Regulatory mechanisms of natural compounds from traditional Chinese herbal medicines on the microglial response in ischemic stroke

ABBV-744 alleviates LPS-induced neuroinflammation via regulation of BATF2-IRF4-STAT1/3/5 axis

Suppression of neuroinflammation using small molecule compounds targeting the key pathways in microglial inflammation has attracted great interest. Recently, increasing attention has been gained to the role of the second bromodomain (BD2) of the bromodomain and extra-terminal (BET) proteins, while its effect and molecular mechanism on microglial inflammation has not yet been explored. In this study, we evaluated the therapeutic effects of ABBV-744, a BD2 high selective BET inhibitor, on lipopolysaccharide (LPS)-induced microglial inflammation in vitro and in vivo, and explored the key pathways by which ABBV-744 regulated microglia-mediated neuroinflammation. We found that pretreatment of ABBV-744 concentration-dependently inhibited the expression of LPS-induced inflammatory mediators/enzymes including NO, TNF-α, IL-1β, IL-6, iNOS, and COX-2 in BV-2 microglial cells. These effects were validated in LPS-treated primary microglial cells. Furthermore, we observed that administration of ABBV-744 significantly alleviated LPS-induced activation of microglia and transcriptional levels of pro-inflammatory factors TNF-α and IL-1β in mouse hippocampus and cortex. RNA-Sequencing (RNA-seq) analysis revealed that ABBV-744 induced 508 differentially expressed genes (DEGs) in LPS-stimulated BV-2 cells, and gene enrichment and gene expression network analysis verified its regulation on activated microglial genes and inflammatory pathways. We demonstrated that pretreatment of ABBV-744 significantly reduced the expression levels of basic leucine zipper ATF-like transcription factor 2 (BATF2) and interferon regulatory factor 4 (IRF4), and suppressed JAK-STAT signaling pathway in LPS-stimulated BV-2 cells and mice, suggesting that the anti-neuroinflammatory effect of ABBV-744 might be associated with regulation of BATF2-IRF4-STAT1/3/5 pathway, which was confirmed by gene knockdown experiments. This study demonstrates the effect of a BD2 high selective BET inhibitor, ABBV-744, against microglial inflammation, and reveals a BATF2-IRF4-STAT1/3/5 pathway in regulation of microglial inflammation, which might provide new clues for discovery of effective therapeutic strategy against neuroinflammation.

Therapeutic effect and mechanisms of traditional Chinese medicine compound (Qilong capsule) in the treatment of ischemic stroke

