Inflammation-induced Insulin Resistance Research Articles

The Complex Immunological Alterations in Patients with Type 2 Diabetes Mellitus on Hemodialysis

It is widely known that diabetes mellitus negatively impacts both the innate immunity (the inflammatory response) and the acquired immunity (the humoral and cellular immune responses). Many patients with diabetes go on to develop chronic kidney disease, which will necessitate hemodialysis. In turn, long-term chronic hemodialysis generates an additional chronic inflammatory response and impairs acquired immunity. The purpose of this paper is to outline and compare the mechanisms that are the basis of the constant aggression towards self-components that affects patients with diabetes on hemodialysis, in order to find possible new therapeutic ways to improve the functionality of the immune system. Our study will take a detailed look at the mechanisms of endothelial alteration in diabetes and hemodialysis, at the mechanisms of inflammatory generation and signaling at different levels and also at the mechanisms of inflammation-induced insulin resistance. It will also discuss the alterations in leukocyte chemotaxis, antigen recognition and the dysfunctionalities in neutrophils and macrophages. Regarding acquired immunity, we will outline the behavioral alterations of T and B lymphocytes induced by diabetes mellitus and chronic hemodialysis.

Anti-Inflammatory and Anti-Adipocyte Dysfunction Effects of Ficus lindsayana Latex and Root Extracts.

Low-grade chronic inflammation and adipocyte dysfunction are prominent risk factors of insulin resistance and type 2 diabetes mellitus (T2DM) in obesity. Thus, prevention of inflammation and adipocyte dysfunction could be one possible approach to mitigate T2DM development. Several Ficus species have been used in traditional medicine for ameliorating inflammation and T2DM. Our previous studies reported biological effects of Ficus lindsayana including antioxidant, anti-cancer, and anti-α-glucosidase activities. Further, this study therefore investigated whether F. lindsayana latex (FLLE) and root (FLRE) extracts inhibit inflammation-stimulated insulin resistance in adipocytes and inflammation in macrophages. FLLE and FLRE (200 µg/mL) had no significant cytotoxicity for macrophages, adipocytes, and blood cells (PBMCs and RBCs). FLRE had a total flavonoid content about three times higher than FLLE, while both had similar levels of total phenolic content. FLRE showed higher abilities than FLLE in suppressing inflammation in both macrophages and adipocytes and reversing the inflammation-induced insulin resistance in adipocytes. In TNF-α-induced adipocytes, FLRE significantly improved insulin-induced glucose uptake and insulin-suppressed lipolysis, while FLLE only significantly improved glucose uptake. Moreover, FLRE and FLLE remarkably reduced chemoattractant (MCP-1) but improved adipogenic (PPARγ and CEBPα) gene expression, leading to the promotion of adipogenesis and the suppression of insulin resistance. In LPS-induced macrophages, FLRE, but not FLLE, significantly inhibited LPS-induced NO production. Moreover, FLRE significantly reduced LPS-stimulated iNOS, COX-2, IL-1β, IL-6, and TNF-α gene expression. These results may provide the potential data for the development of this plant, especially the root part, as an alternative medicine, functional ingredient, or food supplement for the prevention of inflammation and obesity-associated insulin resistance, as well as T2DM.

Modeling and therapeutic targeting of inflammation-induced hepatic insulin resistance using human iPSC-derived hepatocytes and macrophages

Hepatic insulin resistance is recognized as a driver of type 2 diabetes and fatty liver disease but specific therapies are lacking. Here we explore the potential of human induced pluripotent stem cells (iPSCs) for modeling hepatic insulin resistance in vitro, with a focus on resolving the controversy about the impact of inflammation in the absence of steatosis. For this, we establish the complex insulin signaling cascade and the multiple inter-dependent functions constituting hepatic glucose metabolism in iPSC-derived hepatocytes (iPSC-Heps). Co-culture of these insulin-sensitive iPSC-Heps with isogenic iPSC-derived pro-inflammatory macrophages induces glucose output by preventing insulin from inhibiting gluconeogenesis and glycogenolysis and activating glycolysis. Screening identifies TNFα and IL1β as the mediators of insulin resistance in iPSC-Heps. Neutralizing these cytokines together restores insulin sensitivity in iPSC-Heps more effectively than individual inhibition, reflecting specific effects on insulin signaling and glucose metabolism mediated by NF-κB or JNK. These results show that inflammation is sufficient to induce hepatic insulin resistance and establish a human iPSC-based in vitro model to mechanistically dissect and therapeutically target this metabolic disease driver.

