The lymphatic system: a therapeutic target for central nervous system disorders

The lymphatic vasculature forms an organized network that covers the whole body and is involved in fluid homeostasis, metabolite clearance, and immune surveillance. The recent identification of functional lymphatic vessels in the meninges of the brain and the spinal cord has provided novel insights into neurophysiology. They emerge as major pathways for fluid exchange. The abundance of immune cells in lymphatic vessels and meninges also suggests that lymphatic vessels are actively involved in neuroimmunity. The lymphatic system, through its role in the clearance of neurotoxic proteins, autoimmune cell infiltration, and the transmission of pro-inflammatory signals, participates in the pathogenesis of a variety of neurological disorders, including neurodegenerative and neuroinflammatory diseases and traumatic injury. Vascular endothelial growth factor C is the master regulator of lymphangiogenesis, a process that is critical for the maintenance of central nervous system homeostasis. In this review, we summarize current knowledge and recent advances relating to the anatomical features and immunological functions of the lymphatic system of the central nervous system and highlight its potential as a therapeutic target for neurological disorders and central nervous system repair.

Pharmacological Treatment of Secondary Lymphedema

Lymphedema is a chronic disease that results in swelling and decreased function due to abnormal lymphatic fluid clearance and chronic inflammation. In Western countries, lymphedema most commonly develops following an iatrogenic injury to the lymphatic system during cancer treatment. It is estimated that as many as 10 million patients suffer from lymphedema in the United States alone. Current treatments for lymphedema are palliative in nature, relying on compression garments and physical therapy to decrease interstitial fluid accumulation in the affected extremity. However, recent discoveries have increased the hopes of therapeutic interventions that may promote lymphatic regeneration and function. The purpose of this review is to summarize current experimental pharmacological strategies in the treatment of lymphedema.

Coexpression of TLR9 and VEGF-C is associated with lymphatic metastasis in prostate cancer

Prostate cancer (PCa) is one of the most frequent cancers in men, and its biomolecular targets have been extensively studied. This study aimed to analyze the expression of toll-like receptor 9 (TLR9) and vascular endothelial growth factor C (VEGF-C) and the clinical value of the coexpression of TLR9 and VEGF-C in PCa. We retrospectively evaluated 55 patients with clinically localized, intermediate-risk, or high-risk PCa who underwent laparoscopic radical prostatectomy (LRP) and extended pelvic lymph node dissection (ePLND) without neoadjuvant hormonal therapy at a single institution from June 2013 to December 2016. In all 55 patients, the median number of lymph nodes (LNs) resected was 23 (range: 18–31), and a total of 1269 LNs were removed, of which 78 LNs were positive. Seventeen patients had positive LNs, with a positive rate of 30.9%. In addition, the immunohistochemical results in the above patients revealed that high TLR9 expression was correlated with higher Gleason score (GS) (P = 0.049), increased LN metastasis (P = 0.004), and more perineural invasion (PNI) (P = 0.033). Moreover, VEGF-C expression was associated with GS (P = 0.040), pathological stage (pT stage) (P = 0.022), LN metastasis (P = 0.003), and PNI (P = 0.001). Furthermore, a significant positive correlation between TLR9 and VEGF-C was found (P < 0.001), and the TLR9/VEGF-C phenotype was associated with LN metastasis (P = 0.047). Collectively, we propose that TLR9 stimulation may promote LN metastasis in PCa cells through the upregulation of VEGF-C expression, thereby affecting the prognosis of PCa patients. Therefore, these markers may serve as valuable targets for the treatment of PCa.

Reduction of Tissue Na+ Accumulation After Renal Transplantation

Introduction

Chronic kidney disease (CKD) engenders salt-sensitive hypertension. Whether or not tissue Na⁺ accumulation is increased in CKD patients remains uncertain. How tissue Na⁺ is affected after renal transplantation has not been assessed.

Methods

We measured tissue Na⁺ amount in 31 CKD patients (stage 5) and prospectively evaluated tissue Na⁺ content at 3 and 6 months, following living-donor kidney transplantation. Additionally, pre- and post-transplantation data were compared to 31 age- and sex-matched control subjects. ²³Na-magnetic resonance imaging (²³Na-MRI) was used to quantify muscle and skin Na⁺ of the lower leg and water distribution was assessed by bioimpedance spectroscopy.

Results

Compared to control subjects, CKD patients showed increased muscle (20.7 ± 5.0 vs. 15.5 ± 1.8 arbitrary units [a.u.], P < 0.001) and skin Na⁺ content (21.4 ± 7.7 vs. 15.0 ± 2.3 a.u., P < 0.001), whereas plasma Na⁺ concentration did not differ between groups. Restoration of kidney function by successful renal transplantation was accompanied by mobilization of tissue Na⁺ from muscle (20.7 ± 5.0 vs. 16.8 ± 2.8 a.u., P < 0.001) and skin tissue (21.4 ± 7.7 vs. 16.8 ± 5.2 a.u., P < 0.001). The reduction of tissue Na⁺ after transplantation was associated with improved renal function, normalization of blood pressure as well as an increase in lymphatic growth-factor concentration (vascular endothelial growth factor C [VEGF-C] 4.5 ± 1.8 vs. 6.7 ± 2.7 ng/ml, P < 0.01).

Conclusions

Tissue Na⁺ accumulation in predialysis patients with CKD was almost completely reversed to the level of healthy controls after successful kidney transplantation.

