Helicobacter pylori: focus on CagA and VacA major virulence factors: [review] / Helicobacter pylori: enfoque sobre los factores de virulencia CagA y VacA: [revisión]

After colonizing the human gastric mucosa, Helicobacter pylori can remain within the host for years and even decades, and is associated with several, highly significant gastric pathologies. In Mexico, the seroprevalence at 1 year of age is 20 percent and the estimated increment in seropositivity per year is 5 percent for children aged 1-10 years. More than 80 percent of adults are infected by the time they are 18-20 years old. Bacterial virulence factors have been proposed for H. pylori, such as urease, flagella, heat-shock protein, lipopolysaccharide, adhesions, vacuolating cytotoxin, cag pathogenicity island and the cytotoxin-associated protein, the latter being the most studied mechanism to date.

Después de colonizar la mucosa gástrica humana, Helicobacter pylori puede permanecer por años e incluso décadas en el humano, y se asocia a varias patologías gástricas. En México, la seroprevalencia estimada es de 20 por ciento en niños de un año de edad, con una tasa de incremento en seropositividad de 5 por ciento anual durante los primeros 10 años de vida hasta alcanzar 80 por ciento en adultos jóvenes entre los 18 y 20 años de edad. Los factores bacterianos de virulencia propuestos para H. pylori son ureasa, flagelos, proteínas de choque térmico, lipopolisacárido, adhesinas, citotoxina vacuolizante, isla de patogenicidad y la proteína asociada a la citoxina; este último factor es el más estudiado hasta la fecha.

High CD99 expression in memory T and B cells in reactive lymph nodes

We investigated the expression of CD99 in 35 hyperplastic perigastric lymph nodes, which were resected for gastric carcinoma or chronic peptic ulcer. Essentially, all lymphocytes in lymph nodes expressed CD99, but there were two populations with respect to the intensity of CD99 expression--CD99high and CD99low cells. We showed CD99high cells were distributed in paracortical and medullary cords by immunohistochemical study while germinal center cells were CD99low. Using three-color flow cytometric analysis with CD3, CD4, CD8, CD19, CD23, CD45RA, CD45RO, CD69, CD138, IgM, IgD, and IgG, most of CD99high cells were shown to be activated/memory T cells. CD4+CD45RO+ T cells were the subset revealing the highest intensity of CD99 expression while CD4+CD45RA+ T cells were CD99low. Among B cells, IgG+ B cells revealed a higher level of CD99 molecules than IgM+ B cells. These results suggest that CD99 is one of activation-related molecules which are upregulated in recently activated lymphocytes.

Western blot analysis of serological response in Helicobacter pylori in acid peptic diseases.

A prospective study was undertaken in 70 patients presenting with acid peptic disease with the objective of characterising the serological response to Helicobacter pylori and finding antigens specific for the serodiagnosis of H. pylori infection. H. pylori status was assessed by smear microscopy, rapid urease activity, culture and histopathology of endoscopic gastric antral biopsy specimens. Serological characterisation was carried out by using western blotting of various antigenic components of H. pylori and subsequent enzymatic detection of antibodies against them. Four reactive bands in the molecular weight range of 45-65 kDa were present in all subjects irrespective of H. pylori status. Four to six immunoreactive bands in the molecular weight range of 21-45 kDa were found only in patients with positive H. pylori status and histopathologically proven gastritis. These immunoreactive components may be valuable in specific immunodiagnosis of H. pylori infection.

Detection of antibodies to serum IgA and IgG in peptic ulcer cases by indirect haemagglutination test.

Autoantibodies to serum IgA and IgG were detected in 206 peptic ulcer patients (196 duodenal ulcer and 10 gastric ulcer) and 52 healthy age and sex-matched controls by indirect haemagglutination test. A significantly increased mean titre of autoantibodies to serum IgA was observed in the peptic ulcer patients. Forty-eight (24.61%) duodenal ulcer cases had autoantibody titre values above mean +/- 2 SD of controls. Titres of autoantibodies to serum IgG were significantly increased only in the gastric ulcer cases. The results suggest an immunologic abnormality in a sizeable fraction of these cases.

Detection and characterization of circulating immune complexes in peptic ulcer.

BACKGROUND. Immunological factors have been implicated in the pathogenesis of peptic ulcer following the demonstration of autoantibodies against IgA in patients with this disease. We investigated whether circulating immune complexes were present in this condition, and what type of immunoglobulins were involved. METHODS. The sera of 37 patients with duodenal ulcer and 8 with gastric ulcer were tested for the presence of circulating immune complexes using the polyethylene glycol (PEG) assay and the results compared with those in 79 controls. The precipitate was dissociated and the levels of IgA, IgG and IgM estimated using the single radial immunodiffusion technique. Simultaneous estimation of these immunoglobulins in the serum was also done. Autoantibodies against IgA in the serum were tested using the ELISA test. RESULTS. Eleven patients (6 with duodenal ulcer and 5 with gastric ulcer) were found to have circulating immune complexes. The mean protein content of the PEG precipitates was significantly higher in patients than in control subjects (p < 0.001). The mean values of all the immunoglobulin isotypes were higher in patients than in controls. The IgA content in the PEG precipitates of positive cases was higher than that in control subjects (p < 0.05). CONCLUSION. Patients with peptic ulcer have circulating immune complexes which may interfere with normal immunoregulation.

Respuesta de anticuerpos IgG en pacientes colonizados por helicobacter pylori / Antibodies to helicobacter pylori in colonized patients with gastric symptoms and in asymptomatic groups

The IgG antibody response specific to Helicobacter pylori was evaluated through ELISA in a group of 92 gastric patients colonized by this bacteria. 74 had gastritis and 19 gastroduodenal ulcer. Three control groups were studied in a similary way: normal adult volunteers (n=17), adults with E coli or S typhi bacteremia (n=30) and normal infants (n = 30). IgG antibody response to H pylori was demonstrated in 98% of colonized patients and 0% of infants. Asymptomatic individuals and those with bacteremia had high rates of antibody response (76 and 90% respectively), although this rate and also the titers of antibody response were significantly lower than that of colonized patients (p < 0.05). ELISA reactive sera from colonized patients and asymptomatic individuals evidenced a similar antibody pattern when tested by blotting. This profile was absent in non reactive sera, including those with high antibody titers to C jejuni. The presence of specific IgG antibodies to H pylory in the majority of colonized gastric patients and asymptomatic adults suggest that this infection is very common in our population

Antígeno australiano: importancia de su indicación / Australia antigen: importance of its indication

Se estudian 184 casos ingresados en el hospital docente "Comandante Manuel Fajardo", que presentaban enfermedades digestivos, a los cuales se les determinó antígeno australiano, observándose una positividad o presencia del mismo en pacientes con hepatitis viral aguda y crónica, así como en la cirrosis, mientras que en otras afecciones no es recomendable su indicación, aunque sería necesario reafirmar este criterio en un estudio futuro más amplio