Identification of peptides presented through the MHC-II of dendritic cells stimulated with Mycobacterium avium.

Mycobacterium avium (M. avium) represents a species of concern, because of its ability to modulate the host's innate immune response, and therefore influence trajectory of adaptative immunity. Since eradicative response against mycobacteria, and M. tuberculosis/M. avium, relies on peptides actively presented on a Major Histocompatibility complex-II (MHC-II) context, we assessed paradoxical stimulation of Dendritic Cell resulting on immature immunophenotype characterized by membrane minor increase of MHC-II and CD40 despite of high expression of the pro-inflammatory tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in supernatants. Identification of M. avium leucine rich peptides forming short α-helices shutting down Type 1T helper (Th1), contribute to the understanding of immune evasion of an increasingly prevalent pathogen, and may provide a basis for future immunotherapy to infectious and non-infectious disease.

Overexpression of proinflammatory cytokines in dental pulp tissue and distinct bacterial microbiota in carious teeth of Mexican Individuals.

The prevalence of dental caries in the Mexican adult population aged 20 to 85 years is around 93.3%, and 50% in Mexican children and adolescents. Worldwide, it is the most common non-communicable disease. One of the main etiological factors for dental caries is the oral microbiome and changes in its structure and function, with an expansion of pathogenic bacteria like Streptococcus mutans. The exposed dental pulp tissue triggers an innate immune response to counteract this bacterial invasion. The relation between oral dysbiosis and innate immune responses remains unclear. We aimed to understand the relationship between innate immune response and the oral microbiota by quantifying the expression of Toll-like receptors (TLRs) and proinflammatory markers (cytokines and a chemokine) in dental pulp tissue, either exposed or not to carious dentin, and to correlate this information with the oral microbiome found in healthy teeth and those with moderate caries. RNA was purified from pulp tissue, subjected to RT-qPCR and analysed with the ΔΔCt method. Supragingival dental plaque of non-carious teeth and dentin of carious teeth were subjected to 16S targeted sequencing. Principal coordinate analysis, permutational multivariate ANOVA, and linear discriminant analysis were used to assess differences between non-carious and carious teeth. Correlations were assessed with Spearman´s test and corrected for multiple comparisons using the FDR method. The relative abundance (RA) of Lactobacillus, Actinomyces, Prevotella, and Mitsuokella was increased in carious teeth; while the RA of Haemophilus and Porphyromonas decreased. Olsenella and Parascardovia were only detected in carious teeth. Significant overexpression of interleukin 1 beta (IL1 ß), IL6, and CXCL8 was detected in pulp tissue exposed to carious dentin. IL1ß correlated positively with TLR2 and Actinomyces; yet negatively with Porphyromonas. These findings suggest that immune response of pulp tissue chronically exposed to cariogenic microbiome is triggered by proinflammatory cytokines IL1ß and IL6 and the chemokine CXCL8.

The Cysteine Protease Giardipain-1 from Giardia duodenalis Contributes to a Disruption of Intestinal Homeostasis.

In giardiasis, diarrhoea, dehydration, malabsorption, weight loss and/or chronic inflammation are indicative of epithelial barrier dysfunction. However, the pathogenesis of giardiasis is still enigmatic in many aspects. Here, we show evidence that a cysteine protease of Giardia duodenalis called giardipain-1, contributes to the pathogenesis of giardiasis induced by trophozoites of the WB strain. In an experimental system, we demonstrate that purified giardipain-1 induces apoptosis and extrusion of epithelial cells at the tips of the villi in infected jirds (Meriones unguiculatus). Moreover, jird infection with trophozoites expressing giardipain-1 resulted in intestinal epithelial damage, cellular infiltration, crypt hyperplasia, goblet cell hypertrophy and oedema. Pathological alterations were more pronounced when jirds were infected intragastrically with Giardia trophozoites that stably overexpress giardipain-1. Furthermore, Giardia colonization in jirds results in a chronic inflammation that could relate to the dysbiosis triggered by the protist. Taken together, these results reveal that giardipain-1 plays a key role in the pathogenesis of giardiasis.

