Smooth-Muscle-Cell-Specific Deletion of CD38 Protects Mice from AngII-Induced Abdominal Aortic Aneurysm through Inhibiting Vascular Remodeling.

Abdominal aortic aneurysm (AAA) is a serious vascular disease which is associated with vascular remodeling. CD38 is a main NAD+-consuming enzyme in mammals, and our previous results showed that CD38 plays the important roles in many cardiovascular diseases. However, the role of CD38 in AAA has not been explored. Here, we report that smooth-muscle-cell-specific deletion of CD38 (CD38SKO) significantly reduced the morbidity of AngII-induced AAA in CD38SKOApoe-/- mice, which was accompanied with a increases in the aortic diameter, medial thickness, collagen deposition, and elastin degradation of aortas. In addition, CD38SKO significantly suppressed the AngII-induced decreases in α-SMA, SM22α, and MYH11 expression; the increase in Vimentin expression in VSMCs; and the increase in VCAM-1 expression in smooth muscle cells and macrophage infiltration. Furthermore, we demonstrated that the role of CD38SKO in attenuating AAA was associated with the activation of sirtuin signaling pathways. Therefore, we concluded that CD38 plays a pivotal role in AngII-induced AAA through promoting vascular remodeling, suggesting that CD38 may serve as a potential therapeutic target for the prevention of AAA.

A review of the signaling pathways of aerobic and anaerobic exercise on atherosclerosis.

Atherosclerosis (AS), a chronic inflammatory vascular disease with lipid metabolism abnormalities, is one of the major pathological bases of coronary heart disease. As people's lifestyles and diets change, the incidence of AS increases yearly. Physical activity and exercise training have recently been identified as effective strategies for lowering cardiovascular disease (CVD) risk. However, the best exercise mode to ameliorate the risk factors related to AS is not clear. The effect of exercise on AS is affected by the type of exercise, intensity, and duration. In particular, aerobic and anaerobic exercise are the two most widely discussed types of exercise. During exercise, the cardiovascular system undergoes physiological changes via various signaling pathways. The review aims to summarize signaling pathways related to AS in two different exercise types and provide new ideas for the prevention and treatment of AS in clinical practice.

Transcription factor 21 accelerates vascular calcification in mice by activating the IL-6/STAT3 signaling pathway and the interplay between VSMCs and ECs.

Vascular calcification is caused by the deposition of calcium salts in the intimal or tunica media layer of the aorta, which increases the risk of cardiovascular events and all-cause mortality. However, the mechanisms underlying vascular calcification are not fully clarified. Recently it has been shown that transcription factor 21 (TCF21) is highly expressed in human and mouse atherosclerotic plaques. In this study we investigated the role of TCF21 in vascular calcification and the underlying mechanisms. In carotid artery atherosclerotic plaques collected from 6 patients, we found that TCF21 expression was upregulated in calcific areas. We further demonstrated TCF21 expression was increased in an in vitro vascular smooth muscle cell (VSMC) osteogenesis model. TCF21 overexpression promoted osteogenic differentiation of VSMC, whereas TCF21 knockdown in VSMC attenuated the calcification. Similar results were observed in ex vivo mouse thoracic aorta rings. Previous reports showed that TCF21 bound to myocardin (MYOCD) to inhibit the transcriptional activity of serum response factor (SRF)-MYOCD complex. We found that SRF overexpression significantly attenuated TCF21-induced VSMC and aortic ring calcification. Overexpression of SRF, but not MYOCD, reversed TCF21-inhibited expression of contractile genes SMA and SM22. More importantly, under high inorganic phosphate (3 mM) condition, SRF overexpression reduced TCF21-induced expression of calcification-related genes (BMP2 and RUNX2) as well as vascular calcification. Moreover, TCF21 overexpression enhanced IL-6 expression and downstream STAT3 activation to facilitate vascular calcification. Both LPS and STAT3 could induce TCF21 expression, suggesting that the inflammation and TCF21 might form a positive feedback loop to amplify the activation of IL-6/STAT3 signaling pathway. On the other hand, TCF21 induced production of inflammatory cytokines IL-1ß and IL-6 in endothelial cells (ECs) to promote VSMC osteogenesis. In EC-specific TCF21 knockout (TCF21ECKO) mice, VD3 and nicotine-induced vascular calcification was significantly reduced. Our results suggest that TCF21 aggravates vascular calcification by activating IL-6/STAT3 signaling and interplay between VSMC and EC, which provides new insights into the pathogenesis of vascular calcification. TCF21 enhances vascular calcification by activating the IL-6-STAT3 signaling pathway. TCF21 inhibition may be a new potential therapeutic strategy for the prevention and treatment of vascular calcification.

