16 research outputs found
Systematic Review: microRNAs as Potential Biomarkers in Mild Cognitive Impairment Diagnosis
The rate of progression from Mild Cognitive Impairment (MCI) to Alzheimer's disease (AD) is estimated at >10% per year, reaching up to 80–90% after 6 years. MCI is considered an indicator of early-stage AD. In this context, the diagnostic screening of MCI is crucial for detecting individuals at high risk of AD before they progress and manifest further severe symptoms. Typically, MCI has been determined using neuropsychological assessment tools such as the Montreal Cognitive Assessment (MoCA) or Mini-Mental Status Examination (MMSE). Unfortunately, other diagnostic methods are not available or are unable to identify MCI in its early stages. Therefore, identifying new biomarkers for MCI diagnosis and prognosis is a significant challenge. In this framework, miRNAs in serum, plasma, and other body fluids have emerged as a promising source of biomarkers for MCI and AD-related cognitive impairments. Interestingly, miRNAs can regulate several signaling pathways via multiple and diverse targets in response to pathophysiological stimuli. This systematic review aims to describe the current state of the art regarding AD-related target genes modulated by differentially expressed miRNAs in peripheral fluids samples in MCI subjects to identify potential miRNA biomarkers in the early stages of AD. We found 30 articles that described five miRNA expression profiles from peripheral fluid in MCI subjects, showing possible candidates for miRNA biomarkers that may be followed up as fluid biomarkers or therapeutic targets of early-stage AD. However, additional research is needed to validate these miRNAs and characterize the precise neuropathological mechanisms.Fil: Ogonowski, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Adolfo Ibañez; ChileFil: Salcidua, Stefanny. Universidad Adolfo Ibañez; ChileFil: Leon, Tomas. Universidad de Chile; Chile. Trinity College; IrlandaFil: Chamorro Veloso, Nayaret. Neurognos Spa; ChileFil: Valls, Cristian. Neurognos Spa; ChileFil: Avalos, Constanza. Universidad Adolfo Ibañez; ChileFil: Bisquertt, Alejandro. Neurognos Spa; ChileFil: Rentería, Miguel E.. Berghofer Medical Research Institute; AustraliaFil: Orellana, Paulina. Universidad Adolfo Ibañez; ChileFil: Duran Aniotz, Claudia. Universidad Adolfo Ibañez; Chil
Diversidad de las comunidades microbianas adherentes en biopsias de mucosa colónica de pacientes chilenos y españoles con enfermedad de Crohn y colitis ulcerosa
Tesis entregada a la Universidad de Chile en cumplimiento parcial de los requisitos para optar al grado de Doctor en Ciencias con mención en MicrobiologíaLa mayor concentración y diversidad de microorganismos asociados a la microbiota humana reside en el intestino, estableciendo una relación comensal o mutualista con el hospedero, la cual puede verse interrumpida cuando la estructura y composición microbiana es alterada (disbiosis). La disbiosis puede estar asociada a cambios en la dieta, el uso de antibióticos y en una serie de enfermedades, entre ellas las enfermedades inflamatorias intestinales (EII) como Colitis Ulcerosa (CU) y Enfermedad de Crohn (EC). Si bien la mayor parte de los estudios sobre microbiota intestinal se han realizado a partir muestras de heces debido a su fácil obtención, la microbiota adherente del