Outer membrane vesicles of avian pathogenic Escherichia coli induce necroptosis and NF-κB activation in chicken macrophages via RIPK1 mediation.

Outer membrane vesicles (OMVs) are soluble mediators secreted by Gram-negative bacteria that are involved in communication. They can carry a variety of harmful molecules, which induce cytotoxic responses and inflammatory reactions in the absence of direct host cell-bacterium interactions. We previously reported the isolation of OMVs from avian pathogenic Escherichia coli (APEC) culture medium by ultracentrifugation, and characterized them as a substance capable of inducing the production of pro-inflammatory cytokines and causing tissue damage. However, the specific mechanisms by which APEC-secreted OMVs activate host cell death signaling and inflammation are poorly understood. Here, we show that OMVs are involved in the pathogenesis of APEC disease. In an APEC/chicken macrophage (HD11) coculture system, APEC significantly promoted HD11 cell death and inflammatory responses by secreting OMVs. Using western blotting analysis and specific pathway inhibitors, we demonstrated that the induction of HD11 death by APEC OMVs is associated with the activation of receptor interacting serine/threonine kinase 1 (RIPK1)-, receptor interacting serine/threonine kinase 3 (RIPK3)-, and mixed lineage kinase like pseudokinase (MLKL)-induced necroptosis. Notably, necroptosis inhibitor-1 (Nec-1), an RIPK1 inhibitor, reversed these effects. We also showed that APEC OMVs promote the activation of the NF-κB signaling pathway, leading to the phosphorylation of IκB-α and p65, the increased nuclear translocation of p65, and the significant upregulation of interleukin 1ß (IL-1ß) and IL-6 transcription. Importantly, APEC OMVs-induced IL-1ß and IL-6 mRNA expression and the activation of the NF-κB signaling pathway were similarly significantly inhibited by a RIPK1-specific inhibitor. Based on these findings, we have established that RIPK1 plays a dual role in HD11 cells necroptosis and the proinflammatory cytokine (IL-1ß and IL-6) expression induced by APEC OMVs. RIPK1 mediated the induction of necroptosis and the activation of the NF-κB in HD11 cells via APEC OMVs. The results of this study provide a basis for further investigation of the contribution of OMVs to the pathogenesis of APEC.

Emerging role of NEDD8-mediated neddylation in age-related metabolic diseases.

Aging in humans is associated with abdominal distribution and remodeling of body fat and a parallel gradual increase in the prevalence of metabolic diseases such as obesity, type 2 diabetes mellitus and fatty liver disease, as well as the risk of developing metabolic complications. Current treatments might be improved by understanding the detailed mechanisms underlying the onset of age-related metabolic disorders. Neddylation, a post-translational modification that adds the ubiquitin-like protein NEDD8 to substrate proteins, has recently been linked to age-related metabolic diseases, opening new avenues of investigation and raising a potential target for treatment of these diseases. In this review, we will focus on the potential role of NEDD8-mediated neddylation in age-related metabolic dysregulation, insulin resistance, obesity, type 2 diabetes mellitus and fatty liver. We propose that alterations in NEDD8-mediated neddylation contribute to triggering insulin resistance and the development of age-related metabolic dysregulation, thus highlighting NEDD8 as a promising therapeutic target for preventing age-related metabolic diseases.

Acetylation of p65Lys310 by p300 in macrophages mediates anti-inflammatory property of berberine.

Nuclear factor (NF)-κB plays a pivotal role in the regulation of inflammatory response in macrophages. Berberine (BBR), which is an active constituent isolated from Coptis rhizome, possesses a prominent anti-inflammatory activity. Here we show that BBR changes the global acetylation landscape in LPS-induced protein acetylation of macrophages and reduces the acetylation of NF-κB subunit p65 at site Lys310(p65Lys310), leading to the inhibition of NF-κB translocation and transcriptional activity to suppress the expressions of inflammatory factors. BBR resists the inflammatory response in acute LPS-stimulated mice through downregulation of p65Lys310 acetylation in peritoneal macrophages. In obese mice, BBR alleviates the metabolic disorder and inflammation with the reduced acetylation of p65Lys310 in white adipose tissue. Furthermore, we demonstrate that BBR acts as a regulator of p65Lys310 by inhibiting the expression of p300 in macrophages. Our findings elucidate a new molecular mechanism for the anti-inflammatory effect of BBR via the p300/p65Lys310 axis.

