A molecular mechanism for the anti-inflammatory effect of taurine-conjugated 5-aminosalicylic acid in inflamed colon

A narrative review and new insights into the protective effects of taurine against drug side effects

Taurine, a non-essential amino acid produced from cysteine, is abundant in body tissues and blood plasma. It plays vital roles in growth, osmosis, lipid metabolism, and neurohormonal modulation. Taurine has antioxidant, anti-apoptotic, and anti-inflammatory properties, and its deficiency can lead to various diseases including cardiovascular, diabetic, renal, and liver disorders. This report provides a comprehensive review of the functional properties of taurine in counteracting pharmaceutical-induced side effects. A search across databases such as Scopus, PubMed, MEDLINE, and Web of Science yielded 109 articles, of which 75 were included in the study. These results suggest that the protective effects of taurine involve mechanisms such as influencing pathways of Nrf2/OH-1, PI3-kinase/AKT and ERK2, boosting antioxidants (SOD, GPx and CAT), and suppression of inflammatory cytokines (TNF-α, IL-1β and IL-6). Overall, supplementation with taurine along with medications with significant side effects may mitigate these effects and enhance their efficacy. Further investigation of the interactions between taurine and other nutrients or compounds may provide insights into synergistic effects and novel therapeutic approaches.

N-Acetylserotonin is an oxidation-responsive activator of Nrf2 ameliorating colitis in rats

N-Acetylserotonin (NAS) is an intermediate in the melatonin biosynthetic pathway. We investigated the anti-inflammatory activity of NAS by focusing on its chemical feature oxidizable to an electrophile. NAS was readily oxidized by reaction with HOCl, an oxidant produced in the inflammatory state. HOCl-reacted NAS (Oxi-NAS), but not NAS, activated the anti-inflammatory nuclear factor erythroid 2-related factor 2 (Nrf2)-heme oxygenase (HO)-1 pathway in cells. Chromatographic and mass analyses demonstrated that Oxi-NAS was the iminoquinone form of NAS and could react with N-acetylcysteine possessing a nucleophilic thiol to form a covalent adduct. Oxi-NAS bound to Kelch-like ECH-associated protein 1, resulting in Nrf2 dissociation. Moreover, rectally administered NAS increased the levels of nuclear Nrf2 and HO-1 proteins in the inflamed colon of rats. Simultaneously, NAS was converted to Oxi-NAS in the inflamed colon. Rectal NAS mitigated colonic damage and inflammation. The anticolitic effects were significantly compromised by the coadministration of an HO-1 inhibitor.

Exploration of the amino acid metabolic signature in anthracycline-induced cardiotoxicity using an optimized targeted metabolomics approach based on UPLC-MS/MS

Although anthracyclines improve the long-term survival rate of patients with cancer, severe and irreversible myocardial damage limits their clinical application. Amino acid (AA) metabolism in cardiomyocytes can be altered under pathological conditions. Therefore, exploring the AA metabolic signature in anthracycline-induced cardiotoxicity (AIC) is important for identifying novel mechanisms. We established mouse and cellular models of Adriamycin (ADR)-induced cardiac injury. We observed a decreased expression of troponins I (cTnI) after ADR treatment and ADR accelerated the degradation of cTnI, implying that AA metabolism could be altered in AIC. Using a targeted AA metabolomics approach based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), the AA metabolic signatures in the sera of AIC mice and supernatant samples of ADR-treated H9c2 cardiomyocytes were analyzed. The levels of 14 AA metabolites were altered in ADR-treated mice (p < 0.05). Via bioinformatics analysis, we identified nine differential AA metabolites in mice and five differential AA metabolites in ADR-treated H9c2 cardiomyocytes. Three AAs with increased levels (L-glutamate, L-serine, and L-tyrosine) overlapped in the two models, suggesting a possible mechanism of AA metabolic impairment during AIC. The metabolic pathways perturbed by AIC involved aminoacyl-tRNA biosynthesis and alanine, aspartate, and glutamate metabolism. Our data suggests that ADR perturbed AA metabolism in AIC models. Moreover, the targeted AA metabolomics approach based on UPLC-MS/MS can be a unique platform to provide new clues for the prevention and treatment of AIC.

Analysis of clinical characteristics of mesalazine-induced cardiotoxicity

Background: Mesalazine is the first-line inflammatory bowel disease (IBD) treatment. However, it can cause fatal cardiotoxicity. We aimed to analyze the clinical characteristics of mesalazine-induced cardiotoxicity and provide evidence for clinical diagnosis, treatment, and prevention.

Methods: We collected Chinese and English literature on mesalazine-induced cardiotoxicity from 1970 to 2021 for retrospective analysis.

Results: A total of 52 patients (40 males and 12 females) were included, with a median age of 24.5 years (range 9–62) and a median onset time of 14 days (range 2–2880). Cardiotoxicity manifested as myocarditis, pericarditis, and cardiac pericarditis. The main clinical manifestations are chest pain (82.7%), fever (46.2%), and respiratory symptoms such as dyspnea and cough (40.4%). The levels of troponin T, creatine kinase, C-reactive protein, leukocyte count, erythrocyte sedimentation rate, and other biochemical markers were significantly increased. Cardiac imaging often suggests myocardial infarction, pericardial effusion, myocardial necrosis, and other symptoms of cardiac injury. It is essential to discontinue mesalamine immediately in patients with cardiotoxicity. Although corticosteroids are a standard treatment option, the benefits remain to be determined. Re-challenge of mesalamine should be carefully considered as cardiotoxic symptoms may reoccur.