colon es la más representativa de la comunidad microbiológica que co-evoluciona con el hospedero en el transcurso de la enfermedad, pues ésta puede interactuar de forma más directa con el sistema inmunitario. Considerando los antecedentes expuestos el objetivo de esta tesis es la caracterización de la microbiota adherente de individuos con EII mediante análisis de secuenciación masiva y generación de librerías de rDNA16S, a partir de muestras de biopsias de individuos chilenos y españoles (n=66) diagnosticados con EC, CU y controles (CTL). Nuestros resultados mostraron diferencias significativas entre la abundancia relativa de las phyla Proteobactería y Firmicutes entre individuos con EII y CTL, sin embargo no observamos diferencias significativas entre la microbiota de individuos con CU y EC. Por otro lado, a diferencia de los estudios realizados con muestras de heces, donde los individuos con EII fueron clasificados en grupos únicos y definidos (EC, CU o CTL), en nuestro estudio los individuos con EII se clasificaron en 5 grupos distintos según su composición microbiana. Los grupo denominados EII-1, EII-3, EII-2 y EII-5 albergaron únicamente individuos con EC y CU, presentando un enriquecimiento de las phyla Bacteroidetes (34.5%), Proteobacteria (75.4%), y de las Unidades Filogenéticas Operacionales (OPUs) afiliadas a las bacterias Ruminococcus gnavus (9.75%); Cupriavidus necator/Ralstonia pickettii (6.60%); Brevundimonas diminuta/Brevundimonas vancanneytii (5.87%) y Klebsiella oxytoca (32.16%). El grupo EII-4 contuvo individuos con EII y CTL mostrando un enriquecimiento del phylum Firmicutes (59.85%) y OPUs afiliados a Faecalibacterium prausnitzii (14.67%), (bacteria características de individuos sanos). Sumado a los anterior aquellos individuos pertenecientes a los grupos EII-3, EII-2 y EII-5 presentaron abundancias que abarcaron entre el 12.74 al 55.60% en OPUs afiliados a bacterias anaeróbicas facultativas y abundancias del 4.25% al 9.68% en OPUs afiliados a bacterias aeróbias estrictas. Por el contrario, los grupos EII-4 y EII-1 abarcaron abundancias del 41.21% al 45.3% en OPUs afiliados a bacterias anaerobias obligadas y abundancias cercanas al 1.5% en OPUs afiliados a bacterias aerobias estrictas. Además, los análisis de correlación mostraron asociaciones negativas entre los OPUs anaerobios facultativos o aerobios, (indicadores de individuos con EII pertenecientes a los grupos EII-1, EII-2, EII-3, EII-5) con aquellos OPUs anaerobios (indicadoras de EII-4). Este tipo de correlación da cuenta de relaciones de competencia (exclusión) entre estas bacterias, dadas posiblemente por las condiciones ambientales del intestino, es decir un incremento en los niveles de oxígeno durante el proceso de inflamación. Estos resultados concuerdan con lo sugerido en la “hipótesis del oxígeno”, donde se plantea que en condiciones de inflamación crónica las paredes intestinales de individuos con EII conducen a una mayor liberación de hemoglobina (que lleva oxígeno), y especies reactivas de oxígeno a la luz del intestinal. Sumado a lo anterior, los colonocitos bajo señales pro-inflamatorias realizarían un cambio en su metabolismo hacia una glicólisis anaeróbica, la cual no consume oxígeno permitiendo que este difunda hacia el epitelio intestinal conduciendo así un ambiente favorable para bacterias anaerobias facultativas y aerobias.
