Helicobacter pylori infection: Host immune response, implications on gene expression and microRNAs

Helicobacter pylori (H. pylori) infection is the most common bacterial infection worldwide. Persistent infection of the gastric mucosa leads to inflammatory processes and may remain silent for decades or progress causing more severe diseases, such as gastric adenocarcinoma. The clinical consequences of H. pylori infection are determined by multiple factors, including host genetic predisposition, gene regulation, environmental factors and heterogeneity of H. pylori virulence factors. After decades of studies of this successful relationship between pathogen and human host, various mechanisms have been elucidated. In this review, we have made an introduction on H. pylori infection and its virulence factors, and focused mainly on modulation of host immune response triggered by bacteria, changes in the pattern of gene expression in H. pylori-infected gastric mucosa, with activation of gene transcription involved in defense mechanisms, inflammatory and immunological response, cell proliferation and apoptosis. We also highlighted the role of bacteria eradication on gene expression levels. In addition, we addressed the recent involvement of different microRNAs in precancerous lesions, gastric cancer, and inflammatory processes induced by bacteria. New discoveries in this field may allow a better understanding of the role of major factors involved in the pathogenic mechanisms of H. pylori. (C) 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

Non-specific immune parameters and physiological response of Nile tilapia fed beta-glucan and vitamin C for different periods and submitted to stress and bacterial challenge

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Procalcitonin (PCT) and C-reactive Protein (CRP) as severe systemic infection markers in febrile neutropenic adults

Abstract Background Procalcitonin (PCT) is an inflammatory marker that has been used as indicator of severe bacterial infection. We evaluated the concentrations of PCT as a marker for systemic infection compared to C-reactive protein (CRP) in patients neutropenic febrile. Methods 52 adult patients were enrolled in the study. Blood sample was collected in order to determine the serum concentrations of PCT, CRP and other hematological parameters at the onset of fever. The patients were divided into 2 groups, one with severe infection (n = 26) and the other in which the patients did not present such an infection (n = 26). Then PCT and CRP concentrations at the fever onset were compared between groups using non parametric statistical tests, ROC curve, sensitivity, specificity, likelihood ratio, and Spearman's correlation coefficient. Results The mean of PCT was significantly higher in the group with severe infection (6.7 ng/mL versus 0.6 ng/mL – p = 0.0075) comparing with CRP. Serum concentrations of 0.245 ng/mL of PCT displayed 100% de sensitivity and 69.2% specificity. PCT concentrations of 2,145 ng/mL presented a likelihood ratio of 13, which was not observed for any concentration of CRP. Conclusion PCT seems to be an useful marker for the diagnosis of systemic infection in febrile neutropenic patients, probably better than CRP.

The formyl peptide receptor like-1 and scavenger receptor MARCO are involved in glial cell activation in bacterial meningitis

Recent studies have suggested that the scavenger receptor MARCO (macrophage receptor with collagenous structure) mediates activation of the immune response in bacterial infection of the central nervous system (CNS). The chemotactic G-protein-coupled receptor (GPCR) formyl-peptide-receptor like-1 (FPRL1) plays an essential role in the inflammatory responses of host defence mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the antimicrobial peptide cathelicidin CRAMP/LL-37 is up-regulated in bacterial meningitis, but the mechanisms underlying CRAMP expression are far from clear.

Timing of progression from Chlamydia trachomatis infection to pelvic inflammatory disease: a mathematical modelling study

Background Pelvic inflammatory disease (PID) results from the ascending spread of microorganisms from the vagina and endocervix to the upper genital tract. PID can lead to infertility, ectopic pregnancy and chronic pelvic pain. The timing of development of PID after the sexually transmitted bacterial infection Chlamydia trachomatis (chlamydia) might affect the impact of screening interventions, but is currently unknown. This study investigates three hypothetical processes for the timing of progression: at the start, at the end, or throughout the duration of chlamydia infection. Methods We develop a compartmental model that describes the trial structure of a published randomised controlled trial (RCT) and allows each of the three processes to be examined using the same model structure. The RCT estimated the effect of a single chlamydia screening test on the cumulative incidence of PID up to one year later. The fraction of chlamydia infected women who progress to PID is obtained for each hypothetical process by the maximum likelihood method using the results of the RCT. Results The predicted cumulative incidence of PID cases from all causes after one year depends on the fraction of chlamydia infected women that progresses to PID and on the type of progression. Progression at a constant rate from a chlamydia infection to PID or at the end of the infection was compatible with the findings of the RCT. The corresponding estimated fraction of chlamydia infected women that develops PID is 10% (95% confidence interval 7-13%) in both processes. Conclusions The findings of this study suggest that clinical PID can occur throughout the course of a chlamydia infection, which will leave a window of opportunity for screening to prevent PID.

