Apoh, also known as apolipoprotein H, is involved in lipid metabolism, regulating triglycerides, and has a role in pathways related to complement and coagulation regulation [3,6,7]. It is one of the apolipoproteins that can bind free fatty acids, regulate the activity of many proteins involved in HDL metabolism, inhibit lipid transfer, and control the endogenous coagulation cascade [5].

In antiphospholipid syndrome (APS), both exosomes containing APOH (APOH-exos) and APS-exos impair vascular development and lead to pregnancy complications. APOH-exos may be key in the pathogenesis of APS as they can directly enter human umbilical vein endothelial cells (HUVECs) and may act through the phospho-extracellular signal-regulated kinase pathway [1]. Also, in APS patients, polymorphisms in the APOH gene (rs1801690, rs52797880, and rs8178847) are associated with susceptibility to recurrent pregnancy loss (RPL) [2].

In type 2 diabetic patients, APOH plasma levels are associated with metabolic syndrome (MS) alterations and vascular disease, with enhanced levels due to increased liver synthesis [3]. In diabetic kidney disease, the mRNA expression level of Apoh was declined [4]. In Influenza infection, low plasma levels of ApoH are associated with a worse prognosis and respiratory failure [7].

In conclusion, Apoh is crucial in lipid metabolism, complement and coagulation regulation. Its study through various models has revealed its significant roles in diseases such as APS, type 2 diabetes, diabetic kidney disease, and influenza infection. Understanding Apoh's functions can potentially provide new therapeutic targets for these diseases.