High Glucose-induced Inflammatory Response Research Articles

MicroRNA-5010-5p ameliorates high-glucose induced inflammation in renal tubular epithelial cells by modulating the expression of PPP2R2D

IntroductionWe previously reported the significant upregulation of eight circulating exosomal microRNAs (miRNAs) in patients with diabetic kidney disease (DKD). However, their specific roles and molecular mechanisms in the kidney remain...

Lipoxin A4 prevents high glucose-induced inflammatory response in cardiac fibroblast through FOXO1 inhibition

Cardiac cells respond to various pathophysiological stimuli, synthesizing inflammatory molecules that allow tissue repair and proper functioning of the heart; however, perpetuation of the inflammatory response can lead to cardiac fibrosis and heart dysfunction. High concentration of glucose (HG) induces an inflammatory and fibrotic response in the heart. Cardiac fibroblasts (CFs) are resident cells of the heart that respond to deleterious stimuli, increasing the synthesis and secretion of both fibrotic and proinflammatory molecules. The molecular mechanisms that regulate inflammation in CFs are unknown, thus, it is important to find new targets that allow improving treatments for HG-induced cardiac dysfunction. NFκB is the master regulator of inflammation, while FoxO1 is a new participant in the inflammatory response, including inflammation induced by HG; however, its role in the inflammatory response of CFs is unknown. The inflammation resolution is essential for an effective tissue repair and recovery of the organ function. Lipoxin A4 (LXA4) is an anti-inflammatory agent with cytoprotective effects, while its cardioprotective effects have not been fully studied. Thus, in this study, we analyze the role of p65/NFκB, and FoxO1 in CFs inflammation induced by HG, evaluating the anti-inflammatory properties of LXA4. Our results demonstrated that HG induces the inflammatory response in CFs, using an in vitro and ex vivo model, while FoxO1 inhibition and silencing prevented HG effects. Additionally, LXA4 inhibited the activation of FoxO1 and p65/NFκB, and inflammation of CFs induced by HG. Therefore, our results suggest that FoxO1 and LXA4 could be novel drug targets for the treatment of HG-induced inflammatory and fibrotic disorders in the heart.

Curcumin protects PC12 cells from a high glucose-induced inflammatory response by regulating the miR-218-5p/TLR4 axis.

Background:Curcumin exerts a protective effect on diabetic encephalopathy (DN), It is known for its potent neuroprotective, anti-inflammatory, antioxidant, and anticancer properties. However, the underlying mechanisms of curcumin’s neuroprotective effects resulting from high glucose (HG)-induced injuries remain unknown. The purpose of this study is to identify the protective mechanism of Curcumin in the DN.Methods:In this study, pheochromocytoma cells (PC12 cells) were pretreated with different concentrations of Curcumin and then co-treated with Curcumin and glucose for 48 hours, and the cell viability was evaluated by CCK-8, the expression of the inflammatory mediators were detected by ELISA, the miR-218-5p and toll-like receptors (TLR4) level were examined by both quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, the potential target genes of miR-218-5p were identified using luciferase reporter assay.Results:The viability of PC12 cells treated with HG was significantly reduced in a dose- and time-dependent manner. Cotreatment of curcumin with HG significantly increased cell viability. Curcumin inhibited the expression of the inflammatory mediators, tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), and induced the expression of the anti-inflammatory mediator interleukin-10 (IL-10). Curcumin upregulated the levels of miR-218-5p and downregulated the expression of TLR4 in HG-treated PC12 cells. The curcumin-induced anti-inflammatory effect was abrogated by a miR-218-5p inhibitor and overexpression of TLR4. The results suggest that curcumin ameliorates the inflammatory response by upregulating miR-218-5p levels in PC12 cells.Conclusions:Our results indicate a protective role for curcumin in PC12 cells and suggest that it should be considered for the prophylactic treatment of DN in the future.

Grifola frondosa Polysaccharide Ameliorates Early Diabetic Nephropathy by Suppressing the TLR4/NF-κB Pathway.

Grifola frondosa is a medicinal macro-fungus with a wide range of biological activities. Polysaccharides from Grifola frondosa (PGF) play a positive role in regulating blood glucose and alleviating kidney injury. Here, we investigated the exact mechanism of action by which PGF ameliorates diabetic nephropathy. Our results showed that PGF effectively improved glucose tolerance and insulin sensitivity in streptozocin (STZ)-induced DN mice. Additionally, administration of PGF also ameliorated renal function and inflammatory response in STZ-induced DN mice. Consistent with the in vitro results, the high glucose-induced inflammatory response and apoptosis of renal tubular epithelial cells were decreased by PGF treatment. Furthermore, PGF not only suppressed the expression of TLR4, but also more effectively protected the kidney and reduced the inflammatory response when TLR4 was inhibited. All these data revealed that PGF alleviates diabetic nephropathy by blocking the TLR4/NF-κB pathway.

