Reacción a "Nature publishes results of the Human Cell Atlas"

Thanks to important international collaborations, our understanding of the cellular mechanisms in healthy individuals and the pathophysiology of different diseases is being transformed. In this case, recent work brings significant advances towards the construction of the most detailed map of cell types in the human body known to date. Among the findings is the creation of an atlas of cell populations of the digestive tract, integrating data from 25 single-cell RNA-sequencing studies to map the gastrointestinal tract - an organ essential for nutrition but also notable for its role in the immune system. This atlas has combined information from healthy individuals and those with certain pathologies such as inflammatory bowel disease (ulcerative colitis and Crohn's disease) or coeliac disease, which has made it possible to identify specific cellular changes in them, highlighting the role of epithelial metaplasia associated with intestinal inflammation.

These advances are highly relevant findings for several reasons. On the one hand, because of the prevalence of these diseases, since in Spain coeliac disease affects one in 71 people in children and one in 357 in adults, while inflammatory bowel disease (IBD) is present in 0,7% of the Spanish population. In addition to this, especially for the latter, the incidence is progressively increasing and is expected to affect more than 450.000 people.

Despite their increasing frequency, the great heterogeneity of these conditions’ manifestations in each person makes them extremely complex both for their diagnosis and for the individualisation of any treatment. Therefore, the application of high-resolution techniques at the cellular level, and within international efforts such as these, are the basis for further progress in our knowledge in the coming years.

For the first time, cellular changes (metaplasia) that originate in the stem cells of the intestinal crypts and cause the cells to transform in a similar way to those found at the pyloric level or in Brunner's glands have been linked. Moreover, thanks to the possibility of analysing their function at the tissue level, their role as recruiters of T lymphocytes and neutrophils, essential for triggering the inflammatory process and causing the intestinal damage characteristic of this disease (IBD), has been further explored.

Thus, the cellular and spatial resolution of these analyses create a unique framework that allows significant progress in understanding the mechanisms behind these pathologies, as well as in the search for markers associated with the [different] manifestations and natural histories that we observe among patients, thus opening up a great opportunity to search for new treatment targets and to apply measures that are as individualised as possible to each person. These findings underline the importance of addressing inflammation at the cellular level and establish a basis for applying these insights to other inflammatory tissues and diseases, marking a milestone in the search for innovative treatments.