Patchouli alcohol ameliorates dextran sodium sulfate-induced experimental colitis and suppresses tryptophan catabolism. Pharmacol Res. 2017;121:70-82. [PMID: 28456683 DOI: 10.1016/j.phrs.2017.04.017]

Saikosaponin-d ameliorates dextran sulfate sodium-induced colitis by suppressing NF-κB activation and modulating the gut microbiota in mice

Saikosaponin-d (SSd), extracts from Bupleurum falcatum L, exhibits anti-inflammatory and anti-infectious activities. However, the effect of SSd on intestinal inflammation has not been investigated. The aim of this study was to evaluate the effect of SSd on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice, and to elucidate the underlying mechanisms. UC was induced in mice by administrating 3% DSS in drinking water for 7 days. SSd (4 mg/kg and 8 mg/kg) was administered by gavage every day during the experimental process. The results showed that SSd treatment (8 mg/kg) significantly ameliorated UC mice by decreasing disease activity index (DAI), increasing colon length and improving pathological characteristics. SSd treatment (8 mg/kg) significantly suppressed the mRNA levels of pro-inflammatory cytokines including TNF-α, IL-6 and IL-1β, increased that of anti-inflammatory cytokine IL-10. Furthermore, SSd (8 mg/kg) suppressed the activation of NF-κB by decreasing the degradation and phosphorylation of IκB. SSd (8 mg/kg) also protected the intestinal barrier by increasing the mRNA levels of mucin (Muc1 and Muc2) and the protein levels of zonula occludens-1 (ZO-1) and Claudin-1. The 16S rDNA gene high-throughput sequencing revealed that SSd treatment (8 mg/kg) increased the alpha diversity and regulated the structure of gut microbiota in UC mice. Taken together, our findings demonstrated that SSd (8 mg/kg) improved DSS-induced intestinal inflammation by inhibiting NF-κB activation and regulated the gut microbiota.

Fucose Ameliorates Tryptophan Metabolism and Behavioral Abnormalities in a Mouse Model of Chronic Colitis

Growing evidence suggests that intestinal mucosa homeostasis impacts immunity, metabolism, the Central Nervous System (CNS), and behavior. Here, we investigated the effect of the monosaccharide fucose on inflammation, metabolism, intestinal microbiota, and social behavior in the Dextran Sulfate Sodium (DSS)-induced chronic colitis mouse model. Our data show that chronic colitis is accompanied by the decrease of the serum tryptophan level and the depletion of the intestinal microbiota, specifically tryptophan-producing E. coli and Bifidobacterium. These changes are associated with defects in the male mouse social behavior such as a lack of preference towards female bedding in an odor preference test. The addition of fucose to the test animals' diet altered the bacterial community, increased the abundance of tryptophan-producing E. coli, normalized blood tryptophan levels, and ameliorated social behavior deficits. At the same time, we observed no ameliorating effect of fucose on colon morphology and colitis. Our results suggest a possible mechanism by which intestinal inflammation affects social behavior in male mice. We propose fucose as a promising prebiotic, since it creates a favorable environment for the beneficial bacteria that promote normalization of serum tryptophan level and amelioration of the behavioral abnormalities in the odor preference test.

Patchouli alcohol activates PXR and suppresses the NF-κB-mediated intestinal inflammatory

ETHNOPHARMACOLOGICAL RELEVANCE

The pregnane-X-receptor (PXR) is involved in inflammatory bowel disease (IBD). Patchouli alcohol (PA) has anti-inflammatory effects; however, the effect of PA on IBD pathogenesis remains largely unknown.

AIM OF THE STUDY

The aim of the present study was to investigate the anti-inflammatory effect of PA, primarily focused on crosstalk between PA-mediated PXR activation and NF-κB inhibition.

MATERIALS AND METHODS

We evaluated the anti-inflammatory effect of PA with respect to PXR/NF-κB signalling using in vitro and in vivo models. In vitro, PA, identified as a PXR agonist, was evaluated by hPXR transactivation assays and through assessing for CYP3A4 expression and activity. NF-κB inhibition was analysed based on NF-κB luciferase assays, NF-κB-mediated pro-inflammatory gene expression, and NF-κB nuclear translocation after activation of PXR by PA. In vivo, colonic mPXR and NF-κB signalling were analysed to assess PA-mediated the protective effect against dextran sulphate sodium (DSS)-induced colitis. Furthermore, pharmacological inhibition of PXR was further evaluated by examining PA protection against DSS-induced colitis.

