Tongxinluo exerts protective effects via anti-apoptotic and pro-autophagic mechanisms by activating AMPK pathway in infarcted rat hearts.

Background: Proteomics is a potential tool to study the large-scale expression, function and interaction of the complement of proteins in an organism. In this study, we used the TMT-labeled proteomics to detect the various cytokines in an in vitro model of cardiac microvascular endothelial cells (CMECs) ischemia/reperfusion injury with Tongxinluo(TXL) treatment. Our aims are to investigate whether TXL could modulate the secretion function of CMECs, and to synthetically analysis the underlying mechanism of the regulation. Methods: Human CMECs were exposed to different concentrations of TXL, and incubated to scavenge free oxygen for 2 h of hypoxia and were moved to normal conditions for 2 h of reoxygenation. Cell apoptosis was assessed by flow cytometric analysis. CMECs were divided into three groups for TMT-labeled proteomics analysis: CMECs in normal condition (Group N), CMECs in hypoxia and serum deprivation condition (Group HR), CMECs treatment with TXL in hypoxia and serum condition(Group HR+TXL) . We utilized bioinformatics analysis to identify differential proteins. Results: TXL concentration-dependently decreased apoptosis of CMECs. The optimal concentration of TXL to have the maximum protection for CMECs was 800 μg/mL. Both hypoxia/reoxygenation and TXL treatment significantly changed the cytokines level of CMECs. 32 differential proteins between group N and group HR were detected. TXL treatment up-regulated 6 cytokines and down-regulated 6 cytokines in ischemia/reperfusion injury. These proteins mainly had vital functions such as cell proliferation, stress response, regulation of multicelluler organismal metabolic process. We evaluated several proteins played important roles in ischemia/reperfusion injury including Human Heme Oxygenase 1 (HMOX1), angiopoietin 2 (ANGPT2), sequestosome 1 (SQSTM1), and connective tissue growth factor (CTGF). Conclusion: The study presented differential proteins responsible for ischemia/reperfusion injury through TMT-labeled proteomic analysis. We assessed some vital proteins including their characters and roles. These findings may provide new mechanisms of TXL treatment in acute myocardial diseases.

Vasoconstriction and hypersensitivity to the vasoconstrictive action of serotonin occurs in the early stage of atherosclerosis. Vascular neural nitric oxide synthase (nNOS) plays an important role in the regulation of vascular tone and is vasoprotective against atherosclerosis. In this study, we intended to investigate the possible role of nNOS in mediating the effect of Chinese medicine Tongxinluo (TXL) to attenuate vasoconstriction induced by the chronic injury in the collared carotid artery. Twenty-four male Wistar Kyoto rats were assigned to 2 treatments (n = 12): vehicle and TXL (400 mg·kg·d). After 2 weeks of treatment, adventitia injury was induced by placing a silicone collar around the left carotid artery for 2 weeks. Blood flow and vascular reactivity to serotonin were determined, and carotid arteries were harvested for morphometry, RT-PCR, and Western blotting analysis. Expression of nNOS and phosphorylated ERK1/2 was also analyzed in primary cultured vascular smooth muscle cells after TXL and/or ERK kinase inhibitor treatment. Adventitia injury induced by the placement of a silicone collar around the carotid artery for 2 weeks led to chronic vasoconstriction and vascular hypersensitivity to serotonin, which was attenuated by TXL treatment. TXL improved the carotid blood flow and normalized the vascular hypersensitivity to serotonin in collared carotid arteries. The expression of nNOS and phosphorylated ERK1/2 was increased by TXL treatment in both collared carotid artery and vascular smooth muscle cells indicating a possible contribution of ERK1/2 and nNOS signaling to the beneficial effects of TXL. Moreover, we showed that the effect of TXL to increase nNOS expression was mediated by the phosphorylated ERK1/2 since the effect could be abolished by the ERK kinase inhibitor PD98059. TXL increases nNOS expression in the collared carotid artery through activation of ERK1/2 signaling, which may have contributed to the attenuation of vasoconstriction induced by the collar-induced adventitia injury.

