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LPS Primes Brain Responsiveness to High Mobility Group Box-1 Protein.

ABSTRACT: High mobility group box (HMGB)1 action contributes to late phases of sepsis, but the effects of increased endogenous plasma HMGB1 levels on brain cells during inflammation are unclear. Here, we aimed to further investigate the role of HMGB1 in the brain during septic-like lipopolysaccharide-induced inflammation in rats (LPS, 10 mg/kg, i.p.). HMGB-1 mRNA expression and release were measured in the periphery/brain by RT-PCR, immunohistochemistry and ELISA. In vitro experiments with disulfide-HMGB1 in primary neuro-glial cell cultures of the area postrema (AP), a circumventricular organ with a leaky blood-brain barrier and direct access to circulating mediators like HMGB1 and LPS, were performed to determine the direct influence of HMGB1 on this pivotal brain structure for immune-to-brain communication. Indeed, HMGB1 plasma levels stayed elevated after LPS injection. Immunohistochemistry of brains and AP cultures confirmed LPS-stimulated cytoplasmatic translocation of HMGB1 indicative of local HMGB1 release. Moreover, disulfide-HMGB1 stimulation induced nuclear factor (NF)-κB activation and a significant release of interleukin-6, but not tumor necrosis factor α, into AP culture supernatants. However, only a few AP cells directly responded to HMGB1 with increased intracellular calcium concentration. Interestingly, priming with LPS induced a seven-fold higher percentage of responsive cells to HMGB1. We conclude that, as a humoral and local mediator, HMGB1 enhances brain inflammatory responses, after LPS priming, linked to sustained sepsis symptoms.

SUBMITTER: Peek V

PROVIDER: S-EPMC8230749 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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LPS Primes Brain Responsiveness to High Mobility Group Box-1 Protein.

Peek Verena V Harden Lois M LM Damm Jelena J Aslani Ferial F Leisengang Stephan S Roth Joachim J Gerstberger Rüdiger R Meurer Marita M von Köckritz-Blickwede Maren M Schulz Sabine S Spengler Bernhard B Rummel Christoph C

Pharmaceuticals (Basel, Switzerland) 20210611 6

High mobility group box (HMGB)1 action contributes to late phases of sepsis, but the effects of increased endogenous plasma HMGB1 levels on brain cells during inflammation are unclear. Here, we aimed to further investigate the role of HMGB1 in the brain during septic-like lipopolysaccharide-induced inflammation in rats (LPS, 10 mg/kg, i.p.). HMGB-1 mRNA expression and release were measured in the periphery/brain by RT-PCR, immunohistochemistry and ELISA. In vitro experiments with disulfide-HMGB1 ...[more]

PMID: 34208101

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Project description:Diabetes is a global epidemic and more than 50% diabetic patients are also diagnosed with neuropathy, which greatly affects the quality of life of the patients. Available treatments are not always successful due to the limited efficacy and complications, such as addiction and dependency. Studies have implicated that high mobility group box1 (HMGB1) protein plays a crucial role in neuroinflammation and the development of neuropathic conditions. HMGB1 is a proinflammatory cytokine that can be released from necrotic cells in passive form or in response to inflammatory signals as an active form. HMGB1 is the ligand for the receptor for advanced glycation end products (RAGE), and toll-like receptors, (TLR)-2 and TLR4, which also indirectly activates C-X-C chemokine receptor type 4 (CXCR4). We investigated whether blocking of HMGB1 can reduce pain and inflammation in diabetic neuropathic animals to further understand the role of HMGB1 in diabetic neuropathy. Type 2 diabetic rats and mice were treated with natural inhibitor of HMGB1, glycyrrhizin (GLC) for five days/week for four weeks at a dose of 50 mg/kg per day by intraperitoneal injection. The animals were divided into three categories: naïve control, diabetic alone, diabetic with GLC treatment. All of the behavioral analyses were conducted before and after the treatment. The expression of inflammatory markers and changes in histone acetylation in the peripheral nervous system were measured by immunohistochemistry and Western blot analysis after the completion of the treatment. Our study revealed that TLR4, HMGB1, CXCR4, and Nod-like receptor protein 3 (NLRP3) levels were increased in the spinal and dorsal root ganglia (DRG) neurons of Type 2 diabetic mice and rats with painful neuropathy. GLC treatment inhibited the increases in TLR4, NLRP3, and CXCR4 expressions and improved the mechanical and thermal pain threshold in these animals. Immunohistochemical studies revealed that hyperglycemia mediated inflammation influenced HMGB1 acetylation and its release from the neurons. It also altered histone 3 acetylation in the microglial cells. The inhibition of HMGB1 by GLC prevented the release of HMGB1 as well as H3K9 acetylation. These findings indicate that the interruption of HMGB1 mediated inflammation could ameliorate diabetic neuropathy and might exhibit a unique target for the treatment.

Dataset Information

LPS Primes Brain Responsiveness to High Mobility Group Box-1 Protein.

Publications

LPS Primes Brain Responsiveness to High Mobility Group Box-1 Protein.

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