RESULTS

PA induced CYP3A4 expression and activity via an hPXR-dependent mechanism. PA-mediated PXR activation attenuated inflammation by inhibiting NF-κB activity and nuclear translocation. The anti-inflammatory effect of PA on NF-κB was abolished by PXR knockdown. PA prevented DSS-induced inflammation by regulating PXR/NF-κB signalling, whereas pharmacological PXR inhibition abated PA-mediated suppressive effects on NF-κB inflammation signalling.

CONCLUSIONS

PA activates PXR signalling and suppresses NF-κB signalling, consequently causing amelioration of inflammation. Our results highlight the importance of PXR-NF-κB crosstalk in colitis and suggest a novel therapeutic reagent.

Protective Effect of Bruguiera gymnorrhiza (L.) Lam. Fruit on Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice: Role of Keap1/Nrf2 Pathway and Gut Microbiota

Bruguiera gymnorrhiza (BG), a medicinal mangrove, and its fruit (a food material) (BGF), have traditionally been used to treat diarrhea (also known as ulcerative colitis) in folk medicine. However, the mechanism of action against colitis remains ambiguous. This study aimed to investigate the potential efficacy and mechanism of BGF on experimental colitis. Colitis was induced by oral intake of dextran sulfate sodium (DSS) and treated with aqueous extract of BGF (25, 50 and 100 mg/kg) for a week. The Disease Activity Index (DAI), colon length, and histological changes of colon were analyzed. The inflammatory and oxidative stress status was explored. The protein expression of Nrf2 and Keap1 in the colon was detected by Western blotting. The mRNA expression of Nrf2 downstream genes (GCLC, GCLM, HO-1 and NQO1) was determined by RT-PCR. Furthermore, the effect on intestinal flora was analyzed. Results indicated that BGF was rich in pinitol, and showed strong antioxidative activity in vitro. Compared with the DSS model, BGF effectively reduced the body weight loss and DAI, restored the colon length, repaired colonic pathological variations, and decreased the histological scores, which was superior to salicylazosulfapyridine (SASP) with smaller dosage. Moreover, BGF not only abated the levels of MDA and inflammatory mediators (TNF-α, IL-6, IL-1β, and IFN-γ), increased the level of IL-10, but also prevented the depletion of SOD and GSH. BGF upregulated the protein level of nuclear Nrf2 and mRNA levels of GCLC, GCLM, HO-1 and NQO1, while significantly inhibited the protein expression of Keap1 and cytosolic Nrf2. Besides, BGF promoted the growth of probiotics (Bifidobacterium, Anaerotruncus, and Lactobacillus) in the gut, and inhibited the colonization of pathogenic bacteria (Bacteroides and Streptococcus), which contributed to the maintenance of intestinal homeostasis. BGF possessed protective effect against DSS-induced colitis. The potential mechanism of BGF may involve the amelioration of inflammatory and oxidative status, activation of Keap1/Nrf2 signaling pathway, and maintenance of micro-ecological balance of the host. This study provides experimental evidence for the traditional application of BGF in the treatment of diarrhea, and indicates that BGF may be a promising candidate against colitis.

Patchouli alcohol attenuates 5-fluorouracil-induced intestinal mucositis via TLR2/MyD88/NF-kB pathway and regulation of microbiota

Intestinal mucositis causes great suffering to cancer patients who undergo chemotherapy and radiotherapy. Owing to the uncertain side effects of anticancer drugs to attenuate patients' intestinal mucositis, many studies focused on traditional Chinese medicine (TCM). Patchouli alcohol (PA) is an active compound extracted from Pogostemon cablin, and has potent gastrointestinal protective effect. However, whether PA has an effect on intestinal mucositis is still unknown. Therefore, we established a rat model of intestinal mucositis via intraperitoneal injection of 5-fluorouracil, and intragastrically administrated PA (10, 20, and 40 mg/kg) to evaluate the effect of PA on intestinal mucositis. The routine observation (body weight, food intake, and diarrhea) in rats was used to detect whether PA had an effect on intestinal mucositis. Levels of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10, and MPO), mucosal barrier proteins (zonula occludens -1 (ZO-1), claudin-1, occludin, myosin light chain (MLC), and mucin-2) and intestinal microbiota were determined to elucidate the underlying mechanism of PA action on intestinal mucositis in rats. The results showed that PA could effectively improve body weight, food intake, and diarrhea in intestinal mucositis rats, preliminary confirming PA efficacy. Further experiments revealed that PA not only decreased the levels of TNF-α, IL-1β, IL-6, and MPO but also increased the level of IL-10 significantly. In addition, the expression of mucosal barrier proteins and microbiota community were also improved after PA treatment in diseased rats. Hence, PA may prevent the development and progression of intestinal mucositis by improving inflammation, protecting mucosal barrier, and regulating intestinal microbiota.

