Mitochondria, the NLRP3 Inflammasome, and Sirtuins in Type 2 Diabetes: New Therapeutic Targets

Molecular mechanisms of diabetic nephropathy: A narrative review

Diabetic nephropathy (DN) is the predominant secondary nephropathy resulting in global end-stage renal disease. It is attracting significant attention in both domestic and international research due to its widespread occurrence, fast advancement, and limited choices for prevention and treatment. The pathophysiology of this condition is intricate and involves multiple molecular and cellular pathways at various levels. This article provides a concise overview of the molecular processes involved in the development of DN. It discusses various factors, such as signaling pathways, cytokines, inflammatory responses, oxidative stress, cellular damage, autophagy, and epigenetics. The aim is to offer clinicians a valuable reference for DN's diagnosis, treatment, and intervention.

MCC950 as a promising candidate for blocking NLRP3 inflammasome activation: A review of preclinical research and future directions

The NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome is a key component of the innate immune system that triggers inflammation and pyroptosis and contributes to the development of several diseases. Therefore, blocking the activation of the NLRP3 inflammasome has therapeutic potential for the treatment of these diseases. MCC950, a selective small molecule inhibitor, has emerged as a promising candidate for blocking NLRP3 inflammasome activation. Ongoing research is focused on elucidating the specific targets of MCC950 as well as assessfing its metabolism and safety profile. This review discusses the diseases that have been studied in relation to MCC950, with a focus on stroke, Alzheimer's disease, liver injury, atherosclerosis, diabetes mellitus, and sepsis, using bibliometric analysis. It then summarizes the potential pharmacological targets of MCC950 and discusses its toxicity. Furthermore, it traces the progression from preclinical to clinical research for the treatment of these diseases. Overall, this review provides a solid foundation for the clinical therapeutic potential of MCC950 and offers insights for future research and therapeutic approaches.

Targeting the PINK1/Parkin Pathway: a new perspective in the prevention and therapy of diabetic retinopathy

Diabetic retinopathy (DR) is a microvascular complication of diabetes characterized by neurovascular impairment of the retina. The dysregulation of the mitophagy process occurs before apoptotic cell death and the appearance of vascular damage. In particular, mitochondrial alterations happen during DR development, supporting the hypothesis that mitophagy is negatively correlated to disease progression. This process is mainly regulated by the PTEN-induced putative kinase protein 1 (PINK1) /Parkin pathway whose activation promotes mitophagy. In this review, we will summarize the evidence reported in the literature demonstrating the involvement of the PINK1/Parkin pathway in diabetic retinopathy-induced retinal degeneration.

Pharmacological insights and role of bufalin (bufadienolides) in inflammation modulation: a narrative review

Bufadienolides, specifically bufalin, have garnered attention for their potential therapeutic application in modulating inflammatory pathways. Bufalin is derived from toad venom and exhibits promising anti-inflammatory properties. Its anti-inflammatory effects have been demonstrated by influencing crucial signaling pathways like NF-B, MAPK, and JAK-STAT, resulting in the inhibition of pro-inflammatory substances like cytokines, chemokines, and adhesion molecules. Bufalin blocks inflammasome activation and reduces oxidative stress, hence increasing its anti-inflammatory properties. Bufalin has shown effectiveness in reducing inflammation-related diseases such as cancer, cardiovascular problems, and autoimmune ailments in preclinical investigations. Furthermore, producing new approaches of medication delivery and combining therapies with bufalin shows potential for improving its effectiveness and reducing adverse effects. This review explores the pharmacological effects and mechanistic approaches of bufalin as an anti-inflammatory agent, which further highlights its potential for therapy and offers the basis for further study on its therapeutic application in inflammation-related disorders.

Nerolidol rescues hippocampal injury of diabetic rats through inhibiting NLRP3 inflammasome and regulation of MAPK/AKT pathway

Despite the observation of diabetes-induced brain tissue damage and impaired learning and memory, the underlying mechanism of damage remains elusive, and effective, targeted therapeutics are lacking. Notably, the NLRP3 inflammasome is highly expressed in the hippocampus of diabetic individuals. Nerolidol, a naturally occurring compound with anti-inflammatory and antioxidant properties, has been identified as a potential therapeutic option for metabolic disorders. However, the ameliorative capacity of nerolidol on diabetic hippocampal injury and its underlying mechanism remain unclear. Network pharmacology and molecular docking was used to predict the signaling pathways and therapeutic targets of nerolidol for the treatment of diabetes. Then established a diabetic rat model using streptozotocin (STZ) combined with a high-fat diet and nerolidol was administered. Morris water maze to assess spatial learning memory capacity. Hematoxylin and eosin and Nissl staining was used to detect neuronal damage in the diabetic hippocampus. Transmission electron microscopy was used to detect the extent of damage to mitochondria, endoplasmic reticulum (ER) and synapses. Immunofluorescence was used to detect GFAP, IBA1, and NLRP3 expression in the hippocampus. Western blot was used to detect apoptosis (Bcl-2, BAX, and Cleaved-Caspase-3); synapses (postsynaptic densifying protein 95, SYN1, and Synaptophysin); mitochondria (DRP1, OPA1, MFN1, and MFN2); ER (GRP78, ATF6, CHOP, and caspase-12); NLRP3 inflammasome (NLRP3, ASC, and caspase-1); inflammatory cytokines (IL-18, IL-1β, and TNF-α); AKT (P-AKT); and mitogen-activated protein kinase (MAPK) pathway (P-ERK, P-p38, and P-JNK) related protein expression. Network pharmacology showed that nerolidol's possible mechanisms for treating diabetes are the MAPK/AKT pathway and anti-inflammatory effects. Animal experiments demonstrated that nerolidol could improve blood glucose, blood lipids, and hippocampal neuronal damage in diabetic rats. Furthermore, nerolidol could improve synaptic, mitochondrial, and ER damage in the hippocampal ultrastructure of diabetic rats by potentially affecting synaptic, mitochondrial, and ER-related proteins. Further studies revealed that nerolidol decreased neuroinflammation, NLRP3 and inflammatory factor expression in hippocampal tissue while also decreasing MAPK pathway expression and enhancing AKT pathway expression. However, nerolidol improves hippocampal damage in diabetic rats cannot be shown to improve cognitive function. In conclusion, our study reveals for the first time that nerolidol can ameliorate hippocampal damage, neuroinflammation, synaptic, ER, and mitochondrial damage in diabetic rats. Furthermore, we suggest that nerolidol may inhibit NLRP3 inflammasome and affected the expression of MAPK and AKT. These findings provide a new experimental basis for the use of nerolidol to ameliorate diabetes-induced brain tissue damage and the associated disease.

Identification of PKM2 as a pyroptosis-related key gene aggravates senile osteoporosis via the NLRP3/Caspase-1/GSDMD signaling pathway

BACKGROUNDS

Senile osteoporosis-alternatively labeled as skeletal aging-encompasses age-induced bone deterioration and loss of bone microarchitecture. Recent studies have indicated a potential association between senile osteoporosis and chronic systemic inflammation, and pyroptosis in bone marrow-derived mesenchymal stem cells is speculated to contribute to bone loss and osteoporosis. Therefore, targeting pyroptosis in stem cells may be a potential therapeutic strategy for treating osteoporosis.

METHODS

Initially, we conducted bioinformatics analysis to screen the GEO databases to identify the key gene associated with pyroptosis in senile osteoporosis. Next, we analyzed the relationship between altered proteins and clinical data. In vitro experiments were then performed to explore whether the downregulation of PKM2 expression could inhibit pyroptosis. Additionally, an aging-related mouse model of osteoporosis was established to validate the efficacy of a PKM2 inhibitor in alleviating osteoporosis progression.

RESULTS

We identified PKM2 as a key gene implicated in pyroptosis in senile osteoporosis patients through bioinformatics analysis. Further analyses of bone marrow and stem cells demonstrated significant PKM2 overexpression in senile osteoporosis patients. Silencing PKM2 expression inhibited pyroptosis in senile stem cells, of which the osteogenesis potential and angiogenic function were also primarily promoted. Moreover, the results in vivo demonstrated that administering PKM2 inhibitors suppressed pyroptosis in senile osteoporosis mice and mitigated senile osteoporosis progression.

CONCLUSION

Our study uncovered PKM2, a key pyroptosis marker of bone marrow mesenchymal stem cells in senile osteoporosis. Shikonin, a PKM2 inhibitor, was then identified as a potential drug candidate for the treatment of osteoporosis.

