HMGB1, an alarmin promoting HIV dissemination and latency in dendritic cells

Musashi-2 potentiates colorectal cancer immune infiltration by regulating the post-translational modifications of HMGB1 to promote DCs maturation and migration

Post-translational modifications (PTMs) of the non-histone protein high-mobility group protein B1 (HMGB1) are involved in modulating inflammation and immune responses. Recent studies have implicated that the RNA-binding protein (RBP) Musashi-2 (MSI2) regulates multiple critical biological metabolic and immunoregulatory functions. However, the precise role of MSI2 in regulating PTMs and tumor immunity in colorectal cancer (CRC) remains unclear. Here, we present data indicating that MSI2 potentiates CRC immunopathology in colitis-associated colon cancer (CAC) mouse models, cell lines and clinical specimens, specifically via HMGB1-mediated dendritic cell (DC) maturation and migration, further contributes to the infiltration of CD4+ and CD8+ T cells and inflammatory responses. Under stress conditions, MSI2 can exacerbate the production, nucleocytoplasmic transport and extracellular release of damage-associated molecular patterns (DAMPs)-HMGB1 in CRC cells. Mechanistically, MSI2 mainly enhances the disulfide HMGB1 production and protein translation via direct binding to nucleotides 1403-1409 in the HMGB1 3' UTR, and interacts with the cytoplasmic acetyltransferase P300 to upregulate its expression, further promoting the acetylation of K29 residue in HMGB1, thus leading to K29-HMGB1 nucleocytoplasmic translocation and extracellular release. Furthermore, blocking HMGB1 activity with glycyrrhizic acid (Gly) attenuates MSI2-mediated immunopathology and immune infiltration in CRC in vitro and in vivo. Collectively, this study suggests that MSI2 may improve the prognosis of CRC patients by reprogramming the tumor immune microenvironment (TIME) through HMGB1-mediated PTMs, which might be a novel therapeutic option for CRC immunotherapy.

Co-delivery of oxaliplatin prodrug liposomes with Bacillus Calmette-Guérin for chemo-immunotherapy of orthotopic bladder cancer

To reduce recurrence rate after transurethral resection of bladder tumor, long-term intravesical instillations of Bacillus Calmette-Guérin (BCG) and/or chemotherapeutic drugs is the standard treatment for non-muscle invasive bladder carcinoma. However, the main challenges of intravesical therapy, such as short retention time and poor permeability of drugs in the bladder, often require frequent and high-dose administrations, leading to significant adverse effects and financial burden for patients. Aiming at addressing these challenges, we developed a novel approach, in which the cell-penetrating peptide modified oxaliplatin prodrug liposomes and a low-dose BCG were co-delivered via a viscous chitosan solution (LRO-BCG/CS). LRO-BCG/CS addressed these challenges by significantly improving the retention capability and permeability of chemotherapy agents across the bladder wall. Then, oxaliplatin triggered the immunogenic cell death, and the combination of BCG simultaneously further activated the systemic anti-tumor immune response in the MB49 orthotopic bladder tumor model. As a result, LRO-BCG/CS demonstrated superior anti-tumor efficacy and prolonged the survival time of tumor-bearing mice significantly, even at relatively low doses of oxaliplatin and BCG. Importantly, this combinational chemo-immunotherapy showed negligible side effects, offering a promising and well-tolerated therapeutic strategy for bladder cancer patients.

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.

Role of dendritic cells in MYD88-mediated immune recognition and osteoinduction initiated by the implantation of biomaterials

Bone substitute material implantation has become an important treatment strategy for the repair of oral and maxillofacial bone defects. Recent studies have shown that appropriate inflammatory and immune cells are essential factors in the process of osteoinduction of bone substitute materials. Previous studies have mainly focused on innate immune cells such as macrophages. In our previous work, we found that T lymphocytes, as adaptive immune cells, are also essential in the osteoinduction procedure. As the most important antigen-presenting cell, whether dendritic cells (DCs) can recognize non-antigen biomaterials and participate in osteoinduction was still unclear. In this study, we found that surgical trauma associated with materials implantation induces necrocytosis, and this causes the release of high mobility group protein-1 (HMGB1), which is adsorbed on the surface of bone substitute materials. Subsequently, HMGB1-adsorbed materials were recognized by the TLR4-MYD88-NFκB signal axis of dendritic cells, and the inflammatory response was activated. Finally, activated DCs release regeneration-related chemokines, recruit mesenchymal stem cells, and initiate the osteoinduction process. This study sheds light on the immune-regeneration process after bone substitute materials implantation, points out a potential direction for the development of bone substitute materials, and provides guidance for the development of clinical surgical methods.

High Mobility Group Proteins in Sepsis

Sepsis, a systemic inflammatory response disease, is the most severe complication of infection and a deadly disease. High mobility group proteins (HMGs) are non-histone nuclear proteins binding nucleosomes and regulate chromosome architecture and gene transcription, which act as a potent pro-inflammatory cytokine involved in the delayed endotoxin lethality and systemic inflammatory response. HMGs increase in serum and tissues during infection, especially in sepsis. A growing number of studies have demonstrated HMGs are not only cytokines which can mediate inflammation, but also potential therapeutic targets in sepsis. To reduce sepsis-related mortality, a better understanding of HMGs is essential. In this review, we described the structure and function of HMGs, summarized the definition, epidemiology and pathophysiology of sepsis, and discussed the HMGs-related mechanisms in sepsis from the perspectives of non-coding RNAs (microRNA, long non-coding RNA, circular RNA), programmed cell death (apoptosis, necroptosis and pyroptosis), drugs and other pathophysiological aspects to provide new targets and ideas for the diagnosis and treatment of sepsis.

Adenovirus-α-defensin complexes induce NLRP3-associated maturation of human phagocytes via TLR4 engagement

Intramuscular delivery of human adenovirus (HAdV)-based vaccines leads to rapid recruitment of neutrophils, which then release antimicrobial peptides/proteins (AMPs). How these AMPs influence vaccine efficacy over the subsequent 24 h is poorly understood. In this study, we asked if human neutrophil protein 1 (HNP-1), an α-defensin that influences the direct and indirect innate immune responses to a range of pathogens, impacts the response of human phagocytes to three HAdV species/types (HAdV-C5, -D26, -B35). We show that HNP-1 binds to the capsids, redirects HAdV-C5, -D26, -B35 to Toll-like receptor 4 (TLR4), which leads to internalization, an NLRP3-mediated inflammasome response, and IL-1β release. Surprisingly, IL-1β release was not associated with notable disruption of plasma membrane integrity. These data further our understanding of HAdV vaccine immunogenicity and may provide pathways to extend the efficacy. Importance This study examines the interactions between danger-associated molecular patterns and human adenoviruses and its impact on vaccines. HAdVs and HNP-1 can interact, these interactions will modify the response of antigen-presenting cells., which will influence vaccine efficacy.

Intracellular translocation of HMGB1 is important for Zika virus replication in Huh7 cells

Neonatal microcephaly and adult Guillain-Barré syndrome are severe complications of Zika virus (ZIKV) infection. The robustly induced inflammatory cytokine expressions in ZIKV-infected patients may constitute a hallmark for severe disease. In the present study, the potential role of high mobility group box 1 protein (HMGB1) in ZIKV infection was investigated. HMGB1 protein expression was determined by the enzyme-linked immunosorbent assay (ELISA) and immunoblot assay. HMGB1's role in ZIKV infection was also explored using treatment with dexamethasone, an immunomodulatory drug, and HMGB1-knockdown (shHMGB1) Huh7 cells. Results showed that the Huh7 cells were highly susceptible to ZIKV infection. The infection was found to induce HMGB1 nuclear-to-cytoplasmic translocation, resulting in a > 99% increase in the cytosolic HMGB1 expression at 72-h post-infection (h.p.i). The extracellular HMGB1 level was elevated in a time- and multiplicity of infection (MOI)-dependent manner. Treatment of the ZIKV-infected cells with dexamethasone (150 µM) reduced HMGB1 extracellular release in a dose-dependent manner, with a maximum reduction of 71 ± 5.84% (P < 0.01). The treatment also reduced virus titers by over 83 ± 0.50% (P < 0.01). The antiviral effects, however, were not observed in the dexamethasone-treated shHMGB1 cells. These results suggest that translocation of HMGB1 occurred during ZIKV infection and inhibition of the translocation by dexamethasone coincided with a reduction in ZIKV replication. These findings highlight the potential of targeting the localization of HMGB1 in affecting ZIKV infection.

