HMGB1 regulates autophagy of placental trophoblast through ERK signaling pathway

OBJECTIVE

The purpose of this study is to investigate the role of high mobility group protein B1 (HMGB1) in placental development and fetal growth.

METHODS

We employed the Cre-loxP recombination system to establish a placenta-specific HMGB1 knockout mouse model. Breeding HMGB1flox/flox mice with Elf5-Cre mice facilitated the knockout, leveraging Elf5 expression in extra-embryonic ectoderm, ectoplacental cone, and trophoblast giant cells at 12.5 days of embryonic development. The primary goal of this model was to elucidate the molecular mechanism of HMGB1 in placental development, assessing parameters such as placental weight, fetal weight, and bone development. Additionally, we utilized lentiviral interference and overexpression of HMGB1 in human trophoblast cells to further investigate HMGB1's functional role.

RESULTS

Our findings indicate that HMGB1flox/floxElf5cre/+ mouse display fetal growth restriction (FGR), characterized by decreased placental and fetal weight and impaired bone development. And the absence of HMGB1 inhibits autophagosome formation, impairs lysosomal degradation, and disrupts autophagic flux. Depletion of HMGB1 in human trophoblast cells also suppresses cell viability, proliferation, migration, and invasion by inhibiting the ERK signaling pathway. Overexpression of HMGB1 observed the opposite phenotypes.

CONCLUSIONS

HMGB1 participates in the regulation of autophagy through the ERK signaling pathway and affects placental development.

[Effects of electroacupuncture pretreatment on long-term postoperative cognitive dysfunction and neuron-inflammation in aged rats]

OBJECTIVE

To observe the effects of electroacupuncture pretreatment on postoperative cognitive dysfunction (POCD), neuronal apoptosis and neuron-inflammation in aged rats.

METHODS

Thirty-six male SD rats aged 20 months were randomly divided into sham operation group, model group and electroacupuncture (EA) group, with 12 rats in each group. The POCD rats model was prepared by internal fixation of left tibial fracture. Five days before modeling, EA stimulation (2 Hz/15 Hz, 1 mA, 30 min) was applied to "Zusanli" (ST36), "Hegu" (LI4) and "Neiguan" (PC6) on the unaffected side of rats in the EA group, once a day for consecutive 5 d. The learning and memory abilities of rats were evaluated by water maze test 31-35 days after operation. The apoptosis of hippocampal neurons was observed by Tunel/NeuN double staining. The expressions of high mobility group protein B1 (HMGB1) and phosphorylated (p)-nuclear factor (NF)-κB in microglia cells in hippocampal dentate gyrus were detected by immunofluorescence staining. The expression levels of interleukin (IL)-6 and IL-1β in the hippocampus were detected by Western blot.

RESULTS

Compared with the sham operation group, the escape latency was prolonged (P<0.05); the frequency of crossing the original platform, ratio of the swimming distance and the time in the target quadrant of the Morris water maze were significantly decreased (P<0.05); the apoptosis rate of hippocampal neurons was significantly increased (P<0.05); the expressions of HMGB1 and p-NF-κB in microglia cells in the dentate gyrus and the expression levels of IL-6 and IL-1β in hippocampus were increased (P<0.05) in the model group. Compared with the model group, the results of the above indexes were all opposite (P<0.05) in the EA group.

CONCLUSION

EA preconditioning can regulate hippocampal inflammatory response, alleviate neuronal apoptosis rate and long-term cognitive dysfunction in aged rats with POCD, the mechanisms may be related to the inhibition of microglia HMGB1/NF-κB pathway in hippocampal dentate gyrus.

