Induction of Autophagy by Extract from Corydalis heterocarpa for Skin Anti-Aging.

The extracts of Corydalis heterocarpa, a salt-tolerant plant, exhibit diverse physiological properties, including anti-inflammatory, anticancer, and antiadipogenic effects. However, the anti-aging effects of C. heterocarpa extract (CHE) on human skin cells have not yet been investigated. In the present study, we determined that CHE inhibited senescence-associated ß-galactosidase (SA-ß-gal)-stained senescent human dermal fibroblasts (HDFs). Furthermore, CHE markedly suppressed the expression of major regulatory proteins involved in senescence, including p53, p21, and caveolin-1. Interestingly, CHE promoted autophagic flux, as confirmed by the formation of microtubule-associated protein 1 light chain 3B (LC3B) puncta and lysosomal activity. Notably, using RNA sequencing (RNA-seq), we showed that CHE selectively regulated the gene expression of leucine-rich repeat and sterile alpha motif-containing 1 (LRSAM1), an important regulator of autophagy. The adenosine-monophosphate activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway, which is essential for autophagy regulation, was also modulated by CHE. LRSAM1 depletion not only inhibited LC3B expression but also decreased the autophagy flux induced by CHE. Moreover, the knockdown of LRSAM1 suppressed the reversal of CHE-induced senescence in old HDFs. Collectively, our study has revealed the rejuvenating effects and molecular mechanisms of CHE, suggesting that CHE may be a promising anti-aging agent.

The Potentiality of Natural Products and Herbal Medicine as Novel Medications for Parkinson's Disease: A Promising Therapeutic Approach.

As the global population ages, the prevalence of Parkinson's disease (PD) is steadily on the rise. PD demonstrates chronic and progressive characteristics, and many cases can transition into dementia. This increases societal and economic burdens, emphasizing the need to find effective treatments. Among the widely recognized causes of PD is the abnormal accumulation of proteins, and autophagy dysfunction accelerates this accumulation. The resultant Lewy bodies are also commonly found in Alzheimer's disease patients, suggesting an increased potential for the onset of dementia. Additionally, the production of free radicals due to mitochondrial dysfunction contributes to neuronal damage and degeneration. The activation of astrocytes and the M1 phenotype of microglia promote damage to dopamine neurons. The drugs currently used for PD only delay the clinical progression and exacerbation of the disease without targeting its root cause, and come with various side effects. Thus, there is a demand for treatments with fewer side effects, with much potential offered by natural products. In this study, we reviewed a total of 14 articles related to herbal medicines and natural products and investigated their relevance to possible PD treatment. The results showed that the reviewed herbal medicines and natural products are effective against lysosomal disorder, mitochondrial dysfunction, and inflammation, key mechanisms underlying PD. Therefore, natural products and herbal medicines can reduce neurotoxicity and might improve both motor and non-motor symptoms associated with PD. Furthermore, these products, with their multi-target effects, enhance bioavailability, inhibit antibiotic resistance, and might additionally eliminate side effects, making them good alternative therapies for PD treatment.

Natural Products as the Potential to Improve Alzheimer's and Parkinson's Disease.

Alzheimer's disease and Parkinson's disease are the two most common neurodegenerative diseases in the world, and their incidence rates are increasing as our society ages. This creates a significant social and economic burden. Although the exact cause and treatment methods for these diseases are not yet known, research suggests that Alzheimer's disease is caused by amyloid precursor protein, while α-synuclein acts as a causative agent in Parkinson's disease. The accumulation of abnormal proteins such as these can lead to symptoms such as loss of protein homeostasis, mitochondrial dysfunction, and neuroinflammation, which ultimately result in the death of nerve cells and the progression of neurodegenerative diseases. The medications currently available for these diseases only delay their progression and have many adverse effects, which has led to increased interest in developing natural products with fewer adverse effects. In this study, we selected specific keywords and thesis content to investigate natural products that are effective in treating Alzheimer's and Parkinson's diseases. We reviewed 16 papers on natural products and found that they showed promising mechanisms of action such as antioxidant, anti-inflammatory, and mitochondrial function improvement. Other natural products with similar properties could also be considered potential treatments for neurodegenerative diseases, and they can be consumed as part of a healthy diet rather than as medicine.

