Modulation of neutrophil motility by curcumin: implications for inflammatory bowel disease

The Role of Curcumin in Modulating Colonic Microbiota During Colitis and Colon Cancer Prevention

BACKGROUND

Intestinal microbiota influences the progression of colitis-associated colorectal cancer. With diet being a key determinant of the gut microbial ecology, dietary interventions are an attractive avenue for the prevention of colitis-associated colorectal cancer. Curcumin is the most active constituent of the ground rhizome of the Curcuma longa plant, which has been demonstrated to have anti-inflammatory, antioxidative, and antiproliferative properties.

METHODS

Il10 mice on 129/SvEv background were used as a model of colitis-associated colorectal cancer. Starting at 10 weeks of age, wild-type or Il10 mice received 6 weekly intraperitoneal injections of azoxymethane (AOM) or phosphate-buffered saline (PBS) and were started on either a control or a curcumin-supplemented diet. Stools were collected every 4 weeks for microbial community analysis. Mice were killed at 30 weeks of age.

RESULTS

Curcumin-supplemented diet increased survival, decreased colon weight/length ratio, and, at 0.5%, entirely eliminated tumor burden. Although colonic histology indicated improvement with curcumin, no effects of mucosal immune responses have been observed in PBS/Il10 mice and limited effects were seen in AOM/Il10 mice. In wild-type and in Il10 mice, curcumin increased bacterial richness, prevented age-related decrease in alpha diversity, increased the relative abundance of Lactobacillales, and decreased Coriobacterales order. Taxonomic profile of AOM/Il10 mice receiving curcumin was more similar to those of wild-type mice than those fed control diet.

CONCLUSIONS

In AOM/Il10 model, curcumin reduced or eliminated colonic tumor burden with limited effects on mucosal immune responses. The beneficial effect of curcumin on tumorigenesis was associated with the maintenance of a more diverse colonic microbial ecology.

A combined omics approach to evaluate the effects of dietary curcumin on colon inflammation in the Mdr1a(-/-) mouse model of inflammatory bowel disease

The aim of this study was to provide insight into how curcumin reduces colon inflammation in the Mdr1a(-/-) mouse model of human inflammatory bowel disease using a combined transcriptomics and proteomics approach. Mdr1a(-/-) and FVB control mice were randomly assigned to an AIN-76A (control) diet or AIN-76A+0.2% curcumin. At 21 or 24weeks of age, colonic histological injury score (HIS) was determined, colon mRNA transcript levels were assessed using microarrays and colon protein expression was measured using 2D gel electrophoresis and LCMS protein identification. Colonic HIS of Mdr1a(-/-) mice fed the AIN-76A diet was higher (P<.001) than FVB mice fed the same diet; the curcumin-supplemented diet reduced colonic HIS (P<.05) in Mdr1a(-/-) mice. Microarray and proteomics analyses combined with new data analysis tools, such as the Ingenuity Pathways Analysis regulator effects analysis, showed that curcumin's antiinflammatory activity in Mdr1a(-/-) mouse colon may be mediated by activation of α-catenin, which has not previously been reported. We also show evidence to support curcumin's action via multiple molecular pathways including reduced immune response, increased xenobiotic metabolism, resolution of inflammation through decreased neutrophil migration and increased barrier remodeling. Key transcription factors and other regulatory molecules (ERK, FN1, TNFSF12 and PI3K complex) activated in inflammation were down-regulated by dietary intervention with curcumin.

Curcumin suppresses NLRP3 inflammasome activation and protects against LPS-induced septic shock

SCOPE

The NLRP3 inflammasome responds to various pathogen-derived factors and danger-associated molecules, mediating IL-1β maturation, therefore is involved in multiple inflammatory diseases. Curcumin has been shown to possess strong anti-inflammatory activity, but the underlying mechanism is not fully understood. Here, we sought to investigate the role and mechanism of curcumin on the inhibition of mature IL-1β production via the regulation of NLRP3 inflammasome.