Polymeric nano-micelle of carbon monoxide donor SMA/CORM2 ameliorates acetaminophen-induced liver injury via suppressing HMGB1/TLR4 signaling pathway

Acetaminophen (APAP) overdose-induced hepatotoxicity is the most common cause of acute liver failure. Excessive generation of reactive oxygen species (ROS) and inflammatory responses are the major causes of necrosis and/or necroptosis of the liver cells. Currently, the treatment options for APAP-induced liver injury are very limited, N-acetylcysteine (NAC) is the only approved drug to treat APAP overdose patients. It is of great necessity to develop new therapeutic strategies. In a previous study, we focused on the anti-oxidative, anti-inflammatory signal molecule carbon monoxide (CO), and developed a nano-micelle encapsulating CO donor, i.e., SMA/CORM2. Administration of SMA/CORM2 to the mice exposed to APAP significantly ameliorated the liver injury and inflammatory process, in which modulating macrophage reprogramming plays a critical role. Along this line, in this study, we investigated the potential effect of SMA/CORM2 on toll-like receptor 4 (TLR4) and high mobility group protein B1 (HMGB1) signaling pathways that are known to be closely involved in many inflammatory responses and necroptosis. In a mouse APAP-induced liver injury model, similar to the previous study, SMA/CORM2 at 10 mg/kg remarkably improved the condition of the liver after injury as evidenced by histological examination and liver function. During the process of liver injury triggered by APAP, TLR4 expression gradually increased over time, and it was significantly upregulated as early as 4 h after APAP exposure, whereas, an increase of HMGB1 was a late-stage event. Notably, SMA/CORM2 treatment suppressed significantly both TLR4 and HMGB1, consequently inhibiting the progression of inflammation and liver injury. Compared to CORM2 without SMA modification (native CORM2) of 1 mg/kg that is equivalent to 10 mg/kg of SMA/CORM2 (the amount of CORM2 in SMA/CORM2 is 10% [w/w]), SMA/CORM2 exhibited a much better therapeutic effect, indicating its superior therapeutic efficacy to native CORM2. These findings revealed that SMA/CORM2 protects against APAP-induced liver injury via mechanisms involving the suppression of TLR4 and HMGB1 signaling pathways. Taking together the results in this study and previous studies, SMA/CORM2 exhibits great therapeutic potential for APAP overdose-induced liver injury, we thus anticipate the clinical application of SMA/CORM2 for the treatment of APAP overdose, as well as other inflammatory diseases.

Downregulation of circ-YES1 suppresses NSCLC migration and proliferation through the miR-142-3p-HMGB1 axis

BACKGROUND

Circular RNAs (circRNAs) are a new family of abundant regulatory RNAs with roles in various types of cancer. While the hsa_circ_0046701 (circ-YES1) function in non-small cell lung cancer (NSCLC) is unclear.

METHODS

Circ-YES1 expression in normal pulmonary epithelial and NSCLC cells was examined. The small interfering RNA for circ-YES1 was prepared, cell proliferation and migration were assessed. Tumorigenesis in nude mice was assayed to validate the role of circ-YES1. Bioinformatics analyses and luciferase reporter assays were utilized to identify downstream targets of circ-YES1.

RESULTS

Compared to normal pulmonary epithelial cells, the circ-YES1 expression increased in NSCLC cells, and cell proliferation and migration were suppressed after circ-YES1 knockdown. Both high mobility group protein B1 (HMGB1) and miR-142-3p were found to be downstream targets of circ-YES1, and miR-142-3p inhibition and HMGB1 overexpression reversed the effects of circ-YES1 knockdown on cell proliferation and migration. Similarly, HMGB1 overexpression reversed the miR-142-3p overexpression effects on these two processes. The imaging experiment results revealed that circ-YES1 knockdown impeded tumor development and metastasis in a nude mouse xenograft model.

CONCLUSION

Taken together, our results show that circ-YES1 promotes tumor development through the miR-142-3p-HMGB1 axis and support the development of circ-YES1 probability as a new therapeutic NSCLC target.

Inhibition of the receptor for advanced glycation inhibits lipopolysaccharide-mediated High mobility group protein B1 and Interleukin-6 synthesis in human gingival fibroblasts through the NF-κB signaling pathway

AIMS

We investigated the effect of a specific inhibitor of the receptor for advanced glycation (FPS-ZM1) against lipopolysaccharide (LPS)-induced increase in expressions of high mobility group protein B1 (HMGB1) and interleukin-6 (IL-6) in human gingival fibroblasts (HGFs). Furthermore, we explored the potential molecular mechanisms and assessed the involvement of the NF-κB pathway in mediating the changes in the expressions of HMGB1 and IL-6 expression in response to LPS and FPS-ZM1.

