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

Ferroptosis and HMGB2 induced calreticulin translocation required for immunogenic cell death are controlled by the nuclear exporter XPO1

Cisplatin and oxaliplatin cause the secretion of high mobility group box 1 (HMGB1) from cancer cells, which is necessary for initiation of immunogenic cell death (ICD). Calreticulin (CRT) translocation from the endoplasmic reticulum to the plasma membrane is also required; oxaliplatin induces this translocation but cisplatin does not. We have discovered that oxaliplatin causes the secretion of both HMGB1 and HMGB2 from the nucleus into the extracellular milieu. We previously showed that cisplatin mediated secretion of HMGB1 is controlled by the nuclear exporter XPO1 (chromosomal maintenance 1; CRM1). We now find that XPO1 regulates oxaliplatin mediated secretion of both HMGB1 and HMGB2. XPO1 inhibition causes nuclear accumulation of both proteins, inhibition of oxaliplatin-mediated ferroptosis of colon cancer cells, and inhibition of CRT translocation to the plasma membrane of lung and colon cancer cells. Incubation of cancer cells with cell targeted (CT)-HMGB2 confirmed that HMGB2 is responsible for translocation of CRT to the plasma membrane. CT-HMGB2 is three orders of magnitude more potent than oxaliplatin at inducing CRT translocation. Inhibition of HMGB1 and HMGB2 secretion and/or their activation of nuclear factor-kappa B (NF-kB) has potential utility for treating cardiovascular, and neurodegenerative diseases; whereas CT-HMGB2 could augment therapeutic approaches to cancer treatment.

Icariin attenuates vascular endothelial dysfunction by inhibiting inflammation through GPER/Sirt1/HMGB1 signaling pathway in type 1 diabetic rats

Icariin, a flavonoid glycoside, is extracted from Epimedium. This study aimed to investigate the vascular protective effects of icariin in type 1 diabetic rats by inhibiting high-mobility group box 1 (HMGB1)-related inflammation and exploring its potential mechanisms. The impact of icariin on vascular dysfunction was assessed in streptozotocin (STZ)-induced diabetic rats through vascular reactivity studies. Western blotting and immunofluorescence assays were performed to measure the expressions of target proteins. The release of HMGB1 and pro-inflammation cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The results revealed that icariin administration enhanced acetylcholine-induced vasodilation in the aortas of diabetic rats. It also notably reduced the release of pro-inflammatory cytokines, including interleukin-8 (IL-8), IL-6, IL-1β, and tumor necrosis factor-alpha (TNF-α) in diabetic rats and high glucose (HG)-induced human umbilical vein endothelial cells (HUVECs). The results also unveiled that the pro-inflammatory cytokines in the culture medium of HUVECs could be increased by rHMGB1. The increased release of HMGB1 and upregulated expressions of HMGB1-related inflammatory factors, including advanced glycation end products (RAGE), Toll-like receptor 4 (TLR4), and phosphorylated p65 (p-p65) in diabetic rats and HG-induced HUVECs, were remarkably suppressed by icariin. Notably, HMGB1 translocation from the nucleus to the cytoplasm in HUVECs under HG was inhibited by icariin. Meanwhile, icariin could activate G protein-coupled estrogen receptor (GPER) and sirt1. To explore the role of GPER and Sirt1 in the inhibitory effect of icariin on HMGB1 release and HMGB-induced inflammation, GPER inhibitor and Sirt1 inhibitor were used in this study. These inhibitors diminished the effects of icariin on HMGB1 release and HMGB1-induced inflammation. Specifically, the GPER inhibitor also negated the activation of Sirt1 by icariin. These findings suggest that icariin activates GPER and increases the expression of Sirt1, which in turn reduces HMGB1 translocation and release, thereby improving vascular endothelial function in type 1 diabetic rats by inhibiting inflammation.

The correlation between the severity of cerebral microbleeds and serum HMGB1 levels and cognitive impairment in patients with cerebral small vessel disease

Objective

The study investigated the correlation and predictive value between the severity of cerebral microbleeds (CMBs) and the level of serum High Mobility Group Protein B1 (HMGB1) and the occurrence of cognitive impairment in patients with cerebral small vessel disease (CSVD).

Methods

A total of 139 patients with CSVD admitted to the Department of Neurology of the First Affiliated Hospital of Xinxiang Medical University from December 2020 to December 2022 were selected as study subjects. The Montreal Cognitive Assessment (MoCA) scale was used to assess the cognitive function and was divided into the cognitive impairment group and the cognitive normal group. Magnetic Resonance Imaging (MRI) and Susceptibility Weighted Imaging (SWI) were used to screen and assess the severity of CMBs. Serum HMGB1 levels of CSVD patients were measured by enzyme linked immunosorbent assay (ELISA). Multivariable logistic regression analysis was used to explore risk factors for cognitive impairment and CMBs. Pearson correlation analysis was used to investigate the correlation between HMGB1 and cognitive function. Receiver Operating Characteristics (ROC) curves were used to assess the predictive value of HMGB1 for the occurrence of cognitive impairment in patients with CMBs.

Results

High Mobility Group Protein B1, uric acid (UA), glycosylated hemoglobin (HbA1c), CMBs, lacunar cerebral infarction (LI), years of education, and history of hypertension were risk factors for cognitive impairment (P < 0.05); HMGB1 was significantly and negatively associated with total MoCA score, visuospatial/executive ability, and delayed recall ability (P < 0.05). HMGB1 was significantly and positively correlated with the number of CMBs (P < 0.05). The area under the ROC curve for HMGB1 predicting cognitive impairment in patients with CMBs was 0.807 (P < 0.001).

Conclusion

Serum HMGB1 levels are associated with the development of cognitive impairment in CSVD patients, and serum HMGB1 levels have a high predictive value for the development of cognitive impairment in CSVD patients with combined CMBs, which can be used for early clinical identification and intervention of vascular cognitive impairment.