Increased circulating levels of High Mobility Group Box 1 (HMGB1) in acute-phase Chikungunya virus infection: Potential disease biomarker

BACKGROUND

Chikungunya virus (CHIKV) causes a febrile syndrome with intense and debilitating arthralgia that can persist for several months or years after complete virus clearance. As there is no specific antiviral treatment or vaccine against CHIKV, identification of serological markers that help clinical management of CHIKV patients is urgent. The High Mobility Group Box 1 (HMGB1) protein is secreted to extracellular milieu and triggers an intense inflammatory process by inducing the overexpression of pro-inflammatory cytokines. HMGB1 plays an important role in several virus diseases as well as in rheumatoid arthritis.

OBJECTIVES

This study focus on the investigation of HMGB1 serum levels in a sera panel from CHIKV-infected patients in an attempt to assess its potential as a biomarker for chikungunya clinical management.

STUDY DESIGN

Eighty CHIKV-positive samples and 32 samples from healthy donors were subjected to a quantitative HMGB1 ELISA assay to assess the HMGB1 circulating levels.

RESULTS

HMGB1 levels were significantly higher in CHIKV-positive samples (516.12 ng/mL, SEM ± 48.83 ng/mL) compared to negative control (31.20 ng/mL, SEM ± 3.24 ng/mL, p < 0.0001). Circulating levels of HMGB1 persisted elevated during the whole acute-phase of disease and correlated with virus titer (p < 0.05).

CONCLUSIONS

The present study is the first to describe increased serum levels of HMGB1 in CHIKV infection and its positive correlation with virus titer, suggesting its potential use as a biomarker for diagnosis and treatment of chikungunya fever.

Human lung cDC1 drive increased perforin-mediated NK cytotoxicity in Chronic Obstructive Pulmonary Disease

In chronic obstructive pulmonary disease (COPD), lung natural killer cells (NKs) lyse autologous lung epithelial cells in vitro, but underlying mechanisms and their relationship to epithelial cell apoptosis in vivo are undefined. Although this cytolytic capacity of lung NKs depends on priming by dendritic cells (DC), whether priming correlates with DC maturation or is limited to a specific DC subset are also unknown. We recruited ever-smokers (≥10 pack-years) (n=96) undergoing clinically-indicated lung resections. We analyzed lung NKs for cytotoxic molecule transcripts and for cytotoxicity, which we correlated with in situ detection of activated Caspase-3/7+ airway epithelial cells. To investigate DC priming, we measured lung DC expression of CCR2, CCR7, and CX3CR1, and co-cultured peripheral blood NKs with autologous lung DC, either matured using LPS (non-obstructed smokers) or separated into conventional DC type-1 (cDC1) versus cDC type-2 (cDC2) (COPD). Lung NKs in COPD expressed more perforin (p<0.02) and granzyme B (p<0.03) transcripts; inhibiting perforin blocked in vitro killing by lung NKs. Cytotoxicity in vitro correlated significantly (S_r=0.68, p=0.0043) with numbers of apoptotic epithelial cells per airway. In non-obstructed smokers, LPS-induced maturation enhanced DC-mediated priming of blood NKs, reflected by greater epithelial cell death. Although CCR7 expression was greater in COPD in both cDC1 (p<0.03) and cDC2 (p=0.009), only lung cDC1 primed NK killing. Thus, rather than being intrinsic to those with COPD, NK priming is a capacity of human lung DC that is inducible by recognition of bacterial (and possibly other) danger signals and restricted to the cDC1 subset.

Disulfide High-Mobility Group Box 1 Drives Ischemia-Reperfusion Injury in Human Liver Transplantation

BACKGROUND AND AIMS

Sterile inflammation is a major clinical concern during ischemia-reperfusion injury (IRI) triggered by traumatic events, including stroke, myocardial infarction, and solid organ transplantation. Despite high-mobility group box 1 (HMGB1) clearly being involved in sterile inflammation, its role is controversial because of a paucity of patient-focused research.

APPROACH AND RESULTS

Here, we examined the role of HMGB1 oxidation states in human IRI following liver transplantation. Portal blood immediately following allograft reperfusion (liver flush; LF) had increased total HMGB1, but only LF from patients with histopathological IRI had increased disulfide-HMGB1 and induced Toll-like receptor 4-dependent tumor necrosis factor alpha production by macrophages. Disulfide HMGB1 levels increased concomitantly with IRI severity. IRI+ prereperfusion biopsies contained macrophages with hyperacetylated, lysosomal disulfide-HMGB1 that increased postreperfusion at sites of injury, paralleling increased histone acetyltransferase general transcription factor IIIC subunit 4 and decreased histone deacetylase 5 expression. Purified disulfide-HMGB1 or IRI+ blood stimulated further production of disulfide-HMGB1 and increased proinflammatory molecule and cytokine expression in macrophages through a positive feedback loop.

CONCLUSIONS

These data identify disulfide-HMGB1 as a mechanistic biomarker of, and therapeutic target for, minimizing sterile inflammation during human liver IRI.

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.

High Mobility Group Box 1 in Human Cancer

High mobility group box 1 (HMGB1) is an extremely versatile protein that is located predominantly in the nucleus of quiescent eukaryotic cells, where it is critically involved in maintaining genomic structure and function. During cellular stress, however, this multifaceted, cytokine-like protein undergoes posttranslational modifications that promote its translocation to the cytosol, from where it is released extracellularly, either actively or passively, according to cell type and stressor. In the extracellular milieu, HMGB1 triggers innate inflammatory responses that may be beneficial or harmful, depending on the magnitude and duration of release of this pro-inflammatory protein at sites of tissue injury. Heightened awareness of the potentially harmful activities of HMGB1, together with a considerable body of innovative, recent research, have revealed that excessive production of HMGB1, resulting from misdirected, chronic inflammatory responses, appears to contribute to all the stages of tumorigenesis. In the setting of established cancers, the production of HMGB1 by tumor cells per se may also exacerbate inflammation-related immunosuppression. These pro-inflammatory mechanisms of HMGB1-orchestrated tumorigenesis, as well as the prognostic potential of detection of elevated expression of this protein in the tumor microenvironment, represent the major thrusts of this review.

Targeted delivery of Chil3/Chil4 siRNA to alveolar macrophages using ternary complexes composed of HMG and oligoarginine micelles

Cell-type-specific genes involved in disease can be effective therapeutic targets; therefore, the development of a cell-type-specific gene delivery system is essential. In this study, targeted delivery of Chil3 and Chil4 siRNA to activated macrophages was developed using a ligand called high mobility group (HMG) and oligoarginine (OR) micelles. HMG binds to TLR4 and RAGE located on the surface of activated macrophages. Since HMG is positively charged, it binds to the negatively charged siRNA by charge interaction. However, the stable formation of the siRNA/HMG complex requires an additional molecule to act as a carrier. In this study, OR micelles were used as the carrier. Gel retardation assays showed that siRNA, HMG, and OR micelles formed stable siRNA/HMG/OR micelle ternary complexes. In vitro transfection showed that the ternary complexes selectively delivered siRNA to TLR4 expressing macrophages. In addition, intratracheal administration of siRNA/HMG/OR ternary complexes delivered Chil3 and Chil4 siRNA specifically to alveolar macrophages. Furthermore, the siRNA that was delivered using ternary complexes reduced Chil3 and Chil4 expression and suppressed the symptoms of asthma, such as airway inflammation and mucin secretion.

