The peripheral blood transcriptome reflects leukocyte fractions and activity: applications in diving

Introduction: A number of reports link diving to immune responses and systemic inflammation; the types and severity of which are likely to reflect the mode of diving as well as its pathophysiological outcome. Blood is a complex tissue containing many different cell types, out of which leukocytes are essential constituents of the immune system. Leukocytes are also the only blood cells that have chromosome-containing nuclei; global gene expression in blood – the blood transcriptome - therefore ideally represents the biological state of its leukocytes. While traditional transcriptome analysis addresses the activity of genes and biological pathways, several recent papers have introduced a novel approach that also takes cellular composition into account. This approach, adapted from signal processing in e.g. optics and astronomy, uses algorithms that deconvolute complex transcriptome signals to resolve contributions from distinct leukocyte subtypes present in the sample. Material and Methods: Through a series of studies we have mapped peripheral blood transcriptomes before and after asymptomatic dives in experienced scuba divers, freediving athletes, and occupational saturation divers. We have performed transcriptome signal deconvolution for determination of leukocyte subtype fractions before and after dives, and used systems biology tools to assess the effects of diving on the activity of genes and biological pathways. Results and Discussion: The methodology as well as some results from our studies will be presented and discussed.