Role of M2-like macrophage recruitment during angiogenic growth factor therapy

Macrophage-mediated heart repair and remodeling: A promising therapeutic target for post-myocardial infarction heart failure

Heart failure (HF) remains prevalent in patients who survived myocardial infarction (MI). Despite the accessibility of the primary percutaneous coronary intervention and medications that alleviate ventricular remodeling with functional improvement, there is an urgent need for clinicians and basic scientists to further reveal the mechanisms behind post-MI HF as well as investigate earlier and more efficient treatment after MI. Growing numbers of studies have highlighted the crucial role of macrophages in cardiac repair and remodeling following MI, and timely intervention targeting the immune response via macrophages may represent a promising therapeutic avenue. Recently, technology such as single-cell sequencing has provided us with an updated and in-depth understanding of the role of macrophages in MI. Meanwhile, the development of biomaterials has made it possible for macrophage-targeted therapy. Thus, an overall and thorough understanding of the role of macrophages in post-MI HF and the current development status of macrophage-based therapy will assist in the further study and development of macrophage-targeted treatment for post-infarction cardiac remodeling. This review synthesizes the spatiotemporal dynamics, function, mechanism and signaling of macrophages in the process of HF after MI, as well as discusses the emerging bio-materials and possible therapeutic agents targeting macrophages for post-MI HF.

Unraveling and Harnessing the Immune Response at the Cell-Biomaterial Interface for Tissue Engineering Purposes

Biomaterials are defined as "engineered materials" and include a range of natural and synthetic products, designed for their introduction into and interaction with living tissues. Biomaterials are considered prominent tools in regenerative medicine that support the restoration of tissue defects and retain physiologic functionality. Although commonly used in the medical field, these constructs are inherently foreign toward the host and induce an immune response at the material-tissue interface, defined as the foreign body response (FBR). A strong connection between the foreign body response and tissue regeneration is suggested, in which an appropriate amount of immune response and macrophage polarization is necessary to trigger autologous tissue formation. Recent developments in this field have led to the characterization of immunomodulatory traits that optimizes bioactivity, the integration of biomaterials and determines the fate of tissue regeneration. This review addresses a variety of aspects that are involved in steering the inflammatory response, including immune cell interactions, physical characteristics, biochemical cues, and metabolomics. Harnessing the advancing knowledge of the FBR allows for the optimization of biomaterial-based implants, aiming to prevent damage of the implant, improve natural regeneration, and provide the tools for an efficient and successful in vivo implantation.

Lactate secreted by glycolytic conjunctival melanoma cells attracts and polarizes macrophages to drive angiogenesis in zebrafish xenografts

Conjunctival melanoma (CoM) is a rare but potentially lethal cancer of the eye, with limited therapeutic option for metastases. A better understanding how primary CoM disseminate to form metastases is urgently needed in order to develop novel therapies. Previous studies indicated that primary CoM tumors express Vascular Endothelial Growth Factor (VEGF) and may recruit pro-tumorigenic M2-like macrophages. However, due to a lack of proper models, the expected role of angiogenesis in the metastatic dissemination of CoM is still unknown. We show that cells derived from two CoM cell lines induce a strong angiogenic response when xenografted in zebrafish larvae. CoM cells are highly glycolytic and secrete lactate, which recruits and polarizes human and zebrafish macrophages towards a M2-like phenotype. These macrophages elevate the levels of proangiogenic factors such as VEGF, TGF-β, and IL-10 in the tumor microenvironment to induce an angiogenic response towards the engrafted CoM cells in vivo. Chemical ablation of zebrafish macrophages or inhibition of glycolysis in CoM cells terminates this response, suggesting that attraction of lactate-dependent macrophages into engrafted CoM cells drives angiogenesis and serves as a possible dissemination mechanism for glycolytic CoM cells.

Hydrogel-mediated extracellular vesicles for enhanced wound healing: the latest progress, and their prospects for 3D bioprinting

Extracellular vesicles have shown promising tissue recovery-promoting effects, making them increasingly sought-after for their therapeutic potential in wound treatment. However, traditional extracellular vesicle applications suffer from limitations such as rapid degradation and short maintenance during wound administration. To address these challenges, a growing body of research highlights the role of hydrogels as effective carriers for sustained extracellular vesicle release, thereby facilitating wound healing. The combination of extracellular vesicles with hydrogels and the development of 3D bioprinting create composite hydrogel systems boasting excellent mechanical properties and biological activity, presenting a novel approach to wound healing and skin dressing. This comprehensive review explores the remarkable mechanical properties of hydrogels, specifically suited for loading extracellular vesicles. We delve into the diverse sources of extracellular vesicles and hydrogels, analyzing their integration within composite hydrogel formulations for wound treatment. Different composite methods as well as 3D bioprinting, adapted to varying conditions and construction strategies, are examined for their roles in promoting wound healing. The results highlight the potential of extracellular vesicle-laden hydrogels as advanced therapeutic tools in the field of wound treatment, offering both mechanical support and bioactive functions. By providing an in-depth examination of the various roles that these composite hydrogels can play in wound healing, this review sheds light on the promising directions for further research and development. Finally, we address the challenges associated with the application of composite hydrogels, along with emerging trends of 3D bioprinting in this domain. The discussion covers issues such as scalability, regulatory considerations, and the translation of this technology into practical clinical settings. In conclusion, this review underlines the significant contributions of hydrogel-mediated extracellular vesicle therapy to the field of 3D bioprinting and wound healing and tissue regeneration. It serves as a valuable resource for researchers and practitioners alike, fostering a deeper understanding of the potential benefits, applications, and challenges involved in utilizing composite hydrogels for wound treatment.

Highly Bioactive MXene-M2-Exosome Nanocomposites Promote Angiogenic Diabetic Wound Repair through Reconstructing High Glucose-Derived Immune Inhibition

The repair of diabetic wounds remains challenging, primarily due to the high-glucose-derived immune inhibition which often leads to the excessive inflammatory response, impaired angiogenesis, and heightened susceptibility to infection. However, the means to reduce the immunosuppression and regulate the conversion of M2 phenotype macrophages under a high-glucose microenvironment using advanced biomaterials for diabetic wounds are not yet fully understood. Herein, we report two-dimensional carbide (MXene)-M2 macrophage exosome (Exo) nanohybrids (FM-Exo) for promoting diabetic wound repair by overcoming the high-glucose-derived immune inhibition. FM-Exo showed the sustained release of M2 macrophage-derived exosomes (M2-Exo) up to 7 days and exhibited broad-spectrum antibacterial activity. In the high-glucose microenvironment, relative to the single Exo, FM-Exo could significantly induce the optimized M2a/M2c polarization ratio of macrophages by activating the PI3K/Akt signaling pathway, promoting the proliferation, migration of fibroblasts, and angiogenic ability of endothelial cells. In the diabetic full-thickness wound model, FM-Exo effectively regulated the polarization status of macrophages and promoted their transition to the M2 phenotype, thereby inhibiting inflammation, promoting angiogenesis through VEGF secretion, and improving proper collagen deposition. As a result, the healing process was accelerated, leading to a better healing outcome with reduced scarring. Therefore, this study introduced a promising approach to address diabetic wounds by developing bioactive nanomaterials to regulate immune inhibition in a high-glucose environment.

