The NLRP3 Inflammasome as a novel player of the intercellular crosstalk in metabolic disorders. Mediators Inflamm. 2013;2013:678627. [PMID: 23843683 PMCID: PMC3697790 DOI: 10.1155/2013/678627]

Combined UPLC-QqQ-MS/MS and AP-MALDI Mass Spectrometry Imaging Method for Phospholipidomics in Obese Mouse Kidneys: Alleviation by Feeding Sea Cucumber Phospholipids

Sea cucumber phospholipids have ameliorative effects on various diseases related to lipid metabolism. However, it is unclear whether it can ameliorate obesity-associated glomerulopathy (ORG) induced by a high-fat diet (HFD). The present study applied UPLC-QqQ-MS/MS and atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry imaging (AP-MALDI MSI) to investigate the effects of sea cucumber phospholipids, including plasmalogen PlsEtn and plasmanylcholine PakCho, on phospholipid profiles in the HFD-induced ORG mouse kidney. Quantitative analysis of 135 phospholipids revealed that PlsEtn and PakCho significantly modulated phospholipid levels. Notably, PlsEtn modulated kidney overall phospholipids better than PakCho. Imaging the "space-content" of 9 phospholipids indicated that HFD significantly increased phospholipid content within the renal cortex. Furthermore, PlsEtn and PakCho significantly decreased the expression of transport-related proteins CD36, while elevating the expression of fatty acid β-oxidation-related protein PPAR-α in the renal cortex. In conclusion, sea cucumber phospholipids reduced renal lipid accumulation, ameliorated renal damage, effectively regulated the content and distribution of renal phospholipids, and improved phospholipid homeostasis, exerting an anti-OGR effect.

Mitochondrial dysfunction in the pathophysiology of renal diseases

Mitochondria are essential organelles in the human body, serving as the metabolic factory of the whole organism. When mitochondria are dysfunctional, it can affect all organs of the body. The kidney is rich in mitochondria, and its function is closely related to the development of kidney diseases. Studying the relationship between mitochondria and kidney disease progression is of great interest. In the past decade, scientists have made inspiring progress in investigating the role of mitochondria in the pathophysiology of renal diseases. This article discusses various mechanisms for maintaining mitochondrial quality, including mitochondrial energetics, mitochondrial biogenesis, mitochondrial dynamics, mitochondrial DNA repair, mitochondrial proteolysis and the unfolded protein response, mitochondrial autophagy, mitochondria-derived vesicles, and mitocytosis. The article also highlights the cross talk between mitochondria and other organelles, with a focus on kidney diseases. Finally, the article concludes with an overview of mitochondria-related clinical research.

P2X7 receptor antagonists modulate experimental autoimmune neuritis via regulation of NLRP3 inflammasome activation and Th17 and Th1 cell differentiation

BACKGROUND

Guillain-Barré syndrome (GBS), a post-infectious, immune-mediated, acute demyelinating disease of the peripheral nerves and nerve roots, represents the most prevalent and severe acute paralyzing neuropathy. Purinergic P2X7 receptors (P2X7R) play a crucial role in central nervous system inflammation. However, little is known about their role in the immune-inflammatory response within the peripheral nervous system.

METHODS

Initially, we assessed the expression of purinergic P2X7R in the peripheral blood of patients with GBS using flow cytometry and qRT-PCR. Next, we explored the expression of P2 X7R in CD4+ T cells, CD8+ T cells, and macrophages within the sciatic nerves and spleens of rats using immunofluorescence labeling and flow cytometry. The P2X7R antagonist brilliant blue G (BBG) was employed to examine its therapeutic impact on rats with experimental autoimmune neuritis (EAN) induced by immunization with the P0180 - 199 peptide. We analyzed CD4+ T cell differentiation in splenic mononuclear cells using flow cytometry, assessed Th17 cell differentiation in the sciatic nerve through immunofluorescence staining, and examined the expression of pro-inflammatory cytokine mRNA using RT-PCR. Additionally, we performed protein blotting to assess the expression of P2X7R and NLRP3-related inflammatory proteins within the sciatic nerve. Lastly, we utilized flow cytometry and immunofluorescence labeling to examine the expression of NLRP3 on CD4+ T cells in rats with EAN.

RESULTS

P2X7R expression was elevated not only in the peripheral blood of patients with GBS but also in rats with EAN. In rats with EAN, inhibiting P2X7R with BBG alleviated neurological symptoms, reduced demyelination, decreased inflammatory cell infiltration of the peripheral nerves, and improved nerve conduction. BBG also limited the production of pro-inflammatory molecules, down-regulated the expression of P2X7R and NLRP3, and suppressed the differentiation of Th1 and Th17 cells, thus protecting against EAN. These effects collectively contribute to modifying the inflammatory environment and enhancing outcomes in EAN rats.

CONCLUSIONS

Suppression of P2X7R relieved EAN manifestation by regulating CD4+ T cell differentiation and NLRP3 inflammasome activation. This finding underscores the potential significance of P2X7R as a target for anti-inflammatory treatments, advancing research and management of GBS.

Exploring the role of IL-1β in inflammatory bowel disease pathogenesis

Interleukin 1β (IL-1β) is a significant mediator of inflammation and tissue damage in IBD. The balance between IL-1β and its endogenous inhibitor-IL-1Ra-, plays a critical role in both initiation and regulation of inflammation. However, the precise role of IL-1β as a causative factor in IBD or simply a consequence of inflammation remains unclear. This review summarizes current knowledge on the molecular and cellular characteristics of IL-1β, describes the existing evidence on the role of this cytokine as a modulator of intestinal homeostasis and an activator of inflammatory responses, and also discusses the role of microRNAs in the regulation of IL-1β-related inflammatory responses in IBD. Current evidence indicates that IL-1β is involved in several aspects during IBD as it greatly contributes to the induction of pro-inflammatory responses through the recruitment and activation of immune cells to the gut mucosa. In parallel, IL-1β is involved in the intestinal barrier disruption and modulates the differentiation and function of T helper (Th) cells by activating the Th17 cell differentiation, known to be involved in the pathogenesis of IBD. Dysbiosis in the gut can also stimulate immune cells to release IL-1β, which, in turn, promotes inflammation. Lastly, increasing evidence pinpoints the central role of miRNAs involvement in IL-1β-related signaling during IBD, particularly in the maintenance of homeostasis within the intestinal epithelium. In conclusion, given the crucial role of IL-1β in the promotion of inflammation and immune responses in IBD, the targeting of this cytokine or its receptors represents a promising therapeutic approach. Further research into the IL-1β-associated post-transcriptional modifications may elucidate the intricate role of this cytokine in immunomodulation.

Sweet triterpenoid glycoside from Cyclocarya paliurus ameliorates obesity-induced insulin resistance through inhibiting the TLR4/NF-κB/NLRP3 inflammatory pathway

Our prophase studies have manifested that the sweet triterpenoid glycoside from the leaves of Cyclocarya paliurus (CPST) effectively improved the disorders of glucolipid metabolism in vitro and in patients. The current purpose was to further detect its mechanisms involved. The results demonstrated that CPST could ameliorate high-fat diet (HFD)-induced insulin resistance (IR), which was linked to reducing HFD-induced mice's body weight, serum glucose (GLUO), triglyceride (TG), total cholesterol (T-CHO) and low-density lipoprotein cholesterol (LDL-C), lowering the area under the oral glucose tolerance curve and insulin tolerance, elevating the percentage of brown adipose, high-density lipoprotein cholesterol (HDL-C), reducing fat droplets of adipocytes in interscapular brown adipose tissue (iBAT) and cross-sectional area of adipocytes. Further studies manifested that CPST obviously downregulated TLR4, MyD88, NLRP3, ASC, caspase-1, cleased-caspase-1, IL-18, IL-1β, TXNIP, and GSDMD protein expressions and p-NF-кB/NF-кB ratio in iBAT. These aforementioned findings demonstrated that CPST ameliorated HFD induced IR by regulating TLR4/NF-κB/NLRP3 signaling pathway, which in turn enhancing insulin sensitivity and glucose metabolism.

Isoquercitrin Attenuates Steatohepatitis by Inhibition of the Activated NLRP3 Inflammasome through HSP90

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease with a global prevalence of 25%. However, the medicines approved by the FDA or EMA are still not commercially available for the treatment of NAFLD. The NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome plays a crucial role in inflammatory responses, and the mechanisms related to steatohepatitis have been sufficiently clarified. NLRP3 has been widely evaluated as a potential target for multiple active agents in treating NAFLD. As a quercetin glycoside, isoquercitrin (IQ) has a broad inhibitory effect on oxidative stress, cancers, cardiovascular diseases, diabetes, and allergic reactions in vitro and in vivo. This study aimed to investigate the undercover mechanism of IQ in the treatment of NAFLD, particularly in anti-steatohepatitis, by suppressing the NLRP3 inflammasome. In this study, a methionine-choline-deficient induced steatohepatitis mice model was used to explore the effect of IQ on NAFLD treatment. Further mechanism exploration based on transcriptomics and molecular biology revealed that IQ inhibited the activated NLRP3 inflammasome by down-regulating the expression of heat shock protein 90 (HSP90) and suppressor of G-two allele of Skp1 (SGT1). In conclusion, IQ could alleviate NAFLD by inhibiting the activated NLRP3 inflammasome by suppressing the expression of HSP90.