Polymorphism analysis of candidate risk genes for pressure injuries in older Japanese patients: A cross-sectional study at a long-term care hospital

Advances in patient care for pressure injuries (PIs) have reduced the prevalence of PIs in Japan, although not in recent years. Several single-nucleotide polymorphisms (SNPs) have been identified in genes potentially associated with PIs. However, individual variance among PI risks require targeted investigations that may lead to the identification of PI susceptibilities or preventive care options that directly influence PI development pathways. This cross-sectional study examined the association between PIs and SNPs in genes related to tissue tolerance in patients in a long-term care hospital in Japan. A total of 178 participants (130 control, 20 with superficial PI history, and 28 with deep PI history) were enrolled in this study of eight SNPs in hypoxia inducible factor 1 subunit alpha (HIF1A), vascular endothelial growth factor C (VEGFC), heat shock protein 90 alpha family class A member 1 (HSP90AA1), myostatin (MSTN), and vitamin D receptor (VDR). The primary outcome was a history of superficial and deep PIs in the last 6 months. SNPs were examined by real-time polymerase chain reaction, followed by multivariate logistic regression analyses of the associations between the SNPs and PI history. The results showed a significant association between VEGFC rs1485766 and the history of superficial PIs (odds ratio = 2.95; 95% confidence interval = 1.07-8.11; p = 0.04). Stratified analysis using the Braden Scale (≤14) indicated a significant association between HIF1A rs11549465 and deep PIs (p = 0.04). Our study demonstrated that VEGFC rs1485766 and HIF1A rs11549465 were associated with superficial and deep PI susceptibilities, respectively.

Steroids Enable Mesenchymal Stromal Cells to Promote CD8+ T Cell Proliferation Via VEGF-C

Mesenchymal stromal cells (MSCs) function as a formidable regulator of inflammation and tissue homeostasis and expanded MSCs are shown to be effective in treating various inflammatory diseases. Their therapeutic effects require the existence of certain inflammatory cytokines. However, in the absence of sufficient proinflammatory stimuli or in the presence of anti-inflammatory medications, MSCs are animated to promote immune responses and unable to alleviate inflammatory disorders. In this study, it is demonstrated that steroid co-administration interferes the efficacy of MSCs in treating acute graft-versus-host disease (aGvHD). Molecular analysis reveals that vascular endothelial growth factor C (VEGF-C) is highly induced in MSCs by steroids and TNFα and VEGF-C in turn promotes CD8+ T cell response. This immune promoting effect is abolished by blockade or specific genetic ablation of VEGFR3 in CD8+ T cells. Additionally, administration of VEGF-C alone exacerbates aGvHD progression through eliciting more vigorous CD8+ T cell activation and proliferation. Further studies demonstrate that VEGF-C augments the PI3K/AKT signaling process and the expression of downstream genes, such as Cyclin D1. Thus, the data demonstrate that steroids can reverse the immunosuppressive effect of MSCs via promoting VEGF-C-augmented CD8+ T cell response and provide novel information for designing efficacious MSC-based therapies.

c-Myc promotes lymphatic metastasis of pancreatic neuroendocrine tumor through VEGFC upregulation

Pancreatic neuroendocrine tumor (pNET) is a pancreatic neoplasm with neuroendocrine differentiation. pNET in early stage can be treated with surgical resection with long‐term survival, whereas the prognosis of pNET with locoregional or distant metastasis is relatively poor. Lymphangiogenesis is essential for tumor metastasis via the lymphatic system and may overhead distant metastasis. c‐Myc overexpression is involved in tumorigenesis. The role of c‐Myc in lymphangiogenesis is unclear. In this study, we evaluated the mechanism and effect of c‐Myc on lymphangiogenesis of pNET via interaction of lymphatic endothelial cells (LECs) and pNET cells. Lymph node metastasis was evaluated in pNET xenograft mice. Potential target agents to inhibit lymph node metastasis were evaluated in an animal model. We found that vascular endothelial growth factor C (VEGFC) expression and secretion was increased in pNET cell lines with c‐Myc overexpression. c‐Myc transcriptionally upregulates VEGFC expression and the secretion of pNET cells by directly binding to the E‐box of the VEGFC promoter and enhances VEGF receptor 3 phosphorylation and the tube formation of LECs. c‐Myc overexpression is associated with lymph node metastasis in pNET xenograft mice. Combinational treatment with an mTOR inhibitor and c‐Myc inhibitor or VEGFC‐neutralizing chimera protein reduced lymph node metastasis in the mice with c‐Myc overexpression. The mTOR inhibitor acts on lymphangiogenesis by reducing VEGFC expression in pNET cells and inhibiting the tube formation of LECs. In conclusion, mTOR and c‐Myc are important for lymphangiogenesis of pNET and are potential therapeutic targets for prevention and treatment of lymph node metastasis in pNET.

Overexpression of VEGF165 is associated with poor prognosis of cervical cancer

BACKGROUND

Cervical cancer is a major health hazard to Indian women. Human papillomavirus (HPV) infection is an established risk factor for cervical carcinogenesis. However, understanding the cervical cancer biology beyond HPV infection is very crucial to predict aggressive behavior, prognosis, treatment response and survival. In the present study, we explored the role of vascular endothelial growth factor A (VEGFA) isoforms, VEGFC and VEGFD in cervical cancer progression and its association with HPV 16 and 18 infections.

