Blockade of the NLRP3 inflammasome improves metabolic health and lifespan in obese mice.

Aging is the major risk factor for many metabolic chronic diseases. Several metabolic pathways suffer a progressive impairment during aging including body composition and insulin resistance which are associated to autophagy dysfunction and increased inflammation. Many of these alterations are aggravated by non-healthy lifestyle such as obesity and hypercaloric diet which have been shown to accelerate aging. Here, we show that the deleterious effect of hypercaloric diets is reverted by the NLRP3 inflammasome inhibition. NLRP3 deficiency extends mean lifespan of adult mice fed a high-fat diet. This lifespan extension is accompanied by metabolic health benefits including reduced liver steatosis and cardiac damage, improved glucose and lipid metabolism, and improved protein expression profiles of SIRT-1, mTOR, autophagic flux, and apoptosis. These findings suggest that the suppression of NLRP3 prevented many age-associated changes in metabolism impaired by the effect of hypercaloric diets.

NLRP3 inflammasome suppression improves longevity and prevents cardiac aging in male mice.

While NLRP3-inflammasome has been implicated in cardiovascular diseases, its role in physiological cardiac aging is largely unknown. During aging, many alterations occur in the organism, which are associated with progressive impairment of metabolic pathways related to insulin resistance, autophagy dysfunction, and inflammation. Here, we investigated the molecular mechanisms through which NLRP3 inhibition may attenuate cardiac aging. Ablation of NLRP3-inflammasome protected mice from age-related increased insulin sensitivity, reduced IGF-1 and leptin/adiponectin ratio levels, and reduced cardiac damage with protection of the prolongation of the age-dependent PR interval, which is associated with atrial fibrillation by cardiovascular aging and reduced telomere shortening. Furthermore, old NLRP3 KO mice showed an inhibition of the PI3K/AKT/mTOR pathway and autophagy improvement, compared with old wild mice and preserved Nampt-mediated NAD+ levels with increased SIRT1 protein expression. These findings suggest that suppression of NLRP3 prevented many age-associated changes in the heart, preserved cardiac function of aged mice and increased lifespan.

NLRP3 Inflammasome Inhibition by MCC950 in Aged Mice Improves Health via Enhanced Autophagy and PPARα Activity.

The NLRP3 inflammasome has emerged as an important regulator of metabolic disorders and age-related diseases in NLRP3-deficient mice. In this article, we determine whether, in old mice C57BL6J, the NLRP3 inflammasome inhibitor MCC950 is able to attenuate age-related metabolic syndrome to providing health benefits. We report that MCC950 attenuates metabolic and hepatic dysfunction in aged mice. In addition, MCC950 inhibited the Pi3K/AKT/mTOR pathway, enhanced autophagy, and activated peroxisome proliferator-activated receptor-α in vivo and in vitro. The data suggest that MCC950 mediates the protective effects by the mammalian target of rapamycin inhibition, thus activating autophagy and peroxisome proliferator-activated receptor-α. In conclusion, pharmacological inhibition of NLRP3 in aged mice has a significant impact on health. Thus, NLRP3 may be a therapeutic target of human age-related metabolic syndrome.

Aging and the Inflammasomes.

The inflammasomes are innate immune system sensors that control the activation of caspase-1 and induce inflammation in response to infectious microbes and molecules originating from host proteins, leading to the release of pro-inflammatory cytokines, Il1b and IL18, and a particular inflammatory type of cell death termed pyroptosis. It is broadly considered that chronic inflammation may be a common link in age-related diseases, aging being the greatest risk factor for the development of chronic diseases. In this sense, we discuss the role of inflammasomes in non-infectious inflammation and their interest in aging and age-related diseases.

Cardiovascular diseases, NLRP3 inflammasome, and western dietary patterns.

