RESUMEN
Exposure of the Gram-negative pathogen Pseudomonas aeruginosa to subinhibitory concentrations of antibiotics increases the formation of biofilms. We exploited this phenotype to identify molecules with potential antimicrobial activity in a biofilm-based high-throughput screen. The anti-inflammatory compound BAY 11-7082 induced dose-dependent biofilm stimulation, indicative of antibacterial activity. We confirmed that BAY 11-7082 inhibits the growth of P. aeruginosa and other priority pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). We synthesized 27 structural analogues, including a series based on the related scaffold 3-(phenylsulfonyl)-2-pyrazinecarbonitrile (PSPC), 10 of which displayed increased anti-Staphylococcal activity. Because the parent molecule inhibits the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome, we measured the ability of select analogues to reduce interleukin-1ß (IL-1ß) production in mammalian macrophages, identifying minor differences in the structure-activity relationship for the anti-inflammatory and antibacterial properties of this scaffold. Although we could evolve stably resistant MRSA mutants with cross-resistance to BAY 11-7082 and PSPC, their lack of shared mutations suggested that the two molecules could have multiple targets. Finally, we showed that BAY 11-7082 and its analogues synergize with penicillin G against MRSA, suggesting that this scaffold may serve as an interesting starting point for the development of antibiotic adjuvants.
Asunto(s)
Antibacterianos , Staphylococcus aureus Resistente a Meticilina , Animales , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Pruebas de Sensibilidad Microbiana , Nitrilos , Sulfonas/farmacologíaRESUMEN
Lipopolysaccharides (LPSs) can promote metabolic endotoxemia, which is considered inflammatory and metabolically detrimental based on Toll-like receptor (TLR)4 agonists, such as Escherichia coli-derived LPS. LPSs from certain bacteria antagonize TLR4 yet contribute to endotoxemia measured by endotoxin units (EUs). We found that E. coli LPS impairs gut barrier function and worsens glycemic control in mice, but equal doses of LPSs from other bacteria do not. Matching the LPS dose from R. sphaeroides and E. coli by EUs reveals that only E. coli LPS promotes dysglycemia and adipose inflammation, delays intestinal glucose absorption, and augments insulin and glucagon-like peptide (GLP)-1 secretion. Metabolically beneficial endotoxemia promoted by R. sphaeroides LPS counteracts dysglycemia caused by an equal dose of E. coli LPS and improves glucose control in obese mice. The concept of metabolic endotoxemia should be expanded beyond LPS load to include LPS characteristics, such as lipid A acylation, which dictates the effect of metabolic endotoxemia.
Asunto(s)
Endotoxemia/etiología , Intestinos/efectos de los fármacos , Lipopolisacáridos/farmacología , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Animales , Glucemia/análisis , Peso Corporal/efectos de los fármacos , Endotoxemia/metabolismo , Escherichia coli/metabolismo , Péptido 1 Similar al Glucagón/sangre , Glucosa/metabolismo , Insulina/sangre , Intestinos/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Obesidad/metabolismo , Obesidad/patología , Peptidoglicano/farmacología , Rhodobacter sphaeroides/metabolismo , Receptor Toll-Like 4/agonistas , Receptor Toll-Like 4/metabolismoRESUMEN