Background. The exacerbated consumption of glucose in tumor cells is a widely reported event, this metabolic modification is associated with the activation of anabolic pathways that contribute to uncontrolled proliferation. Lung cancer tumor cells often present glycolytic metabolism phenotypes with large lactate secretions, due to the fact that they usually develop in hypoxic microenvironments and with low nutrient concentrations. The inhibition of signaling pathways triggered by growth factors receptors, as well as, the activation of AMP-activated protein kinase (AMPK) pathway has the ability to restore a catabolic phenotype in tumor cells thus controlling proliferation and evasion of the immune system. It has been observed that treatment with EGFR tyrosine kinase inhibitors (TKIs) reduces the glycolytic phenotype in certain lung cancer cell lines, on the other hand Metformin has shown a reestablishment of oxidative characteristics in several cell lines of solid tumors. Hypothesis. The Afatinib-Metformin treatment has the ability to modulate the AMPK and EGFR signaling pathways with a decreasing in the glycolytic phenotype in cell lines with different mutational EGFR status. Objective. To determine the effect of combination Afatinib-Metformin on the activation of the EGFR and AMPK pathways and their relationship with glucose consumption in cell lines with different EGFR mutational status. Methods. Three different doses of Afatinib and one dose of Metformin were used in lung adenocarcinoma cell lines A549, H1975 and HCC827 (ATCC). Activation of AMPK and EGFR signaling pathways was assessed by Western Blot and Flow Cytometry. Results. All cell lines showed decreased expression of EGFR as well as its active form. Interestingly LKB1 inhibition was shown with all treatments in H1975 and HCC827 cell lines that express it basally. The evaluation of downstream protein activation of the EGFR pathway showed inhibition of the S6K effector when treatment with Afatinib was administered. As regards the evaluation of glucose uptake all cell lines showed a reduction of up to 50% compared to the control when the combined treatment was administered. Conclusions. The combination treatment Afatinib-Metformin shows regulation of EGFR signaling pathway and inhibition of LKB1 that is one of the activators of AMPK. A down regulation of the incorporation of glucose was shown and this could be associated with a reestablishment of the oxidative character of the metabolic phenotype. Note: This abstract was not presented at the meeting. Citation Format: Pedro Barrios-Bernal, Mario Orozco-Morales, Giovanny Soca-Chafre, Oscar Arrieta, Norma Hernández-Pedro. Cellullar modifications of glucose uptake through the modulation of AMPK & EGFR signaling axes in lung cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1849.

Autophagy is promoted as a response to such environmental stress conditions as ATP depletion and excessive accumulation of reactive oxygen species (ROS). Multiple signalling pathways, including AMP-activated protein kinase (AMPK), are indicated to promote autophagy in ischaemic/hypoxic (I/R) heart. However, it's far more to clarify the orchestrated cross-talk between AMPK and other signalling pathways in the autophagy. In the present study, we investigated the autophagy induction by hypoxia in Rat H9C2 cardiomyocytes with LC3-EGFP reporter, EM and Western blot analysis. Then, we examined the promotion of forkhead box O (FOXO) 3, one member of FOXO transcriptional protein family, by hypoxia in Rat H9C2 cells and determined the mediation of FOXO 3 in the hypoxia-induced autophagy in H9C2 cells. In addition, we investigated the role of AMPK signalling in the FOXO3-mediated, hypoxia-induced autophagy in H9C2 cells. It was demonstrated that hypoxia induced significant autophagy in H9C2 cells, via promoting autophagic vesicles, inducing the conversion of LC3-I to LC3-II and up-regulating autophagy-related (ATG) markers. Moreover, FOXO3 was up-regulated by the hypoxia in H9C2 cells; and the knockdown of FOXO3 significantly reduced the hypoxia-induced autophagy. In addition, AMPK signalling was significantly promoted by hypoxia in H9C2 cells, and the chemical manipulation of AMPK exerted significant influence on the hypoxia-induced autophagy and on the FOXO3 level. In conclusion, FOXO3 regulated the hypoxia-induced autophagy in cardiomyocytes, and AMPK mediated the FOXO3 promotion during the autophagy induction by hypoxia, implying the key regulatory role of FOXO3 and AMPK signalling in the hypoxia-induced autophagy in cardiomyocytes.

