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

Neuroinflammation and COVID-19 Ischemic Stroke Recovery—Evolving Evidence for the Mediating Roles of the ACE2/Angiotensin-(1–7)/Mas Receptor Axis and NLRP3 Inflammasome

Cerebrovascular events, notably acute ischemic strokes (AIS), have been reported in the setting of novel coronavirus disease (COVID-19) infection. Commonly regarded as cryptogenic, to date, the etiology is thought to be multifactorial and remains obscure; it is linked either to a direct viral invasion or to an indirect virus-induced prothrombotic state, with or without the presence of conventional cerebrovascular risk factors. In addition, patients are at a greater risk of developing long-term negative sequelae, i.e., long-COVID-related neurological problems, when compared to non-COVID-19 stroke patients. Central to the underlying neurobiology of stroke recovery in the context of COVID-19 infection is reduced angiotensin-converting enzyme 2 (ACE2) expression, which is known to lead to thrombo-inflammation and ACE2/angiotensin-(1–7)/mitochondrial assembly receptor (MasR) (ACE2/Ang-(1-7)/MasR) axis inhibition. Moreover, after AIS, the activated nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome may heighten the production of numerous proinflammatory cytokines, mediating neuro-glial cell dysfunction, ultimately leading to nerve-cell death. Therefore, potential neuroprotective therapies targeting the molecular mechanisms of the aforementioned mediators may help to inform rehabilitation strategies to improve brain reorganization (i.e., neuro-gliogenesis and synaptogenesis) and secondary prevention among AIS patients with or without COVID-19. Therefore, this narrative review aims to evaluate the mediating role of the ACE2/Ang- (1-7)/MasR axis and NLRP3 inflammasome in COVID-19-mediated AIS, as well as the prospects of these neuroinflammation mediators for brain repair and in secondary prevention strategies against AIS in stroke rehabilitation.

Curcumin ameliorates H2O2‑induced inflammatory response in chondrocytes by inducing autophagy activation

Relapsing polychondritis (RP) is a clinical disease characterized by inflammation of cartilage tissue and chondrocytes. The principal curcuminoid curcumin is the most active component in turmeric and has been reported to have a chondroprotective effect, including anti-inflammatory activity, which is vitally important for mitigating RP symptoms and prognosis. However, the mechanisms underlying these actions have remained to be fully elucidated. In the present study, the chondroprotective mechanisms of curcumin on hydrogen peroxide (H₂O₂)-treated primary chondrocytes were examined in vitro. The viability of chondrocytes treated with H₂O₂ was significantly reduced in a dose- and time-dependent manner. Cotreatment of curcumin with H₂O₂ significantly decreased growth inhibition. It was observed that curcumin inhibited the expression levels of the inflammatory mediators interleukin (IL)-1β, IL-6 and inducible nitric oxide synthase and induced autophagy activation. Curcumin increased the protein levels of the autophagy marker beclin-1 and light chain 3-II and decreased the expression levels of P62 in H₂O₂-treated chondrocytes. The curcumin-induced anti-inflammatory effects were markedly abrogated by the autophagy inhibitor 3-methyladenine. In conclusion, the present study suggested that curcumin regulates inflammatory factors by activating autophagy in chondrocytes. The protective role of curcumin in chondrocytes was demonstrated, suggesting that it should be explored for the prophylactic treatment of RP in the clinic in the future.

3β,23-Dihydroxy-12-ene-28-ursolic Acid Isolated from Cyclocarya paliurus Alleviates NLRP3 Inflammasome-Mediated Gout via PI3K-AKT-mTOR-Dependent Autophagy

Gout is regarded as a painful inflammatory arthritis induced by the deposition of monosodium urate crystals in joints and soft tissues. Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-mediated IL-1β production plays a crucial role in the pathological process of gout. Cyclocarya paliurus (CP) tea was found to have an effect on reducing the blood uric acid level of people with hyperuricemia and gout. However, its medicinal ingredients and mechanism for the treatment of gout are still unclear. Thus, this study was designed to investigate the effects of the active triterpenoids isolated from C. paliurus on gout and explore the underlying mechanism. The results showed that compound 2 (3β,23-dihydroxy-12-ene-28-ursolic acid) from C. paliurus significantly decreased the protein expression of IL-1β, caspase-1, pro-IL-1β, pro-caspase-1, and NLRP3. Furthermore, the production of ROS in the intracellular was reduced after compound 2 treatment. However, ROS agonist rotenone remarkably reversed the inhibitory effect of compound 2 on the protein expression of NLRP3 inflammasome. Additionally, the expression level of LC3 and the ratio of LC3II/LC3I were increased, but the expression level of p62 was suppressed by compound 2 whereas an autophagy inhibitor 3-methyladenine (3-MA) significantly abolished the inhibitory effects of compound 2 on the generation of ROS and the protein expression of NLRP3 inflammasome. Moreover, compound 2 could ameliorate the expression ratio of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR. Interestingly, mTOR activator MHY-1485 could block the promotion effect of compound 2 on autophagy regulation and inhibitory effect of compound 2 on induction of ROS and IL-1β. In conclusion, these findings suggested that compound 2 may effectively improve NLRP3 inflammasome-mediated gout via PI3K-AKT-mTOR-dependent autophagy and could be further investigated as a potential agent against gout.

Intranasal curcumin and dexamethasone combination ameliorates inflammasome (NLRP3) activation in lipopolysachharide exposed asthma exacerbations

The inflammasome NOD-like receptor (NLR) family, the pyrin domain containing 3 (NLRP3) is closely associated with exacerbation of asthma as endotoxin (lipopolysaccharide, LPS) is one of its activators present in the environment. Present study is undertaken to investigate anti-inflammatory effects of a well known phytochemical, curcumin, which might regulate LPS exposed asthma exacerbations by modulating NLRP3 activation if given through intranasal route. Balb/c mice were sensitized with intraperitoneal injection of OVA (Ovalbumin; 100 μg of OVA with alum) from day 1 to 8 and exposed to LPS with 1% OVA aerosol from day 9 to 15. LPS (0.1 μg) was given an hour before sensitization and OVA-aerosol challenge. Significant decrease in inflammatory cell recruitment and restoration of structural changes in lungs, alterations in mRNA and protein expressions of TLR-4, NF-κB, NLRP3, Caspase-1, IL-1β, MMP-9, IL-5 and IL-17 in intranasal curcumin alone and corticosteroid combined pretreatment group.

Design of Hepatic Targeted Drug Delivery Systems for Natural Products: Insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-dysfunction-associated fatty liver disease (MAFLD), affects a quarter of the worldwide population. Natural products have been extensively utilized in treating NAFLD because of their distinctive advantages over chemotherapeutic drugs, despite the fact that there are no approved drugs for therapy. Notably, the limitations of many natural products, such as poor water solubility, low bioavailability in vivo, low hepatic distribution, and lack of targeted effects, have severely restricted their clinical application. These issues could be resolved via hepatic targeted drug delivery systems (HTDDS) that boost clinical efficacy in treating NAFLD and decrease the adverse effects on other organs. Herein an overview of natural products comprising formulas, single medicinal plants, and their crude extracts has been presented to treat NAFLD. Also, the clinical efficacy and molecular mechanism of active monomer compounds against NAFLD are systematically discussed. The targeted delivery of natural products via HTDDS has been explored to provide a different nanotechnology-based NAFLD treatment strategy and to make suggestions for natural-product-based targeted nanocarrier design. Finally, the challenges and opportunities put forth by the nomenclature update of NAFLD are outlined along with insights into how to improve the NAFLD therapy and how to design more rigorous nanocarriers for the HTDDS. In brief, we summarize the up-to-date developments of the NAFLD-HTDDS based on natural products and provide viewpoints for the establishment of more stringent anti-NAFLD natural-product-targeted nanoformulations.

