Gut microbiome-host interactions in driving environmental pollutant trichloroethene-mediated autoimmunity.

Trichloroethene (TCE), a widely used industrial solvent, is associated with the development of autoimmune diseases (ADs), including systemic lupus erythematosus and autoimmune hepatitis. Increasing evidence support a linkage between altered gut microbiome composition and the onset of ADs. However, it is not clear how gut microbiome contributes to TCE-mediated autoimmunity, and initial triggers for microbiome-host interactions leading to systemic autoimmune responses remain unknown. To achieve this, female MRL+/+ mice were treated with 0.5 mg/ml TCE for 52 weeks and fecal samples were subjected to 16S rRNA sequencing to determine the microbiome composition. TCE exposure resulted in distinct bacterial community revealed by ß-diversity analysis. Notably, we observed reduction in Lactobacillaceae, Rikenellaceae and Bifidobacteriaceae families, and enrichment of Akkermansiaceae and Lachnospiraceae families after TCE exposure. We also observed significantly increased colonic oxidative stress and inflammatory markers (CD14 and IL-1ß), and decreased tight junction proteins (ZO-2, occludin and claudin-3). These changes were associated with increases in serum antinuclear and anti-smooth muscle antibodies and cytokines (IL-6 and IL-12), together with increased PD1 + CD4+ T cells in TCE-exposed spleen and liver tissues. Importantly, fecal microbiota transplantation (FMT) using feces from TCE-treated mice to antibiotics-treated mice induced increased anti-dsDNA antibodies and hepatic CD4+ T cell infiltration in the recipient mice. Our studies thus delineate how imbalance in gut microbiome and mucosal redox status together with gut inflammatory response and permeability changes could be the key factors in contributing to TCE-mediated ADs. Furthermore, FMT studies provide a solid support to a causal role of microbiome in TCE-mediated autoimmunity.

Interplay and roles of oxidative stress, toll-like receptor 4 and Nrf2 in trichloroethene-mediated autoimmunity.

Previous studies in MRL+/+ mice suggest involvement of oxidative stress (OS) in trichloroethene (TCE)-mediated autoimmunity. However, molecular mechanisms underlying the autoimmunity remain to be fully elucidated. Even though toll-like receptors (TLRs) and Nuclear factor (erythroid-derived 2)-like2 (Nrf2) pathways are implicated in autoimmune diseases (ADs), interplay of OS, TLR and Nrf2 in TCE-mediated autoimmune response remains unexplored. This study was, therefore, undertaken to clearly establish a link among OS, TLR4 and Nrf2 pathways in TCE-induced autoimmunity. Groups of female MRL+/+ mice were treated with TCE, sulforaphane (SFN, an antioxidant) or TCE + SFN (TCE, 10 mmol/kg, i.p., every 4th day; SFN, 8 mg/kg, i.p., every other day) for 6 weeks. TCE exposure led to greater formation of serum 4-hydroxynonenal (HNE)-protein adducts, HNE-specific circulating immune complexes (CICs) and protein carbonyls which were associated with significant increases in serum antinuclear antibodies (ANAs). Moreover, incubation of splenocytes from TCE-treated mice with HNE-modified proteins resulted in enhanced splenocyte proliferation and cytokine release evidenced by increased expression of cyclin D3, Cyclin-dependent kinase 6 (CDK6) and phospho-pRb as well as increased release of IL-6, TNF-α and INF-γ. More importantly, TCE exposure resulted in increased expression of TLR4, MyD88, IRAK4, NF-kB and reduced expression of Nrf2 and HO-1 in the spleen. Remarkably, SFN supplementation not only attenuated TCE-induced OS, upregulation in TLR4 and NF-kB signaling and downregulation of Nrf2, but also ANA levels. These results, in addition to providing further support to a role of OS, also suggest that an interplay among OS, TLR4 and Nrf2 pathways contributes to TCE-mediated autoimmune response. Attenuation of TCE-mediated autoimmunity by SFN provides an avenue for preventive and/or therapeutic strategies for ADs involving OS.