Glucose deprivation is a major metabolic stress that requires coordinated adaptive responses to maintain cellular homeostasis and survival, yet the role of tripartite motif-containing 24 (TRIM24) in this process remains unclear. To address this question, we generated CRISPR-Cas9-mediated TRIM24-knockout MCF-7 and HEK293 cell lines, performed targeted metabolomic profiling and aspartate assays, used 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), aminooxyacetic acid (AOA), aspartate supplementation, and glutamic-oxaloacetic transaminase 2 (GOT2) knockdown to probe AMPK signaling and aspartate metabolism, and examined starvation responses in constitutive Trim24 knockout mice on a C57BL/6 background. Loss of TRIM24 sensitized cells to glucose deprivation. Re-expression of TRIM24 partially restored cell viability under glucose deprivation in both MCF-7 and HEK293 cells. Under glucose-free conditions, TRIM24 deficiency was associated with impaired AMP-activated protein kinase (AMPK) pathway activation, increased intracellular aspartate accumulation, and altered ATP/AMP levels. Pharmacological reactivation of AMPK by AICAR improved the survival of TRIM24-deficient cells under glucose deprivation. Reducing intracellular aspartate by AOA treatment or GOT2 knockdown restored AMPK pathway activation and improved adaptation to glucose deprivation, whereas exogenous aspartate suppressed AMPK signaling and increased ATP/AMP levels. In vivo, starvation of Trim24-deficient mice was associated with reduced AMPK pathway activation and increased aspartate levels. Together, these findings support a model in which TRIM24 contributes to adaptation to glucose deprivation and in which abnormal aspartate accumulation contributes to impaired AMPK pathway activation in TRIM24-deficient cells.

Alzheimer disease (AD) is usually accompanied by two prominent pathological features, cerebral accumulation of amyloid-β (Aβ) plaques and presence of MAPT/tau neurofibrillary tangles. Dysregulated clearance of Aβ largely contributes to its accumulation and plaque formation in the brain. Macroautophagy/autophagy is a lysosomal degradative process, which plays an important role in the clearance of Aβ. Failure of autophagic clearance of Aβ is currently acknowledged as a contributing factor to increased accumulation of Aβ in AD brains. In this study, we have identified crocetin, a pharmacologically active constituent from the flower stigmas of Crocus sativus, as a potential inducer of autophagy in AD. In the cellular model, crocetin induced autophagy in N9 microglial and primary neuron cells through STK11/LKB1 (serine/threonine kinase 11)-mediated AMP-activated protein kinase (AMPK) pathway activation. Autophagy induction by crocetin significantly increased Aβ clearance in N9 cells. Moreover, crocetin crossed the blood-brain barrier and induced autophagy in the brains’ hippocampi of wild-type male C57BL/6 mice. Further studies in transgenic male 5XFAD mice, as a model of AD, revealed that one-month treatment with crocetin significantly reduced Aβ levels and neuroinflammation in the mice brains and improved memory function by inducing autophagy that was mediated by AMPK pathway activation. Our findings support further development of crocetin as a pharmacological inducer of autophagy to prevent, slow down progression, and/or treat AD. Abbreviations: Aβ: amyloid-β; ABCB1/P-gp/P-glycoprotein: ATP-binding cassette, subfamily B (MDR/TAP), member 1; AD: Alzheimer disease; AMPK/PRKAA: AMP-activated protein kinase; APP: amyloid beta (A4) precursor protein; ATG: autophagy related; BBB: blood-brain barrier; BECN1: beclin 1, autophagy related; CAMKK2/CaMKKβ: calcium/calmodulin-dependent protein kinase kinase 2, beta; CSE: Crocus sativus extract; CTSB: cathepsin B; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; GFAP: glial fibrillary acidic protein; GSK3B/GSK3β: glycogen synthase kinase 3 beta; Kp: brain partition coefficient; LRP1: low density lipoprotein receptor-related protein 1; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAP2: microtubule-associated protein 2; MAPK/ERK: mitogen-activated protein kinase; MAPT/tau: microtubule-associated protein tau; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MTOR: mechanistic target of rapamycin kinase; MWM: Morris water maze; NFKB/NF-κB: nuclear factor of kappa light polypeptide gene enhancer in B cells; NMDA: N-methyl-d-aspartic acid; RPTOR: regulatory associated protein of MTOR; RPS6KB1/p70S6K: ribosomal protein S6 kinase 1; SQSTM1: sequestosome 1; SRB: sulforhodamine B; STK11/LKB1: serine/threonine kinase 11; TFEB: transcription factor EB; TSC2: TSC complex subunit 2; ULK1: unc-51 like kinase 1.

