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1.
Cancer Res Commun ; 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38934090

RESUMO

Escherichia coli that harbor the polyketide synthase (pks) genomic island produce colibactin and are associated with sporadic colorectal cancer development (CRC). Given the considerable prevalence of pks+ bacteria in healthy individuals, we sought to identify strategies to limit the growth and expansion of pks+ E. coli. We found that culture supernatants of the probiotic strain E. coli Nissle 1917 were able to inhibit the growth of the murine pathogenic strain pks+ E. coli NC101 (EcNC101). We performed a non-targeted analysis of the metabolome in supernatants from several E. coli strains and identified putrescine as a potential postbiotic capable of suppressing EcNC101 growth in vitro. The effect of putrescine supplementation was then evaluated in the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of CRC in mice colonized with EcNC101. Putrescine supplementation inhibited the growth of pks+ E. coli; reduced the number and size of colonic tumors; and downmodulated the release of inflammatory cytokines in the colonic lumen. Additionally, putrescine supplementation led to shifts in the composition and function of gut microbiota, characterized by an increase of the Firmicutes/Bacteroidetes ratio and enhanced acetate production. The effect of putrescine was further confirmed in vitro using a pks+ E. coli strain isolated from a CRC patient. These results suggest that probiotic-derived metabolites can be used as an alternative to live bacteria in individuals at risk of developing CRC due to the presence of pks+ bacteria in their colon.

2.
Clin Cancer Res ; 30(3): 616-628, 2024 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-38010363

RESUMO

PURPOSE: Anastomotic leak (AL) is a major complication in colorectal cancer surgery and consists of the leakage of intestinal content through a poorly healed colonic wound. Colorectal cancer recurrence after surgery is a major determinant of survival. We hypothesize that AL may allow cancer cells to escape the gut and lead to cancer recurrence and that improving anastomotic healing may prevent local implantation and metastatic dissemination of cancer cells. EXPERIMENTAL DESIGN: We investigated the association between AL and postoperative outcomes in patients with colorectal cancer. Using mouse models of poor anastomotic healing, we assessed the processes of local implantation and dissemination of cancer cells. The effect of dietary supplementation with inulin and 5-aminosalicylate (5-ASA), which activate PPAR-γ in the gut, on local anastomotic tumors was assessed in mice undergoing colonic surgery. Inulin and 5-ASA were also assessed in a mouse model of liver metastasis. RESULTS: Patients experiencing AL displayed lower overall and oncologic survival than non-AL patients. Poor anastomotic healing in mice led to larger anastomotic and peritoneal tumors. The microbiota of patients with AL displays a lower capacity to activate the antineoplastic PPAR-γ in the gut. Modulation of gut microbiota using dietary inulin and 5-ASA reinforced the gut barrier and prevented anastomotic tumors and metastatic spread in mice. CONCLUSIONS: Our findings reinforce the hypothesis that preventing AL is paramount to improving oncologic outcomes after colorectal cancer surgery. Furthermore, they pave the way toward dietary targeting of PPAR-γ as a novel way to enhance healing and diminish cancer recurrence.


Assuntos
Neoplasias Colorretais , Microbioma Gastrointestinal , Humanos , Camundongos , Animais , Fístula Anastomótica/etiologia , Fístula Anastomótica/prevenção & controle , Inulina , Receptores Ativados por Proliferador de Peroxissomo , Fatores de Risco , Recidiva Local de Neoplasia/prevenção & controle , Neoplasias Colorretais/patologia
4.
Front Microbiol ; 14: 1067505, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36819017

