HMGB1 augments cognitive impairment in sepsis-associated encephalopathy by binding to MD-2 and promoting NLRP3-induced neuroinflammation

SHARPIN contributes to sevoflurane-induced neonatal neurotoxicity through up-regulating HMGB1 to repress M2 like-macrophage polarization

Sevoflurane exposure can result in neurotoxicity especially among children, which remains an important complication after surgery. However, its related mechanisms remain unclear. Here, we investigated the biological roles of SHARPIN in sevoflurane-induced neurotoxicity. As detected by qPCR, Western blotting and immunohistochemical staining, SHARPIN and HMGB1 expression was elevated in sevoflurane-stimulated mice as compared with the control mice. SHARPIN depletion attenuated hippocampus injury, repressed the expression of HMGB1 and M1-like macrophage markers (iNOS, TNF-α, IL-1β, IL-6), but enhanced the expression of M2-like macrophage markers (ARG-1, IL-10). GST pull-down and Co-IP assays demonstrated that SHARPIN directly interacted with HMGB1 to enhance HMGB1 expression in SH-SY5Y cells. The inhibitory effects of SHARPIN silencing on inflammatory reaction and M1-like macrophages were counteracted by HMGB1 overexpression. Finally, SHARPIN-HMGB1 pathway affected neuroinflammation triggered by sevoflurane via modulating macrophage polarization. Collectively, our data suggested that SHARPIN stimulated sevoflurane-induced neurotoxicity via converting M2-like macrophages to M1-like macrophages by enhancing HMGB1 expression. SHARPIN intervention may be a promising therapeutic method to relieve sevoflurane-induced neurotoxicity.

MSC-derived exosomal miR-140-3p improves cognitive dysfunction in sepsis-associated encephalopathy by HMGB1 and S-lactoylglutathione metabolism

MiRNAs in mesenchymal stem cells (MSCs)-derived exosome (MSCs-exo) play an important role in the treatment of sepsis. We explored the mechanism through which MSCs-exo influences cognitive impairment in sepsis-associated encephalopathy (SAE). Here, we show that miR-140-3p targeted Hmgb1. MSCs-exo plus miR-140-3p mimic (Exo) and antibiotic imipenem/cilastatin (ABX) improve survival, weight, and cognitive impairment in cecal ligation and puncture (CLP) mice. Exo and ABX inhibit high mobility group box 1 (HMGB1), IBA-1, interleukin (IL)-1β, IL-6, iNOS, TNF-α, p65/p-p65, NLRP3, Caspase 1, and GSDMD-N levels. In addition, Exo upregulates S-lactoylglutathione levels in the hippocampus of CLP mice. Our data further demonstrates that Exo and S-lactoylglutathione increase GSH levels in LPS-induced HMC3 cells and decrease LD and GLO2 levels, inhibiting inflammatory responses and pyroptosis. These findings suggest that MSCs-exo-mediated delivery of miR-140-3p ameliorates cognitive impairment in mice with SAE by HMGB1 and S-lactoylglutathione metabolism, providing potential therapeutic targets for the clinical treatment of SAE.

How inflammation influences psychiatric disease

Recent studies highlight the strong correlation between infectious diseases and the development of neuropsychiatric disorders. In this editorial, we comment on the article "Anti-infective therapy durations predict psychological stress and laparoscopic surgery quality in pelvic abscess patients" by Zhang et al, published in the recent issue of the World Journal of Psychiatry 2023; 13 (11): 903-911. Our discussion highlighted the potential consequences of anxiety, depression, and psychosis, which are all linked to bacterial, fungal, and viral infections, which are relevant to the impact of inflammation on the sequelae in mental health as those we are observing after the coronavirus disease 2019 pandemic. We focus specifically on the immune mechanisms triggered by inflammation, the primary contributor to psychiatric complications. Importantly, pathophysiological mechanisms such as organ damage, post-injury inflammation, and infection-induced endocrine alterations, including hypocortisolism or autoantibody formation, significantly contribute to the development of chronic low-grade inflammation, promoting the emergence or development of psychiatric alterations in susceptible individuals. As inflammation can have long-term effects on patients, a multidisciplinary treatment plan can avoid complications and debilitating health issues, and it is crucial to recognize and address the mental health implications.