Conclusion: Mesalazine may cause cardiotoxicity in patients with inflammatory bowel disease, which should be comprehensively diagnosed based on clinical manifestations, biochemical indicators, and cardiac function imaging examinations. Mesalazine should be immediately discontinued, and corticosteroids may be an effective treatment for cardiotoxicity.

Promoting mechanism of serum amyloid a family expression in mouse intestinal epithelial cells

Serum amyloid A (SAA) is an acute phase inflammatory protein that we previously described as a robust biomarker of colorectal inflammation in patients with ulcerative colitis (UC) in clinical remission. However, what induces SAA expression in UC remains unclear. This study demonstrates that SAA is significantly expressed in the intestinal tract of UC mouse models when compared with C-reactive protein, another inflammatory biomarker. Moreover, interleukin-6 and tumor necrosis factor-α were found to promote SAA1 expression, as were Toll-like receptor ligands flagellin and lipopolysaccharide. Furthermore, results suggested that the nuclear factor-kappa B (NF-κB) pathway may be involved in the promotion of SAA1 expression by flagellin, which was inhibited by treatment with 5-aminosalicylic acid (5-ASA). Therefore, the flagellin/NF-κB/SAA1 axis may represent one of the mechanisms by which 5-ASA suppresses intestinal inflammation.

Taurine loaded chitosan-pectin nanoparticle shows curative effect against acetic acid-induced colitis in rats

Owing to the poor outcomes and adverse side effects of existing ulcerative colitis drugs, the study aimed to develop an alternative nano-based treatment approach. The study was designed to characterize the in vitro and in vivo properties of taurine, taurine-loaded chitosan pectin nanoparticles (Tau-CS-PT-NPs) and chitosan pectin nanoparticles (CS-PT-NPs) in the therapy of acetic acid (AA)-induced colitis in rats. CS-PT-NPs and Tau-CS-PT-NPs were prepared by ionic gelation method then in vitro characterized, including transmission electron microscopy (TEM), polydispersity index (PDI), zeta potential, Fourier transform infrared (FTIR) spectroscopy, encapsulation efficiency (EE), and drug release profile. Following colitis induction, rats were orally administrated with free taurine, Tau-CS-PT-NPs, and CS-PT-NPs once per day for six days. The sizes of Tau-CS-PT-NPs and CS-PT-NPs were 74.17 ± 2.88 nm and 42.22 ± 2.41 nm, respectively. EE was about 69.09 ± 1.58%; furthermore, 60% of taurine was released in 4 h in simulated colon content. AA-induced colitis in untreated rats led to necrosis of colon tissues and a significant increase in interleukin-1beta (IL-1β), Tumor Necrosis Factor-alpha (TNF-α), myeloperoxidase (MPO), and malondialdehyde (MDA) levels associated with a remarkable reduction in glutathione (GSH) level in colon tissue in comparison to control group. Treatment with taurine, Tau-CS-PT-NPs, and CS-PT-NPs partly reversed these effects. The present study demonstrated that the administration of free taurine, CS-PT-NPs, and Tau-CS-PT-NPs exerted beneficial effects in acetic acid-induced colitis by their anti-inflammatory and antioxidant activities. The best therapeutic effect was observed in animals treated with taurine-loaded chitosan pectin nanoparticles.

The role of taurine on chemotherapy-induced cardiotoxicity: A systematic review of non-clinical study

AIMS

Although chemotherapeutic agents have highly beneficial effects against cancer, they disturb the body's normal homeostasis. One of the critical side effects of chemotherapeutic agents is their deleterious effect on the cardiac system, which causes limitations of their clinical usage. Taurine constitutes more than 50% of the amino acids in the heart. The use of taurine might prevent chemotherapy-induced cardiotoxicity. This systematic study aims to evaluate the protective role of taurine against cardiotoxicity induced by chemotherapy.

METHODS

A systematic search was performed in databases up to November 2020, and the review is designed on PRISMA guidelines. The search keywords were selected based on our study target and were searched in the title and abstract. After the consecutive screening, out of a whole of 94 articles, 8 articles were included according to our inclusion and exclusion criteria.

KEY FINDINGS

According to the study results, chemotherapy decreases body and heart weight and increases mortality. Also, it induces some biochemical and histological changes compared to the control group. By co-administration of taurine with chemotherapy, alterations returned near to the average level. These protective effects of taurine are mediated through anti-oxidant, anti-inflammatory, and anti-apoptotic properties.

SIGNIFICANCE

Based on evaluated non-clinical studies, taurine ameliorates chemotherapy-induced cardiotoxicity, but its possible interaction with the efficacy of anti-cancer medicines that mostly act through induction of oxidants remains to be elucidated in the future. This needs conducting well-designed studies to assess the effectiveness and safety of this combination simultaneously.

Role of taurine, its haloamines and its lncRNA TUG1 in both inflammation and cancer progression. On the road to therapeutics? (Review)

For one century, taurine is considered as an end product of sulfur metabolism. In this review, we discuss the beneficial effect of taurine, its haloamines and taurine upregulated gene 1 (TUG1) long non‑coding RNA (lncRNA) in both cancer and inflammation. We outline how taurine or its haloamines (N‑Bromotaurine or N‑Chlorotaurine) can induce robust and efficient responses against inflammatory diseases, providing insight into their molecular mechanisms. We also provide information about the use of taurine as a therapeutic approach to cancer. Taurine can be combined with other chemotherapeutic drugs, not only mediating durable responses in various malignancies, but also circumventing the limitations met from chemotherapeutic drugs, thus improving the therapeutic outcome. Interestingly, the lncRNA TUG1 is regarded as a promising therapeutic approach, which can overcome acquired resistance of cancer cells to selected strategies. In this regard, we can translate basic knowledge about taurine and its TUG1 lncRNA into potential therapeutic options directed against specific oncogenic signaling targets, thereby bridging the gap between bench and bedside.

