High-Fat Diet-Induced Mild Obesity Alters the Activation of T Cells and Maintains Intestinal Homeostasis in Food Allergy Animal Model

A close association between obesity and food allergies has been described, but from the perspective of T cell differentiation, controversial findings exist regarding the impact of high-fat diet (HFD) feeding on the development of food allergies. Our study aimed to explore the relationship between HFD-induced mild obesity and food allergy development in female BALB/c mice. Following 18 weeks of HFD feeding, experimental animals demonstrated a 10.92% body weight gain accompanied by a 32.45% elevation in total cholesterol levels and a 39.50% increase in low-density lipoprotein-cholesterol levels. Upon allergen challenge, control diet (COD)-fed mice developed obvious food allergy symptoms and hypothermia, which were slightly alleviated in HFD-fed mice. Flow cytometry revealed that splenocytes from HFD-fed mice exhibited a 102.32% increase in CD4⁺T-bet⁺ T (Th1) cell populations and a 38.69% elevation in CD4⁺RORγt⁺ T (Th17) cell populations compared to COD-fed allergic mice. These changes corresponded with a 28.41% reduction in the Th2/Th1 ratio and a 56.67% increase in the Th17/Treg ratio. Moreover, real-time quantitative PCR showed that HFD-fed allergic mice had higher expressions of <i>Foxp3</i>, <i>Occludin1</i>, and <i>TJP1</i> in the intestine. Therefore, we concluded that HFD-induced mild obesity restored the Th2/Th1 and Th17/Treg balance, reinforced intestinal barrier function, and thereby did not increase allergy risk in female BALB/c mice.