High Mobility Group Box-1 (HMGb1): Current Wisdom and Advancement as a Potential Drug Target

Probing the interactions of genistein with HMGB1 through multi-spectroscopic and in-silico approaches

Functional regulation of proteins by ligand-protein interactions plays a crucial role in understanding biological processes and identifying potential drugs. High mobility group box 1 (HMGB1) plays a pivotal role in sterile inflammation as a key immunomodulatory protein. Genistein, a well-known isoflavone compound, has been shown to have neuroprotective effects. In this study, we investigated the genistein-HMGB1 interactions using experimental and computational approaches. Our results revealed that genistein binds to HMGB1 with a KD value of 6.06 × 10-5 M. The addition of genistein significantly quenched the fluorescence of HMGB1. Thermodynamic analyses demonstrated that hydrogen bonds and hydrophobic forces are the primary forces during the binding process. Furthermore, the interaction between genistein and HMGB1 led to changes in the microenvironment of protein chromogenic amino acids and subtle alterations in the protein secondary structure. Molecular modeling results indicate that Pro95, Pro98, and Lys154 are the major amino acid residues for genistein binding to HMGB1. Meanwhile, at the cellular level, an inhibitory effect of genistein on HMGB1-induced NO release from microglia was observed, demonstrating an inhibition rate of 42.1 %. Our studies demonstrated that genistein could be applied in treating neurological diseases through its interaction with HMGB1.

Targeting HMGB1 and Its Interaction with Receptors: Challenges and Future Directions

High mobility group box 1 (HMGB1) is a nonhistone chromatin protein predominantly located in the nucleus. However, under pathological conditions, HMGB1 can translocate from the nucleus to the cytoplasm and subsequently be released into the extracellular space through both active secretion and passive release mechanisms. The distinct cellular locations of HMGB1 facilitate its interaction with various endogenous and exogenous factors, allowing it to perform diverse functions across a range of diseases. This Perspective provides a comprehensive overview of the structure, release mechanisms, and multifaceted roles of HMGB1 in disease contexts. Furthermore, it introduces the development of both small molecule and macromolecule inhibitors targeting HMGB1 and its interaction with receptors. A detailed analysis of the predicted pockets is also presented, aiming to establish a foundation for the future design and development of HMGB1 inhibitors.

Ternary model structural complex of C5a, C5aR2, and β-arrestin1

Complement component fragment 5a (C5a) is one of the potent proinflammatory modulators of the complement system. C5a recruits two genomically related G protein-coupled receptors (GPCRs), like C5aR1 and C5aR2, constituting a binary complex. The C5a-C5aR1/C5aR2 binary complexes involve other transducer proteins like heterotrimeric G-proteins and β-arrestins to generate the fully active ternary complexes that trigger intracellular signaling through downstream effector molecules in tissues. In the absence of structural data, we had recently developed highly refined model structures of C5aR2 in its inactive (free), meta-active (complexed to the CT-peptide of C5a), and active (complexed to C5a) state embedded to a model palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer. Compared to C5aR1, C5aR2 is established as a noncanonical GPCR, as it recruits and signals through β-arrestins rather than G-proteins. Notably, structural understanding of the ternary complex involving C5a-C5aR2-β-arrestin is currently unknown. The current study has attempted to fill the gap by generating a highly refined, fully active ternary model structural complex of the C5a-C5aR2-β-arrestin1 embedded in a model POPC bilayer. The computational modeling, 500 ns molecular dynamics (MD) studies, and the principal component analysis (PCA), including the molecular mechanics Poisson-Boltzmann surface area (MM PBSA) based data presented in this study, provide an experimentally testable hypothesis about C5a-C5aR2-β-arrestin1 extendable to other such ternary systems. The model ternary complex of C5a-C5aR2-β-arrestin1 will further enrich the current structural understanding related to the interaction of β-arrestins with the C5a-C5aR2 system.Communicated by Ramaswamy H. Sarma.

Natural triterpenoid-aided identification of the druggable interface of HMGB1 occupied by TLR4

HMGB1 interacts with TLR4 to activate the inflammatory cascade response, contributing to the pathogenesis of endogenous tissue damage and infection. The immense importance of HMGB1-TLR4 interaction in the immune system has made its binding interface an area of significant interest. To map the binding interface of HMGB1 occupied by TLR4, triterpenoids that disrupt the HMGB1-TLR4 interaction and interfere with HMGB1-induced inflammation were developed. Using the unique triterpenoid PT-22 as a probe along with photoaffinity labeling and site-directed mutagenesis, we found that the binding interface of HMGB1 was responsible for the recognition of TLR4 located on the "L" shaped B-box with K114 as a crucial hot-spot residue. Amazingly, this highly conserved interaction surface overlapped with the antigen-recognition epitope of an anti-HMGB1 antibody. Our findings propose a novel strategy for better understanding the druggable interface of HMGB1 that interacts with TLR4 and provide insights for the rational design of HMGB1-TLR4 PPI inhibitors to fine tune immune responses.

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.

Serum high mobility group box 1 as a potential biomarker for the progression of kidney disease in patients with type 2 diabetes

Background

As a damage-associated molecular pattern protein, high mobility group box 1 (HMGB1) is associated with kidney and systemic inflammation. The predictive and therapeutic value of HMGB1 as a biomarker has been confirmed in various diseases. However, its value in diabetic kidney disease (DKD) remains unclear. Therefore, this study aimed to investigate the correlation between serum and urine HMGB1 levels and DKD progression.

Methods

We recruited 196 patients with type 2 diabetes mellitus (T2DM), including 109 with DKD and 87 T2DM patients without DKD. Additionally, 60 healthy participants without T2DM were also recruited as controls. Serum and urine samples were collected for HMGB1 analysis. Simultaneously, tumor necrosis factor receptor superfamily member 1A (TNFR-1) in serum and kidney injury molecule (KIM-1) in urine samples were evaluated for comparison.

Results

Serum and urine HMGB1 levels were significantly higher in patients with DKD than in patients with T2DM and healthy controls. Additionally, serum HMGB1 levels significantly and positively correlated with serum TNFR-1 (R 2 = 0.567, p<0.001) and urine KIM-1 levels (R 2 = 0.440, p<0.001), and urine HMGB1 has a similar correlation. In the population with T2DM, the risk of DKD progression increased with an increase in serum HMGB1 levels. Multivariate logistic regression analysis showed that elevated serum HMGB1 level was an independent risk factor for renal function progression in patients with DKD, and regression analysis did not change in the model corrected for multiple variables. The restricted cubic spline depicted a nonlinear relationship between serum HMGB1 and renal function progression in patients with DKD (p-nonlinear=0.007, p<0.001), and this positive effect remained consistent across subgroups.

Conclusion

Serum HMGB1 was significantly correlated with DKD and disease severity. When the HMGB1 level was ≥27 ng/ml, the risk of renal progression increased sharply, indicating that serum HMGB1 can be used as a potential biomarker for the diagnosis of DKD progression.

A Review of Proposed Mechanisms in Rheumatoid Arthritis and Therapeutic Strategies for the Disease

Rheumatoid arthritis (RA) is characterized by synovial edema, inflammation, bone and cartilage loss, and joint degradation. Patients experience swelling, stiffness, pain, limited joint movement, and decreased mobility as the condition worsens. RA treatment regimens often come with various side effects, including an increased risk of developing cancer and organ failure, potentially leading to mortality. However, researchers have proposed mechanistic hypotheses to explain the underlying causes of synovitis and joint damage in RA patients. This review article focuses on the role of synoviocytes and synoviocytes resembling fibroblasts in the RA synovium. Additionally, it explores the involvement of epigenetic regulatory systems, such as microRNA pathways, silent information regulator 1 (SIRT1), Peroxisome proliferatoractivated receptor-gamma coactivator (PGC1-α), and protein phosphatase 1A (PPM1A)/high mobility group box 1 (HMGB1) regulators. These mechanisms are believed to modulate the function of receptors, cytokines, and growth factors associated with RA. The review article includes data from preclinical and clinical trials that provide insights into potential treatment options for RA.

