AMPK deficiency inhibits fatty acid oxidation in endothelial progenitor cells to aggravate impaired angiogenesis after ischemic stroke in hyperlipidemic mice.

BACKGROUND: Hyperlipidemia is a risk factor for stroke, and worsens neurological outcome after stroke. Endothelial progenitor cells (EPCs), which become dysfunctional in cerebral ischemia, hold capacity to promote revascularization. OBJECTIVE: We investigated the role of dyslipidemia in impairment of EPC-mediated angiogenesis in cerebral ischemic mice. METHODS AND RESULTS: The high fat diet (HFD)-fed mice following by ischemic stroke exhibited increased infarct volumes and neurological severity scores, and poorer angiogenesis. Bone marrow-EPCs treated with palmitic acid (PA) showed impaired functions and inhibited activity of AMP-activated protein kinase (AMPK). Notably, AMPK deficiency aggravated EPC dysfunction, further decreased mitochondrial membrane potential, and increased reactive oxygen species level in EPCs with PA treatment. Furthermore, the expression of fatty acid oxidation (FAO)-related genes was remarkably reduced, and carnitine palmitoyltransferase 1A (CPT1A) protein expression was downregulated in AMPK-deficient EPCs. AMPK deficiency aggravated neurological severity scores and angiogenesis in ischemic brain of HFD-fed mice, accompanied by suppressed protein level of CPT1A. EPC transplantation corrected impaired neurological severity scores and angiogenesis in AMPK-deficient mice. CONCLUSION: Our findings suggest that AMPK deficiency aggravates poor angiogenesis in ischemic brain by mediating FAO and oxidative stress thereby inducing EPC dysfunction in hyperlipidemic mice.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming.

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

Macrophage SHP2 Deficiency Alleviates Diabetic Nephropathy via Suppression of MAPK/NF-κB- Dependent Inflammation.

Increasing evidence implicates chronic inflammation as the main pathological cause of diabetic nephropathy (DN). Exploration of key targets in the inflammatory pathway may provide new treatment options for DN. We aimed to investigate the role of Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) in macrophages and its association with DN. The upregulated phosphorylation of SHP2 was detected in macrophages in both patients with diabetes and in a mouse model. Using macrophage-specific SHP2-knockout (SHP2-MKO) mice and SHP2fl/fl mice injected with streptozotocin (STZ), we showed that SHP2-MKO significantly attenuated renal dysfunction, collagen deposition, fibrosis, and inflammatory response in mice with STZ-induced diabetes. RNA-sequencing analysis using primary mouse peritoneal macrophages (MPMs) showed that SHP2 deletion mainly affected mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways as well as MAPK/NF-κB-dependent inflammatory cytokine release in MPMs. Further study indicated that SHP2-deficient macrophages failed to release cytokines that induce phenotypic transition and fibrosis in renal cells. Administration with a pharmacological SHP2 inhibitor, SHP099, remarkably protected kidneys in both type 1 and type 2 diabetic mice. In conclusion, these results identify macrophage SHP2 as a new accelerator of DN and suggest that SHP2 inhibition may be a therapeutic option for patients with DN.

Clinically relevant antibiotic resistance genes are linked to a limited set of taxa within gut microbiome worldwide.

The acquisition of antimicrobial resistance (AR) genes has rendered important pathogens nearly or fully unresponsive to antibiotics. It has been suggested that pathogens acquire AR traits from the gut microbiota, which collectively serve as a global reservoir for AR genes conferring resistance to all classes of antibiotics. However, only a subset of AR genes confers resistance to clinically relevant antibiotics, and, although these AR gene profiles are well-characterized for common pathogens, less is known about their taxonomic associations and transfer potential within diverse members of the gut microbiota. We examined a collection of 14,850 human metagenomes and 1666 environmental metagenomes from 33 countries, in addition to nearly 600,000 isolate genomes, to gain insight into the global prevalence and taxonomic range of clinically relevant AR genes. We find that several of the most concerning AR genes, such as those encoding the cephalosporinase CTX-M and carbapenemases KPC, IMP, NDM, and VIM, remain taxonomically restricted to Proteobacteria. Even cfiA, the most common carbapenemase gene within the human gut microbiome, remains tightly restricted to Bacteroides, despite being found on a mobilizable plasmid. We confirmed these findings in gut microbiome samples from India, Honduras, Pakistan, and Vietnam, using a high-sensitivity single-cell fusion PCR approach. Focusing on a set of genes encoding carbapenemases and cephalosporinases, thus far restricted to Bacteroides species, we find that few mutations are required for efficacy in a different phylum, raising the question of why these genes have not spread more widely. Overall, these data suggest that globally prevalent, clinically relevant AR genes have not yet established themselves across diverse commensal gut microbiota.