Combination of NIR therapy and regulatory T cell modulation using layer-by-layer hybrid nanoparticles for effective cancer photoimmunotherapy

The efficacy of combined near-infrared (NIR) and immune therapies for inhibiting tumor growth and recurrence has gained increasing research attention. Regulatory T cells in the tumor microenvironment constitute a major obstacle in achieving robust CD8⁺ T cell antitumor immunotherapy. In the present study, we designed a photoimmunotherapy-based strategy involving a combination of photothermal and photodynamic therapies, followed by Treg cell suppression, for eliciting an immune response with IR-780- and imatinib-loaded layer-by-layer hybrid nanoparticles. Methods: The layer-by-layer hybrid nanoparticles were prepared through electrostatic interactions. Their photothermal effect, photodynamic effect as well as their effect on inhibiting Treg cells' suppressive function were investigated in vitro and in vivo. Their antitumor effect was evaluated using B16/BL6 and MC-38 tumor-bearing mice. Results: The layer-by-layer hybrid nanoparticles, which were pH-sensitive, enabled the release of IR-780 dye for NIR-induced photothermal and photodynamic effects, and the release of imatinib-loaded glucocorticoid-induced TNF receptor family-related protein/poly(lactic-co-glycolic acid) (GITR-PLGA) nanoparticles to initiate antitumor immunotherapy. The photothermal and photodynamic effects caused by IR-780 under NIR exposure resulted in direct tumor apoptosis/necrosis and the production of tumor-associated antigen, promoted dendritic cell maturation, and enhanced the presentation of tumor-associated antigen to T cells, while the imatinib-loaded GITR-PLGA cores reduced the suppressive function of Treg cells, and consequently activated effective CD8⁺ T cells towards tumors. Conclusion: With the significant photothermal, photodynamic and immunotherapies, the system successfully eradicated tumor growth, diminished tumor recurrence, and improved survival in vivo. The proposed nanoparticles provide a novel and versatile approach to boost antitumor photoimmunotherapy.

HMGB1 regulates T helper 2 and T helper17 cell differentiation both directly and indirectly in asthmatic mice

The Th (T helper) 2 response is characteristic of allergic asthma, and Th17 cells are involved in more severe asthma. Recent studies demonstrated that HMGB1 (High mobility group box 1 protein) regulates airway inflammation and the Th2, Th17 inflammatory response in asthma. HMGB1 can interact with Toll-like receptors (TLR) 2 and 4, and the receptor for advanced glycation end products (RAGE), activating the NF-κB (nuclear factor kappa B) signaling pathway and inducing the release of downstream inflammatory mediators. Both Th cells and dendritic cells express TLR2, TLR4, and RAGE receptors. Therefore, we speculate that HMGB1 could regulate the differentiation of Th2, Th17 cells in asthma through direct and indirect mechanisms. An ovalbumin (OVA)-induced mouse asthmatic model was established. Anti-HMGB1 antibody or rHMGB1 was administered to OVA-sensitized mice 30 min prior to each challenge. For in vitro studies, magnetically separated CD4⁺ naive T cells were stimulated with or without rHMGB1 and/or anti-HMGB1 antibody. BMDCs (bone marrow-derived dendritic cells)-stimulated with or without rHMGB1 and/or anti-HMGB1 antibody were cocultured with CD4⁺ naive T cells. Our study showed that administration of rHMGB1 aggravated airway inflammation and mucus production, and induced Th2, Th17 polarization in asthmatic mice, and that anti-HMGB1 antibody weakened characteristic features of asthma and blocked the Th2, Th17 inflammatory responses. HMGB1 could directly act on naive T cells to induce differentiation of Th2, Th17 cells in vitro through activating the TLR2, TLR4, RAGE-NF-κB signal pathway in CD4⁺ naive T cells. HMGB1 could also indirectly promote Th2, Th17 differentiation via activating the TLR2, TLR4, RAGE-NF-κB signal pathway in DCs to mediate their maturation and antigen-presenting ability in vitro.

High-Mobility Group Nucleosome-Binding Protein 1 as Endogenous Ligand Induces Innate Immune Tolerance in a TLR4-Sirtuin-1 Dependent Manner in Human Blood Peripheral Mononuclear Cells

High-mobility group nucleosome-binding protein 1 (HMGN1) functions as a non-histone chromatin-binding protein in the cell nucleus. However, extracellular HMGN1 acts as an endogenous danger-associated inflammatory mediator (also called alarmin). We demonstrated that HMGN1 not only directly stimulated cytokine production but also had the capacity to induce immune tolerance by a TLR4-dependent pathway, similar to lipopolysaccharide (LPS)-induced tolerance. HMGN1-induced tolerance was accompanied by a metabolic shift associated with the inhibition of the induction of Warburg effect (aerobic glycolysis) and histone deacetylation via Sirtuin-1. In addition, HMGN1 pre-challenge of mice also downregulated TNF production similar to LPS-induced tolerance in vivo. In conclusion, HMGN1 is an endogenous TLR4 ligand that can induce both acute stimulation of cytokine production and long-term tolerance, and thus it might play a modulatory role in sterile inflammatory processes such as those induced by infection, trauma, or ischemia.

Alarmins and central nervous system inflammation in HIV-associated neurological disorders

In the era of highly active antiretroviral therapy (HAART), HIV-1-associated neurocognitive disorders (HAND) persist in infected individuals with adequate immunological and virological status. Risk factors for cognitive impairment include hepatitis C virus co-infection, host genetic factors predisposing to HAND, the early establishment of the virus in the CNS and its persistence under HAART; thus, the CNS is an important reservoir for HIV. Microglial cells are permissive to HIV-1, and NLRP3 inflammasome-associated genes were found expressed in brains of HIV-1-infected persons, contributing to brain disease. Inflammasomes can be triggered by alarmins or danger-associated molecular patterns (DAMPs), which directly stimulate the production of proinflammatory mediators by glial cells, contribute to blood-brain barrier injury through induction of release of various proteases and allow the passage of infected macrophages, and trigger IL-1β release from primed cells. Amongst alarmins involved in HIV-1-induced neuropathogenesis, IL-33 and high-mobility group box 1 (HMGB1) are of particular interest. Neurocognitive alterations were recently associated with dysregulation of the IL-33/ST2 axis in the CNS, leading to the induction of neuronal apoptosis, decrease in synaptic function and neuroinflammation. Specific biomarkers, including HMGB1 and anti-HMGB1 antibodies, have been identified in cerebrospinal fluid from patients with HAND, correlated with immune activation and identifying a very early stage of neurocognitive impairment that precedes changes in metabolites detected by magnetic resonance spectroscopy. Moreover, HMGB1 plays a crucial role in HIV-1 persistence in dendritic cells and in the constitution of viral reservoirs. In this review, the mechanisms whereby alarmins contribute to HIV-1-induced CNS inflammation and neuropathogenesis will be discussed.

HMGB1/anti-HMGB1 antibodies define a molecular signature of early stages of HIV-Associated Neurocognitive Isorders (HAND)

BACKGROUND

HIV-associated neurocognitive disorders (HAND) persist in the post-HAART era, characterized by asymptomatic neurocognitive impairment (ANI) and mild neurocognitive disorders (MND). High mobility group box 1 (HMGB1) is a non-histone chromosomal protein widely expressed in the nucleus of all eukaryotic cells, including brain cells, which acts as a potent proinflammatory cytokine when actively secreted from immune cells. Recent reports suggested that HMGB1 acts on microglial cells to promote neuroinflammation. In this study, our aim was to determine whether HMGB1 is involved in HAND, but also to identify early new markers of neurological impairment in HIV-infected patients.

METHODS

CSF and serum were collected from 103 HIV-1-infected patients enrolled in Neuradapt, a prospective study of the prevalence of HAND in HIV-1 infected patients at Nice University Hospital. Stored fluids were assessed for immunological, virological, and brain metabolite parameters. In addition to HIV RNA and DNA measurements, expression of T-cell surface markers of activation (CD38 and HLA-DR) was analyzed on whole blood. Concentration of 27 cytokines and chemokines was measured using multiplex bead assays on serum and CSF. Concentration of HMGB1 and anti-HMGB1 IgG autoantibodies were also measured on the same samples. Changes in cerebral metabolites N-acetyl aspartate (NAA), Choline (Cho) and creatinine (Cr) were assessed by magnetic resonance microscopy (MRS).

