Cd209a, also known as SIGNR5, is a C-type lectin receptor (CLR) related to human DC-SIGN. It plays crucial roles in immune-related processes. Cd209a can interact with other receptors like Dectin-2 and Mincle, and is involved in signaling pathways such as Raf-1 activation. It is significant in driving immunopathology in certain diseases and has potential in antigen-delivery-mediated adaptive immunity [1,3,4].

In schistosome-induced immunopathology, CD209a-deficient CBA mice show decreased Th17 responses and are protected from severe immunopathology. CD209a augments egg-induced IL-1β and IL-23 production initiated by Dectin-2 and Mincle in vitro [1]. In Helicobacter pylori infection, CD209a mediates LECT2-induced maturation and cytokine secretion in bone marrow-derived dendritic cells (BMDCs), with LECT2 acting via the CD209a-JNK/P38 MAPK pathway [2]. Also, LECT2 protects mice from bacterial sepsis by activating macrophages through the CD209a receptor [5].

In conclusion, Cd209a is a key player in immune-mediated disease processes. Gene-knockout mouse models, especially in schistosomiasis, H. pylori infection, and bacterial sepsis, have revealed its importance in driving Th17-mediated immunopathology, modulating dendritic cell function, and activating macrophages. Understanding Cd209a's function can provide insights into the mechanisms of these diseases and potential therapeutic strategies [1,2,5].

References:

1. Kalantari, Parisa, Morales, Yoelkys, Miller, Emily A, Bunnell, Stephen C, Stadecker, Miguel J. . CD209a Synergizes with Dectin-2 and Mincle to Drive Severe Th17 Cell-Mediated Schistosome Egg-Induced Immunopathology. In Cell reports, 22, 1288-1300. doi:10.1016/j.celrep.2018.01.001. https://pubmed.ncbi.nlm.nih.gov/29386115/

2. Zhang, Xiaofen, Sun, Kefang, Tang, Chenxi, Yu, Chaohui, Li, Lan. 2023. LECT2 modulates dendritic cell function after Helicobacter pylori infection via the CD209a receptor. In Journal of gastroenterology and hepatology, 38, 625-633. doi:10.1111/jgh.16138. https://pubmed.ncbi.nlm.nih.gov/36740832/

3. Ponichtera, Holly E, Shainheit, Mara G, Liu, Beiyun C, Hacohen, Nir, Stadecker, Miguel J. 2014. CD209a expression on dendritic cells is critical for the development of pathogenic Th17 cell responses in murine schistosomiasis. In Journal of immunology (Baltimore, Md. : 1950), 192, 4655-65. doi:10.4049/jimmunol.1400121. https://pubmed.ncbi.nlm.nih.gov/24729611/

4. Schetters, Sjoerd T T, Kruijssen, Laura J W, Crommentuijn, Matheus H W, Garcia-Vallejo, Juan J, van Kooyk, Yvette. 2018. Mouse DC-SIGN/CD209a as Target for Antigen Delivery and Adaptive Immunity. In Frontiers in immunology, 9, 990. doi:10.3389/fimmu.2018.00990. https://pubmed.ncbi.nlm.nih.gov/29867967/

5. Lu, Xin-Jiang, Chen, Jiong, Yu, Chao-Hui, Zhang, Shun, Xu, Lei. 2012. LECT2 protects mice against bacterial sepsis by activating macrophages via the CD209a receptor. In The Journal of experimental medicine, 210, 5-13. doi:10.1084/jem.20121466. https://pubmed.ncbi.nlm.nih.gov/23254286/