Matrix Stiffness of GelMA Hydrogels Regulates Lymphatic Endothelial Cells toward Enhanced Lymphangiogenesis.

Lymphatic vessel regeneration is crucial for various tissue engineering strategies, particularly in resolving inflammation and restoring tissue homeostasis. In our study, we focused on investigating how hydrogel matrix stiffness influences lymphatic endothelial cells (LECs) in promoting lymphatic vessel regeneration. Gelatin methacrylate (GelMA) was chosen as our biomaterial due to its versatility in tissue engineering and biofabrication. We fabricated GelMA hydrogels at concentrations of 5, 7.5, and 15% (w/v) with corresponding Young's modulus values of 1.55 kPa (soft matrix), 12.02 kPa (medium matrix), and 48.50 kPa (stiff matrix). Among these, the 7.5% GelMA hydrogel exhibited optimal stiffness for promoting lymphangiogenesis. LECs seeded either on the hydrogel surface or within spontaneously formed a more stable lymphatic capillary network compared with other GelMA formulations. Furthermore, we investigated the enhancement of lymphangiogenesis by incorporating VEGF-C into the GelMA hydrogel, leveraging the synergistic effects of mechanical and chemical cues. Our results underscored the critical role of FAK-phosphorylation in this process; treatment with an FAK-specific inhibitor prevented the formation of tube-like structures by LECs and attenuated the expression of lymphatic markers. Overall, our findings highlight how the mechanical and chemical cues provided by GelMA hydrogels can effectively regulate LEC behavior toward enhanced lymphangiogenesis via the integrin/FAK mechanotransduction pathway. This study proposes a promising strategy for developing hydrogel-based scaffolds or bioinks tailored to promote lymphatic vessel regeneration in therapeutic applications.

Regulatory Effects of SLC7A2-CPB2 on Lymphangiogenesis: A New Approach to Suppress Lymphatic Metastasis in HNSCC.

BACKGROUND: Lymph node metastasis (LNM) is a critical factor affecting the outcomes of head and neck squamous cell carcinoma (HNSCC) and the main reason for treatment failure. This study was designed to examine the effects of the key genes involved in the LNM of HNSCC. METHODS: Tissue samples (HNSCC) were examined by transcriptome sequencing, and the core genes associated with LNM were detected via bioinformatics analysis. The functions of these core genes were then validated using the TCGA biological database and their effects on the propagation, invasion, and metastasis of HNSCC cells were evaluated through cell culture experiments. Moreover, the effect of core gene expression on the LNM capability of HNSCC was confirmed via a footpad xenograft mice model. RESULTS: In the findings, a key gene involved in the LNM of HNSCC was identified as SLC7A2. It was correlated with adverse clinical prognosis and expressed with low expression in HNSCC tissues. As shown in cell culture experiments, FaDu and SCC15 cell growth, invasion, and migration were inhibited when SLC7A2 was overexpressed. Further, cell apoptosis was stimulated, and lymphangiogenesis was suppressed through the downregulation of CPB2 expression. Animal studies demonstrated that the growth and LNM of HNSCC cells were inhibited by SLC7A2 overexpression. CONCLUSION: It is concluded that SLC7A2 is involved in HNSCC lymphatic metastasis by controlling CPB2 function. The results are anticipated to offer new directions for the effective treatment of HNSCC.

Enhanced lymphangiogenesis in the left lateral segment of a biopsied liver during portoenterostomy for biliary atresia.

PURPOSE: We investigate the histopathology of the portal vein branches and lymphatic vessels to elucidate the mechanism of atrophy of the left lateral segment (LLS) of the liver in biliary atresia (BA). METHODS: LLS and right anterior segment (RAS) liver biopsy samples obtained during Kasai portoenterostomy (KPE) from ten consecutive patients with BA underwent histopathological investigation of the portal vein and lymphatic vessels using double chromogenic immunostaining for CD31/D2-40 and the hepatitis-like findings (HLF) score. Each parameter and clinical data were compared between prognostic groups. RESULTS: HLF scores in the LLS were always higher than those in the RAS. There was no difference in portal vein and lymphatic vascular morphology, whereas the number of lymphatic vessels was correlated with the fibrotic area of all specimen areas. Left-to-right ratio of the number of lymphatic vessels was correlated with the age at KPE (r = 0.784, p = 0.007) and the pre-KPE CRP value (r = 0.723, p = 0.018). CONCLUSIONS: Lymphangiogenesis on the LLS compared to the RAS was significantly correlated with the degree of fibrosis and the age at KPE. Further investigation is warranted to clarify the causes of LLS atrophy and lymphangiogenesis relevant to immune dysregulation.