MATERIAL AND METHODS

A total of 110 cervical cancer tissues and 50 normal cervical tissues were collected for the study. Reverse transcription-polymerase chain reaction was employed to analyze tissue VEGFA isoforms, VEGFC and VEGFD expression.

RESULTS

VEGF165 was significantly higher, whereas VEGFC and VEGFD were significantly lower in malignant cervical carcinoma tissues as compared to normal cervix tissues. Expression levels of VEGF121 and VEGFC were significantly associated with type of tumor growth while VEGF165 was significantly associated with lymph node metastasis. VEGF165 transcript levels were significantly higher in patients with squamous cell carcinoma (SCC) and developed recurrence. Most strikingly, higher VEGF165 expression was significantly associated with worst disease-free survival (DFS) specifically in patients with SCC.

CONCLUSION

Association of VEGF165 with lymph node metastasis, disease recurrence and worst DFS indicated that VEGF165 is an important prognostic factor in cervical carcinogenesis.

The Diagnostic and Prognostic Role of Vascular Endothelial Growth Factor C in Sepsis and Septic Shock

Introduction

Variations in the expression of vascular endothelial growth factor (VEGF) could be used as a biomarker in critically ill patients with sepsis and septic shock. Inflammation potently upregulates VEGF-C expression via macrophages with an unpredictable response. This study aimed to assess one of the newer biomarkers (VEGF-C) in patients with sepsis or septic shock and its clinical value as a diagnostic and prognostic tool.

Material and methods

The study involved 142 persons divided into three groups. Group A consisted of fifty-eight patients with sepsis; Group B consisted of forty-nine patients diagnosed as having septic shock according to the Sepsis -3 criteria. A control group of thirty-five healthy volunteers comprised Group C. Severity scores, prognostic score and organ dysfunction score, were recorded at the time of enrolment in the study. The analysis included specificity and sensitivity of plasma VEGF-C for diagnosis of septic shock. Circulating plasma VEGF-C levels were correlated with the APACHE II, MODS and severity scores and mortality.

Results

The mean (SD) plasma VEGF-C levels in septic shock patients (1374(789) pg./m), on vasopressors at the time of admission to the ICU, were significantly higher 1374(789)pg./mL, compared the mean (SD) plasma VEGF-C levels in sepsis patients (934(468) pg./mL); (p = 0.0005, Student's t-test.) Plasma VEGF-C levels in groups A and B were shown to be significantly correlated with the APACHE II (r = 0.21, p = 0.02; r = 0.45, p = 0.0009) and MODS score (r = 0.29, p = 0.03; r = 0.4, p = 0.003). There was no association between plasma VEGF-C levels and mortality [p = 0.1]. The cut-off value for septic shock was 1010 pg./ml.

Conclusions

VEGF-C may be used as a prognostic marker in sepsis and septic shock due to its correlation with APACHE II values and as an early marker to determine the likelihood of developing MODS. It could be used as an early biomarker for diagnosing patients with septic shock.

Effect of oral mucosal transplantation on the expression of EGF and VEGF-C during skin wound repair

This study evaluated the effects of oral mucosal transplantation on epidermal growth factor (EGF) and vascular endothelial growth factor C (VEGF-C) in skin wound repair. Sixty-four rats were randomly separated into group A, B, C and D (16 rats in each group). The right abdomen skin was excised 1, 3, 5 and 7 days after injury, respectively. Oral mucosa of the rat tongue was transplanted to the right abdomen skin. Fourteen days after the healing of the oral mucosa graft, the rat skin full-thickness model was prepared at the transplant site (the study group) and the contralateral site (the control group). Rats in each group were anesthetized and sacrificed at 1, 3, 5 and 7 days after injury. Expression of EGF and VEGF-C in skin tissue was detected by RT-qPCR and ELISA. At 3 days, expression levels of EGF and VEGF-C mRNA and protein in skin tissue were significantly higher than those at 1 day (P<0.05). At 5 days, expression levels of EGF and VEGF-C mRNA and protein in skin tissue were significantly higher than those at 3 days (P<0.05). At 7 days, expression levels of EGF mRNA and protein in skin tissue were significantly lower than those at 5 days (P<0.05), while VEGF-C levels were significantly increased (P<0.05). Expression levels of EGF and VEGF-C mRNA and protein in the skin tissue of the study group were significantly lower than those in the control group at all days (P<0.05). EGF and VEGF-C may be involved in scar formation, and play an important role in the process of skin wound repair.

Chemokine CCL4 Induces Vascular Endothelial Growth Factor C Expression and Lymphangiogenesis by miR-195-3p in Oral Squamous Cell Carcinoma

The inflammatory chemokine (C–C motif) ligand 4 (CCL4) plays an important role in the pathogenesis and progression of cancer. In particular, higher serum CCL4 levels in patients with oral squamous cell carcinoma (OSCC) are associated with a more advanced stage of disease. OSCC accounts for approximately 95% of oral cancer in Taiwan and has a poor prognosis, due to aggressive local invasion and metastasis, leading to recurrence. OSCC spreads preferentially through lymphatic vessels and has the propensity to metastasize to the cervical lymph nodes even in the early stage of disease. Vascular endothelial growth factor C (VEGF-C) is an essential regulator of lymphangiogenesis. In particular, VEGF-C is specific to lymphatic vessel development, and VEGF-C expression levels have been found to directly correlate with lymph node metastasis in OSCC. However, it is unclear as to whether CCL4 correlates with VEGF-C expression and lymphangiogenesis in OSCC. We found that CCL4 increased VEGF-C expression and promoted lymphangiogenesis in oral cancer cells in vitro and in vivo. miR-195-3p mimic reversed CCL4-enhanced VEGF-C expression. CCL4 stimulation of oral cancer cells augmented JAK2 and STAT3 phosphorylation. Thus, CCL4 may be a new molecular therapeutic target for inhibition of lymphangiogenesis and metastasis in OSCC.