Neuroprotective effects of annexin A1 tripeptide in rats with sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is characterized by high incidence and mortality rates, with limited treatment options available. The underlying mechanisms and pathogenesis of SAE remain unclear. Annexin A1 (ANXA1), a membrane-associated protein, is involved in various in vivo pathophysiological processes. This study aimed to explore the neuroprotective effects and mechanisms of a novel bioactive ANXA1 tripeptide (ANXA1sp) in SAE. Forty Sprague-Dawley rats were randomly divided into four groups (n = 10 each): control, SAE (intraperitoneal injection of lipopolysaccharide), vehicle (SAE + normal saline), and ANXA1sp (SAE + ANXA1sp) groups. Changes in serum inflammatory factors (interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]), hippocampal reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP) levels were measured. The Morris water maze and Y maze tests were used to assess learning and memory capabilities in the rats. Further, changes in peroxisome proliferator-activated receptor-gamma (PPAR-γ) and apoptosis-related protein expression were detected using western blot. The IL-6, TNF-α, and ROS levels were significantly increased in the SAE group compared with the levels in the control group. Intraperitoneal administration of ANXA1sp led to a significant decrease in the IL-6, TNF-α, and ROS levels (p < 0.05). Compared with the SAE group, the ANXA1sp group exhibited reduced escape latency on day 5, a significant increase in the number of platform crossings and the percent spontaneous alternation, and significantly higher hippocampal MMP and ATP levels (p < 0.05). Meanwhile, the expression level of PPAR-γ protein in the ANXA1sp group was significantly increased compared with that in the other groups (p < 0.05). The expressions of apoptosis-related proteins (nuclear factor-kappa B [NF-κB], Bax, and Caspase-3) in the SAE and vehicle groups were significantly increased, with a noticeable decrease in Bcl-2 expression, compared with that noted in the control group. Moreover, the expressions of NF-κB, Bax, and Caspase-3 were significantly decreased in the ANXA1sp group, and the expression of Bcl-2 was markedly increased (p < 0.05). ANXA1sp can effectively reverse cognitive impairment in rats with SAE. The neuroprotective effect of ANXA1sp may be attributed to the activation of the PPAR-γ pathway, resulting in reduced neuroinflammatory response and inhibition of apoptosis.

A comprehensive insight into the molecular and cellular mechanisms of action of resveratrol on complications of sepsis a systematic review

Sepsis and septic shock are still one of the most important medical challenges. Sepsis is an extreme and uncontrolled response of the innate immune system to invading pathogenesis. Resveratrol (3,5,4'-trihydroxytrans-stilbene), is a phenolic and non-flavonoid compound naturally produced by some plants and fruits. The object of the current study is to systematically review the impacts of resveratrol and its mechanisms of function in the management of sepsis and its related complications. The guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statements were applied to perform the study (PROSPERO: CRD42021289357). We searched Embase, Web of Science, Google Scholar, Science Direct, PubMed, ProQuest, and Scopus databases up to January 2023 by using the relevant keywords. Study criteria were met by 72 out of 1415 articles screened. The results of this systematic review depict that resveratrol can reduces the complications of sepsis by affecting inflammatory pathways, oxidative stress, and modulating immune responses. Future human randomized clinical trials are necessary due to the promising therapeutic effects of resveratrol on sepsis complications and the lack of clinical trials in this regard.

HMGB1 in depression: An overview of microglial HMBG1 in the pathogenesis of depression

Depression is a prevalent psychiatric disorder with elusive pathogenesis. Studies have proposed that enhancement and persistence of aseptic inflammation in the central nervous system (CNS) may be closely associated with the development of depressive disorder. High mobility group box 1 (HMGB1) has obtained significant attention as an evoking and regulating factor in various inflammation-related diseases. It is a non-histone DNA-binding protein that can be released as a pro-inflammatory cytokine by glial cells and neurons in the CNS. Microglia, as the immune cell of the brain, interacts with HMGB1 and induces neuroinflammation and neurodegeneration in the CNS. Therefore, in the current review, we aim to investigate the role of microglial HMGB1 in the pathogenetic process of depression.