Macrophage-derived VEGF-C reduces cardiac inflammation and prevents heart dysfunction in CVB3-induced viral myocarditis via remodeling cardiac lymphatic vessels.

BACKGROUND: Cardiac lymphatic vessels are important channels for cardiac fluid circulation and immune regulation. In myocardial infarction and chronic heart failure, promoting cardiac lymphangiogenesis is beneficial in reducing cardiac edema and inflammation. However, the specific involvement of cardiac lymphangiogenesis in viral myocarditis (VMC) has not been studied. Despite the recognized participation of macrophages in lymphangiogenesis, the contribution of macrophages to cardiac lymphangiogenesis in VMC is still unclear. METHODS: The male Balb/c mice with VMC were grouped according to the time to explore changes in inflammation, cardiac function and lymphangiogenesis. Adeno-associated virus (AAV) was used to determine the effect of cardiac lymphangiogenesis in VMC. Macrophage depletion and VEGF-CC156S treatment were used to investigate the connection between macrophages and cardiac lymphangiogenesis. RESULTS: Cardiac inflammation and lymphatic vessel density were both upregulated, peaking on day 7 following CVB3 infection. After treatment with AAV-sVEGFR3, lymphangiogenesis was inhibited, leading to worsened cardiac dysfunction and aggravated inflammation. However, these effects were reversed by AAV-VEGF-C treatment. Furthermore, macrophages infiltrated the inflamed myocardium and secreted VEGF-C. In vitro, VEGF-C was upregulated when RAW264.7 cells were co-cultured with CVB3. Macrophage depletion in mice with VMC inhibited lymphangiogenesis, while supplementation with VEGF-CC156S depressed it. CONCLUSION: Collectively, these results indicate that activation of the VEGF-C/VEGFR3 axis exerts a protective effect in CVB3-induced VMC by resolving inflammation and alleviating cardiac dysfunction through increased lymphatic vasculature density, with macrophage-derived VEGF-C partially contributing to this effect.

CEACAM1 increased the lymphangiogenesis through miR-423-5p and NF- kB in Non-Small Cell Lung Cancer.

Background: Lung cancer causes significant mortality, with invasion and metastasis being the main features that cause most cancer deaths. Lymph node metastasis is the primary metastatic route in non-small cell carcinoma (NSCLC) and influences the staging and prognosis of NSCLC. Cumulative studies have reported that Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is involved in the progression of various cancers. However, few studies have discussed the function of CEACAM1 in lymphangiogenesis in NSCLC. Here, we examined how CEACAM1 influences lymphangiogenesis in NSCLC. Methods: A total of 30 primary squamous cell carcinoma (LUSC) patients diagnosed with LN metastasis were prospectively selected. LUSC tumor tissues, para-cancerous tissues, and positive lymph node tissues were harvested. The expression and subcellular location of CEACAM1, CD31, and LVYE1 in clinical samples were detected by immunohistochemistry. Next, the CEACAM1 and hsa-miR-423-5p expressions were detected by qPCR. The protein expression of lymphangiogenesis-associated proteins and critical cytokines of the NF-κB pathway in HDLECs was detected by Western blot. A tube formation assay was performed to detect the lymphangiogenesis in different groups. The interaction between CEACAM1 and hsa-miR-423-5p was verified using a dual luciferase assay. Results: CEACAM1 was found to be a potential gene associated with lung cancer prognosis. It was positively correlated with angiogenesis and lymphangiogenesis. Then, we detected the function of CEACAM1 in lymphangiogenesis and found that CEACAM1 promoted lymphangiogenesis. hsa-miR-423-5p overexpression inhibited lymphangiogenesis via targeting CEACAM1. Finally, we observed that CEACAM1 can activate the NF-κB pathway and, therefore, promote lymphangiogenesis. Conclusion: We found that CEACAM1 enhanced lymphangiogenesis in NSCLC via NF-kB activation and was repressed by miR-423-5p. This suggests the value of CEACAM1 as a new therapeutic marker in NSCLC.

