Fibroblast activation in vascular inflammation

Bacteriophage-cocktail hydrogel dressing to prevent multiple bacterial infections and heal diabetic ulcers in mice

Bacteriophage (phage) has been reported to reduce the bacterial infection in delayed-healing wounds and, as a result, aiding in the healing of said wounds. In this study we investigated whether the presence of phage itself could help repair delayed-healing wounds in diabetic mice. Three strains of phage that target Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa were used. To prevent the phage liquid from running off the wound, the mixture of phage (phage-cocktail) was encapsulated in a porous hydrogel dressing made with three-dimensional printing. The phage-cocktail dressing was tested for its phage preservation and release efficacy, bacterial reduction, cytotoxicity with 3T3 fibroblast, and performance in repairing a sterile full-thickness skin wound in diabetic mice. The phage-cocktail dressing released 1.7%-5.7% of the phages embedded in 24 h, and reduced between 37%-79% of the surface bacteria compared with the blank dressing (p <.05). The phage-cocktail dressing exhibited no sign of cytotoxicity after 3 days (p <.05). In vivo studies showed that 14 days after incision, the full-thickness wound treated with a phage-cocktail dressing had a higher wound healing ratio compared with the blank dressing and control (p <.01). Histological analysis showed that the structure of the skin layers in the group treated with phage-cocktail dressing was restored in an orderly fashion. Compared with the blank dressing and control, the repaired tissue in the phage-cocktail dressing group had new capillary vessels and no sign of inflammation in its dermis, and its epidermis had a higher degree of re-epithelialization (p <.05). The slow-released phage has demonstrated positive effects in repairing diabetic skin wounds.

A Co-Culture System for Studying Cellular Interactions in Vascular Disease

Cardiovascular diseases (CVDs) are leading causes of morbidity and mortality globally, characterized by complications such as heart failure, atherosclerosis, and coronary artery disease. The vascular endothelium, forming the inner lining of blood vessels, plays a pivotal role in maintaining vascular homeostasis. The dysfunction of endothelial cells contributes significantly to the progression of CVDs, particularly through impaired cellular communication and paracrine signaling with other cell types, such as smooth muscle cells and macrophages. In recent years, co-culture systems have emerged as advanced in vitro models for investigating these interactions and mimicking the pathological environment of CVDs. This review provides an in-depth analysis of co-culture models that explore endothelial cell dysfunction and the role of cellular interactions in the development of vascular diseases. It summarizes recent advancements in multicellular co-culture models, their physiological and therapeutic relevance, and the insights they provide into the molecular mechanisms underlying CVDs. Additionally, we evaluate the advantages and limitations of these models, offering perspectives on how they can be utilized for the development of novel therapeutic strategies and drug testing in cardiovascular research.

Decoding the impact of ageing and environment stressors on skin cell communication

The integumentary system serves as a crucial protective barrier and is subject to complex signaling pathways that regulate its physiological functions. As the body's first line of defense, the skin is continuously exposed to environmental stressors, necessitating a robust network of signaling molecules to maintain homeostasis. Considering the main cellular components to be keratinocytes, melanocytes, fibroblasts, and fibrous components, collagen of various types, this review explores the intricate signaling mechanisms that govern skin integrity, focusing on key pathways involved in impacts of ageing and environment factors on skin health. The role of growth factors, cytokines, hormones and other molecular mediators in these processes is examined. Specially for women, decrease of estrogen is determinant to alter signaling and to compromise skin structure, especially the dermis. Environmental factors, such as ultraviolet rays and pollution alongside the impact of ageing on signaling pathways, especially TGF-β and proteases (metalloproteinases and cathepsins). Furthermore, with advancing age, the skin's capacity to shelter microbiome challenges diminishes, leading to alterations in signal transduction and subsequent functional decline. Understanding these age-related changes is essential for developing targeted therapies aimed at enhancing skin health and resilience, but also offers a promising avenue for the treatment of skin disorders and the promotion of healthy ageing.