Label-free analysis of the β-hydroxybutyricacid drug on mitochondrial redox states repairment in type 2 diabetic mice by resonance raman scattering

BACKGROUND

Mitochondrial redox imbalance underlies the pathophysiology of type2 diabetes mellitus (T2DM), and is closely related to tissue damage and dysfunction. Studies have shown the beneficial effects of dietary strategies that elevate β-hydroxybutyrate (BHB) levels in alleviating T2DM. Nevertheless, the role of BHB has not been clearly elucidated.

METHODS

We performed a spectral study to visualize the preventive effects of BHB on blood and multiorgan mitochondrial redox imbalance in T2DM mice via using label-free resonance Raman spectroscopy (RRS), and further explored the impact of BHB therapy on the pathology of T2DM mice by histological and biochemical analyses.

FINDINGS

Our data revealed that RRS-based mitochondrial redox states assay enabled clear and reliable identification of the improvement of mitochondrial redox imbalance by BHB, evidenced by the reduction of Raman peak intensity at 750 cm-1, 1128 cm-1 and 1585 cm-1 in blood, tissue as well as purified mitochondria of db/db mice and the increase of tissue mitochondrial succinic dehydrogenase (SDH) staining after BHB treatment. Exogenous supplementation of BHB was also found to attenuate T2DM pathology related to mitochondrial redox states, involving organ injury, blood glucose control, insulin resistance and systemic inflammation.

INTERPRETATION

Our findings provide strong evidence for BHB as a potential therapeutic strategy targeting mitochondria for T2DM.

Mitochondrial Mechanisms in Immunity and Inflammatory Conditions: Beyond Energy Management

Significance: The growing importance of mitochondria in the immune response and inflammation is multifaceted. Unraveling the different mechanisms by which mitochondria have a relevant role in the inflammatory response beyond the energy management of the process is necessary for improving our understanding of the host immune defense and the pathogenesis of various inflammatory diseases and syndromes. Critical Issues: Mitochondria are relevant in the immune response at different levels, including releasing activation molecules, changing its structure and function to accompany the immune response, and serving as a structural base for activating intermediates as NLRP3 inflammasome. In this scientific journey of dissecting mitochondrial mechanisms, new questions and interesting aspects arise, such as the involvement of mitochondrial-derived vesicles in the immune response with the putative role of preventing uncontrolled situations. Recent Advances: Researchers are continuously rethinking the role of mitochondria in acute and chronic inflammation and related disorders. As such, mitochondria have important roles as centrally positioned signaling hubs in regulating inflammatory and immune responses. In this review, we present the current understanding of mitochondrial mechanisms involved, beyond the largely known mitochondrial dysfunction, in the onset and development of inflammatory situations. Future Directions: Mitochondria emerge as an interesting and multifaceted platform for studying and developing pharmaceutical and therapeutic approaches. There are many ongoing studies aimed to describe the effects of specific mitochondrial targeted molecules and treatments to ameliorate the consequences of exacerbated inflammatory components of pathologies and syndromes, resulting in an open area of increasing research interest.

Semaglutide ameliorates cognition and glucose metabolism dysfunction in the 3xTg mouse model of Alzheimer's disease via the GLP-1R/SIRT1/GLUT4 pathway

Disorders of brain glucose metabolism is known to affect brain activity in neurodegenerative diseases including Alzheimer's disease (AD). Furthermore, recent evidence has shown an association between AD and type 2 diabetes. Numerous reports have found that glucagon-like peptide-1 (GLP-1) receptor agonists improve the cognitive behavior and pathological features in AD patients and animals, which may be related to the improvement of glucose metabolism in the brain. However, the mechanism by which GLP-1 agonists improve the brain glucose metabolism in AD patients remains unclear. In this study, we found that SIRT1 is closely related to expression of GLP-1R in hippocampus of 3xTg mice. Therefore, we used semaglutide, a novel GLP-1R agonist currently undergoing two phase 3 clinical trials in AD patients, to observe the effect of SIRT1 after semaglutide treatment in 3XTg mice and HT22 cells, and to explore the mechanism of SIRT1 in the glucose metabolism disorders of AD. The mice were injected with semaglutide on alternate days for 30 days, followed by behavioral experiments including open field test, new object recognition test, and Y-maze. The content of glucose in the brain was also measured by using 18FDG-PET-CT scans. We measured the expression of Aβ and tau in the hippocampus, observed the expression of GLUT4 which is downstream of SIRT1, and tested the Glucose oxidase assay (GOD-POD) and Hexokinase (HK) in HT22 cells. Here, we found in the 3xTg mouse model of AD and in cultured HT22 mouse neurons that SIRT1 signaling is involved in the impairment of glucose metabolism in AD. Semaglutide can increased the expression levels of SIRT1 and GLUT4 in the hippocampus of 3xTg mice, accompanied by an improvement in learning and memory, decreased in Aβ plaques and neurofibrillary tangles. In addition, we further demonstrated that semaglutide improved glucose metabolism in the brain of 3xTg mice in vitro, semaglutide promoted glycolysis and improved glycolytic disorders, and increased the membrane translocation of GLUT4 in cultured HT22 cells. These effects were blocked by the SIRT1 inhibitor (EX527). These findings indicate that semaglutide can regulate the expression of GLUT4 to mediate glucose transport through SIRT1, thereby improving glucose metabolism dysfunction in AD mice and cells. The present study suggests that SIRT1/GLUT4 signaling pathway may be an important mechanism for GLP-1R to promote glucose metabolism in the brain, providing a reliable strategy for effective therapy of AD.

Mechanisms of NLRP3 inflammasome activation and the development of peptide inhibitors

The Nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3), a member of the nucleotide-binding oligomerization domain (NOD) like receptors (NLRs) family, plays an important role in the innate immune response against pathogen invasions. NLRP3 inflammasome consisting of NLRP3 protein, the adapter protein apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD) (ASC), and the effector protein pro-caspase-1, is central to this process. Upon activation, NLRP3 inflammasome initiates the release of inflammatory cytokines and triggers a form of cell death known as pyroptosis. Dysregulation or inappropriate activation of NLRP3 has been implicated in various human diseases, including type 2 diabetes, colitis, depression, and gout. Consequently, understanding the mechanism underlying NLRP3 inflammasome activation is critical for the development of therapeutic drugs. In the pursuit of potential therapeutic agents, peptides present several advantages over small molecules. They offer higher selectivity, increased potency, reduced toxicity, and fewer off-target effects. The advancements in molecular biology have expanded the opportunities for applying peptides in medicine, unlocking their vast medical potential. This review begins by providing a comprehensive summary of recent research progress regarding the mechanisms governing NLRP3 inflammasome activation. Subsequently, we offer an overview of current peptide inhibitors capable of modulating the NLRP3 inflammasome activation pathway.

Targeting the NLRP3 inflammasome for the treatment of hypertensive target organ damage: Role of natural products and formulations

BACKGROUND AND AIM

Hypertension is a major global health problem that causes target organ damage (TOD) in the heart, brain, kidney, and blood vessels. The mechanisms of hypertensive TOD are not fully understood, and its treatment is challenging. This review provides an overview of the current knowledge on the role of Nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome in hypertensive TOD and the natural products and formulations that inhibit it.

METHODS

We searched PubMed, Web of Science, Google Scholar, and CNKI for relevant articles using the keywords "hypertension," "target organ damage," "NLRP3 inflammasome," "natural products," and "formulations." We reviewed the effects of the NLRP3 inflammasome on hypertensive TOD in different organs and discussed the natural products and formulations that modulate it.

KEY RESULTS

In hypertensive TOD, the NLRP3 inflammasome is activated by various stimuli such as oxidative stress and inflammation. Activation of NLRP3 inflammasome leads to the production of pro-inflammatory cytokines that exacerbate tissue damage and dysfunction. Natural products and formulations, including curcumin, resveratrol, triptolide, and allicin, have shown protective effects against hypertensive TOD by inhibiting the NLRP3 inflammasome.

CONCLUSIONS AND IMPLICATIONS

The NLRP3 inflammasome is a promising therapeutic target in hypertensive TOD. Natural products and formulations that inhibit the NLRP3 inflammasome may provide novel drug candidates or therapies for hypertensive TOD. Further studies are needed to elucidate the molecular mechanisms and optimize the dosages of these natural products and formulations and evaluate their clinical efficacy and safety.