Microbioma oral: variabilidad entre regiones y poblaciones / Oral Microbiome: Variability Between Regions and Populations

Resumen De acuerdo con la Organización Mundial de la Salud (OMS), 3.58 billones de personas son afectadas por desórdenes orales, donde la caries, seguida de la enfermedad periodontal son las más frecuentes y las principales causas de daño al tejido pulpar y pérdida de órganos dentales. En México, el Sistema de Vigilancia Epidemiológica de Patologías Bucales (SIVEPAB) reportó que el 53% de la población se ve afectada por algún grado de enfermedad periodontal, mientras que en promedio la caries afecta al 93.3% de la población de entre 20 a 85 años y más, así como a alrededor del 50.0% de niños y adolescentes, por lo que ambos padecimientos son considerados un problema de salud pública importante en este país. Adicionalmente, se sabe que el microbioma oral humano está asociado con la salud y la enfermedad bucodental. Entre los géneros bacterianos que comúnmente habitan la cavidad oral humana destacan Streptococcus spp., Lactobacillus spp. y Porphyromonas spp. que, a través del desequilibrio del microbioma oral (disbiosis), se asocian con la caries o la enfermedad periodontal. En vista de que estamos constantemente expuestos a este tipo de infecciones crónicas inflamatorias, se sabe que las bacterias orales se trasladan a otras partes del cuerpo contribuyendo al desarrollo y exacerbación de la inflamación sistémica y otras enfermedades. Ya que existen factores como la ubicación geográfica, además de la disbiosis, la edad, la dieta y la genética, que influyen en la variabilidad del microbioma humano. Es importante analizar la diversidad del microbioma oral desde esta perspectiva, ya que el conocimiento que se tiene hasta el momento aún es escaso; por lo anterior se realizó una búsqueda de artículos publicados entre 2010 y 2020 en poblaciones de Asia, África, América y Europa, con el fin de responder la siguiente pregunta: ¿el factor geográfico tiene un impacto en la composición de la variabilidad del microbioma oral humano?

Abstract According to the World Health Organization (WHO), 3.58 billion people were affected by oral disorders, where caries, followed by periodontal disease are the most frequent and the main causes of damage to pulp tissue and loss of dental organs. In Mexico, the Epidemiological Surveillance System for Oral Pathologies (SIVEPAB) reported that 53% of the population is affected by some degree of periodontal disease, while on average caries affects 93.3% of the population between 20 and 85 years old and older, as well as about 50.0% of children and adolescents, so both conditions are considered an important public health problem in this country. Additionally, the human oral microbiome is known to be associated with oral health and disease. An imbalance in the oral microbiome (dysbiosis) can result in the proliferation of Streptococcus mutans and Porphyromonas gingivalis, linked to caries and periodontal disease. The latter two conditions, the most prevalent oral diseases worldwide, are the main causes of damage to pulp tissue and loss of dental organs. In the presence of these pathologies, constant exposure to the corresponding inflammatory chronic infection could lead to the translocation of oral bacteria to other parts of the body, where they may contribute to the development and/or exacerbation of systemic inflammation and trigger disease. Since age, diet, genetics, and geographical location are known to influence the variability of the human microbiome, it is important to analyze differences in the oral microbiome between distinct populations. Up to now, little attention has been given to this task. The current review carried out for articles published between 2010 and 2020 and describes the human oral microbiome in populations of Asia, Africa, America and Europa, to explore whether geographical differences have an impact on the variability of the human oral microbiome.

RNA Microarray-Based Comparison of Innate Immune Phenotypes between Human THP-1 Macrophages Stimulated with Two BCG Strains.

Currently, the only available vaccine against tuberculosis is Mycobacterium bovis Bacille Calmette-Guérin (BCG). Pulmonary tuberculosis protection provided by the vaccine varies depending on the strain, the patient's age and the evaluated population. Although the adaptive immune responses induced by different BCG strains have been widely studied, little conclusive data is available regarding innate immune responses, especially in macrophages. Here, we aimed to characterize the innate immune responses of human THP-1-derived macrophages at the transcriptional level following a challenge with either the BCG Mexico (M.BCG) or Phipps (P.BCG) strains. After a brief in vitro characterization of the bacterial strains and the innate immune responses, including nitric oxide production and cytokine profiles, we analyzed the mRNA expression patterns and performed pathway enrichment analysis using RNA microarrays. Our results showed that multiple biological processes were enriched, especially those associated with innate inflammatory and antimicrobial responses, including tumor necrosis factor (TNF)-α, type I interferon (IFN-I) and IFN-γ. However, four DEGs were identified in macrophages infected with M.BCG compared to P. BCG. These findings indicated the proinflammatory stimulation of macrophages induced by both BCG strains, at the cytokine level and in terms of gene expression, suggesting a differential expression pattern of innate immune transcripts depending on the mycobacterial strain.

