Curcumin alleviates DSS-induced colitis via inhibiting NLRP3 inflammsome activation and IL-1β production

UBE2W Improves the Experimental Colitis by Inhibiting the NF-κB Signaling Pathway

BACKGROUND

The NF-κB signaling cascade regulates immune response and is often dysregulated in tumor development. UBE2W is a novel type I ubiquitin-conjugating enzyme (E2) whose biological function is still unclear.

AIMS

This study was designed to investigate whether UBE2W regulates NF-κB signaling pathway and is involved in the progression of experimental colitis.

METHODS

At the cellular level, the effect of UBE2W on NF-κB transcriptional activity was measured using a dual-luciferase reporter assay. The influence of UBE2W on NF-κB pathway activation and the entry of p65 into the nucleus were determined by Western blot and immunofluorescence analyses, respectively. Moreover, the colitis model was established by administering 2.5% dextran sulfate sodium (DSS)/water to UBE2W overexpression, UBE2W-knockdown and control mice. Body weight, stool consistency, colon length and clinical severity were examined. Expression of pro-inflammatory cytokines and phosphorylation of p65 and IκB in the colon tissue were measured by qRT-PCR and Western blot, respectively.

RESULTS

UBE2W inhibited TNFα-induced NF-κB transcription activity, attenuated IκB and p65 phosphorylation, downregulated TNFα and IL-8 expression and blocked the entry of p65 into the nucleus. In the DSS-induced colitis model, UBE2W-knockdown mice had increased weight loss, more serious diarrhea and mucosal injures compared with the control mice. Moreover, phosphorylation of IκB and p65 and the expression of pro-inflammatory mediators such as TNFα, IL-6 were significantly increased in UBE2W knockdown mice. However, these changes were completely reversed in UBE2W overexpression mice.

CONCLUSIONS

The overexpression of UBE2W ameliorates the severity of DSS-induced colitis, which may be mediated by inhibiting the expression of pro-inflammatory mediators and activation of the NF-κB signaling pathway. These findings provide evidence that UBE2W might have potential therapeutic implications in IBD.

Amination Potentially Augments the Ameliorative Effect of Curcumin on Inhibition of the IL-6/Stat3/c-Myc Pathway and Gut Microbial Modulation in Colitis-Associated Tumorigenesis

Epigallocatechin gallate and tetrahydrocurcumin are aminated as colonic metabolites, preserving their bioactivities and improving their capabilities. We compared the bioactivities of unaminated (CUR) and aminated (AC) curcumin in inflammatory colitis-associated tumorigenesis. The anti-inflammatory and anticancer capabilities of CUR and AC were evaluated using RAW264.7 and HT29 cell lines, respectively. An azoxymethane/dextran sodium sulfate-induced colitis-associated carcinogenesis mouse model was used with CUR and two-dose AC interventions. AC had a greater anti-inflammatory effect but a similar anticancer effect as CUR in vitro. CUR and low-dose AC (LAC) significantly preserved colon length and reduced tumor number in vivo. Both CUR and LAC inhibited activation of the protein kinase B (AKT)/nuclear factor kappa B (NF-κB) signaling pathway, its downstream cytokines, and the interleukin (IL)-6/signal transducer and activator of transcription 3 (STAT3)/c-myelocytomatosis oncogene (c-MYC) pathway. However, only LAC significantly preserved E-cadherin, reduced N-cadherin, and facilitated beneficial gut microbial growth, including Akkermansia and Bacteroides, potentially explaining AC's better ameliorative effect at low than high doses.

Polyphenols from foxtail millet bran ameliorate DSS-induced colitis by remodeling gut microbiome

INTRODUCTION

Polyphenols from plants possess the anti-inflammatory and gut microbiota modulated properties. Foxtail millet (Setaria italica L., FM) has potential medical and nutritional functions because of rich phenolic and other phytochemical components.

METHODS

Here, the study explored the effects of bound polyphenol of inner shell (BPIS) from FM bran on dextran sodium sulfate (DSS)-induced experimental colitis mice.

RESULTS

Results showed that BPIS administration effectively relieved the weight loss, decreased disease active index (DAI) scores, restrained the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, increased anti-inflammatory cytokines IL-10, IL-4, IL-5. BPIS prevented gut barrier damage by enhancing tight junction proteins Claudin1, ZO-1 and Occludin, increasing the number of goblet cells and facilitating the gene expressions of mucin family. In addition, BPIS restored the gut microbiota composition and increased the relative abundance of commensal bacteria such as Lachnospiraceae and Rikenellaceae and restrained the growth of S24-7 and Staphylococcaceae. Concentrations of short-chain-fatty acids (SCFAs) generated by gut microbiota were elevated in BPIS treated colitis mice.

CONCLUSION

These data suggest that BPIS effectively ameliorates DSS-induced colitis by preventing intestinal barrier damage and promoting gut microbiota community.

The role of cholesterol and mitochondrial bioenergetics in activation of the inflammasome in IBD

Inflammatory Bowel Disease (IBD) is characterized by a loss of intestinal barrier function caused by an aberrant interaction between the immune response and the gut microbiota. In IBD, imbalance in cholesterol homeostasis and mitochondrial bioenergetics have been identified as essential events for activating the inflammasome-mediated response. Mitochondrial alterations, such as reduced respiratory complex activities and reduced production of tricarboxylic acid (TCA) cycle intermediates (e.g., citric acid, fumarate, isocitric acid, malate, pyruvate, and succinate) have been described in in vitro and clinical studies. Under inflammatory conditions, mitochondrial architecture in intestinal epithelial cells is dysmorphic, with cristae destruction and high dynamin-related protein 1 (DRP1)-dependent fission. Likewise, these alterations in mitochondrial morphology and bioenergetics promote metabolic shifts towards glycolysis and down-regulation of antioxidant Nuclear erythroid 2-related factor 2 (Nrf2)/Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling. Although the mechanisms underlying the mitochondrial dysfunction during mucosal inflammation are not fully understood at present, metabolic intermediates and cholesterol may act as signals activating the NLRP3 inflammasome in IBD. Notably, dietary phytochemicals exhibit protective effects against cholesterol imbalance and mitochondrial function alterations to maintain gastrointestinal mucosal renewal in vitro and in vivo conditions. Here, we discuss the role of cholesterol and mitochondrial metabolism in IBD, highlighting the therapeutic potential of dietary phytochemicals, restoring intestinal metabolism and function.

Polyphenols and inflammatory bowel disease: Natural products with therapeutic effects?

Inflammatory bowel disease (IBD) is a long-life disease with periods of recurrence and relief. Oxidative stress plays an important role in the pathogenesis of this disease. Recent years' studies in the field of IBD treatment mostly have focused on targeting cytokines and immune cell trafficking using antibodies and inhibitors, altering the composition of intestinal bacteria in the line of attenuation of inflammation using probiotics and prebiotics, and attenuating oxidative stress through antioxidant supplementation. Studies in animal models of IBD have shown that some polyphenolic compounds including curcumin, quercetin, resveratrol, naringenin, and epigallocatechin-3-gallate can affect almost all of the above aspects and are useful compounds in the treatment of IBD. Clinical studies performed on IBD patients have also confirmed the findings of animal model studies and have shown that supplementation with some of the above-mentioned polyphenolic compounds has positive effects in reducing disease clinical and endoscopic activity, inducing and maintaining remission, and improving quality of life. In this review article, in addition to a detailed reviewing the effects of the above-mentioned polyphenolic compounds on the events involved in the pathogenesis of IBD, the results of these clinical studies will also be reviewed.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Curcumin analog C66 alleviates inflammatory colitis by inhibiting the activation of NF-κB

BACKGROUND

The pathogenesis of inflammatory bowel disease (IBD) remains unclear. C66, a derivative of curcumin, reportedly exerts anti-inflammatory, antifibrotic and anti-apoptotic effects by targeting the JNK pathway. However, the effect of C66 against IBD is not clear. In this study, we aimed to investigate the effect of C66 against IBD.