Cachexia causes time-dependent activation of the inflammasome in the liver

BACKGROUND

Cachexia is a wasting syndrome associated with systemic inflammation and metabolic disruption. Detection of the early signs of the disease may contribute to the effective attenuation of associated symptoms. Despite playing a central role in the control of metabolism and inflammation, the liver has received little attention in cachexia. We previously described relevant disruption of metabolic pathways in the organ in an animal model of cachexia, and herein, we adopt the same model to investigate temporal onset of inflammation in the liver. The aim was thus to study inflammation in rodent liver in the well-characterized cachexia model of Walker 256 carcinosarcoma and, in addition, to describe inflammatory alterations in the liver of one cachectic colon cancer patient, as compared to one control and one weight-stable cancer patient.

METHODS

Colon cancer patients (one weight stable [WSC] and one cachectic [CC]) and one patient undergoing surgery for cholelithiasis (control, n = 1) were enrolled in the study, after obtainment of fully informed consent. Eight-week-old male rats were subcutaneously inoculated with a Walker 256 carcinosarcoma cell suspension (2 × 10⁷ cells in 1.0 mL; tumour-bearing [T]; or phosphate-buffered saline-controls [C]). The liver was excised on Days 0 (n = 5), 7 (n = 5) and 14 (n = 5) after tumour cell injection.

RESULTS

In rodent cachexia, we found progressively higher numbers of CD68⁺ myeloid cells in the liver along cancer-cachexia development. Similar findings are described for CC, whose liver showed infiltration of the same cell type, compared with both WSC and control patient organs. In advanced rodent cachexia, hepatic phosphorylated c-Jun N-terminal kinase protein content and the inflammasome pathway protein expression were increased in relation to baseline (P < 0.05). These changes were accompanied by augmented expression of the active interleukin-1β (IL-1β) form (P < 0.05 for both circulating and hepatic content).

CONCLUSIONS

The results show that cancer cachexia is associated with an increase in the number of myeloid cells in rodent and human liver and with modulation of hepatic inflammasome pathway. The latter contributes to the aggravation of systemic inflammation, through increased release of IL-1β.

Innate Immune System in the Pathogenesis of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a prevalent condition characterized by lipid accumulation in hepatocytes with low alcohol consumption. The development of sterile inflammation, which occurs in response to a range of cellular stressors or injuries, has been identified as a major contributor to the pathogenesis of NAFLD. Recent studies of the pathogenesis of NAFLD reported the newly developed roles of damage-associated molecular patterns (DAMPs). These molecules activate pattern recognition receptors (PRRs), which are placed in the infiltrated neutrophils, dendritic cells, monocytes, or Kupffer cells. DAMPs cause the activation of PRRs, which triggers a number of immunological responses, including the generation of cytokines that promote inflammation and the localization of immune cells to the site of the damage. This review provides a comprehensive overview of the impact of DAMPs and PRRs on the development of NAFLD.

Glucagon induces the hepatic expression of inflammatory markers in vitro and in vivo

Glucagon exerts multiple hepatic actions, including stimulation of glycogenolysis/gluconeogenesis. The liver plays a crucial role in chronic inflammation by synthesizing proinflammatory molecules, which are thought to contribute to insulin resistance and hyperglycaemia. Whether glucagon affects hepatic expression of proinflammatory cytokines and acute-phase reactants is unknown. Herein, we report a positive relationship between fasting glucagon levels and circulating interleukin (IL)-1β (r = 0.252, p = .042), IL-6 (r = 0.230, p = .026), fibrinogen (r = 0.193, p = .031), complement component 3 (r = 0.227, p = .024) and high sensitivity C-reactive protein (r = 0.230, p = .012) in individuals without diabetes. In CD1 mice, 4-week continuous treatment with glucagon induced a significant increase in circulating IL-1β (p = .02), and IL-6 (p = .001), which was countered by the contingent administration of the glucagon receptor antagonist, GRA-II. Consistent with these results, we detected a significant increase in the hepatic activation of inflammatory pathways, such as expression of NLRP3 (p < .02), and the phosphorylation of nuclear factor kappaB (NF-κB; p < .02) and STAT3 (p < .01). In HepG2 cells, we found that glucagon dose-dependently stimulated the expression of IL-1β (p < .002), IL-6 (p < .002), fibrinogen (p < .01), complement component 3 (p < .01) and C-reactive protein (p < .01), stimulated the activation of NLRP3 inflammasome (p < .01) and caspase-1 (p < .05), induced the phosphorylation of TRAF2 (p < .01), NF-κB (p < .01) and STAT3 (p < .01). Preincubating cells with GRA-II inhibited the ability of glucagon to induce an inflammatory response. Using HepaRG cells, we confirmed the dose-dependent ability of glucagon to stimulate the expression of NLRP3, the phosphorylation of NF-κB and STAT3, in the absence of GRA-II. These results suggest that glucagon has proinflammatory effects that may participate in the pathogenesis of hyperglycaemia and unfavourable cardiometabolic risk profile.

Salvianolic acid B ameliorates non-alcoholic fatty liver disease by inhibiting hepatic lipid accumulation and NLRP3 inflammasome in ob/ob mice

Non-alcoholic fatty liver disease (NAFLD) has high occurrence in the global world, which poses serious threats to human health. Salvianolic acid B (SalB), an extract of the root of Salvia miltiorrhiza, has the protective effect on metabolic homeostasis. However, the mechanism is still unknown. In this study, we used ob/ob mice, a model of NAFLD, to explore the hepatoprotective effects of SalB. The results showed that SalB significantly reduced the body weights and liver weights, and ameliorated plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), hepatic free fatty acid (FFA), total cholesterol (TC) levels, and hepatic TG and TC levels in ob/ob mice. SalB reduced the number of lipid droplets and inhibited hepatic lipogenesis by regulating peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FASN), stearoyl-Co A desaturase 1 (SCD1), and cluster of differentiation 36 (CD36). Compared to ob/ob mice, the lower expressions of the pro-inflammatory cytokines, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and F4/80, were observed after SalB treatment. Importantly, SalB treatment inhibited the activation of NLRP3 inflammasome and reduced the severity of liver inflammation. Our findings suggested that SalB improved NAFLD pathology in ob/ob mice by reducing hepatic lipid accumulation and NLRP3 inflammasome activation, which might be the potential hepatoprotective mechanism of SalB.

Cell-specific Deletion of NLRP3 Inflammasome Identifies Myeloid Cells as Key Drivers of Liver Inflammation and Fibrosis in Murine Steatohepatitis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. The NLRP3 inflammasome, a platform for caspase-1 activation and release of interleukin 1β, is increasingly recognized in the induction of inflammation and liver fibrosis during NAFLD. However, the cell-specific contribution of NLRP3 inflammasome activation in NAFLD remains unknown.

METHODS

To investigate the role of NLRP3 inflammasome activation in hepatocytes, hepatic stellate cells (HSCs) and myeloid cells, a conditional Nlrp3 knock-out mouse was generated and bred to cell-specific Cre mice. Both acute and chronic liver injury models were used: lipopolysaccharide/adenosine-triphosphate to induce in vivo NLRP3 activation, choline-deficient, L-amino acid-defined high-fat diet, and Western-type diet to induce fibrotic nonalcoholic steatohepatitis (NASH). In vitro co-culture studies were performed to dissect the crosstalk between myeloid cells and HSCs.

RESULTS

Myeloid-specific deletion of Nlrp3 blunted the systemic and hepatic increase in interleukin 1β induced by lipopolysaccharide/adenosine-triphosphate injection. In the choline-deficient, L-amino acid-defined high-fat diet model of fibrotic NASH, myeloid-specific Nlrp3 knock-out but not hepatocyte- or HSC-specific knock-out mice showed significant reduction in inflammation independent of steatosis development. Moreover, myeloid-specific Nlrp3 knock-out mice showed ameliorated liver fibrosis and decreased HSC activation. These results were validated in the Western-type diet model. In vitro co-cultured studies with human cell lines demonstrated that HSC can be activated by inflammasome stimulation in monocytes, and this effect was significantly reduced if NLRP3 was downregulated in monocytes.

CONCLUSIONS

The study provides new insights in the cell-specific role of NLRP3 in liver inflammation and fibrosis. NLRP3 inflammasome activation in myeloid cells was identified as crucial for the progression of NAFLD to fibrotic NASH. These results may have implications for the development of cell-specific strategies for modulation of NLRP3 activation for treatment of fibrotic NASH.