Sirtuin4 alleviates severe acute pancreatitis by regulating HIF-1α/HO-1 mediated ferroptosis

Acute pancreatitis (AP) is a common emergency of the digestive system and serious cases can develop into severe acute pancreatitis (SAP), which ortality rates up to 30%. Sirtuin4 (SIRT4) is a member of the sirtuin family, and plays a key role in inflammation and oxidative stress. However, the potential role of SIRT4 in SAP has yet to be elucidated. In the present study, we found that the expression level of SIRT4 in human AP was downregulated by screening a public database, suggesting that SIRT4 may play a role in AP. Subsequently, we used L-arginine (L-Arg) to induce SAP in SIRT4 knockout (SIRT4_KO) and SIRT4 overexpression (AAV_SIRT4) mice. The results showed that the pancreatic tissue injury and related lung and kidney injury were serious in SIRT4_KO mice after SAP induction, but were significantly reduced in AAV_SIRT4 mice. More importantly, we found that the levels of antioxidant factors GSH and SOD were decreased in SIRT4_KO mice, and the production of oxidative products and lipid peroxidation markers was increased, suggesting that SIRT4 was involved in inflammation and oxidative stress during SAP. Further studies showed that the absence or overexpression of SIRT4 affected the expression level of Hypoxia-inducible factor-1α (HIF-1α) after SAP induction, and regulated the expression of ferroptosis related proteins by mediating HIF-1α/HO-1 pathway. Collectively, our study revealed that SIRT4 plays a protective role in SAP by regulating the HIF-1α/HO-1 pathway to inhibit ferroptosis.

Functionalized Metal-Organic Framework-Modified Hydrogel That Breaks the Vicious Cycle of Inflammation and ROS for Repairing of Diabetic Bone Defects

The regeneration of diabetic bone defects remains challenging. Hyperglycemia causes inflammation state and excessive reactive oxygen species (ROS) during bone regeneration period. These two effects reinforce one another and create an endless loop that is also accompanied by mitochondrial dysfunction. However, there is still no effective and inclusive method targeting at the two aspects and breaking the vicious cycle. Herein, nanoparticles-Met@ZIF-8(metformin loaded zeolitic imidazolate frameworks) modified hydrogel that is capable of releasing metformin and Zn elements are constructed. This hydrogel treats hyperglycemia while also controlling mitochondrial function, reducing inflammation, and restoring homeostasis. In addition, the synergetic effect from metformin and Zn ions inhibits ROS-inflammation cascade generation and destroys the continuous progress by taking effects in both ROS and inflammation and further keeping organelles' homeostasis. Furthermore, with the recovery of mitochondria and breakdown of the ROS-inflammation cascade cycle, osteogenesis under a diabetic microenvironment is enhanced in vivo and in vitro. In conclusion, the study provides critical insight into the biological mechanism and potential therapy for diabetic bone regeneration.

Study on the mechanism of NLRP3 effect on the skeleton of de-ovalized mice

Postmenopausal osteoporosis caused by estrogen deficiency affects millions of women worldwide. By influencing both osteoblast and osteoclast development, NOD-like receptor thermoprotein structural domain-associated protein 3 (NLRP3) is a key player in the etiology of osteoporosis (OP). The purpose of this research was to look into the mechanism of action of NLRP3 in osteoporosis caused by a lack of estrogen, highlighting that NLRP3 induces osteoblast pyroptosis and thus inflammatory responses in de-ovulated mice, thereby inhibiting osteogenic differentiation and participating in the development of osteoporosis. In de-ovulated mice, we found an enhanced inflammatory response and suppression of osteogenic activity. In vitro experiments, we found a significant increase in markers of cell pyroptosis and inflammatory responses and a significant decrease in markers of osteogenic differentiation in osteoblasts from de-ovulated mice. However, knockdown of the NLRP3 gene inhibited this cell pyroptosis and improved osteogenic differentiation of osteoblasts. Our findings indicate a potential therapeutic potential for the treatment of estrogen deficiency-induced osteoporosis by demonstrating the critical role that NLRP3 inflammatory vesicles and their downstream-mediated cellular pyroptosis play in bone differentiation.

The interplay between sexual abuse and inflammation, oxidative stress, and DNA damage in drug-naïve panic disorder patients

Although accumulating evidence suggests an interplay between child abuse and inflammatory processes and the pathophysiology of mental disorders, few studies have investigated the cellular mechanisms related to this matter. Furthermore, no studies to date have evaluated cytokine, oxidative stress, and DNA damage levels in drug-naïve panic disorder (PD) patients and their possible association with childhood trauma. The aim of the present study was to determine the levels of the proinflammatory interleukin (IL)-1B, the oxidative stress marker TBARS, and  8-hydroxy-2' -deoxyguanosine (8-OHdG; representing DNA damage) in drug-naïve PD patients compared to controls. Furthermore, this investigation aimed to determine whether early-life trauma could predict peripheral levels of the previously mentioned markers in unmedicated PD patients. This work showed that drug-naïve PD patients presented elevated levels of TBARS and IL-1B but not 8-OHdG compared to healthy controls. In addition, sexual abuse during childhood was associated with increased levels of IL-1B in PD patients. Our findings suggest that the microglial NLRP3 inflammasome complex might be activated in drug-naïve PD patients. This study is the first to associated sexual abuse with increased levels of IL-1B in drug-naïve PD patients and to demonstrate that this population presents high concentrations of oxidative stress and inflammation markers but not DNA damage markers when compared to healthy controls. Independent replication of these findings would support further clinical trials of inflammasome inhibitory drugs in PD patients, which could lead to effective novel treatments for people with PD and contribute to elucidating pathophysiological differences depending on trauma exposure in the immune disturbances accompanying PD.

Insights into the Role of Plasmatic and Exosomal microRNAs in Oxidative Stress-Related Metabolic Diseases

A common denominator of metabolic diseases, including type 2 diabetes Mellitus, dyslipidemia, and atherosclerosis, are elevated oxidative stress and chronic inflammation. These complex, multi-factorial diseases are caused by the detrimental interaction between the individual genetic background and multiple environmental stimuli. The cells, including the endothelial ones, acquire a preactivated phenotype and metabolic memory, exhibiting increased oxidative stress, inflammatory gene expression, endothelial vascular activation, and prothrombotic events, leading to vascular complications. There are different pathways involved in the pathogenesis of metabolic diseases, and increased knowledge suggests a role of the activation of the NF-kB pathway and NLRP3 inflammasome as key mediators of metabolic inflammation. Epigenetic-wide associated studies provide new insight into the role of microRNAs in the phenomenon of metabolic memory and the development consequences of vessel damage. In this review, we will focus on the microRNAs related to the control of anti-oxidative enzymes, as well as microRNAs related to the control of mitochondrial functions and inflammation. The objective is the search for new therapeutic targets to improve the functioning of mitochondria and reduce oxidative stress and inflammation, despite the acquired metabolic memory.

Cardiovascular disease treatment using traditional Chinese medicine：Mitochondria as the Achilles' heel

Cardiovascular disease (CVD), involving the pathological alteration of the heart or blood vessels, is one of the main causes of disability and death worldwide, with an estimated 18.6 million deaths per year. CVDs are caused by a variety of risk factors, including inflammation, hyperglycemia, hyperlipidemia, and increased oxidative stress. Mitochondria, the hub of ATP production and the main generator of reactive oxygen species (ROS), are linked to multiple cellular signaling pathways that regulate the progression of CVD and therefore are recognized as an essential target for CVD management. Initial treatment of CVD generally focuses on diet and lifestyle interventions; proper drugs or surgery can prolong or save the patient's life. Traditional Chinese medicine (TCM), a holistic medical care system with an over 2500-year history, has been proven to be efficient in curing CVD and other illnesses, with a strengthening effect on the body. However, the mechanisms underlying TCM alleviation of CVD remain elusive. Recent studies have recognized that TCM can alleviate cardiovascular disease by manipulating the quality and function of mitochondria. This review systematically summarizes the association of mitochondria with cardiovascular risk factors, and the relationships between mitochondrial dysfunction and CVD progression. We will investigate the research progress of managing cardiovascular disease by TCM and cover widely used TCMs that target mitochondria for the treatment of cardiovascular disease.

From Diabetes to Diabetic Complications: Role of Autophagy

Diabetes and its complications reduce quality of life and are life-limiting. At present, diabetes treatment consists of hypoglycemic agents to control blood glucose and the use of insulin-sensitizing drugs to overcome insulin resistance. In diabetes, autophagy is impaired and thus there is poor intracellular environment homeostasis. Pancreatic β-cells and insulin target tissues are protected by enhancing autophagy. Autophagy decreases β-cell apoptosis, promotes β-cell proliferation, and alleviates insulin resistance. Autophagy in diabetes is regulated by the mammalian target of rapamycin (mTOR)/adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway and others. Autophagy enhancers can likely be used as a treatment for diabetes and its complications. This review examines the evidence linking autophagy to diabetes.

