lncRNA PVT1沉默对高糖诱导的血管内皮细胞增殖、凋亡及氧化应激的影响*

目的: 探讨抑制lncRNA PVT1对高糖诱导的血管内皮细胞的增殖,凋亡和氧化应激的影响。方法: 体外培养人脐静脉内皮细胞(HUVECs),分为四组:对照组(5.5 mmol/L葡萄糖),高糖组(30 mmol/L葡萄糖),高糖+siNC组(30 mmol/L葡萄糖+siNC,细胞转染阴性对照组),高糖+siPVT1组(30 mmol/L葡萄糖+siPVT1,抑制lncRNA PVT1组)。采用荧光定量PCR的方法检测转染后PVT1的表达水平。MTT检测siPVT1(短片段干扰RNA PVT1)对高糖诱导的HUVECs细胞增殖能力的影响。流式细胞术检测siPVT1对高糖诱导的HUVECs细胞ROS和凋亡水平。Western blot检测HUVECs细胞中凋亡相关蛋白如Bax,Bcl-2和cleaved-caspase-3的表达水平。结果: 与对照组比较,转染siPVT1后,PVT1的表达水平显著降低(P＜0.05)。MTT结果显示,与对照组比较,培养24 h和48 h后高糖组中HUVECs细胞增殖活力均显著降低,与高糖+siNC组(阴性对照组)比较,培养24 h和48 h后,高糖+siPVT1组中的HUVECs细胞增殖活力显著增加(P＜0.05)。流式细胞术检测结果表明,与对照组比较,高糖组HUVECs细胞中ROS和凋亡率均显著增加;和高糖+siNC组比较,高糖+siPVT1组中HUVECs细胞中ROS和凋亡率均有减少(P＜0.05)。Western blot结果表明,与对照组比较,高糖组中cleaved-caspase-3和Bax表达水平均显著上调,Bcl-2的表达水平显著下调(P＜0.05,P＜0.01)。与高糖+siNC组比较,高糖+siPVT1组cleaved-caspase-3和Bax表达水平显著下调,Bcl-2的表达显著上调(P＜0.05,P＜0.01)。结论: 抑制lncRNA PVT1可以显著增加高糖诱导的HUVECs细胞增殖活力,减轻氧化应激,抑制细胞凋亡。     

Long non‐coding RNA F11‐AS1 inhibits HBV‐related hepatocellular carcinoma progression by regulating NR1I3 via binding to microRNA‐211‐5p

Long non‐coding RNAs (lncRNAs) could regulate growth and metastasis of hepatocellular carcinoma (HCC). In this study, we aimed to investigate the mechanism of lncRNA F11‐AS1 in hepatitis B virus (HBV)–related HCC. The relation of lncRNA F11‐AS1 expression in HBV‐related HCC tissues to prognosis was analysed in silico. Stably HBV‐expressing HepG2.2.15 cells were established to explore the regulation of lncRNA F11‐AS1 by HBx protein, as well as to study the effects of overexpressed lncRNA F11‐AS1 on proliferation, migration, invasion and apoptosis in vitro. Subsequently, the underlying interactions and roles of lncRNA F11‐AS1/miR‐211‐5p/NR1I3 axis in HBV‐related HCC were investigated. Additionally, the influence of lncRNA F11‐AS1 and miR‐211‐5p on tumour growth and metastasis capacity of HepG2.2.15 cells were studied on tumour‐bearing nude mice. Poor expression of lncRNA F11‐AS1 was correlated with poor prognosis in patients with HBV‐related HCC, and its down‐regulation was caused by the HBx protein. lncRNA F11‐AS1 was proved to up‐regulate the NR1I3 expression by binding to miR‐211‐5p. Overexpression of lncRNA F11‐AS1 reduced the proliferation, migration and invasion, yet induced apoptosis of HepG2.2.15 cells in vitro, which could be abolished by overexpression of miR‐211‐5p. Additionally, either lncRNA F11‐AS1 overexpression or miR‐211‐5p inhibition attenuated the tumour growth and metastasis capacity of HepG2.2.15 cells in vivo. Collectively, lncRNA F11‐AS1 acted as a modulator of miR‐211‐5p to positively regulate the expression of NR1I3, and the lncRNA F11‐AS1/miR‐211‐5p/NR1I3 axis participated in HBV‐related HCC progression via interference with the cellular physiology of HCC.     

