Immunohistochemical detection of human small lymphatic vessels under normal and pathological conditions using the LYVE-1 antibody

Effect of Semaglutide and Empagliflozin on Pulmonary Structure and Proteomics in Obese Mice

Objective

This study utilized proteomics to investigate changes in protein expression associated with lung health in obese mice exposed to semaglutide and empagliflozin through a high-fat diet.

Methods

Twenty-eight male C57BL/6JC mice were randomly assigned to two groups: a control diet group (n = 7) and a high-fat diet group (n = 21). The HFD group was further divided into three groups: HFD group (n = 7), Sema group (n = 7), and Empa group (n = 7). Post-treatment, mice underwent assessments including glucose tolerance, lipids, oxidative stress markers, body weight, lung weight, and structure. Proteomics identified differentially expressed proteins (DEPs) in lung tissue, and bioinformatics analyzed the biological processes and functions of these proteins.

Results

Semaglutide and empagliflozin significantly attenuated obesity-induced hyperglycemia, abnormal lipid metabolism, oxidative stress response, and can decrease alveolar wall thickness, enlarge alveolar lumen, and reduce collagen content in lung tissue. Both medications also attenuated lung elastic fibre cracking and disintegration. In the HFD/NCD group, there were 66 DEPs, comprising 30 proteins that were increased and 36 that were decreased. Twenty-three DEPs overlapped between Sema/HFD and Empa/HFD, with 11 up-regulated and 12 down-regulated simultaneously. After analysing DEPs in different groups, four proteins - LYVE1, BRAF, RGCC, and CHMP5 - were all downregulated in the HFD group and upregulated by semaglutide and empagliflozin treatment.

Conclusion

This study demonstrates that obesity induced by a high-fat diet causes a reduction in the expression of LYVE1, BRAF, RGCC, and CHMP5 proteins, potentially affecting lung function and structure in mice. Significantly, the administration of semaglutide and empagliflozin elevates the levels of these proteins, potentially offering therapeutic benefits against lung injury caused by obesity. Merging semaglutide with empagliflozin may exert a more pronounced impact.

Lymphatic Vessels in Chronic Rhinosinusitis

Purpose

The purpose of this study was to analyze the nasal lymphatic system in order to uncover novel factors that might be involved in pathogenesis of chronic rhinosinusitis (CRS) with (CRSwNP) and without nasal polyps (CRSsNP).

Patients and Methods

Lymphatic vessels (LVs) and macrophages were localized and counted in the inferior and middle turbinate, the uncinate process and the ethmoid of CRSwNP and CRSsNP patients, the NP and the inferior turbinate of controls (n≥6 per group). Lysates of the same tissue types (n=7 per group) were analyzed for lymphatic vessel endothelial receptor 1 (LYVE-1), for matrix metalloproteinase 14 (MMP-14) and for Hyaluronic acid (HA) using ELISA. HA was localized in sections of CRSwNP NP, CRSsNP ethmoid and control inferior turbinate (n=6 per group). The results of HA levels were correlated to the number of macrophages in tissues. The nasal secretions of CRSwNP (n=28), CRSsNP (n=30), and control (n=30) patients were analyzed for LYVE-1 and HA using ELISA.

Results

The number of LVs was significantly lower in tissues of both CRS groups compared to the control. In the tissue lysates, LYVE-1 expression differed significantly between the CRSwNP tissues with a particularly high level in the NP. MMP-14 was significantly overexpressed in CRSwNP uncinate process. There were no significant differences in tissue HA expression. In the mucus LYVE-1 was significantly underexpressed in CRSsNP compared to CRSwNP and control, while HA was significantly underexpressed in both CRS groups. In the NP, HA and macrophages were accumulated particularly below the epithelium. Tissue levels of HA revealed a significant positive correlation with the number of macrophages.

Conclusion

CRS might be associated with an insufficient clearing of the nasal mucosa through the lymphatics. The accumulation of HA and macrophages might promote inflammation, fluid retention, and polyp formation. These results may provide novel CRS-associated factors.

Kaposiform Lymphangiomatosis: Pathologic Aspects in 43 Patients

Kaposiform lymphangiomatosis is an uncommon generalized lymphatic anomaly with distinctive clinical, radiologic, histopathologic, and molecular findings. Herein, we document the pathology in 43 patients evaluated by the Boston Children's Hospital Vascular Anomalies Center from 1999 to 2020. The most frequent presentations were respiratory difficulty, hemostatic abnormalities, and a soft tissue mass. Imaging commonly revealed involvement of some combination of mediastinal, pulmonary, pleural, and pericardial compartments and most often included spleen and skeleton. Histopathology was characterized by dilated, redundant, and abnormally configured lymphatic channels typically accompanied by dispersed clusters of variably canalized, and often hemosiderotic, spindled lymphatic endothelial cells that were immunopositive for D2-40, PROX1, and CD31. An activating lesional NRAS variant was documented in 9 of 10 patients. The clinical course was typically aggressive, marked by hemorrhage, thrombocytopenia, diminished fibrinogen levels, and a mortality rate of 21%.

Prominent Receptors of Liver Sinusoidal Endothelial Cells in Liver Homeostasis and Disease

Liver sinusoidal endothelial cells (LSECs) are the most abundant non-parenchymal cells lining the sinusoidal capillaries of the hepatic system. LSECs are characterized with numerous fenestrae and lack basement membrane as well as a diaphragm. These unique morphological characteristics of LSECs makes them the most permeable endothelial cells of the mammalian vasculature and aid in regulating flow of macromolecules and small lipid-based structures between sinusoidal blood and parenchymal cells. LSECs have a very high endocytic capacity aided by scavenger receptors (SR), such as SR-A, SR-B (SR-B1 and CD-36), SR-E (Lox-1 and mannose receptors), and SR-H (Stabilins). Other high-affinity receptors for mediating endocytosis include the FcγRIIb, which assist in the antibody-mediated removal of immune complexes. Complemented with intense lysosomal activity, LSECs play a vital role in the uptake and degradation of many blood borne waste macromolecules and small (<280 nm) colloids. Currently, seven Toll-like receptors have been investigated in LSECs, which are involved in the recognition and clearance of pathogen-associated molecular pattern (PAMPs) as well as damage associated molecular pattern (DAMP). Along with other SRs, LSECs play an essential role in maintaining lipid homeostasis with the low-density lipoprotein receptor-related protein-1 (LRP-1), in juxtaposition with hepatocytes. LSECs co-express two surface lectins called L-Specific Intercellular adhesion molecule-3 Grabbing Non-integrin Receptor (L-SIGN) and liver sinusoidal endothelial cell lectin (LSECtin). LSECs also express several adhesion molecules which are involved in the recruitment of leukocytes at the site of inflammation. Here, we review these cell surface receptors as well as other components expressed by LSECs and their functions in the maintenance of liver homeostasis. We further discuss receptor expression and activity and dysregulation associated with the initiation and progression of many liver diseases, such as hepatocellular carcinoma, liver fibrosis, and cirrhosis, alcoholic and non-alcoholic fatty liver diseases and pseudocapillarization with aging.

