NLRP3 inflammasome in colitis and colitis-associated colorectal cancer

Polyphyllin Ⅵ modulates macrophage polarization through autophagy-NLRP3 inflammasome to alleviate inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with a rising global prevalence. If left untreated, it can result in severe complications, including colon cancer. Key factors in IBD pathogenesis include macrophages, NOD-like receptor thermal protein domain associated protein 3 (NLRP3), and autophagy. Polyphyllin Ⅵ (PPⅥ), a metanoidal saponin derived from the traditional Chinese herb Chonglou, exhibits significant anti-inflammatory and anti-cancer properties, making it a compound of considerable therapeutic interest.

PURPOSE

The present study investigated the relevant mechanism of PPⅥ on protecting IBD from the perspective of NLRP3 as well as macrophage immunomodulation and laid a theoretical foundation for the development of novel IBD therapeutic drugs.

METHODS

The IBD mice were prepared by dextran sodium sulfate, and RAW 264.7 inflammatory cells were established through LPS and ATP stimulation. The indicators of macrophage polarization, NLRP3, and autophagy were detected using Western Blot, RT-qPCR, H&E staining, immunofluorescence, and flow cytometry.

RESULTS

PPⅥ can enhance the inflammatory state of LPS-induced RAW264.7 macrophages, which can reduce weight loss, decrease DAI score, increase colon length, reduce oxidative stress, and decrease intestinal epithelial barrier damage, and thus diminish inflammatory injury in DSS-induced IBD mice. PPⅥ can modify intestinal inflammation and injury by modulating macrophage function. The administration of PPⅥ can maintain the balance between M1-type macrophages and M2-type macrophages while regulating the intestinal macrophage polarization via the NLRP3 inflammasome and autophagy through wildtype mice, cells, and Nlrp3-/- mice.

CONCLUSION

PPⅥ can regulate macrophage polarization through autophagic modulation of NLRP3 inflammasome to promote the repair of intestinal epithelial damage and maintain the integrity of the mucosal barrier, which contributes to the attenuation of inflammatory injury in DSS-induced IBD mice and provides a database for the development of novel clinical drugs.

INNOVATIONS

1. This subject discovered the protective effect of PPⅥ on IBD mice. 2. This subject proved that macrophages have an important role in the intestinal protection of PPⅥ in IBD mice, and PPⅥ can inhibit the polarization of M1-type macrophages and promote the polarization of M2-type macrophages. 3. This subject demonstrated that PPⅥ could regulate macrophage polarization through NLRP3 inflammasome and ameliorate intestinal inflammation in vitro, in vivo, and in Nlrp3-/- mice. 4. This subject confirmed that PPⅥ could regulate macrophage polarization to alleviate inflammatory injury by inhibiting NLRP3 inflammasome through modulating autophagy in vitro, in vivo, and the application of inhibitors. 5. This study explored the developmental value of PPⅥ and laid the theoretical foundation for the development of novel therapeutic drugs as well as therapeutic strategies for IBD.

Anti-Inflammatory Effects of Spexin on Acetic Acid‑Induced Colitis in Rats via Modulating the NF-κB/NLRP3 Inflammasome Pathway

Ulcerative colitis is a chronic inflammatory bowel disease characterized by inflammation and ulcers in the lining of the colon and rectum. Spexin is a novel peptide with antioxidant and anti-inflammatory properties. This study aims to elucidate the therapeutic effects and underlying mechanisms of spexin in mitigating acetic acid-induced colitis in rats. Male Sprague Dawley rats were assigned to control (n = 14) and colitis (n = 21) groups. Colitis was induced via 5% acetic acid (AA) administration (1 mL, intrarect). Post-induction, rats received subcutaneous saline (1 mL/kg), spexin (50 µg/kg/day), or oral sulfasalazine (500 mg/kg) for 5 days. Control groups received saline or spexin. After 24 h of the final treatment, colons were evaluated macroscopically, and levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-18 were determined by ELISA, oxidative stress markers myeloperoxidase (MPO), malondialdehyde (MDA) and glutathione (GSH) levels were measured spectrophotometrically and NOD-like receptor pyrin domain-containing 3 (NLRP3), nuclear factor-κB (NF-κB), caspase-1 proteins were analyzed with Western Blot alongside histopathological assessments. Colitis induction significantly elevated macroscopic damage scores, stool consistency, inflammatory cytokines, MDA, MPO, and NLRP3, NF-κB, caspase-1, while reducing GSH levels (p < 0.001-0.01). Microscopic evaluations confirmed increased necrosis, submucosal edema, and inflammatory cell infiltration (p < 0.001). Spexin reversed these effects by enhancing GSH levels (p < 0.01), reducing macroscopic/microscopic scores, cytokines, MDA, and MPO levels (p < 0.05-0.001), and suppressing NLRP3, NF-κB, and caspase-1 activation (p < 0.01-0.001). For the first time that spexin ameluates acetic acid-induced colitis in rats by modulating the NF-κB/NLRP3 signaling pathway, reducing oxidative damage, enhancing antioxidant capacity, and suppressing inflammation.

Inflammasomes and autophagy in cancer: unlocking targeted therapies

This study clarifies the interaction between autophagy and inflammasome within the cancer framework. The inflammasome generates pro-inflammatory cytokines to direct the immune response to pathogens and cellular stressors. Autophagy maintains cellular homeostasis and can either promote or inhibit cancer. These pathways interact to affect tumorigenesis, immune responses, and therapy. Autophagy controls inflammasome activity by affecting cancer pathogenesis and tumor microenvironment inflammation, highlighting novel cancer therapeutic approaches. Recent studies indicate that modulating autophagy and inflammasome pathways can boost anti-cancer immunity, reduce drug-resistance, and improve therapeutic efficacy. Recent studies indicate modulating inflammasome and autophagy pathways can augment anti-cancer immunity, mitigate therapy resistance, and improve treatment efficacy. Cancer research relies on understanding the inflammasome-autophagy relationship to develop targeted therapies that enhance anti-tumor efficacy and reduce inflammatory symptoms. Customized therapies may improve outcomes based on autophagy gene variations and inflammasome polymorphisms. This study investigates autophagy pathways and the inflammasome in tumor immunopathogenesis, cytokine function, and cancer therapeutic strategies, highlighting their significance in cancer biology and treatment.

The intervention of NLRP3 inflammasome inhibitor: oridonin against azoxymethane and dextran sulfate sodium-induced colitis-associated colorectal cancer in male BALB/c mice

Colorectal cancer (CRC) ranks third globally in cancer diagnoses. The dysregulation of the NLRP3 inflammasome is prominently linked to several types of cancers. Oridonin, a principal component of Rabdosia rubescens, exhibits inhibitory activity against NLRP3 and is well-recognized for its diverse pharmacological benefits. However, its role in an animal model of colitis-associated colorectal cancer (CACC) remains unexplored. In the present study, the effectiveness of oridonin was investigated against CACC, developed using azoxymethane (AOM), a tumour initiator, and dextran sulphate sodium (DSS), a tumour promoter, in male BALB/c mice. The two-stage murine model of inflammation-associated cancer was established by administering AOM (10 mg/kg b.w.; i.p., once) followed by DSS (2% w/v) in drinking water (3 cycles, 7 days/cycle). Over a span of 10 weeks, the dose-dependent (2.5, 5, and 10 mg/kg, b.w.; i.p.) effects of oridonin were investigated in BALB/c mice. Oridonin significantly alleviated CACC severity, as evidenced by reduced DAI scores and restored body weight. Moreover, it attenuated surrogate markers of inflammation, including myeloperoxidase, nitrite, plasma LPS, TNF-α, IL-1β, and DNA damage. Histopathological examination revealed diminished tumorigenesis and apoptotic cells, corroborated by reduced Ki-67 and TNF-α, along with increased p53 expression in the colon. Following oridonin treatment, IHC/immunofluorescence analyses demonstrated a significantly reduced expression of the components of NLRP3 inflammasome including NLRP3, ASC-1, and caspase-1. Notably, the high dose of oridonin (10 mg/kg) consistently exhibited significant protective effects against CACC by modulating various molecular targets. Present findings confirmed the potential of oridonin in the protection of colitis-associated colorectal cancer, providing valuable insights into its mechanism of action and clinical significance.