Enhancing Renal Lymphatic Expansion Prevents Hypertension in Mice

RATIONALE

Hypertension is associated with renal infiltration of activated immune cells; however, the role of renal lymphatics and immune cell exfiltration is unknown.

OBJECTIVE

We tested the hypotheses that increased renal lymphatic density is associated with 2 different forms of hypertension in mice and that further augmenting renal lymphatic vessel expansion prevents hypertension by reducing renal immune cell accumulation.

METHODS AND RESULTS

Mice with salt-sensitive hypertension or nitric oxide synthase inhibition-induced hypertension exhibited significant increases in renal lymphatic vessel density and immune cell infiltration associated with inflammation. Genetic induction of enhanced lymphangiogenesis only in the kidney, however, reduced renal immune cell accumulation and prevented hypertension.

CONCLUSIONS

These data demonstrate that renal lymphatics play a key role in immune cell trafficking in the kidney and blood pressure regulation in hypertension.

Biology of Vascular Endothelial Growth Factor C in the Morphogenesis of Lymphatic Vessels

Because virtually all tissues contain blood vessels, the importance of hemevascularization has been long recognized in regenerative medicine and tissue engineering. However, the lymphatic vasculature has only recently become a subject of interest. Central to the task of growing a lymphatic network are lymphatic endothelial cells (LECs), which constitute the innermost layer of all lymphatic vessels. The central molecule that directs proliferation and migration of LECs during embryogenesis is vascular endothelial growth factor C (VEGF-C). VEGF-C is therefore an important ingredient for LEC culture and attempts to (re)generate lymphatic vessels and networks. During its biosynthesis VEGF-C undergoes a stepwise proteolytic processing, during which its properties and affinities for its interaction partners change. Many of these fundamental aspects of VEGF-C biosynthesis have only recently been uncovered. So far, most—if not all—applications of VEGF-C do not discriminate between different forms of VEGF-C. However, for lymphatic regeneration and engineering purposes, it appears mandatory to understand these differences, since they relate, e.g., to important aspects such as biodistribution and receptor activation potential. In this review, we discuss the molecular biology of VEGF-C as it relates to the growth of LECs and lymphatic vessels. However, the properties of VEGF-C are similarly relevant for the cardiovascular system, since both old and recent data show that VEGF-C can have a profound effect on the blood vasculature.

VEGF-C mediated enhancement of lymphatic drainage reduces intestinal inflammation by regulating IL-9/IL-17 balance and improving gut microbiota in experimental chronic colitis

BACKGROUND

Inflammation-associated lymphangiogenesis (IAL) induced by vascular endothelial growth factor (VEGF)-C/VEGF receptor-3 (VEGFR-3) pathway plays a crucial role in chronic intestinal inflammation. This study aimed to investigate the effects of VEGF-C mediated enhancement of lymphatic drainage on the intestinal inflammation in experimental chronic colitis (CC) and the potential mechanism was explored.

METHODS

Mouse CC model was established by three cycles of 2% DSS administration for 5 days following water administration for 5 days. CC mice were injected via the tail vein with AD-VEGF-C-EGFP (VEGF-C+DSS group) or AD-EGFP (AD-EGFP group) at the end of each cycle and animals in control group were given access to drinking water only. Disease activity index (DAI), lymphatic vessel density (LVD), colonic cytokines, Th9 cells (CD3⁺ cells) and CD68⁺ macrophage infiltration, and lymph flow were detected. Fresh feces were collected and processed for DNA extraction and MiSeq Illumina sequencing of V4 region of bacterial 16S rRNA gene. Alpha- and beta diversities and compositional differences at phylum and genus levels were determined in intestinal microbiota.

RESULTS

AD-VEGF-C treatment significantly reduced colon inflammation, elevated the increase in lymph drainage, decreased CD68⁺ macrophages and CD3⁺ T cells (Th9 cells), reduced IL-9, and increased IL-17 in colon mucosa when compared with DSS mice. In addition, VEGF-C treated mice showed significantly increased the abundance of Bacterioidate and decreased Firmicutes at phylum level in fecal samples.

CONCLUSION

VEGF-C improves intestinal inflammation by enhancing lymphatic drainage, reducing intestinal Th9 cells, regulating intestinal IL-9/IL-17 balance and increasing intestinal Bacterioidate abundance in CC mice.