Patchouli Alcohol, a Compound from Pogostemon cablin, Inhibits Obesity

Obesity predisposes people to a variety of chronic metabolic diseases. Identification of natural factors that prevent the development of obesity is likely to be the most successful means of ameliorating the current obesity epidemic. Patchouli alcohol is a sesquiterpene alcohol found in Pogostemon cablin and possesses health benefit activities. This study was designed to examine if patchouli alcohol affects adipogenesis, and investigates the underlying mechanisms whereby patchouli alcohol exerts antiobesity effect. 3T3-L1 adipocytes were differentiated with treatment of different concentrations of patchouli alcohol. An in vivo study was performed to test the effect of patchouli alcohol gavage on a high-fat diet (HFD)-induced obesity. Treatment of patchouli alcohol reduced lipid accumulation in 3T3-L1 adipocytes in a dose-dependent manner without toxicity. Regarding mechanism, treatment of patchouli alcohol reduced expression of peroxisome proliferator-activated receptor-gamma (PPARγ) and CCAAT-enhancer-binding protein-alpha (C/EBPα) and increased expression of total and active β-catenin in 3T3-L1 adipocytes. Oral gavage of patchouli alcohol led to a significant reduction of body weight and fat accumulation in the mice fed with HFD. Transcriptome analysis indicates that smad7 is most highly activated gene in patchouli alcohol-treated 3T3-L1 cells. Patchouli alcohol possesses health benefit effect through inhibiting adipogenesis and fat tissue development.

Application of Herbaceous Medications for Inflammatory Bowel Disease as a Complementary and Alternative Therapy

BACKGROUND

Conventional medicine for the treatment of IBD is prevailingly composed of sulfadiazine, 5-aminosalicylic acid, glucocorticoid, and immunosuppressants, which have the merits of alleviating intestine inflammation, but long-term use of these drugs may cause toxic side effects; additionally, these drugs may be expensive. In the pursuit of novel and more economic therapies, patients may increasingly look at complementary and alternative medicine (CAM). Recently, CAM is increasingly favored by the general public on account of its safety, low toxicity, and effectiveness. As a branch of CAM, herbal plants and their extracts have a significant effect on the treatment of IBD. Treatment of IBD with herbaceous plants has been reported, but specific mechanisms and effects have not yet been elaborated.

METHODS

English abstracts were identified in PubMed and Science Direct by multiple search terms, such as "herbal," "CAM," "IBD," "ulcerative colitis," "abdominal pain," and so on. Full-length articles were selected for review.

RESULTS

Herbaceous plants and their extracts have been shown to be effective against IBD in many studies, and herbaceous plants may be effective in treating symptoms such as abdominal pain, diarrhea, mucus, and bloody stools.

CONCLUSIONS

Herbal medications could be used as a complementary and alternative treatment for IBD, but they require more rigorous scientific testing.

Current translational potential and underlying molecular mechanisms of necroptosis

Cell death has a fundamental impact on the evolution of degenerative disorders, autoimmune processes, inflammatory diseases, tumor formation and immune surveillance. Over the past couple of decades extensive studies have uncovered novel cell death pathways, which are independent of apoptosis. Among these is necroptosis, a tightly regulated, inflammatory form of cell death. Necroptosis contribute to the pathogenesis of many diseases and in this review, we will focus exclusively on necroptosis in humans. Necroptosis is considered a backup mechanism of apoptosis, but the in vivo appearance of necroptosis indicates that both caspase-mediated and caspase-independent mechanisms control necroptosis. Necroptosis is regulated on multiple levels, from the transcription, to the stability and posttranslational modifications of the necrosome components, to the availability of molecular interaction partners and the localization of receptor-interacting serine/threonine-protein kinase 1 (RIPK1), receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). Accordingly, we classified the role of more than seventy molecules in necroptotic signaling based on consistent in vitro or in vivo evidence to understand the molecular background of necroptosis and to find opportunities where regulating the intensity and the modality of cell death could be exploited in clinical interventions. Necroptosis specific inhibitors are under development, but >20 drugs, already used in the treatment of various diseases, have the potential to regulate necroptosis. By listing necroptosis-modulated human diseases and cataloging the currently available drug-repertoire to modify necroptosis intensity, we hope to kick-start approaches with immediate translational potential. We also indicate where necroptosis regulating capacity should be considered in the current applications of these drugs.