MDM2 is implicated in high‐glucose‐induced podocyte mitotic catastrophe via Notch1 signalling

Podocyte injury and depletion are essential events involved in the pathogenesis of diabetic nephropathy (DN). As a terminally differentiated cell, podocyte is restricted in ‘post‐mitosis’ state and unable to regenerate. Re‐entering mitotic phase will cause podocyte disastrous death which is defined as mitotic catastrophe (MC). Murine double minute 2 (MDM2), a cell cycle regulator, is widely expressed in renal resident cells including podocytes. Here, we explore whether MDM2 is involved in podocyte MC during hyperglycaemia. We found aberrant mitotic podocytes with multi‐nucleation in DN patients. In vitro, cultured podocytes treated by high glucose (HG) also showed an up‐regulation of mitotic markers and abnormal mitotic status, accompanied by elevated expression of MDM2. HG exposure forced podocytes to enter into S phase and bypass G2/M checkpoint with enhanced expression of Ki67, cyclin B1, Aurora B and p‐H3. Genetic deletion of MDM2 partly reversed HG‐induced mitotic phase re‐entering of podocytes. Moreover, HG‐induced podocyte injury was alleviated by MDM2 knocking down but not by nutlin‐3a, an inhibitor of MDM2‐p53 interaction. Interestingly, knocking down MDM2 or MDM2 overexpression showed inhibition or activation of Notch1 signalling, respectively. In addition, genetic silencing of Notch1 prevented HG‐mediated podocyte MC. In conclusion, high glucose up‐regulates MDM2 expression and leads to podocyte MC. Notch1 signalling is an essential downstream pathway of MDM2 in mediating HG‐induced MC in podocytes.     

HMGB1 mediates hyperglycaemia‐induced cardiomyocyte apoptosis via ERK/Ets‐1 signalling pathway

Apoptosis is a key event involved in diabetic cardiomyopathy. The expression of high mobility group box 1 protein (HMGB1) is up‐regulated in diabetic mice. However, the molecular mechanism of high glucose (HG)‐induced cardiomyocyte apoptosis remains obscure. We aimed to determine the role of HMGB1 in HG‐induced apoptosis of cardiomyocytes. Treating neonatal primary cardiomyocytes with HG increased cell apoptosis, which was accompanied by elevated levels of HMGB1. Inhibition of HMGB1 by short‐hairpin RNA significantly decreased HG‐induced cell apoptosis by reducing caspase‐3 activation and ratio of Bcl2‐associated X protein to B‐cell lymphoma/leukemia‐2 (bax/bcl‐2). Furthermore, HG activated E26 transformation‐specific sequence‐1 (Ets‐1), and HMGB1 inhibition attenuated HG‐induced activation of Ets‐1 via extracellular signal‐regulated kinase 1/2 (ERK1/2) signalling. In addition, inhibition of Ets‐1 significantly decreased HG‐induced cardiomyocyte apoptosis. Similar results were observed in streptozotocin‐treated diabetic mice. Inhibition of HMGB1 by short‐hairpin RNA markedly decreased myocardial cell apoptosis and activation of ERK and Ets‐1 in diabetic mice. In conclusion, inhibition of HMGB1 may protect against hyperglycaemia‐induced cardiomyocyte apoptosis by down‐regulating ERK‐dependent activation of Ets‐1.     

