Background. HMGB1 acts as an important inflammatory mediator and is a potential therapeutic target for sepsis. Glycyrrhizin (GL), a natural triterpene glycoside derived from licorice, has been demonstrated to inhibit HMGB1 activity. The aim of this study is to explore how GL affects the HMGB1 signaling in sepsis. Methods. We used a CLP model of sepsis and in vitro LPS or HMGB1-treated NR8383 cells to examine the effects of GL on expression of HMGB1 and proinflammatory cytokines. Furthermore, we explored the effect of GL on interactions between HMGB1 and RAGE or TLR4 and the activations of NF-κB and MAPKs. Results. GL significantly decreased mortality and reduced serum levels of HMGB1 in vivo. GL also attenuated the release and expression of HMGB1 and proinflammatory cytokines. Direct stimulation by HMGB1 elevated the release of proinflammatory cytokines faster than LPS did and it was also inhibited by GL. Furthermore, GL blocked the interaction of HMGB1 with RAGE and TLR4 and suppressed the downstream MAPKs/NF-κB signaling pathway. Conclusion. GL may protect rats against sepsis by blocking the interaction of HMGB1 with cell surface receptors and HMGB1-mediated inflammatory responses.

Among several leading cardiovascular disorders, ischemia–reperfusion (I/R) injury causes severe manifestations including acute heart failure and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology and dysfunction also play an important role in the prognosis of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks altering gene transcription and translation. While the role of lncRNAs has been extensively studied in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. In this study, the functional roles of Zinc finger protein 36-like 2 (ZFP36L2) and lncRNA PVT1 were determined in cardiomyocytes under hypoxia/reoxygenation (H/R) injury in vitro and myocardial I/R injury in vivo. Western blot and qRT-PCR analysis were used to assess the levels of ZFP36L2, mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocytes. Cardiac function was determined by immunohistochemistry, H&E staining, and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy. The mechanistic model consisting of PVT1 with ZFP36L2 and microRNA miR-21-5p with E3 ubiquitin ligase MARCH5 was assessed by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays. These results identified a novel regulatory axis involving PVT1, miR-21-5p, and MARCH5 that alters mitochondrial morphology and function during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocytes H/R model, we demonstrated that ZFP36L2 directly associates with PVT1 and alters mitochondrial fission and fusion. PVT1 also interactes with miR-21-5p and suppresses its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and its effect on mitochondrial fission and fusion are directly proportional to PVT1 expression during H/R injury. Our findings show that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.

Autophagy and pyroptosis of macrophages play important protective or detrimental roles in sepsis. However, the underlying mechanisms remain unclear. High mobility group box protein 1 (HMGB1) is associated with both pyroptosis and autophagy. lipopolysaccharide (LPS) is an important pathogenic factor involved in sepsis. Lentivirus-mediated HMGB1 shRNA was used to inhibit the expression of HMGB1. Macrophages were treated with acetylation inhibitor (AA) to suppress the translocation of HMGB1 from the nucleus to the cytosol. Autophagy and pyroptosis-related protein expressions were detected by Western blot. The levels of caspase-1 activity were detected and the rate of pyroptotic cells was detected by flow cytometry. LPS induced autophagy and pyroptosis of macrophages at different stages, and HMGB1 downregulation decreased LPS-induced autophagy and pyroptosis. Treatment with acetylation inhibitor (anacardic acid) significantly suppressed LPS-induced autophagy, an effect that was not reversed by exogenous HMGB1, suggesting that cytoplasmic HMGB1 mediates LPS-induced autophagy of macrophages. Anacardic acid or an anti-HMGB1 antibody inhibited LPS-induced pyroptosis of macrophages. HMGB1 alone induced pyroptosis of macrophages and this effect was inhibited by anti-HMGB1 antibody, suggesting that extracellular HMGB1 induces macrophage pyroptosis and mediates LPS-induced pyroptosis. In summary, HMGB1 plays different roles in mediating LPS-induced autophagy and triggering pyroptosis according to subcellular localization.