Mesalazine Activates Adenosine Monophosphate-activated Protein Kinase: Implication in the Anti-inflammatory Activity of this Anti-colitic Drug

OBJECTIVE

Mesalazine, 5-aminosalicylic acid (5-ASA), is an anti-inflammatory drug that is most widely used for the treatment of Inflammatory Bowel Disease (IBD). Despite extensive clinical use, the exact pharmacological mechanism underlying the anti-colitic effects of 5-ASA has not yet been elucidated. A potential molecular mechanism underlying 5-ASA-mediated anti-colitic activity was investigated.

METHODS

An anti-inflammatory pharmacology of 5-ASA was scrutinized in human colon carcinoma cells and murine macrophages and in a TNBS-induced rat colitis model.

RESULTS

5-ASA induced phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrate acetyl-CoA carboxylase in cells. 5-ASA activation of AMPK occurred regardless of the presence of the pro-inflammatory mediators, Tumor Necrosis Factor Alpha (TNF-α) and lipopolysaccharide. 5-ASA inhibits TNF-α-dependent Nuclear Factor-Kappa B (NF-κB) activation, which was dampened by AMPK inhibition. Oral gavage of sulfasalazine (a colon-specific prodrug of 5- ASA) or rectal administration of 5-ASA ameliorated 2,4,6-trinitrobenzene sulfonic acid (TNBS)- induced rat colitis and activated AMPK in the inflamed colonic tissues while markedly diminishing the levels of NF-κB-regulated pro-inflammatory mediators cyclooxygenase-2, inducible nitric oxide synthase, and cytokine-induced neutrophil chemoattractant-3, elevated by the induction of inflammation. Rectal co-administration of 5-ASA and an AMPK inhibitor undermined 5-ASA-mediated activation of AMPK and its anti-colitic effects.

CONCLUSION

These findings suggest that the activation of AMPK is involved in 5-ASA-mediated anticolitic effects at least partly via interference with pro-inflammatory NF-κB signaling.

Ribose-Taurine Suppresses Inflammation Through NF-κB Regulation in Activated RAW 264.7 Macrophages

Ribose-taurine (Rib-T) suppressed the generation of inflammatory mediators and cytokines, such as nitric oxide (NO) and prostaglandin E2 (PGE2) through the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β induced by LPS was effectively blocked by Rib-T. Moreover, the anti-inflammatory actions of Rib-T were involved in its inhibitory effects against the nuclear translocation of nuclear factor-kappa B (NF-κB) p65, and NF-κB DNA-binding activity. These results suggest that the anti-inflammatory action of Rib-T is associated with NF-κB regulation.

Anti-inflammatory Action of Glucose-Taurine Reduced by Inhibiting NF-κB Activation in LPS-Activated RAW264.7 Macrophages

In the present study, we investigated the regulation of inflammatory effects by glucose-taurine reduced (G-T-R), a taurine-carbohydrate derivative, on lipopolysaccharide (LPS)-induced RAW264.7 macrophages. The anti-inflammatory action of G-T-R revealed that this derivative markedly inhibited the nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW264.7 macrophages induced by LPS. Suppression of NO and PGE2 production was involved in the inhibitory action by G-T-R on the inducible nitric oxide synthase and cyclooxygenase-2 proteins expression. G-T-R decreased the production of a variety of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and interleukin-6. Moreover, G-T-R effectively suppressed the nuclear factor-kappa B (NF-κB) activation in LPS-stimulated RAW264.7 macrophages according to evaluation of the molecular inflammatory mechanisms. Thus, we suggest that G-T-R modulates several inflammatory pathways mediated by NF-κB activation, demonstrating its potential or preventing and treating inflammatory conditions.

Taurine does not affect the composition, diversity, or metabolism of human colonic microbiota simulated in a single-batch fermentation system

Accumulating evidence suggests that dietary taurine (2-aminoethanesulfonic acid) exerts beneficial anti-inflammatory effects in the large intestine. In this study, we investigated the possible impact of taurine on human colonic microbiota using our single-batch fermentation system (Kobe University Human Intestinal Microbiota Model; KUHIMM). Fecal samples from eight humans were individually cultivated with and without taurine in the KUHIMM. The results showed that taurine remained largely undegraded after 30 h of culturing in the absence of oxygen, although some 83% of the taurine was degraded after 30 h of culturing under aerobic conditions. Diversity in bacterial species in the cultures was analyzed by 16S rRNA gene sequencing, revealing that taurine caused no significant change in the diversity of the microbiota; both operational taxonomic unit and Shannon-Wiener index of the cultures were comparable to those of the respective source fecal samples. In addition, principal coordinate analysis indicated that taurine did not alter the composition of bacterial species, since the 16S rRNA gene profile of bacterial species in the original fecal sample was maintained in each of the cultures with and without taurine. Furthermore, metabolomic analysis revealed that taurine did not affect the composition of short-chain fatty acids produced in the cultures. These results, under these controlled but artificial conditions, suggested that the beneficial anti-inflammatory effects of dietary taurine in the large intestine are independent of the intestinal microbiota. We infer that dietary taurine may act directly in the large intestine to exert anti-inflammatory effects.

