Blockade of Hepatocyte PCSK9 Ameliorates Hepatic Ischemia-Reperfusion Injury by Promoting Pink1-Parkin-Mediated Mitophagy

Shenfu injection ameliorates hepatic ischemia-reperfusion injury through induction of ferroptosis via JAK2/STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Shenfu injection (SF) is a traditional Chinese medicine (TCM) compound preparation developed from the Shenfu decoction, which is described in the ancient Chinese medical book "Ji Sheng Fang" from the Song Dynasty. It is composed of two traditional Chinese medicines: Ginseng Radix et Rhizoma Rubra (G. Radix) and Aconiti Lateralis Radix Preparata (A. Lateralis). SF is renowned for its effects of restoring yang, rescuing adverse conditions, replenishing qi and consolidating deficiency. Research indicated that SF may enhance the recovery from Hepatic ischemia-reperfusion injury (HIRI), although its potential pharmacological mechanisms remain to be clearly defined.

AIM OF THE STUDY

To explore the pharmacological effects and mechanisms of SF in the treatment of HIRI.

MATERIALS AND METHODS

This study employed network pharmacology alongside both in vivo and in vitro experimental validation. It involved retrieving drug ingredients and targets from a database, constructing networks of chemical composition-targets- pathways and protein-protein interactions to pinpoint key targets. To evaluate the binding affinity between active ingredients and their respective targets, molecular docking was employed. Further, the study predicted potential targets and signaling pathways influenced by SF through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses. Finally, in vivo and in vitro experimental validation were performed using the HIRI mouse model and the oxygen-glucose deprivation/reperfusion (OGD/R)-induced AML12 cells model.

RESULTS

Findings from in vivo experiments indicated that SF could markedly lower serum glutamic pyruvic transaminase (ALT) and glutamic oxaloacetic transaminase (AST) levels, improve hepatic histopathological damage, reduce the count of myeloperoxidase (MPO) positive cells, and decrease the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in HIRI mice. Moreover, we investigated ferroptosis-related biomarkers and found that pretreatment with SF could significantly reduce the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and iron in both HIRI mice and OGD/R-induced AML12 cells. Furthermore, it boosted the activity of superoxide dismutase (SOD) and glutathione (GSH), upregulated the protein expression of glutathione Peroxidase 4 (GPX4), and elevated the mRNA expression of GPX4, solute carrier family 7 member 11 (SLC7A11), and prostaglandin-endoperoxide synthase 2 (PTGS2) in both in vivo and in vitro. The findings from the network pharmacology analysis showed that 51 active components of SF were effective against HIRI and 257 potential intersecting target points. Further screening identified five key targets: AKT1, IL-1β, TNF, STAT3, and PTGS2. KEGG pathway analysis enriched for signaling pathways such as JAK2/STAT3. Additionally, the outcomes of molecular docking revealed a significant binding affinity among the four primary active components of SF and their respective targets. Western blotting results indicated that SF could inhibit the activation of the JAK2/STAT3 pathway in HIRI mice and OGD/R-induced AML12 cells.

CONCLUSION

Through network pharmacology, molecular docking and in vivo and in vitro experiments, it was preliminarily demonstrated that SF attenuates HIRI through the induction of ferroptosis via JAK2/STAT3 pathway.

Met-Exo attenuates pyroptosis in miniature pig liver IRI by improving mitochondrial quality control

Metformin(Met) and adipose-derived stem cell exosomes(ADSCs-Exo) both demonstrate therapeutic effects on mitochondrial dysfunction and pyroptosis. There is also a phenomenon of mutual promotion between these two pathological states. The synergistic effect of metformin-loaded exosomes (Met-Exo) via electroporation in a miniature pig liver ischemia-reperfusion injury (IRI) model remains unexplored. This study established a liver IRI model in miniature pigs to compare the effects of ADSCs-Exo and Met-Exo. We found that Met-Exo intervention better activated the Adenosine 5'-monophosphate activated protein kinase (AMPK)/NAD-dependent deacetylase sirtuin-1(SIRT1) axis, improved mitochondrial dynamics, promoted mitochondrial biogenesis, and inhibited the sustained excessive autophagy of mitochondria after liver IRI. It was then demonstrated that by improving mitochondrial dysfunction, ATP production in liver tissue could be ensured, and ROS generation could be suppressed. This also further inhibited the occurrence of pyroptosis and ensured that mitochondria were protected from gasdermin D-N(GSDMD-N) attack. Met-Exo inhibited the occurrence of pyroptosis through the above pathways, reducing the release of inflammatory factors such as IL-1β and IL-18, and alleviating inflammation. This provides a new therapeutic approach for clinical treatment of liver IRI and improving the success rate of liver transplantation.