Non-tuberculous mycobacteria immunopathogenesis: Closer than they appear. a prime of innate immunity trade-off and NTM ways into virulence.

INTRODUCTION: The growing incidence of non-tuberculous mycobacteria (NTM) and changes in epidemiological factors have indicated that immune dysregulation may be associated with the emergence of NTM. Minireview entails to acknowledge complex interaction and new ways NTM are evolving around diverse immune status. METHODS: In order to perform this review, we selected peer reviewed, NLM database articles under the terms NTM, mycobacterium complex 'AND' -Host- immune response, immunity regulation, Disease, Single Nucleotide Polymorphism (SNP´s), and -pathogen- followed by a snow ball rolling basis search on immune components and NTM related with diseases distribution. RESULTS: The universal exposure and diversity of NTM are well-documented; however, hospitals seldom establish vigilant control of water quality or immunodeficiencies for patients with NTM infections. Depending on the chemical structures and immune mechanisms presented by various NTM varieties, they can trigger different effects in dendritic and natural killer cells, which release interleukin (IL)-17, tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and rIL-1B. The T helper (Th)2-acquired immune response is responsible for autoimmune responses in patients with NTM infections, and, quite disturbingly, immunocompetent patients have been reported to suffer from NTM infections. CONCLUSION: New technologies and a comprehensive view has taught us; to acknowledge metabolic/immune determinants and trade-offs along transit through mutualism-parasite continuous.

Integrative and Conjugative Elements of Helicobacter pylori Are Hypothetical Virulence Factors Associated With Gastric Cancer.

Helicobacter pylori is a bacteria with high genome plasticity that has been associated with diverse gastric pathologies. The genetic diversity of this bacteria has limited the characterization of virulence factors associated with gastric cancer (GC). To identify potentially helpful disease biomarkers, we compared 38 complete genomes and 108 draft genomes of H. pylori isolated worldwide from patients with diverse gastric pathologies and 53 draft genomes of H. pylori isolated from Mexican patients with GC, intestinal metaplasia, gastritis, peptic ulcer, and dyspepsia. H. pylori strains isolated from GC were 3-11 times more likely to harbor any of seven genes encoded within an integrative and conjugative element (ICE) than H. pylori isolated from subjects with other gastric pathologies. We tested the cytopathic effects on AGS cells of selected H. pylori strains with known cytotoxin-associated gene pathogenicity island (cag-PAI) and ICE status (H. pylori strains 29CaP, 29CaCe, 62A9, 7C, 8822, and 26695) and the histopathological damage of H. pylori 29CaP and 62A9 in a mouse model. H. pylori 29CaP, which harbors a complete ICEHptfs3 but lacks cag-PAI, elicited distinctive morphology changes and higher histopathological scores compared with other H. pylori strains carrying cag-PAI and hybrid ICE with incomplete TFSS. The presence of intact segments of ICE regions might be a risk factor to develop GC that needs to be addressed in future studies.

Uric Acid Has Direct Proinflammatory Effects on Human Macrophages by Increasing Proinflammatory Mediators and Bacterial Phagocytosis Probably via URAT1.

The relationship of uric acid with macrophages has not been fully elucidated. We investigated the effect of uric acid on the proinflammatory ability of human macrophages and then examined the possible molecular mechanism involved. Primary human monocytes were differentiated into macrophages for subsequent exposure to 0, 0.23, 0.45, or 0.9 mmol/L uric acid for 12 h, in the presence or absence of 1 mmol/L probenecid. Flow cytometry was used to measure proinflammatory marker production and phagocytic activity that was quantified as a percentage of GFP-labeled Escherichia coli positive macrophages. qPCR was used to measure the macrophage expression of the urate anion transporter 1 (URAT1). As compared to control cells, the production of tumor necrosis factor-alpha (TNF-alpha), toll-like receptor 4 (TLR4), and cluster of differentiation (CD) 11c was significantly increased by uric acid. In contrast, macrophages expressing CD206, CX3C-motif chemokine receptor 1 (CX3CR1), and C-C chemokine receptor type 2 (CCR2) were significantly reduced. Uric acid progressively increased macrophage phagocytic activity and downregulated URAT1 expression. Probenecid-a non-specific blocker of URAT1-dependent uric acid transport-inhibited both proinflammatory cytokine production and phagocytic activity in macrophages that were exposed to uric acid. These results suggest that uric acid has direct proinflammatory effects on macrophages possibly via URAT1.