Immunomodulatory effect of Ti-Cu alloy by surface nanostructure synergistic with Cu2+ release

The inflammatory response induced by implant/macrophage interaction has been considered to be one of the vital factors in determining the success of implantation. In this study, TiCuNxOy coating with an immunomodulatory strategy was proposed for the first time, using nanostructured TiCuNxOy coating synthesized on Ti-Cu alloy by oxygen and nitrogen plasma-based surface modification. It was found that TiCuNxOy coating inhibited macrophage proliferation but stimulated macrophage preferential activation and presented an elongated morphology due to the surface nanostructure. The most encouraging discovery was that TiCuNxOy coating promoted the initial pro-inflammatory response of macrophages and then accelerated the M1-to-M2 transition of macrophages via a synergistic effect of fast-to-slow Cu2+ release and surface nanostructure, which was considered to contribute to initial infection elimination and tissue healing. As expected, TiCuNxOy coating released desirable Cu2+ and generated a favorable immune response that facilitated HUVEC recruitment to the coating, and accelerated proliferation, VEGF secretion and NO production of HUVECs. On the other hand, it is satisfying that TiCuNxOy coating maintained perfect long-term antibacterial activity (≥99.9%), mainly relying on Cu2O/CuO contact sterilization. These results indicated that TiCuNxOy coating might offer novel insights into the creation of a surface with immunomodulatory effects and long-term bactericidal potential for cardiovascular applications.

The microRNA-4766/VEGFA axis mediates macrophage M2-type polarization to inhibit colorectal cancer proliferation and migration

OBJECTIVE

To investigate the miR-4766/VEGFA axis in regulating M2-type macrophage polarization under hypoxia and its effect on the proliferation and migration of colorectal cancer (CRC) cells.

METHODS

The differentially expressed genes (DEGs) in macrophages before and after hypoxia treatment in the dataset GSE154427 were analyzed. microRNA (miR)-4766 and VEGFA were selected as the research objects and then detected for mRNA expression and protein level using qRT-PCR and Western blot, respectively. The expression levels of M2 macrophage markers such as CD206, CD163, and ARG1 were detected to determine the M2-type macrophage polarization. The targeted binding of miR-4766 to VEGFA was verified using Dual-luciferase reporter gene assay. CCK-8 and Transwell assays were performed, respectively, to detect the capacity of cells to proliferate and migrate. IL-10 and TGF-β levels in the conditioned medium were detected using ELISA.

RESULTS

miR-4766 was upregulated, and VEGFA was downregulated in hypoxia-treated macrophages. miR-4766 inhibited, while VEGFA promoted the polarization of M2-type macrophages. miR-4766 targeted and negatively regulated VEGFA. miR-4766 inhibited the polarization of M2-type macrophages and then suppressed CRC cell proliferation and migration via targeting VEGFA.

CONCLUSION

Restoring miR-4766 expression to inhibit VEGFA expression promised to be a potential strategy to suppress CRC development.

Communications between macrophages and cardiomyocytes

The heart is a muscular organ that pumps blood throughout the body and is one of the most vital organs in human body. While cardiomyocytes are essential for maintaining the normal function of the heart, a variety of cardiovascular diseases such as coronary artery occlusion, arrhythmia, and myocarditis can lead to cardiomyocyte death, resulting in deterioration of heart function. The adult mammalian heart is incapable of regenerating sufficient cardiomyocytes following cardiac injuries, eventually leading to heart failure and death. Cardiac macrophages are ubiquitously distributed in the healthy heart and accumulated at the site of injury. Macrophages play essential roles in regulating homeostasis and proliferation of cardiomyocyte, promoting electrical conduction, and removing dead cardiomyocytes and debris through direct and indirect cell-cell crosstalk. In this review, we summarize the latest insights into the role of macrophages in maintaining cardiac homeostasis and the macrophage-cardiomyocyte crosstalk in both healthy and injured scenarios. Video Abstract.

A study of the correlation between stroke and gut microbiota over the last 20years: a bibliometric analysis

Purpose

This study intends to uncover a more thorough knowledge structure, research hotspots, and future trends in the field by presenting an overview of the relationship between stroke and gut microbiota in the past two decades.

Method

Studies on stroke and gut microbiota correlations published between 1st January 2002 and 31st December 2021 were retrieved from the Web of Science Core Collection and then visualized and scientometrically analyzed using CiteSpace V.

Results

A total of 660 papers were included in the study, among which the United States, the United Kingdom, and Germany were the leading research centers. Cleveland Clinic, Southern Medical University, and Chinese Academy of Science were the top three institutions. The NATURE was the most frequently co-cited journal. STANLEY L HAZEN was the most published author, and Tang WHW was the most cited one. The co-occurrence analysis revealed eight clusters (i.e., brain-gut microbiota axis, fecal microbiome transplantation, gut microbiota, hypertension, TMAO, ischemic stroke, neuroinflammation, atopobiosis). "gut microbiota," "Escherichia coli," "cardiovascular disease," "risk," "disease," "ischemic stroke," "stroke," "metabolism," "inflammation," and "phosphatidylcholine" were the most recent keyword explosions.

Conclusion

Findings suggest that in the next 10 years, the number of publications produced annually may increase significantly. Future research trends tend to concentrate on the mechanisms of stroke and gut microbiota, with the inflammation and immunological mechanisms, TMAO, and fecal transplantation as hotspots. And the relationship between these mechanisms and a particular cardiovascular illness may also be a future research trend.

Tumor Vasculature as an Emerging Pharmacological Target to Promote Anti-Tumor Immunity

Tumor vasculature abnormality creates a microenvironment that is not suitable for anti-tumor immune response and thereby induces resistance to immunotherapy. Remodeling of dysfunctional tumor blood vessels by anti-angiogenic approaches, known as vascular normalization, reshapes the tumor microenvironment toward an immune-favorable one and improves the effectiveness of immunotherapy. The tumor vasculature serves as a potential pharmacological target with the capacity of promoting an anti-tumor immune response. In this review, the molecular mechanisms involved in tumor vascular microenvironment-modulated immune reactions are summarized. In addition, the evidence of pre-clinical and clinical studies for the combined targeting of pro-angiogenic signaling and immune checkpoint molecules with therapeutic potential are highlighted. The heterogeneity of endothelial cells in tumors that regulate tissue-specific immune responses is also discussed. The crosstalk between tumor endothelial cells and immune cells in individual tissues is postulated to have a unique molecular signature and may be considered as a potential target for the development of new immunotherapeutic approaches.

