Determining the role of oxysterols in lymphocyte homing to lymph nodes in homeostasis and inflammation

确定氧甾醇在淋巴细胞归巢至淋巴结的稳态和炎症中的作用

• 批准号: 10677408
• 负责人: KEVIN Y CHEN
• 金额: $ 3.98万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10677408
• 关键词: 25-hydroxycholesterol; Adhesions; Adoptive Transfer; Antibody Response; Antigens; Area; Autoimmunity; Automobile Driving; B-Cell Activation; B-Lymphocytes; BLR1 gene; Basal lamina; Binding; Biological Assay; Blood; Blood Circulation; Blood capillaries; CCL19 gene; CCL21 gene; CD4 Positive T Lymphocytes; CXCR4 gene; Capillary Endothelial Cell; Carbohydrates; Cells; Cellular Immunity; Chemotactic Factors; Cholesterol; Chronic; Circulation; Complement; Complement 3d Receptors; Coupled; Data; Defect; Dendritic Cells; Dependence; Development; Disease; Drops; Endothelium; Enzymes; Exhibits; Extravasation; Fibroblasts; G-Protein-Coupled Receptors; Generations; Genes; Genetic Transcription; Goals; High Endothelial Venule; Homeostasis; Homing; Hour; Human Herpesvirus 4; Hydroxylation; Immune; Immunization; Immunologic Surveillance; Immunotherapy; In Vitro; Infection; Inflammation; Interferons; Invaded; Knock-out; Knockout Mice; Knowledge; Ligands; Lymphatic; Lymphocyte; Lymphocytic Infiltrate; Lymphoid Tissue; Malignant Neoplasms; Mediating; Memory; Migration Assay; Mixed Function Oxygenases; Mus; Organ; Peripheral; Peyer' s Patches; Process; Property; Publishing; Reporting; Role; Scanning; Signal Transduction; Site; Skin; Stains; Stimulus; Stromal Cells; Surface; T-Lymphocyte; Testing; Toll-like receptors; Virus Diseases; Visualization; Work; acute infection; adaptive immune response; antigen test; cell motility; cell type; chemokine; design; draining lymph node; experimental study; fMet-Leu-Phe receptor; improved; in vivo; intravital imaging; lymph nodes; lymphatic circulation; migration; novel; novel therapeutics; pathogen; postcapillary venule; protein expression; receptor; reconstitution; recruit; selective expression; sialomucins; trafficking; tumor; tumorigenesis; two photon microscopy; vascular addressins

PROJECT SUMMARY/ABSTRACT Lymphocyte entry into lymph nodes (LNs) from blood is a key homeostatic process for efficient initiation of an adaptive immune response to pathogens. Naïve B and T cells traffic through LNs to scan for foreign antigens delivered to and concentrated in these organs from diverse sites of potential infection. If no antigens are encountered, lymphocytes exit LNs into lymphatic circulation before returning to the blood and beginning the cycle again. This constant lymphocyte recirculation requires large scale extravasation into lymphoid tissue under non-inflammatory conditions, and the specialized vessels supporting this process in LNs are called high endothelial venules (HEVs). HEVs express and luminally present several vascular ‘addressins’ and chemokines that together support a multi-step adhesion cascade for lymphocyte entry into LNs. The signals promoting lymphocyte arrest on HEV walls are well-elucidated, but the chemoattractants driving transmigration across the endothelium are not fully understood. Elucidating the ligands and receptors that mediate this fundamental step of entry is essential for understanding and manipulating immune cell trafficking in diseases such as cancer and autoimmunity. The enzyme Ch25h, which produces 25-hydroxycholesterol (25HC) from cholesterol, is highly and selectively expressed in HEVs compared to capillary endothelium in LNs. Furthermore, Cyp7b1, which hydroxylates 25HC to generate 7𝛼𝛼,25-dihydroxycholesterol (7,25HC), is expressed in stromal cells surrounding LN HEVs. 7,25HC is a potent ligand for EBI2, a GPCR that helps guide activated B cell movement within LNs and is also highly expressed in naïve B and T cells. The capability for oxysterol synthesis by HEVs suggests EBI2 and 7,25HC may play a role in mediating lymphocyte entry into LNs. We hypothesize that a gradient of 7,25HC across HEVs supports post-adhesion transendothelial migration of naïve B and T cells. In preliminary studies, EBI2 KO B cells and CD4 T cells displayed a recruitment defect to LNs in adoptive transfers, and a similar homing defect was evident in mice lacking Ch25h or Cyp7b1. Furthermore, dependency on EBI2 for lymphocyte entry into LNs increased in a viral infection setting. We hypothesize this is due to elevated 7,25HC levels and reduced chemokine levels in inflamed LNs. From these results, we aim to determine the step of LN entry that EBI2 directs via a combination of in vivo homing assays, intravital imaging, and in vitro migration assays (Aim 1). In addition, we will examine EBI2’s role in maintaining lymphocyte homing in inflamed LNs by characterizing the changes, and signals mediating these changes, in LN oxysterol and chemokine levels during infection (Aim 2). Overall, this work will define a novel chemoattractant driving lymphocyte migration into LNs and advance our understanding of the transmigration process. As well as their role in LNs, HEVs form in tumor associated tertiary lymphoid tissues and at sites of chronic inflammation. Our findings could inform development of novel therapeutics that modulate lymphocyte infiltration in these disease settings.

项目总结/文摘