CD38 deficiency promotes skeletal muscle and brown adipose tissue energy expenditure through activating NAD+-Sirt1-PGC1α signaling pathway.

Obesity is a metabolic syndrome characterized by abnormal lipid deposition and energy imbalance. CD38 is a single-chain transmembrane glycoprotein widely expressed in a variety of cell types. The roles of skeletal muscle and brown fat in CD38 deficiency under HFD-induced obesity remain unknown. In this study, we established obesity model with HFD and examined the changes in metabolites with metabonomics. Our results showed that CD38 expression was increased in muscle and brown fat after HFD treatment. Moreover, the results of metabonomics showed that CD38 deficiency significantly altered the metabolites in energy metabolism, cofactor generation, and redox homeostasis. Furthermore, CD38 deficiency reduced the expressions of NADPH oxidase 2 and FASN in mRNA level. We found that the expressions of Sirt1, Sirt3, and PGC1α were upregulated in CD38-deficient muscle tissue. In brown fat, the Sirt1-3, cell death inducing DFFA-like effector A, ELOVL3, and Dio2 expressions were increased in CD38-deficient mice. Our results showed the uncoupling protein 1 expression was upregulated. And NAD+ supplementation increased the expression of Sirt1 and PGC1α after palmitic acid treatment. Taken together, our results demonstrated that the protection of CD38 deficiency on HFD-induced obesity was related to the inhibition of oxidative stress and increasing energy expenditure via activating NAD+/Sirtuins signaling pathways in muscle and brown fat.

Shikonin exerts antitumor activity by causing mitochondrial dysfunction in hepatocellular carcinoma through PKM2-AMPK-PGC1α signaling pathway.

Shikonin, a naphthoquinone derivative isolated from the root of Lithospermum erythrorhizon, exhibits broad-spectrum antitumor activity via different molecular mechanisms. In this study, we investigated the effect of shikonin on mitochondrial dysfunction in hepatocellular carcinoma (HCC). Our results showed that shikonin inhibited the proliferation, migration, and invasiveness of HCCLM3 cells, and promoted cell apoptosis in a dose-dependent manner. More importantly, shikonin affected mitochondrial function by disrupting mitochondrial membrane potential and oxidative stress (OS) status. Furthermore, shikonin decreased the oxygen consumption rate of HCCLM3 cells, as well as the levels of ATP and metabolites involved in the tricarboxylic acid cycle (TCA cycle). We also investigated the molecular mechanisms underlying the regulation of mitochondrial function by shikonin as an inhibitor of PKM2. Shikonin decreased the expression of PKM2 in the mitochondria and affected other metabolic pathways (AMPK and PGC1α pathways), which aggravated the oxidative stress and nutrient deficiency. Our results indicate a novel role of shikonin in triggering mitochondria dysfunction via the PKM2-AMPK-PGC1α signaling pathway and provide a promising therapeutic approach for the treatment of HCC.

CD38 Deficiency Promotes Inflammatory Response through Activating Sirt1/NF-κB-Mediated Inhibition of TLR2 Expression in Macrophages.