RESUMO

Introduction: The prebiotic inulin has previously shown both protective and tumor-promoting effects in colorectal cancer (CRC). These inconsistencies may be due to the gut microbial composition as several bacteria have been associated with CRC. Specifically, polyketide synthase-positive (pks+) Escherichia coli promotes carcinogenesis and facilitates CRC progression through the production of colibactin, a genotoxin that induces double-strand DNA breaks (DSBs). We investigated whether colibactin-producing Escherichia coli changed the protection conferred by inulin against tumor growth and progression using the ApcMin/+ mouse model of CRC. Methods: Mice received a 2% dextran sodium sulfate (DSS) solution followed by oral gavage with the murine pks + E. coli strain NC101 (EcNC101) and were fed a diet supplemented with 10% cellulose as control or 10% inulin for 4 weeks. Results: Inulin supplementation led to increase EcNC101 colonization compared to mice receiving the control diet. The increased colonization of EcNC101 resulted in more DSBs, tumor burden, and tumor progression in ApcMin/+ mice. The tumorigenic effect of EcN101 in ApcMin/+ mice mediated by inulin was dependent on colibactin production. Pasteurized E. coli Nissle 1917 (EcN), a probiotic, suppressed the inulin-driven EcNC101 expansion and impacted tumor progression. Discussion: Our results suggest that the presence of pks + E. coli influences the outcome of inulin supplementation in CRC and that microbiota-targeted interventions may mitigate this effect. Given the prevalence of pks + E. coli in both healthy and CRC populations and the importance of a fiber-rich diet, inulin supplementation in individuals colonized with pks + bacteria should be considered with caution.

5.
Gut ; 72(6): 1143-1154, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36585238

RESUMO

OBJECTIVE: Colorectal cancer (CRC) is the third most diagnosed cancer, and requires surgical resection and reconnection, or anastomosis, of the remaining bowel to re-establish intestinal continuity. Anastomotic leak (AL) is a major complication that increases mortality and cancer recurrence. Our objective is to assess the causal role of gut microbiota in anastomotic healing. DESIGN: The causal role of gut microbiota was assessed in a murine AL model receiving faecal microbiota transplantation (FMT) from patients with CRC collected before surgery and who later developed or not, AL. Anastomotic healing and gut barrier integrity were assessed after surgery. Bacterial candidates implicated in anastomotic healing were identified using 16S rRNA gene sequencing and were isolated from faecal samples to be tested both in vitro and in vivo. RESULTS: Mice receiving FMT from patients that developed AL displayed poor anastomotic healing. Profiling of gut microbiota of patients and mice after FMT revealed correlations between healing parameters and the relative abundance of Alistipes onderdonkii and Parabacteroides goldsteinii. Oral supplementation with A. onderdonkii resulted in a higher rate of leaks in mice, while gavage with P. goldsteinii improved healing by exerting an anti-inflammatory effect. Patients with AL and mice receiving FMT from AL patients presented upregulation of mucosal MIP-1α, MIP-2, MCP-1 and IL-17A/F before surgery. Retrospective analysis revealed that patients with AL present higher circulating neutrophil and monocyte counts before surgery. CONCLUSION: Gut microbiota plays an important role in surgical colonic healing in patients with CRC. The impact of these findings may extend to a vast array of invasive gastrointestinal procedures.


Assuntos
Neoplasias Colorretais , Microbioma Gastrointestinal , Camundongos , Animais , Citocinas , Microbioma Gastrointestinal/fisiologia , Estudos Retrospectivos , RNA Ribossômico 16S , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/microbiologia , Neoplasias Colorretais/cirurgia
6.
Gut Pathog ; 14(1): 51, 2022 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-36578036

RESUMO

BACKGROUND: Colorectal cancer (CRC) is the third most diagnosed cancer and the second most common cause of cancer deaths worldwide. CRC patients present with an increase in pathogens in their gut microbiota, such as polyketide synthase-positive bacteria (pks +) and enterotoxigenic Bacteroides fragilis (ETBF). The pks + Escherichia coli promotes carcinogenesis and facilitates CRC progression through the production of colibactin, a genotoxin that induces double-strand DNA breaks (DSBs). ETBF is a procarcinogenic bacterium producing the B. fragilis toxin (bft) that promotes colorectal carcinogenesis by modulating the mucosal immune response and inducing epithelial cell changes. METHODS: Fecal samples were collected from healthy controls (N = 62) and CRC patients (N = 94) from the province of Québec (Canada), and a bacterial DNA extraction was performed. Fecal DNA samples were then examined for the presence of the pks island gene and bft using conventional qualitative PCR. RESULTS: We found that a high proportion of healthy controls are colonized by pks + bacteria (42%) and that these levels were similar in CRC patients (46%). bft was detected in 21% of healthy controls and 32% of CRC patients, while double colonization by both pks + bacteria and ETBF occurred in 8% of the healthy controls and 13% of the CRC patients. Most importantly, we found that early-onset CRC (< 50 years) patients were significantly less colonized with pks + bacteria (20%) compared to late-onset CRC patients (52%). CONCLUSIONS: Healthy controls had similar levels of pks + bacteria and ETBF colonization as CRC patients, and their elevated levels may place both groups at greater risk of developing CRC. Colonization with pks + bacteria was less prevalent in early-compared to late-onset CRC.