METHODS

HGFs were cultured with enzymatic digestion-tissue explants method. The proliferation of LPS-stimulated HGFs pretreated with FPS-ZM1 at 24, 48, and 72 h was determined by cell counting kit 8 assay. The expressions of HMGB1 and IL-6 were measured using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Western blot analysis was used to assess the expressions of receptor for advanced glycation end products (RAGE) and NF-κB.

RESULTS

LPS enhanced the protein expression of RAGE in HGFs. At the same time, LPS stimulated mRNA and protein expressions of HMGB1 and IL-6 in HGFs. However, pretreatment with FPS-ZM1 attenuated these effects. Pretreatment with FPS-ZM1 (250, 500 nM) significantly inhibited the LPS-induced NF-κB activity.

CONCLUSION

FPS-ZM1 down-regulated the LPS-induced HMGB1 and IL-6 expression in HGFs through blocking NF-κB activation. FPS-ZM1 is a promising therapeutic agent for inflammatory diseases caused by oral bacteria.

Associations between HMGB1 gene polymorphisms and susceptibility and clinical outcomes in Chinese Han sepsis patients

OBJECTIVES

High mobility group box 1 protein (HMGB1) is an important late inflammatory mediator in the body. In recent years, studies have found that it plays an important pathogenic role in various diseases such as sepsis. However, it is unclear whether the genetic variation of the HMGB1 gene is related to the susceptibility to sepsis. This study investigated the relationship between susceptibility and outcome of the HMGB1 gene rs2249825, rs1045411, and rs1360485 single nucleotide polymorphisms (SNPs) in Chinese Han patients with sepsis.

METHODS

The HMGB1 gene rs2249825, rs1045411, and rs1360485 genotypes were detected by the direct sequencing method in 345 patients with sepsis and 345 healthy controls. Serum HMGB1 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The HMGB1 gene rs2249825 and rs1045411 site SNPs were associated with sepsis risk, but the rs1360485 site SNP was not associated with sepsis risk. Subjects with the HMGB1 gene rs2249825 and rs1045411 site mutations had higher serum HMGB1 levels, and patients with mutant genotype sepsis had higher APACHE II scores and lower 30-day survival rates. There were no correlations among the rs1360485 site SNP, sepsis risk, and patient 30-day survival.

CONCLUSION

The HMGB1 gene rs2249825 and rs1045411 site SNPs are associated with susceptibility and outcomes of Chinese Han patients with sepsis. The rs2249825 locus C allele and the rs1045411 locus A allele are high risk factors for sepsis and severity in the Chinese Han population, and are associated with adverse outcomes in patients with sepsis.

Increased serum levels of high mobility group protein B1 and calprotectin in pre-eclampsia

OBJECTIVE

To determine whether women with pre-eclampsia have serum levels of biomarkers indicative of an elevated systemic inflammatory response.

METHOD

The present cross-sectional study was conducted among pregnant women either with pre-eclampsia or without pre-eclampsia who were recruited at a single Chinese hospital between August 1, 2016, and April 30, 2017. Eligible women had no history of acute or chronic inflammation. Serum concentrations of high mobility group protein B1 (HMG-1), calprotectin, and Toll-like receptor 4 (TLR4) were measured and compared.

RESULTS

There were 55 patients included (25 with pre-eclampsia and 30 without). The mean serum concentration of calprotectin was 2656.76 ± 1724.56 μg/L in the pre-eclampsia group versus 1877.33 ± 905.69 μg/L in the control group (P=0.036). Among patients with pre-eclampsia, elevated calprotectin levels were positively associated with the duration of hypertension in pregnancy (P=0.031) and were negatively associated with pregnancy duration at delivery (P=0.035). The mean serum concentration of HMG-1 was 72.48 ± 27.57 μg/L in the pre-eclampsia group versus 57.57 ± 20.07 μg/L in the control group (P=0.017). The mean serum concentration of TLR4 was 22.83 ± 8.46 μg/L in the pre-eclampsia group versus 18.83 ± 6.79 μg/L in the control group (P=0.057).