Identification of lncRNA‐155 encoded by MIR155HG as a novel regulator of innate immunity against influenza A virus infection

Long noncoding RNAs (lncRNAs) are single‐stranded RNA molecules longer than 200 nt that regulate many cellular processes. MicroRNA 155 host gene (MIR155HG) encodes the microRNA (miR)‐155 that regulates various signalling pathways of innate and adaptive immune responses against viral infections. MIR155HG also encodes a lncRNA that we call lncRNA‐155. Here, we observed that expression of lncRNA‐155 was markedly upregulated during influenza A virus (IAV) infection both in vitro (several cell lines) and in vivo (mouse model). Interestingly, robust expression of lncRNA‐155 was also induced by infections with several other viruses. Disruption of lncRNA‐155 expression in A549 cells diminished the antiviral innate immunity against IAV. Furthermore, knockout of lncRNA‐155 in mice significantly increased IAV replication and virulence in the animals. In contrast, overexpression of lncRNA‐155 in human cells suppressed IAV replication, suggesting that lncRNA‐155 is involved in host antiviral innate immunity induced by IAV infection. Moreover, we found that lncRNA‐155 had a profound effect on expression of protein tyrosine phosphatase 1B (PTP1B) during the infection with IAV. Inhibition of PTP1B by lncRNA‐155 resulted in higher production of interferon‐beta (IFN‐β) and several critical interferon‐stimulated genes (ISGs). Together, these observations reveal that MIR155HG derived lncRNA‐155 can be induced by IAV, which modulates host innate immunity during the virus infection via regulation of PTP1B‐mediated interferon response.     

Angiotensin II‐induced redox‐sensitive SGLT1 and 2 expression promotes high glucose‐induced endothelial cell senescence

High glucose (HG)‐induced endothelial senescence and dysfunction contribute to the increased cardiovascular risk in diabetes. Empagliflozin, a selective sodium glucose co‐transporter2 (SGLT2) inhibitor, reduced the risk of cardiovascular mortality in type 2 diabetic patients but the protective mechanism remains unclear. This study examines the role of SGLT2 in HG‐induced endothelial senescence and dysfunction. Porcine coronary artery cultured endothelial cells (ECs) or segments were exposed to HG (25 mmol/L) before determination of senescence‐associated beta‐galactosidase activity, protein level by Western blot and immunofluorescence staining, mRNA by RT‐PCR, nitric oxide (NO) by electron paramagnetic resonance, oxidative stress using dihydroethidium and glucose uptake using 2‐NBD‐glucose. HG increased ECs senescence markers and oxidative stress, down‐regulated eNOS expression and NO formation, and induced the expression of VCAM‐1, tissue factor, and the local angiotensin system, all these effects were prevented by empagliflozin. Empagliflozin and LX‐4211 (dual SGLT1/2 inhibitor) reduced glucose uptake stimulated by HG and H₂O₂ in ECs. HG increased SGLT1 and 2 protein levels in cultured ECs and native endothelium. Inhibition of the angiotensin system prevented HG‐induced ECs senescence and SGLT1 and 2 expression. Thus, HG‐induced ECs ageing is driven by the local angiotensin system via the redox‐sensitive up‐regulation of SGLT1 and 2, and, in turn, enhanced glucotoxicity.     

lncRNA NR2F1‐AS1 promotes breast cancer angiogenesis through activating IGF‐1/IGF‐1R/ERK pathway

Long non‐coding RNAs (lncRNAs) take various effects in cancer mostly through sponging with microRNAs (miRNAs). lncRNA NR2F1‐AS1 is found to promote tumour progression in hepatocellular carcinoma, endometrial cancer and thyroid cancer. However, the role of lncRNA NR2F1‐AS1 in breast cancer angiogenesis remains unknown. In this study, we found lncRNA NR2F1‐AS1 was positively related with CD31 and CD34 in breast cancer through Pearson's correlation analysis, while lncRNA NR2F1‐AS1 transfection promoted human umbilical vascular endothelial cell (HUVEC) tube formation. In breast cancer cells, lncRNA NR2F1‐AS1 enhanced the HUVEC proliferation, tube formation and migration ability through tumour‐conditioned medium (TCM). In zebrafish model, lncRNA NR2F1‐AS1 increased the breast cancer cell‐related neo‐vasculature and subsequently promoted the breast cancer cell metastasis. In mouse model, lncRNA NR2F1‐AS1 promoted the tumour vessel formation, increased the micro vessel density (MVD) and then induced the growth of primary tumour. Mechanically, lncRNA NR2F1‐AS1 increased insulin‐like growth factor‐1 (IGF‐1) expression through sponging miRNA‐338‐3p in breast cancer cells and then activated the receptor of IGF‐1 (IGF‐1R) and extracellular signal‐regulated kinase (ERK) pathway in HUVECs. These results indicated that lncRNA NR2F1‐AS1 could promote breast cancer angiogenesis through IGF‐1/IGF‐1R/ERK pathway.     