RESULTS

Clinical, virological and immunological characteristics were comparable between HAND (n = 30) and no HAND (n = 73) patients, except the absolute numbers of CD8⁺ T cells, which were higher in patients with HAND. Among the 29 molecules tested, only 4 of them were significantly upregulated in the CSF from HAND patients as compared to healthy donors i.e. HMGB1, anti-HMGB1 IgG antibodies, IP-10 and MCP1. CSF HMGB1 levels were positively correlated with HIV-1 DNA in aviremic HAND patients, suggesting a positive impact of HMGB1 on HIV reservoirs. Moreover, in contrast to NAA/Cr and Cho/NAA ratios, circulating anti-HMGB1 IgG antibody levels could discriminate patients with no HAND from patients with no HAND and a single deficit (average ROC-AUC = 0.744, p = 0.03 for viremic patients), thus enabling the identification of a very early stage of neurocognitive impairment.

CONCLUSION

We report that brain injury in chronically HIV-infected patients on stable HAART is strongly associated with persistent CNS inflammation, which is correlated with increased levels of HMGB1 and anti-HMGB1 IgG in the CSF. Moreover, we identified circulating anti-HMGB1 IgG as a very early biomarker of neurological impairment in patients without HAND. These results might have important implication for the identification of patients who are at high risk of developing neurological disorders.

Diagnostic Value of High-Mobility Group Box 1 (HMGB1) Protein in Acute and Perforated Appendicitis

AIM

Acute appendicitis is the most common cause of abdominal surgical emergencies. Early diagnosis of appendicitis can reduce perforation and mortality rate. High-mobility group box 1 (HMGB1) protein has been identified as a pro-inflammatory factor and its elevated serum levels have been noted in different diseases. So, the aim of this study was to determine the serum levels of HMGB1 in patients with acute and perforated appendicitis in compare to normal appendix.

MATERIAL AND METHODS

For this purpose, serum samples were obtained from 81 patients with primary criteria-based appendicitis 6 hr before and 72 hr after appendectomy, in which serum levels of HMGB1 were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The levels of HMGB1 in patients with perforated appendicitis were significantly (p =.045) higher than in patients with acute appendicitis and normal appendix (p =.001) before appendectomy. Serum levels of HMGB1 were increased 72 hr after appendectomy in all the groups (p =.03) compared with the serum levels before appendectomy.

CONCLUSIONS

Since the serum levels of HMGB1 in patients with acute and perforated appendicitis were higher than in patients with normal appendix, these findings could be useful to develop a new biomarker along with other laboratory tests for accurate diagnosis of patients with appendicitis.

The Initial Months of Antiretroviral Therapy and Its Influence on AGEs, HMGB1, and sRAGE Levels in Asymptomatic HIV-Infected Individuals

The development of the typical comorbidities of aging which currently affects people living with HIV/AIDS (PLWHA) can be partially ascribed to the persistent immune activation and chronic inflammation characterizing these individuals. The aim of this study was to analyze the effect exerted by combined antiretroviral therapy (cART) administration on plasma levels of HMGB1 (high mobility group box protein-1), AGEs (advanced glycation end products), their soluble receptor sRAGE, cytokines, C-reactive protein (CRP), and some metabolic markers in asymptomatic PLWHA. Analyses were performed longitudinally in 30 PLWHA, before and about 6–12 months after cART initiation. We observed that lower levels of AGEs in post-cART group were accompanied by an increase of CRP and triglyceride levels already in the early months of therapy. Because of the current ever-earlier recommendations to start cART and its prolonged use, these and other markers should be investigated in order to monitor and postpone the appearance of non-AIDS comorbidities in PLWHA.

Translocation of Endogenous Danger Signal HMGB1 From Nucleus to Membrane Microvesicles in Macrophages

High mobility group box 1 (HMGB1) is a nuclear protein that can be released from activated or dead cells. Extracellular HMGB1 can serve as a "danger signal" and novel cytokine that mediates sterile inflammation. In addition to its soluble form, extracellular HMGB1 can also be carried by membrane microvesicles. However, the cellular mechanisms responsible for nuclear HMGB1 translocation to the plasma membrane and release onto membrane microvesicles have not been investigated. Tobacco smoking is a major cause of sterile inflammation in many diseases. Smoking also increases blood levels of HMGB1. In this study, we found that exposure of macrophages to tobacco smoke extract (TSE) stimulated HMGB1 expression, redistribution, and release into the extracellular milieu both as a soluble molecule and, surprisingly, as a microvesicle-associated form (TSE-MV). Inhibition of chromosome region maintenance-1 (CRM1), a nuclear exporter, attenuated TSE-induced HMGB1 redistribution from the nucleus to the cytoplasm, and then its release on TSE-MVs. Our study demonstrates a novel mechanism for the translocation of nuclear HMGB1 to the plasma membrane, and then its release in a microvesicle-associated form. J. Cell. Physiol. 231: 2319-2326, 2016. © 2016 Wiley Periodicals, Inc.

PEGylated Copper Nanowires as a Novel Photothermal Therapy Agent

Metal nanowires are promising for their applications including electrical connectors, transparent conductive electrodes and conductive additives, but the use of metal nanowires as photothermal agents to convert light to heat has yet to be reported. Here we synthesized dispersible polyethylene glycol-coated (PEGylated) copper nanowires (CuNWs) and showed for the first time that PEGylated CuNWs were able to convert near-infrared (NIR, 808 nm) light into heat at a photothermal efficiency of 12.5%. The PEGylated CuNWs exhibited good reusability and enabled rapid temperature rise to >50 °C in 6 min by NIR irradiation. The PEGylated CuNWs were flexible and intertwined around the cancer cells, which, upon NIR irradiation, allowed for direct heat transmission to cells and effectively triggered cancer cell ablation in vitro. Intratumoral injection of PEGylated CuNWs into colon tumor-bearing mice and ensuing NIR irradiation for 6 min significantly raised the local temperature to >50 °C, induced necrosis, and suppressed tumor growth. Compared with other NIR light absorbing noble metal-based nanomaterials, PEGylated CuNWs are relatively easy to synthesize in both laboratory and large scales using the low cost copper. This study demonstrated the potential of PEGylated CuNWs as a new cost-effective photothermal agent, and paved a new avenue to using CuNWs for cancer therapy.

Key Role of DAMP in Inflammation, Cancer, and Tissue Repair

PURPOSE

This review aimed to take stock of the current status of research on damage-associated molecular pattern (DAMP) protein. We discuss the Janus-faced role of DAMP molecules in inflammation, cancer, and tissue repair. The high-mobility group box (HMGB)-1 and adenosine triphosphate proteins are well-known DAMP molecules and have been primarily associated with inflammation. However, as we shall see, recent data have linked these molecules to tissue repair. HMGB1 is associated with cancer-related inflammation. It activates nuclear factor kB, which is involved in cancer regulation via its receptor for advanced glycation end-products (RAGE), Toll-like receptors 2 and 4. Proinflammatory activity and tissue repair may lead to pharmacologic intervention, by blocking DAMP RAGE and Toll like receptor 2 and 4 role in inflammation and by increasing their concentration in tissue repair, respectively.

METHODS

We conducted a MEDLINE search for articles pertaining to the various issues related to DAMP, and we discuss the most relevant articles especially (ie, not only those published in journals with a higher impact factor).

FINDINGS

A cluster of remarkable articles on DAMP have appeared in the literature in recent years. Regarding inflammation, several strategies have been proposed to target HMGB1, from antibodies to recombinant box A, which interacts with RAGE, competing with the full molecule. In tissue repair, it was reported that the overexpression of HMGB1 or the administration of exogenous HMGB1 significantly increased the number of vessels and promoted recovery in skin-wound, ischemic injury.

