High‐mobility group box 1 (HMGB1) was initially recognized as a ubiquitous nuclear protein involved in maintaining the nucleosome integrity and facilitating gene transcription. HMGB1 has since been reevaluated to be a prototypical damage‐associated molecular pattern (DAMP) protein, and together with its exogenous counterpart, pathogen‐associated molecular pattern (PAMP), completes the body's alarmin system against disturbances in homeostasis. HMGB1 can be released into the extracellular matrix (ECM) by either granulocytes or necrotic cells to serve as a chemotaxis/cytokine during infection, endotoxemia, hypoxia, ischemia–reperfusion events, and cancer. Different isoforms of HMGB1 present with distinctive physiological functions in ECM—fully‐reduced HMGB1 (all thiol) acts as the initial damage signal to recruit circulating myeloid cells, disulfide HMGB1 behaves as a cytokine to activate macrophages and neutrophils, and both signals are turned off when HMGB1 is terminally oxidized into the final sulfonate form. Targeting HMGB1 constitutes a favorable therapeutic strategy for inflammation and inflammatory diseases. Antagonists such as ethyl pyruvate inhibit HMGB1 by interfering with its cytoplasmic exportation, while others such as glycyrrhizin directly bind to HMGB1 and render it unavailable for its receptors. The fact that a mixture of different HMGB1 isoforms is present in the ECM poses a challenge in pinpointing the exact role of an individual antagonist. A more discriminative probe for HMGB1 may be necessary to advance our knowledge of HMGB1, HMGB1 antagonists, and inflammatory‐related diseases.

Asbestos causes malignant transformation of primary human mesothelial cells (HM), leading to mesothelioma. The mechanisms of asbestos carcinogenesis remain enigmatic, as exposure to asbestos induces HM death. However, some asbestos-exposed HM escape cell death, accumulate DNA damage, and may become transformed. We previously demonstrated that, upon asbestos exposure, HM and reactive macrophages releases the high mobility group box 1 (HMGB1) protein that becomes detectable in the tissues near asbestos deposits where HMGB1 triggers chronic inflammation. HMGB1 is also detectable in the sera of asbestos-exposed individuals and mice. Searching for additional biomarkers, we found higher levels of the autophagy marker ATG5 in sera from asbestos-exposed individuals compared to unexposed controls. As we investigated the mechanisms underlying this finding, we discovered that the release of HMGB1 upon asbestos exposure promoted autophagy, allowing a higher fraction of HM to survive asbestos exposure. HMGB1 silencing inhibited autophagy and increased asbestos-induced HM death, thereby decreasing asbestos-induced HM transformation. We demonstrate that autophagy was induced by the cytoplasmic and extracellular fractions of HMGB1 via the engagement of the RAGE receptor and Beclin 1 pathway, while nuclear HMGB1 did not participate in this process. We validated our findings in a novel unique mesothelial conditional HMGB1-knockout (HMGB1-cKO) mouse model. Compared to HMGB1 wild-type mice, mesothelial cells from HMGB1-cKO mice showed significantly reduced autophagy and increased cell death. Autophagy inhibitors chloroquine and desmethylclomipramine increased cell death and reduced asbestos-driven foci formation. In summary, HMGB1 released upon asbestos exposure induces autophagy, promoting HM survival and malignant transformation.

Mesothelioma has long been associated with the exposure to asbestos, which was largely used in manufacturing activities. Toxicology studies in vitro and in vivo demonstrated that asbestos fibers were carcinogenic, and epidemiology studies revealed that asbestos exposure was paralleled by the increase in the incidence of mesothelioma and related mortality rates. More recently, the role of chronic inflammation and the molecular mechanisms involved in carcinogenesis by mineral fibers were elucidated following the discovery of the roles of HMGB1 and inflammasome. A change of paradigm was the discovery of a prevalence of mesotheliomas attributable to inherited mutations of cancer susceptibility genes. The discovery of BAP1 as a predisposition gene for the development of familial mesothelioma and other cancers implemented genome studies in patients with mesothelioma and routine clinical surveys in individuals at risk to identify germline mutations associated with cancers included in the BAP1 syndrome. A further progress in the approach to asbestos-related malignancy was the adoption of combined genetics and environmental analyses according to the model of gene-environment (GxE) interactions. This review aims at updating on the most recently discovered mechanisms of tumorigenesis and the pivotal role of GxE interactions.

Human malignant mesothelioma (MM) is an aggressive cancer linked to asbestos and erionite exposure. We previously reported that High-Mobility Group Box-1 protein (HMGB1), a prototypic damage-associated molecular pattern, drives MM development and sustains MM progression. Moreover, we demonstrated that targeting HMGB1 inhibited MM cell growth and motility in vitro, reduced tumor growth in vivo, and prolonged survival of MM-bearing mice. Ethyl pyruvate (EP), the ethyl ester of pyruvic acid, has been shown to be an effective HMGB1 inhibitor in inflammation-related diseases and several cancers. Here, we studied the effect of EP on the malignant phenotype of MM cells in tissue culture and on tumor growth in vivo using an orthotopic MM xenograft model. We found that EP impairs HMGB1 secretion by MM cells leading to reduced RAGE expression and NF-κB activation. As a consequence, EP impaired cell motility, cell proliferation, and anchorage-independent growth of MM cells. Moreover, EP reduced HMGB1 serum levels in mice and inhibited the growth of MM xenografts.Our results indicate that EP effectively hampers the malignant phenotype of MM, offering a novel potential therapeutic approach to patients afflicted with this dismal disease.