CD38 was first identified as a lymphocyte-specific antigen and then has been found to be widely expressed in a variety of cell types. The functions of CD38 are involved in numerous biological processes including immune responses. Here, we showed the downregulations of both TLR2 mRNA and protein in macrophages from CD38-/- mice and in CD38 knockdown RAW264.7 cells. Several NF-κB-binding motifs in the promoter region of the TLR2 gene were identified by the bioinformatics analysis and were confirmed by the luciferase activity assay with the different truncated TLR2 promoters. CD38 deficiency resulted in the reduction of NF-κB p65 and acetyl-NF-κB p65 (Ac-p65) levels as determined by Western blot. The expression of Sirt1 did not change, but an increased activity of Sirt1 was observed in CD38-deficient macrophages. Inhibition of the Sirt1/NF-κB signaling pathway resulted in downregulation of TLR2 expression in RAW264.7 cells. However, re-expression of CD38 in the knockdown clones reversed the effect on Sirt1/NF-κB/TLR2 signaling, which is NAD-dependent. Moreover, the inflammatory cytokines including G-CSF, IL-1alpha, IL-6, MCP-1, MIP-1alpha, and RANTES were increased in CD38 knockdown RAW264.7 cells. Taken together, our data demonstrated that CD38 deficiency enhances inflammatory response in macrophages, and the mechanism may be partly associated with increased Sirt1 activity, which promoted NF-κB deacetylation and then inhibited expression of the TLR2 gene. Obviously, our study may provide an insight into the molecular mechanisms in CD38-mediated inflammation.

Inhibition of Macrophage CD36 Expression and Cellular Oxidized Low Density Lipoprotein (oxLDL) Accumulation by Tamoxifen: A PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR)γ-DEPENDENT MECHANISM.

Macrophage CD36 binds and internalizes oxidized low density lipoprotein (oxLDL) to facilitate foam cell formation. CD36 expression is activated by peroxisome proliferator-activated receptor γ (PPARγ). Tamoxifen, an anti-breast cancer medicine, has demonstrated pleiotropic functions including cardioprotection with unfully elucidated mechanisms. In this study, we determined that treatment of ApoE-deficient mice with tamoxifen reduced atherosclerosis, which was associated with decreased CD36 and PPARγ expression in lesion areas. At the cellular level, we observed that tamoxifen inhibited CD36 protein expression in human THP-1 monocytes, THP-1/PMA macrophages, and human blood monocyte-derived macrophages. Associated with decreased CD36 protein expression, tamoxifen reduced cellular oxLDL accumulation in a CD36-dependent manner. At the transcriptional level, tamoxifen decreased CD36 mRNA expression, promoter activity, and the binding of the PPARγ response element in CD36 promoter to PPARγ protein. Tamoxifen blocked ligand-induced PPARγ nuclear translocation and CD36 expression, but it increased PPARγ phosphorylation, which was due to that tamoxifen-activated ERK1/2. Furthermore, deficiency of PPARγ expression in macrophages abolished the inhibitory effect of tamoxifen on CD36 expression or cellular oxLDL accumulation both in vitro and in vivo Taken together, our study demonstrates that tamoxifen inhibits CD36 expression and cellular oxLDL accumulation by inactivating the PPARγ signaling pathway, and the inhibition of macrophage CD36 expression can be attributed to the anti-atherogenic properties of tamoxifen.

Activation of PPARγ does not contribute to macrophage ABCA1 expression and ABCA1-mediated cholesterol efflux to apoAI.

Activation of macrophage ABCA1/G1 expression and cholesterol efflux is believed one of the mechanisms by which PPARγ inhibits atherosclerosis. PPARγ can also activate CD36 expression, a receptor for oxLDL, which may supply LXR ligands to activate LXR-ABCA1/G1 pathways. However, the controversial effects of PPARγ on ABCA1 expression have been reported. In this study, we used peritoneal macrophages isolated from wild type and CD36 deficient (CD36-/-) mice to clarify if PPARγ ligands can influence ABCA1 expression by CD36 function. We found that CD36 deficiency had no effect on cholesterol efflux and ABCA1/ABCG1 expression at basal levels. In both cell types, PPARγ ligands (15d-PGJ2, troglitazone and pioglitazone) reduced ABCA1 expression and ABCA1-mediated cholesterol efflux to apoAI, with most by troglitazone. LXR ligand-induced ABCA1 expression and cholesterol efflux was attenuated by PPARγ ligands. Associated with decreased ABCA1 protein levels, ABCA1 mRNA and promoter activity were reduced by PPARγ ligands. Furthermore, high expressing PPARγ reduced ABCA1 expression and LXR-activated ABCA1 promoter in a CD36-independent manner. In contrast, ABCG1 expression was induced by PPARγ ligands while inhibited by PPARγ inactivation. Taken together, our study suggests that enhancement of macrophage cholesterol metabolism by PPARγ is not contributed by activating ABCA1 expression and ABCA1-mediated cholesterol efflux to apoAI, which is not involved by CD36 expression either.