7.
BMC Microbiol ; 21(1): 259, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34583649

RESUMO

BACKGROUND: Oral iron supplementation is commonly prescribed for anemia and may play an important role in the gut microbiota recovery of anemic individuals who received antibiotic treatment. This study aims to investigate the effects of iron supplementation on gut microbiota recovery after antibiotics exposure. RESULTS: Mice were subjected to oral antibiotic treatment with neomycin and metronidazole and were fed diets with different concentrations of iron. The composition of the gut microbiota was followed throughout treatment by 16S rRNA sequencing of DNA extracted from fecal samples. Gut microbiota functions were inferred using PICRUSt2, and short-chain fatty acid concentration in fecal samples was assessed by liquid-chromatography mass spectrometry. Iron supplementation after antibiotic exposure shifted the gut microbiota composition towards a Bacteroidetes phylum-dominant composition. At the genus level, the iron-supplemented diet induced an increase in the abundance of Parasutterella and Bacteroides, and a decrease of Bilophila and Akkermansia. Parasutterella excrementihominis, Bacteroides vulgatus, and Alistipes finegoldii, were more abundant with the iron excess diet. Iron-induced shifts in microbiota composition were accompanied by functional modifications, including an enhancement of the biosynthesis of primary bile acids, nitrogen metabolism, cyanoamino acid metabolism and pentose phosphate pathways. Recovery after antibiotic treatment increased propionate levels independent of luminal iron levels, whereas butyrate levels were diminished by excess iron. CONCLUSIONS: Oral iron supplementation after antibiotic therapy in mice may lead to deleterious changes in the recovery of the gut microbiota. Our results have implications on the use of oral iron supplementation after antibiotic exposure and justify further studies on alternative treatments for anemia in these settings.


Assuntos
Antibacterianos/efeitos adversos , Bactérias/efeitos dos fármacos , Suplementos Nutricionais/efeitos adversos , Disbiose/induzido quimicamente , Microbioma Gastrointestinal/efeitos dos fármacos , Ferro/efeitos adversos , Animais , Bactérias/classificação , Biodiversidade , Disbiose/microbiologia , Fezes/microbiologia , Ferro/farmacologia , Camundongos
8.
Clin Nutr ; 40(6): 3842-3851, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34130031

RESUMO

BACKGROUND AND AIMS: Anastomotic leak (AL) is a major complication in colorectal surgery. Recent evidence suggests that the gut microbiota may affect healing and may cause or prevent AL. Butyrate is a beneficial short-chain fatty acid (SCFA) that is produced as a result of bacterial fermentation of dietary oligosaccharides and has been described as beneficial in the maintenance of colonic health. To assess the impact of oligosaccharides on colonic anastomotic healing in mice, we propose to modulate the microbiota with oligosaccharides to increase butyrate production via enhancement of butyrate-producing bacteria and, consequently, improve anastomotic healing in mice. METHODS: Animal experiments were conducted in mice that were subjected to diets supplemented with inulin, galacto-oligosaccharides (GOS) or cellulose, as a control, for two weeks before undergoing a surgical colonic anastomosis. Macroscopic and histological assessment of the anastomosis was performed. Extent of epithelial proliferation was assessed by Ki-67 immunohistochemistry. Gelatin zymography was used to evaluate the extent of matrix metalloproteinase (MMP) hydrolytic activity. RESULTS: Inulin and GOS diets were associated with increased butyrate production and better anastomotic healing. Histological analysis revealed an enhanced mucosal continuity, and this was associated with an increased re-epithelialization of the wound as determined by increased epithelial proliferation. Collagen concentration in peri-anastomotic tissue was higher with inulin and GOS diets and MMP activity, a marker of collagen degradation, was lower with both oligosaccharides. Inulin and GOS diets were further associated with lower bacterial translocation. CONCLUSIONS: Dietary supplementation with inulin and GOS may improve anastomotic healing and reinforce the gut barrier in mice.


