Tripartite Motif Containing 52 Positively Regulates NF-κB Signaling by Promoting IκBα Ubiquitination in Lipopolysaccharide-Treated Microglial Cell Activation

It's a TRIM-endous view from the top: the varied roles of TRIpartite Motif proteins in brain development and disease

The tripartite motif (TRIM) protein family members have been implicated in a multitude of physiologies and pathologies in different tissues. With diverse functions in cellular processes including regulation of signaling pathways, protein degradation, and transcriptional control, the impact of TRIM dysregulation can be multifaceted and complex. Here, we focus on the cellular and molecular roles of TRIMs identified in the brain in the context of a selection of pathologies including cancer and neurodegeneration. By examining each disease in parallel with described roles in brain development, we aim to highlight fundamental common mechanisms employed by TRIM proteins and identify opportunities for therapeutic intervention.

TRIM52 aggravated inflammation and pyroptosis in dextran sulfate sodium-induced inflammatory bowel disease through activation of the TLR4/NF-κBs pathway

INTRODUCTION

Inflammatory bowel disease (IBD), which mainly leads to diarrhea, fatigue, stool blood, abdominal pain, and cramping, is threatening public health. Tripartite motif-containing 52 (TRIM52) has been reported to play an important role in inflammatory responses via activating the toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway. However, the causes of IBD need to be elucidated, and the function of TRIM52 in IBD remains unclear. Here, we demonstrated that TRIM52 aggravated inflammation and pyroptosis in dextran sulfate sodium (DSS)-induced IBD by activating TLR4/NF-κBs pathway.

METHODS

The colitis model was established on mice through DSS induction. For the TRIM52 knockdown, the mice were infected with a recombinant adenoviral vector expressing sgRNAs targeting TRIM52. RT-qPCR, western blot, and immunohistochemistry were performed to verify TRIM52 expression in DSS-induced IBD. The body weight, disease activity index, colon length, and H&E staining were used to assess the IBD symptoms in mice with TRIM52 knockdown. The inflammatory responses were examined by RT-qPCR and ELISA measuring tumor necrosis factor-α (TNF-α), inter-leukin 6 (IL-6), and interleukin 1β (IL-1β). Furthermore, the pyroptosis in colon tissue was detected by western blot. Finally, the TLR4/NF-κBs pathway activity was also examined by western blot.

RESULTS

TRIM52 expression was up-regulated in DSS-induced IBD, and knockdown of TRIM52 could alleviate the symptoms of IBD. TRIM52 knockdown retarded DSS-induced inflammatory response and inhibited DSS-induced pyroptosis in colon tissue. In addition, TRIM52 played a role in activating TLR4/NF-κBs pathway.

CONCLUSION

Knockdown of TRIM52 alleviated inflammation and pyroptosis in IBD by regulating TLR4/NF-κBs pathway. TRIM52 is expected to be a novel diagnostic indicator for IBD and a target of therapeutic treatment.

Duloxetine ameliorates lipopolysaccharide-induced microglial activation by suppressing iNOS expression in BV-2 microglial cells

RATIONALE

It is known that both selective serotonin and serotonin noradrenaline reuptake inhibitors (SSRI, SNRI) are first-line drugs for the treatment of major depressive disorder. It has also been considered that both SSRI and SNRI can improve the symptoms of major depressive disorder by increasing the concentration of monoamine in the synaptic cleft based on the monoamine hypothesis. However, accumulating evidence has indicated that inflammation in the brain may be a key factor in the pathophysiological mechanisms that underlie the development of major depressive disorder.

OBJECTIVES

It has been advocated that microglial cells may regulate the inflammatory response under pathological conditions such as major depressive disorder. In this study, we focused on whether duloxetine can ameliorate the inflammatory response induced by lipopolysaccharide (LPS) in BV-2 microglial cells.

RESULTS

Our results indicated that duloxetine significantly decreased the NO production induced by LPS. The increase in the protein expression level of iNOS induced by LPS was significantly decreased by treatment with duloxetine. Moreover, the increases in the protein expression levels of phosphorylated-IκBα, phosphorylated-Akt and Akt induced by LPS were also significantly decreased. Unexpectedly, the protein expression levels of other pro-inflammatory factors such as COX-2 and the phosphorylation ratios for various molecules including IκBα and Akt were not changed by treatment with duloxetine.

CONCLUSIONS

These findings suggest that duloxetine may have an anti-inflammatory effect, which could contribute to its therapeutic effectiveness for major depressive disorder.

Bioinformatics-Based Approach for Exploring the Immune Cell Infiltration Patterns in Alzheimer's Disease and Determining the Intervention Mechanism of Liuwei Dihuang Pill

Traditional Chinese medicine (TCM) compounds have recently garnered attention for the regulation of immune cell infiltration and the prevention and treatment of Alzheimer's disease (AD). The Liuwei Dihuang Pill (LDP) has potential in this regard; however, its specific molecular mechanism currently remains unclear. Therefore, we adopted a bioinformatics approach to investigate the infiltration patterns of different types of immune cells in AD and explored the molecular mechanism of LDP intervention, with the aim of providing a new basis for improving the clinical immunotherapy of AD patients. We found that M1 macrophages showed significantly different degrees of infiltration between the hippocampal tissue samples of AD patients and healthy individuals. Four immune intersection targets of LDP in the treatment of AD were identified; they were enriched in 206 biological functions and 30 signaling pathways. Quercetin had the best docking effect with the core immune target PRKCB. Our findings suggest that infiltrated immune cells may influence the course of AD and that LDP can regulate immune cell infiltration through multi-component, multi-target, and multi-pathway approaches, providing a new research direction regarding AD immunotherapy.