1538-P: Brain TGFß Regulates Glucose Tolerance in Male Mice with Metabolic Syndrome

Hypothalamic inflammation contributes to insulin resistance and obesity. Transforming growth factor beta (TGFβ) is among the inflammatory mediators inducing hypothalamic inflammation. In this study, we investigated the role of brain TGFβ on metabolic function. We hypothesized that TGFβ in the brain promotes insulin resistance and reduces glucose tolerance in diabetic and obese mice. C57BL/J male mice were fed either hypercaloric diet (HCD, 52% fat) or regular diet (RD) from weaning. At 3 months age, intraperitoneal glucose tolerance test (GTT), insulin tolerance test (ITT) and weight confirmed the acquisition of metabolic syndrome. Hypothalamic protein expression was assessed for TGFβ receptor 2, phosphorylated SMAD3, SMAD6 and SMAD7, as downstream signal transducer proteins for TGFβ. Compared to RD male mice (n=6), mice on HCD (n=6) showed glucose intolerance (AUC; 60587 ±2460 vs. 30802±1923, p<0.0001), insulin intolerance (AUC; Mean±SEM; 19025836.0 vs.11436±1087, p=0.02) and weight gain (33.67±2.028 vs. 26.89±0.4231 g). HCD mice also exhibited increased protein levels of TGFβR2 (normalized to total protein, Fold Change (FC)±SEM to RD group; 3.54±0.3, p<0.0001), pSMAD3 (FC 2±0.5, p=0.04) while inhibitors for TGFβ signaling such as SMAD6 and SMAD7, were downregulated (FC 0.7±0.1, p=0.03 and 0.8±0.04, p=0.03, respectively). To understand the role of brain TGFβ on metabolic regulation, 3 months HCD mice were subjected to intracerebroventricular (ICV) infusion with either TGFβ neutralizing antibody (nAb, n=4) or IgG control antibody (n=4) using subcutaneous osmotic pumps connected to ICV cannula for 2 weeks. GTT was measured after 2-week infusion. Treatment with TGFβ nAb resulted in lower fasting blood glucose compared to before treatment (166.1 ±6.878 vs. 229.9 ±3.923 mg/dL) and at 120 min time point (229.9 ±28.69 vs. 382.2 ±24.33 mg/dL). In conclusion, brain TGFβ plays a key role in regulating glucose metabolism probably through inflammation-induced insulin resistance. Disclosure M.Elgazzaz: None. K.Miao: None. A.R.Nuzzo: None. L.Restivo: None. K.Moles: None. E.D.Lazartigues: None. Funding American Diabetes Association (1-19-IBS-291 to E.D.L.)

Liraglutide and Exercise Synergistically Attenuate Vascular Inflammation and Enhance Metabolic Insulin Action in Early Diet-Induced Obesity.

Inflammation-induced vascular insulin resistance occurs early in diet-induced obesity and contributes to metabolic insulin resistance. We examined whether exercise and GLP-1 receptor agonism, alone or in combination, modulate vascular and metabolic insulin actions during obesity development. We found that exercise and liraglutide synergistically enhanced the metabolic actions of insulin and reduced perimicrovascular macrophage accumulation, vascular oxidative stress, and inflammation in the early stage of obesity development. Our data suggest that early combination use of exercise and a GLP-1 receptor agonist might be an effective strategy in preventing vascular and metabolic insulin resistance and associated complications during the development of obesity.

The Mechanisms of Neochlorogenic Acid (3-Caffeoylquinic Acid) in Improving glucose and Lipid Metabolism in Rats with Insulin Resistance Induced by A High Fat-High Fructose Diet

