C1QTNF4, also known as C1q/TNF-related protein 4, is a member of the C1QTNF family. It has structural homology with both complement C1q and the tumor necrosis factor superfamily. C1QTNF4 is involved in the regulation of inflammatory pathways with a pro-inflammatory function [1,2]. It may also play a role in innate immunity modulation, as nucleolin has been identified as its cell surface receptor [2].

In a study on systemic lupus erythematosus (SLE), the p.His198Gln mutation in the C1QTNF4 gene was significantly associated with an increased risk of SLE in Iranian patients, and this mutation led to early-onset SLE [1]. In another study, gene-level analysis indicated C1QTNF4 as a functional candidate in SLE susceptibility, and the p.His198Gln de novo mutation (DNM) inhibited the TNF-dependent functions of C1QTNF4 on NF-κB activation and apoptosis [4]. In vascular remodelling, C1QTNF4 was found to inhibit vascular smooth muscle cell (VSMC) proliferation and migration, and down-regulate the FAK/PI3K/AKT pathway, protecting blood vessels from abnormal neointima formation [3].

In conclusion, C1QTNF4 is important in regulating inflammatory pathways and innate immunity. Its mutations are associated with SLE, and it plays a role in vascular remodelling. Studies, especially those on its mutations in relation to SLE, contribute to understanding the disease mechanisms. The findings in vascular remodelling also provide insights into potential treatments for vascular stenosis diseases.