Mango polyphenolics reduce inflammation in intestinal colitis-involvement of the miR-126/PI3K/AKT/mTOR axis in vitro and in vivo.

This study sought to elucidate the mechanisms underlying the anti-inflammatory effect of mango (Mangifera Indica L.) polyphenolics containing gallic acid and gallotanins, and the role of the miR-126/PI3K/AKT/mTOR signaling axis in vitro and in vivo. Polyphenolics extracted from mango (var. Keitt) were investigated in lipopolysaccharide (LPS)-treated CCD-18Co cells. Rats received either a beverage with mango polyphenolics or a control beverage, and were exposed to three cycles of 3% dextran sodium sulfate (DSS) followed by a 2-wk recovery period. The mango extract (10 mg GAE/L) suppressed the protein expression of NF-κB, p-NF-κB, PI3K (p85ß), HIF-1α, p70S6K1, and RPS6 in LPS-treated CCD-18Co cells. LPS reduced miR-126 expression, whereas, the mango extract induced miR-126 expression in a dose-dependent manner. The relationship between miR-126 and its target, PI3K (p85ß), was confirmed by treating cells with miR-126 antagomiR where mango polyphenols reversed the effects of the antagomiR. In vivo, mango beverage protected against DSS-induced colonic inflammation (47%, P = 0.05) and decreased the Ki-67 labeling index in the central and basal regions compared to the control. Mango beverage significantly attenuated the expression of pro-inflammatory cytokines such as TNF-α, IL-1ß, and iNOS at the mRNA and protein level. Moreover, the expression of PI3K, AKT, and mTOR was reduced, whereas, miR-126 was upregulated by the mango treatment. These results suggest that mango polyphenols attenuated inflammatory response by modulating the PI3K/AKT/mTOR pathway at least in part through upregulation of miRNA-126 expression both in vitro and in vivo; thus, mango polyphenolics might be relevant as preventive agents in ulcerative colitis. © 2016 Wiley Periodicals, Inc.

Pomegranate polyphenolics suppressed azoxymethane-induced colorectal aberrant crypt foci and inflammation: possible role of miR-126/VCAM-1 and miR-126/PI3K/AKT/mTOR.

The antitumorigenic activities of polyphenols such as ellagitannins and anthocyanins in pomegranate (Punica granatum L.) have been previously studied where cytotoxic, anti-inflammatory and antioxidant effects were evident in various cancer models. The objective of this study was to investigate the role of miR-126/vascular cell adhesion molecule 1 (VCAM-1) and miR-126/phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) in pomegranate-mediated anti-inflammatory and anticarcinogenic effects in vivo and in vitro. Sprague-Dawley rats (n = 10 per group) received pomegranate juice (2504.74 mg gallic acid equivalents/l) or a polyphenol-free control beverage ad libitum for 10 weeks and were injected with azoxymethane (AOM) subcutaneously (15mg/kg) at weeks 2 and 3. Consumption of pomegranate juice suppressed the number of aberrant crypt foci (ACF) and dysplastic ACF by 29 and 53.5% (P = 0.05 and 0.04), respectively, and significantly lowered proliferation of mucosa cells. Pomegranate juice significantly downregulated proinflammatory enzymes nitric oxide synthase and cyclooxygenase-2 messenger RNA (mRNA) and protein expression. In addition, it suppressed nuclear factor-κB and VCAM-1 mRNA and protein expression in AOM-treated rats. Pomegranate also inhibited phosphorylation of PI3K/AKT and mTOR expression and increased the expression of miR-126. The specific target and functions of miR-126 were investigated in HT-29 colon cancer cell lines. In vitro, the involvement of miR-126 was confirmed using the antagomiR for miR-126, where pomegranate reversed the effects of the antagomiR on the expression of miR-126, VCAM-1 and PI3K p85ß. In summary, therapeutic potentials of pomegranate in colon tumorigenesis were due in part to targeting miR-126-regulated pathways, which contributes in the underlying anti-inflammatory mechanisms.