Clinical characteristics and outcomes in children hospitalised with pandemic influenza A/H1N1/09 virus infection – a nationwide survey by the Pediatric Infectious Diseases Group of Switzerland

OBJECTIVE To describe all patients admitted to children's hospitals in Switzerland with a diagnosis of influenza A/H1N1/09 virus infection during the 2009 influenza pandemic, and to analyse their characteristics, predictors of complications, and outcome. METHODS All patients ≤18-years-old hospitalised in eleven children's hospitals in Switzerland between June 2009 and January 2010 with a positive influenza A/H1N1/09 reverse transcriptase polymerase chain reaction (RT-PCR) from a nasopharyngeal specimen were included. RESULTS There were 326 PCR-confirmed patients of whom 189 (58%) were younger than 5 years of age, and 126 (38.7%) had one or more pre-existing medical condition. Fever (median 39.1 °C) was the most common sign (85.6% of all patients), while feeding problems (p = 0.003) and febrile seizures (p = 0.016) were significantly more frequent in children under 5 years. In 142 (43.6%) patients there was clinical suspicion of a concomitant bacterial infection, which was confirmed in 36 patients (11%). However, severe bacterial infection was observed in 4% of patients. One third (n = 108, 33.1%) of the patients were treated with oseltamivir, 64 (59.3%, or 20% overall) within 48 hours of onset of symptoms. Almost half of the patients (45.1%) received antibiotics for a median of 7 days. Twenty patients (6.1%) required intensive care, mostly for complicated pneumonia (50%) without an underlying medical condition. The median duration of hospitalisation was 2 days (range 0-39) for 304 patients. Two children (<15 months of age with underlying disease) died. CONCLUSIONS Although pandemic influenza A/H1N1/09 virus infection in children is mostly mild, it can be severe, regardless of past history or underlying disease.

Helicobacter pylori infection and the effect on growth in a cohort of children in the US/Mexico border

Helicobacter pylori (H. pylori) is an S-shaped or curved gram-negative bacterium that is mostly found in the human stomach. H. pylori causes gastritis in adults and children, which can lead to gastric ulcers or risk of cancer. Transmission of this bacterial infection remains to be unknown but is mostly acquired during childhood. Little is known about the effect H. pylori has on growth in children. Although some studies have reported that H. pylori is associated with subnormal growth, the association of H. pylori with growth retardation and malnutrition is poorly described. Data from this study comes from The Pasitos Cohort Study which draws its population from three border communities which include Socorro and San Elizario in Texas, as well as Ciudad Juarez, Chihuahua, Mexico. Birth documentation was obtained for 803 infants and 472 entered follow-up. This cohort study allowed us to assess the growth of children from 6 months to the seventh anniversary, and describe the prevalence of underweight, short stature and overweight in the study population. We also tested the hypothesis that children in the Pasitos Cohort Study who were ever infected with H. pylori show an increased risk of growth retardation or malnutrition at 66 months of age. Using the 2000 CDC Growth Reference, we found that the mean BMI of the study population increased as children grew older, while the mean of their height for age decreased slightly. The proportion of children who were classified as of short stature was under 5%, while those considered underweight were less than 10% at selected six-months of age intervals. Using the subset of children who were 66 months of age we found that the risk of underweight was higher among those who ever tested positive for H. pylori infection using the urea breath test; however, due to small numbers of children with 'wasting' this difference was not statistically significant. Moreover, since the six cases of under weight occurred among children of low socio-economic status we could not rule out potential confounding. The risk of developing short stature was not different among those ever infected and those who never tested positive for H. pylori infection. ^