CAFs vs. TECs: when blood feuds fuel cancer progression, dissemination and therapeutic resistance

Neoplastic progression involves complex interactions between cancer cells and the surrounding stromal milieu, fostering microenvironments that crucially drive tumor progression and dissemination. Of these stromal constituents, cancer-associated fibroblasts (CAFs) emerge as predominant inhabitants within the tumor microenvironment (TME), actively shaping multiple facets of tumorigenesis, including cancer cell proliferation, invasiveness, and immune evasion. Notably, CAFs also orchestrate the production of pro-angiogenic factors, fueling neovascularization to sustain the metabolic demands of proliferating cancer cells. Moreover, CAFs may also directly or indirectly affect endothelial cell behavior and vascular architecture, which may impact in tumor progression and responses to anti-cancer interventions. Conversely, tumor endothelial cells (TECs) exhibit a corrupted state that has been shown to affect cancer cell growth and inflammation. Both CAFs and TECs are emerging as pivotal regulators of the TME, engaging in multifaceted biological processes that significantly impact cancer progression, dissemination, and therapeutic responses. Yet, the intricate interplay between these stromal components and the orchestrated functions of each cell type remains incompletely elucidated. In this review, we summarize the current understanding of the dynamic interrelationships between CAFs and TECs, discussing the challenges and prospects for leveraging their interactions towards therapeutic advancements in cancer.

Tissue fibroblasts are versatile immune regulators: An evaluation of their impact on the aging process

Fibroblasts are abundant stromal cells which not only control the integrity of extracellular matrix (ECM) but also act as immune regulators. It is known that the structural cells within tissues can establish an organ-specific immunity expressing many immune-related genes and closely interact with immune cells. In fact, fibroblasts can modify their immune properties to display both pro-inflammatory and immunosuppressive activities in a context-dependent manner. After acute insults, fibroblasts promote tissue inflammation although they concurrently recruit immunosuppressive cells to enhance the resolution of inflammation. In chronic pathological states, tissue fibroblasts, especially senescent fibroblasts, can display many pro-inflammatory and immunosuppressive properties and stimulate the activities of different immunosuppressive cells. In return, immunosuppressive cells, such as M2 macrophages and myeloid-derived suppressor cells (MDSC), evoke an excessive conversion of fibroblasts into myofibroblasts, thus aggravating the severity of tissue fibrosis. Single-cell transcriptome studies on fibroblasts isolated from aged tissues have confirmed that tissue fibroblasts express many genes coding for cytokines, chemokines, and complement factors, whereas they lose some fibrogenic properties. The versatile immune properties of fibroblasts and their close cooperation with immune cells indicate that tissue fibroblasts have a crucial role in the aging process and age-related diseases.

Investigating the role of TGF-β and BDNF in cancer-related depression: a primary cross-sectional study

BACKGROUND

Cancer-related depression is a well-documented condition that significantly impacts long-term quality of life. Brain-derived neurotrophic factor (BDNF), a neurotrophin essential for neurogenesis and neuronal plasticity, has been implicated in various neuropsychological disorders including depression associated with cancer. Cytokines, on the other hand, play a crucial role in regulating depression, potentially by influencing BDNF expression. Transforming growth factor-β (TGF-β), a key immune regulator within the tumor microenvironment, has been found to elevate BDNF levels, establishing a link between peripheral immune responses and depression. The study aims to investigate the correlation of TGF-β and BDNF in cancer-related depression.

METHODS

This study involved a cohort of 153 gynecological patients, including 61 patients with gynecological cancer and 92 patients without cancer. Depression levels were assessed using the subscale of Hospital Anxiety and Depression Scale (HADS-D), and TGF-β and BDNF plasma levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The study revealed elevated plasma TGF-β levels in patients with cancer (32.24 ± 22.93 ng/ml) compared to those without cancer (25.24 ± 19.72 ng/ml) (P = 0.046). Additionally, reduced levels of BDNF were observed in patients presenting depression symptoms (44.96 ± 41.06 pg/ml) compared to those without depression (133.5 ± 176.7 pg/ml) (P = 0.036). Importantly, a significant correlation between TGF-β and BDNF was found in patients without cancer but with depression (correlation coefficient = 0.893, **P < 0.01). Interestingly, cancer appeared to influence the association between TGF-β and BDNF in patients with depression, as evidenced by a significant difference in the correlation of TGF-β and BDNF between cancer and non-cancer groups (P = 0.041).