Aurantio-obtusin improves obesity and protects hepatic inflammation by rescuing mitochondrial damage in overwhelmed brown adipose tissue

BACKGROUND

Obesity is frequently linked to chronic systamic inflammation and presents significant challenges to public health. Aurantio-obtusin (AO) boosted the brown adipose tissue (BAT) thermogenesis in diet-induced obesity. However, the specific mechanisms by which injured mitochondria-related damage signals derived from overwhelmed BAT can transmit to liver and exacerbate metabolic disorders and whether AO can reverse this process remain unknown.

MATERIALS AND METHODS

After applying high-fat diet and glucose-fructose water (HFHS)-induced obesity mice, different BAT transplant procedures and primary BAT adipocytes, we investigated the anti-obesity effects and mechanism of AO through RNA sequencing and biology techniques.

RESULTS

AO improved whole-body lipid accumulation, mitochondrial metabolism in BAT and hepatic inflammation in HFHS-induced obesity mice. Interscapular transplant of BAT-derived from obese donor mice triggered hepatic inflammation of chow diet-fed recipient mice, which was protected by AO. Furthermore, the transplantation of BAT-derived from AO-treated mice protected hepatic inflammation in obese mice. In vivo and in lipid-challenged primary BAT adipocytes, AO decreased kexin type 9 (PCSK9), prevented mPTP opening and mitochondrial DNA (mtDNA) release in extracellular vesicles (EVs) manner by inhibiting the acetylation of cyclophilin D associated with adenine nucleotide translocase, suppressing oligomerization of voltage-dependent anion channel 1 and activating mitophagy. Ultimately, AO inhibited mtDNA-containing EVs-induced cyclic GMP-AMP synthase/stimulator of interferon genes (STING) activation and hepatic inflammation, which was confirmed by Sting-/- mice.

CONCLUSION

AO not only improves thermogenesis and mitochondrial function of BAT but also prevents liver inflammation by repairing mitochondrial function and blocking the transfer of mtDNA from BAT to the liver.

PCSK9 inhibitor alleviates experimental pulmonary fibrosis-induced pulmonary hypertension via attenuating epithelial-mesenchymal transition by suppressing Wnt/β-catenin signaling in vivo and in vitro

Background

The co-occurrence of pulmonary hypertension (PH) in patients with pulmonary fibrosis (PF) is linked to a more unfavorable prognosis and increased mortality compared to PF cases without PH. Early intervention and comprehensive management are pivotal for improving survival outcomes. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein essential in cholesterol metabolism. However, the potential for PCSK9 inhibition to alleviate PF-induced PH has not been previously reported.

Methods

A mouse model of PF-induced PH was established using intratracheal injection of bleomycin (BLM), followed by administration of a PCSK9 inhibitor every other day. Data on right ventricle (RV) remodeling and changes in pulmonary arteries were collected and analyzed. Transforming growth factor-beta (TGF-β) was also administered to MLE-12 cells as an experimental lung fibrosis model. The mechanisms of PCSK9's impact on lung fibrosis were examined both in vivo and in vitro.

Results

Inhibition of PCSK9 significantly reduced pulmonary artery thickening and RV remodeling in the BLM-induced mouse model. Moreover, the blockage of PCSK9 effectively attenuated the migration and epithelial-mesenchymal transition (EMT) process of TGF-β-induced MLE-12 cells. We also observed that the PCSK9 inhibitor suppressed the expression of the Wnt/β-catenin pathway in both animal and cell experiments.

Conclusion

PCSK9 plays a crucial role in the progression of PF-induced PH by regulating cell EMT and Wnt/β-catenin signaling. Targeting PCSK9 expression or activity could effectively control lung fibrosis and its PH complication.

Curcumin's Protective Role in Heatstroke-Induced Acute Liver Injury: Targeting Pyroptosis and Enhancing SIRT1 Expression

Heatstroke (HS) is a severe systemic condition that significantly impacts organ function, with the liver being particularly vulnerable. Sirtuin 1 (SIRT1), a crucial deacetylase, is implicated in various diseases' pathophysiology. Curcumin, a natural polyphenol, has been shown to modulate SIRT1 activity, offering therapeutic benefits. This study explores the impact of HS on hepatic SIRT1 expression and the protective mechanisms of curcumin against HS-induced hepatic injury. Male C57BL/6 mice are divided into control and curcumin pretreatment groups, subjected to HS induction, and assessed for liver injury biomarkers, oxidative stress, and inflammatory cytokines. Results indicate that HS downregulates SIRT1, leading to liver damage and systemic inflammation. Curcumin pretreatment dose-responsively attenuates these effects, with the highest dose providing optimal protection, potentially through SIRT1 restoration. The findings suggest that curcumin's hepatoprotective role in HS may be mediated by upregulating SIRT1, highlighting its therapeutic potential in heatstroke-related liver damage.