High Mobility Group Box 1 Protein: A Plausible Therapeutic Molecular Target in Parkinson's Disease

Parkinson's disease (PD) is a widespread neurodegenerative disorder that exerts a broad variety of detrimental effects on people's health. Accumulating evidence suggests that mitochondrial dysfunction, neuroinflammation, α-synuclein aggregation and autophagy dysfunction may all play a role in the development of PD. However, the molecular mechanisms behind these pathophysiological processes remain unknown. Currently, research in PD has focussed on high mobility group box 1 (HMGB1), and different laboratory approaches have shown promising outcomes to some level for blocking HMGB1. Given that HMGB1 regulates mitochondrial dysfunction, participates in neuroinflammation, and modulates autophagy and apoptosis, it is hypothesised that HMGB1 has significance in the onset of PD. In the current review, research targeting multiple roles of HMGB1 in PD pathology was integrated, and the issues that need future attention for targeted therapeutic approaches are mentioned.

Revealing the extracellular function of HMGB1 N-terminal region acetylation assisted by a protein semi-synthesis approach

HMGB1 (high-mobility group box 1) is a non-histone chromatin-associated protein that has been widely reported as a representative damage-associated molecular pattern (DAMP) and to play a pivotal role in the proinflammatory process once it is in an extracellular location. Accumulating evidence has shown that HMGB1 undergoes extensive post-translational modifications (PTMs) that actively regulate its conformation, localization, and intermolecular interactions. However, fully characterizing the functional implications of these PTMs has been challenging due to the difficulty in accessing homogeneous HMGB1 with site-specific PTMs of interest. In this study, we developed a streamlined protein semi-synthesis strategy via salicylaldehyde ester-mediated chemical ligations (Ser/Thr ligation and Cys/Pen ligation, STL/CPL). This methodology enabled us to generate a series of N-terminal region acetylated HMGB1 proteins. Further studies revealed that acetylation regulates HMGB1-heparin interaction and modulates HMGB1's stability against thrombin, representing a regulatory switch to control HMGB1's extracellular activity.

Temporal patterns of cytokine and injury biomarkers in hospitalized COVID-19 patients treated with methylprednisolone

Background

The novel coronavirus disease 2019 (COVID-19) presents with complex pathophysiological effects in various organ systems. Following the COVID-19, there are shifts in biomarker and cytokine equilibrium associated with altered physiological processes arising from viral damage or aggressive immunological response. We hypothesized that high daily dose methylprednisolone improved the injury biomarkers and serum cytokine profiles in COVID-19 patients.

Methods

Injury biomarker and cytokine analysis was performed on 50 SARS-Cov-2 negative controls and 101 hospitalized severe COVID-19 patients: 49 methylprednisolone-treated (MP group) and 52 placebo-treated serum samples. Samples from the treated groups collected on days D1 (pre-treatment) all the groups, D7 (2 days after ending therapy) and D14 were analyzed. Luminex assay quantified the biomarkers HMGB1, FABP3, myoglobin, troponin I and NTproBNP. Immune mediators (CXCL8, CCL2, CXCL9, CXCL10, TNF, IFN-γ, IL-17A, IL-12p70, IL-10, IL-6, IL-4, IL-2, and IL-1β) were quantified using cytometric bead array.

Results

At pretreatment, the two treatment groups were comparable demographically. At pre-treatment (D1), injury biomarkers (HMGB1, TnI, myoglobin and FABP3) were distinctly elevated. At D7, HMGB1 was significantly higher in the MP group (p=0.0448) compared to the placebo group, while HMGB1 in the placebo group diminished significantly by D14 (p=0.0115). Compared to healthy control samples, several immune mediators (IL-17A, IL-6, IL-10, MIG, MCP-1, and IP-10) were considerably elevated at baseline (all p≤0.05). At D7, MIG and IP-10 of the MP-group were significantly lower than in the placebo-group (p=0.0431, p=0.0069, respectively). Longitudinally, IL-2 (MP-group) and IL-17A (placebo-group) had increased significantly by D14. In placebo group, IL-2 and IL-17A continuously increased, as IL-12p70, IL-10 and IP-10 steadily decreased during follow-up. The MP treated group had IL-2, IFN-γ, IL-17A and IL-12p70 progressively increase while IL-1β and IL-10 gradually decreased towards D14. Moderate to strong positive correlations between chemokines and cytokines were observed on D7 and D14.

Conclusion

These findings suggest MP treatment could ameliorate levels of myoglobin and FABP3, but appeared to have no impact on HMGB1, TnI and NTproBNP. In addition, methylprednisolone relieves the COVID-19 induced inflammatory response by diminishing MIG and IP-10 levels. Overall, corticosteroid (methylprednisolone) use in COVID-19 management influences the immunological molecule and injury biomarker profile in COVID-19 patients.

HMGB1: a potential new target for tendinopathy treatment

Tendinopathy describes a complex pathology of the tendon characterized by abnormalities in the microstructure, composition, and cellularity of the tendon, leading to pain, limitation of activity and reduced function. Nevertheless, the mechanism of tendinopathy has not been fully elucidated, and the treatment of tendinopathy remains a challenge. High mobility group box 1 (HMGB1), a highly conserved and multifaceted nuclear protein, exerts multiple roles and high functional variability and is involved in many biological and pathological processes. In recent years, several studies have suggested that HMGB1 is associated with tendinopathy and may play a key role in the pathogenesis of tendinopathy. Therefore, this review summarizes the expression and distribution of HMGB1 in tendinopathy, focuses on the roles of HMGB1 and HMGB1-based potential mechanisms involved in tendinopathy, and finally summarizes the findings on HMGB1-based therapeutic approaches in tendinopathy, probably providing new insight into the mechanism and further potential therapeutic targets of tendinopathy.

The role of HMGB1 in COVID-19-induced cytokine storm and its potential therapeutic targets: A review

Hyperinflammation characterized by elevated proinflammatory cytokines known as 'cytokine storms' is the major cause of high severity and mortality seen in COVID-19 patients. The pathology behind the cytokine storms is currently unknown. Increased HMGB1 levels in serum/plasma of COVID-19 patients were reported by many studies, which positively correlated with the level of proinflammatory cytokines. Dead cells following SARS-CoV-2 infection might release a large amount of HMGB1 and RNA of SARS-CoV-2 into extracellular space. HMGB1 is a well-known inflammatory mediator. Additionally, extracellular HMGB1 might interact with SARS-CoV-2 RNA because of its high capability to bind with a wide variety of molecules including nucleic acids and could trigger massive proinflammatory immune responses. This review aimed to critically explore the many possible pathways by which HMGB1-SARS-CoV-2 RNA complexes mediate proinflammatory responses in COVID-19. The contribution of these pathways to impair host immune responses against SARS-CoV-2 infection leading to a cytokine storm was also evaluated. Moreover, since blocking the HMGB1-SARS-CoV-2 RNA interaction might have therapeutic value, some of the HMGB1 antagonists have been reviewed. The HMGB1- SARS-CoV-2 RNA complexes might trigger endocytosis via RAGE which is linked to lysosomal rupture, PRRs activation, and pyroptotic death. High levels of the proinflammatory cytokines produced might suppress many immune cells leading to uncontrolled viral infection and cell damage with more HMGB1 released. Altogether these mechanisms might initiate a proinflammatory cycle leading to a cytokine storm. HMGB1 antagonists could be considered to give benefit in alleviating cytokine storms and serve as a potential candidate for COVID-19 therapy.