Antimicrobial resistance and antibiotic consumption in Mexican hospitals / Resistencia antimicrobiana y consumo de antibióticos en hospitales mexicanos

Abstract: Objective: To establish the current situation of antimicrobial resistance and antibiotic consumption in Mexican hospitals. Materials and methods: Antimicrobial susceptibility data from blood and urine isolates were collected. Defined daily dose (DDD) of antibiotic consumption/100 occupied beds (OBD) was calculated. Results: Study period: 2016 and 2017. Of 4 382 blood isolates, E. coli and K. pneumoniae were most frequently reported, with antimicrobial resistance >30% for most drugs tested, only for carbapenems and amikacin resistance were <20%. A. baumannii had antimicrobial resistance >20% to all drugs. Resistance to oxacillin in S. aureus was 20%. From 12 151 urine isolates, 90% corresponded to E. coli; resistance to ciprofloxacin, cephalosporins and trimethoprim/sulfamethoxazole was >50%, with good susceptibility to nitrofurantoin, amikacin and carbapenems. Global median antimicrobial consumption was 57.2 DDD/100 OB. Conclusions: This report shows a high antimicrobial resistance level in Gram-negative bacilli and provides an insight into the seriousness of the problem of antibiotic consumption.

Resumen: Objetivo: Establecer la situación actual de la resistencia antimicrobiana y el consumo de antibióticos en hospitales mexicanos. Material y métodos:F Se colectaron datos de susceptibilidad antimicrobiana de aislamientos de sangre y orina. Se calculó la dosis diaria definida (DDD) del consumo de antibióticos/100 estancias. Resultados: Periodo de estudio de 2016 a 2017. De 4 382 aislamientos en sangre, E. coli y K. pneumoniae fueron las más frecuentes, con resistencia >30% a la mayoría de las drogas evaluadas; sólo para carbapenémicos y amikacina la resistencia fue <20%. A. baumannii tuvo resistencia >20% a todos los fármacos. La resistencia a oxacilina en S. aureus fue de 20%. De 12 151 aislamientos en urocultivos, 90% correspondió a E. coli; la resistencia a ciprofloxacina, cefalosporinas y trimetoprima/sulfametoxazol fue >50%, con buena susceptibilidad a nitrofurantoína, amikacina y carbapenémicos. La mediana del consumo global de antibióticos en DDD/100 estancias fue de 57.2. Conclusiones: Este reporte muestra el nivel elevado de resistencia en bacilos Gram-negativos y brinda una perspectiva de la gravedad del problema del consumo de antibióticos.

Translation of gastric disease progression at gene level expression.

Helicobacter pylori is associated with the development of several lesions in the human stomach. This chronic infection produces gastritis, which can progress to intestinal metaplasia and gastric cancer. To date, there is very little information regarding gene-expression in the different phases of progression caused by chronic H. pylori infection. In this study, we performed a genome-wide gene-expression analysis in gastric biopsies of patients chronically infected with H. pylori, using the potential of high-throughput technologies that have not been fully exploited in this area. Here we illustrate the potential correlation of H. pylori infection with the gene expression changes in follicular gastritis, chronic gastritis and intestinal metaplasia. We also suggest its potential as biomarkers of each condition. An exploratory set of 21 biopsies from patients with follicular gastritis, chronic gastritis, and intestinal metaplasia were analyzed by gene-expression microarrays in order to identify the biological processes altered in each lesion. The microarray data was corroborated by real-time PCR, while 79 Formalin-Fixed Paraffin-Embeded samples were analyzed by immunohistochemistry. Follicular gastritis exhibited significant enrichment in genes associated with glutamate signaling, while chronic gastritis showed a down-regulation in metallothionein 1 and 2 and in oxidative phosphorylation-related genes, which could be associated with the chronic infecton of H. pylori. Intestinal metaplasia exhibited an over-expression of gastrointestinal stem cell markers, such as LGR5 and PROM1, as well as messenger RNA and nucleic acid metabolism-related genes. The gene-expression patterns found in this study provide new comparative information about chronic gastritis, follicular gastritis and intestinal metaplasia that may play an important role in the development of gastric cancer.