Curcumin Inhibits In Vitro SARS-CoV-2 Infection In Vero E6 Cells through Multiple Antiviral Mechanisms

Due to the scarcity of therapeutic approaches for COVID-19, we investigated the antiviral and anti-inflammatory properties of curcumin against SARS-CoV-2 using in vitro models. The cytotoxicity of curcumin was evaluated using MTT assay in Vero E6 cells. The antiviral activity of this compound against SARS-CoV-2 was evaluated using four treatment strategies (i. pre-post infection treatment, ii. co-treatment, iii. pre-infection, and iv. post-infection). The D614G strain and Delta variant of SARS-CoV-2 were used, and the viral titer was quantified by plaque assay. The anti-inflammatory effect was evaluated in peripheral blood mononuclear cells (PBMCs) using qPCR and ELISA. By pre-post infection treatment, Curcumin (10 µg/mL) exhibited antiviral effect of 99% and 99.8% against DG614 strain and Delta variant, respectively. Curcumin also inhibited D614G strain by pre-infection and post-infection treatment. In addition, curcumin showed a virucidal effect against D614G strain and Delta variant. Finally, the pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) released by PBMCs triggered by SARS-CoV-2 were decreased after treatment with curcumin. Our results suggest that curcumin affects the SARS-CoV-2 replicative cycle and exhibits virucidal effect with a variant/strain independent antiviral effect and immune-modulatory properties. This is the first study that showed a combined (antiviral/anti-inflammatory) effect of curcumin during SARS-CoV-2 infection. However, additional studies are required to define its use as a treatment for the COVID-19.

Curcumin prevents As3+-induced carcinogenesis through regulation of GSK3β/Nrf2

Background

Arsenic (As³⁺) is a carcinogen with considerable environmental and occupational relevancy. Its mechanism of action and methods of prevention remain to be investigated. Previous studies have demonstrated that ROS is responsible for As³⁺-induced cell transformation, which is considered as the first stage of As³⁺ carcinogenesis. The NF-E2 p45-related factor-2 (Nrf2) signaling pathway regulates the cellular antioxidant response, and activation of Nrf2 has recently been shown to limit oxidative damage following exposure to As³⁺

Methods and results

In this study, molecular docking was used to virtually screen natural antioxidant chemical databases and identify molecules that interact with the ligand-binding site of Keap1 (PDB code 4L7B). The cell-based assays and molecular docking findings revealed that curcumin has the best inhibitory activity against Keap1-4L7B. Co-immunoprecipitation (Co-IP) results indicated that curcumin is a potent Keap1 Kelch domain-dependent Nrf2 activator that stabilizes Nrf2 by hindering its ubiquitination. The increased activation of Nrf2 and its target antioxidant genes by curcumin could significantly decrease As³⁺-generated ROS. Moreover, curcumin induced autophagy in As³⁺-treated BEAS-2B via inducing autophagy by the formation of a p62/LC-3 complex and increasing autophagic flux by promoting transcription factor EB (TFEB) and lysosome-associated membrane protein 1 (LAMP1) expression. Knockdown of Nrf2 abolished curcumin-induced autophagy and downregulated ROS. Further studies showed that inhibition of autophagosome and lysosome fusion with bafilomycin a1 (BafA1) could block curcumin and prevented As³⁺-induced cell transformation. These results demonstrated that curcumin prevents As³⁺-induced cell transformation by inducing autophagy via the activation of the Nrf2 signaling pathway in BEAS-2B cells. However, overexpression of Keap-1 showed a constitutively high level of Nrf2 in As³⁺-transformed BEAS-2B cells (AsT) is Keap1-independent regulation. Overexpression of Nrf2 in AsT demonstrated that curcumin increased ROS levels and induced cell apoptosis via the downregulation of Nrf2. Further studies showed that curcumin decreased the Nrf2 level in AsT by activating GSK-3β to inhibit the activation of PI3K/AKT. Co-IP assay results showed that curcumin promoted the interaction of Nrf2 with the GSK-3β/β-TrCP axis and ubiquitin. Moreover, the inhibition of GSK-3β reversed Nrf2 expression in curcumin-treated AsT, indicating that the decrease in Nrf2 is due to activation of the GSK-3β/β-TrCP ubiquitination pathway. Furthermore, in vitro and in vivo results showed that curcumin induced cell apoptosis, and had anti-angiogenesis and anti-tumorigenesis effects as a result of activating the GSK-3β/β-TrCP ubiquitination pathway and subsequent decrease in Nrf2.

Conclusions

Taken together, in the first stage, curcumin activated Nrf2, decreased ROS, and induced autophagy in normal cells to prevent As³⁺-induced cell transformation. In the second stage, curcumin promoted ROS and apoptosis and inhibited angiogenesis via inhibition of constitutive expression of Nrf2 in AsT to prevent tumorigenesis. Our results suggest that antioxidant natural compounds such as curcumin can be evaluated as potential candidates for complementary therapies in the treatment of As³⁺-induced carcinogenesis.

An Epigenetic Insight into NLRP3 Inflammasome Activation in Inflammation-Related Processes

Aberrant NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome activation in innate immune cells, triggered by diverse cellular danger signals, leads to the production of inflammatory cytokines (IL-1β and IL-18) and cell death by pyroptosis. These processes are involved in the pathogenesis of a wide range of diseases such as autoimmune, neurodegenerative, renal, metabolic, vascular diseases and cancer, and during physiological processes such as aging. Epigenetic dynamics mediated by changes in DNA methylation patterns, chromatin assembly and non-coding RNA expression are key regulators of the expression of inflammasome components and its further activation. Here, we review the role of the epigenome in the expression, assembly, and activation of the NLRP3 inflammasome, providing a critical overview of its involvement in the disease and discussing how targeting these mechanisms by epigenetic treatments could be a useful strategy for controlling NLRP3-related inflammatory diseases.

Bisdemethoxycurcumin attenuates lipopolysaccharide-induced intestinal damage through improving barrier integrity, suppressing inflammation, and modulating gut microbiota in broilers

Bisdemethoxycurcumin has good antioxidant and anti-inflammatory effects and has been widely used as food and feed supplements in the form of curcuminoids. However, the beneficial effect of individual bisdemethoxycurcumin on preventing lipopolysaccharide (LPS)-induced inflamed intestinal damage is unclear. The present study aimed to investigate whether dietary bisdemethoxycurcumin supplementation could attenuate LPS-induced intestinal damage and alteration of cecal microbiota in broiler chickens. In total, 320 one-day-old male Arbor Acres broiler chickens with a similar weight were randomly divided into four treatments. The treatments were designed as a 2 × 2 factorial arrangement: basal diet (CON); 150 mg/kg bisdemethoxycurcumin diet (BUR); LPS challenge + basal diet (LPS); LPS challenge + 150 mg/kg bisdemethoxycurcumin diet (L-BUR). Results showed that dietary bisdemethoxycurcumin supplementation attenuated the LPS-induced decrease of average daily feed intake. LPS challenge compromised the intestinal morphology and disrupted the intestinal tight junction barrier. Dietary bisdemethoxycurcumin supplementation significantly increased villus length:crypt depth ratio and upregulated the mRNA expression of intestinal tight junction proteins. Moreover, a remarkably reduced mRNA expression of inflammatory mediators was observed following bisdemethoxycurcumin supplementation. The cecal microbiota analysis showed that bisdemethoxycurcumin supplementation increased the relative abundance of the genus Faecalibacterium while decreased the relative abundance of the genera Bacteroides and Subdoligranulum. In conclusion, dietary bisdemethoxycurcumin supplementation could counteract LPS-induced inflamed intestinal damage in broiler chickens by improving intestinal morphology, maintaining intestinal tight junction, downregulating pro-inflammatory mediators, and restoring cecal microbiota.

Network Pharmacology Analysis of Molecular Mechanism of Curcuma Longa L. extracts Regulating Glioma Immune Inflammatory Factors: Implications for Precise Cancer Treatment

INTRODUCTION

Curcuma longa L. has been associated with different antioxidant, anti-inflammatory, bactericidal and anticancer effects, but the mechanisms of the effects are not yet clearly understood. This study aimed to investigate the key targets and the effect of potential molecular mechanisms of Curcuma longa L. extracts on glioma using different network pharmacology analysis approaches.

METHODS

The components of Curcuma longa were extracted by gas chromatography-mass spectrometry (GC-MS), and the active components related to the occurrence and development of glioma were determined by traditional Chinese medicine systems pharmacology database and analysis platform (TCMSP) database, and the same targets of the active components and glioma were screened by network pharmacology approach. Then, the protein's function and regulatory pathway of the common targets were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The protein's action and regulatory pathway of the common targets were analyzed with the Cytoscape package using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database to construct the target interaction network through which the key targets were identified.