Cardiovascular Disease in Duchenne Muscular Dystrophy

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Cardiomyopathy is the leading cause of death in patients with DMD.

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DMD has no cure, and there is no current consensus for treatment of DMD cardiomyopathy.

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This review discusses therapeutic strategies to potentially reduce or prevent cardiac dysfunction in DMD patients.

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Additional studies are needed to firmly establish optimal treatment modalities for DMD cardiomyopathy.

Duchenne muscular dystrophy (DMD) is a devastating disease affecting approximately 1 in every 3,500 male births worldwide. Multiple mutations in the dystrophin gene have been implicated as underlying causes of DMD. However, there remains no cure for patients with DMD, and cardiomyopathy has become the most common cause of death in the affected population. Extensive research is under way investigating molecular mechanisms that highlight potential therapeutic targets for the development of pharmacotherapy for DMD cardiomyopathy. In this paper, the authors perform a literature review reporting on recent ongoing efforts to identify novel therapeutic strategies to reduce, prevent, or reverse progression of cardiac dysfunction in DMD.

Chronic Inflammation in Obesity and Cancer Cachexia

Chronic inflammation has long been linked to obesity and related conditions such as type 2 diabetes and metabolic syndrome. According to current research, the increased risk of cancer in people with certain metabolic diseases may be due to chronic inflammation. Adipocytokines, which are pro-inflammatory cytokines secreted in excess, are elevated in many chronic metabolic diseases. Cytokines and inflammatory mediators, which are not directly linked to DNA, are important in tumorigenesis. Cachexia, a type of metabolic syndrome linked to the disease, is associated with a dysregulation of metabolic pathways. Obesity and cachexia have distinct metabolic characteristics, such as insulin resistance, increased lipolysis, elevated free fatty acids (FFA), and ceramide levels, which are discussed in this section. The goal of this research project is to create a framework for bringing together our knowledge of inflammation-mediated insulin resistance.

C1q/tumor necrosis factor-related protein 9 protects cultured chondrocytes from IL-1β-induced inflammatory injury by inhibiting NLRP3 inflammasome activation via the AdipoR1/AMPK axis

C1q/tumor necrosis factor-related protein 9 (CTRP9) has been identified as a novel anti-inflammatory factor that participates in numerous pathological conditions. However, whether CTRP9 participates in the regulation of osteoarthritis has not been studied. This work sought to determine the possible role of CTRP9 in osteoarthritis using an in vitro model, namely interleukin-1β (IL-1β)-stimulated chondrocytes. There was a decreased level of CTRP9 in chondrocytes after IL-1β stimulation. CTRP9 upregulation dramatically repressed IL-1β-evoked apoptosis and inflammatory response in cultured chondrocytes. The mechanistic investigation revealed that CTRP9 overexpression restrained the activation of the nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome in IL-1β-stimulated chondrocytes via the adiponectin receptor 1 (AdipoR1)/adenosine monophosphate-activated protein kinase (AMPK) axis. Notably, inhibition of AdipoR1 or AMPK abolished the regulatory effects of CTRP9 overexpression on IL-1β-evoked apoptosis and inflammasome activation. Overall, the results of this work delineate that CTRP9 protects cultured chondrocytes from IL-1β-induced inflammatory injury by inhibiting NLRP3 inflammasome activation via the AdipoR1/AMPK axis. This work underscores a potential role of CTRP9 in the progression of osteoarthritis.

The contribution of sterile inflammation to the fatty liver disease and the potential therapies

Hepatic inflammation is prevalent in several metabolic liver diseases. Recent scientific advances about the pathogenesis of metabolic liver diseases showed an emerging role of several damage-associated molecular patterns (DAMPs), including DNA, high-mobility group box 1 (HMGB1), ATP and uric acid. For these DAMPs to induce inflammation, they should stimulate pattern recognition receptors (PRRs), which are located in the hepatic immune cells like resident Kupffer cells, infiltrated neutrophils, monocytes or dendritic cells. As a consequence, proinflammatory cytokines like interleukins (ILs)-1β and 18 alongside tumor necrosis factor (TNF)-α are overproduced and released, leading to pronounced hepatic inflammation and cellular death. This review highlights the contribution of these DAMPs and PRRs in the settings of alcoholic and nonalcoholic steatohepatitis. The review also summarizes the therapeutic usefulness of targeting NLR family pyrin domain containing 3 (NLRP3)-inflammasome, Toll-like receptors (TLRs) 4 and 9, IL-1 receptor (IL-1R), caspase 1, uric acid and GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) in these hepatic inflammatory disorders.

Loop Between NLRP3 Inflammasome and Reactive Oxygen Species

Significance: Inflammasomes are cytosolic multiprotein complexes that mediate innate immune pathways. Inflammasomes activate inflammatory caspases and regulate inflammatory cytokines interleukin (IL)-1β and IL-18 as well as inflammatory cell death (pyroptosis). Among known inflammasomes, NLRP3 (NLR family pyrin domain containing 3) inflammasome is unique and well studied owing to the fact that it senses a broad range of stimuli and is implicated in the pathogenesis of both microbial and sterile inflammatory diseases. Recent Advances: Reactive oxygen species (ROS), especially derived from the mitochondria, are one of the critical mediators of NLRP3 inflammasome activation. Furthermore, NLRP3 inflammasome-driven inflammation recruits inflammatory cells, including macrophages and neutrophils, which in turn cause ROS production, suggesting a feedback loop between ROS and NLRP3 inflammasome. Critical Issues: The precise mechanism of how ROS affects NLRP3 inflammasome activation still need to be addressed. This review will summarize the current knowledge on the molecular mechanisms underlying the activation of NLRP3 inflammasome with particular emphasis on the intricate balance of feedback loop between ROS and inflammasome activation. Future Directions: Understanding that this relationship is loop rather than traditionally understood linear mechanism will enable to fine-tune inflammasome activation under varied pathological settings. Antioxid. Redox Signal. 36, 784-796.

The value of plasma insulin-like growth factor 1 and interleukin-18 in the diagnosis of bronchopulmonary dysplasia in premature infants

OBJECTIVE

To explore the diagnostic value of IGF-1 and IL-18 in premature infants with BPD.

METHODS

Through a prospective observational study, the serum samples of infants in the BPD group and the non-BPD group were collected at different targeted time points, and the serum IGF-1 and IL-18 concentrations were dynamically monitored by ELISA. The Student t-test and one-way analysis of variance were adopted to analyze data, and the receiver operating characteristic (ROC) curve was used to test the diagnostic value.

RESULT

A total of 90 VLBW premature infants admitted to NICU between January 2020 and 2021 were finally included. Compared with the non-BPD group, infants diagnosed with BPD had a significantly lower serum concentration of IGF-1 (P < 0.05) but a higher level of IL-18 (P < 0.05) on days 1, 7, 14, and 28 after birth. With the ROC curve analysis, the serum concentration IGF-1 on day 14 and IL-18 on day 28 reported high sensitivity and specificity to predict the risk of BPD (IGF-1: sensitivity: 89.29%, specificity: 77.78%, AUC: 0.8710; IL-18: sensitivity: 53.57%, specificity: 83.33%, AUC: 0.7887). And more substantial predictive power was found in combined analysis of IGF-1 and serum IL-18 on day 14: the sensitivity was 91.07% and the specificity was 83.33%, with the AUC of 0.9142.

CONCLUSION

IGF-1 and IL-18 might be closely involved in the occurrence and development of BPD. The serum concentration of IGF-1 combined with IL-18 could be potentially sensitive markers for the early diagnosis and severity of BPD.

Purinergic signaling as a new mechanism underlying physical exercise benefits: a narrative review

In the last years, it has become evident that both acute and chronic physical exercise trigger responses/adaptations in the purinergic signaling and these adaptations can be considered one important mechanism related to the exercise benefits for health improvement. Purinergic system is composed of enzymes (ectonucleotidases), receptors (P1 and P2 families), and molecules (ATP, ADP, adenosine) that are able to activate these receptors. These components are widely distributed in almost all cell types, and they respond/act in a specific manner depending on the exercise types and/or intensities as well as the cell type (organ/tissue analyzed). For example, while acute intense exercise can be associated with tissue damage, inflammation, and platelet aggregation, chronic exercise exerts anti-inflammatory and anti-aggregant effects, promoting health and/or treating diseases. All of these effects are dependent on the purinergic signaling. Thus, this review was designed to cover the aspects related to the relationship between physical exercise and purinergic signaling, with emphasis on the modulation of ectonucleotidases and receptors. Here, we discuss the impact of different exercise protocols as well as the differences between acute and chronic effects of exercise on the extracellular signaling exerted by purinergic system components. We also reinforce the concept that purinergic signaling must be understood/considered as a mechanism by which exercise exerts its effects.