Resveratrol and quercetin in combination have anticancer activity in colon cancer cells and repress oncogenic microRNA-27a.

Resveratrol and quercetin (RQ) in combination (1:1 ratio) previously inhibited growth in human leukemia cells. This study investigated the anticancer activity of the same mixture in HT-29 colon cancer cells. RQ decreased the generation of reactive oxygen species (ROS) by up to 2.25-fold and increased the antioxidant capacity by up to 3-fold in HT-29 cells (3.8-60 µg/mL), whereas IC50 values for viability were 18.13, 18.73, and 11.85 µg/mL, respectively. RQ also induced caspase-3-cleavage (2-fold) and increased PARP cleavage. Specificity protein (Sp) transcription factors are overexpressed in colon and other cancers and regulate genes required for cell proliferation survival and angiogenesis. RQ treatment decreased the expression of Sp1, Sp3, and Sp4 mRNA and this was accompanied by decreased protein expression. Moreover, the Sp-dependent antiapoptotic survival gene survivin was also significantly reduced, both at mRNA and protein levels. RQ decreased microRNA-27a (miR-27a) and induced zinc finger protein ZBTB10, an Sp-repressor, suggesting that interactions of RQ with the miR-27a-ZBTB10-axis play a role in Sp downregulation. This was confirmed by transfection of cells with the specific mimic for miR-27a, which partially reversed the effects of RQ. These findings are consistent with previous studies on botanical anticancer agents in colon cancer cells.

Autophagy dysregulation in trichloroethene-mediated inflammation and autoimmune response.

Trichloroethene (TCE), an organic solvent extensively used for degreasing metals, can cause inflammatory autoimmune disorders [i.e., systemic lupus erythematosus (SLE) and autoimmune hepatitis] from both environmental and occupational exposure. Autophagy has emerged as a pivotal pathogenic factor in various autoimmune diseases. However, role of autophagy dysregulation in TCE-mediated autoimmunity is largely unknown. Here, we investigate whether autophagy dysregulation contributes to pathogenesis of TCE-mediated autoimmune responses. Using our established mouse model, we observed TCE-treated mice had elevated MDA-protein adducts, microtubule-associated protein light chain 3 conversion (LC3-II/LC3-I), beclin-1, phosphorylation of AMP-activated protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) phosphorylation in the livers of MRL+ /+ mice. Suppression of oxidative stress with antioxidant N-acetylcysteine (NAC) effectively blocked TCE-mediated induction of autophagy markers. On the other hand, pharmacological autophagy induction with rapamycin significantly reduced TCE-mediated hepatic inflammation (NLRP3, ASC, Caspase1 and IL1-ß mRNA levels), systemic cytokines (IL-12 and IL-17) and autoimmune responses (ANA and anti-dsDNA levels). Taken together, these results suggest that autophagy plays a protective role against TCE-mediated hepatic inflammation and autoimmunity in MRL+ /+ mice. These novel findings on the regulation of autophagy could help in designing therapeutic strategies for chemical exposure-mediated autoimmune responses.

Cytotoxicity of pomegranate polyphenolics in breast cancer cells in vitro and vivo: potential role of miRNA-27a and miRNA-155 in cell survival and inflammation.