Obesity associates with inflammation, insulin resistance, and higher blood lipids. It is unclear if immune responses facilitate lipid breakdown and release from adipocytes via lipolysis in a separate way from hormones or adrenergic signals. We found that an ancient component of ER stress, inositol-requiring protein 1 (IRE1), discriminates inflammation-induced adipocyte lipolysis versus lipolysis from adrenergic or hormonal stimuli. Our data show that inhibiting IRE1 kinase activity was sufficient to block adipocyte-autonomous lipolysis from multiple inflammatory ligands, including bacterial components, certain cytokines, and thapsigargin-induced ER stress. IRE1-mediated lipolysis was specific for inflammatory triggers since IRE1 kinase activity was dispensable for isoproterenol and cAMP-induced lipolysis in adipocytes and mouse adipose tissue. IRE1 RNase activity was not associated with inflammation-induced adipocyte lipolysis. Inhibiting IRE1 kinase activity blocked NF-κB activation, interleukin-6 secretion, and adipocyte-autonomous lipolysis from inflammatory ligands. Inflammation-induced lipolysis mediated by IRE1 occurred independently from changes in insulin signaling in adipocytes, suggesting that inflammation can promote IRE1-mediated lipolysis independent of adipocyte insulin resistance. We found no role for canonical unfolded protein responses or ABL kinases in linking ER stress to IRE1-mediated lipolysis. Adiponectin-Cre-mediated IRE1 knockout in mice showed that adipocyte IRE1 was required for inflammatory ligand-induced lipolysis in adipose tissue explants and that adipocyte IRE1 was required for approximately half of the increase in blood triglycerides after a bacterial endotoxin-mediated inflammatory stimulus in vivo. Together, our results show that IRE1 propagates an inflammation-specific lipolytic program independent from hormonal or adrenergic regulation. Targeting IRE1 kinase activity may benefit metabolic syndrome and inflammatory lipid disorders.
Asunto(s)
Adipocitos/metabolismo , Lipólisis/fisiología , Proteínas de la Membrana/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Células 3T3-L1 , Adipocitos/fisiología , Tejido Adiposo/metabolismo , Animales , Citocinas/metabolismo , Inflamación/metabolismo , Insulina/metabolismo , Resistencia a la Insulina/fisiología , Macrófagos/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/fisiología , Ratones , FN-kappa B/metabolismo , Obesidad/metabolismo , Fosforilación , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/fisiología , Transducción de SeñalRESUMEN
OBJECTIVE: Hyperinsulinemia can be both a cause and consequence of obesity and insulin resistance. Hyperinsulinemia can result from increased insulin secretion and/or reduced insulin clearance. While many studies have focused on mechanisms triggering insulin secretion during obesity, the triggers for changes in insulin clearance during obesity are less defined. In this study, we investigated the role of the microbiota in regulating insulin clearance during diet-induced obesity. METHODS: Blood glucose and insulin clearance were tested in conventional male mice treated with antibiotics and germ-free mice colonized with microbes from mice that were fed a control (chow) diet or an obesogenic high-fat diet (HFD). The composition of the fecal microbiota was analyzed using 16S rRNA sequencing. RESULTS: Short-term HFD feeding and aging did not alter insulin clearance in the mice. Oral antibiotics mitigated impaired blood insulin clearance in the mice fed an HFD for 12 weeks or longer. Germ-free mice colonized with microbes from HFD-fed donor mice had impaired insulin but not C-peptide clearance. Microbe-transmissible insulin clearance impairment was only observed in germ-free mice after more than 6 weeks post-colonization upon HFD feeding. Five bacterial taxa predicted >90% of the variance in insulin clearance. Mechanistically, impaired insulin clearance was associated with lower levels of hepatic Ceacam-1 but increased liver and skeletal muscle insulin-degrading enzyme (IDE) activity. CONCLUSIONS: Gut microbes regulate insulin clearance during diet-induced obesity. A small cluster of microbes or their metabolites may be targeted for mitigating defects in insulin clearance and hyperinsulinemia during the progression of obesity and type 2 diabetes.