Fundamentals of Membrane Lipid Replacement: A Natural Medicine Approach to Repairing Cellular Membranes and Reducing Fatigue, Pain, and Other Symptoms While Restoring Function in Chronic Illnesses and Aging

Membrane Lipid Replacement (MLR) uses natural membrane lipid supplements to safely replace damaged, oxidized lipids in membranes in order to restore membrane function, decrease symptoms and improve health. Oral MLR supplements contain mixtures of cell membrane glycerolphospholipids, fatty acids, and other lipids, and can be used to replace and remove damaged cellular and intracellular membrane lipids. Membrane injury, caused mainly by oxidative damage, occurs in essentially all chronic and acute medical conditions, including cancer and degenerative diseases, and in normal processes, such as aging and development. After ingestion, the protected MLR glycerolphospholipids and other lipids are dispersed, absorbed, and internalized in the small intestines, where they can be partitioned into circulating lipoproteins, globules, liposomes, micelles, membranes, and other carriers and transported in the lymphatics and blood circulation to tissues and cellular sites where they are taken in by cells and partitioned into various cellular membranes. Once inside cells, the glycerolphospholipids and other lipids are transferred to various intracellular membranes by lipid carriers, globules, liposomes, chylomicrons, or by direct membrane-membrane interactions. The entire process appears to be driven by 'bulk flow' or mass action principles, where surplus concentrations of replacement lipids can stimulate the natural exchange and removal of damaged membrane lipids while the replacement lipids undergo further enzymatic alterations. Clinical studies have demonstrated the advantages of MLR in restoring membrane and organelle function and reducing fatigue, pain, and other symptoms in chronic illness and aging patients.

CBD Alleviates Liver Injuries in Alcoholics With High-Fat High-Cholesterol Diet Through Regulating NLRP3 Inflammasome-Pyroptosis Pathway

Alcohol abuse and high-fat diet–induced liver diseases have been the most prevalent chronic liver diseases and the leading reasons for liver transplantation around the world. Cannabidiol (CBD) is a botanical component extracted from marijuana plants without psychoactive impact. In our previous reports, we found that CBD can prevent fatty liver induced by Lieber–DeCarli ethanol diet or non-alcoholic fatty liver disease (NAFLD) induced by high-fat high-cholesterol diet. The current work is a further study on whether CBD can alleviate liver injuries induced by ethanol plus high-fat high-cholesterol diet (EHFD), which is a model simulating heavy alcohol drinkers in a Western diet. A mice liver injury model induced by EHFD for 8 weeks was applied to explore the protective properties of CBD and the underlying mechanisms. We found that CBD prevented liver steatosis and oxidative stress induced by EHFD. CBD treatment inhibited macrophage recruitment and suppressed activation of NFκB–NLRP3–pyroptosis pathway in mice livers. The hepatoprotective property of CBD in the current model might be a result of inhibition of inflammation via alleviating activation of the hepatic NFκB–NLRP3 inflammasome–pyroptosis pathway by CBD.

Hepatic protective effects of Shenling Baizhu powder, a herbal compound, against inflammatory damage via TLR4/NLRP3 signalling pathway in rats with nonalcoholic fatty liver disease

OBJECTIVE

High-fat diet (HFD) and inflammation are two key contributors to nonalcoholic fatty liver disease (NAFLD). Shenling Baizhu powder (SLBZP), a classical herbal compound, has been successfully used to alleviate NAFLD. However, its specific mechanisms are not fully understood. In this study, we assessed the anti-NAFLD effect of SLBZP in vivo.

METHODS

Rats were fed an HFD with or without SLBZP or with probiotics. At the end of week 16, an echo magnetic resonance imaging (EchoMRI) body composition analyser was used to quantitatively analyse body composition; a micro-computed tomography (micro-CT) imaging system was used to evaluate whole body and liver fat; and the Moor full-field laser perfusion imager 2 was used to assess liver microcirculation, after which, all rats were sacrificed. Then, biochemical indicators in the blood and the ultrastructure of rat livers were evaluated. Protein expression related to the liver Toll-like receptor 4 (TLR4)/Nod-like receptor family pyrin domain-containing 3 (NLRP3) signalling pathway was assessed using Western blot analysis. Further, high-throughput screening of 29 related inflammatory factors in liver tissue was performed using a cytokine array.

RESULTS

SLBZP supplementation reduced body weight, serum free fatty acid, and insulin resistance index (P < 0.05). It also ameliorated liver microcirculation and ultrastructural abnormalities. EchoMRI and micro-CT quantitative analyses showed that treatment with SLBZP reduced fat mass and visceral fat (P < 0.05 and P < 0.01, respectively). In addition, SLBZP decreased the expression of lipopolysaccharide (LPS)-activated TLR4/NLRP3 signalling pathway-related proteins and altered the expression levels of some inflammatory cytokines in liver tissues.

CONCLUSION

SLBZP can inhibit NLRP3 inflammasome activation and interleukin-1β release by suppressing LPS-induced TLR4 expression in rats with HFD-induced NAFLD. Thus, SLBZP may be beneficial for the prevention and treatment of inflammatory damage and associated diseases.

Vitamin D ameliorates high-fat-diet-induced hepatic injury via inhibiting pyroptosis and alters gut microbiota in rats

Accumulating evidence suggests that vitamin D (VD) has a therapeutic effect on non-alcoholic fatty liver disease (NAFLD). Pyroptosis and gut microbiota have been recognized as critical factors of the progression of NAFLD. However, the effect of VD on the pyroptosis and gut microbiota in NAFLD remains inconclusive. Herein, rats were fed high fat diet (HFD) for 12 weeks and concurrently treated with 5 μg/kg 1,25(OH)₂D₃ twice a week. BRL-3A cells were stimulated with 0.4 mmol/L palmitic acid (PA) and 1 μg/ml lipopolysaccharide (LPS) for 16 h and treated with 10^-6 mol/L 1,25(OH)₂D₃. Effect of VD on the hepatic injury, lipid accumulation, activation of NLRP3 inflammasome and pyroptosis was determined in vivo and in vitro. Next, gasdermin D N-terminal (GSDMD-N) fragment was overexpressed in BRL-3A cells to investigate the role of pyroptosis in the therapeutic effect of VD on NAFLD. In addition, gut microbiota in NAFLD rats was also analyzed. Results showed that VD attenuated HFD-induced hepatic injury in vivo and PA-LPS-induced impairment of cell viability in vitro, and inhibited lipid accumulation, activation of NLRP3 inflammasome and pyroptosis in vivo and in vitro. GSDMD-N fragment overexpression suppressed the protective effect of VD on PA-LPS-induced activation of NLRP3 inflammasome, impairment of cell viability and lipid accumulation, indicating that VD might attenuate NAFLD through inhibiting pyroptosis. Additionally, VD also restored HFD-induced gut microbiota dysbiosis by increasing the relative abundance of Lactobacillus and reducing that of Acetatifactor, Oscillibacter and Flavonifractor. This study provides a novel mechanism underlying VD therapy against NAFLD.

Implication of the NLRP3 Inflammasome in Bovine Age-Related Sarcopenia

Sarcopenia is defined as the age-related loss of skeletal muscle mass, quality, and strength. The pathophysiological mechanisms underlying sarcopenia are still not completely understood. The aim of this work was to evaluate, for the first time, the expression of NLRP3 inflammasome in bovine skeletal muscle in order to investigate the hypothesis that inflammasome activation may trigger and sustain a pro-inflammatory environment leading to sarcopenia. Samples of skeletal muscle were collected from 60 cattle belonging to three age-based groups. Morphologic, immunohistochemical and molecular analysis were performed to assess the presence of age-related pathologic changes and chronic inflammation, the expression of NLRP3 inflammasome and to determine the levels of interleukin-1β, interleukin-18 and tumor necrosis factor alpha in muscle tissue. Our results revealed the presence of morphologic sarcopenia hallmark, chronic lymphocytic inflammation and a type II fibers-selective NLRP3 expression associated to a significant decreased number of immunolabeled-fibers in aged animals. Moreover, we found a statistically significant age-related increase of pro-inflammatory cytokines such as interleukin-1β and interleukin-18 suggesting the activation of NLRP3 inflammasome. Taken together, our data suggest that NLRP3 inflammasome components may be normally expressed in skeletal muscle, but its priming and activation during aging may contribute to enhance a pro-inflammatory environment altering normal muscular anabolism and metabolism.

