Probiotic supplementation with Lactiplantibacillus plantarum 299v modulates ER and oxidative stress pathways in ?-cells and prevents Type 1 diabetes in gluten-free BioBreeding Rats

Here we investigated the effect of Lp299v supplement on T1D progression and inflammatory phenotypes in diabetes prone BB DRlyp/lyp rats. Rats were weaned at 21 days onto a normal cereal diet (ND) or a gluten-free hydrolyzed casein diet (HCD), with and without daily Lp299v supplementation. All DRlyp/lyp ND rats developed T1D by day 83 (mean time to onset of 62.8+/-7.9 days). DRlyp/lyp ND+Lp299v rats exhibited an insignificant delay in T1D onset (62.6+/-6.5 days), however 8% remained diabetes-free to day 130. Providing DRlyp/lyp rats HCD prevented T1D in 17% of rats (to age 130 days) and significantly delayed onset (mean time to onset 72.8+/-7.3 days, p<0.001). Providing DRlyp/lyp rats HCD+Lp299v prevented T1D in 25% of rats and more robustly delayed onset (mean time to onset 84.9 +/-14.3 days, p<0.001). While multiplex ELISA failed to detect significantly altered plasma cytokine/chemokine levels at 40 days of life, plasma induced transcription revealed greatest normalization of systemic inflammation in the HCD+Lp299v group. Plasma SCFA levels (propionate and butyrate, p<0.01) were elevated in the HCD+Lp299v group compared to the ND group. Global gene expression analysis of pancreatic islets was conducted at 40 days, prior to insulitis. Endoplasmic reticulum (ER) stress has been implicated in the formation of islet neoantigens that may underlie the initial loss of immune tolerance in T1D. Under one or both diets, Lp299v favorably modulated islet expression levels of pathways and transcripts related to inflammation and innate immunity (Cxcl9, Cxcl10), oxidative stress (Gsta1, Gsta4, Gstp1, Gstk1), as well as ER stress and unfolded protein response (Cirbp, Edem1, Hspa1a, Atf4). These ongoing studies add to a growing understanding that inherited susceptibility can be modulated by diet and microbiota.