NLRP3 is a promising target for regulating high glucose-induced inflammatory response in Megalobrama amblycephala

The nucleotide-binding domain, leucine-rich repeat and pyrin domain containing protein 3 (NLRP3) has emerged as a key regulator of glucose homeostasis in mammals, while relevant information are still poorly interpreted in aquatic animals. Herein, we cloned and characterized NLRP3 gene from Megalobrama amblycephala, and analyzed its function in high glucose (HG)-induced inflammation. Full-length cDNA of NLRP3 measured 4380 bp with 3570 bp open reading frame encoding 1189 amino acids, compared with Pimephales promelas, it displayed 90.3% homology. Structural analysis revealed that M. amblycephala NLRP3 processed characteristic domains of pyrin, FISNA, NACHT, CARD and LRRs. Spatial expression analysis displayed NLRP3 was ubiquitously expressed in eight organs/tissues (gill, liver, spleen, intestine, head kidney, white muscle, heart and brain) with largest magnitude in head kidney. After a 13-week nutritional experiment, carbohydrate-enriched (45%) diets significantly upregulated NLRP3 mRNA levels in the liver and white muscle than that of the control (30%) diets. Glucose loading caused a significantly increased NLRP3 mRNA levels in the white muscle and liver, with maximum values got at 1 and 2 h, respectively. Subsequently, the mRNA levels rapidly returned to the basal level at 12 h. As for the in-vitro experiments, both ATP and high-glucose treatments remarkably increased the expression of NLRP3 and pro-inflammatory cytokines (IL1β and IL6) in hepatocytes. Additionally, high-leucine (30 mM) levels remarkably increased NLRP3 protein content and transcriptions of NLRP3, NF-κB, IL1β and IL6 than those of the HG and HG + low leucine (10 mM) treatment groups, while the opposite was true for IL8 and IL10. Overall, our findings indicated that M. amblycephala NLRP3 is highly conserved compared with other vertebrates. NLRP3 participated in the control of HG-induced inflammation, and high-leucine levels could aggravate HG-induced inflammation in hepatocytes of M. amblycephala via NLRP3 activation.

Molecular characterization of thioredoxin-interacting protein (TXNIP) from Megalobrama amblycephala and its potential roles in high glucose-induced inflammatory response

This study aimed to characterize the full-length cDNA of thioredoxin-interacting protein (TXNIP) from Megalobrama amblycephala, and investigate its roles in high glucose (HC)-induced inflammatory response. The cDNA obtained covered 2706-bp with an open reading frame of 1203-bp encoding 400 amino acids, compared to Cyprinus carpio, it showed 89.96% homology. The highest expression of txnip was observed in head kidney followed by spleen and liver. After a 12-week feeding trial, high-carbohydrate diet remarkably increased txnip expression in liver and white muscle. Glucose administration resulted in a remarkably increased liver txnip expression, which peaked at 1 h. Thereafter, the expression decreased remarkably to the basal value at 12 h. However, insulin injection resulted in a significant decrease in txnip expression with minimum values attained at 2 h. Subsequently, it gradually increased to the normal values. Moreover, in the in-vitro study, over-expression of txnip along with remarkably increased il-1β and il-6 expression in hepatocytes, and its knockdown led to remarkably reduced il-1β expression. Furthermore, metformin treatment remarkably increased the cell viability and trx expression of hepatocytes under high glucose, while the opposite was true for ROS levels, LDH activity, the ALT/AST ratio, Txnip protein content and the transcriptions of txnip, tnfα and il-1β.

Protective mechanisms of Taiwanese green propolis toward high glucose-induced inflammation via NLRP3 inflammasome signaling pathway in human gingival fibroblasts.