Long noncoding RNA PVT1 facilitates high glucose-induced cardiomyocyte death through the miR-23a-3p/CASP10 axis

Dilated cardiomyopathy (DCM) is the leading cause of morbidity and mortality in diabetic patients. Long noncoding RNA plasmacytoma variant translocation 1 (PVT1) has been shown to be related to the pathogenesis of DCM. However, the mechanism by which PVT1 regulates DCM pathogenesis is unclear. High glucose level was employed to construct a DCM cell model in vitro. Cell viability was determined via cell counting kit-8 assay. The level of lactate dehydrogenase (LDH) was measured with the corresponding kit. Expression levels of PVT1, miR-23a-3p, and caspase-10 (CASP10) messenger RNA were evaluated with a quantitative real-time polymerase chain reaction. Cell apoptosis was assessed by flow cytometry assay. Protein levels of B-cell lymphoma 2-associated X (Bax), cleaved-caspase-3 (cleaved-casp-3), and CASP10 were examined via western blot analysis. The relationship between PVT1 or CASP10 and miR-23a-3p was verified with dual-luciferase reporter assay. We observed that PVT1 and CASP10 were upregulated while miR-23a-3p was downregulated in high glucose-induced cardiomyocytes. High glucose levels repressed cardiomyocyte activity and induced cardiomyocyte apoptosis, but this influence was antagonized by PVT1 knockdown or miR-23a-3p overexpression. Furthermore, PVT1 acted as a sponge for miR-23a-3p, and miR-23a-3p inhibition counterbalanced the influence of PVT1 silencing on viability and apoptosis of cardiomyocytes under high glucose level treatment. PVT1 could increase CASP10 expression via sponging miR-23a-3p. In conclusion, PVT1 acted as a deleterious lncRNA in DCM. PVT1 facilitated cardiomyocyte death by regulating the miR-23a-3p/CASP10, which offered a new mechanism to comprehend the pathogenesis of DCM.     

miR‐185 affected the EMT,cell viability,and proliferation via DNMT1/MEG3 pathway in TGF‐β1‐induced renal fibrosis

Kidney fibrosis is usually the final manifestation of a wide variety of renal diseases. Recent years, research reported that long non‐coding RNAs (lncRNAs) played important roles in a variety of human diseases. However, the role and underlying mechanisms of lncRNAs in kidney fibrosis were complicated and largely unclear. In our study, we constructed the cell model of renal fibrosis in HK2 cells using transforming growth factor β1 (TGF‐β1) and found that lncRNA maternally expressed gene 3 (MEG3) was downregulated in TGF‐β1‐induced renal fibrosis. We then found that overexpressed MEG3 inhibited the TGF‐β1‐induced promotion of epithelial–mesenchymal transition, cell viability, and proliferation. Furthermore, we demonstrated that DNA methyltransferases 1 (DNMT1) regulated the MEG3 expression by altering the CpGs methylation level of MEG3 promoter in TGF‐β1‐induced renal fibrosis. In addition, we further revealed that miR‐185 could regulate the DNMT1 expression and thus, modulate the MEG3 in TGF‐β1‐induced renal fibrosis. Ultimately, our study illustrated that the modulation of the miR‐185/ DNMT1/ MEG3 pathway exerted important roles in TGF‐β1‐induced renal fibrosis. In summary, our finding displayed a novel regulatory mechanism for TGF‐β1‐induced renal fibrosis, which provided a new potential therapeutic target for renal fibrosis.     