METHODS AND RESULTS

Curcumin dramatically inhibited the production of mature IL-1β in LPS-primed macrophages triggered by multiple NLRP3 inflammasome activators, and also reduced the level of cleaved caspase-1 as measured by western blot and ELISA. Curcumin prevented K(+) efflux, the common trigger for NLRP3 inflammasome activation, and attenuated lysosomes disruption and intracellular ROS formation as well. The inhibition of NLRP3 inflammasome by curcumin was in part mediated via the suppression of extracellular regulated protein kinases phosphorylation. Furthermore, administration of curcumin significantly reduced peritoneal IL-1β and HMGB-1 concentration induced by LPS and improved the survival of mice suffering from lethal endotoxic shock.

CONCLUSION

Curcumin potently inhibits the activation of NLRP3 inflammasome which may contribute to its anti-inflammatory activity. Our finding offers a mechanistic basis for the therapeutic potential of curcumin in septic shock and other NLRP3 inflammasome-driven diseases.

Curcumin in Combination With Mesalamine Induces Remission in Patients With Mild-to-Moderate Ulcerative Colitis in a Randomized Controlled Trial

BACKGROUND & AIMS

The phytochemical compound curcumin was reported to be effective in maintaining remission in patients with ulcerative colitis (UC). We investigated curcumin's efficacy in inducing remission in patients with active mild-to-moderate UC.

METHODS

We performed a multicenter randomized, placebo-controlled, double-blind study of 50 mesalamine-treated patients with active mild-to-moderate UC (defined by the Simple Clinical Colitis Activity Index [SCCAI]) who did not respond to an additional 2 weeks of the maximum dose of mesalamine oral and topical therapy. Patients were randomly assigned to groups who were given curcumin capsules (3 g/day, n = 26) or an identical placebo (n = 24) for 1 month, with continued mesalamine. The primary outcome was the rate of clinical remission (SCCAI ≤2) at week 4. Clinical and endoscopic responses were also recorded.

RESULTS

In the intention-to-treat analysis, 14 patients (53.8%) receiving curcumin achieved clinical remission at week 4, compared with none of the patients receiving placebo (P = .01; odds ratio [OR], 42; 95% confidence interval [CI], 2.3-760). Clinical response (reduction of ≥3 points in SCCAI) was achieved by 17 patients (65.3%) in the curcumin group vs. 3 patients (12.5%) in the placebo group (P < .001; OR, 13.2; 95% CI, 3.1-56.6). Endoscopic remission (partial Mayo score ≤1) was observed in 8 of the 22 patients evaluated in the curcumin group (38%), compared with none of 16 patients evaluated in the placebo group (P = .043; OR, 20.7; 95% CI, 1.1-393). Adverse events were rare and comparable between the 2 groups.

CONCLUSIONS

Addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects. Curcumin may be a safe and promising agent for treatment of UC. Clinicaltrials.gov number: NCT01320436.

Curcumin, inflammation, and chronic diseases: how are they linked?

It is extensively verified that continued oxidative stress and oxidative damage may lead to chronic inflammation, which in turn can mediate most chronic diseases including cancer, diabetes, cardiovascular, neurological, inflammatory bowel disease and pulmonary diseases. Curcumin, a yellow coloring agent extracted from turmeric, shows strong anti-oxidative and anti-inflammatory activities when used as a remedy for the prevention and treatment of chronic diseases. How oxidative stress activates inflammatory pathways leading to the progression of chronic diseases is the focus of this review. Thus, research to date suggests that chronic inflammation, oxidative stress, and most chronic diseases are closely linked, and the antioxidant properties of curcumin can play a key role in the prevention and treatment of chronic inflammation diseases.

Molecular analysis of curcumin-induced polarization of murine RAW264.7 macrophages