METHODS

C57BL/6J mice were treated with 2.5% DSS for 7 days, and then administered water for 3 days to develop the IBD mouse model. A mouse intestinal epithelial cell line, MODE-K, stimulated by lipopolysaccharide (LPS) was used as the in vitro model. The therapeutic effects of C66 were evaluated and the pharmacological mechanisms were explored.

RESULTS

Compared to the model group, C66 treatment significantly reduced colitis-associated damage, including a decrease in disease activity index (DAI), a higher body weight and longer colon. In addition, the infiltration of distal inflammatory cells, loss of crypt tissues, and destruction of epithelial cells were reduced in C66-treated group. In addition, C66 treatment reduced fibrotic areas and inflammatory responses in the colon tissues, leading to increased epithelial cell proliferation and decreased apoptosis in colon. Furthermore, C66 treatment decreased the levels of p-JNK and p-P65, indicating that C66 inhibits the activation of the JNK and NF-κB signaling pathways induced by DSS in colon tissues. Finally, in vitro data show that C66 inhibited LPS-induced inflammation and apoptosis in small intestinal epithelial cells.  CONCLUSIONS: The curcumin analog C66 exhibits its anti-inflammatory effect by inhibiting the DSS-induced activation of JNK/NF-κB signaling pathways. C66 may be a potential candidate for the treatment of IBD.

Effects of molecular weight on intestinal anti-inflammatory activities of β-D-glucan from Ganoderma lucidum

To investigate the influence of molecular weight (Mw) on the anti-inflammatory activity of β-D-glucan from Ganoderma lucidum, ultrasonic irradiation was applied to treat the β-D-glucan (GLP, 2.42 × 106 g/mol) solution to obtain two degraded fractions with molecular weight of 6.53 × 105 g/mol (GLPC) and 3.49 × 104 g/mol (GLPN). Structural analysis proved that the degraded fractions possessed similar repeated units with the original β-D-glucan. The in vitro anti-inflammatory activity studies showed that all fractions could significantly inhibit LPS-induced expression of cytokines including TNF-α, IL-8, MIF and MCP-1 in Caco-2 cells at certain concentrations. Moreover, GLPC and GLPN exhibited better anti-inflammatory activity than GLPC. The intestinal anti-inflammatory activity evaluated by dextran sulfate sodium (DSS)—induced colitis mice model showed that intragastric administration of GLPN (lower Mw fraction) could significantly recover inflamed tissues of mice. Compared with GLP and GLPC, GLPN exhibited stronger ability to inhibit the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). The results revealed that Mw of β-D-glucan influenced its anti-inflammatory activity and decreasing of Mw would improve the activity, which provided evidence for the potential use of β-D-glucan from G. lucidum as anti-colitis ingredients.

Linarin ameliorates dextran sulfate sodium-induced colitis in C57BL/6J mice via the improvement of intestinal barrier, suppression of inflammatory responses and modulation of gut microbiota

Linarin is a natural flavonoid compound found in Chrysanthemum indicum, Mentha species and other plants with various biological activities. The study aimed to investigate the protective effect of linarin supplementation on dextran sulfate sodium (DSS)-induced colitis in C57BL/6J mice and its potential mechanisms. The results showed that doses of linarin at 25 and 50 mg kg^-1 day^-1 alleviated the DSS-induced histopathological damage, and improved the mucosal layer and intestinal barrier function. Importantly, Linarin significantly suppressed the levels of myeloperoxidase activity and pro-inflammatory cytokines (IL-6, TNF-α, IFN-γ and IL-1β) in the colon, and enhanced the mRNA level of anti-inflammatory cytokine (IL-10). Moreover, 50 mg kg^-1 day^-1 linarin reversed the gut microbiota damaged by DSS, including Alistipes, Rikenella and Clostridia UCG-014_norank. Linarin also partly increased the relative abundance of short-chain fatty acids (SCFAs)-producing bacteria, including Lactobacillus, Roseburia, Parabacteroides and Blautia, and elevated the contents of SCFAs. Collectively, linarin attenuates DSS-induced colitis in mice, suggesting that linarin may be a promising nutritional strategy for reducing inflammatory bowel disease.

Jatrorrhizine Alleviates DSS-Induced Ulcerative Colitis by Regulating the Intestinal Barrier Function and Inhibiting TLR4/MyD88/NF-κB Signaling Pathway

Background

Ulcerative colitis (UC), a kind of autoimmune disease with unknown etiology, has been troubling human physical and mental health. Jatrorrhizine (Jat) is a natural isoquinoline alkaloid isolated from Coptis Chinensis, which has been proved to have antibacterial, anti-inflammatory, and antitumor effects.

Purpose

The purpose is to explore the therapeutic effect of Jat on DSS-induced UC and the mechanism of action. Study Design. The UC mice model was induced by 3% DSS in drinking water. The mice were orally administered with Jat (40, 80, 160 mg/kg) for 10 days.

Methods

The changes in body weight, colon length, spleen wet weight index, disease activity index (DAI), colonic histopathology, and inflammatory factors of serum and colon tissue were analyzed to evaluate the severity of colitis mice. The colon mucus secretion capacity was analyzed by Alcian blue periodic acid Schiff (AB-PAS) staining. Furthermore, protein expressions such as TLR4, MyD88, p–NF–κB-p65, NF-κB-p65, COX-2, ZO-1, and Occludin were detected to elucidate the molecular mechanism of Jat on DSS-induced colitis model.

Results

The results showed that Jat could significantly alleviate the symptoms, colon shortening, spleen index, and histological damage and restore the body weight in DSS-induced colitis mice. Jat also suppressed the levels of inflammatory cytokines and upregulated the levels of anti-inflammatory cytokines. In addition, Jat repaired the intestinal barrier function by upregulating the level of colonic tight junction (TJ) proteins and enhancing the secretion of mucin produced by goblet cells. Furthermore, Jat could significantly suppress the expression of TLR4, MyD88, p–NF–κB-p65/NF-κB-p65, and COX-2 in colon tissue.

Conclusion

The results suggested that Jat plays a protective role in DSS-induced colitis by regulating the intestinal barrier function and inhibiting the TLR4/MyD88/NF-κB signaling pathway. This study, for the first time, demonstrates the therapeutic and protective effects of Jat on UC.