Assuntos
Fístula Anastomótica/prevenção & controle , Doenças do Colo/cirurgia , Ácidos Graxos Voláteis/administração & dosagem , Inulina/administração & dosagem , Animais , Suplementos Nutricionais , Modelos Animais de Doenças , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Período Perioperatório , Complicações Pós-Operatórias/prevenção & controle , Resultado do Tratamento , Cicatrização
9.
BMC Cancer ; 21(1): 172, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33596864

RESUMO

BACKGROUND: Colibactin is a genotoxin that induces DNA double-strand breaks that may lead to carcinogenesis and is produced by Escherichia coli strains harboring the pks island. Human and animal studies have shown that colibactin-producing gut bacteria promote carcinogenesis and enhance the progression of colorectal cancer through cellular senescence and chromosomal abnormalities. In this study, we investigated the impact of prebiotics on the genotoxicity of colibactin-producing E. coli strains Nissle 1917 and NC101. METHODS: Bacteria were grown in medium supplemented with 20, 30 and 40 mg/mL of prebiotics inulin or galacto-oligosaccharide, and with or without 5 µM, 25 µM and 125 µM of ferrous sulfate. Colibactin expression was assessed by luciferase reporter assay for the clbA gene, essential for colibactin production, in E. coli Nissle 1917 and by RT-PCR in E. coli NC101. The human epithelial colorectal adenocarcinoma cell line, Caco-2, was used to assess colibactin-induced megalocytosis by methylene blue binding assay and genotoxicity by γ-H2AX immunofluorescence analysis. RESULTS: Inulin and galacto-oligosaccharide enhanced the expression of clbA in pks+ E. coli. However, the addition of 125 µM of ferrous sulfate inhibited the expression of clbA triggered by oligosaccharides. In the presence of either oligosaccharide, E. coli NC101 increased dysplasia and DNA double-strand breaks in Caco-2 cells compared to untreated cells. CONCLUSION: Our results suggest that, in vitro, prebiotic oligosaccharides exacerbate DNA damage induced by colibactin-producing bacteria. Further studies are necessary to establish whether oligosaccharide supplementation may lead to increased colorectal tumorigenesis in animal models colonized with pks+ E. coli.


Assuntos
Carcinogênese/patologia , Neoplasias do Colo/patologia , Dano ao DNA , Escherichia coli/metabolismo , Mutagênicos/efeitos adversos , Oligossacarídeos/farmacologia , Peptídeos/efeitos adversos , Policetídeos/efeitos adversos , Células CACO-2 , Carcinogênese/induzido quimicamente , Senescência Celular , Neoplasias do Colo/induzido quimicamente , Neoplasias do Colo/genética , Ilhas Genômicas , Humanos
10.
Sci Rep ; 10(1): 21026, 2020 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-33273556

RESUMO

Iron homeostasis is an essential biological process that ensures the tissue distribution of iron for various cellular processes. As the major producer of hepcidin, the liver is central to the regulation of iron metabolism. The liver is also home to many immune cells, which upon activation may greatly impact iron metabolism. Here, we focus on the role of invariant natural killer T (iNKT) cells, a subset of T lymphocytes that, in mice, is most abundant in the liver. Activation of iNKT cells with the prototypical glycosphingolipid antigen, α-galactosylceramide, resulted in immune cell proliferation and biphasic changes in iron metabolism. This involved an early phase characterized by hypoferremia, hepcidin induction and ferroportin suppression, and a second phase associated with strong suppression of hepcidin despite elevated levels of circulating and tissue iron. We further show that these changes in iron metabolism are fully dependent on iNKT cell activation. Finally, we demonstrate that the biphasic regulation of hepcidin is independent of NK and Kupffer cells, and is initially driven by the STAT3 inflammatory pathway, whereas the second phase is regulated by repression of the BMP/SMAD signaling pathway. These findings indicate that iNKT activation and the resulting cell proliferation influence iron homeostasis.