RESULTS

GC-MS combined with TCMSP database was used to identify the active components related to the occurrence and development of glioma in Curcuma longa. Finally, we identified the active components 1-(1,5-Dimethyl-4-hexenyl)-4-methyl benzene and Zingiberene. At the same time, 190 target genes of Curcuma longa extracts on glioma were obtained using the Venn diagram. The results of GO analysis showed that the biological processes involved included a response to stimulation, metabolic process, inflammatory process, cell differentiation, and regulation of biological processes. KEGG analysis showed that the PI3K-Akt signaling pathway, MAPK signaling pathway, Th17 cell differentiation, and proteoglycan pathway might be involved in cancer. Further analyses showed that the IL-17 signaling pathway and Interleukin-4 and interleukin-13 signaling were involved in the inflammatory pathway. The analysis of key nodes showed that GSK3B, MAPK14, HSP90AA1, MAPK3 and MAPK8 were IL-17 signaling pathways, while HIF1A and JAK3 were Interleukin-4 and interleukin-13 signaling pathways.

CONCLUSION

Curcuma longa extracts can regulate the occurrence and development of glioma by regulating the immune-inflammatory responses.

Effect of curcumin on the non-alcoholic steatohepatitis via inhibiting the M1 polarization of macrophages

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a global medical problem and macrophages' activation is closely related to the pathogenesis of NASH. Curcumin is a polyphenol from turmeric with significant anti-inflammatory activity.

OBJECTIVE

The objective of present study was to observe the effect of curcumin on macrophages' activation and secretion of pro-inflammatory cytokines in NASH.

METHODS

Hematoxylin and eosin and TUNEL staining were used to observe the hepatic function. RT-PCR was conducted to evaluate the hepatic mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Flow cytometry was adopted to detect the M1 polarization of macrophages. The RAW264.7 macrophage was pretreated with different doses of curcumin, and then lipopolysaccharide (LPS) and interferon-γ (IFN-γ) were given to activate the M1 macrophage. The activation ratio of M1 macrophage was observed by flow cytometry, and IL-1β and TNF-α expression was detected by RT-PCR and ELISA.

RESULTS

After treatment with curcumin, the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the mRNA expression of TNF-α and IL-1β, and M1 polarization of macrophages were significantly decreased. Hematoxylin and eosin and TUNEL staining showed that inflammation and apoptosis in the liver were improved. What is more, curcumin can effectively inhibit M1 macrophage activation induced by lipopolysaccharide and IFN-γ and reduce the secretion of IL-1β and TNF-α.

CONCLUSION

Curcumin can effectively improve NASH and reduce hepatic cell necrosis by inhibiting the M1 polarization of macrophages and the secretion of inflammatory factors.

Covid 19: Diet Composition and Health

The virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the disease coronavirus disease 2019 (COVID-19). The cumulative number of cases reported globally is now nearly 197 million and the number of cumulative deaths is 4.2 million (26 July to 1 August 2021). Currently we are focusing primarily on keeping a safe distance from others, washing our hands, and wearing masks, and the question of the effects of diet and diet-dependent risk factors remains outside the center of attention. Nevertheless, numerous studies indicate that diet can play an important role in the course of COVID-19. In this paper, based on select scientific reports, we discuss the structure and replication cycle of SARS-CoV-2, risk factors, dietary standards for sick patients, and the roles of the microbiome and dietary components supporting the immune system in preventing COVID-19.

The Role of Curcumin in Cancer Treatment

Curcumin is a polyphenol extracted from the rhizomes of the turmeric plant, Curcuma longa which has anti-inflammatory, and anticancer properties. Chronic inflammation is associated with the development of cancer. Curcumin acts on the regulation of various immune modulators, including cytokines, cyclooxygenase-2 (COX-2), and reactive oxygen species (ROS), which partly explains its anticancer effects. It also takes part in the downregulation of growth factors, protein kinases, oncogenic molecules and various signaling pathways, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), c-Jun N-terminal kinase (JNK) and signal transducer and activator of transcription 3 (STAT3) signaling. Clinical trials of curcumin have been completed or are ongoing for various types of cancer. This review presents the molecular mechanisms of curcumin in different types of cancer and the evidence from the most recent clinical trials.

Promise of the NLRP3 Inflammasome Inhibitors in In Vivo Disease Models

Nucleotide-binding oligomerization domain NOD-like receptors (NLRs) are conserved cytosolic pattern recognition receptors (PRRs) that track the intracellular milieu for the existence of infection, disease-causing microbes, as well as metabolic distresses. The NLRP3 inflammasome agglomerates are consequent to sensing a wide spectrum of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Certain members of the NLR family have been documented to lump into multimolecular conglomerates called inflammasomes, which are inherently linked to stimulation of the cysteine protease caspase-1. Following activation, caspase-1 severs the proinflammatory cytokines interleukin (IL)-1β and IL-18 to their biologically active forms, with consequent commencement of caspase-1-associated pyroptosis. This type of cell death by pyroptosis epitomizes a leading pathway of inflammation. Accumulating scientific documentation has recorded overstimulation of NLRP3 (NOD-like receptor protein 3) inflammasome involvement in a wide array of inflammatory conditions. IL-1β is an archetypic inflammatory cytokine implicated in multiple types of inflammatory maladies. Approaches to impede IL-1β's actions are possible, and their therapeutic effects have been clinically demonstrated; nevertheless, such strategies are associated with certain constraints. For instance, treatments that focus on systemically negating IL-1β (i.e., anakinra, rilonacept, and canakinumab) have been reported to result in an escalated peril of infections. Therefore, given the therapeutic promise of an NLRP3 inhibitor, the concerted escalated venture of the scientific sorority in the advancement of small molecules focusing on direct NLRP3 inflammasome inhibition is quite predictable.

Atherosclerosis: immunopathogenesis and strategies for immunotherapy

Atherosclerosis, a chronic inflammatory condition in which atheroma accumulates within the intima of the arterial wall, is a life-threatening manifestation of cardiovascular disease, due to atheroma rupture, chronic luminal narrowing and thrombosis. Current knowledge of the role of a protective immune response in atherosclerotic lesions has provided promising opportunities to develop new immunotherapeutic strategies. In particular, Tregs exert an atheroprotective role by releasing anti-inflammatory cytokines (IL-10/TGF-β) and suppressing autoreactive T lymphocytes. In vivo animal experiments have shown that this can be achieved by developing vaccines that stimulate immunological tolerance to atheroma antigens. Here, we present an overview of the current knowledge of the proatherogenic immune response, and we discuss the strategies currently used as immunoregulatory therapy.

Mechanistic Insight into the Effects of Curcumin on Neuroinflammation-Driven Chronic Pain

Chronic pain is a persistent and unremitting condition that has immense effects on patients' quality of life. Studies have shown that neuroinflammation is associated with the induction and progression of chronic pain. The activation of microglia and astrocytes is the major hallmark of spinal neuroinflammation leading to neuronal excitability in the projection neurons. Excessive activation of microglia and astrocytes is one of the major contributing factors to the exacerbation of pain. However, the current chronic pain treatments, mainly by targeting the neuronal cells, remain ineffective and unable to meet the patients' needs. Curcumin, a natural plant product found in the Curcuma genus, improves chronic pain by diminishing the release of inflammatory mediators from the spinal glia. This review details the role of curcumin in microglia and astrocytes both in vitro and in vivo and how it improves pain. We also describe the mechanism of curcumin by highlighting the major glia-mediated cascades in pain. Moreover, the role of curcumin on inflammasome and epigenetic regulation is discussed. Furthermore, we discuss the strategies used to improve the efficacy of curcumin. This review illustrates that curcumin modulating microglia and astrocytes could assure the treatment of chronic pain by suppressing spinal neuroinflammation.

Thioredoxin-interacting protein (TXNIP) as a target for Alzheimer's disease: flavonoids and phenols

Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloid plaques and tangles that have become the fifth leading cause of death worldwide. Previous studies have found that thioredoxin interacting protein (TXNIP) expression was increased during the development of AD neurons. TXNIP separates from the TXNIP-thioredoxin complex, and the TXNIP-NLRP3 complex assembles ASC and pro-caspase-1 to form the NLRP3 inflammasome, which triggers AD inflammation and apoptosis. CB-dock was used to explore whether 21 natural flavonoids and phenols target TXNIP based on references. Docking results showed that rutin, puerarin, baicalin, luteolin and quercetin are the most potent TXNIP inhibitors, and among them, rutin as the most effective flavonoid. And rosmarinic acid is the most potent TXNIP inhibitor of phenols. These phytochemicals could be helpful to find the lead compounds in designing and developing novel agents for Alzheimer's disease.