Asunto(s)
Microbioma Gastrointestinal/fisiología , Insulina/metabolismo , Obesidad/microbiología , Animales , Glucemia/metabolismo , Dieta Alta en Grasa , Heces/microbiología , Glucosa/metabolismo , Hiperinsulinismo/metabolismo , Resistencia a la Insulina/fisiología , Hígado/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Obesidad/metabolismo , ARN Ribosómico 16SRESUMEN
Obesity promotes nonalcoholic fatty liver disease (NAFLD). The intestinal microbiota contributes to NAFLD progression through a gut-to-liver pathway that promotes inflammation and fibrosis. Gut microbiota-derived factors can travel to the liver and activate immune responses in liver resident cells to promote inflammation and NAFLD. Little is known about bacterial sensors or immune responses that can protect against NAFLD. We tested whether the bacterial cell wall sensor nucleotide-binding oligomerization domain-containing (NOD)2 protects against diet-induced NAFLD in mice. Whole body deletion of NOD2 exacerbated liver steatosis and fibrosis in mice fed a NAFLD-promoting diet. Mice with a hepatocyte-specific deletion of NOD2 (Nod2-/-HKO) also had higher liver steatosis and fibrosis compared with littermate wild-type mice (WT) fed a NAFLD-promoting diet. Hepatocyte-specific NOD2 deletion altered the composition of the gut microbiome. Nod2-/-HKO mice had increased relative abundance of Clostridiales and lower Erysipelotrichaceae among other changes in cecal bacteria compared with littermate WT mice. Hepatocyte-specific NOD2 deletion altered a transcriptional program of liver inflammation, metabolism, and fibrosis. Nod2-/-HKO mice had higher levels of transcripts involved in lipid and cholesterol metabolism. Nod2-/-HKO mice had higher transcript levels of transforming growth factor-ß and collagen isoforms, which coincided with higher levels of liver collagen compared with WT mice. These data show that bacterial cell wall sensing within hepatocytes can engage retrograde cross-talk from the liver to the gut, where liver immunity communicates with the gut to influence the intestinal host-microbe relationship during diet-induced NAFLD, and NOD2 within the hepatocyte confers protection from liver steatosis and fibrosis.
Asunto(s)
Disbiosis/fisiopatología , Microbioma Gastrointestinal/fisiología , Cirrosis Hepática/fisiopatología , Hígado/fisiopatología , Proteína Adaptadora de Señalización NOD2/fisiología , Enfermedad del Hígado Graso no Alcohólico/fisiopatología , Animales , Dieta , Disbiosis/prevención & control , Hepatocitos/química , Hepatocitos/fisiología , Cirrosis Hepática/etiología , Cirrosis Hepática/prevención & control , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteína Adaptadora de Señalización NOD2/deficiencia , Enfermedad del Hígado Graso no Alcohólico/etiología , Enfermedad del Hígado Graso no Alcohólico/prevención & control , Receptor Cross-TalkRESUMEN
Statins lower cholesterol and risk of cardiovascular disease. Statins can increase blood glucose and risk of new-onset diabetes. It is unclear why statins can have opposing effects on lipids versus glucose. Statins have cholesterol-independent pleiotropic effects that influence both insulin and glucose control. Statin lowering of isoprenoids required for protein prenylation promotes pancreatic ß-cell dysfunction and adipose tissue insulin resistance. Protein prenylation influences immune function and statin-mediated adipose tissue insulin resistance involves the NLR family pyrin domain-containing 3 (NLRP3) inflammasome and IL-1ß. However, the intracellular cues that statins engage to activate the NLRP3 inflammasome and those responsible for IL-1ß-mediated insulin resistance in adipose tissue have not been identified. We hypothesized that stress kinases or components of the insulin signaling pathway mediated statin-induced insulin resistance. We tested the associations of p38, ERK, JNK, phosphatase, and tensin homolog (PTEN), and mTOR in statin-exposed adipose tissue from WT and IL-1ß-/- mice. We found that statins increased phosphorylation of p38 in WT and IL-1ß-/- mice. Statin activation of p38 upstream of IL-1ß led to priming of this NLRP3 inflammasome effector in macrophages. We found that mTORC1 inhibition with low doses of rapamycin (2 or 20 nM) lowered macrophage priming of IL-1ß mRNA and secretion of IL-1ß caused by multiple statins. Rapamycin (20 nM) or the rapalog everolimus (20 nM) prevented atorvastatin-induced lowering of insulin-mediated phosphorylation of Akt in mouse adipose tissue. These results position p38 and mTOR as mediators of statin-induced insulin resistance in adipose tissue and highlight rapalogs as candidates to mitigate the insulin resistance and glycemic side effects of statins.
