HMGB1 from Astrocytes Promotes EAE by Influencing the Immune Cell Infiltration-Associated Functions of BMECs in Mice

Astrocytes-Secreted WNT5B Disrupts the Blood-Brain Barrier Via ROR1/JNK/c-JUN Cascade During Meningitic Escherichia Coli Infection

The blood-brain barrier (BBB) is a complex structure that separates the central nervous system (CNS) from the peripheral blood circulation. Effective communication between different cell types within the BBB is crucial for its proper functioning and maintenance of homeostasis. In this study, we demonstrate that meningitic Escherichia coli (E. coli)-induced WNT5B plays a role in facilitating intercellular communication between astrocytes and brain microvascular endothelial cells (BMECs). We discovered that astrocytes-derived WNT5B activates the non-canonical WNT signaling pathway JNK/c-JUN in BMECs through its receptor ROR1, leading to inhibition of ZO-1 expression and impairment of the tight junction integrity in BMECs. Notably, our findings reveal that c-JUN, a transcription factor, directly regulates ZO-1 expression. By employing a dual luciferase reporting system and chromatin immunoprecipitation techniques, we identified specific binding sites of c-JUN on the ZO-1 promoter region. Overall, our study highlights the involvement of WNT5B in mediating intercellular communication between astrocytes and BMECs, provides insights into the role of WNT5B in meningitic E. coli-induced disruption of BBB integrity, and suggests potential therapeutic targeting of WNT5B as a strategy to address BBB dysfunction.

CD8+T cell infiltration-associated barrier function of brain endothelial cells is enhanced by astragalus polysaccharides via inhibiting the PI3K/AKT signaling pathway

Pathogenic CD8+T cells play an essential role in neuroinflammation and neural injury, which leads to the progression of inflammatory neurological disorders. Thus, blocking the infiltration of CD8+T cells is necessary for the treatment of neuroinflammatory diseases. Our previous study demonstrated that astragalus polysaccharide (APS) could significantly reduce the infiltration of CD8+T cells in experimental autoimmune encephalomyelitis mice. However, the mechanism by which APS suppresses CD8+T cell infiltration remains elusive. In this study, we further found that APS could reduce the CD8+T cell infiltration in experimental autoimmune encephalomyelitis and lipopolysaccharide (LPS)-induced neuroinflammatory model. Furthermore, we established the mouse brain endothelial cell (bEnd.3) inflammatory injury model by interleukin-1β or LPS in vitro. The results showed that APS treatment downregulated the expression of vascular cell adhesion molecule1 to decrease the adhesion of CD8+T cells to bEnd.3 cells. APS also upregulated the expression of zonula occludens-1 and vascular endothelial cadherin to reduce the transendothelial migration of CD8+T cells. The PI3K/AKT signaling pathway might mediate this protective effect of APS on bEnd.3 cells against inflammatory injury. In addition, we demonstrated the protective effect of APS on the integrity of brain endothelial cells in an LPS-induced neuroinflammatory model. In summary, our results indicate that APS can reduce peripheral CD8+T cell infiltration via enhancing the barrier function of brain endothelial cells; it may be a potential for the prevention of neuroinflammatory diseases.

The Involvement of Glial Cells in Blood-Brain Barrier Damage in Neuroimmune Diseases

The blood-brain barrier and glial cells, particularly astrocytes, interact with each other in neuroimmune diseases. In the inflammatory environment typical of these diseases, alterations in vascular endothelial cell surface molecules and weakened cell connections allow immune cells and autoantibodies to enter the central nervous system. Glial cells influence the adhesion of endothelial cells by changing their morphology and releasing various signaling molecules. Multiple sclerosis has been the most studied disease in relation to vascular endothelial and glial cell interactions, but these cells also significantly affect the onset and severity of other neuroimmune conditions, including demyelinating and inflammatory diseases. In this context, we present an overview of these interactions and highlight how they vary across different neuroimmune diseases.