Assuntos
Homeostase , Ferro/metabolismo , Células Matadoras Naturais/imunologia , Ativação Linfocitária , Animais , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Proliferação de Células , Galactosilceramidas/imunologia , Hepcidinas/genética , Hepcidinas/metabolismo , Fígado/citologia , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL
11.
PLoS Med ; 16(7): e1002847, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31265453

RESUMO

BACKGROUND: The identification of patients with high-risk prostate cancer (PC) is a major challenge for clinicians, and the improvement of current prognostic parameters is an unmet clinical need. We and others have identified an association between the nuclear localization of NF-κB p65 and biochemical recurrence (BCR) in PC in small and/or single-centre cohorts of patients. METHODS AND FINDINGS: In this study, we accessed 2 different multi-centre tissue microarrays (TMAs) representing cohorts of patients (Test-TMA and Validation-TMA series) of the Canadian Prostate Cancer Biomarker Network (CPCBN) to validate the association between p65 nuclear frequency and PC outcomes. Immunohistochemical staining of p65 was performed on the Test-TMA and Validation-TMA series, which include PC tissues from patients treated by first-line radical prostatectomy (n = 250 and n = 1,262, respectively). Two independent observers evaluated the p65 nuclear frequency in digital images of cancer tissue and benign adjacent gland tissue. Kaplan-Meier curves coupled with a log-rank test and univariate and multivariate Cox regression models were used for statistical analyses of continuous values and dichotomized data (cutoff of 3%). Multivariate analysis of the Validation-TMA cohort showed that p65 nuclear frequency in cancer cells was an independent predictor of BCR using continuous (hazard ratio [HR] 1.02 [95% CI 1.00-1.03], p = 0.004) and dichotomized data (HR 1.33 [95% CI 1.09-1.62], p = 0.005). Using a cutoff of 3%, we found that this biomarker was also associated with the development of bone metastases (HR 1.82 [95% CI 1.05-3.16], p = 0.033) and PC-specific mortality (HR 2.63 [95% CI 1.30-5.31], p = 0.004), independent of clinical parameters. BCR-free survival, bone-metastasis-free survival, and PC-specific survival were shorter for patients with higher p65 nuclear frequency (p < 0.005). As the small cores on TMAs are a limitation of the study, a backward validation of whole PC tissue section will be necessary for the implementation of p65 nuclear frequency as a PC biomarker in the clinical workflow. CONCLUSIONS: We report the first study using the pan-Canadian multi-centre cohorts of CPCBN and validate the association between increased frequency of nuclear p65 frequency and a risk of disease progression.


Assuntos
Biomarcadores Tumorais/análise , Núcleo Celular/química , Imuno-Histoquímica , Neoplasias da Próstata/química , Fator de Transcrição RelA/análise , Idoso , Neoplasias Ósseas/secundário , Canadá , Núcleo Celular/patologia , Progressão da Doença , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Variações Dependentes do Observador , Valor Preditivo dos Testes , Intervalo Livre de Progressão , Prostatectomia , Neoplasias da Próstata/mortalidade , Neoplasias da Próstata/patologia , Neoplasias da Próstata/cirurgia , Reprodutibilidade dos Testes , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Análise Serial de Tecidos
12.
PLoS One ; 14(4): e0208677, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31026259

RESUMO

Anemia is frequently encountered in patients with inflammatory bowel disease (IBD), decreasing the quality of life and significantly worsening the prognosis of the disease. The pathogenesis of anemia in IBD is multifactorial and results mainly from intestinal blood loss in inflamed mucosa and impaired dietary iron absorption. Multiple studies have proposed the use of the polyphenolic compound curcumin to counteract IBD pathogenesis since it has significant preventive and therapeutic properties as an anti-inflammatory agent and very low toxicity, even at high dosages. However, curcumin has been shown to possess properties consistent with those of an iron-chelator, such as the ability to modulate proteins of iron metabolism and decrease spleen and liver iron content. Thus, this property may further contribute to the development and severity of anemia of inflammation and iron deficiency in IBD. Herein, we evaluate the effects of curcumin on systemic iron balance in the dextran sodium sulfate (DSS) model of colitis in C57Bl/6 and BALB/c mouse strains that were fed an iron-sufficient diet. In these conditions, curcumin supplementation caused mild anemia, lowered iron stores, worsened colitis and significantly decreased overall survival, independent of the mouse strain. These findings suggest that curcumin usage as an anti-inflammatory supplement should be accompanied by monitoring of erythroid parameters to avoid exacerbation of iron deficiency anemia in IBD.