Oxidized 5-aminosalicylic acid activates Nrf2-HO-1 pathway by covalently binding to Keap1: Implication in anti-inflammatory actions of 5-aminosalicylic acid

Mesalazine (5-aminosalicylic acid, 5-ASA), a currently used drug for anti-inflammatory bowel disease, is easily oxidized by HOCl, a strong oxidant generated in gut inflammation, to produce electrophilic quinones. We investigated whether this chemical feature has an implication in the anti-inflammatory pharmacology of 5-ASA. Human colon carcinoma HCT116 cells were treated with HOCl-reacted 5-ASA. Oxidized 5-ASA activated Nrf2 while 5-ASA itself was not effective. Activation of Nrf2 led to induction of hemeoxygenase (OH)-1, an anti-inflammatory enzyme. Western blot analysis of Keap1, a cytosolic repressor of Nrf2, following precipitation of biotin-labeled proteins in cell lysates treated with biotin-tagged 5-ASA, revealed a much greater amount of Keap1 when biotin-tagged 5-ASA was oxidized with HOCl. Precipitation of Keap1 was attenuated markedly by pretreatment with oxidized 5-ASA or a sulfhydryl donor. In addition, treatment with oxidized 5-ASA in cell lysates reduced the Keap1 amount that coimmunoprecipitated with Nrf2. In parallel, rectal administration of 5-ASA increased the level of HO-1 and nuclear Nrf2 in the inflamed colonic tissues, but not in normal colonic tissues. Moreover, oral gavage of sulfasalazine, a colon-specific prodrug of 5-ASA currently used clinically, activated the Nrf2-HO-1 pathway in the colonic tissues where inflammation was in progress, which was not observed when inflammation subsided. Collectively, our data suggest that Nrf2-HO-1 pathway is involved in the anti-inflammatory pharmacology of 5-ASA, which was likely being exerted exclusively in the inflammatory state.

Roles of Dietary Amino Acids and Their Metabolites in Pathogenesis of Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is a kind of chronic inflammation, which has increasing incidence and prevalence in recent years. IBD mainly divides into Crohn's disease (CD) and ulcerative colitis (UC). It is hard to cure IBD completely, and novel therapies are urgently needed. Amino acids (AAs) and their metabolites are regarded as important nutrients for humans and animals and also play an important role in IBD amelioration. In the present study, the potential protective effects of AAs and their metabolites on IBD had been summarized with the objective to provide insights into IBD moderating using dietary AAs and their metabolites as a potential adjuvant therapy.

Novel protective role of curcumin and taurine combination against experimental hepatocarcinogenesis

Hepatocarcinogenesis is a prerequisite to hepatocellular carcinoma (HCC), which is one of the most common cancers among humans. Therefore, it is important to search for agents that protect against hepatocarcinogenesis. The present study aimed to investigate the protective effects of a combination of taurine and curcumin against experimental hepatocarcinogenesis induced by diethyl nitrosamine (DENA) in a rat model. A total of 100 rats were divided into eight groups. Eight weeks following DENA injection and treatment with curcumin and taurine, the rats were sacrificed to obtain blood and hepatic tissue samples for the evaluation of various markers and histopathological observations. Serum levels of interleukin-2 (IL-2), interferon-γ (IFN-γ), α-fetoprotein (AFP) and α-L-fucosidase (AFU) were determined. Rats injected with DENA for eight weeks showed a high percentage of malignant changes in hepatic tissues, as well as a significant increases in the serum levels of AFP and AFU and significant reductions in the serum levels of IL-2 and IFN-γ. Treatment with curcumin and taurine markedly reduced the extent of malignant changes in the rat liver tissues, with their liver tissues showing patterns similar to that of the normal control rats. In addition, this combination resulted in normal serum levels of IL-2, IFN-γ, AFP and AFU. The results of the present study suggested that a combination of curcumin and taurine may be a novel prophylactic agent against hepatocarcinogenesis in high-risk groups exposed to chemical hepatocarcinogens.

Mucoadhesive microparticulates based on polysaccharide for target dual drug delivery of 5-aminosalicylic acid and curcumin to inflamed colon

In this work, thiolated chitosan/alginate composite microparticulates (CMPs) coated by Eudragit S-100 were developed for colon-specific delivery of 5-aminosalicylic acid (5-ASA) and curcumin (CUR), and the use of it as a multi drug delivery system for the treatment of colitis. The physicochemical properties of the CMPs were evaluated. In vitro release was performed in gradually pH-changing medium simulating the conditions of different parts of GIT, and the results showed that the Eudragit S-100 coating has a pH-sensitive release property, which can avoid drug being released at a pH lower than 7. An everted sac method was used to evaluate the mucoadhesion of CMPs. Ex vivo mucoadhesive tests showed CMPs have excellent mucosa adhesion for the colonic mucosa of rats. In vivo treatment effect of enteric microparticulates systems was evaluated in colitis rats. The results showed superior therapeutic efficiency of this drug delivery system for the colitis rats induced by TNBS. Therefore, the enteric microparticulates systems combined the properties of pH dependent delivery, mucoadhesive, and control release, and could be an available tool for the treatment of human inflammatory bowel disease.