Curcumin-Loaded Microspheres Are Effective in Preventing Oxidative Stress and Intestinal Inflammatory Abnormalities in Experimental Ulcerative Colitis in Rats

Curcumin’s role in the treatment of ulcerative colitis (UC) has been proven by numerous studies, but its preventive administration, with the aim of reducing the remission episodes that are characteristic of this disease, must be further investigated. This study investigates the effects of a novel curcumin-loaded polymeric microparticulate oral-drug-delivery system for colon targeting (Col-CUR-MPs) in an experimental model of UC. Male Wistar rats (n = 40) were divided into five groups (n = 8), which were treated daily by oral gavage for seven days with a 2% aqueous solution of carboxymethylcellulose sodium salt (CMCNa) (healthy and disease control), free curcumin powder (reference), Col-CUR-MPs (test) and prednisolone (reference) prior to UC induction by the intrarectal administration of acetic acid (AA), followed by animal sacrification and blood and colonic samples’ collection on the eighth day. Col-CUR-MPs exhibited an important preventive effect in the severity degree of oxidative stress that resulted following AA intrarectal administration, which was proved by the highest catalase (CAT) and total antioxidant capacity (TAC) levels and the lowest nitrites/nitrates (NOx), total oxidative status (TOS) and oxidative stress index (OSI) levels. Biochemical parameter analysis was supported by histopathological assessment, confirming the significant anti-inflammatory and antioxidant effects of this novel colon-specific delivery system in AA-induced rat models of UC. Thus, this study offers encouraging perspectives regarding the preventive administration of curcumin in the form of a drug delivery system for colon targeting.

Tackling Inflammatory Bowel Diseases: Targeting Proinflammatory Cytokines and Lymphocyte Homing

Inflammatory bowel diseases (IBDs) are characterized by chronic inflammatory disorders that are a result of an abnormal immune response mediated by a cytokine storm and immune cell infiltration. Proinflammatory cytokine therapeutic agents, represented by TNF inhibitors, have developed rapidly over recent years and are promising options for treating IBD. Antagonizing interleukins, interferons, and Janus kinases have demonstrated their respective advantages in clinical trials and are candidates for anti-TNF therapeutic failure. Furthermore, the blockade of lymphocyte homing contributes to the excessive immune response in colitis and ameliorates inflammation and tissue damage. Factors such as integrins, selectins, and chemokines jointly coordinate the accumulation of immune cells in inflammatory regions. This review assembles the major targets and agents currently targeting proinflammatory cytokines and lymphatic trafficking to facilitate subsequent drug development.

Inflammasome-targeting natural compounds in inflammatory bowel disease: Mechanisms and therapeutic potential

Inflammatory bowel disease (IBD), mainly including Crohn’s disease and ulcerative colitis, seriously affects human health and causes substantial social and economic burden. The pathogenesis of IBD is still not fully elucidated, whereas recent studies have demonstrated that its development is associated with the dysfunction of intestinal immune system. Accumulating evidence have proven that inflammasomes such as NLRP3 and NLRP6 play a prominent role in the pathogenesis of IBD. Thus, regulating the activation of inflammasomes have been considered to be a promising strategy in IBD treatment. A number of recent studies have provided evidence that blocking inflammasome related cytokine IL-1β can benefit a group of IBD patients with overactivation of NLRP3 inflammasome. However, therapies for targeting inflammasomes with high efficacy and safety are rare. Traditional medical practice provides numerous medical compounds that may have a role in treatment of various human diseases including IBD. Recent studies demonstrated that numerous medicinal herb derived compounds can efficiently prevent colon inflammation in animal models by targeting inflammasomes. Herein, we summarize the main findings of these studies focusing on the effects of traditional medicine derived compounds on colitis treatment and the underlying mechanisms in regulating the inflammasomes. On this basis, we provide a perspective for future studies regarding strategies to improve the efficacy, specificity and safety of available herbal compounds, and to discover new compounds using the emerging new technologies, which will improve our understanding about the roles and mechanisms of herbal compounds in the regulation of inflammasomes and treatment of IBD.

Dietary AhR Ligands Have No Anti-Fibrotic Properties in TGF-β1-Stimulated Human Colonic Fibroblasts

Background: Intestinal fibrosis is a common complication in inflammatory bowel disease (IBD) patients without specific treatment. Aryl hydrocarbon receptor (AhR) activation is associated with better outcomes in intestinal inflammation. Development of novel therapies targeting fibrogenic pathways is required and we aimed to screen dietary AhR ligands for their anti-fibrotic properties in TGF-β1-stimulated human colonic fibroblast cells. Methods: The study was conducted using TGF-β1-stimulated CCD-18Co, a human colonic fibroblast cell line in response to increased concentrations of dietary ligands of AhR such as FICZ, ITE, L-kynurenine and curcumin. Fibrosis markers such as α-SMA, COL1A1, COL3A1 and CTGF were assessed. AhR and ANRT RNA were evaluated. Results: TGF-β1 at 10 ng/mL significantly induced mRNA levels for ECM-associated proteins such as CTGF, COL1A1 and COL3A1 in CCD-18Co cells. FICZ from 10 to 1000 nM, L-kynurenine from 0.1 to 10 μM, ITE from 1 to 100 μM or curcumin from 5 to 20 μM had no significant effect on fibrosis markers in TGF-β1-induced CCD-18Co. Conclusions: Our data highlight that none of the tested dietary AhR ligands had an effect on fibrosis markers in TGF-β1-stimulated human colonic fibroblast cells in our experimental conditions. Further studies are now required to identify novel potential targets in intestinal fibrosis.

WTAP-mediated N6-methyladenosine modification of NLRP3 mRNA in kidney injury of diabetic nephropathy

Background

Diabetic nephropathy (DN) is prevalent in patients with diabetes. N⁶-methyladenosine (m⁶A) methylation has been found to cause modification of nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing (NLRP) 3, which is involved in cell pyroptosis and inflammation. WTAP is a key gene in modulating NLRP3 m⁶A.

Methods

In this study, WTAP was silenced or overexpressed in high glucose (HG)-treated HK-2 cells to determine its influence on pyroptosis, NLRP3 inflammasome-related proteins, and the release of pro-inflammatory cytokines. NLRP3 expression and m⁶A levels were assessed in the presence of WTAP shRNA (shWTAP). WTAP expression in HK-2 cells was examined with the introduction of C646, a histone acetyltransferase p300 inhibitor.

Results

We found that WTAP expression was enhanced in patients with DN and in HG-treated HK-2 cells. Knockdown of WTAP attenuated HG-induced cell pyroptosis and NLRP3-related pro-inflammatory cytokines in both HK-2 cells and db/db mice, whereas WTAP overexpression promoted these cellular processes in HK-2 cells. WTAP mediated the m⁶A of NLRP3 mRNA that was stabilized by insulin-like growth factor 2 mRNA binding protein 1. Histone acetyltransferase p300 regulated WTAP expression. WTAP mRNA levels were positively correlated with NLRP3 inflammasome components and pro-inflammatory cytokines.

Conclusion

Taken together, WTAP promotes the m⁶A methylation of NLRP3 mRNA to upregulate NLRP3 inflammasome activation, which further induces cell pyroptosis and inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00350-8.

Therapeutic Potential of Curcumin in a Rat Model of Dextran Sulfate Sodium-Induced Ulcerative Colitis by Regulating the Balance of Treg/Th17 Cells

The pathogenesis of ulcerative colitis (UC) remains unclear, and it is believed that an imbalance of regulatory T (Treg) cells and T helper 17 (Th17) cells is related to the occurrence of UC. Curcumin has been confirmed to exert anti-inflammatory effects in bronchial asthma and osteoarthritis by regulating the balance of Treg/Th17 cells. This study aimed to explore the therapeutic potential of curcumin in dextran sulfate sodium (DSS)-induced UC rats by regulating the balance of Treg/Th17 cells. Disease activity index (DAI) scores were calculated. Changes in colon inflammation were observed using hematoxylin and eosin staining. Treg and Th17 cells in the spleen were detected by flow cytometry, and the levels of interleukin (IL)-10 and IL-17A were determined using enzyme-linked immunosorbent assay. In DSS-induced colitis, curcumin significantly ameliorated colitis symptoms by reducing the DAI and increasing colon length. Additionally, curcumin significantly increased the expression of Treg cells and decreased the expression of Th17 cells and the extent of histopathological damage. Furthermore, curcumin increased the expression of IL-10 and decreased the expression of IL-17A. Curcumin attenuates DSS-induced UC injury by regulating Treg/Th17 balance and related cytokine secretion. Thus, curcumin may be a promising therapeutic drug for treating UC.