Linderalactone mitigates diabetic cardiomyopathy in mice via suppressing the MAPK/ATF6 pathway.

Diabetic cardiomyopathy (DCM) is a challenging diabetic complication that manifests as chronic inflammation. Yet, the mechanism underlying diabetes-associated myocardial injury is not fully understood. We investigated the pharmacological effects and mechanisms of linderalactone, a natural compound that can prevent diabetes-induced cardiomyopathy in mice. Diabetes was induced by a single dose of streptozotocin (120 mg/kg, i.p.). Diabetic mice were administrated with linderalactone (2.5 or 5 mg/kg) by gavage for five weeks. Harvested heart tissues were then subjected to RNA-sequencing analysis to explore the potential mechanism of linderalactone. Linderalactone prevented heart dysfunction by inhibiting myocardial hypertrophy, fibrosis, and inflammation, without altering blood glucose. RNA-sequencing indicated that linderalactone exerted its cardioprotective effects mainly by affecting the mitogen-activated protein kinase (MAPK)/ activating transcription factor 6 (ATF6) pathway. Linderalactone also suppressed endoplasmic reticulum (ER) stress mediated by the diabetes-activated MAPKs/ATF6 pathway, thereby reducing myocardial hypertrophy and inflammation in heart tissues and in cultured cardiomyocytes. Inhibition of MAPKs or a deficiency of ATF6 in cardiomyocytes mimicked the linderalactone-associated decreases in high glucose-induced hypertrophy and inflammation. Linderalactone showed beneficial effects in alleviating diabetic cardiomyopathy, in part by modulating the MAPK/ATF6 signaling pathway to mitigate myocardial hypertrophy and inflammation. Linderalactone may have clinical utility in the treatment for diabetes-associated cardiomyopathy.

The effects of sodium sulfite on Helicobacter pylori by establishing a hypoxic environment.

Helicobacter pylori (H. pylori) is an obligate microaerobion and does not survive in low oxygen. Sodium sulfite (SS) reacts and consume oxygen in solutions. The present study aimed to investigate the effects of SS on H. pylori. The effects of SS on oxygen concentrations in solutions and on H. pylori in vivo and in vitro were examined, and the mechanisms involved were explored. The results showed that SS decreased the oxygen concentration in water and artificial gastric juice. In Columbia blood agar and special peptone broth, SS concentration-dependently inhibited the proliferation of H. pylori ATCC43504 and Sydney strain-1 in Columbia blood agar or special peptone broth, and dose-dependently decreased the number of H. pylori in Mongolian gerbils and Kunming mouse infection models. The H. pylori was relapsed in 2 weeks withdrawal and the recurrence in the SS group was lower than that in the positive triple drug group. These effects were superior to positive triple drugs. After SS treatments, the cell membrane and cytoplasm structure of H. pylori were disrupted. SS-induced oxygen-free environment initially blocked aerobic respiration, triggered oxidative stress, disturbed energy production. In conclusion, SS consumes oxygen and creates an oxygen-free environment in which H. pylori does not survive. The present study provides a new strategy and perspective for the clinical treatment of H. pylori infectious disease.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming.

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

Inflammatory Bowel Disease-Associated Gut Commensals Degrade Components of the Extracellular Matrix.