This study investigated the effects and the mechanism of actions of neochlorogenic acid (3-caffeoylquinic acid; 3-CQA) on glucose and lipid metabolism in rats fed a high fat-high fructose diet (HFFD). Male rats were fed HFFD (40 % lard and 20 % fructose) for 16 weeks. At the 10th week, the HFFD rats were split into 3 groups: HFFD receiving distilled water (HFFD control group), HFFD receiving 3-CQA 50 mg/kg and HFFD receiving metformin 200 mg/kg once daily for a further 6 weeks. At the end of treatment, fasting blood glucose (FBG), oral glucose-tolerance test (OGTT), lipid profile, insulin, leptin, adiponectin, markers of oxidative stress, and hepatic triglyceride content were measured. Liver, adipose tissue, and skeletal muscle were collected for histological, gene and protein examinations. Compared to the HFFD control group, the 3-CQA group exhibited significantly reduced FBG, insulin and leptin levels, and improved OGTT. Serum adiponectin increased and lipid profiles were normalized. Hepatic triglyceride was reduced with a decrease in lipid droplets in liver histological sections. Levels of serum SOD and CAT activity, and MDA were reversed by 3-CQA treatment. Moreover, 3-CQA significantly reduced the expression of adipocyte pro-inflammatory cytokine genes (MCP-1, TNF-α, and IL-6), hepatic lipogenic genes (SREBP1c, FAS, and GPAT), and hepatic gluconeogenic genes (PEPCK and G6Pase). Additionally, 3-CQA increased expression of muscle GLUT4 gene, and of GLUT4 protein with increased p-AKT and p-AMPK in skeletal muscle. In conclusion, 3-CQA improves glucose and lipid metabolism plausibly by decreasing oxidative stress and inflammation-induced insulin resistance, downregulating the expression of lipogenic and gluconeogenic genes, and enhancing insulin signaling in HFFD-induced insulin-resistant rats. HIGHLIGHTS Neochlorogenic acid (3-CQA) improves glucose and lipid metabolism by decreasing insulin resistance Neochlorogenic acid (3-CQA) deceases insulin resistance due to its activities in ameliorating obesity, oxidative stress, and adipose tissue inflammation The beneficial effects of Neochlorogenic acid (3-CQA) to improve glucose and lipid homeostasis may be mediated via suppression of hepatic glucose production and lipogenesis, and activation of muscle glucose uptake and AKT and AMPK pathways GRAPHICAL ABSTRACT

Taxoids-rich extract from Taxus wallichiana alleviates high-fat diet-induced insulin resistance in C57BL/6 mice through inhibition of low-grade inflammation.

The needle powder of Taxus wallichiana is in use for the management of diabetes and inflammation-related complications in the Indian and Chinese Systems of Traditional Medicine but the lack of proper pharmacological intervention has prompted us to investigate the pharmacological mechanism against inflammation-induced insulin resistance in high-fat diet-fed C57BL/6 mice. Hexane (Tw-H), chloroform (Tw-C), and ethyl acetate (Tw-EA) extracts were prepared from a needle of T. wallichiana and its effect on glucose uptake against TNF-α-induced insulin resistance in skeletal muscle cells was studied. Among all, Tw-EA extract has shown promising glucose uptake potential. Tw-EA treatment is also able to decrease the lipid accumulation in adipocytes. Chemical signature of Tw-EA using HPLC showed the presence of taxoids. Efficacy of taxoids-rich extract from T. wallichiana (Tw-EA) was further validated in in vivo system against high-fat diet (HFD)-induced insulin resistance in C57BL/6 mice. Oral treatment ofTw-EA showed significant reduction in blood glucose, pro-inflammatory cytokine production and body weight gain when compared with vehicle-treated HFD-induced insulin resistance in C57BL/6 mice. Histopathology and immunohistochemistry study in skeletal muscle and adipose tissue revealed that oral treatment of Tw-EA is able to reduce the infiltration of inflammatory cells in skeletal muscles, ameliorate the hypertrophy in adipose tissue and upregulate the GLUT4 protein expression. Treatment with Tw-EAsignificantly up-regulated mRNA expression of insulin signaling pathway (IRS-1, PI3K, AKT, GLUT 4). This study suggested the beneficial effect of taxoids-rich extract fromTaxus wallichianaagainst the inflammation-associated insulin resistance condition.

Current progress in the hypoglycemic mechanisms of natural polysaccharides.

Unhealthy dietary pattern-induced type 2 diabetes mellitus poses a great threat to human health all over the world. Accumulating evidence has revealed that the pathophysiology of type 2 diabetes mellitus is closely associated with the dysregulation of glucose metabolism and energy metabolism, serious oxidative stress, prolonged endoplasmic reticulum stress, metabolic inflammation and intestinal microbial dysbiosis. Most important of all, insulin resistance and insulin deficiency are two key factors inducing type 2 diabetes mellitus. Nowadays, natural polysaccharides have gained increasing attention owing to their numerous health-promoting functions, such as hypoglycemic, energy-regulating, antioxidant, anti-inflammatory and prebiotic activities. Therefore, natural polysaccharides have been used to alleviate diet-induced type 2 diabetes mellitus. Specifically, this review comprehensively summarizes the underlying hypoglycemic mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates hypoglycemic mechanisms of natural polysaccharides from the perspectives of their regulatory effects on glucose metabolism, insulin resistance and mitochondrial dysfunction.