Inflammatory-Dependent Bidirectional Effect of Bile Acids on NLRP3 Inflammasome and Its Role in Ameliorating CPT-11-Induced Colitis

Irinotecan (CPT-11) in combination with 5-fluorouracil and leucovorin is a first-line chemotherapy regimen for the treatment of colorectal cancer; however, its clinical application is limited by the dose-limiting gastrointestinal toxicity of colitis. In our previous studies, several bile acids (BAs) were found significantly elevated in the colon of the CPT-11-induced rat colitis model. On the other hand, NLRP3 inflammasome has been reported to play important roles in mediating colitis. Interestingly, BA was stated to activate the NLRP3 inflammasome in some studies, while in some other reports, it showed an inhibitory effect. We assumed that the inflammatory status in different circumstances might have contributed to the controversial findings. In this study, we first discovered, under non-inflammatory conditions, that supplementing BA could activate the NLRP3 inflammasome in THP-1-differentiated macrophages and promote inflammation. In lipopolysaccharide (LPS)-induced inflammatory macrophages, however, BA inhibited the NLRP3 inflammasome and reduced inflammation. Further experiments demonstrated that Takeda G protein-coupled receptor 5 (TGR5) is essential in mediating the inhibitory effect of BA, while phospho-SP1 (p-SP1) is key to the activation. Furthermore, we applied the above findings to ameliorate CPT-11-caused colitis in rats by inhibiting SP1 with mithramycin A (MitA) or activating TGR5 using oleanolic acid (OA). Our findings may shed light on the discovery of effective interventions for reducing dose-limiting chemotherapy-induced colitis.

HucMSC-Ex carrying miR-203a-3p.2 ameliorates colitis through the suppression of caspase11/4-induced macrophage pyroptosis

BACKGROUND

Inflammatory bowel disease (IBD) is a kind of chronic, idiopathic, and recurrent inflammation, associated with dysregulated intestinal mucosal immunity. Caspase (casp) 11/4-induced macrophage pyroptosis contributes to the development of inflammation, while human umbilical cord mesenchymal stem cell-secreted exosomes (hucMSC-Ex) play a reparative role in IBD.

OBJECTIVE

The present study focused on the treatment of IBD with hucMSC-Ex and its regulatory mechanism via the casp11/4 pathway.

METHODS

BALB/c mice were used to establish a dextran sulfate sodium (DSS)-induced colitis model, and hucMSC-Ex was administered intravenously to estimate its therapeutic effect. In vitro, RAW264.7 cells line, THP-1 cells line, and mouse peritoneal macrophages (MPMs) were stimulated with lipopolysaccharides (LPS) to activate an inflammatory environment of pyroptosis, followed by repairing with hucMSC-Ex. MicroRNA mimics and inhibitors were provided to verify the role of miR-203a-3p.2 from hucMSC-Ex in inflammation. The results were analyzed by Western blot, RT-qPCR、ELISA, and LDH secretion.

RESULTS

HucMSC-Ex inhibited the activation of casp11 and reduced the secretion of interleukin (IL)-1β, IL-6, and casp11, which relieved macrophage pyroptosis to alleviate murine colitis. A consistent outcome was revealed in the cell experiments, where hucMSC-Ex contributed to a decreased casp11/4 expression, and lactate dehydrogenase (LDH) release, as a marker of cell damage. Moreover, miR-203a-3p.2 from hucMSC-Ex functioned as an effective mediator in the interaction with casp4 in THP-1 macrophage pyroptosis.

CONCLUSION

HucMSC-Ex ameliorates colitis through the suppression of casp11/4-induced macrophage pyroptosis, and hucMSC-Ex carrying miR-203a-3p.2 inhibits casp4-induced macrophage pyroptosis in an inflammatory environment.

Hydroxysafflor yellow A protects against ulcerative colitis via suppressing TLR4/NF-κB signaling pathway

Hydroxysafflower yellow A (HSYA) protects against acute kidney injury through TLR4/NF-κB pathway. However, the effect and potential mechanism of HSYA in ulcerative colitis (UC) have been rarely reported, which is thus investigated in this research. An in vivo UC model was established by oral administration of 5% dextran sulfate sodium (DSS) in Sprague-Dawley rats. After HSYA treatment, the daily body weight and colon length of rats were measured. Then rat colon tissues, myeloperoxidase (MPO) activity, and the levels of inflammatory cytokines were examined by histopathological examination (HE) staining, immunohistochemistry, ultraviolet spectrophotometry, and enzyme-linked immune sorbent assay (ELISA) respectively. The activated TLR4/NF-κB pathway was detected by Western blot. RAW 264.7 cell viability was detected by MTT assay after lipopolysaccharide (LPS) treatment, and ELISA and Western blot were performed again to investigate the effects of HSYA on LPS-treated cells. DSS administration increased body weight and colon length of rats and induced colon tissue injury. DSS or LPS treatment up-regulated the levels of TNF-α, IL-1β, and IL-6 and activated TLR4/NF-κB pathway of colon tissues and cells, respectively. HSYA partially reversed the above effect of DSS and LPS treatment, and the effects of the drug were improved with the dosage. Taken together, HSYA alleviates UC by suppressing TLR4/NF-κB signaling pathway, which may provide a new insight for the treatment of UC.

Integrated Analysis Reveals the Targets and Mechanisms in Immunosuppressive Effect of Mesalazine on Ulcerative Colitis

Background

Ulcerative colitis (UC) is an inflammatory bowel disease that causes inflammation and ulcers in the digestive tract. Approximately 3 million US adults suffer from this disease. Mesalazine, an anti-inflammatory agent, is commonly used for the treatment of UC. However, some studies have demonstrated side effects of mesalazine, such as acute pancreatitis and hypereosinophilia. Therefore, a better understanding of the anti-inflammatory mechanism of mesalazine in UC could help improve the effectiveness of the drug and reduce its side effects. In this study, we used a dextran sodium sulfate-induced UC mouse model, and applied network pharmacology and omics bioinformatics approaches to uncover the potential pharmaceutical targets and the anti-inflammatory mechanism of mesalazine.

Results

Network pharmacology analysis identified the core targets of mesalazine, biological processes, and cell signaling related to immunity and inflammatory responses mediated by mesalazine. Molecular docking analysis then indicated possible binding motifs on the core targets (including TNF-α, PTGS2, IL-1β, and EGFR). Metabolomics and 16S metagenomic analyses highlighted the correlation between gut microbiota and metabolite changes caused by mesalazine in the UC model.

Conclusions

Collectively, the omics and bioinformatics approaches and the experimental data unveiled the detailed molecular mechanisms of mesalazine in UC treatment, functional regulation of the gut immune system, and reduction of intestinal inflammation. More importantly, the identified core targets could be targeted for the treatment of UC.