CONCLUSIONS

These findings underscore the active involvement of TGF-β and BDNF crosstalk in the context of cancer-related depression.

Cholesteryl Hemiazelate Present in Cardiovascular Disease Patients Causes Lysosome Dysfunction in Murine Fibroblasts

There is growing evidence supporting the role of fibroblasts in all stages of atherosclerosis, from the initial phase to fibrous cap and plaque formation. In the arterial wall, as with macrophages and vascular smooth muscle cells, fibroblasts are exposed to a myriad of LDL lipids, including the lipid species formed during the oxidation of their polyunsaturated fatty acids of cholesteryl esters (PUFA-CEs). Recently, our group identified the final oxidation products of the PUFA-CEs, cholesteryl hemiesters (ChE), in tissues from cardiovascular disease patients. Cholesteryl hemiazelate (ChA), the most prevalent lipid of this family, is sufficient to impact lysosome function in macrophages and vascular smooth muscle cells, with consequences for their homeostasis. Here, we show that the lysosomal compartment of ChA-treated fibroblasts also becomes dysfunctional. Indeed, fibroblasts exposed to ChA exhibited a perinuclear accumulation of enlarged lysosomes full of neutral lipids. However, this outcome did not trigger de novo lysosome biogenesis, and only the lysosomal transcription factor E3 (TFE3) was slightly transcriptionally upregulated. As a consequence, autophagy was inhibited, probably via mTORC1 activation, culminating in fibroblasts' apoptosis. Our findings suggest that the impairment of lysosome function and autophagy and the induction of apoptosis in fibroblasts may represent an additional mechanism by which ChA can contribute to the progression of atherosclerosis.

Microbiota in cancer: molecular mechanisms and therapeutic interventions

The diverse bacterial populations within the symbiotic microbiota play a pivotal role in both health and disease. Microbiota modulates critical aspects of tumor biology including cell proliferation, invasion, and metastasis. This regulation occurs through mechanisms like enhancing genomic damage, hindering gene repair, activating aberrant cell signaling pathways, influencing tumor cell metabolism, promoting revascularization, and remodeling the tumor immune microenvironment. These microbiota-mediated effects significantly impact overall survival and the recurrence of tumors after surgery by affecting the efficacy of chemoradiotherapy. Moreover, leveraging the microbiota for the development of biovectors, probiotics, prebiotics, and synbiotics, in addition to utilizing antibiotics, dietary adjustments, defensins, oncolytic virotherapy, and fecal microbiota transplantation, offers promising alternatives for cancer treatment. Nonetheless, due to the extensive and diverse nature of the microbiota, along with tumor heterogeneity, the molecular mechanisms underlying the role of microbiota in cancer remain a subject of intense debate. In this context, we refocus on various cancers, delving into the molecular signaling pathways associated with the microbiota and its derivatives, the reshaping of the tumor microenvironmental matrix, and the impact on tolerance to tumor treatments such as chemotherapy and radiotherapy. This exploration aims to shed light on novel perspectives and potential applications in the field.

Skin Cell and Tissue Responses to Cross-Linked Hyaluronic Acid in Low-Grade Inflammatory Conditions

Hyaluronic acid (HA), used in a variety of medical applications, is associated in rare instances to long-term adverse effects. Although the aetiology of these events is unknown, a number of hypotheses have been proposed, including low molecular weight of HA (LMW-HA) in the filler products. We hypothesized that cross-linked HA and its degradation products, in a low-grade inflammatory microenvironment, could impact immune responses that could affect cell behaviours in the dermis. Using two different cross-linking technologies VYC-15L and HYC-24L+, and their hyaluronidase-induced degradation products, we observed for nondegraded HA, VYC-15L and HYC-24L+, a moderate and transient increase in IL-1β, TNF-α in M1 macrophages under low-grade inflammatory conditions. Endothelial cells and fibroblasts were preconditioned using inflammatory medium produced by M1 macrophages. 24 h after LMW-HA fragments and HA stimulation, no cytokine was released in these preconditioned cells. To further characterize HA responses, we used a novel in vivo murine model exhibiting a systemic low-grade inflammatory phenotype. The intradermal injection of VYC-15L and its degradation products induced an inflammation and cell infiltration into the skin that was more pronounced than those by HYC-24L+. This acute cutaneous inflammation was likely due to mechanical effects due to filler injection and tissue integration rather than its biological effects on inflammation. VYC-15L and its degradation product potentiated microvascular response to acetylcholine in the presence of a low-grade inflammation. The different responses with 2D cell models and mouse model using the two tested cross-linking HA technologies showed the importance to use integrative complex model to better understand the effects of HA products according to inflammatory state.