IMPLICATIONS

Due to the bivalent nature of DAMP, it is often difficult to explain the relative role of DAMP in inflammation versus its role in tissue repair. However, this point is crucial as DAMP-related treatments move into clinical practice.

HMGB1 Is Involved in IFN-α Production and TRAIL Expression by HIV-1-Exposed Plasmacytoid Dendritic Cells: Impact of the Crosstalk with NK Cells

Plasmacytoid dendritic cells (pDCs) are innate sensors of viral infections and important mediators of antiviral innate immunity through their ability to produce large amounts of IFN-α. Moreover, Toll-like receptor 7 (TLR7) and 9 (TLR9) ligands, such as HIV and CpG respectively, turn pDCs into TRAIL-expressing killer pDCs able to lyse HIV-infected CD4⁺ T cells. NK cells can regulate antiviral immunity by modulating pDC functions, and pDC production of IFN-α as well as cell–cell contact is required to promote NK cell functions. Impaired pDC-NK cell crosstalk was reported in the setting of HIV-1 infection, but the impact of HIV-1 on TRAIL expression and innate antiviral immunity during this crosstalk is unknown. Here, we report that low concentrations of CCR5-tropic HIV-1_Ba-L promote the release of pro-inflammatory cytokines such as IFN-α, TNF-α, IFN-γ and IL-12, and CCR5-interacting chemokines (MIP-1α and MIP-1β) in NK-pDCs co-cultures. At high HIV-1_BaL concentrations, the addition of NK cells did not promote the release of these mediators, suggesting that once efficiently triggered by the virus, pDCs could not integrate new activating signals delivered by NK cells. However, high HIV-1_BaL concentrations were required to trigger IFN-α-mediated TRAIL expression at the surface of both pDCs and NK cells during their crosstalk. Interestingly, we identified the alarmin HMGB1, released at pDC-NK cell synapse, as an essential trigger for the secretion of IFN-α and IFN-related soluble mediators during the interplay of HIV-1 exposed pDCs with NK cells. Moreover, HMGB1 was found crucial for mTRAIL translocation to the plasma membrane of both pDCs and NK cells during their crosstalk following pDC exposure to HIV-1. Data from serum analyses of circulating HMGB1, HMGB1-specific antibodies, sTRAIL and IP-10 in a cohort of 67 HIV-1⁺ patients argue for the in vivo relevance of these observations. Altogether, these findings identify HMGB1 as a trigger for IFN-α-mediated TRAIL expression at the surface of pDCs and NK cells, and they suggest a novel mechanism of innate control of HIV-1 infection.

Plasmacytoid dendritic cells (pDC) are the most potent IFN-α-producing cells and serve as an essential link between innate and adaptive immunity. Exposure of pDCs to HIV-1 triggers IFN-α production, which in turn upregulates TNF-related apoptosis-inducing ligand (TRAIL), turning pDCs into killer pDCs, able to kill infected CD4⁺ T cells. At sites of infection, pDCs might activate or get activated by Natural killer (NK) cells, and pDC-NK cell-cell contact is required to promote the cytolytic potential of NK cells. Functional defects in the pDC and NK cell compartments were reported in the setting of HIV-1 infection, but the precise mechanisms by which HIV impairs NK cell and pDC crosstalk remain to be fully elucidated. To address this question, we developed an ex-vivo model of NK-pDC interaction, based on a short-term contact between sorted peripheral NK cells and purified pDCs exposed to HIV-1_BaL. We found that the concentration of HIV-1 is critical to sustain the functional activation of both pDCs and NK cells. Moreover, we identified the alarmin HMGB1 as an essential trigger for the secretion of IFN-α and IFN-related soluble mediators during the interplay of HIV-1-exposed pDCs and NK cells. HMGB1 was also found crucial for HIV-1-induced translocation of TRAIL on both pDC and NK cell membrane. The in vivo relevance of the interdependency between HMGB1, IFN- and TRAIL is suggested by the strong positive correlations between circulating levels of these mediators in a cohort of 67 HIV-1 infected patients. Altogether these findings highlight a new function for HMGB1 and they suggest a novel mechanism of innate control of HIV infection.

HMGB1 Promotes Hepatitis C Virus Replication by Interaction with Stem-Loop 4 in the Viral 5' Untranslated Region

High-mobility group box 1 (HMGB1) protein is a highly conserved nuclear protein involved in multiple human diseases, including infectious diseases, immune disorders, metabolic disorders, and cancer. HMGB1 is comprised of two tandem HMG boxes (the A box and the B box) containing DNA-binding domains and an acidic C-terminal peptide. It has been reported that HMGB1 enhances viral replication by binding to viral proteins. However, its role in hepatitis C virus (HCV) replication is unknown. Here, we show that HMGB1 promoted HCV replication but had no effect on HCV translation. RNA immunoprecipitation experiments indicated that the positive strand, not the negative strand, of HCV RNA interacted with HMGB1. HCV infection triggered HMGB1 protein translocation from the nucleus to the cytoplasm, in which it interacted with the HCV genome. Moreover, the A box of HMGB1 is the pivotal domain to interact with stem-loop 4 (SL4) of the HCV 5' untranslated region. Deletion of the HMGB1 A box abrogated the enhancement of HCV replication by HMGB1. Our data suggested that HMGB1 serves as a proviral factor of HCV to facilitate viral replication in hepatocytes by interaction with the HCV genome.

IMPORTANCE

Hepatitis C virus (HCV) is a major global health threat, affecting more than 170 million people infection worldwide. These patients are at high risk of developing severe liver diseases such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Currently, no vaccine is available. Many host factors may be implicated in the pathogenesis of HCV-related diseases. In this study, we found a novel HCV RNA-binding protein, HMGB1, that promotes HCV RNA replication. Moreover, SL4 in the 5' untranslated region of the HCV genome is the key region for HMGB1 binding, and the A box of HMGB1 protein is the functional domain to interact with HCV RNA and enhance viral replication. HMGB1 appears to play an important role in HCV-related diseases, and further investigation is warranted to elucidate the specific actions of HMGB1 in HCV pathogenesis.

Role of Bruton's tyrosine kinase inhibitors in HIV-1-infected cells

Many cellular cofactors have been documented to be critical for various stages of viral replication. Using high-throughput proteomic assays, we have previously identified Bruton's tyrosine kinase (BTK) as a host protein that was uniquely upregulated in the plasma membrane of human immunodeficiency virus (HIV-1)-infected T cells. Here, we have further characterized the BTK expression in HIV-1 infection and show that this cellular factor is specifically expressed in infected myeloid cells. Significant upregulation of the phosphorylated form of BTK was observed in infected cells. Using size exclusion chromatography, we found BTK to be virtually absent in the uninfected U937 cells; however, new BTK protein complexes were identified and distributed in both high molecular weight (∼600 kDa) and a small molecular weight complex (∼60-120 kDa) in the infected U1 cells. BTK levels were highest in cells either chronically expressing virus or induced/infected myeloid cells and that BTK translocated to the membrane following induction of the infected cells. BTK knockdown in HIV-1-infected cells using small interfering RNA (siRNA) resulted in selective death of infected, but not uninfected, cells. Using BTK-specific antibody and small-molecule inhibitors including LFM-A13 and a FDA-approved compound, ibrutinib (PCI-32765), we have found that HIV-1-infected cells are sensitive to apoptotic cell death and result in a decrease in virus production. Overall, our data suggests that HIV-1-infected cells are sensitive to treatments targeting BTK expressed in infected cells.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Dynamic localization and the associated translocation mechanism of HMGBs in response to GCRV challenge in CIK cells

