VEGF Requires the Receptor NRP-1 To Inhibit Lipopolysaccharide-Dependent Dendritic Cell Maturation

Abstract

To stimulate a productive T cell response, dendritic cells (DC) must undergo maturation characterized by heightened cell surface expression of MHC and costimulatory molecules as well as cytokine production. Conversely, the inhibition of DC maturation is a central mechanism of immune tolerance. The control of the DC maturation process relies on the integration of several cellular stimulatory or inhibitory signals. The soluble factors and their receptors controlling this central aspect of DC biology are incompletely characterized. We show that murine bone marrow-derived DC (BMDC) maturation induced by LPS, as opposed to polyinosinic:polycytidylic acid or cytosine-phosphate-guanine, is robustly inhibited by vascular endothelial growth factor (VEGF), a previously identified immunosuppressive cytokine. Using BMDC from wild type and conditional knockout mice, we show that neuropilin-1 (NRP-1), a known receptor of VEGF, is necessary to suppress LPS-dependent BMDC maturation. The absence of NRP-1 had no ostensible effects on the biology of BMDC in the absence of VEGF. However, NRP-1-deficient BMDC remained completely insensitive to the VEGF-dependent inhibition of BMDC maturation in culture. In the presence of VEGF, NRP-1 directly interacted with the LPS receptor TLR4 and suppressed downstream signaling through ERK and NF-κβ, resulting in a sharp inhibition of MHC class II and costimulatory molecules (CD40, CD86) expression as well as proinflammatory cytokine production. Consequently, we identify NRP-1 as a target to optimize DC maturation within environments that are rich in VEGF, such as tumors.

Multifaceted Role of Neuropilins in the Immune System: Potential Targets for Immunotherapy

“…Thus, when bone marrow-derived DCs are challenged with LPS in presence of VEGF, the latter, in concert with its coreceptor NRP1, impairs DC maturation. This is characterized by the downregulation of MHC-II and other costimulatory molecules, as well as, the expression of proinflammatory cytokines such as IL-12, TNF-α, IL-1β, and IL-6 ( 109 ). Observations of this nature are clinically relevant for the design of more efficient DC vaccines and the reprogramming of DC maturation in conditions where VEGF is present in the surrounding milieu.…”

A secreted pore‐forming protein modulates cellular endolysosomes to augment antigen presentation

“…BMDCs were harvested after treatment with PBS, LPS, or βγ-CAT for 12 hours, and LPS was used as a positive control to induce DC maturation. 41 The percentages of cell-surface CD40 and CD86 molecules, markers of DC maturation, were monitored by flow cytometry. The percentages of CD40 and CD86 positive cells were significantly enhanced after βγ-CAT treatment ( Figure 1H,I, Figure S2A mRNA levels of CD40, CD86, and other cytokines related to DC maturation were upregulated in the presence of βγ-CAT ( Figure S2C,D).…”

Cigarette Smoke Extract Promotes TIM4 Expression in Murine Dendritic Cells Leading to Th2 Polarization through ERK-Dependent Pathways

“…Murine bone marrow-derived DCs were cultured as described by Oussa et al [20]. In brief, bone marrow cells were washed from the mice femur and tibia, RBC were lysed, and the remaining cells were cultured at 1 × 10 6 cells/mL in RPMI medium with 10 ng/mL murine GM-CSF and IL-4.…”