Effect of the arabinogalactan from Ixeris chinensis (Thunb.) Nakai. attenuates DSS-induced colitis and accompanying depression-like behavior

An arabinogalactan (ICPA) was extracted from the medicinal and edible plant Ixeris chinensis (Thunb.) Nakai., and ICPA exhibited excellent immunomodulatory activity. In this research, the impact of ICPA on DSS-induced ulcerative colitis was investigated. The results indicated that ICPA ameliorated the symptoms of colitis mice including loss of body weight, decrease of disease activity index, shortness of colon length and reduction of spleen index that caused by DSS. After treatment with ICPA, inflammatory cell infiltration and crypt loss were alleviated, and the number of goblet epithelial cells was enriched. ICPA inhibited the overproduction of TNF-α, IL-1β, and NLRP3, and promoted the secretion of IL-10 in colon tissues. Meanwhile, the intestinal barrier integrity was restored through increasing the expression of ZO-1 and occludin. ICPA could also regulate the structure of gut microbiota through elevating the abundance of Turicibacter and Bifidobacterium, and decreasing the ratio of Bacteroidetes/Firmicutes. In addition, ICPA improved the depression-like behavior of UC mice, and reduced the expression of proteins NLRP3, GFAP, and Iba-1 in brain tissues. These results suggested ICPA had an alleviative effect on UC and accompanied depression-like behavior, and could be developed as a dietary supplement for the prevention and treatment of UC.

The m6A methyltransferase METTL3 modifies Kcnk6 promoting on inflammation associated carcinogenesis is essential for colon homeostasis and defense system through histone lactylation dependent YTHDF2 binding

Inflammation induces tumor formation and plays a crucial role in tumor progression and prognosis. KCNK6, by regulating K(+) efflux to reduce NLRP3 Inflammasome-induced lung injury, relaxes the aorta. This study aims to elucidate the effects and biological mechanism of KCNK6 in inflammation-associated carcinogenesis, which may be essential for colon homeostasis and the defense system. To induce colitis, mice were given 3.0% Dextran Sodium Sulfate (DSS) in their drinking water for 7 days. The Azoxymethane (AOM) +DSS method was used to induce colon cancer in the mice model. Bone marrow-derived macrophages (BMDM) from Kcnk6-/- mice, AW264.7 cells, and human colon cancer HCT116 and Caco2 cells were used as in vitro models. The loss of Kcnk6 prevented spontaneous colitis and restored mucosal integrity and homeostatic molecules. Additionally, the loss of Kcnk6 reduced the severity of AOM/DSS-induced carcinogenesis. Kcnk6 promoted cell viability and proliferation in HCT-116 or Caco-2 cells. The loss of Kcnk6 inhibited the levels of inflammatory factors in BMDM cells. Kcnk6 accelerated potassium channel activity, inducing NLRP3 inflammasome activation. METTL3-mediated m6A modification increased Kcnk6 stability in a YTHDF2-dependent manner. Histone lactylation activated the transcription of YTHDF2/Kcnk6. Our study revealed the important role of Kcnk6 in inflammation-associated carcinogenesis progression. The m6A methyltransferase METTL3 and histone lactylation increased Kcnk6 stability in a YTHDF2-dependent manner, providing a potential strategy for inflammation-associated carcinogenesis or colorectal cancer therapy.

Therapeutic effect of Sheng Mai San, a traditional Chinese medicine formula, on inflammatory bowel disease via inhibition of NF-κB and NLRP3 inflammasome signaling

Introduction

Inflammatory bowel disease (IBD) is a globally emergent chronic inflammatory disease which commonly requires lifelong care. To date, there remains a pressing need for the discovery of novel anti-inflammatory therapeutic agents against this disease. Sheng Mai San (SMS) is a traditional Chinese medicine prescription with a long history of use for treating Qi and Yin deficiency and recent studies have shown that SMS exhibits anti-inflammatory potential. However, the effects of SMS on the gastrointestinal system remain poorly studied, and its therapeutic potential and underlying molecular mechanisms in IBD have yet to be discovered. In this study, we examined the therapeutic efficacy of SMS in IBD and its anti-inflammatory activity and underlying molecular mechanism, in vivo and in vitro.

Methods

The therapeutic efficacy of SMS in IBD was assessed in the DSS-induced acute colitis mouse model. Body weight, stool consistency, rectal bleeding, colon length, organ coefficient, cytokine levels in colon tissues, infiltration of immune cells, and colon pathology were evaluated. The anti-inflammatory activity of SMS and related molecular mechanisms were further examined in lipopolysaccharide (LPS)-induced macrophages via assessment of pro-inflammatory cytokine secretion and NF-κB, MAPK, STAT3, and NLRP3 signalling.

Results

SMS significantly ameliorated the severity of disease in acute colitis mice, as evidenced by an improvement in disease activity index, colon morphology, and histological damage. Additionally, SMS reduced pro-inflammatory cytokine production and infiltration of immune cells in colon tissues. Furthermore, in LPS-induced macrophages, we demonstrated that SMS significantly inhibited the production of cytokines and suppressed the activation of multiple pro-inflammatory signalling pathways, including NF-κB, MAPK, and STAT3. SMS also abolished NLRP3 inflammasome activation and inhibited subsequent caspase-1 activation and IL-1β secretion, suggesting a new therapeutic target for the treatment of IBD. These mechanistic findings were also confirmed in in vivo assays.

Conclusion

This study presents the anti-inflammatory activity and detailed molecular mechanism of SMS, in vitro and in vivo. Importantly, we highlight for the first time the potential of SMS as an effective therapeutic agent against IBD.

Mechanism of Nicotiflorin in San-Ye-Qing rhizome for anti-inflammatory effect in ulcerative colitis

BACKGROUND

The incidence of ulcerative colitis (UC) is on the rise globally and the development of drugs targeting UC is urgent. Finding the target of action of natural products is important for drug discovery, elucidation of drug action mechanism, and disease mechanism. San-Ye-Qing (SYQ), is an ancient herbal medicine, but whether the powder of its rhizome has pharmacological effects against UC and its mechanism of action are not clear.

PURPOSE

To evaluate the therapeutic effectiveness of rhizome powder of SYQ in treating UC, and conduct an isolation and characterization of the chemical constituents of the powder. Further, screen the most potent compounds among them and determine the potential mechanism for treating UC.

METHODS

In vivo, the therapeutic effect of SYQ's rhizome powder on UC was assessed by mice's body weight, DAI score, colon length, tissue MPO activity, serum inflammatory markers, etc. Additionally, HPLC was used to isolate and identify the specific chemical components of SYQ's rhizome powder. Then, the most effective compounds and their therapeutic targets were analysed and screened in SYQ rhizome powder using network pharmacology, combined with CCK-8 assay, NO release assay and molecular docking assay, in conjunction with CETSA, DARTS, SPR and enzyme activity assay. Finally, the biological effects of the key compound on the targets were validated using Western blot and ELISA.

RESULTS

In vivo, SYQ rhizome powder effectively restored mice's body weight, lowered DAI and pathological score, downregulated the expression of inflammatory biomarkers, and restored colon length, as well as the colonic epithelial and mucus barriers. Afterward, 9 compounds were isolated and identified from the powder of the rhizomes of SYQ by HPLC. Nicotiflorin is the primary compound in SYQ with the highest concentration. According to both CCK-8 and NO release tests, Nicotiflorin is also the most efficacious compound. Combined with network pharmacological prediction, molecular docking analysis, CETSA, DARTS, SPR and enzyme activity assay, Nicotiflorin may ultimately suppress inflammation by targeting p65 and inhibiting the NF-κB pathway, thereby attenuating the activation of NLRP3 inflammasome. To verify this conclusion, Western blot and ELISA experiments were conducted.