NLRP3-Mediated Inflammation in Atherosclerosis and Associated Therapeutics

The NLRP3 inflammasome is a crucial constituent of the body’s innate immune system, and a multiprotein platform which is initiated by pattern recognition receptors (PRRs). Its activation leads to caspase-1 maturation and release of inflammatory cytokines, interleukin-1β (IL-1β) and IL-18, and subsequently causes pyroptosis. Recently, the excess activation of NLRP3 inflammasome has been confirmed to mediate inflammatory responses and to participate in genesis and development of atherosclerosis. Therefore, the progress on the discovery of specific inhibitors against the NLRP3 inflammasome and the upstream and downstream inflammatory factors has become potential targets for clinical treatment. Here we review the recently described mechanisms about the NLRP3 inflammasome activation, and discuss emphatically the pharmacological interventions using statins and natural medication for atherosclerosis associated with NLRP3 inflammasome.

Phycocyanin Ameliorates Colitis-Associated Colorectal Cancer by Regulating the Gut Microbiota and the IL-17 Signaling Pathway

Phycocyanin (PC) is a pigment-protein complex. It has been reported that PC exerts anti-colorectal cancer activities, although the underlying mechanism has not been fully elucidated. In the present study, azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced mice were orally administrated with PC, followed by microbiota and transcriptomic analyses to investigate the effects of PC on colitis-associated cancer (CAC). Our results indicated that PC ameliorated AOM/DSS induced inflammation. PC treatment significantly reduced the number of colorectal tumors and inhibited proliferation of epithelial cell in CAC mice. Moreover, PC reduced the relative abundance of Firmicutes, Deferribacteres, Proteobacteria and Epsilonbacteraeota at phylum level. Transcriptomic analysis showed that the expression of genes involved in the intestinal barrier were altered upon PC administration, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed the IL-17 signaling pathway was affected by PC treatment. The study demonstrated the protective therapeutic action of PC on CAC.

Electroacupuncture Reduces Visceral Pain Via Cannabinoid CB2 Receptors in a Mouse Model of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) results in chronic abdominal pain in patients due to the presence of inflammatory responses in the colon. Electroacupuncture (EA) is effective in alleviating visceral pain and colonic inflammation associated with IBD. Cannabinoid CB2 receptor agonists also reduce colonic inflammation in a mouse model of IBD. However, whether EA reduces visceral pain and colonic inflammation via the CB2 receptor remains unknown. Here, we determined the mechanism of the antinociceptive effect of EA in a mouse model of IBD induced by rectal perfusion of 2,4,6-trinitrobenzenesulfonic acid solution (TNBS). EA or sham EA was performed at the bilateral Dachangshu (BL25) point for seven consecutive days. The von Frey and colorectal distension tests were performed to measure mechanical referred pain and visceral pain. Western blotting and immunohistochemistry assays were carried out to determine the expression of IL-1β and iNOS and activation of macrophages in the colon tissues. We found that EA, but not sham EA, attenuated visceral hypersensitivity and promoted activation of CB2 receptors, which in turn inhibited macrophage activation and the expression of IL-1β and iNOS. The effects of EA were blocked by AM630, a specific CB2 receptor antagonist, and by CB2 receptor knockout. Our findings suggest that EA attenuates mechanical allodynia and visceral hypersensitivity associated with IBD by activating CB2 receptors and subsequent inhibition of macrophage activation and expression of IL-1β and iNOS.

Curcumin Alleviates Dextran Sulfate Sodium-induced Colitis in Mice Through Regulating Gut Microbiota

SCOPE

Curcumin is a natural polyphenol compound with multiple pharmacologic activities. The present study aims to explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its anti-inflammatory, anti-oxidant, and anti-apoptotic properties, as well as their associations with altered intestinal microbiome.

METHODS AND RESULTS

DSS, i.e., Dextran Sulfate Sodium, (3%) was administered to C57BL/6J mice in the drinking water daily for 6 days in DSS and curcumin groups. Then mice in curcumin groups were orally administered with 50 or 150 mg/kg curcumin for 7 days. On day 13, mice were sacrificed. Results showed that oral administration with curcumin relieved macroscopic pathological manifestations, e.g. colon length and histological change. Moreover, it enhanced intestinal barrier via increasing expression of tight junction proteins, e.g. occludin, ZO-1, claudin-3; alleviated DSS-induced intestinal apoptosis via suppressing caspase-3 pathway; mitigated intestinal inflammation via inhibiting the MAPK/NFκB/STAT3 pathway. We also noticed that curcumin is beneficial for modulating abundance of some specific bacteria, including Akkermansia, Coprococcus, Roseburia, and Turicibacter, as well as families such as F16, Enterococcaceae, and Aerococcaceae. Most of the altered bacteria by curcumin are highly correlated with colitis-associated parameters.

CONCLUSION

curcumin shows therapeutic potential against colitis. It may be served as alternative medicine or adjuvant therapy in the treatment of colitis. This article is protected by copyright. All rights reserved.

Phenols and terpenoids: natural products as inhibitors of NLRP3 inflammasome in cardiovascular diseases

Inflammatory infiltration has been implicated in the pathogenesis of cardiovascular diseases (CVDs). The NLRP3 inflammasome is involved in the development of several types of CVDs, including myocardial infarction, myocardial ischemia-reperfusion damage, heart failure, atrial fibrillation, and hypertension. Inhibiting the activity of NLRP3 inflammasome can inhibit the progress of CVDs. However, there is no NLRP3 inflammasome inhibitor in clinic, and it is very important to find a safe and effective NLRP3 inhibitor. Phenols and terpenoids are naturally natural products that have many anti-inflammatory effects in CVDs by modulating the NLRP3 inflammatory pathway. Thus, 20 natural products from phenols and terpenoids for the treatment of cardiovascular disease based on the inhibition of NLRP3 inflammasome were summarized and screened. Docking results showed salvianolic acid B and ellagic acid in phenols, and oridonin and triptolide in terpenoids had a better binding activity with NLRP3, which can provide theoretical support for finding novel NLRP3 inflammasome inhibitors or lead compounds in the future.

Amelioration of AOM/DSS-Induced Murine Colitis-Associated Cancer by Evodiamine Intervention is Primarily Associated with Gut Microbiota-Metabolism-Inflammatory Signaling Axis

Evodiamine (EVO), an indole alkaloid derived from Rutaceae plants Evodia rutaecarpa (Juss.) Benth.、Evodia rutaecarpa (Juss.) Benth. Var. bodinieri (Dode) Huang or Evodia rutaecarpa (Juss.) Benth. Var. officinalis (Dode) Huang, has anti-inflammatory and anti-tumor activities. Our previous study found that EVO attenuates colitis by regulating gut microbiota and metabolites. However, little is known about its effect on colitis-associated cancer (CAC). In this study, the protective effects of EVO on azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis and tumor mice were observed, and the underlying potential mechanism was clarified. The results suggested that EVO ameliorated AOM/DSS-induced colitis by inhibiting the intestinal inflammation and improving mucosal barrier function. And EVO significantly reduced the number and size of AOM/DSS-induced colorectal tumors along with promoted apoptosis and inhibited proliferation of epithelial cell. Moreover, EVO promoted the enrichment of SCFAs-producing bacteria and reduced the levels of the pro-inflammatory bacteria, which contributes to the changes of microbiota metabolism, especially tryptophan metabolism. Furthermore, inflammatory response (like Wnt signaling pathway、Hippo signaling pathway and IL-17 signaling pathway) were effectively alleviated by EVO. Our study demonstrated that the protective therapeutic action of EVO on CAC is to inhibit the development of intestinal inflammation-cancer by regulating gut microbiota metabolites and signaling pathways of colon intestinal epithelial, which may represent a novel agent for colon cancer prevention via manipulation of gut microbiota.