To investigate protective effects of Taiwanese green propolis (TGP) against high glucose-induced inflammatory responses in human gingival fibroblasts (HGFs) through NLRP3 inflammasome signaling pathway. NLRP3 inflammasome has been implicated in the progression of both diabetes mellitus and periodontitis, suggesting a common potential therapeutic target for these diseases. Propolis is renowned for various biological activities, particularly anti-inflammation and antioxidant, representing a promising therapy for many conditions. However, underlying mechanisms remain unclear. The cytotoxicity of TGP was evaluated by cell viability assay. The mRNA levels and protein expression or secretion of various inflammatory molecules and NLRP3 inflammasome-related molecules in high glucose-exposed HGFs with or without pretreatment of TGP (5μg/ml) were determined by real-time PCR and western blot or specific kits, respectively. Intracellular and mitochondrial ROS measurements, NADPH oxidase activity determination, and subcellular fractions were performed to assess ROS generation. The transcriptional activity of NF-κB was measured by luciferase reporter kit. The signaling components were further differentiated using pharmacological inhibitors of ROS and small interfering RNAs of TLR2, TLR4, or NF-κB. High glucose could induce IL-1β-driven inflammatory responses in HGFs via the activation of NLRP3 inflammasome regulated by TLR2/TLR4 coupled ROS in NF-κB-dependent manner. TGP had no adverse impact on the cell viability of HGFs at concentrations no greater than 10μg/ml, and could exert inhibitory effects on high glucose-induced inflammatory responses via the interruption of NLRP3 inflammasome signaling pathway. Taiwanese green propolis could elicit protective effects against IL-1β-driven inflammation in high glucose-exposed HGFs through TLR2/TLR4 combined ROS/NF-κB/NLRP3 inflammasome pathway.

Wnt5a promotes renal tubular inflammation in diabetic nephropathy by binding to CD146 through noncanonical Wnt signaling

Immune and inflammatory factors have emerged as key pathophysiological mechanisms in the progression of diabetic renal injury. Noncanonical Wnt5a signaling plays an essential role in obesity- or diabetes-induced metabolic dysfunction and inflammation, but its explicit molecular mechanisms and biological function in diabetic nephropathy (DN) remain unknown. In this study, we found that the expression of Wnt5a and CD146 in the kidney and the level of soluble form of CD146 (sCD146) in serum and urine samples were upregulated in DN patients compared to controls, and this alteration was correlated with the inflammatory process and progression of renal impairment. Blocking the activation of Wnt5a signaling with the Wnt5a antagonist Box5 prevented JNK phosphorylation and high glucose-induced inflammatory responses in db/db mice and high glucose-treated HK-2 cells. Similar effects were observed by silencing Wnt5a with small-interfering RNA (siRNA) in cultured HK-2 cells. Knockdown of CD146 blocked Wnt5a-induced expression of proinflammatory cytokines and activation of JNK, which suggests that CD146 is essential for the activation of the Wnt5a pathway. Finally, we confirmed that Wnt5a directly interacted with CD146 to activate noncanonical Wnt signaling in HK-2 cells. Taken together, our findings suggest that by directly binding to CD146, Wnt5a-induced noncanonical signaling is a contributing mechanism for renal tubular inflammation in diabetic nephropathy. The concentration of sCD146 in serum and urine could be a potential biomarker to predict renal outcomes in DN patients.

LncRNA H19 inhibits high glucose-induced inflammatory responses of human retinal epithelial cells by targeting miR-19b to increase SIRT1 expression.

Diabetic retinopathy (DR) is a common complication of diabetes mellitus. Inflammatory responses play crucial roles in the progress of DR. Long noncoding RNA (lncRNAs) and microRNAs (miRNAs) are key signal transduction molecules in retina, and tightly connected with DR occurrence and development. Our study aimed to explore the functions of lncRNA H19, miR-19b and silence information regulator factor related enzymes 1 (SIRT1) in the progress of DR. Retinal pigment epithelial cells (ARPE-19) were used to build high-glucose (HG) model. Quantitative real-time PCR (qPCR) was performed to detect expression of H19, miR-19b and SIRT1 at normal glucose (NG) and HG conditions. And western blotting was performed to test protein level of SIRT1. QPCR and enzyme-linked immunosorbent assay were performed to detect expression of inflammatory cytokines. Finally, the interactions among H19, miR-19b and SIRT1 were determined by dual-luciferase reporter assay. Our results showed that lncRNA H19 and SIRT1 were reduced, while miR-19b was increased in ARPE-19 cells with HG condition. MiR-19b positively regulated the expression of inflammatory cytokines, including TNF-α, IL-1β and IL-6. Inhibition of miR-19b and overexpression of H19 inhibited the expression of inflammatory cytokines, such as TNF-α, IL-1β and IL-6, while knockdown of SIRT1 reversed their effects on inflammatory cytokines. Furthermore, overexpression of miR-19b reversed the inhibitory effects of overexpression of H19 on inflammatory cytokines. Importantly, H19 targeted miR-19b to downregulate miR-19b expression. Furthermore, miR-19b bound to SIRT1 and declined SIRT1 expression. H19/miR-19b/SIRT1 axis plays a key role of HG-induced inflammatory response in ARPE-19 cells, which provides new targets for DR treatment.