Extracellular matrix (ECM) remodeling has emerged as a key feature of inflammatory bowel disease (IBD), and ECM fragments have been proposed as markers of clinical disease severity. Recent studies report increased protease activity in the gut microbiota of IBD patients. Nonetheless, the relationship between gut microbiota and ECM remodeling has remained unexplored. We hypothesized that members of the human gut microbiome could degrade the host ECM and that bacteria-driven remodeling, in turn, could enhance colonic inflammation. Through a variety of in vitro assays, we first confirmed that multiple bacterial species found in the human gut are capable of degrading specific ECM components. Clinical stool samples obtained from ulcerative colitis patients also exhibited higher levels of proteolytic activity in vitro, compared to those of their healthy counterparts. Furthermore, culture supernatants from bacteria species that are capable of degrading human ECM accelerated inflammation in dextran sodium sulfate (DSS)-induced colitis. Finally, we identified several of the bacterial proteases and carbohydrate degrading enzymes (CAZymes) that are potentially responsible for ECM degradation in vitro. Some of these protease families and CAZymes were also found in increased abundance in a metagenomic cohort of IBD. These results demonstrate that some commensal bacteria in the gut are indeed capable of degrading components of human ECM in vitro and suggest that this proteolytic activity may be involved in the progression of IBD. A better understanding of the relationship between nonpathogenic gut microbes, host ECM, and inflammation could be crucial to elucidating some of the mechanisms underlying host-bacteria interactions in IBD and beyond. IMPORTANCE Healthy gut epithelial cells form a barrier that keeps bacteria and other substances from entering the blood or tissues of the body. Those cells sit on scaffolding that maintains the structure of the gut and informs our immune system about the integrity of this barrier. In patients with inflammatory bowel disease (IBD), breaks are formed in this cellular barrier, and bacteria gain access to the underlying tissue and scaffolding. In our study, we discovered that bacteria that normally reside in the gut can modify and disassemble the underlying scaffolding. Additionally, we discovered that changes to this scaffolding affect the onset of IBD in mouse models of colitis as well as the abilities of these mice to recover. We propose that this new information will reveal how breaks in the gut wall lead to IBD and will open up new avenues by which to treat patients with IBD.

Circulating exo-miR-154-5p regulates vascular dementia through endothelial progenitor cell-mediated angiogenesis.

Background: Vascular dementia (VaD) mainly results from cerebral vascular lesions and tissue changes, which contribute to neurodegenerative processes. Effective therapeutic approaches to targeting angiogenesis may reduce mortality of VaD. Endothelial progenitor cells (EPCs) play a key role in postnatal angiogenesis. Many exosomal microRNAs (exo-miRNAs) have been reported to involve in the development of dementia. The present study was designed to investigate whether the expression profile of the exo-miRNAs is significantly altered in patients with VaD and to reveal the function of differentially expressed miRNAs and the relevant mechanisms in EPC-mediated angiogenesis in VaD rat model. Results: Exosomes isolated from serum of patients with VaD (n = 7) and age-matched control subjects (n = 7), and miRNA sequencing and bioinformatics analysis found that circulating exosome miRNA-155-5p, miRNA-154-5p, miR-132-5p, and miR-1294 were upregulated in patients with VaD. The expression of miRNA-154-5p was further verified to be upregulated in clinical samples (n = 23) and 2-vessel occlusion-induced VaD rat model by reverse transcription quantitative PCR (RT-qPCR). Notably, miRNA-154-5p inhibition in bone marrow-EPCs (BM-EPCs) from VaD rats improved EPC functions, including tube formation, migration, and adhesion, and elevated concentrations of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α). The mRNA levels of ICAM-1, VCAM-1, and MCP-1 were reduced in miRNA-154-5p-inhibited EPCs. In addition, miRNA-154-5p inhibition increased the level of superoxide dismutase (SOD), and decreased reactive oxygen species (ROS) in EPCs. PRKAA2 was chosen as a promising target gene of miR-154-5p, and miRNA-154-5p inhibition upregulated the protein expression of AMPKα2. Furthermore, upregulation of miR-154-5p markedly diminished EPC functions and inhibited angiogenesis following EPC transplantation in VaD rats. Conclusion: Circulating exo-miR-154-5p was upregulated in patients with VaD, and miR-154-5p upregulation was associated with impaired EPC functions and angiogenesis in VaD rat model. Therefore, miR-154-5p is a promising biomarker and therapeutic strategy for VaD.