Several studies have demonstrated that polyphenolics from pomegranate (Punica granatum L.) are potent inhibitors of cancer cell proliferation and induce apoptosis, cell cycle arrest, and also decrease inflammation in vitro and vivo. There is growing evidence that botanicals exert their cytotoxic and anti-inflammatory activities, at least in part, by decreasing specificity protein (Sp) transcription factors. These are overexpressed in breast tumors and regulate genes important for cancer cell survival and inflammation such as the p65 unit of NF-κB. Moreover, previous studies have shown that Pg extracts decrease inflammation in lung cancer cell lines by inhibiting phosphatidylinositol-3,4,5-trisphosphate (PI3K)-dependent phosphorylation of AKT in vitro and inhibiting the activation of NF-kB in vivo. The objective of this study was to investigate the roles of miR-27a-ZBTB10-Sp and miR-155-SHIP-1-PI3K on the anti-inflammatory and cytotoxic activity of pomegranate extract. Pg extract (2.5-50 µg/ml) inhibited growth of BT-474 and MDA-MB-231 cells but not the non-cancer MCF-10F and MCF-12F cells. Pg extract significantly decreased Sp1, Sp3, and Sp4 as well as miR-27a in BT474 and MDA-MB-231 cells and increased expression of the transcriptional repressor ZBTB10. A significant decrease in Sp proteins and Sp-regulated genes was also observed. Pg extract also induced SHIP-1 expression and this was accompanied by downregulation of miRNA-155 and inhibition of PI3K-dependent phosphorylation of AKT. Similar results were observed in tumors from nude mice bearing BT474 cells as xenografts and treated with Pg extract. The effects of antagomirs and knockdown of SHIP-1 by RNA interference confirmed that the anti-inflammatory and cytotoxic effects of Pg extract were partly due to the disruption of both miR-27a-ZBTB10 and miR-155-SHIP-1. In summary, the anticancer activities of Pg extract in breast cancer cells were due in part to targeting microRNAs155 and 27a. Both pathways play an important role in the proliferative/inflammatory phenotype exhibited by these cell lines.

Differential Expression of miRNAs in Trichloroethene-Mediated Inflammatory/Autoimmune Response and Its Modulation by Sulforaphane: Delineating the Role of miRNA-21 and miRNA-690.

Trichloroethene (TCE), an occupational and ubiquitous environmental contaminant, is associated with the induction of autoimmune diseases (ADs). Although oxidative stress plays a major role in TCE-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Altered non-coding RNAs, including the expression of microRNAs (miRNAs), can influence target genes, especially related to apoptosis and inflammation, and contribute to ADs. Therefore, the objective of this study was to delineate the contribution of miRNAs in TCE-mediated inflammatory and autoimmune response. To achieve this, we treated female MRL+/+ mice with TCE (10 mmol/kg in corn oil, i.p., every fourth day) with/without antioxidant sulforaphane (SFN; 8 mg/kg in corn oil, i.p., every other day) for 6 weeks. With the use of miRNA microarray, 293 miRNAs were analyzed, which included 35 miRNAs that were relevant to inflammation and ADs. Among those 35 miRNAs, 8 were modulated by TCE and/or TCE+SFN exposure. TCE treatment led to increased expression of 3 miRNAs and also decreased expression of 3 miRNAs. Interestingly, among the 35 differentially expressed miRNAs, antioxidant SFN modulated the expression of 6 miRNAs. Based on the microarray findings, we subsequently focused on two miRNAs (miRNA-21 and miRNA-690), which are known to be involved in inflammation and autoimmune response. The increases in miRNA-21 and miR-690 (observed using miRNA microarray) were further validated by RT-PCR, and the TCE-mediated increases in miR-21 and miR-690 were ameliorated by SFN treatment. Modulating miR-21 and miR-690 by respective inhibitors or mimics suppressed the expression of NF-κB (p65) and IL-12 in RAW 264.7 cells. Our findings suggest a contributory role of miR-21 and miR-690 in TCE-mediated and its metabolite dichloroacetyl chloride (DCAC)-mediated inflammation and autoimmune response and support that antioxidant SFN could be a potential therapeutic candidate for inflammatory responses and ADs.

Redox-sensitive Nrf2 and MAPK signaling pathways contribute to trichloroethene-mediated autoimmune disease progression.