Phloretin ameliorates dextran sulfate sodium-induced ulcerative colitis in mice by regulating the gut microbiota

Phloretin, extracted from the pericarp and velamen of apples or pears, is a dihydrochalcone flavonoid with anti-bacterial and anti-inflammatory activities. It has been reported that phloretin has anti-inflammatory effects in ulcerative colitis (UC) mice. However, the role of the gut microbiota in the phloretin anti-UC process remains unclear. In this study, we observed that the anti-UC effect of phloretin was affected by co-housing, probably because of the transmissible nature of the gut micobiota. Through fecal micobiota transplantation (FMT), the effects of the gut microbiota on the anti-UC of phloretin were further confirmed. UC was induced in mice by administrating 3% dextran sulfate sodium (DSS) in drinking water for 7 days. Phloretin (60 mg/kg) was administered by gavage every day during the experiment. Fecal microbes (10⁹ CFU/mL) from phloretin-treated UC mice were administered by gavage to non-phloretin-treated UC mice for 7 days. The results showed that FMT, like phloretin, ameliorated UC by improving disease symptoms and colon inflammation, balancing inflammatory cytokines, maintaining intestinal barrier integrity, restoring systemic immune function, inhibiting NF-κB and NLRP3 inflammasome activation and ameliorating the oxidant stress. Both FMT and phloretin treatment increased the levels of Bacteroidetes, Alistipes and Lactobacillus and decreased those of Firmicutes, Oscillibacter and Ruminiclostridium_6. Correlation analysis between gut microbes and micro-environmental factors revealed that Alistipes abundance was negatively correlated with DAI, pathological score, and TNF-α, IL-6 and IL-1β levels, and Alistipes was more abundant in phloretin or FMT treated UC mice. Oscillibacter abundance was significantly positively correlated with IL-6 and IL-1β levels and pathological score, and Oscillibacter was increased in UC mice. Furthermore, network analysis of the dominant genera revealed that Alistipes abundance was negatively related to Oscillibacter abundance. In conclusion, this study suggests that the anti-UC effects of phloretin are achieved through regulation of the gut microbiota and phloretin has the potential to be developed as a promising agent for the treatment of UC.

Astragaloside IV alleviates the symptoms of experimental ulcerative colitis in vitro and in vivo

Ulcerative colitis (UC) is a chronic and relapsing inflammatory intestinal disease. Although the morbidity of UC has increased notably in recent years, effective therapeutic treatment remains unsatisfactory. Astragaloside IV (ASI), a monomeric compound isolated from the traditional Chinese medicine herb Ligusticum chuanxiong, exhibits anti-inflammatory effects. The present study aimed to investigate the therapeutic effects of ASI on experimental UC in vitro and in vivo. Cell proliferation was detected via a Cell Counting Kit-8 assay in vitro. In addition, the concentrations of the inflammatory factors myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and nitric oxide (NO) in the colon tissues were determined by ELISA. Western blot analysis was used to examine phosphorylated transcription factor p65 (p-p65), p-inhibitor of NF-κB (IκB), claudin-1 and tight junction protein ZO-1 (ZO-1) protein levels in vitro and in vivo, respectively. The results indicated that lipopolysaccharide (LPS) significantly increased the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 in CCD-18Co cells, which was markedly ameliorated by ASI. In addition to the inhibition of pro-inflammatory cytokines, ASI decreased the levels of p-p65 and p-IκB proteins. In addition, ASI decreased the disease activity index scores, and increased colon lengths in dextran sulfate sodium-induced UC mice. ASI also decreased the levels of the pro-inflammatory factors MPO, TNF-α, IL-1β, IL-6 and NO, and upregulated the expression of claudin-1 and ZO-1 in colon tissues. Therefore, ASI was effective in ameliorating experimental UC in vitro and in vivo via the inhibition of inflammatory molecules, and the downregulation of NF-κB signaling. In conclusion, ASI may serve as a potential therapeutic agent for the treatment of UC.