5-Aminosalicylic Acid Azo-Linked to Procainamide Acts as an Anticolitic Mutual Prodrug via Additive Inhibition of Nuclear Factor kappaB

To improve the anticolitic efficacy of 5-aminosalicylic acid (5-ASA), a colon-specific mutual prodrug of 5-ASA was designed. 5-ASA was coupled to procainamide (PA), a local anesthetic, via an azo bond to prepare 5-(4-{[2-(diethylamino)ethyl]carbamoyl}phenylazo)salicylic acid (5-ASA-azo-PA). 5-ASA-azo-PA was cleaved to 5-ASA and PA up to about 76% at 10 h in the cecal contents while remaining stable in the small intestinal contents. Oral gavage of 5-ASA-azo-PA and sulfasalazine, a colon-specific prodrug currently used in clinic, to rats showed similar efficiency in delivery of 5-ASA to the large intestine, and PA was not detectable in the blood after 5-ASA-azo-PA administration. Oral gavage of 5-ASA-azo-PA alleviated 2,4,6-trinitrobenzenesulfonic acid-induced rat colitis. Moreover, combined intracolonic treatment with 5-ASA and PA elicited an additive ameliorative effect. Furthermore, combined treatment with 5-ASA and PA additively inhibited nuclear factor-kappaB (NFκB) activity in human colon carcinoma cells and inflamed colonic tissues. Finally, 5-ASA-azo-PA administered orally was able to reduce inflammatory mediators, NFκB target gene products, in the inflamed colon. 5-ASA-azo-PA may be a colon-specific mutual prodrug acting against colitis, and the mutual anticolitic effects occurred at least partly through the cooperative inhibition of NFκB activity.

PAK1 modulates a PPARγ/NF-κB cascade in intestinal inflammation

P21-activated kinases (PAKs) are multifunctional effectors of Rho GTPases with both kinase and scaffolding activity. Here, we investigated the effects of inflammation on PAK1 signaling and its role in colitis-driven carcinogenesis. PAK1 and p-PAK1 (Thr423) were assessed by immunohistochemistry, immunofluorescence, and Western blot. C57BL6/J wildtype mice were treated with a single intraperitoneal TNFα injection. Small intestinal organoids from these mice and from PAK1-KO mice were cultured with TNFα. NF-κB and PPARγ were analyzed upon PAK1 overexpression and silencing for transcriptional/translational regulation. PAK1 expression and activation was increased on the luminal intestinal epithelial surface in inflammatory bowel disease and colitis-associated cancer. PAK1 was phosphorylated upon treatment with IFNγ, IL-1β, and TNFα. In vivo, mice administered with TNFα showed increased p-PAK1 in intestinal villi, which was associated with nuclear p65 and NF-κB activation. p65 nuclear translocation downstream of TNFα was strongly inhibited in PAK1-KO small intestinal organoids. PAK1 overexpression induced a PAK1-p65 interaction as visualized by co-immunoprecipitation, nuclear translocation, and increased NF-κB transactivation, all of which were impeded by kinase-dead PAK1. Moreover, PAK1 overexpression downregulated PPARγ and mesalamine recovered PPARγ through PAK1 inhibition. On the other hand PAK1 silencing inhibited NF-κB, which was recovered using BADGE, a PPARγ antagonist. Altogether these data demonstrate that PAK1 overexpression and activation in inflammation and colitis-associated cancer promote NF-κB activity via suppression of PPARγ in intestinal epithelial cells.

Evaluation of glycine-bearing celecoxib derivatives as a colon-specific mutual prodrug acting on nuclear factor-κB, an anti-inflammatory target

In an inflammatory state where HOCl is generated, glycine readily reacts with HOCl to produce glycine chloramine, an anti-inflammatory oxidant. Colonic delivery of celecoxib elicits anticolitic effects in a trinitrobenzene sulfonic acid-induced rat colitis model. Glycine-bearing celecoxib derivatives were prepared and evaluated as a colon-specific mutual prodrug acting on nuclear factor-κB (NFκB), an anticolitic target. Glycylcelecoxib (GC), N-glycylaspart-1-ylcelecoxib (N-GA1C), and C-glycylaspart-1-ylcelecoxib (C-GA1C) were synthesized and their structures identified using infrared and proton nuclear magnetic resonance spectrometer. The celecoxib derivatives were chemically stable in pH 6.8 and 1.2 buffers. GC and C-GA1C were resistant to degradation in the small intestinal contents, while N-GA1C was substantially cleaved to release celecoxib. In contrast, all the celecoxib derivatives were degraded to liberate celecoxib in the cecal content. These results suggest that GC and C-GA1C could be delivered to and liberate celecoxib and glycine in the large intestine. In human colon carcinoma HCT116 and murine macrophage RAW264.7 cells, combined celecoxib–glycine chloramine treatment additively suppressed the production of proinflammatory NFκB target gene products. Collectively, our data suggest that C-GA1C is a potential colon-specific mutual prodrug acting against NFκB.

PAK1 promotes intestinal tumor initiation

p21-activated kinase 1 (PAK1) is a serine/threonine kinase that is overexpressed in colorectal cancer. PAK1 is a target of mesalamine [5-aminosylicylic acid (5-ASA)], a common drug for the treatment of ulcerative colitis with prospective chemopreventive properties. Here, we investigated whether PAK1 deletion impedes tumorigenesis in murine intestinal cancer models. Ten-week-old APC(min) or APC(min)/PAK1(-/-) mice were monitored for 8 weeks, euthanized, and assessed for tumor number and size. Six- to 8-week-old PAK1(-/-) and wild-type (WT) mice received one 10 mg/kg intraperitoneal injection of azoxymethane (AOM) and four cycles of 1.7% dextran sodium sulfate (DSS) for 4 days followed by 14 days of regular water. Mice also received 5-ASA via diet. Tumor incidence and size was assessed via colonoscopy and pathology. Molecular targets of PAK1 and 5-ASA were evaluated via immunohistochemistry (IHC) in both models. PAK1 deletion reduced tumor multiplicity and tumor burden but did not alter average tumor size in APC(min) mice. IHC revealed that PAK1 deletion reduced p-AKT, β-catenin, and c-Myc expression in APC(min) adenomas. Colonoscopy and pathologic analysis revealed that PAK1 deletion reduced tumor multiplicity without affecting tumor size in AOM/DSS-treated mice. 5-ASA treatment and PAK1 deletion impeded tumor multiplicity and dysplastic lesions in AOM/DSS mice. IHC further revealed that 5-ASA blocked β-catenin signaling via inhibition of PAK1/p-AKT. These data indicate that PAK1 contributes to initiation of intestinal carcinogenesis.

