María Mercedes Bravo

E6 molecular variants of human papillomavirus (HPV) type 16: an updated and unified criterion for clustering and nomenclature.

Reports on taxonomic identification of E6/HPV 16 variants, dont have a worldwide, updated and unified criterion for clustering and nomenclature. Our aim was to update the existing criterion and propose a new one for clustering and nomenclature for E6/HPV 16 molecular variants based on the descriptive and comparative analyses of nucleotide sequences. A systematic search of the publications between 1991 and 2010 was carried out in PUBMED and manually. 240 E6/HPV 16 variants were identified. 157 were classified as European (E), 24 as Asian (As), 14 as Asian American (AA), 11 as North American 1 (NA 1), 19 as African 1 (Af 1) and 15 as African 2 (Af 2). Three classes were determined for the E, 3 each for the As, Af 2 and AA branches, 4 classes for the NA 1 and 6 for the Af 1 branch. This study reports our results and proposes an updated criterion for clustering and nomenclature that will be useful for E6 variant identification.

Altered HLA Class I and HLA-G Expression Is Associated with IL-10 Expression in Patients with Cervical Cancer

Although high-risk human papillomaviruses (HPVs) are an important risk factor in the etiopathogenesis of cervical cancer, increasing evidence suggests that the ability to avoid immune surveillance seems to be linked to the transforming potential of HPV and a rapid progression to cancer. In other cancer models, IL-10 contributes to impair anti-tumor immune response either by downregulating human leukocyte antigen Class I (HLA-I) expression or by increasing HLA-G expression. To comprehend how these alterations could contribute to evasion of immune surveillance in cervical cancer, we analyzed HLA-I, HLA-G and IL-10 expressions by immunohistochemistry in 63 biopsies from patients with cervical intraepithelial neoplasia III (CIN-III) and cervical cancer. Immunohistochemistry showed absent or weak HLA-I expression in 50/59 cases. In these cases, a high percentage had loss of heterozygosis. IL-10 and HLA-G expression were observed in 46.6 and 27.6% of cases, respectively. Concurrent upregulation of IL-10 was found in 87.5% of HLA-G positive cases (p = 0.000). Similarly, a significant association between IL-10 expression and HLA-I downregulation was found (p = 0.028). Finally, we observed higher HLA-G expression in patients with HLA-I downregulation than in those with normal HLA-I expression (p = 0.004). Our results suggest that, in cervical cancer, the IL-10 expression may induce an immunosuppressive environment by upregulating HLA-G expression and downregulating HLA class I expression.

Los genotipos de Helicobacter pylori en gastritis no atrófica difieren de los encontrados en úlcera péptica, lesiones premalignas y cáncer gástrico en Colombia

Background: Helicobacter pylori is recognized as an etiologic agent of several gastric diseases. Bacterial genotypes have been related to clinical outcome in several populations. Aim: To compare cagA, vacA and iceA genotypes of Colombian isolates from patients with several gastrointestinal diseases, including gastric cancer. Material and methods: We used polymerase chain reactions to amplify vacA, cagA and iceA genes of 137 H pylori isolates coming from 26 patients with gastric cancer (GC), 34 with peptic ulcer (PU), 19 with intestinal metaplasia (IM), 23 with atrophic gastritis (AG) and 35 with non atrophic gastritis (NAG). Results: vacA s1-m1, cagA+, iceA+ were the most frequently found genotypes. vacA s1 and m1 subtypes were found in 92 (67%) and 82 (60%) cases respectively. Sixty three percent were cagA+ and 85% were iceA+. There was a lower prevalence of s1 allele in cases of NAG (43%), compared with GC, PU and IM (81%, 77% and 81% prevalence, respectively, p <0.01). Isolates from NAG also showed a low frequency of vacA m1 subtype (40%) compared with GC or IM (81% and 84% respectively, p <0.01). The prevalence of cagA+ strains was significantly higher in GC patients (80%) than in NAG patients (51.4%, p <0.01). No differences in the frequency of vacA s1a, s1b and iceA subtypes, were observed. Conclusions: A lower frequency of cytotoxic H pylori genotypes such as cagA and vacA s1m1 and a higher frequency of non cytotoxic genotypes, was observed in patients with NAG, when compared to patients with GC or PU. These results suggest that even in Colombia, vacA and cagA could be used as markers of increased virulence (Rev Med Chile 2002; 130: 143-51)

Increase of human papillomavirus-16 E7-specific T helper type 1 response in peripheral blood of cervical cancer patients after radiotherapy.