Regnase-1 plays an essential role in maintaining skin immune homeostasis via regulation of chemokine expression.

Regnase-1 is an endoribonuclease that regulates the stability of target genes. Here, we investigated whether Regnase-1 plays a regulatory role in the pathophysiology of atopic dermatitis, a chronic inflammatory skin disease. Regnase-1 levels were decreased in skin and serum of atopic dermatitis patients and mice. Regnase-1+/- mice exhibited more severe atopic dermatitis symptoms than wild-type mice in a house dust mite allergen-induced atopic dermatitis model. Regnase-1 deficiency led to the global changes in gene expression related with innate immune and inflammatory responses, in particular chemokines. The skin Regnase-1 level had an inverse relationship with chemokine expression when we analyzed samples of atopic dermatitis patients and Regnase-1-deficient mice, suggesting that potentiated chemokine production contributes to the augmented inflammation at lesion sites. Subcutaneous administration of recombinant Regnase-1 to mice significantly ameliorated atopic dermatitis-like skin inflammation with reduced chemokine production in a house dust mite-induced atopic dermatitis NC/Nga mouse model. These results indicate that Regnase-1 plays an essential role in maintaining skin immune homeostasis as a regulator of chemokine expression. Modulating Regnase-1 activity may be an efficient therapeutic strategy for treating chronic inflammatory diseases, including atopic dermatitis.

Loganin Prevents Hepatic Steatosis by Blocking NLRP3 Inflammasome Activation.

Activation of the NLRP3 inflammasome is a necessary process to induce fibrosis in nonalcoholic fatty liver disease (NAFLD). Nonalcoholic steatohepatitis (NASH) is a kind of NAFLD that encompasses the spectrum of liver disease. It is characterized by inflammation and ballooning of hepatocytes during steatosis. We tested whether inhibiting the NLRP3 inflammasome could prevent the development and pathology of NASH. We identified loganin as an inhibitor of the NLRP3 inflammasome and investigated whether in vivo administration of loganin prevented NASH symptoms using a methionine-choline deficient (MCD) diet model in mice. We found that loganin inhibited the NLRP3 inflammasome activation triggered by ATP or nigericin, as shown by suppression of the production of interleukin (IL)-1ß and caspase-1 (p10) in mouse primary macrophages. The speck formation of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) was blocked by loganin, showing that the assembly of the NLRP3 inflammasome complex was impaired by loganin. Administration of loganin reduced the clinical signs of NASH in mice fed the MCD diet, including hepatic inflammation, fat accumulation, and fibrosis. In addition, loganin reduced the expression of NLRP3 inflammasome components in the liver. Our findings indicate that loganin alleviates the inflammatory symptoms associated with NASH, presumably by inhibiting NLRP3 inflammasome activation. In summary, these findings imply that loganin may be a novel nutritional and therapeutic treatment for NASH-related inflammation.

Verbenalin Reduces Amyloid-Beta Peptide Generation in Cellular and Animal Models of Alzheimer's Disease.

Verbenalin, among the major constituents of Verbena officinalis, has been reported to exhibit sleep-promoting and antioxidant activities. This study demonstrates the effects of verbenalin on amyloid-beta (Aß) peptide generation in Swedish mutant amyloid precursor protein (APP)-overexpressing Neuro2a cells (SweAPP/N2a) and in Alzheimer's disease (AD) animal models. We further performed molecular biological analyses of these in vitro and in vivo models of AD. The effects of verbenalin were assessed based on the expression of factors related to Aß peptide production using Western blotting, enzyme-linked immunosorbent assay, and immunohistochemistry (IHC). The intracellular expression and release of APP protein were both decreased by verbenalin treatment in SweAPP/N2a cells. Thus, the production of Aß peptides was decreased. Compared to those in AD transgenic (Tg) mice, IHC revealed that verbenalin-treated animals showed decreased Aß and tau expression levels in the hippocampus. In addition, verbenalin restored the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus of AD animal models. These findings suggest that verbenalin may decrease Aß formation both in vitro and in vivo. Verbenalin may also help improve the pathological hallmarks of AD.