Enzyme-Activatable Polypeptide for Plasma Membrane Disruption and Antitumor Immunity Elicitation

Enzyme-instructed self-assembly of bioactive molecules into nanobundles inside cells is conceived to potentially disrupt plasma membrane and subcellular structure. Herein, an alkaline phosphatase (ALP)-activatable hybrid of ICG-CF₄ KY^p is facilely synthesized by conjugating photosensitizer indocyanine green (ICG) with CF₄ KY^p peptide via classical Michael addition reaction. ALP-induced dephosphorylation of ICG-CF₄ KY^p enables its transformation from small-molecule precursor into rigid nanofibrils, and such fibrillation in situ causes severe mechanical disruption of cytomembrane. Besides, ICG-mediated photosensitization causes additional oxidative damage of plasma membrane by lipid peroxidation. Hollow MnO₂ nanospheres devote to deliver ICG-CF₄ KY^p into tumorous tissue through tumor-specific acidity/glutathione-triggered degradation of MnO₂ , which is monitored by fluorescent probing and magnetic resonance imaging. The burst release of damage-associated molecular patterns and other tumor antigens during therapy effectively triggers immunogenetic cell death and improves immune stimulatory, as demonstrated by the promotion of dendritic cell maturation and CD8⁺ lymphocyte infiltration, as well as constraint of regulatory T cell population. Taken together, such cytomembrane injury strategy based on peptide fibrillation in situ holds high clinical promise for lesion-specific elimination of primary, abscopal, and metastatic tumors, which may enlighten more bioinspired nanoplatforms for anticancer theranostics.

Cytokine sustained delivery for cancer therapy; special focus on stem cell- and biomaterial- based delivery methods

As immune regulators, cytokines serve critical role as signaling molecules in response to danger, tissue damage, or injury. Importantly, due to their vital role in immunological surveillance, cytokine therapy has become a promising therapeutics for cancer therapy. Cytokines have, however, been used only in certain clinical settings. Two key characteristics of cytokines contribute to this clinical translational challenge: first, they are highly pleiotropic, and second, in healthy physiology, they are typically secreted and act very locally in tissues. Systemic administration of the cytokines can consequently result in serious side effects. Thus, scientists have sought various strategies to circumvent theses hurdles. Recent in vivo reports signify that cytokine delivery platforms can increase their safety and therapeutic efficacy in tumor xenografts. Meanwhile, cytokine delivery using multipotent stem cells, in particular mesenchymal stem/stromal cells (MSCs), and also a diversity of particles and biomaterials has demonstrated greater capability in this regards. Herein, we take a glimpse into the recent advances in cytokine sustained delivery using stem cells and also biomaterials to ease safe and effective treatments of a myriad of human tumors.

Ferritin Nanocaged Doxorubicin Potentiates Chemo-Immunotherapy against Hepatocellular Carcinoma via Immunogenic Cell Death

Although immunotherapy of hepatocellular carcinoma using immune checkpoint inhibitors has achieved certain success, only a subset of patients benefits from this therapeutic strategy. The combination of immunostimulatory chemotherapeutics represents a promising strategy to enhance the effectiveness of immunotherapy. However, it is hampered by the poor delivery of conventional chemotherapeutics. Here, it is shown that H-ferritin nanocages loaded with doxorubicin (DOX@HFn) show potent chemo-immunotherapy in hepatocellular carcinoma tumor models. DOX@HFn is constructed with uniform size, high stability, favorable drug loading, and intracellular acidity-driven drug release. The receptor-mediated targeting of DOX@HFn to liver cancer cells promote cellular uptake and tumor penetration in vitro and in vivo. DOX@HFn triggers immunogenic cell death to tumor cells and promotes the subsequent activation and maturation of dendritic cells. In vivo studies in H22 subcutaneous hepatoma demonstrate that DOX@HFn significantly inhibits the tumor growth with >30% tumors completely eliminated, while alleviating the systemic toxicity of free DOX. DOX@HFn also exhibits robust antitumor immune response and tumoricidal effect in a more aggressive Hepa1-6 orthotopic liver tumor model, which is confirmed by the in situ magnetic resonance imaging and transcriptome sequencing. This study provides a facile and robust strategy to improve therapeutic efficacy of liver cancer.

The anaphylatoxin C5a: Structure, function, signaling, physiology, disease, and therapeutics

The complement system is one of the oldest known tightly regulated host defense systems evolved for efficiently functioning cell-based immune systems and antibodies. Essentially, the complement system acts as a pivot between the innate and adaptive arms of the immune system. The complement system collectively represents a cocktail of ∼50 cell-bound/soluble glycoproteins directly involved in controlling infection and inflammation. Activation of the complement cascade generates complement fragments like C3a, C4a, and C5a as anaphylatoxins. C5a is the most potent proinflammatory anaphylatoxin, which is involved in inflammatory signaling in a myriad of tissues. This review provides a comprehensive overview of human C5a in the context of its structure and signaling under several pathophysiological conditions, including the current and future therapeutic applications targeting C5a.

PARP1 Activation Induces HMGB1 Secretion Promoting Intestinal Inflammation in Mice and Human Intestinal Organoids

Extracellular High-mobility group box 1 (HMGB1) contributes to the pathogenesis of inflammatory disorders, including inflammatory bowel diseases (IBD). Poly (ADP-ribose) polymerase 1 (PARP1) has been recently reported to promote HMGB1 acetylation and its secretion outside cells. In this study, the relationship between HMGB1 and PARP1 in controlling intestinal inflammation was explored. C57BL6/J wild type (WT) and PARP1^-/- mice were treated with DSS to induce acute colitis, or with the DSS and PARP1 inhibitor, PJ34. Human intestinal organoids, which are originated from ulcerative colitis (UC) patients, were exposed to pro-inflammatory cytokines (INFγ + TNFα) to induce intestinal inflammation, or coexposed to cytokines and PJ34. Results show that PARP1^-/- mice develop less severe colitis than WT mice, evidenced by a significant decrease in fecal and serum HMGB1, and, similarly, treating WT mice with PJ34 reduces the secreted HMGB1. The exposure of intestinal organoids to pro-inflammatory cytokines results in PARP1 activation and HMGB1 secretion; nevertheless, the co-exposure to PJ34, significantly reduces the release of HMGB1, improving inflammation and oxidative stress. Finally, HMGB1 release during inflammation is associated with its PARP1-induced PARylation in RAW264.7 cells. These findings offer novel evidence that PARP1 favors HMGB1 secretion in intestinal inflammation and suggest that impairing PARP1 might be a novel approach to manage IBD.

Clinical Biomarker of Sterile Inflammation, HMGB1, in Patients with Chronic Non-Specific Low Back Pain: A Pilot Cross-Sectional Study

The present study explores whether the inflammatory biomarker of sterile inflammation, high mobility box 1 (HMGB1), contributes to the inflammatory/nociceptive pathophysiology that characterizes chronic non-specific low back pain (LBP). Patients with chronic LBP (N = 10, >3 pain score on a 11-point Visual Analogue Scale, VAS) and asymptomatic participants (N = 12) provided peripheral blood (PB) samples. The proportion of classical CD14++ monocytes within PB leukocytes was determined by flow cytometry. The plasma and extracellular HMGB1 levels in unstimulated adherent cell (AC) cultures were measured using specific immunoassays. HMGB1 localization in ACs was assessed by immunofluorescent staining. The relative gene expression levels of tumor necrosis factor α (TNFα), interleukin-1 beta (IL-1β) and HMGB1 were determined by quantitative polymerase chain reaction (qRT-PCR) in relation to the pain intensity (11-point VAS scores) in patients with LBP. The extracellular release of HMGB1 in the LBP patient AC cultures was significantly elevated (p = 0.001) and accompanied by its relocation into the cytoplasm from the nuclei. The number of CD14++ monocytes in the patients' PB was significantly (p = 0.03) reduced, while the HMGB1 plasma levels remained comparable to those of the controls. The mRNA levels of TNFα, IL-1β and HMGB1 were overexpressed relative to the controls and those of HMGB1 and IL-1β were correlated with the VAS scores at a significant level (p = 0.01-0.03). The results suggest that HMGB1 may play an important role in the pathophysiology of chronic non-specific LBP.