It has been suggested that tumour cell lysis by gamma‐radiation induces a tumoral antigen release eliciting an immune response. It is not clear how a specific immune response in cervical cancer patients is developed after radiotherapy. This study is an attempt to investigate the role of the human papillomavirus type 16 (HPV‐16) E7‐specific T helper response before and after radiotherapy. Lymphocytes were isolated from 32 cervical cancer patients before and after radiotherapy and from 16 healthy women. They were stimulated for 12u2003hr with autologous HPV‐16 E7‐pulsed monocyte‐derived dendritic cells or directly with HPV‐16 E7 synthetic peptides: E751–70, E765–84 and E779–98. The cells were stained for CD4, CD69, intracellular interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) cytokines and analysed by flow cytometry. A specific CD4+u2003CD69+u2003IFN‐γ+ immune response against HPV‐16 E779–98 peptide was observed in 10 of 14 patients (71·4%) after treatment, compared with 4 of 14 (28·5%) before radiotherapy (Pu2003=u20030·039); however, this response was not associated with a successful clinical response. Before treatment, 5 of 31 patients showed a HPV‐16 E779–98‐specific T helper type 2 (Th2) response. Interestingly, this response was significantly associated with a decrease in disease‐free survival (Pu2003=u20030·027). These results suggest that a Th2‐type cellular response could be useful as a predictor of recurrence and poor prognosis. An increase of the HPV‐specific immune response was observed after radiotherapy; however, it is not enough to control completely the disease after treatment. Our results support that the E7‐specific T‐cell IFN‐γ response in cervical cancer patients, rather than reflecting the host’s capability of controlling tumour growth, might be an indicator for disease severity.

Whole Genome Sequence and Phylogenetic Analysis Show Helicobacter pylori Strains from Latin America Have Followed a Unique Evolution Pathway

Helicobacter pylori (HP) genetics may determine its clinical outcomes. Despite high prevalence of HP infection in Latin America (LA), there have been no phylogenetic studies in the region. We aimed to understand the structure of HP populations in LA mestizo individuals, where gastric cancer incidence remains high. The genome of 107 HP strains from Mexico, Nicaragua and Colombia were analyzed with 59 publicly available worldwide genomes. To study bacterial relationship on whole genome level we propose a virtual hybridization technique using thousands of high-entropy 13 bp DNA probes to generate fingerprints. Phylogenetic virtual genome fingerprint (VGF) was compared with Multi Locus Sequence Analysis (MLST) and with phylogenetic analyses of cagPAI virulence island sequences. With MLST some Nicaraguan and Mexican strains clustered close to Africa isolates, whereas European isolates were spread without clustering and intermingled with LA isolates. VGF analysis resulted in increased resolution of populations, separating European from LA strains. Furthermore, clusters with exclusively Colombian, Mexican, or Nicaraguan strains were observed, where the Colombian cluster separated from Europe, Asia, and Africa, while Nicaraguan and Mexican clades grouped close to Africa. In addition, a mixed large LA cluster including Mexican, Colombian, Nicaraguan, Peruvian, and Salvadorian strains was observed; all LA clusters separated from the Amerind clade. With cagPAI sequence analyses LA clades clearly separated from Europe, Asia and Amerind, and Colombian strains formed a single cluster. A NeighborNet analyses suggested frequent and recent recombination events particularly among LA strains. Results suggests that in the new world, H. pylori has evolved to fit mestizo LA populations, already 500 years after the Spanish colonization. This co-adaption may account for regional variability in gastric cancer risk.

Polimorfismos genéticos de interleucinas IL-1B-511, IL-1RN, IL-10, factor de necrosis tumoral α-308 e infección por Helicobacter pylori CagA positivo en cáncer gástrico y úlcera duodenal en diferentes poblaciones en Colombia

Resumen Objetivo Determinar la asociacion entre los polimorfismos IL-1B-511, IL-1RN, TNF-α-308, IL-10-819 e IL-101082 y la infeccion por Helicobacter pylori CagA positivo en un grupo de pacientes con cancer gastrico y ulcera duodenal en diferentes poblaciones en Colombia. Metodos Estudio de casos y controles con 341 pacientes: con gastritis no atrofica, 194; con cancer gastrico, 58; ulcera duodenal con lesiones preneoplasicas, 54; y con ulcera duodenal, 35. La genotipificacion de los polimorfismos se hizo por discriminacion alelica usando PCR en tiempo real, y la del IL-1RN, por PCR convencional y electroforesis en agarosa. La infeccion por Helicobacter pylori CagA se determino mediante ELISA. Se utilizo la regresion logistica en el analisis estadistico. Resultados Ser portador del genotipo IL-1B-511TT (ORxa0=xa04,69; IC 95% 1,22-18,09) y tener una infeccion por Helicobacter pylori CagA positivo (ORxa0=xa04,43; IC 95% 1,72–11,4) se asociaron a cancer gastrico. Tener una infeccion por Helicobacter pylori CagA positivo (ORxa0=xa04,39; IC95% 1,82–10,59) se asocio a la presencia de ulcera duodenal con lesiones preneoplasicas, y ser portador del genotipo IL-1B-511CT se asocio a ulcera duodenal (ORxa0=xa00,30; IC 95% 0,10–0,91). Conclusion Los resultados sugieren que la respuesta pro-inflamatoria y la genetica virulenta de la bacteria son factores relacionados con los diferentes desenlaces ocasionados por la infeccion por Helicobacter pylori en la poblacion estudiada; asi, el polimorfismo IL-1B-511 es un factor relacionado con cancer gastrico y ulcera duodenal, y la infeccion por Helicobacter pylori CagA positivo es un factor asociado a cancer gastrico y ulcera duodenal con lesiones preneoplasicas.