High-mobility group box (HMGB) proteins, a family of chromatin-associated nuclear proteins, play amazingly multifaceted roles in the immune system of mammals. Thus far, little is known about the nucleocytoplasmic distribution of HMGBs in teleosts. The present study systematically investigated the dynamic localization of all six HMGB proteins in Ctenopharyngodon idella kidney (CIK) cells. Under basal conditions, all HMGBs exclusively localized to the nucleus. Grass carp reovirus (GCRV), polyinosinic-polycytidylic (poly(I∶C)) potassium salt and lipopolysaccharide (LPS) challenge evoked the nuclear export of HMGBs to various degrees: GCRV challenge induced the highest nuclear export of CiHMGB2b, and poly(I∶C) and LPS evoked the highest nucleocytoplasmic shuttling of CiHMGB1b. Overall, the nucleocytoplasmic shuttling of CiHMGB2a and CiHMGB3b was rarely induced by these challenges. Dynamic imaging uncovered that the nucleocytoplasmic GCRV-induced relocation of CiHMGB2b occurred in cells undergoing karyotheca rupture, apoptosis or proliferation. Western blot analyses were used to examine HMGB-EGFP fusion proteins in whole cell lysates, cytosol, nuclear fractions and culture medium. Further investigation demonstrated the nuclear retention of N-terminal HMG-boxes and the nucleocytoplasmic distribution of the C-terminal acidic tails. Comparative analyses of the dynamic relocation of full-length, truncated or chimeric HMGBs confirmed that the intramolecular interaction between HMG-boxes and C-tail domains mediated the nucleocytoplasmic translocation of HMGBs. These results not only provide an overall understanding of the subcellular localization of HMGBs, but also reveal the induction mechanism of the nucleocytoplasmic translocation of HMGBs by GCRV challenge, which lays a foundation for further studies on the interactions among pathogens, HMGBs and pattern recognition receptors in the innate immunity of teleosts.

Increased plasma cell-free DNA level during HTNV infection: correlation with disease severity and virus load

Cell-free DNA (cf-DNA) in blood represents a promising DNA damage response triggered by virus infection or trauma, tumor, etc. Hantavirus primarily causes two diseases: haemorrhagic fever with renal syndrome (HFRS) and Hantavirus cardiopulmonary syndrome (HCPS), depending on different Hantavirus species. The aim of this study was to evaluate plasma cf-DNA levels in acute phase of HFRS, and to correlate plasma cf-DNA with disease severity and plasma Hanttan virus (HTNV) load. We observed the appearance of cf-DNA in 166 plasma samples from 76 HFRS patients: the plasma cf-DNA levels peaked at the hypotensive stage of HFRS, and then decreased gradually. Until the diuretic stage, there was no significant difference in plasma cf-DNA level between patients and the healthy control. Exclusively in the febrile/hypotensive stage, the plasma cf-DNA levels of severe/critical patients were higher than those of the mild/moderate group. Moreover, the plasma cf-DNA value in the early stage of HFRS was correlated with HTNV load and disease severity. In most of the patients, plasma cf-DNA displayed a low-molecular weight appearance, corresponding to the size of apoptotic DNA. In conclusion, the plasma cf-DNA levels were dynamically elevated during HFRS, and correlated with disease severity, which suggests that plasma cf-DNA may be a potential biomarker for the pathogenesis and prognosis of HFRS.

Genome-wide analysis of primary peripheral blood mononuclear cells from HIV + patients-pre-and post- HAART show immune activation and inflammation the main drivers of host gene expression

BACKGROUND

Although the host gene expression in the context of HIV has been explored by several studies, it remains unclear how HIV is able to manipulate and subvert host gene machinery before and after highly active antiretroviral therapy (HAART) in the same individual. In order to define the underlying pharmaco-genomic basis of HIV control during HAART and genomic basis of immune deterioration prior to HAART initiation, we performed a genome-wide expression analysis using primary peripheral blood mononuclear cells (PBMC) derived from 14 HIV + subjects pre-highly active antiretroviral therapy (HAART) (time point-1 or TP1) with detectable plasma viremia and post-HAART (time point-2 or TP2) with effective control of plasma viremia (<40 HIV RNA copies/mL of plasma).

METHODS

Genomic RNA extracted from the PBMCs was used in microarray analysis using HT-12V3 Illumina chips. Illumina®BeadStudio Software was used to obtain differentially expressed (DE) genes. Only the genes with p value <0.01 and FDR of <5% were considered for analysis. Pathway analysis was performed in MetaCore™ to derive functional annotations. Functionally significant genes were validated by qRT-PCR.

RESULTS

Between TP1 and TP2, 234 genes were differentially expressed (DE). During viremic phase (TP1), there was an orchestrated and coordinated up-regulation of immune, inflammation and antiviral genes, consistent with HIV infection and immune activation, which comprised of genes mainly involved in antiviral action of interferons and their signalling. In contrast, the therapy-mediated control phase (TP2) showed systematic down-regulation of these pathways, suggesting that the reduction in plasma viremia with HAART has a considerable influence on reducing the immune activation, thereby implying a definitive role of HIV in subverting the human gene machinery.

CONCLUSIONS

This is the first study to show the evidence for the differential regulation of gene expression between the untreated and treated time points, suggesting that gene expression is a consequence of cellular activation during plasma viremia. Affirmation to these observations comes from down-modulation of genes involved in cellular activation and inflammation upon initiation of HAART coinciding with below detectable levels of plasma viremia.

Genome-wide analysis of primary peripheral blood mononuclear cells from HIV + patients-pre-and post- HAART show immune activation and inflammation the main drivers of host gene expression

Background

Although the host gene expression in the context of HIV has been explored by several studies, it remains unclear how HIV is able to manipulate and subvert host gene machinery before and after highly active antiretroviral therapy (HAART) in the same individual. In order to define the underlying pharmaco-genomic basis of HIV control during HAART and genomic basis of immune deterioration prior to HAART initiation, we performed a genome-wide expression analysis using primary peripheral blood mononuclear cells (PBMC) derived from 14 HIV + subjects pre-highly active antiretroviral therapy (HAART) (time point-1 or TP1) with detectable plasma viremia and post-HAART (time point-2 or TP2) with effective control of plasma viremia (<40 HIV RNA copies/mL of plasma).

Methods

Genomic RNA extracted from the PBMCs was used in microarray analysis using HT-12V3 Illumina chips. Illumina®BeadStudio Software was used to obtain differentially expressed (DE) genes. Only the genes with p value <0.01 and FDR of <5% were considered for analysis. Pathway analysis was performed in MetaCore™ to derive functional annotations. Functionally significant genes were validated by qRT-PCR.

Results

Between TP1 and TP2, 234 genes were differentially expressed (DE). During viremic phase (TP1), there was an orchestrated and coordinated up-regulation of immune, inflammation and antiviral genes, consistent with HIV infection and immune activation, which comprised of genes mainly involved in antiviral action of interferons and their signalling. In contrast, the therapy-mediated control phase (TP2) showed systematic down-regulation of these pathways, suggesting that the reduction in plasma viremia with HAART has a considerable influence on reducing the immune activation, thereby implying a definitive role of HIV in subverting the human gene machinery.

Conclusions

This is the first study to show the evidence for the differential regulation of gene expression between the untreated and treated time points, suggesting that gene expression is a consequence of cellular activation during plasma viremia. Affirmation to these observations comes from down-modulation of genes involved in cellular activation and inflammation upon initiation of HAART coinciding with below detectable levels of plasma viremia.

Electronic supplementary material

The online version of this article (doi:10.1186/2052-8426-2-11) contains supplementary material, which is available to authorized users.