Inflammasomes and their roles in arthritic disease pathogenesis.

The inflammasome is a molecular platform that is created in the cytosolic compartment to mediate the host immunological response to cellular injury and infection. Caspase-1 may be activated by the inflammasome, which leads to the generation of the inflammatory cytokines interleukin-1ß (IL-1ß) and IL-18 and the beginning of pyroptosis, which is a type of proinflammatory cell death. Scientists have identified a number of different inflammasomes in the last 2 decades. The NLRP3 inflammasome has been studied the most, and its activity may be triggered by a broad range of different inducers. However, activation of the NLRP3 inflammasome in a manner that is not properly controlled is also a factor in the etiology of many human illnesses. Accumulating evidence indicates that the NLRP3 inflammasome plays a significant role in the innate and adaptive immune systems and the development of various arthritic illnesses, such as rheumatoid arthritis, ankylosing spondylitis, and gout. The present review provides a concise summary of the biological properties of the NLRP3 inflammasome and presents the fundamental processes behind its activation and control. We discuss the role of the inflammasome in the pathogenesis of arthritic diseases, such as rheumatoid arthritis, ankylosing spondylitis, and gout, and the potential of newly developed therapies that specifically target the inflammasome or its products for the treatment of inflammatory diseases, with a particular emphasis on treatment and clinical application.

Natural Products as a Novel Therapeutic Strategy for NLRP3 Inflammasome-Mediated Gout.

Gout is the most common form of inflammatory arthritis. It occurs when monosodium urate crystals (MSU) are deposited within joints due to hyperuricemia and persistent elevations of serum uric acid levels. Traditional gout treatment such as urate-lowering therapy is difficult to continue for a long period of time due to the risk of side effects. Recent studies have shown that the modulation of MSU-induced inflammatory responses is dependent on the inflammatory cytokine IL-1ß, which has a central role in a chain of processes involving multiple cytokines and mediators. In this regard, the NLRP3 inflammasome is known to play a crucial part and thus has been proposed as a novel target in the treatment for gout. However, the biochemical mechanism for NLRP3 inflammasome activation has not yet been clearly elucidated. Therefore, this report can provide an overview of natural extractions targeted to prevent or treat NLRP3 inflammasome-mediated gout in the MSU-induced gout model. In addition, the research and development of such natural products are suggested as a potential strategy in the treatment of gout.

Improvement Effect of Soyeom Pharmacopuncture on Gout via NLRP3 Inflammasome Regulation.

Objectives: Gout is an inflammatory arthritis of the joints and soft tissues occurring due to deposition of monosodium urate (MSU) crystals, which are caused by persistent hyperuricemia. Soyeom pharmacopuncture is one treatment method that has been traditionally used for pain management in Oriental medicine. However, studies on its effect in reducing gout pain have been insufficient. Therefore, we selected Soyeom pharmacopuncture among natural products used in Korea as the new target of our study. Methods: The effects of Soyeom pharmacopuncture were examined in mouse models of acute gout induced by injection of MSU crystals into footpads. IL-1ß, IL-6, and TNF-α production were examined by immunoblotting and enzyme-linked immunosorbent assay as hallmarks of NLRP3 inflammasome and cytokine activation. Results: Soyeom pharmacopuncture reduced foot edema in gout-induced mice, as well as IL-1ß, nitrite, IL-6, and TNF-α production. Moreover, Soyeom pharmacopuncture also reduced MSU-induced gout inflammatory gene expressions, specifically those in the NF-kB pathway. Conclusion: Pharmacopuncture may serve as a new solution for other inflammatory diseases as well. Through active follow-up studies, we could thoroughly understand the clinical value of Soyeom pharmacopuncture.