Embryo-derive TNF promotes decidualization via fibroblast activation

Decidualization is a process in which endometrial stromal fibroblasts differentiate into specialized secretory decidual cells and essential for the successful establishment of pregnancy. The underlying mechanism during decidualization still remains poorly defined. Because decidualization and fibroblast activation share similar characteristics, this study was to examine whether fibroblast activation is involved in decidualization. In our study, fibroblast activation-related markers are obviously detected in pregnant decidua and under in vitro decidualization. ACTIVIN A secreted under fibroblast activation promotes in vitro decidualization. We showed that arachidonic acid released from uterine luminal epithelium can induce fibroblast activation and decidualization through PGI₂ and its nuclear receptor PPARδ. Based on the significant difference of fibroblast activation-related markers between pregnant and pseudopregnant mice, we found that embryo-derived TNF promotes CPLA_2α phosphorylation and arachidonic acid release from luminal epithelium. Fibroblast activation is also detected under human in vitro decidualization. Similar arachidonic acid-PGI₂-PPARδ-ACTIVIN A pathway is conserved in human endometrium. Collectively, our data indicate that embryo-derived TNF promotes CPLA_2α phosphorylation and arachidonic acid release from luminal epithelium to induce fibroblast activation and decidualization.

Hydroxysafflower Yellow A Inhibits Vascular Adventitial Fibroblast Migration via NLRP3 Inflammasome Inhibition through Autophagy Activation

Inflammation is closely associated with progression of vascular remodeling. The NLRP3 inflammasome is the key molecule that promotes vascular remodeling via activation of vascular adventitia fibroblast (VAF) proliferation and differentiation. VAFs have a vital effect on vascular remodeling that could be improved using hydroxysafflower yellow A (HSYA). However, whether HSYA ameliorates vascular remodeling through inhibition of NLRP3 inflammasome activation has not been explored in detail. Here, we cultured primary VAFs and analyzed the migration of VAFs induced by angiotensin II (ANG II) to determine the potential effects and mechanism of HSYA on VAF migration. The results thereof showed that HSYA remarkably inhibited ANG II-induced VAF migration, NLRP3 inflammasome activation, and the TLR4/NF-κB signaling pathway in a dose-dependent manner. In addition, it is worth noting that LPS promoted ANG II-induced VAF migration and NLRP3 inflammasome assembly, which could be significantly reversed using HSYA. Moreover, HSYA could be used to inhibit NLRP3 inflammasome activation by promoting autophagy. In conclusion, HSYA could inhibit ANG II-induced VAF migration through autophagy activation and inhibition of NLRP3 inflammasome activation through the TLR4/NF-κB signaling pathway.

Globular adiponectin-mediated vascular remodeling by affecting the secretion of adventitial-derived tumor necrosis factor-α induced by urotensin II

OBJECTIVES

In this study, we explored how adiponectin mediated urotensin II (UII)‍-induced tumor necrosis factor-‍α (TNF-‍α) and α‍-smooth muscle actin (α‍-SMA) expression and ensuing intracellular signaling pathways in adventitial fibroblasts (AFs).

