Crohn's disease is a chronic immune-mediated intestinal inflammation targeted against a yet incompletely defined subset of commensal gut microbiota and occurs on the background of a genetic predisposition under the influence of environmental factors. Genome-wide association studies have identified about 70 genetic risk loci associated with Crohn's disease. The greatest risk for Crohn's disease represent polymorphisms affecting the CARD15 gene encoding nucleotide-binding oligomerization domain 2 (NOD2) which is an intracellular sensor for muramyl dipeptide, a peptidoglycan constituent of bacterial cell wall. The accumulated evidence suggests that gut microbiota represent an essential, perhaps a central factor in the induction and maintaining of Crohn's disease where dysregulation of normal co-evolved homeostatic relationships between intestinal microbiota and host mucosal immune system leads to intestinal inflammation. Taken together, these findings identify Crohn's disease as a syndrome of overlapping phenotypes that involves variable influences of genetic and environmental factors. A deeper understanding of different genetic abnormalities underlying Crohn's disease together with the identification of beneficial and harmful components of gut microbiota and their interactions are essential conditions for the categorization of Crohn's disease patients, which enable us to design more effective, preferably causative, individually tailored therapy. and L. Hrnčířová, J. Krejsek, I. Šplíchal, T. Hrnčíř
S rozvojem molekulární a evoluční biologie si víc a víc uvědomujeme komplikovanost sítí vztahů mezi jednotlivými organismy v biosféře. Každý druh ve své existenci životně závisí na jiných druzích a ty zase na dalších. Někdy je souhra dvou druhů tak těsná, že vyhynutí jednoho druhu znamená zánik obou, někdy dokonce již popisujeme soustavu jako jeden druh. Evoluční vznik každého druhu je silně ovlivněn horizontálními přenosy genů, endosymbiózami etc. Jakýkoli eukaryotický organismus na Zemi, včetně člověka, je složitou stavebnicí genů rozmanitého původu. S nástupem epigenetiky a epigenetické dědičnosti vzniká představa, že prostředí změnu nejen vybírá, nýbrž především vytváří a že tato změna se různými mechanismy může dědit. Člověk tedy není izolován od okolní přírody. Je její součástí v mnohem silnějším smyslu, než jsme si kdy mysleli., The contemporary development of molecular genetics and evolutionary biology and new informations stemming from both these fields learn us, that the complexity of life and global net of relationships in each and every ecosystem is much more complex as previously thought. Every species is in its existence dependent on other species and they still on others. Cooperation between the two species is sometimes so tightly connected, that extinction of one species inevitably leads to the extinction of the other. We even sometimes describe the system as one species altogether. Each and every eucaryotic organism on this planet is a complicated system of genes of different origin, with strong influence of horizontal gene transfer, endosymbiosis etc. The research in the field of epigenetics and epigenetic inheritance lead us to the idea, that the environment not only select the new forms of a species, but that the environemnt first and foremost induces the emergence of new phenotypes and that these changes are or at least sometimes can be inherited. Human being is not isolated from the rest of the nature. We are part of the nature in much stronger sense than we have ever considered., Vácha M. O., and Literatura