En este contexto, uno de los componentes de la respuesta inmune innata que parece controlar la población que conforma la microbiota intestinal son los péptidos antimicrobianos (PAMs). Entre los PAMs estudiados en el epitelio colónico se encuentran las Catelicidina (CAMP) y β-defensinas (hBD), los cuales poseen actividad antimicrobiana sobre grupos bacterianos específicos. Modelos murinos que sobreexpresan PAMs muestran una disbiosis con respecto a sus pares silvestres, dando cuenta de la importancia de los PAMs como reguladores de la composición microbiana intestinal. Adicionalmente, investigaciones recientes han demostrado que pacientes con EII poseen una expresión alterada de PAMs con respecto a individuos CTL. En esta línea de pensamiento, esta tesis propuso como hipótesis “El aumento de la población de Proteobacteria observado en la mucosa intestinal en pacientes con EC con respecto a pacientes CU, se asocia con la disminución en la expresión de péptidos antimicrobianos CAMP y hBD 2-4”. Sin embargo, debido al bajo número de muestras que permitieran obtener un RNA íntegro y de calidad para analizar los niveles de expresión de los PAMs CAMP y hBD-2, no fue posible demostrar que nuestros resultados fueron significativos en la correlación con respecto a los phylum bacterianos. En esta condición esta hipótesis no puede ser aceptada ni rechazada.The highest concentration and diversity of microorganisms belonging to the human microbiota reside in the intestine, establishing a commensal or mutualistic relationship with the host. This relationship can be modified when the microbial structure and composition is altered (dysbiosis). Dysbiosis may be associated to changes in diet, use of antibiotics and to a number of diseases, including inflammatory bowel diseases (IBD) such as Ulcerative Colitis (UC) and Crohn's Disease (CD). Although, due to the easiness to collect them, most of the studies on intestinal microbiota are carried out analyzing stool samples, the adherent microbiota of the colon is representative of the microbial community which co-evolves with the host, interacting directly with the immune system, during the course of the disease. Considering the above, the aim of this thesis was to characterize the adherent microbiota of individuals suffering IBD by means of massive sequencing analysis. Samples (biopsies) were obtained from Chilean and Spanish individuals (n = 66) diagnosed with CD, UC, and control (CTL). Our results showed significant differences between the relative abundance of phyla Proteobacteria and Firmicutes among individuals with IBD and CTL but no differences were observed when comparing the microbiota of individuals with UC and CD. Unlike the studies based on stool samples, in which individuals with IBD are classified as unique and defined groups (CD, CU or CTL) in our study individuals with IBD were classified into five different groups according to their microbial composition. Groups IBD-1, IBD-3, IBD-2 and IBD-5 contained only individuals with CD and UC, presenting an enrichment of phyla Bacteroidetes (34.5%) and Proteobacteria (75.4%) and Operational Phylogenetic Units (OPUs) affiliated with bacteria Ruminococcus gnavus (9.75%) ;Cupriavidus necator / Ralstonia pickettii (6.60%); Brevundimonas diminuta / B revundimonas vancanneytii (5.87%) and Klebsiella oxytoca (32.16%). Group IBD-4 contained individuals with IBD and CTL showing an enrichment of phylum Firmicutes (59.85%) and OPUs affiliated with Faecalibacterium prausnitzii (14.67%), (bacterium characteristic of healthy individuals). In addition to the above, individuals belonging to groups IBD-3, IBD-2 and IBD-5 showed abundances between 12.74 to 55.60% of OPUs affiliated to anaerobic or facultative bacteria, and abundances of 4.25% to 9.68% of OPUs affiliated to obligate aerobes. On the contrary, groups IBD-4 and IBD-1 showed abundances of 41.21% to 45.3% of OPUs affiliated with obligated anaerobic bacteria and abundances close to 1.5% of OPUs affiliated to obligated aerobic bacteria. In addition, correlation analyzes showed negative associations between facultative anaerobic and aerobic OPUs (indicators of individuals with IBD belonging to groups IBD-1, IBD-2, IBD-3, IBD-5) with those obligated anaerobic OPUs (indicators of IBD-4). This kind of correlation exemplifies competition relationships (exclusion) between these bacteria, possibly due to the environmental conditions of the intestine, i.e. an increase in oxygen levels during the process of inflammation. These results are consistent with the "oxygen hypothesis" which proposes that in/under conditions of chronic inflammation, causing the release of oxygen carrying hemoglobin in the intestinal mucosa and reactive oxygen species in the intestinal lumen. In addition, colonocytes under pro-inflammatory signals shift their metabolism towards an oxygen consuming anaerobic glycolysis, increasing epithelial oxygenation which leads to a favorable environment for facultative and aerobic bacteria.
