SCARF1, also known as scavenger receptor class F member 1, SREC-1 or SR-F1, is a type I transmembrane protein belonging to the scavenger receptor superfamily. It plays a key role in the binding and endocytosis of various endogenous and exogenous ligands, such as modified low-density lipoproteins (LDLs). It is essential for maintaining homeostasis and immunity, and is involved in both innate and adaptive immunity [1].

SCARF1-deficient mice develop a systemic lupus erythematosus (SLE)-like disease, highlighting its importance in the clearance of apoptotic host cells for maintaining homeostasis [1,5]. In liver transplantation, overexpression of SCARF1 in Kupffer cells improves acute rejection and liver function by enhancing phagocytosis, promoting M2 polarization via the calcium-dependent PI3K-AKT-STAT3 signalling pathway [3]. In hepatocellular carcinoma, SCARF1 expression is downregulated in tumor tissues, and higher expression is prognostic of better survival, with a role in recruiting proinflammatory CD4+ T cells [4].

In conclusion, SCARF1 is crucial for maintaining homeostasis and immunity. Gene-knockout mouse models have revealed its significance in preventing autoimmune diseases like SLE, improving liver transplantation outcomes, and in the prognosis of hepatocellular carcinoma. Understanding SCARF1's functions provides insights into disease mechanisms and potential therapeutic targets in these disease areas. [1,3,4,5]

References:

1. Patten, Daniel A. 2018. SCARF1: a multifaceted, yet largely understudied, scavenger receptor. In Inflammation research : official journal of the European Histamine Research Society ... [et al.], 67, 627-632. doi:10.1007/s00011-018-1154-7. https://pubmed.ncbi.nlm.nih.gov/29725698/

2. Wang, Yuanyuan, Xu, Fan, Li, Guangyi, Gu, Yijun, He, Yongning. 2024. Structure of scavenger receptor SCARF1 and its interaction with lipoproteins. In eLife, 13, . doi:10.7554/eLife.93428. https://pubmed.ncbi.nlm.nih.gov/39541158/

3. Xu, Xue-Song, Feng, Zhi-Hao, Cao, Ding, Li, Jin-Zheng, Gong, Jian-Ping. 2021. SCARF1 promotes M2 polarization of Kupffer cells via calcium-dependent PI3K-AKT-STAT3 signalling to improve liver transplantation. In Cell proliferation, 54, e13022. doi:10.1111/cpr.13022. https://pubmed.ncbi.nlm.nih.gov/33686740/

4. Patten, Daniel A, Wilkinson, Alex L, O'Rourke, Joanne M, Shetty, Shishir. 2020. Prognostic Value and Potential Immunoregulatory Role of SCARF1 in Hepatocellular Carcinoma. In Frontiers in oncology, 10, 565950. doi:10.3389/fonc.2020.565950. https://pubmed.ncbi.nlm.nih.gov/34354939/

5. Ramirez-Ortiz, Zaida G, Pendergraft, William F, Prasad, Amit, El Khoury, Joseph, Means, Terry K. 2013. The scavenger receptor SCARF1 mediates the clearance of apoptotic cells and prevents autoimmunity. In Nature immunology, 14, 917-26. doi:10.1038/ni.2670. https://pubmed.ncbi.nlm.nih.gov/23892722/