Asunto(s)
Atorvastatina/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Inflamasomas/efectos de los fármacos , Resistencia a la Insulina , Insulina/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/efectos de los fármacos , Serina-Treonina Quinasas TOR/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/efectos de los fármacos , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Animales , Inflamasomas/metabolismo , Interleucina-1beta/genética , MAP Quinasa Quinasa 4/efectos de los fármacos , MAP Quinasa Quinasa 4/metabolismo , Ratones , Ratones Noqueados , Proteína Quinasa 1 Activada por Mitógenos/efectos de los fármacos , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/efectos de los fármacos , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Fosfohidrolasa PTEN/efectos de los fármacos , Fosfohidrolasa PTEN/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Adipose tissue regulates metabolic homeostasis by participating in endocrine and immune responses in addition to storing and releasing lipids from adipocytes. Obesity skews adipose tissue adipokine responses and degrades the coordination of adipocyte lipogenesis and lipolysis. These defects in adipose tissue metabolism can promote ectopic lipid deposition and inflammation in insulin-sensitive tissues such as skeletal muscle and liver. Sustained caloric excess can expand white adipose tissue to a point of maladaptation exacerbating both local and systemic inflammation. Multiple sources, instigators and propagators of adipose tissue inflammation occur during obesity. Cross-talk between professional immune cells (i.e. macrophages) and metabolic cells (i.e. adipocytes) promote adipose tissue inflammation during metabolic stress (i.e. metaflammation). Metabolic stress and endogenous danger signals can engage pathogen recognition receptors (PRRs) of the innate immune system thereby activating pro-inflammatory and stress pathways in adipose tissue. The Nod-like receptor protein 3 (NLRP3) inflammasome can act as a metabolic danger sensor to a wide range of pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Activation of the NLRP3 inflammasome facilitates caspase-1 dependent production of the pro-inflammatory cytokines IL-1ß and IL-18. Activation of the NLRP3 inflammasome can promote inflammation and pyroptotic cell death, but caspase-1 is also involved in adipogenesis. This review discusses the role of the NLRP3 inflammasome in adipose tissue immunometabolism responses relevant to metabolic disease. Understanding the potential sources of NLRP3 activation and consequences of NLRP3 effectors may reveal therapeutic opportunities to break or fine-tune the connection between metabolism and inflammation in adipose tissue during obesity.
Asunto(s)
Tejido Adiposo/metabolismo , Metabolismo Energético/fisiología , Inflamasomas/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Adipocitos/metabolismo , Animales , Humanos , Resistencia a la Insulina/fisiología , Obesidad/metabolismoRESUMEN
Defining the host receptors and metabolic consequences of bacterial components can help explain how the microbiome influences metabolic diseases. Bacterial peptidoglycans that activate nucleotide-binding oligomerization domain-containing (NOD)1 worsen glucose control, whereas NOD2 activation improves glycemia. Receptor-interacting serine/threonine-protein kinase 2 (RIPK2) is required for innate immunity instigated by NOD1 and NOD2. The role of RIPK2 in the divergent effects of NOD1 versus NOD2 on blood glucose was unknown. We found that whole body deletion of RIPK2 negated all effects of NOD1 or NOD2 activation on blood glucose during an acute, low level endotoxin challenge in mice. It was known that NOD1 in hematopoietic cells participates in insulin resistance and metabolic inflammation in obese mice. It was unknown if RIPK2 in hematopoietic cells is required for the glucose-lowering and anti-inflammatory effects of NOD2 activation. We hypothesized that RIPK2 in nonhematopoietic cells dictated the glycemic effects of NOD2 activation. We found that whole body deletion of RIPK2 prevented the glucose-lowering effects of repeated NOD2 activation that were evident during a glucose tolerance test (GTT) in high-fat diet (HFD)-fed wild-type (WT) mice. NOD2 activation lowered glucose during a GTT and lowered adipose tissue inflammation in mice with RIPK2 deleted in hematopoietic cells. We conclude that RIPK2 in nonhematopoietic cells mediates the glucose lowering and anti-inflammatory effects of NOD2-activating postbiotics. We propose a model where lipopolysaccharides and NOD1 ligands synergize in hematopoietic cells to promote insulin resistance but NOD2 activation in nonhematopoietic cells promotes RIPK2-dependent immune tolerance and lowering of inflammation and insulin resistance.