Curcumin Modulates Nitrosative Stress, Inflammation, and DNA Damage and Protects against Ochratoxin A-Induced Hepatotoxicity and Nephrotoxicity in Rats

Ochratoxin A (OTA) is a fungal toxin of critical concern for food safety both for human health and several animal species, also representing a cancer threat to humans. Curcumin (CURC) is a natural polyphenol that has anti-apoptotic, anti-inflammatory, and antioxidant effects. The aim of this study was to investigate the cytoprotective effect of CURC against OTA-induced nephrotoxicity and hepatotoxicity through the study of the nitrosative stress, pro-inflammatory cytokines, and deoxyribonucleic acid (DNA) damage. Sprague Dawley rats were daily treated with CURC (100 mg/kg b.w.), OTA (0.5 mg/kg b.w), or CURC with OTA by oral gavage for 14 days. Our results demonstrated that OTA exposure was associated with significant increase of pro-inflammatory and DNA oxidative-damage biomarkers. Moreover, OTA induced the inducible nitric oxide synthase, (iNOS) resulting in increased nitric oxide (NO) levels both in kidney and liver. The co-treatment OTA + CURC counteracted the harmful effects of chronic OTA treatment by regulating inflammation, reducing NO levels and oxidative DNA damage in kidney and liver tissues. Histology revealed that OTA + CURC treatment determinates mainly an Iba1+ macrophagic infiltration with fewer CD3+ T-lymphocytes in the tissues. In conclusion, we evidenced that CURC exerted cytoprotective and antioxidant activities against OTA-induced toxicity in rats.

Effectiveness of Two Plant-Based In-Feed Additives against an Escherichia coli F4 Oral Challenge in Weaned Piglets

This study evaluates the efficacy of two plant-based feed supplementations to fight colibacillosis in weanlings. A total of 96 piglets (32 pens) were assigned to four diets: a control diet (T1) or supplemented with ZnO (2500 ppm Zn) (T2) or two different plant supplements, T3 (1 kg/t; based on essential oils) and T4 (T3 + 1.5 kg/t based on non-volatile compounds). After one week, animals were challenged with ETEC F4, and 8 days after, one animal per pen was euthanized. Performance, clinical signs, microbial analysis, inflammatory response, intestinal morphology, and ileal gene expression were assessed. ZnO improved daily gains 4 days after challenge, T3 and T4 showing intermediate values (96, 249, 170, and 157 g/d for T1, T2, T3, and T4, p = 0.035). Fecal lactobacilli were higher with T3 and T4 compared to ZnO (7.55, 6.26, 8.71, and 8.27 cfu/gFM; p = 0.0007) and T3 increased the lactobacilli/coliforms ratio (p = 0.002). T4 was associated with lower levels of Pig-MAP (p = 0.07) and increases in villus/crypt ratio (1.49, 1.90, 1.73, and 1.84; p = 0.009). Moreover, T4 was associated with an upregulation of the REG3G gene (p = 0.013; p_FDR = 0.228) involved in the immune response induced by enteric pathogens. In conclusion, both plant supplements enhanced animal response in front of an ETEC F4 challenge probably based on different modes of action.

A Systematic Review Assessing Clinical Utility of Curcumin with a Focus on Cancer Prevention

SCOPE

There is extensive pre-clinical evidence for utility of curcuminoids across many diseases with a particular focus on cancer prevention, yet there remains a paucity of clinical evidence for its approved use. To assess current knowledge on the broader potential for clinical efficacy of curcumin and in particular, in cancer prevention strategies, this study undertook a systematic review determining the number and quality of randomized controlled trials (RCTs) undertaken across any pathology.

METHODS AND RESULTS

Search strategies for RCTs using a quantifiable amount of curcuminoids, are applied across Medline (Medical Literature Analysis and Retrieval System Online), Embase (Excerpta Medica dataBASE), Cochrane and clinicaltrials.gov. There are 314 curcuminoid-based RCTs, with 100 of these revealing significant within- and between-group changes relating to the primary outcome. Twenty three studies are conducted in a setting where there is an increased risk of cancer. Fifteen of these meet all prescribed quality criteria, and 10 reveal positive outcomes.

CONCLUSIONS

A substantial number of studies reveal positive outcomes following curcumin use. However, despite the vast array of preclinical data, there are relatively few RCTs conducted in the prevention setting. Future approaches to trials must deliver improved robustness and credibility of curcumin-related research to facilitate approvals for use in clinical settings.

Protective effects of curcumin on chemical and drug-induced cardiotoxicity: a review

Cardiotoxicity is a major adverse effect that can be induced by both therapeutic agents and industrial chemicals. The pathogenesis of such cardiac damage is multifactorial, often injuring the cardiac tissue by generating free radicals, oxidative stress, and/or inflammation. Curcumin (CUR) is a bright yellow chemical produced by Curcuma longa plants. It is the principal curcuminoid of turmeric (Curcuma longa), a member of the ginger family, Zingiberaceae. Administration of CUR has been reported to ameliorate the chemical and drug-induced cardiac injury in several studies. CUR has been suggested to act as an effective candidate against oxidative stress and inflammation in heart tissue via regulation of Nrf2 and suppression of p38 MAPK/NF-κB and NLRP3 inflammasomes. The anti-apoptotic properties of CUR have also been reported to modulate the AMPK, Akt, JNK, and ERK signaling pathways. This review explores the potential protective effects of CUR regarding the detrimental effects often observed in cardiac tissue following exposure to several chemicals including drugs.

Curcumin Alleviates Cerebral Ischemia-reperfusion Injury by Inhibiting NLRP1-dependent Neuronal Pyroptosis

BACKGROUND

Cerebral ischemia-reperfusion injury is caused by a blood reperfusion injury in the ischemic brain and usually occurs in the treatment stage of ischemic disease, which can aggravate brain tissue injury.

OBJECTIVE

Curcumin was reported to exert a good therapeutic effect on neural cells against ischemia-reperfusion injury, while the mechanism was unclear.

METHODS

In this study, oxygen glucose deprivation (OGD) model of fetal rat cerebral cortical neurons and the middle cerebral artery occlusion (MCAO) model of rats were employed to mimic cerebral ischemia-reperfusion injury in vitro and in vivo，respectively.

RESULTS

We confirmed that curcumin has a promotive effect on neuronal proliferation and an inhibitory effect on neuronal pyroptosis. Furthermore, we found that curcumin could improve cerebral infarction. The results of western blotting showed that curcumin down-regulated the expression of nucleotide-binding oligomerization domain-containing protein-, leucine-rich repeats-, and pyrin domain-containing protein 1 (NLRP1), cysteinyl aspartate-specific protease 1 (caspase-1), gasdermin D (GSDMD), IL-1β, IL-6, TNF-α, and iNOS proteins in OGD and MCAO models. NLRP1-dependent neuronal pyroptosis played an important role in cerebral ischemia-reperfusion injury.

CONCLUSION

Curcumin could effectively inhibit NLRP1-dependent neuronal pyroptosis by suppressing the p38 MAPK pathway and therefore exerted neuroprotective effects against cerebral ischemia-reperfusion injury.

Therapeutic effect of modulating the NLRP3-regulated transforming growth factor-β signaling pathway on interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a disorder with complex pathogenesis and lacks effective treatment. Chronic inflammation is the main pathogenesis of Hunner-type IC/BPS. The NLR family pyrin domain-containing 3 (NLRP3) inflammasome-related transforming growth factor-β (TGF-β)/Smad signaling pathway plays a crucial role in inflammation-related tissue fibrosis. Lipopolysaccharide (LPS) and protamine sulfate (LPS/PS) were instilled into the mouse bladder twice a week for 5 consecutive weeks to establish a chronic inflammation-induced IC/BPS model (LPS/PS model). Following LPS/PS treatment, curcumin (oral, 100 mg/kg; a potent NLRP3 modulator) was administered for 2 weeks in the curcumin treatment group, and normal saline was used for the sham group. Bladder function was evaluated by performing the voiding spot assay and examining the status of urothelial denudation and fibrosis in bladder tissues. The expression of NLRP3 inflammasome, interleukin-1β, TGF-β, Smad, vimentin, and E-cadherin in bladder tissues was evaluated through immunohistochemistry staining. Results revealed that the repeated instillation of LPS/PS leads to voiding dysfunction, bladder urothelium denudation, and detrusor muscle fibrosis through the upregulation of the NLRP3 inflammasome/IL-1β-related TGF-β/Smad pathway and the increased epithelial-mesenchymal transition process in bladder tissues. The downregulation of the NLRP3 inflammasome/IL-1β-related TGF-β/Smad pathway in bladder tissues through curcumin effectively mitigated bladder injury in the LPS/PS model. In conclusion, the NLRP3 inflammasome/IL-1β-related TGF-β/Smad pathway plays a crucial role in bladder injury in the LPS/PS model, and modulation of this pathway, such as by using curcumin, can effectively mitigate the sequelae of chronic inflammation-induced IC/BPS.