Human mesenchymal stromal cells broadly modulate high glucose-induced inflammatory responses of renal proximal tubular cell monolayers

BackgroundRenal proximal tubular epithelial cells (RPTEC) are dysfunctional in diabetic kidney disease (DKD). Mesenchymal stromal cells (MSC) may modulate DKD pathogenesis through anti-inflammatory mediators. This study aimed to investigate the pro-inflammatory effect of extended exposure to high glucose (HG) concentration on stable RPTEC monolayers and the influence of MSC on this response.MethodsMorphologically stable human RPTEC/TERT1 cell monolayers were exposed to 5 mM and 30 mM (HG) D-glucose or to 5 mM D-glucose + 25 mM D-mannitol (MAN) for 5 days with sequential immunoassays of supernatants and end-point transcriptomic analysis by RNA sequencing. Under the same conditions, MSC-conditioned media (MSC-CM) or MSC-containing transwells were added for days 4–5. Effects of CM from HG- and MAN-exposed RPTEC/MSC co-cultures on cytokine secretion by monocyte-derived macrophages were determined.ResultsAfter 72–80 h, HG resulted in increased RPTEC/TERT1 release of interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1 and neutrophil gelatinase-associated lipocalin (NGAL). The HG pro-inflammatory effect was attenuated by concentrated (10×) MSC-CM and, to a greater extent, by MSC transwell co-culture. Bioinformatics analysis of RNA sequencing data confirmed a predominant effect of HG on inflammation-related mediators and biological processes/KEGG pathways in RPTEC/TERT1 stable monolayers as well as the non-contact-dependent anti-inflammatory effect of MSC. Finally, CM from HG-exposed RPTEC/MSC transwell co-cultures was associated with attenuated secretion of inflammatory mediators by macrophages compared to CM from HG-stimulated RPTEC alone.ConclusionsStable RPTEC monolayers demonstrate delayed pro-inflammatory response to HG that is attenuated by close proximity to human MSC. In DKD, this MSC effect has potential to modulate hyperglycemia-associated RPTEC/macrophage cross-talk.

Rapamycin Attenuates High Glucose-Induced Inflammation Through Modulation of mTOR/NF-κB Pathways in Macrophages.

Background: The NLRP3 inflammasome is one of the key contributors to impaired wound healing in diabetes. In this study, we assessed the role of rapamycin on high glucose-induced inflammation in THP-1-derived macrophages and investigated the underlying signaling mechanisms.Methods: THP-1-derived macrophages were treated with high glucose to induce NLRP3 inflammasome activation. The cells were pretreated with rapamycin, BAY 11-7082, or PDTC before exposure to HG. mTOR, NF-κB, and NLRP3 inflammasome expression were measured by western blotting.Results: We found that rapamycin reduced NLRP3 inflammasome activation in macrophages. Rapamycin reduced NLRP3 inflammasome activation by inhibiting mTOR phosphorylation and NF-κB activation. Moreover, mTOR siRNA inhibited NF-κB activation, leading to the suppression of NLRP3 inflammasome activation.Conclusion: Rapamycin can ameliorate high glucose-induced NLRP3 inflammasome activation by attenuating the mTOR/NF-κB signaling pathway in macrophages. Rapamycin may act as a possible therapeutic option for high glucose-induced inflammatory response in impaired wound healing in the future.

LncRNA MALAT1 promotes high glucose-induced inflammatory response of microglial cells via provoking MyD88/IRAK1/TRAF6 signaling