5,2′‐dibromo‐2,4′,5′‐trihydroxydiphenylmethanone attenuates LPS‐induced inflammation and ROS production in EA.hy926 cells via HMBOX1 induction

Inflammation and reactive oxygen species (ROS) are important factors in the pathogenesis of atherosclerosis (AS). 5,2′‐dibromo‐2,4′,5′‐trihydroxydiphenylmethanone (TDD), possess anti‐atherogenic properties; however, its underlying mechanism of action remains unclear. Therefore, we sought to understand the therapeutic molecular mechanism of TDD in inflammatory response and oxidative stress in EA.hy926 cells. Microarray analysis revealed that the expression of homeobox containing 1 (HMBOX1) was dramatically upregulated in TDD‐treated EA.hy926 cells. According to the gene ontology (GO) analysis of microarray data, TDD significantly influenced the response to lipopolysaccharide (LPS); it suppressed the LPS‐induced adhesion of monocytes to EA.hy926 cells. Simultaneously, TDD dose‐dependently inhibited the production or expression of IL‐6, IL‐1β, MCP‐1, TNF‐α, VCAM‐1, ICAM‐1 and E‐selectin as well as ROS in LPS‐stimulated EA.hy926 cells. HMBOX1 knockdown using RNA interference attenuated the anti‐inflammatory and anti‐oxidative effects of TDD. Furthermore, TDD inhibited LPS‐induced NF‐κB and MAPK activation in EA.hy926 cells, but this effect was abolished by HMBOX1 knockdown. Overall, these results demonstrate that TDD activates HMBOX1, which is an inducible protective mechanism that inhibits LPS‐induced inflammation and ROS production in EA.hy926 cells by the subsequent inhibition of redox‐sensitive NF‐κB and MAPK activation. Our study suggested that TDD may be a potential novel agent for treating endothelial cells dysfunction in AS.     

Long non‐coding RNA MALAT1 mediates hypoxia‐induced pro‐survival autophagy of endometrial stromal cells in endometriosis

Endometriosis is a common gynecological disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells. Hypoxia has been implicated as a crucial microenvironmental factor that contributes to endometriosis. It has been reported that long non‐coding RNA MALAT1 (lncRNA‐MALAT1) highly expressed in endometriosis and up‐regulated by hypoxia. Hypoxia may also induce autophagy, which might act as cell protective mechanism. However, the relationship between lncRNA‐MALAT1 and autophagy under hypoxia conditions in endometriosis remains unknown. In the present study, we found that both lncRNA‐MALAT1 and autophagy level were up‐regulated in ectopic endometrium from patients with endometriosis, and its expression level correlates positively with that of hypoxia‐inducible factor‐1α (HIF‐1α). In cultured human endometrial stromal cells, both lncRNA‐MALAT1 and autophagy were induced by hypoxia in a time‐dependent manner and lncRNA‐MALAT1 up‐regulation was dependent on HIF‐1α signalling. Our analyses also show that knockdown of lncRNA‐MALAT1 suppressed hypoxia induced autophagy. Furthermore, inhibiting autophagy with specific inhibitor 3‐Methyladenine (3‐MA) and Beclin1 siRNA enhanced apoptosis of human endometrial stromal cells under hypoxia condition. Collectively, our findings identify that lncRNA‐MALAT1 mediates hypoxia‐induced pro‐survival autophagy of endometrial stromal cells in endometriosis.     

Valsartan independent of AT1 receptor inhibits tissue factor,TLR‐2 and ‐4 expression by regulation of Egr‐1 through activation of AMPK in diabetic conditions

