Relationship Between Intestinal Bacteria and the Anticancer Effect of Hematopoietic Stem-Cell Transplantation
Menée à partir d'échantillons de selles provenant de 541 patients atteints d'un cancer hématologique, cette étude analyse la relation entre la composition de la flore intestinale, déterminée à l'aide du séquençage de l'ARN ribosomique 16S, et le risque de récidive ou la progression de la maladie dans les deux ans qui suivent une greffe allogénique de cellules souches hématopoïétiques
The complex interplay between the intestinal microbiota and the immune system has been of interest for many years in allogeneic hematopoietic stem-cell transplantation (HSCT). For example, early studies by van Bekkum et al1 demonstrated that, after allogeneic HSCT, germ-free mice had much longer survival times than mice treated in conventional environments. In fact, in those studies, transplantation across murine histocompatibility barriers was not associated with graft-versus-host disease (GVHD) in germ-free mice, but, when bacteria were reintroduced, lethal GVHD followed. Similar data were observed by the Seattle group in early studies of patients with aplastic anemia. They showed that the rate of grades 2 to 4 acute GVHD in patients treated in conventional nursing environments was more than twice the rate in patients treated in laminar airflow rooms with gut decontamination.2 The difference in mortality was thought to be caused by both a reduction in fatal infections by virtue of the reduction in gut bacteria and a reduction in acute GVHD. Studies in aplastic anemia have an advantage, because concerns about leukemic relapse or the effects of prior chemotherapy that may influence susceptibility to infection and the underlying inflammatory milieu are not relevant. Unfortunately, controlled trials of gut decontamination have been difficult to perform and, for the most part, have been equivocal3; however, data continue to suggest that effective gut decontamination does reduce the incidence of acute GVHD.4 One aspect of this observation that remains obscure is the degree that decontamination influences important subsets of bacterial microflora. Most of the studies did not culture the stool, and they certainly did not use more modern approaches, such as 16S ribosomal sequencing.
Journal of Clinical Oncology , éditorial en libre accès, 2016