Transgenic type2 diabetes mouse models for in vivo redox measurement of hepatic mitochondrial oxidative stress

BACKGROUND

Oxidative stress is involved in the progression of diabetes and its associated complications. However, it is unclear whether increased oxidative stress plays a primary role in the onset of diabetes or is a secondary indicator caused by tissue damage. Previous methods of analyzing oxidative stress have involved measuring the changes in oxidative stress biomarkers. Our aim is to identify a novel approach to clarify whether oxidative stress plays a primary role in the onset of diabetes.

METHODS

We constructed transgenic type 2 diabetes mouse models expressing redox-sensitive green fluorescent proteins (roGFPs) that distinguished between mitochondria and whole cells. Pancreas, liver, skeletal muscle, and kidney redox states were measured in vivo.

RESULTS

Hepatic mitochondrial oxidation increased when the mice were 4 weeks old and continued to increase in an age-dependent manner. The increase in hepatic mitochondrial oxidation occurred simultaneously with weight gain and increased blood insulin levels before the blood glucose levels increased. Administering the oxidative stress inducer acetaminophen increased the vulnerability of the liver mitochondria to oxidative stress.

CONCLUSIONS

This study demonstrates that oxidative stress in liver mitochondria in mice begins at the onset of diabetes rather than after the disease has progressed.

GENERAL SIGNIFICANCE

RoGFP-expressing transgenic type 2 diabetes mouse models are effective and convenient tools for measuring hepatic mitochondrial redox statuses in vivo. These models may be used to assess mitochondria-targeting antioxidants and establish the role of oxidative stress in type 2 diabetes.

Recent Pharmacological Options in Type 2 Diabetes and Synergic Mechanism in Cardiovascular Disease

Diabetes Mellitus is a multifactorial disease with a critical impact worldwide. During prediabetes, the presence of various inflammatory cytokines and oxidative stress will lead to the pathogenesis of type 2 diabetes. Furthermore, insulin resistance and chronic hyperglycemia will lead to micro- and macrovascular complications (cardiovascular disease, heart failure, hypertension, chronic kidney disease, and atherosclerosis). The development through the years of pharmacological options allowed us to reduce the persistence of chronic hyperglycemia and reduce diabetic complications. This review aims to highlight the specific mechanisms with which the new treatments for type 2 diabetes reduce oxidative stress and insulin resistance and improve cardiovascular outcomes.

Increased mitochondrial proton leak and glycolysis in peripheral blood mononuclear cells in type-1-diabetes

Changes in cellular bioenergetics such as mitochondrial respiration and glycolysis may play a role in the pathogenesis of various diseases including type 1 diabetes (T1D). We used Seahorse extracellular flux technology to analyse the efficiency of glycolysis and mitochondrial oxidative phosphorylation in peripheral blood mononuclear cells (PBMCs) obtained from fresh blood samples from fifteen long-term T1D individuals with albuminuria (five females) with an average (±SD) age of 58 (±14) years and 15 age and sex-matched healthy non-diabetic controls. In T1D PBMCs, mitochondrial proton leak was higher (T1D: 21,3 ± 1,46 pmol/min; controls: 17,3 ± 1,24 pmol/min; p = 0,049) and glucose (5 mM) suppressed mitochondrial proton leak more than in healthy controls. Further, PBMCs from T1D individuals had higher glycolysis compared with healthy controls (T1D: 9,68 ± 0,94 mpH/min; controls: 7,07 ± 0,64 mpH/min; p = 0,032). Correlation analysis of circulating inflammatory factors identified Leukaemia Inhibitor factor 1 (LIF) being negatively correlated with PBMC glycolysis. Our results suggest that mitochondrial and glycolytic pathways of PBMCs from long-term T1D individuals with albuminuria might be dysfunctional, possibly due to increased cellular metabolic load and/or oxidative stress in which inflammatory factors could play a role.

Association between Parkinson's Disease and Diabetes Mellitus: From Epidemiology, Pathophysiology and Prevention to Treatment

Diabetes mellitus (DM) and Parkinson's disease (PD) are both age-related diseases of global concern being among the most common chronic metabolic and neurodegenerative diseases, respectively. While both diseases can be genetically inherited, environmental factors play a vital role in their pathogenesis. Moreover, DM and PD have common underlying molecular mechanisms, such as misfolded protein aggregation, mitochondrial dysfunction, oxidative stress, chronic inflammation, and microbial dysbiosis. Recently, epidemiological and experimental studies have reported that DM affects the incidence and progression of PD. Moreover, certain antidiabetic drugs have been proven to decrease the risk of PD and delay its progression. In this review, we elucidate the epidemiological and pathophysiological association between DM and PD and summarize the antidiabetic drugs used in animal models and clinical trials of PD, which may provide reference for the clinical translation of antidiabetic drugs in PD treatment.

The BCL2/BAX/ROS pathway is involved in the inhibitory effect of astragaloside IV on pyroptosis in human umbilical vein endothelial cells

CONTEXT

Astragaloside IV (AS-IV) is extracted from Astragalus membranaceus (Fisch.) Bunge (Fabaceae). However, its effects on endothelial cell injury remain unclear.

OBJECTIVE

To investigate the mechanisms underlying the effects of AS-IV on lipopolysaccharide (LPS)-induced endothelial injury in vitro.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were pre-treated with AS-IV (100 µmol/mL), 4-hydroxy-3-methoxyacetophenone (APO, 10 µmol/mL), N-acetylcysteine (NAC, 50 µmol/mL) and Ac-YVAD-cmk (AC, 5 µmol/mL) for 2 h before 1 μg/mL LPS 24 h exposure. Untreated cells cultured without any exposure were used as controls. Cell viability, reactive oxygen species (ROS) and pyroptosis assays were performed. The pyroptosis related proteins were detected by western blot.

RESULTS

The rate in late pyroptosis (Q2-2) of AS-IV (13.65 ± 0.74%), APO (13.69 ± 0.67%) and NAC (15.87 ± 0.46%) groups was lower than the LPS group (21.89 ± 0.66%, p < 0.05), while the rate in early pyroptosis (Q2-4) of AS-IV group (12.00 ± 0.26%) was lower than other groups (p < 0.05). The expression of NOX4, GSDMD, NLRP3, ASC and caspase-1 decreased after AS-IV, NAC or AC intervention (p < 0.05). The ROS production in AS-IV (4664 ± 153.20), APO (4094 ± 78.37), NAC (5103 ± 131.10) and AC (3994 ± 102.50) groups was lower than the LPS (5986 ± 127.30) group, while the mitochondrial BCL2/BAX protein expression ratio increased in AS-IV, APO and NAC groups (p < 0.05).

DISCUSSION AND CONCLUSIONS

AS-IV suppressed pyroptosis in LPS-activated HUVECs by inducing ROS/NLRP3-mediated inhibition of the inflammatory response, providing a scientific basis for clinical applications of AS-IV.

ROS-triggered endothelial cell death mechanisms: Focus on pyroptosis, parthanatos, and ferroptosis

The endothelium is a single layer of epithelium covering the surface of the vascular system, and it represents a physical barrier between the blood and vessel wall that plays an important role in maintaining intravascular homeostasis. However, endothelial dysfunction or endothelial cell death can cause vascular barrier disruption, vasoconstriction and diastolic dysfunction, vascular smooth muscle cell proliferation and migration, inflammatory responses, and thrombosis, which are closely associated with the progression of several diseases, such as atherosclerosis, hypertension, coronary atherosclerotic heart disease, ischemic stroke, acute lung injury, acute kidney injury, diabetic retinopathy, and Alzheimer's disease. Oxidative stress caused by the overproduction of reactive oxygen species (ROS) is an important mechanism underlying endothelial cell death. Growing evidence suggests that ROS can trigger endothelial cell death in various ways, including pyroptosis, parthanatos, and ferroptosis. Therefore, this review will systematically illustrate the source of ROS in endothelial cells (ECs); reveal the molecular mechanism by which ROS trigger pyroptosis, parthanatos, and ferroptosis in ECs; and provide new ideas for the research and treatment of endothelial dysfunction-related diseases.