This study aimed to investigate the effects of curcumin on macrophages polarization and possible mechanism involved, and to analyze the molecular basis of its antiatherosclerosis activity. RAW264.7 macrophages (M0) and M1 macrophages were treated with curcumin at 0, 6.25, 12.5, and 25 μmol/L with or without GW9662. Using real-time polymerase chain reaction and Western blot analysis, we examined the phenotype markers of M1 [iNOS, interleukin (IL)-1β, IL-6, and MCP-1] and M2 (KLF4, FIZZ1, and MGL1] macrophages. Curcumin reduced the expression of the M1 phenotype markers and upregulated the expression of proliferator-activated receptor γ in M0 and M1 macrophages and IKBα in M1 macrophages. When M1 macrophages were incubated with curcumin and GW9662, the expression of the M1 phenotype markers was decreased, while IKBα was upregulated. The expression of the M2 phenotype markers in M0 and M1 macrophages was upregulated after the curcumin treatment. When M0 and M1 macrophages were incubated with curcumin and GW9662, the expression of the M2 phenotype markers was reduced. Curcumin inhibited the M1 inflammation phenotype as a result of the direct activation of IKBα and polarized the macrophages to become M2 phenotype through the activation of proliferator-activated receptor γ. These findings provide new clues to develop new drug therapy for atherosclerosis.

Advances in treatment of ulcerative colitis with herbs: From bench to bedside

Ulcerative colitis (UC), an idiopathic inflammatory disorder in the colon, has become a clinical challenge, owing to the increasing incidence and poor prognosis. The conventional treatments for UC including aminosalicylates, corticosteroids, and immunosuppressants, induce remission in only half of patients. Meanwhile, the treatments often come with serious side effects which can be life-threatening. Herbal medicine, one of the most common traditional Chinese medicine modalities, has been introduced for centuries into clinical treatment of many human diseases such as infections and functional disorders. Recently, the potential effectiveness of herbs has been suggested as the treatment of UC, as shown by a variety of clinical trials and experimental studies. The herbs reported in the literature include aloe vera gel, butyrate, tormentil extracts, wheat grass juice, and curcumin. In the review, bioactivity of the herbs and their involvement in UC treatment are discussed.

The effect of turmeric (Curcuma longa) extract on the functionality of the solute carrier protein 22 A4 (SLC22A4) and interleukin-10 (IL-10) variants associated with inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic relapsing disease. Genetic predisposition to the disease reduces an individual's capacity to respond appropriately to environmental challenges in the intestine leading to inappropriate inflammation. IBD patients often modify their diet to mitigate or reduce the severity of inflammation. Turmeric (Curcuma longa L., Zingiberaceae) has historically been used in Chinese, Hindu, and Ayurvedic medicine over several centuries to treat inflammatory disorders. To understand how turmeric may influence the consequences of a genetic predisposition to inappropriate inflammation, we used HEK293 cells to examine the in vitro capacity of turmeric extract and fractions to affect the functionality of two gene variants, solute carrier protein 22 A4 (SLC22A4, rs1050152) and interleukin-10 (IL-10, rs1800896) associated with IBD. We found that a turmeric extract and several chromatographically separated fractions beneficially affected the variants of SLC22A4 and IL-10 associated with IBD, by reducing inappropriate epithelial cell transport (SLC22A4, 503F) and increasing anti-inflammatory cytokine gene promoter activity (IL-10, -1082A). The effect of turmeric on the IL-10 variant was strongly associated with the curcumin content of the extract and its fractions.

Members of the novel UBASH3/STS/TULA family of cellular regulators suppress T-cell-driven inflammatory responses in vivo

The UBASH3/STS/TULA family consists of two members sharing substantial homology and a similar multi-domain architecture, which includes a C-terminal histidine phosphatase domain capable of dephosphorylating phosphotyrosine-containing substrates. TULA-family proteins act as downregulators of receptor-induced activation in several cell types, including T cells and platelets. Deletion of both family members in mice has been shown to result in hyperresponsiveness of T cells to T-cell receptor (TCR)/CD3 complex engagement, but little is known about the biological consequences of double knockout (dKO) and especially of either single KO (sKO). We elucidated the biological consequences of the lack of TULA-family proteins in dKO and TULA and TULA-2 sKO animals. In order to do so, we examined immune responses in Trinitrobenzene sulfonic acid (TNBS)-induced colitis, a mouse model of human inflammatory bowel disease, which is characterized by the involvement of multiple cell types, of which T cells have a crucial role, in the development of a pathological inflammatory condition. Our data indicate that TNBS treatment upregulates T-cell responses in all KO mice studied to a significantly higher degree than in wild-type mice. Although the lack of either TULA-family member exacerbates inflammation and T-cell responses in a specific fashion, the lack of both TULA and TULA-2 in dKO exerts a higher effect than the lack of a single family member in TULA and TULA-2 sKO. Analysis of T-cell responses and TCR-mediated signaling argues that the proteins investigated affect T-cell signaling by regulating phosphorylation of Zap-70, a key protein tyrosine kinase.