Emerging roles of histone deacetylases in adaptive thermogenesis.

Brown and beige adipose tissues regulate body energy expenditure through adaptive thermogenesis, which converts energy into heat by oxidative phosphorylation uncoupling. Although promoting adaptive thermogenesis has been demonstrated to be a prospective strategy for obesity control, there are few methods for increasing adipose tissue thermogenesis in a safe and effective way. Histone deacetylase (HDAC) is a category of epigenetic modifying enzymes that catalyzes deacetylation on both histone and non-histone proteins. Recent studies illustrated that HDACs play an important role in adipose tissue thermogenesis through modulating gene transcription and chromatin structure as well as cellular signals transduction in both deacetylation dependent or independent manners. Given that different classes and subtypes of HDACs show diversity in the mechanisms of adaptive thermogenesis regulation, we systematically summarized the effects of different HDACs on adaptive thermogenesis and their underlying mechanisms in this review. We also emphasized the differences among HDACs in thermogenesis regulation, which will help to find new efficient anti-obesity drugs targeting specific HDAC subtypes.

Biodistribution of 89Zr-DFO-labeled avian pathogenic Escherichia coli outer membrane vesicles by PET imaging in chickens.

Avian pathogenic Escherichia coli (APEC) is a serious systemic infectious disease in poultry infections, causing severe economic losses to the poultry industry. Previous studies have shown that secretion of virulence proteins was required for the pathogenicity of APEC through the secretion system. Outer membrane vesicles (OMVs) are a generalized secretion system of Gram-negative bacteria that play a key role in the long-distance delivery of virulence factors, but whether they are associated with the pathogenic mechanism of APEC has not been determined. In this study, OMVs were purified and characterized from AE17 (O2 serotype) by ultracentrifugation and density gradient centrifugation and their protein cargo was identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, 89Zr was labeled after chelating AE17 OMVs by DFO and positron emission tomography PET imaging was used to track 89Zr-DFO-OMVs in chickens and to pathologically analyze the distribution sites. This study showed that AE17 OMVs were membrane vesicles ranging in size from 20 to 200 nm and proteomic analysis revealed the presence of virulence proteins, including adhesion proteins OmpA, OmpC, OmpF, OmpX, FimH, FimC and FigE, and serum resistance proteins OmpT and MliC and immune response regulator proteins (FliC). In addition, in vivo PET imaging to track the biodistribution of AE17 OMVs showed that AE17 OMVs were taken up by the lung region and the gastrointestinal and renal regions but were not detected in other areas. Pathological analysis of the tissue sites where AE17 OMVs were ingested showed inflammatory responses and damage. These findings suggested that AE17 OMVs not only contained a group of virulence proteins associated with AE17 infection but can also deliver these virulence proteins over long distances and caused tissue inflammatory damage. Our study revealed a previously unidentified causative microbial signal in the pathogenesis of APEC that could aid in the development of vaccines and antibiotics effective against APEC.

Adipose-Muscle crosstalk in age-related metabolic disorders: The emerging roles of adipo-myokines.

Obesity and type 2 diabetes account for a considerable proportion of the global burden of age-related metabolic diseases. In age-related metabolic diseases, tissue crosstalk and metabolic regulation have been primarily linked to endocrine processes. Skeletal muscle and adipose tissue are endocrine organs that release myokines and adipokines into the bloodstream, respectively. These cytokines regulate metabolic responses in a variety of tissues, including skeletal muscle and adipose tissue. However, the intricate mechanisms underlying adipose-muscle crosstalk in age-related metabolic diseases are not fully understood. Recent exciting evidence suggests that myokines act to control adipose tissue functions, including lipolysis, browning, and inflammation, whereas adipokines mediate the beneficial actions of adipose tissue in the muscle, such as glucose uptake and metabolism. In this review, we assess the mechanisms of adipose-muscle crosstalk in age-related disorders and propose that the adipokines adiponectin and spexin, as well as the myokines irisin and interleukin-6 (IL-6), are crucial for maintaining the body's metabolic balance in age-related metabolic disorders. In addition, these changes of adipose-muscle crosstalk in response to exercise or dietary flavonoid consumption are part of the mechanisms of both functions in the remission of age-related metabolic disorders. A better understanding of the intricate relationships between adipose tissue and skeletal muscle could lead to more potent therapeutic approaches to prolong life and prevent age-related metabolic diseases.