Relevant mediators involved in and therapies targeting the inflammatory response induced by activation of the NLRP3 inflammasome in ischemic stroke

The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is a member of the NLR family of inherent immune cell sensors. The NLRP3 inflammasome can detect tissue damage and pathogen invasion through innate immune cell sensor components commonly known as pattern recognition receptors (PRRs). PRRs promote activation of nuclear factor kappa B (NF-κB) pathways and the mitogen-activated protein kinase (MAPK) pathway, thus increasing the transcription of genes encoding proteins related to the NLRP3 inflammasome. The NLRP3 inflammasome is a complex with multiple components, including an NAIP, CIITA, HET-E, and TP1 (NACHT) domain; apoptosis-associated speck-like protein containing a CARD (ASC); and a leucine-rich repeat (LRR) domain. After ischemic stroke, the NLRP3 inflammasome can produce numerous proinflammatory cytokines, mediating nerve cell dysfunction and brain edema and ultimately leading to nerve cell death once activated. Ischemic stroke is a disease with high rates of mortality and disability worldwide and is being observed in increasingly younger populations. To date, there are no clearly effective therapeutic strategies for the clinical treatment of ischemic stroke. Understanding the NLRP3 inflammasome may provide novel ideas and approaches because targeting of upstream and downstream molecules in the NLRP3 pathway shows promise for ischemic stroke therapy. In this manuscript, we summarize the existing evidence regarding the composition and activation of the NLRP3 inflammasome, the molecules involved in inflammatory pathways, and corresponding drugs or molecules that exert effects after cerebral ischemia. This evidence may provide possible targets or new strategies for ischemic stroke therapy.

Natural products and analogs as preventive agents for metabolic syndrome via peroxisome proliferator-activated receptors: An overview

Natural products and synthetic analogs have drawn much attention as potential therapeutical drugs to treat metabolic syndrome. We reviewed the underlying mechanisms of 32 natural products and analogs with potential pharmacological effects in vitro, and especially in rodent models and/or patients, that usually act on the PPAR pathway, along with other molecular targets. Recent outstanding total syntheses or semisyntheses of these lead compounds are stated. In general, they can activate the transcriptional activity of PPARα, PPARγ, PPARα/γ, PPARβ/δ, PPARα/δ, PPARγ/δ and panPPAR as weak, partial agonists or selective PPARγ modulators (SPPARγM), which may be useful for managing obesity, type 2 diabetes (T2D), dyslipidemia and non-fatty liver disease (NAFLD). Terpenoids is the largest group of compounds that act as potential modulators on PPARs and are comprised from small lipophilic cannabinoids to lipophilic pentacyclic triterpenes and polar saponins. Shikimates-phenylpropanoids include polar heterocyclic flavonoids and phenolic compounds containing at least one C3-C6 unit and usually a double bond on the propyl chain. Quercetin (19), resveratrol (24) and curcumin (27), stand out from this group for exhibiting beneficial effects on patients. Alkaloids, the minor group of potential modulators on PPARs, include berberine (30), which has been widely explored in preclinical and clinical studies for its potential beneficial effects on T2D and dyslipidemia. However, large-scale clinical trials may be warranted for the promising compounds.

Curcumin as a Potential Treatment for COVID-19

Coronavirus disease 2019 (COVID-19) is an infectious disease that rapidly spread throughout the world leading to high mortality rates. Despite the knowledge of previous diseases caused by viruses of the same family, such as MERS and SARS-CoV, management and treatment of patients with COVID-19 is a challenge. One of the best strategies around the world to help combat the COVID-19 has been directed to drug repositioning; however, these drugs are not specific to this new virus. Additionally, the pathophysiology of COVID-19 is highly heterogeneous, and the way of SARS-CoV-2 modulates the different systems in the host remains unidentified, despite recent discoveries. This complex and multifactorial response requires a comprehensive therapeutic approach, enabling the integration and refinement of therapeutic responses of a given single compound that has several action potentials. In this context, natural compounds, such as Curcumin, have shown beneficial effects on the progression of inflammatory diseases due to its numerous action mechanisms: antiviral, anti-inflammatory, anticoagulant, antiplatelet, and cytoprotective. These and many other effects of curcumin make it a promising target in the adjuvant treatment of COVID-19. Hence, the purpose of this review is to specifically point out how curcumin could interfere at different times/points during the infection caused by SARS-CoV-2, providing a substantial contribution of curcumin as a new adjuvant therapy for the treatment of COVID-19.

Xi Lei San Attenuates Dextran Sulfate Sodium-Induced Colitis in Rats and TNF-α-Stimulated Colitis in CACO2 Cells: Involvement of the NLRP3 Inflammasome and Autophagy

Objective

Inflammatory bowel disease (IBD) is a chronic nonspecific inflammatory bowel disease with an unclear etiology. The active ingredients of traditional Chinese medicines (TCMs) exert anti-inflammatory, antitumor, and immunomodulatory effects, and their multitarget characteristics provide them with a unique advantage for treating IBD. However, the therapeutic effects and underlying mechanisms of Xi Lei San in treatment of IBD remain unknown. This study was designed to investigate whether Xi Lei San exerted an anti-inflammatory effect in IBD via a mechanism involving NLRP3 inflammasomes and autophagy.

Methods

We successfully established a rat model of dextran sulfate sodium- (DSS-) induced colitis as well as a cellular model of TNF-α-induced colitis. Xi Lei San and indirubin were identified by HPLC analysis. Rats were treated with Xi Lei San or alum crystals, and their body weights and morphology of intestinal tissues were examined. A western blot analysis was performed to determine the expression levels of inflammasome-related proteins and autophagy-related proteins, ELISA was performed to analyze IL-1β, IL-18, and IL-33 concentrations, and flow cytometry was used to monitor cell apoptosis and ROS levels.

Results

Xi Lei San and indirubin were identified by HPLC analysis. We found that Xi Lei San could significantly increase the weights of rats and improve the structure of the intestinal tissues in DSS-induced colitis model rats. We also found that Xi Lei San significantly inhibited NLRP3 inflammasome activity, reduced the levels of inflammatory cytokines, and suppressed autophagy in DSS-induced colitis model rats. In vitro experiments revealed that Xi Lei San could repress apoptosis as well as ROS and inflammatory cytokine production in TNF-α-induced CACO2 cells by reducing the activity of NLRP3 inflammasomes and autophagy.

Conclusions

Our findings showed that Xi Lei San significantly ameliorated IBD by inhibiting NLRP3 inflammasome, autophagy, and oxidative stress.