Gut microbiota-derived acetate promotes long-term recovery through angiogenesis guided by lymphatic ingrowth in older adults with stroke.

Introduction: Ischemic stroke is a leading cause of morbidity and mortality in older adults. Therefore, in this study, we sought to understand the interplay between the microbiota, gut, and brain in the context of stroke in older adults. Objective: To determine whether gut microbiota from younger individuals promotes recovery through angiogenesis in both elderly stroke patients and aged stroke mice, we explored the changes in gut microbiota and the correlation between short-chain fatty acids (SCFAs) and angiogenesis in the aged stroke population. Then, we altered the gut microbiome in aged mice by transplanting microbiota from younger donors before inducing experimental stroke to explore the mechanism by which gut microbiota-derived SCFAs promote angiogenesis. Methods: Part I: We conducted a single-center, double-blind trial to compare gut microbiota diversity and SCFA levels in fecal samples from older stroke patients with those from younger stroke patients. Additionally, we measured levels of vascular endothelial growth factor (VEGF) and VEGFC levels in plasma to assess their correlation with SCFA levels. Part II: We performed fecal microbiota transplantation (FMT) 3 days before inducing ischemic stroke in aged male mice (16-18) via distal middle cerebral artery occlusion (dMCAO). The FMT was conducted using gut microbiomes from either young donors (2-3 months) or aged donors (16-18 months). Results: In older stroke patients, gut microbiota diversity was significantly reduced compared to that in younger stroke patients. Furthermore, levels of acetate, a bacterially derived SCFA, were lower and positively correlated with angiogenesis markers (VEGF and VEGF-C). In aged stroke mice, transplantation of young microbiota improved stroke outcomes by promoting angiogenesis, which was facilitated by lymphatic ingrowth into the cortex. This protective effect was linked to gut microbiota-derived acetate, which enhanced lymphangiogenesis by replenishing acetyl coenzyme A. Conclusions: (a) Gut microbiota-derived acetate promotes angiogenesis post-stroke and (b) lymphatic ingrowth into the cerebral cortex was observed in post-dMCAO mice. These findings suggest that selectively promoting SCFA-producing bacteria, particularly acetate-producers, could be a promising therapeutic strategy to reduce functional impairments in older stroke subjects.

Lymphatic-specific methyltransferase-like 3-mediated m6A modification drives vascular patterning through prostaglandin metabolism reprogramming.

Lymphangiogenesis plays a pivotal role in the pathogenesis of various vascular disorders, including ocular vascular diseases and cancers. Deregulation of N 6-methyladenosine (m6A) modification has been identified as a key contributor to human diseases. However, the specific involvement of m6A modification in lymphatic remodeling remains poorly understood. In this study, we demonstrate that inflammatory stimulation and corneal sutures induce elevated levels of methyltransferase-like 3 (METTL3)-mediated m6A modification. METTL3 knockdown inhibits lymphatic endothelial viability, proliferation, migration, and tube formation in vitro. METTL3 knockdown attenuates corneal sutures-induced lymphangiogenesis and intratumoral lymphangiogenesis initiated by subcutaneous grafts, consequently restraining corneal neovascularization, tumor growth, and tumor neovascularization in vivo. Mechanistically, METTL3 knockdown upregulates prostaglandin-endoperoxide synthase 2 expression through an m6A-YTHDF2-dependent pathway, enhancing the synthesis of cyclopentenone prostaglandins (CyPGs). Aberrant CyPG production in lymphatic endothelial cells impairs mitochondrial oxidative phosphorylation, contributing to pathological lymphangiogenesis. Moreover, selective inhibition of METTL3 with STM2457 reduces m6A levels in lymphatic endothelial cells, effectively suppressing pathological lymphangiogenesis. This study provides compelling evidence that lymphatic-specific METTL3 plays a critical role in vascular patterning through prostaglandin metabolism reprogramming. Thus, METTL3 emerges as a promising target for treating lymphangiogenesis-related diseases.