Bacterial Reverse Mutation Test of Verbenalin.

Objectives: Verbenalin is a compound found in herbs such as Cornus officinalis and Verbena officinalis. This study investigated whether verbenalin is safe by analyzing its mutagenicity. Methods: To examine the mutagenic potential of verbenalin, a bacterial reverse mutation test (Ames test) was conducted with Salmonella typhimurium and Escherichia coli strains. Experiments with and without metabolic activity were performed. Results: The mean colony number was less than double that of the control. Growth inhibition and precipitation of verbenalin were not apparent in all strains at different concentrations regardless of metabolic activity. Conclusion: Verbenalin did not show any signs of mutagenicity in this study. Additional toxicity studies including repeated oral toxicity, reproductive toxicity, and carcinogenicity tests are needed.

RIG-I Deficiency Promotes Obesity-Induced Insulin Resistance.

Inflammation and immunity are linked to the onset and development of obesity and metabolic disorders. Pattern recognition receptors (PRRs) are key regulators of inflammation and immunity in response to infection and stress, and they have critical roles in metainflammation. In this study, we investigated whether RIG-I (retinoic acid-inducible gene I)-like receptors were involved in the regulation of obesity-induced metabolic stress in RIG-I knockout (KO) mice fed a high-fat diet (HFD). RIG-I KO mice fed an HFD for 12 weeks showed greater body weight gain, higher fat composition, lower lean body mass, and higher epididymal white adipose tissue (eWAT) weight than WT mice fed HFD. In contrast, body weight gain, fat, and lean mass compositions, and eWAT weight of MDA5 (melanoma differentiation-associated protein 5) KO mice fed HFD were similar to those of WT mice fed a normal diet. RIG-I KO mice fed HFD exhibited more severely impaired glucose tolerance and higher HOMA-IR values than WT mice fed HFD. IFN-ß expression induced by ER stress inducers, tunicamycin and thapsigargin, was abolished in RIG-I-deficient hepatocytes and macrophages, showing that RIG-I is required for ER stress-induced IFN-ß expression. Our results show that RIG-I deficiency promotes obesity and insulin resistance induced by a high-fat diet, presenting a novel role of RIG-I in the development of obesity and metabolic disorders.

Topical application of celastrol alleviates atopic dermatitis symptoms mediated through the regulation of thymic stromal lymphopoietin and group 2 innate lymphoid cells.

Atopic dermatitis is a chronic inflammatory skin disease, of which incidence is closely related to exposure to environmental pollutants and allergens. Thymic stromal lymphopoietin (TSLP) plays an important role in the early stages of atopic dermatitis development by inducing Th2 immune responses. In addition, TSLP regulates activation of group 2 innate lymphoid cells (ILC2), promoting the pathogenesis of atopic dermatitis. The aim of this study was to investigate whether celastrol alleviated atopic dermatitis symptoms by regulating TSLP expression and ILC2 stimulation. Celastrol suppressed TSLP production in mouse keratinocyte cells by inhibiting NF-ĸB activation. Topical application of celastrol significantly improved atopic dermatitis symptoms induced by house dust mite (HDM) in NC/Nga mice as determined by dermatitis score and histological assessment. Celastrol decreased the levels of TSLP in atopic dermatitis skin lesions of HDM-stimulated NC/Nga mice. Celastrol reduced levels of Th2 cytokines including IL-4, IL-5, and IL-13 in atopic dermatitis skin lesions of NC/Nga mice. Further, celastrol significantly reduced ILC2 population in atopic dermatitis skin lesions of NC/Nga mice. These results indicate that topical application of celastrol improved atopic dermatitis symptoms by lowering TSLP levels and concomitant immune responses. Data demonstrated that reduced TSLP levels and associated lower number of ILC2 cells alleviate atopic dermatitis symptoms induced by house dust mite.

Oxidized Phospholipids in Tumor Microenvironment Stimulate Tumor Metastasis via Regulation of Autophagy.