CONCLUSION

Elevated levels of HMG-1 and calprotectin could reflect an excessive systemic inflammatory response in pre-eclampsia.

Expression of High Mobility Group Protein B1 in Cardiac Tissue of Elderly Patients with Coronary Artery Disease with or without Inflammatory Rheumatic Disease

BACKGROUND

It is known from clinical practice and observational studies that elderly patients with a diagnosis of inflammatory rheumatic diseases (IRD) bear a significantly increased risk for cardiovascular diseases such as coronary artery disease (CAD) and heart failure. The molecular mechanism, however, is still not known. Recently, high mobility group protein B1 (HMGB1), a ubiquitous, highly conserved single polypeptide expressed in all mammal eukaryotic cells, has been identified to mediate myocardial dysfunction in vitro once released from the nuclei of cardiomyocytes.

OBJECTIVE

To investigate whether HMGB1 and its receptors are expressed in cardiac muscles of elderly patients with CAD with or without IRD.

METHODS

HMGB1 and its 3 well-known receptors, receptor for advanced glycation end products, Toll-like receptor 2 (TLR2), and TLR4, were examined by immunohistochemistry on myocardial biopsy specimens from 18 elderly patients with CAD (10 with IRD, 8 without IRD). Furthermore, total HMGB1 protein levels were measured by Western blot from the cardiac biopsies in 5 patients with and 5 without IRD.

RESULTS

Pathologic cytosolic HMGB1 in cardiomyocytes was massively recorded in all patients with IRD, but only slightly expressed in 1 patient without IRD. Total HMGB1 levels were also consistently lower in myocardial muscle biopsies of patients with IRD compared to those without IRD. Furthermore, all 3 HMGB1 receptors were expressed in cardiomyocytes of all patients.

CONCLUSION

The increased cytosolic expression of HMGB1 in cardiomyocytes and the lower total amount of HMGB1 in the cardiac specimens of IRD patients is consistent with a greater release of HMGB1 from the myocardial nuclei in IRD than non-IRD individuals. Thus, the HMGB1 signaling pathways may be more easily activated in elderly CAD patients with concomitant IRD and trigger a detrimental inflammatory process causing severe cardiovascular problems. Therefore, targeting HMGB1 in IRD patients might reduce the risk for cardiovascular events.

Clinical significance of expression of high mobility group protein B1 and Toll-like receptor 4 in esophageal squamous cell carcinoma

AIM: To detect the expression of high mobility group protein B1 (HMGB1) and Toll-like receptor 4 (TLR4) in human esophageal squamous cell carcinoma and analyze their clinical significance.

METHODS: The expression of HMGB1 and TLR4 was detected by EnVision immunohisto-

chemical staining method in 72 esophageal squamous carcinoma specimens and 15 matched normal tissue specimens. Statistical methods were used to analyze the relationship between the expression of HMGB1 and TLR4 and clinical and pathological parameters.

RESULTS: The expression of HMGB1 and TLR4 in esophageal squamous carcinoma tissues was significantly higher than that in matched normal tissues (P < 0.05). HMGB1 and TLR4 expression was positively associated with lymphatic metastasis and TNM stage (P < 0.05), but negatively correlated with tumor size and degree of differentiation. The expression of HMGB1 and TLR4 had a significant positive correlation (r = 0.377, P < 0.01).

CONCLUSION: The expression of HMGB1 and TLR4 in esophageal squamous carcinoma tissues is associated with lymphatic metastasis and TNM stage, and the joint detection of HMGB1 and TLR4 expression may help evaluate the degree of malignancy of esophageal squamous carcinoma. HMGB1/TLR may be used as important biological indicators reflecting the prognosis of esophageal cancer and important targets for therapy of esophageal cancer.

Changes in expression of high mobility group protein B1 in acute liver failure in rats

AIM: To observe the changes in the expression of high mobility group protein B1 (HMGB1) and other inflammatory cytokines in acute liver failure (ALF) in rats.