Tumor-associated lymphatic vessel density is a reliable biomarker for prognosis of esophageal cancer after radical resection: a systemic review and meta-analysis.

Purpose: To explore whether tumor-associated lymphatic vessel density (LVD) could be a biomarker for the prognosis of patients with esophageal cancer after radical resection. Methods: A systematic literature search was performed through PubMed, EMBASE, Wanfang Data, and Cochrane Library from the inception of databases until March 19, 2024. The selected studies investigated overall survival (OS) and/or recurrence-free survival (RFS) of patients with esophageal cancer with different levels of LVD after radical resection. The OS and RFS data were pooled as hazard ratios (HR) and 95% confidential interval (CI). Furthermore, the standardized mean differences (SMDs) and 95% CI were aggregated to evaluate the correlation between LVD and clinicopathological features. Results: A total of 10 retrospective studies of 1,201 patients were finally included for the meta-analysis. Patients with esophageal cancer with a high level of LVD exhibited worse OS (HR 1.65, 95% CI 1.18 to 2.31) and RFS (HR 1.57, 95% CI 1.09 to 2.26) than those with a low level of LVD. Subgroup analysis of different pathological subtypes revealed that patients with esophageal adenocarcinoma with a high level of LVD had significantly worse RFS (HR 2.84, 95% CI 1.61 to 5.02) than those with a low level of LVD; while patients with esophageal squamous cell carcinoma with a high level of LVD had similar OS (HR 1.52, 95% CI 0.93 to 2.47) and RFS (HR 1.03, 95% CI 0.72 to 1.48) to those with a low level of LVD. Furthermore, tumors with lymph node metastasis had significantly higher levels of LVD than those without lymph node metastasis (SMD = 1.11, 95% CI 0.54 to 1.67). Tumors at the stages III-IV had significantly higher levels of LVD than those at the stages I-II (SMD = 1.62, 95% CI 0.90 to 2.34). Conclusion: A high level of LVD in tumor was associated with worse survival of patients with esophageal cancer after radical resection, especially in patients with esophageal adenocarcinoma. Tumor-associated LVD is a new parameter that should be measured in postoperative pathology for predicting the prognosis of patients with esophageal cancer. Systematic review registration: https://www.crd.york.ac.uk/prospero/ PROSPERO, identifier CRD42024553766.

Lymphangiogenesis: novel strategies to promote cutaneous wound healing.

The cutaneous lymphatic system regulates tissue inflammation, fluid balance and immunological responses. Lymphangiogenesis or lymphatic dysfunction may lead to lymphedema, immune deficiency, chronic inflammation etc. Tissue regeneration and healing depend on angiogenesis and lymphangiogenesis during wound healing. Tissue oedema and chronic inflammation can slow wound healing due to impaired lymphangiogenesis or lymphatic dysfunction. For example, impaired lymphangiogenesis or lymphatic dysfunction has been detected in nonhealing wounds such as diabetic ulcers, venous ulcers and bedsores. This review summarizes the structure and function of the cutaneous lymphatic vessel system and lymphangiogenesis in wounds. Furthermore, we review wound lymphangiogenesis processes and remodelling, especially the influence of the inflammatory phase. Finally, we outline how to control lymphangiogenesis to promote wound healing, assess the possibility of targeting lymphangiogenesis as a novel treatment strategy for chronic wounds and provide an analysis of the possible problems that need to be addressed.

An injectable thermosensitive hydrogel delivering M2 macrophage-derived exosomes alleviates osteoarthritis by promoting synovial lymphangiogenesis.