Sonic hedgehog selectively promotes lymphangiogenesis after kidney injury through noncanonical pathway

Kidney fibrosis is associated with an increased lymphangiogenesis, characterized by the formation and expansion of new lymphatic vessels. However, the trigger and underlying mechanism responsible for the growth of lymphatic vessels in diseased kidney remain poorly defined. Here, we report that tubule-derived sonic hedgehog (Shh) ligand is a novel lymphangiogenic factor that plays a crucial role in mediating lymphatic endothelial cell proliferation and expansion. Shh was induced in renal tubular epithelium in various models of fibrotic chronic kidney disease, and this was accompanied by an expansion of lymphatic vessels in adjacent areas. In vitro, Shh selectively promoted the proliferation of human dermal lymphatic endothelial cells (HDLECs) but not human umbilical vein endothelial cells, as assessed by cell counting, MTT assay, and bromodeoxyuridine incorporation. Shh also induced the expression of vascular endothelial growth factor receptor-3, cyclin D1, and proliferating cell nuclear antigen in HDLECs. Shh did not affect the expression of Gli1, the downstream target and readout of canonical hedgehog signaling, but activated ERK-1/2 in HDLECs. Inhibition of Smoothened with small-molecule inhibitor or blockade of ERK-1/2 activation abolished the lymphatic endothelial cell proliferation induced by Shh. In vivo, inhibition of Smoothened also repressed lymphangiogenesis and attenuated renal fibrosis. This study identifies Shh as a novel mitogen that selectively promotes lymphatic, but not vascular, endothelial cell proliferation and suggests that tubule-derived Shh plays an essential role in mediating lymphangiogenesis after kidney injury.

Hyaluronan as tunable drug delivery system

The hyaluronan (HA) polymer is an important macromolecule of extracellular matrix with remarkable structure and functions: it is a linear and unbranched polymer without sulphate or phosphate groups and has key role in several biological processes in mammals. It is ubiquitous in mammalian tissues with several and specific functions, influencing cell proliferation and migration as well as angiogenesis and inflammation. To exert these important functions in tissues HA modifies the concentration and size. Considering this HA content in tissues is carefully controlled by different mechanisms including covalent modification of the synthetic enzymes and epigenetic control of their gene expression. The function of HA is also critical in several pathologies including cancer, diabetes and chronic inflammation. Among these biological roles, the structural properties of HA allow to use this polymer in regenerative medicine including cosmetics and drug delivery. HA takes advantage from its capacity to form gels even at concentration of 1% producing scaffolds with very intriguing mechanical properties. These hydrogels are useful in regenerative medicine as biocompatible material for advanced therapeutic uses. In this review we highlight the biological aspects of HA addressing the mechanisms controlling the HA content in tissues and its role as drug delivery system.

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

The selective distribution of LYVE-1-expressing endothelial cells and reticular cells in the reticulo-endothelial system (RES)

LYVE-1, a receptor molecule for hyaluronan, is expressed in the lymphatic endothelium, blood sinus endothelium, and certain macrophage lineages. The present immunohistochemical study revealed a broader distribution of LYVE-1 in vascular endothelial cells of the murine lung, adrenal gland, and heart as well as the liver and spleen. In addition, sinus reticular cells-including sinuslining cells-in the medulla of the lymph node also intensely expressed LYVE-1. Ultrastructurally, immuno-gold particles for LYVE-1 were localized on the entire length of plasma membrane in all cell types. Most of these LYVE-1-expressing cells had previously been classified as the reticuloendothelial system (RES) specialized for eliminating foreign particles. An LPS stimulation decreased the LYVE-1 expression in macrophages but elevated the expression at mRNA and protein levels in the liver and lung, major organs for the elimination of blood-born waste substances. LYVE-1-expressing endothelial cells in these organs participated in the endocytosis of exogenous particles, and the uptake ability was conspicuously enhanced by the LPS challenge. Although the expression of the degrading enzyme, hyaluronidase, was generally low in the LYVE-1-expressing cells, they were topographically associated with a dense distribution of macrophages possessing hyaluronidase activities in each tissue. These findings suggest that the LYVE-1-expressing cells might be involved in the uptake of hyaluronan and other waste products as well as foreign particles circulating in the blood and lymph while participating in the subsequent degradation in relay with adjacent macrophage populations.

Linagliptin alleviates fatty liver disease in diabetic db/db mice

AIM

To study the effects of linagliptin on the structural signs of non-alcoholic fatty liver disease (NAFLD) in db/db mice.

METHODS

Male diabetic db/db mice (BKS.Cg-Dock7^m+/⁺Lepr^db/J) aged 10 wk received the dipeptidyl peptidase 4 (DPP4) inhibitor linagliptin (10 mg/kg) or saline as a placebo once per day by gavage for 8 wk. Intact db/db mice served as controls. Structural changes in the liver were analyzed from light and electron microscopic images of sections from intact, placebo-treated and linagliptin-treated animals. We estimated the changes in hepatocytes, sinusoidal cells, liver microvasculature and lymphatic roots. Hepatic staining for lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) was assessed by immunohistochemistry.