The role of NLRP3 inflammasome in sepsis: A potential therapeutic target

Sepsis is the host immune imbalance following infection and leads to organ dysfunction, with highly complicated pathophysiology. To date, sepsis still lacks effective therapies with high mortality rates. Recently, numerous studies have highlighted the potential of NLRP3 inflammasome as a therapeutic target during sepsis. NLRP3 inflammasome is a protein complex that could induce the activation of caspase-1 and the following release of pro-inflammatory cytokines such as IL-1β and IL-18. It was demonstrated that NLRP3 inflammasome was involved in the development and progression of sepsis. In contrast, inhibition of NLRP3 inflammasome activation could mitigate the inflammatory response, protect organ function, and improve outcomes and mortality. This paper illustrated the activation pathways of the NLRP3 inflammasome and its possible molecular mechanisms in the pathophysiology of sepsis. Meanwhile, the beneficial effects of inhibiting NLRP3 activation in sepsis-related organ damage were also presented. In addition, the diverse role of NLRP3 inflammasome in bacterial clearance was addressed. Of note, several herbal extracts targeting NLRP3 inflammasome in the treatment of sepsis were emphasized. We hope that this paper could provide a basis for further drug research targeting NLRP3 inflammasome.

HSF1 Alleviates Brain Injury by Inhibiting NLRP3-Induced Pyroptosis in a Sepsis Model

Background

Sepsis, which could cause a systemic inflammatory response, is a life-threatening disease with a high morbidity and mortality rate. There is evidence that brain injury may be related to severe systemic infection induced by sepsis. The brain injury caused by sepsis could increase the risk of mortality in septic patients, which seriously affects the septic patient's prognosis of survival. Although there remains a focus on sepsis research, clinical measures to prevent and treat brain injury in sepsis are not yet available, and the high mortality rate is still a big health burden. Therefore, it is necessary to investigate the new molecules or regulated pathways that can effectively inhibit the progress of sepsis.

Objective

NLR family pyrin domain-containing 3 (NLRP3) increased in the procession of sepsis and functioned as the key regulator of pyroptosis. Heat shock factor 1 (HSF1) can protect organs from multiorgan dysfunction syndrome induced by lipopolysaccharides in mice, and NLRP3 could be inhibited by HSF1 in many organs. However, whether HSF1 regulated NLRP3 in sepsis-induced brain injury, as well as the detailed mechanism of HSF1 in brain injury, remains unknown in the sepsis model. In this research, we try to explore the relationship between HSF1 and NLRP3 in a sepsis model and try to reveal the mechanism of HSF1 inhibiting the process of brain injury.

Methods

In this study, we used wild-type mice and hsf1 ^-/- mice for in vivo research and PC12 cells for in vitro research. Real-time PCR and Western blot were used to analyze the expression of HSF1, NLRP3, cytokines, and pyrolytic proteins. EthD-III staining was chosen to detect the pyroptosis of the hippocampus and PC12 cells.

Results

The results showed that HSF1 is negatively related to pyroptosis. The pyroptosis in cells of brain tissue was significantly increased in the hsf1 ^-/- mouse model compared to hsf1 ^+/+ mice. In PC12 cells, hsf1 siRNA can upregulate pyroptosis while HSF1-transfected plasmid could inhibit the pyroptosis. HSF1 could negatively regulate the NLRP3 pathway in PC12 cells, while hsf1 siRNA enhanced the pyroptosis in PC12 cells, which could be reversed by nlrp3 siRNA.

Conclusion

These results imply that HSF1 could alleviate sepsis-induced brain injury by inhibiting pyroptosis through the NLRP3-dependent pathway in brain tissue and PC12 cells, suggesting HSF1 as a potential molecular target for treating brain injury in sepsis clinical studies.