In vitro effects of curcumin on proinflammatory cytokines and expression of their genes in minor salivary gland tissue of patients with Sjogren's syndrome

Curcumin reduces disease severity and ameliorates lupus-like/Sjögren's Syndrome-like disease in mice model. The immunological basis of these effects is largely unknown. This study examined the effects of curcumin on pro-inflammatory cytokines secreted by minor salivary glands in patients with primary Sjögren's syndrome (pSS). Minor salivary gland (MSG) tissue samples were collected from patients undergoing biopsy for suspected pSS. The tissues were treated with phytohemagglutinin (PHA) alone as well as PHA with curcumin (30 μM) and cultured in RPMI 1640 medium for 48 h at 37 °C in CO₂ incubator. After the incubation period, culture supernatant and tissues were stored in the freezer (-80 °C). IL-6 levels were measured in supernatant by ELISA kit. Gene expressions of pro-inflammatory cytokines, namely IL-6, IL-8, TNF-α, IL-1β, IL-4, IL-10, IL-17, IL-21, and IFN-γ, were measured by qPCR. IL-6 secretion levels and gene expressions were compared statistically between groups by Student's t test. Forty-seven patients were screened. Eight patients satisfied ACR/EULAR criteria for pSS. Seven patients with absent glandular inflammation and negative serology constituted sicca controls. These 15 subjects were included in final analysis. In pSS group, but not in controls, median IL-6 levels in supernatant were less in curcumin-treated as compared to PHA-alone subset [5.5 (0.7-13.34) vs 18.3 (12-32) ng/ml; p = 0.0156]. mRNA expression levels of IL-6 were also lower in curcumin-treated samples as compared to PHA alone, when cases and controls were analyzed together as well as in cases alone (p = 0.0009 and p = 0.0078, respectively); however, mRNA expression of IL-1β was lower in curcumin-treated samples as compared to PHA alone, only when cases and controls were analyzed together (p = 0.0215). There was no difference in other cytokine gene expression levels between the subsets under the in-vitro experimental conditions. In conclusion, curcumin reduced mRNA expression as well as secretion of IL-6 levels by salivary gland tissue of patients with pSS. Curcumin also suppressed PHA-induced mRNA expression levels of IL-6 and IL-1β in MSG tissue of patients with pSS and controls when analyzed together as a combined group.

Medicinal plants and bioactive natural products as inhibitors of NLRP3 inflammasome

The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome is a multiprotein complex that induces caspase-1 activation and the downstream substrates involved with the processing and secretion of the pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18 and tumor necrosis factor-α (TNF- α). The NLRP3 inflammasome is activated by a wide range of danger signals that derive from metabolic dysregulation. Activation of this complex often involves the adaptor ASC and upstream sensors including NLRP1, NLRP3, NLRC4, AIM2, and pyrin, which are activated by different stimuli including infectious agents and changes in cell homeostasis. It has been shown that nutraceuticals and medicinal plants have antiinflammatory properties and could be used as complementary therapy in the treatment of several chronic diseases that are related to inflammation, for example, cardiovascular diseases and diabetes mellitus. Herb-based medicine has demonstrated protective effects against NLRP3 inflammasome activation. Therefore, this review focuses on the effects of nutraceuticals and bioactive compounds derived from medicinal plants on NLRP3 inflammasome activation and the possible mechanisms of action of these natural products. Thus, herb-based, natural products/compounds can be considered novel, practical, and accessible agents in chronic inflammatory diseases by inhibiting NLRP3 inflammasome activation.

1'-Acetoxychavicol acetate inhibits NLRP3-dependent inflammasome activation via mitochondrial ROS suppression

The nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing (NLRP) 3 inflammasome is a multiprotein complex that triggers Caspase-1-mediated IL-1β production and pyroptosis, and its dysregulation is associated with the pathogenesis of inflammatory diseases. 1'-Acetoxychavicol acetate (ACA) is a natural compound in the rhizome of tropical ginger Alpinia species with anti-microbial, anti-allergic and anti-cancer properties. In this study, we found that ACA suppressed NLRP3 inflammasome activation in mouse bone marrow-derived macrophages and human THP-1 monocytes. ACA inhibited Caspase-1 activation and IL-1β production by NLRP3 agonists such as nigericin, monosodium urate (MSU) crystals, and ATP. Moreover, it suppressed oligomerization of the adapter molecule, apoptosis-associated speck-like protein containing a CARD (ASC), and Caspase-1-mediated cleavage of pyroptosis executor Gasdermin D. Mechanistically, ACA inhibited generation of mitochondrial reactive oxygen species (ROS) and prevented release of oxidized mitochondrial DNA, which trigger NLRP3 inflammasome activation. ACA also prevented NLRP3 inflammasome activation in vivo, as evidenced in the MSU crystal-induced peritonitis and dextran sodium sulfate-induced colitis mouse models accompanied by decreased Caspase-1 activation. Thus, ACA is a potent inhibitor of the NLRP3 inflammasome for prevention of NLRP3-associated inflammatory diseases.

The Immunomodulatory and Anti-Inflammatory Effect of Curcumin on Immune Cell Populations, Cytokines, and In Vivo Models of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a widespread chronic autoimmune disorder affecting the joints, causing irreversible cartilage, synovium, and bone degradation. During the course of the disease, many immune and joint cells are activated, causing inflammation. Immune cells including macrophages, lymphocytes, neutrophils, mast cells, natural killer cells, innate lymphoid cells, as well as synovial tissue cells, like fibroblast-like synoviocytes, chondrocytes, and osteoclasts secrete different proinflammatory factors, including many cytokines, angiogenesis-stimulating molecules and others. Recent studies reveal that curcumin, a natural dietary anti-inflammatory compound, can modulate the response of the cells engaging in RA course. This review comprises detailed data about the pathogenesis and inflammation process in rheumatoid arthritis and demonstrates scientific investigations about the molecular interactions between curcumin and immune cells responsible for rheumatoid arthritis development to discuss this herbal drug’s immunoregulatory role in RA treatment.

Curcumin analogue AI-44 alleviates MSU-induced gouty arthritis in mice via inhibiting cathepsin B-mediated NLRP3 inflammasome activation

NOD-like receptors (NLRs), as a part of intracellular pattern recognition receptors (PRR), are important regulators in innate immune system. The NLRP3 inflammasome which is a member of NLRs has been linked to several human inflammatory diseases. Gouty arthritis is triggered when the deposition of monosodium urate (MSU) crystals in joints induces acute inflammation characterized by the recruitment of macrophages and neutrophils. In this study, we explored the curcumin analogue AI-44 alleviated the gouty arthritis in mice via suppressing MSU engaging NLRP3 inflammasome activation. Furthermore, we demonstrated that AI-44 inhibited the interaction of cathepsin B and NLRP3 to prevent the activation of NLRP3 inflammasome. Moreover, we found AI-44 inhibited the enzyme activity of cathepsin B and bound to the key residue E122 in cytoplasm but not in lysosome. Collectively, these data suggest that AI-44 is a novel drug candidate for the treatment of gouty arthritis through targeting cathepsin B and inhibiting NLRP3 inflammasome activation.

Obesity-Associated Inflammation: Does Curcumin Exert a Beneficial Role?

Curcumin is a lipophilic polyphenol, isolated from the plant turmeric of Curcuma longa. Curcuma longa has always been used in traditional medicine in Asian countries because it is believed to have numerous health benefits. Nowadays it is widely used as spice component and in emerging nutraceutical food worldwide. Numerous studies have shown that curcumin possesses, among others, potential anti-inflammatory properties. Obesity represents a main risk factor for several chronic diseases, including type 2 diabetes, cardiovascular disease, and some types of cancer. The establishment of a low-grade chronic inflammation, both systemically and locally in adipose tissue, occurring in obesity most likely represents a main factor in the pathogenesis of chronic diseases. The molecular mechanisms responsible for the onset of the obesity-associated inflammation are different from those involved in the classic inflammatory response caused by infections and involves different signaling pathways. The inflammatory process in obese people is triggered by an inadequate intake of nutrients that produces quantitative and qualitative alterations of adipose tissue lipid content, as well as of various molecules that act as endogenous ligands to activate immune cells. In particular, dysfunctional adipocytes secrete inflammatory cytokines and chemokines, the adipocytokines, able to recruit immune cells into adipose tissue, amplifying the inflammatory response also at systemic level. This review summarizes the most recent studies focused at elucidating the molecular targets of curcumin activity responsible for its anti-inflammatory properties in obesity-associated inflammation and related pathologies.

Dynamic roles of inflammasomes in inflammatory tumor microenvironment

The inflammatory tumor microenvironment has been known to be closely connected to all stages of cancer development, including initiation, promotion, and progression. Systemic inflammation in the tumor microenvironment is increasingly being recognized as an important prognostic marker in cancer patients. Inflammasomes are master regulators in the first line of host defense for the initiation of innate immune responses. Inflammasomes sense pathogen-associated molecular patterns and damage-associated molecular patterns, following recruitment of immune cells into infection sites. Therefore, dysregulated expression/activation of inflammasomes is implicated in pathogenesis of diverse inflammatory disorders. Recent studies have demonstrated that inflammasomes play a vital role in regulating the development and progression of cancer. This review focuses on fate-determining roles of the inflammasomes and the principal downstream effector cytokine, IL-1β, in the tumor microenvironment.