RESULTS

In 18-wk-old diabetic mice, liver steatosis (predominantly microvesicular and mediovesicular steatosis) was accompanied by dilation of the roots of the lymphatic system, interlobular blood vessels and bile canaliculi. Compared to saline-treated mice, linagliptin-treated mice exhibited a reduction in the mean numeral densities of hepatocytes with lipid droplets (92.4% ± 1.7% vs 64.9% ± 5.8% per field of view, P = 0.0002) and a lower proportion of hepatocytes with a high density of lipid droplets (20.7% ± 3.6% vs 50.4% ± 3.1%, P = 0.0007). We observed heterogeneous hepatocytes and relatively preserved cell structures in the linagliptin group. Dilation of blood and lymphatic vessels, as well as ultrastructural changes in the hepatocyte endoplasmic reticulum and mitochondria, were alleviated by linagliptin treatment. In intact and placebo-treated mice, immunohistochemical staining for LYVE-1 was observed in the endothelial cells of interlobular lymphatic vessels and on the membranes of some endothelial sinusoidal cells. We observed an enlarged LYVE-1 reaction area in linagliptin-treated mice compared to intact and placebo-treated mice. The improvement in the structural parameters of the liver in linagliptin-treated mice was independent to changes in the plasma glucose levels.

CONCLUSION

The DPP4 inhibitor linagliptin alleviates liver steatosis and structural changes in the hepatic microvasculature and lymphatic roots in a model of NAFLD in diabetic db/db mice.

Artefact as the Pathologist’s Friend: Peritumoral Retraction in In Situ and Infiltrating Duct Carcinoma of the Breast

Peritumoral retraction artefact appears in tissue sections as an empty space partially or completely encircling a nest of tumor cells, usually in conformity with the rounded or angular outline of that particular nest. The present study was designed to test this finding in a large series of cases and to quantify the appearance of peritumoral retraction artefact in, in situ and infiltrating duct carcinoma of the breast. We examined 199 cases of infiltrating duct carcinoma (IDC) and 188 cases of ductal carcinoma in situ (DCIS). Of the total of 387 cases, 111 were core needle biopsies, whereas the others were larger resections. In each specimen, retraction was evaluated on hematoxylin and eosin-stained slides as negative, 1+ (1% to 25% of tumor showing retraction), 2+ (26% to 50%), 3+ (51% to 75%), or 4+ (76% to 100%). Overall, peritumoral retraction was noted in 168 of 199 cases (84.4%) of IDC, versus 30 of 188 cases (16%) of DCIS ( P < 0.0001). Peritumoral retraction scored as 2+ or greater (26% to 50%) was seen in only 1 of 188 DCIS specimens, compared with 77 of 199 IDC. Thus, peritumoral retraction artefact appears to be a significant finding seen during the evaluation of hematoxylin and eosin specimens for the diagnosis of carcinoma. We discuss the possibility that this phenomenon might represent true prelymphatic space involvement rather than a fixation artefact.

Intravascular/Intralymphatic Histiocytosis: A Report of 3 Cases

Intravascular/intralymphatic histiocytosis (IV/ILH) is a rare, reactive cutaneous condition, with uncertain pathogenesis. It may be associated with various inflammatory and neoplastic diseases. Although the clinical presentation is various, the biopsies reveal dilated vessels, mostly lymphatics, containing aggregates of histiocytes within their lumina. We described 3 cases of IV/ILH with different clinical presentations. In the first case, the patient presented with lymphedema in the genital region without any underlying disease. However, the second and third cases had reticular erythematous skin lesions. The second case had common variable immunodeficiency disease, rheumatoid arthritis, inflammatory bowel disease, and a history of a lymphoproliferative lesion. The third case had metal prostheses at both his right and left knees. In all these 3 cases, histopathologic and immunohistochemical findings were similar to each other and to those cases reported in the literature. In addition, the third case was admixed with reactive angioendotheliomatosis. In the second case, the endothelium of the ectatic vessels expressed CD31 and CD34, but not D2-40/podoplanin, pointing out that these vessels were blood vessels rather than lymphatics, differing from the other 2 cases. In conclusion, we believe, the most convincing statement about IV/ILH is that it is not a distinct clinicopathologic entity, but a histopathologic feature found as a part of a constellation of inflammatory changes or many other conditions.

Lymphangiogenesis and Inflammation-Looking for the "Missing Pieces" of the Puzzle

Several papers about lymphangiogenesis and inflammation focused on the detailed and complicated descriptions of the molecular pathways accompanying both non-tumor and tumor inflammatory-induced lymphatic vessel development. Many authors are tempted to present inflammatory-induced lymphangiogenesis in pathologic conditions neglecting the role of inflammatory cells during embryonic lymphatic vessel development. Some of the inflammatory cells are largely characterized in inflammatory-induced lymphangiogenesis, while others as mast cells, eosinophils, or plasma cells are less studied. No phenotypic characterization of inflammation-activated lymphatic endothelial cell is available in this moment. Another paradox is related to the existence of few papers regarding lymphangiogenesis inside lymphoid organs and for their related pathology. There are still several "missing pieces of such a big puzzle" of lymphangiogenesis and inflammation, with a direct impact on the ineffectiveness of the anti-inflammatory therapy as lymphangiogenesis inhibitors. The present paper will focus on the controversial issues of lymphangiogenesis and inflammation.

Biology and biotechnology of hyaluronan

The hyaluronan (HA) polymer is a critical component of extracellular matrix with a remarkable structure: is a linear and unbranched polymer without sulphate or phosphate groups. It is ubiquitous in mammals showing several biological functions, ranging from cell proliferation and migration to angiogenesis and inflammation. For its critical biological functions the amount of HA in tissues is carefully controlled by different mechanisms including covalent modification of the synthetic enzymes and epigenetic control of their gene expression. The concentration of HA is also critical in several pathologies including cancer, diabetes and inflammation. Beside these biological roles, the structural properties of HA allow it to take advantage of its capacity to form gels even at concentration of 1 % producing scaffolds with very promising applications in regenerative medicine as biocompatible material for advanced therapeutic uses. In this review we highlight the biological aspects of HA addressing the mechanisms controlling the HA content in tissues as well as its role in important human pathologies. In the second part of the review we highlight the different use of HA polymers in the modern biotechnology.