Oxidized phospholipids are well known to play physiological and pathological roles in regulating cellular homeostasis and disease progression. However, their role in cancer metastasis has not been entirely understood. In this study, effects of oxidized phosphatidylcholines such as 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC) on epithelial-mesenchymal transition (EMT) and autophagy were determined in cancer cells by immunoblotting and confocal analysis. Metastasis was analyzed by a scratch wound assay and a transwell migration/invasion assay. The concentrations of POVPC and 1-palmitoyl-2-glutaroyl-sn-glycero-phosphocholine (PGPC) in tumor tissues obtained from patients were measured by LC-MS/MS analysis. POVPC induced EMT, resulting in increase of migration and invasion of human hepatocellular carcinoma cells (HepG2) and human breast cancer cells (MCF7). POVPC induced autophagic flux through AMPK-mTOR pathway. Pharmacological inhibition or siRNA knockdown of autophagy decreased migration and invasion of POVPC-treated HepG2 and MCF7 cells. POVPC and PGPC levels were greatly increased at stage II of patient-derived intrahepatic cholangiocarcinoma tissues. PGPC levels were higher in malignant breast tumor tissues than in adjacent nontumor tissues. The results show that oxidized phosphatidylcholines increase metastatic potential of cancer cells by promoting EMT, mediated through autophagy. These suggest the positive regulatory role of oxidized phospholipids accumulated in tumor microenvironment in the regulation of tumorigenesis and metastasis.

Loganin Alleviates Gout Inflammation by Suppressing NLRP3 Inflammasome Activation and Mitochondrial Damage.

Gout is a type of inflammatory arthritis caused by the deposition of monosodium uric acid (MSU) crystals in tissues. The etiology of gout is directly linked to the NLRP3 inflammasome, since MSU crystals are NLRP3 inflammasome activators. Therefore, we decided to search for a small-molecule inhibitor of the NLRP3 inflammasome for the prevention of gout inflammation. We found that loganin suppressed MSU crystals-induced caspase-1 (p20) and interleukin (IL)-1ß production and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks formation in mouse primary macrophages, showing its ability to inhibit the NLRP3 inflammasome. In an air pouch inflammation model, oral administration of loganin to mice prevented MSU crystals-induced production of mature IL-1ß and IL-18 in air pouch exudates, resulting in decreased neutrophil recruitment. Furthermore, oral administration of loganin suppressed MSU crystals-induced gout inflammation in a mouse foot gout model, which was accompanied by the inhibition of the NLRP3 inflammasome. Loganin blocked de novo synthesis of mitochondrial DNA in air pouches and foot tissues injected with MSU crystals. Consistently, loganin prevented MSU crystals-induced mitochondrial damage in macrophages, as it increased mitochondrial membrane potential and decreased the amount of mitochondrial reactive oxygen species. These data demonstrate that loganin suppresses NLRP3 inflammasome activation by inhibiting mitochondrial stress. These results suggest a novel pharmacological strategy to prevent gout inflammation by blocking NLRP3 inflammasome activation and mitochondrial dysfunction.

A Novel Treatment Strategy by Natural Products in NLRP3 Inflammasome-Mediated Neuroinflammation in Alzheimer's and Parkinson's Disease.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases. Many studies have demonstrated that the release of NLRP3 inflammasome-mediated proinflammatory cytokines by the excessive activation of microglia is associated with the pathogenesis of AD and PD and suggested that the NLRP3 inflammasome plays an important role in AD and PD development. In both diseases, various stimuli, such as Aß and α-synuclein, accelerate the formation of the NLRP3 inflammasome in microglia and induce pyroptosis through the expression of interleukin (IL)-1ß, caspase-1, etc., where neuroinflammation contributes to gradual progression and deterioration. However, despite intensive research, the exact function and regulation of the NLRP3 inflammasome has not yet been clearly identified. Moreover, there have not yet been any experiments of clinical use, although many studies have recently been conducted to improve treatment of inflammatory diseases using various inhibitors for NLRP3 inflammasome pathways. However, recent studies have reported that various natural products show improvement effects in the in vivo models of AD and PD through the regulation of NLRP3 inflammasome assembly. Therefore, the present review provides an overview of natural extraction studies aimed at the prevention or treatment of NLRP3 inflammasome-mediated neurological disorders. It is suggested that the discovery and development of these various natural products could be a potential strategy for NLRP3 inflammasome-mediated AD and PD treatment.