Five-aminosalicylic Acid: an update for the reappraisal of an old drug

Inflammatory bowel disease (IBD) comprises several conditions with chronic or recurring immune response and inflammation of the gastrointestinal apparatus, of which ulcerative colitis and Crohn's disease are the commonest forms. This disease has a significant prevalence and it is of an unknown aethiology. Five-aminosalicylic acid (5-ASA) and its derivatives are among the oldest drugs approved for the treatment of the IBD. In this review we reapprise aspects of 5-ASA mechanism of action, safety, and efficacy that in our opinion make it a valuable drug that can be fruitfully tailored in personalised treatments as a therapeutic option alongside other immune-modifying agents.

Design, synthesis, docking and anti-inflammatory evaluation of novel series of benzofuran based prodrugs

Several new benzofuran derivatives were synthesized, via appropriate synthetic route as anti-inflammatory agents. The anti-inflammatory activity of the prepared compounds was evaluated using carrageenan rat model. Among the synthesized compounds, some compounds showed comparable anti-inflammatory activity to nimesulide, the standard drug taken for anti-inflammatory studies. Docking study of the prepared compounds was performed for the study of interaction of molecules with the active site of COX-2. Preliminary biological studies and docking gave an interesting insight, into the validity of employing benzofuran analogues as good anti-inflammatory agent.

Pharmacological evaluation and preliminary pharmacokinetics studies of a new diclofenac prodrug without gastric ulceration effect

Long-term nonsteroidal anti-inflammatory drugs (NSAIDs) therapy has been associated with several adverse effects such as gastric ulceration and cardiovascular events. Among the molecular modifications strategies, the prodrug approach is a useful tool to discover new safe NSAIDs. The 1-(2,6-dichlorophenyl)indolin-2-one is a diclofenac prodrug which demonstrated relevant anti-inflammatory properties without gastro ulceration effect. In addition, the prodrug decreases PGE(2) levels, COX-2 expression and cellular influx into peritoneal cavity induced by carrageenan treatment. Preliminary pharmacokinetic studies have shown in vivo bioconversion of prodrug to diclofenac. This prodrug is a new nonulcerogenic NSAID useful to treat inflammatory events by long-term therapy.

Mesalamine-induced myocarditis and coronary vasculitis in a pediatric ulcerative colitis patient: a case report

Mesalamine-containing products are often a first-line treatment for ulcerative colitis. Severe adverse reactions to these products, including cardiovascular toxicity, are rarely seen in pediatric patients. We present a case of a 16-year-old boy with ulcerative colitis treated with Asacol, a mesalamine-containing product, who developed sudden onset chest pain after four weeks on therapy. Serial electrocardiograms showed nonspecific ST segment changes, an echocardiogram showed mildly decreased left ventricular systolic function with mild to moderate left ventricular dilation and coronary ectasia, and his troponins were elevated. Following Asacol discontinuation, his chest pain resolved, troponins were trending towards normal, left ventricular systolic function normalized, and coronary ectasia improved within 24 hours suggesting an Asacol-associated severe drug reaction. Mesalamine-induced cardiovascular toxicity, although rare, may represent a life-threatening disorder. Therefore, every patient presenting with acute chest pain should receive a workup to rule out this rare drug-induced disorder.

Anti-inflammatory actions of a taurine analogue, ethane β-sultam, in phagocytic cells, in vivo and in vitro

The ability of a taurine prodrug, ethane β-sultam, to reduce cellular inflammation has been investigated, in vitro, in primary cultures of alveolar macrophages and an immortilised N9 microglial cell line and in vivo in an animal model of inflammation and control rats. Ethane β-sultam showed enhanced ability to reduce the inflammatory response in alveolar macrophages, as assayed by the lipopolysaccharide-stimulated-nitric oxide release, (LPS stimulated-NO), in comparison to taurine both in vitro (10 nM, 50 nM) and in vivo (0.15 mmol/kg/day by gavage). In addition, ethane β-sultam, (50, 100 and 1000 nM) significantly reduced LPS-stimulated glutamate release from N9 microglial cells to a greater extent than taurine. The anti-inflammatory response of taurine was shown to be mediated via stabilisation of IkBα. The use of a taurine prodrug as therapeutic agents, for the treatment of neurological conditions, such as Parkinson's and Alzheimer's disease and alcoholic brain damage, where activated phagocytic cells contribute to the pathogenesis, may be of great potential.

Potential for amino acids supplementation during inflammatory bowel diseases

The pathophysiology of inflammatory bowel diseases (IBDs) is multifactorial and involves interactions of gut luminal content with mucosal barrier and especially immune cells. Malnutrition is a frequent issue during IBD flares, especially in Crohn's disease (CD) patients, and nutritional support is frequently used to treat malnutrition but also in an attempt to modulate intestinal inflammation. The use of oral or enteral nutrition intervention in IBDs may be effective, alone or in combination with drugs, to achieve and maintain remission. However, standard diets are less effective than new-generation biotherapies and could be improved by supplementation with specific immunomodulatory amino acids. Experimental studies evaluating glutamine, the preferential substrate for enterocytes, are promising. Some clinical studies with oral glutamine in CD are until now disappointing, but new formulations and targeting could enhance glutamine efficacy at the site of mucosal lesions. The role of arginine, involved in nitric oxide and polyamines synthesis, still remains debated. However, the effects of these amino acids in IBD have been poorly documented in humans. Other candidates like glycine, cysteine, histidine, or taurine should also be evaluated in the future.

