Marie Lewis

The host and intestinal microbiota have co-evolved and this has resulted in intricate and integrated relationships existing between the two. Correlations between the composition and function of the microbiota and host health are clear, but it is rare that a single bacterial strain is identified as a specific marker for disease. Instead, in conditions such as Inflammatory Bowel Disease, neoplasia and malignancy, autoimmunity, allergy, liver disease, diabetes and obesity-related disorders, the literature refers to a microbial population "shift" which results in dysbiosis.

My research focus is how the intestinal microbiota influences the host system in terms of the development of immune and metabolic phenotype and function, specifically, the immediate and sustained effects of early-life manipulation of both composition and function of the microbiota on long-term 'programming' of host physiology. These manipulations include early-life environment, antibiotic therapy, dietary supplementation and nutrition.

This work has established that the dietary protein source at weaning causes sustained shifts in metabonomic and immunological development and that the effects of probiotics on immune responses can be influenced by earlier nutrition. This work has also provided the first direct evidence, derived from intervention, that components of the early-life environment present on farms profoundly affect both local regulation of the mucosal immune system and systemic immune responses to food proteins at weaning.

The overall, long-term goal of this research is to identify the mechanisms underlying early-life programming events and to develop medically feasible interventions which 'rescue' infants from the detrimental effects resulting from early-life experiences. These include caesarean section, antibiotic therapy and maternal obesity which have been linked to allergy, autoimmunity and metabolic syndrome in off-spring respectively.