Allergic inflammation triggers dyslipidemia via IgG signalling

Background Allergic diseases begin early in life and are often chronic, thus creating an inflammatory environment that may precede or exacerbate other pathologies. In this regard, allergy has been associated to metabolic disorders and with a higher risk of cardiovascular disease, but the underlying mechanisms remain incompletely understood. Methods We used a murine model of allergy and atherosclerosis, different diets and sensitization methods, and cell‐depleting strategies to ascertain the contribution of acute and late phase inflammation to dyslipidemia. Untargeted lipidomic analyses were applied to define the lipid fingerprint of allergic inflammation at different phases of allergic pathology. Expression of genes related to lipid metabolism was assessed in liver and adipose tissue at different times post‐allergen challenge. Also, changes in serum triglycerides (TGs) were evaluated in a group of 59 patients ≥14 days after the onset of an allergic reaction. Results We found that allergic inflammation induces a unique lipid signature that is characterized by increased serum TGs and changes in the expression of genes related to lipid metabolism in liver and adipose tissue. Alterations in blood TGs following an allergic reaction are independent of T‐cell‐driven late phase inflammation. On the contrary, the IgG‐mediated alternative pathway of anaphylaxis is sufficient to induce a TG increase and a unique lipid profile. Lastly, we demonstrated an increase in serum TGs in 59 patients after undergoing an allergic reaction. Conclusion Overall, this study reveals that IgG‐mediated allergic inflammation regulates lipid metabolism. Allergic inflammation induces a unique lipid signature in circulation that is characterized by triglyceride changes. Blood changes in triglyceride levels and composition during allergic inflammation are driven by IgG signalling. IgG‐mediated allergic inflammation regulates lipid metabolism, which may contribute to atherosclerosis and, ultimately, to cardiovascular events. Abbreviations: HC, high cholesterol; LDLr, low‐density lipoprotein receptor; RE, regular; TG, triglyceride; WT, wild‐type.