Assuntos
Anemia Ferropriva/induzido quimicamente , Anti-Inflamatórios não Esteroides/efeitos adversos , Colite/tratamento farmacológico , Curcumina/efeitos adversos , Anemia Ferropriva/metabolismo , Anemia Ferropriva/patologia , Animais , Anti-Inflamatórios não Esteroides/uso terapêutico , Colite/induzido quimicamente , Colite/patologia , Curcumina/uso terapêutico , Sulfato de Dextrana , Feminino , Ferro da Dieta/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL
13.
Front Physiol ; 9: 159, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29556203

RESUMO

Iron homeostasis is tightly regulated to provide virtually all cells in the body, particularly red blood cells, with this essential element while defending against its toxicity. The peptide hormone hepcidin is central to the control of the amount of iron absorbed from the diet and iron recycling from macrophages. Previously, we have shown that hepcidin induction in macrophages following Toll-like receptor (TLR) stimulation depends on the presence of myeloid differentiation primary response gene 88 (MyD88). In this study, we analyzed the regulation of iron metabolism in MyD88-/- mice to further investigate MyD88 involvement in iron sensing and hepcidin induction. We show that mice lacking MyD88 accumulate significantly more iron in their livers than wild-type counterparts in response to dietary iron loading as they are unable to appropriately control hepcidin levels. The defect was associated with inappropriately low levels of Smad4 protein and Smad1/5/8 phosphorylation in liver samples found in the MyD88-/- mice compared to wild-type mice. In conclusion, our results reveal a previously unknown link between MyD88 and iron homeostasis, and provide new insights into the regulation of hepcidin through the iron-sensing pathway.

14.
Front Microbiol ; 8: 1809, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28983289

RESUMO

Dietary heme can be used by colonic bacteria equipped with heme-uptake systems as a growth factor and thereby impact on the microbial community structure. The impact of heme on the gut microbiota composition may be particularly pertinent in chronic inflammation such as in inflammatory bowel disease (IBD), where a strong association with gut dysbiosis has been consistently reported. In this study we investigated the influence of dietary heme on the gut microbiota and inferred metagenomic composition, and on chemically induced colitis and colitis-associated adenoma development in mice. Using 16S rRNA gene sequencing, we found that mice fed a diet supplemented with heme significantly altered their microbiota composition, characterized by a decrease in α-diversity, a reduction of Firmicutes and an increase of Proteobacteria, particularly Enterobacteriaceae. These changes were similar to shifts seen in dextran sodium sulfate (DSS)-treated mice to induce colitis. In addition, dietary heme, but not systemically delivered heme, contributed to the exacerbation of DSS-induced colitis and facilitated adenoma formation in the azoxymethane/DSS colorectal cancer (CRC) mouse model. Using inferred metagenomics, we found that the microbiota alterations elicited by dietary heme resulted in non-beneficial functional shifts, which were also characteristic of DSS-induced colitis. Furthermore, a reduction in fecal butyrate levels was found in mice fed the heme supplemented diet compared to mice fed the control diet. Iron metabolism genes known to contribute to heme release from red blood cells, heme uptake, and heme exporter proteins, were significantly enriched, indicating a shift toward favoring the growth of bacteria able to uptake heme and protect against its toxicity. In conclusion, our data suggest that luminal heme, originating from dietary components or gastrointestinal bleeding in IBD and, to lesser extent in CRC, directly contributes to microbiota dysbiosis. Thus, luminal heme levels may further exacerbate colitis through the modulation of the gut microbiota and its metagenomic functional composition. Our data may have implications in the development of novel targets for therapeutic approaches aimed at lowering gastrointestinal heme levels through heme chelation or degradation using probiotics and nutritional interventions.