One of the components of the innate immune response that seems to control the microbial population are the antimicrobial peptides (AMPs). Among the AMPs studied in the colonic epithelium, Cathelicidin (CAMP) and β-defensins (hBD), which have antimicrobial activity on specific bacterial groups, can be mentioned. Murine models overexpressing AMPs showed a dysbiosis when compared to their wild type mates, revealing the importance of AMPs as regulators of the intestinal microbial composition. Additionally, recent research showed that patients with IBD have an altered expression of AMPs when compared to CTL individuals. In this context, this thesis proposed the following hypothesis: "The increase in the population of Proteobacteria observed in the intestinal mucosa in patients with CD when compared to patients with UC is associated with the decrease in the expression of antimicrobial peptides CAMP and hBD 2-4". However, due to the low number of samples that allowed to obtain a high-quality RNA to analyze the levels of expression of the CAMP and hBD-2 MAPs, it was not possible to demonstrate that our results were significant in the correlation of MAPs with bacterial phyla. In this condition this hypothesis cannot be accepted or rejected.Fundación Maria Ghilardi, beca para estudios de postgrado durante el año 2013, Comisión Nacional de Ciencia y Tecnología (CONICYT-21140975), beca para estudios de Doctorado (años 2014-2017) y FONDECYT 1161161
New insights for vaccine development against Clostridium difficile infections
Increased antibiotic usage is the main risk factor for gut microbiota dysbiosis. In dysbiosis, there is an increased susceptibility to intestinal pathogens, such as Clostridium difficile infection, the leading cause of hospital-acquired infection worldwide. High-spectrum antibiotics, such as vancomycin or metronidazole, also increases the risk of developing CDI symptoms after the treatment. An impaired immune response could also be responsible for the high incidence of recurrence of CDI (R-CDI), suggesting that immune system stimulation could help eradicate the infection in patients suffering multiple episodes in CDI or prevent the infective course. Here, we discuss novel immunotherapeutic approaches that aid the immune system to target C. difficile and how these can be improved
Distinctive gut microbiota is associated with diarrheagenic Escherichia coli infections in chilean children
Background: Diarrheagenic Escherichia coli (DEC) strains are a major cause of diarrhea in children under 5 years of age worldwide. DEC pathogenicity relies on the interaction of bacteria with environmental factors, including the host's resident gut microbiota. Previous reports have shown changes in the gut microbiota's composition during episodes of diarrhea, which may increase the pathogenicity of DEC strains. More intense and detailed identification of microbiota strains specifically associated with DEC infections and disease is needed to pinpoint their role in DEC pathogenicity.
Aim: To identify resident indicative bacterial taxa in DEC-positive diarrhea stool samples of Chilean children.
Methods: We analyzed 63 diarrheal stool samples from children 1-5 years of age by FilmArray (R) GI in order to identify a potential pathogen and to group diarrhea episodes into those caused by DEC as sole pathogen (DEC group, 32 samples) and those caused by an enteric virus as sole pathogen (viral group, 31 samples). In addition, 30 stool samples from healthy children, negative for enteric pathogens, were evaluated (healthy group). The 16S rRNA gene was amplified and sequenced using 454 pyrosequencing. Sequences were clustered into operational taxonomic units (OTUs) at 99% identity and their representatives were used to assign them to operational phylogenetic units (OPUs) using a phylogenetic inference approach.
Results: Taxa assignment using the OPU approach resulted in a lower number of units but with higher accuracy compared to the OTU approach. Data analysis indicated an increase in sequences belonging to the phylum Proteobacteria in the DEC group compared to the viral and healthy groups. Samples displayed a statistically different community structure by sample grouping by redundancy analysis and ANOVA. Escherichia albertii (p = 0.001), Citrobacter werkmanii (p = 0.001), Yersinia enterocolitica, subsp. paleartica (p = 0.048), and Haemophilus sputorum (p = 0.028) were indicative species for the DEC group as compared to the viral and healthy groups.