BCR-Associated Protein 31 Regulates Macrophages Polarization and Wound Healing Function via Early Growth Response 2/C/EBPβ and IL-4Rα/C/EBPβ Pathways

The BCR-associated protein 31 (BAP31), a transmembrane protein in the endoplasmic reticulum, participates in the regulation of immune cells, such as microglia and T cells, and has potential functions in macrophages that remain to be unexplored. In this study, we designed and bred macrophage-specific BAP31 knockdown mice to detect the polarization and functions of macrophages. The results revealed that M2 macrophage-associated genes were suppressed in mouse bone marrow–derived macrophages of Lyz2 Cre-BAP31flox/flox mice. Multiple macrophage-associated transcription factors were demonstrated to be able to be regulated by BAP31. Among these factors, C/EBPβ was the most significantly decreased and was regulated by early growth response 2. BAP31 could also affect C/EBPβ via modulating IL-4Rα ubiquitination and proteasome degradation in IL-4–stimulated macrophages. Furthermore, we found that BAP31 affects macrophages functions, including angiogenesis and skin fibrosis, during the wound healing process through IL-4Rα, as confirmed by infection with adeno-associated virus–short hairpin (sh)-IL-4Rα in Lyz2 Cre-BAP31flox/flox mice. Our findings indicate a novel mechanism of BAP31 in regulating macrophages and provide potential solutions for the prevention and treatment of chronic wounds.

Mitochondrial-targeting antioxidant MitoQ modulates angiogenesis and promotes functional recovery after spinal cord injury

BACKGROUND

In traumatic spinal cord injury (SCI), secondary injuries, including vascular injury, cellular death, mitochondrial dysfunction, and vascular injury, have been considered as important causes of impaired functional recovery after SCI. Postinjury angiogenesis has been considered to be a potential strategy for SCI treatment. New-born vessels may play a key role in nerve regeneration, which indicates the importance of angiogenesis in nerve regeneration. Recent studies have revealed the crosstalk between reactive oxygen species (ROS) and angiogenesis. As the main source of cellular ROS, mitochondria have been proven to be essential to the angiogenesis process.

METHODS

SCI was established in a T10 clip-compression animal model. Then, the animals received an intraperitoneal injection of MitoQ (1 mg/ml) on Days 0, 1, and 2 after surgery. The Basso Mouse Scale (BMS) score and footprint analysis (CatWalk analysis) were performed to evaluate functional recovery after SCI. Immunofluorescence assay (LEL-FITC/CD31/Iba-1/Neurofilament) was performed to evaluate angiogenesis, microglia activation and neural regeneration. RT-qPCR (VEGFR-1, VEGFR-2 and VEGFA) was performed to evaluate angiogenesis-related factor in injured spinal cord. ATP production assay and western-blotting assay (Mfn-1 and Drp-1) were performed to evaluate mitochondrial function in the injured spinal cord. BV2 cells were used as in vitro cell models. After receiving TBHP or TBHP-MitoQ treatment, ELISA and immunofluorescence assays were used to evaluate the level of VEGFA secretion from BV2 cells. A coculture system of HUVECs and BV2 cells was established. Tube formation assays and immunofluorescence assays (CD31) were performed on HUVECs in a coculture system to evaluate angiogenesis promotion. ATP production assays were performed to evaluate mitochondrial function in BV2 cells. MitoSOX Red and DCFH-DA staining were performed to evaluate mitochondrial and cellular ROS.

RESULTS

In vitro MitoQ promoted the secretion of VEGFA from BV2 cells, which was verified through ELISA and immunofluorescence assays. The angiogenic promotion of MitoQ-treated BV2 cells was evaluated by tube formation and immunofluorescence assays (CD31) in a coculture system of BV2 cells and HUVECs. MitoQ inhibited cellular and mitochondrial-derived ROS in TBHP-treated BV2 cells. ATP production was increased in MitoQ-treated BV2 cells. To verify MitoQ's effect in vivo, a T10 clip-compression animal model was established successfully. MitoQ significantly promoted functional recovery, as shown by the BMS assay and gait analyser. The promotion of neural regeneration was identified through immunofluorescence assay of neurofilament. Immunofluorescence assay (LEL-FITC/CD31/Iba-1) and RT-qPCR (VEGFR-1, VEGFR-2 and VEGFA) indicated that MitoQ could promote angiogenesis and inhibit macrophage/microglia activation in lesion-site after SCI. Enhanced ATP production and increased Mfn-1 with decreased Drp-1 protein expression showed MitoQ could promote mitochondrial function in SCI.

CONCLUSION

The mitochondrial-specific antioxidant MitoQ promotes functional recovery and tissue preservation through the enhancement of angiogenesis with the modification of mitochondrial function after SCI.

Cellular Immune Signal Exchange From Ischemic Stroke to Intestinal Lesions Through Brain-Gut Axis

As a vital pivot for the human circulatory system, the brain-gut axis is now being considered as an important channel for many of the small immune molecules’ transductions, including interleukins, interferons, neurotransmitters, peptides, and the chemokines penetrating the mesentery and blood brain barrier (BBB) during the development of an ischemic stroke (IS). Hypoxia-ischemia contributes to pituitary and neurofunctional disorders by interfering with the molecular signal release and communication then providing feedback to the gut. Suffering from such a disease on a long-term basis may cause the peripheral system’s homeostasis to become imbalanced, and it can also lead to multiple intestinal complications such as gut microbiota dysbiosis (GMD), inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and even the tumorigenesis of colorectal carcinoma (CRC). Correspondingly, these complications will deteriorate the cerebral infarctions and, in patients suffering with IS, it can even ruin the brain’s immune system. This review summarized recent studies on abnormal immunological signal exchange mediated polarization subtype changes, in both macrophages and microglial cells as well as T-lymphocytes. How gut complications modulate the immune signal transduction from the brain are also elucidated and analyzed. The conclusions drawn in this review could provide guidance and novel strategies to benefit remedies for both IS and relative gut lesions from immune-prophylaxis and immunotherapy aspects.