Curcumin increases gelatinase activity in human neutrophils by a p38 mitogen-activated protein kinase (MAPK)-independent mechanism

Curcumin has been found to possess anti-inflammatory activities and neutrophils, key players in inflammation, were previously found to be important targets to curcumin in a few studies. For example, curcumin was found to induce apoptosis in neutrophils by a p38 mitogen-activated protein kinase (MAPK)-dependent mechanism. However, the role of curcumin on the biology of neutrophils is still poorly defined. To study the role of curcumin on neutrophil degranulation and to determine the role of p38 MAPK, human neutrophils were freshly isolated from healthy individuals and incubated in vitro with curcumin. Degranulation was studied at three levels: surface expression of granule markers by flow cytometry; release of matrix metallopeptidase-9 (MMP-9 or gelatinase B) enzyme into supernatants by Western blot; and gelatinase B activity by zymography. Activation of p38 MAPK was studied by monitoring its tyrosine phosphorylation levels by western blot and its role by the utilization of a pharmacological inhibitor. The results indicate that curcumin increased the cell surface expression of CD35 (secretory vesicle), CD63 (azurophilic granules), and CD66b (gelatinase granules) in neutrophils. Also, curcumin increased the release and enzymatic activity of gelatinase B in the extracellular milieu and activated p38 MAP kinase in these cells. However, in contrast to fMLP, curcumin-induced enzymatic activity and secretion of gelatinase B were not reversed by use of a p38 inhibitor. Finally, it was found that curcumin was able to enhance phagocytosis. Taken together, the results here demonstrate that curcumin induced degranulation in human neutrophils and that the increased gelatinase activity is not dependent on p38 MAPK activation. Therefore, degranulation is another human neutrophil function that could be modulated by curcumin, as well as phagocytosis.

Induction with NCB-02 (curcumin) enema for mild-to-moderate distal ulcerative colitis - a randomized, placebo-controlled, pilot study

BACKGROUND AND AIMS

Curcumin, an active ingredient of turmeric with anti-inflammatory properties, has been demonstrated to be useful in experimental models of ulcerative colitis (UC). It's efficacy in humans needs to be investigated.

METHODS

A randomized, double-blind, single-centre pilot trial was conducted in patients with distal UC (<25 cm involvement) and mild-to-moderate disease activity. Forty-five patients were randomized to either NCB-02 (standardized curcumin preparation) enema plus oral 5-ASA or placebo enema plus oral 5-ASA. Primary end point was disease response, defined as reduction in Ulcerative Colitis Diseases Activity Index by 3 points at 8 weeks, and secondary end points were improvement in endoscopic activity and disease remission at 8 weeks.

RESULTS

Response to treatment was observed in 56.5% in NCB-02 group compared to 36.4% (p=0.175) in placebo group. At week 8, clinical remission was observed in 43.4% of patients in NCB-02 group compared to 22.7% in placebo group (p=0.14) and improvement on endoscopy in 52.2% of patients in NCB-02 group compared to 36.4% of patients in placebo group (p=0.29). Per protocol analysis revealed significantly better outcomes in NCB-02 group, in terms of clinical response (92.9% vs. 50%, p=0.01), clinical remission (71.4% vs. 31.3%, p=0.03), and improvement on endoscopy (85.7% vs. 50%, p=0.04).