A targeted polypeptide-based nanoconjugate as a nanotherapeutic for alcohol-induced neuroinflammation

Alcohol abuse induces the expression of inflammatory mediators by activating the immune receptors to trigger neuroinflammation and brain damage; however, therapies that reduce neuroimmune system activation may protect against alcohol's damaging effects. Curcuminoids possess anti-inflammatory properties but suffer from low bioavailability; therefore, we designed a new receptor-targeted biodegradable star-shaped crosslinked polypeptide polymer that bears propargylamine moieties and bisdemethoxycurcumin (StClPr-BDMC-ANG) as an enhanced anti-inflammatory therapeutic that penetrates the blood-brain-barrier and ameliorates alcohol-induced neuroinflammation. StClPr-BDMC-ANG administration maintains the viability of primary glia and inhibits the ethanol-induced upregulation of crucial inflammatory mediators in the prefrontal and medial cortex in a mouse model of chronic ethanol consumption. StClPr-BDMC-ANG treatment also suppresses the ethanol-mediated downregulation of microRNAs known to negatively modulate neuroinflammation in the brain cortex (miRs 146a-5p and let-7b-5p). In summary, our results demonstrate the attenuation of alcohol-induced neuroinflammation by an optimized and targeted polypeptide-based nanoconjugate of a curcuminoid.

β-Glucan-induced reprogramming of human macrophages inhibits NLRP3 inflammasome activation in cryopyrinopathies

Exposure of mononuclear phagocytes to β-glucan, a naturally occurring polysaccharide, contributes to the induction of innate immune memory, which is associated with long-term epigenetic, metabolic, and functional reprogramming. Although previous studies have shown that innate immune memory induced by β-glucan confers protection against secondary infections, its impact on autoinflammatory diseases, associated with inflammasome activation and IL-1β secretion, remains poorly understood. In particular, whether β-glucan-induced long-term reprogramming affects inflammasome activation in human macrophages in the context of these diseases has not been explored. We found that NLRP3 inflammasome-mediated caspase-1 activation and subsequent IL-1β production were reduced in β-glucan-reprogrammed macrophages. β-Glucan acted upstream of the NLRP3 inflammasome by preventing potassium (K+) efflux, mitochondrial ROS (mtROS) generation, and, ultimately, apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization and speck formation. Importantly, β-glucan-induced memory in macrophages resulted in a remarkable attenuation of IL-1β secretion and caspase-1 activation in patients with an NLRP3-associated autoinflammatory disease, cryopyrin-associated periodic syndromes (CAPS). Our findings demonstrate that β-glucan-induced innate immune memory represses IL-1β-mediated inflammation and support its potential clinical use in NLRP3-driven diseases.

Antiviral and immunomodulatory activity of curcumin: A case for prophylactic therapy for COVID-19

Coronavirus disease-19 (COVID-19), a devastating respiratory illness caused by SARS-associated coronavirus-2 (SARS-CoV-2), has already affected over 64 million people and caused 1.48 million deaths, just 12 months from the first diagnosis. COVID-19 patients develop serious complications, including severe pneumonia, acute respiratory distress syndrome (ARDS), and or multiorgan failure due to exaggerated host immune response following infection. Currently, drugs that were effective against SARS-CoV are being repurposed for SARS-CoV-2. During this public health emergency, food nutraceuticals could be promising prophylactic therapeutics for COVID-19. Curcumin, a bioactive compound in turmeric, exerts diverse pharmacological activities and is widely used in foods and traditional medicines. This review presents several lines of evidence, which suggest curcumin as a promising prophylactic, therapeutic candidate for COVID-19. First, curcumin exerts antiviral activity against many types of enveloped viruses, including SARS-CoV-2, by multiple mechanisms: direct interaction with viral membrane proteins; disruption of the viral envelope; inhibition of viral proteases; induce host antiviral responses. Second, curcumin protects from lethal pneumonia and ARDS via targeting NF-κB, inflammasome, IL-6 trans signal, and HMGB1 pathways. Third, curcumin is safe and well-tolerated in both healthy and diseased human subjects. In conclusion, accumulated evidence indicates that curcumin may be a potential prophylactic therapeutic for COVID-19 in the clinic and public health settings.

Epigallocatechin-3-gallate prevents inflammation and diabetes -Induced glucose tolerance through inhibition of NLRP3 inflammasome activation

Epigallocatechin-3-gallate (EGCG), the primary polyphenol component of green tea, has been shown to inhibit both oxidation and inflammation. However, the exact mechanism through which EGCG exhibits anti-inflammatory effects remains unclear. In this study, we assessed the potential pathways by which EGCG regulates NLRP3 inflammasome activity in vitro. We found that EGCG inhibits caspase-1 activation and IL-1β secretion by suppressing NLRP3 inflammasome activation in mouse bone marrow-derived macrophages (BMDMs). EGCG was also observed to block NLRP3-mediated ASC speckle formation and to alleviate pyroptosis in BMDMs. In addition, EGCG treatment could improve high-fat diet (HFD)-induced glucose tolerance and prevent NLRP3 inflammasome-dependent inflammation in a mouse model of HFD-induced type 2 diabetes (T2D). Taken together, our results show that EGCG is a general inhibitor of NLRP3 inflammasome activation and administration of EGCG in T2D mice could improve glucose tolerance in vivo.

Mycoplasma pneumoniae Infections: Pathogenesis and Vaccine Development

Mycoplasma pneumoniae is a major causative agent of community-acquired pneumonia which can lead to both acute upper and lower respiratory tract inflammation, and extrapulmonary syndromes. Refractory pneumonia caused by M. pneumonia can be life-threatening, especially in infants and the elderly. Here, based on a comprehensive review of the scientific literature related to the respective area, we summarize the virulence factors of M. pneumoniae and the major pathogenic mechanisms mediated by the pathogen: adhesion to host cells, direct cytotoxicity against host cells, inflammatory response-induced immune injury, and immune evasion. The increasing rate of macrolide-resistant strains and the harmful side effects of other sensitive antibiotics (e.g., respiratory quinolones and tetracyclines) in young children make it difficult to treat, and increase the health risk or re-infections. Hence, there is an urgent need for development of an effective vaccine to prevent M. pneumoniae infections in children. Various types of M. pneumoniae vaccines have been reported, including whole-cell vaccines (inactivated and live-attenuated vaccines), subunit vaccines (involving M. pneumoniae protein P1, protein P30, protein P116 and CARDS toxin) and DNA vaccines. This narrative review summarizes the key pathogenic mechanisms underlying M. pneumoniae infection and highlights the relevant vaccines that have been developed and their reported effectiveness.

Curcumin attenuates renal interstitial fibrosis by regulating autophagy and retaining mitochondrial function in unilateral ureteral obstruction rats

Renal interstitial fibrosis (RIF) is the leading cause of end-stage renal disease, partly because of the lack of effective treatments. Curcumin, the primary active ingredient in turmeric, reportedly exerts potent antifibrotic effects. This study investigated the effects of curcumin on RIF in unilateral ureteral obstruction (UUO) rats and characterized the underlying action mechanism. UUO rats were treated with curcumin for 7 and 14 d. Renal fibrosis was evaluated through haematoxylin-eosin staining, Masson staining, and type I and III collagen expression. Autophagy and mitochondria were observed through scanning electron microscopy. NLRP3 inflammasomes, mitochondria, and autophagy-related proteins were detected through Western blotting. Mitochondrial respiratory enzyme activity was assessed spectrophotometrically. Compared with UUO rats, renal fibrosis was attenuated and NLRP3 inflammasome activation was inhibited in curcumin-treated rats. Furthermore, mitochondrial dysfunction was ameliorated and the LC3B/LC3A ratio and Beclin-1 expression were increased in curcumin-treated rats. Additionally, curcumin inhibited the PI3K/AKT/mTOR pathway. These results indicate that curcumin is a promising treatment agent for RIF, and its antifibrotic effects may be mediated by the inhibition of NLRP3 inflammasome activity through the regulation of autophagy and protection of mitochondrial function in UUO rats.