Although a large number of studies have confirmed from multiple levels that diabetes mellitus (DM) promotes cerebral ischemic reperfusion (I/R) injury, but the precise mechanism is still unclear. A cerebral I/R injury model in diabetic rats was established. The neurological deficit scores and brain edema were monitored at 24 and 72 hours after injury. The peri-infarct cortical tissues of rats were isolated for molecular biology detection. The rat primary microglia and microglia line HAPI were cultured to establish the cell model of DM-I/R by high glucose (HG) and hypoxia-reoxygenation (H/R). The endogenous expression of MALAT1 and MyD88 was regulated by the transfection with pcDNA-MALAT1, si-MALAT1 and si-MyD88, respectively. The cerebral I/R injury model in diabetic rats had more severe neuronal injury as shown by the significantly higher neurological deficit scores and an obvious increasing brain edema at 24 and 72 hours after injury. Moreover, the microglia were activated and induced a large number of inflammatory cytokines TNF-α, IL-1β and IL-6 in the peri-infarct cortical tissues during cerebral I/R injury associated with DM. The expression of MALAT1, MyD88, IRAK1 and TRAF6 protein were significantly up-regulated by DM-I/R in vitro and in vivo. Furthermore, the HG-H/R-induced MALAT1 promoted the inflammatory response in microglia via MyD88/IRAK1/TRAF6 signaling. Our results suggested that MALAT1 mediated the exacerbation of cerebral I/R injury induced by DM through triggering the inflammatory response in microglia via MyD88 signaling.

Attenuation of inflammatory response by a novel chalcone protects kidney and heart from hyperglycemia-induced injuries in type 1 diabetic mice

High glucose-induced inflammatory response in diabetic complications plays an important role in disease occurrence and development. With inflammatory cytokines and signaling pathways as important mediators, targeting inflammation may be a new avenue for treating diabetic complications. Chalcones are a class of natural products with various pharmacological activities. Previously, we identified L2H17 as a chalcone with good anti-inflammatory activity, inhibiting LPS-induced inflammatory response in macrophages. In this study, we examined L2H17's effect on hyperglycemia-induced inflammation both in mouse peritoneal macrophages and a streptozotocin-induced T1D mouse model. Our results indicate that L2H17 exhibits a strong inhibitory effect on the expression of pro-inflammatory cytokines, cell adhesion molecules, chemokines and macrophage adhesion via modulation of the MAPK/NF-κB pathway. Furthermore, in vivo oral administration of L2H17 resulted in a significant decrease in the expression of pro-inflammatory cytokines and cell adhesion molecules, contributing to a reduction of key markers for renal and cardiac dysfunction and improvements in fibrosis and pathological changes in both renal and cardiac tissues of diabetic mice. These findings provide the evidence supporting targeting MAPK/NF-κB pathway may be effective therapeutic strategy for diabetic complications, and suggest that L2H17 may be a promising anti-inflammatory agent with potential as a therapeutic agent in the treatment of renal and cardiac diabetic complications.

Inhibition of autophagy induces IL-1β release from ARPE-19 cells via ROS mediated NLRP3 inflammasome activation under high glucose stress

Autophagy plays an important role in the development of diabetic retinopathy (DR). Retinal pigment epithelial (RPE) cells are the main cells involved in DR, a process in which hyperglycemia plays a crucial role. This study was conducted to investigate the protective effect of autophagy against high glucose-induced inflammatory response in ARPE-19 cells and its underlying mechanism. In the present study we subjected ARPE-19 cells to high glucose stress and showed that ARPE-19 cells respond to high glucose with an increase in autophagy. 3-methyladenine (3-MA) inhibited occurrence of autophagy and it leaded to the accumulation of damaged-mitochondria-producing-ROS, and the activation of NLRP3 inflammasome, and subsequently, caused IL-1β secretion.

SIRT1 is a regulator in high glucose-induced inflammatory response in RAW264.7 cells.

Sepsis is defined as a systemic inflammatory response syndrome that disorders the functions of host immune system, including the imbalance between pro- and anti-inflammatory responses mediated by immune macrophages. Sepsis could also induce acute hyperglycemia. Studies have shown that the silent mating type information regulation 2 homolog 1 (SIRT1), an NAD+-dependent deacetylase, mediates NF-κb deacetylation and inhibits its function. Therefore, SIRT1 is likely to play an important role in high glucose-mediated inflammatory signalings. Here we demonstrate that high glucose significantly downregulates both the mRNA and protein levels of SIRT1 and upregulates the mRNA level and the release of two pro-inflammatory cytokines, IL-1β and TNF-α, in RAW264.7 macrophages. Interestingly, the reduced level of SIRT1 by high glucose is remarkably upregulated by SIRT1 activator SRT1720, while the level and the release of IL-1β and TNF-α significantly decrease with the use of SRT1720. However, when the function of SIRT1 is inhibited by EX527 or its expression is suppressed by RNAi, the upregulated level and release of IL-1β and TNF-α by high glucose are further increased. Taken together, these findings collectively suggest that SIRT1 is an important regulator in many high glucose-related inflammatory diseases such as sepsis.