB1 release into tendon matrix (Fig. 1G, K, O). Metformin inhibited HMGB1 release (Fig. 1H, L, P). ITR induced degenerative tendinopathy as evidenced by the cell morphological changes from elongated shape in normal tendon (Fig. 2A, E, I, M) to round shape (Fig. 2C, G, K, O) and the accumulation of proteoglycans (Fig. 2K, O) in ITR tendon. Metformin injection inhibited ITR effect, which is shown by less round shaped cells and low proteoglycan levels found in metformin injected ITR tendons (Fig. 2D, H, L, P). ITR promoted the expression of chondrogenic markers (collagen II and SOX-9) in tendon (Fig. 3C, G, K, O), and metformin inhibited the expression of chondrogenic makers (Fig. 3D, H, L, P).Conclusion:Our study demonstrated that mechanical overloading induced degenerative changes in mouse tendons characterized by the presence of chondrocyte-like cells, accumulation of proteoglycans, high levels of chondrogenic marker SOX-9 and Collagen II expression. Administration of metformint reduced the degenerative responses in overloaded tendon and blocked the development of tendinopathy. These findings support the notion that mechanical overloading induces tendinopathy development by initiation of tendon inflammation via HMGB1, which leads to eventual tendon degeneration. Thus, metformin, a commonly prescribed and FDA approved drug that specifically inhibits HMGB1, can be used to prevent tendinopathy development due to mechanical overloading placed on the tendon.

Baicalin Ameliorates Cognitive Impairment and Protects Microglia from LPS-Induced Neuroinflammation via the SIRT1/HMGB1 Pathway.

Systemic inflammation often induces neuroinflammation and disrupts neural functions, ultimately causing cognitive impairment. Furthermore, neuronal inflammation is the key cause of many neurological conditions. It is particularly important to develop effective neuroprotectants to prevent and control inflammatory brain diseases. Baicalin (BAI) has a wide variety of potent neuroprotective and cognitive enhancement properties in various models of neuronal injury through antioxidation, anti-inflammation, anti-apoptosis, and stimulating neurogenesis. Nevertheless, it remains unclear whether BAI can resolve neuroinflammation and cognitive decline triggered by systemic or distant inflammatory processes. In the present study, intraperitoneal lipopolysaccharide (LPS) administration was used to establish neuroinflammation to evaluate the potential neuroprotective and anti-inflammatory effects of BAI. Here, we report that BAI activated silent information regulator 1 (SIRT1) to deacetylate high-mobility group box 1 (HMGB1) protein in response to acute LPS-induced neuroinflammation and cognitive deficits. Furthermore, we demonstrated the anti-inflammatory and cognitive enhancement effects and the underlying molecular mechanisms of BAI in modulating microglial activation and systemic cytokine production, including tumor necrosis factor- (TNF-) α and interleukin- (IL-) 1β, after LPS exposure in mice and in the microglial cell line, BV2. In the hippocampus, BAI not only reduced reactive microglia and inflammatory cytokine production but also modulated SIRT1/HMGB1 signaling in microglia. Interestingly, pretreatment with SIRT1 inhibitor EX-527 abolished the beneficial effects of BAI against LPS exposure. Specifically, BAI treatment inhibited HMGB1 release via the SIRT1/HMGB1 pathway and reduced the nuclear translocation of HMGB1 in LPS-induced BV2 cells. These effects were reversed in BV2 cells by silencing endogenous SIRT1. Taken together, these findings indicated that BAI reduced microglia-associated neuroinflammation and improved acute neurocognitive deficits in LPS-induced mice via SIRT1-dependent downregulation of HMGB1, suggesting a possible novel protection against acute neurobehavioral deficits, such as delayed neurocognitive recovery after anesthesia and surgery challenges.

Inhibitory Functions of Novel Compounds from Dioscorea batatas Decne Peel on HMGB1-mediated Septic Responses