METHODS: D-galactosamine (D-Gal) and lipopolysaccharide (LPS) were used to establish a model of ALF by intraperitoneal injection. Rats were treated with normal saline alone in a control group. Serum and liver tissues were collected at different time points (3, 6, 12, 48, 72 and 96 h). Serum biochemical indicators were detected, and HMGB1 expression in liver tissue was observed by immunohistochemical analysis. HE staining was performed to evaluate the severity of liver damage. The changes of HMGB1, interleukin 1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) mRNA expression were determined by real-time fluorescent quantitative PCR, and the levels of HMGB1, IL-1β, IL-6 and TNF-α were measured using ELISA kits. rHMGB1 was injected via the tail vein alone or combined with D-Gal and LPS by intraperitoneal injection, and the changes of symptoms and signs and survival rates of rats were observed.

RESULTS: ALF was successfully induced in rats using D-Gal and LPS. In ALF rats, the peak of HMGB1 gene expression and serum levels of HMGB1 were later but lasted longer than IL-1β, IL-6 and TNF-α. Cytoplasmic translocation of HMGB1 was observed as early as 3 h after D-Gal and LPS administration. In 24-48 h, normal liver tissue structures disappeared, and HMGB1 was overflowed from necrotic liver cells and showed diffused yellow staining, full of the entire field of vision. Administration of exogenous rHMGB1 reduced the time to death and increased mortality rates .

CONCLUSION: HMGB1 may be passively leaked by necrosis hepatic cells, which appeared later compared with other inflammatory cytokines. The interaction of HMGB1 and other inflammatory cytokines can promote the inflammation progression in ALF.

Expression of high mobility group protein B1 in the lungs of rats with sepsis

BACKGROUND

Vibrio vulnificus inside the body could activate the NF-κB signaling pathway and initiate the inflammatory cascade. The lung is one of the earliest organs affected by sepsis associated with acute lung injury. High mobility group protein B1 (HMGB1) is an important late-acting pro-inflammatory cytokine involving in the pathophysiology of sepsis. It is also involved in the injury process in the lung, liver and intestine. There has been no report on the involvement of HMGB1 in Vibrio vulnificus sepsis-induced lung injury.

METHODS

Sixty rats were randomly divided into a normal control group (group A, n=10) and a Vibrio vulnificus sepsis group (group B, n=50). Sepsis was induced in the rats by subcutaneous injection of Vibrio vulnificus (concentration 6×10(8) cfu/mL, volume 0.1 mL/100g)) into the left lower limbs. The rats in group B were sacrificed separately 1, 6, 12, 24, and 48 hours after the infection. Their lungs were stored as specimens, lung water content was measured, and lung pathology was observed under a light microscope. The expressions of the HMGB1 gene and protein in the lungs were detected by RT-PCR and Western blot. Data were analyzed with one-way analysis of variance (ANOVA) and the LSD method for pair-wise comparison between the two groups. P<0.05 was considered statistically significant.

RESULTS

Compared to group A (0.652±0.177), HMGB1 mRNA expression in the lungs of group B was significantly higher at 0 hour (1.161±0.358, P=0.013), 24 hours (1.679±0.235, P=0.000), and 48 hours (1.258±0.274, P=0.004) (P<0.05), and peaked at 24 hours. Compared to group A (0.594±0.190), HMGB1 protein expression at 6 hours (1.408±0.567, P=0.026) after infection was significantly increased (P<0. 05), and peaked at 24 hours (2.415±1.064, P=0.000) after infection. Compared to group A (0.699±0.054), lung water content was significantly increased at 6 hours (0.759±0.030, P=0.001),12 hours (0.767±0.023, P=0.000), 24 hours (0.771±0.043, P=0.000) and 48 hours (0.789±0.137, P=0.000) after infection (P<0.05). Compared to group A, pathological changes at 12 hours in group B indicate marked pulmonary vascular congestion, interstitial edema and inflammatory infiltration. Alveolar cavity collapse and boundaries of the alveolar septum could not be clearly identified.

CONCLUSION

Vibrio vulnificus sepsis can lead to injury in rat lungs, and increased HMGB1 expression in lung tissue may be one of the mechanisms for injury from Vibrio vulnificus sepsis.