Lymph nodes provide specialized stromal microenvironments that support the recruitment and organization of T cells and B cells, enabling them to effectively participate in immune responses. While CD4 ؉ 3 ؊ lymphoid tissue inducer cells (LTic's) are known to play a key role in influencing lymph node (LN) development, the mechanisms that regulate the development of stromal organizer cells are unclear. Here, we define an ontogenetic program of lymph node stromal cell maturation in relation to the requirement for LTic's. We also describe a lymph node reaggregation assay to study cell-cell interactions and lymphocyte recruitment to these organs that reproduces the in vivo events during lymph node development. In addition, analysis of the lymph node anlagen in normal and lymphotoxin a (LTa)-deficient embryos shows that LTamediated signaling is required to sustain proliferation and survival of stromal cells in vivo. Our data identify LTa-independent and LTa-dependent stages of lymph node development, and provide direct evidence for the role of LTic's during LN organogenesis.( IntroductionOne of the main features of the immune system is the cross-talk interaction between different cell types that ensures full activation of immune responses. The exchange of information between cells of the immune system occurs within specific microenvironments in secondary lymphoid organs such as the spleen, lymph nodes (LNs), and Peyer patches (PPs). Disruption or abnormal development of these microenvironments leads to ineffective adaptive immune responses, resulting in repetitive infections and decrease survival of the host.LN organogenesis during embryo development depends on successful interactions between bone marrow-derived lymphoid tissue inducer cells (LTic's) and mesenchymal organizer stromal cells. [1][2][3] The signals involved in these interactions are transmitted through ligands and receptors of the tumor necrosis factor family that converge in activation of the NF-B transcription factors, resulting in marked changes in gene expression. 4,5 Genetic approaches had shown the crucial roles of lymphotoxin ␤ receptor (Lt␤R) and receptor activator of NF-B (RANK) and their ligands in the development of LNs. For instance, Lta Ϫ/Ϫ mice and Ltbr Ϫ/Ϫ mice lack all LNs, Ltb Ϫ/Ϫ mice form only mesenteric LNs, and Rank Ϫ/Ϫ and Rank-l Ϫ/Ϫ mice develop only rudimentary mesenteric LNs. 3,[6][7][8][9][10] Similarly, mice deficient in the NF-B family proteins RelA and RelB lack all LNs, while Nfkb2 Ϫ/Ϫ and Ikka aa knock-in mice present with defects in peripheral LNs. [11][12][13][14][15][16] While LTic's express the membrane-bound LT␣ 1 ␤ 2 ligand, stromal cells express the LT␤R receptor. Engagement of LT␤R receptor on stromal cells results in production of chemokines such as CXCL13, CCL21, and CCL19, and cell adhesion molecules that will attract further LTic's that express the chemokine receptors CXCR5 and CCR7. [17][18][19] Subsequent formation of cell clusters between LTic's and organizer cells results in organization of specific areas in...

Anti-VEGF therapy perturbs tumor metabolism, severely impairing oxygen, glucose, and ATP levels. In this study, we investigated the effects of anti-VEGF therapy in multiple experimental tumor models that differ in their glycolytic phenotypes to gain insights into optimal modulation of the metabolic features of this therapy. Prolonged treatments induced vascular regression and necrosis in tumor xenograft models, with highly glycolytic tumors becoming treatment resistant more rapidly than poorly glycolytic tumors. By PET imaging, prolonged treatments yielded an increase in both hypoxic and proliferative regions of tumors. A selection for highly glycolytic cells was noted and this metabolic shift was stable and associated with increased tumor aggressiveness and resistance to VEGF blockade in serially transplanted mice. Our results support the hypothesis that the highly glycolytic phenotype of tumor cells studied in xenograft models, either primary or secondary, is a cell-autonomous trait conferring resistance to VEGF blockade. The finding that metabolic traits of tumors can be selected by antiangiogenic therapy suggests insights into the evolutionary dynamics of tumor metabolism. Cancer Res; 75(1); 120-133. Ó2014 AACR.

RelA (p65) phosphorylation at threonine 505 acts as a negative regulator of NF-κB function. In addition to its role in regulation of cell death, a role is demonstrated for T505 phosphorylation in regulating autophagy, proliferation, and migration. NOXA is also identified as a downstream, T505-dependent effector of RelA in cell death.