Complementary induction of immunogenic cell death by oncolytic parvovirus H-1PV and gemcitabine in pancreatic cancer

Novel therapies employing oncolytic viruses have emerged as promising anticancer modalities. The cure of particularly aggressive malignancies requires induction of immunogenic cell death (ICD), coupling oncolysis with immune responses via calreticulin, ATP, and high-mobility group box protein B1 (HMGB1) release from dying tumor cells. The present study shows that in human pancreatic cancer cells (pancreatic ductal adenocarcinoma [PDAC] cells n=4), oncolytic parvovirus H-1 (H-1PV) activated multiple interconnected death pathways but failed to induce calreticulin exposure or ATP release. In contrast, H-1PV elevated extracellular HMGB1 levels by 4.0±0.5 times (58%±9% of total content; up to 100 ng/ml) in all infected cultures, whether nondying, necrotic, or apoptotic. An alternative secretory route allowed H-1PV to overcome the failure of gemcitabine to trigger HMGB1 release, without impeding cytotoxicity or other ICD activities of the standard PDAC medication. Such broad resistance of H-1PV-induced HMGB1 release to apoptotic blockage coincided with but was uncoupled from an autocrine interleukin-1β (IL-1β) loop. That and the pattern of viral determinants maintained in gemcitabine-treated cells suggested the activation of an inflammasome/caspase 1 (CASP1) platform alongside DNA detachment and/or nuclear exclusion of HMGB1 during early stages of the viral life cycle. We concluded that H-1PV infection of PDAC cells is signaled through secretion of the alarmin HMGB1 and, besides its own oncolytic effect, might convert drug-induced apoptosis into an ICD process. A transient arrest of cells in the cyclin A1-rich S phase would suffice to support compatibility of proliferation-dependent H-1PV with cytotoxic regimens. These properties warrant incorporation of the oncolytic virus H-1PV, which is not pathogenic in humans, into multimodal anticancer treatments.

IMPORTANCE

The current therapeutic concepts targeting aggressive malignancies require an induction of immunogenic cell death characterized by exposure of calreticulin (CRT) as well as release of ATP and HMGB1 from dying cells. In pancreatic tumor cells (PDAC cells) infected with the oncolytic parvovirus H-1PV, only HMGB1 was released by all infected cells, whether nondying, necrotic, or succumbing to one of the programmed death pathways, including contraproductive apoptosis. Our data suggest that active secretion of HMGB1 from PDAC cells is a sentinel reaction emerging during early stages of the viral life cycle, irrespective of cell death, that is compatible with and complements cytotoxic regimens. Consistent induction of HMGB1 secretion raised the possibility that this reaction might be a general "alarming" phenomenon characteristic of H-1PV's interaction with the host cell; release of IL-1β points to the possible involvement of a danger-sensing inflammasome platform. Both provide a basis for further virus-oriented studies.

Blood dendritic cells: "canary in the coal mine" to predict chronic inflammatory disease?

The majority of risk factors for chronic inflammatory diseases are unknown. This makes personalized medicine for assessment, prognosis, and choice of therapy very difficult. It is becoming increasingly clear, however, that low-grade subclinical infections may be an underlying cause of many chronic inflammatory diseases and thus may contribute to secondary outcomes (e.g., cancer). Many diseases are now categorized as inflammatory-mediated diseases that stem from a dysregulation in host immunity. There is a growing need to study the links between low-grade infections, the immune responses they elicit, and how this impacts overall health. One such link explored in detail here is the extreme sensitivity of myeloid dendritic cells (mDCs) in peripheral blood to chronic low-grade infections and the role that these mDCs play in arbitrating the resulting immune responses. We find that emerging evidence supports a role for pathogen-induced mDCs in chronic inflammation leading to increased risk of secondary clinical disease. The mDCs that are elevated in the blood as a result of low-grade bacteremia often do not trigger a productive immune response, but can disseminate the pathogen throughout the host. This aberrant trafficking of mDCs can accelerate systemic inflammatory disease progression. Conversely, restoration of dendritic cell homeostasis may aid in pathogen elimination and minimize dissemination. Thus it would seem prudent when assessing chronic inflammatory disease risk to consider blood mDC numbers, and the microbial content (microbiome) and activation state of these mDCs. These may provide important clues (“the canary in the coal mine”) of high inflammatory disease risk. This will facilitate development of novel immunotherapies to eliminate such smoldering infections in atherosclerosis, cancer, rheumatoid arthritis, and pre-eclampsia.

Cytokine networking of innate immunity cells: a potential target of therapy

Innate immune cells, particularly macrophages and epithelial cells, play a key role in multiple layers of immune responses. Alarmins and pro-inflammatory cytokines from the IL (interleukin)-1 and TNF (tumour necrosis factor) families initiate the cascade of events by inducing chemokine release from bystander cells and by the up-regulation of adhesion molecules required for transendothelial trafficking of immune cells. Furthermore, innate cytokines produced by dendritic cells, macrophages, epithelial cells and innate lymphoid cells seem to play a critical role in polarization of helper T-cell cytokine profiles into specific subsets of Th1/Th2/Th17 effector cells or regulatory T-cells. Lastly, the innate immune system down-regulates effector mechanisms and restores homoeostasis in injured tissue via cytokines from the IL-10 and TGF (transforming growth factor) families mainly released from macrophages, preferentially the M2 subset, which have a capacity to induce regulatory T-cells, inhibit the production of pro-inflammatory cytokines and induce healing of the tissue by regulating extracellular matrix protein deposition and angiogenesis. Cytokines produced by innate immune cells represent an attractive target for therapeutic intervention, and multiple molecules are currently being tested clinically in patients with inflammatory bowel disease, rheumatoid arthritis, systemic diseases, autoinflammatory syndromes, fibrosing processes or malignancies. In addition to the already widely used blockers of TNFα and the tested inhibitors of IL-1 and IL-6, multiple therapeutic molecules are currently in clinical trials targeting TNF-related molecules [APRIL (a proliferation-inducing ligand) and BAFF (B-cell-activating factor belonging to the TNF family)], chemokine receptors, IL-17, TGFβ and other cytokines.

Mucosal immunization with high-mobility group box 1 in chitosan enhances DNA vaccine-induced protection against coxsackievirus B3-induced myocarditis

Coxsackievirus B3 (CVB3), a small single-stranded RNA virus, belongs to the Picornaviridae family. Its infection is the most common cause of myocarditis, with no vaccine available. Gastrointestinal mucosa is the major entry port for CVB3; therefore, the induction of local immunity in mucosal tissues may help control initial viral infections and alleviate subsequent myocardial injury. Here we evaluated the ability of high-mobility group box 1 (HMGB1) encapsulated in chitosan particles to enhance the mucosal immune responses induced by the CVB3-specific mucosal DNA vaccine chitosan-pVP1. Mice were intranasally coimmunized with 4 doses of chitosan-pHMGB1 and chitosan-pVP1 plasmids, at 2-week intervals, and were challenged with CVB3 4 weeks after the last immunization. Compared with chitosan-pVP1 immunization alone, coimmunization with chitosan-pHMGB1 significantly (P < 0.05) enhanced CVB3-specific fecal secretory IgA levels and promoted mucosal T cell immune responses. In accordance, reduced severity of myocarditis was observed in coimmunized mice, as evidenced by significantly (P < 0.05) reduced viral loads, decreased myocardial injury, and increased survival rates. Flow cytometric analysis indicated that HMGB1 enhanced dendritic cell (DC) recruitment to mesenteric lymph nodes and promoted DC maturation, which might partly account for its mucosal adjuvant effect. This strategy may represent a promising approach to candidate vaccines against CVB3-induced myocarditis.

Inflammation triggers high mobility group box 1 (HMGB1) secretion in adipose tissue, a potential link to obesity

BACKGROUND

Low grade inflammation is one of the major metabolic disorders in case of obesity due to variable secretion of adipose derived cytokines called adipokines. Recently the nuclear protein HMGB1 was identified as an inflammatory alarmin in obesity associated diseases. However HMGB1 role in adipose tissue inflammation is not yet studied.

OBJECTIVES

The aim of this study was to prove the expression of HMGB1 in human adipose tissue and to assess the levels of expression between normo-weight and obese individuals. Furthermore we determined which type of cells within adipose tissue is involved in HMGB1 production under inflammatory signal.

METHODS

Western-blot was performed on protein lysates from human normo-weight and obese adipose tissue to study the differential HMGB1 expression. Human normo-weight adipose tissue, adipose-derived stromal cells (ASCs) and adipocytes were cultured and stimulated with LPS to induce inflammation. HMGB1, IL-6 and MCP-1 secretion and gene expression were quantified by ELISA and Q-PCR respectively, as well as cell death by LDH assay. HMGB1 translocation during inflammation was tracked down by immunofluorescence in ASCs.