15.
Inflamm Bowel Dis ; 23(5): 753-766, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28368910

RESUMO

BACKGROUND: Iron is an important nutrient for both the host and colonizing bacteria. Oral iron supplementation may impact the composition of the microbiota and can be particularly damaging to patients suffering from inflammatory bowel disease (IBD). However, patients with IBD may require iron supplementation to treat their anemia. METHODS: We fed mice with diets supplemented with ferrous sulfate at different doses (5, 50, and 500 mg of iron/kg chow) and with different iron formulations (ferrous sulfate, ferrous bisglycinate and ferric ethylenediaminetetraacetic acid [FEDTA]), and analyzed the effects on the composition of the gut microbiota by 16S ribosomal RNA gene sequencing. Using the dextran sodium sulfate (DSS)-induced colitis mouse model, we investigated the effects of iron supplementation in colitis severity, as well as the use of the probiotic Escherichia coli Nissle 1917 (EcN) in combination with iron supplementation. RESULTS: Iron supplementation at different doses induced shifts in the gut microbial communities and inferred metabolic pathways. However, depending on the iron formulation used in the diets, iron supplementation during dextran sodium sulfate-induced colitis was either beneficial (ferrous bisglycinate) or highly detrimental (FEDTA). Finally, the beneficial effect of the probiotic EcN in the dextran sodium sulfate-induced colitis model was potentiated by oral iron supplementation with ferrous sulfate. CONCLUSIONS: These results show that the iron formulations used to treat iron deficiency influence the gut microbiota and colitis in mice and suggest that distinct iron compounds may be of particular relevance to patients with IBD. In addition, the beneficial action of probiotics in IBD may be enhanced by oral iron supplementation.


Assuntos
Colite/dietoterapia , Sulfato de Dextrana/toxicidade , Suplementos Nutricionais , Ferro/farmacologia , Microbiota , Probióticos/uso terapêutico , Animais , Colite/etiologia , Modelos Animais de Doenças , Feminino , Absorção Intestinal , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Proteção
18.
Neuropharmacology ; 79: 506-14, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24412648

RESUMO

Prolonged exposure of oligodendrocyte progenitor cultures to non-toxic concentrations of glutamate receptor agonists for 24 h decreased cellular proliferation mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Since prolonged agonist stimulation can regulate the expression of various families of receptors, we examined this possibility. Pretreatment of progenitor cultures with 100 µM kainic acid (KA) for 1-24 h caused a time-dependent decrease in AMPA receptor activity, determined by agonist-induced (45)Ca(2+) uptake. The maximum effect (70-80% decrease), observed in the 24 h-pretreated cells, was accompanied by a significant reduction in AMPA receptor subunits, as determined by Western blotting. GluR2/3 and GluR4 subunits were the most affected. Receptor down-regulation and (45)Ca(2+) uptake were only partially reversible upon KA removal. Furthermore, 24 h co-treatment of cultures with CNQX blocked the KA-induced decreases in calcium uptake. To address whether calpain, a calcium-activated protease, was implicated in the regulation of the AMPA receptor subunits, cultures were treated with the specific inhibitor PD150606 alone or in combination with KA for 24 h. Calpain inhibition significantly increased GluR1 in both conditions and partly reversed downregulation of GluR4 by KA. Collectively, these results indicate that calpain is not involved in the agonist-induced down-regulation of AMPA receptors subunits 2/3 in oligodendrocyte progenitors, while it downregulates GluR1 and GluR4.


Assuntos
Agonistas de Aminoácidos Excitatórios/farmacologia , Ácido Caínico/farmacologia , Oligodendroglia/efeitos dos fármacos , Receptores de AMPA/metabolismo , Células-Tronco/efeitos dos fármacos , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Acrilatos/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cálcio/metabolismo , Calpaína/antagonistas & inibidores , Calpaína/metabolismo , Células Cultivadas , Regulação para Baixo/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Oligodendroglia/metabolismo , Ratos Sprague-Dawley , Receptores de Glutamato Metabotrópico/metabolismo , Células-Tronco/metabolismo , Fatores de Tempo
19.
Exp Neurol ; 226(1): 47-57, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20696161

RESUMO

Fyn, a nonreceptor Src-like tyrosine kinase (SLK), plays an important role in oligodendrocyte differentiation and myelination in the brain. However, its role in myelination of peripheral nerves remains undefined. Here we report that selective inhibitors of SLKs (PP2 and SU6656) caused a dose-dependent decrease in the accumulation of several myelin proteins, including myelin basic protein (MBP), protein zero (P0) and myelin-associated glycoprotein (MAG) in rat Schwann cell-dorsal root ganglion neuron (SC-DRGN) co-cultures. Interestingly, SLK inhibition was insufficient to completely abrogate myelin synthesis, as removal of PP2 after several days of treatment permitted a partial recovery of myelin proteins expression. Furthermore, fewer and shorter myelinated segments formed in the continuous presence of PP2, although the myelin formed was normally compacted. PP2 also decreased the number of SCs expressing Krox-20, a master-regulatory transcription factor expressed by myelinating SCs, by 50%. These results were corroborated by selective knockdown of Fyn and Lyn kinases using siRNA. Extracellular matrix is important to SC differentiation and peripheral myelination. Using phospho-specific antibodies, we showed that addition of extracellular matrix extracts to SC-DRGN co-cultures resulted in the activation of ERK, Akt and p38 MAPK, three protein kinases involved in SC proliferation, differentiation and peripheral myelination. PP2 blocked the phosphorylation of all three kinases. Our results support a role for SLKs in the initiation of peripheral myelination via the activation of p38, Akt and ERK, which regulate Krox-20 expression and peripheral myelination.