Mitochondrial transplantation: opportunities and challenges in the treatment of obesity, diabetes, and nonalcoholic fatty liver disease

Metabolic diseases, including obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD), are rising in both incidence and prevalence and remain a major global health and socioeconomic burden in the twenty-first century. Despite an increasing understanding of these diseases, the lack of effective treatments remains an ongoing challenge. Mitochondria are key players in intracellular energy production, calcium homeostasis, signaling, and apoptosis. Emerging evidence shows that mitochondrial dysfunction participates in the pathogeneses of metabolic diseases. Exogenous supplementation with healthy mitochondria is emerging as a promising therapeutic approach to treating these diseases. This article reviews recent advances in the use of mitochondrial transplantation therapy (MRT) in such treatment.

The effect of tai chi intervention on NLRP3 and its related antiviral inflammatory factors in the serum of patients with pre-diabetes

Background

NLRP3 inflammasome and its related antiviral inflammatory factors have been implicated in the pathogenesis of type 2 diabetes mellitus (T2DM) and insulin resistance, but its contribution to pre-diabetes remains poorly understood.

Objective

To investigate the effects and the potential mechanism of Tai Chi intervention on NLRP3 inflammasome and its related inflammatory factors in the serum of middle-aged and older people with pre-diabetes mellitus (PDM).

Methods

40 pre-diabetic subjects were divided into a pre-diabetic control group (PDM-C group, N=20) and a Tai Chi group (PDM-TC group, N=20) by random number table. 10 normoglycemic subjects (NG) were selected as controls. We measured clinical metabolic parameters and collected blood samples before and after the 12 weeks of Tai Chi intervention. Antiviral inflammatory factors in serum were detected by enzyme-linked immunosorbent assay.

Results

The blood glucose, insulin resistance, and inflammation in PDM groups were higher than those in the NG group (P<0.05 and P<0.01, respectively). The results also suggested that 12 weeks of Tai Chi intervention could reduce body weight, blood pressure, blood glucose, insulin resistance, blood lipid, and the expressions of serum inflammatory factors in the pre-diabetic population.

Conclusion

Tai Chi intervention may improve blood glucose, lipid levels, and insulin resistance in middle-aged and elderly pre-diabetic patients by reducing the level of NLRP3 inflammasome and its related inflammatory factors.

Aerobic exercise alleviates pyroptosis-related diseases by regulating NLRP3 inflammasome

Pyroptosis plays a crucial role in a variety of human diseases, including atherosclerosis, obesity, diabetes, depression, and Alzheimer’s disease, which usually release pyroptosis-related cytokines due to inflammation. Many studies have demonstrated that aerobic exercise is a good option for decreasing the release of pyroptosis-related cytokines. However, the molecular mechanisms of aerobic exercise on pyroptosis-related diseases remain unknown. In this review, the effects of aerobic exercise on pyroptosis in endothelial cells, adipocytes and hippocampal cells, and their potential mechanisms are summarized. In endothelial cells, aerobic exercise could inhibit NOD-like receptor protein 3 (NLRP3) inflammasome-mediated pyroptosis by improving the endothelial function, while reducing vascular inflammation and oxidative stress. In adipocytes, aerobic exercise has been shown to inhibit pyroptosis by ameliorating inflammation and insulin resistance. Moreover, aerobic exercise could restrict pyroptosis by attenuating microglial activation, neuroinflammation, and amyloid-beta deposition in hippocampal cells. In summary, aerobic exercise alleviates the pyroptosis-related diseases by regulating the NLRP3 inflammation si0067naling.

Role of c-miR-21, c-miR-126, Redox Status, and Inflammatory Conditions as Potential Predictors of Vascular Damage in T2DM Patients

The development of type 2 diabetes mellitus (T2DM) vascular complications (VCs) is associated with oxidative stress and chronic inflammation and can result in endothelial dysfunctions. Circulating microRNAs play an important role in epigenetic regulation of the etiology of T2DM. We studied 30 healthy volunteers, 26 T2DM patients with no complications, and 26 T2DM patients with VCs, to look for new biomarkers indicating a risk of developing VCs in T2DM patients. Peripheral blood samples were used to determine redox state, by measuring the endogenous antioxidant defense system (superoxide dismutase, SOD; catalase, CAT; glutathione reductase, GRd; glutathione peroxidase, GPx; and glucose-6-phosphate dehydrogenase, G6DP) and markers of oxidative damage (advanced oxidation protein products, AOPP; lipid peroxidation, LPO). Additionally, inflammatory marker levels (IL-1, IL-6, IL-18, and TNF-α), c-miR-21, and c-miR-126 expression were analyzed. T2DM patients showed the highest oxidative damage with increased GSSG/GSH ratios, LPO, and AOPP levels. In both diabetic groups, we found that diminished SOD activity was accompanied by increased CAT and decreased GRd and G6PD activities. Diabetic patients presented with increased relative expression of c-miR-21 and decreased relative expression of c-miR-126. Overall, c-miR-21, SOD, CAT, and IL-6 had high predictive values for diabetes diagnoses. Finally, our data demonstrated that IL-6 exhibited predictive value for VC development in the studied population. Moreover, c-miR-21 and c-miR-126, along with GPx and AOPP levels, should be considered possible markers for VC development in future studies.

Pathophysiological Role of Nucleic Acid-Sensing Pattern Recognition Receptors in Inflammatory Diseases

Pattern recognition receptors (PRRs) play critical roles in recognizing pathogen-derived nucleic acids and inducing innate immune responses, such as inflammation and type I interferon production. PRRs that recognize nucleic acids include members of endosomal Toll-like receptors, cytosolic retinoic acid inducible gene I-like receptors, cyclic GMP–AMP synthase, absent in melanoma 2-like receptors, and nucleotide binding oligomerization domain-like receptors. Aberrant recognition of self-derived nucleic acids by these PRRs or unexpected activation of downstream signaling pathways results in the constitutive production of type I interferons and inflammatory cytokines, which lead to the development of autoimmune or autoinflammatory diseases. In this review, we focus on the nucleic acid-sensing machinery and its pathophysiological roles in various inflammatory diseases.

Kindlin-2 protects pancreatic β cells through inhibiting NLRP3 inflammasome activation in diabetic mice

Diabetes mellitus has been a major public health problem worldwide, characterized by insulin resistance and dysfunction of β-cells. A previous study showed that Kindlin-2 loss in β-cells dramatically reduces insulin secretion and decreases β-cell mass, resulting in severe diabetes-like phenotypes. It suggests that Kindlin-2 in β-cells play an important role in regulating glucose homeostasis. However, the effect of Kindlin-2 on the function of β-cells under chronic hyperglycemia in diabetes has not been explored. Here we report that Kindlin-2 overexpression ameliorates diabetes and improves insulin secretion in mice induced by streptozocin. In contrast, Kindlin-2 insufficiency exacerbates diabetes and promotes β-cells dysfunction and inflammation in β-cells induced by a high-fat diet (HFD). In vitro, Kindlin-2 overexpression prevented high-glucose (HG)-induced dysfunction in β-cells. Kindlin-2 overexpression also decreased the expression of pro-inflammatory cytokines and NLRP3 inflammasome expression in β-cells exposed to HG. Furthermore, the loss of Kindlin-2 aggravates the expression of inflammatory cytokines and NLRP3 induced by HG in β-cells. Collectively, we demonstrate that Kindlin-2 protects against diabetes by inhibiting NLRP3 inflammasome activation.

NLRP3 inflammasome links vascular senescence to diabetic vascular lesions

Vascular senescence is inextricably linked to the onset and progression of cardiovascular diseases (CVDs), which are the main cause of mortality in people with Type 2 diabetes (T2DM). Previous studies have emphasized the importance of chronic aseptic inflammation in diabetic vasculopathy. Here, we found the abnormal activation of NLRP3 inflammasome in the aorta of both old and T2DM mice by immunofluorescence and Western Blot analysis. Histopathological and isometry tension analysis showed that the presence of T2DM triggered or aggravated the increase of vascular aging markers, as well as age-associated vascular impairment and vasomotor dysfunction, which were improved by NLRP3 deletion or inhibition. Differential expression of aortic genes links to senescence activation and vascular remodeling supports the favorable benefits of NLRP3^-/- during T2DM. In vitro results based on primary mice aortic endothelial cells (MAECs) and vascular smooth muscle cells (VSMCs) demonstrate that NLRP3 deficiency attenuated premature senescence and restored proliferation and migration capability under-stimulation, and partially ameliorated replicative senescence. These results provide an insight into the critical role of NLRP3 signaling in T2DM-induced vascular aging and loss of vascular homeostasis, and provide the possibility that targeting NLRP3 inflammasome might be a promising strategy to prevent diabetic vascular senescence and associated vascular lesions.