Novel Mechanism for Buffering Dietary Salt in Humans: Effects of Salt Loading on Skin Sodium, Vascular Endothelial Growth Factor C, and Blood Pressure

High dietary sodium intake triggers increased blood pressure (BP). Animal studies show that dietary salt loading results in dermal Na⁺ accumulation and lymphangiogenesis mediated by VEGF-C (vascular endothelial growth factor C), both attenuating the rise in BP. Our objective was to determine whether these mechanisms function in humans. We assessed skin electrolytes, BP, and plasma VEGF-C in 48 healthy participants randomized to placebo (70 mmol sodium/d) and slow sodium (200 mmol/d) for 7 days. Skin Na⁺ and K⁺ concentrations were measured in mg/g of wet tissue and expressed as the ratio Na⁺:K⁺ to correct for variability in sample hydration. Skin Na⁺:K⁺ increased between placebo and slow sodium phases (2.91±0.08 versus 3.12±0.09; P=0.01). In post hoc analysis, there was a suggestion of a sex-specific effect, with a significant increase in skin Na⁺:K⁺ in men (2.59±0.09 versus 2.88±0.12; P=0.008) but not women (3.23±0.10 versus 3.36±0.12; P=0.31). Women showed a significant increase in 24-hour mean BP with salt loading (93±1 versus 91±1 mm Hg; P<0.001) while men did not (96±2 versus 96±2 mm Hg; P=0.91). Skin Na⁺:K⁺ correlated with BP, stroke volume, and peripheral vascular resistance in men but not in women. No change was noted in plasma VEGF-C. These findings suggest that the skin may buffer dietary Na⁺, reducing the hemodynamic consequences of increased salt, and this may be influenced by sex.

miR-144 inhibits growth and metastasis of cervical cancer cells by targeting VEGFA and VEGFC

MicroRNAs (miRs) are aberrantly expressed in various cancer types and have critical roles in their genesis and progression. miR-144 has been identified to be involved in the development of hepatocellular carcinoma and rectal cancer. However, the roles of miR-144 in cervical cancer and the underlying molecular mechanisms have remained elusive. The present study identified that miR-144 was significantly decreased in cervical cancer tissues compared with that in matched normal cervical tissues as well as in metastatic vs. non-metastatic cervical cancer tissues. miR-144 downregulation was significantly associated with the International Federation of Gynecology and Obstetrics stage and lymph node metastasis. In a gain-of function study, miR-144 mimics were transfected into the Hela and C33A cervical cancer cell lines, which led to suppression of cell growth. In addition, overexpression of miR-144 inhibited the migration and invasion of Hela and C33A cells. Furthermore, a bioinformatics analysis identified vascular endothelial growth factor A (VEGFA) VEGFC as two novel target genes of miR-144. Of note, a dual luciferase reporter assay, reverse-transcription quantitative polymerase chain reaction analysis and western blot analysis demonstrated that miR-144 repressed the expression of VEGFA and VEGFC by directly targeting to their 3'-untranslated region. Taken together, the results suggested that miR-144 acts as a tumor suppressor in the proliferation and metastasis of cervical cancer cells by directly targeting VEGFA and VEGFC, suggesting that miR-144 may be a novel promising diagnostic and therapeutic biomarker for cervical cancer.

MicroRNA-186 regulates the invasion and metastasis of bladder cancer via vascular endothelial growth factor C

The present study aimed to investigate the expression of microRNA (miRNA or miR)-186 in tumor tissue, blood and urine from patients with bladder cancer. The mechanism by which miR-186 regulates the invasion and metastasis of bladder cancer was also assessed. A total of 76 patients who underwent surgical resection of bladder cancer tissues between August 2012 and January 2016 were included in the present study. Blood and urine samples were also collected from the 76 patients and another 66 healthy subjects. Expression of vascular endothelial growth factor C (VEGF-C) mRNA and miR-186 was measured using reverse transcription-quantitative polymerase chain reaction. Western blot analysis was performed to assess VEGF-C protein expression in tumor tissues. The content of VEGF-C protein in blood and urine samples was measured using an enzyme-linked immunosorbent assay. To identify the direct interaction between miR-186 and VEGF-C mRNA, a dual luciferase reporter assay was performed. The present findings demonstrated that VEGF-C mRNA expression in tumor tissues, blood and urine of bladder cancer patients was upregulated. VEGF-C protein expression in bladder cancer tissues was also enhanced. VEGF-C protein content in blood and urine from bladder cancer patients was elevated, consistent with the results for VEGF-C mRNA. Expression of miR-186 was reduced in tumor tissues, blood and urine. Dual luciferase reporter assay demonstrated that miR-186 regulated the expression of VEGF-C by binding with its 3'-untranslated region. Therefore, the results of the present study indicate that the expression of VEGF-C mRNA and protein is upregulated in tumor tissues, blood and urine from patients with bladder cancer, while that of miR-186 is downregulated in these samples. miR-186 potentially regulates the invasion and metastasis of bladder cancer via VEGF-C, and may become a gene marker for bladder cancer in the future.