CONCLUSIONS

Our results suggest that the extract from SYQ rhizomes has therapeutic properties for UC. Its active ingredient Nicotiflorin exerted potent anti-UC effects by binding to p65 and inhibiting the activation of NF-κB and NLRP3 inflammasomes.

Predictive model using four ferroptosis-related genes accurately predicts gastric cancer prognosis

BACKGROUND

Gastric cancer (GC) is a common malignancy of the digestive system. According to global 2018 cancer data, GC has the fifth-highest incidence and the third-highest fatality rate among malignant tumors. More than 60% of GC are linked to infection with Helicobacter pylori (H. pylori), a gram-negative, active, microaerophilic, and helical bacterium. This parasite induces GC by producing toxic factors, such as cytotoxin-related gene A, vacuolar cytotoxin A, and outer membrane proteins. Ferroptosis, or iron-dependent programmed cell death, has been linked to GC, although there has been little research on the link between H. pylori infection-related GC and ferroptosis.

AIM

To identify coregulated differentially expressed genes among ferroptosis-related genes (FRGs) in GC patients and develop a ferroptosis-related prognostic model with discrimination ability.

METHODS

Gene expression profiles of GC patients and those with H. pylori-associated GC were obtained from The Cancer Genome Atlas and Gene Expression Omnibus (GEO) databases. The FRGs were acquired from the FerrDb database. A ferroptosis-related gene prognostic index (FRGPI) was created using least absolute shrinkage and selection operator-Cox regression. The predictive ability of the FRGPI was validated in the GEO cohort. Finally, we verified the expression of the hub genes and the activity of the ferroptosis inducer FIN56 in GC cell lines and tissues.

RESULTS

Four hub genes were identified (NOX4, MTCH1, GABARAPL2, and SLC2A3) and shown to accurately predict GC and H. pylori-associated GC. The FRGPI based on the hub genes could independently predict GC patient survival; GC patients in the high-risk group had considerably worse overall survival than did those in the low-risk group. The FRGPI was a significant predictor of GC prognosis and was strongly correlated with disease progression. Moreover, the gene expression levels of common immune checkpoint proteins dramatically increased in the high-risk subgroup of the FRGPI cohort. The hub genes were also confirmed to be highly overexpressed in GC cell lines and tissues and were found to be primarily localized at the cell membrane. The ferroptosis inducer FIN56 inhibited GC cell proliferation in a dose-dependent manner.

CONCLUSION

In this study, we developed a predictive model based on four FRGs that can accurately predict the prognosis of GC patients and the efficacy of immunotherapy in this population.

Huang Qin decoction increases SLC6A4 expression and blocks the NFκB-mediated NLRP3/Caspase1/GSDMD pathway to disrupt colitis-associated carcinogenesis

Huang Qin decoction (HQD) is a traditional Chinese medicine formula for treating colitis, but the effects and molecular mechanism of action of HQD in colitis-associated carcinogenesis (CAC) are still unclear. Therefore, we aimed to determine the beneficial effects of HQD on CAC in mice and to reveal the underlying mechanism involved. AOM/DSS was used to induce CAC in mice, and the effects of HQD on tumorigenesis in mice were examined (with mesalazine serving as a positive control). Mesalazine or HQD treatment alleviated body weight loss and decreased the disease activity index in mice induced by AOM/DSS. Mesalazine or HQD treatment also suppressed the shortening of colon tissue length, the number of tumors, and the infiltration of inflammatory cells. The genes targeted by HQD were predicted and verified, followed by knockout experiments. Elevated SLC6A4 and inhibited serotonin production and inflammation were observed in HQD-treated mice. HQD inhibited the NFκB and NLRP3/caspase1/GSDMD pathways. The therapeutic effect of HQD was diminished in SLC6A4-deficient AOM/DSS mice. Additionally, the downregulation of SLC6A4 mitigated the inhibitory effect of HQD-containing serum on MODE-K cell pyroptosis. Our findings suggest that SLC6A4 is a pivotal regulator of HQD-alleviated CAC via its modulation of the NLRP3/caspase1/GSDMD pathway.

USP50 regulates NLRP3 inflammasome activation in duodenogastric reflux-induced gastric tumorigenesis

Duodenogastric reflux (DGR) has been linked to the onset of gastric cancer (GC), although the precise mechanism is yet obscure. Herein, we aimed to investigate how refluxed bile acids (BAs) and macrophages are involved in gastric carcinogenesis. In both active human bile reflux gastritis and the murine DGR model, ubiquitin specific protease 50 (USP50) was dramatically raised, and macrophages were the principal leukocyte subset that upregulated USP50 expression. Enhancing USP50 expression amplified bile acid-induced NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and subsequent high-mobility group box protein 1 (HMGB1) release, while USP50 deficiency resulted in the reversed alteration. Mechanistically, USP50 interacted with and deubiquitinated apoptosis-associated speck-like protein containing CARD (ASC) to activate NLRP3 inflammasome. The release of HMGB1 contributes to gastric tumorigenesis by PI3K/AKT and MAPK/ERK pathways. These results may provide new insights into bile reflux-related gastric carcinogenesis and options for the prevention of DGR-associated GC.

Management of ulcerative colitis by dichloroacetate: Impact on NFATC1/NLRP3/IL1B signaling based on bioinformatics analysis combined with in vivo experimental verification

The inflammatory response in ulcerative colitis (UC) could be relieved by the conventional immunomodulatory agents; 5-aminosalicylic acid, corticosteroids, or azathioprine. However, the low remission rates and the intolerance to these agents necessitate investigation of gene expression signature in UC that could influence the therapeutic efficacy of drugs, as well as the interference with persistence genes by novel therapeutic option. Three microarray datasets (GSE66407, GSE38713 and GSE14580) from the NCBI-GEO database were utilized. Differentially expressed genes between samples of patients with UC and healthy ones were analyzed using R software. In addition, in vivo study using oxazolone-induced UC in BALB/c mice was carried out to investigate the proposed therapeutic efficacy of dichloroacetate (DCA). The bioinformatics analysis revealed the persistence of NLRP3, NFATC1, and IL1B in UC despite treatment with common therapeutic agents. DCA administration to oxazolone-treated mice showed remarkable interference with those persistence genes. Western blotting analysis for NLRP3, NFATC1, nuclear/total NF-κB, and cleaved caspase-1 revealed the ability of DCA to reduce the expression levels of these proteins in oxazolone-treated mice. Additionally, the inflammatory cytokines IL-1β and IL-13 were reduced in colonic tissue by DCA treatment. The therapeutic efficacy of DCA was further confirmed by the apparent reduction in histopathological scoring, disease activity index, and the normalization of colon length. Therefore, DCA could be suggested as a novel and promising therapeutic option in UC based on its ability to interfere with the persistence of NFATC1/NLRP3/IL1B signaling. That merits further safety/toxicological pre-clinical assessment and update of bioavailability/metabolism data prior to clinical investigation.

Knockdown of LRRK2 inhibits the progression of lung cancer by regulating TLR4/NF-κB pathways and NLRP3 inflammasome

Leucine-rich repeat kinase 2 (LRRK2) plays an important role in a variety of inflammatory diseases, as well as peripheral and central immune responses. At present, there are few reports about the role of LRRK2 in lung cancer, and need to be further explored. The main purpose of this study is to explore the role and mechanism of LRRK2 in lung cancer. The results revealed that the expression of LRRK2 was increased in the tissues of lung cancer patient and lung cancer cells. Further studies found that interference with LRRK2 expression significantly induced the apoptosis, and promoted the expression of caspase-3, caspase-9, and Bax. More importantly, si-LRRK2 inhibited the expression of VEGF and P-gp, indicating inhibition of cell proliferation and drug resistance. What's more, LRRK2 regulated TLR4/NF-κB signaling pathways and NLRP3 inflammasome, and TLR4/NF-κB pathways was involved in the molecular mechanism of LRRK2 on lung cancer cells. In conclusion, this study suggested that the mechanism of si-LRRK2 inhibiting the progression of lung cancer is to regulate the TLR4/NF-κB signaling pathways and NLRP3 inflammasome.

