Citrullinated scavenger receptor class A peptide epitope (Cit-SR-A)

The citrullinated scavenger receptor class A (SR-A) peptide epitope is a neoantigen formed by the post-translational modification of arginine residues to citrulline within the SR-A protein, also known as MSR1 [UniProt, 2024]. This modification is catalyzed by peptidylarginine deiminase (PAD) enzymes, which are typically activated in the tumor microenvironment under conditions of stress, such as hypoxia or nutrient deprivation, which trigger autophagy [Scancell Holdings, 2023]. These citrullinated peptides are subsequently presented on the cell surface by MHC class II molecules, making them visible to CD4+ T cells [Brentville et al., 2020]. While SR-A is naturally expressed on macrophages, its citrullinated form is highly associated with stressed cancer cells in various solid tumors, including lung and ovarian cancers [PubMed, 2016]. Therapeutic strategies, such as the Moditope platform, utilize these epitopes in vaccines to stimulate an immune response that specifically targets and destroys tumor cells while sparing healthy, non-stressed tissue [Scancell, 2024]. This approach exploits the immune system's ability to recognize stress-induced modifications as 'non-self' to overcome tumor-induced immune tolerance.

Other names

Citrullinated MSR1 peptideCitrullinated macrophage scavenger receptor 1Cit-MSR1Citrullinated scavenger receptor A1Moditope SR-A epitope

Stimulation of a potent CD4+ T-cell mediated immune response against tumor cells presenting citrullinated neoantigens on MHC class II molecules.