Osteoarthritis (OA) is a prevalent chronic degenerative disease affecting millions worldwide, with current treatment measures lacking efficacy in slowing disease progression. The synovial lymphatic system (SLS) has emerged as a crucial player in OA pathogenesis, with compromised drainage function contributing to disease advancement. Lymphatic endothelial cells (LECs) within the SLS are influenced by synovial macrophages, whose precise impact on LEC function remains unclear. Exosomes released by macrophages may serve as mediators of this interaction, with potential implications for OA progression. Here, we propose that polarized macrophages modulate LEC activity via exosome release in synovial tissue, with M2 macrophage-derived exosomes (M2Exo) promoting LEC proliferation, migration, and lymphangiogenesis, potentially offering a therapeutic avenue for OA. Moreover, we developed an injectable thermosensitive hydrogel with the characteristic of sustained release of M2Exo for alleviating OA. The hydrogel was prepared by dynamically linking hyaluronic acid (HA) and Pluronic F-127 and loading M2Exo, termed as M2Exo loaded HP hydrogel. The in vitro and in vivo experiments showed that M2Exo loaded HP hydrogel exhibits a controlled release profile of exosomes, thereby efficaciously fostering synovial lymphangiogenesis and enhancing synovial lymphatic drainage functionality under OA conditions, thus alleviating OA progression, and providing promising insights into OA therapeutic strategies. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) is a widespread degenerative disease with limited effective treatments to halt its progression. This research highlights the critical role of the synovial lymphatic system (SLS) in OA, focusing on how macrophage-derived exosomes influence lymphatic endothelial cell (LEC) function. We propose that M2 macrophage-derived exosomes (M2Exo) enhance LEC activity, promoting lymphangiogenesis, and offering a therapeutic approach for OA. Furthermore, we developed an injectable thermosensitive hydrogel (M2Exo loaded HP hydrogel) for sustained M2Exo release. Our in vitro and in vivo experiments demonstrate that this hydrogel supports synovial lymphangiogenesis and improves lymphatic drainage, effectively alleviating OA progression. This study presents significant advancements in OA therapy, offering new insights into its management.

Melatonin downregulates angiogenesis and lymphangiogenesis by regulating tumor-associated macrophages via NLRP3 inflammasomes in lung adenocarcinoma.

Tumor-associated macrophages (TAMs), present within the tumor microenvironment (TME), strictly modulate tumor angiogenesis and lymphangiogenesis. Nevertheless, the associated signaling networks and candidate drug targets for these events remains to be elucidated. Given its antioxidative activities, we speculated that melatonin may reduce pyroptosis, and thereby modulate both angiogenesis and lymphangiogenesis. We revealed that a co-culture of A549 cells and THP-1 macrophages strongly enhanced expressions of the NLRP3 inflammasome axis members, and augmented angiogenesis and lymphangiogenesis. Next, we overexpressed NLRP3 in the A549 cells, and demonstrated that excess NLRP3 expression substantially upregulated VEGF and CXCL cytokine expressions, and enhanced lymphatic endothelial cells (LECs) tube formation. In contrast, NLRP3 inhibition produced the opposite effect. In addition, relative to controls, melatonin administration strongly inhibited the NLRP3 inflammasome axis, as well as angiogenesis and lymphangiogenesis in the co-culture system. Subsequent animal experiments using a Lewis Lung Carcinoma (LLC) subcutaneous tumor model in mice corroborate these findings. Melatonin treatment and NLRP3 knockdown significantly inhibit tumor growth and downregulate NLRP3 and IL-1ß expression in tumor tissues. Furthermore, melatonin downregulates the expression of angiogenic and lymphangiogenic markers in tumor tissues. Taken together, the evidence suggested that a THP-1 macrophage and A549 cell co-culture stimulates angiogenesis and lymphangiogenesis via the NLRP3 axis. Melatonin protected against the TAMs- and NLRP3 axis-associated promotion of the aforementioned events in vitro and in vivo. Hence, melatonin is a promising candidate for managing for tumor-related angiogenesis and lymphangiogenesis in lung adenocarcinoma.