Role of NLRP3 inflammasome activation in HCC cell progression

Hepatocellular carcinoma (HCC) is a globally prevalent and fatal malignancy worldwide, and identifying therapeutic strategies is time-consuming. Numerous reports have suggested the involvement of the NLRP3 inflammasome in the progression of various cancers. However, the detailed mechanisms underlying the role of NLRP3 inflammasome in HCC progression remain unclear. In this study, we observed low expression levels of the NLRP3 inflammasome in a subset of HCC cells. Furthermore, we demonstrated that the NLRP3 inflammasome can be activated by LPS + ATP through the nuclear factor kappa B signaling pathway, as confirmed by western blotting and immunofluorescence staining. To assess the impact of NLRP3 inflammasome activation on HCC cell behavior, we employed Edu staining, cell cycle assay, Annexin V/PI staining, and wound healing assay. Our results revealed that NLRP3 inflammasome activation inhibited the proliferation of Bel-7402 and SMMC-7721 cells, arrested the cell cycle at the G1 phase, and suppressed cell migration, while apoptosis remained unaffected. In summary, our findings suggest that targeting the NLRP3 inflammasome could have therapeutic potential for HCC.

Oral intake of titanium dioxide nanoparticles affect the course and prognosis of ulcerative colitis in mice: involvement of the ROS-TXNIP-NLRP3 inflammasome pathway

BACKGROUND

Titanium dioxide (TiO2), no matter in nanoscale or micron sizes, has been widely used in food industry as additives for decades. Given the potential impact of TiO2 on the gastrointestinal epithelial and parenchymal cells, including goblet cells, the public consumers may suffer the risk of diseases caused by its widespread dissemination in food products. We therefore set out to investigate the impact of TiO2 NPs on the course and prognosis of ulcerative colitis by oral gavaging TiO2 NPs at the doses levels of 0, 30, 100, and 300 mg/kg during the induction (7 days, from day 1 to day 7) and recovery (10 days, from day 8 to day 17) phases of colitis in mice.

RESULTS

The ulcerative colitis (UC) disease model was established by administrating of 2.5% dextran sulfate sodium (DSS) solution. Our results show that TiO2 NPs significantly enhanced the severity of DSS-induced colitis, decreased the body weight, increased the disease activity index (DAI) and colonic mucosa damage index (CMDI) scores, shortened the colonic length, increased the inflammatory infiltration in the colon. The most significant changes occurred in the low dose (30 mg/kg) group of TiO2 NPs exposure during the development phase of UC and the high dose (300 mg/kg) group of TiO2 NPs during UC self-healing phase. Increased reactive oxygen species (ROS) level and upregulation of anti-oxidant enzymes including total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX) and catalase (CAT), demonstrate that the TiO2 NP exposure has triggered oxidative stress in mice. Moreover, the upregulation of caspase-1 mRNA and increased expression of thioredoxin interacting protein (TXNIP) further demonstrate the involvement of the ROS-TXNIP-NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in aggravating the development of UC.

CONCLUSION

Oral intake of TiO2 NPs could affect the course of acute colitis in exacerbating the development of UC, prolonging the UC course and inhibiting UC recovery.

Identification of Novel Core Genes Involved in Malignant Transformation of Inflamed Colon Tissue Using a Computational Biology Approach and Verification in Murine Models

Inflammatory bowel disease (IBD) is a complex and multifactorial systemic disorder of the gastrointestinal tract and is strongly associated with the development of colorectal cancer. Despite extensive studies of IBD pathogenesis, the molecular mechanism of colitis-driven tumorigenesis is not yet fully understood. In the current animal-based study, we report a comprehensive bioinformatics analysis of multiple transcriptomics datasets from the colon tissue of mice with acute colitis and colitis-associated cancer (CAC). We performed intersection of differentially expressed genes (DEGs), their functional annotation, reconstruction, and topology analysis of gene association networks, which, when combined with the text mining approach, revealed that a set of key overexpressed genes involved in the regulation of colitis (C3, Tyrobp, Mmp3, Mmp9, Timp1) and CAC (Timp1, Adam8, Mmp7, Mmp13) occupied hub positions within explored colitis- and CAC-related regulomes. Further validation of obtained data in murine models of dextran sulfate sodium (DSS)-induced colitis and azoxymethane/DSS-stimulated CAC fully confirmed the association of revealed hub genes with inflammatory and malignant lesions of colon tissue and demonstrated that genes encoding matrix metalloproteinases (acute colitis: Mmp3, Mmp9; CAC: Mmp7, Mmp13) can be used as a novel prognostic signature for colorectal neoplasia in IBD. Finally, using publicly available transcriptomics data, translational bridge interconnecting of listed colitis/CAC-associated core genes with the pathogenesis of ulcerative colitis, Crohn's disease, and colorectal cancer in humans was identified. Taken together, a set of key genes playing a core function in colon inflammation and CAC was revealed, which can serve both as promising molecular markers and therapeutic targets to control IBD and IBD-associated colorectal neoplasia.

The Multifaceted Role and Regulation of Nlrp3 Inflammasome in Colitis-Associated Colo-Rectal Cancer: A Systematic Review

Colitis-associated colo-rectal cancer remains the leading cause of mortality in inflammatory bowel diseases, with inflammation remaining one of the bridging points between the two pathologies. The NLRP3 inflammasome complex plays an important role in innate immunity; however, its misregulation can be responsible for the apparition of various pathologies such as ulcerative colitis. Our review focuses on the potential pathways of upregulation or downregulation of the NLRP3 complex, in addition to evaluating its role in the current clinical setting. Eighteen studies highlighted the potential pathways of NLRP3 complex regulation as well as its role in the metastatic process in colo-rectal cancer, with promising results. Further research is, however, needed in order to validate the results in a clinical setting.

The role of NLRP3 inflammasome in digestive system malignancy

Digestive system malignancies, the most common types of cancer and a major cause of death in the worldwide, are generally characterized by high morbidity, insidious symptoms and poor prognosis. NLRP3 inflammasome, the most studied inflammasome member, is considered to be crucial in tumorigenesis. In this paper, we reviewed its pro-tumorigenic and anti-tumorigenic properties in different types of digestive system malignancy depending on the types of cells, tissues and organs involved, which would provide promising avenue for exploring new anti-cancer therapies.

The employment of vaccinia virus for colorectal cancer treatment: A review of preclinical and clinical studies

Colorectal cancer (CRC) is one of the leading malignancies that causes death worldwide. Cancer vaccines and oncolytic immunotherapy bring new hope for patients with advanced CRC. The capability of vaccinia virus (VV) in carrying foreign genes as antigens or immunostimulatory factors has been demonstrated in animal models. VV of Wyeth, Western Reserve, Lister, Tian Tan, and Copenhagen strains have been engineered for the induction of antitumor response in multiple cancers. This paper summarized the preclinical and clinical application and development of VV serving as cancer vaccines and oncolytic vectors in CRC treatment. Additionally, the remaining challenges and future direction are also discussed.

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.

Shuanghua decoction exerts anticancer activity by activating NLRP3 inflammasome via ROS and inhibiting NF-κB signaling in hepatocellular carcinoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is a major subtype of liver cancer, with a high mortality rate, and close relation to chronic hepatitis. The components of the NLRP3 inflammasome are poorly expressed or even lost in HCC. Downregulation of the NLRP3 inflammasome expression significantly affects the clinical stages and pathological grade of HCC. According to previous research, Shuanghua decoction (SHD), a traditional folk prescription, has an inhibitory effect on nasopharyngeal cancer.

PURPOSE

This study aimed to reveal the therapeutic potential of the traditional folk recipe, SHD and its demolition recipe for HCC, and to explore the underlying mechanism.