Hexapeptide induces M2 macrophage polarization via the JAK1/STAT6 pathway to promote angiogenesis in bone repair

Angiogenesis is essential for successful bone defect repair. In normal tissue repair, the physiological inflammatory response is the main regulator of angiogenesis through the activity of macrophages and the cytokines secreted by them. In particular, M2 macrophages which secrete high levels of PDGF-BB are typically considered to promote angiogenesis. A hexapeptide [WKYMVm, (Trp-Lys-Tyr-Met-Val-D-Met-NH2)] has been reported to modulate inflammatory activities. However, the underlying mechanisms by which WKYMVm regulates macrophages remain unclear. In this study, the possible involvement by which WKYMVm induces the polarization of macrophages and affects their behaviors was evaluated. In vitro results showed that macrophages were induced to an M2 rather than M1 phenotype and the M2 phenotype was enhanced by WKYMVm through activation of the JAK1/STAT6 signaling pathway. It was also found that WKYMVm played an important role in the PDGF-BB production increase and proangiogenic abilities in M2 macrophages. Consistent with the results in vitro, the elevated M2/M0 ratio induced by WKYMVm enhanced the formation of new blood vessels in a femoral defect mouse model. These findings suggest that WKYMVm could be a promising alternative strategy for angiogenesis in bone repair by inducing M2 macrophage polarization.

Regulation of endothelial functionality through direct and immunomodulatory effects by Ni-Ti-O nanospindles on NiTi alloy

Stent implantation has become one of the most widely used methods for the treatment of cardiovascular diseases. However, endothelial dysfunction and abnormal inflammatory response following implantation may lead to delayed re-endothelialization, resulting in vascular restenosis and stent thrombus. To address the concerns, we constructed nanospindles composed of TiO₂ and Ti₄Ni₂O through hydrothermal treatment of amorphous Ni-Ti-O nanopores anodically grown on NiTi alloy. The results show the treatment can significantly improve hydrophilicity and reduce Ni ion release, essentially independent of hydrothermal duration. The nanospindle surfaces not only promote the expression of endothelial functionality but also activate macrophages to induce a favorable immune response, downregulate pro-inflammatory M1 markers and upregulate pro-healing M2 markers. Moreover, nitric oxide (NO) synthesis, VEGF secretion, and migration of endothelial cells are enhanced after cultured in macrophage conditioned medium. The nanospindles thus are promising as vascular stent coatings to promote re-endothelization.

The effect of hypoxia-mimicking responses on improving the regeneration of artificial vascular grafts

Cellular transition to hypoxia following tissue injury, has been shown to improve angiogenesis and regeneration in multiple tissues. To take advantage of this, many hypoxia-mimicking scaffolds have been prepared, yet the oxygen access state of implanted artificial small-diameter vascular grafts (SDVGs) has not been investigated. Therefore, the oxygen access state of electrospun PCL grafts implanted into rat abdominal arteries was assessed. The regions proximal to the lumen and abluminal surfaces of the graft walls were normoxic and only the interior of the graft walls was hypoxic. In light of this differential oxygen access state of the implanted grafts and the critical role of vascular regeneration on SDVG implantation success, we investigated whether modification of SDVGs with HIF-1α stabilizer dimethyloxalylglycine (DMOG) could achieve hypoxia-mimicking responses resulting in improving vascular regeneration throughout the entirety of the graft wall. Therefore, DMOG-loaded PCL grafts were fabricated by electrospinning, to support the sustained release of DMOG over two weeks. In vitro experiments indicated that DMOG-loaded PCL mats had significant biological advantages, including: promotion of human umbilical vein endothelial cells (HUVECs) proliferation, migration and production of pro-angiogenic factors; and the stimulation of M2 macrophage polarization, which in-turn promoted macrophage regulation of HUVECs migration and smooth muscle cells (SMCs) contractile phenotype. These beneficial effects were downstream of HIF-1α stabilization in HUVECs and macrophages in normoxic conditions. Our results indicated that DMOG-loaded PCL grafts improved endothelialization, contractile SMCs regeneration, vascularization and modulated the inflammatory reaction of grafts in abdominal artery replacement models, thus promoting vascular regeneration.

Prox1 induces new lymphatic vessel formation and promotes nerve reconstruction in a mouse model of sciatic nerve crush injury

The peripheral nervous system lacks lymphatic vessels and is protected by the blood–nerve barrier, which prevents lymphocytes and antibodies from entering the neural parenchyma. Peripheral nerve injury results in degeneration of the distal nerve and myelin degeneration causes macrophage aggregation, T lymphocyte infiltration, major histocompatibility complex class II antigen expression, and immunoglobulin G deposition in the nerve membrane, which together result in nerve edema and therefore affect nerve regeneration. In the present paper, we show myelin expression was absent from the sciatic nerve at 7 days after injury, and the expression levels of lymphatic vessel endothelial hyaluronan receptor 1 (LYVE‐1) and Prospero Homeobox 1 (Prox1) were significantly increased in the sciatic nerve at 7 days after injury. The lymphatic vessels were distributed around the myelin sheath and co‐localized with lymphatic endothelial cells. Prox1 induces the formation of new lymphatic vessels, which play important roles in the elimination of tissue edema as well as in morphological and functional restoration of the damaged nerve. This study provides evidence of the involvement of new lymphatic vessels in nerve repair after sciatic nerve injury.

Lymphatic and Immune Cell Cross-Talk Regulates Cardiac Recovery After Experimental Myocardial Infarction

Supplemental Digital Content is available in the text.

Objective:

Lymphatics play an essential pathophysiological role in promoting fluid and immune cell tissue clearance. Conversely, immune cells may influence lymphatic function and remodeling. Recently, cardiac lymphangiogenesis has been proposed as a therapeutic target to prevent heart failure after myocardial infarction (MI). We investigated the effects of gene therapy to modulate cardiac lymphangiogenesis post-MI in rodents. Second, we determined the impact of cardiac-infiltrating T cells on lymphatic remodeling in the heart.

Approach and Results:

Comparing adenoviral versus adeno-associated viral gene delivery in mice, we found that only sustained VEGF (vascular endothelial growth factor)-C_C156S therapy, achieved by adeno-associated viral vectors, increased cardiac lymphangiogenesis, and led to reduced cardiac inflammation and dysfunction by 3 weeks post-MI. Conversely, inhibition of VEGF-C/-D signaling, through adeno-associated viral delivery of soluble VEGFR3 (vascular endothelial growth factor receptor 3), limited infarct lymphangiogenesis. Unexpectedly, this treatment improved cardiac function post-MI in both mice and rats, linked to reduced infarct thinning due to acute suppression of T-cell infiltration. Finally, using pharmacological, genetic, and antibody-mediated prevention of cardiac T-cell recruitment in mice, we discovered that both CD4⁺ and CD8⁺ T cells potently suppress, in part through interferon-γ, cardiac lymphangiogenesis post-MI.

