Regulation of TREM2 on BV2 inflammation through PI3K/AKT/mTOR pathway

TREM2 Alleviates Neuroinflammation by Maintaining Cellular Metabolic Homeostasis and Mitophagy Activity During Early Inflammation

AIMS

Inflammation is a pivotal characteristic of neurodegenerative diseases. The triggering receptor expressed on the myeloid cells 2 (TREM2) gene has previously been shown to suppress inflammation by directly inhibiting inflammation-related pathways. Mitochondrial dysfunction has recently emerged as another critical pathological manifestation of neurodegenerative diseases. Although TREM2 is involved in the regulation of cellular energy metabolism and mitochondrial autophagy, its role in the relationship between inflammation and mitochondrial autophagy remains unclear.

METHODS

In this study, we generated TREM2-overexpressing BV-2 cells and established a neuroinflammatory model with LPS. We compared these cells with wild-type cells in terms of inflammation, metabolism, autophagy, and mitochondria using methods such as RT-qPCR, Western blotting, immunocytochemistry, transmission electron microscopy, and flow cytometry.

RESULTS

Microglia overexpressing TREM2 exhibited increased resistance to inflammation. Additionally, these cells inhibited the metabolic reprogramming that occurs early in LPS-induced inflammation, reduced ROS release, mitigated mitochondrial damage, maintained a certain level of autophagic activity, and cleared damaged mitochondria. Consequently, they alleviated the inflammation caused by the mitochondrial barrier.

CONCLUSIONS

ur results suggest that TREM2 can alleviate inflammation by maintaining cellular metabolic homeostasis and mitochondrial autophagy activity.

Identification of BCL3 as a biomarker for chondrocyte programmed cell death in osteoarthritis

Osteoarthritis (OA) is a condition that is widely prevalent and causes joint pain and disability, with programmed cell death (PCD) playing a role in its pathogenesis. This study aimed to identify biomarkers associated with PCD in OA and explore their potential roles. Three RNA-sequencing datasets (GSE114007, GSE51588 and GSE220243) related to OA were analysed. Differential expression and weighted gene co-expression network identified key differentially expressed PCD-related genes (DE-PRMGs). Potential biomarkers were identified and validated through receiver operating characteristic (ROC) curves, correlation analyses, gene set enrichment analysis, single-cell expression and RT-qPCR. A total of 45 DE-PRMGs were identified, affecting pathways like TNF signalling and RNA degradation. BCL3, TREM2 and NRP2 were prioritized as potential OA biomarkers, which are associated with ribosome function and immune cell infiltration and potentially linked to PCD. The functional role of one of the molecules identified, BCL3, was explored further using a cell model of inflammation induced chondrocytes. BCL3 was significantly down regulated in OA samples from the public dataset and clinical samples analysed by RT-qPCR. BCL3 overexpression reduced apoptosis in chondrocytes stimulated with inflammatory cytokines. Thus the functional studies highlighted the anti-apoptotic role of BCL3 in chondrocytes and provide new insights into OA pathogenesis with potential for future therapeutic development.

Biomimetic Nanovesicles as a Dual Gene Delivery System for the Synergistic Gene Therapy of Alzheimer's Disease

The association between dysfunctional microglia and amyloid-β (Aβ) is a fundamental pathological event and increases the speed of Alzheimer's disease (AD). Additionally, the pathogenesis of AD is intricate and a single drug may not be enough to achieve a satisfactory therapeutic outcome. Herein, we reported a facile and effective gene therapy strategy for the modulation of microglia function and intervention of Aβ anabolism by ROS-responsive biomimetic exosome-liposome hybrid nanovesicles (designated as TSEL). The biomimetic nanovesicles codelivery β-site amyloid precursor protein cleaving enzyme-1 (BACE1) siRNA (siBACE1) and TREM2 plasmid (pTREM2) gene drug efficiently penetrate the blood-brain barrier and enhance the drug accumulation at AD lesions with the help of exosomes homing ability and angiopep-2 peptides. Specifically, an upregulation of TREM2 expression can reprogram microglia from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype while also restoring its capacity to phagocytose Aβ and its nerve repair function. In addition, siRNA reduces the production of Aβ plaques at the source by knocking out the BACE1 gene, which is expected to further enhance the therapeutic effect of AD. The in vivo study suggests that TSEL through the synergistic effect of two gene drugs can ameliorate APP/PS1 mice cognitive impairment by regulating the activated microglial phenotype, reducing the accumulation of Aβ, and preventing the retriggering of neuroinflammation. This strategy employs biomimetic nanovesicles for the delivery of dual nucleic acids, achieving synergistic gene therapy for AD, thus offering more options for the treatment of AD.