METHODS

Growth-arrested AFs and rat tunica adventitia of vessels were incubated with UII and inhibitors of signal transduction pathways for 1‍‒‍24 h. The cells were then harvested for TNF-α receptor (TNF-‍α-R) messenger RNA (mRNA) and TNF-‍α protein expression determination by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Adiponectin and adiponectin receptor (adipoR) expression was measured by RT-PCR, quantitative real-time PCR (qPCR), immunohistochemical analysis, and cell counting kit-8 (CCK-8) cell proliferation experiments. We then quantified TNF-α and α-SMA mRNA and protein expression levels by qPCR and immunofluorescence (IF) staining. RNA interference (RNAi) was used to explore the function of the adipoR genes. To investigate the signaling pathway, we applied western blotting (WB) to examine phosphorylation of adenosine 5'-monophosphate (AMP)‍-activated protein kinase (AMPK). In vivo, an adiponectin (APN)‍-knockout (APN-KO) mouse model mimicking adventitial inflammation was generated to measure TNF-α and α‍-SMA expression by application of qPCR and IF, with the goal of gaining a comprehensive atlas of adiponectin in vascular remodeling.

RESULTS

In both cells and tissues, UII promoted TNF-α protein and TNF-α-R secretion in a dose- and time-dependent manner via Rho/protein kinase C (PKC) pathway. We detected marked expression of adipoR1, T-cadherin, and calreticulin as well as a moderate presence of adipoR2 in AFs, while no adiponectin was observed. Globular adiponectin (gAd) fostered the growth of AFs, and acted in concert with UII to induce α-SMA and TNF-α through the adipoR1/T-cadherin/calreticulin/AMPK pathway. In AFs, gAd and UII synergistically induced AMPK phosphorylation. In the adventitial inflammation model, APN deficiency up-regulated the expression of α-SMA, UII receptor (UT), and UII while inhibiting TNF-‍α expression.

CONCLUSIONS

From the results of our study, we can speculate that UII induces TNF‍-‍α protein and TNF-‍α‍-R secretion in AFs and rat tunica adventitia of vessels via the Rho and PKC signal transduction pathways. Thus, it is plausible that adiponectin is a major player in adventitial progression and could serve as a novel therapeutic target for cardiovascular disease administration.

Single-Cell RNA Sequencing Technology Revealed the Pivotal Role of Fibroblast Heterogeneity in Angiotensin II-Induced Abdominal Aortic Aneurysms

The mechanism of abdominal aortic aneurysm (AAA) has not been fully elucidated. In this study, we aimed to map the cellular heterogeneity, molecular alteration, and functional transformation of angiotensin (Ang) II-induced AAA in mice based on single-cell RNA sequencing (sc-RNA seq) technology. sc-RNA seq was performed on suprarenal abdominal aorta tissue from male Apoe^-/- C57BL/6 mice of Ang II-induced AAA and shame models to determine the heterogeneity and phenotypic transformation of all cells. Immunohistochemistry was used to determine the pathophysiological characteristics of AAA. The single-cell trajectory was performed to predict the differentiation of fibroblasts. Finally ligand-receptor analysis was used to evaluate intercellular communication between fibroblasts and smooth muscle cells (SMCs). More than 27,000 cells were isolated and 25 clusters representing 8 types of cells were identified, including fibroblasts, macrophages, endothelial cells, SMCs, T lymphocytes, B lymphocytes, granulocytes, and natural killer cells. During AAA progression, the function and phenotype of different type cells altered separately, including activation of inflammatory cells, alternations of macrophage polarization, phenotypic transformation of vascular smooth muscle cells, and endothelial to mesenchymal transformation. The alterations of fibroblasts were the most conspicuous. Single-cell trajectory revealed the critical reprogramming genes of fibroblasts mainly enriched in regulation of immune system. Finally, the ligand-receptor analysis confirmed that disorder of collagen metabolism led by fibroblasts was one of the most prominent characteristics of Ang II-induced AAA. Our study revealed the cellular heterogeneity of Ang II-induced AAA. Fibroblasts may play a critical role in Ang II-induced AAA progression according to multiple biological functions, including immune regulation and extracellular matrix metabolic balance. Our study may provide us with a different perspective on the etiology and pathogenesis of AAA.