Endometrial response toward bovine herpesvirus 4 infection

Metriti ed endometriti sono le patologie maggiormente responsabili delle perdite economiche negli allevamenti bovini da latte, specialmente nel periodo successivo al parto. Mentre le metriti coinvolgono e si sviluppano in tutto l’utero e sono caratterizzate dalla presenza di sintomi sistemici, le endometriti consistono in una infiammazione che riguarda il solo endometrio, con la presenza di perdite purulente, distruzione della superficie epiteliale, congestione vascolare, edema stromale ed accumulo di linfociti e plasmacellule. Queste patologie, inoltre, possono causare, disfunzione ovarica, con conseguente infertilità e riduzione sia dell’efficienza riproduttiva della vacca sia della produzione stessa di latte. Nonostante queste malattie siano, nella maggior parte dei casi, correlate all’instaurarsi di infezioni batteriche, che possono subentrare nell’utero direttamente durante il parto, il ruolo di alcuni virus nello sviluppo di queste patologie è stato recentemente approfondito e la correlazione tra l’ Herpesvirus Bovino 4 e l’insorgere di metriti ed endometriti è stata dimostrata. L’ Herpesvirus Bovino 4 (BoHV-4) è un gamma-herpesvirus ed il suo genoma è costituito da una molecola lineare di DNA a doppio filamento con una struttura genomica di tipo B, caratterizzata dalla presenza di un’unica lunga sequenza centrale (LUR) fiancheggiata da multiple sequenze poli-ripetute (prDNA). BoHV-4 è stato isolato sia da animali sani sia da animali con differenti patologie, tra cui malattie oculari e respiratorie, ma soprattutto da casi di metriti, endometriti, vaginiti o aborti. Generalmente, il ruolo svolto dal virus in questo tipo di patologie è associato alla compresenza di altri tipi di patogeni, che possono essere virus, come nel caso del Virus Della Diarrea Virale Bovina (BVDV), o più frequentemente batteri. Usualmente, l’iniziale difesa dell’endometrio bovino nei confronti dei microbi si fonda sul sistema immunitario innato e l’attivazione di specifici recettori cellulari determina la sintesi e la produzione di citochine e chemochine pro infiammatorie, che possono essere in grado di modulare la replicazione di BoHV-4. Il genoma di BoHV-4 possiede due principali trascritti per i geni Immediate Early (IE), trai quali ORF50/IE2 è il più importante ed il suo prodotto, Rta/ORF50, è fortemente conservato tra tutti gli Herpesvirus. Esso è responsabile della diretta trans-attivazione di numerosi geni virali e cellulari e può essere modulato da differenti stimoli extracellulari. Precedentemente è stato dimostrato come il TNF-, prodotto dalle cellule stromali e dai macrofagi all’interno dell’endometrio, in conseguenza ad infezione batterica, sia in grado di aumentare la replicazione di BoHV-4 attraverso l’attivazione del pathway di NFkB e direttamente agendo sul promotore di IE2. Per queste ragioni, è risultato di forte interesse investigare quali potessero essere, invece, i fattori limitanti la replicazione di BoHV-4. In questo lavoro è stata studiata la relazione tra cellule endometriali stromali bovine infettate con l’Herpesvirus Bovino 4 e l’interferon gamma (IFN-) ed è stata dimostrata la capacità di questa molecola di restringere la replicazione di BoHV-4 in maniera IDO1 indipendente ed IE2 dipendente. Inoltre, la presenza di alcuni elementi in grado di interagire con l’ IFN-γ, all’interno del promotore di IE2 di BoHV-4, ha confermato questa ipotesi. Basandoci su questi dati, abbiamo potuto supporre l’esistenza di uno stretto vincolo tra l’attivazione dell’asse dell’interferon gamma e la ridotta replicazione di BoHV-4, andando a porre le basi per una nuova efficiente cura e prevenzione per le patologie uterine. Poiché il meccanismo corretto attraverso il quale BoHV-4 infetta l’endometrio bovino non è ancora ben compreso, è stato interessante approfondire in maniera più accurata l’interazione presente tra il virus ed il substrato endometriale, analizzando le differenze esistenti tra cellule infettate e non, in termini di espressione genica. Basandoci su dati preliminari ottenuti attraverso analisi con RNA sequencing (RNAseq), abbiamo visto come numerosi geni risultino over-espressi in seguito ad infezione con BoHV-4 e come, tra questi, la Metalloproteasi 1 sia uno dei più interessanti, a causa delle sue possibili implicazioni nello sviluppo delle patologie dell’endometrio uterino bovino. Successive analisi, effettuate tramite westernblotting e real time PCR, sono state in grado di confermare tale dato, sottolineando l’efficacia di un nuovo approccio sperimentale, basato sul RNAseq, per lo studio dell’insorgenza delle patologie.

