A Humanized Diet Profile May Facilitate Colonization and Immune Stimulation in Human Microbiota-Colonized Mice

Background: In spite of the importance of the use of gnotobiotic mice for human fecal transfer, colonization efficiency and immune stimulation after human microbiota inoculation in mice are poorly studied compared to mouse microbiota inoculation. We tested the colonization efficiency and immune responses in mice bred for one additional generation after inoculating the parent generation with either a human (HM) or a mouse microbiota (MM). Furthermore, we tested if colonization efficiency and immune stimulation could be improved in HM-colonized mice by dietary approaches: if these were fed a diet closer to the human diet either in its sources of animal fat and protein [the “animal source” (AS) diet] or in its proportions of macronutrients from the normal sources of a mouse diet [the “human profile” (HP) diet]. Results: Although significantly lower in mice with a human microbiota (30–40% vs. 61– 70%) the colonization efficiency was significantly higher in HM mice fed the HP diet (40%), and in MM mice fed AS (70%). The microbiota of mice fed HP was comparable to the microbiota of mice fed a standard rodent chow, while the microbiota of mice fed the animal source diet (AS) clustered separately. Mice inoculated with mouse fecal matter had significantly more CD4+ T cells and Cd4 expression and significantly fewer regulatory T cells (Tregs) and FoxP3 expression than human microbiota inoculated mice, but cell proportions differences were mostly apparent between mice fed the AS diet. Mice fed the HP diet had significantly higher expression of Cd8a. Conclusion: It is concluded that a diet with a humanized profile could support the establishment of a human microbiota in mice, which will, however, still elicit a lower colonization efficiency compared to mice inoculated with a mouse microbiota.The work was funded by the Innovation Fund Denmark (Grant No. 1355-00004B) and Taconic Biosciences. IM-I was funded during the experimental work by a fellowship associated to her Sara Borrell postdoctoral contract (CD12/00530), and nowadays is supported by a Miguel Servet contract (CP16/00163) both from Instituto de Salud Carlos III co-founded by Fondo Europeo de Desarrollo Regional – FEDER.Ye

Combined Exposure to Anti-Androgens Exacerbates Disruption of Sexual Differentiation in the Rat

OBJECTIVE: The aim of this study was to assess whether the joint effects of three androgen receptor antagonists (vinclozolin, flutamide, procymidone) on male sexual differentiation after in utero and postnatal exposures can be predicted based on dose-response data of the individual chemicals. METHODS: Test chemicals and mixtures were administered by gavage to time-mated nulliparous, young adult Wistar rats from gestational day 7 to the day before expected birth, and from postnatal days 1-16. Changes in anogenital distance (AGD) and nipple retention (NR) in male offspring rats were chosen as end points for extensive dose-response studies. Vinclozolin, flutamide, and procymidone were combined at a mixture ratio proportional to their individual potencies for causing retention of six nipples in male offspring. RESULTS: With AGD as the end point, the joint effects of the three anti-androgens were essentially dose additive. The observed responses for NR were slightly higher than those expected on the basis of dose addition. A combination of doses of each chemical, which on its own did not produce statistically significant AGD alterations, induced half-maximal mixture effects. At individual doses associated with only modest effects on NR, the mixture induced NR approaching female values in the males. CONCLUSIONS: Effects of a mixture of similarly acting anti-androgens can be predicted fairly accurately on the basis of the potency of the individual mixture components by using the dose addition concept. Exposure to anti-androgens, which individually appears to exert only small effects, may induce marked responses in concert with, possibly unrecognized, similarly acting chemicals

Neonatal microbial colonization in mice promotes prolonged dominance of CD11b+Gr-1+cells and accelerated establishment of the CD4+T cell population in the spleen

To assess the microbial influence on postnatal hematopoiesis, we examined the role of early life microbial colonization on the composition of leukocyte subsets in the neonatal spleen. A high number of CD11b(+)Gr-1(+) splenocytes present perinatally was sustained for a longer period in conventionally colonized (CONV) mice than in mono-colonized (MC) and germfree (GF) mice, and the CD4(+) T cell population established faster in CONV mice. At the day of birth, compared to GF mice, the expression of Cxcl2 was up-regulated and Arg1 down-regulated in livers of CONV mice. This coincided with lower abundance of polylobed cells in the liver of CONV mice. An earlier peak in the expression of the genes Tjp1, Cdh1, and JamA in intestinal epithelial cells of CONV mice indicated an accelerated closure of the epithelial barrier. In conclusion, we have identified an important microbiota-dependent neonatal hematopoietic event, which we suggest impacts the subsequent development of the T cell population in the murine spleen

Postnatal hematopoiesis and gut microbiota in NOD mice deviate from C57BL/6 mice

Neonatal studies in different mouse strains reveal that early life colonization affects the development of adaptive immunity in mice. The nonobese diabetic (NOD) mouse spontaneously develops autoimmune diabetes, but neonatal studies of NOD mice are lacking. We hypothesized that NOD mice deviate from another much used mouse strain, C57BL/6, with respect to postnatal microbiota and/or hematopoiesis and compared this in newborn mice of dams housed under the same conditions. A distinct bacteria profile rich in staphylococci was found at postnatal days (PND) 1–4 in NOD mice. Furthermore, a distinct splenic cell profile high in a granulocytic phenotype was evident in the neonatal NOD mice whereas neonatal C57BL/6 mice showed a profile rich in monocytes. Neonatal expression of Reg3g and Muc2 in the gut was deviating in NOD mice and coincided with fewer bacteria attaching to the Mucosal surface in NOD compared to C57BL/6 mice