Conclusions:

We show that resolution of cardiac inflammation after MI may be accelerated by therapeutic lymphangiogenesis based on adeno-associated viral gene delivery of VEGF-C_C156S. Conversely, our work uncovers a major negative role of cardiac-recruited T cells on lymphatic remodeling. Our results give new insight into the interconnection between immune cells and lymphatics in orchestration of cardiac repair after injury.

Propranolol Attenuates Proangiogenic Activity of Mononuclear Phagocytes: Implication in Choroidal Neovascularization

Purpose

Targeting β-adrenergic receptor signaling with propranolol has emerged as a potential candidate to counteract choroidal neovascularization (CNV). Little is known of its effect on macrophages, which play a critical role in CNV. We investigated the effect of propranolol on angiogenic response of mononuclear phagocytes (MPs).

Methods

The angiogenic effect of propranolol was evaluated in laser-induced CNV model. Mice received intraperitoneal injections of propranolol (6 mg/kg/d) or vehicle. CNV area and inflammatory cells were determined respectively by using lectin staining and an anti-IBA-1 antibody on RPE/choroid flat mounts. Inflammatory gene expression was evaluated by quantitative (q) PCR analysis. Mechanisms of propranolol was studied in MP cell lines J774 and RAW264.7 and in primary peritoneal macrophages. Expression of pro- and antiangiogenic mediators was studied. In addition, effects of propranolol treatment of MPs was assessed on choroidal explant.

Results

CNV was attenuated by propranolol and concomitantly associated with decreased inflammatory mediators IL-6 and TNFα, albeit with accumulation of (β-adrenoceptor harboring) MPs in the CNV area. Conditioned media from MPs preincubated with propranolol exerted antiangiogenic effects. Treatment of J774 confirmed the attenuation of inflammatory response to propranolol and increased cleaved caspase-3 on choroidal explant. We found that propranolol increased pigment epithelium-derived factor (PEDF) expression in MPs. Trapping of PEDF with an antibody abrogated antiangiogenic effects of propranolol. PEDF was also detected in CNV-associated MPs.

Conclusions

We hereby show that propranolol confers on MPs antiangiogenic properties by increasing PEDF expression, which complements its effects on vascular tissue resulting in inhibition of choroidal vasoproliferation in inflammatory conditions. The study supports possible use of propranolol as a therapeutic modality for CNV.

A dual functional collagen scaffold coordinates angiogenesis and inflammation for diabetic wound healing

Chronic diabetic wounds, which are associated with persistent inflammation and impaired angiogenesis, occur frequently in diabetic patients.

Lebetin 2, a Snake Venom-Derived B-Type Natriuretic Peptide, Provides Immediate and Prolonged Protection against Myocardial Ischemia-Reperfusion Injury via Modulation of Post-Ischemic Inflammatory Response

Myocardial infarction (MI) followed by left ventricular (LV) remodeling is the most frequent cause of heart failure. Lebetin 2 (L2), a snake venom-derived natriuretic peptide, exerts cardioprotection during acute myocardial ischemia-reperfusion (IR) ex vivo. However, its effects on delayed consequences of IR injury, including post-MI inflammation and fibrosis have not been defined. Here, we determined whether a single L2 injection exerts cardioprotection in IR murine models in vivo, and whether inflammatory response to ischemic injury plays a role in L2-induced effects. We quantified infarct size (IS), fibrosis, inflammation, and both endothelial cell and cardiomyocyte densities in injured myocardium and compared these values with those induced by B-type natriuretic peptide (BNP). Both L2 and BNP reduced IS, fibrosis, and inflammatory response after IR, as evidenced by decreased leukocyte and proinflammatory M1 macrophage infiltrations in the infarcted area compared to untreated animals. However, only L2 increased anti-inflammatory M2-like macrophages. L2 also induced a higher density of endothelial cells and cardiomyocytes. Our data show that L2 has strong, acute, prolonged cardioprotective effects in post-MI that are mediated, at least in part, by the modulation of the post-ischemic inflammatory response and especially, by the enhancement of M2-like macrophages, thus reducing IR-induced necrotic and fibrotic effects.

Lymphatic system identification, pathophysiology and therapy in the cardiovascular diseases

The mammalian circulatory system comprises both the cardiovascular system and the lymphatic system. In contrast to the closed, high-pressure and circular blood vascular circulation, the lymphatic system forms an open, low-pressure and unidirectional transit network from the extracellular space to the venous system. It plays a key role in regulating tissue fluid homeostasis, absorption of gastrointestinal lipids, and immune surveillance throughout the body. Despite the critical physiological functions of the lymphatic system, a complete understanding of the lymphatic vessels lags far behind that of the blood vasculatures due to the challenge of their visualization. During the last 20 years, discoveries of underlying genes responsible for lymphatic vessel biology, combined with state-of-the-art lymphatic function imaging and quantification techniques, have established the importance of the lymphatic vasculature in the pathogenesis of cardiovascular diseases including lymphedema, obesity and metabolic diseases, dyslipidemia, hypertension, inflammation, atherosclerosis and myocardial infraction. In this review, we highlight the most recent advances in the field of lymphatic vessel biology, with an emphasis on the new identification techniques of lymphatic system, pathophysiological mechanisms of atherosclerosis and myocardial infarction, and new therapeutic perspectives of lymphangiogenesis.

Combination of metformin with sodium selenite induces a functional phenotypic switch of human GM-CSF monocyte-derived macrophages

OBJECTIVES

We evaluated the effects of metformin (Met, 1,1‑dimethylbiguanide hydrochloride) combined or not with sodium selenite (Ss, Na₂SeO₃) on the functional activities of LPS-activated GM-CSF monocyte-derived macrophages (GM-MDM).

MATERIALS AND METHODS

Human GM-MDMs from three healthy donors were treated with Met or Ss alone, or with the combination of Met and Ss, and assayed for various biological activities and cytokines expression.