The role of flavonoids in inhibiting IL-6 and inflammatory arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the synovial joints. RA has well-known clinical manifestations and can cause progressive disability and premature death along with socioeconomic burdens. Interleukin-6 (IL-6) has been implicated in the pathology of RA where it can stimulate pannus formation, osteoclastogenesis, and oxidative stress. Flavonoids are plant metabolites with beneficial pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, anticancer, and others. Flavonoids are polyphenolic compounds found in a variety of plants, vegetables, and fruits. Many flavonoids have demonstrated anti-arthritic activity mediated mainly through the suppression of pro-inflammatory cytokines. This review thoroughly discusses the accumulate data on the role of flavonoids on IL-6 in RA.

Pharmacological Mechanisms and Clinical Applications of Curcumin: Update

Curcumin, a well-known hydrophobic polyphenol extracted from the rhizomes of turmeric (Curcuma longa L.), has attracted great interest in the last ten years due to its multiple pharmacological activities. A growing body of evidence has manifested that curcumin has extensive pharmacological activities including anti-inflammatory, anti-oxygenation, lipid regulation, antiviral, and anticancer with hypotoxicity and minor adverse reactions. However, the disadvantages of low bioavailability, short half-life in plasma, low drug concentration in blood, and poor oral absorption severely limited the clinical application of curcumin. Pharmaceutical researchers have carried out plenty of dosage form transformations to improve the druggability of curcumin and have achieved remarkable results. Therefore, the objective of this review summarizes the pharmacological research progress, problems in clinical application and the improvement methods of curcumin's druggability. By reviewing the latest research progress of curcumin, we believe that curcumin has a broad clinical application prospect for its wide range of pharmacological activities with few side effects. The deficiencies of lower bioavailability of curcumin could be improved by dosage form transformation. However, curcumin in the clinical application still requires further study regarding the underlying mechanism and clinical trial verification.

Cherry Polyphenol Extract Ameliorated Dextran Sodium Sulfate-Induced Ulcerative Colitis in Mice by Suppressing Wnt/β-Catenin Signaling Pathway

Ulcerative colitis (UC) is a chronic and nonspecific inflammatory disease of the colon and rectum, and its etiology remains obscure. Cherry polyphenols showed potential health-promoting effects. However, both the protective effect and mechanism of cherry polyphenols on UC are still unclear. This study aimed to investigate the potential role of the free polyphenol extract of cherry in alleviating UC and its possible mechanism of action. Our study revealed that the free polyphenol extract of cherry management significantly alleviated UC symptoms, such as weight loss, colon shortening, the thickening of colonic mucous layer, etc. The free polyphenol extract of cherry treatment also introduced a significant reduction in levels of malondialdehyde (MDA), myeloperoxidase (MPO) and nitric oxide (NO), while causing a significant elevation in levels of catalase (CAT), glutathione (GSH-Px), superoxide dismutase (SOD), as well as the downregulation of pro-inflammatory cytokines. This indicated that such positive effects were performed through reducing oxidative damage or in a cytokine-specific manner. The immunofluorescence analysis of ZO-1 and occludin proteins declared that the free polyphenol extract of cherry had the potential to prompt intestinal barrier function. The reduced expression levels of β-catenin, c-myc, cyclin D1 and GSK-3β suggested that the cherry extract performed its positive effect on UC by suppressing the Wnt/β-ctenin pathway. This finding may pave the way into further understanding the mechanism of cherry polyphenols ameliorating ulcerative colitis.

Forsythiaside A alleviates methotrexate-induced intestinal mucositis in rats by modulating the NLRP3 signaling pathways

Most chemotherapeutic drugs can kill the tumor cells, but also cause a vast damage to body, such as intestinal mucositis (IM). The present study was design to find out the effect of Forsythiaside A (FTA) on chemotherapeutic-induced IM in rats. Briefly, for 3 consecutive days, male Sprague-Dawley rats were treated with 7 mg / kg methotrexate (MTX) to establish IM and simultaneously administered with 40 or 80 mg / kg FTA for 7 days. Our results showed that the final body weight and daily food intake were increased, and the disease activity index was reduced in the MTX group after FTA treatment. The MTX group showed the pathological alterations like the inflammatory cells infiltration, the mucosal layer destruction, glands expansion, intestinal villi structure disorder and goblet cells reduction, while we found that 80 mg / kg FTA treatment displayed evident reversal effects. ELISA further suggested that TNF-α, IL-1β and IL-18 levels in serum in MTX-induced rats were reduced after 80 mg / kg FTA treatment. Moreover, FTA decreased the number of leukocytes, neutrophils and lymphocytes in peripheral blood. Western blot and immunofluorescence results indicated that the expression levels of NLRP3, cleaved caspase 1, cleaved IL-1β and CD68 positive rate were down-regulated in MTX-induced rats after 80 mg / kg FTA intervention. The findings of the current study suggested that FTA effectively inhibited MTX-induced IM in rats by attenuating the activation of the NLRP3 signaling pathways.

Lactobacillus casei ATCC 393 and it's metabolites alleviate dextran sulphate sodium-induced ulcerative colitis in mice through the NLRP3-(Caspase-1)/IL-1β pathway

Inflammatory bowel disease (IBD) represents a broad group of intestinal disorders, including ulcerative colitis (UC) and Crohn's disease (CD). Probiotics are increasingly being recognized as a means of treatment for people suffering from IBD. Our previous studies demonstrated that Lactobacillus casei ATCC 393 (L. casei ATCC 393) effectively alleviated enterotoxigenic Escherichia coli K88-induced intestinal barrier dysfunction. This study was conducted to investigate the protective effects of L. casei ATCC 393 and its metabolites on dextran sulfate sodium (DSS)-induced UC in C57BL/6 mice and the potential mechanism of these effects. The results showed that oral administration of L. casei ATCC 393 and its metabolites both effectively reversed the DSS-induced weight loss, and the reduction in the disease activity index (DAI), colon length, and villus height of colon tissue in mice. Compared to the DSS-induced model group, L. casei ATCC 393 and its metabolites significantly inhibited the infiltration of immune cells into the intestinal mucosa, decreased the production of pro-inflammatory factors, and increased the expression of anti-inflammatory factors in the serum and colon tissue, increased the expression levels of occludin, ZO-1, and claudin-1, and reduced the expression of nucleotide binding oligomeric domain-like receptor protein 3 (NLRP3), cysteine proteinase-1 (Caspase-1), IL-1β, and IL-18. In addition, L. casei ATCC 393 and its metabolites effectively improved DSS-induced gut microbiota dysbiosis. These results suggested that L. casei ATCC 393 and its metabolites alleviated the DSS-induced ulcerative inflammatory response in C57BL/6 mice through the NLRP3-(Caspase-1)/IL-1β signaling pathway.

Anti-Inflammatory Effects of Curcumin in the Inflammatory Diseases: Status, Limitations and Countermeasures

Curcumin is a natural compound with great potential for disease treatment. A large number of studies have proved that curcumin has a variety of biological activities, among which anti-inflammatory effect is a significant feature of it. Inflammation is a complex and pervasive physiological and pathological process. The physiological and pathological mechanisms of inflammatory bowel disease, psoriasis, atherosclerosis, COVID-19 and other research focus diseases are not clear yet, and they are considered to be related to inflammation. The anti-inflammatory effect of curcumin can effectively improve the symptoms of these diseases and is expected to be a candidate drug for the treatment of related diseases. This paper mainly reviews the anti-inflammatory effect of curcumin, the inflammatory pathological mechanism of related diseases, the regulatory effect of curcumin on these, and the latest research results on the improvement of curcumin pharmacokinetics. It is beneficial to the further study of curcumin and provides new ideas and insights for the development of curcumin anti-inflammatory preparations.