Para-phenylenediamine, an oxidative hair dye ingredient, increases thymic stromal lymphopoietin and proinflammatory cytokines causing acute dermatitis.

Due to high consumption of cosmetics in modern society, people are always exposed to the risk of skin damage and complications. Para-phenylenediamine (P-PD), an ingredient of hair dye, has been reported to cause allergic contact dermatitis. However, the mechanism has not been well elucidated. Here, we identify that P-PD causes dermatitis by increasing thymic stromal lymphopoietin (TSLP) and inflammatory cytokines. Topical application of P-PD to mouse ear skin in consecutive 5 days resulted in dermatitis symptoms and increased ear thickness. TSLP production in skin was upregulated by P-PD treatment alone. In addition, P-PD-induced TSLP production was potentiated by MC903, which is an in vivo TSLP inducer. P-PD increased TSLP production in keratinocytes (KCMH-1 cells and phorbol 12-myristate 13-acetate-stimulated PAM212 cells). The production of proinflammatory cytokines such as IL-1ß, IL-6, IFN-γ, and CCL2, was upregulated by P-PD treatment together with MC903. The results show that repeated exposure to P-PD causes acute contact dermatitis mediated by increasing the expression of TSLP and proinflammatory cytokines.

Repurposing Auranofin, an Anti-Rheumatic Gold Compound, to Treat Acne Vulgaris by Targeting the NLRP3 Inflammasome.

Activation of the NLRP3 inflammasome is critical for host defense as well as the progression of inflammatory diseases through the production of the proinflammatory cytokine IL-1ß, which is cleaved by active caspase-1. It has been reported that overactivation of the NLRP3 inflammasome contributes to the development and pathology of acne vulgaris. Therefore, inhibiting activation of the NLRP3 inflammasome may provide a new therapeutic strategy for acne vulgaris. In this study, we investigated whether auranofin, an anti-rheumatoid arthritis agent, inhibited NLRP3 inflammasome activation, thereby effectively treating acne vulgaris. Auranofin suppressed NLRP3 inflammasome activation induced by Propionibacterium acnes, reducing the production of IL-1ß in primary mouse macrophages and human sebocytes. In a P. acnes-induced acne mouse model, injection of P. acnes into the ears of mice induced acne symptoms such as redness, swelling, and neutrophil infiltration. Topical application of auranofin (0.5 or 1%) to mouse ears significantly reduced the inflammatory symptoms of acne vulgaris induced by P. acnes injection. Topical application of auranofin led to the downregulation of the NLRP3 inflammasome activated by P. acnes in mouse ear skin. These results show that auranofin inhibits the NLRP3 inflammasome, the activation of which is associated with acne symptoms. The results further suggest that topical application of auranofin could be a new therapeutic strategy for treating acne vulgaris by targeting the NLRP3 inflammasome.

Sweroside Prevents Non-Alcoholic Steatohepatitis by Suppressing Activation of the NLRP3 Inflammasome.