Evaluation of the Antioxidative, Antibacterial, and Anti-Inflammatory Effects of the Aloe Fermentation Supernatant Containing Lactobacillus plantarum HM218749.1.

Little work is done to develop Aloe vera (AV) using probiotics. To explore the potential benefits, the antioxidant effects and the antibacterial effects on foodborne pathogens of Aloe fermentation supernatant were evaluated in vitro. Our results indicated that the Aloe fermentation supernatant fermented by Lactobacillus plantarum HM218749.1 had very strong scavenging capacities of the DPPH (86%), O2 (•-) (85%), (•)OH (76%), and Fe(2+) chelation (82%) and reducing powers (242.5 mg/L), and the inhibition zones for Salmonella typhimurium, Salmonella enteritidis, Shigella flexneri, Escherichia coli, Listeria monocytogenes, S. dysenteriae 301, Staphylococcus aureus Cowan1, and Propionibacterium acnes were 16, 15, 19, 20, 21, 20, and 27 mm. Moreover, the low concentration of Aloe fermentation supernatant had significantly reduced the production of IL-1ß, TNF-α, and IL-6 in both mRNA and protein levels (P < 0.01). Therefore, the Aloe fermentation supernatant can be used as functional beverage or cosmetic ingredients to guard human intestinal health, delaying senescence, and prevent chronic diseases.

Inhibition of tumor growth by U0126 is associated with induction of interferon-γ production.

Several MEK1/2 inhibitors have been in clinical trial evaluation for cancer treatment. Interferon-γ (IFN-γ) is a cytokine with multiple biological functions including antitumor activity. Expression of IFN-γ can be induced by liver X receptor (LXR), a ligand-activated transcription factor. However, it remains unknown if the anti-cancer action of MEK1/2 inhibitors is completed, at least in part, by activating IFN-γ expression. In this study, we determined that U0126, a MEK1/2 inhibitor, increased tumor-free and survival rates and decreased growth of inoculated Lewis lung carcinomas in wild type mice. However, the protective effects were substantially attenuated in IFN-γ deficient (IFN-γ-/-) mice. At cellular and molecular levels, MEK1/2 inhibitors increased IFN-γ protein and mRNA expression and activated natural IFN-γ promoter but not the IFN-γ promoters with mutations of the LXR responsive elements (LXREs). MEK1/2 inhibitors also enhanced formation of the LXRE-nuclear protein complexes by inducing LXR expression and nuclear translocation. Similarly, MEK1/2 siRNA inhibited phosphorylation of ERK1/2 by MEK1/2 while activated IFN-γ expression. In contrast, inhibition of LXR expression by siRNA blocked MEK1/2 inhibitors-induced IFN-γ expression. U0126 also inhibited chemicals-induced pulmonary carcinomas, which was associated with increased IFN-γ expression in the lung. Taken together, our study suggests that MEK1/2 inhibitors induce IFN-γ production in an LXR-dependent manner and the induction of IFN-γ expression can partially contribute to the anti-tumorigenic properties of U0126.

Identification of interferon-γ as a new molecular target of liver X receptor.