Lessons from Cardiac and Vascular Biopsies from Patients with and without Inflammatory Rheumatic Diseases

Feiring Heart Biopsy Study enables searching for potential pathogenetic mechanisms, therapeutic targets, and biomarkers through the assessment of clinical data and multiple blood and tissue samples from patients with and without inflammatory rheumatic diseases (IRDs), undergoing coronary artery bypass grafting. Some of our findings, for example, more inflammation (including the presence of immune cells and expression of proinflammatory cytokines) in vessels and the heart, and the presence of certain bacteria and autoantigens in vessels, could contribute to the increased risk of ischemia, aneurysms, and/or cardiac dysfunction in IRDs. Furthermore, some of the detected factors could be involved in the pathomechanisms of these conditions in general.

HMGB1 accumulation in cytoplasm mediates noise-induced cochlear damage

Damage-associated molecular pattern molecules (DAMPs) play a critical role in mediating cochlear cell death, which leads to noise-induced hearing loss (NIHL). High-mobility group box 1 (HMGB1), a prototypical DAMP released from cells, has been extensively studied in the context of various diseases. However, whether extracellular HMGB1 contributes to cochlear pathogenesis in NIHL and the potential signals initiating HMGB1 release from cochlear cells are not well understood. Here, through the transfection of the adeno-associated virus with HMGB1-HA-tag, we first investigated early cytoplasmic accumulation of HMGB1 in cochlear hair cells after noise exposure. We found that the cochlear administration of HMGB1-neutralizing antibody immediately after noise exposure significantly alleviated hearing loss and outer hair cells (OHCs) death induced by noise exposure. In addition, activation of signal transducer and activators of transcription 1 (STAT1) and cellular hyperacetylation were verified as potential canonical initiators of HMGB1 cytoplasmic accumulation. These findings reveal the adverse effects of extracellular HMGB1 on the cochlea and the potential signaling events mediating HMGB1 release in hair cells, indicating multiple potential pharmacotherapeutic targets for NIHL.

ROS-responsive 18β-glycyrrhetic acid-conjugated polymeric nanoparticles mediate neuroprotection in ischemic stroke through HMGB1 inhibition and microglia polarization regulation

Ischemic stroke is an acute and serious cerebral vascular disease, which greatly affects people's health and brings huge economic burden to society. Microglia, as important innate immune components in central nervous system (CNS), are double-edged swords in the battle of nerve injury, considering their polarization between pro-inflammatory M1 or anti-inflammatory M2 phenotypes. High mobility group box 1 (HMGB1) is one of the potent pro-inflammatory mediators that promotes the M1 polarization of microglia. 18β-glycyrrhetinic acid (GA) is an effective intracellular inhibitor of HMGB1, but of poor water solubility and dose-dependent toxicity. To overcome the shortcomings of GA delivery and to improve the efficacy of cerebral ischemia therapy, herein, we designed reactive oxygen species (ROS) responsive polymer-drug conjugate nanoparticles (DGA) to manipulate microglia polarization by suppressing the translocation of nuclear HMGB1. DGA presented excellent therapeutic efficacy in stroke mice, as evidenced by the reduction of infarct volume, recovery of motor function, suppressed of M1 microglia activation and enhanced M2 activation, and induction of neurogenesis. Altogether, our work demonstrates a close association between HMGB1 and microglia polarization, suggesting potential strategies for coping with inflammatory microglia-related diseases.

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We synthesized GA-boronate ester-conjugated diethylaminoethylen-dextran polymer-drug conjugate nanoparticles.

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The DGA nanoparticles achieve ROS-responsive drug release.

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The DGA nanoparticles inhibit cytoplasmic translocation of nuclear HMGB1, thus modulate microglia to M2 phenotype.

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The DGA nanoparticles effectively alleviate the pathology of stroke, reduce infarct volume, and enhance neurogenesis.

Looking on the horizon; potential and unique approaches to developing radiation countermeasures for deep space travel

Future lunar missions and beyond will require new and innovative approaches to radiation countermeasures. The Translational Research Institute for Space Health (TRISH) is focused on identifying and supporting unique approaches to reduce risks to human health and performance on future missions beyond low Earth orbit. This paper will describe three funded and complementary avenues for reducing the risk to humans from radiation exposure experienced in deep space. The first focus is on identifying new therapeutic targets to reduce the damaging effects of radiation by focusing on high throughput genetic screens in accessible, sometimes called lower, organism models. The second focus is to design innovative approaches for countermeasure development with special attention to nucleotide-based methodologies that may constitute a more agile way to design therapeutics. The final focus is to develop new and innovative ways to test radiation countermeasures in a human model system. While animal studies continue to be beneficial in the study of space radiation, they can have imperfect translation to humans. The use of three-dimensional (3D) complex in vitro models is a promising approach to aid the development of new countermeasures and personalized assessments of radiation risks. These three distinct and unique approaches complement traditional space radiation efforts and should provide future space explorers with more options to safeguard their short and long-term health.

The Role of High Mobility Group Box 1 (HMGB1) in Neurodegeneration: A Systematic Review

BACKGROUND

High mobility group box 1 (HMGB1) protein is a damage-associated molecular pattern (DAMP) that plays an important role in the repair and regeneration of tissue injury. It also acts as a pro-inflammatory cytokine through the activation of toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE), to elicit the neuroinflammatory response. HMGB1 may aggravate several cellular responses, which may lead to pathological inflammation and cellular death. Thus, there have been a considerable amount of research into the pathological role of HMGB1 in diseases. However, whether the mechanism of action of HMGB1 is similar in all neurodegenerative disease pathology remains to be determined.

OBJECTIVE

Therefore, this systematic review aimed to critically evaluate and elucidate the role of HMGB1 in the pathology of neurodegeneration based on the available literature.

METHODS

A comprehensive literature search was performed on four databases; EMBASE, PubMed, Scopus, and CINAHL Plus.

RESULTS

A total of 85 articles were selected for critical appraisal, after subjecting to the inclusion and exclusion criteria in this study. The selected articles revealed that HMGB1 levels were found elevated in most neurodegeneration except in Huntington's disease and Spinocerebellar ataxia, where the levels were found decreased. This review also showcased that HMGB1 may act on distinctive pathways to elicit its pathological response leading to the various neurodegeneration processes/ diseases.

CONCLUSION

While there have been promising findings in HMGB1 intervention research, further studies may still be required before any HMGB1 intervention may be recommended as a therapeutic target for neurodegenerative diseases.

AllergoOncology: Danger signals in allergology and oncology: A European Academy of Allergy and Clinical Immunology (EAACI) Position Paper

The immune system interacts with many nominal 'danger' signals, endogenous danger-associated (DAMP), exogenous pathogen (PAMP) and allergen (AAMP)-associated molecular patterns. The immune context under which these are received can promote or prevent immune activating or inflammatory mechanisms and may orchestrate diverse immune responses in allergy and cancer. Each can act either by favouring a respective pathology or by supporting the immune response to confer protective effects, depending on acuity or chronicity. In this Position Paper under the collective term danger signals or DAMPs, PAMPs and AAMPs, we consider their diverse roles in allergy and cancer and the connection between these in AllergoOncology. We focus on their interactions with different immune cells of the innate and adaptive immune system and how these promote immune responses with juxtaposing clinical outcomes in allergy and cancer. While danger signals present potential targets to overcome inflammatory responses in allergy, these may be reconsidered in relation to a history of allergy, chronic inflammation and autoimmunity linked to the risk of developing cancer, and with regard to clinical responses to anti-cancer immune and targeted therapies. Cross-disciplinary insights in AllergoOncology derived from dissecting clinical phenotypes of common danger signal pathways may improve allergy and cancer clinical outcomes.