Roles of HMGB1 on life-threatening traumatic brain injury and sequential peripheral organ damage

Traumatic brain injury (TBI) has been found to be associated with certain peripheral organ injuries; however, a few studies have explored the chronological influences of TBI on multiple organs and the systemic effects of therapeutic interventions. Particularly, high-mobility group box 1 (HMGB1) is a potential therapeutic target for TBI; however, its effects on peripheral organs remain unclear. Therefore, this study aimed to determine whether severe TBI can lead to multiple organ injury and how HMGB1 inhibition affects peripheral organs. This study used a weight drop-induced TBI mouse model and found that severe TBI can trigger short-lived systemic inflammation, in the lungs and liver, but not in the kidneys, regardless of the severity of the injury. TBI led to an increase in circulating HMGB1 and enhanced gene expressions of its receptors in every organ. Anti-HMGB1 antibody treatment reduced neuroinflammation but increased inflammation in peripheral organs. This study also found that HMGB1 inhibition appears to have a beneficial role in early neuroinflammation but could lead to detrimental effects on peripheral organs through decreased peripheral immune suppression. This study provides novel insights into the chronological changes in multiple organs due to TBI and the unique roles of HMGB1 between the brain and other organs.

Active secretion of IL-33 from astrocytes is dependent on TMED10 and promotes central nervous system homeostasis

Interleukin-33 (IL-33), secreted by astrocytes, regulates the synapse development in the spinal cord and hippocampus and suppresses autoimmune disease in the central nervous system (CNS). However, the mechanism of unconventional protein secretion of this cytokine remains unclear. In this study, we found that IFN-γ promotes the active secretion of IL-33 from astrocytes, and the active secretion of IL-33 from cytoplasm to extracellular space was dependent on interaction with transmembrane emp24 domain 10 (TMED10) via the IL-1 like cytokine domain in astrocytes. Knockout of Il-33 or its receptor St2 induced hippocampal astrocyte activation and depressive-like disorder in naive mice, as well as increased spinal cord astrocyte activation and polarization to a neurotoxic reactive subtype and aggravated passive experimental autoimmune encephalomyelitis (EAE). Our results have identified that IL-33 is actively secreted by astrocytes through the unconventional protein secretion pathway facilitated by TMED10 channels. This process helps maintain CNS homeostasis by inhibiting astrocyte activation.

IGF2BP3 prevent HMGB1 mRNA decay in bladder cancer and development

BACKGROUND

IGF2BP3 functions as an RNA-binding protein (RBP) and plays a role in the posttranscriptional control of mRNA localization, stability, and translation. Its dysregulation is frequently associated with tumorigenesis across various cancer types. Nonetheless, our understanding of how the expression of the IGF2BP3 gene is regulated remains limited. The specific functions and underlying mechanisms of IGF2BP3, as well as the potential benefits of targeting it for therapeutic purposes in bladder cancer, are not yet well comprehended.

METHODS

The mRNA and protein expression were examined by RT-qPCR and western blotting, respectively. The methylation level of CpG sites was detected by Bisulfite sequencing PCR (BSP). The regulation of IGF2BP3 expression by miR-320a-3p was analyzed by luciferase reporter assay. The functional role of IGF2BP3 was determined through proliferation, colony formation, wound healing, invasion assays, and xenograft mouse model. The regulation of HMGB1 by IGF2BP3 was investigated by RNA immunoprecipitation (RIP) and mRNA stability assays.