Conclusion: Gut microbiota in Chilean children with DEC-positive diarrhea differed from microbiota associated with enteric virus and healthy children. Indicative species found in this study may prove relevant in advancing our understanding of the relationship between resident gut microbiota and DEC leading to the occurrence of disease.FONDECYT
1160426
1120809
1161161
CONICYT-PCHA/Doctorado
Nacional/2014-21140975
Nacional/2015-2115037
Deciphering Additional Roles for the EF-Tu, l-Asparaginase II and OmpT Proteins of Shiga Toxin-Producing Escherichia coli
Shiga toxin-producing Escherichia coli (STEC) causes outbreaks and sporadic cases of gastroenteritis. STEC O157:H7 is the most clinically relevant serotype in the world. The major virulence determinants of STEC O157:H7 are the Shiga toxins and the locus of enterocyte effacement. However, several accessory virulence factors, mainly outer membrane proteins (OMPs) that interact with the host cells may contribute to the virulence of this pathogen. Previously, the elongation factor thermo unstable (EF-Tu), l-asparaginase II and OmpT proteins were identified as antigens in OMP extracts of STEC. The known subcellular location of EF-Tu and l-asparaginase II are the cytoplasm and periplasm, respectively. Therefore, we investigate whether these two proteins may localize on the surface of STEC and, if so, what roles they have at this site. On the other hand, the OmpT protein, a well characterized protease, has been described as participating in the adhesion of extraintestinal pathogenic E. coli strains. Thus, we investigate whether OmpT has this role in STEC. Our results show that the EF-Tu and l-asparaginase II are secreted by O157:H7 and may also localize on the surface of this bacterium. EF-Tu was identified in outer membrane vesicles (OMVs), suggesting it as a possible export mechanism for this protein. Notably, we found that l-asparaginase II secreted by O157:H7 inhibits T-lymphocyte proliferation, but the role of EF-Tu at the surface of this bacterium remains to be elucidated. In the case of OmpT, we show its participation in the adhesion of O157:H7 to human epithelial cells. Thus, this study extends the knowledge of the pathogenic mechanisms of STEC
Glucocorticoids impair phagocytosis and inflammatory response against crohn's disease-associated adherent-invasive escherichia coli
Crohn's disease (CD) is a chronic inflammatory bowel disorder characterized by deregulated inflammation triggered by environmental factors Notably, adherent-invasive Escherichia coli (AIEC), a bacterium with the ability to survive within macrophages is believed to be one of such factors Glucocorticoids are the first line treatment for CD and to date, it is unknown how they affect bactericidal and inflammatory properties of macrophages against AIEC The aim of this study was to evaluate the impact of glucocorticoid treatment on AIEC infected macrophages First, THP-1 cell-derived macrophages were infected with a CD2-a AIEC strain, in the presence or absence of the glucocorticoid dexamethasone (Dex) and mRNA microarray analysis was performed Differentially expressed mRNAs were confirmed by TaqMan-qPCR. In addition, an amikacin protection assay was used to evaluate the phagocytic and bactericidal activity of Dex-treated macrophages infected with E. coli strains (CD2-a, HM605, NRG857c, and HB101). Finally, cytokine secretion and the inflammatory phenotype of macrophages were evaluated by ELISA and flow cytometry, respectively The microarray analysis showed that CD2-a, Dex, and CD2-a + Dex-treated macrophages have differential inflammatory gene profiles Also, canonical pathway analysis revealed decreased phagocytosis signaling by Dex and anti inflammatory polarization on CD2-a + Dex macrophages. Moreover, amikacin protection assay showed reduced phagocytosis upon Dex treatment and TaqMan-qPCR confirmed Dex inhibition of three phagocytosis-associated genes All bacteria strains induced TNF-alpha, IL-6, IL-23, CD40, and CD80, which was inhibited by Dex Thus, our data demonstrate that glucocorticoids impair phagocytosis and induce anti-inflammatory polarization after AIEC infection, possibly contributing to the survival of AIEC in infected CD patients.Fondecyt