Influence of iron on bacterial infections in leukaemia

The influence of iron metabolism, both on the invading bacterial pathogen and in the host is widespread and often appears to be crucial in determining the outcome of an infection. This study involved the investigation of leukaemia, a clinical disease where abnormal availability of iron may play a part in predisposing patients to bacterial infection. The iron status throughout a Gram-negative septicaemia and in 20 random, newly diagnosed leukaemic patients was assessed. The results revealed that the majority of the patients exhibited high serum iron levels and serum transferrin saturation often at 100%, with an inability to reduce the latter to within normal values during an infection episode. The antibody response to P.aeruginosa, E.coli and K.pneumoniae outer membrane protein (OMP) antigens were investigated by immunoblotting with sequential serum samples during infection in the leukaemic host. Antibodies to all the major OMPs, were observed, although recognition of iron-regulated membrane proteins (IRMPs) was in many cases weak. Results from the enzyme-linked immunosorbent assay indicated that in all patients antibody titre in response to infection was poor. Sub-MICs of mitomycin C significantly altered the surface characteristics of P.aeruginosa. The silver-stained SDS-PAGE gels of proteinase K digested whole cell lysates of strains PAO1, 6750, M7 and PAJ indicated that core LPS was affected in the presence of mitomycin C. In contrast, the rough strain AK1012 showed no observable differences. Results obtained using quantitative gas-liquid chromatographic analysis showed the amount of LPS fatty acids to be unaffected, however, the KDO and carbohydrate content in strains PAO1, 6750 and M7 under Fe+ and Fe- growth conditions were decreased by up to 4-fold in the presence of mitomycin C, indicating perturbed expression of LPS. The cell surface became significantly more hydrophobic in the P.aeruginosa strains, except AK1012 which was comparatively unaffected. The induction of protein G (OprG) in P.aeruginosa was found to be a sensitive indicator of media iron. The data indicated that expression of OprG can be modulated by growth rate/phase, availability of iron and by the presence of ciprofloxacin in the growth medium.

An overview on Human Leukocyte Antigen (HLA) region gene expression during Pseudomonas aeruginosa infection

The human leukocyte antigen (HLA) complex is an extensively studied cluster of genes with immunoregulatory function. Pseudomonas aeruginosa is capable of infecting individuals with weakened immune systems, and is associated with a high mortality rate. Previous genetic studies of the HLA region have found correlations between bacterial infection and its effect on regulating HLA gene expressions to establish their infection. This project analyzes the expression of classical HLA loci (A, B, C, DR, DQ, DP) in human B cells and macrophage cells during the infection of virulent strains of P. aeruginosa. Cells were cultured and infected with different virulent live, and heat-killed strains of P. aeruginosa for different time periods. The mRNA was extracted and converted into cDNA followed by real-time quantitative PCR and data analysis. The Western Blot technique was used to identify the targeted protein’s cell surface expression. Infection with P. aeruginosa was found to inhibit the expression of HLA proteins. The PA14 strain inhibited expression of all targeted genes in all experiments. Infections with PA01 and PA103 showed different patterns depending on the incubation time and the targeted gene. These differences suggest that the three strains use various mechanisms to inhibit HLA protein expression.

A bacterial acetyltransferase targets the protein kinase ZIP1, a positive regulator of plant immunity

Pseudomonas syringae is a model bacterial pathogen that penetrates the leaf to reach the plant apoplast, where it replicates causing disease. In order to do that, the pathogen must interfere and suppress a two-tiered plant defense response: PTI (PAMP-Triggered Immunity, or basal resistance) and ETI (Effector-Triggered Immunity). P. syringae uses a type III secretion system to directly deliver effector proteins inside the plant cell cytosol, many of which are known to suppress PTI, some of which are known to trigger ETI, and a handful of which are known to suppress ETI. Bacterial infection can also trigger a systemic plant defense response that protects the plant against additional pathogen attacks known as SAR (Systemic Acquired Resistance). We are particularly interested in the molecular and cellular mechanisms involved in effector-mediated defense evasion by P. syringae, in particular those involved in the suppression of ETI and SAR, and/or mediation of hormone signaling. Here we present data describing effector-mediated interference with plant immunity, by means of acetylation of a key positive regulator of local and systemic responses. Our work identifies a novel plant target for effector function, and characterizes its function. This work illustrates how analyzing the means by which a given effector interferes with its target can provide novel information regarding eukaryotic molecular mechanisms.