Mouse lymphatic endothelial cell targeted probes: anti-LYVE-1 antibody-based magnetic nanoparticles

Purpose

To investigate the specific targeting property of lymphatic vessel endothelial hyaluronan receptor-1 binding polyethylene glycol-coated ultrasmall superparamagnetic iron oxide (LYVE-1-PEG-USPIO) nanoparticles to mouse lymphatic endothelial cells (MLECs).

Methods

A ligand specific target to lymphatic vessels was selected by immunohistochemical staining on the sections of a Lewis subcutaneous transplanted tumor. The z-average hydrodynamic diameter (HD), zeta potential, and the relaxivity of PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles were determined with a laser particle analyzer and magnetic resonance T₂ spin echo sequence, respectively. Prussian blue staining and transmission electron microscopy (TEM) of nanoparticle labeled cells were performed to determine the nanoparticles’ binding form. Magnetic resonance imaging (MRI) was performed in vitro to evaluate the signal enhancement on the T₂ spin echo sequence of the nanoparticle labeled cells. The iron content of the labeled cells after the Prussian blue staining and MRI scanning was determined by atomic absorption spectroscopy (AAS).

Results

The anti-LYVE-1 antibody was used as the specific ligand to synthesize the target probe to the MLECs. The mean z-average HDs of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 57.42 ± 0.31 nm and 47.91 ± 0.73 nm, respectively, and the mean zeta potentials of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 12.38 ± 4.87 mV and 2.57 ± 0.83 m V, respectively. The relaxivities of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 185.48 mM⁻¹s⁻¹ and 608.32 mM⁻¹s⁻¹. Cells binding nanoparticles were visualized as blue granules in the Prussian blue staining. The TEM results of the labeled cells showed the specific localization of nanoparticles. The AAS results of labeled cells after the Prussian blue staining and MRI scanning showed that the LYVE-1-PEG-USPIO nanoparticles had good binding selectivity for MLECs. MRI results indicated that the PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles could generate contrast on T₂-weighted imaging, and the correlation between R₂ and the iron content of the labeled cells was significantly positive.

Conclusion

This study demonstrated that LYVE-1-PEG-USPIO nanoparticles might potentially be used as an MRI contrast agent for targeting MLECs, and the magnetic properties of LYVE-1-PEG-USPIO nanoparticles were suitable for MRI.

BAMBI regulates angiogenesis and endothelial homeostasis through modulation of alternative TGFβ signaling

BACKGROUND

BAMBI is a type I TGFβ receptor antagonist, whose in vivo function remains unclear, as BAMBI(-/-) mice lack an obvious phenotype.

METHODOLOGY/PRINCIPAL FINDINGS

Identifying BAMBI's functions requires identification of cell-specific expression of BAMBI. By immunohistology we found BAMBI expression restricted to endothelial cells and by electron microscopy BAMBI(-/-) mice showed prominent and swollen endothelial cells in myocardial and glomerular capillaries. In endothelial cells over-expression of BAMBI reduced, whereas knock-down enhanced capillary growth and migration in response to TGFβ. In vivo angiogenesis was enhanced in matrigel implants and in glomerular hypertrophy after unilateral nephrectomy in BAMBI(-/-) compared to BAMBI(+/+) mice consistent with an endothelial phenotype for BAMBI(-/-) mice. BAMBI's mechanism of action in endothelial cells was examined by canonical and alternative TGFβ signaling in HUVEC with over-expression or knock-down of BAMBI. BAMBI knockdown enhanced basal and TGFβ stimulated SMAD1/5 and ERK1/2 phosphorylation, while over-expression prevented both.

CONCLUSIONS/SIGNIFICANCE

Thus we provide a first description of a vascular phenotype for BAMBI(-/-) mice, and provide in vitro and in vivo evidence that BAMBI contributes to endothelial and vascular homeostasis. Further, we demonstrate that in endothelial cells BAMBI interferes with alternative TGFβ signaling, most likely through the ALK 1 receptor, which may explain the phenotype observed in BAMBI(-/-) mice. This newly described role for BAMBI in regulating endothelial function has potential implications for understanding and treating vascular disease and tumor neo-angiogenesis.

Vascular and perivascular lesions of skin and soft tissues in children and adolescents

Vascular anomalies in children and adolescents are the most common soft tissue lesions and include reactive, malformative, and neoplastic tumefactions, with a full spectrum of benign, intermediate, and malignant neoplasms. These lesions are diagnostically challenging because of morphologic complexity and recent changes in classification systems, some of which are based on clinical features and others on pathologic findings. In recent decades, there have been significant advances in clinical diagnosis, development of new therapies, and a better understanding of the genetic aspects of vascular biology and syndromes that include unusual vascular proliferations. Most vascular lesions in children and adolescents are benign, although the intermediate locally aggressive and intermediate rarely metastasizing neoplasms are important to distinguish from benign and malignant mimics. Morphologic recognition of a vasoproliferative lesion is straightforward in most instances, and conventional morphology remains the cornerstone for a specific diagnosis. However, pathologic examination is enhanced by adjunctive techniques, especially immunohistochemistry to characterize the type of vessels involved. Multifocality may cause some uncertainty regarding the assignment of "benign" or "malignant." However, increased interest in vascular anomalies, clinical expertise, and imaging technology have contributed greatly to our understanding of these disorders to the extent that in most vascular malformations and in many tumors, a diagnosis is made clinically and biopsy is not required for diagnosis. The importance of close collaboration between the clinical team and the pathologist cannot be overemphasized. For some lesions, a diagnosis is not possible from evaluation of histopathology alone, and in a subset of these, a specific diagnosis may not be possible even after all assembled data have been reviewed. In such instances, a consensus diagnosis in conjunction with clinical colleagues guides therapy. The purpose of this review is to delineate the clinicopathologic features of vascular lesions in children and adolescents with an emphasis on their unique aspects, use of diagnostic adjuncts, and differential diagnosis.