LXR (liver X receptor) is a ligand-activated transcription factor and plays an important role in regulation of lipid homoeostasis and inflammation. Several studies indicate that LXR inhibits IFN-γ (interferon γ)-induced biological responses; however, the influence of LXR on IFN-γ expression has not been fully elucidated. In the present study, we investigated the effects of LXR activation on IFN-γ expression at different levels. At the molecular level, we surprisingly observed that LXR ligand (T0901317) induced macrophage and T-cell IFN-γ protein expression which was associated with increased mRNA and secreted protein levels in culture medium. In contrast, selective inhibition of LXRα and/or LXRß expression by siRNA reduced IFN-γ expression. Promoter analysis defined the multiple LXREs (LXR-responsive elements) in the proximal region of the IFN-γ promoter. EMSAs and ChIP indicated that LXR activation enhanced the binding of LXR protein to these LXREs. In vivo, T0901317 increased wild-type mouse serum IFN-γ levels and IFN-γ expression in the lung and lymph nodes. Functionally, we observed that administration of T0901317 to wild-type mice increased rates of survival and being tumour-free, and inhibited tumour growth when the animals were inoculated with LLC1 carcinoma. In contrast, these protective effects were substantially attenuated in IFN-γ-knockout (IFN-γ-/-) mice, suggesting that the induction of IFN-γ production plays a critical role in T0901317-inhibited tumour growth. Taken together, the results of the present study show that IFN-γ is another molecular target of LXR activation, and it suggests a new mechanism by which LXR inhibits tumour growth.

DNA topoisomerase II inhibitors induce macrophage ABCA1 expression and cholesterol efflux-an LXR-dependent mechanism.

ATP-binding cassette transporter A1 (ABCA1) facilitates cholesterol efflux and thereby inhibits lipid-laden macrophage/foam cell formation and atherosclerosis. ABCA1 expression is transcriptionally regulated by activation of liver X receptor (LXR). Both etoposide and teniposide are DNA topoisomerase II (Topo II) inhibitors and are chemotherapeutic medications used in the treatment of various cancers. Interestingly, etoposide inhibits atherosclerosis in rabbits by unclear mechanisms. Herein, we report the effects of etoposide and teniposide on macrophage ABCA1 expression and cholesterol efflux. Both etoposide and teniposide increased macrophage free cholesterol efflux. This increase was associated with increased ABCA1 mRNA and protein expression. Etoposide and teniposide also increased ABCA1 promoter activity in an LXR-dependent manner and formation of the LXRE-LXR/RXR complex indicating that transcriptional induction had occurred. Expression of ABCG1 and fatty acid synthase (FAS), another two LXR-targeted genes, was also induced by etoposide and teniposide. In vivo, administration of mice with either etoposide or teniposide induced macrophage ABCA1 expression and enhanced reverse cholesterol transport from macrophages to feces. Taken together, our study indicates that etoposide and teniposide increase macrophage ABCA1 expression and cholesterol efflux that may be attributed to the anti-atherogenic properties of etoposide. Our study also describes a new function for Topo II inhibitors in addition to their role in anti-tumorigenesis.

Tamoxifen inhibits macrophage FABP4 expression through the combined effects of the GR and PPARγ pathways.

Macrophage adipocyte fatty acid-binding protein (FABP4) plays an important role in foam cell formation and development of atherosclerosis. Tamoxifen inhibits this disease process. In the present study, we determined whether the anti-atherogenic property of tamoxifen was related to its inhibition of macrophage FABP4 expression. We initially observed that tamoxifen inhibited macrophage/foam cell formation, but the inhibition was attenuated when FABP4 expression was selectively inhibited by siRNA.We then observed that tamoxifen and 4-hydroxytamoxifen inhibited FABP4 protein expression in primary macrophages isolated from both the male and female wild-type mice, suggesting that the inhibition is sex-independent. Tamoxifen and 4-hydroxytamoxifen inhibited macrophage FABP4 protein expression induced either by activation of GR (glucocorticoid receptor) or PPARγ (peroxisome-proliferator-activated receptor γ). Associated with the decreased protein expression, Fabp4 mRNA expression and promoter activity were also inhibited by tamoxifen and 4-hydroxytamoxifen, indicating transcriptional regulation. Analysis of promoter activity and EMSA/ChIP assays indicated that tamoxifen and 4-hydroxytamoxifen activated the nGRE (negative glucocorticoid regulatory element), but inhibited the PPRE (PPARγ regulatory element) in the Fabp4 gene. In vivo, administration of tamoxifen to ApoE (apolipoprotein E)-deficient (apoE-/-) mice on a high-fat diet decreased FABP4 expression in macrophages and adipose tissues as well as circulating FABP4 levels. Tamoxifen also inhibited FABP4 protein expression by human blood monocyte-derived macrophages. Taken together, the results of the present study show that tamoxifen inhibited FABP4 expression through the combined effects of GR and PPARγ signalling pathways. Our findings suggest that the inhibition of macrophage FABP4 expression can be attributed to the antiatherogenic properties of tamoxifen.