METHODS

The effect of SHD and its demolition recipe on HCC cell biological behaviors was assessed using the MTT assay, colony formation, LDH release assay, KFluor-Edu staining, annexin V-FITC/PI staining assay, Hoechst staining, wound-healing assay, transwell assay, reactive oxygen species (ROS) release assay, HPLC, nude mice model, HE staining, IHC, western blot, and immunofluorescence staining in vitro and in vivo.

RESULTS

SHD was found to inhibit HCC, and Oldenlandia and OP (Oldenlandia: Prunella spike = 2.5:1) were identified as the main ingredients that inhibited the proliferation and migration of HCC cells via the activation of the ROS-mediated NLRP3 inflammasome and inhibition of the NF-κB signaling pathway in vitro and in vivo.

CONCLUSION

Overall, Chinese medicine theory and pharmacology research revealed that SHD, Oldenlandia and OP may be promising traditional Chinese medicine for the treatment of HCC.

Investigating the Role of the NLRP3 Inflammasome Pathway in Acute Intestinal Inflammation: Use of THP-1 Knockout Cell Lines in an Advanced Triple Culture Model

The NLRP3 inflammasome plays an important role in intestinal homeostasis as well as inflammation. However, in vivo studies investigating the role of the NLRP3 inflammasome in inflammatory bowel disease (IBD) report contrasting results, leaving it unclear if the NLRP3 inflammasome augments or attenuates intestinal inflammation. To investigate the role of the NLRP3/caspase-1 pathway in a model of acute intestinal inflammation, we modified a previously established in vitro triple culture model of the healthy and inflamed intestine (Caco-2/HT29-MTX-E12/THP-1). Using THP-1 knockout cell lines, we analyzed how the NLRP3 inflammasome and its downstream enzyme caspase-1 (CASP1) affect inflammatory parameters including barrier integrity and cytotoxicity, as well as gene expression and secretion of pro-inflammatory cytokines and mucus. Furthermore, we investigated differences in inflammation-mediated cytotoxicity towards enterocyte-like (Caco-2) or goblet-like (HT29-MTX-E12) epithelial cells. As a complementary approach, inflammation-related cytotoxicity and gene expression of cytokines was analyzed in intestinal tissue explants from wildtype (WT) and Nlrp3^-/- mice. Induction of intestinal inflammation impaired the barrier, caused cytotoxicity, and altered gene expression of pro-inflammatory cytokines and mucins in vitro, while the knockout of NLRP3 and CASP1 in THP 1 cells led to attenuation of these inflammatory parameters. The knockout of CASP1 tended to show a slightly stronger attenuating effect compared to the NLRP3 knockout model. We also found that the inflammation-mediated death of goblet-like cells is NLRP3/caspase-1 dependent. Furthermore, inflammation-related cytotoxicity and upregulation of pro-inflammatory cytokines was present in ileal tissue explants from WT, but not Nlrp3^-/- mice. The here presented observations indicate a pro-inflammatory and adverse role of the NLRP3 inflammasome in macrophages during acute intestinal inflammation.

Comparison of Selenium-Enriched Lactobacillusparacasei, Selenium-Enriched Yeast, and Selenite for the Alleviation of DSS-Induced Colitis in Mice

Patients with inflammatory bowel disease (IBD) have been found to have decreased immune function. Selenium (Se) is an essential trace element that is beneficial for human health, which has a significant stimulating effect on immune function. We compared the effects of different Se forms on the alleviation of colitis in DSS-induced mice. Moreover, we also aimed to determine whether Se-enriched Lactobacillus paracasei CCFM 1089 could be used as a new organic Se supplement. Different Se supplements (Se-enriched L. paracasei CCFM 1089, Se-enriched yeast and sodium selenite) were given to Se-deficient mice suffering from colitis. Se-enriched L. paracasei CCFM 1089, which is based on selenocysteine (SeCys), had similar effects in terms of reducing oxidative stress and inhibiting pro-inflammatory factors to Se-enriched yeast; however, selenase activity in the Se-enriched L. paracasei CCFM 1089-treated mice was higher than that in other treatment groups. In addition, Se-enriched L. paracasei CCFM 1089 could better protect the intestinal mucosa, which increased the expression of tight junction proteins (ZO-1 and occludin) in mice. Thus Se-enriched L. paracasei CCFM 1089 was shown to alleviate IBD, suggesting that it has potential as a good organic Se supplement.

The Pro-tumor and Anti-tumor Effects of NLRP3 Inflammasome as a New Therapeutic Option for Colon Cancer: a Meta-analysis of Pre-clinical Studies

In this review, we aimed to elaborate on these findings and explore how NLRP3 inflammasome affects CRC and which mechanism could be a potential therapeutic target. For this purpose, major indexing databases consist of Cochrane central, ISI web of science (WOS), PubMed/Medline, Scopus, and EMBASE were systematically searched using standard terms without any language, study region, or type restrictions. After applying the exclusion criteria, the main properties of 12 articles on 326 animals included in this meta-analysis. Of 12, eight were about an anti-tumoral effect, and four were on a pro-tumoral effect of the inflammasome. NLRP3 inhibition reduced IL-1β (SMD: -4.14, 95% CI: -5.49, -2.79, P < 0.00001, I² = 76%), TNFα (SMD: -2.18, 95% CI: -3.23, -1.13, P < 0.00001, I² = 82%), and IL-18 (SMD: -2.27, 95% CI: -3.38, -1.16, P = 0.0002, I² = 74%) significantly contrasted with the model controls. Colons harvested from NLRP3 inhibition groups showed significant truncation compared with the model controls (SMD: -1.75, 95% CI: -2.69, -0.81, P = 0.0003, I² = 60%). We demonstrated significantly decreased tumorigenesis following NLRP3 inactivation, as well as an increased survival rate compared with the model controls. To translate anti-cancer agents based on anti-NLRP3 from bench to bedside, it is necessary to identify the molecules that selectively target NLRP3 or its downstream pathways in malignant cells, as well as considering metabolic heterogeneity and the mechanisms causing such cancer-connected heterogeneity. Other studies are needed to separate the molecular and functional complexity of this network.SummarySecretion of IL-1β is contingent upon activation of the inflammasome complex of NLRP3. It has been suggested that activation of this complex necessitates two signals. One of these signals is made available by activation of toll-like-receptor (TLR)-mediated NF-kappa and actuates the IL-1β precursor synthesis and NLRP3 assembly. Another signal is conceivable to be mediated by hazard signals e.g., the purinergic P2X7 receptor stimulated by Adenosine triphosphate or other stimuli resulting in the efflux of potassium.

Innate Immune Responses in Pediatric Patients with Gastritis—A Trademark of Infection or Chronic Inflammation?

The aim of this study was to define the relationship between several environmental, laboratory, and genetic factors, i.e., TLR2 and NLRP3 polymorphisms, and Helicobacter pylori (H. pylori) infection in children, by comparing three different groups of pediatric subjects: H. pylori-induced gastritis, non-H. pylori gastritis, and healthy controls. Our final study sample included 269 children, which were divided into three groups according to the histopathological exam: group 1 with 51 children with H. pylori-induced gastritis, group 2 with 103 children with H. pylori-negative gastritis, and group 3 (control group) with 115 children without any histopathological changes. All children underwent a thorough anamnesis, clinical exam, laboratory tests, and upper digestive endoscopy with gastric biopsy for rapid urease test, histopathological exam, and genetic analysis of TLR2 rs3804099, TLR2 rs3804100, and NLRP3 rs10754558 gene polymorphisms. We noticed a significant association between living conditions and the type of gastritis (p < 0.0001). Both rapid urease and serological tests were significantly associated with the presence of H. pylori (p < 0.0001). The CT variant genotype of TLR2 rs380499 was significantly associated with neutrophil count (p = 0.0325). We noticed a significant association between the CC variant genotype of NLRP3 rs10754558 and leucocytes, neutrophils, eosinophils, as well as ALT (p = 0.0185, p = 0.0379, p = 0.0483, p = 0.0356). Based on these findings, we state that poor living conditions and rural areas represent risk factors for H. pylori infection. The rapid urease test is a reliable diagnostic tool for this infection. CT and TT carriers of TLR2 rs3804099, as well as CC carriers of NLRP3 rs10754558, might display a more severe degree of systemic inflammation.