RESULTS

Met alone and Ss alone had significantly different effects on phagocytosis and killing capacities and IL-β production, but had similar effects on the downregulation of inducible nitric oxide synthase (iNOS) activity, relative nicotinamide adenine dinucleotide reduced (NADH) dehydrogenase (Complex I), intracellular free calcium ions (_ifCa²⁺), and on the upregulation of arginase activity. Additionally, iNOS activity-to-arginase activity ratio was downregulated in Met or Ss treated-GM-MDMs, and, conversely, upregulated in GM-MDMs treated with Met + Ss in combination, indicating that arginase activity dominates that of iNOS when the two treatments are associated. Moreover, combination of Met with Ss significantly upregulated hydrogen peroxide (H₂O₂) production and phagocytic capacity, but significantly downregulated the production of IL-1β, iNOS activity and killing capacity. On the contrary, we show that Met alone induced significant downregulation of phagocytic capacity and slight upregulation of killing capacity. Nevertheless, Ss seems to accentuate the effect of Met on the downregulation of NO production, as well as to reverse its effect on both phagocytic and killing capacities. On the other hand, all treatments induced a sharp decrease in relative levels of NADH dehydrogenase, and a marked decrease in the levels of _ifCa²⁺. Finally, we found that GM-MDMs treated with Met or Ss, or Met combined with Ss exhibited different functional activation phenotypes, as indicated by the surface expression of co-stimulatory and cell activation and presentation molecules CD14, CD80, CD86 and HLA-DR.

CONCLUSIONS

Our results demonstrated that Met/Ss combination can play an important role in the modulation of functional activities of human LPS-activated GM-MDMs. Additionally, the overall effects of Met and the induction of "M2" GM-MDMs-associated arginase could be influenced by its combination with Ss.

Regulation of Type 2 Immunity in Myocardial Infarction

Type 2 immunity participates in the pathogeneses of helminth infection and allergic diseases. Emerging evidence indicates that the components of type 2 immunity are also involved in maintaining metabolic hemostasis and facilitating the healing process after tissue injury. Numerous preclinical studies have suggested regulation of type 2 immunity-related cytokines, such as interleukin-4, -13, and -33, and cell types, such as M2 macrophages, mast cells, and eosinophils, affects cardiac functions after myocardial infarction (MI), providing new insights into the importance of immune modulation in the infarcted heart. This review provides an overview of the functions of these cytokines and cells in the setting of MI as well as their potential to predict the severity and prognosis of MI.

Blockade of vascular endothelial growth factor receptor 2 inhibits intraplaque haemorrhage by normalization of plaque neovessels

BACKGROUND

Plaque angiogenesis is associated with atherosclerotic lesion growth, plaque instability and negative clinical outcome. Plaque angiogenesis is a natural occurring process to fulfil the increasing demand of oxygen and nourishment of the vessel wall. However, inadequate formed, immature plaque neovessels are leaky and cause intraplaque haemorrhage.

OBJECTIVE

Blockade of VEGFR2 normalizes the unbridled process of plaque neovessel formation and induces maturation of nascent vessels resulting in prevention of intraplaque haemorrhage and influx of inflammatory cells into the plaque and subsequently increases plaque stability.

METHODS AND RESULTS

In human carotid and vein graft atherosclerotic lesions, leaky plaque neovessels and intraplaque haemorrhage co-localize with VEGF/VEGFR2 and angiopoietins. Using hypercholesterolaemic ApoE3*Leiden mice that received a donor caval vein interposition in the carotid artery, we demonstrate that atherosclerotic vein graft lesions at t28 are associated with hypoxia, Hif1α and Sdf1 up-regulation. Local VEGF administration results in increased plaque angiogenesis. VEGFR2 blockade in this model results in a significant 44% decrease in intraplaque haemorrhage and 80% less extravasated erythrocytes compared to controls. VEGFR2 blockade in vivo results in a 32% of reduction in vein graft size and more stable lesions with significantly reduced macrophage content (30%), and increased collagen (54%) and smooth muscle cell content (123%). Significant decreased VEGF, angiopoietin-2 and increased Connexin 40 expression levels demonstrate increased plaque neovessel maturation in the vein grafts. VEGFR2 blockade in an aortic ring assay showed increased pericyte coverage of the capillary sprouts.

CONCLUSION

Inhibition of intraplaque haemorrhage by controlling neovessels maturation holds promise to improve plaque stability.

An In Vitro Model of Angiogenesis during Wound Healing Provides Insights into the Complex Role of Cells and Factors in the Inflammatory and Proliferation Phase

Successful vascularization is essential in wound healing, the histo-integration of biomaterials, and other aspects of regenerative medicine. We developed a functional in vitro assay to dissect the complex processes directing angiogenesis during wound healing, whereby vascular cell spheroids were induced to sprout in the presence of classically (M1) or alternatively (M2) activated macrophages. This simulated a microenvironment, in which sprouting cells were exposed to the inflammatory or proliferation phases of wound healing, respectively. We showed that M1 macrophages induced single-cell migration of endothelial cells and pericytes. In contrast, M2 macrophages augmented endothelial sprouting, suggesting that vascular cells infiltrate the wound bed during the inflammatory phase and extensive angiogenesis is initiated upon a switch to a predominance of M2. Interestingly, M1 and M2 shared a pro-angiogenic secretome, whereas pro-inflammatory cytokines were solely secreted by M1. These results suggested that acute inflammatory factors act as key inducers of vascular cell infiltration and as key negative regulators of angiogenesis, whereas pro-angiogenic factors are present throughout early wound healing. This points to inflammatory factors as key targets to modulate angiogenesis. The here-established wound healing assay represents a useful tool to investigate the effect of biomaterials and factors on angiogenesis during wound healing.

Protein tyrosine phosphatase 1B inactivation limits aging-associated heart failure in mice

We have previously shown that protein tyrosine phosphatase 1B (PTP1B) inactivation in mice [PTP1B-deficient (PTP1B−/−) mice] improves left ventricular (LV) angiogenesis, perfusion, remodeling, and function and limits endothelial dysfunction after myocardial infarction. However, whether PTP1B inactivation slows aging-associated cardiovascular dysfunction remains unknown. Wild-type (WT) and PTP1B−/− mice were allowed to age until 18 mo. Compared with old WT mice, in which aging increased the LV mRNA expression of PTP1B, old PTP1B−/− mice had 1) reduced cardiac hypertrophy with decreased LV mRNA levels of hypertrophic markers and atrial and brain natriuretic peptides, 2) lower LV fibrosis (collagen: 16 ± 3% in WT mice and 5 ± 3% in PTP1B−/− mice, P < 0.001) with decreased mRNA levels of transforming growth-factor-β1 and matrix metalloproteinase-2, and 3) higher LV capillary density and lower LV mRNA level of hypoxic inducible factor-1α, which was associated over time with a higher rate of proangiogenic M2 type macrophages and a stable LV mRNA level of VEGF receptor-2. Echocardiography revealed an age-dependent LV increase in end-diastolic volume in WT mice together with alterations of fractional shortening and diastole (transmitral Doppler E-to-A wave ratio). Invasive hemodynamics showed better LV systolic contractility and better diastolic compliance in old PTP1B−/− mice (LV end-systolic pressure-volume relation: 13.9 ± 0.9 in WT mice and 18.4 ± 1.6 in PTP1B−/− mice; LV end-diastolic pressure-volume relation: 5.1 ± 0.8 mmHg/relative volume unit in WT mice and 1.2 ± 0.3 mmHg/relative volume unit in PTP1B−/− mice, P < 0.05). In addition, old PTP1B−/− mice displayed a reduced amount of LV reactive oxygen species. Finally, in isolated resistance mesenteric arteries, PTP1B inactivation reduced aging-associated endothelial dysfunction (flow-mediated dilatation: −0.4 ± 2.1% in WT mice and 8.2 ± 2.8% in PTP1B−/− mice, P < 0.05). We conclude that PTP1B inactivation slows aging-associated LV remodeling and dysfunction and reduces endothelial dysfunction in mesenteric arteries.