Beneficial effects of nutritional supplements on intestinal epithelial barrier functions in experimental colitis models in vivo

Acute and chronic colitis affect a huge proportion of the population world-wide. The etiology of colitis cases can be manifold, and diet can significantly affect onset and outcome of colitis. While many forms of acute colitis are easily treatable, chronic forms of colitis such as ulcerative colitis and Crohn's disease (summarized as inflammatory bowel diseases) are multifactorial with poorly understood pathogenesis. Inflammatory bowel diseases are characterized by exacerbated immune responses causing epithelial dysfunction and bacterial translocation. There is no cure and therapies aim at reducing inflammation and restoring intestinal barrier function. Unfortunately, most drugs can have severe side effects. Changes in diet and inclusion of nutritional supplements have been extensively studied in cell culture and animal models, and some supplements have shown promising results in clinical studies. Most of these nutritional supplements including vitamins, fatty acids and phytochemicals reduce oxidative stress and inflammation and have shown beneficial effects during experimental colitis in rodents induced by dextran sulphate sodium or 2,4,6-trinitrobenzene sulfonic acid, which remain the gold standard in pre-clinical colitis research. Here, we summarize the mechanisms through which such nutritional supplements contribute to epithelial barrier stabilization.

Rhubarb Peony Decoction ameliorates ulcerative colitis in mice by regulating gut microbiota to restoring Th17/Treg balance

ETHNOPHARMACOLOGY RELEVANCE

Rhubarb Peony Decoction (RPD) is a formula of traditional Chinese medicine chronicled in Jin Gui Yao Lve, commonly used to treat ulcerative colitis (UC). However, the underlying mechanism of RPD treating UC remains elusive. In our study, we investigated the therapeutic efficacy of RPD and potential mechanism involved in inhibiting dextran sulfate sodium (DSS)-induced ulcerative colitis in mice.

METHODS

The colitis was induced by DSS in mice for 5 days and estimated body weight loss, disease activity index (DAI) and colon length. Histological changes were observed by H&E staining. The number and abundance of gut mircrobiota were measured with 16 S rDNA sequencing. GC-MS was used to detect the concentration of short chain fatty acids (SCFAs) in cecum. Flow cytometry analyzed the proportion of Th17 and Treg cells in mesenteric lymph nodes (MLNs). IL-17A and Foxp3 in colon were determined by immunohistochemical analyses. The level of cytokine was determined by Multi-Analyte Flow Assay Kit.

RESULTS

Administration of RPD significantly alleviated the pathological changes of UC mice, involving rescued the inflammation-related reduction of colon length, ameliorated body weight loss and damaged tissue. In addition, RPD altered the gut microbiota, involving restored α diversity, increased significantly the abundance of Firmicutes and Actinobacteria, decreased the Proteobacteria and Bacteroidetes. Furthermore, the number of Butyricicoccus pullicaecorum, a butyrate-producing bacterium, were augmented obviously by RPD. Besides, RPD restored the content of SCFA in intestinal tract. Additionally, the proportion of Th17 cells and Treg cells in mesenteric lymph nodes, likewise, the expression of IL-17A and Foxp3 in colon were regulated by RPD, contributing to the restoration of Th17/Treg balance. Moreover, RPD significantly decreased the level of IL-6, TNF-α, IFNγ, IL-10, IL-17A, IL-21, IL-22 in colon, simultaneously increased Treg-related cytokine TGF-β at dose-dependently.

CONCLUSIONS

These results demonstrated that RPD had effect on ulcerative colitis, which was related to regulating gut microbiota, especially Butyricicoccus pullicaecorum, and SCFAs to restore the gut Th17/Treg homeostasis.