Mitogen-activated protein kinase (MAPK) pathways are involved in the regulation of cellular responses, including cell proliferation, differentiation, cell growth, and apoptosis. Because these responses are tightly related to cellular energy level, AMP-activated protein kinase (AMPK), which plays an essential role in energy homeostasis, has emerged as another key regulator. In the present study, we demonstrate a novel signal network between AMPK and MAPK in HCT116 human colon carcinoma. Glucose deprivation activated AMPK and three MAPK subfamilies, extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK), and p38 MAPK. Under these conditions, inhibition of endogenous AMPK by expressing a dominant-negative form significantly potentiated ERK activation, indicating that glucose deprivation-induced AMPK is specifically antagonizing ERK activity in HCT116 cells. Moreover, we provide novel evidence that AMPK activity is critical for p53-dependent expression of dual-specificity phosphatase (DUSP) 1 & 2, which are negative regulators of ERK. Notably, ERK exhibits pro-apoptotic effects in HCT116 cells under glucose deprivation. Collectively, our data suggest that AMPK protects HCT116 cancer cells from glucose deprivation, in part, via inducing DUSPs, which suppresses pro-apoptotic ERK, further implying that a signal network between AMPK and ERK is a critical regulatory point in coupling the energy status of the cell to the regulation of cell survival.

This study aimed to determine whether hesperetin (HPT) has chondroprotective effects against the TNF-α-induced inflammatory response of chondrocytes and related mechanisms and clarify the impact of HPT on osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT). Under tumor necrosis factor-α (TNF-α) stimulation, rat chondrocytes were treated with or without HPT. The CCK-8 assay was used to detect viability and cytotoxicity. RT-qPCR and Western blot were used to examine the expression of aggrecan, collagen type II, and inflammatory and proliferative genes/proteins in chondrocytes. Flow cytometry was used to check the cell cycle to determine whether HPT protects chondrocytes against the inhibitory effect of TNF-α on chondrocyte proliferation. In addition, RNA sequencing was used to discover possible molecular targets and pathways and then validate these pathways with specific protein phosphorylation levels. Finally, immunofluorescence staining was used to examine the phosphorylation of the AMP-activated protein kinase (AMPK) pathway. The results showed that HPT restored the upregulation of interleukin 1β (IL-1β), PTGS2, and MMP-13 induced by TNF-α. In addition, HPT reversed the degradation of the extracellular matrix of chondrocytes induced by TNF-α. HPT also reversed the inhibitory effect of TNF-α on chondrocyte proliferation. RNA sequencing revealed 549 differentially expressed genes (DEGs), of which 105 were upregulated and 444 were downregulated, suggesting the potential importance of the AMPK pathway. Progressive analysis showed that HPT mediated the repair of TNF-α-induced chondrocyte damage through the AMPK signaling pathway. Thus, local treatment of HPT can improve OA induced by ACLT. These findings indicated that HPT has significant protective and anti-inflammatory effects on chondrocytes through the AMPK signaling pathway, effectively preventing cartilage degradation. Given the various beneficial effects of HPT, it can be used as a potential natural drug to treat OA.