Asunto(s)
Glucemia/metabolismo , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Microbiota , Proteína Adaptadora de Señalización NOD2/metabolismo , Proteína Serina-Treonina Quinasa 2 de Interacción con Receptor/metabolismo , Activación Metabólica , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Animales , Dieta Alta en Grasa , Prueba de Tolerancia a la Glucosa , Células Madre Hematopoyéticas/efectos de los fármacos , Células Madre Hematopoyéticas/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Obesos , Proteína Adaptadora de Señalización NOD1/metabolismo , Proteína Serina-Treonina Quinasa 2 de Interacción con Receptor/genéticaRESUMEN
Statins lower cholesterol and adverse cardiovascular outcomes, but this drug class increases diabetes risk. Statins are generally anti-inflammatory. However, statins can promote inflammasome-mediated adipose tissue inflammation and insulin resistance through an unidentified immune effector. Statins lower mevalonate pathway intermediates beyond cholesterol, but it is unknown whether lower cholesterol underpins statin-mediated insulin resistance. We sought to define the mevalonate pathway metabolites and immune effectors that propagate statin-induced adipose insulin resistance. We found that LDL cholesterol lowering was dispensable, but statin-induced lowering of isoprenoids required for protein prenylation triggered NLRP3/caspase-1 inflammasome activation and interleukin-1ß (IL-1ß)-dependent insulin resistance in adipose tissue. Multiple statins impaired insulin action at the level of Akt/protein kinase B signaling in mouse adipose tissue. Providing geranylgeranyl isoprenoids or inhibiting caspase-1 prevented statin-induced defects in insulin signaling. Atorvastatin (Lipitor) impaired insulin signaling in adipose tissue from wild-type and IL-18-/- mice, but not IL-1ß-/- mice. Atorvastatin decreased cell-autonomous insulin-stimulated lipogenesis but did not alter lipolysis or glucose uptake in 3T3-L1 adipocytes. Our results show that statin lowering of prenylation isoprenoids activates caspase-1/IL-1ß inflammasome responses that impair endocrine control of adipocyte lipogenesis. This may allow the targeting of cholesterol-independent statin side effects on adipose lipid handling without compromising the blood lipid/cholesterol-lowering effects of statins.