Dectin-1 as a Potential Inflammatory Biomarker for Metabolic Inflammation in Adipose Tissue of Individuals with Obesity.

In obesity, macrophage activation and infiltration in adipose tissue (AT) underlie chronic low-grade inflammation-induced insulin resistance. Although dectin-1 is primarily a pathogen recognition receptor and innate immune response modulator, its role in metabolic syndromes remains to be clarified. This study aimed to investigate the dectin-1 gene expression in subcutaneous AT in the context of obesity and associated inflammatory markers. Subcutaneous AT biopsies were collected from 59 nondiabetic (lean/overweight/obese) individuals. AT gene expression levels of dectin-1 and inflammatory markers were determined via real-time reverse transcriptase-quantitative polymerase chain reaction. Dectin-1 protein expression was assessed using immunohistochemistry. Plasma lipid profiles were measured by ELISA. AT dectin-1 transcripts and proteins were significantly elevated in obese as compared to lean individuals. AT dectin-1 transcripts correlated positively with body mass index and fat percentage (r ≥ 0.340, p ≤ 0.017). AT dectin-1 RNA levels correlated positively with clinical parameters, including plasma C-reactive protein and CCL5/RANTES, but negatively with that of adiponectin. The expression of dectin-1 transcripts was associated with that of various proinflammatory cytokines, chemokines, and their cognate receptors (r ≥ 0.300, p ≤ 0.05), but not with anti-inflammatory markers. Dectin-1 and members of the TLR signaling cascade were found to be significantly associated, suggesting an interplay between the two pathways. Dectin-1 expression was correlated with monocyte/macrophage markers, including CD16, CD68, CD86, and CD163, suggesting its monocytes/macrophage association in an adipose inflammatory microenvironment. Dectin-1 expression was independently predicted by CCR5, CCL20, TLR2, and MyD88. In conclusion, dectin-1 may be regarded as an AT biomarker of metabolic inflammation in obesity.

Variable frequencies of peripheral T-lymphocyte subsets in the diabetes spectrum from type 1 diabetes through latent autoimmune diabetes in adults (LADA) to type 2 diabetes.

T lymphocytes are key players in the pathogenesis of autoimmune diabetes. We recruited subjects with T1D (n=81), LADA (n=82), T2D (n=95) and NGT (n=218) and analyzed the percentages of T-lymphocyte subsets, including T helper 1 (Th1), T helper 2 (Th2), T helper 17 (Th17), T cytotoxic 1 (Tc1), regulatory T cells (Tregs), effector T (Teff), naïve T, central memory T (Tcm), and effector memory T (Tem) cells by flow cytometry. LADA patients possessed similar frequencies of IFN-γ+CD4+ T (Th1), IFN-γ+CD8+ T and CD4+ Teff cells compared with T1D patients, but much lower than those of NGT subjects. Like T2D patients, LADA patients had increased frequencies of CD4+ Tem and CD8+ Tem cells with respect to T1D and NGT subjects. In LADA patients, Th2 cells were decreased while CD4+ Tcm cells were increased compared with NGT subjects. Notably, we observed significant negative correlations between the CD4+ Tcm cell frequency and C-peptide in LADA subjects. These data demonstrates that LADA patients possess T-cell subset changes resembling both T1D and T2D and represent the middle of the diabetes spectrum between T1D and T2D. Based on these T-cell subset alterations, we speculate that autoimmunity-induced β-cell destruction and inflammation-induced insulin resistance might both be involved in the pathogenesis of LADA.

Solubilization of luteolin in PVP40 solid dispersion improves inflammation-induced insulin resistance in mice

Our previous studies have confirmed that luteolin (LU) has a good therapeutic effect on obesity and its complications. However, due to its poor water solubility, the bioavailability is low with limited clinical application. Therefore, the water-soluble solid dispersions (SD) of luteolin were prepared with polyvinylpyrrolidone (PVP) (K10, K40 & K90) by solvent evaporation. The polyvinylpyrrolidone K40 (PVP40) was selected as the ideal carrier to formulate polyvinylpyrrolidone K40-luteolin solid dispersion (PVP40-LU SD), thereby the solubility of luteolin increased about 250 times compared to the pure luteolin, without changing its physical stability and activity. The crystallinity of luteolin was reduced after the formation of solid dispersion, and no strong drug-polymer interactions were observed. This prepared water-soluble luteolin inhibits the polarization of inflammatory macrophages by decreasing the expression of pro-inflammatory cytokine genes interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in vitro. Moreover, it can improve glucose tolerance and insulin sensitivity quickly after intraperitoneal injection in mice.