Associations between the expression of MTA1 and VEGF-C in esophageal squamous cell carcinoma with lymph angiogenesis and lymph node metastasis

The aim of the present study was to investigate the association between the expression levels of metastasis-related gene 1 (MTA1) and vascular endothelial growth factor C (VEGF-C) in esophageal squamous cell carcinoma (ESCC) with lymph angiogenesis and lymph node metastasis. The paraffin-embedded tissue samples of 107 cases of ESCC and 56 cases of normal esophageal tissues were collected from the Department of Cardiothoracic Surgery, Suining Central Hospital from March 2013 to January 2014. Immunohistochemical assays were performed to detect the expression levels of MTA1, VEGF-C and D2-40 in ESCC, and the micro-lymphatic vessel density (LVD) was evaluated. Their associations with various clinicopathological parameters were also analyzed. The protein expression levels of MTA1 and VEGF-C in ESCC were significantly higher compared with those in normal esophageal tissues (P<0.05); the high protein expression levels of MTA1 and VEGF-C in ESCC tissues at various tumor-node-metastasis stages exhibited statistically significant differences, as revealed by the Kruskal-Wallis test (P<0.05). The protein expression levels of MTA1 and VEGF-C in ESCC exhibited positive correlations (Spearman's ρ, r=0.512; P=0.000); the LVD level in the group with high expression of MTA1 and VEGF-C was significantly higher compared with in the low expression group (P<0.05). The comparison between MTA1 and VEGF-C protein expression levels in the group with a high rate of lymph node metastasis demonstrated statistically significant differences when compared with in the low lymph node metastasis group (P<0.05). The expression levels of MTA1 and VEGF-C in ESCC exhibited a positive correlation in ESCC, which may co-promote lymph angiogenesis and lymph node metastasis in ESCC; therefore, they may be used as biomarkers for determining the prognosis of ESCC.

Lymphatic System in Cardiovascular Medicine

The mammalian circulatory system comprises both the cardiovascular system and the lymphatic system. In contrast to the blood vascular circulation, the lymphatic system forms a unidirectional transit pathway from the extracellular space to the venous system. It actively regulates tissue fluid homeostasis, absorption of gastrointestinal lipids, and trafficking of antigen-presenting cells and lymphocytes to lymphoid organs and on to the systemic circulation. The cardinal manifestation of lymphatic malfunction is lymphedema. Recent research has implicated the lymphatic system in the pathogenesis of cardiovascular diseases including obesity and metabolic disease, dyslipidemia, inflammation, atherosclerosis, hypertension, and myocardial infarction. Here, we review the most recent advances in the field of lymphatic vascular biology, with a focus on cardiovascular disease.

Selective Stimulation of Cardiac Lymphangiogenesis Reduces Myocardial Edema and Fibrosis Leading to Improved Cardiac Function Following Myocardial Infarction

BACKGROUND

The lymphatic system regulates interstitial tissue fluid balance, and lymphatic malfunction causes edema. The heart has an extensive lymphatic network displaying a dynamic range of lymph flow in physiology. Myocardial edema occurs in many cardiovascular diseases, eg, myocardial infarction (MI) and chronic heart failure, suggesting that cardiac lymphatic transport may be insufficient in pathology. Here, we investigate in rats the impact of MI and subsequent chronic heart failure on the cardiac lymphatic network. Further, we evaluate for the first time the functional effects of selective therapeutic stimulation of cardiac lymphangiogenesis post-MI.

METHODS AND RESULTS

We investigated cardiac lymphatic structure and function in rats with MI induced by either temporary occlusion (n=160) or permanent ligation (n=100) of the left coronary artery. Although MI induced robust, intramyocardial capillary lymphangiogenesis, adverse remodeling of epicardial precollector and collector lymphatics occurred, leading to reduced cardiac lymphatic transport capacity. Consequently, myocardial edema persisted for several months post-MI, extending from the infarct to noninfarcted myocardium. Intramyocardial-targeted delivery of the vascular endothelial growth factor receptor 3-selective designer protein VEGF-CC152S, using albumin-alginate microparticles, accelerated cardiac lymphangiogenesis in a dose-dependent manner and limited precollector remodeling post-MI. As a result, myocardial fluid balance was improved, and cardiac inflammation, fibrosis, and dysfunction were attenuated.

CONCLUSIONS

We show that, despite the endogenous cardiac lymphangiogenic response post-MI, the remodeling and dysfunction of collecting ducts contribute to the development of chronic myocardial edema and inflammation-aggravating cardiac fibrosis and dysfunction. Moreover, our data reveal that therapeutic lymphangiogenesis may be a promising new approach for the treatment of cardiovascular diseases.

Fenofibrate inhibits the expression of VEGFC and VEGFR-3 in retinal pigmental epithelial cells exposed to hypoxia

The aim of the present study was to examine the mechanisms through which fenofibrate inhibits the ability of human retinal pigment epithelial cells (RPE cells) exposed to hypoxia to stimulate the proliferation and migration of human umbilical vein endothelial cells (HUVECs). For this purpose, RPE cells and HUVECs were divided into the following groups: RPE-normoxia, RPE + fenofibrate, RPE-hypoxia, RPE hypoxia + fenofibrate; HUVECs normal culture and HUVECs + RPE-hypoxia culture supernatant. RPE cell hypoxia was induced by cobalt(II) chloride (CoCl₂). A superoxide anion probe was used to measure the production of superoxide anion, which is indicative of hypoxic conditions. Cell proliferation was assessed by MTT assay, and the expression of vascular endothelial growth factor C (VEGFC) and vascular endothelial growth factor receptor-3 (VEGFR-3) in the RPE cell culture supernatant was measured by enzyme-linked immunosorbent assay (ELISA). The migration ability of the HUVECs was determined by scratch-wound assay, and the angiogenic ability of the HUVECs was examined by measuring cell lumen formation. The mRNA and protein expression levels of VEGFC and VEGFR-3 in the RPE cells were measured by RT-qPCR and western blot analysis, respectively. Our results revealed that fenofibrate inhibited the increase in the expression and release of VEGFC and VEGFR-3 into the RPE cell culture supernatant induced by exposure to hypoxia. The culture of HUVECs in medium supernatant of RPE cells epxosed to hypoxia enhanced the viability and migration ability of the HUVECs and promoted lumen formation; these effects were inhibited by fenofibrate. In conclusion, our data demonstrated that the exposure of RPE cells to hypoxia induced the expression and release of VEGFC and VEGFR-3 into the cell culture supernatant. The culture of HUVECs in conditioned medium from RPE cells exposed to hypoxia increased VEGFC and VEGFR-3 expression, and promoted the proliferation and migration of the HUVECs, as well as capillary tube formation, suggesting that RPE cells play an important role in the formation of choroidal neovascularization resulting from hypoxia. Fenofibrate inhibited the upregulation of VEGFC and VEGFR-3 in the RPE cells exposed to hypoxia, and thus reduced the ability of HUVECs to form new blood vessels.