Inhibition of high mobility group box 1 (HMGB1) signaling and restoration of endothelial integrity are emerging as promising therapeutic strategies for managing severe vascular inflammatory diseases. Dioscorea batatas Decne (DBD, Chinese yam), a perennial plant which belongs to Dioscoreaceae, is widely cultivated across Korea, Japan, China, and other tropical and subtropical regions, and both the aerial parts and roots of this plant are used for food and medicinal purposes. Here, we determined the effects of the two phenanthrene compounds from DBD peel, 2,7-dihydroxy-4,6-dimethoxyphenanthrene (1) and 6,7-dihydroxy-2,4-dimethoxyphenanthrene (2), on HMGB1-mediated septic responses and survival rate in cecal ligation and puncture (CLP)-induced septic model. The anti-inflammatory activities of compounds 1 and 2 were monitored by lipopolysaccharide (LPS)- or CLP-induced release of HMGB1. The anti-septic activities of compounds 1 and 2 were determined by measuring permeability, leukocyte adhesion and migration, and pro-inflammatory protein activation in HMGB1-activated human umbilical vein endothelial cells (HUVECs) and mice. Compounds 1 and 2 inhibited HMGB1 release and downregulated HMGB1-mediated inflammatory responses in HUVECs. Compounds 1 and 2 also inhibited HMGB1-induced hyperpermeability and leukocyte migration in mice. Additionally, treatment with compounds 1 and 2 reduced CLP-induced HMGB1 release and sepsis-related mortality and pulmonary damage in vivo. Our results indicate that the compounds 1 and 2 are potential therapeutic agents for treating severe vascular inflammatory diseases via HMGB1 signaling pathway inhibition.

Histidine-Rich Glycoprotein Inhibits High Mobility Group Box 1-Mediated Pathways in Vascular Endothelial Cells

Background: High mobility group box-1 (HMGB1) protein has been postulated to play a pathogenic role in severe sepsis. Histidine-rich glycoprotein (HRG) was proposed as a new biomarker to predict the outcome of sepsis patients and demonstrated to improve survival rate and relieve symptom of septic mice. However, its effect on HMGB1 signaling has never been investigated. Our research focuses on the effects of HRG on HMGB1 mobilization and HMGB1-mediated pathway in endothelial cells and the involvement of specific receptors for HRG. Methods: A variety of biochemical assays were applied to explore the effects of HRG on HMGB1 release and HMGB1-mediated signal pathway in EA.hy 926 endothelial cells. The receptor for HRG was identified using co-immunoprecipitation experiments and surface plasmon resonance analysis. Findings: HRG potently inhibited the LPS-induced translocation and release of HMGB1 and effectively suppressed rHMGB1-induced ICAM-1 and VCAM-1 expression, inflammatory cytokines secretion and NF-κB activation in EA.hy 926 endothelial cells. HRG also inhibited HMGB1 release and HMGB1-mediated inflammatory responses in LPS-injected mice. Moreover, we first clarified that these protective effects of HRG on endothelial cells were mediated through C-type lectin domain family 1 member A (CLEC-1A) receptor. Interpretation: The present findings strongly support the supplementary therapy with HRG in sepsis and will provide the new insights into the understanding of the functional role of CLEC1A in the maintenance of vascular endothelial cells. Funding Statement: This research was supported by grants from AMED (no. 18im0210109h0002) and from the Secom Science and Technology Foundation to M.N., a Grant-in-Aid for Scientific Research (no.15H04686 to M.N.), a Grant-in-Aid for Young Scientists (no. 17K15580 to H.W.), and a Grant-in-Aid for Scientific Research (no. 16K08232 to K.T.) from the Japan Society for the Promotion of Science (JSPS). The author S.G. was supported by the scholarship from China Scholarship Council. Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: Human neutrophils were isolated from peripheral blood obtained from healthy volunteers in accordance with ethics approval and guidelines of Okayama University and the Declaration of Helsinki. All animal experiments were approved by the university's committee and performed according to the guidelines of Okayama University on animal experiments.

Propofol Protects Lung Endothelial Barrier Function by Suppression of High-Mobility Group Box 1 (HMGB1) Release and Mitochondrial Oxidative Damage Catalyzed by HMGB1.

BackgroundThe processes of mechanical ventilation-induced lung injury (VILI) triggers the release of high-mobility group box 1 (HMGB1), a prominent damage-associated molecular pattern (DAMP) family member, which can cause damage to pulmonary vascular endothelial cells. We aimed to determine whether propofol protected against endothelial cell injury induced by HMGB1 in vitro and in vivo.Material/MethodsICR mice (male) were mechanically ventilated for 4 h after anesthetization at both low tidal volume (LVT, 6 ml/kg) and high tidal volume (HVT, 30 ml/kg). A propofol bolus (10 mg/kg) was administered to the animals prior to the onset of ventilation, followed by infusion at 5 mg/(kg·h). We obtained confluent cultures of mouse lung vascular endothelial cells (MLVECs) and then performed cyclic stretching at 20% stretch for 4 h with or without propofol.ResultsHMGB1 reduced the expression of tight junctions between endothelial cells, including VE-cadherin and ZO-1, and increased endothelial permeability, and both were blocked by propofol. We found that MLVECs exhibited mitochondrial oxidative damage by HMGB1, which was successfully suppressed through administration of MnTBAP as well as propofol. Propofol ameliorated HVT-associated lung vascular hyperpermeability and HMGB1 production in vivo. Propofol also inhibited HMBG1 release caused by cyclic stretching in MLVECs in vitro.ConclusionsOur results prove that the cyto-protective function of propofol protects against lung ventilation-induced dysfunction of the lung endothelial barrier. This function of propofol is mediated through inhibition of HMGB1 release caused by mechanical stretching and mitochondrial oxidative damage triggered by HMGB1.