Dihydromyricetin Ameliorates Inflammation-Induced Insulin Resistance via Phospholipase C-CaMKK-AMPK Signal Pathway.

Patients with metabolic syndrome have a higher risk of type II diabetes and cardiovascular disease. The metabolic syndrome has become an urgent public health problem. Insulin resistance is the common pathophysiological basis of metabolic syndrome. The higher incidence of insulin resistance in obese groups is due to increased levels of inflammatory factors during obesity. Therefore, developing a therapeutic strategy for insulin resistance has great significance for the treatment of the metabolic syndrome. Dihydromyricetin, as a bioactive polyphenol, has been used for anti-inflammatory, antitumor, and improving insulin sensitivity. However, the target of DHM and molecular mechanism of DHM for preventing inflammation-induced insulin resistance is still unclear. In this study, we first confirmed the role of dihydromyricetin in inflammation-induced insulin resistance in vivo and in vitro. Then, we demonstrated that dihydromyricetin resisted inflammation-induced insulin resistance by activating Ca2+-CaMKK-AMPK using signal pathway blockers, Ca2+ probes, and immunofluorescence. Finally, we clarified that dihydromyricetin activated Ca2+-CaMKK-AMPK signaling pathway by interacting with the phospholipase C (PLC), its target protein, using drug affinity responsive target stability (DARTS) assay. Our results not only demonstrated that dihydromyricetin resisted inflammation-induced insulin resistance via the PLC-CaMKK-AMPK signal pathway but also discovered that the target protein of dihydromyricetin is the PLC. Our results provided experimental data for the development of dihydromyricetin as a functional food and new therapeutic strategies for treating or preventing PLC.

Effects of Exercise, Metformin, Pioglitazone and Exenatide Treatment on Inflammation Induced Insulin Resistance and Ubiquitin Proteasome System in Diabetes and Obesity

Purpose: The aim of this study is; To examine the destruction of insulin receptor substrate-1 (IRS-1) molecule, which is one of the mechanisms that cause insulin resistance in diabetes and obesity, and its effect to reduce this destruction. For this purpose, the effects of exercise, metformin, exenatide and pioglitazone treatments on IRS-1 ubiquitination in pancreas, muscle and adipose tissue were investigated in an obese and diabetic animal model.Method: Obese rat model was used in this study. This model is characterised by obesity, diabetes and insulin resistance. This study investigated the molecular mechanisms of IRS-1 breakdown in diabetes. IRS1, SOCS1, SOC3 expressions were evaluated in the liver, muscle and adipose tissue of this model. At the same time, immunohistochemical analyses were performed in terms of IRS1, SOCS1 and SOCS3 in the same tissues.Results: Gene expression and Immunohistochemical analysis results were evaluated, the increase in IRS1 was noticeable in rats treated with exenatide, especially in the liver tissue despite the greater decrease in SOCS1 (P> 0.05). It was determined that other drugs in this study and used in the treatment of diabetes may also affect this mechanism to different degrees.Conclusion: Our findings showed that some drugs used in the treatment of diabetes may alter the SOCS effect and / or proteasomal degradation of the IRS-1 protein. This effect was particularly pronounced in liver tissue. However, more comprehensive studies are required to show the contribution of ubiquitination in the destruction of IRS-1 and which drugs are effective on this mechanism.Acknowledgement: This study was supported by the Scientific And Tecnological Research Council Of Turkey (TÜBİTAK) Project No: 217S089

Review: Obesity Induced Insulin Resistance, Type 2 Diabetes and Emerging Therapeutic Approaches.