Assuntos
Bainha de Mielina/enzimologia , Bainha de Mielina/fisiologia , Nervos Periféricos/enzimologia , Nervos Periféricos/fisiologia , Quinases da Família src/fisiologia , Animais , Axônios/metabolismo , Western Blotting , Células Cultivadas , Proteína 2 de Resposta de Crescimento Precoce/biossíntese , Proteína 2 de Resposta de Crescimento Precoce/genética , Matriz Extracelular/metabolismo , Gânglios Espinais/citologia , Gânglios Espinais/enzimologia , Imuno-Histoquímica , Microscopia Eletrônica , Proteínas da Mielina/biossíntese , Proteínas da Mielina/genética , Bainha de Mielina/ultraestrutura , Nervos Periféricos/ultraestrutura , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-fyn/biossíntese , RNA Interferente Pequeno , Ratos , Ratos Sprague-Dawley , Células de Schwann/enzimologia , Células de Schwann/ultraestrutura , Canais de Sódio/metabolismo , Transfecção , Proteínas Quinases p38 Ativadas por Mitógeno/biossíntese , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Quinases da Família src/antagonistas & inibidores , Quinases da Família src/genética
20.
J Neuropathol Exp Neurol ; 69(9): 930-44, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20720504

RESUMO

We examined the effects of growth factors and axonal signals on the differentiation of human fetal and adult oligodendrocyte progenitor cells (OPCs) and determined whether these effects translated into enhanced axonal ensheathment. Only small numbers of fetal OPCs grown in defined medium expressed the oligodendroglial lineage markers Olig2 and O4. The combination of platelet-derived growth factor-AA and basic fibroblast growth factor enhanced proliferation of Olig2-positive and O4-positive cells; a combination of brain-derived neurotrophic factor and insulin-like growth factor 1 promoted O4-positive cell differentiation, galactocerebroside expression, and morphological complexity. Coculturing with rodent dorsal root ganglion neurons in defined medium alone enhanced OPC differentiation and myelin basic protein expression. The addition of brain-derived neurotrophic factor/insulin-like growth factor 1 further enhanced differentiation, axonal attachment and ensheathment, and clustering of the contactin-associated protein Caspr and Na+ channels. By contrast, most adult OPCs were O4 positive and Olig2 positive in defined medium; both brain-derived neurotrophic factor/insulin-like growth factor 1 and platelet-derived growth factor-AA/basic fibroblast growth factor promoted their myelin basic protein expression and membrane sheet formation; coculture with dorsal root ganglion neurons further increased myelin basic protein expression. Growth factors also enhanced attachment of adult OPCs to axons, but their capacity to ensheath axons was lower than that of fetal OPCs. These results demonstrate that fetal and adult OPCs show measurable responses to selected growth factors and axon signals that correlate with their capacity for axon ensheathment. The distinct properties of fetal and adult OPCs may be related to differences in their chronological age and initial differentiation states.


Assuntos
Axônios/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Oligodendroglia/fisiologia , Transdução de Sinais/fisiologia , Células-Tronco/efeitos dos fármacos , Células-Tronco/fisiologia , Adulto , Animais , Axônios/ultraestrutura , Células Cultivadas , Técnicas de Cocultura , Feminino , Gânglios Espinais/citologia , Idade Gestacional , Humanos , Neurônios/citologia , Neurônios/metabolismo , Oligodendroglia/citologia , Oligodendroglia/efeitos dos fármacos , Gravidez , Ratos , Ratos Sprague-Dawley , Células-Tronco/citologia
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