Cd209b, also known as SIGNR1, is a C-type lectin receptor expressed on various cells such as antigen-presenting cells (APCs), microglia, and liver sinusoidal endothelial cells. It plays crucial roles in multiple biological processes including immune responses, pathogen-host interactions, and macrophage polarization. It is involved in pathways related to bacterial dissemination, clearance of pathogens, and regulation of inflammation [1,2,3].

In gene-related studies, mice lacking SIGNR1 (Cd209b) showed increased susceptibility to Uropathogenic Escherichia coli (UPEC) infection, indicating that Cd209b contributes to the clearance of UPEC during urinary tract infections [2]. In experimental colitis, SIGNR1-deficient mice had reduced susceptibility to the disease, with decreased levels of pro-inflammatory cytokines, suggesting its role in regulating inflammation [4].

In conclusion, Cd209b is essential in pathogen-host interactions and immune regulation. Studies using Cd209b-deficient mouse models have revealed its significance in urinary tract infections and experimental colitis, providing insights into disease mechanisms and potential therapeutic targets related to these conditions.

References:

1. Yang, Kun, He, Yingxia, Park, Chae Gyu, Skurnik, Mikael, Chen, Tie. 2019. Yersinia pestis Interacts With SIGNR1 (CD209b) for Promoting Host Dissemination and Infection. In Frontiers in immunology, 10, 96. doi:10.3389/fimmu.2019.00096. https://pubmed.ncbi.nlm.nih.gov/30915064/

2. Zhang, Yingmiao, Zhang, Song, He, Yingxia, Cai, Huahua, Chen, Tie. 2020. Murine SIGNR1 (CD209b) Contributes to the Clearance of Uropathogenic Escherichia coli During Urinary Tract Infections. In Frontiers in cellular and infection microbiology, 9, 457. doi:10.3389/fcimb.2019.00457. https://pubmed.ncbi.nlm.nih.gov/31998663/

3. Park, Jin-Yeon, Choi, Heong-Jwa, Prabagar, Miglena G V, Chin, Chan Young, Kang, Young-Sun. 2008. The C-type lectin CD209b is expressed on microglia and it mediates the uptake of capsular polysaccharides of Streptococcus pneumoniae. In Neuroscience letters, 450, 246-51. doi:10.1016/j.neulet.2008.11.070. https://pubmed.ncbi.nlm.nih.gov/19095040/

4. Saunders, Sean P, Barlow, Jillian L, Walsh, Caitriona M, McKenzie, Andrew N J, Fallon, Padraic G. 2010. C-type lectin SIGN-R1 has a role in experimental colitis and responsiveness to lipopolysaccharide. In Journal of immunology (Baltimore, Md. : 1950), 184, 2627-37. doi:10.4049/jimmunol.0901970. https://pubmed.ncbi.nlm.nih.gov/20130211/