Lymphatic fluctuation in the parenchymal remodeling stage of acute interstitial pneumonia, organizing pneumonia, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis

Because the superficial lymphatics in the lungs are distributed in the subpleural, interlobular and peribroncovascular interstitium, lymphatic impairment may occur in the lungs of patients with idiopathic interstitial pneumonias (IIPs) and increase their severity. We investigated the distribution of lymphatics in different remodeling stages of IIPs by immunohistochemistry using the D2-40 antibody. Pulmonary tissue was obtained from 69 patients with acute interstitial pneumonia/diffuse alveolar damage (AIP/DAD, N = 24), cryptogenic organizing pneumonia/organizing pneumonia (COP/OP, N = 6), nonspecific interstitial pneumonia (NSIP/NSIP, N = 20), and idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP, N = 19). D2-40+ lymphatic in the lesions was quantitatively determined and associated with remodeling stage score. We observed an increase in the D2-40+ percent from DAD (6.66 ± 1.11) to UIP (23.45 ± 5.24, P = 0.008) with the advanced process of remodeling stage of the lesions. Kaplan-Meier survival curves showed a better survival for patients with higher lymphatic D2-40+ expression than 9.3%. Lymphatic impairment occurs in the lungs of IIPs and its severity increases according to remodeling stage. The results suggest that disruption of the superficial lymphatics may impair alveolar clearance, delay organ repair and cause severe disease progress mainly in patients with AIP/DAD. Therefore, lymphatic distribution may serve as a surrogate marker for the identification of patients at greatest risk for death due to IIPs.

Transforming growth factor-β induces vascular endothelial growth factor-C expression leading to lymphangiogenesis in rat unilateral ureteral obstruction

Inflammation is recognized as an important contributor to lymphangiogenesis; however, in tubulointerstitial lesions in human chronic kidney diseases, this process is better correlated with the presence of myofibroblasts rather than macrophages. As little is known about the interaction between lymphangiogenesis and renal fibrosis, we utilized the rat unilateral ureteral obstruction model to analyze inflammation, fibrosis, lymphangiogenesis, and growth factor expression. Additionally, we determined the relationship between vascular endothelial growth factor-C (VEGF-C), an inducer of lymphangiogenesis, and the profibrotic factor, transforming growth factor-β1 (TGF-β1). The expression of both TGF-β1 and VEGF-C was detected in tubular epithelial and mononuclear cells, and gradually increased, peaking 14 days after ureteral obstruction. The kinetics and localization of VEGF-C were similar to those of TGF-β1, and the expression of these growth factors and lymphangiogenesis were linked with the progression of fibrosis. VEGF-C expression was upregulated by TGF-β1 in cultured proximal tubular epithelial cells, collecting duct cells, and macrophages. Both in vitro and in vivo, the induction of VEGF-C along with the overall appearance of lymphatics in vivo was specifically suppressed by the TGF-β type I receptor inhibitor LY364947. Thus, TGF-β1 induces VEGF-C expression, which leads to lymphangiogenesis.

Hyaluronan as an immune regulator in human diseases

Accumulation and turnover of extracellular matrix components are the hallmarks of tissue injury. Fragmented hyaluronan stimulates the expression of inflammatory genes by a variety of immune cells at the injury site. Hyaluronan binds to a number of cell surface proteins on various cell types. Hyaluronan fragments signal through both Toll-like receptor (TLR) 4 and TLR2 as well as CD44 to stimulate inflammatory genes in inflammatory cells. Hyaluronan is also present on the cell surface of epithelial cells and provides protection against tissue damage from the environment by interacting with TLR2 and TLR4. Hyaluronan and hyaluronan-binding proteins regulate inflammation, tissue injury, and repair through regulating inflammatory cell recruitment, release of inflammatory cytokines, and cell migration. This review focuses on the role of hyaluronan as an immune regulator in human diseases.

Phenotype of tumor lymphatic vessels is a prognostic factor in human tongue squamous cell carcinoma

Tumor metastasis to lymph nodes occurs through the lymphatic vessels located in the tumor circumference. However, few studies have focused on the phenotypes of lymphatic vessels around these tumors. We investigated the characteristics of the lymph vessels of tongue squamous cell carcinoma (SCC) and compared them to clinicopathological characteristics. A total of 43 patients diagnosed as having tongue SCC consulted Hokkaido University Hospital were examined. The lymphatic vessels were identified by antibody D2-40 and the number and diameter of tumor lymphatic vessels were measured. The proliferative activity of lymphatic endothelial cells was also examined by immunostaining using antibody MIB-1. We then measured the DNA density of lymphatic endothelial cells in normal and tumor tissues. The number of tumor lymphatic vessels significantly increased in highly metastatic cases of tongue SCC, particularly in cases with a large number of micro lymphatic vessels. A significant correlation was found between the metastatic and proliferative activity of tumor lymphatic endothelial cells. Moreover, the DNA density of tumor lymphatic endothelial cells increased compared to normal tissues. These results suggest that the phenotypes of tumor lymphatic endothelial cells are an indicator of lymph node metastasis of tongue SCC.

Solitary hepatic lymphangioma: report of a case

A 52-year-old woman presented with upper abdominal pain. Abdominal ultrasonography showed a 4-cm well-defined mass containing solid and cystic components in segment IV of the liver, and contrast-enhanced T1-weighted magnetic resonance imaging revealed heterogeneous enhancement within the tumor, indicating a solid or fibrous component. There were no cystic lesions in any other organs. A partial hepatectomy was performed, based on a preoperative diagnosis of sclerosing hemangioma and biliary cystadenoma or cystadenocarcinoma. Pathologically, the tumor appeared to be a multilocular and cystic lesion lined by attenuated endothelial- like cells with no atypia. Immunohistochemistry demonstrated the endothelial-like cells to be positive for the lymphatic-specific markers D2-40, LYVE-1, and Prox-1, which proved helpful for confirming the diagnosis as solitary hepatic lymphangioma. This case is presented with details of the pathologic and radiologic findings, because solitary hepatic lymphangioma is an extremely rare tumor and no previous reports have provided details of the immunohistochemical characteristics.

Solitary hepatic lymphangioma: report of a case

A 52-year-old woman presented with upper abdominal pain. Abdominal ultrasonography showed a 4-cm well-defined mass containing solid and cystic components in segment IV of the liver, and contrast-enhanced T1-weighted magnetic resonance imaging revealed heterogeneous enhancement within the tumor, indicating a solid or fibrous component. There were no cystic lesions in any other organs. A partial hepatectomy was performed, based on a preoperative diagnosis of sclerosing hemangioma and biliary cystadenoma or cystadenocarcinoma. Pathologically, the tumor appeared to be a multilocular and cystic lesion lined by attenuated endothelial- like cells with no atypia. Immunohistochemistry demonstrated the endothelial-like cells to be positive for the lymphatic-specific markers D2-40, LYVE-1, and Prox-1, which proved helpful for confirming the diagnosis as solitary hepatic lymphangioma. This case is presented with details of the pathologic and radiologic findings, because solitary hepatic lymphangioma is an extremely rare tumor and no previous reports have provided details of the immunohistochemical characteristics.