Alarmins in autoimmune diseases

Alarmins are endogenous, constitutively expressed, chemotacting and immune activating proteins or peptides released because of non-programmed cell death (i.e. infections, trauma, etc). They are considered endogenous damage-associated molecular patterns (DAMPs), able to induce a sterile inflammation. In the last years, several studies highlighted a possible role of different alarmins in the pathogenesis of various autoimmune and immune-mediated diseases. We reviewed the relevant literature about this topic, for about 160 articles. Particularly, we focused on systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, idiopathic inflammatory myopathies, ANCA-associated vasculitides, Behçet's disease) and cutaneous organ-specific autoimmune diseases (vitiligo, psoriasis, alopecia, pemphigo). Finally, we discussed about future perspectives and potential therapeutic implications of alarmins in autoimmune diseases. In fact, identification of receptors and downstream signal transducers of alarmins may lead to the identification of antagonistic inhibitors and agonists, with the capacity to modulate alarmins-related pathways and potential therapeutic applicability.

Relationships between serum HMGB1 concentration and subpopulation composition of circulating monocytes in patients with subclinical atherosclerosis

Chronic non-infectious inflammation of low intensity is the most important mechanism of development and progression in atherosclerosis. Under the conditions of persistent non-resolving inflammation observed in the vascular wall and atherosclerotic plaque (ASB), permanent tissue damage occurs, thus leading to increased formation of endogenous danger-associated molecular patterns (DAMPs). The non-histone chromosomal protein HMGB1 may be regarded as a prototypical DAMPs. HMGB1 acts as a DAMP if entering the extracellular space, causing inflammation by its binding to pattern-recognizing receptors (TLR2, TLR4, RAGE, CD36, etc.). A number of clinical studies have revealed higher HMGB1 levels in the blood of patients with coronary heart disease and atherosclerotic disease of the lower limb arteries, as well as its interrelations with the burden of coronary artery atherosclerosis. Currently, the mechanisms of HMGB1-mediated atherosclerosis progression are studied only fragmentary. The aim of our study was to investigate relationships between the serum HMGB1 level and subsets of circulating monocyte subpopulations in patients with subclinical atherosclerosis.

The study enrolled patients aged 40-64 years with subclinical atherosclerosis of peripheral arteries. Serum HMGB1 concentration was determined using enzyme immunoassay kits (Human HMGB1/HMG-1 ELISA Kit, NBP2-62766, Novus Biologicals, USA). The serum HMGB1 threshold was 18.75 pg/ml, whereas the measurement range was 31.25 to 2000 pg/ml. Phenotyping of the blood monocyte subpopulations was performed by flow cytometry using Navios 6/2 device (Beckman Coulter, USA).

An increase in serum HMGB1 concentration was associated with decreased number of classical M2 monocytes, and an increase in intermediate and M1 monocytes. Moreover, an increase in HMGB1 concentration was associated with higher numbers of classical, intermediate, and non-classical monocytes expressing CD36 and TLR2. Increased HMGB1 concentration (from Q1 to Q4) correlated with higher numbers of classical (p = 0.001) and intermediate monocytes (p = 0.006) but not with non-classical phenotypes (p = 0.147). Upon increase of HMGB1 concentration (Q1 to Q4), we have found an increase in the number of classical (p < 0.0001), intermediate (p < 0.0001), and non-classical (p < 0.0001), CD36-expressing monocytes. An increased number of intermediate (p = 0.022; p1, 4 = 0.034) and non-classical, TLR2-expressing monocytes was also revealed (p = 0.002; p1, 4 = 0.035). By mean of correlation analysis, IL-1β concentrations showed direct correlation with the number of M1 monocytes (r = 0.268; p = 0.035) and inverse relation with the number of M2 monocytes (r = -0.376; p = 0.003).

Increased serum HMGB1 concentration in patients with subclinical atherosclerosis was associated with decreased numbers of classical and M2 monocytes, as well as higher numbers of intermediate and M1 monocytes, like as with increased contents of intermediate and non-classical monocytes expressing CD36 and TLR2. IL-1β levels directly correlated with HMGB1 concentration and the number of Mi-monocytes.

Molecular insights into the multifaceted functions and therapeutic targeting of high mobility group box 1 in metabolic diseases

HMGB1 is a ubiquitously expressed protein localized in nucleus, cytoplasm, as well as secreted into extracellular space. Nuclear HMGB1 binds to DNAs and RNAs, regulating genomic stability and transcription. Cytoplasmic HMGB1 regulates autophagy through binding to core autophagy regulators. Secreted extracellular HMGB1 functions as a ligand to various receptors (RAGE and TLRs, etc.), regulating multiple signalling pathways, such as MAPK, PI3K and NF-κB signallings. Trafficking and localization of HMGB1 across cellular compartments could be regulated by its posttranslational modifications, which fine-tune its functions in metabolic diseases, inflammation and cancers. The current review examines the up-to-date findings pertaining to the biological functions of HMGB1, with focus on its posttranslational modifications and roles in downstream signalling pathways involved in metabolic diseases. This review also discusses the feasibility of targeting HMGB1 as a potential pharmacological intervention for metabolic diseases.

Microbial-Catalyzed Baeyer-Villiger Oxidation for 3,4-seco-Triterpenoids as Potential HMGB1 Inhibitors

Pentacyclic triterpenoids are considered to be the potential HMGB1 inhibitors, but due to the limited number of hydrogen bond donors and the number of rotatable bonds in the rigid skeletons, their further chemical biology research with this target was restricted. To improve these profiles, microbial-catalyzed Baeyer-Villiger oxidation of the primary ursane and oleanane-type triterpenoids including uvaol (1), erythrodiol (2), oleanolic acid (3), and ursolic acid (4) was performed by Streptomyces olivaceus CICC 23628. As a result, ten new and one known A-ring cleaved metabolites were obtained and the possible biogenetic pathways were also discussed based on the HPLC-MS analysis. Furthermore, the direct interactions between compounds 1d, 2b, and HMGB1 were observed by the biolayer interferometry technique. Molecular docking revealed that the newly introduced vicinal diol at C-4, C-24, and the hydroxyl group at C-21 of compound 1d are crucial for binding with HMGB1. The cellular assay showed that co-treatment of 1d could significantly block HMGB1-activated nitric oxide release with an IC₅₀ value of 9.37 μM on RAW 264.7 cells. Altogether, our research provides some insights into 3,4-seco-triterpenes as potential anti-inflammatory candidates for the discovery of novel HMGB1 inhibitors.

HMGB1-mediated restriction of EPO signaling contributes to anemia of inflammation

Anemia of inflammation, also known as anemia of chronic disease, is refractory to erythropoietin (EPO) treatment, but the mechanisms underlying the EPO refractory state are unclear. Here, we demonstrate that high mobility group box-1 protein (HMGB1), a damage-associated molecular pattern molecule recently implicated in anemia development during sepsis, leads to reduced expansion and increased death of EPO-sensitive erythroid precursors in human models of erythropoiesis. HMGB1 significantly attenuates EPO-mediated phosphorylation of the Janus kinase 2/STAT5 and mTOR signaling pathways. Genetic ablation of receptor for advanced glycation end products, the only known HMGB1 receptor expressed by erythroid precursors, does not rescue the deleterious effects of HMGB1 on EPO signaling, either in human or murine precursors. Furthermore, surface plasmon resonance studies highlight the ability of HMGB1 to interfere with the binding between EPO and the EPOR. Administration of a monoclonal anti-HMGB1 antibody after sepsis onset in mice partially restores EPO signaling in vivo. Thus, HMGB1-mediated restriction of EPO signaling contributes to the chronic phase of anemia of inflammation.

TMT labeled comparative proteomic analysis reveals spleen active immune responses during Clostridium perfringens type C infected piglet diarrhea

Background

Clostridium perfringens (C. perfringens) type C is the principal pathogenic clostridia of swine, frequently causing hemorrhagic diarrhea, even necrotic enteritis in piglets, leading to severe economic loss for swine industr ies worldwide. However, there are no specific and effective prevention measures. Therefore, clarifying the molecular mechanisms of hosts against pathogenesis infection is very important to reduce the incidence of C. perfringens type C infected piglet diarrhea disease.