Electroacupuncture Alleviates Neuroinflammation by Inhibiting the HMGB1 Signaling Pathway in Rats with Sepsis-Associated Encephalopathy

Sepsis-Associated Encephalopathy (SAE) is common in sepsis patients, with high mortality rates. It is believed that neuroinflammation is an important mechanism involved in SAE. High mobility group box 1 protein (HMGB1), as a late pro-inflammatory factor, is significantly increased during sepsis in different brain regions, including the hippocampus. HMGB1 causes neuroinflammation and cognitive impairment through direct binding to advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4). Electroacupuncture (EA) at Baihui (GV20) and Zusanli (ST36) is beneficial for neurological diseases and experimental sepsis. Our study used EA to treat SAE induced by lipopolysaccharide (LPS) in male Sprague-Dawley rats. The Y maze test was performed to assess working memory. Immunofluorescence (IF) and Western blotting (WB) were used to determine neuroinflammation and the HMGB1 signaling pathway. Results showed that EA could improve working memory impairment in rats with SAE. EA alleviated neuroinflammation by downregulating the hippocampus's HMGB1/TLR4 and HMGB1/RAGE signaling, reducing the levels of pro-inflammatory factors, and relieving microglial and astrocyte activation. However, EA did not affect the tight junctions' expression of the blood-brain barrier (BBB) in the hippocampus.

HMGB1 is a critical molecule in the pathogenesis of Gram-negative sepsis

Gram-negative sepsis is a severe clinical syndrome associated with significant morbidity and mortality. Lipopolysaccharide (LPS), expressed on Gram-negative bacteria, is a potent pro-inflammatory toxin that induces inflammation and coagulation via two separate receptor systems. One is Toll-like receptor 4 (TLR4), expressed on cell surfaces and in endosomes, and the other is the cytosolic receptor caspase-11 (caspases-4 and -5 in humans). Extracellular LPS binds to high mobility group box 1 (HMGB1) protein, a cytokine-like molecule. The HMGB1-LPS complex is transported via receptor for advanced glycated end products (RAGE)-endocytosis to the endolysosomal system to reach the cytosolic LPS receptor caspase-11 to induce HMGB1 release, inflammation, and coagulation that may cause multi-organ failure. The insight that LPS needs HMGB1 assistance to generate severe inflammation has led to successful therapeutic results in preclinical Gram-negative sepsis studies targeting HMGB1. However, to date, no clinical studies have been performed based on this strategy. HMGB1 is also actively released by peripheral sensory nerves and this mechanism is fundamental for the initiation and propagation of inflammation during tissue injury. Homeostasis is achieved when other neurons actively restrict the inflammatory response via monitoring by the central nervous system and the vagus nerve through the cholinergic anti-inflammatory pathway. The neuronal control in Gram-negative sepsis needs further studies since a deeper understanding of the interplay between HMGB1 and acetylcholine may have beneficial therapeutic implications. Herein, we review the synergistic overlapping mechanisms of LPS and HMGB1 and discuss future treatment opportunities in Gram-negative sepsis.

Neuroinflammation Following Traumatic Brain Injury: Take It Seriously or Not

Traumatic brain injury (TBI) is associated with high mortality and disability, with a substantial socioeconomic burden. With the standardization of the treatment process, there is increasing interest in the role that the secondary insult of TBI plays in outcome heterogeneity. The secondary insult is neither detrimental nor beneficial in an absolute sense, among which the inflammatory response was a complex cascade of events and can thus be regarded as a double-edged sword. Therefore, clinicians should take the generation and balance of neuroinflammation following TBI seriously. In this review, we summarize the current human and animal model studies of neuroinflammation and provide a better understanding of the inflammatory response in the different stages of TBI. In particular, advances in neuroinflammation using proteomic and transcriptomic techniques have enabled us to identify a functional specific delineation of the immune cell in TBI patients. Based on recent advances in our understanding of immune cell activation, we present the difference between diffuse axonal injury and focal brain injury. In addition, we give a figurative profiling of the general paradigm in the pre- and post-injury inflammatory settings employing a bow-tie framework.