NLRP3 Inflammasome at the Interface of Inflammation, Endothelial Dysfunction, and Type 2 Diabetes

Type 2 diabetes mellitus (T2DM), accounting for 90–95% cases of diabetes, is characterized by chronic inflammation. The mechanisms that control inflammation activation in T2DM are largely unexplored. Inflammasomes represent significant sensors mediating innate immune responses. The aim of this work is to present a review of links between the NLRP3 inflammasome, endothelial dysfunction, and T2DM. The NLRP3 inflammasome activates caspase-1, which leads to the maturation of pro-inflammatory cytokines interleukin 1β and interleukin 18. In this review, we characterize the structure and functions of NLRP3 inflammasome as well as the most important mechanisms and molecules engaged in its activation. We present evidence of the importance of the endothelial dysfunction as the first key step to activating the inflammasome, which suggests that suppressing the NLRP3 inflammasome could be a new approach in depletion hyperglycemic toxicity and in averting the onset of vascular complications in T2DM. We also demonstrate reports showing that the expression of a few microRNAs that are also known to be involved in either NLRP3 inflammasome activation or endothelial dysfunction is deregulated in T2DM. Collectively, this evidence suggests that T2DM is an inflammatory disease stimulated by pro-inflammatory cytokines. Finally, studies revealing the role of glucose concentration in the activation of NLRP3 inflammasome are analyzed. The more that is known about inflammasomes, the higher the chances to create new, effective therapies for patients suffering from inflammatory diseases. This may offer potential novel therapeutic perspectives in T2DM prevention and treatment.

Inhibition of NLRP3-inflammasome mediated IL-1β release by phenylpropanoic acid derivatives: in-silico and in-vitro approach

NLRP3 inflammasome activation and subsequent release of IL-1β are being explored as a causal pathology for inflammatory and autoimmune disorders. Modulation of this pathway by the compounds from natural sources may provide a better targeted approach with improved therapeutic outcome. The study was carried out to test the ability of phenylpropanoic acid derivatives to inhibit the NLRP3 inflammasome pathway and IL-1β release. The main purpose of the study was to test the active derivatives with respect to the possible molecular interactions in-silico, effect on mRNA expression of molecular markers and, effect on released cytokine. Autodock along with SwissADME was used to carry out the in-silico studies including the prediction studies as well as molecular docking studies. The effect of test compounds on mRNA expression of important proteins was evaluated against U87MG cells using RT-qPCR. The changes in released cytokine levels was evaluated using ELISA. The tested phenylpropanoic acid derivatives had a comparable molecular docking profile to that of selected standards. The prediction studies indicated that these compounds have suitable properties to be a drug candidate. mRNA expression studies showed that the derivatives can downregulate the proteins responsible for inflammasome activation and same was reflected in ELISA when the concentration of released cytokine was evaluated. Based on the above results, phenylpropanoic acid derivatives have potential to be developed as specific NLRP3-inflammasome inhibitors.

Next Generation Health Claims Based on Resilience: The Example of Whole-Grain Wheat

Health claims on foods are a way of informing consumers about the health benefits of a food product. Traditionally, these claims are based on scientific evaluation of markers originating from a pharmacological view on health. About a decade ago, the definition of health has been rephrased to 'the ability to adapt' that opened up the possibility for a next generation of health claims based on a new way of quantifying health by evaluating resilience. Here, we would like to introduce an opportunity for future scientific substantiation of health claims on food products by using whole-grain wheat as an example. Characterization of the individual whole wheat grain food product or whole wheat flour would probably be considered as sufficiently characterized by the European Food Safety Authority, while the food category whole grain is not specific enough. Meta-analysis provides the scientific evidence that long-term whole-grain wheat consumption is beneficial for health, although results from single 'gold standard' efficacy studies are not always straight forward based on classic measurement methods. Future studies may want to underpin the scientific argumentation that long-term whole grain wheat consumption improves resilience, by evaluating the disruption and rate of a selected panel of blood markers in response to a standardized oral protein glucose lipid tolerance test and aggregated into biomarkers with substantiated physiological benefits, to make a next-generation health claim for whole-grain wheat achievable in the near future.

Autophagy, One of the Main Steps in Periodontitis Pathogenesis and Evolution

Periodontitis represents a complex inflammatory disease that compromises the integrity of the tooth-supporting tissue through the interaction of specific periodontal pathogens and the host’s immune system. Experimental data help to outline the idea that the molecular way towards periodontitis initiation and progression presents four key steps: bacterial infection, inflammation, oxidative stress, and autophagy. The aim of this review is to outline the autophagy involvement in the pathogenesis and evolution of periodontitis from at least three points of view: periodontal pathogen invasion control, innate immune signaling pathways regulation and apoptosis inhibition in periodontal cells. The exact roles played by reactive oxygen species (ROS) inside the molecular mechanisms for autophagy initiation in periodontitis still require further investigation. However, clarifying the role and the mechanism of redox regulation of autophagy in the periodontitis context may be particularly beneficial for the elaboration of new therapeutic strategies.

Energy Provisioning and Inflammasome Activation: The Pivotal Role of AMPK in Sterile Inflammation and Associated Metabolic Disorders

BACKGROUND

Body defenses and metabolic processes probably co-evolved in such a way that rapid, energy-intensive acute inflammatory repair is functionally integrated with energy allocation in a starvation/ infection / injury-prone primitive environment. Disruptive metabolic surplus, aggravated by sedentary lifestyle induces chronic under-activation of AMPK, the master regulator of intracellular energy homeostasis. Sudden increase in chronic, dysregulated 'sterile' inflammatory disorders probably results from a shift towards calorie rich, sanitized, cushioned, injury/ infection free environment, repositioning inflammatory repair pathways towards chronic, non-microbial, 'sterile', 'low grade', and 'parainflammation'. AMPK, (at the helm of energy provisioning) supervises the metabolic regulation of inflammasome activation, a common denominator in lifestyle disorders.

DISCUSSION

In this review, we discuss various pathways linking AMPK under-activation and inflammasome activation. AMPK under-activation, the possible norm in energy-rich sedentary lifestyle, could be the central agency that stimulates inflammasome activation by multiple pathways such as 1: decreasing autophagy, and accumulation of intracellular DAMPs, (particulate crystalline molecules, advanced glycation end-products, oxidized lipids, etc.) 2: stimulating a glycolytic shift (pro-inflammatory) in metabolism, 3: promoting NF-kB activation and decreasing Nrf2 activation, 4: increasing reactive oxygen species (ROS) formation, Unfolded Protein Response (UPR) and Endoplasmic Reticulum (ER) stress.

CONCLUSION

The 'inverse energy crisis' associated with calorie-rich, sedentary lifestyle, advocates dietary and pharmacological interventions for treating chronic metabolic disorders by overcoming / reversing AMPK under-activation.

A Specific Strain of Lactic Acid Bacteria, Lactobacillus paracasei, Inhibits Inflammasome Activation In Vitro and Prevents Inflammation-Related Disorders

Some strains of lactic acid bacteria (LAB) have anti-inflammatory effects, but the mechanism underlying the alleviation of inflammation by LAB is not fully understood. In this study, we examined the inhibitory effect of a certain strain of LAB, Lactobacillus paracasei, on inflammasome activation, which is associated with various inflammatory disorders. Using bone marrow-derived macrophages from BALB/c mice, we found that L. paracasei, but not L. rhamnosus, suppressed NLRP3 inflammasome activation and inhibited subsequent caspase-1 activation and IL-1β secretion. L. paracasei also had inhibitory effects on AIM2 and NLRC4 inflammasome activation as well as the NLRP3 inflammasome. These inhibitory effects of L. paracasei on inflammasome activation were dependent on autocrine IL-10 induced by L. paracasei-stimulated macrophages. Furthermore, IL-10 production by L. paracasei-stimulated macrophages was involved with phagocytosis and the NOD2 signaling pathway in macrophages. In addition to in vitro studies, oral administration of L. paracasei in C57BL/6 mice reduced monosodium urate crystal-induced peritoneal inflammation in vivo. Moreover, continuous intake of L. paracasei in C57BL/6 mice alleviated high fat diet-induced insulin resistance and aging-induced expression of biomarkers for T cell senescence. Taken together, we demonstrated that L. paracasei inhibits inflammasome activation in vitro and exhibits an anti-inflammatory function in vivo. These results indicate that LAB that have inhibitory effects on inflammasome activation might contribute to the alleviation of inflammation-related disorders.