There is a strong association between obesity, insulin resistance and type 2 diabetes mellitus. Abdominal obesity appears to be a major mediator of insulin resistance and hyperinsulinemia. Insulin resistance is a pathological condition in which cells fail to respond normally to the hormone insulin. leading to high blood sugar (impaired glucose uptake in peripheral tissues, particularly in skeletal muscle.) The more life-threatening problems fall into four main areas: type 2 diabetes, cardiovascular diseases (CVD), dyslipidemia and certain types of cancers and musculoskeletal disorders. There is considerable evidence that inflammation is a primary mediator of obesity induced insulin resistance and related co-morbidities, including diabetes and CVD whereby pro-inflammatory substances and other chemokines produced by adipocytes and macrophages are able to cause insulin resistance. The major inflammatory factors include pro-inflammatory interleukins (IL-1 & IL-6) and signaling intermediate-nuclear factor kappa B cells (NF-kB), chemokines and cytokines, tumor necrosis factor alpha (TNF-α), adiponectin (ADN), circulating C-reactive protein (CRP) concentrations, toll-like receptors (Tlr), free fatty acids (FFA), oxidative stress and dietary fatty acids. Considering this viewpoint, in the present review, we have selected ten well designed clinical studies with salsalates, thiazolidinediones (TZD) and TNF-α–antagonists to discuss and analyze these emerging therapeutic approaches for the treatment of obesity induced insulin resistance and type 2 diabetes mellitus. These therapeutics provide sufficient evidence of improved glycemic control post treatment in obese patients by targeting the state of chronic inflammation that characterizes obesity and resulted in improved insulin sensitivity by reducing adipocyte pro-inflammatory cytokine expression, adipose tissue macrophage content and immune cell infiltration into adipose tissue and other inflammatory markers. Even with looking at only few studies, analyzing each pathway, the hypothesis that targeting pro-inflammatory pathways in adipocytes with TZD and salicylates as a novel approach remains supported for reducing chronic inflammation-induced insulin resistance in obese patients, with TZD emerging with the strongest effects.

The Role of the Nrf2 Signaling in Obesity and Insulin Resistance.

Obesity, a metabolic disorder characterized by excessive accumulation of adipose tissue, has globally become an increasingly prevalent disease. Extensive studies have been conducted to elucidate the underlying mechanism of the development of obesity. In particular, the close association of inflammation and oxidative stress with obesity has become increasingly evident. Obesity has been shown to exhibit augmented levels of circulating proinflammatory cytokines, which have been associated with the activation of pathways linked with inflammation-induced insulin resistance, a major pathological component of obesity and several other metabolic disorders. Oxidative stress, in addition to its role in stimulating adipose differentiation, which directly triggers obesity, is considered to feed into this pathway, further aggravating insulin resistance. Nuclear factor E2 related factor 2 (Nrf2) is a basic leucine zipper transcription factor that is activated in response to inflammation and oxidative stress, and responds by increasing antioxidant transcription levels. Therefore, Nrf2 has emerged as a critical new target for combating insulin resistance and subsequently, obesity. However, the effects of Nrf2 on insulin resistance and obesity are controversial. This review focuses on the current state of research on the interplay of inflammation and oxidative stress in obesity, the role of the Nrf2 pathway in obesity and insulin resistance, and the potential use of Nrf2 activators for the treatment of insulin resistance.

Collaborative assembly-mediated siRNA delivery for relieving inflammation-induced insulin resistance

Obesity plays a primary causative role in insulin resistance and hyperglycemia that contributes to type 2 diabetes. Excess lipid storage in the liver renders activation of the resident macrophages and chronic secretion of inflammatory mediators, therefore causing or aggravating insulin resistance. Herein, we develop collaborative assemblies using a “one-pot” synthesis method for macrophage-specific delivery of small interfering RNAs (siRNAs) that target the inflammatory proteins. Ternary nanocomplex (NC) composed of the siRNA molecule, a synthetic thiol-bearing methacrylated hyaluronic acid (sm-HA) and protamine forms through an electrostatic-driven physical assembly, which is chemically crosslinked to acquire the collaboratively assembled nanocapsule (cNC) concurrently. The obtained cNC displays significantly higher stability than NC. Functional moieties as flexible assembly units can be easily equipped on cNC for long circulation, active targeting, or controlled siRNA release. cNC-F decorated with folic acid, a macrophage-targeting ligand promotes the siRNA accumulation in the activated macrophages in the liver of the obese mouse model. cNC-F loaded with siRNA targeting inflammatory indicators efficiently control the macrophage inflammatory response by reducing the expression of the inflammatory proteins (> 40% reduction) and ameliorating the insulin resistance symptoms of the obese mice.