Patients suffering from diabetes mellitus (DM) are at a severe risk of atherothrombosis. Early growth response (Egr)‐1 is well characterized as a central mediator in vascular pathophysiology. We tested whether valsartan independent of Ang II type 1 receptor (AT₁R) can reduce tissue factor (TF) and toll‐like receptor (TLR)‐2 and ‐4 by regulating Egr‐1 in THP‐1 cells and aorta in streptozotocin‐induced diabetic mice. High glucose (HG, 15 mM) increased expressions of Egr‐1, TF, TLR‐2 and ‐4 which were significantly reduced by valsartan. HG increased Egr‐1 expression by activation of PKC and ERK1/2 in THP‐1 cells. Valsartan increased AMPK phosphorylation in a concentration and time‐dependent manner via activation of LKB1. Valsartan inhibited Egr‐1 without activation of PKC or ERK1/2. The reduced expression of Egr‐1 by valsartan was reversed by either silencing Egr‐1, or compound C, or DN‐AMPK‐transfected cells. Valsartan inhibited binding of NF‐κB and Egr‐1 to TF promoter in HG condition. Furthermore, valsartan reduced inflammatory cytokine (TNF‐α, IL‐6 and IL‐1β) production and NF‐κB activity in HG‐activated THP‐1 cells. Interestingly, these effects of valsartan were not affected by either silencing AT₁R in THP‐1 cells or CHO cells, which were devoid of AT₁R. Importantly, administration of valsartan (20 mg/kg, i.p) for 8 weeks significantly reduced plasma TF activity, expression of Egr‐1, TLR‐2, ‐4 and TF in thoracic aorta and improved glucose tolerance of streptozotocin‐induced diabetic mice. Taken together, we concluded that valsartan may reduce atherothrombosis in diabetic conditions through AMPK/Egr‐1 regulation.     

LncRNA NR2F1‐AS1 regulates hepatocellular carcinoma oxaliplatin resistance by targeting ABCC1 via miR‐363

Emerging evidence has validated the vital role of long non‐coding RNA (lncRNA) in the chemoresistance of cancer treatment. In the present study, we investigate the function of lncRNA NR2F1‐AS1 on oxaliplatin (OXA) resistance of hepatocellular carcinoma (HCC) and discover the underlying molecular mechanism. Results revealed that lncRNA NR2F1‐AS1 was up‐regulated in oxaliplatin‐resistant HCC tissue and cells using microarray analysis and RT‐PCR. Meanwhile, ABCC1 protein was overexpressed in OXA‐resistant HCC cells (Huh7/OXA and HepG2/OXA). In vitro, NR2F1‐AS1 knockdown reduced the invasion, migration, drug‐resistant gene (MDR1, MRP5, LRP1) and IC50 value in Huh7/OXA and HepG2/OXA cells. In vivo, NR2F1‐AS1 knockdown decreased the tumour weight of HCC cells. Bioinformatics tools and luciferase reporter assay confirmed miR‐363 targeted the 3′‐UTR of NR2F1‐AS1 and ABCC1 mRNA, presenting that NR2F1‐AS1 promoted ABCC1 expression through endogenous sponging miR‐363. In summary, results conclude that NR2F1‐AS1 regulates HCC OXA resistance through targeting miR‐363‐ABCC1 pathway, providing a vital theoretic mechanism and therapeutic target for HCC chemoresistance.     

lncRNA MIR4435‐2HG promoted clear cell renal cell carcinoma malignant progression via miR‐513a‐5p/KLF6 axis

Long non‐coding RNAs (lncRNAs) take various biological effects in clear cell renal cell carcinoma (ccRCC) mostly through sponging with microRNAs (miRNAs). lncRNA MIR4435‐2HG is found to promote tumour progression in gastric cancer, glioblastoma and hepatocellular carcinoma. However, the role of lncRNA MIR4435‐2HG in ccRCC progression remains unknown. The purpose of this research was to investigate the potential molecular mechanism of lncRNA MIR4435‐2HG regarding the regulation of ccRCC initiation and progression. In this study, we found the up‐regulation of MIR4435‐2HG in ccRCC tissues and cell lines. Functionally, overexpression of MIR4435‐2HG promoted the proliferation as well as the metastasis in ccRCC cell lines, whereas knockdown of MIR4435‐2HG inhibited the above changes. Then, bioinformatic analysis and luciferase reporter assays confirmed the negative regulation effect of MIR4435‐2HG on miR‐513a‐5p. And further investigations showed that KLF6, which collected from the intersection of databases, was the potential conjugated mRNAs of miR‐513a‐5p. Finally, the rescue experiments revealed the relation among MIR4435‐2HG and KLF6, which showed that KLF6 could reverse the promoting effect of MIR4435‐2HG on ccRCC in vitro and in vivo. Therefore, our findings provided insight into the mechanisms of MIR4435‐2HG in ccRCC and revealed an alternative target for the clinical diagnosis and treatment of ccRCC.     