Exploring the effects of hypoxia and reoxygenation time on hepatocyte apoptosis and inflammation

Hepatic Ischemia-Reperfusion Injury (HIRI) is an unavoidable pathological process during liver surgeries such as liver transplantation and hepatic resection, which involves a complex set of molecular and cellular mechanisms. The mechanisms of HIRI may involve a variety of biological processes in which inflammation and apoptosis play a central role. Therefore, it is crucial to deeply investigate the effects of different hypoxia and reoxygenation times on the construction of an in vitro model of hepatic ischemia-reperfusion injury. The human normal liver cell line HL-7702 IRI model was constructed by hypoxia chamber, and the inflammation and apoptosis focal levels of cells were detected by enzyme-linked immunosorbent assay, western blot and quantitative reverse transcription polymerase chain reaction. When 12-hour reoxygenation time was fixed, the inflammation and apoptosis indexes of HIRI model increased with the prolongation of hypoxia time (6, 12 and 24 hours). These indices reached highest level in the model group of 24-hour fixed hypoxia and 12-hour reoxygenation. Inflammation and apoptosis indices were significantly higher in the model group of 24-hours fixed hypoxia and 12-hours reoxygenation than in the group of 6 and 24 hours of reoxygenation. Taken together, the findings from this research demonstrated that during hypoxia phase, cells exhibited a clear time-dependent response of inflammation and cell death; on the contrary, during the reoxygenation phase, the cellular damage was not monotonically incremental, but showed an inverted U-shaped dynamic pattern. The present study reveals in depth the dynamic changes of cellular responses under hypoxia and reoxygenation conditions, providing us with an important theoretical basis to guide the selection and optimization of in vitro experimental models.

Inhibition of PCSK9 Protects against Cerebral Ischemia‒Reperfusion Injury via Attenuating Microcirculatory Dysfunction

Proprotein convertase substilin/kexin type 9 (PCSK9), a pivotal protein regulating lipid metabolism, has been implicated in promoting microthrombotic formation and inflammatory cascades, thereby contributing to cardiovascular ischemia/reperfusion (I/R) injury. However, its involvement in cerebral I/R injury and its potential role in microcirculation protection remain unexplored. In this investigation, we utilized a middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model to simulate ischemic stroke. Different concentrations of evolocumab (1, 5, 10 mg/kg, i.v.), a PCSK9 inhibitor, were administered to assess its impact. Immunofluorescence staining was employed to analyze changes in the expression of occludin, claudin-5, thrombocyte, ICAM-1, VCAM-1, and CD45, providing insights into blood-brain barrier integrity, platelet adhesion, and immune cell infiltration. Moreover, the Morris water maze and elevated plus maze were utilized to evaluate neurological and behavioral functions in MCAO/R mice, shedding light on the effects of PCSK9 inhibition. Our findings revealed a surge in plasma PCSK9 levels post-MCAO/R, peaking at 24 h post-reperfusion. Evolocumab (10 mg/kg) treatment significantly mitigated brain infarction and neurological deficits, evidenced by enhanced locomotor function and reduced post-stroke anxiety. However, it did not ameliorate cognitive impairment following MCAO/R. Additionally, evolocumab administration led to diminished leakage of evans blue solution and upregulated expression of occludin and claudin-5. Thrombocyte, ICAM-1, VCAM-1, and CD45 levels were notably reduced in the penumbral area post-evolocumab treatment. These protective effects are speculated to be mediated through the inhibition of the ERK/NF-κB pathway. The PCSK9 inhibitor evolocumab holds promise as a therapeutic agent during the acute phase of stroke, exerting its beneficial effects by modulating the ERK/NF-κB signaling pathway.