High Phenotypic and Genotypic Diversity of Enterococcus faecium from Clinical and Commensal Isolates in Third Level Hospital.

Background: The use of antimicrobials and myeloablative chemotherapy regimens has promoted multiresistant microorganisms to emerge as nosocomial pathogens, such as vancomycin-resistant Enterococcus faecium (VREfm). We described a polyclonal outbreak of bloodstream infection caused by Efm in a hemato-oncological ward in Mexico. Our aim was to describe the clonal complex (CC) of the Efm strains isolated in the outbreak in comparison with commensal and environmental isolates. Methodology: Sixty Efm clinical, environmental, and commensal strains were included. We constructed a cladogram and a phylogenetic tree using Vitek and Multilocus sequence typing data, respectively. Results: We reported 20 new sequence types (ST), among which 17/43 clinical isolates belonged to CC17. The predominant ST in the clinical strains were ST757, ST1304, ST412, and ST770. Neither environmental nor commensal isolates belonged to CC17. The phylogeny of our collection shows that the majority of the clinical isolates were different from the environmental and commensal isolates, and only a small group of clinical isolates was closely related with environmental and commensal isolates. The cladogram revealed a similar segregation to that of the phylogeny. Conclusions: We found a high diversity among clinical, environmental, and commensal strains in a group of samples in a single hospital. Highest diversity was found between commensal and environmental isolates.

Microbiome-MX 2018: microbiota and microbiome opportunities in Mexico, a megadiverse country.

A weekly conference series paired with lectures entitled "Microbiome-MX: exploring the Microbiota and Microbiome Research in Mexico" was organized to provide a multidisciplinary overview of the most recent research done in Mexico using high-throughput sequencing. Scientists and postgraduate students from several disciplines such as microbiology, bioinformatics, virology, immunology, nutrition, and medical genomics gathered to discuss state of the art in each of their respective subjects of expertise, as well as advances, applications and new opportunities on microbiota/microbiome research. In particular, high-throughput sequencing is a crucial tool to understand the challenges of a megadiverse developing country as Mexico, and moreover to know the scientific capital and capabilities available for collaboration. The conference series addressed three main topics important for Mexico: i) the complex role of microbiota in health and prevalent diseases such as obesity, diabetes, inflammatory bowel disease, tuberculosis, HIV, autoimmune diseases and gastric cancer; ii) the use of local, traditional and prehispanic products as pre/probiotics to modulate the microbiota and improve human health; and iii) the impact of the microbiota in shaping the biodiversity of economically important terrestrial and marine ecosystems. Herein, we summarize the contributions that Mexican microbiota/microbiome research is making to the global trends, describing the highlights of the conferences and lectures, rather than a review of the state-of-the-art of this research. This meeting report also presents the efforts of a multidisciplinary group of scientist to encourage collaborations and bringing this research field closer for younger generations.

Novel protein interactions with an actin homolog (MreB) of Helicobacter pylori determined by bacterial two-hybrid system.

The bacterium Helicobacter pylori infects more than 50% of the world population and causes several gastroduodenal diseases, including gastric cancer. Nevertheless, we still need to explore some protein interactions that may be involved in pathogenesis. MreB, an actin homolog, showed some special characteristics in previous studies, indicating that it could have different functions. Protein functions could be realized via protein-protein interactions. In the present study, the MreB protein from H. pylori 26695 fused with two tags 10×His and GST in tandem was overexpressed and purified from Escherchia coli. The purified recombinant protein was used to perform a pull-down assay with H. pylori 26695 cell lysate. The pulled-down proteins were identified by mass spectrometry (MALDI-TOF), in which the known important proteins related to morphogenesis were absent but several proteins related to pathogenesis process were observed. The bacterial two-hybrid system was further used to evaluate the protein interactions and showed that new interactions of MreB respectively with VacA, UreB, HydB, HylB and AddA were confirmed but the interaction MreB-MreC was not validated. These results indicated that the protein MreB in H. pylori has a distinct interactome, does not participate in cell morphogenesis via MreB-MreC but could be related to pathogenesis.