Pyroptosis: A possible link between obesity-related inflammation and inflammatory diseases

The main manifestation of obesity is persistent low-level inflammation and insulin resistance, which is an important factor inducing or promoting other obesity-related diseases. As a proinflammatory programmed cell death, pyroptosis plays an important role, especially in the activation and regulation of the NLRP3 inflammasome pathway. Pyroptosis is associated with the pathogenesis of many chronic inflammatory diseases and is characterized by the formation of micropores in the plasma membrane and the release of a large number of proinflammatory cytokines. This article mainly introduces the main pathways and key molecules of pyroptosis and focuses on the phenomenon of pyroptosis in obesity. It is suggested that the regulation of pyroptosis-related targets may become a new potential therapy for the prevention and treatment of systemic inflammatory response caused by obesity, and we summarize the potential molecular substances that may be beneficial to obesity-related inflammatory diseases through target pyroptosis.

Apple Polyphenols Extract (APE) Alleviated Dextran Sulfate Sodium Induced Acute Ulcerative Colitis and Accompanying Neuroinflammation via Inhibition of Apoptosis and Pyroptosis

The main aim of this study was to investigate the potent anti-apoptosis and anti-pyroptosis effects of apple polyphenols extract (APE) on dextran sulfate sodium model group (DSS)-induced acute ulcerative colitis (UC) and the protective effect of APE against acute UC-related neuroinflammation and synapse damage. Forty-three C57BL/6 male mice were randomly divided into a control group (CON), a 3% DSS model group (DSS), a 500 mg/(kg·bw·d) APE group (HAP), and a 125 (LD) or 500 (HD) mg/(kg·bw·d) APE treatment concomitantly with DSS treatment group. The results showed that APE significantly ameliorated DSS-induced acute UC through inhibiting intestinal epithelial cell (IEC) apoptosis and the Caspase-1/Caspase-11-dependent pyroptosis pathway, with increased BCL-2 protein expression and decreased protein levels of NLRP3, ASC, Caspase-1/11, and GSDND. Furthermore, APE significantly reduced acute UC-related neuroinflammation and synapse damage, supported by decreased mRNA levels of hypothalamus Cox-2 and hippocampus Gfap and also increased the mRNA levels of hypothalamus Psd-95. The increased protein expression of ZO-1 and Occludin improved the intestinal barrier integrity and improved the function of goblet cells by upregulating the protein level of MUC-2 and TTF3 accounted for the beneficial effects of APE on UC-associated neuroinflammation. Therefore, APE might be a safe and effective agent for the management of acute UC.

Curcumin Improves Epithelial Barrier Integrity of Caco-2 Monolayers by Inhibiting Endoplasmic Reticulum Stress and Subsequent Apoptosis

Curcumin is a natural polyphenol and is supposed to possess antioxidant, anti-inflammatory, anticancer, and antiapoptotic properties. Although some studies have reported the therapeutic effects of curcumin on ulcerative colitis (UC), the specific mechanism remains unclear. An in vitro coculture model of Caco-2 and differentiated THP-1 cells was established. After administration of curcumin (10 μM), Western blot analysis was performed to evaluate the protein levels of tight junction (TJ) proteins zonula occludens- (ZO-) 1 and claudin-1. Annexin V-APC/7-AAD assays and flow cytometry were conducted to assess Caco-2 cell apoptosis. The expression levels of oxidative stress and endoplasmic reticulum stress- (ERS-) related molecules were determined by Western blot analysis. Curcumin administration significantly upregulated ZO-1 and claudin-1 protein levels and reduced Caco-2 cell apoptosis. The protein levels of oxidative stress markers inducible nitric oxide synthase (iNOS) and γH2AX and ERS-induced apoptosis-related molecules C/EBP homologous protein (CHOP) and cleaved caspase-12 were significantly downregulated upon curcumin treatment. Furthermore, curcumin administration greatly blocked the protein kinase-like endoplasmic reticulum kinase- (PERK-) eukaryotic translation initiation factor 2α- (eIF2α-) activating transcription factor 4- (ATF4-) CHOP signaling pathway. Curcumin enhanced intestinal epithelial barrier integrity in the in vitro coculture model by upregulating TJ protein expressions and reducing intestinal epithelial cell apoptosis. The potential mechanisms may be suppression of ERS and subsequent apoptosis.

Chlorogenic acid ameliorates Klebsiella pneumoniae-induced pneumonia in immunosuppressed mice via inhibiting the activation of NLRP3 inflammasomes

Chlorogenic acid (CGA) possesses a wide variety of bioactive properties, such as antioxidation, anti-inflammation and anti-bacteria. This study was aimed at exploring the effects of CGA of anti-inflammation and anti-bacteria on mouse pneumonia prepared by immunosuppressed mice infected with Klebsiella pneumoniae (K. pneumoniae) in vivo and the cellular inflammasomes through lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced RAW 264.7 murine macrophages in vitro. Mice received CGA treatment (30 and 90 mg kg^-1) for 8 consecutive days and on the fourth day immunosuppression in mice was induced by cyclophosphamide (40 mg kg^-1) for 5 days before inoculation of K. pneumoniae. Immunosuppressed mice infected with K. pneumoniae developed severe pneumonia, with marked interstitial vascular congestion, widened alveolar intervals, infiltration of monocytes, lymphocytes and macrophages as well as the damage of epithelial architecture, with growing mortality and count forming unit (CFU). CGA treatment significantly decreased the ratio of lung/body weight, reduced the severity of pneumonia induced by K. pneumoniae, decreased the lung injury, inflammatory cell infiltration scores and CD68 protein expression, inhibited the expression of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and elevated the expression of IL-10. Meanwhile, we investigated the mechanism of CGA to counter K. pneumoniae-induced pneumonia and found that CGA remarkably repressed the activation of nucleotide-binding domain like receptor protein 3 (NLRP3) inflammasome. Altogether, our results indicate that the dietary intake of CGA or its rich foods ameliorates K. pneumonia-induced pneumonia by inhibiting the activation of NLRP3 inflammasomes.

Alleviation Effects of Bifidobacterium animalis subsp. lactis XLTG11 on Dextran Sulfate Sodium-Induced Colitis in Mice

Inflammatory bowel disease (IBD) is a chronic immune-related disease, which can occur through the dysfunction of the immune system caused by the imbalance of gut microbiota. Previous studies have reported the beneficial effects of Bifidobacterium on colitis, while the related mechanisms behind these effects have not been fully elucidated. The aim of our study is to investigate the alleviation effect of Bifidobacterium animalis subsp. lactis XLTG11 (B. lactis) on dextran sulfate sodium (DSS)-induced colitis and its potential mechanism. The results showed that B. lactis XLTG11 significantly decreased weight loss, disease activity index score, colon shortening, myeloperoxide activity, spleen weight, and colon tissue damage. Additionally, B. lactis XLTG11 significantly decreased the levels of pro-inflammatory cytokines and increased the level of anti-inflammatory cytokine. Meanwhile, high doses of B. lactis XLTG11 significantly up-regulated the expression of tight junction proteins and inhibited activation of Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MYD88)/nuclear factor-κB (NF-κB) signaling pathway. Furthermore, B. lactis XLTG11 increased the gut microbiota diversity and modulated gut microbiota composition caused by DSS. Moreover, Spearman’s correlation analysis also found that several specific gut microbiota were significantly correlated with colitis-related indicators. These results demonstrated that B. lactis XLTG11 can alleviate DSS-induced colitis by inhibiting the activation of the TLR4/MYD88/NF-κB signaling pathway, regulating inflammatory cytokines, improving intestinal barrier function, and modulating the gut microbiota.