Background Qilong capsule (QLC) is a well-known traditional Chinese medicine compound extensively used in clinical practice. It has been approved by the China's FDA for the treatment of ischemic stroke (IS). In our clinical trial involving QLC (ClinicalTrials.gov identifier: NCT03174535), we observed the potential of QLC to improve neurological function in IS patients at the 24th week, while ensuring their safety. However, the effectiveness of QLC beyond the initial 12-week period remains uncertain, and the precise mechanisms underlying its action in IS have not been fully elucidated. Purpose In order to further explore the clinical efficacy of QLC in treating IS beyond the initial 12-week period and systematically elucidate its underlying mechanisms. Study Design This study employed an interdisciplinary integration strategy that combines post hoc analysis of clinical trials, transcriptome sequencing, integrated bioinformatics analysis, and animal experiments. Methods In this study, we conducted a post-hoc analysis with 2302 participants to evaluate the effectiveness of QLC at the 12th week. The primary outcome was the proportion of patients achieving functional independence at the 12th week, defined as a score of 0-2 on the modified Rankin Scale (mRS), which ranges from 0 (no symptoms) to 6 (death). Subsequently, we employed RNA sequencing (RNA-Seq) and quantitative reverse transcription polymerase chain reaction (RT-qPCR) techniques in the QLC trial to investigate the potential molecular mechanisms underlying the therapeutic effect of QLC in IS. Simultaneously, we utilized integrated bioinformatics analyses driven by external multi-source data and algorithms to further supplement the exploration and validation of QLC's therapeutic mechanism in treating IS. This encompassed network pharmacology analysis and analyses at the mRNA, cellular, and pathway levels focusing on core targets. Additionally, we developed a disease risk prediction model using machine learning. By identifying differentially expressed core genes (DECGs) between the normal and IS groups, we quantitatively predicted IS occurrence. Furthermore, to assess its protective effects and determine the key regulated pathway, we conducted experiments using a middle cerebral artery occlusion and reperfusion (MACO/R) rat model. Results Our findings demonstrated that the combination of QLC and conventional treatment (CT) significantly improved the proportion of patients achieving functional independence (mRS score 0-2) at the 12th week compared to CT alone (n = 2,302, 88.65 % vs 87.33 %, p = 0.3337; n = 600, 91.33 % vs 84.67 %, p = 0.0165). Transcriptome data revealed that the potential underlying mechanism of QLC for IS is related to the regulation of the NF-κB inflammatory pathway. The RT-qPCR results demonstrated that the regulatory trends of key genes, such as MD-2, were consistent with those observed in the RNA-Seq analysis. Integrated bioinformatics analysis elucidated that QLC regulates the NF-κB signaling pathway by identifying core targets, and machine learning was utilized to forecast the risk of IS onset. The MACO/R rat model experiment confirmed that QLC exerts its anti-CIRI effects by inhibiting the MD-2/TLR-4/NF-κB signaling axis. Conclusion: Our interdisciplinary integration study has demonstrated that the combination of QLC with CT exhibits significant superiority over CT alone in improving functional independence in patients at the 12th week. The potential mechanism underlying QLC's therapeutic effect in IS involves the inhibition of the MD-2/TLR4/NF-κB inflammatory signaling pathway, thereby attenuating cerebral ischemia/reperfusion inflammatory injury and facilitating neurofunctional recovery. The novelty and innovative potential of this study primarily lie in the novel finding that QLC significantly enhances the proportion of patients achieving functional independence (mRS score 0-2) at the 12th week. Furthermore, employing a "multilevel-multimethod" integrated research approach, we elucidated the potential mechanism underlying QLC's therapeutic effect in IS.

A natural small molecule aspidosperma-type alkaloid, hecubine, as a new TREM2 activator for alleviating lipopolysaccharide-induced neuroinflammation in vitro and in vivo

Neuroinflammation and oxidative stress play a crucial role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease. The triggering receptor expressed on myeloid cells 2 (TREM2), highly expressed by microglia in the central nervous system (CNS), can modulate neuroinflammatory responses. Currently, there are no approved drugs specifically targeting TREM2 for CNS diseases. Aspidosperma alkaloids have shown potential as anti-inflammatory and neuroprotective agents. This study aimed to elucidate the potential therapeutic effect of Hecubine, a natural aspidosperma-type alkaloid, as a TREM2 activator in lipopolysaccharide (LPS)-stimulated neuroinflammation in in vitro and in vivo models. In this study, molecular docking and cellular thermal shift assay (CTSA) were employed to investigate the interaction between Hecubine and TREM2. Enzyme-linked immunosorbent assay (ELISA), quantitative PCR, immunofluorescence, Western blotting, and shRNA gene knockdown were used to assess the anti-neuroinflammatory and antioxidant effects of Hecubine in microglial cells and zebrafish. Our results revealed that Hecubine directly interacted with TREM2, leading to its activation. Knockdown of TREM2 mRNA expression significantly abolished the anti-inflammatory and antioxidant effects of Hecubine on LPS-stimulated proinflammatory mediators (NO, TNF-α, IL-6, and IL-1β) and oxidative stress in microglia cells. Furthermore, Hecubine upregulated Nrf2 expression levels while downregulating TLR4 signaling expression levels both in vivo and in vitro. Silencing TREM2 upregulated TLR4 and downregulated Nrf2 signaling pathways, mimicking the effect of Hecubine, further supporting TREM2 as the drug target by which Hecubine inhibits neuroinflammation. In conclusion, this is the first study to identify a small molecule, namely Hecubine directly targeting TREM2 to mediate anti-neuroinflammation and anti-oxidative effects, which serves as a potential therapeutic agent for the treatment of neural inflammation-associated CNS diseases.