The pathological mechanisms of acute intracerebral hemorrhage (ICH) remain unknown and unverified. In the present study, we used quantitative proteomics to elucidate the pathological mechanisms and to identify novel biomarker and therapeutic target candidates via tissue proteome in a rat model of acute ICH. Rats were experimentally induced with ICH (n = 6) or Sham (n = 6), and their brain tissue was obtained by 24 h. The TMT-LC–MS/MS-based proteomics approach was used to quantify the differential proteomes across brain tissue, and the results were further analyzed by ingenuity pathway analysis to explore canonical pathways and the relationship involved in the uploaded data. Upon quantification, we found that 96 secreted proteins that were identified in the ICH 24-h group were significantly different those in the control group (P < 0.05); among these proteins, 57 increased and 39 decreased in abundance. Bioinformatic analyses of differentially expressed proteins demonstrated that the protein localization and ERK1 and ERK2 cascade were the top two biological processes with the highest concentrations of differentially proteins. The top protein-protein action network with high confidence levels of protein was the albumin and ERK signaling pathways. Albumin, ERK, and p-ERK were assessed in brain tissue by western blot analysis, and higher expression levels of albumin and p-ERK were observed in the ICH group. Our proteomic results highlight important change in the biological processes of ERK1 and ERK2 cascade, which are possible targets for future interventions of ICH. To our knowledge, this study provides in-depth analysis of ICH in brain tissue, and we propose 96 new biomarker candidates for ICH, including albumin and ERK.

Monocytes serve an important role in systemic inflammation. High mobility group box-1 protein (HMGB1) promotes recruitment and suppresses apoptosis in monocytes through the receptor for advanced glycation end products/nuclear factor (NF)-B and toll-like receptor 4/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathways. Glycyrrhizin (GL), an effective component of licorice, weakens the proinflammatory effect of HMGB1. The present study investigated the effect of GL on the migration and apoptosis of monocytes associated with HMGB1 signaling. THP-1 cells were used to evaluate the behavior of monocytes in response to GL treatment, and the downstream pathways were investigated. GL suppressed HMGB1-induced monocyte migration and increased HMGB1-inhibited monocyte apoptosis. GL inhibited the activation of the NF-B and MAPK/ERK signaling pathways induced by HMGB1 and decreased the expression of monocyte chemoattractant protein-1 (MCP-1) and myeloid cell leukemia 1 (Mcl-1). Taken together, the results indicated that GL may suppress the migration of monocytes and induce apoptosis to reduce systemic inflammation by blocking downstream NF-B/MCP-1 and MAPK/ERK/Mcl-1 signaling pathways.

Background: The use of continuous glucose monitoring (CGM) in the hospital setting is growing, with more patients using these devices at home, especially during the COVID-19 pandemic. Frail and critically ill patients with COVID-19 and previously normal glucose tolerance are also associated with variability in their glucose levels during their intensive care unit (ICU) stay. However, very limited evidence supports the use of CGM in ICU settings, especially among frail patients with COVID-19. Objective: We aimed to investigate the effectiveness of CGM on ICU-related outcomes among frail and critically ill patients with confirmed COVID-19. Methods: This was an exploratory, prospective, open-label, parallel, single-center, randomized controlled trial. A total of 124 patients was finally analyzed. The primary outcome was 28-day, in-ICU mortality. The secondary outcome included the length of ICU stay as well as the occurrence of hypoglycemia and severe hypoglycemia events. Results: The mean age was 78.3 (SD 11.5) years. The mean fasting glucose level and hemoglobin A1c level at baseline were 8.12 (SD 1.54) mmol/L and 7.2% (SD 0.8%), respectively. The percentage of participants with diabetes was 30.6% (38/124). The corresponding hazard ratio of the primary outcome in the intermittently scanned CGM (isCGM) group when compared with the point-of-care testing (POCT) group was 0.18 (95% CI 0.04-0.79). The average length of ICU stay was 10.0 (SD 7.57) days in the isCGM group and 14.0 (SD 6.86) days in the POCT group (P=.02). At the end of study period, the mean value of fasting glucose in the isCGM group and the POCT group was 6.07 (SD 0.63) mmol/L and 7.76 (SD 0.62) mmol/L, respectively (P=.01). A total of 207 hypoglycemia events (<3.9 mmol/L) was detected, with 43 in the isCGM group and 164 in the POCT group (P<.001). A total of 81 severe hypoglycemia events (<2.8 mmol/L) was detected, with 16 in the isCGM group and 65 in the POCT group (P<.001). The major adverse event in this study was bleeding in the puncture site, with a total of 6 occurrences in the isCGM group. During the follow-up, none of the participants dropped out because of bleeding in the puncture site. Conclusions: We found a significant clinical benefit from the use of CGM among frail and critically ill patients with COVID-19. These findings support the use of CGM in the ICU and might help with the extension of application in various in-hospital settings. Trial Registration: Chinese Clinical Trial Registry ChiCTR2200059733; https://www.chictr.org.cn/showproj.html?proj=169257