Oral Probiotic VSL#3 Prevents Autoimmune Diabetes by Modulating Microbiota and Promoting Indoleamine 2,3-Dioxygenase-Enriched Tolerogenic Intestinal Environment

Figure 1

All-trans-retinoic acid (RA) does not enhance the protective effect of the VSL#3 probiotic against autoimmune T1D. (a) VSL#3 (14 mg/kg of body weight) was administered orally three times per week alone () or in combination with RA (i.p.) (). A control group () received sterile PBS by oral gavage. An additional group received RA alone i.p. All treatments were initiated at 4 weeks of age. Diabetes incidence was evaluated by measuring blood glucose levels staring at 12 weeks of age. For all groups, diabetes was diagnosed after two consecutive measurements of glycemia ≥ 250 mg/dL. Mice were pooled from two independent experiments. The log-rank (Mantel-Cox) test was used for the comparison of diabetes incidence rates between the different groups ( value < 0.05). (b) The histopathological signs of diabetes were evaluated in pancreatic sections stained with hematoxylin-eosin. The islets were ranked as free of insulitis (intact islets), affected by peri-insulitis (mononuclear cells in the connective tissue around the islets), or affected by insulitis (mononuclear cell infiltration > 20% of the islet). (c) Two representative images of the histopathological analysis are shown.

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