RESULTS

We observed a significant elevation in IGF2BP3 levels within bladder cancer samples, correlating with more advanced stages and grades, as well as an unfavorable prognosis. Subsequent investigations revealed that the upregulation of IGF2BP3 expression is triggered by copy number gain/amplification and promoter hypomethylation in various tumor types, including bladder cancer. Furthermore, miR-320a-3p was identified as another negative regulator in bladder cancer. Functionally, the upregulation of IGF2BP3 expression exacerbated bladder cancer progression, including the proliferation, migration, and invasion of bladder cancer. Conversely, IGF2BP3 silencing produced the opposite effects. Moreover, IGF2BP3 expression positively correlated with inflammation and immune infiltration in bladder cancer. Mechanistically, IGF2BP3 enhanced mRNA stability and promoted the expression of HMGB1 by binding to its mRNA, which is a factor that promotes inflammation and orchestrates tumorigenesis in many cancers. Importantly, pharmacological inhibition of HMGB1 with glycyrrhizin, a specific HMGB1 inhibitor, effectively reversed the cancer-promoting effects of IGF2BP3 overexpression in bladder cancer. Furthermore, the relationship between HMGB1 mRNA and IGF2PB3 is also observed in mammalian embryonic development, with the expression of both genes gradually decreasing as embryonic development progresses.

CONCLUSIONS

Our present study sheds light on the genetic and epigenetic mechanisms governing IGF2BP3 expression, underscoring the critical involvement of the IGF2BP3-HMGB1 axis in driving bladder cancer progression. Additionally, it advocates for the investigation of inhibiting IGF2BP3-HMGB1 as a viable therapeutic approach for treating bladder cancer.

Early Growth Response Gene-1 Deficiency Interrupts TGFβ1 Signaling Activation and Aggravates Neurodegeneration in Experimental Autoimmune Encephalomyelitis Mice

Early growth response protein 1 (Egr-1) triggers the transcription of many genes involved in cell growth, differentiation, synaptic plasticity, and neurogenesis. However, its mechanism in neuronal survival and degeneration is still poorly understood. This study demonstrated that Egr-1 was down-regulated at mRNA and protein levels in the central nervous system (CNS) of experimental autoimmune encephalomyelitis (EAE) mice. Egr-1 knockout exacerbated EAE progression in mice, as shown by increased disease severity and incidence; it also aggravated neuronal apoptosis, which was associated with weakened activation of the BDNF/TGFβ 1/MAPK/Akt signaling pathways in the CNS of EAE mice. Consistently, Egr-1 siRNA promoted apoptosis but mitigated the activation of BDNF/TGFβ 1/MAPK/Akt signaling in SH-SY5Y cells. Our results revealed that Egr-1 is a crucial regulator of neuronal survival in EAE by regulating TGFβ 1-mediated signaling activation, implicating the important role of Egr-1 in the pathogenesis of multiple sclerosis as a potential novel therapy target.

Role of DAMPs and cell death in autoimmune diseases: the example of multiple sclerosis

Multiple sclerosis is a chronic neuroinflammatory demyelinating disease of the central nervous system (CNS) of unknown etiology and still incompletely clarified pathogenesis. The disease is generally considered a disorder resulting from a complex interplay between environmental risk factors and predisposing causal genetic variants. To examine the etiopathogenesis of the disease, two complementary pre-clinical models are currently discussed: the "outside-in" model proposing a peripherally elicited inflammatory/autoimmune attack against degraded myelin as the cause of the disease, and the "inside-out" paradigm implying a primary cytodegenerative process of cells in the CNS that triggers secondary reactive inflammatory/autoimmune responses against myelin debris. In this review, the integrating pathogenetic role of damage-associated molecular patterns (DAMPs) in these two scenario models is examined by focusing on the origin and sources of these molecules, which are known to promote neuroinflammation and, via activation of pattern recognition receptor-bearing antigen-presenting cells, drive and shape autoimmune responses. In particular, environmental factors are discussed that are conceptually defined as agents which produce endogenous DAMPs via induction of regulated cell death (RCD) or act themselves as exogenous DAMPs. Indeed, in the field of autoimmune diseases, including multiple sclerosis, recent research has focused on environmental triggers that cause secondary events in terms of subroutines of RCD, which have been identified as prolific sources of DAMPs. Finally, a model of a DAMP-driven positive feed-forward loop of chronic inflammatory demyelinating processes is proposed, aimed at reconciling the competing "inside-out" and "outside-in" paradigms.