Diagnostic value of sphingolipid metabolism-related genes CD37 and CXCL9 in nonalcoholic fatty liver disease.

The development of nonalcoholic fatty liver disease (NAFLD) has been reported to be caused by sphingolipid family inducing insulin resistance, mitochondrial dysfunction, and inflammation, which can be regulated by multiple sphingolipid metabolic pathways. This study aimed to explore the molecular mechanism of crucial sphingolipid metabolism related genes (SMRGs) in NAFLD. Firstly, the datasets (GSE48452, GSE126848, and GSE63067) from the Gene Expression Omnibus database and sphingolipid metabolism genes (SMGs) from previous research were collected for this study. The differentially expressed genes (DEGs) between different NAFLD and controls were acquired through "limma," and the SMRGs were authenticated via weighted gene co-expression network analysis (WGCNA). After overlapping the DEGs and SMRGs, the causality between the intersection genes (DE-SMRGs) and NAFLD was explored to sort out the candidate biomarkers by Mendelian randomization (MR) study. The receiver operating characteristic (ROC) curves of candidate biomarkers in GSE48452 and GSE126848 were yielded to determine the biomarkers, followed by the nomogram construction and enrichment analysis. Finally, the immune infiltration analysis, the prediction of transcription factors (TFs) and drugs targeting biomarkers were put into effect. A total of 23 DE-SMRGs were acquired based on the differential analysis and weighted gene co-expression network analysis (WGCNA), of which 3 DE-SMRGs (CD37, CXCL9 and IL7R) were picked out for follow-up analysis through univariate and multivariate MR analysis. The values of area under ROC curve of CD37 and CXCL9 were >0.7 in GSE48452 and GSE126848, thereby being regarded as biomarkers, which were mainly enriched in amino acid metabolism. With respect to the Spearman analysis between immune cells and biomarkers, CD37 and CXCL9 were significantly positively associated with M1 macrophages (P < .001), whose proportion was observably higher in NAFLD patients compared with controls. At last, TFs (ZNF460 and ZNF384) of CD37 and CXCL9 and a total of 79 chemical drugs targeting CD37 and CXCL9 were predicted. This study mined the pivotal SMRGs, CD37 and CXCL9, and systematically explored the mechanism of action of both biomarkers based on the public databases, which could tender a fresh reference for the clinical diagnosis and therapy of NAFLD.

TRIM65 knockout inhibits the development of HCC by polarization tumor-associated macrophages towards M1 phenotype via JAK1/STAT1 signaling pathway.

BACKGROUND & AIMS: Tumor-associated macrophages (TAMs) are main components of immune cells in tumor microenvironment (TME), and play a crucial role in tumor progression. Tripartite motif-containing protein 65 (TRIM65) has been associated with tumor progression. However, whether TRIM65 regulate the interaction of tumor cell and TAMs in HCC and the underlying mechanisms remain unknown. In this study, we investigated the role of TRIM65 in TME of HCC and explored its underlying mechanisms. METHODS: The relation of TRIM65 expression level with tumor grades, TNM stages, and worse prognosis of HCC patients was evaluated by bioinformatics analysis, as well as immune infiltration level of macrophages. TRIM65 shRNA was transfected into HepG2 cells, and TRIM65 overexpression plasmid was transfected into Huh7 cells, and the effect of TRIM65 on cell growth was examined by EdU assay. The mouse subcutaneous Hep1-6 tumor-bearing model with WT and TRIM65-/- mice was established to study the role of TRIM65 in HCC. Immunohistochemistry staining, Immunofluorescence staining, qRT-PCR and western blot were performed to evaluate the effect of TRIM65 on TAM infiltration, TAM polarization and JAK1/STAT1 signaling pathway. RESULTS: Bioinformatics analysis revealed that TRIM65 was upregulated in 16 types of cancer especially in HCC, and high level of TRIM65 was strongly correlated with higher tumor grades, TNM stages, and worse prognosis of patients with HCC as well as immune infiltration level of macrophages (M0, M1, and M2). Moreover, we observed that TRIM65 shRNA-mediated TRIM65 knockdown significantly inhibited the HepG2 cells growth while TRIM65 overexpression highly increased the Huh7 cells growth in vitro. TRIM65 knockout significantly inhibited the tumor growth as well as macrophages polarization towards M2 but promoted macrophages polarization towards M1 in vivo. Mechanistically, the results demonstrate that TRIM65 knockout promoted macrophage M1 polarization in conditioned medium-stimulated peritoneal macrophages and in tumor tissues by activating JAK1/STAT1 signaling pathway. CONCLUSIONS: Taken together, our study suggests that tumor cells utilize TRIM65-JAK1/STAT1 axis to inhibit macrophage M1 polarization and promote tumor growth, reveals the role of TRIM65 in TAM-targeting tumor immunotherapy.