Asunto(s)
Tejido Adiposo/metabolismo , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Insulina/farmacología , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Tejido Adiposo/efectos de los fármacos , Animales , Atorvastatina/efectos adversos , Caspasa 1/metabolismo , Inflamasomas/efectos de los fármacos , Inflamasomas/metabolismo , Resistencia a la Insulina , Interleucina-1beta/metabolismo , Lipogénesis/efectos de los fármacos , Masculino , Ácido Mevalónico/metabolismo , Ratones , Ratones Mutantes , Prenilación/efectos de los fármacosRESUMEN
Inflammation underpins aspects of insulin resistance and dysglycemia. Microbiota-derived cell wall components such as muropeptides or endotoxin can trigger changes in host immunity and metabolism. Specific peptidoglycan motifs promote metabolic tissue inflammation, lipolysis and insulin resistance via Nucleotide-binding oligomerization domain-containing protein 1 (Nod1). Receptor-interacting serine/threonine-protein kinase 2 (Ripk2) mediates Nod1-induced immunity, but the role of Ripk2 in metabolism is ill-defined. We hypothesized that Ripk2 was required for Nod1-mediated inflammation, lipolysis and dysglycemia. This is relevant because certain tyrosine kinase inhibitors (TKIs) inhibit Ripk2 and there is clinical evidence of TKIs lowering inflammation and blood glucose. Here, we showed that only a subset of TKIs known to inhibit Ripk2 attenuated Nod1 ligand-mediated adipocyte lipolysis. TKIs that inhibit Ripk2 decreased cytokine responses induced by Nod1-activating peptidoglycan, but not endotoxin in both metabolic and immune cells. Pre-treatment of adipocytes or macrophages with the TKI gefitinib inhibited Nod1-induced Cxcl1 and Il-6 secretion. Furthermore, treatment of mice with gefitinib prevented Nod1-induced glucose intolerance in vivo. Ripk2 was required for these effects on inflammation and metabolism, since Nod1-mediated cytokine and blood glucose changes were absent in Ripk2-/- mice. Our data show that specific TKIs used in cancer also inhibit Nod1-Ripk2 immunometabolism responses indicative of metabolic disease.
Asunto(s)
Glucemia/metabolismo , Pared Celular/metabolismo , Inflamación/patología , Lipólisis/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Proteína Serina-Treonina Quinasas de Interacción con Receptores/antagonistas & inhibidores , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Animales , Citocinas/metabolismo , Endotoxinas , Gefitinib/farmacología , Resistencia a la Insulina , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Macrófagos/patología , Ratones , Ratones Endogámicos C57BL , Modelos Biológicos , FN-kappa B/metabolismo , Péptidos/metabolismo , Proteína Serina-Treonina Quinasa 2 de Interacción con Receptor , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismoRESUMEN
Intestinal dysbiosis contributes to obesity and insulin resistance, but intervening with antibiotics, prebiotics, or probiotics can be limited by specificity or sustained changes in microbial composition. Postbiotics include bacterial components such as lipopolysaccharides, which have been shown to promote insulin resistance during metabolic endotoxemia. We found that bacterial cell wall-derived muramyl dipeptide (MDP) is an insulin-sensitizing postbiotic that requires NOD2. Injecting MDP lowered adipose inflammation and reduced glucose intolerance in obese mice without causing weight loss or altering the composition of the microbiome. MDP reduced hepatic insulin resistance during obesity and low-level endotoxemia. NOD1-activating muropeptides worsened glucose tolerance. IRF4 distinguished opposing glycemic responses to different types of peptidoglycan and was required for MDP/NOD2-induced insulin sensitization and lower metabolic tissue inflammation during obesity and endotoxemia. IRF4 was dispensable for exacerbated glucose intolerance via NOD1. Mifamurtide, an MDP-based drug with orphan drug status, was an insulin sensitizer at clinically relevant doses in obese mice.