Methods

We performed an TMT labeling-based quantitative spleen proteomic analysis of the control group (SC), tolerance group (SR) and susceptible group (SS) to identify the differentially expressed proteins (DEPs), and screened potential molecular markers of piglet spleen tissues in response to C. perfringens type C infection.

Results

In this study, a total of 115, 176 and 83 DEPs were identified in SR vs SC, SS vs SC, and SR vs SC, respectively, which may play the important regulatory roles in the process of piglet spleens in response toC. perfringens type C-infected diarrhea diseases. GO enrichment analysis revealed that the DEPs were mostly significantly enriched in acute inflammatory response, defense response, antimicrobial response, transporter activity, cellular metabolic process and so on, and KEGG pathway enrichment analysis showed that the significantly enriched immune related pathways of the PPAR signaling pathway, IL-17 signaling pathway, antigen processing and presentation, which hints at the immune defense process of piglet spleen against C. perfringens infection. This study helps to elucidate the protein expressional pattern of piglet spleen against C. perfringens type C-infected diarrhea disease, which can contribute to the prevention and control for pig diarrhea disease and the further development of diarrhea resistant pig breeding.

HMGB1 Inhibition to Ameliorate Organ Failure and Increase Survival in Trauma

Several preclinical and clinical reports have demonstrated that levels of circulating high mobility group box 1 protein (HMGB1) are increased early after trauma and are associated with systemic inflammation and clinical outcomes. However, the mechanisms of the interaction between HMGB1 and inflammatory mediators that lead to the development of remote organ damage after trauma remain obscure. HMGB1 and inflammatory mediators were analyzed in plasma from 54 combat casualties, collected on admission to a military hospital in Iraq, and at 8 and 24 h after admission. In total, 45 (83%) of these patients had traumatic brain injury (TBI). Nine healthy volunteers were enrolled as controls. HMGB1 plasma levels were significantly increased in the first 8 h after admission, and were found to be associated with systemic inflammatory responses, injury severity score, and presence of TBI. These data provided the rationale for designing experiments in rats subjected to blast injury and hemorrhage, to explore the effect of HMGB1 inhibition by CX-01 (2-O, 3-O desulfated heparin). Animals were cannulated, then recovered for 5–7 days before blast injury in a shock tube and volume-controlled hemorrhage. Blast injury and hemorrhage induced an early increase in HMGB1 plasma levels along with severe tissue damage and high mortality. CX-01 inhibited systemic HMGB1 activity, decreased local and systemic inflammatory responses, significantly reduced tissue and organ damage, and tended to increase survival. These data suggest that CX-01 has potential as an adjuvant treatment for traumatic hemorrhage.

Complement C5a induces the formation of neutrophil extracellular traps by myeloid-derived suppressor cells to promote metastasis

Myeloid-derived suppressor cells (MDSCs) play a major role in cancer progression. In this study, we investigated the mechanisms by which complement C5a increases the capacity of polymorphonuclear MDSCs (PMN-MDSCs) to promote tumor growth and metastatic spread. Stimulation of PMN-MDSCs with C5a favored the invasion of cancer cells via a process dependent on the formation of neutrophil extracellular traps (NETs). NETosis was dependent on the production of high mobility group box 1 (HMGB1) by cancer cells. Moreover, C5a induced the surface expression of the HMGB1 receptors TLR4 and RAGE in PMN-MDSCs. In a mouse lung metastasis model, inhibition of C5a, C5a receptor-1 (C5aR1) or NETosis reduced the number of circulating-tumor cells (CTCs) and the metastatic burden. In support of the translational relevance of these findings, C5a was able to stimulate migration and NETosis in PMN-MDSCs obtained from lung cancer patients. Furthermore, myeloperoxidase (MPO)-DNA complexes, as markers of NETosis, were elevated in lung cancer patients and significantly correlated with C5a levels. In conclusion, C5a induces the formation of NETs from PMN-MDSCs in the presence of cancer cells, which may facilitate cancer cell dissemination and metastasis.

Luteolin attenuates hepatic injury in septic mice by regulating P2X7R-based HMGB1 release

P2X7 receptor (P2X7R) and NLRP3 cooperatively participate in inflammation and hepatocyte damage during hepatic injury induced by lipopolysaccharides (LPS). High-mobility group box 1 (HMGB1) released from immune cells in response to such stimuli plays a vital role in mediating inflammation via TLR4 and the receptor for advanced glycation end products (RAGE), a receptor for HMGB1. However, the correlation among P2X7R, RAGE and TLR4 in regulating the release of HMGB1 has not been elucidated. Increasing the number of daily foods is found to be beneficial for hepatocyte damage in septic hepatic injury. Hence, we investigated the effects of luteolin, a natural flavonoid mainly existing in vegetables and fruits, on liver injury, focusing on how luteolin participates in hepatitis based on the P2X7R-RAGE-TLR4 axis by regulating the release of HMGB1. The results demonstrated that the indicators of hepatic injury such as increased ALT, AST in the serum and infiltration of immune cells were attenuated after luteolin treatment in LPS-induced mice. Luteolin could also suppress the production and release of HMGB1 and the activation of caspase 1 both in LPS-induced mice and LPS/ATP-stimulated HepG2 cells. Collectively, luteolin reversed LPS-induced hepatic injury, especially inflammation, likely by regulating the release of HMGB1 through the P2X7R-RAGE-TLR4 axis.

Systematic Development of Peptide Inhibitors Targeting the CXCL12/HMGB1 Interaction

During inflammatory reactions, the production and release of chemotactic factors guide the recruitment of selective leukocyte subpopulations. The alarmin HMGB1 and the chemokine CXCL12, both released in the microenvironment, can form a heterocomplex, which exclusively acts on the chemokine receptor CXCR4, enhancing cell migration, and in some pathological conditions such as rheumatoid arthritis exacerbates the immune response. An excessive cell influx at the inflammatory site can be diminished by disrupting the heterocomplex. Here, we report the computationally driven identification of the first peptide (HBP08) binding HMGB1 and selectively inhibiting the activity of the CXCL12/HMGB1 heterocomplex. Furthermore, HBP08 binds HMGB1 with the highest affinity reported so far (K_d of 0.8 ± 0.4 μM). The identification of this peptide represents an important step toward the development of innovative pharmacological tools for the treatment of severe chronic inflammatory conditions characterized by an uncontrolled immune response.

Magnesium sulfate ameliorates sepsis-induced diaphragm dysfunction in rats via inhibiting HMGB1/TLR4/NF-κB pathway

Diaphragm dysfunction could be induced by sepsis with subsequent ventilatory pump failure that is associated with local infiltration of inflammatory factors in the diaphragm. It has been shown that the administration of anticonvulsant agent, magnesium sulfate (MgSO₄) could decrease systematic inflammatory response. We recently reported that MgSO₄ could inhibit macrophages high mobility group box 1 (HMGB1) secretion that confirms its anti-inflammatory properties. Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signal pathway appears to be involved in the pathology of septic experimental animal’s inflammatory response and involve in the pathogenic mechanisms of sepsis-induced diaphragm dysfunction. Thus, in this study, we are aiming to explore whether MgSO₄ could ameliorate sepsis-induced diaphragm dysfunction via TLR4/NF-κB pathway in a rodent model with controlled mechanical ventilation (CMV) and subsequent septic challenge.