Synthetic Vascular Graft with Spatially Distinct Architecture for Rapid Biomimetic Cell Organisation in a Perfusion Bioreactor

Access to lab-grown fully functional blood vessels would provide an invaluable resource to vascular medicine. The complex architecture and cellular makeup of native vessels, however, makes this extremely challenging to reproduce in vitro. Bioreactor systems have helped advanced research in this area by replicating many of the physiological conditions necessary for full-scale tissue growth outside of the body. A key element underpinning these technologies are 3D vascular graft templates which serve as temporary scaffolds to direct cell growth into similar cellular architectures observed in native vessels. Grafts further engineered with appropriate physical cues to accommodate the multiple cell types that reside within native vessels may help improve the production efficiency and physiological accuracy of bioreactor-grown vessel substitutes. Here, we engineered two distinct scaffold architectures into an electrospun vascular graft aiming to encourage the spatial organisation of human vascular endothelial cells (hCAECs) in a continuous luminal monolayer, co-cultured with human fibroblasts (hFBs) populating the graft wall. Using an electrospun composite of polycaprolactone (PCL) and gelatin, we evaluated physical parameters including fibre thickness, fibre alignment, and porosity, that best mimicked the spatial composition and growth of hCAECs and hFBs in native vessels. Upon identifying the optimal scaffold architectures for each cell type, we constructed a custom-designed mandrel that combined these distinct architectures into a single vascular graft during a single electrospinning processing run. When connected to a perfusion bioreactor system, the dual architecture graft spatially oriented hCAECs and hFBs into the graft wall and lumen, respectively, directly from circulation. This biomimetic cell organisation was consistent with positive graft remodelling with significant collagen deposition in the graft wall. These findings demonstrate the influence of architectural cues to direct cell growth within vascular graft templates and the future potential of these approaches to more accurately and efficiency produce blood vessel substitutes in bioreactor systems.

Efferocytosis of vascular cells in cardiovascular disease

Cell death and the clearance of apoptotic cells are tightly regulated by various signaling molecules in order to maintain physiological tissue function and homeostasis. The phagocytic removal of apoptotic cells is known as the process of efferocytosis, and abnormal efferocytosis is linked to various health complications and diseases, such as cardiovascular disease, inflammatory diseases, and autoimmune diseases. During efferocytosis, phagocytic cells and/or apoptotic cells release signals, such as "find me" and "eat me" signals, to stimulate the phagocytic engulfment of apoptotic cells. Primary phagocytic cells are macrophages and dendritic cells; however, more recently, other neighboring cell types have also been shown to exhibit phagocytic character, including endothelial cells and fibroblasts, although they are comparatively slower in clearing dead cells. In this review, we focus on macrophage efferocytosis of vascular cells, such as endothelial cells, smooth muscle cells, fibroblasts, and pericytes, and its relation to the progression and development of cardiovascular disease. We also highlight the role of efferocytosis-related molecules and their contribution to the maintenance of vascular homeostasis.

Single-Cell Transcriptome Profiles Reveal Fibrocytes as Potential Targets of Cell Therapies for Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is potentially life-threatening in aging population due to the risk of aortic rupture and a lack of optimal treatment. The roles of different vascular and immune cells in AAA formation and pathogenesis remain to be future characterized. Single-cell RNA sequencing was performed on an angiotensin (Ang) II-induced mouse model of AAA. Macrophages, B cells, T cells, fibroblasts, smooth muscle cells and endothelial cells were identified through bioinformatic analyses. The discovery of multiple subtypes of macrophages, such as the re-polarization of Trem2⁺Acp5⁺ osteoclast-like and M2-like macrophages toward the M1 type macrophages, indicates the heterogenous nature of macrophages during AAA development. More interestingly, we defined CD45⁺COL1⁺ fibrocytes, which was further validated by flow cytometry and immunostaining in mouse and human AAA tissues. We then reconstituted these fibrocytes into mice with Ang II-induced AAA and found the recruitment of these fibrocytes in mouse AAA. More importantly, the fibrocyte treatment exhibited a protective effect against AAA development, perhaps through modulating extracellular matrix production and thus enhancing aortic stability. Our study reveals the heterogeneity of macrophages and the involvement of a novel cell type, fibrocyte, in AAA. Fibrocyte may represent a potential cell therapy target for AAA.