CONCLUSION

In this pilot study we found some evidence that use of NCB-02 enema may tend to result in greater improvements in disease activity compared to placebo in patients with mild-to-moderate distal UC. The role of NCB-02 as a novel therapy for UC should be investigated further.

pTyr421 cortactin is overexpressed in colon cancer and is dephosphorylated by curcumin: involvement of non-receptor type 1 protein tyrosine phosphatase (PTPN1)

Cortactin (CTTN), first identified as a major substrate of the Src tyrosine kinase, actively participates in branching F-actin assembly and in cell motility and invasion. CTTN gene is amplified and its protein is overexpressed in several types of cancer. The phosphorylated form of cortactin (pTyr⁴²¹) is required for cancer cell motility and invasion. In this study, we demonstrate that a majority of the tested primary colorectal tumor specimens show greatly enhanced expression of pTyr⁴²¹-CTTN, but no change at the mRNA level as compared to healthy subjects, thus suggesting post-translational activation rather than gene amplification in these tumors. Curcumin (diferulolylmethane), a natural compound with promising chemopreventive and chemosensitizing effects, reduced the indirect association of cortactin with the plasma membrane protein fraction in colon adenocarcinoma cells as measured by surface biotinylation, mass spectrometry, and Western blotting. Curcumin significantly decreased the pTyr⁴²¹-CTTN in HCT116 cells and SW480 cells, but was ineffective in HT-29 cells. Curcumin physically interacted with PTPN1 tyrosine phosphatases to increase its activity and lead to dephosphorylation of pTyr⁴²¹-CTTN. PTPN1 inhibition eliminated the effects of curcumin on pTyr⁴²¹-CTTN. Transduction with adenovirally-encoded CTTN increased migration of HCT116, SW480, and HT-29. Curcumin decreased migration of HCT116 and SW480 cells which highly express PTPN1, but not of HT-29 cells with significantly reduced endogenous expression of PTPN1. Curcumin significantly reduced the physical interaction of CTTN and pTyr⁴²¹-CTTN with p120 catenin (CTNND1). Collectively, these data suggest that curcumin is an activator of PTPN1 and can reduce cell motility in colon cancer via dephosphorylation of pTyr⁴²¹-CTTN which could be exploited for novel therapeutic approaches in colon cancer therapy based on tumor pTyr⁴²¹-CTTN expression.

Protectin DX, a double lipoxygenase product of DHA, inhibits both ROS production in human neutrophils and cyclooxygenase activities

Neutrophils play a major role in inflammation by releasing large amounts of reactive oxygen species (ROS) produced by NADPH oxidase (NOX) and myeloperoxidase (MPO). This ROS overproduction is mediated by phosphorylation of the NOX subunits in an uncontrolled manner. Therefore, targeting neutrophil subunits would represent a promising strategy to moderate NOX activity, lower ROS, and other inflammatory agents, such as cytokines and leukotrienes, produced by neutrophils. For this purpose, we investigated the effects of protectin DX (PDX)-a docosahexaenoic acid di-hydroxylated product which inhibits blood platelet aggregation-on neutrophil activation in vitro. We found that PDX decreases ROS production, inhibits NOX activation and MPO release from neutrophils. We also confirm, that PDX is an anti-aggregatory and anti-inflammatory agent by inhibiting both cyclooxygenase-1 and -2 (COX-1 and COX-2, E.C. 1.14.99.1) as well as COX-2 in lipopolysaccharides-treated human neutrophils. However, PDX has no effect on the 5-lipoxygenase pathway that produces the chemotactic agent leukotriene B4 (LTB4). Taken together, our results suggest that PDX could be a protective agent against neutrophil invasion in chronic inflammatory diseases.

Curcumin Protects Mice From Coxsackievirus B3-Induced Myocarditis by Inhibiting the Phosphatidylinositol 3 kinase/Akt/Nuclear Factor-κB Pathway

Viral myocarditis is an inflammation of the myocardium, and coxsackievirus B3 (CVB3) is one of the most important etiologic agents. Curcumin is an active ingredient of Curcumin longa, which has been used as a traditional Chinese herb for the treatment of various inflammatory diseases. The aim of this study was to explore the therapeutic effect of curcumin on CVB3-induced myocarditis and the underlying mechanism. Our results showed that treatment with curcumin could significantly attenuate CVB3-induced myocarditis, as demonstrated by improved weight loss, increased survival rate, reduced serological level cardiac enzymes, and improved heart histopathology. Of importance, curcumin administration was revealed to significantly reduce the systemic and local myocardial expression of proinflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL) 6, and IL-1β, in the CVB3-infected mice. Further study showed that curcumin treatment significantly inhibited the CVB3-induced activation of nuclear factor-κB (NF-κB), a key transcription factor in the pathogenesis of inflammation, in a phosphatidylinositol 3 kinase (PI3K)/Akt pathway-dependent manner. These data indicate that curcumin has protective effect against CVB3-induced myocarditis by inhibiting PI3K/Akt/NF-κB signaling pathway and thus reducing the inflammatory response.