Asunto(s)
Acetilmuramil-Alanil-Isoglutamina/inmunología , Resistencia a la Insulina , Factores Reguladores del Interferón/inmunología , Obesidad/complicaciones , Obesidad/microbiología , Animales , Endotoxemia/complicaciones , Endotoxemia/inmunología , Endotoxemia/microbiología , Inflamación/complicaciones , Inflamación/inmunología , Inflamación/microbiología , Ratones Endogámicos C57BL , Ratones Obesos , Microbiota , Proteína Adaptadora de Señalización NOD1/inmunología , Proteína Adaptadora de Señalización NOD2/inmunología , Obesidad/inmunologíaRESUMEN
Those with diabetes invariably develop complications including cardiovascular disease (CVD). To reduce their CVD risk, diabetics are generally prescribed cholesterol-lowering 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors (i.e., statins). Statins inhibit cholesterol biosynthesis, but also reduce the synthesis of a number of mevalonate pathway intermediates, leading to several cholesterol-independent effects. One of the pleiotropic effects of statins is the reduction of the anti-fibrinolytic hormone plasminogen activator inhibitor-1 (PAI-1). We have previously demonstrated that a PAI-1 specific inhibitor alleviated diabetes-induced delays in skin and muscle repair. Here we tested if statin administration, through its pleiotropic effects on PAI-1, could improve skin and muscle repair in a diabetic rodent model. Six weeks after diabetes onset, adult male streptozotocin-induced diabetic (STZ), and WT mice were assigned to receive control chow or a diet enriched with 600 mg/kg Fluvastatin. Tibialis anterior muscles were injured via Cardiotoxin injection to induce skeletal muscle injury. Punch biopsies were administered on the dorsal scapular region to induce injury of skin. Twenty-four days after the onset of statin therapy (10 days post-injury), tissues were harvested and analyzed. PAI-1 levels were attenuated in statin-treated diabetic tissue when compared to control-treated tissue, however no differences were observed in non-diabetic tissue as a result of treatment. Muscle and skin repair were significantly attenuated in Fluvastatin-treated STZ-diabetic mice as demonstrated by larger wound areas, less mature granulation tissue, and an increased presence of smaller regenerating muscle fibers. Despite attenuating PAI-1 levels in diabetic tissue, Fluvastatin treatment impaired cutaneous healing and skeletal muscle repair in STZ-diabetic mice.
RESUMEN
Statins lower cholesterol and are commonly prescribed for prevention and treatment of cardiovascular disease risk. Statins have pleotropic actions beyond cholesterol lowering, including decreased protein prenylation, which can alter immune function. The general anti-inflammatory effect of statins may be a key pleiotropic effect that improves cardiovascular disease risk. However, a series of findings have shown that statins increase the pro-inflammatory cytokine, IL-1ß, via decreased protein prenylation in immune cells. IL-1ß can be regulated by the NLRP3 inflammasome containing caspase-1. Statins have been associated with an increased risk of new onset diabetes. Inflammation can promote ineffective insulin action (insulin resistance), which often precedes diabetes. This review highlights the links between statins, insulin resistance and immunity via the NLRP3 inflammasome. We propose that statin-induced changes in immunity should be investigated as a mechanism underlying increased risk of diabetes. It is possible that statin-related insulin resistance occurs through a separate pathway from various mechanisms that confer cardiovascular benefits. Therefore, understanding the potential mechanisms that segregate statin-induced cardiovascular effects from those that cause dysglycemia may lead to improvements in this drugs class.
RESUMEN
Pattern recognition receptors link metabolite and bacteria-derived inflammation to insulin resistance during obesity. We demonstrate that NOD2 detection of bacterial cell wall peptidoglycan (PGN) regulates metabolic inflammation and insulin sensitivity. An obesity-promoting high-fat diet (HFD) increased NOD2 in hepatocytes and adipocytes, and NOD2(-/-) mice have increased adipose tissue and liver inflammation and exacerbated insulin resistance during a HFD. This effect is independent of altered adiposity or NOD2 in hematopoietic-derived immune cells. Instead, increased metabolic inflammation and insulin resistance in NOD2(-/-) mice is associated with increased commensal bacterial translocation from the gut into adipose tissue and liver. An intact PGN-NOD2 sensing system regulated gut mucosal bacterial colonization and a metabolic tissue dysbiosis that is a potential trigger for increased metabolic inflammation and insulin resistance. Gut dysbiosis in HFD-fed NOD2(-/-) mice is an independent and transmissible factor that contributes to metabolic inflammation and insulin resistance when transferred to WT, germ-free mice. These findings warrant scrutiny of bacterial component detection, dysbiosis, and protective immune responses in the links between inflammatory gut and metabolic diseases, including diabetes.