[Research progress in epigenetic pharmacological effects of rhein].

Rhein, which is one of the main active components of Rheum palmatum, has a range of pharmacological activities such as the regulation of the metabolism of glucose and lipids, anti-inflammatory, anti-tumor, anti-fibrosis, etc. Epigenetics refers to the heritable variation of gene expression without altering the DNA sequence. It is involved in the emergence and development of inflammation, renal fibrosis, diabetes, cancer, atherosclerosis, and other diseases, thus becoming a new strategy for the treatment of many di-seases. A series of studies have shown that epigenetic modification may be a common molecular mechanism of various pharmacological effects of rhein. This paper summarized the effects of rhein on the regulation of epigenetic modification and its underlying mechanisms, which involve the regulation of DNA methylation, protein acetylation, and RNA methylation, so as to provide a basis for the development and application of rhein.

Rapid detection of porcine circovirus type 4 via multienzyme isothermal rapid amplification.

Porcine circovirus type 4 (PCV4) is a newly emerging pathogen that was first detected in 2019 and is associated with diverse clinical signs, including respiratory and gastrointestinal distress, dermatitis and various systemic inflammations. It was necessary to develop a sensitive and specific diagnostic method to detect PCV4 in clinical samples, so in this study, a multienzyme isothermal rapid amplification (MIRA) assay was developed for the rapid detection of PCV4 and evaluated for sensitivity, specificity and applicability. It was used to detect the conserved Cap gene of PCV4, operated at 41°C and completed in 20 min. With the screening of MIRA primer-probe combination, it could detect as low as 101 copies of PCV4 DNA per reaction and was highly specific, with no cross-reaction with other pathogens. Further assessment with clinical samples showed that the developed MIRA assay had good correlation with real-time polymerase chain reaction assay for the detection of PCV4. The developed MIRA assay will be a valuable tool for the detection of the novel PCV4 in clinical samples due to its high sensitivity and specificity, simplicity of operation and short testing time.

Upregulation of adiponectin by Ginsenoside Rb1 contributes to amelioration of hepatic steatosis induced by high fat diet.

Background: Ginsenoside Rb1 (GRb1) is capable of regulating lipid and glucose metabolism through its action on adipocytes. However, the beneficial role of GRb1-induced up-regulation of adiponectin in liver steatosis remains unelucidated. Thus, we tested whether GRb1 ameliorates liver steatosis and insulin resistance by promoting the expression of adiponectin. Methods: 3T3-L1 adipocytes and hepatocytes were used to investigate GRb1's action on adiponectin expression and triglyceride (TG) accumulation. Wild type (WT) mice and adiponectin knockout (KO) mice fed high fat diet were treated with GRb1 for 2 weeks. Hepatic fat accumulation and function as well as insulin sensitivity was measured. The activation of AMPK was also detected in the liver and hepatocytes. Results: GRb1 reversed the reduction of adiponectin secretion in adipocytes. The conditioned medium (CM) from adipocytes treated with GRb1 reduced TG accumulation in hepatocytes, which was partly attenuated by the adiponectin antibody. In the KO mice, the GRb1-induced significant decrease of TG content, ALT and AST was blocked by the deletion of adiponectin. The elevations of GRb1-induced insulin sensitivity indicated by OGTT, ITT and HOMA-IR were also weakened in the KO mice. The CM treatment significantly enhanced the phosphorylation of AMPK in hepatocytes, but not GRb1 treatment. Likewise, the phosphorylation of AMPK in liver of the WT mice was increased by GRb1, but not in the KO mice. Conclusions: The up-regulation of adiponectin by GRb1 contributes to the amelioration of liver steatosis and insulin resistance, which further elucidates a new mechanism underlying the beneficial effects of GRb1 on obesity.