The p53‐inducible long noncoding RNA TRINGS protects cancer cells from necrosis under glucose starvation

The tumor suppressor p53 is activated in response to cellular stress to prevent malignant transformation. However, several recent studies have shown that p53 can play protective roles in tumor cell survival under adversity. Whether p53‐regulated long noncoding RNAs are involved in this process remains to be fully understood. Here, we show that under glucose starvation condition, p53 directly upregulates a novel lncRNA named TRINGS (Tp53‐regulated inhibitor of necrosis under glucose starvation) in human tumor cells. TRINGS binds to STRAP and inhibits STRAP–GSK3β–NF‐κB necrotic signaling to protect tumor cells from cell death. Interestingly, TRINGS appears to respond to glucose starvation specifically, as it is not activated by serum, serine, or glutamine deprivation. Collectively, our findings reveal that p53‐induced lncRNA TRINGS controls the necrotic pathway and contributes to the survival of cancer cells harboring wild‐type p53 under glucose stress.     

β‐carotene suppresses Porphyromonas gingivalis lipopolysaccharide‐mediated cytokine production in THP‐1 monocytes cultured with high glucose condition

Periodontitis is associated with development of diabetes mellitus. Although lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg), a major pathogen of periodontitis, may lead the progression of diabetes complications, the precise mechanisms are unclear. We, therefore, investigated the effects of β‐carotene on production of Pg LPS‐induced inflammatory cytokines in human monocytes cultured high glucose (HG) condition. THP‐1 cells were cultured under 5.5 mM or 25 mM glucose conditions, and cells were stimulated with Pg LPS. To investigate the productivity of TNF‐α, IL‐6, and MCP‐1, cell supernatants were collected for ELISA. To examine the effects of NF‐kB signals on cytokine production, Bay11‐7082 was used. HG enhanced Pg LPS‐induced production of TNF‐α, IL‐6, and MCP‐1 via NF‐kB signals in THP‐1. β‐carotene suppressed the enhancement of the Pg LPS‐induced cytokine production in THP‐1 via NF‐κB inactivation. Our results suggest that β‐carotene might be a potential anti‐inflammatory nutrient for circulating Pg LPS‐mediated cytokine production in diabetic patients with periodontitis.     

SIRT1 reduction causes renal and retinal injury in diabetes through endothelin 1 and transforming growth factor β1

In diabetes, hyperglycaemia causes up‐regulation of endothelin 1 (ET‐1) and transforming growth factor beta 1 (TGF‐β1). Previously we showed glucose reduces sirtuin1 (SIRT1), a class III histone deacetylase. Here, we investigated the regulatory role of SIRT1 on ET‐1 and TGF‐β1 expression. Human microvascular endothelial cells were examined following incubation with 25 mmol/l glucose (HG) and 5 mmol/l glucose (NG) with or without SIRT1 or histone acetylase p300 overexpression or knockdown. mRNA expressions of ET‐1, TGF‐β1, SIRT1, p300 and collagen 1α(I) were examined. SIRT1 enzyme activity, ET‐1 and TGF‐β1 protein levels were measured. Histone acetylation and endothelial permeability were further investigated. Similar analyses were performed in the kidneys and retinas of SIRT1 overexpressing transgenic mice with or without streptozotocin induced diabetes. Renal functions were evaluated. In the endothelial cells (ECs), HG caused increased permeability and escalated production of ET‐1, TGF‐β1, collagen Iα(I). These cells also showed increased p300 expression, histone acetylation and reduced SIRT1 levels. These changes were rectified in the ECs following p300 silencing or by SIRT1 overexpression, whereas SIRT1 knockdown or p300 overexpression in NG mimicked the effects of HG. High ET‐1 and TGF‐β1 levels were seen in the kidneys and retinas of diabetic mice along with micro‐albuminuria and increased fibronectin protein (marker of glucose‐induced cell injury) levels. Interestingly, these detrimental changes were blunted in SIRT1 overexpressing transgenic mice with diabetes. This study showed a novel SIRT1 mediated protection against renal and retinal injury in diabetes, regulated through p300, ET‐1 and TGF‐β1.