The PINK1/Parkin signaling pathway-mediated mitophagy: a forgotten protagonist in myocardial ischemia/reperfusion injury

Myocardial ischemia causes extensive damage, further exacerbated by reperfusion, a phenomenon called myocardial ischemia/reperfusion injury (MIRI). Nowadays, the pathological mechanisms of MIRI have received extensive attention. Oxidative stress, multiple programmed cell deaths, inflammation and others are all essential pathological mechanisms contributing to MIRI. Mitochondria are the energy supply centers of cells. Numerous studies have found that abnormal mitochondrial function is an essential "culprit" of MIRI, and mitophagy mediated by the phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1)/Parkin signaling pathway is an integral part of maintaining mitochondrial function. Therefore, exploring the association between the PINK1/Parkin signaling pathway-mediated mitophagy and MIRI is crucial. This review will mainly summarize the crucial role of the PINK1/Parkin signaling pathway-mediated mitophagy in MIR-induced several pathological mechanisms and various potential interventions that affect the PINK1/Parkin signaling pathway-mediated mitophagy, thus ameliorating MIRI.

Exosomes-mediated delivery of miR-486-3p alleviates neuroinflammation via SIRT2-mediated inhibition of mitophagy after subarachnoid hemorrhage

BACKGROUND

Neuroinflammation participates in the pathogenesis of subarachnoid haemorrhage (SAH); however, no effective treatments exist. MicroRNAs regulate several aspects of neuronal dysfunction. In a previous study, we found that exosomal miR-486-3p is involved in the pathophysiology of SAH. Targeted delivery of miR-486-3p without blood-brain barrier (BBB) restriction to alleviate SAH is a promising neuroinflammation approach.

METHODS

In this study, we modified exosomes (Exo) to form an RVG-miR-486-3p-Exo (Exo/miR) to achieve targeted delivery of miR-486-3p to the brain. Neurological scores, brain water content, BBB damage, flow cytometry and FJC staining were used to determine the effect of miR-486-3p on SAH. Western blot analysis, ELISA and RT-qPCR were used to measure relevant protein and mRNA levels. Immunofluorescence staining and laser confocal detection were used to measure the expression of mitochondria, lysosomes and autophagosomes, and transmission electron microscopy was used to observe the level of mitophagy in the brain tissue of mice after SAH.

RESULTS

Tail vein injection of Exo/miR improved targeting of miR-486-3p to the brains of SAH mice. The injection reduced levels of neuroinflammation-related factors by changing the phenotype switching of microglia, inhibiting the expression of sirtuin 2 (SIRT2) and enhancing mitophagy. miR-486-3p treatment alleviated neurobehavioral disorders, brain oedema, BBB damage and neurodegeneration. Further research found that the mechanism was achieved by regulating the acetylation level of peroxisome proliferator-activated receptor γ coactivator l alpha (PGC-1α) after SIRT2 enters the nucleus.

CONCLUSION

Exo/miR treatment attenuates neuroinflammation after SAH by inhibiting SIRT2 expression and stimulating mitophagy, suggesting potential clinical applications.

A single-chain antibody construct with specificity of a natural IgM antibody reduces hepatic ischemia reperfusion injury in mice

Natural immunoglobulin M (IgM) antibodies have been shown to recognize post-ischemic neoepitopes following reperfusion of tissues and to activate complement. Specifically, IgM antibodies and complement have been shown to drive hepatic ischemia reperfusion injury (IRI). Herein, we investigate the therapeutic effect of C2 scFv (single-chain antibody construct with specificity of a natural IgM antibody) on hepatic IRI in C57BL/6 mice. Compared with PBS-treated mice, C2 scFv-treated mice displayed almost no necrotic areas, significant reduction in serum ALT, AST and LDH levels, and significantly reduced in the number of TUNEL positive cells. Moreover, C2 scFv-treated mice exhibited a notable reduction in inflammatory cells after hepatic IRI than PBS-treated mice. The serum IL-6, IL-1β, TNF-α and MPC-1 levels were also severely suppressed by C2 scFv. Interestingly, C2 scFv reconstituted hepatic inflammation and IRI in Rag1-/- mice. We found that C2 scFv promoted hepatic cell death and increased inflammatory cytokines and infiltration of inflammatory cells after hepatic IRI in Rag1-/- mice. In addition, IgM and complement 3d (C3d) were deposited in WT mice and in Rag1-/- mice reconstituted with C2 scFv, indicating that C2 scFv can affect IgM binding and complement activation and reconstitute hepatic IRI. C3d expression was significantly lower in C57BL/6 mice treated with C2 scFv compared to PBS, indicating that excessive exogenous C2 scFv inhibited complement activation. These data suggest that C2 scFv alleviates hepatic IRI by blocking complement activation, and treatment with C2 scFv may be a promising therapy for hepatic IRI.