Cross-talks in colon cancer between RAGE/AGEs axis and inflammation/immunotherapy

The tumour microenvironment is the result of the activity of many types of cells in various metabolic states, whose metabolites are shared between cells. This cellular complexity results in an availability profile of nutrients and reactive metabolites such as advanced glycation end products (AGE). The tumour microenvironment is not favourable to immune cells due to hypoxia and for the existence of significant competition between various types of cells for a limited nutrient pool. However, it is now known that cancer cells can influence the host's immune reaction through the expression and secretion of numerous molecules. The microenvironment can therefore present itself in different patterns that contribute to shaping immune surveillance. Colorectal cancer (CRC) is one of the most important causes of death in cancer patients. Recently, immunotherapy has begun to give encouraging results in some groups of patients suffering from this neoplasm. The analysis of literature data shows that the RAGE (Receptor for advanced glycation end products) and its numerous ligands contribute to connect the energy metabolic pathway, which appears prevalently disconnected by mitochondrial running, with the immune reaction, conditioned by local microbiota and influencing tumour growth. Understanding how metabolism in cancer and immune cells shapes response and resistance to therapy, will provide novel potential strategies to increase both the number of tumour types treated by immunotherapy and the rate of immunotherapy response. The analysis of literature data shows that an immunotherapy approach based on the knowledge of RAGE and its ligands is not only possible, but also desirable in the treatment of CRC.

Tanshinones: An Update in the Medicinal Chemistry in Recent 5 Years

Tanshinones are an important type of natural products isolated from Salvia miltiorrhiza Bunge with various bioactivities. Tanshinone IIa, cryptotanshinone and tanshinone I are three kinds of tanshinones which have been widely investigated. Particularly, sodium tanshinone IIa sulfonate is a water-soluble derivative of tanshinone IIa and it is used in clinical in China for treating cardiovascular diseases. In recent years, there are increasing interests in the investigation of tanshinones derivatives in various diseases. This article presents a review of the anti-atherosclerotic effects, cardioprotective effects, anticancer activities, antibacterial activities and antiviral activities of tanshinones and structural modification work in recent years.

The Role of Autophagy in Hypoxia-Induced Neuroinflammation

Autophagy is a critical cytoprotective mechanism that takes a hand in innate or adaptive immune responses. Hypoxia is a common pathophysiological mechanism that can lead to systemic pathological reactions. In recent years, the impact of hypoxia on the central nervous system has attracted more attention. In the past, autophagy was thought to be directly involved in the apoptosis of nerve cells under hypoxia. An increasing amount of evidence shows that the neuroinflammatory response plays an indispensable role in the neural damage caused by hypoxia. There are many mechanisms related to the neuroinflammatory response induced by hypoxia, among which autophagy is an important aspect, but the role of autophagy is still unclear. This article focuses on how autophagy flux of central immune cells is modified under hypoxic conditions, and how this autophagy affects neuroinflammatory response.

Emerging medical therapies in crush syndrome - progress report from basic sciences and potential future avenues

Crush injury is a disease that is commonly found in victims of earthquakes, debris flows, mine disasters, explosions, terrorist attacks, local wars, and other accidents. The complications that arise due to the crush injury inflicted on victims give rise to crush syndrome (CS). If not treated in time, the mortality rate of CS is very high. The most important measure that can be taken to reduce mortality in such situations is to immediately start treatment. However, the traditional treatment methods such as fluid resuscitation, diuresis, and hemodialysis are not feasible enough to be carried out at the disaster scene. So there is a need for developing new treatments that are efficient and convenient. Because it is difficult to diagnose in the disaster area and reach the treatment equipment and treat on time. It has become a new research needs to be directed into identifying new medical treatment targets and methods using the etiology and pathophysiological mechanisms of CS. In recent years, a large number of new anti-oxidant and anti-inflammatory drug therapies have been shown to be highly efficacious in CS rat/mouse models. Some of them are expected to become specific drugs for the emergency treatment of a large number of patients who may develop CS in the aftermath of earthquakes, wars, and other disasters in the future. Hence, we have reviewed the latest research on the medical therapy of CS as a source for anyone wishing to pursue research in this direction.

The Effect and Regulatory Mechanism of High Mobility Group Box-1 Protein on Immune Cells in Inflammatory Diseases

High mobility group box-1 protein (HMGB1), a member of the high mobility group protein superfamily, is an abundant and ubiquitously expressed nuclear protein. Intracellular HMGB1 is released by immune and necrotic cells and secreted HMGB1 activates a range of immune cells, contributing to the excessive release of inflammatory cytokines and promoting processes such as cell migration and adhesion. Moreover, HMGB1 is a typical damage-associated molecular pattern molecule that participates in various inflammatory and immune responses. In these ways, it plays a critical role in the pathophysiology of inflammatory diseases. Herein, we review the effects of HMGB1 on various immune cell types and describe the molecular mechanisms by which it contributes to the development of inflammatory disorders. Finally, we address the therapeutic potential of targeting HMGB1.

Could Targeting HMGB1 be Useful for the Clinical Management of COVID-19 Infection?

Since the high mobility group box-1 (HMGB1) molecule had been recognized as a proinflammatory cytokine, which mediates endotoxin lethality of mice, there have been lots of papers about targeting the HMGB1 within the contexts of infection, inflammation, and cancer. The pathogenic impact of HMGB1 to the severe acute respiratory syndrome (SARS) and disease management with herbal formulations targeting this unique protein have already been proposed. However, the failure of the numerous current anti-viral therapies on the ongoing viral infections casts reappraisal of the possible interrelationships regarding the HMGB1 and SARS-CoV-2. COVID-19 pandemic due to the SARS-CoV-2 virus is a currently ongoing challenging global health crisis. There is still not any proven exact treatment of COVID-19 with high level of evidence. In this paper, we focused on the potential usage of external and/or inhalation preparation of antiviral/antibacterial herbal products capable of targeting HMGB1 for the clinical management candidates of the ongoing COVID-19 infection.

Effect of folinic acid on serum homocysteine, TNFα, IL-10, and HMGB1 gene expression in head injury model

Background

Head injury or traumatic brain injury is the leading cause of mortality and morbidity. Many modalities of neuroprotection had been developed in brain injury but there was no much information regarding folinic acid's effect on neuroinflammation associated with homocysteine, TNFα, IL-10, and HMGB1.

Objective

This study aimed to investigate whether folinic acid has improving effect on head injury model.

Method

This study was done in the rat's head injury model using modified Marmarou weight drop model. Fifteen rats were randomized and grouped into 3 groups: Group A: Folinic acid (+), head injury (−); Group B: Folinic acid (−), head injury (+); Group C: Folinic acid (+), head injury (+). Folinic acid was administered intraperitoneally with a dose of 60 mg/m². Blood samples were taken immediately after head injury (H0), 12 h (H12), and 24 h (H24) after head injury from the lateral vein of tail. Serum level of homocysteine, TNFα, and IL-10 were measured using ELISA, and HMGB1 gene expression was measured with Real-Time RT-PCR.

Results

This study found serum level of homocysteine, TNFα, IL-10 and HMGB1 gene expression were markedly increased at all time points after head injury. Significantly lower level of serum homocysteine, TNFα, IL-10 and HMGB1 gene expression were found after 24 h treatment with folinic acid in group C compared to those in group B.

Conclusion

Folinic acid may have anti-inflammatory properties in traumatic brain injury by inhibition of serum level of homocysteine, TNFα, IL-10 and HMGB1 gene expression.

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An animal study of head injury model using modified Marmarou weight drop model.

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This three groups study with folinic acid treatment on head injury rats.

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Folinic acid has anti-inflammatory properties in traumatic brain injury model.

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Folinic acid inhibits serum level of homocysteine, TNFα, IL-10 and HMGB1expression.