Pansteatitis in the Nile Crocodile: A Glimpse into the Pathophysiology using RNA‐Seq and bioinformatics

Concerted efforts to identify the pathogenesis and mechanism(s) involved in pansteatitis, that was attributed to the recent crocodile die off in the Kruger National Park, South Africa have been in the forefront of investigation in recent time. As part of the efforts, molecular characterization of healthy and pansteatitis adipose tissue was carried out by RNA sequencing (RNA‐Seq) using Next Generation Sequencing (NGS) and de novo assembly of the adipose transcriptome, followed by differential gene expression analysis.Healthy adipose tissue consisting of fifty samples was collected from the subcutaneous, visceral, intermuscular adipose tissues and the abdominal fat body of ten 4 years old juvenile crocodiles from a local crocodile farm in Pretoria, South Africa. Ten pansteatitis samples were collected from visceral and intermuscular adipose tissues of five crocodiles that were dying of pansteatitis.Seventy genes were differentially expressed in pansteatitis. They include genes coding for extracellular matrix (ECM) signaling ligands, inflammatory cytokines and tumour necrosis factor alpha (TNFα) receptors, fatty acid synthase and fatty acid binding proteins, peroxisome proliferator‐activated receptor gamma (PPARγ), nuclear factor and apoptosis signaling ligands, and mitogen activated protein kinase enzymes among others. Majority (88.6%) of the upregulated genes were found to be involved in hypoxia inducible pathways for activation of NFkβ and inflammation, apoptosis, Toll‐like receptor pathway and PPARγ. Bicaudal homologous 2 Drosophila gene (BICD2) associated with spinal and lower extremity muscle atrophy was also upregulated in pansteatitis while Sphingosine‐1‐phosphate phosphatase 2 (SGPP2) involved in Sphingosine‐1‐phosphate metabolism was downregulated. Futhermore, Doublesex –mab‐related transcription factor 1 (DMRT1) responsible for sex gonad development and germ cell differentiation was also downregulated.Thus, from the present study, based on differentially expressed genes in pansteatitis, affected Nile crocodiles might have died partly due to their inability to utilize stored triglycerides as a result of inflammation induced insulin resistance, leading to starvation in the midst of plenty. Affected animals may have also suffered muscular atrophy of the lower extremities and poor fertility.

Effect of JAK-STAT pathway in regulation of fatty liver hemorrhagic syndrome in chickens.

ObjectiveTo explore the molecular mechanisms of fatty liver hemorrhagic syndrome (FLHS) in laying hens, an experiment was conducted to reveal the differences in histopathological observation and gene expression between FLHS group and normal group.MethodsWe compared the histopathological difference using hematoxylin and eosin staining and proceeded with RNA sequencing of adipose tissue to search differentially expressed genes and enriched biological processes and pathways. Then we validated the mRNA expression levels by real-time polymerase chain reaction and quantified protein levels in the circulation by enzyme-linked immunosorbent assay.ResultsWe identified 100 differentially expressed transcripts corresponding to 66 genes (DEGs) were identified between FLHS-affected group and normal group. Seven DEGs were significantly enriched in the immune response process and lipid metabolic process, including phospholipase A2 group V, WAP kunitz and netrin domain containing 2, delta 4-desaturase sphingolipid 2, perilipin 3, interleukin-6 (IL-6), ciliary neurotrophic factor (CNTF), and suppressor of cytokine signaling 3 (SOCS3). And these genes could be the targets of immune response and be involved in metabolic homeostasis during the process of FLHS in laying hens. Based on functional categories of the DEGs, we further proposed a model to explain the etiology and pathogenesis of FLHS. IL-6 and SOCS3 mediate inflammatory responses and the satiety hormone of leptin, induce dysfunction of Jak-STAT signaling pathway, leading to insulin resistance and lipid metabolic disorders. Conversely, CNTF may reduce tissue destruction during inflammatory attacks and confer protection from inflammation-induced insulin resistance in FLHS chickens.ConclusionThese findings highlight the therapeutic implications of targeting the JAK-STAT pathway. Inhibition of IL6 and SOCS3 and facilitation of CNTF could serve as a favorable strategy to enhance insulin action and improve glucose homoeostasis, which are of importance for treating obesity-related disorders for chickens.

