Synchrony of High Endothelial Venules and Lymphatic Vessels Revealed by Immunization

Abstract

The mature phenotype of peripheral lymph node (LN) high endothelial venules (HEVs), defined as MAdCAM-1lowPNAdhighLTβRhigh HEC-6SThigh, is dependent on signaling through the lymphotoxin-β receptor (LTβR). Plasticity of PLN HEVs during immunization with oxazolone was apparent as a reversion to an immature phenotype (MAdCAM-1highPNAdlowLTβRlow HEC-6STlow) followed by recovery to the mature phenotype. The recovery was dependent on B cells and was inhibited by LTβR-Ig treatment. Concurrent with HEV reversion, at day 4 following oxazolone or OVA immunization, reduced accumulation of Evans blue dye and newly activated DCs in the draining LNs revealed a temporary afferent lymphatic vessel (LV) functional insufficiency. T cell priming to a second Ag was temporarily inhibited. At day 7, lymphangiogenesis peaked in both the skin and draining LN, and afferent LV function was restored at the same time as HEV phenotype recovery. This process was delayed in the absence of B cells. LV and HEV both express the LTβR. During lymphangiogenesis in the draining LN, HEV, and LV were directly apposed; some vessels appeared to express both PNAd and LYVE-1. Pretreatment with LTβR-Ig drastically reduced the number of PNAd+LYVE-1+ vessels, suggesting a reduction in LV and HEV cross-talk. The concordance in time and function and the close physical contact between LVs and HEVs in the remodeling process after immunization indicate that the two vascular systems are in synchrony and engage in cross-talk through B cells and LTβR.

Absence of Nkx2-3 Homeodomain Transcription Factor Reprograms the Endothelial Addressin Preference for Lymphocyte Homing in Peyer’s Patches

“…It is not yet known how the absence of Nkx2-3 during the embryonic period can influence the postnatal deviation of vascular patterning. A similar plasticity was noted following immunization where mature HEVs in pLN reverted to an immature PNAd 2 MAdCAM-1 + phenotype, with subsequent reversal involving B cell-mediated stimulation of LTbR and B cell-dependent HEV recovery (36).…”

Impaired lymphatic contraction associated with immunosuppression

“…Although lymphangiogenesis and vessel dilation are thought to increase the delivery of lymph to the draining lymph node, a decrease in drainage has also been observed during inflammation and surrounding some cancers (1,2,7). Whether reductions in collecting lymphatic function can affect subsequent immune response by limiting entry of antigen/dendritic cells (DCs) into the draining lymph node (LN) is not known.…”

Transgenic LacZ under control of Hec-6st regulatory sequences recapitulates endogenous gene expression on high endothelial venules

“…Although LacZ levels differed to some extent between the various lines, it was always significantly higher in NALT isolated from 7-to 10-week-old mice (Fig. 3 Bb and Bd) when compared with 3-week-old siblings ( (27,28). Seven days after a single injection of 100 g of LT␤R-Ig per mouse, HEC-6ST and luminal PNAd expression are almost completely inhibited in LN HEV.…”

“…Treatment with LT␤R-Ig can also reverse established insulitis and prevent diabetes (38). Because LT␤R is expressed on several cell types in the LN, including HEV and lymphatic vessel endothelial cells, dendritic cells, and stromal cells (28,(39)(40)(41), LT␤R-Ig treatment can have extensive effects on LN. Thus, investigating the role of LT␤R signaling in regulating HEV phenotype and function without affecting other cell types is challenging and requires appropriate tools.…”