Anti-Inflammatory and Anti-(Lymph)angiogenic Properties of an ABCB5+ Limbal Mesenchymal Stem Cell Population.

Corneal transparency and avascularity are essential for vision. The avascular cornea transitions into the vascularized conjunctiva at the limbus. Here, we explore a limbal stromal cell sub-population that expresses ABCB5 and has mesenchymal stem cell characteristics. Human primary corneal stromal cells were enriched for ABCB5 by using FACS sorting. ABCB5+ cells expressed the MSC markers CD90, CD73, and CD105. ABCB5+ but not ABCB5- cells from the same donor displayed evidence of pluripotency with a significantly higher colony-forming efficiency and the ability of trilineage differentiation (osteogenic, adipogenic, and chondrogenic). The ABCB5+ cell secretome demonstrated lower levels of the pro-inflammatory protein MIF (macrophage migration inhibitory factor) as well as of the pro-(lymph)angiogenic growth factors VEGFA and VEGFC, which correlated with reduced proliferation of Jurkat cells co-cultured with ABCB5+ cells and decreased proliferation of blood and lymphatic endothelial cells cultured in ABCB5+ cell-conditioned media. These data support the hypothesis that ABCB5+ limbal stromal cells are a putative MSC population with potential anti-inflammatory and anti-(lymph)angiogenic effects. The therapeutic modulation of ABCB5+ limbal stromal cells may prevent cornea neovascularization and inflammation and, if transplanted to other sites in the body, provide similar protective properties to other tissues.

Acute Kidney Injury Results in Long-term Alterations of Kidney Lymphatics in Mice.

The long-term effects of a single episode of acute kidney injury (AKI) induced by bilateral ischemia-reperfusion injury (BIRI) on kidney lymphatic dynamics are not known. The purpose of this study was to determine if alterations in kidney lymphatics are sustained in the long-term and how they relate to inflammation and injury. Mice underwent BIRI as a model of AKI and were followed up to 9 months. While kidney function markers initially normalized, histological analysis revealed sustained tissue damage and inflammation for up to 9 months. Transcriptional analysis showed both acute and late-stage lymphangiogenesis, supported by increased expression of lymphatic markers, with unique signatures at each phase. Expression of Ccl21a was distinctly upregulated during late-stage lymphangiogenesis. Three-dimensional tissue cytometry confirmed increased lymphatic vessel abundance, particularly in the renal cortex, at early and late timepoints post-injury. Additionally, the study identified the formation of tertiary lymphoid structures composed of CCR7+ lymphocytes and observed changes in immune cell composition over time, suggesting a complex and dynamic response to AKI involving tissue remodeling and immune cell involvement. These studies provide new insights into the role of lymphatics in the progression of AKI to chronic kidney disease.

Activation of ß3-AR by mirabegron prevents aortic dissection/aneurysm by promoting lymphangiogenesis in perivascular adipose tissue.

AIMS: ß3-AR (ß3-adrenergic receptor) is essential for cardiovascular homeostasis through regulating adipose tissue function. Perivascular adipose tissue (PVAT) has been implicated in the pathogenesis of aortic dissection and aneurysm (AD/AA). Here, we aim to investigate ß3-AR activation-mediated PVAT function in AD/AA. METHODS AND RESULTS: Aortas from patients with thoracic aortic dissection (TAD) were collected to detect ß3-AR expression in PVAT. ApoE-/- and ß-aminopropionitrile monofumarate (BAPN)-treated C57BL/6 mice were induced with Angiotensin II (AngII) to simulate AD/AA, and subsequently received either placebo or mirabegron, a ß3-AR agonist. The results demonstrated an up-regulation of ß3-AR in PVAT of TAD patients and AD/AA mice. Moreover, activation of ß3-AR by mirabegron significantly prevented AngII-induced AD/AA formation in mice. RNA-sequencing analysis of adipocytes from PVAT revealed a notable increase of the lymphangiogenic factor VEGF-C in mirabegron-treated mice. Consistently, enhanced lymphangiogenesis was found in PVAT with mirabegron treatment. Mechanistically, the number of CD4+/CD8+ T cells and CD11c+ cells was reduced in PVAT but increased in adjacent draining lymph nodes (LNs) of mirabegron-treated mice, indicating the improved draining and clearance of inflammatory cells in PVAT by lymphangiogenesis. Importantly, adipocyte-specific VEGF-C knockdown by the adeno-associated virus system restrained lymphangiogenesis and exacerbated inflammatory cell infiltration in PVAT, which ultimately abolished the protection of mirabegron on AD/AA. In addition, the conditional medium derived from mirabegron-treated adipocytes activated the proliferation and tube formation of lymphatic endothelial cells (LECs), which was abrogated by the silencing of VEGF-C in adipocytes. CONCLUSIONS: Our findings illustrated the therapeutic potential of ß3-AR activation by mirabegron on AD/AA, which promoted lymphangiogenesis by increasing adipocyte-derived VEGF-C and, therefore, ameliorated PVAT inflammation.