Significance of lymphatic invasion and cancer invasion-related proteins on lymph node metastasis in gastric cancer

BACKGROUND AND AIMS

Cancer invasion and metastasis are critical events for patient prognosis; however, the most important step in the whole process of lymph node (LN) metastasis in gastric cancer remains obscure. In this study, the significance of cancer cell behaviors, such as cell detachment, stromal invasion and lymphatic invasion on regional LN metastasis in gastric cancer was investigated by comprehensive immunohistochemistry.

METHODS

A total of 210 cases with gastric cancer were selected. These consisted of 105 cases with regional LN metastasis (LN[+] group) and 105 cases without LN metastasis (LN[-] group). Both groups exhibited the same depth of invasion. Cancer tissues were subjected to immunohistochemistry with antibodies against claudin-3, claudin-4, beta-catenin, matrix metalloproteinase (MMP)-1, and MMP-2, as well as endothelial markers of lymphatic vessel endothelial hyaluronan receptor-1 and von Willebrand factor for the objective discrimination between lymphatics and blood vessels. The expression of each protein as well as the histopathological parameters were compared between LN(+) and LN(-) groups.

RESULTS

Along with lymphatic invasion by cancer cells and gross tumor size, MMP-1 expression in cancer cells at the invasive front of the primary tumor was a significant, independent predictor of LN metastasis. The expression of claudins and beta-catenin was associated with the histopathological type of cancer, but not with LN status.

CONCLUSION

Among the cancer invasion-related proteins examined, MMP-1 plays a vital role in LN metastasis of gastric cancer. Tumor size, lymphatic invasion and MMP-1 expression level at the invasive front were the predictive factors of LN metastasis of gastric cancer.

Lymphatic vessels develop during tubulointerstitial fibrosis

Recent progress with specific markers of lymphatic vessel endothelium allowed recognition of lymphangiogenic events in various disease states; however, there is little information concerning this process in human chronic renal diseases. To determine this we measured expression of the lymphatic marker D2-40 and vascular endothelial growth factor-C (VEGF-C), a major growth factor in lymphangiogenesis, in 124 human renal biopsy specimens. In the kidneys of control subjects and in uninjured areas of pathologic specimens, lymphatic vessels were detected only around the arcuate and interlobular arteries. An increase in the number of lymphatic vessels was found at the site of tubulointerstitial lesions correlating with the degree of tissue damage and more strongly correlating with areas of fibrosis than inflammation. On serial sections, lymphatic vessel proliferation was found in the tubulointerstitial area at the site of tuft adhesions to Bowman's capsule. Lymphatic growth was associated with VEGF-C expression in inflammatory mononuclear cells and tubular epithelial cells, mainly of proximal tubules. Lymphangiogenesis and VEGF-C expression was elevated in diabetic nephropathy in comparison to other renal diseases. Our results indicate that lymphangiogenesis is a common feature in the progression of the tubulointerstitial fibrosis.

Histopathological predictor for regional lymph node metastasis in gastric cancer

Regional lymph node metastasis in gastric cancer is a definitive indicator of the patient's prognosis. The goal of this study was to identify the predictors for lymph node metastasis among all the possible histopathological parameters, especially by conducting an objective discrimination of the lymphatic and blood vessels. A total of 210 resected primary gastric cancers with or without lymph node metastasis were evaluated based on the conventional histopathological parameters together with immunohistochemistry using antisera-recognizing lymphatic endothelial hyaluronan receptor-1 (LYVE-1), von Willebrand factor, and lymphangiogenesis promoter vascular endothelial growth factor-C (VEGF-C) antibodies. A multivariate regression analyses of the results indicated that only lymphatic invasion was a significant independent predictor of lymph node metastasis at any stage of cancer invasion. VEGF-C expression was partially related to lymph node metastasis in early gastric cancer. The identification of lymphatic invasion by LYVE-1 antibody is therefore useful to predict regional lymph node metastasis in gastric cancer.

Histopathologic determinants of regional lymph node metastasis in early colorectal cancer

BACKGROUND

Early colorectal cancer (ECC) is curable by endoscopic local resection; however, 10% of patients with ECC exhibit lymph node (LN) metastasis. In the current study, accurate predictors for LN metastasis in patients with ECC were examined by using immunohistochemistry with the lymphatic endothelial hyaluronan receptor 1 (LYVE-1) antibody to discriminate between lymphatics and blood vessels.

METHODS

Colorectal tissue specimens obtained from 71 patients with ECC, including 28 patients with regional LN metastasis, were immunostained with antibodies against LYVE-1, beta-catenin, claudin-3, claudin-4, and cytokeratin. The significance of the histopathologic variables for LN metastasis in ECC was investigated on the basis of specific histopathologic parameters.

RESULTS

Lymphatic invasion confirmed by LYVE-1 immunohistochemistry was observed mainly in the submucosal area around the primary tumor and rarely was observed in the tumor. Expression patterns of beta-catenin, claudin-3, and claudin-4 in cancer cells at the invasive front were irrelevant to LN status. Tumor size, depth of invasion, histologic tumor type, budding formation, and lymphatic invasion were statistically significant to LN status in univariate analysis; however, only 2 factors--lymphatic invasion and budding formation at the invasive front-were independent predictors of LN metastasis in ECC.

CONCLUSIONS

LYVE-1 immunohistochemistry appeared to be a useful method for detecting lymphatics invaded by cancer cells, and detailed examination of the submucosa around the tumor may be important for predicting LN metastasis. When lymphatic invasion and budding formation are observed histopathologically in patients with ECC, additional therapy, such as adjuvant chemotherapy or a curative resection of the regional LN, may be required.