Supplementary selenium in the form of selenylation α-D-1,6-glucan ameliorates dextran sulfate sodium induced colitis in vivo

The deficiency of selenium has been found in clinical IBD patients and supplementation selenium is recognized as beneficial for colitis treatment. In this study, an organic selenium compound-selenylation α-D-1,6-glucan (sCPA) was prepared, and the effect of sCPA on DSS induced colitis mice was investigated. The results suggested that sCPA prevented the weight loss, colon length shortening, and stool loose of colitis mice. It protected colon mucosal barrier by promoting tight junction protein ZO-1 and Occludin expression. Moreover, sCPA reduced oxidative stress via regulating SOD and MDA levels, and decreased the contents of inflammatory proteins NF-κB and NLRP3 and adjusted TNF-α, IFN-γ, IL-1β, and IL-10 inflammatory cytokines. Furthermore, sCPA repaired intestinal microbiota composition especially Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria that altered by DSS in colitis mice. Meanwhile, SCFAs produced by gut microbiota were restored by sCPA close to the level in the normal group. In conclusion, these findings indicated that the sCPA might be a potential dietary selenium supplementation for the prevention and treatment of colitis.

Interruption of Helicobacter pylori-Induced NLRP3 Inflammasome Activation by Chalcone Derivatives

Helicobacter pylori causes chronic gastritis through cag pathogenicity island (cagPAI), vacuolating cytotoxin A (VacA), lipopolysaccharides (LPS), and flagellin as pathogen-related molecular patterns (PAMPs), which, in combination with the pattern recognition receptors (PRRs) of host cells promotes the expression and secretion of inflammation-causing cytokines and activates innate immune responses such as inflammasomes. To identify useful compounds against H. pylori-associated gastric disorders, the effect of chalcone derivatives to activate the nucleotide-binding oligomerization domain (NOD)-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome was examined in an H. pylori-infected human monocytic THP-1 cell line in this study. Among the five synthetic structurally-related chalcone derivatives examined, 2'-hydroxy-4',6'-dimethoxychalcone (8) and 2'-hydroxy-3,4,5- trimethoxychalcone (12) strongly blocked the NLRP3 inflammasome in H. pylori-infected THP-1 cells. At 10 μM, these compounds inhibited the production of active IL-1β, IL-18, and caspase-1, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomerization, but did not affect the expression levels of NLRP3, ASC, and pro-caspase-1. The interruption of NLRP3 inflammasome activation by these compounds was found to be mediated via the inhibition of the interleukin-1 receptor-associated kinase 4 (IRAK4)/IκBα/NF-κB signaling pathway. These compounds also inhibited caspase-4 production associated with non-canonical NLRP3 inflammasome activation. These results show for the first time that certain chalcones could interrupt the activation of the NLRP3 inflammasome in H. pylori-infected THP-1 cells. Therefore, these chalcones may be helpful in alleviating H. pylori-related inflammatory disorders including chronic gastritis.

NLRP3 induces the autocrine secretion of IL-1β to promote epithelial-mesenchymal transition and metastasis in breast cancer

Tumor metastasis is a leading cause of mortality in patients with breast cancer (BC). As a predominant component of inflammasome, Nod-like receptor protein 3 (NLRP3) was found to be required for tumor progression, while the role of NLRP3 in BC metastasis remains largely undefined. In current study, we found that invasive BC had aberrant upregulation of NLRP3 expression, especially in the claudin-low subtype. And higher expression of NLRP3 predicted poor survival of BC patients. Further investigation suggested that NLRP3 promotes the migration and invasion, as well as the metastasis of BC cells. Moreover, we revealed that NLRP3 induces the autocrine secretion of IL-1β to promote epithelial-mesenchymal transition via a Caspase-1-dependent manner. Hence, this study suggested that upregulation of NLRP3 in BC induces the autocrine secretion of IL-1β and promotes EMT and metastasis of BC cells.

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.

NLRP3 Promotes Colorectal Cancer Cell Proliferation and Metastasis via Regulating Epithelial Mesenchymal Transformation

BACKGROUND

Nucleotide-binding domain Leucine-rich Repeat Protein 3 (NLRP3) plays a regulatory role in the immune and inflammatory responses, and has been implicated in Colorectal Cancer (CRC) progression and metastasis. However, the underlying molecular mechanisms have not been fully elucidated.

METHODS

In this study, we analyzed the expression levels of NLRP3 in human CRC tissues, and performed functional assays in CRC cell lines and a subcutaneous tumor model to elucidate its role in the development and progression of CRC.

RESULTS

In this study, we found that NLRP3 was significantly upregulated in human CRC tissues and was associated with tumor size and invasion, lymph node metastasis, venous invasion, neural invasion and TNM staging. Furthermore, knockdown of NLRP3 in CRC cells inhibited their migration and growth in vitro and in vivo, and reversed Epithelial-Mesenchymal Transition (EMT) in vitro.

CONCLUSION

Our findings indicate that NLRP3 likely regulates CRC metastasis by activating the EMT program, and is a potential therapeutic target.

Targeting the NLRP3 Inflammasome as a New Therapeutic Option for Overcoming Cancer

Inflammasomes are multiprotein complexes that regulate the maturation and secretion of the proinflammatory cytokines interleukin-1beta (IL-1β and interleukin-18 (IL-18) in response to various intracellular stimuli. As a member of the inflammasomes family, NLRP3 is the most studied and best characterized inflammasome and has been shown to be involved in several pathologies. Recent findings have made it increasingly apparent that the NLRP3 inflammasome may also play a central role in tumorigenesis, and it has attracted attention as a potential anticancer therapy target. In this review, we discuss the role of NLRP3 in the development and progression of cancer, offering a detailed summary of NLRP3 inflammasome activation (and inhibition) in the pathogenesis of various forms of cancer. Moreover, we focus on the therapeutic potential of targeting NLRP3 for cancer therapy, emphasizing how understanding NLRP3 inflammasome-dependent cancer mechanisms might guide the development of new drugs that target the inflammatory response of tumor-associated cells.

Low NLRP3 expression predicts a better prognosis of colorectal cancer

Background: NOD-like receptor pyrin domain-3 (NLRP3) inflammasome activation is a double-edged sword in tumorigenesis. Whether NLRP3 is involved in the progression and prognosis of colorectal cancer (CRC) remains elucidated and is the focus of the present study.

Methods: Immunohistochemistry (IHC) was applied on tissue microarray (TMA) to determine the expression of NLRP3 in CRC patients. All 100 patients were divided into the low NLRP3 group and the high NLRP3 group according to their NLRP3 IHC scoring. Additionally, CRC xenografts were established by injecting HCT116 or RKO cells subcutaneously into nude mice. Cell proliferation and apoptosis were determined in HCT116 cells after treatment with NLRP3 inhibitor MCC950.

Results: NLRP3 expression was up-regulated in colon adenocarcinoma tissues compared with that in paracancerous tissues in CRC patients, HCT116 xenograft, and RKO xenograft. High NLRP3 level correlated with the advanced TNM classification of malignant tumors, the occurrence of distant metastasis, vascular invasion, and positive lymph nodes. Furthermore, Kaplan–Meier survival analysis revealed that a high NLRP3 level was associated with a low 5-year survival rate and even a low 10-year survival rate. Moreover, the multivariable Cox proportional hazards regression model implied that NLRP3 expression level was an independent risk factor for CRC prognosis. Inhibition of NLRP3 by MCC950 suppressed cell proliferation, induced cell apoptosis, and decreased mRNA levels of interleukin 1β (IL1β) and interleukin 18 (IL18) in HCT116 cells.

Conclusions: High level of NLRP3 predicts poor survival in CRC patients. NLRP3 is a putative prognostic biomarker and a potential therapeutic target in CRC treatments.

