Oral administration of visceral adipose tissue antigens ameliorates metabolic disorders in mice and elevates visceral adipose tissue-resident CD4+CD25+Foxp3+ regulatory T cells

Obesity and type 2 diabetes are linked with chronic, low-grade inflammation in visceral adipose tissue (VAT). A unique population of VAT-resident CD4+Foxp3+ Tregs plays a crucial role in regulating VAT inflammation and metabolic homeostasis. VAT-resident Tregs display a highly restricted TCR repertoire, suggesting they recognize certain autoantigen(s) in VAT. A dramatic reduction of VAT-resident Tregs has been shown to closely correlate with obesity-related VAT chronic inflammation and metabolic disorders. Oral tolerance strategy may modulate inflammatory response to autoantigens by several mechanisms including induction of autoantigen-specific Tregs. Here, we explored the effects and cellular mechanism of oral administration of VAT pooled antigens on high-fat diet (HFD)-induced metabolic disorders in mice. Indeed, we found that oral treatment of VAT mixture antigens effectively inhibited gain in body weight and fat mass, ameliorated serum lipid parameters, and improved insulin sensitivity in HFD mice. This strategy was shown to significantly restore HFD-induced decrease of VAT-resident Tregs, accompanied by a hampered M2-type to M1-type macrophages phenotypic switch as well as decreased CD8+ T cells infiltration in VAT. Thus, oral administration of VAT antigens may be a novel and safe strategy against obesity and its related metabolic disorders.