Activation of AMPK/miR-181b Axis Alleviates Endothelial Dysfunction and Vascular Inflammation in Diabetic Mice.

Hyperglycemia in diabetes mellitus impairs endothelial function and disrupts microRNA (miRNA) profiles in vasculature, increasing the risk of diabetes-associated complications, including coronary artery disease, diabetic retinopathy, and diabetic nephropathy. miR-181b was previously reported to be an anti-inflammatory mediator in vasculature against atherosclerosis. The current study aimed to investigate whether miR-181b ameliorates diabetes-associated endothelial dysfunction, and to identify potential molecular mechanisms and upstream inducer of miR-181b. We found that miR-181b level was decreased in renal arteries of diabetic patients and in advanced glycation end products (AGEs)-treated renal arteries of non-diabetic patients. Transfection of miR-181b mimics improved endothelium-dependent vasodilation in aortas of high fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice, accompanied by suppression of superoxide overproduction and vascular inflammation markers. AMPK activator-induced AMPK activation upregulated miR-181b level in human umbilical vein endothelial cells (HUVECs). Chronic exercise, potentially through increased blood flow, activated AMPK/miR-181b axis in aortas of diabetic mice. Exposure to laminar shear stress upregulated miR-181b expression in HUVECs. Overall, our findings highlight a critical role of AMPK/miR-181b axis and extend the benefits of chronic exercise in counteracting diabetes-associated endothelial dysfunction.

Treatment with spexin mitigates diet-induced hepatic steatosis in vivo and in vitro through activation of galanin receptor 2.

It was reported that spexin as an adipocyte-secreted protein could regulate obesity and insulin resistance. However, the specific metabolic contribution of spexin to fatty liver remains incompletely understood. Herein, we investigated the effects of spexin on hepatosteatosis and explored the underlying molecular mechanisms. HFD-fed mice were injected with spexin and/or GALR2 antagonist M871, while PA-induced HepG2 cells were treated with spexin in the absence or presence of M871 for 12 h, respectively. Gene expression in liver tissues and hepatocytes was assessed by qRT-PCR and western blotting, respectively. The results showed that body weight, visceral fat content, liver lipid droplet formation, hepatic intracellular triglyceride, and serum triglyceride were reduced in spexin-treated mice. Furthermore, spexin increased the expression of hepatic CPT1A, PPARα, SIRT1, KLF9, PGC-1α and PEPCK in vivo and in vitro. Additionally, spexin treatment improved glucose tolerance and insulin sensitivity in mice fed the HFD. Interestingly, these spexin-mediated beneficial effects were abolished by the GALR2 antagonist M871 in mice fed HFD and PA-induced HepG2 cells, suggesting that spexin mitigated HFD-induced hepatic steatosis by activating the GALR2, thereby increasing CPT1A, PPARα, SIRT1, KLF9, PGC-1α and PEPCK expression. Taken together, these data suggest that spexin ameliorates NAFLD by improving lipolysis and fatty acid oxidation via activation of GALR2 signaling.

Increased Serum VEGF-B Level Is Associated With Renal Function Impairment in Patients With Type 2 Diabetes.

Aims/Introduction: Renal function impairment related to type 2 diabetes (T2DM) presents serious threat to public health. Previous studies suggest that vascular endothelial growth factor-B (VEGF-B) might contribute to renal injury. Therefore, this study investigated the association of serum VEGF-B level with the risk of renal function impairment in T2DM patients. Materials and Methods: Serum VEGF-B levels were measured in 213 patients with type 2 diabetes and 31 healthy participants. Participants with type 2 diabetes were further divided into a group of 112 participants with eGFR<90 mL/min/1.73m2 and 101 participants with eGFR≥ 90 mL/min/1.73m2. Clinical data were collected, and a binary logistic regression model was employed to test the association between potential predictors and eGFR. Results: Serum VEGF-B levels evaluated in type 2 diabetes patients compared with healthy controls. In patients with type 2 diabetes, serum VEGF-B level was positively correlated with triglyceride, serum creatinine and cystatin C while negatively correlated with HDL-C and eGFR. Binary logistic regression showed that serum VEGF-B level was an independent risk factor of eGFR<90 mL/min/1.73m2. Conclusions: Serum VEGF-B level is associated with renal function impairment in patients with type 2 diabetes and may be a potential drug target for diabetic kidney disease.

