FL-infiltrating stromal cells overexpress CXCL12 that triggers FL B-cell migration, adhesion, and activation
Polarization into CXCL12hi stroma involves IL-4pos TFH, unlike TNFpos malignant B cells, revealing an indirect protumoral activity of FL-TFH
Follicular lymphoma (FL) is the most frequent indolent lymphoma and is characterized by the accumulation of germinal center-derived malignant B cells engaged in a bidirectional crosstalk with their supportive microenvironment in invaded lymph nodes (LN) and bone marrow (BM). T follicular helper cells (TFH) and infiltrating stromal cells have been shown to favor FL B-cell growth but the mechanisms of their protumoral effect and how LN/BM microenvironment is converted into a lymphoma-permissive cell niche remain poorly understood. We demonstrated here that FL-infiltrating LN and BM stromal cells overexpressed CXCL12 in situ. IL-4hi FL-TFH, unlike FL B cells themselves, triggered CXCL12 upregulation in human stromal cell precursors. In agreement, expression of CXCL12 was associated with IL-4 expression and signaling within the FL BM and LN niches. This IL-4/CXCL12 axis was amplified in activated lymphoid stromal cells as shown in our in vitro model of human lymphoid stroma differentiation and in an inducible mouse model of ectopic lymphoid organ formation. Finally, CXCL12 triggered primary FL B-cell activation, migration, and adhesion, a process antagonized by Btk and PI3K inhibitors. These data identified the IL-4/CXCL12 loop as a previously unrecognized pathway involved in lymphoid stroma polarization and as a potential therapeutic target in FL patients.
- Submitted August 30, 2016.
- Accepted February 12, 2017.
- Copyright © 2017 American Society of Hematology
To view this item, select one of the options below.
If you already have a subscription, you may gain access using your ASH username and password.
Log in through your institution
Subscribe to the Journal - Subscribe to the print and/or online journal.