Hyperpolarized 13 C magnetic resonance imaging for noninvasive assessment of tissue inflammation

Inflammation is a central mechanism underlying numerous diseases and incorporates multiple known and potential future therapeutic targets. However, progress in developing novel immunomodulatory therapies has been slowed by a need for improvement in noninvasive biomarkers to accurately monitor the initiation, development and resolution of immune responses as well as their response to therapies. Hyperpolarized magnetic resonance imaging (MRI) is an emerging molecular imaging technique with the potential to assess immune cell responses by exploiting characteristic metabolic reprogramming in activated immune cells to support their function. Using specific metabolic tracers, hyperpolarized MRI can be used to produce detailed images of tissues producing lactate, a key metabolic signature in activated immune cells. This method has the potential to further our understanding of inflammatory processes across different diseases in human subjects as well as in preclinical models. This review discusses the application of hyperpolarized MRI to the imaging of inflammation, as well as the progress made towards the clinical translation of this emerging technique.

Specific NLRP3 inflammasome inhibitors: promising therapeutic agents for inflammatory diseases

Innate immunity serves as a first line of defence against danger signals, invading pathogens and microbes. The inflammasomes, as pattern recognition receptors, sense these danger signals to initiate pro-inflammatory cascades. The nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3) inflammasome is the most well characterised inflammasome, and its aberrant activation is implicated in many inflammatory diseases. In the past decade, targeting the NLRP3 inflammasome has become an emerging strategy for inflammatory diseases. To avoid off-target immunosuppressive effects, specific NLRP3 inhibitors have been developed and show promising therapeutic effects. This review discusses the therapeutic effects and clinical perspectives of specific NLRP3 inhibitors, as well as recent progress in the development of these inhibitors for the treatment of inflammatory diseases.

Role of the NLRP3 Inflammasome: Insights Into Cancer Hallmarks

In response to a variety of stresses, mammalian cells activate the inflammasome for targeted caspase-dependent pyroptosis. The research community has recently begun to deduce that the activation of inflammasome is instigated by several known oncogenic stresses and metabolic perturbations; nevertheless, the role of inflammasomes in the context of cancer biology is less understood. In manipulating the expression of inflammasome, researchers have found that NLRP3 serves as a deterministic player in conducting tumor fate decisions. Understanding the mechanistic underpinning of pro-tumorigenic and anti-tumorigenic pathways might elucidate novel therapeutic onco-targets, thereby providing new opportunities to manipulate inflammasome in augmenting the anti-tumorigenic activity to prevent tumor expansion and achieve metastatic control. Accordingly, this review aims to decode the complexity of NLRP3, whereby summarizing and clustering findings into cancer hallmarks and tissue contexts may expedite consensus and underscore the potential of the inflammasome in drug translation.

Rab GTPase Mediating Regulation of NALP3 in Colorectal Cancer

The NALP3 inflammasome signaling contributes to inflammation within tumor tissues. This inflammation may be promoted by the vesicle trafficking of inflammasome components and cytokines. Rab5, Rab7 and Rab11 regulate vesicle trafficking. However, the role of these proteins in the regulation of inflammasomes remains largely unknown. To elucidate the role of these Rab proteins in inflammasome regulation, HCT-116, a colorectal cancer (CRC) cell line expressing pDsRed-Rab5 wild type (WT), pDsRed-Rab5 dominant-negative (DN), pDsRed-Rab7 WT, pDsRed-Rab7 DN, pDsRed-Rab11 WT and pDsRed-Rab11 DN were treated with lipopolysaccharide (LPS)/nigericin. Inflammasome activation was analyzed by measuring the mRNA expression of NLRP3, Pro-CASP1, RAB39A and Pro-IL-1β, conducting immunofluorescence imaging and western blotting of caspase-1 and analysing the secretion levels of IL-1β using enzyme-linked immunosorbent assay (ELISA). The effects of Rabs on cytokine release were evaluated using MILLIPLEX MAP Human Cytokine/Chemokine Magnetic Bead Panel-Premixed 41 Plex. The findings showed that LPS/nigericin-treated cells expressing Rab5-WT indicated increased NALP3 expression and secretion of the IL-1β as compared to Rab5-DN cells. Caspase-1 was localized in the nucleus and cytosol of Rab5-WT cells but was localized in the cytosol in Rab5-DN cells. There were no any effects of Rab7 and Rab11 expression on the regulation of inflammasomes. Our results suggest that Rab5 may be a potential target for the regulation of NALP3 in the treatment of the CRC inflammation.

Recent insights on modulation of inflammasomes by adipokines: a critical event for the pathogenesis of obesity and metabolism-associated diseases

Aberrant production of adipokines, a group of adipocytes-derived hormones, is considered one of the most important pathological characteristics of obesity. In individuals with obesity, beneficial adipokines, such as adiponectin are downregulated, whereas leptin and other pro-inflammatory adipokines are highly upregulated. Hence, the imbalance in levels of these adipokines is thought to promote the development of obesity-linked complications. However, the mechanisms by which adipokines contribute to the pathogenesis of various diseases have not been clearly understood. Inflammasomes represent key signaling platform that triggers the inflammatory and immune responses through the processing of the interleukin family of pro-inflammatory cytokines in a caspase-1-dependent manner. Beyond their traditional function as a component of the innate immune system, inflammasomes have been recently integrated into the pathological process of multiple metabolism- and obesity-related disorders such as cardiovascular diseases, diabetes, fatty liver disease, and cancer. Interestingly, emerging evidence also highlights the role of adipokines in the modulation of inflammasomes activation, making it a promising mechanism underlying distinct biological actions of adipokines in diseases driven by inflammation and metabolic disorders. In this review, we summarize the effects of adipokines, in particular adiponectin, leptin, visfatin and apelin, on inflammasomes activation and their implications in the pathophysiology of obesity-linked complications.

Dietary intake of fermented kimchi prevented colitis-associated cancer

Kimchi is composed of various chemopreventive phytochemicals and profuse probiotics, defining kimchi as probiotic foods. Concerns had increased on the modulation of intestinal microbiota on various kinds of systemic diseases. Under the hypothesis that dietary intake of kimchi can be ideal intervention for either ameliorating colitis or preventing colitic cancer, we performed the study to validate the efficolitic cancery of fermented kimchi on preventing colitic cancer. Using azoxymethane-initiated and dextran sulfate sodium-promoted colitic cancer models, we have administrated fermented or non-fermented kimchi to modulate colitic cancer preemptively. Detailed molecular mechanisms were explored. Preemptive administration of fermented kimchi significantly afforded colitic cancer prevention through attenuating inflammasomes (IL-18, IL-1β, caspase-1), enhancing antioxidative (NQO1, GST-π), imposing anti-proliferative (Bax, caspase-3, β-catenin), and affording cytoprotective actions (HSP70, 15-PGDH), while non-fermented kimchi did not prevent colitic cancer. Special recipe cancer preventive kimchi (cpkimchi) was more effective compared to standard recipe fermented kimchi (p<0.01), while non-fermented kimchi (kimuchi) worsened colitic cancer development, telling the importance of fermentation in cancer prevention. Repression of NF-kB p65, induction of tumor suppressive 15-PGDH, and inactivation of ERK1/2 by cpkimchi contributed to colitic cancer prevention. Dietary intake of cpkimchi ameliorated colitis and prevented colitic cancer via concerted anti-inflammatory, antioxidative, and anti-mutagenic actions.

Does NLRP3 Inflammasome and Aryl Hydrocarbon Receptor Play an Interlinked Role in Bowel Inflammation and Colitis-Associated Colorectal Cancer?

Inflammation is a hallmark in many forms of cancer; with colitis-associated colorectal cancer (CAC) being a progressive intestinal inflammation due to inflammatory bowel disease (IBD). While this is an exemplification of the negatives of inflammation, it is just as crucial to have some degree of the inflammatory process to maintain a healthy immune system. A pivotal component in the maintenance of such intestinal homeostasis is the innate immunity component, inflammasomes. Inflammasomes are large, cytosolic protein complexes formed following stimulation of microbial and stress signals that lead to the expression of pro-inflammatory cytokines. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome has been extensively studied in part due to its strong association with colitis and CAC. The aryl hydrocarbon receptor (AhR) has recently been acknowledged for its connection to the immune system aside from its role as an environmental sensor. AhR has been described to play a role in the inhibition of the NLRP3 inflammasome activation pathway. This review will summarise the signalling pathways of both the NLRP3 inflammasome and AhR; as well as new-found links between these two signalling pathways in intestinal immunity and some potential therapeutic agents that have been found to take advantage of this link in the treatment of colitis and CAC.