HIV-1 Latency and Viral Reservoirs: Existing Reversal Approaches and Potential Technologies, Targets, and Pathways Involved in HIV Latency Studies

Eradication of latent human immunodeficiency virus (HIV) infection is a global health challenge. Reactivation of HIV latency and killing of virus-infected cells, the so-called "kick and kill" or "shock and kill" approaches, are a popular strategy for HIV cure. While antiretroviral therapy (ART) halts HIV replication by targeting multiple steps in the HIV life cycle, including viral entry, integration, replication, and production, it cannot get rid of the occult provirus incorporated into the host-cell genome. These latent proviruses are replication-competent and can rebound in cases of ART interruption or cessation. In general, a very small population of cells harbor provirus, serve as reservoirs in ART-controlled HIV subjects, and are capable of expressing little to no HIV RNA or proteins. Beyond the canonical resting memory CD4⁺ T cells, HIV reservoirs also exist within tissue macrophages, myeloid cells, brain microglial cells, gut epithelial cells, and hematopoietic stem cells (HSCs). Despite a lack of active viral production, latently HIV-infected subjects continue to exhibit aberrant cellular signaling and metabolic dysfunction, leading to minor to major cellular and systemic complications or comorbidities. These include genomic DNA damage; telomere attrition; mitochondrial dysfunction; premature aging; and lymphocytic, cardiac, renal, hepatic, or pulmonary dysfunctions. Therefore, the arcane machineries involved in HIV latency and its reversal warrant further studies to identify the cryptic mechanisms of HIV reservoir formation and clearance. In this review, we discuss several molecules and signaling pathways, some of which have dual roles in maintaining or reversing HIV latency and reservoirs, and describe some evolving strategies and possible approaches to eliminate viral reservoirs and, ultimately, cure/eradicate HIV infection.

Role of HMGB1 in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN), one of major dose-limiting side effects of first-line chemotherapeutic agents such as paclitaxel, oxaliplatin, vincristine, and bortezomib is resistant to most of existing medicines. The molecular mechanisms of CIPN have not been fully understood. High mobility group box 1 (HMGB1), a nuclear protein, is a damage-associated molecular pattern protein now considered to function as a pro-nociceptive mediator once released to the extracellular space. Most interestingly, HMGB1 plays a key role in the development of CIPN. Soluble thrombomodulin (TMα), known to degrade HMGB1 in a thrombin-dependent manner, prevents CIPN in rodents treated with paclitaxel, oxaliplatin, or vincristine and in patients with colorectal cancer undergoing oxaliplatin-based chemotherapy. In this review, we describe the role of HMGB1 and its upstream/downstream mechanisms in the development of CIPN and show drug candidates that inhibit the HMGB1 pathway, possibly useful for prevention of CIPN.

Beneficial effect of Indigo Naturalis on acute lung injury induced by influenza A virus

Background

Infections induced by influenza viruses, as well as coronavirus disease 19 (COVID-19) pandemic induced by severe acute respiratory coronavirus 2 (SARS-CoV-2) led to acute lung injury (ALI) and multi organ failure, during which traditional Chinese medicine (TCM) played an important role in treatment of the pandemic. The study aimed to investigate the effect of Indigo Naturalis on ALI induced by influenza A virus (IAV) in mice.

Method

The anti-influenza and anti-inflammatory properties of aqueous extract of Indigo Naturalis (INAE) were evaluated in vitro. BALB/c mice inoculated intranasally with IAV (H1N1) were treated intragastrically with INAE (40, 80 and 160 mg/kg/day) 2 h later for 4 or 7 days. Animal lifespan and mortality were recorded. Expression of high mobility group box-1 protein (HMGB-1) and toll-like receptor 4 (TLR4) were evaluated through immunohistological staining. Inflammatory cytokines were also monitored by ELISA.

Result

INAE inhibited virus replication on Madin-Darby canine kidney (MDCK) cells and decreased nitric oxide (NO) production from lipopolysaccharide (LPS)-stimulated peritoneal macrophages in vitro. The results showed that oral administration of 160 mg/kg of INAE significantly improved the lifespan (P < 0.01) and survival rate of IAV infected mice, improved lung injury and lowered viral replication in lung tissue (P < 0.01). Treatment with INAE (40, 80 and 160 mg/kg) significantly increased liver weight and liver index (P < 0.05), as well as weight and organ index of thymus and spleen at 160 mg/kg (P < 0.05). Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) levels were reduced by INAE administration (P < 0.05). The expression of HMGB-1 and TLR4 in lung tissue were also suppressed. The increased production of myeloperoxidase (MPO) and methylene dioxyamphetamine (MDA) in lung tissue were inhibited by INAE treatment (P < 0.05). Treatment with INAE reduced the high levels of interferon α (IFN-α), interferon β (IFN-β), monocyte chemoattractant protein-1 (MCP-1), regulated upon activation normal T cell expressed and secreted factor (RANTES), interferon induced protein-10 (IP-10), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) (P < 0.05), with increased production of interferon γ (IFN-γ) and interleukin-10 (IL-10) (P < 0.05).

Conclusion

The results showed that INAE alleviated IAV induced ALI in mice. The mechanisms of INAE were associated with its anti-influenza, anti-inflammatory and anti-oxidation properties. Indigo Naturalis might have clinical potential to treat ALI induced by IAV.

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

BACKGROUND

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).

METHODS

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.

RESULTS

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.

CONCLUSIONS

Inhibition of HMGB1 by injections of Met prevented tendinopathy development due to mechanical overloading in the Achilles tendon in mice.

CLINICAL RELEVANCE

Met may be able to be repurposed as a therapeutic option for preventing the development of tendinopathy in high-risk patients.

Discovery of 5,5'-Methylenedi-2,3-Cresotic Acid as a Potent Inhibitor of the Chemotactic Activity of the HMGB1·CXCL12 Heterocomplex Using Virtual Screening and NMR Validation

HMGB1 is a key molecule that both triggers and sustains inflammation following infection or injury, and is involved in a large number of pathologies, including cancer. HMGB1 participates in the recruitment of inflammatory cells, forming a heterocomplex with the chemokine CXCL12 (HMGB1·CXCL12), thereby activating the G-protein coupled receptor CXCR4. Thus, identification of molecules that disrupt this heterocomplex can offer novel pharmacological opportunities to treat inflammation-related diseases. To identify new HMGB1·CXCL12 inhibitors we have performed a study on the ligandability of the single HMG boxes of HMGB1 followed by a virtual screening campaign on both HMG boxes using Zbc Drugs and three different docking programs (Glide, AutoDock Vina, and AutoDock 4.2.6). The best poses in terms of scoring functions, visual inspection, and predicted ADME properties were further filtered according to a pharmacophore model based on known HMGB1 binders and clustered according to their structures. Eight compounds representative of the clusters were tested for HMGB1 binding by NMR. We identified 5,5'-methylenedi-2,3-cresotic acid (2a) as a binder of both HMGB1 and CXCL12; 2a also targets the HMGB1·CXCL12 heterocomplex. In cell migration assays 2a inhibited the chemotactic activity of HMGB1·CXCL12 with IC50 in the subnanomolar range, the best documented up to now. These results pave the way for future structure activity relationship studies to optimize the pharmacological targeting of HMGB1·CXCL12 for anti-inflammatory purposes.

Structure-based design of glycyrrhetinic acid derivatives as potent anti-sepsis agents targeting high-mobility group box-1

Novel Glycyrrhetinic Acid (GA) derivatives with fused heterocycles on A ring were structure-based designed and synthesized. Their potential anti-inflammatory effects were investigated by a classical LPS stimulated macrophage model. Surface plasmon resonance (SPR) was used to verify the binding of GA analogues with HMGB1. A preliminary structure-activity relationship was summarized and an analogue GA-60 with ortho-methoxybenzyl pyrozole showed stronger anti-inflammatory effect and higher affinity for HMGB1 with a K_d value of 12.5 μM. In addition, this compound exhibited excellent inhibitory functions on NO (96%), TNF-α (94%), and IL-6 (100%), by interfering with phosphorylation of p38, ERK, JNK MAPKs, as well as that of NF-κB p65 and IKKα/β. Moreover, GA-60 extended the survival of either the classic CLP-induced or LPS-induced sepsis mouse models. Molecular modeling predictions further supported these findings, clearly indicating that inhibiting HMGB1 release, using fused heterocyclic GA derivatives, is a promising strategy for treatment of sepsis.