Expression and clinical significance of microRNA-21, maspin and vascular endothelial growth factor-C in bladder cancer

The present study aimed to explore the expression and clinical significance of microRNA-21 (miR-21), maspin and vascular endothelial growth factor C (VEGF-C) in bladder cancer (BC). A total of 53 BC samples and 12 normal bladder tissue samples were collected. Total messenger RNA (mRNA) was extracted, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to evaluate the expression of miR-21 and maspin in BC and normal bladder tissues. Immunohistochemistry was used for the detection of maspin and VEGF-C protein expression. Furthermore, the correlations between these molecules and certain clinicopathological parameters were investigated, and survival analysis was performed to assess their prognostic significance. miR-21 mRNA expression and VEGF-C protein expression were increased in BC tissues compared with those in normal bladder tissues, whereas maspin mRNA and protein expression levels in BC tissues were significantly decreased (P<0.01). miR-21, maspin and VEGF-C expression were significantly associated with the stage, grade and lymph node metastasis of BC (P<0.05), but not the other clinicopathological features evaluated. There was a marked inverse correlation between the mRNA expression of miR-21 and maspin, with a coefficient of -0.978 (P<0.001). Similarly, there was a significant inverse correlation between the protein expression of maspin and VEGF-C, with a coefficient of -0.589 (P<0.001). Overexpression of miR-21 and VEGF-C, as well as decreased maspin expression, were associated with a poorer prognosis. These results suggested that upregulation of miR-21, decreased maspin expression and enhanced VEGF-C in BC may promote tumor progression. miR-21, maspin and VEGF-C may therefore have significant roles as biomarkers for prognosis and as therapeutic targets of BC.

High-mobility group box 1 protein activating nuclear factor-κB to upregulate vascular endothelial growth factor C is involved in lymphangiogenesis and lymphatic node metastasis in colon cancer

OBJECTIVES

To investigate the roles of high-mobility group box 1 (HMGB1) protein in lymphangiogenesis and lymphatic node metastasis in colon cancer.

METHODS

Archival tumour specimens from patients with colon cancer were analysed in this retrospective immunohistochemical study. HMGB1, vascular endothelial growth factor C (VEGF-C) and podoplanin protein levels were analysed immunohistochemically. In vitro studies using the colon cancer cell line HCT116 were also undertaken to investigate the relationship between HMGB1, VEGF-C and nuclear factor (NF)-κB.

RESULTS

Specimens from 70 patients with colon cancer were reviewed. The presence of positive HMGB1 immunohistochemical staining significantly correlated with lymphatic microvessel density, lymph node metastasis and VEGF-C immunohistochemical staining in colon cancer specimens. The presence of positive VEGF-C immunohistochemical staining significantly correlated with lymph node metastasis. The in vitro studies demonstrated that HMGB1 upregulated VEGF-C mRNA and protein in a dose-dependent manner in HCT116 cells, and that this was mediated via NF-κB.

CONCLUSIONS

HMGB1 immunohistochemical staining was significantly associated with lymphangiogenesis and lymphatic node metastasis in colon cancer. There was evidence that HMGB1 upregulates VEGF-C by activating NF-κB in a colon cancer cell line.

Calpastatin counteracts pathological angiogenesis by inhibiting suppressor of cytokine signaling 3 degradation in vascular endothelial cells

RATIONALE

Janus kinase/signal transducer and activator of transcription (JAK/STAT) signals and their endogenous inhibitor, suppressor of cytokine signaling 3 (SOCS3), in vascular endothelial cells (ECs) reportedly dominate the pathological angiogenesis. However, how these inflammatory signals are potentiated during pathological angiogenesis has not been fully elucidated. We suspected that an intracellular protease calpain, which composes the multifunctional proteolytic systems together with its endogenous inhibitor calpastatin (CAST), contributes to the JAK/STAT regulations.

OBJECTIVE

To specify the effect of EC calpain/CAST systems on JAK/STAT signals and their relationship with pathological angiogenesis.