CysLT2R Antagonist HAMI 3379 Ameliorates Post-Stroke Depression through NLRP3 Inflammasome/Pyroptosis Pathway in Gerbils.

Post-stroke depression (PSD) is a kind of prevalent emotional disorder following stroke that usually results in slow functional recovery and even increased mortality. We had reported that the cysteinyl leukotriene receptor 2 (CysLT2R) antagonist HAMI3379 (HM3379) contributes to the improvement of neurological injury. The present study was designed to investigate the role of HM3379 in PSD-induced chronic neuroinflammation and related mechanisms in gerbils. The gerbils were subjected to transient global cerebral ischemia (tGCI) and spatial restraint stress to induce the PSD model. They were randomized to receive the vehicle or HM3379 (0.1 mg/kg, i.p.) for a consecutive 14 days. In the PSD-treated gerbils, HM3379 had noteworthy efficacy in improving the modified neurological severity score (mNSS) and depression-like behaviors, including the sucrose preference test and the forced swim test. HM3379 administration significantly mitigated neuron loss, lessened TUNEL-positive neurons, and reduced the activation of microglia in the cerebral cortex. Importantly, HM3379 downregulated protein expressions of the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome and pyroptosis including NLRP3, cleaved caspase-1, interleukin-1ß (IL-1ß), IL-18, cleaved gasdermin-N domain (GSDMD-N), and apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC). Mechanistically, HM3379 could repress pyroptosis via inhibiting NLRP3 inflammasome activation under oxygen-glucose deprivation (OGD) stimulation. Knockdown of CysLT2R by short hairpin RNA (shRNA) or overexpression of CysLT2R by lentivirus (LV)-CysLT2R could abolish or restore the anti-depression effect of HM3379. Our results demonstrated that the selective CysLT2R antagonist HM3379 has beneficial effects on PSD, partially by suppressing the NLRP3 inflammasome/pyroptosis pathway.

Sclareol ameliorates hyperglycemia-induced renal injury through inhibiting the MAPK/NF-κB signaling pathway.

Diabetic nephropathy (DN) represents the most serious complication of diabetes. Previous studies have shown that the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) are linked to inflammation in the development of DN. Sclareol, a natural diterpene compound, has beneficial effects on inflammation. Thus, we hypothesized that sclareol might prevent DN via anti-inflammatory actions. This study aimed to investigate the actions of sclareol in the progression of DN, and explored the related molecular mechanism. Sclareol treatment significantly alleviated renal dysfunction, fibrosis, and inflammatory cytokine levels in a dose-dependent manner in diabetic mice. Moreover, sclareol inhibited the activations of MAPKs and NF-κB in diabetic kidney tissues. The therapeutic effects of sclareol were confirmed under high levels of glucose in SV40 cells, and sclareol prevented high glucose-induced fibrosis and inflammatory responses, which was largely driven by MAPKs and NF-κB inhibitions. In particular, MAPKs inhibitors mixture could suppress the NF-κB pathway and release of inflammatory cytokines that sclareol was involved in. In conclusion, sclareol has benefits for diabetes-induced renal dysfunction, which was partially associated with amelioration of fibrosis and inflammation via mediation of the MAPK/NF-κB signaling pathway. Sclareol may be a promising agent for preventing the progression of DN.

Geographic differences in gut microbiota composition impact susceptibility to enteric infection.