Trichloroethene (TCE) exposure is associated with the induction of autoimmune diseases (ADs). Although oxidative stress plays a major role in TCE-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Dysregulation of redox-sensitive nuclear factor (erythroid-derived 2)-like2 (Nrf2), resulting in uncontrolled antioxidant and cytoprotective genes, and pro-inflammatory MAPK signaling pathways could be critical in TCE-mediated disease progression. This study was, therefore, focused on establishing status and contribution of Nrf2 and MAPK signaling in TCE-mediated inflammatory and autoimmune responses, especially during disease progression. To achieve these objectives, time-response studies were conducted by treating female MRL+/+ mice with TCE (0.5 mg/mL, a dose relevant to human exposure) for 24, 36 and 52 wks. TCE exposure led to reduction in Nrf2 expression, but increased phos-NF-κB (p65) and iNOS along with increased phosphorylation of MAPKs (p38, ERK and JNK) and downstream pro-inflammatory cytokines IL-12, TNF-α and RANTES in the livers in a time-dependent manner. These changes were also associated with time-dependent increases in liver protein carbonyls and induction of serum anti-dsDNA antibodies (marker of systemic lupus erythematosus disease), further supporting the role of oxidative stress and Nrf2/MAPK signaling in TCE-mediated autoimmune response progression. The mechanistic role of MAPK in TCE-mediated autoimmunity was further established by treating MRL+/+ mice with sulforaphane (SFN; 8 mg/kg, i.p., every other day) along with TCE (10 mmol/kg, i.p., every 4th day) for 6 wks using an established protocol, and by in vitro treatment of T cells with dichloroacetyl chloride (a TCE metabolite) with/without p38 MAPK inhibitor. SFN treatment attenuated the TCE-mediated phosphorylation of p38 MAPK. More importantly, treatment with SFN or p38 inhibitor led to suppression of downstream pro-inflammatory cytokines IL-12 and TNF-α. These findings thus support the contribution of Nrf2 and MAPK signaling pathways and help in delineating novel potential therapeutic targets against TCE-mediated autoimmunity.

Aberrant Gut Microbiome Contributes to Intestinal Oxidative Stress, Barrier Dysfunction, Inflammation and Systemic Autoimmune Responses in MRL/lpr Mice.

Microbiome composition and function have been implicated as contributing factors in the pathogenesis of autoimmune diseases (ADs), including systemic lupus erythematosus (SLE), rheumatoid arthritis and autoimmune hepatitis (AIH). Furthermore, dysbiosis of gut microbiome is associated with impaired barrier function and mucosal immune dysregulation. However, mechanisms by which gut microbiome contributes to the ADs and whether antioxidant treatment can restore gut homeostasis and ameliorate the disease outcome are not known. This study was, therefore, focused on examining the involvement of gut microbiome and host responses in the pathogenesis of SLE using unique female mouse models (C57BL/6, MRL+/+ and MRL/lpr) of 6 and 18 weeks with varying degrees of disease progression. Fecal microbiome diversity and composition, gut oxidative stress (OS), barrier function and inflammation, as well as systemic autoimmunity were determined. Interestingly, each mouse strain had distinct bacterial community as revealed by ß-diversity. A lower Firmicutes/Bacteroidetes ratio in 6-week-old MRL/lpr mice was observed, evidenced by decrease in Peptostreptococcaceae under Firmicutes phylum along with enrichment of Rikenellaceae under Bacteroidetes phylum. Additionally, we observed increases in colonic OS [4-hydroxynonenal (HNE)-adducts and HNE-specific immune complexes], permeability changes (lower tight junction protein ZO-2; increased fecal albumin and IgA levels) and inflammatory responses (increased phos-NF-κB, IL-6 and IgG levels) in 18-week-old MRL/lpr mice. These changes were associated with markedly elevated AD markers (antinuclear and anti-smooth muscle antibodies) along with hepatic portal inflammation and severe glomerulonephritis. Notably, antioxidant N-acetylcysteine treatment influenced the microbial composition (decreased Rikenellaceae; increased Akkeransiaceae, Erysipelotrichaceae and Muribaculaceae) and attenuated the systemic autoimmunity in MRL/lpr mice. Our data thus show that gut microbiome dysbiosis is associated with increased colonic OS, barrier dysfunction, inflammatory responses and systemic autoimmunity markers. These findings apart from delineating a role for gut microbiome dysbiosis, also support the contribution of gut OS, permeability changes and inflammatory responses in the pathogenesis of ADs.

Enhancing the Nrf2 Antioxidant Signaling Provides Protection Against Trichloroethene-mediated Inflammation and Autoimmune Response.