Asunto(s)
Bacterias/inmunología , Dieta/métodos , Disbiosis , Inflamación/patología , Resistencia a la Insulina , Proteína Adaptadora de Señalización NOD2/metabolismo , Peptidoglicano/metabolismo , Animales , Pared Celular/química , Ratones , Ratones Noqueados , Peptidoglicano/análisisRESUMEN
Statins reduce lipid levels and are widely prescribed. Statins have been associated with an increased incidence of type 2 diabetes, but the mechanisms are unclear. Activation of the NOD-like receptor family, pyrin domain containing 3 (NLRP3)/caspase-1 inflammasome, promotes insulin resistance, a precursor of type 2 diabetes. We showed that four different statins increased interleukin-1ß (IL-1ß) secretion from macrophages, which is characteristic of NLRP3 inflammasome activation. This effect was dose dependent, absent in NLRP3(-/-) mice, and prevented by caspase-1 inhibition or the diabetes drug glyburide. Long-term fluvastatin treatment of obese mice impaired insulin-stimulated glucose uptake in adipose tissue. Fluvastatin-induced activation of the NLRP3/caspase-1 pathway was required for the development of insulin resistance in adipose tissue explants, an effect also prevented by glyburide. Fluvastatin impaired insulin signaling in lipopolysaccharide-primed 3T3-L1 adipocytes, an effect associated with increased caspase-1 activity, but not IL-1ß secretion. Our results define an NLRP3/caspase-1-mediated mechanism of statin-induced insulin resistance in adipose tissue and adipocytes, which may be a contributing factor to statin-induced development of type 2 diabetes. These results warrant scrutiny of insulin sensitivity during statin use and suggest that combination therapies with glyburide, or other inhibitors of the NLRP3 inflammasome, may be effective in preventing the adverse effects of statins.
Asunto(s)
Tejido Adiposo/metabolismo , Proteínas Portadoras/metabolismo , Ácidos Grasos Monoinsaturados/uso terapéutico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Indoles/uso terapéutico , Inflamasomas/efectos de los fármacos , Inflamasomas/metabolismo , Células 3T3-L1 , Tejido Adiposo/efectos de los fármacos , Animales , Proteínas Portadoras/genética , Caspasa 1/genética , Caspasa 1/metabolismo , Ácidos Grasos Monoinsaturados/efectos adversos , Fluvastatina , Gliburida/uso terapéutico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Indoles/efectos adversos , Resistencia a la Insulina , Interleucina-1beta/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Masculino , Ratones , Proteína con Dominio Pirina 3 de la Familia NLR , Obesidad/tratamiento farmacológico , Obesidad/metabolismoRESUMEN
Obesity is associated with inflammation that can drive metabolic defects such as hyperlipidemia and insulin resistance. Specific metabolites can contribute to inflammation, but nutrient intake and obesity are also associated with altered bacterial load in metabolic tissues (i.e. metabolic endotoxemia). These bacterial cues can contribute to obesity-induced inflammation. The specific bacterial components and host receptors that underpin altered metabolic responses are emerging. We previously showed that Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) activation with bacterial peptidoglycan (PGN) caused insulin resistance in mice. We now show that PGN induces cell-autonomous lipolysis in adipocytes via NOD1. Specific bacterial PGN motifs stimulated lipolysis in white adipose tissue (WAT) explants from WT, but not NOD1â»/â»mice. NOD1-activating PGN stimulated mitogen activated protein kinases (MAPK),protein kinase A (PKA), and NF-κB in 3T3-L1 adipocytes. The NOD1-mediated lipolysis response was partially reduced by inhibition of ERK1/2 or PKA alone, but not c-Jun N-terminal kinase (JNK). NOD1-stimulated lipolysis was partially dependent on NF-κB and was completely suppressed by inhibiting ERK1/2 and PKA simultaneously or hormone sensitive lipase (HSL). Our results demonstrate that bacterial PGN stimulates lipolysis in adipocytes by engaging a stress kinase, PKA, NF-κB-dependent lipolytic program. Bacterial NOD1 activation is positioned as a component of metabolic endotoxemia that can contribute to hyperlipidemia, systemic inflammation and insulin resistance by acting directly on adipocytes.