Adipose-derived stem cells alleviate liver injury induced by type 1 diabetes mellitus by inhibiting mitochondrial stress and attenuating inflammation

Background

Type 1 diabetes mellitus (T1D) is a worldwide health priority due to autoimmune destruction and is associated with an increased risk of multiorgan complications. Among these complications, effective interventions for liver injury, which can progress to liver fibrosis and hepatocellular carcinoma, are lacking. Although stem cell injection has a therapeutic effect on T1D, whether it can cure liver injury and the underlying mechanisms need further investigation.

Methods

Sprague–Dawley rats with streptozotocin (STZ)-induced T1D were treated with adipose-derived stem cell (ADSC) or PBS via the tail vein formed the ADSC group or STZ group. Body weights and blood glucose levels were examined weekly for 6 weeks. RNA-seq and PCR array were used to detect the difference in gene expression of the livers between groups.

Results

In this study, we found that ADSCs injection alleviated hepatic oxidative stress and injury and improved liver function in rats with T1D; potential mechanisms included cytokine activity, energy metabolism and immune regulation were potentially involved, as determined by RNA-seq. Moreover, ADSC treatment altered the fibroblast growth factor 21 (FGF21) and transforming growth factor β (TGF-β) levels in T1D rat livers, implying its repair capacity. Disordered intracellular energy metabolism, which is closely related to mitochondrial stress and dysfunction, was inhibited by ADSC treatment. PCR array and ingenuity pathway analyses suggested that the ADSC-induced suppression of mitochondrial stress is related to decreased necroptosis and apoptosis. Moreover, mitochondria-related alterations caused liver inflammation, resulting in liver injury involving the T lymphocyte-mediated immune response.

Conclusions

Overall, these results improve our understanding of the curative effect of ADSCs on T1D complications: ADSCs attenuate liver injury by inhibiting mitochondrial stress (apoptosis and dysfunctional energy metabolism) and alleviating inflammation (inflammasome expression and immune disorder). These results are important for early intervention in liver injury and for delaying the development of liver lesions in patients with T1D.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02760-z.

Penehyclidine hydrochloride suppresses inflammation response and reduces podocyte injury in diabetic nephropathy by targeting fibrinogen-like protein 2

BACKGROUND

Diabetic nephropathy (DN) is one of the main complications of diabetes. Penehyclidine hydrochloride (PHC) has anti-inflammatory, anti-apoptotic and anti-oxidative stress effects. Nevertheless, whether PHC can be used to prevent podocyte injury has not been reported.

OBJECTIVES

This present study aimed to identify the functional role of PHC in DN as well as its underlying mechanism.

METHODS

The high-glucose (HG)-induced podocyte damage in vitro model was established. The proliferation, apoptotic rate, inflammatory factors, and gene/protein expressions of HG-induced MPC5 cells were determined using CCK-8 assay, flow cytometry, ELISA, real-time PCR, and Western blot upon PHC treatment. Co-immunoprecipitation experiments and pull-down assay were performed to verify the interactions between fibrinogen-like protein 2 (Fgl2) and toll-like receptor 4 (TLR4) as well as TLR4 and NLRP3. A rat in vivo model was used to confirm the effect of PHC treatment.

RESULTS

PHC treatment reduced Fgl2 expression and inhibited HG-induced podocyte injury and DN-induced kidney damage. Flg2 was associated with TLR4 and NLRP3. It was further proved that PHC treatment suppressed the TLR4-NF-кB and NLRP3-Caspase-1 pathways through Fgl2, which eventually inhibited inflammatory cytokines and prevented HG-induced podocyte injury both in vitro and in vivo.

CONCLUSION

PHC treatment possibly ameliorates DN by preventing podocyte injury via inactivating the TLR4-NF-кB and NLRP3-Caspase-1 signaling pathways by Flg2.

NLRP3 Inflammasome in Vascular Disease: A Recurrent Villain to Combat Pharmacologically

Despite the great advances in medicine, mortality from cardiovascular diseases keeps on growing. This tendency is not likely to change considering the pandemic proportions of obesity and diabetes. Besides, the global population is more aged as life expectancy increases, and vascular aging plays a key role in the increased risk of vascular disease. In light of recent trials, namely the CANTOS study, showing the enormous potential of anti-inflammatory therapies and in particular those targeted to IL-1β, a change in therapeutical management of cardiovascular diseases is coming about. The NLRP3 inflammasome is a multiprotein complex that assembles to engage the innate immune defense by processing the maturation of pro-inflammatory cytokines IL-1β and IL-18. Substantial evidence has positioned the NLRP3 inflammasome at the center of vascular disease progression, with a particular significance in the context of aging and the low-grade chronic inflammation associated (inflammaging). Therefore, pharmacological blockade of the NLRP3 inflammasome and its end products has arisen as an extremely promising tool to battle vascular disease. In this review, we discuss the mechanisms by which the NLRP3 inflammasome contributes to vascular disease, with particular attention to the consequences of aging, and we enumerate the therapeutic options available to combat this recurrent villain.

A novel mechanism for NLRP3 inflammasome activation

The NLRP3 inflammasome, as an important component of the innate immune system, plays vital roles in various metabolic disorders. It has been reported that the NLRP3 inflammasome can be activated by a broad range of distinct stimuli, such as K⁺ efflux, mitochondrial dysfunction, lysosomal disruption and trans-Golgi disassembly, etc. However, there has been no well-established model for NLRP3 inflammasome activation so far, especially the underlying mechanisms for mitochondria in NLRP3 inflammasome activation remain elusive. Given that K⁺ efflux is a widely accepted nexus for triggering activation of NLRP3 inflammasome in most previous studies, we sought to elucidate the role of mitochondria in K⁺ efflux-induced NLRP3 inflammasome activation. Here, we demonstrated that inflammation activation by LPS evoked the expression of genes that involved in mitochondrial biogenesis and mitophagy, subsequently mitochondrial mass and mitochondrial membrane potential were also elevated, suggesting the contribution of mitochondria in inflammatory responses. Moreover, we inhibited mitochondrial biogenesis by silencing Tfam and genetic ablation of Tfam abolished the NLRP3 inflammasome activation induced by K⁺ efflux via release of mitochondrial DNA (mtDNA), as deprivation of cellular mtDNA by EtBr treatment could reverse inflammasome activation induced by K⁺ efflux. Collectively, we reveal that mtDNA release induced by K⁺ efflux in macrophages activates NLRP3 inflammasome, and propose that mitochondria may serve as a potential therapeutic target for NLRP3 inflammasome-related diseases.

FMDV Leader Protein Interacts with the NACHT and LRR Domains of NLRP3 to Promote IL-1β Production

Foot-and-mouth disease virus (FMDV) infection causes inflammatory clinical symptoms, such as high fever and vesicular lesions, even death of animals. Interleukin-1β (IL-1β) is an inflammatory cytokine that plays an essential role in inflammatory responses against viral infection. The viruses have developed multiple strategies to induce the inflammatory responses, including regulation of IL-1β production. However, the molecular mechanism underlying the induction of IL-1β by FMDV remains not fully understood. Here, we found that FMDV robustly induced IL-1β production in macrophages and pigs. Infection of Casp-1 inhibitor-treated cells and NOD-, LRR- and pyrin domain-containing 3 (NLRP3)-knockdown cells indicated that NLRP3 is essential for FMDV-induced IL-1β secretion. More importantly, we found that FMDV Lpro associates with the NACHT and LRR domains of NLRP3 to promote NLRP3 inflammasome assembly and IL-1β secretion. Moreover, FMDV Lpro induces calcium influx and potassium efflux, which trigger NLRP3 activation. Our data revealed the mechanism underlying the activation of the NLRP3 inflammasome after FMDV Lpro expression, thus providing insights for the control of FMDV infection-induced inflammation.