Anti-inflammatory action of mollugin and its synthetic derivatives in HT-29 human colonic epithelial cells is mediated through inhibition of NF-kappaB activation

Mollugin is the active compound of Rubia cordifolia, which has been used as a traditional Chinese medicine for the treatment of various inflammatory diseases including arthritis and uteritis. In the present study, we investigated for the first time the inhibitory effects and the mechanisms of action of mollugin (M1) and its synthetic derivatives (M2-M4) on tumor necrosis factor (TNF)-alpha-induced inflammatory responses in HT-29 human colon epithelial cells. Treatment with M1 and its derivatives M2-M4 significantly inhibited TNF-alpha-induced attachment of U937 monocytic cells to HT-29 cells, which mimics the initial phase of colon inflammation. TNF-alpha-induced mRNA induction of the chemokines, monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-8, and the intercellular cell adhesion molecule (ICAM)-1, which are involved in adhesion between leukocytes and epithelial cells, was suppressed by M1-M4, and M1 was the most efficacious. In addition, M1-M4 significantly suppressed TNF-alpha-induced NF-kappaB transcriptional activity. Such NF-kappaB inhibitory activity of M1-M4 (20 microM) correlated with their ability to suppress TNF-alpha-induced chemokine expression and U937 monocytic cell adhesion to HT-29 colonic epithelial cells. Treatment of HT-29 cells with M1 and PDTC, a NF-kappaB inhibitor, synergistically suppressed both TNF-alpha-induced NF-kappaB activation and monocytic cell adhesion to HT-29 cells. These results suggest that M1-M4 inhibit TNF-alpha-induced expression of inflammatory molecules via NF-kappaB, and that M1, a potent NF-kappaB inhibitor, may be a valuable new drug candidate for the treatment of colon inflammation.

Synthesis, ex vivo and in vitro hydrolysis study of an indoline derivative designed as an anti-inflammatory with reduced gastric ulceration properties

The compound 1-(2,6-dichlorophenyl)indolin-2-one (1), planned as a pro-drug of diclofenac (2), was easily synthesized in 94% yield by an intramolecular reaction in the presence of coupling agent (i.e., EDC). Compound 1 showed anti-inflammatory and analgesic activity without gastro-ulcerogenic effects. The chemical and enzymatic hydrolysis profile of the lactam derivative 1 does not indicate conversion to diclofenac (2). This compound is a new non-ulcerogenic prototype for treatment of chronic inflammatory diseases.

An anti-inflammatory mechanism of taurine conjugated 5-aminosalicylic acid against experimental colitis: taurine chloramine potentiates inhibitory effect of 5-aminosalicylic acid on IL-1beta-mediated NFkappaB activation

Previously, we reported that oral administration of taurine conjugated 5-aminosalicylic acid, a colon-specific prodrug of 5-aminosalicylic acid (5-ASA), is effective in ameliorating experimental colitis and taurine elicits an additive anti-inflammatory effect upon cotreatment with 5-ASA. To explore a molecular mechanism for the anti-inflammatory property of the prodrug, we investigated the effect of the conjugate on IL-1beta-mediated NFkappaB activation. In human colon carcinoma Caco-2 and HCT116 cells, NFkappaB activity was accessed by a luciferase reporter assay and IL-6 secretion. Protein levels were determined by Western blotting. IL-6 levels were monitored by an Elisa kit. Treatment with either 5-ASA or taurine chloramine (TauCl) inhibited IL-1beta-mediated NFkappaB dependent luciferase expression and IL-6 secretion. In HCT116 cells, the inhibitory effect by TauCl or 5-ASA was through preventing IL-1beta-induced IkappaB kinase activation and subsequently interfering with IkappaBalpha degradation and p65 nuclear accumulation. Furthermore, combined TauCl/5-ASA treatment interfered additively with the activation process, leading to additive inhibitory effect on IL-1beta-mediated NFkappaB activation. Our results suggest that the anti-inflammatory effect of the prodrug on experimental colitis is attributed to the inhibition of the IL-1beta-mediated NFkappaB activation and the taurine effect is through TauCl potentiating the ability of 5-ASA to inhibit IL-1beta dependent NFkappaB activation.

Balsalazine decreases intestinal mucosal permeability of dextran sulfate sodium-induced colitis in mice

AIM

To investigate the effect of balsalazine treatment on intestinal mucosal permeability in dextran sulfate sodium (DSS)-induced colitis and to determine the mechanism of the balsalazine-induced changes.

METHODS

Experimental colitis was induced in C57BL/6J mice by the administration of 5% DSS. Balsalazine was administered intragastrically at doses of 42, 141, and 423 mg/kg. The disease activity index (DAI) score was evaluated and colon tissue was collected for the assessment of histological changes. The amount of malondialdehyde (MDA) in the colon was determined, along with the activity of myeloperoxidase (MPO), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Mucosa from the small intestine was collected to determine the levels of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. The mucosa was ultrastructurally examined with transmission electron microscopy and intestinal permeability was assayed using Evans blue.

RESULTS

Balsalazine was found to reduce the DAI score and the histological index (HI) score, decrease the MDA content and the activity of MPO, and increase the activity of SOD and GSH-Px in colitis mice. At the same time, balsalazine ameliorated microvillus and tight junction structure, resulting in a decrease in the amount of Evans blue permeating into the intestinal wall and the levels of TNF-alpha and IFN-gamma in colitis mice.