Palmatine attenuated dextran sulfate sodium (DSS)-induced colitis via promoting mitophagy-mediated NLRP3 inflammasome inactivation

Activation of NLRP3 inflammasomes is crucial in the pathological process of Ulcerative colitis (UC), which could be negatively regulated by PINK1/Parkin-driven mitophagy. Palmatine is a herb derived isoquinoline alkaloid with potent anti-inflammatory and anti-bacteria activities. In present study, we evaluated the effect of palmatine on dextran sulfate sodium (DSS)-induced mice colitis and examined whether its effect is exerted by promoting mitophagy-mediated NLRP3 inflammasome inactivation. The result showed that palmatine (40, 100 mg/kg) significantly prevented bodyweight loss and colonic shortening in DSS mice, and reduced the disease activity index and histopathologic score. The levels of MPO, IL-1β, TNF-α and the number of F4/80+ cells in colon of DSS mice were remarkably decreased by palmatine. Moreover, palmatine suppressed NLRP3 inflammasomes activation, but enhanced the expression of the mitophagy-related proteins involving LC3, PINK1 and Parkin in colonic tissue of DSS mice. These effects was consistent with the in vitro data revealing that palmatine inhibited the activation of NLRP3 inflammasomes, while promoted the expression and mitochondrial recruitment of PINK1 and Parkin in THP-1 cell differentiated macrophages. Furthermore, the effect of palmatine on THP-1 cells was neutralized by a mitophagy inhibitor Cyclosporin A (CsA) and PINK1-siRNA. In parallel, CsA significantly attenuated the therapeutic effect of palmatine in DSS mice, illustrating that the anti-colitis effect of palmatine is closely related to mitophagy. Taken together, the current results demonstrated that palmatine protected mice against DSS-induced colitis by facilitating PINK1/Parkin-driven mitophagy and thus inactivating NLRP3 inflammasomes in macrophage.

Palmatine ameliorated murine colitis by suppressing tryptophan metabolism and regulating gut microbiota

Inflammatory bowel disease (IBD), majorly include Crohn's disease (CD) and ulcerative colitis (UC), is chronic and relapsing inflammatory disorders of the gastrointestinal tract, which treatment options remain limited. Here we examined the therapeutic effects of an isoquinoline alkaloid, Palmatine (Pal), on mice experimental colitis induced by dextran sulfate sodium (DSS) and explored underlying mechanisms. Colitis was induced in BALB/c mice by administering 3% DSS in drinking water for 7 days. Pal (50 and 100 mg kg^-1) and the positive drug Sulfasalazine (SASP, 200 mg kg^-1) were orally administered for 7 days. Disease activity index (DAI) was evaluated on day 8, and colonic tissues were collected for biochemistry analysis. The fecal microbiota was characterized by high-throughput Illumina MiSeq sequencing. And plasma metabolic changes were detected by UPLC-MS. Our results showed that Pal treatment significantly reduced DAI scores and ameliorated colonic injury in mice with DSS-induced colitis. Mucosal integrity was improved and cell apoptosis was inhibited. Moreover, gut microbiota analysis showed that mice received Pal-treatment have higher relative abundance of Bacteroidetes and Firmicutes, but reduced amount of Proteobacteria. Moreover, Pal not only suppressed tryptophan catabolism in plasma, but also decreased the protein expression of indoleamine 2,3-dioxygenase 1 (IDO-1, the rate-limiting enzyme of tryptophan catabolism) in colon tissue. This is consolidated by molecular docking, which suggested that Pal is a potent IDO-1 inhibitor. Taken together, our findings demonstrate that Pal ameliorated DSS-induced colitis by mitigating colonic injury, preventing gut microbiota dysbiosis, and regulating tryptophan catabolism, which indicated that Pal has great therapeutic potential for colitis.

Periplaneta americana Ameliorates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Rats by Keap1/Nrf-2 Activation, Intestinal Barrier Function, and Gut Microbiota Regulation