Catestatin improves insulin sensitivity by attenuating endoplasmic reticulum stress: In vivo and in silico validation

Obesity is characterized by a state of chronic, unresolved inflammation in insulin-targeted tissues. Obesity-induced inflammation causes accumulation of proinflammatory macrophages in adipose tissue and liver. Proinflammatory cytokines released from tissue macrophages inhibits insulin sensitivity. Obesity also leads to inflammation-induced endoplasmic reticulum (ER) stress and insulin resistance. In this scenario, based on the data (specifically patterns) generated by our in vivo experiments on both diet-induced obese (DIO) and normal chow diet (NCD) mice, we developed an in silico state space model to integrate ER stress and insulin signaling pathways. Computational results successfully followed the experimental results for both DIO and NCD conditions. Chromogranin A (CgA) peptide catestatin (CST: hCgA352-372) improves obesity-induced hepatic insulin resistance by reducing inflammation and inhibiting proinflammatory macrophage infiltration. We reasoned that the anti-inflammatory effects of CST would alleviate ER stress. CST decreased obesity-induced ER dilation in hepatocytes and macrophages. On application of Proportional-Integral-Derivative (PID) controllers on the in silico model, we checked whether the reduction of phosphorylated PERK resulting in attenuation of ER stress, resembling CST effect, could enhance insulin sensitivity. The simulation results clearly pointed out that CST not only decreased ER stress but also enhanced insulin sensitivity in mammalian cells. In vivo experiment validated the simulation results by depicting that CST caused decrease in phosphorylation of UPR signaling molecules and increased phosphorylation of insulin signaling molecules. Besides simulation results predicted that enhancement of AKT phosphorylation helps in both overcoming ER stress and achieving insulin sensitivity. These effects of CST were verified in hepatocyte culture model.

Next generation sequencing and RNA-seq characterization of adipose tissue in the Nile crocodile (Crocodylus niloticus) in South Africa: Possible mechanism(s) of pathogenesis and pathophysiology of pansteatitis.

BackgroundConcerted efforts to identify the pathogenesis and mechanism(s) involved in pansteatitis, (a generalized inflammation of the adipose tissue), that was attributed to the recent crocodile die off in the Olifants River and Loskop Dam in Kruger National Park, Mpumalanga, South Africa have been in the forefront of research in recent time. As part of the efforts, molecular characterization of healthy and pansteatitis adipose tissue was carried out by RNA sequencing (RNA-Seq) using Next Generation Sequencing (NGS) and de novo assembly of the adipose transcriptome, followed by differential gene expression analysis.MethodologyHealthy adipose tissue consisting of fifty samples was collected from the subcutaneous, visceral, intermuscular adipose tissues and the abdominal fat body of ten 4 years old juvenile crocodiles from a local crocodile farm in Pretoria, South Africa. Ten pansteatitis samples were collected from visceral and intermuscular adipose tissues of five crocodiles that were dying of pansteatitis.ResultsForty-two thousand, two hundred and one (42,201) transcripts were assembled, out of which 37, 835 had previously been characterized. The de novo assembled transcriptome had an N50 (average sequence) of 436 bp, percentage GC content of 43.92, which compared well with previously assembled transcripts in the saltwater crocodile. Seventy genes were differentially expressed and upregulated in pansteatitis. These included genes coding for extracellular matrix (ECM) signaling ligands, inflammatory cytokines and tumour necrosis factor alpha (TNFα) receptors, fatty acid synthase and fatty acid binding proteins, peroxisome proliferator-activated receptor gamma (PPARγ), nuclear factor and apoptosis signaling ligands, and mitogen activated protein kinase enzymes among others. Majority (88.6%) of the upregulated genes were found to be involved in hypoxia inducible pathways for activation of NFkβ and inflammation, apoptosis, Toll-like receptor pathway and PPARγ. Bicaudal homologous 2 Drosophila gene (BICD2) associated with spinal and lower extremity muscle atrophy was also upregulated in pansteatitis while Sphingosine -1-phosphate phosphatase 2 (SGPP2) involved in Sphingosine -1- phosphate metabolism was downregulated. Futhermore, Doublesex–mab-related transcription factor 1 (DMRT1) responsible for sex gonad development and germ cell differentiation was also downregulated.ConclusionThus, from the present study, based on differentially expressed genes in pansteatitis, affected Nile crocodiles might have died partly due to their inability to utilize stored triglycerides as a result of inflammation induced insulin resistance, leading to starvation in the midst of plenty. Affected animals may have also suffered muscular atrophy of the lower extremities and poor fertility.