Large-scale studies of human gut microbiomes have revealed broad differences in composition across geographically distinct populations. Yet, studies examining impacts of microbiome composition on various health outcomes typically focus on single populations, posing the question of whether compositional differences between populations translate into differences in susceptibility. Using germ-free mice humanized with microbiome samples from 30 donors representing three countries, we observe robust differences in susceptibility to Citrobacter rodentium, a model for enteropathogenic Escherichia coli infections, according to geographic origin. We do not see similar responses to Listeria monocytogenes infections. We further find that cohousing the most susceptible and most resistant mice confers protection from C. rodentium infection. This work underscores the importance of increasing global participation in microbiome studies related to health outcomes. Diverse cohorts are needed to identify both population-specific responses to specific microbiome interventions and to achieve broader-reaching biological conclusions that generalize across populations.

A multifaceted cellular damage repair and prevention pathway promotes high-level tolerance to ß-lactam antibiotics.

Bactericidal antibiotics are powerful agents due to their ability to convert essential bacterial functions into lethal processes. However, many important bacterial pathogens are remarkably tolerant against bactericidal antibiotics due to inducible damage repair responses. The cell wall damage response two-component system VxrAB of the gastrointestinal pathogen Vibrio cholerae promotes high-level ß-lactam tolerance and controls a gene network encoding highly diverse functions, including negative control over multiple iron uptake systems. How this system contributes to tolerance is poorly understood. Here, we show that ß-lactam antibiotics cause an increase in intracellular free iron levels and collateral oxidative damage, which is exacerbated in the ∆vxrAB mutant. Mutating major iron uptake systems dramatically increases ∆vxrAB tolerance to ß-lactams. We propose that VxrAB reduces antibiotic-induced toxic iron and concomitant metabolic perturbations by downregulating iron uptake transporters and show that iron sequestration enhances tolerance against ß-lactam therapy in a mouse model of cholera infection. Our results suggest that a microorganism's ability to counteract diverse antibiotic-induced stresses promotes high-level antibiotic tolerance and highlights the complex secondary responses elicited by antibiotics.

Obesity and load-induced posttraumatic osteoarthritis in the absence of fracture or surgical trauma.

Osteoarthritis is increasingly viewed as a heterogeneous disease with multiple phenotypic subgroups. Obesity enhances joint degeneration in mouse models of posttraumatic osteoarthritis (PTOA). Most models of PTOA involve damage to surrounding tissues caused by surgery/fracture; it is unclear if obesity enhances cartilage degeneration in the absence of surgery/fracture. We used a nonsurgical animal model of load-induced PTOA to determine the effect of obesity on cartilage degeneration 2 weeks after loading. Cartilage degeneration was caused by a single bout of cyclic tibial loading at either a high or moderate load magnitude in adult male mice with severe obesity (C57Bl6/J + high-fat diet), mild obesity (toll-like receptor 5 deficient mouse [TLR5KO]), or normal adiposity (C57Bl6/J mice + normal diet and TLR5KO mice in which obesity was prevented by manipulation of the gut microbiome). Two weeks after loading, cartilage degeneration occurred in limbs loaded at a high magnitude, as determined by OARSI scores (P < .001). However, the severity of cartilage damage did not differ among groups. Osteophyte width and synovitis of loaded limbs did not differ among groups. Furthermore, obesity did not enhance cartilage damage in limbs evaluated 6 weeks after loading. Constituents of the gut microbiota differed among groups. Our findings suggest that, in the absence of surgery/fracture, obesity may not influence cartilage loss after a single mechanical insult, suggesting that either damage to surrounding tissues or repeated mechanical insult is necessary for obesity to influence cartilage degeneration. These findings further illustrate heterogeneity in PTOA phenotypes and complex interactions between mechanical/metabolic factors in cartilage loss.

Highly multiplexed spatial mapping of microbial communities.