Suppression of experimental choroidal neovascularization by curcumin in mice

Purpose

To investigate the effects of curcumin on the development of experimental choroidal neovascularization (CNV) with underlying cellular and molecular mechanisms.

Methods

C57BL/6N mice were pretreated with intraperitoneal injections of curcumin daily for 3 days prior to laser-induced CNV, and the drug treatments were continued until the end of the study. The CNV area was analyzed by fluorescein-labeled dextran angiography of retinal pigment epithelium (RPE)-choroid flat mounts on day 7 and 14, and CNV leakage was evaluated by fluorescein angiography (FA) on day 14 after laser photocoagulation. The infiltration of F4/80 positive macrophages and GR-1 positive granulocytes were evaluated by immunohistochemistry on RPE-choroid flat mounts on day 3. Their expression in RPE-choroid complex was quantified by real-time PCR (F4/80) and Western blotting (GR-1) on day 3. RPE-choroid levels of vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1, and intercellular adhesion molecule (ICAM)-1 were examined by ELISA on day 3. Double immunostaining of F4/80 and VEGF was performed on cryo-sections of CNV lesions on day 3. The expression of nuclear factor (NF)-κB and hypoxia-inducible factor (HIF)−1α in the RPE-choroid was determined by Western blotting.

Results

Curcumin-treated mice had significantly less CNV area (P<0.05) and CNV leakage (P<0.001) than vehicle-treated mice. Curcumin treatment led to significant inhibition of F4/80 positive macrophages (P<0.05) and GR-1 positive granulocytes infiltration (P<0.05). VEGF mainly expressed in F4/80 positive macrophages in laser injury sites, which was suppressed by curcumin treatment (P<0.01). Curcumin inhibited the RPE-choroid levels of TNF-α (P<0.05), MCP-1 (P<0.05) and ICAM-1 (P<0.05), and suppressed the activation of NF-κB in nuclear extracts (P<0.05) and the activation of HIF−1α (P<0.05).

Conclusion

Curcumin treatment led to the suppression of CNV development together with inflammatory and angiogenic processes including NF-κB and HIF−1α activation, the up-regulation of inflammatory and angiogenic cytokines, and infiltrating macrophages and granulocytes. This provides molecular and cellular evidence of the validity of curcumin supplementation as a therapeutic strategy for the suppression of age-related macular degeneration (AMD)-associated CNV.

Curcuma longa extract exerts a myorelaxant effect on the ileum and colon in a mouse experimental colitis model, independent of the anti-inflammatory effect

Background

Curcuma has long been used as an anti-inflammatory agent in inflammatory bowel disease. Since gastrointestinal motility is impaired in inflammatory states, the aim of this work was to evaluate if Curcuma Longa had any effect on intestinal motility.

Methods

The biological activity of Curcuma extract was evaluated against Carbachol induced contraction in isolated mice intestine. Acute and chronic colitis were induced in Balb/c mice by Dextran Sulphate Sodium administration (5% and 2.5% respectively) and either Curcuma extract (200 mg/kg/day) or placebo was thereafter administered for 7 and 21 days respectively. Spontaneous contractions and the response to Carbachol and Atropine of ileum and colon were studied after colitis induction and Curcuma administration.

Results

Curcuma extract reduced the spontaneous contractions in the ileum and colon; the maximal response to Carbachol was inhibited in a non-competitive and reversible manner. Similar results were obtained in ileum and colon from Curcuma fed mice. DSS administration decreased the motility, mainly in the colon and Curcuma almost restored both the spontaneous contractions and the response to Carbachol after 14 days assumption, compared to standard diet, but a prolonged assumption of Curcuma decreased the spontaneous and Carbachol-induced contractions.