NEW & NOTEWORTHY The present study shows that protein tyrosine phosphatase 1B inactivation in aged mice improves left ventricular systolic and diastolic function associated with reduced adverse cardiac remodeling (hypertrophy, fibrosis, and capillary rarefaction) and limits vascular endothelial dysfunction. This suggests that protein tyrosine phosphatase 1B inhibition could be an interesting treatment approach in age-related cardiovascular dysfunction.

CD11c+ M1-like macrophages (MΦs) but not CD206+ M2-like MΦ are involved in folliculogenesis in mice ovary

Macrophages (MΦs) are involved in folliculogenesis and ovulation. However, it is unknown which type of MΦ, M1 or M2, plays a more essential role in the ovary. CD206 or CD11c diphtheria toxin receptor transgenic (DTR) mice, which enable depletion of CD206+ M2 MΦs and CD11c+ MΦ or CD11c+ Dendritic cells (DCs), respectively, were used. Oocytes were used for in vitro fertilization and embryo transfer. In vitro fertilized embryos derived from M2 MΦ depleted oocytes were transferred to pseudo pregnant wild type mice. CD11c DTR mice were also used to investigate the role of CD11c cells, M1 MΦ and DCs in folliculogenesis. In WT mice, the proportion of CD206+ M2-like MΦs was not increased in follicular induction, while that of CD11c+ M1-like MΦs was increased. In CD206 DTR mice, folliculogenesis was normal and the ovulation number, fertilization rate, and implantation rate were similar to those in WT mice. In CD11c DTR mice, folliculogenesis was impaired with ovarian hemorrhage and the staining of platelet derived growth factor-receptor β (PDGF-Rβ), a marker of pericytes, and CD34, a marker of endothelial cells, was reduced. CD11c+ cells, M1 MΦs or DCs, may be involved in folliculogenesis, while M2 MΦs are not involved in folliculogenesis.

HDAC inhibition helps post-MI healing by modulating macrophage polarization

AIMS

Following an acute myocardial infarction (MI) the extracellular matrix (ECM) undergoes remodeling in order to prevent dilation of the infarct area and maintain cardiac output. Excessive and prolonged inflammation following an MI exacerbates adverse ventricular remodeling. Macrophages are an integral part of the inflammatory response that contribute to this remodeling. Treatment with histone deacetylase (HDAC) inhibitors preserves LV function and myocardial remodeling in the post-MI heart. This study tested whether inhibition of HDAC activity resulted in preserving post-MI LV function through the regulation of macrophage phenotype and early resolution of inflammation.

METHODS AND RESULTS

HDAC inhibition does not affect the recruitment of CD45⁺ leukocytes, CD45⁺/CD11b⁺ inflammatory monocytes or CD45⁺/CD11b⁺CD86⁺ inflammatory macrophages for the first 3 days following infarct. Further, HDAC inhibition does not change the high expression level of the inflammatory cytokines in the first days following MI. However, by day 7, there was a significant reduction in the levels of CD45⁺/Cd11b⁺ and CD45⁺/CD11b⁺/CD86⁺ cells with HDAC inhibition. Remarkably, HDAC inhibition resulted in the dramatic increase in the recruitment of CD45⁺/CD11b⁺/CD206⁺ alternatively activated macrophages as early as 1 day which remained significantly elevated until 5 days post-MI. qRT-PCR revealed that HDAC inhibitor treatment shifts the cytokine and chemokine environment towards an M2 phenotype with upregulation of M2 markers at 1 and 5 days post-MI. Importantly, HDAC inhibition correlates with significant preservation of both LV ejection fraction and end-diastolic volume and is associated with a significant increase in micro-vessel density in the border zone at 14 days post-MI.

CONCLUSION

Inhibition of HDAC activity result in the early recruitment of reparative CD45⁺/CD11b⁺/CD206⁺ macrophages in the post-MI heart and correlates with improved ventricular function and remodeling. This work identifies a very promising therapeutic opportunity to manage macrophage phenotype and enhance resolution of inflammation in the post-MI heart.

Adrenomedullin promotes the growth of pancreatic ductal adenocarcinoma through recruitment of myelomonocytic cells

Stromal infiltration of myelomonocytic cells is a hallmark of pancreatic ductal adenocarcinoma (PDAC) and is related to a poor prognosis. However, the detailed mechanism for the recruitment of myelomonocytic cells to pancreatic cancer tissue remains unclear. In the present study, pancreatic cancer cells secreted high levels of adrenomedullin (ADM), and CD11b⁺ myelomonocytic cells expressed all components of ADM receptors, including GPR182, CRLR, RAMP2 and RAMP3. ADM enhanced the migration and invasion of myelomonocytic cells through activation of the MAPK, PI3K/Akt and eNOS signaling pathways, as well as the expression and activity of MMP-2. ADM also promoted the adhesion and trans-endothelial migration of myelomonocytic cells by increasing expression of VCAM-1 and ICAM-1 in endothelial cells. In addition, ADM induced macrophages and myeloid-derived suppressor cells (MDSCs) to express pro-tumor phenotypes. ADM knockdown in tumor-bearing mice or administration of AMA, an ADM antagonist, significantly inhibited the recruitment of myelomonocytic cells and tumor angiogenesis. Moreover, in vivo depletion of myelomonocytic cells using clodronate liposomes suppressed the progression of PDAC. These results reveal a novel function of ADM in PDAC, and suggest ADM is a promising target in the treatment of PDAC.