Cardiovascular diseases (CVD) are the leading cause of death worldwide, with high prevalence in industrialized countries. Cardiovascular risk factors are mainly influenced by diet, which like other lifestyle factors can be modified to either reduce or increase cardiovascular risk. Other metabolic diseases such as metabolic syndrome, type II diabetes mellitus, and obesity are associated to CVD and highly influenced by the diet. Inflammation has demonstrated to be a key factor in the biological progress of these diseases. Interestingly, IL-1ß which is associated to several steps in the development of atherosclerosis, heart disease, and the association of obesity and type II diabetes with CVD, is activated by the inflammasome complex, a multiprotein complex composed of an intracellular sensor, typically a Nod-like receptor (NLR), the precursor procaspase-1, and the adaptor ASC (apoptosis-associated speck-like protein containing a CARD. In the last years, inflammasome complex has been studied in depth and has been associated with the effect of unhealthy diets both from a clinical and experimental view point. We have reviewed the evidences supporting the role of the inflammasome complex in the development of cardiovascular pathology by unhealthy diets and the therapeutic perspectives.

NLRP3-inflammasome inhibition prevents high fat and high sugar diets-induced heart damage through autophagy induction.

The NLRP3-inflammasome complex has emerged as an important component of inflammatory processes in metabolic dysfunction induced by high-caloric diets. In this study, we investigate the molecular mechanisms by which NLRP3 inhibition may attenuate diet-induced cardiac injury. Here we show the cardiac damage induced by high sugar diet (HSD), high fat diet (HFD) or high sugar/fat diet (HSFD) over 15 weeks. Genetic ablation of NLRP3 protected against this damage by autophagy induction and apoptotic control. Furthermore, NLRP3 inhibition by the selective small molecule MCC950 resulted in similar autophagy induction and apoptotic control in hearts after diets. These data were reproduced in THP-1 cells treated with MCC950 and cultured in media supplemented with serum from mice dosed with MCC950 and fed with diets. NLRP3 inhibition exerted beneficial metabolic, and autophagic adaptations in hearts from obesogenic diets. The inhibition of NLRP3 activation may hold promise in the treatment of metabolic and cardiovascular diseases.

Adenosine Monophosphate (AMP)-Activated Protein Kinase: A New Target for Nutraceutical Compounds.

Adenosine monophosphate-activated protein kinase (AMPK) is an important energy sensor which is activated by increases in adenosine monophosphate (AMP)/adenosine triphosphate (ATP) ratio and/or adenosine diphosphate (ADP)/ATP ratio, and increases different metabolic pathways such as fatty acid oxidation, glucose transport and mitochondrial biogenesis. In this sense, AMPK maintains cellular energy homeostasis by induction of catabolism and inhibition of ATP-consuming biosynthetic pathways to preserve ATP levels. Several studies indicate a reduction of AMPK sensitivity to cellular stress during aging and this could impair the downstream signaling and the maintenance of the cellular energy balance and the stress resistance. However, several diseases have been related with an AMPK dysfunction. Alterations in AMPK signaling decrease mitochondrial biogenesis, increase cellular stress and induce inflammation, which are typical events of the aging process and have been associated to several pathological processes. In this sense, in the last few years AMPK has been identified as a very interesting target and different nutraceutical compounds are being studied for an interesting potential effect on AMPK induction. In this review, we will evaluate the interaction of the different nutraceutical compounds to induce the AMPK phosphorylation and the applications in diseases such as cancer, type II diabetes, neurodegenerative diseases or cardiovascular diseases.

AMPK/Mitochondria in Metabolic Diseases.

The obtaining of nutrients is the most important task in our lives. Energy is central to life's evolutions; this was one of the aspect that induced the selection of the more adaptable and more energetically profitable species. Nowadays things have changed in our modern society. A high proportion of people has access to plenty amount of food and the obesity appear as one of the pathological characteristics of our society. Energy is obtained essentially in the mitochondria with the transfer of protons across the inner membrane that produce ATP. The exactly regulation of the synthesis and degradation of ATP (ATP ↔ ADP + phosphate) is essential to all form of life. This task is performed by the 5' adenosine monophosphate-activated protein kinase (AMPK). mtDNA is highly exposed to oxidative damage and could play a central role in human health and disease. This high potential rate of abnormalities is controlled by one of the most complex mechanism: the autophagy. AMPK appears to be the key cellular energy sensor involved in multiple cellular mechanisms and is essential to have a good metabolic homeostasis to face all the aggression and start the inflammatory reaction. Therefore its disturbances have been related with multiple diseases. Recent findings support the role of AMPK in inflammation and immunity such as Metabolic Syndrome, Obesity and Diabetes. All these Metabolic Disorders are considered pandemics and they need an adequate control and prevention. One important way to achieve it is deepen in the pathogenic mechanisms. Mitochondria and AMPK are the key elements through which it happen, their knowledge and research allow us to a better management. The discovery and use of drugs that can modulate them is imperative to improve our way of manage the metabolic disorders.