Conclusions

Curcuma extract has a direct and indirect myorelaxant effect on mouse ileum and colon, independent of the anti-inflammatory effect. The indirect effect is reversible and non-competitive with the cholinergic agent. These results suggest the use of curcuma extract as a spasmolytic agent.

8-(Tosylamino)quinoline inhibits macrophage-mediated inflammation by suppressing NF-κB signaling

AIM

The macrophage-mediated inflammatory response may contribute to the development of cancer, diabetes, atherosclerosis and septic shock. This study was to characterize several new compounds to suppress macrophage-mediated inflammation.

METHODS

Peritoneal macrophages from C57BL/6 male mice and RAW264.7 cells were examined. Anti-inflammatory activity was evaluated in the cells exposed to lipopolysaccharide (LPS). The mechanisms of the anti-inflammatory activity were investigated via measuring transcription factor activation in response to specific signals and via assaying the activities of the target kinases.

RESULTS

Of 7 candidate compounds tested, 8-(tosylamino)quinoline (8-TQ, compound 7) exhibited the strongest activities in suppressing the production of NO, TNF-α, and PGE(2) in LPS-activated RAW264.7 cells and peritoneal macrophages (the IC(50) values=1-5 μmol/L). This compound (1.25-20 μmol/L) dose-dependently suppressed the expression of the pro-inflammatory genes for iNOS, COX-2, TNF-α, and the cytokines IL-1β and IL-6 at the level of transcription in LPS-activated RAW264.7 cells. 8-TQ (20 μmol/L) significantly suppressed the activation of NF-κB and its upstream signaling elements, including inhibitor of κB (IκBα), IκBα kinase (IKK) and Akt in LPS-activated RAW264.7 cells. In in vivo experiments, oral administration of 20 and 40 mg/kg 8-TQ for 3 d significantly alleviated the signs of LPS-induced hepatitis and HCl/EtOH-induced gastritis, respectively, in ICR mice.

CONCLUSION

8-TQ (compound 7) exerts significant anti-inflammatory activity through the inhibition of the Akt/NF-κB pathway, thus may be developed as a novel anti-inflammatory drug.

P2Y6 receptor contributes to neutrophil recruitment to inflamed intestinal mucosa by increasing CXC chemokine ligand 8 expression in an AP-1-dependent manner in epithelial cells

BACKGROUND

Inflammatory bowel diseases are characterized by the presence of CXCL8 at the site of lesions resulting in neutrophil recruitment and loss of tissue functions. We report that P2Y(6) receptor activation stimulates CXCL8 expression and release by intestinal epithelial cells (IECs). In this context, we investigated if uridine 5'-diphosphate (UDP) enemas stimulate neutrophil recruitment to the mucosa of mice suffering from colitis-like disease and we characterized the signaling events linking P2Y(6) to CXCL8 expression in IEC.

METHODS

Neutrophil recruitment was monitored by immunofluorescence and FACS analysis. Expression of Cxcl1, a mouse functional homolog of CXCL8, was determined by quantitative real-time polymerase chain reaction (qPCR). Pharmacological inhibitors and interfering RNAs were used to characterize the signaling pathway. The outcomes of these treatments on protein phosphorylation and on CXCL8 expression were characterized by western blots, qPCR, luciferase, and chromatin immunoprecipitation (ChIP) assays.

RESULTS

Mutation of the AP-1 site in the CXCL8 core promoter abolished the UDP-stimulating effect. The c-fos/c-jun dimer was identified as the AP-1 complex regulating CXCL8 in response to UDP stimulation. Regulation of CXCL8 expression by P2Y(6) required PKCδ activation upstream of the signaling pathway composed of MEK1/2-ERK1/2 and c-fos. UDP administration to mice suffering from colitis-like disease increased the number of neutrophil infiltrating the mucosa, correlating with Cxcl1 increased expression in IEC and the severity of inflammation.

CONCLUSIONS

This study not only describes the P2Y(6) signaling mechanism regulating CXCL8 expression in IEC, but it also illustrates the potential of targeting P2Y(6) to reduce intestinal inflammation.