RESULTS

HMGB1 was expressed 2-fold more in adipose tissue from obese compared to normo-weight individuals. LPS led to an up-regulation in HMGB1 secretion and gene expression in ASCs, while no change was noticed in adipocytes. Moreover, this HMGB1 release was not attributable to any cell death. In LPS-stimulated ASCs, HMGB1 translocation from nucleus to cytoplasm was detectable at 12h and the nuclear HMGB1 was completely drained out after 24h of treatment.

CONCLUSION

The expression level studies between adipose tissue from normo-weight and obese individuals together with in vitro results strongly suggest that adipose tissue secretes HMGB1 in response to inflammatory signals which characterized obesity.

Interferon-beta induces distinct gene expression response patterns in human monocytes versus T cells

Background

Monocytes, which are key players in innate immunity, are outnumbered by neutrophils and lymphocytes among peripheral white blood cells. The cytokine interferon-β (IFN-β) is widely used as an immunomodulatory drug for multiple sclerosis and its functional pathways in peripheral blood mononuclear cells (PBMCs) have been previously described. The aim of the present study was to identify novel, cell-specific IFN-β functions and pathways in tumor necrosis factor (TNF)-α-activated monocytes that may have been missed in studies using PBMCs.

Methodology/Principal Findings

Whole genome gene expression profiles of human monocytes and T cells were compared following in vitro priming to TNF-α and overnight exposure to IFN-β. Statistical analyses of the gene expression data revealed a cell-type-specific change of 699 transcripts, 667 monocyte-specific transcripts, 21 T cell-specific transcripts and 11 transcripts with either a difference in the response direction or a difference in the magnitude of response. RT-PCR revealed a set of differentially expressed genes (DEGs), exhibiting responses to IFN-β that are modulated by TNF-α in monocytes, such as RIPK2 and CD83, but not in T cells or PBMCs. Known IFN-β promoter response elements, such as ISRE, were enriched in T cell DEGs but not in monocyte DEGs. The overall directionality of the gene expression regulation by IFN-β was different in T cells and monocytes, with up-regulation more prevalent in T cells, and a similar extent of up and down-regulation recorded in monocytes.

Conclusions

By focusing on the response of distinct cell types and by evaluating the combined effects of two cytokines with pro and anti-inflammatory activities, we were able to present two new findings First, new IFN-β response pathways and genes, some of which were monocytes specific; second, a cell-specific modulation of the IFN-β response transcriptome by TNF-α.

Immunotoxicological impact of engineered nanomaterial exposure: mechanisms of immune cell modulation

Abstract Engineered nanomaterials (ENMs) are increasingly being utilized in many consumer products and various medical applications, thereby leading to the potentiality of increased human exposures. Assessment of the adverse effects on the immune system is an important component for evaluating the overall health and safety of ENM. Tasked with eliminating pathogens and removing cancerous cells, the immune system is constantly functioning to maintain homeostasis. Small modifications to the immune system, which may occur following ENM exposure, could lead to impaired protection or an inappropriate immune response resulting in autoimmunity and damage to the host. This review seeks to survey and evaluate the current literature to better understand the impact of ENM exposure on cells critical to the innate and adaptive immune systems.

Understanding factors that modulate HIV infection at the female genital tract mucosae for the rationale design of microbicides

Women are now becoming the pivot of the epidemiological spread of HIV infection worldwide, especially in developing countries. Therefore, research to develop an efficient microbicide is now a priority for the prevention of HIV-1 acquisition in exposed women. However, recent disappointing failures in microbicide clinical trials revealed major gaps in basic and applied knowledge that hinder the development of effective microbicide formulations. Indeed, the inhibitory power of microbicide molecules may be affected by several physiological and immunological factors present in male and female genital tracts. Furthermore, mucosal crossing of HIV-1 to increase the ability to reach the submucosal target cells (macrophages, lymphocytes, and dendritic cells) may be modulated by supraepithelial factors such as seminal complement components (opsonized HIV-1), by epithelial factors released in the submucosal microenvironment such as antimicrobial soluble factors, cytokines, and chemokines, and by potent intraepithelial and submucosal innate immunity. The design of vaginal microbicide formulations should take into account an understanding of the intimate mechanisms involved in the crossing of HIV through the female genital mucosae, in the context of a mixture of both male and female genital fluids.

Circulating levels of HMGB1 are correlated strongly with MD2 in HIV-infection: possible implication for TLR4-signalling and chronic immune activation

Progressive HIV infection is characterized by profound enterocyte damage, microbial translocation and chronic immune activation. We aimed to test whether High Mobility Group Box protein 1(HMGB1), a marker of cell death, alone, or in combination with LPS, might contribute to HIV-associated immune activation and progression. Altogether, 29 untreated HIV-infected individuals, 25 inflammatory bowel disease (IBD) patients and 30 controls were included. HIV-infected patients had lower plasma LPS levels than IBD patients, but higher levels of soluble CD14 and Myeloid Differentiation (MD) 2, which interacts with TLR4 to initiate LPS-signalling. Furthermore, plasma levels of HMGB1 and MD2 were correlated directly within the HIV-infected cohort (r = 0.89, P < 0.001) and the IBD-cohort (r = 0.85, P < 0.001), implying HMGB1 signalling through the MD2/TLR4-pathway. HMGB1 and LPS, although not inter-correlated, were both moderately (r = 0.4) correlated with CD38 density on CD8+ T cells in HIV progressors. The highest levels of CD38 density and MD2 were found in progressors with plasma levels of both LPS and HMGB1 above the fiftieth percentile. Our results could imply that, in some patients, immune activation is triggered by microbial translocation, in some by cell death and in some by HMGB1 in complex with bacterial products through activation of the MD2/TLR4-pathway.

HMGB1 protein binds to influenza virus nucleoprotein and promotes viral replication

Influenza virus has evolved replication strategies that hijack host cell pathways. To uncover interactions between viral macromolecules and host proteins, we applied a phage display strategy. A library of human cDNA expression products displayed on filamentous phages was submitted to affinity selection for influenza viral ribonucleoproteins (vRNPs). High-mobility-group box (HMGB) proteins were found to bind to the nucleoprotein (NP) component of vRNPs. HMGB1 and HMGB2 bind directly to the purified NP in the absence of viral RNA, and the HMG box A domain is sufficient to bind the NP. We show that HMGB1 associates with the viral NP in the nuclei of infected cells, promotes viral growth, and enhances the activity of the viral polymerase. The presence of a functional HMGB1 DNA-binding site is required to enhance influenza virus replication. Glycyrrhizin, which reduces HMGB1 binding to DNA, inhibits influenza virus polymerase activity. Our data show that the HMGB1 protein can play a significant role in intranuclear replication of influenza viruses, thus extending previous findings on the bornavirus and on a number of DNA viruses.

HMGB1 protein binds to influenza virus nucleoprotein and promotes viral replication

Influenza virus has evolved replication strategies that hijack host cell pathways. To uncover interactions between viral macromolecules and host proteins, we applied a phage display strategy. A library of human cDNA expression products displayed on filamentous phages was submitted to affinity selection for influenza viral ribonucleoproteins (vRNPs). High-mobility-group box (HMGB) proteins were found to bind to the nucleoprotein (NP) component of vRNPs. HMGB1 and HMGB2 bind directly to the purified NP in the absence of viral RNA, and the HMG box A domain is sufficient to bind the NP. We show that HMGB1 associates with the viral NP in the nuclei of infected cells, promotes viral growth, and enhances the activity of the viral polymerase. The presence of a functional HMGB1 DNA-binding site is required to enhance influenza virus replication. Glycyrrhizin, which reduces HMGB1 binding to DNA, inhibits influenza virus polymerase activity. Our data show that the HMGB1 protein can play a significant role in intranuclear replication of influenza viruses, thus extending previous findings on the bornavirus and on a number of DNA viruses.