Genetic Alterations in Gastric Cancer Associated with Helicobacter pylori Infection.

Gastric cancer is a world health problem and depicts the fourth leading mortality cause from malignancy in Mexico. Causation of gastric cancer is not only due to the combined effects of environmental factors and genetic variants. Recent molecular studies have transgressed a number of genes involved in gastric carcinogenesis. The aim of this review is to understand the recent basics of gene expression in the development of the process of gastric carcinogenesis. Genetic variants, polymorphisms, desoxyribonucleic acid methylation, and genes involved in mediating inflammation have been associated with the development of gastric carcinogenesis. Recently, these genes (interleukin 10, Il-17, mucin 1, ß-catenin, CDX1, SMAD4, SERPINE1, hypoxia-inducible factor 1 subunit alpha, GSK3ß, CDH17, matrix metalloproteinase 7, RUNX3, RASSF1A, TFF1, HAI-2, and COX-2) have been studied in association with oncogenic activation or inactivation of tumor suppressor genes. All these mechanisms have been investigated to elucidate the process of gastric carcinogenesis, as well as their potential use as biomarkers and/or molecular targets to treatment of disease.

FRNA Bacteriophages as Viral Indicators of Faecal Contamination in Mexican Tropical Aquatic Systems.

A particular challenge to water safety in populous intertropical regions is the lack of reliable faecal indicators to detect microbiological contamination of water, while the numerical relationships of specific viral indicators remain largely unexplored. The aim of this study was to investigate the numerical relationships of FRNA-bacteriophage genotypes, adenovirus 41, and human adenoviruses (HADV) in Mexican surface water systems to assess sewage contamination. We studied the presence of HADV, HADV41 and FRNA bacteriophage genotypes in water samples and quantified by qPCR and RT-qPCR. Virus and water quality indicator variances, as analyzed by principal component analysis and partial least squared regression, followed along the major percentiles of water faecal enterococci. FRNA bacteriophages adequately deciphered viral and point source water contamination. The strongest correlation for HADV was with FRNA bacteriophage type II, in water samples higher than the 50th percentiles of faecal enterococci, thus indicating urban pollution. FRNA bacteriophage genotypes I and III virus indicator performances were assisted by their associations with electrical conductivity and faecal enterococci. In combination, our methods are useful for inferring water quality degradation caused by sewage contamination. The methods used have potential for determining source contamination in water and, specifically, the presence of enteric viruses where clean and contaminated water have mixed.

A polyclonal outbreak of bloodstream infections by Enterococcus faecium in patients with hematologic malignancies.

BACKGROUND: Enterococcus faecium causes bloodstream infection (BSI) in patients with hematologic malignancies (HMs). We studied the clinical features and outcomes of patients with HM with vancomycin-sensitive E faecium (VSE) and vancomycin-resistant E faecium (VRE) BSI and determined the genetic relatedness of isolates and circumstances associated with the upsurge of E faecium BSI. METHODS: Case-control study of patients with HM and E faecium-positive blood culture from January 2008-December 2012; cases were patients with VRE and controls were VSE isolates. The strains were tested for Van genes by polymerase chain reaction amplification and we performed pulsed-field gel electrophoresis to determine genetic relatedness. RESULTS: Fifty-eight episodes of E faecium BSI occurred: 35 sensitive and 23 resistant to vancomycin. Mortality was 46% and 57%, attributable 17% and 40%, respectively. Early stage HM was associated with VSE (P = .044), whereas an episode of BSI within the 3 months before the event (P = .039), prophylactic antibiotics (P = .013), and vancomycin therapy during the previous 3 months (P = .001) was associated with VRE. The VanA gene was identified in 97% of isolates studied. E faecium isolates were not clonal. CONCLUSIONS: E faecium BSI was associated with high mortality. This outbreak of VRE was not clonal; it was associated with antibiotic-use pressure and highly myelosuppressive chemotherapy.

TLR4 and DC-SIGN receptors recognized Mycobacterium scrofulaceum promoting semi-activated phenotype on bone marrow dendritic cells.