Innate immunity as a target for acute cardioprotection

Acute obstruction of a coronary artery causes myocardial ischaemia and if prolonged, may result in an ST-segment elevation myocardial infarction (STEMI). First-line treatment involves rapid reperfusion. However, a highly dynamic and co-ordinated inflammatory response is rapidly mounted to repair and remove the injured cells which, paradoxically, can further exacerbate myocardial injury. Furthermore, although cardiac remodelling may initially preserve some function to the heart, it can lead over time to adverse remodelling and eventually heart failure. Since the size of the infarct corresponds to the subsequent risk of developing heart failure, it is important to find ways to limit initial infarct development. In this review, we focus on the role of the innate immune system in the acute response to ischaemia-reperfusion (IR) and specifically its contribution to cell death and myocardial infarction. Numerous danger-associated molecular patterns are released from dying cells in the myocardium, which can stimulate pattern recognition receptors including toll like receptors and NOD-like receptors (NLRs) in resident cardiac and immune cells. Activation of the NLRP3 inflammasome, caspase 1, and pyroptosis may ensue, particularly when the myocardium has been previously aggravated by the presence of comorbidities. Evidence will be discussed that suggests agents targeting innate immunity may be a promising means of protecting the hearts of STEMI patients against acute IR injury. However, the dosing and timing of such agents should be carefully determined because innate immunity pathways may also be involved in cardioprotection. This article is part of a Cardiovascular Research Spotlight Issue entitled 'Cardioprotection Beyond the Cardiomyocyte', and emerged as part of the discussions of the European Union (EU)-CARDIOPROTECTION Cooperation in Science and Technology (COST) Action, CA16225.

Cellular Interplay as a Consequence of Inflammatory Signals Leading to Liver Fibrosis Development

Inflammation has been known to be an important driver of fibrogenesis in the liver and onset of hepatic fibrosis. It starts off as a process meant to protect the liver from further damage, but it can become the main promoter of liver fibrosis. There are many inflammation-related pathways activated during liver fibrosis that lead to hepatic stellate cells (HSCs) activation and collagen-deposition in the liver. Such events are mostly modulated upstream of HSCs and involve signals from hepatocytes and innate immune cells. One particular event is represented by cell death during liver injury that generates multiple inflammatory signals that further trigger sterile inflammation and enhancement of inflammatory response. The assembly of inflammasome that responds to danger-associated molecular patterns (DAMPs) stimulates the release of pro-inflammatory cytokines and at the same time, initiates programmed cell death called pyroptosis. This review focuses on cellular and molecular mechanisms responsible for initiation and progress of inflammation in the liver.

Role of NLRP3 inflammasome in inflammatory bowel diseases

Inflammasomes are multiprotein intracellular complexes which are responsible for the activation of inflammatory responses. Among various subtypes of inflammasomes, NLRP3 has been a subject of intensive investigation. NLRP3 is considered to be a sensor of microbial and other danger signals and plays a crucial role in mucosal immune responses, promoting the maturation of proinflammatory cytokines interleukin 1β (IL-1β) and IL-18. NLRP3 inflammasome has been associated with a variety of inflammatory and autoimmune conditions, including inflammatory bowel diseases (IBD). The role of NLRP3 in IBD is not yet fully elucidated as it seems to demonstrate both pathogenic and protective effects. Studies have shown a relationship between genetic variants and mutations in NLRP3 gene with IBD pathogenesis. A complex interaction between the NLRP3 inflammasome and the mucosal immune response has been reported. Activation of the inflammasome is a key function mediated by the innate immune response and in parallel the signaling through IL-1β and IL-18 is implicated in adaptive immunity. Further research is needed to delineate the precise mechanisms of NLRP3 function in regulating immune responses. Targeting NLRP3 inflammasome and its downstream signaling will provide new insights into the development of future therapeutic strategies.

Current and Future Nutritional Strategies to Modulate Inflammatory Dynamics in Metabolic Disorders

Obesity, type 2 diabetes, and other metabolic disorders have a large impact on global health, especially in Western countries. An important hallmark of metabolic disorders is chronic low-grade inflammation. A key player in chronic low-grade inflammation is dysmetabolism, which is defined as the inability to keep homeostasis resulting in loss of lipid control, oxidative stress, inflammation, and insulin resistance. Although often not yet detectable in the circulation, chronic low-grade inflammation can be present in one or multiple organs. The response to a metabolic challenge containing lipids may magnify dysfunctionalities at the tissue level, causing an overflow of inflammatory markers into the circulation and hence allow detection of early low-grade inflammation. Here, we summarize the evidence of successful application of metabolic challenge tests in type 2 diabetes, metabolic syndrome, obesity, and unhealthy aging. We also review how metabolic challenge tests have been successfully applied to evaluate nutritional intervention effects, including an "anti-inflammatory" mixture, dark chocolate, whole grain wheat and overfeeding. Additionally, we elaborate on future strategies to (re)gain inflammatory flexibility. Through epigenetic and metabolic regulation, the inflammatory response may be trained by regular mild and metabolic triggers, which can be understood from the perspective of trained immunity, hormesis and pro-resolution. New strategies to optimize dynamics of inflammation may become available.

NLRP6 deficiency aggravates liver injury after allogeneic hematopoietic stem cell transplantation

This study aims to observe the expression and role of NLRP6 in liver injury after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). Allo-HSCT model was established through infusion of 5 × 10⁶ bone marrow mononuclear cells into whole body irradiated mice. On days 7, 14, 21 and 28 after transplantation, the peripheral blood was collected to detect liver function. The liver of the mice was obtained to assess the pathological changes of liver tissues after allo-HSCT by H&E staining and Mason staining. Meanwhile, expression of NLRP6, phosphorylated p38-MAPK and IκBα, caspase-1 and NLRP3 in liver were detected by Western blot. ELISA was used for detection of the level of interleukin (IL)-1β, IL-18, tumor necrosis factor (TNF)-α, IL-6, myeloperoxidase (MPO) and tumor growth factor (TGF)-β1. Increased expression of NLRP6, phosphorylated Iκbα, phosphorylated p38-MAPK, pro-caspase-1, and p20, in liver tissue with injury and fibrosis in mice after allo-HSCT were observed. Meanwhile, the level of IL-1β, IL-18, IL-6 and TNF-α was also increased. However, NLRP6^-/- mice showed more severe liver damage and liver fibrosis after transplantation together with higher level of phosphorylated Iκbα, phosphorylated p38-MAPK, Pro-caspase-1, p20 expression as well as IL-1β, IL-18, IL-6, and TNF-α secretion compared with wide-type. Interestingly, the expression of NLRP3 in the liver of NLRP6^-/- mice was significantly higher than that of wild-type. In conclusion, the expression of NLRP6 in host's liver is associated with liver injury after allo-HSCT. NLRP6 deficiency in host's liver leads to more severe liver damage, indicating a protective role of NLRP6 in host's liver to liver damage after allo-HSCT.

Caffeine Inhibits NLRP3 Inflammasome Activation by Suppressing MAPK/NF-κB and A2aR Signaling in LPS-Induced THP-1 Macrophages

Excessive inflammation induced by various risk factors is associated with the development of bronchopulmonary dysplasia (BPD). Caffeine exerts potent anti-inflammatory effects as a clinical preventive medicine for BPD. Recently, NLRP3 inflammasome activation has been demonstrated to be essential for the pathogenesis of BPD. In the present study, we aimed to investigate the effects of caffeine on NLRP3 inflammasome activation in LPS-induced THP-1 macrophages and to explore the underlying the detailed mechanism. We found that caffeine significantly reduced NLRP3 expression, ASC speck formation, and caspase 1 cleavage and therefore decreased IL-1β and IL-18 secretion in THP-1 macrophages. Caffeine also markedly decreased the phosphorylation levels of MAPK and NF-κB pathway members, further suppressing the translocation of NF-κB in THP-1 macrophages. Moreover, silencing of the caffeine-antagonized adenosine A2a receptor (A2aR) significantly decreased cleaved caspase 1 expression in THP-1 macrophages by reducing ROS production. Given these findings, we conclude that caffeine inhibits NLRP3 inflammasome activation by suppressing MAPK/NF-κB signaling and A2aR-associated ROS production in LPS-induced THP-1 macrophages.

Comparative Transcriptome Analyses Provide Potential Insights into the Molecular Mechanisms of Astaxanthin in the Protection against Alcoholic Liver Disease in Mice

Alcoholic liver disease (ALD) is a major cause of chronic liver disease worldwide. It is a complex process, including a broad spectrum of hepatic lesions from fibrosis to cirrhosis. Our previous study suggested that astaxanthin (AST) could alleviate the hepatic inflammation and lipid dysmetabolism induced by ethanol administration. In this study, a total of 48 male C57BL/6J mice were divided into 4 groups: a Con group (fed with a Lieber–DeCarli liquid diet), an AST group (fed with a Lieber–DeCarli liquid diet and AST), an Et group (fed with an ethanol-containing Lieber–DeCarli liquid diet), and a EtAST group (fed with an ethanol-containing Lieber–DeCarli liquid diet and AST). Then, comparative hepatic transcriptome analysis among the groups was performed by Illumina RNA sequencing. Gene enrichment analysis was conducted to identify pathways affected by the differentially expressed genes. Changes of the top genes were verified by quantitative real-time PCR (qRT-PCR) and Western blot. A total of 514.95 ± 6.89, 546.02 ± 15.93, 576.06 ± 21.01, and 690.85 ± 54.14 million clean reads were obtained for the Con, AST, Et, and EtAST groups, respectively. Compared with the Et group, 1892 differentially expressed genes (DEGs) (including 351 upregulated and 1541 downregulated genes) were identified in the AST group, 1724 differentially expressed genes (including 233 upregulated and 1491 downregulated genes) were identified in the Con group, and 1718 DEGs (including 1380 upregulated and 338 downregulated genes) were identified in the EtAST group. The enrichment analyses revealed that the chemokine signaling, the antigen processing and presentation, the nucleotide-binding and oligomerization domain (NOD)-like receptor signaling, and the Toll-like receptor signaling pathways enriched the most differentially expressed genes. The findings of this study provide insights for the development of nutrition-related therapeutics for ALD.