Mapping the complex biogeography of microbial communities in situ with high taxonomic and spatial resolution poses a major challenge because of the high density1 and rich diversity2 of species in environmental microbiomes and the limitations of optical imaging technology3-6. Here we introduce high-phylogenetic-resolution microbiome mapping by fluorescence in situ hybridization (HiPR-FISH), a versatile technology that uses binary encoding, spectral imaging and decoding based on machine learning to create micrometre-scale maps of the locations and identities of hundreds of microbial species in complex communities. We show that 10-bit HiPR-FISH can distinguish between 1,023 isolates of Escherichia coli, each fluorescently labelled with a unique binary barcode. HiPR-FISH, in conjunction with custom algorithms for automated probe design and analysis of single-cell images, reveals the disruption of spatial networks in the mouse gut microbiome in response to treatment with antibiotics, and the longitudinal stability of spatial architectures in the human oral plaque microbiome. Combined with super-resolution imaging, HiPR-FISH shows the diverse strategies of ribosome organization that are exhibited by taxa in the human oral microbiome. HiPR-FISH provides a framework for analysing the spatial ecology of environmental microbial communities at single-cell resolution.

[Effects of antihyperglycemics on endothelial progenitor cells].

Endothelial progenitor cells (EPCs) play an important role in diabetic vascular complications. A large number of studies have revealed that some clinical antihyperglycemics can improve the complications of diabetes by regulating the function of EPCs. Metformin can improve EPCs function in diabetic patients by regulating oxidative stress level or downstream signaling pathway of adenosine monophosphate activated protein kinase; Pioglitazone can delay the aging of EPCs by regulating telomerase activity; acarbose, sitagliptin and insulin can promote the proliferation, migration and adhesion of EPCs. In addition to lowering blood glucose, the effects of antihyperglycemics on EPCs may also be one of the mechanisms to improve the complications of diabetes. This article reviews the research progress on the regulation of EPC proliferation and function by antihyperglycemics.

Widespread transfer of mobile antibiotic resistance genes within individual gut microbiomes revealed through bacterial Hi-C.

The gut microbiome harbors a 'silent reservoir' of antibiotic resistance (AR) genes that is thought to contribute to the emergence of multidrug-resistant pathogens through horizontal gene transfer (HGT). To counteract the spread of AR, it is paramount to know which organisms harbor mobile AR genes and which organisms engage in HGT. Despite methods that characterize the overall abundance of AR genes in the gut, technological limitations of short-read sequencing have precluded linking bacterial taxa to specific mobile genetic elements (MGEs) encoding AR genes. Here, we apply Hi-C, a high-throughput, culture-independent method, to surveil the bacterial carriage of MGEs. We compare two healthy individuals with seven neutropenic patients undergoing hematopoietic stem cell transplantation, who receive multiple courses of antibiotics, and are acutely vulnerable to the threat of multidrug-resistant infections. We find distinct networks of HGT across individuals, though AR and mobile genes are associated with more diverse taxa within the neutropenic patients than the healthy subjects. Our data further suggest that HGT occurs frequently over a several-week period in both cohorts. Whereas most efforts to understand the spread of AR genes have focused on pathogenic species, our findings shed light on the role of the human gut microbiome in this process.

Protective effects of acarbose against insulitis in multiple low-dose streptozotocin-induced diabetic mice.

AIMS: The development of type 1 diabetes is associated with inflammatory lesion of the pancreatic islets, known as insulitis. In this study, we focused on the protective effects of acarbose against insulitis in streptozotocin (STZ)-induced diabetic mice and the underlying mechanisms. MAIN METHODS: The mouse models were established via intraperitoneal injection of multiple low-dose STZ. Blood glucose level and body weight were measured. The severity of insulitis and inflammatory parameters in pancreatic tissues were evaluated. Insulin levels in pancreas and serum were also assessed. In vitro, MIN6 ß cells were exposed to pro-inflammatory cytokines to assess the protective effects of acarbose. Cell function and apoptosis were evaluated. KEY FINDINGS: We found that acarbose administration by gavage reduced the severity of insulitis and improved insulin levels in the experimental diabetic mice. ELISA revealed decreased levels of the inflammatory response markers IL-1ß and TNF-α in mouse pancreatic tissues following acarbose treatment. In vitro, acarbose increased cell viability, decreased cell apoptosis, and improved GSIS in MIN6 ß cells exposed to pro-inflammatory cytokines. In addition, caspase-3 level and p-p53/p53 ratio in ß cells were reduced by acarbose treatment. SIGNIFICANCE: Taken together, these results revealed a novel function of acarbose in attenuating insulitis. The protective effects of acarbose elicited in vitro and in vivo were shown to be mediated, at least in part, through its anti-inflammatory action.