Ethyl 2-Succinate-Anthraquinone Attenuates Inflammatory Response and Oxidative Stress via Regulating NLRP3 Signaling Pathway

Aloe-emodin widely possesses antibacterial, anti-inflammatory, antioxidant, antiviral, and anti-infectious properties. This study investigated the effect of ethyl 2-succinate-anthraquinone (Luhui derivative, LHD) on inflammation. In vitro, a THP-1 macrophage inflammation model, made by 100 ng/ml phorbol-12-myristate-13-acetate (PMA) and 1 μg/ml LPS for 24 h, was constructed. The LHD group (6.25 μmol/L, 12.5 μmol/L, 25 μmol/L, 50 μmol/L) had no effect on THP-1 cell activity, and the expression of IL-6 mRNA was down-regulated in a concentration-dependent manner, of which the 25 μmol/L group had the best inhibitory effect. The migration of THP-1 macrophages induced by LPS was decreased by the LHD. Moreover, the LHD suppressed ROS fluorescence expression by inhibiting MDA expression and increasing SOD activity. In vivo, we revealed that the LHD, in different doses (6.25 mg/kg, 12.5 mg/kg, 25 mg/kg, 50 mg/kg), has a protective effect on stress physiological responses by assessing the body temperature of mice. Interestingly, acute lung injury (e.g., the structure of the alveoli disappeared and capillaries in the alveolar wall were dilated and congested) and liver damage (e.g., hepatocyte swelling, neutrophil infiltration, and hepatocyte apoptosis) were obviously improved at the same condition. Furthermore, we initially confirmed that the LHD can down-regulate the expression of NLRP3, IL-1β, and caspase-1 proteins, thereby mediating the NLRP3 inflammasome signaling pathway to produce anti-inflammatory effects. In conclusion, our results indicate that the LHD exerts anti-inflammatory activity via regulating the NLRP3 signaling pathway, inhibition of oxidative stress, and THP-1 macrophage migration.

Research Progress of Mitochondrial Mechanism in NLRP3 Inflammasome Activation and Exercise Regulation of NLRP3 Inflammasome

NLRP3 is an important pattern recognition receptor in the innate immune system, and its activation induces a large number of pro-inflammatory cytokines, IL-1β and IL-18 which are involved in the development of various diseases. In recent years, it has been suggested that mitochondria are the platform for NLRP3 inflammasome activation. Additionally, exercise is considered as an important intervention strategy to mediate the innate immune responses. Generally, chronic moderate-intensity endurance training, resistance training and high-intensity interval training inhibit NLRP3 inflammasome activation in response to various pathological factors. In contrast, acute exercise activates NLRP3 inflammasome. However, the mechanisms by which exercise regulates NLRP3 inflammasome activation are largely unclear. Therefore, the mechanism of NLRP3 inflammasome activation is discussed mainly from the perspective of mitochondria in this review. Moreover, the effect and potential mechanism of exercise on NLRP3 inflammasome are explored, hoping to provide new target for relevant research.

Paeonol for the Treatment of Atherosclerotic Cardiovascular Disease: A Pharmacological and Mechanistic Overview

With improvement in living standards and average life expectancy, atherosclerotic cardiovascular disease incidences and mortality have been increasing annually. Paeonia suffruticosa, a natural herb, has been used for the treatment of atherosclerotic cardiovascular disease for thousands of years in Eastern countries. Paeonol is an active ingredient extracted from Paeonia suffruticosa. Previous studies have extensively explored the clinical benefits of paeonol. However, comprehensive reviews on the cardiovascular protective effects of paeonol have not been conducted. The current review summarizes studies reporting on the protective effects of paeonol on the cardiovascular system. This study includes studies published in the last 10 years. The biological characteristics of Paeonia suffruticosa, pharmacological mechanisms of paeonol, and its toxicological and pharmacokinetic characteristics were explored. The findings of this study show that paeonol confers protection against atherosclerotic cardiovascular disease through various mechanisms, including inflammation, platelet aggregation, lipid metabolism, mitochondria damage, endoplasmic reticulum stress, autophagy, and non-coding RNA. Further studies should be conducted to elucidate the cardiovascular benefits of paeonol.

Molecular Hydrogen as a Novel Protective Agent against Pre-Symptomatic Diseases

Mibyou, or pre-symptomatic diseases, refers to state of health in which a disease is slowly developing within the body yet the symptoms are not apparent. Common examples of mibyou in modern medicine include inflammatory diseases that are caused by chronic inflammation. It is known that chronic inflammation is triggered by the uncontrolled release of proinflammatory cytokines by neutrophils and macrophages in the innate immune system. In a recent study, it was shown that molecular hydrogen (H2) has the ability to treat chronic inflammation by eliminating hydroxyl radicals (·OH), a mitochondrial reactive oxygen species (ROS). In doing so, H2 suppresses oxidative stress, which is implicated in several mechanisms at the root of chronic inflammation, including the activation of NLRP3 inflammasomes. This review explains these mechanisms by which H2 can suppress chronic inflammation and studies its applications as a protective agent against different inflammatory diseases in their pre-symptomatic state. While mibyou cannot be detected nor treated by modern medicine, H2 is able to suppress the pathogenesis of pre-symptomatic diseases, and thus exhibits prospects as a novel protective agent.

The Application of Functional Magnetic Resonance Imaging in Type 2 Diabetes Rats With Contrast-Induced Acute Kidney Injury and the Associated Innate Immune Response

AIMS

Contrast-induced acute kidney injury (CI-AKI) is the third most common in-hospital acquired AKI, and its mechanism is not fully clear. Its morbidity increases among populations with chronic kidney disease (CKD), older age, diabetes mellitus (DM), and so on. Immediate and effective noninvasive diagnostic methods are lacking, so CI-AKI often prolongs hospital stays and increases extra medical costs. This study aims to explore the possibility of diagnosing CI-AKI with functional magnetic resonance imaging (fMRI) based on type 2 DM rats. Moreover, we attempt to reveal the immune response in CI-AKI and to clarify why DM is a predisposing factor for CI-AKI.

METHODS

A type 2 DM rat model was established by feeding a high-fat and high-sugar diet combined with streptozotocin (STZ) injection. Iodixanol-320 was the contrast medium (CM) administered to rats. Images were obtained with a SIEMENS Skyra 3.0-T magnetic resonance imager. Renal histopathology was evaluated using H&E staining and immunohistochemistry (IHC). The innate immune response was revealed through western blotting and flow cytometry.

RESULTS

Blood oxygenation level-dependent (BOLD) imaging and intravoxel incoherent motion (IVIM) imaging can be used to predict and diagnose CI-AKI effectively. The R 2 ∗ value (r > 0.6, P < 0.0001) and D value (| r| > 0.5, P < 0.0001) are strongly correlated with histopathological scores. The NOD-like receptor pyrin 3 (NLRP3) inflammasome participates in CI-AKI and exacerbates CI-AKI in DM rats. Moreover, the percentages of neutrophils and M1 macrophages increase dramatically in rat kidneys after CM injection (neutrophils range from 56.3 to 56.6% and M1 macrophages from 48 to 54.1% in normal rats, whereas neutrophils range from 85.5 to 92.4% and M1 macrophages from 82.1 to 89.8% in DM rats).

CONCLUSIONS/INTERPRETATION

BOLD and IVIM-D can be effective noninvasive tools in predicting CI-AKI. The innate immune response is activated during the progression of CI-AKI and DM will exacerbate this progression.

Roles of NLRP3 inflammasome in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is one of the leading causes of low back pain and one of the most common health problems in the world. The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing-3 (NLRP3) inflammasome, as a pattern recognition receptor, has been shown to be associated with the pathological processes of many diseases in recent years. With the exploration of the mechanism of IVDD, recent studies have shown that activation of the NLRP3 inflammasome is associated with intervertebral disc (IVD) inflammation, pyroptosis, extracellular matrix degradation and apoptosis of IVD cells. In this review, we summarize the structural characteristics of NLRP3 inflammasome and the activation signalling mechanisms. We also describe the role of the NLRP3 inflammasome in the pathological process of IVDD and the application of the targeting the NLRP3 inflammasome in IVDD treatment.

VDAC1 regulates mitophagy in NLRP3 inflammasome activation in retinal capillary endothelial cells under high-glucose conditions

Diabetic retinopathy (DR) has been considered to involve mitochondrial alterations and be related to the nucleotide-binding oligomerization domain-like receptors 3 (NLRP3) inflammasome activation. The voltage-dependent anion channel 1 (VDAC1) protein is one of the key proteins that regulates the metabolic and energetic functions of the mitochondria. To explore the involvement of VDAC1 in mitophagy regulation of NLRP3 inflammasome activation under high-glucose (HG) conditions, this study examined expressions of VDAC1, mitochondrial function and mitophagy-related proteins, and NLRP3 inflammasome-related proteins in human retinal capillary endothelial cells (HRCECs) cultured with 30 mM of glucose in the presence or absence of mitophagy inhibitor (Mdivi-1) using Western blot. Mitochondrial membrane potential and mitochondrial reactive oxygen species (mtROS) were detected using flow cytometry. GFP-tagged pAdTrack-VDAC1 adenovirus was used to overexpress VDAC1. Cell biological behaviors, including proliferation, migration, tubule formation, and apoptosis, were also observed. Our results showed that when compared to the normal glucose and high mannitol groups, increased amounts of mitochondrial fragments, reduced mitochondrial membrane potential, increased expression of mitochondrial fission protein Drp 1, decreased expression of mitochondrial fusion protein Mfn 2, accumulation of mtROS, and activation of the NLRP3 inflammasome were observed in the HG group. Meanwhile, HG markedly reduced the protein expressions of PINK1, Parkin and VDAC1. Inhibition of mitophagy reduced PINK1 expression, enhanced NLRP3 expression, but failed to alter VDAC1. VDAC1 overexpression promoted PINK1 expression, inhibited NLRP3 activation and changed the cell biological behaviors under HG conditions. These findings demonstrate that VDAC1-mediated mitophagy plays a crucial role in regulating NLRP3 inflammasome activation in retinal capillary endothelial cells under HG conditions, suggesting that VDAC1 may be a potential target for preventing or treating DR.