Mutation in cytochrome b gene of mitochondrial DNA in a family with fibromyalgia is associated with NLRP3-inflammasome activation.

BACKGROUND: Fibromyalgia (FM) is a worldwide diffuse musculoskeletal chronic pain condition that affects up to 5% of the general population. Many symptoms associated with mitochondrial diseases are reported in patients with FM such as exercise intolerance, fatigue, myopathy and mitochondrial dysfunction. In this study, we report a mutation in cytochrome b gene of mitochondrial DNA (mtDNA) in a family with FM with inflammasome complex activation. METHODS: mtDNA from blood cells of five patients with FM were sequenced. We clinically and genetically characterised a patient with FM and family with a new mutation in mtCYB. Mitochondrial mutation phenotypes were determined in skin fibroblasts and transmitochondrial cybrids. RESULTS: After mtDNA sequence in patients with FM, we found a mitochondrial homoplasmic mutation m.15804T>C in the mtCYB gene in a patient and family, which was maternally transmitted. Mutation was observed in several tissues and skin fibroblasts showed a very significant mitochondrial dysfunction and oxidative stress. Increased NLRP3-inflammasome complex activation was observed in blood cells from patient and family. CONCLUSIONS: We propose further studies on mtDNA sequence analysis in patients with FM with evidences for maternal inheritance. The presence of similar symptoms in mitochondrial myopathies could unmask mitochondrial diseases among patients with FM. On the other hand, the inflammasome complex activation by mitochondrial dysfunction could be implicated in the pathophysiology of mitochondrial diseases.

Stress-Induced Depressive Behaviors Require a Functional NLRP3 Inflammasome.

Depression is a major public health concern in modern society, yet little is known about the molecular link between this condition and neuroinflammation. The inflammasome complex was recently shown to be implicated in depression. The present study shows the implication of NLRP3 inflammasome in animal model of stress-induced depression. Accordingly, we show here that in the absence of a NLRP3 inflammasome, prolonged stress does not provoke depressive behaviors or microglial activation in mice or dampen hippocampal neurogenesis. Indeed, NLRP3 deletion or inhibition of microglial activation impairs the stress-induced alterations associated with depression. According to these findings in animal model, the inflammasome could be a target for new therapeutic interventions to prevent depression in patients.

AMPK Phosphorylation Modulates Pain by Activation of NLRP3 Inflammasome.

AIMS: Impairment in adenosine monophosphate-activated protein kinase (AMPK) activity and NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation are associated with several metabolic and inflammatory diseases. In this study, we investigated the role of AMPK/NLRP3 inflammasome axis in the molecular mechanism underlying pain perception. RESULTS: Impairment in AMPK activation induced by compound C or sunitinib, two AMPK inhibitors, provoked hyperalgesia in mice (p<0.001) associated with marked NLRP3 inflammasome protein activation and increased serum levels of interleukin-1ß (IL-1ß) (24.56±0.82 pg/ml) and IL-18 (23.83±1.882 pg/ml) compared with vehicle groups (IL-1ß: 8.15±0.44; IL-18: 4.92±0.4). This effect was rescued by increasing AMPK phosphorylation via metformin treatment (p<0.001), caloric restriction diet (p<0.001), or NLRP3 inflammasome genetic inactivation using NLRP3 knockout (nlrp3(-/-)) mice (p<0.001). Deficient AMPK activation and overactivation of NLRP3 inflammasome axis were also observed in blood cells from patients with fibromyalgia (FM), a prevalent human chronic pain disease. In addition, metformin treatment (200 mg/daily), which increased AMPK activation, restored all biochemical alterations examined by us in blood cells and significantly improved clinical symptoms, such as, pain, fatigue, depression, disturbed sleep, and tender points, in patients with FM. INNOVATION AND CONCLUSIONS: These data suggest that AMPK/NLRP3 inflammasome axis participates in chronic pain and that NLRP3 inflammasome inhibition by AMPK modulation may be a novel therapeutic target to fight against chronic pain and inflammatory diseases as FM.