1120577
1170648
3150328
MECESUP
uch1304
CLC PI
2012-DA015
Conicyt
21120682
Fondequip
EQM 15003
image_8_Glucocorticoids Impair Phagocytosis and Inflammatory Response Against Crohn’s Disease-Associated Adherent-Invasive Escherichia coli.PDF
<p>Crohn’s disease (CD) is a chronic inflammatory bowel disorder characterized by deregulated inflammation triggered by environmental factors. Notably, adherent-invasive Escherichia coli (AIEC), a bacterium with the ability to survive within macrophages is believed to be one of such factors. Glucocorticoids are the first line treatment for CD and to date, it is unknown how they affect bactericidal and inflammatory properties of macrophages against AIEC. The aim of this study was to evaluate the impact of glucocorticoid treatment on AIEC infected macrophages. First, THP-1 cell-derived macrophages were infected with a CD2-a AIEC strain, in the presence or absence of the glucocorticoid dexamethasone (Dex) and mRNA microarray analysis was performed. Differentially expressed mRNAs were confirmed by TaqMan-qPCR. In addition, an amikacin protection assay was used to evaluate the phagocytic and bactericidal activity of Dex-treated macrophages infected with E. coli strains (CD2-a, HM605, NRG857c, and HB101). Finally, cytokine secretion and the inflammatory phenotype of macrophages were evaluated by ELISA and flow cytometry, respectively. The microarray analysis showed that CD2-a, Dex, and CD2-a + Dex-treated macrophages have differential inflammatory gene profiles. Also, canonical pathway analysis revealed decreased phagocytosis signaling by Dex and anti-inflammatory polarization on CD2-a + Dex macrophages. Moreover, amikacin protection assay showed reduced phagocytosis upon Dex treatment and TaqMan-qPCR confirmed Dex inhibition of three phagocytosis-associated genes. All bacteria strains induced TNF-α, IL-6, IL-23, CD40, and CD80, which was inhibited by Dex. Thus, our data demonstrate that glucocorticoids impair phagocytosis and induce anti-inflammatory polarization after AIEC infection, possibly contributing to the survival of AIEC in infected CD patients.</p
image_2_Glucocorticoids Impair Phagocytosis and Inflammatory Response Against Crohn’s Disease-Associated Adherent-Invasive Escherichia coli.PDF
<p>Crohn’s disease (CD) is a chronic inflammatory bowel disorder characterized by deregulated inflammation triggered by environmental factors. Notably, adherent-invasive Escherichia coli (AIEC), a bacterium with the ability to survive within macrophages is believed to be one of such factors. Glucocorticoids are the first line treatment for CD and to date, it is unknown how they affect bactericidal and inflammatory properties of macrophages against AIEC. The aim of this study was to evaluate the impact of glucocorticoid treatment on AIEC infected macrophages. First, THP-1 cell-derived macrophages were infected with a CD2-a AIEC strain, in the presence or absence of the glucocorticoid dexamethasone (Dex) and mRNA microarray analysis was performed. Differentially expressed mRNAs were confirmed by TaqMan-qPCR. In addition, an amikacin protection assay was used to evaluate the phagocytic and bactericidal activity of Dex-treated macrophages infected with E. coli strains (CD2-a, HM605, NRG857c, and HB101). Finally, cytokine secretion and the inflammatory phenotype of macrophages were evaluated by ELISA and flow cytometry, respectively. The microarray analysis showed that CD2-a, Dex, and CD2-a + Dex-treated macrophages have differential inflammatory gene profiles. Also, canonical pathway analysis revealed decreased phagocytosis signaling by Dex and anti-inflammatory polarization on CD2-a + Dex macrophages. Moreover, amikacin protection assay showed reduced phagocytosis upon Dex treatment and TaqMan-qPCR confirmed Dex inhibition of three phagocytosis-associated genes. All bacteria strains induced TNF-α, IL-6, IL-23, CD40, and CD80, which was inhibited by Dex. Thus, our data demonstrate that glucocorticoids impair phagocytosis and induce anti-inflammatory polarization after AIEC infection, possibly contributing to the survival of AIEC in infected CD patients.</p