Introduction: Trimetazidine (TMZ) is an anti-anginal drug that has been widely used in Europe and Asia. The TMZ can optimize energy metabolism via inhibition of long-chain 3-ketoacyl CoA thiolase (3-KAT) in the heart, with subsequent decrease in fatty acid oxidation and stimulation of glucose oxidation. However, the mechanism by which TMZ aids in cardioprotection against ischemic injury has not been characterized. Hypothesis: AMP-activated protein kinase (AMPK) is an energy sensor that control ATP supply from substrate metabolism and protect heart from energy stress. TMZ changes the cardiac AMP/ATP ratio via modulating fatty acid oxidation, thereby it may trigger AMPK signaling cascade that contribute to protection heart from ischemia/reperfusion (I/R) injury. Methods: The mouse in vivo regional ischemia and reperfusion by the ligation of the left anterior descending coronary artery (LAD) were used for determination of myocardial infarction. The infarct size was compared between C57BL/6J WT mice and AMPK kinase dead (KD) transgenic mice with or without TMZ treatment. The ex vivo working heart perfusion system was used to monitor the effect of TMZ on glucose oxidation and fatty acid oxidation in the heart. Results: TMZ treatment significantly stimulates cardiac AMPK and extracellular signal-regulated kinase (ERK) signaling pathways (p<0.05 vs. vehicle group). The administration of TMZ reduces myocardial infarction size in WT C57BL/6J hearts, the reduction of myocardial infarction size by TMZ in AMPK KD hearts was significantly impaired versus WT hearts (p<0.05). Intriguingly, the administration of ERK inhibitor, PD 98059, to AMPK KD mice abolished the cardioprotection of TMZ against I/R injury. The ex vivo working heart perfusion data demonstrated that TMZ treatment significantly activates AMPK signaling and modulating the substrate metabolism by shifting fatty acid oxidation to glucose oxidation during reperfusion, leading to reduction of oxidative stress in the I/R hearts. Conclusions: Both AMPK and ERK signaling pathways mediate the cardioprotection of TMZ against ischemic injury. The metabolic benefits of TMZ for angina patients could be due to the activation of energy sensor AMPK in the heart by TMZ administration.

Skeletal muscle dysfunction, a striking systemic comorbidity of chronic obstructive pulmonary disease (COPD), is associated with declines in activities of daily living, reductions in health status and prognosis, and increases in mortality. Bufei Jianpi formula (BJF), a traditional Chinese herbal formulation, has been shown to improve skeletal muscle tension and tolerance via inhibition of cellular apoptosis in COPD rat models. This study aimed to investigate the mechanisms by which BJF regulates the adenosine monophosphate-activated protein kinase (AMPK) pathway to improve mitochondrial function and to suppress mitophagy in skeletal muscle cells. Our study showed that BJF repaired lung function and ameliorated pathological impairment in rat lung and skeletal muscle tissues. BJF also improved mitochondrial function and reduced mitophagy via the AMPK signaling pathway in rat skeletal muscle tissue. In vitro, BJF significantly improved cigarette smoke extract-induced mitochondrial functional impairment in L6 skeletal muscle cells through effects on mitochondrial membrane potential, mitochondrial permeability transition pores, adenosine triphosphate production, and mitochondrial respiration. In addition, BJF led to upregulated expression of mitochondrial biogenesis markers, including AMPK-α, PGC-1α, and TFAM and downregulation of mitophagy markers, including LC3B, ULK1, PINK1, and Parkin, with increased expression of downstream markers of the AMPK pathway, including mTOR, PPARγ, and SIRT1. In conclusion, BJF significantly improved skeletal muscle and mitochondrial function in COPD rats and L6 cells by promoting mitochondrial biogenesis and suppressing mitophagy via the AMPK pathway. This study suggests that BJF may have therapeutic potential for prophylaxis and treatment of skeletal muscle dysfunction in patients with COPD.

Etoposide-induced protein 2.4 ameliorates high glucose-induced epithelial-mesenchymal transition by activating adenosine monophosphate-activated protein kinase pathway in renal tubular cells.

Under metabolic stress conditions such as hypoxia and glucose deprivation, an increase in the AMP:ATP ratio activates the AMP-activated protein kinase (AMPK) pathway, resulting in the modulation of cellular metabolism. Metformin, which is widely prescribed for type 2 diabetes mellitus (T2DM) patients, regulates blood sugar by inhibiting hepatic gluconeogenesis and promoting insulin sensitivity to facilitate glucose uptake by cells. At the molecular level, the most well-known mechanism of metformin-mediated cytoprotection is AMPK pathway activation, which modulates metabolism and protects cells from degradation or pathogenic changes, such as those related to aging and diabetic retinopathy (DR). Recently, it has been revealed that metformin acts via AMPK- and non-AMPK-mediated pathways to exert effects beyond those related to diabetes treatment that might prevent aging and ameliorate DR. This review focuses on new insights into the anticancer effects of metformin and its potential modulation of several novel types of nonapoptotic cell death, including ferroptosis, pyroptosis, and necroptosis. In addition, the antimetastatic and immunosuppressive effects of metformin and its hypothesized mechanism are also discussed, highlighting promising cancer prevention strategies for the future.