Activation of liver X receptor induces macrophage interleukin-5 expression.

IL-5 stimulates production of T15/EO6 IgM antibodies that can block the uptake of oxidized low density lipoprotein by macrophages, whereas a deficiency in macrophage IL-5 expression accelerates development of atherosclerosis. Liver X receptors (LXRs) are ligand-activated transcription factors that can induce macrophage ABCA1 expression and cholesterol efflux, thereby inhibiting the development of atherosclerosis. However, it remains unknown whether additional mechanisms, such as the regulation of macrophage IL-5 expression, are related to the anti-atherogenic properties of LXR. We initially defined IL-5 expression in macrophages where the LXR ligand (T0901317) induced macrophage IL-5 protein expression and secretion. The overexpression of LXR increased, whereas its knockdown inhibited IL-5 expression. Furthermore, we found that LXR activation increased IL-5 transcripts, promoter activity, formation of an LXR·LXR-responsive element complex, and IL-5 protein stability. In vivo, we found that T0901317 increased IL-5 and total IgM levels in plasma and IL-5 expression in multiple tissues in wild type mice. In LDL receptor knock-out (LDLR(-/-)) mice, T0901317 increased IL-5 expression in the aortic root area. Taken together, our studies demonstrate that macrophage IL-5 is a target gene for LXR activation, and the induction of macrophage IL-5 expression can be related to LXR-inhibited atherosclerosis.

An update on the role of TRIM/NLRP3 signaling pathway in atherosclerosis.

Atherosclerosis (AS) is a chronic inflammatory disease of large and medium arteries that includes lipid metabolism disorder and recruitment of immune cells to the artery wall. An increasing number of studies have confirmed that inflammasome over-activation is associated with the onset and progression of atherosclerosis. The NLRP3 inflammasome, in particular, has been proven to increase the incidence rate of cardiovascular diseases (CVD) by promoting pro-inflammatory cytokine release and reducing plaque stability. The strict control of inflammasome and prevention of excessive inflammatory reactions have been the research focus of inflammatory diseases. Tripartite motif (TRIM) is a protein family with a conservative structure and rapid evolution. Several studies have demonstrated the TRIM family's regulatory role in mediating inflammation. This review aims to clarify the relationship between TRIMs and NLRP3 inflammasome and provide insights for future research and treatment discovery.

LPS inhibits TRIM65 expression in macrophages and C57BL/6J mouse by activating the ERK1/2 signaling pathway.