Trichloroethene (trichloroethylene, TCE) and one of its reactive metabolites dichloroacetyl chloride (DCAC) are associated with the induction of autoimmunity in MRL+/+ mice. Although oxidative stress plays a major role in TCE-/DCAC-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Nuclear factor (erythroid-derived 2)-like2 (Nrf2) is an oxidative stress-responsive transcription factor that binds to antioxidant responsive element (ARE) and provides protection by regulating cytoprotective and antioxidant gene expression. However, the potential of Nrf2 in the regulation of TCE-/DCAC-mediated autoimmunity is not known. This study thus focused on establishing the role of Nrf2 and consequent inflammatory responses in TCE-/DCAC-mediated autoimmunity. To achieve this, we pretreated Kupffer cells (KCs) or T cells with/without tert-butylhydroquinone (tBHQ) followed by treatment with DCAC. In both KCs and T cells, DCAC treatment significantly downregulated Nrf2 and HO-1 expression along with induction of Keap-1 and caspase-3, NF-κB (p65), TNF-α, and iNOS, whereas pretreatment of these cells with tBHQ attenuated these responses. The in vitro findings were further verified in vivo by treating female MRL+/+ mice with TCE along with/without sulforaphane. TCE exposure in mice also led to reduction in Nrf2 and HO-1 but increased phospho-NF-κB (p-p65) and iNOS along with increased anti-dsDNA antibodies. Interestingly, sulforaphane treatment led to amelioration of TCE-mediated effects, resulting in Nrf2 activation and reduction in inflammatory and autoimmune responses. Our results show that TCE/DCAC mediates an impairment in Nrf2 regulation. Attenuation of TCE-mediated autoimmunity via activation of Nrf2 supports that antioxidants sulforaphane/tBHQ could be potential therapeutic agents for autoimmune diseases.

Açaí (Euterpe oleracea Mart.) beverage consumption improves biomarkers for inflammation but not glucose- or lipid-metabolism in individuals with metabolic syndrome in a randomized, double-blinded, placebo-controlled clinical trial.

Açaí (Euterpe oleracea Mart.) berries, characterized by high polyphenol concentrations (predominantly anthocyanins), have demonstrated anti-inflammatory and anti-diabetic activities. The study objective was to determine the modulation of lipid and glucose-metabolism, as well as oxidative stress and inflammation, by an açaí-beverage (containing 1139 mg L-1 gallic acid equivalents of total polyphenolics) in 37 individuals with metabolic syndrome (BMI 33.5 ± 6.7 kg m-2) who were randomized to consume 325 mL twice per d of a placebo control or açaí-beverage for 12 weeks. Anthropometric measurements, dietary intake, and blood and urine samples were collected at baseline and after 12 weeks of consumption. Two functional biomarkers, plasma level of interferon gamma (IFN-γ) and urinary level of 8-isoprostane, were significantly decreased after 12 weeks of açaí consumption compared to the placebo control (p = 0.0141 and 0.0099, respectively). No significant modification of biomarkers for lipid- and glucose-metabolism was observed in this study. Findings from this small pilot study provide a weak indication that the selected dose of açaí polyphenols may be beneficial in metabolic syndrome as only two biomarkers for inflammation and oxidative stress were improved over 12 weeks. Follow-up studies should be conducted with higher polyphenol-doses before drawing conclusions regarding the efficacy of açaí polyphenols in metabolic syndrome.

Pomegranate polyphenolics reduce inflammation and ulceration in intestinal colitis-involvement of the miR-145/p70S6K1/HIF1α axis in vivo and in vitro.