CONCLUSION

In colitis mice, the anti-colitis effect of balsalazine results in a decrease in intestinal mucosal permeability. The mechanism of this effect is partly associated with balsalazine's antioxidative and anti-inflammatory effects.Acta Pharmacologica Sinica (2009) 30: 987-993; doi: 10.1038/aps.2009.77.

Dietary taurine attenuates dextran sulfate sodium (DSS)-induced experimental colitis in mice

Effects of dietary taurine on the experimental colitis induced by dextran sulfate sodium (DSS) were studied. C57BL/6 mice administrated taurine or placebo for 5 days were given 3% DSS to induce acute. The colitis was as-sessed using indices such as diarrhea/bleeding scores, colon length change, histological score and tissue myeloperoxidase (MPO) activity. Further, tissue mRNA levels of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2, were determined by real-time PCR. Taurine supplementation significantly attenuated the severity of diarrhea, colon shortening, histological score, MPO activity elevation and abnormal MIP-2 gene expression, indicating that taurine prevents DSS-induced colitis. Taurine also inhibited the TNF-alpha-induced secretion of IL-8 (a human homologue of MIP-2) from human intestinal epithelial Caco-2 cells. Inhibition of chemokine secretion from intestinal cells may be involved in the mechanisms underlying the cytoprotective function of taurine in the intestinal epithelium.

Effects of glutamine on proinflammatory gene expression and activation of nuclear factor kappa B and signal transducers and activators of transcription in TNBS-induced colitis

BACKGROUND

We investigated the effects of glutamine on proinflammatory gene expression and activation of nuclear factor kappa B (NF-kappaB) and signal transducers and activators of transcription (STAT) in a rat model of experimental colitis.

METHODS

Colitis was induced in male Wistar rats by intracolonic administration of 30 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Glutamine (25 mg/kg) was given by rectal route daily for 7 days.

RESULTS

Glutamine significantly reduced gross damage and histopathological scores and prevented the decrease of anal pressure and the elevated myeloperoxidase activity observed in the colon of animals receiving TNBS. TNBS administration induced a marked increase of vascular cell adhesion molecule (VCAM-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein levels. These inflammatory events were associated with increased protein level of NF-kappaB p50 and p65 subunits in the nucleus and significant phosphorylation/degradation of the inhibitor IkappaBalpha. Protein levels of the phosphorylated forms of STAT1, STAT5, and Akt were elevated in animals with colonic damage. All these effects were inhibited by administration of glutamine. Increases in the cytosolic concentration of TBARS and hydroperoxide-initiated chemiluminescence, markers of oxidative stress, and levels of tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) were significantly inhibited at 48 hours of TNBS instillation in glutamine-treated animals.

CONCLUSIONS

Inhibition of the expression of proinflammatory mediators that are regulated by the NF-kappaB and STAT signaling pathways contribute to the therapeutical effect of glutamine in the TNBS model of experimental colitis. These effects may be brought about by inhibition of oxidative stress and reduced expression of proinflammatory cytokines.

The intestinal anti-inflammatory effects of the novel agent UR-1505 in the TNBS model of rat colitis are mediated by T-lymphocyte inhibition

UR-1505 is a novel pentafluoropropoxy derivative of salicylic acid, selected from a series of salicylate derivatives, according to their activity as inhibitors of T-lymphocyte activation. This study describes the anti-inflammatory activity of UR-1505 on trinitrobenzenesulphonic acid-induced colitis in rat, an experimental model that resembles to Crohn's disease (CD), as well as its in vitro effects on T-cells and bone marrow-derived macrophages (BMDM) activation. UR-1505 showed intestinal anti-inflammatory effect, associated with reduced colonic levels of TNFalpha and LTB(4), inhibition of the expression of IFNgamma and iNOS, and lower colonic leukocyte infiltration. The in vitro assays revealed that UR-1505 also inhibited T-lymphocyte proliferation and IL-12/IFNgamma production, two of the main pro-inflammatory cytokines involved in the pathogenesis of CD. However, UR-1505 did not modify LPS- nor IFNgamma-induced activation in BMDM. Thus, UR-1505 specifically affects T-cells without modifying the activation of BMDM. In conclusion, the intestinal anti-inflammatory activity of UR-1505 seems to be mediated by a reduction in the recruitment of immune cells to the inflammatory foci, together with the inhibition of T-cell activation. These results suggest that UR-1505 may be an interesting candidate to be explored for the treatment of CD.

Attenuation by dietary taurine of dextran sulfate sodium-induced colitis in mice and of THP-1-induced damage to intestinal Caco-2 cell monolayers

The effects of dietary taurine on the experimental colitis induced by dextran sulfate sodium (DSS) in mice were evaluated. C57BL/6 female mice were given 3% DSS in drinking water for 5 d to induce acute colitis. Taurine at 2% was added to the drinking water 5 d before and during the DSS-treatment to investigate its preventive effect. Taurine supplementation significantly attenuated the weight decrease, diarrhea severity, colon shortening, and the increase in the colonic tissue myeloperoxidase activity induced by DSS. Taurine also significantly inhibited the increase in the expression of a pro-inflammatory chemokine, macrophage inflammatory protein 2 (MIP-2), but not of interleukin (IL)-1beta or tumor necrosis factor (TNF)-alpha mRNA. Furthermore, taurine significantly protected the intestinal Caco-2 cell monolayers from the damage by macrophage-like THP-1 cells in an in vitro coculture system. These results suggest that taurine prevented DSS-induced colitis partly in association with (1) its inhibitory effects on the secretion of MIP-2 from the intestinal epithelial cells and on the infiltration of such inflammatory cells as neutrophils and (2) its cytoprotective functions on the epithelial barrier from the direct toxicity of DSS and from the inflammatory cell-induced injury.