A neutraceutical by design: the clinical application of curcumin in colonic inflammation and cancer

Unquestionably, the natural food additive curcumin, derived from the colorful spice turmeric used in many Asian cuisines, possesses a diverse array of biological activities. These range from its anti-inflammatory, antineoplastic, and metabolic modifying properties to surprising roles in disorders ranging from Alzheimer's disease to cystic fibrosis. Its effects on growth factor receptors, signaling molecules, and transcription factors, together with its epigenetic effects are widely considered to be extraordinary. These pleiotropic attributes, coupled with its safety even when used orally at well over 10 g/day, are unparalleled amongst pharmacological agents. However, there is one drawback; apart from the luminal gastrointestinal tract where its pharmacology predicts that reasonable drug levels can be attained, its broader use is hampered by its poor solubility and hence near undetectable plasma levels. Medicinal chemistry and nanotechnology have resulted in the generation of compounds where the modified drug or its delivery system has improved matters such that this shortcoming has been addressed to some extent, with the surprising finding that it remains safe to use. It is predicted that either the parental compound or its derivatives may eventually find a place in the therapeutic management protocols of several conditions.

Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10(-/-) mice by attenuating the activation of T cells and promoting their apoptosis

Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10(-/-) mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10(-/-) mice. After JWH-133 treatment, the percentage of CD4(+) T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD.

Multifaceted roles of curcumin: two sides of a coin!

INTRODUCTION

Curcumin has been a front-line topic of mainstream scientific research for a variety of diseases from cancer to Alzheimer's to infectious diseases. Curcumin suppresses the type 1 immune response, which might lead to alleviation of type 1 immune response disorders. However, the inhibition of type 1 immune response might invite infections with opportunistic pathogens. Considering its low bioavailability, several curcumin derivatives have been designed to improve its functionality.

AREAS COVERED

This is a consolidated review which aims to compare and contrast diverse aspects of curcumin in variety of diseases. The intricate underlying mechanisms and the functional determinants of curcumin are discussed.

EXPERT OPINION

Curcumin being considered as a spicy panacea, is not a remedy for all diseases. However, its ability to act differentially as an anti-oxidant or pro-oxidant akin to that of a double-edged sword/friend turning foe can be either beneficial or harmful for the host. It exhibits anti-oxidant properties at concentrations achievable in the body, making the host vulnerable to infections due to the suppression of innate immune responses. With the increase in knowledge of its functional groups, production of analogues of curcumin is underway to enhance its bioavailability and hence its therapeutic potency.

Curcumin: the potential for efficacy in gastrointestinal diseases

Curcumin is a naturally occurring phytochemical and an extract of turmeric. Extensive in vitro and in vivo data have paved the way for curcumin to become the subject of clinical trials. Curcumin modulates key signalling pathways important in cellular processes. Numerous mechanisms of action have been elucidated. The potential for clinical efficacy is apparent from benign and malignant disease models. Curcumin has potent anti-inflammatory and anti-neoplastic properties used alone and in combination with standard therapies. Early-phase trials have ascertained pharmacological properties and consistently demonstrate it to be safe and well tolerated. However, bioavailability is limited and efficacious doses have not yet been determined. Evidence of efficacy has been derived from animal models or small clinical trials. There is only finite data supporting the use of curcumin in phase III trials with specific diseases (e.g. ulcerative colitis). However, for the vast majority of conditions additional early-phase studies are required to justify larger trials determining efficacy.

Therapeutic potential of curcumin in gastrointestinal diseases

Curcumin, also known as diferuloylmethane, is derived from the plant Curcuma longa and is the active ingredient of the spice turmeric. The therapeutic activities of curcumin for a wide variety of diseases such as diabetes, allergies, arthritis and other chronic and inflammatory diseases have been known for a long time. More recently, curcumin’s therapeutic potential for preventing and treating various cancers is being recognized. As curcumin’s therapeutic promise is being explored more systematically in various diseases, it has become clear that, due to its increased bioavailability in the gastrointestinal tract, curcumin may be particularly suited to be developed to treat gastrointestinal diseases. This review summarizes some of the current literature of curcumin’s anti-inflammatory, anti-oxidant and anti-cancer potential in inflammatory bowel diseases, hepatic fibrosis and gastrointestinal cancers.