Adipose tissue spexin in physical exercise and age-associated diseases.

It is known that a strong association exists between a suboptimal lifestyle (physical inactivity and sedentary behavior and/or high calorie diet) and increased propensity of developing age-associated diseases, such as obesity and T2DM. Physical exercise can alleviate obesity-induced insulin resistance and T2DM, however, the precise mechanism for this outcome is not fully understood. The endocrine disorder of adipose tissue in obesity plays a critical role in the development of insulin resistance. In this regard, spexin has been recently described as an adipokine that plays an important role in the pathophysiology of obesity-induced insulin resistance and T2DM. In obese states, expression of adipose tissue spexin is reduced, inducing the adipose tissue and skeletal muscle more susceptible to insulin resistance. Emerging evidences point out that exercise can increase spexin expression. In return, spexin could exert the exercise-protective roles to ameliorate insulin resistance, suggesting that spexin is a potential mediator for exercise to ameliorate obesity-induced insulin resistance and T2DM, namely, the beneficial effect of exercise on insulin sensitivity is at least partly mediated by spexin. This review summarizes our and others' recent studies regarding the effects of obesity on adipose tissue spexin induction, along with the potential effect of exercise on this response in obese context, and provides a new insight into the multivariate relationship among exercise, spexin and T2DM. It should be therefore taken into account that a combination of spexin and exercise training is an effective therapeutic strategy for age-associated diseases.

Emerging roles of kisspeptin/galanin in age-related metabolic disease.

Age is a major risk factor for developing metabolic diseases such as obesity and diabetes. There is an unprecedented rise in obesity and type 2 diabetes in recent decades. A convincing majority of brain-gut peptides are associated with a higher risk to develop metabolic disorders, and may contribute to the pathophysiology of age-related metabolic diseases. Accumulating basic studies revealed an intriguing role of kisspeptin and galanin involved in the amelioration of insulin resistance in different ways. In patients suffered from obesity and diabetes a significant, sex-related changes in the plasma kisspeptin and galanin levels occurred. Kisspeptin is anorexigenic to prevent obesity, its level is negatively correlative with obesity and insulin resistance. While galanin is appetitive to stimulate food intake and body weight, its level is positively correlative with obesity, HOMA-IR and glucose/triglyceride concentration. In turn, kisspeptin and galanin also distinctly increase glucose uptake and utilization as well as energy expenditure. This article reviews recent evidence dealing with the role of kisspeptin and galanin in the pathophysiology of age-related metabolic diseases. It should be therefore taken into account that the targeted modulation of those peptidergic signaling may be potentially helpful in the future treatment of age-related metabolic diseases.

A high methionine and low folate diet alters glucose homeostasis and gut microbiome.

Hyperhomocysteinemia (HHcy) is considered as a risk factor for several complications, including cardiovascular and neurological disorders. A high methionine low folate (HMLF) diet chronically causes HHcy by accumulating homocysteine in the systemic circulation. Elevated Hcy level is also associated with the incidence of diabetes mellitus. However, very few studies focus on the impact of HMLF diet on glucose homeostasis, and that on gut microbiome profile. HHcy was induced by feeding C57BL/6 mice a HMLF diet for 8 weeks. The HMLF diet feeding resulted in a progressive body weight loss, and development of slight glucose intolerance and insulin resistance in HHcy mice. Notably, the HMLF diet alters the gut microbiome profile and increases the relative abundance of porphyromonadaceae family of bacteria in HHcy mice. These findings provide new insights into the roles of dysregulated glucose homeostasis and gut flora in the pathogenesis of HHcy-related complications.

Nitrogen-Centered Radical-Mediated Cascade Amidoglycosylation of Glycals.