The microbiological signature of human cutaneous leishmaniasis lesions exhibits restricted bacterial diversity compared to healthy skin

Localised cutaneous leishmaniasis (LCL) is the most common form of cutaneous leishmaniasis characterised by single or multiple painless chronic ulcers, which commonly presents with secondary bacterial infection. Previous culture- based studies have found staphylococci, streptococci, and opportunistic pathogenic bacteria in LCL lesions, but there have been no comparisons to normal skin. In addition, this approach has strong bias for determining bacterial composition. The present study tested the hypothesis that bacterial communities in LCL lesions differ from those found on healthy skin (HS). Using a high throughput amplicon sequencing approach, which allows for better populational evaluation due to greater depth coverage and the Quantitative Insights Into Microbial Ecology pipeline, we compared the microbiological signature of LCL lesions with that of contralateral HS from the same individuals. Streptococcus , Staphylococcus , Fusobacterium and other strict or facultative anaerobic bacteria composed the LCL microbiome. Aerobic and facultative anaerobic bacteria found in HS, including environmental bacteria, were significantly decreased in LCL lesions (p < 0.01). This paper presents the first comprehensive microbiome identification from LCL lesions with next generation sequence methodology and shows a marked reduction of bacterial diversity in the lesions.

Comparative Genomics of Field Isolates of Mycobacterium bovis and M. caprae Provides Evidence for Possible Correlates with Bacterial Viability and Virulence

Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly affect humans and animals worldwide. The life cycle of mycobacteria is complex and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Recently, comparative genomics analyses have provided new insights into the evolution and adaptation of the MTBC to survive inside the host. However, most of this information has been obtained using M. tuberculosis but not other members of the MTBC such as M. bovis and M. caprae. In this study, the genome of three M. bovis (MB1, MB3, MB4) and one M. caprae (MB2) field isolates with different lesion score, prevalence and host distribution phenotypes were sequenced. Genome sequence information was used for whole-genome and protein-targeted comparative genomics analysis with the aim of finding correlates with phenotypic variation with potential implications for tuberculosis (TB) disease risk assessment and control. At the whole-genome level the results of the first comparative genomics study of field isolates of M. bovis including M. caprae showed that as previously reported for M. tuberculosis, sequential chromosomal nucleotide substitutions were the main driver of the M. bovis genome evolution. The phylogenetic analysis provided a strong support for the M. bovis/M. caprae clade, but supported M. caprae as a separate species. The comparison of the MB1 and MB4 isolates revealed differences in genome sequence, including gene families that are important for bacterial infection and transmission, thus highlighting differences with functional implications between isolates otherwise classified with the same spoligotype. Strategic protein-targeted analysis using the ESX or type VII secretion system, proteins linking stress response with lipid metabolism, host T cell epitopes of mycobacteria, antigens and peptidoglycan assembly protein identified new genetic markers and candidate vaccine antigens that warrant further study to develop tools to evaluate risks for TB disease caused by M. bovis/M.caprae and for TB control in humans and animals.

Phagocytosis of bacteria by olfactory ensheathing cells and Schwann cells

Opportunistic bacterial infections of the nasal cavity could potentially lead to infection of the brain if the olfactory or trigeminal nerves are colonised. The olfactory nerve may be a more susceptible route because primary olfactory neurons are in direct contact with the external environment. Peripheral glia are known to be able to phagocytose some species of bacteria and may therefore provide a defence mechanism against bacterial infection. As the nasal cavity is frequently exposed to bacterial infections, we hypothesised that the olfactory and trigeminal nerves within the nasal cavity could be subjected to bacterial colonisation and that the olfactory ensheathing cells and Schwann cells may be involved in responding to the bacterial invasion. We have examined the ability of mouse OECs and Schwann cells from the trigeminal nerve and dorsal root ganglia to phagocytose Escherichia coli and Burkholderia thailandensis in vitro. We found that all three sources of glia were equally able to phagocytose E. coli with 75-85% of glia having phagocytosed bacteria within 24h. We also show that human OECs phagocytosed E. coli. In contrast, the mouse OECs and Schwann cells had little capacity to phagocytose B. thailandensis. Thus subtypes of peripheral glia have similar capacities for phagocytosis of bacteria but show selective capacity for the two different species of bacteria that were examined. These results have implications for the understanding of the mechanisms of bacterial infections as well as for the use of glia for neural repair therapies.