Dual Role of PTPN22 but Not NLRP3 Inflammasome Polymorphisms in Type 1 Diabetes and Celiac Disease in Children

Genetic polymorphisms in genes coding for inflammasome components nucleotide-binding oligomerization domain leucine rich repeat and pyrin domain-containing protein 3 (NLRP3) and caspase recruitment domain-containing protein 8 (CARD8) have been associated with autoinflammatory and autoimmune diseases. On the other hand several studies suggested that NLRP3 inflammasome contributes to maintenance of gastrointestinal immune homeostasis and that activation of NLRP3 is regulated by protein tyrosine phosphatase non-receptor 22 (PTPN22). PTPN22 polymorphism was implicated in the risk for various autoimmune diseases including type 1 diabetes (T1D) but not for celiac disease (CD). The aim of our study was to evaluate the role of inflammasome related polymorphisms in subjects with either T1D or CD as well as in subjects affected by both diseases. We examined PTPN22 rs2476601 (p.Arg620Trp), NLRP3 rs35829419 (p.Gln705Lys), and CARD8 rs2043211 (p.Cys10Ter) in 66 subjects with coexisting T1D and CD, 65 subjects with T1D who did not develop CD, 67 subjects diagnosed only with CD and 127 healthy unrelated Slovenian individuals. All results were adjusted for clinical characteristic and human leukocyte antigen (HLA) risk. PTPN22 rs2476601 allele was significantly more frequent among subjects with T1D (P_adj = 0.001) and less frequent in subjects with CD (P_adj = 0.039) when compared to controls. In patients with coexisting T1D and CD this variant was significantly less frequent compared to T1D group (P_adj = 0.010). Protective effect on CD development in individuals with T1D was observed only within the low risk HLA group. On the other hand, we found no association of NLRP3 rs35829419 and CARD8 rs2043211 with the development of T1D, CD or both diseases together. In conclusion PTPN22 rs2476601polymorphism was significantly associated with the risk of developing T1D in Slovenian population, while no associations of proinflammatory NLRP3 and CARD8 polymorphisms with T1D and CD were observed. Interestingly, the same PTPN22 variant protected from CD. We hypothesize that this effect may be mediated through the NLRP3 inflammasome activation.

NLRP3 Inflammasome: A Possible Link Between Obesity-Associated Low-Grade Chronic Inflammation and Colorectal Cancer Development

Emerging evidence reveals that adipose tissue-associated inflammation is a main mechanism whereby obesity promotes colorectal cancer risk and progression. Increased inflammasome activity in adipose tissue has been proposed as an important mediator of obesity-induced inflammation and insulin resistance development. Chronic inflammation in tumor microenvironments has a great impact on tumor development and immunity, representing a key factor in the response to therapy. In this context, the inflammasomes, main components of the innate immune system, play an important role in cancer development showing tumor promoting or tumor suppressive actions depending on the type of tumor, the specific inflammasome involved, and the downstream effector molecules. The inflammasomes are large multiprotein complexes with the capacity to regulate the activation of caspase-1. In turn, caspase-1 enhances the proteolytic cleavage and the secretion of the inflammatory cytokines interleukin (IL)-1β and IL-18, leading to infiltration of more immune cells and resulting in the generation and maintenance of an inflammatory microenvironment surrounding cancer cells. The inflammasomes also regulate pyroptosis, a rapid and inflammation-associated form of cell death. Recent studies indicate that the inflammasomes can be activated by fatty acids and high glucose levels linking metabolic danger signals to the activation of inflammation and cancer development. These data suggest that activation of the inflammasomes may represent a crucial step in the obesity-associated cancer development. This review will also focus on the potential of inflammasome-activated pathways to develop new therapeutic strategies for the prevention and treatment of obesity-associated colorectal cancer development.

Inhibitory Effects of Toll-Like Receptor 4, NLRP3 Inflammasome, and Interleukin-1β on White Adipocyte Browning

Adipose tissue expansion is accompanied by infiltration and accumulation of pro-inflammatory macrophages, which links obesity to pathologic conditions such as type 2 diabetes. However, little is known regarding the role of pro-inflammatory adipose tissue remodeling in the thermogenic activation of brown/beige fat. Here, we investigated the effect of pattern recognition receptors (PRR) activation in macrophages, especially the toll-like receptor 4 (TLR4) and Nod-like receptor 3 (NLRP3), on white adipocyte browning. We report that TLR4 activation by lipopolysaccharide repressed white adipocyte browning in response to β3-adrenergic receptor activation and caused ROS production and mitochondrial dysfunction, while genetic deletion of TLR4 protected mitochondrial function and thermogenesis. In addition, activation of NLRP3 inflammasome in macrophages attenuated UCP1 induction and mitochondrial respiration in cultures of primary adipocytes, while the absence of NLRP3 protected UCP1 in adipocytes. The effect of NLRP3 inflammasome activation on browning was mediated by IL-1β signaling, as blocking IL-1 receptor in adipocytes protected thermogenesis. We also report that IL-1β interferes with thermogenesis via oxidative stress stimulation and mitochondrial dysfunction as we observed a statistically significant increase in ROS production, decrease in SOD enzyme activity, and increase in mitochondrial depolarization in adipocytes treated with IL-1β. Collectively, we demonstrated that inflammatory response to obesity, such as TLR4 and NLRP3 inflammasome activation as well as IL-1β secretion, attenuates β3-adrenoreceptor-induced beige adipocyte formation via oxidative stress and mitochondrial dysfunction. Our findings provide insights into targeting innate inflammatory system for enhancement of the adaptive thermogenesis against obesity.

Coptidis Rhizoma inhibits NLRP3 inflammasome activation and alleviates renal damage in early obesity-related glomerulopathy

BACKGROUND

Obese subjects have been considered to be in a state of chronic, low-grade systemic inflammation. Excess fat accumulation and persistent inflammation may promote renal dysfunction, to cause chronic kidney disease (CKD) and even end-stage kidney failure. Coptidis Rhizoma is a classical traditional Chinese herb well known for its hypoglycemic and hypolipidemic properties. The mechanism is partially associated with its anti-inflammatory effect. However, this effect is rarely investigated in obesity and obesity-related glomerulopathy (ORG).

PURPOSE

The current study was designed to evaluate the effect of Coptidis Rhizoma on ORG. It also aimed to determine whether this renal protection effect of Coptidis Rhizoma was related to the inhibition of NLRP3 inflammasome in ORG.

METHODS

Coptidis Rhizoma concentrated granules were prepared and the main components were identified by 3D-High Performance Liquid Chromatography (3D-HPLC) assay. The animal model of early stage ORG was established in obesity-prone (OP) rats by high protein and high fat diet feeding for 12 weeks. The treatment with Coptidis Rhizoma at different dosages was administered by intragastric infusion simultaneously. Then body weight, kidney weight, plasma lipid profiles, 24 h urine protein/albumin content and kidney histology were measured. Inflammatory biomarkers were examined both in the rat plasma and renal cortex. The gene expressions of NLRP3 inflammasome complex and NF-κB in renal tissues were also measured.

RESULTS

Coptidis Rhizoma alleviated dyslipidemia and reduced the renal weight of the rats with ORG. Meanwhile, urinary albumin to creatinine ratio and creatinine clearance rate were significantly improved. Coptidis Rhizoma also attenuated glomerular hypertrophy, mesangial hyperplasia, and effacement of podocyte foot in renal tissues of ORG rats. In addition, Coptidis Rhizoma intervention decreased the levels of proinflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18) both in plasma and renal tissue. The gene expression of NLRP3 inflammasome was down-regulated and NF-κB activity was also inhibited by Coptidis Rhizoma in renal tissues of ORG rats.

CONCLUSION

Coptidis Rhizoma can ameliorate early renal damage in ORG rats and the mechanisms appear to be related to the inhibition of NLRP3 inflammasome complex.