Rosiglitazone accelerates wound healing by improving endothelial precursor cell function and angiogenesis in db/db mice.

BACKGROUND & AIMS: Endothelial precursor cell (EPC) dysfunction is one of the risk factors for diabetes mellitus (DM) which results in delayed wound healing. Rosiglitazone (RSG) is a frequently prescribed oral glucose-lowering drug. Previous studies have shown the positive effects of RSG on ameliorating EPC dysfunction in diabetic patients. Interestingly, knowledge about RSG with regard to the wound healing process caused by DM is scarce. Therefore, in this study, we investigated the possible actions of RSG on wound healing and the related mechanisms involved in db/db diabetic mice. METHODS: Db/db mice with spontaneous glucose metabolic disorder were used as a type 2 DM model. RSG (20 mg/kg/d, i.g.,) was administered for 4 weeks before wound creation and bone marrow derived EPC (BM-EPC) isolation. Wound closure was assessed by wound area and CD31 staining. Tubule formation and migration assays were used to judge the function of the BM-EPCs. The level of vascular endothelial growth factor (VEGF), stromal cell derived factor-1α (SDF-1α) and insulin signaling was determined by ELISA. Cell viability of the BM-EPCs was measured by CCK-8 assay. RESULTS: RSG significantly accelerated wound healing and improved angiogenesis in db/db mice. Bioactivities of tube formation and migration were decreased in db/db mice but were elevated by RSG. Level of both VEGF and SDF-1α was increased by RSG in the BM-EPCs of db/db mice. Insulin signaling was elevated by RSG reflected in the phosphorylated-to-total AKT in the BM-EPCs. In vitro, RSG improved impaired cell viability and tube formation of BM-EPCs induced by high glucose, but this was prevented by the VEGF inhibitor avastin. CONCLUSION: Our data demonstrates that RSG has benefits for wound healing and angiogenesis in diabetic mice, and was partially associated with improvement of EPC function through activation of VEGF and stimulation of SDF-1α in db/db mice.

Nicotinamide riboside exerts protective effect against aging-induced NAFLD-like hepatic dysfunction in mice.

BACKGROUND & AIMS: Aging is one of the risk factors of non-alcoholic fatty liver disease (NAFLD). Yet, the mechanism underlying the aging-associated NAFLD-like syndrome is not fully understood. Nicotinamide adenine dinucleotide (NAD), a ubiquitous coenzyme, has protective effects against aging. Here, we investigated the actions of NAD precursors nicotinamide riboside (NR) on the development of aging-induced NAFLD. METHODS: NR supplemented food (2.5 g/kg food) was applied to aged mice for three months while normal chow to the other groups. Body weight, food intake, liver weight and fat pat mass were measured. The serum concentrations of lipid content, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and NAD were determined by biochemical assays. Pathological assessment and immunohistochemistry analysis of hepatic tissues were used to evaluate the effect of NR on NAFLD development and inflammatory infiltration. RESULTS: NR repletion significantly reduced fat pat mass in aged mice, while not altered the body weight, food intake, and liver weight. NR repletion significantly rescued the NAD reduction in aged mice. The total cholesterol and triglyceride levels could be lowered by NR repletion in aged mice. The AST level was also significantly reduced by NR repletion in aged group, while the ALT level lowered but without significance. Notably, moderate NAFLD phenotypes, including steatosis and hepatic fibrosis could be markedly corrected by NR repletion. In addition, Kupffer cells accumulated and inflammatory infiltration could also be remarkably reversed by NR repletion in aged mice. CONCLUSION: Aging was associated with NAFLD-like phenotypes in mice, which could be reversed by oral NR repletion. Therefore, oral NR uptake might be a promising strategy to halt the progression of NAFLD.