A multifunctional hydrogel coating to direct fibroblast activation and infected wound healing via simultaneously controllable photobiomodulation and photodynamic therapies

Bacterial infection treatment and subsequent tissue rebuilding are the main tasks of biomaterial research. To endow implants with antibacterial activity and biological functions, the material systems are usually very complicated and ineffective. Recently, the concept of photobiomodulation (PBM), or low-level laser therapy (LLLT), has attracted increasing attention in tissue repair applications but still has not obtained wide acceptance. Because of the same laser resource, PBM could simultaneously work with 660 nm laser triggered photodynamic therapy (PDT), which will significantly simplify the material system and achieve the multiple functions of antibacterial activity and biological modulation effects. Herein, we attempt to validate the effectiveness of PBM and combine PBM with a PDT-based material system. A catechol motif-modified methacrylated gelatin containing photosensitizer Chlorin e6-loaded mesoporous polydopamine nanoparticles was fabricated (GelMAc/MPDA@Ce6). This hydrogel could be tightly adhered to titanium surfaces to serve as surface coating materials or directly used as dressings. Because of the 660 nm laser-triggered ROS generation property of Ce6, GelMAc/MPDA@Ce6 exhibited a remarkable and rapid antibacterial activity when the laser power was 1 W cm^-2. After bacterial elimination, when the power was adjusted to 100 mW cm^-2, daily irradiation brought an excellent PBM effect: the fibroblast activation was realized to accelerate wound repair. According to our in vitro and in vivo results, the fabricated hydrogel coating possessed both antibacterial activity and fibroblast activation ability only by adjusting the power of laser irradiation, which will greatly strengthen the confidence of using PBM in broader fields and give a good example to combine PBM with traditional biomaterial design.

Camostat mesilate inhibits pro-inflammatory cytokine secretion and improves cell viability by regulating MFGE8 and HMGN1 in lipopolysaccharide-stimulated DF-1 chicken embryo fibroblasts

Camostat mesilate (CM) possesses potential anti-viral and anti-inflammatory activities. However, it remains unknown whether CM is involved in lipopolysaccharide (LPS)-mediated inflammatory responses and cell injury. In this project, differentially expressed proteins (DEPs, fold change ≥ 1.2 or ≤ 0.83 and Q value ≤ 0.05) in response to LPS stimulation alone or in combination with CM were identified through tandem mass tags (TMT)/mass spectrometry (MS)-based proteomics analysis in DF-1 chicken embryo fibroblasts. The mRNA expression levels of filtered genes were determined by RT-qPCR assay. The results showed that CM alleviated the detrimental effect of LPS on cell viability and inhibited LPS-induced TNF-α and IL-6 secretions in DF-1 chicken embryo fibroblasts. A total of 141 DEPs that might be involved in mediating functions of both LPS and CM were identified by proteomics analysis in DF-1 chicken embryo fibroblasts. LPS inhibited milk fat globule EGF and factor V/VIII domain containing (MFGE8) expression and induced high mobility group nucleosome binding domain 1 (HMGN1) expression, while these effects were abrogated by CM in DF-1 chicken embryo fibroblasts. MFGE8 knockdown facilitated TNF-α and IL-6 secretions , reduced cell viability, stimulated cell apoptosis in DF-1 chicken embryo fibroblasts co-treated with LPS and CM. HMGN1 loss did not influence TNF-α and IL-6 secretions, cell viability, and cell apoptosis in DF-1 chicken embryo fibroblasts co-treated with LPS and CM. In conclusion, CM exerted anti-inflammatory and pro-survival activities by regulating MFGE8 in LPS-stimulated DF-1 chicken embryo fibroblasts, deepening our understanding of the roles and molecular basis of CM in protecting against Gram-negative bacteria.

Evaluating outcomes of pulsed dye laser therapy combined with intralesional triamcinolone injection after surgical removal of hypertrophic cesarean section scars

BACKGROUND

Recently, pulsed dye laser (PDL) combined with triamcinolone intralesional injection (TAILI) has been introduced for surgical scar prevention. However, little is known about this procedure's effectiveness in preventing hypertrophic scar following surgical scar removal.

OBJECTIVES

This study aimed to evaluate the outcome of early intervention using PDL combined with TAILI after surgical removal of hypertrophic cesarean section (CS) scars.