LNMAC Promotes Cervical Squamous Cell Carcinoma Lymphatic Metastasis via Epigenetic Regulation of FGF2-Induced Lymphangiogenesis.

The lymph node is the most common site of distant metastasis of cervical squamous cell carcinoma (CSCC), which elicits dismal prognosis and limited efficiency for treatment. Elucidation of the mechanisms underlying CSCC lymphatic metastasis would provide potential therapeutic strategies for nodal metastatic of CSCC. Here, based on in vivo lymphatic metastasis screening model, a circular RNA is identified that is termed as lymph node metastasis associated circRNA (LNMAC), is markedly upregulated in lymphatic metastatic CSCC and correlated with lymph node metastasis. Overexpression of LNMAC dramatically augments the metastatic capability of CSCC cells to the lymph node via inducing lymphangiogenesis. Mechanistically, LNMAC epigenetically upregulates fibroblast growth factor 2 (FGF2) expression by directly associating with histone acacetylase 1 (HDAC1), preventing Importin α6/8-mediated nuclear translocation of HDAC1 and eliciting histone H3K27ac-induced FGF2 transcriptional activation. Treatment with 3F12E7, an anti-FGF2 monoclonal antibody, effectively inhibits LNMAC-induced CSCC lymphatic metastasis. Taken together, these findings indicate that LNMAC plays a crucial role in FGF2-mediated lymphangiogenesis and lymphatic metastasis, highlighting that LNMAC might be a therapeutic target for lymph node metastasis in CSCC patients.

The emerging importance of lymphangiogenesis in aging and aging-associated diseases.

Lymphatic aging represented by cellular and functional changes, is involved in increased geriatric disorders, but the intersection between aging and lymphatic modulation is less clear. Lymphatic vessels play an essential role in maintaining tissue fluid homeostasis, regulating immune function, and promoting macromolecular transport. Lymphangiogenesis and lymphatic remodeling following cellular senescence and organ deterioration are crosslinked with the progression of some lymphatic-associated diseases, e.g., atherosclerosis, inflammation, lymphoedema, and cancer. Age-related detrimental tissue changes may occur in lymphatic vessels with diverse etiologies, and gradually shift towards chronic low-grade inflammation, so-called inflammaging, and lead to decreased immune response. The investigation of the relationship between advanced age and organ deterioration is becoming an area of rapidly increasing significance in lymphatic biology and medicine. Here we highlight the emerging importance of lymphangiogenesis and lymphatic remodeling in the regulation of aging-related pathological processes, which will help to find new avenues for effective intervention to promote healthy aging.

Mechanisms of lymph node metastasis: An extracellular vesicle perspective.