Objective recognition of vascular lesions in Mondor's disease by immunohistochemistry

BACKGROUND

Mondor's disease (MD) is considered an inflammatory condition of superficial vasculitis that develops mainly in the anterolateral thoracoabdominal wall. The pathogenesis of the disease has been controversial, however, because of the lack of histopathologic methods for differentiating between the small vein and the lymphatic vessel.

AIM

To objectively examine the origin of vascular lesions in MD, we investigated the endothelial cells of their blood and lymphatic vessels.

METHODS

Immunohistochemical examinations were carried out on specimens involving vascular lesions from 16 patients with MD, using antibodies against von Willebrand factor and human lymphatic vessel endothelial hyaluronan receptor-1, which specifically discriminate between lymphatic and blood vessels.

RESULTS

The histopathologic findings clearly showed thrombophlebitis in 14 patients, a lesion originating in the lymphatic vessel in one patient, and sclerosis that consisted of the artery together with veins in another.

CONCLUSION

This study suggests that almost all cases of MD are due to thrombophlebitis, with a small minority due to lymphangitis or other conditions. We believe this study will contribute to the better recognition of the factual changes in the condition designated MD.

Lymphangiogenesis in myocardial remodelling after infarction

Ishikawa Y, Akishima-Fukasawa Y, Ito K, Akasaka Y, Tanaka M, Shimokawa R, Kimura-Matsumoto M, Morita H, Sato S, Kamata I & Ishii T (2007) Histopathology51, 345–353

Lymphangiogenesis in myocardial remodelling after infarction

Significance of lymphatic invasion and proliferation on regional lymph node metastasis in renal cell carcinoma

We studied the associations of lymphatic invasion and lymphatic vessel density around tumors with lymph node (LN) status in renal cell carcinoma (RCC) by immunohistochemical analysis using D2-40 antibody as a lymphatic marker. Surgically removed specimens from 76 cases with RCC, including 16 cases with LN metastasis, were used. Lymphatic vessel density around the tumor increased compared with normal kidneys but was not significant by LN status. Tumor size, tumor cell types, patterns of tumor growth, nuclear grade of tumor cells, venous invasion, lymphatic invasion, and primary tumor stage were predictive factors for LN metastasis. Based on multivariate regression analysis, only lymphatic invasion was an independent risk factor for LN metastasis. The immunohistochemical detection of lymphatics was useful for identifying the lymphatic invasion of RCC, and the presence of lymphatic invasion around RCC was an independent predictive factor for LN metastasis.

Pseudolymphomatous Cutaneous Angiosarcoma: A Rare Variant of Cutaneous Angiosarcoma Readily Mistaken for Cutaneous Lymphoma

Cutaneous angiosarcoma is probably the most malignant neoplasm involving the skin. Three clinical variants of cutaneous angiosarcoma are recognized, including angiosarcoma of the scalp and face of elderly patients, angiosarcoma associated with chronic lymphedema, and postirradiation angiosarcoma. Histopathologically, these three variants of angiosarcoma show similar features, which consist of poorly circumscribed, irregularly dilated, and anastomosing vascular channels lined by prominent endothelial cells that dissect through the dermis. Focally, neoplastic endothelial cells show large, hyperchromatic, and pleomorphic nuclei, protruding within vascular lumina and creating small papillations. Usually, inflammatory infiltrate is sparse and consists of a patchy, perivascular lymphoid infiltrate around the neoformed vessels. In rare instances, cutaneous angiosarcomas may exhibit prominent inflammatory infiltrate, and the neoplasm may be mistaken for an inflammatory process, both from clinical and histopathologic points of view. We describe four examples of cutaneous angiosarcomas with dense lymphocytic infiltrates involving the neoplasm. Immunohistochemically, lymphocytes expressed immunoreactivity for CD3, CD5, and CD45 markers, whereas the germinal centers were positive for CD20, CD79a, and Bcl-6. The neoplastic endothelial cells expressed immunoreactivity for the CD31, CD34, podoplanin, Prox-1, Lyve-1, and D2-40. We discuss the possible relationship between neoplastic endothelial lymphatic cells and reactive lymphocytes. Cutaneous angiosarcoma with prominent lymphocytic infiltrate may be readily mistaken for cutaneous follicle center cell lymphoma or cutaneous pseudolymphoma.

The human renal lymphatics under normal and pathological conditions

Ishikawa Y, Akasaka Y, Kiguchi H, Akishima-Fukasawa Y, Hasegawa T, Ito K, Kimura-Matsumoto M, Ishiguro S, Morita H, Sato S, Soh S & Ishii T (2006) Histopathology49, 265–273

The human renal lymphatics under normal and pathological conditions

Evidence of lymphangiogenesis in Warthin's tumor of the parotid gland

The details of the pathogenesis of cystadenolymphoma (Warthin's tumor) of the parotid gland are still unclear. Neovascularization is considered to be a pivotal factor for solid tumor progression and biological behavior of the tumor. Using double-labeling immunohistochemistry for LYVE-1 and CD34 (specific markers for lymphatic and vascular endothelial cells, respectively) this study analyzes lymphatic vessel density (LVD) and blood vessel density (BVD) in 10 Warthin's tumors and 10 pleomorphic adenomas of the parotid gland as well as in 5 normal parotid glands and 5 normal parotid lymph nodes. There was no significant difference in the intratumoral LVD and BVD among pleomorphic adenoma and normal parotid gland tissue. In contrast, the intratumoral LVD and BVD were significantly higher in Warthin's tumor than pleomorphic adenoma, normal parotid gland and parotid lymph node (P<0.0001 versus P<0.004). The increase in lymphatic vessels in Warthin's tumor suggests that epithelial tumor cells might promote lymphangiogenesis in this kind of lesions.