IL-4 as a Repurposed Biological Drug for Myocardial Infarction through Augmentation of Reparative Cardiac Macrophages: Proof-of-Concept Data in Mice

Recent research has shown that reparative (alternatively activated or M2) macrophages play a role in repair of damaged tissues, including the infarcted hearts. Administration of IL-4 is known to augment M2 macrophages. This translational study thus aimed to investigate whether IL-4 administration is useful for the treatment of myocardial infarction. Long-acting IL-4 complex (IL-4c; recombinant IL-4 mixed with anti-IL-4 monoclonal antibody as a stabilizer) was administered after coronary artery ligation in mice. It was observed that IL-4c administration increased accumulation of CD206+F4/80+ M2-like macrophages predominantly in the injured myocardium, compared to the control. Sorted cardiac M2-like macrophages highly expressed wide-ranging tissue repair-related genes. Indeed, IL-4c administration enhanced cardiac function in association with reduced infarct size and enhanced tissue repair (strengthened connective tissue formation, improved microvascular formation and attenuated cardiomyocyte hypertrophy). Experiments using Trib1 -/- mice that had a depleted ability to develop M2 macrophages and other in-vitro studies supported that these IL-4-mediated effects were induced via M2-like macrophages. On the other hand, when administered at Day 28 post-MI, the effects of IL-4c were diminished, suggesting a time-frame for IL-4 treatment to be effective. These data represent proof-of-concept of efficacy of IL-4 treatment for acute myocardial infarction, encouraging its further development.

Nanoparticle-Based Magnetic Resonance Imaging on Tumor-Associated Macrophages and Inflammation

The inflammatory response, mediated by tissue-resident or newly recruited macrophages, is an underlying pathophysiological condition for many diseases, including diabetes, obesity, neurodegeneration, atherosclerosis, and cancer. Paradoxically, inflammation is a double-edged sword in oncology. Macrophages are, generally speaking, the major drivers of inflammatory insult. For many solid tumors, high density of cells expressing macrophage-associated markers have generally been found in association with a poor clinical outcome, characterized by inflamed microenvironment, a high level of dissemination and resistance to conventional chemotherapies. On another hand, radiation treatment also triggers an inflammatory response in tumors (often referred to as pseudoprogression), which can be associated with a positive treatment response. As such, non-invasive imaging of cancer inflammation and tumor-associated macrophages (TAMs) provides a revolutionary diagnostic tool and monitoring strategy for anti-inflammatory, immuno- and radiotherapies. Recently, quantitative T2-weighted magnetic resonance imaging (qT2wMRI), using injection of superparamagnetic iron oxide nanoparticles (SPIONs), has been reported for the assessment of TAMs non-invasively in animal models and in human trials. The SPIONs are magnetic resonance imaging (MRI) contrast agents that significantly decrease T2 MR relaxation times in inflamed tissues due to the macrophage-specific uptake and retention. It has been shown that macrophage-populated tumors and metastases will accumulate iron oxide nanoparticles and decrease T2-relaxation time that will result in a negative (dark) contrast in qT2wMRI. Non-invasive imaging of TAMs using SPION holds a great promise for staging the inflammatory microenvironment of primary and metastatic tumors as well monitoring the treatment response of cancer patients treated with radiation and immunotherapy.

Plaque angiogenesis and its relation to inflammation and atherosclerotic plaque destabilization

PURPOSE OF REVIEW

The review discusses the recent literature on plaque angiogenesis and its relation to inflammation and plaque destabilization. Furthermore, it discusses how plaque angiogenesis can be used to monitor atherosclerosis and serve as a therapeutic target.

RECENT FINDINGS

Histopathologic studies have shown a clear relationship between plaque angiogenesis, intraplaque hemorrhage (IPH), plaque vulnerability, and cardiovascular events. Hypoxia is a main driver of plaque angiogenesis and the mechanism behind angiogenesis is only partly known. IPH, as the result of immature neovessels, is associated with increased influx of inflammatory cells in the plaques. Experimental models displaying certain features of human atherosclerosis such as plaque angiogenesis or IPH are developed and can contribute to unraveling the mechanism behind plaque vulnerability. New imaging techniques are established, with which plaque angiogenesis and vulnerability can be detected. Furthermore, antiangiogenic therapies in atherosclerosis gain much attention.

SUMMARY

Plaque angiogenesis, IPH, and inflammation contribute to plaque vulnerability. Histopathologic and imaging studies together with specific experimental studies have provided insights in plaque angiogenesis and plaque vulnerability. However, more extensive knowledge on the underlying mechanism is required for establishing new therapies for patients at risk.

Antagonist antibodies to vascular endothelial growth factor receptor 2 (VEGFR-2) as anti-angiogenic agents

Interaction of numerous signaling pathways in endothelial and mesangial cells results in exquisite control of the process of physiological angiogenesis, with a central role played by vascular endothelial growth factor receptor 2 (VEGFR-2) and its cognate ligands. However, deregulated angiogenesis participates in numerous pathological processes. Excessive activation of VEGFR-2 has been found to mediate tissue-damaging vascular changes as well as the induction of blood vessel expansion to support the growth of solid tumors. Consequently, therapeutic intervention aimed at inhibiting the VEGFR-2 pathway has become a mainstay of treatment in cancer and retinal diseases. In this review, we introduce the concepts of physiological and pathological angiogenesis, the crucial role played by the VEGFR-2 pathway in these processes, and the various inhibitors of its activity that have entered the clinical practice. We primarily focus on the development of ramucirumab, the antagonist monoclonal antibody (mAb) that inhibits VEGFR-2 and has recently been approved for use in patients with gastric, colorectal, and lung cancers. We examine in-depth the pre-clinical studies using DC101, the mAb to mouse VEGFR-2, which provided a conceptual foundation for the role of VEGFR-2 in physiological and pathological angiogenesis. Finally, we discuss further clinical development of ramucirumab and the future of targeting the VEGF pathway for the treatment of cancer.

In situ expression of M2 macrophage subpopulation in leprosy skin lesions

The clinical manifestations of the leprosy depend on host immune response and the macrophages are the primary cells involved in this process. M1 and M2 cells exhibited distinct morphology, distinct surface marker profiles, as well as different cytokine and chemokine secretion. Macrophages express receptors such as CD163, CD68, CD206, and costimulatory molecules such as CD80 and CD86, and cytokines that trigger a suppressive or inflammatory response. Thirty-three untreated patients were selected, 17 patients had the tuberculoid leprosy (TT) and 16 had the lepromatous leprosy (LL). We performed immunohistochemistry to detect IL-13, IL-10, TGF-β, FGF-β, CD163, CD68, arginase 1. M2 macrophages showed significant differences between the groups studied with increase in the expression of costimulatory molecules (CD68 and CD163), arginase 1 and cytokines (IL-10, IL-13, TGF-β and FGF-b) in the LL form. Response of M2 macrophages emerge as an alternative for a better understanding of the innate immunity in the polar forms of leprosy, highlighting the role of cytokines, arginase 1 and costimulatory molecules in the repair and suppressive responses in the lepromatous form of the 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.