In several solid tumors such as breast cancer, prostate cancer, colorectal cancer or melanoma, tumor draining lymph nodes are the earliest tissues where colonization by tumor cells is detected. Lymph nodes act as sentinels of metastatic dissemination, the deadliest phase of tumor progression. Besides hematogenous dissemination, lymphatic spread of tumor cells has been demonstrated, adding more complexity to the mechanisms involved in metastasis. A network of blood and lymphatic vessels surrounds tumors providing routes for tumor soluble factors to mediate regional and long-distance effects. Additionally, extracellular vesicles (EVs), particularly small EVs/exosomes, have been shown to circulate through the blood and lymph, favoring the formation of pre-metastatic niches in the tumor-draining lymph nodes (TDLNs) and distant organs. In this review, we present an overview of the relevance of lymph node metastasis, the structural and immune changes occurring in TDLNs during tumor progression, and how extracellular vesicles contribute to modulating some of these alterations while promoting the formation of lymph node pre-metastatic niches.

Podoplanin and its multifaceted roles in mammalian developmental program.

Podoplanin is a vital molecule which plays an integral part in the regulation of development, immunity, and cancer. Expression of Podoplanin is detected at different early developmental stages of mammalian embryo, and it functions to modulate morphogenesis of various organ systems. In experimental animal models of different genetic backgrounds, absence of Podoplanin results in either embryonic lethality or immediate death upon birth, suggesting the importance of the gene in early developmental processes. This review discusses the gene and protein structure of Podoplanin; and elucidates various functions of Podoplanin in different systems, including central nervous system as well as respiratory, lymphatic, and cardiovascular systems.

Lymphangiogenesis in the liver of biliary atresia.

BACKGROUND: Lymphatic vessels (LVs) play a crucial role in immune reactions by serving as the principal conduits for immune cells. However, to date, no study has analyzed the morphological changes in the LVs of patients with biliary atresia (BA). In this study, we aimed to determine the morphological changes in the LVs irrigating the liver in patients with BA, elucidate their correlations with the morphology of the portal vein (PV) branches, and discuss their etiopathogenetic significance. METHODS: Morphometric analyses of liver biopsy specimens from patients treated between 1986 and 2016 were performed. The parameters measured were as follows: the whole liver area of the specimen, fibrotic area, number of LVs, LVs without patent lumen (designated as Ly0) and PV branches, and diameters of the LVs with patent lumen and the PVs. RESULTS: The numbers of LVs, Ly0, and PV branches per unit area of the whole liver specimen were significantly higher in patients with BA than in control participants with liver disease and those with normal livers. However, no correlation was observed between the fibrotic area and the average diameter of LVs or PVs, and between the fibrotic area and the number of LVs or PV branches. Furthermore, no correlation was observed between the total number of LVs and the number of PV branches. CONCLUSIONS: The present study showed a significant increase in the number of total LVs and Ly0, characterized by a high Ly0 to total LVs ratio, suggesting that lymphangiogenesis occurs in the liver of patients with BA.

Unlocking potential of oxytocin: improving intracranial lymphatic drainage for Alzheimer's disease treatment.

Background: The impediment to ß-amyloid (Aß) clearance caused by the invalid intracranial lymphatic drainage in Alzheimer's disease is pivotal to its pathogenesis, and finding reliable clinical available solutions to address this challenge remains elusive. Methods: The potential role and underlying mechanisms of intranasal oxytocin administration, an approved clinical intervention, in improving intracranial lymphatic drainage in middle-old-aged APP/PS1 mice were investigated by live mouse imaging, ASL/CEST-MRI scanning, in vivo two-photon imaging, immunofluorescence staining, ELISA, RT-qPCR, Western blotting, RNA-seq analysis, and cognitive behavioral tests. Results: Benefiting from multifaceted modulation of cerebral hemodynamics, aquaporin-4 polarization, meningeal lymphangiogenesis and transcriptional profiles, oxytocin administration normalized the structure and function of both the glymphatic and meningeal lymphatic systems severely impaired in middle-old-aged APP/PS1 mice. Consequently, this intervention facilitated the efficient drainage of Aß from the brain parenchyma to the cerebrospinal fluid and then to the deep cervical lymph nodes for efficient clearance, as well as improvements in cognitive deficits. Conclusion: This work broadens the underlying neuroprotective mechanisms and clinical applications of oxytocin medication, showcasing its promising therapeutic prospects in central nervous system diseases with intracranial lymphatic dysfunction.