Metformin and caloric restriction induce an AMPK-dependent restoration of mitochondrial dysfunction in fibroblasts from Fibromyalgia patients.

Impaired AMPK is associated with a wide spectrum of clinical and pathological conditions, ranging from obesity, altered responses to exercise or metabolic syndrome, to inflammation, disturbed mitochondrial biogenesis and defective response to energy stress. Fibromyalgia (FM) is a world-wide diffused musculoskeletal chronic pain condition that affects up to 5% of the general population and comprises all the above mentioned pathophysiological states. Here, we tested the involvement of AMPK activation in fibroblasts derived from FM patients. AMPK was not phosphorylated in fibroblasts from FM patients and was associated with decreased mitochondrial biogenesis, reduced oxygen consumption, decreased antioxidant enzymes expression levels and mitochondrial dysfunction. However, mtDNA sequencing analysis did not show any important alterations which could justify the mitochondrial defects. AMPK activation in FM fibroblast was impaired in response to moderate oxidative stress. In contrast, AMPK activation by metformin or incubation with serum from caloric restricted mice improved the response to moderate oxidative stress and mitochondrial metabolism in FM fibroblasts. These results suggest that AMPK plays an essential role in FM pathophysiology and could represent the basis for a valuable new therapeutic target/strategy. Furthermore, both metformin and caloric restriction could be an interesting therapeutic approach in FM.

Oxidative stress, mitochondrial dysfunction and, inflammation common events in skin of patients with Fibromyalgia.

Fibromyalgia is a chronic pain syndrome with unknown etiology. Recent studies have shown some evidence demonstrating that oxidative stress, mitochondrial dysfunction and inflammation may have a role in the pathophysiology of fibromyalgia. Despite several skin-related symptoms accompanied by small fiber neuropathy have been studied in FM, these mitochondrial changes have not been yet studied in this tissue. Skin biopsies from patients showed a significant mitochondrial dysfunction with reduced mitochondrial chain activities and bioenergetics levels and increased levels of oxidative stress. These data were related to increased levels of inflammation and correlated with pain, the principal symptom of FM. All these parameters have shown a role in peripheral nerve damage which has been observed in FM as a possible responsible to allodynia. Our findings may support the role of oxidative stress, mitochondrial dysfunction and inflammation as interdependent events in the pathophysiology of FM with a special role in the peripheral alterations.

Lipophilic antioxidants prevent lipopolysaccharide-induced mitochondrial dysfunction through mitochondrial biogenesis improvement.

Oxidative stress is implicated in several infectious diseases. In this regard, lipopolysaccharide (LPS), an endotoxic component, induces mitochondrial dysfunction and oxidative stress in several pathological events such as periodontal disease or sepsis. In our experiments, LPS-treated fibroblasts provoked increased oxidative stress, mitochondrial dysfunction, reduced oxygen consumption and mitochondrial biogenesis. After comparing coenzyme Q10 (CoQ10) and N-acetylcysteine (NAC), we observed a more significant protection of CoQ10 than of NAC, which was comparable with other lipophilic and hydrophilic antioxidants such as vitamin E or BHA respectively. CoQ10 improved mitochondrial biogenesis by activating PGC-1α and TFAM. This lipophilic antioxidant protection was observed in mice after LPS injection. These results show that mitochondria-targeted lipophilic antioxidants could be a possible specific therapeutic strategy in pharmacology in the treatment of infectious diseases and their complications.