Characterization of Angiogenesis and Lymphangiogenesis in Human Minor Salivary Glands with Sjögren’s Syndrome

Abstract

Angiogenesis has been proposed to play a role in the inflammation observed in Sjögren’s Syndrome (SS). However, no studies have validated the degree of angiogenesis in salivary glands with SS. Therefore, the goal of this study was to determine the presence and localization of angiogenesis and lymphangiogenesis in salivary glands with SS. We used frozen tissue sections from human minor salivary glands (hMSG) with and without SS in our analyses. To investigate signs of angiogenesis, hMSG tissue lysates were used to detect levels of the pro-angiogenic protein vascular endothelial growth factor (VEGF) by western blot analyses. Additionally, we labeled blood vessels using antibodies specific to platelet endothelial cell adhesion molecule-1 (PECAM-1) and von Willebrand Factor (vWF) to determine blood vessel organization and volume fraction using fluorescence microscopy. Lymphatic vessel organization and volume fraction were determined using antibodies specific to lymphatic vessel endothelial hyaluronan receptor (LYVE-1). Our results suggest that expression levels of VEGF are decreased in hMSG with SS as compared with controls. Interestingly, there were no significant differences in blood or lymphatic vessel organization or volume fraction between hMSG with and without SS, suggesting that angiogenesis and lymphangiogenesis have little impact on the progression of SS.

Mobilization of lymphatic endothelial precursor cells and lymphatic neovascularization in primary Sjögren's syndrome

“…As displayed in Figure 4M-O, MSG lymphatic vessels were consistently and strongly immunostained by D2-40, while CD31 + blood vessels were consistently negative for D2-40. In line with previous observations in human parotid gland and MSGs [7], lymphatic vessels were absent from acinar regions in control MSGs (Fig. 4D, E, G and H).…”

“…In normal conditions, salivary gland lymphatic vessels are selectively localized within the interlobular connective tissue, being absent in lobules and acinar regions 7, 24. Our study revealed that pSS salivary gland tissues display a consistent increase of interlobular lymphatic vessels.…”

“…In addition, we reported an increased and anatomically aberrant lymphatic neovascularization in MSGs from patients with pSS. The only two available studies that focused on lymphatic neovascularization in MSGs were limited to the assessment of glandular mature lymphatic ECs and yielded conflicting results 7, 8. In fact, while Yazisiz et al .…”

“…Although an increased blood vessel density that parallels the extent of glandular inflammation and an activation of VEGF-A/VEGF receptor (VEGFR)-2 and neuropilin-1 co-receptor pro-angiogenic system have been recently described in pSS [4][5][6], the lymphatic vessel counterpart is almost unexplored. Only two studies attempted to quantify the lymphatic vascular bed extension in pSS MSGs through the detection of mature lymphatic endothelial cells (ECs), but they yielded conflicting results reporting either no difference or an increase in lymphatic capillaries in patients compared with controls (the latter defined as MSGs without foci) [7,8]. During adulthood, lymphatic vessels originate not only from lymphangiogenesis, namely from pre-existing lymphatic vasculature, as previously thought, but also from lymphvasculogenesis, the generation of novel vessels via precursor cells.…”

Peri-articular lymphatic system and "Bi" theory of Chinese medicine in the pathogenesis and treatment of arthritis

“…Lymphatic endothelial cells (LECs) of capillaries present loose overlapping intercellular junctions and anchoring filaments that support fluid drainage. LECs specifically express proteins such as lymphatic endothelial hyaluronan receptor 1 (LYVE-1) (13–16) and podoplanin, (17–19) which have been used as markers for identifying lymphatic vessels in tissue sections. The LEC junctions and permits interstitial fluid uptake when interstitial fluid accumulates within tissues, the extracellular matrix swells and pulls the anchoring filaments.…”