Complex microbiota targeted rederivation (CMTR) as an alternative method to study effect of gut microbiota on host physiology
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Rodent models are invaluable tools to study the effects of differing gut microbiota (GM) on health and disease. Our laboratory has demonstrated that mouse GM profiles vary among animal vendors suggesting that subtle differences in GM may be an important experimental variable influencing reproducibility. To assess the role of microbiota on model phenotypes, complex microbiota targeted rederivation (CMTR) can be used. With CMTR, mice of the desired model are rederived using embryo transfer into surrogate dams with one or more desired GM profiles. Unfortunately, differing GM are often present in inbred strains of mice complicating CMTR as these strains frequently have poor reproductive indices and variations in maternal care which can add unwanted experimental variables. To overcome this, we exploited the benefits of outbred mice as surrogates by establishing colonies of CD1 mice with differing GM profiles. CD1 embryos were transferred into CD1 or C57BL/6 surrogate dams that varied by GM composition and complexity to establish three separate colonies. Using targeted next generation sequencing, female offspring were shown to have similar GM profiles to surrogate dams. Furthermore, breeding colonies of CD1 mice with distinct GM profiles were maintained for four generations, demonstrating stability of GM profiles within these colonies. We then compared changes in the phenotype of B6 IL-10-/- and C3H IL-10-/- mice rederived by CMTR using either CD1 colonies or the inbred strains from which the colonies were derived. Cecal and colonic histologic lesion scores differed significantly between groups, but no differences were seen when surrogate source of GM (CD1 vs inbred strain) was compared. These findings underscore that CMTR using outbred CD1 colonies will be an invaluable experimental resource for experiments desiring to assess the role of complex microbiota on model phenotypes.