Microbiote et dépression : une piste thérapeutique prometteuse

Abstract

There is increasing evidence towards an interaction between the intestinal microbiota, gut, and central nervous system. Based on this compelling body of evidence, there is growing enthusiasm for research focused on translating this emerging association into novel therapies for psychiatric illnesses. The links between gut microbiota disturbances and brain dysfunction have clearly been demonstrated in rodents. Researchers have proven that gut microbiota plays a major role in the central nervous system development, and that germ-free mice (mice born by c-section and without microbiota) do develop severe behavioral disorders mimicking MD with social withdrawal, self-neglect, eating and sleep disorders, anxiety, as well as hopelessness. A recent study has demonstrated that this major depression phenotype could be transferable from one mouse to another through microbiota transplantation. Moreover, microbiota dysfunctions have been associated with peripheral immune inflammation as well as neuro-inflammation (also called microglia activation). Subjects with irritable bowel syndrome (IBS) display higher rates of comorbid MD. The gut microbiota of patients with Major Depression (MD) to be similar to that of patients with IBS-diarrhea subtype (IBS-D) in that sense that their gut microbiota was less diverse than that from healthy control samples, with similar abundances of alterations (high proportions of Bacteroides and Prevotella). IBS is currently considered to be the paradigmatic microbiota-related disorder. Another study found the MD groups exhibited increased levels of Enterobacteriaceae and Alistipes (nocive bacteria), though reduced levels of Faecalibacterium (healthy bacteria). In this study, a negative correlation was likewise observed between Faecalibacterium and severity of depressive symptoms. Alpha gut microbiota diversity within samples was associated with depressive severity in two studies. Another study found altered microbiota signatures in the gut microbiota of MD patients, including Bacteroidetes, Proteobacteria, Firmicutes, and Actinobacteria phyla and, more specifically, 16 bacterial families. Probiotics are microorganisms that, when consumed, contribute to the host gut microbial flora, thereby producing beneficial effects on health. Among several possibilities for MD treatment that have garnered substantial interest in recent times, probiotics hold particular appeal. The effectiveness of probiotic administration in MD constitutes a strong evidence for developing microbiota-orientated treatments in this indication. Probiotics have yielded medium-to-large significant effects in the setting of depression (d=−.73 [95% CI=−1.02; −.44]). Whereas the first study evaluating the therapeutic efficacy of prebiotics or probiotics on depression or anxiety was conducted over a decade ago, approximately half of all existing studies were published over the past two years, reflecting the rapidly growing interest in this area. Duration of probiotic administration across trials ranged from 8 days to 45 weeks, whereas it is still unclear if the effect is maintained following probiotic discontinuation.