Nontuberculous mycobacteria (NTM) are recognized as emerging pathogens and their immune regulatory mechanisms are not well described yet. From them, Mycobacterium avium is known to be a weak activator of dendritic cells (DCs) that impairs the response induced by BCG vaccine. However, whether other NTM such as Mycobacterium scrofulaceum may modulate the activation of DCs, has not been extensively studied. Here, we exposed bone marrow-derived DCs (BMDCs) to M. scrofulaceum and we analyzed the effect on the activation of DCs. We found that M. scrofulaceum has a comparable ability to induce a semi-mature DC phenotype, which was produced by its interaction with DC-SIGN and TLR4 receptors in a synergic effect. BMDCs exposed to M. scrofulaceum showed high expression of PD-L2 and production of IL-10, as well as low levels of co-stimulatory molecules and pro-inflammatory cytokines. In addition to immunophenotype induced on DCs, changes in morphology, re-organization of cytoskeleton and decreased migratory capacity are consistent with a semi-mature phenotype. However, unlike other pathogenic mycobacteria, the DC-semi-mature phenotype induced by M. scrofulaceum was reversed after re-exposure to BCG, suggesting that modulation mechanisms of DC-activation used by M. scrofulaceum are different to other known pathogenic mycobacteria. This is the first report about the immunophenotypic characterization of DC stimulated by M. scrofulaceum.

Complete Genome Sequence of Helicobacter pylori Strain 29CaP Isolated from a Mexican Patient with Gastric Cancer.

Helicobacter pylori infection is a risk factor for the development of gastric cancer and other gastroduodenal diseases. We report here the complete genome sequence of H. pylori strain 29CaP, isolated from a Mexican patient with gastric cancer. The genomic data analysis revealed a cag-negative H. pylori strain that contains a prophage sequence.

Catecholamine norepinephrine diminishes lung epithelial cell adhesion of Streptococcus pneumoniae by binding iron.

Systemic release of norepinephrine (NE) is a component of the acute host response to infection, and studies in the field of microbial endocrinology indicate generally that NE increases the bacterial growth rate and promotes invasive disease. However, NE attenuates experimental invasive pneumococcal disease. We determined that NE promoted pneumococcal growth but paradoxically decreased pneumococcal adhesion to host cells. This effect was independent of the classical adhesin CbpA. Microarray analysis indicated that the effect of NE involved two two-component regulatory systems that both regulate expression of the Piu iron uptake ABC transport operon. We propose that NE, a known siderophore, enhances iron availability to the bacteria, resulting in greater bacterial replication and decreased expression of Piu operon products. Downregulation of the operon includes decreased expression of the Piu-associated adhesin PiuD. Our results suggested that the iron-dependent inhibitory effect of NE on pneumococcal adherence is a mechanism underlying the amelioration of pneumococcal disease by NE.

Nitric oxide not apoptosis mediates differential killing of Mycobacterium bovis in bovine macrophages.

To identify the resistance phenotype against Mycobacterium bovis in cattle, we used a bactericidal assay that has been considered a marker of this trait. Three of 24 cows (12.5%) were phenotyped as resistant and 21 as susceptible. Resistance of bovine macrophages (MΦ) to BCG challenge was evaluated for its association with SLC11A1 GT microsatellite polymorphisms within 3'UTR region. Twenty-three cows (95.8%) had a GT13 genotype, reported as resistant, consequently the SLC11A1 polymorphism was not in agreement with our bactericidal assay results. MΦ of cows with resistant or susceptible phenotype were challenged in vitro with virulent M. bovis field strain or BCG, and nitric oxide production, bacterial killing and apoptosis induction were measured in resting and LPS-primed states. M. bovis field strain induced more apoptosis than BCG, although the difference was not significant. Resistant MΦ controlled better the replication of M. bovis (P<0.01), produced more nitric oxide (P<0.05) and were slightly more prone to undergo apoptosis than susceptible cells. LPS pretreatment of MΦ enhanced all the functional parameters analyzed. Inhibition of nitric oxide production with n (G)-monomethyl-L-arginine monoacetate enhanced replication of M. bovis but did not modify apoptosis rates in both resistant and susceptible MΦ. We conclude that nitric oxide production not apoptosis is a major determinant of macrophage resistance to M. bovis infection in cattle and that the influence of SLC11A1 gene 3'UTR polymorphism is not associated with this event.