Modulation of Macrophage Phenotype by Biodegradable Polyurethane Nanoparticles: Possible Relation between Macrophage Polarization and Immune Response of Nanoparticles

Nanomaterials with surface functionalized by different chemical groups can either provoke or attenuate the immune responses of the nanomaterials, which is critical to their biomedical efficacies. In this study, we demonstrate that synthetic waterborne polyurethane nanoparticles (PU NPs) can inhibit the macrophage polarization toward the M1 phenotype but not M2 phenotype. The surface-functionalized PU NPs decrease the secretion levels of proinflammatory cytokines (TNF-α and IL-1β) for M1 macrophages. Specifically, PU NPs with carboxyl groups on the surface exhibit a greater extent of inhibition on M1 polarization than those with amine groups. These water-suspended PU NPs reduce the nuclear factor-κB (NF-κB) activation and suppress the subsequent NLR family pyrin domain containing 3 (NLRP3) inflammasome signals. Furthermore, the dried PU films assembled from PU NPs have a similar effect on macrophage polarization and present a smaller shifting foreign body reaction (FBR) in vivo than the conventional poly(l-lactic acid). Taken together, the biodegradable waterborne PU NPs demonstrate surface-dependent immunosuppressive properties and macrophage polarization effects. The findings suggest potential therapeutic applications of PU NPs in anti-inflammation and macrophage-related disorders and propose a mechanism for the low FBR observed for biodegradable PU materials.

Pro-atherogenic and pro-oxidant crosstalk between adipocytes and macrophages

PURPOSE

Obesity, which is characterized by triglyceride accumulation mainly in adipocytes but also in arterial wall cells such as macrophages, is a major risk factor for developing atherosclerosis. We aimed to identify the crosstalk related to lipid metabolism and oxidation status between adipocytes and macrophages.

METHODS

We used a co-culture model system with J477A.1 cultured macrophages and 3T3L1 cultured adipocytes. For an in-vivo co-culture system, we used C57BL/6 mouse peritoneal macrophages and visceral or subcutaneous adipose tissue.

RESULTS

Adipocytes significantly increased reactive oxygen species generation, up to twofold, and decreased cholesterol content by 22% in the co-cultured macrophages. Macrophages significantly increased triglyceride-biosynthesis rate by twofold and decreased triglyceride-degradation rate by 30%, resulting in increased triglyceride accumulation in the co-cultured adipocytes by up to 72%. In the in-vivo mouse model, visceral adipose tissue crosstalk with macrophages resulted in a significant pro-atherogenic phenotype with respect to cellular cholesterol metabolism. In contrast, the interaction between subcutaneous adipose tissue and macrophages mostly affected cellular triglyceride metabolism. There were no significant effects on mitochondrial respiration capacity in the macrophages. Upon oxidative-stress reduction in the co-cultured cells using the polyphenol-rich antioxidant, pomegranate juice, the expression of genes related to cellular lipid accumulation was significantly reduced.

CONCLUSIONS

We reveal, for the first time, that paracrine interactions between adipocytes and macrophages result in oxidative stress and lipids metabolic alterations in both cells, toward increased atherogenicity which can be reversed by phenolic antioxidants.

Underrated enemy - from nonalcoholic fatty liver disease to cancers of the gastrointestinal tract

Nonalcoholic fatty liver disease (NAFLD) is intrahepatic ectopic lipid deposition which is present despite a lack of other causes of secondary hepatic fat accumulation. It is the most common chronic liver disorder in the welldeveloped countries. NAFLD is a multidisciplinary disease that affects various systems and organs and is inextricably linked to simple obesity, metabolic syndrome, insulin resistance and overt diabetes mellitus type 2. The positive energy balance related to obesity leads to a variety of systemic changes including modified levels of insulin, insulin- like growth factor-1, adipokines, hepatokines and cytokines. It is strongly linked to carcinogenesis and new evidence proves that NAFLD is associated with higher risk of all-cause mortality and cancer-specific mortality among cancer survivors. This article focuses on the association between NAFLD and extrahepatic gastrointestinal tract cancers, aiming to shed light on the pathomechanism of changes leading to the development of tumors.

Downregulation of the NLRP3 inflammasome by adiponectin rescues Duchenne muscular dystrophy

BACKGROUND

The hormone adiponectin (ApN) exerts powerful anti-inflammatory effects on skeletal muscle and can reverse devastating myopathies, like Duchenne muscular dystrophy (DMD), where inflammation exacerbates disease progression. The NLRP3 inflammasome plays a key role in the inflammation process, and its aberrant activation leads to several inflammatory or immune diseases. Here we investigated the expression of the NLRP inflammasome in skeletal muscle and its contribution to DMD.

RESULTS

We find that NLRP3 is expressed in skeletal muscle and show that ApN downregulates NLRP3 via its anti-inflammatory mediator, miR-711. This repression occurs both in vitro in C2C12 myotubes and in vivo after either local (via muscle electrotransfer) or systemic (by using transgenic mice) ApN supplementation. To explore the role of the NLRP3 inflammasome in a murine model of DMD, we crossed mdx mice with Nlrp3-knockout mice. In mdx mice, all components of the inflammasome were upregulated in muscle, and the complex was overactivated. By contrast, in mdx mice lacking Nlrp3, there was a reduction in caspase-1 activation, inflammation and oxidative stress in dystrophic muscle, and these mice showed higher global muscle force/endurance than regular mdx mice as well as decreased muscle damage. To investigate the relevance of NLPR3 regulation in a human disease context, we characterized NLRP3 expression in primary cultures of myotubes from DMD subjects and found a threefold increase compared to control subjects. This overexpression was attenuated by ApN or miR-711 mimic treatments.

CONCLUSIONS

The NLRP3 inflammasome plays a key pathogenic role in DMD and muscle inflammation, thereby opening new therapeutic perspectives for these and other related disorders.

Curcumin Suppresses IL-1β Secretion and Prevents Inflammation through Inhibition of the NLRP3 Inflammasome

Turmeric is traditionally used as a spice and coloring in foods. Curcumin is the primary active ingredient in the turmeric, and compelling evidence has shown that it has the ability to inhibit inflammation. However, the mechanism mediating its anti-inflammatory effects are not fully understood. We report that curcumin inhibited caspase-1 activation and IL-1β secretion through suppressing LPS priming and the inflammasome activation pathway in mouse bone marrow-derived macrophages. The inhibitory effect of curcumin on inflammasome activation was specific to the NLRP3, not to the NLRC4 or the AIM2 inflammasomes. Curcumin inhibited the NLRP3 inflammasome by preventing K⁺ efflux and disturbing the downstream events, including the efficient spatial arrangement of mitochondria, ASC oligomerization, and speckle formation. Reactive oxygen species, autophagy, sirtuin-2, or acetylated α-tubulin was ruled out as the mechanism by which curcumin inhibits the inflammasome. Importantly, in vivo data show that curcumin attenuated IL-1β secretion and prevented high-fat diet-induced insulin resistance in wide-type C57BL/6 mice but not in Nlrp3-deficient mice. Curcumin also repressed monosodium urate crystal-induced peritoneal inflammation in vivo. Taken together, we identified curcumin as a common NLRP3 inflammasome activation inhibitor. Our findings reveal a mechanism through which curcumin represses inflammation and suggest the potential clinical use of curcumin in NLRP3-driven diseases.

The level of physical training modulates cytokine levels through P2X7 receptor in healthy subjects

INTRODUCTION

The P2X7 receptor-NLRP3 inflammasome complex (P2X7R-Infl) regulates inflammatory and immune responses. Physical exercise modulates heat-shock proteins (Hsps), influencing cytokine levels and oxidative stress; Hsp72 triggers P2X7R-Infl-dependent responses.

SUBJECTS AND METHODS

We studied the effect of a single bout of maximal exercise on lymphomonocyte expression of P2X7R, NLRP3, caspase-1, NF-kB and Hsp72 and circulating levels of IL-1β, IL-18 and MCP-1, all modulated by P2X7R-Infl, in healthy sedentary (SED), trained (ATH), endurance (END) male individuals.

RESULTS

Baseline P2X7R, NLRP3 and Caspase-1 expression progressively increased from SED to ATH and END; NF-kβ showed the same trend. Hsp72 did not differ among groups. Acute exercise strongly reduced P2X7R in all participants, irrespective of their degree of physical training. Inflammasome responses differed across groups: in SED, NLRP3 and Caspase-1 increased; in ATH, NLRP3 reduced and caspase-1 did not vary; in END, NLRP3 and Caspase-1 declined. Baseline IL-1β, higher in END, was unmodified after exercise; IL-18 decreased; MCP-1 doubled in SED, did not vary in ATH, declined in END. In the whole study population, significant direct relationships emerged between P2X7R expression and IL-1β, IL-18, MCP-1 levels, all P < .001; also Caspase-1 related with these markers. A multivariate analysis showed age, BMI and P2X7R as determinants of postexercise IL-1β levels.

CONCLUSION

Endurance show higher P2X7R-Infl expression and function vs SED and ATH; however, maximal exercise determines prevailing pro-inflammatory vs anti-inflammatory responses in untrained and trained participants, respectively, highlighting a likely cause-effect relationship between degree of physical activity and P2X7R-Infl-mediated responses.