Periplaneta americana, a magic medicinal insect being present for over 300 million years, exhibits desirable therapeutic outcome for gastrointestinal ulcer treatment. Nowadays, P. americana ethanol extract (PAE) has been shown to ameliorate ulcerative colitis (UC) by either single-use or in combination with other therapeutic agents in clinics. However, its underlying mechanisms are still seldom known. Herein, we investigated the anti-UC activity of PAE by alleviating intestinal inflammation and regulating the disturbed gut microbiota structure in dextran sulfate sodium (DSS)-induced UC rats. Based on multiple constitute analyses by HPLC for quality control, PAE was administrated to DSS-induced UC rats by oral gavage for 2 weeks. The anti-UC effect of PAE was evaluated by inflammatory cytokine production, immunohistochemical staining, and gut microbiota analysis via 16S rRNA sequencing. As a result, PAE remarkably attenuated DSS-induced UC in rats. The colonic inflammatory responses manifested as decreased colonic atrophy, intestinal histopathology scores and inflammatory cytokines. In addition, PAE improved the intestinal barrier function via activating Keap1/Nrf-2 pathway and promoting the expressions of tight junction proteins. It was observed that the UC rats showed symptoms of gut microbial disturbance, i.e., the increased Firmicutes/Bacteroidetes ratio and the significantly decreased probiotics such as Lactobacillus, Roseburia, and Pectobacterium, which were negatively correlated with these detected pro-inflammatory cytokines (secreted by immune CD⁴⁺ T cells, and including IFN-γ, TNF-α, IL-6, IL-8, IL-17, IL-1β). Besides, PAE administration regulated the abnormal intestinal microbial composition and made it similar to that in normal rats. Therefore, PAE could attenuate the DSS-induced UC in rats, by means of ameliorating intestinal inflammation, improving intestinal barrier function, and regulating the disturbed gut microbiota, especially improving beneficial intestinal flora growth, modulating the flora structure, and restoring the intestinal-immune system.

Berberrubine attenuates mucosal lesions and inflammation in dextran sodium sulfate-induced colitis in mice

Ulcerative colitis (UC) is a chronic relapsing disease without satisfactory treatments, in which intestinal inflammation and disrupted intestinal epithelial barrier are two main pathogeneses triggering UC. Berberrubine (BB) is deemed as one of the major active metabolite of berberine (BBR), a naturally-occurring isoquinoline alkaloid with appreciable anti-UC effect. This study aimed to comparatively investigate the therapeutic effects of BB and BBR on dextran sodium sulfate (DSS)-induced mouse colitis model, and explore the potential underlying mechanism. Results revealed that BB (20 mg/kg) produced a comparable therapeutic effect as BBR (50 mg/kg) and positive control sulfasalazine (200 mg/kg) by significantly reducing the disease activity index (DAI) with prolonged colon length and increased bodyweight as compared with the DSS group. BB treatment was shown to significantly ameliorate the DSS-induced colonic pathological alternations and decreased histological scores. In addition, BB markedly attenuated colonic inflammation by alleviating inflammatory cell infiltration and inhibiting myeloperoxidase (MPO) and cytokines (TNF-α, IFN-γ, IL-1β, IL-6, IL-4 and IL-10) productions in DSS mice. Furthermore, BB treatment substantially upregulated the expression of tight junction (TJ) proteins (zonula occludens-1, zonula occludens-2, claudin-1, occludin) and mRNA expression of mucins (mucin-1 and mucin-2), and decreased the Bax/Bcl-2 ratio. In summary, BB exerted similar effect to its analogue BBR and positive control in attenuating DSS-induced UC with much lower dosage and similar mechanism. The protective effect observed may be intimately associated with maintaining the integrity of the intestinal mucosal barrier and mitigating intestinal inflammation, which were mediated at least partially, via favorable modulation of TJ proteins and mucins and inhibition of inflammatory mediators productions in the colonic tissue. This is the first report to demonstrate that BB possesses pronounced anti-UC effect similar to BBR and sulfasalazine with much smaller dosage. BB might have the potential to be further developed into a promising therapeutic option in the treatment of UC.

Therapeutic Potential of Amino Acids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which includes both ulcerative colitis and Crohn’s disease, is a chronic relapsing inflammation of the gastrointestinal tract, and is difficult to treat. The pathophysiology of IBD is multifactorial and not completely understood, but genetic components, dysregulated immune responses, oxidative stress, and inflammatory mediators are known to be involved. Animal models of IBD can be chemically induced, and are used to study etiology and to evaluate potential treatments of IBD. Currently available IBD treatments can decrease the duration of active disease but because of their adverse effects, the search for novel therapeutic strategies that can restore intestinal homeostasis continues. This review summarizes and discusses what is currently known of the effects of amino acids on the reduction of inflammation, oxidative stress, and cell death in the gut when IBD is present. Recent studies in animal models have identified dietary amino acids that improve IBD, but amino acid supplementation may not be adequate to replace conventional therapy. The animal models used in dietary amino acid research in IBD are described.