Caffeic Acid Phenethyl Ester Prevents Colitis-Associated Cancer by Inhibiting NLRP3 Inflammasome

Long-lasting inflammation in the intestinal tract renders individuals susceptible to colitis-associated cancer (CAC). The NOD-like receptor protein 3 (NLRP3) inflammasome plays a key role in the progression of inflammatory bowel disease and CAC. Therefore, identifying effective drugs that prevent CAC by targeting NLRP3 inflammasome is of great interest. Here, we aimed to evaluate the anti-inflammatory effect of caffeic acid phenethyl ester (CAPE) on bone marrow-derived macrophages (BMDMs), THP-1 cells, and azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon cancer mouse model. We also investigated the anti-tumor mechanism of CAPE. We found that CAPE decreased NLRP3 inflammasome activation in BMDMs and THP-1 cells and protected mice from colorectal cancer induced by AOM/DSS. CAPE regulated NLRP3 at the post-transcriptional level by inhibiting reactive oxygen species (ROS) production. However, CAPE did not affect NLRP3 or IL-1β transcription, but instead enhanced NLRP3 binding to ubiquitin molecules, promoting NLRP3 ubiquitination, and contributing to the anti-tumor effect in the AOM/DSS mouse model. Moreover, CAPE suppressed the interaction between NLRP3 and CSN5 but enhanced that between NLRP3 and Cullin1 both in vivo and in vitro. Altogether, our findings demonstrate that CAPE prevents CAC by post-transcriptionally inhibiting NLRP3 inflammasome. Thus, CAPE may be an effective candidate for reducing the risk of CAC in patients with inflammatory bowel disease.

Natural compounds flavonoids as modulators of inflammasomes in chronic diseases

The use of dietary or medicinal plant based natural compounds to disease treatment has become a unique trend in clinical research. Flavonoids, a group of polyphenolic compounds have drawn significant attention due to their modulatory effects on inflammasomes associated with the initiation and progression of chronic disorders including metabolic, neurodegenerative diseases and cancer. In this article, the role of most commonly studied natural flavonoids with their disease-specific impact via inflammasomes as a potential molecular target has been described. Since the role of inflammation is evident in multiple diseases, flavonoids may serve as a promising tool in drug discovery for the intervention of chronic diseases by manipulating the status of inflammation via inflammasome targeting.

The NLRP3 inflammasome: a therapeutic target for inflammation-associated cancers

Introduction: Inflammasomes are large multimeric intracellular complexes that are capable of maturation and secretion of pro-inflammatory cytokines, IL-1β and IL-18, in response to danger signal molecules. As a member of the inflammasome family, the NLRP3 inflammasome has recently been under intense investigation revealing its possible role in several human diseases especially cancers.Areas covered: In this review, we will discuss the biology and mechanism of NLRP3 inflammasome activation, its role in specific types of tumors and the novel therapeutic modalities targeting this complex.Expert opinion: The NLRP3 inflammasome and its components including the adapter apoptosis-associated speck-like (ASC) protein and caspase-1 impose different and sometimes contrasting effects in tumorigenesis depending on various contexts. Considering the novel role of this complex in the initiation and progression of neoplasia, the NLRP3 inflammasome and its pathways provide desirable therapeutic targets for prevention, treatment, and prognosis of certain types of cancer. To date, several agents have been introduced for this purpose, some of which have shown promising results in the clinic.

Exosome-like Nanoparticles from Ginger Rhizomes Inhibited NLRP3 Inflammasome Activation

The nucleotide-binding domain and leucine-rich repeat-containing family, pyrin domain-containing 3 (NLRP3) inflammasome is a key regulator of innate immune responses, and its aberrant activation is implicated in the pathogenesis of many diseases such as Alzheimer's disease and type 2 diabetes. Targeting the NLRP3 inflammasome could hold promise to combat these complex diseases, but therapies specifically inhibiting the NLRP3 inflammasome have not been developed for patient treatment. The current study aimed to identify food-borne exosome-like nanoparticles (ELNs) that inhibit NLRP3 inflammasome activity. Nine vegetables or fruits were selected to extract ELNs, which were examined for their inhibitory effects on activation of the NLRP3 inflammasome in primary macrophages. Although most of the tested ELNs posed minimal impacts, the ELNs from ginger rhizomes (G-ELNs) strongly inhibited NLRP3 inflammasome activation. The G-ELNs contained lipids, proteins, and RNAs and were easily taken up by macrophages. G-ELN treatment suppressed pathways downstream of inflammasome activation including caspase1 autocleavage, interleukin (IL)-1β and IL-18 secretion, and pyroptotic cell death. Apoptotic speck protein containing a caspase recruitment domain (ASC) oligomerization and speck formation assays indicated that G-ELNs blocked assembly of the NLRP3 inflammasome. The lipids in G-ELNs, rather than the RNAs or proteins, were responsible for the inhibitory activity observed. Together, the data suggested G-ELNs as new potent agents that block NLRP3 inflammasome assembly and activation. The unique features of G-ELNs including biomolecule protection and tissue bioavailability should facilitate the development of G-ELN-based therapy to target the NLRP3 inflammasome in the disease settings.

Interrelations of Apoptotic and Cellular Senescence Genes Methylation in Inflammatory Bowel Disease Subtypes and Colorectal Carcinoma in Egyptians Patients

Ras-related domain family member 1 transcript variant A (RASSF1A) controls apoptosis and cell proliferation while p14/ARF gene has a regulatory role in cellular senescence. Failure of apoptosis and cellular senescence occurs during inflammatory bowel disease (IBD) and colorectal cancer (CRC). To reveal the role of peripheral leukocyte promoter methylation of RASSF1A and p14/ARF in the pathogenesis of IBD subtypes and CRC we investigated the methylation state of the two genes by methylation-specific polymerase chain reaction (MSP-PCR) in 60 CRC patients, 60 patients with IBD; 27 with ulcerative colitis and 33 had Crohn's disease and also in 30 healthy subjects. Methylated RASSF1A and p14/ARF genes were detected in 55% and 60% of CRC, while the frequency of the methylated RASSF1A and p14/ARF genes was 23.3% and 43.3% in IBD patients and 3.3% and 13.3% in the control group (P = 0.000 each). Also, the frequency of methylated RASSF1A gene was significantly higher in ulcerative colitis than in Crohn's disease, while a non-significant frequency of methylated p14/ARF was detected between ulcerative colitis and Crohn's disease. Furthermore, methylated RASSF1A and p14/ARF were associated with the grade of CRC but not associated with the age of patients, family history, or tumor location. Results suggest that methylated RASSF1A and p14/ARF are related to CRC and IBD pathogenesis and may be used as molecular biomarkers for early detection of CRC and IBD.

Discovery of Quinazolin-4(3 H)-ones as NLRP3 Inflammasome Inhibitors: Computational Design, Metal-Free Synthesis, and in Vitro Biological Evaluation

NLRP3 inflammasome is an important therapeutic target for a number of human diseases. Herein, computationally designed series of quinazolin-4(3 H)-ones were synthesized using iodine-catalyzed coupling of arylalkynes (or styrenes) with O-aminobenzamides. The key event in this transformation involves the oxidative cleavage of the C-C triple/double bond and the release of formaldehyde. The reaction relies on the C-N bond formation along with the C-C bond cleavage under metal-free conditions. The nitro-substituted quinazolin-4(3 H)-one 2k inhibited NLRP3 inflammasome (IC₅₀ 5 μM) via the suppression of IL-1β release from ATP-stimulated J774A.1 cells.