METHODS AND RESULTS

The loss of CAST, which is ensured by several growth factor classes, was detectable in neovessels in murine allograft tumors, some human malignant tissues, and oxygen-induced retinopathy lesions in mice. EC-specific transgenic introduction of CAST caused downregulation of JAK/STAT signals, upregulation of SOCS3 expression, and depletion of vascular endothelial growth factor (VEGF)-C, thereby counteracting unstable pathological neovessels and disease progression in tumors and oxygen-induced retinopathy lesions in mice. Neutralizing antibody against VEGF-C ameliorated pathological angiogenesis in oxygen-induced retinopathy lesions. Small interfering RNA-based silencing of endogenous CAST in cultured ECs facilitated μ-calpain-induced proteolytic degradation of SOCS3, leading to VEGF-C production through amplified interleukin-6-driven STAT3 signals. Interleukin-6-induced angiogenic tube formation in cultured ECs was accelerated by CAST silencing, which is suppressible by pharmacological inhibition of JAK/STAT signals, antibody-based blockage of VEGF-C, and transfection of calpain-resistant SOCS3, whereas transfection of wild-type SOCS3 exhibited modest angiostatic effects.

CONCLUSIONS

Loss of CAST in angiogenic ECs facilitates μ-calpain-induced SOCS3 degradation, which amplifies pathological angiogenesis through interleukin-6/STAT3/VEGF-C axis.

Dickkopf-1 is a novel prognostic biomarker for laryngeal squamous cell carcinoma

CONCLUSIONS

Dickkopf-1 (DKK1) is a novel prognostic biomarker for laryngeal squamous cell carcinoma (LSCC). DKK1 may be a promising strategy for the future treatment of LSCC metastasis and recurrence.

OBJECTIVES

DKK1 is reportedly involved in the metastasis and invasion of several tumor types. This study aimed to investigate the prognostic value of DKK1 in LSCC.

METHODS

DKK1 expression was measured in Hep-2 cell lines, as well as in tumor and peritumoral tissues, using quantitative real-time PCR and western blot analyses. The role of DKK1 in LSCC was investigated by depleting DKK1 using small interfering RNAs. Tissue microarrays of 102 LSCC patient samples were employed to immunohistochemically detect expression of DKK1, vascular endothelial growth factor C (VEGF-C), and β-catenin. Prognostic significance was assessed using Kaplan-Meier survival estimates.

RESULTS

DKK1 expression was elevated in the Hep-2 cell line and tumor samples. DKK1 depletion decreased cell proliferation, migration, and invasiveness. High DKK1 expression was significantly associated with T and clinical stage, lymph node metastasis, and tumor size (p < 0.05). Increased DKK1 levels in LSCC tissues correlated with elevated VEGF-C and β-catenin. Multivariate analyses revealed that DKK1 was an unfavorable predictor of overall survival.

Role of VEGF-C gene polymorphisms in susceptibility to hepatocellular carcinoma and its pathological development

BACKGROUND

Vascular endothelial growth factor C (VEGF-C), an angiogenic/lymphangiogenic factor with high expression levels in tumor tissues, plays important roles in the development of several malignancies including hepatocellular carcinoma (HCC). The purpose of this study was to examine whether VEGF-C gene polymorphisms are associated with susceptibility to HCC and its clinicopathological development.

METHODS

Genetic polymorphisms of VEGF-C of 135 patients with HCC and 520 noncancer controls were analyzed by a real-time polymerase chain reaction (PCR).

RESULTS

We found that a significantly (P = 0.021) higher risk for HCC was shown in individuals with the VEGF-C rs1485766 A/A genotype compared to those with wild-type homozygotes; a high frequency of an advanced stage and a low frequency of being positive for cirrhosis were respectively shown in HCC patients with the VEGF-C rs7664413 CT/TT and rs3775194 GC/CC genotypes. Moreover, we found that the GGACA, GACTG, CGATG, and GGCTG haplotypes of five VEGF-C single-nucleotide polymorphisms (SNPs) combined were also related to the risk of HCC.

CONCLUSIONS

Our results suggest that the VEGF-C rs1485766 SNP and either of five haplotypes combined might contribute to a prediction of susceptibility to HCC. The genetic polymorphism of VEGF-C rs7664413 might be a predictive factor for advanced-stage HCC.

Therapeutic lymphangiogenesis with implantation of adipose-derived regenerative cells

Background

Lymphedema is one of the serious clinical problems that can occur after surgical resection of malignant tumors such as breast cancer or intra‐pelvic cancers. However, no effective treatment options exist at present. Here, we report that implantation of adipose‐derived regenerative cells (ADRCs) can induce lymphangiogenesis in a mouse model of reparative lymphedema.

Methods and Results

ADRCs were isolated from C57BL/6J mice. To examine the therapeutic efficacy of ADRC implantation in vivo, we established a new mouse model of tail lymphedema. Lymphedema was improved significantly by local injection of ADRCs (P<0.05). Histological analysis revealed that lymphatic capillary density was greater in the ADRC group than in the phosphate‐buffered saline control group (P<0.01). Tissue expression of vascular endothelial growth factor C mRNA and plasma levels of vascular endothelial growth factor C were greater in the ADRC group than in the control group (P<0.01 and P<0.05, respectively). ADRCs released vascular endothelial growth factor C, which directly stimulated lymphangiogenesis. Implantation of ADRCs also enhanced recruitment of bone marrow–derived M2 macrophages, which served as lymphatic endothelial progenitor cells.

Conclusions

Implantation of autologous ADRCs could be a useful treatment option for patients with severe lymphedema via mediation of lymphangiogenesis. (J Am Heart Assoc. 2012;1:e000877 doi: 10.1161/JAHA.112.000877.)