Forsythiae Fructus aqueous extract attenuates cisplatin-induced kaolin consumption (pica) by inhibiting NLRP3 inflammasome activation in rats

The present study was conducted to evaluate the effect of Forsythiae Fructus aqueous extract (FAE) against cisplatin-induced emesis and to explore the antiemetic mechanism of FAE by focusing on NLRP3 inflammasome activation in a rat pica model. Our results showed that FAE significantly ameliorated cisplatin-induced acute and delayed pica in rats. Moreover, FAE improved the gastrointestinal histopathological injury and reduced the levels of serum ROS, IL-1β, and IL-18 in cisplatin-treated rats. In addition, the expressions of NLRP3, ASC, caspase-1, and IL-1β and the colocalization of the NLRP3 with ASC or caspase-1 in rat gastric antrum and ileum were also suppressed by FAE. Taken together, our findings indicate that FAE has a therapeutic effect against CINV, which may be related to its inhibition of the activation of NLRP3 inflammasome.

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.

Curcumin increases heat shock protein 70 expression via different signaling pathways in intestinal epithelial cells

Intestinal inflammation is associated with the integrity of the intestinal epithelium, which forms a physical barrier against noxious luminal substances. Heat shock 70 kDa protein 1A (HSP70), a molecular chaperon that exerts a cytoprotective effect, regulates intestinal integrity. This study investigated the modulation of HSP70 expression by dietary polyphenols, with particular reference to curcumin, in human intestinal Caco-2 cells. Immunoblot analysis demonstrated that among the 21 different polyphenols tested, curcumin most potently increased HSP70 levels in Caco-2 cells without affecting cell viability. Curcumin also increased the phosphorylation of heat shock factor 1 (HSF1), a well-known transcription factor of HSP70. Promoter and qRT-PCR assays indicated that curcumin upregulated Hspa1a levels via transcriptional activation. Pharmacological inhibition of MEK, a mechanistic target of rapamycin, p38 mitogen-activated protein kinase, and phosphatidyl 3-inositol kinase suppressed curcumin-mediated HSP70 expression, whereas HSF1 phosphorylation was sensitive only to MEK inhibition. Taken together, curcumin increases the expression of HSP70 in intestinal Caco-2 cells via transcriptional activation, possibly enhancing cell integrity. The effects exerted by curcumin are regulated by various signaling pathways. Our findings will expectedly contribute to a deeper understanding of the regulation of intestinal HSP70 by dietary components.

Roles of PRR-Mediated Signaling Pathways in the Regulation of Oxidative Stress and Inflammatory Diseases

Oxidative stress is a major contributor to the pathogenesis of various inflammatory diseases. Accumulating evidence has shown that oxidative stress is characterized by the overproduction of reactive oxygen species (ROS). Previous reviews have highlighted inflammatory signaling pathways, biomarkers, molecular targets, and pathogenetic functions mediated by oxidative stress in various diseases. The inflammatory signaling cascades are initiated through the recognition of host cell-derived damage associated molecular patterns (DAMPs) and microorganism-derived pathogen associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). In this review, the effects of PRRs from the Toll-like (TLRs), the retinoic acid-induced gene I (RIG-I)-like receptors (RLRs) and the NOD-like (NLRs) families, and the activation of these signaling pathways in regulating the production of ROS and/or oxidative stress are summarized. Furthermore, important directions for future studies, especially for pathogen-induced signaling pathways through oxidative stress are also reviewed. The present review will highlight potential therapeutic strategies relevant to inflammatory diseases based on the correlations between ROS regulation and PRRs-mediated signaling pathways.

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.

Identification of Tubocapsanolide A as a novel NLRP3 inhibitor for potential treatment of colitis

Increasing evidence have reported that NLRP3 inflammasome has a crucial role in various kinds of immunological diseases including colitis. However, there have only a few drug candidates directly targeting inflammasomes for the therapy of colitis. Here, we first reported that Tubocapsanolide A (TA), a natural small molecule, as a novel inhibitor of NLRP3 inflammasome for the treatment of colitis. TA inhibited the activation of NLRP3 inflammasome and suppressed the secretion of IL-1β and IL-18 in macrophages. Moreover, the ASC oligomerization was inhibited by TA. The assembly of the NLRP3 inflammasome was also restrained by TA, while had little effects on potassium and chloride efflux. Biolayer interferometry analysis showed that TA could directly bind to NLRP3. Importantly, LC-MS/MS analysis further demonstrated that TA covalently bound to the cysteine 514 residue (Cys514) of NLRP3. In vivo experiments showed that TA remarkably ameliorated DSS-induced experimental colitis in mice. However, the protection of TA against DSS-induced experimental colitis was abrogated in NLRP3-deficient (Nlrp3^-/-) mice. Taken together, this study indicates TA as a novel inhibitor of NLRP3, which identifies Cys514 as a novel regulatory site of NLRP3 and suggests TA as a promising candidate compound for the treatment of colitis.

Yu Shi An Chang Fang Ameliorates TNBS-Induced Colitis in Mice by Reducing Inflammatory Response and Protecting the Intestinal Mucosal Barrier

Ulcerative colitis (UC) is an inflammatory bowel disease that is related to the occurrence of colon cancer. This study aimed to investigate the underlying mechanism by which Yu Shi An Chang Fang (YST) treated UC. 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) was used to construct the UC model. The body weight, fecal viscosity, and fecal bleeding of all mice were recorded every day to calculate the DAI value. The pathological changes in colon tissues were observed by hematoxylin-eosin (H&E) staining. The levels of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and myeloperoxidase (MPO) reflecting inflammation and the levels of malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) reflecting oxidative stress in colon tissues were all measured by their assay kits. The mRNA expression of TNF-α, IL-1β, and IL-6 in colon tissues was detected by quantitative reverse transcription-PCR (qRT-PCR). The expression of proteins related to pyroptosis and the colonic mucosal barrier was analyzed by Western blot. As a result, TNBS caused decreases in body weight and colon lengths, triggered serious histological damage, promoted inflammation, oxidative stress, and pyroptosis, and destroyed the colonic mucosal barrier. The above changes caused by TNBS in colitis mice could be partially reversed by YST. In conclusion, YST ameliorates TNBS-induced UC in mice by reducing the inflammatory response and protecting the intestinal mucosal barrier.

Therapeutic implications of inflammasome in inflammatory bowel disease

Inflammatory bowel disease (IBD) remains a persistent health problem with a global burden surging over 6.8 million cases currently. Clinical pathology of IBD is complicated; however, hyperactive inflammatory and immune responses in the gut is shown to be one of the persistent causes of the disease. Human gut inflammasome, the activator of innate immune system is believed to be a primary underlying cause for the pathology and is largely associated with the progression of IBD. To manage IBD, there is a need to fully understand the role of inflammasome activation in IBD. Since inflammasome potentially play a significant role in IBD, systemic modulation of inflammasome may provide an effective therapeutic and clinical approach to control IBD symptoms. In this review, we have focused on this association between IBD and gut inflammasome, and recent advances in the research and therapeutic strategies for IBD. We have discussed inflammasomes and their components, outcomes from the experimental animals and human studies, inflammasome inhibitors, and developments in the inflammasome-targeted therapies for IBD.