Phylogenomics of Colombian Helicobacter pylori isolates

BackgroundDuring the Spanish colonisation of South America, African slaves and Europeans arrived in the continent with their corresponding load of pathogens, including Helicobacter pylori. Colombian strains have been clustered with the hpEurope population and with the hspWestAfrica subpopulation in multilocus sequence typing (MLST) studies. However, ancestry studies have revealed the presence of population components specific to H. pylori in Colombia. The aim of this study was to perform a thorough phylogenomic analysis to describe the evolution of the Colombian urban H. pylori isolates.ResultsA total of 115 genomes of H. pylori were sequenced with Illumina technology from H. pylori isolates obtained in Colombia in a region of high risk for gastric cancer. The genomes were assembled, annotated and underwent phylogenomic analysis with 36 reference strains. Additionally, population differentiation analyses were performed for two bacterial genes. The phylogenetic tree revealed clustering of the Colombian strains with hspWestAfrica and hpEurope, along with three clades formed exclusively by Colombian strains, suggesting the presence of independent evolutionary lines for Colombia. Additionally, the nucleotide diversity of horB and vacA genes from Colombian isolates was lower than in the reference strains and showed a significant genetic differentiation supporting the hypothesis of independent clades with recent evolution.ConclusionsThe presence of specific lineages suggest the existence of an hspColombia subtype that emerged from a small and relatively isolated ancestral population that accompanied crossbreeding of human population in Colombia.

Rapid evolution of the Helicobacter pylori AlpA adhesin in a high gastric cancer risk region from Colombia

To be able to survive, Helicobacter pylori must adhere to the gastric epithelial cells of its human host. For this purpose, the bacterium employs an array of adhesins, for example, AlpA. The adhesin AlpA has been proposed as a major adhesin because of its critical role in human stomach colonization. Therefore, understanding how AlpA evolved could be important for the development of new diagnostic strategies. However, the genetic variation and microevolutionary patterns of alpA have not been described in Colombia. The study aim was to describe the variation patterns and microevolutionary process of alpA in Colombian clinical isolates of H. pylori. The existing polymorphisms, which are deviations from the neutral model of molecular evolution, and the genetic differentiation of the alpA gene from Colombian clinical isolates of H. pylori were determined. The analysis shows that gene conversion and purifying selection have shaped the evolution of three different variants of alpA in Colombia.

Draft Genome Sequence of a Helicobacter pylori Strain Isolated from a Patient with Diffuse Gastritis from a Region of High Cancer Risk in Colombia

ABSTRACT The draft genome sequence of one Colombian Helicobacter pylori strain is presented. This strain was isolated from a patient with diffuse gastritis from Tibaná, Boyacá, a region with high gastric cancer risk.

Lesiones preneoplásicas gástricas en pacientes colombianos: asociación de polimorfismos genéticos interleucinas 1B-511, 1RN, 10-819, 10-1082, factor de necrosis tumoral-α-308 y anticuerpos inmunoglobulina G hacia cagA de Helicobacter pylori

Resumen Objetivo Evaluar la asociacion de los polimorfismos de alguna de las citocinas mas estudiadas en relacion con el cancer gastrico (IL-1B-511, IL-1RN intron-2-VNTR, TNF-α-308, IL-10-819 e IL-10-1082) y la presencia de anticuerpos hacia la proteina cagA de Helicobacter pylori con las lesiones preneoplasicas gastricas en pacientes colombianos. Materiales y metodos Se estudiaron 185 pacientes con lesiones preneoplasicas (gastritis atrofica, metaplasia intestinal y displasia), y 154 controles (gastritis no atrofica), provenientes de hospitales de una zona de riesgo alto y otra de riesgo bajo para cancer gastrico. Se obtuvieron biopsias gastricas y muestras de sangre; la genotipificacion de los polimorfismos se hizo por discriminacion alelica usando PCR en tiempo real y por PCR convencional y electroforesis en agarosa (VNTR del intron 2 de IL-1RN); la serologia de Helicobacter pylori y Helicobacter pylori cagA se determino por ELISA. Se utilizo regresion logistica multinomial en el analisis estadistico. Resultados El genotipo IL-1B-511TT ( odds ratio xa0=xa04,05; intervalo de confianza 95% 1,35-12,10) se asocio a metaplasia intestinal; no se observaron otras asociaciones entre los diferentes polimorfismos y las lesiones preneoplasicas. La infeccion por Helicobacter pylori cagA positivo se asocio a gastritis atrofica, metaplasia intestinal y displasia (ORxa0=xa02,66; 13,70; 40,29, respectivamente). Conclusion Los resultados sugieren que entre los genotipos proinflamatorios el genotipo IL-1B - 511TT estaria asociado a la metaplasia intestinal, y la serologia de Helicobacter pylori cagA positivo seria un biomarcador util para intervenir y prevenir la presencia de lesiones preneoplasicas. Se necesitan otros estudios con poblacion colombiana que evaluen la asociacion hallada de IL1B-511 con la metaplasia intestinal.