This study investigated the potential role of the p70S6K1/HIF1α axis in the anti-inflammatory activities of pomegranate (Punica granatum L.) polyphenolics in dextran sodium sulfate (DSS)-induced colitis in Sprague-Dawley rats and in lipopolysaccharide (LPS)-treated CCD-18Co colon-myofibroblastic cells. Rats were administered either control (CT) or pomegranate beverage (PG), containing ellagic acid and ellagitannins, then exposed to three cycles of 3% DSS followed by a 2-week recovery period. PG protected against DSS-induced colon inflammation and ulceration (50% and 66.7%, P=.05 and .045, respectively), and decreased the Ki-67 proliferative index in the central and basal regions compared to the control. PG also significantly reduced the expression of proinflammatory cytokines (TNF-α and IL-1ß), COX-2, and iNOS at mRNA and protein levels. In addition, the expression of p70S6K1 and HIF1α was reduced, while the tumor suppressor miR-145 was induced by PG. The intestinal microbiota of rats treated with PG showed a significant increase in Ruminococcaceae that include several butyrate producing bacteria (P=.03). In vitro, PG reduced the expression of p70S6K1 and HIF1α and induced miR-145 in a dose-dependent manner. The involvement of miR-145/p70S6K1 was confirmed by treating LPS-treated CCD-18Co cells with miR-145 antagomiR, where the pomegranate polyphenolics reversed the effects of the antagomiR for p70S6K1 mRNA and protein levels. These results suggest that pomegranate polyphenols attenuated DSS-induced colitis by modulating the miR-145/p70S6K/HIF1α axis, indicating potential use in therapeutic treatment of ulcerative colitis.

Plum polyphenols inhibit colorectal aberrant crypt foci formation in rats: potential role of the miR-143/protein kinase B/mammalian target of rapamycin axis.

The nutritional prevention of aberrant crypt foci by polyphenols may be a crucial step to dietary cancer prevention. The objective of this study was to determine the underlying mechanisms that contribute to the anti-inflammatory and antitumorigenic properties of plum (Prunus salicina L.) polyphenols, including chlorogenic acid and neochlorogenic acid, in azoxymethane (AOM)-treated rats. The hypothesis was that plum polyphenolics suppress AOM-induced aberrant crypt foci formation through alterations in the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway and relative micro-RNA expressions. Sprague-Dawley rats (n=10/group) received plum beverage (1346mg gallic acid equivalents/L) or a control beverage ad libitum for 10 weeks with subcutaneous injections of AOM (15mg/kg) at weeks 2 and 3. Results show that the consumption of the plum beverage decreased the number of dysplastic aberrant crypt foci by 48% (P<.05) and lowered proliferation of mucosal cells by 24% (P<.05). The plum beverage decreased the activity of glutathione peroxidase, superoxide dismutase, and catalase in mucosal scrapings, as well as the superoxide dismutase activity in serum. The results were accompanied by a down-regulation of proinflammatory enzymes nuclear factor κB, nitric oxide synthase, cyclooxygenase-2, and vascular cell adhesion molecule 1 messenger RNA. Plum inhibited the expression of AKT and mTOR messenger RNA, phosphorylated AKT, mTOR, and hypoxia-inducible factor-1α protein levels, and the ratio of the phosphorylated/total protein expression of mTOR. Also, the plum beverage increased the expression of miR-143, which is involved in the regulation of AKT. These results suggest that plum polyphenols may exhibit a chemopreventive potential against colon carcinogenesis by impacting the AKT/mTOR pathway and miR-143.

Comparison of anti-inflammatory mechanisms of mango (Mangifera Indica L.) and pomegranate (Punica Granatum L.) in a preclinical model of colitis.

SCOPE: Tannin-rich fruits have been evaluated as alternative prevention strategies for colorectal cancer based on their anti-inflammatory properties. This study compared tannin-rich preparations from mango (rich in gallotannins) and pomegranate (rich in ellagitannins) in the dextran sodium sulfate-induced colitis model. METHODS AND RESULTS: In rats, mango and pomegranate beverages decreased intestinal inflammation and the levels of pro-inflammatory cytokines in mucosa and serum. The mango beverage suppressed the ratio of phosphorylated/total protein expression of the IGF-1R-AKT/mTOR axis and downregulated mRNA expression of Igf1, Insr, and pik3cv. Pomegranate decreased p70S6K and RPS6, as well as Rps6ka2, Map2k2, and Mapk1 mRNA. In silico modeling indicated a high binding of docked of gallic acid to the catalytic domain of IGF-1R, which may suppress the activity of the enzyme. Ellagic acid docked effectively into the catalytic domains of both IGF-1R and EGFR. In vitro assays with lipopolysaccharide-treated CCD-18Co cells using polyphenolic extracts from each beverage, as well as pure compounds, corroborated the predictions made in silico. CONCLUSION: Mango polyphenols inhibited the IGF-1R- AKT/mTOR axis, and pomegranate polyphenols downregulate the mTOR downstream pathway through reductions in ERK1/2. These results suggest that extracts rich in gallo- and ellagitannins act on different molecular targets in the protection against ulcerative colitis.

