Infection with Helicobacter pylori is the major cause for the development of peptic ulcer disease (PUD). In children, with no other etiology for the disease, this rare event occurs shortly after infection. In these young patients, habits of smoking, diet, consumption of alcohol and non-steroid anti-inflammatory drugs and stress, in addition to the genetic susceptibility of the patient, represent a minor influence. Accordingly, the virulence of the implicated H. pylori strain should play a crucial role in the development of PUD. Corroborating this, our in vitro infection assays comparing a pool of five H. pylori strains isolated from children with PUD to a pool of five other pediatric clinical isolates associated with non-ulcer dyspepsia (NUD) showed the greater ability of PUD strains to induce a marked decrease in the viability of gastric cells and to cause severe damage in the cells cytoskeleton as well as an impairment in the production/secretion of mucins. To uncover virulence features, we compared the proteome of these two groups of H. pylori strains. Two-dimensional gel electrophoresis followed by mass-spectrometry allowed us to detect 27 differentially expressed proteins between them. In addition to the presence of genes encoding well established virulence factors, namely cagA, vacAs1, oipA “on” status, homB and jhp562 genes, the pediatric ulcerogenic strains shared a proteome profile characterized by changes in the abundance of: motility-associated proteins, accounting for higher motility; antioxidant proteins, which may confer increased resistance to inflammation; and enzymes involved in key steps in the metabolism of glucose, amino acids and urea, which may be advantageous to face fluctuations of nutrients. In conclusion, the enhanced virulence of the pediatric ulcerogenic H. pylori strains may result from a synergy between their natural ability to better adapt to the hostile human stomach and the expression of the established virulence factors.

This study showed evidence of the variability of antigenic pattern among H. pylori strains. We believe that this fact contributes to the failure of anti-H. pylori vaccines and the low accuracy of serological tests based on a low number of proteins or antigens of only one strain.

The planning, implementation and results of the first edition of the Molecular School are presented, as the first pre-university school project held in Portugal. This is not, however, a strictly Portuguese project, since it can be replicated in other countries at the secondary school level, with minor adjustments. Herein, the pilot edition of Molecular School is detailed and discussed, where 36 secondary school students have participated. The plan for the second edition, to be held in the first semester of 2021, with the confirmed participation of around 100 students, is further presented. Briefly, the project is divided in two modules: theoretical and laboratory work. These were prepared in a complementary way and performed to achieve the same purpose: deliver a wider vision of what chemistry really is. Hence, the classes were designed having in mind the applications that chemistry has in our everyday life, in the different academic research fields and in industry. A better preparation and training at the laboratory level was also a goal of this project. The enthusiasm, happiness and the motivation shown by the students, and their eagerness to participate in the future editions of the Molecular School, were clear signs of this project success.