CY-09 attenuates the progression of osteoarthritis via inhibiting NLRP3 inflammasome-mediated pyroptosis

Excessive activation of inflammation in chondrocyte has been considered to be a major reason cause of cellular death and degeneration in osteoarthritis (OA) development. The NLRP3 inflammasome-mediated pyroptosis pathway is closely related to inflammation regulation. This research was conducted to confirm whether NLRP3 expression and activity are impacted in the development of OA and to detect the role of CY-09, a selective and direct inhibitor of NLRP3 in the in vitro and in vivo models of OA. Our findings corroborated that the expression of NLRP3 is stimulated in OA cartilage. CY-09 can maintain extracellular matrix (ECM) homeostasis and regulate inflammation in TNF-α treated chondrocytes via inhibition of NLRP3 inflammasome-mediated pyroptosis. Moreover, the chondrocyte protective effects of CY-09 were further confirmed in vivo in a DMM-induced OA model. In conclusion, our research indicates that experimental OA activated the NLRP3 activity, and pharmacological inhibition of NLRP3 inflammasome activation by CY-09 protects chondrocytes against inflammation and attenuates OA development.

Micro-ribonucleic acid-23a-3p prevents the onset of type 2 diabetes mellitus by suppressing the activation of nucleotide-binding oligomerization-like receptor family pyrin domain containing 3 inflammatory bodies-caused pyroptosis through negatively regulating NIMA-related kinase 7

AIMS/INTRODUCTION

Micro-ribonucleic acids (miRNAs) possess crucial functions in governing metabolisms associated with type 2 diabetes mellitus. This study aimed to investigate the role of miR-23a-3p in pyroptosis caused by nucleotide-binding oligomerization-like receptor family pyrin domain containing 3 (NLRP3) inflammatory body activation, thereby reducing the occurrence of type 2 diabetes mellitus.

MATERIALS AND METHODS

miR-23a-3p and NIMA-related kinase 7 (NEK7) expression in type 2 diabetes mellitus patients and rat models was examined. Dual-luciferase reporter gene experiments were used to verify the targeting relationship between miR-23a-3p and NEK7. Bone marrow-derived macrophages were transfected with miR-23a-3p mimic, miR-23a-3p inhibitor or short hairpin NEK7 and were treated with a specific activator of NLRP3 inflammatory body (lipopolysaccharide + adenosine-5'-triphosphate) to evaluate expression of NEK7, miR-23a-3p, gasdermin D p30, pro-caspase-1 and caspase-1 in cells, and interleukin-1β and tumor necrosis factor-α in supernatant. Type 2 diabetes mellitus rat models were used to observe the influences of miR-23a-3p, NEK7 and NLRP3 inflammatory body on pyroptosis and type 2 diabetes mellitus in vivo.

RESULTS

NEK7 was overexpressed, whereas miR-23a-3p was underexpressed in patients and rat models with type 2 diabetes mellitus. NEK7 was a target gene of miR-23a-3p. After the addition of lipopolysaccharide + adenosine-5'-triphosphate in bone marrow-derived macrophages, the expression of miR-23a-3p subsequently declined. Furthermore, the addition of lipopolysaccharide + adenosine-5'-triphosphate elevated NEK7, NLRP3, pro-caspase-1, cle-caspase-1 and gasdermin D p30 expressions in bone marrow-derived macrophages, and enhanced levels of interleukin-1β and tumor necrosis factor-α in the supernatant, accompanied with conspicuous cell pyroptosis, which was reversed after miR-23a-3p overexpression and NEK7 silencing. miR-23a-3p overexpression alleviated liver and kidney damage in type 2 diabetes mellitus rats, and reduced NLRP3-induced pyroptosis.

CONCLUSIONS

Targeting NEK7 by miR-23a-3p could reduce NLRP3-induced pyroptosis, and assuage liver and kidney injuries in type 2 diabetes mellitus rats.

The near-infrared dye IR-61 restores erectile function in a streptozotocin-induced diabetes model via mitochondrial protection

This study aimed to evaluate the therapeutic effect of IR-61, a novel mitochondrial heptamethine cyanine dye with antioxidant effects, on diabetes mellitus-induced erectile dysfunction (DMED). Eight-week-old male Sprague-Dawley rats were intraperitoneally injected with streptozotocin (STZ) to induce type 1 diabetes. Eight weeks after STZ injection, all rats were divided into three groups: the control group, DM group, and DM + IR-61 group. In the DM + IR-61 group, the rats were administered IR-61 (1.6 mg kg^-1) twice a week by intravenous injection. At week 13, erectile function was evaluated by determining the ratio of the maximal intracavernous pressure to mean arterial pressure, and the penises were then harvested for fluorescent imaging, transmission electron microscopy, histological examinations, and Western blot analysis. Whole-body imaging suggested that IR-61 was highly accumulated in the penis after intravenous injection. IR-61 treatment significantly improved the maximal ICP of diabetic rats. Additionally, IR-61 ameliorated diabetes-induced inflammation, apoptosis, and phenotypic transition of corpus cavernosum smooth muscle cells (CCSMCs) in penile tissue. IR-61 also attenuated mitochondrial damage, reduced reactive oxygen species production in the corpus cavernosum and upregulated sirtuin1 (SIRT1), sirtuin3 (SIRT3), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and heme oxygenase expression in penile tissue. In conclusion, IR-61 represents a potential therapeutic option for DMED by protecting the mitochondria of CCSMCs, which may be mediated by activation of the SIRT1, SIRT3, and Nrf2 pathways.

NLRP3 Inflammasome: A New Target for Prevention and Control of Osteoporosis?

Osteoporosis is a systemic bone metabolism disease that often causes complications, such as fractures, and increases the risk of death. The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an intracellular multiprotein complex that regulates the maturation and secretion of Caspase-1 dependent proinflammatory cytokines interleukin (IL)-1β and IL-18, mediates inflammation, and induces pyroptosis. The chronic inflammatory microenvironment induced by aging or estrogen deficiency activates the NLRP3 inflammasome, promotes inflammatory factor production, and enhances the inflammatory response. We summarize the related research and demonstrate that the NLRP3 inflammasome plays a vital role in the pathogenesis of osteoporosis by affecting the differentiation of osteoblasts and osteoclasts. IL-1β and IL-18 can accelerate osteoclast differentiation by expanding inflammatory response, and can also inhibit the expression of osteogenic related proteins or transcription factors. In vivo and in vitro experiments showed that the overexpression of NLRP3 protein was closely related to aggravated bone resorption and osteogenesis deficiency. In addition, abnormal activation of NLRP3 inflammasome can not only produce inflammation, but also lead to pyroptosis and dysfunction of osteoblasts by upregulating the expression of Caspase-1 and gasdermin D (GSDMD). In conclusion, NLRP3 inflammasome overall not only accelerates bone resorption, but also inhibits bone formation, thus increasing the risk of osteoporosis. Thus, this review highlights the recent studies on the function of NLRP3 inflammasome in osteoporosis, provides information on new strategies for managing osteoporosis, and investigates the ideal therapeutic target to treat osteoporosis.

Mitochondria and T2D: Role of Autophagy, ER Stress, and Inflammasome

Type 2 diabetes (T2D) is one of the main current threats to human health. Both T2D and its numerous clinical complications are related to mitochondrial dysfunction and oxidative stress. Over the past decade, great progress has been made in extending our knowledge about the signaling events regulated by mitochondria. However, the links among mitochondrial impairment, oxidative stress, autophagy, endoplasmic reticulum (ER) stress, and activation of the inflammasome still need to be clarified. In light of this deficit, we aim to provide a review of the existing literature concerning the complicated crosstalk between mitochondrial impairment, autophagy, ER stress, and the inflammasome in the molecular pathogenesis of T2D.