Background: Mindfulness-based interventions (MBIs) have been reported to be efficacious in treating attention deficit hyperactivity disorder (ADHD). However, the value of the control effect of MBIs on ADHD core symptoms remains controversial. To clarify the literature on the control effect of MBIs on the symptoms of ADHD and guide future researches, an effect-size analysis was conducted. Methods: A systematic search in PubMed, Embase, Web of Science, Medline, Cochrane Library, China National Knowledge Infrastructure, and Wangfang Data databases was performed up to January 11, 2019. The overall effect size of MBIs on ADHD core symptoms (ie, inattention and hyperactivity/impulsivity) was recorded by the metric of Hedges’ g with 95% confidence interval, Z -value, and P -value. Results: Eleven eligible studies featuring 682 participants were included in the meta-analysis. The overall results indicated that MBIs had large effects on inattention (Hedges’ g = −0.825) and hyperactivity/impulsivity (Hedges’ g = −0.676) relative to the control group. Results from subgroup analyses between self- and observer rating on ADHD symptoms revealed that the effect of MBIs both remained in a large range and self-rated ADHD core symptom had a greater impact on heterogeneity across the studies. Meta-regression found that the overall effect might be moderated by participant age group and control condition. Conclusion: The present meta-analysis suggested that MBIs had large effects in reducing ADHD core symptoms in comparison with the control group. Future researches are needed to assess follow-up effects of MBIs on ADHD core symptoms and explore the correlation between the individual level of mindfulness and reduction of ADHD symptoms.

BackgroundMalignant mesothelioma (MM) is a very aggressive type of cancer, with a dismal prognosis and inherent resistance to chemotherapeutics. Development and evaluation of new therapeutic approaches is highly needed. Immunosuppressant FTY720, approved for multiple sclerosis treatment, has recently raised attention for its anti-tumor activity in a variety of cancers. However, its therapeutic potential in MM has not been evaluated yet.MethodsCell viability and anchorage–independent growth were evaluated in a panel of MM cell lines and human mesothelial cells (HM) upon FTY720 treatment to assess in vitro anti-tumor efficacy. The mechanism of action of FTY720 in MM was assessed by measuring the activity of phosphatase protein 2A (PP2A)—a major target of FTY720. The binding of the endogenous inhibitor SET to PP2A in presence of FTY720 was evaluated by immunoblotting and immunoprecipitation. Signaling and activation of programmed cell death were evaluated by immunoblotting and flow cytometry. A syngeneic mouse model was used to evaluate anti-tumor efficacy and toxicity profile of FTY720 in vivo.ResultsWe show that FTY720 significantly suppressed MM cell viability and anchorage–independent growth without affecting normal HM cells. FTY720 inhibited the phosphatase activity of PP2A by displacement of SET protein, which appeared overexpressed in MM, as compared to HM cells. FTY720 promoted AKT dephosphorylation and Bcl-2 degradation, leading to induction of programmed cell death, as demonstrated by caspase-3 and PARP activation, as well as by cytochrome c and AIF intracellular translocation. Moreover, FTY720 administration in vivo effectively reduced tumor burden in mice without apparent toxicity.ConclusionsOur preclinical data indicate that FTY720 is a potentially promising therapeutic agent for MM treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-017-1158-z) contains supplementary material, which is available to authorized users.

Background: Psychological stress was an important mental health problem among the general population and warrant research to inform strategies for effective prevention. iMBIs provide a possibility to offer easily accessible, efficacious, convenient, and low-cost interventions on a wide scale. However, the efficacy of iMBIs in the general population remains unclear. The aim of this meta-analysis is to evaluate the effects of iMBIs for stress reduction in the general population. Methods: A systematic search in PubMed, Embase, Web of Science, Medline, Cochrane Library, CNKI, and Wanfang Data databases was performed up to April 10, 2019. The overall effect sizes of the iMBIs on stress, depression, anxiety, and mindfulness were recorded by the metric of Hedges’ g with 95% confidence interval (CI), Z-value, and P value. Results: Sixteen eligible studies were included in the meta-analysis. The overall results indicated that iMBIs had small to moderate effects on stress (Hedges’ g = −0.393) and mindfulness (Hedges’ g = −0.316) compared with the control group. Results from subgroup analyses revealed that the type of sample and delivery mode had a greater impact on heterogeneity across the studies. Meta-regression found that the overall effect might be moderated by guidance for iMBIs. Conclusion: The present meta-analysis suggested that iMBIs had small to moderate effects in reducing stress and improving mindfulness of the general population in comparison with the control group. Future research is needed to explore how iMBIs are remolded to improve adherence and suit specific individuals.

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