Mango polyphenolics suppressed tumor growth in breast cancer xenografts in mice: role of the PI3K/AKT pathway and associated microRNAs.

The cytotoxic and anti-inflammatory properties of mango polyphenolics including gallic acid and gallotannins have been demonstrated in numerous types of cancers. We hypothesized that the phosphoinositide 3-kinase (PI3K)/AKT pathway and the expression of related miRNAs are involved in the chemotherapeutic activities of mango polyphenolics in a mouse xenograft model for breast cancer. The objectives of this research were to determine the tumor-cytotoxic activities of mango polyphenolics and the underlying molecular mechanisms involving posttranscriptional targets in BT474 breast cancer cells and xenografts in mice. In vitro findings showed cytotoxic effects of mango polyphenolics in BT474 breast cancer cells within a concentration range of 2.5 to 20 mg/L gallic acid equivalents. Mango polyphenolics suppressed the expression of PI3K, AKT, hypoxia inducible factor-1α, and vascular endothelial growth factor (VEGF) mRNA, and pAKT, AKT, pPI3K (p85), VEGF and nuclear factor-kappa B protein levels. The involvement of miR-126 was verified by using antagomiR for miR-126, where mango reversed the effect of the antagomiR of miR-126. In vivo, the intake of mango polyphenolics decreased the tumor volume by 73% in BT474 xenograft-bearing mice compared with the control group. In addition, mango reduced the expression of nuclear factor-kappa B (p65), pAKT, pPI3K, mammalian target of rapamycin, hypoxia inducible factor-1α, and VEGF protein in athymic nude mice. A screening for miRNA expression changes confirmed that mango polyphenolics modulated the expression of cancer-associated miRNAs including miR-126 in the xenografted tumors. In summary, mango polyphenolics have a chemotherapeutic potential against breast cancer that at least in part is mediated through the PI3K/AKT pathway and miR-126.

Polyphenolic extracts from cowpea (Vigna unguiculata) protect colonic myofibroblasts (CCD18Co cells) from lipopolysaccharide (LPS)-induced inflammation--modulation of microRNA 126.

Cowpea (Vigna unguiculata) is a drought tolerant crop with several agronomic advantages over other legumes. This study evaluated varieties from four major cowpea phenotypes (black, red, light brown and white) containing different phenolic profiles for their anti-inflammatory property on non-malignant colonic myofibroblasts (CCD18Co) cells challenged with an endotoxin (lipopolysaccharide, LPS). Intracellular reactive oxygen species (ROS) assay on the LPS-stimulated cells revealed antioxidative potential of black and red cowpea varieties. Real-time qRT-PCR analysis in LPS-stimulated cells revealed down-regulation of proinflammatory cytokines (IL-8, TNF-α, VCAM-1), transcription factor NF-κB and modulation of microRNA-126 (specific post-transcriptional regulator of VCAM-1) by cowpea polyphenolics. The ability of cowpea polyphenols to modulate miR-126 signaling and its target gene VCAM-1 were studied in LPS-stimulated endothelial cells transfected with a specific inhibitor of miR-126, and treated with 10 mg GAE/L black cowpea extract where the extract in part reversed the effect of the miR-126 inhibitor. This suggests that cowpea may exert their anti-inflammatory activities at least in part through induction of miR-126 that then down-regulate VCAM-1 mRNA and protein expressions. Overall, Cowpea therefore is promising as an anti-inflammatory dietary component.