Non-alcoholic steatohepatitis (NASH), a type of non-alcoholic fatty liver disease, is characterized as steatosis and inflammation in the liver. NLRP3 inflammasome activation is associated with NASH pathology. We hypothesized that suppressing the NLRP3 inflammasome could be effective in preventing NASH. We searched substances that could inhibit the activation of the NLRP3 inflammasome and identified sweroside as an NLRP3 inhibitor. We investigated whether sweroside can be applied to prevent the pathological symptoms associated with NASH in a methionine-choline-deficient (MCD) diet-induced NASH mouse model. The activation of the NLRP3 inflammasome was determined by detecting the production of caspase-1 and IL-1ß from pro-caspase-1 and pro-IL-1ß in primary mouse macrophages and mouse liver. In a NASH model, mice were fed an MCD diet for two weeks with daily intraperitoneal injections of sweroside. Sweroside effectively inhibited NLRP3 inflammasome activation in primary macrophages as shown by a decrease in IL-1ß and caspase-1 production. In a MCD diet-induced NASH mouse model, intraperitoneal injection of sweroside significantly reduced serum aspartate transaminase and alanine transaminase levels, hepatic immune cell infiltration, hepatic triglyceride accumulation, and liver fibrosis. The improvement of NASH symptoms by sweroside was accompanied with its inhibitory effects on the hepatic NLRP3 inflammasome as hepatic IL-1ß and caspase-1 were decreased. Furthermore, sweroside blocked de novo synthesis of mitochondrial DNA in the liver, contributing to suppression of the NLRP3 inflammasome. These results suggest that targeting the NLRP3 inflammasome with sweroside could be beneficially employed to improve NASH symptoms.

Skin Barrier Abnormalities and Immune Dysfunction in Atopic Dermatitis.

Atopic dermatitis (AD) is a common and relapsing skin disease that is characterized by skin barrier dysfunction, inflammation, and chronic pruritus. While AD was previously thought to occur primarily in children, increasing evidence suggests that AD is more common in adults than previously assumed. Accumulating evidence from experimental, genetic, and clinical studies indicates that AD expression is a precondition for the later development of other atopic diseases, such as asthma, food allergies, and allergic rhinitis. Although the exact mechanisms of the disease pathogenesis remain unclear, it is evident that both cutaneous barrier dysfunction and immune dysregulation are critical etiologies of AD pathology. This review explores recent findings on AD and the possible underlying mechanisms involved in its pathogenesis, which is characterized by dysregulation of immunological and skin barrier integrity and function, supporting the idea that AD is a systemic disease. These findings provide further insights for therapeutic developments aiming to repair the skin barrier and decrease inflammation.

Direct Binding to NLRP3 Pyrin Domain as a Novel Strategy to Prevent NLRP3-Driven Inflammation and Gouty Arthritis.

OBJECTIVE: The NLRP3 inflammasome is closely linked to the pathophysiology of a wide range of inflammatory diseases. This study was undertaken to identify small molecules that directly bind to NLRP3 in order to develop pharmacologic interventions for NLRP3-related diseases. METHODS: A structure-based virtual screening analysis was performed with ~62,800 compounds to select efficient NLRP3 inhibitors. The production of caspase 1-p10 and interleukin-1ß (IL-1ß) was measured by immunoblotting and enzyme-linked immunosorbent assay to examine NLRP3 inflammasome activation. Two gouty arthritis models and an air pouch inflammation model induced by monosodium urate monohydrate (MSU) crystal injection were used for in vivo experiments. Primary synovial fluid cells from gout patients were used to determine the relevance of NLRP3 inflammasome inhibition in human gout. RESULTS: Beta-carotene (provitamin A) suppressed the NLRP3 inflammasome activation induced by various activators, including MSU crystals, in mouse bone marrow-derived primary macrophages (P < 0.05). Surface plasmon resonance analysis demonstrated the direct binding of ß-carotene to the pyrin domain (PYD) of NLRP3 (KD = 3.41 × 10-6 ). Molecular modeling and mutation assays revealed the interaction mode between ß-carotene and the NLRP3 PYD. Inflammatory symptoms induced by MSU crystals were attenuated by oral administration of ß-carotene in gouty arthritis mouse models (P < 0.05), correlating with its suppressive effects on the NLRP3 inflammasome in inflamed tissues. Furthermore, ß-carotene reduced IL-1ß secretion from human synovial fluid cells isolated from gout patients (P < 0.05), showing its inhibitory efficacy in human gout. CONCLUSION: Our results present ß-carotene as a selective and direct inhibitor of NLRP3, and the binding of ß-carotene to NLRP3 PYD as a novel pharmacologic strategy to combat NLRP3 inflammasome-driven diseases, including gouty arthritis.