Nutrition as Metabolic Treatment for Anxiety

Despite the overwhelming prevalence of anxiety disorders in modern society, medications and psychotherapy often fail to achieve complete symptom resolution. A complementary approach to medicating symptoms is to address the underlying metabolic pathologies associated with mental illnesses and anxiety. This may be achieved through nutritional interventions. In this perspectives piece, we highlight the roles of the microbiome and inflammation as influencers of anxiety. We further discuss the evidence base for six specific nutritional interventions: avoiding artificial sweeteners and gluten, including omega-3 fatty acids and turmeric in the diet, supplementation with vitamin D, and ketogenic diets. We attempt to integrate insights from the nutrition science-literature in order to highlight some practices that practitioners may consider when treating individual patients. Notably, this piece is not meant to serve as a comprehensive review of the literature, but rather argue our perspective that nutritional interventions should be more widely considered among clinical psychiatrists. Nutritional psychiatry is in its infancy and more research is needed in this burgeoning low-risk and potentially high-yield field.

Nutraceutical Strategies for Suppressing NLRP3 Inflammasome Activation: Pertinence to the Management of COVID-19 and Beyond

Inflammasomes are intracellular protein complexes that form in response to a variety of stress signals and that serve to catalyze the proteolytic conversion of pro-interleukin-1β and pro-interleukin-18 to active interleukin-1β and interleukin-18, central mediators of the inflammatory response; inflammasomes can also promote a type of cell death known as pyroptosis. The NLRP3 inflammasome has received the most study and plays an important pathogenic role in a vast range of pathologies associated with inflammation-including atherosclerosis, myocardial infarction, the complications of diabetes, neurological and autoimmune disorders, dry macular degeneration, gout, and the cytokine storm phase of COVID-19. A consideration of the molecular biology underlying inflammasome priming and activation enables the prediction that a range of nutraceuticals may have clinical potential for suppressing inflammasome activity-antioxidants including phycocyanobilin, phase 2 inducers, melatonin, and N-acetylcysteine, the AMPK activator berberine, glucosamine, zinc, and various nutraceuticals that support generation of hydrogen sulfide. Complex nutraceuticals or functional foods featuring a number of these agents may find utility in the prevention and control of a wide range of medical disorders.

Curcumin and inflammatory bowel diseases: From in vitro studies to clinical trials

Inflammatory bowel diseases (IBDs) may result from mutations in genes encoding for innate immunity, which can lead to exacerbated inflammatory response. Although some mono-targeted treatments have developed in recent years, IBDs are caused through several pathway perturbations. Therefore, targeting all these pathways is difficult to be achieved by a single agent. Moreover, those mono-targeted therapies are usually expensive and may cause side-effects. These limitations highlight the significance of an available, inexpensive and multi-targeted dietary agents or natural compounds for the treatment and prevention of IBDs. Curcumin is a multifunctional phenolic compound that is known for its anti-inflammatory and immunomodulatory properties. Over the past decades, mounting experimental investigations have revealed the therapeutic potential of curcumin against a broad spectrum of inflammatory diseases including IBDs. Furthermore, it has been reported that curcumin directly interacts with many signaling mediators implicated in the pathogenesis of IBDs. These preclinical findings have created a solid basis for the assessment of the efficacy of curcumin in clinical practice. In clinical trials, different dosages e.g., 550 mg /three times daily-1month, and 1 g /twice times daily-6month of curcumin were used for patients with IBDs. Taken together, these findings indicated that curcumin could be employed as a therapeutic candidate in the treatment of IBDs. Moreover, it seems that overcome to current limitations of curcumin i.e., poor oral bioavailability, and poor oral absorption with using nanotechnology and others, could improve the efficacy of curcumin both in pre-clinical and clinical studies.

Gallic Acid Alleviates Gouty Arthritis by Inhibiting NLRP3 Inflammasome Activation and Pyroptosis Through Enhancing Nrf2 Signaling

Gallic acid is an active phenolic acid widely distributed in plants, and there is compelling evidence to prove its anti-inflammatory effects. NLRP3 inflammasome dysregulation is closely linked to many inflammatory diseases. However, how gallic acid affects the NLRP3 inflammasome remains unclear. Therefore, in the present study, we investigated the mechanisms underlying the effects of gallic acid on the NLRP3 inflammasome and pyroptosis, as well as its effect on gouty arthritis in mice. The results showed that gallic acid inhibited lactate dehydrogenase (LDH) release and pyroptosis in lipopolysaccharide (LPS)-primed and ATP-, nigericin-, or monosodium urate (MSU) crystal-stimulated macrophages. Additionally, gallic acid blocked NLRP3 inflammasome activation and inhibited the subsequent activation of caspase-1 and secretion of IL-1β. Gallic acid exerted its inhibitory effect by blocking NLRP3-NEK7 interaction and ASC oligomerization, thereby limiting inflammasome assembly. Moreover, gallic acid promoted the expression of nuclear factor E2-related factor 2 (Nrf2) and reduced the production of mitochondrial ROS (mtROS). Importantly, the inhibitory effect of gallic acid could be reversed by treatment with the Nrf2 inhibitor ML385. NRF2 siRNA also abolished the inhibitory effect of gallic acid on IL-1β secretion. The results further showed that gallic acid could mitigate MSU-induced joint swelling and inhibit IL-1β and caspase 1 (p20) production in mice. Moreover, gallic acid could moderate MSU-induced macrophages and neutrophils migration into joint synovitis. In summary, we found that gallic acid suppresses ROS generation, thereby limiting NLRP3 inflammasome activation and pyroptosis dependent on Nrf2 signaling, suggesting that gallic acid possesses therapeutic potential for the treatment of gouty arthritis.

The effects of adipose tissue-derived stem cells seeded onto the curcumin-loaded collagen scaffold in healing of experimentally- induced oral mucosal ulcers in rat

OBJECTIVES

Various therapeutic approaches, including stem-cell-based strategies and tissue engineering, have been proposed for oral ulcerative lesions. We investigated the effects of adipose tissue-derived stem cells (ADSCs) seeded onto the curcumin-loaded collagen scaffold in the mucosal healing of oral ulcers in rats.

MATERIALS AND METHODS

The current experimental study was conducted on 40 male Sprague-Dawley rats. Oral ulcers were created over both sides of buccal mucosa, and the rats were randomly divided into four equal groups: 1) an untreated group (negative control); 2) Teriadent-treated group (positive control); 3) group treated with curcumin-loaded collagen scaffold; and 4) group received the ADSCs (3 × 106 cells) seeded onto the curcumin-loaded collagen scaffold. Rats were sacrificed on 3rd and 7th day after ulceration for histopathological examination as well as measurement of tissue levels of myeloperoxidase (MPO), superoxide dismutase (SOD), and Interleukin-1 beta (IL-1β) activity.

RESULTS

Compared with the negative control, the tissue levels of MPO and IL-1β were significantly decreased in all treated groups (P<0.0001); however, the SOD activity was elevated (P<0.0001). The highest SOD activity as well as the lowest MPO and IL-1β levels were observed in the ADSCs-curcumin-loaded collagen scaffold group. The ulcer healing process at 3rd and 7th day follow-up was much more progressed in the ADSCs-curcumin-loaded collagen scaffold group in comparison with the untreated group (P=0.037 and P=0.004, respectively).

CONCLUSION

According to the findings of this study, ADSCs seeded onto the curcumin-loaded collagen scaffold seems to have a promising potential for oral ulcer healing applications.

Flavonoids with Inhibitory Effects on NLRP3 Inflammasome Activation from Millettia velutina

Eight new flavonoids, including two β-hydroxy/methoxychalcones, velutones A and B (1 and 2), two 1,3-diarylpropan-1-ols, velutols C and D (3 and 4), a dihydroxychalcone, velutone E (5), a chalcone, velutone F (6), a furanoflavanone, velutone G (7), and a furanoflavonol, velutone H (8), and 14 known compounds were isolated from Millettia velutina. Their structures were determined by high-resolution electrospray ionisation mass spectrometry (HR-ESIMS) and spectroscopic data analyses and time-dependent density functional theory electronic circular dichroism (TD-DFT-ECD) calculations. Among the isolated constituents, compound 6 exhibited the most potent inhibitory effect (IC₅₀: 1.3 μM) against nigericin-induced IL-1β release in THP-1 cells. The initial mechanism of action study revealed that compound 6 suppressed NLRP3 inflammasome activation via blocking ASC oligomerization without affecting the priming step, which subsequently inhibited caspase-1 activation and IL-1β secretion. Most importantly, compound 6 exerted potent protective effects in the LPS-induced septic shock mice model by improving the survival rate of mice and suppressing serum IL-1β release. These results demonstrated that compound 6 had the potential to be developed as a broad-spectrum NLRP3 inflammasome inhibitor for the treatment of NLRP3-related disease.