The molecular mechanisms of Aloin induce gastric cancer cells apoptosis by targeting High Mobility Group Box 1.

Purpose: Aloin (ALO), a bioactive ingredient extracted from aloe vera, has anti-tumor effects. High Mobility Group Box 1 (HMGB1), a highly conserved nuclear DNA-binding protein, has been implicated in various cancer types. Highly expressed HMGB1 is closely associated with tumor cells apoptosis, proliferation and migration. We investigated the specific molecular mechanisms by which ALO-induced apoptosis by targeting HMGB1 in gastric cancer cells.Materials and methods: Human gastric cancer HGC-27 cells were treated with different doses of ALO (100, 200 and 400 µg/ml) for 24 h, after which DAPI staining was used to observe the nuclear morphology, Annexin V/PI double staining assay was used to determine the rate of apoptosis; Western blotting was used to detect the levels of PARP, pro-caspase3, HMGB1 and RAGE; nuclear translocation of HMGB1 was determined by conducting a nucleoplasm separation experiment. The Enzyme linked immunosorbent assay (ELISA) assay was used to detect release of HMGB1. The HGC-27 cells, transfected with HMGB1 shRNA plasmids, were stimulated with ALO for 24 h, after which a flow cytometry assay was used to detect the rate of apoptosis. HGC-27 cells were pre-treated with or without ALO and then stimulated with rhHMGB1, the phosphorylation of Akt, mTOR, P70S6K, S6, 4EBP1, ERK, P90RSK, cAMP regulatory element binding (CREB) were detected by Western blotting.Results: After different doses of ALO treatment, the nuclei showed morphological changes characteristic of apoptosis. Apoptotic rates were enhanced in a dose dependent manner. The level of cleaved PARP was enhanced and pro-caspase3, HMGB1 and RAGE levels were reduced, HMGB1 nuclear translocation and release were inhibited. The activation of rhHMGB1-induced Akt-mTOR-P70S6K and ERK-CREB signalling pathways was inhibited by ALO. Blocking these signalling pathways by special inhibitors and HMGB1 knockdown could enhance ALO-induced HGC-27 cell apoptosis.Conclusion: ALO- induced HGC-27 cell apoptosis by down-regulating expressions of HMGB1 and RAGE, inhibiting HMGB1 release and then suppressing rhHMGB1-induced activation of Akt-mTOR-P70S6K and ERK-P90RSK-CREB signalling pathways.

HMGB1 mediated autophagy protects glioblastoma cells from carbon-ion beam irradiation injury

The present study investigated autophagy changes and the expression of HMGB1 in human glioblastoma cells, responding to carbon-ion beam irradiation (35 keV/μm, 80.55 MeV/u). U251 cells were irradiated with carbon-ion beams and cell proliferation was measured by counting the number of living cells. The expression of Light Chain 3 beta (LC3B), Beclin 1, high-mobility-group box 1 (HMGB1), pro-form caspase-3 and Cellular FLICE-like inhibitory protein (c-FLIP) was analyzed by western blotting. Caspase enzyme activity was determined via a caspase cleavage based florescent substrate commercial Kit. Living cell counting demonstrated a time- and dose-dependent cell death in U251 cells. The expression of LC3B and Beclin 1 revealed that, a high level of autophagy was induced 24 h after irradiation with 1 Gy carbon ions and then decreased in a time- and dose-dependent manner. The expression of the whole HMGB1 showed a well correlation with the dynamic autophagic level. Cytoplasmic HMGB1 maintained autophagy was concluded. Enzyme-Linked Immuno Sorbent Assay (ELISA) measurement found that, HMGB1 was released into the extracellular space in a time- and dose-dependent manner. Lower intracellular HMGB1 levels correlated with decreased autophagy as measured by the expression of LC3B. Decreased expression of pro-form caspase-3 and c-FLIP as well as the increased caspase enzyme activity indicated that apoptosis was induced by carbon-ion beam irradiation. Inhibition of HMGB1 release from the area of intracellular to that of extracellular significantly increased cell survival. In summary, carbon-ion beam irradiation could elevate autophagy and HMGB1 expression efficiently, which would protect the cells from programmed cell death via inducing autophagy. Apoptosis as measured by expression of caspase activities increased as the dose increased, which was accompanied with decreased levels of LC3B and HMGB1.