The response of AMP-activated protein kinase (AMPK) to oxidative stress has been recently reported but the downstream signals of this response are largely unknown. Meanwhile, the upstream events for the activation of nuclear factor erythroid-2-related factor-2 (Nrf2), a critical transcriptional activator for antioxidative responses, remain unclear. In the present study, we investigated the relationship between AMPK and Nrf2 signal pathways in lipopolysaccharide (LPS)-triggered inflammatory system, in which berberine (BBR), a known AMPK activator, was used for inflammation suppression. In inflammatory macrophages, BBR attenuated LPS-induced expression of inflammatory genes (inducible nitric oxide synthase [iNOS], cyclooxygenase-2 [COX2], interleukin [IL]-6), and the generation of nitric oxide and reactive oxygen species, but increased the transcription of Nrf2-targeted antioxidative genes (NADPH quinone oxidoreductase-1 [NQO-1], heme oxygenase-1 [HO-1]), as well as the nuclear localization and phosphorylation of Nrf2 protein. Importantly, we found BBR-induced activation of Nrf2 is AMPK-dependent, as either pharmacologically or genetically inactivating AMPK blocked the activation of Nrf2. Consistent with in vitro experiments, BBR down-regulated the expression of proinflammatory genes but upregulated those of Nrf2-targeted genes in lungs of LPS-injected mice, and these effects were attenuated in Nrf2-deficient mice. Moreover, the effect of BBR on survival time extension and plasma redox regulation in endotoxin-shocked mice was largely weakened when Nrf2-depleted. Our results demonstrate convergence between AMPK and Nrf2 pathways and this intersection is essential for anti-inflammatory effect of BBR in LPS-stimulated macrophages and endotoxin-shocked mice. Uncovering this intersection is significant for understanding the relationship between energy homeostasis and antioxidative responses and may be beneficial for developing new therapeutic strategies against inflammatory diseases. Antioxid. Redox Signal. 20, 574-588.

A previous study demonstrated the renal-protective effect of thalidomide (Thd) in diabetic nephropathy rats through the activation of the adenosine monophosphate-activated protein kinase (AMPK) and inhibition of the nuclear factor κB (NF-κB)/monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog signaling pathways. The association between AMPK inactivation and high glucose (HG)-induced meningeal cell (MC) proliferation and extracellular matrix (ECM) accumulation via NF-κB and TGF-β1 signaling remains unknown. The aim of the current study was to demonstrate the effects of Thd on cell proliferation and ECM expression in HG-cultured MCs and the underlying mechanisms. HG-cultured human MCs were treated with Thd. Cell proliferation was measured by MTT assay and quantification of cell proliferation was based on the measurement of bromodeoxyuridine incorporation. The differences in TGF-β1, fibronectin and MCP-1 protein expression levels were detected via ELISA and western blot analysis. The AMPK signaling pathway was also examined by western blot analysis in MCs. Compound C, an AMPK inhibitor and AICAR (5-aminoimidazole-4-carboxamide 1β-D-ribofuranoside), an AMPK agonist, were used to analyze the functional role of AMPK in MCs. Cell proliferation was significantly decreased in HG-cultured MCs following treatment with high concentrations of Thd (100 and 200 µg/ml) for 24 h compared with the HG-cultured MC group. Thd suppressed the inflammatory processes in HG-induced MCs. These effects were partially mediated through the activation of AMPK and inhibition of the NF-κB/MCP-1 signaling pathways. Taken together, these results suggest that Thd may have therapeutic potential in diabetic renal injury via the AMPK signaling pathway.

Resveratrol ameliorates lipid accumulation and inflammation in human SZ95 sebocytes via the AMPK signaling pathways in vitro