image_5_Glucocorticoids Impair Phagocytosis and Inflammatory Response Against Crohn’s Disease-Associated Adherent-Invasive Escherichia coli.PDF
<p>Crohn’s disease (CD) is a chronic inflammatory bowel disorder characterized by deregulated inflammation triggered by environmental factors. Notably, adherent-invasive Escherichia coli (AIEC), a bacterium with the ability to survive within macrophages is believed to be one of such factors. Glucocorticoids are the first line treatment for CD and to date, it is unknown how they affect bactericidal and inflammatory properties of macrophages against AIEC. The aim of this study was to evaluate the impact of glucocorticoid treatment on AIEC infected macrophages. First, THP-1 cell-derived macrophages were infected with a CD2-a AIEC strain, in the presence or absence of the glucocorticoid dexamethasone (Dex) and mRNA microarray analysis was performed. Differentially expressed mRNAs were confirmed by TaqMan-qPCR. In addition, an amikacin protection assay was used to evaluate the phagocytic and bactericidal activity of Dex-treated macrophages infected with E. coli strains (CD2-a, HM605, NRG857c, and HB101). Finally, cytokine secretion and the inflammatory phenotype of macrophages were evaluated by ELISA and flow cytometry, respectively. The microarray analysis showed that CD2-a, Dex, and CD2-a + Dex-treated macrophages have differential inflammatory gene profiles. Also, canonical pathway analysis revealed decreased phagocytosis signaling by Dex and anti-inflammatory polarization on CD2-a + Dex macrophages. Moreover, amikacin protection assay showed reduced phagocytosis upon Dex treatment and TaqMan-qPCR confirmed Dex inhibition of three phagocytosis-associated genes. All bacteria strains induced TNF-α, IL-6, IL-23, CD40, and CD80, which was inhibited by Dex. Thus, our data demonstrate that glucocorticoids impair phagocytosis and induce anti-inflammatory polarization after AIEC infection, possibly contributing to the survival of AIEC in infected CD patients.</p
image_7_Glucocorticoids Impair Phagocytosis and Inflammatory Response Against Crohn’s Disease-Associated Adherent-Invasive Escherichia coli.PDF
<p>Crohn’s disease (CD) is a chronic inflammatory bowel disorder characterized by deregulated inflammation triggered by environmental factors. Notably, adherent-invasive Escherichia coli (AIEC), a bacterium with the ability to survive within macrophages is believed to be one of such factors. Glucocorticoids are the first line treatment for CD and to date, it is unknown how they affect bactericidal and inflammatory properties of macrophages against AIEC. The aim of this study was to evaluate the impact of glucocorticoid treatment on AIEC infected macrophages. First, THP-1 cell-derived macrophages were infected with a CD2-a AIEC strain, in the presence or absence of the glucocorticoid dexamethasone (Dex) and mRNA microarray analysis was performed. Differentially expressed mRNAs were confirmed by TaqMan-qPCR. In addition, an amikacin protection assay was used to evaluate the phagocytic and bactericidal activity of Dex-treated macrophages infected with E. coli strains (CD2-a, HM605, NRG857c, and HB101). Finally, cytokine secretion and the inflammatory phenotype of macrophages were evaluated by ELISA and flow cytometry, respectively. The microarray analysis showed that CD2-a, Dex, and CD2-a + Dex-treated macrophages have differential inflammatory gene profiles. Also, canonical pathway analysis revealed decreased phagocytosis signaling by Dex and anti-inflammatory polarization on CD2-a + Dex macrophages. Moreover, amikacin protection assay showed reduced phagocytosis upon Dex treatment and TaqMan-qPCR confirmed Dex inhibition of three phagocytosis-associated genes. All bacteria strains induced TNF-α, IL-6, IL-23, CD40, and CD80, which was inhibited by Dex. Thus, our data demonstrate that glucocorticoids impair phagocytosis and induce anti-inflammatory polarization after AIEC infection, possibly contributing to the survival of AIEC in infected CD patients.</p