A nitrogen-centered radical-mediated strategy for preparing 1,2-trans-2-amino-2-deoxyglycosides in one step was established. The cascade amidoglycosylation was initiated by a benzenesulfonimide radical generated from NFSI under the catalytic reduction of TEMPO. The benzenesulfonimide radical was electrophilically added to the glycals, and then the resulting glycosidic radical was converted to oxocarbenium upon oxidation by TEMPO+, which enabled the following anomeric specific glycosylation.

A promising biomarker of elevated galanin level in hypothalamus for osteoporosis risk in type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) and osteoporosis are two major healthcare problems worldwide. T2DM is considered to be a risk factor for osteoporosis. Interestingly, several epidemiological studies suggest that bone abnormalities associated with diabetes may differ, at least in part, from those associated with senile or post-menopausal osteoporosis. The growing prevalence that patients with T2DM simultaneously suffer from osteoporosis, puts forward the importance to discuss the relationship between both diseases, as well as to investigate correlative agents to treat them. Emerging evidences demonstrate that neuropeptide galanin is involved in the pathogenesis of T2DM and osteoporosis. Galanin via activation of central GALR2 increases insulin sensitivity as well as bone density and mass in animal models. The disorder of galanin function plays major role in development of both diseases. Importantly, galanin signaling is indispensable for ΔFosB, an AP1 antagonist, to play the bone mass-accruing effects in the ventral hypothalamic neurons of diabetic models. This review summarizes our and other recent studies to provide a new insight into the multivariate relationship among galanin, T2DM and osteoporosis, highlighting the beneficial effect of galanin on the comorbid state of both diseases. These may help us better understanding the pathogenesis of osteoporosis and T2DM and provide useful clues for further inquiry if elevated galanin level may be taken as a biomarker for both conjoint diseases, and GALR2 agonist may be taken as a novel therapeutic strategy to treat both diseases concurrently.

Sn-based metal-organic framework for highly selective capture of monophosphopeptides.

Sn-based metal-organic framework (MOF) was utilized to effectively capture monophosphopeptides due to the unique affinity. The Sn-based MOF demonstrated the good sensitivity and selectivity in the model phosphoproteins enrichment and was successfully applied in the biological fluids.

Melatonin Alleviates Glucose and Lipid Metabolism Disorders in Guinea Pigs Caused by Different Artificial Light Rhythms.

Modern lifestyle-associated factors, such as high-calorie intake, high-fat diet (HFD), and excessive artificial light, are risk factors for glucose and lipid metabolism disturbances. Melatonin may be beneficial for managing obesity and diabetes; however, the underlying molecular mechanisms are not well elucidated. We aimed to assess whether melatonin has beneficial effects on constant artificial light-induced fat deposition, lipid metabolism, and insulin resistance. Guinea pigs were randomly divided into five experimental groups: control (C), HFD (H), 12 h light (12HL), 24 h light (24HL), and melatonin (M). The majority of indexes, including insulin resistance and obesity, were measured after 10 weeks. AMP-activated protein kinase α (AMPKα)/peroxisome proliferator-activated receptor-α (PPARα) pathway expression was analyzed by quantitative reverse transcription PCR and western blotting. Although insulin resistance and obesity indexes were higher in the 24HL group than in the 12HL group, they were significantly lower in the M group than in the 24HL group. Melatonin treatment markedly upregulated AMPKα, phosphorylated AMPKα (p-AMPKα), PPARα, and carnitine palmitoyl-CoA transferase 1 A (CPT1A) gene and protein expression. Melatonin may alleviate insulin resistance and obesity caused by persistent artificial light exposure in guinea pigs, likely via activation of the AMPKα/PPARα signaling pathway.

Highly efficient enrichment of N-glycopeptides by two-dimensional Hf-based metal-organic framework nanosheets.

Highly efficient enrichment of target glycopeptides plays a crucial role in glycoproteome research. Owing to their large surface area and excellent hydrophilicity, 2-D Hf-BTB nanosheets showed effective and selective enrichment of 78 glycopeptides derived from 29 glycoproteins with 90 N-glycosylation sites from just 2 µL of human serum.