Cyclooxygenase-2 expression is associated with VEGF-C and lymph node metastases in gastric cancer patients

Previous studies have suggested that cyclooxygenase-2 (COX-2) over-expression is associated with angiogenesis in gastric cancer. However, the relationship between COX-2 and lymphangiogenesis is still unclear. The aim of this study was to determine the relationship between COX-2 expression and lymphangiogenic factor, vascular endothelial growth factor-C (VEGF-C), in human gastric cancer, as well as to correlate with clinicopathological parameters. Sixty-three gastric cancer patients underwent radical gastrectomy (D2 or D3) were enrolled in this study. The expression of COX-2 and VEGF-C were detected by immunohistochemistry, and the small lymphatic vessels were immunohistochemically stained by LYVE-1 antibody. The association between COX-2 and VEGF-C expressions and clinicopathological parameters (such as gender, tumor location, lymph node status and Lauren classification) were determined. VEGF-C over-expression was observed in 33 of 63 patients (52%), while COX-2 over-expression occurred in 42 of 63 tumor samples (67%). Presence of microlymphatic vessels with LYVE-1 staining was found in 35 cases. COX-2 over-expression was highly correlated with VEGF-C over-expression (P = 0.032), microlymphatic vessels (P = 0.002) as well as presence of metastatic lymph nodes (P = 0.007). However, no significant correlation was found between COX-2 expression and other clinicopathological parameters. Our data suggest that COX-2 expression is associated with lymphangiogenesis and lymph node metastasis in human gastric carcinoma. This raises the possibility that COX-2-mediated VEGF-C over-expression might promote lymph node metastasis via lymphangiogenesis pathway in patients with gastric cancer.

Inducible nitric oxide synthase activity correlates with lymphangiogenesis and vascular endothelial growth factor-C expression in head and neck squamous cell carcinoma

Nitric oxide (NO) is a diatomic free radical molecule that has been implicated in tumour angiogenesis and progression of head and neck squamous cell carcinoma (HNSCC). However, the mechanism underlying the effect of NO on tumour spread remains largely unknown. Tumour lymphangiogenesis has recently received considerable attention and there is increasing evidence that it is relevant for metastasis to lymph nodes in HNSCC. Here, we study the correlation between inducible NOS synthase (iNOS) activity and lymphangiogenesis in a series of 60 HNSCCs and the possible involvement of the lymphangiogenic factor vascular endothelial growth factor (VEGF)-C. HNSCC presenting with lymph node metastasis had a significantly higher lymphatic vessel density in both the tumour mass and the peritumour area (p = 0.006 and p = 0.001, respectively). Similarly, tumours with lymph node metastasis showed greater lymphatic vessel area than tumours with no lymph node involvement (p = 0.001 for intratumour lymphatics and p < 0.001 for peritumour lymphatics). iNOS activity measured in specimens from the tumour periphery correlated strongly with both lymphatic vessel density and lymphatic vessel area (p = 0.01, rs = 0.45 and p < 0.001, rs = 0.725, respectively). Conversely, these correlations were not observed in specimens from the tumour core. In addition, VEGF-C mRNA expression was significantly elevated in tumours with high iNOS activity (p = 0.008, rs = 0.563), and VEGF-C expression correlated positively with the presence of lymph node metastases (p = 0.03). In vitro, in the A431 human squamous carcinoma cell line, exogenous and endogenous stimulation of the iNOS pathway led to up-regulation of VEGF-C, which was blocked by the NOS inhibitor L-NNA. Taken together, our results indicate that iNOS activity may promote lymphangiogenesis and spread to lymph nodes in HNSCC, with the possible involvement of VEGF-C.

Reelin immunoreactivity in lymphatics and liver during development and adult life

Reelin, a glycoprotein secreted by Cajal-Retzius cells, is crucial for cortex lamination and cell positioning. Some peripheral reelin expression has also been reported. Here we describe in developing rat and human and in adult rat very definite reelin immunolocalization in two cell types. Reelin was present in endothelial cells of lymphatic vessels, but not of blood vessels. Reelin was also detected in stellate (Ito) cells of the liver as shown by immunoelectron microscopic examination. The immunlocalization observed in adult tissues indicates a broader role of reelin beyond its previously demonstrated role in neuronal development.

Topographic distribution of lymphatic vessels in the normal human prostate

BACKGROUND

The lymphatic endothelial hyaluronan receptor (LYVE-1) is a specific cell surface protein in lymphatic endothelium. The antiserum against human LYVE-1 was developed and was confirmed a powerful marker of lymphatic endothelium in human organs. With this novel marker we investigated the small network of intraprostate lymphatic vessels.

METHODS

To identify intraprostatic lymphatic vessels, we performed an immunohistochemical staining method using LYVE-1 pAb and von Willebrand Factor (vWF), and assessed the difference in distribution of small lymphatic vessels between the components in the prostate.

RESULTS

The density of lymphatic vessel was significantly high around ejaculatory ducts and in the fibromascular area between the globular area of peripheral zone and transitional zone. Predominat lymphatic vessels distributed in the fibromascular area in the anterior and posterior prostate of extrastromal area.

CONCLUSIONS

Recognition of the distinctive features of the intraprostate lymphatic network, can help the investigation of lymphatic involvement in cancer of the prostate.

Angiogenesis and lymphangiogenesis and expression of lymphangiogenic factors in the atherosclerotic intima of human coronary arteries☆

Little information regarding the development of lymphangiogenesis in coronary atherosclerosis is available. We immunohistochemically investigated the correlation among intimal neovascularization (CD34 for angiogenesis and lymphatic vessel endothelial hyaluronan receptor-1 [LYVE-1] and podoplanin for lymphangiogenesis), the expression of lymphangiogenic factors (vascular endothelial growth factor [VEGF]-C and VEGF-D), and the progression of atherosclerosis using 169 sections of human coronary arteries from 23 autopsy cases. The more the atherosclerosis advanced, the more often the neointimas contained newly formed blood vessels ( P < .0001). Vascular endothelial growth factor-C was expressed mostly in foamy macrophages and in some smooth muscle cells, whereas VEGF-D was abundantly expressed in both. The number of VEGF-C-expressing cells, but not that of VEGF-D-expressing cells, was increased as the lesion advanced and the number of intimal blood vessels increased ( P < .01). Lymphatic vessels were rare in the atherosclerotic intima (LYVE-1 vs CD34 = 13 vs 3955 vessels) compared with the number seen in the adventitia (LYVE-1 vs CD34 = 360 vs 6921 vessels). The current study suggests that VEGF-C, but not VEGF-D, may contribute to plaque progression and be a regulator for angiogenesis rather than lymphangiogenesis in coronary atherosclerotic intimas. Imbalance of angiogenesis and lymphangiogenesis may be a factor contributing to sustained inflammatory reaction during human coronary atherogenesis.