Activated macrophages serve a key role in various inflammatory diseases, such as atherosclerosis and septic shock. Tripartite motif-containing protein 65 (TRIM65) has been previously reported to participate in tumor progression and lung inflammation. However, the molecular mechanisms that controls its expression under inflammatory conditions and its consequences in activated macrophages remain poorly understood. The present study first collected the tissues of C57BL/6J mice, smooth muscle cells, macrophages and endothelial cells to determine the expression and distribution of TRIM65 by reverse transcription-quantitative (RT-q) PCR and western blotting. Mouse and human macrophages were treated with LPS and C57BL/6J mice were intraperitoneally injected with LPS followed by isolation of spleen, lung, aorta and bone marrow. Following treatment, TRIM65 mRNA and protein level was examined by RT-qPCR and western blotting. The results showed that TRIM65 was highly expressed in organs of the immune system, such as the spleen, lymph node and thymus, but lowly expressed in heart, liver, brain and kidneys. TRIM65 was also highly expressed in macrophages and endothelial cells. TRIM65 mRNA and protein expression levels were found to be decreased in LPS-treated macrophages in vitro and in tissues isolated from C57BL/6J mice intraperitoneally injected with LPS in vivo. In addition, to identify the signaling pathways by which LPS regulates TRIM65 expression, inhibitors of MAPK and Akt signaling pathways were used to treat macrophages followed by examination the expression of TRIM65 by western blotting. The results demonstrated that LPS-inhibited TRIM65 expression was blocked by treatment with the ERK1/2 inhibitor U0126. Moreover, the RT-qPCR results showed that TRIM65 knockout potentiated LPS-induced expression of inflammatory cytokines in macrophages. Taken together, data from the present study suggest that LPS decreased TRIM65 expression in macrophages and C57BL/6J mouse by activating the ERK1/2 signaling pathway, whilst TRIM65 knockout promoted macrophage activation. This information may facilitate the development of potential therapeutic strategies for the prevention and treatment of inflammatory diseases, such as atherosclerosis.

Neuroprotective effects of an engineered Escherichia coli Nissle 1917 on Parkinson's disease in mice by delivering GLP-1 and modulating gut microbiota.

Considerable evidence suggests that insulin resistance is closely linked to Parkinson's disease (PD), leading to agents aiming at treating diabetes can be regarded as new neuroprotective strategies in PD, notably glucagon-like peptide-1 (GLP-1). However, the extremely short half-life of GLP-1 due to degradation by the ubiquitous proteolytic enzyme limits its clinical application. In this study, we engineered the recombinant integrant probiotic strain Escherichia coli Nissle 1917 (EcN) to create a strain EcN-GLP-1 that effectively delivers the heterologous GLP-1 molecule. Subsequently, we assessed its neuroprotective effects on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mice. We demonstrated that EcN-GLP-1 treatment could improve motor deficits, increase tyrosine hydroxylase-positive neurons, suppress microglia and astrocyte activation, reduce brain and colon inflammation, and ameliorate colonic barrier function damaged by MPTP induction. Meanwhile, we confirmed that the oral administration of EcN-GLP-1 could restore the disturbance of gut microbiota in the MPTP-induced PD mice, by reducing the relative abundances of Akkermansia and Oscillospira, and increasing the level of Prevotella in the gut. These results support further development of an engineered probiotic platform in which production of GLP-1 for gut-brain disorders, such as PD.

Osteopontin Promotes Macrophage M1 Polarization by Activation of the JAK1/STAT1/HMGB1 Signaling Pathway in Nonalcoholic Fatty Liver Disease.

Background and Aims: Osteopontin (OPN) is reported to be associated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD). However, the function of OPN in NAFLD is still inconclusive. Therefore, our aim in this study was to evaluate the role of OPN in NAFLD and clarify the involved mechanisms. Methods: We analyzed the expression change of OPN in NAFLD by bioinformatic analysis, qRT-PCR, western blotting and immunofluorescence staining. To clarify the role of OPN in NAFLD, the effect of OPN from HepG2 cells on macrophage polarization and the involved mechanisms were examined by FACS and western blotting. Results: OPN was significantly upregulated in NAFLD patients compared with normal volunteers by microarray data, and the high expression of OPN was related with disease stage and progression. OPN level was also significantly increased in liver tissue samples of NAFLD from human and mouse, and in HepG2 cells treated with oleic acid (OA). Furthermore, the supernatants of OPN-treated HepG2 cells promoted the macrophage M1 polarization. Mechanistically, OPN activated the janus kinase 1(JAK1)/signal transducers and activators of transcription 1 (STAT1) signaling pathway in HepG2 cells, and consequently HepG2 cells secreted more high-mobility group box 1 (HMGB1), thereby promoting macrophage M1 polarization. Conclusions: OPN promoted macrophage M1 polarization by increasing JAK1/STAT1-induced HMGB1 secretion in hepatocytes.