METHODS

The medical records of 35 patients who underwent early intervention using PDL and TAILI after removal of hypertrophic CS scars were retrospectively reviewed. The scars' average Vancouver Scar Scale (VSS) scores before scar removal and 3 months after the final treatment were compared.

RESULTS

The patients received 4.23 treatments on average and were followed up for a mean period of 7.74 months. The mean final VSS was 3.11 ± 1.52 and was significantly lower than that of the previous VSS (9.29 ± 1.74, p = 0.000). VSS of the previous CS scar, and the presence or absence of keloid formation in other areas, was associated with treatment outcome (p = 0.003 and 0.008, respectively).

CONCLUSIONS

Early intervention using PDL combined with TAILI could prevent the recurrence or progression of hypertrophic CS scarring after surgical scar removal.

Mechanisms of homocysteine-induced damage to the endothelial, medial and adventitial layers of the arterial wall

Homocysteine (Hcy) is a non-protein forming amino acid which is the direct metabolic precursor of methionine. Increased concentration of serum Hcy is considered a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature. Serum Hcy is associated with atherosclerosis, hypertension and aneurysms of the aorta in humans, though the precise mechanisms by which Hcy contributes to these conditions remain elusive. Results from clinical trials that successfully lowered serum Hcy without reducing features of vascular disease in cardiovascular patients have cast doubt on whether or not Hcy directly impacts the vasculature. However, studies in animals and in cell culture suggest that Hcy has a vast array of toxic effects on the vasculature, with demonstrated roles in endothelial dysfunction, medial remodeling and adventitial inflammation. It is hypothesized that rather than serum Hcy, tissue-bound Hcy and the incorporation of Hcy into proteins could underlie the toxic effects of Hcy on the vasculature. In this review, we present evidence for Hcy-associated vascular disease in humans, and we critically examine the possible mechanisms by which Hcy specifically impacts the endothelial, medial and adventitial layers of the arterial wall. Deciphering the mechanisms by which Hcy interacts with proteins in the arterial wall will allow for a better understanding of the pathomechanisms of hyperhomocysteinemia and will help to define a better means of prevention at the appropriate window of life.

Preparation of Cell-Paved and -Incorporated Polysaccharide Hollow Fibers Using a Microfluidic Device

Cellular constructs having hollow tubular structures are expected to be used as artificial blood vessels. We have recently demonstrated that water-insoluble polyion complexes (PICs) were formed from water-soluble polysaccharides with opposite charges at the interface of coaxial flows, which resulted in the formation of hollow fibers. In this study, both inside- and outside-cell-laden chondroitin sulfate C (CS)/chitosan (CHI) hollow fibers were prepared by utilizing a microfluidic device and modification with cell adhesive molecules. Loading of type I collagen (COL) and surface modification with fibronectin and gelatin using layer-by-layer assembly techniques improved the adhesion and spreading of fibroblast cells to/on the surface of CS/CHI hollow fibers. On the other hand, by suspending mesenchymal stem cells (MSCs) in the core flow solution, cells were successfully loaded in the walls of the hollow fibers. As the culture time extended, cells trapped in the PIC structures constituting the wall of the hollow fibers migrated to the interface between the hollow fibers and the medium: cells adhered to and stretched "on" the lumen surfaces in the COL-loaded fibers. In contrast, for the case of unmodified hollow fibers, it was difficult for cells to adhere to the lumen surfaces. Therefore, cell aggregates were formed "in" the lumen. Results of the live/dead assay and MTT assay clearly demonstrated that MSCs possessed certain levels of cell viability and proliferated for up to 10 days, especially for the cases of COL-loaded hollow fibers. On the basis of these results, the utility of the present hollow fibers in the formation of cellular constructs corresponding to blood vessels is also discussed.

Impact of Human Dermal Microvascular Endothelial Cells on Primary Dermal Fibroblasts in Response to Inflammatory Stress

The aim of the present study was to evaluate the impact of the microenvironment produced by dermal microvascular endothelial cells, secondary to a pro-inflammatory challenge, on 2D culture models using dermal fibroblasts and in 3D reconstructed skin model using dermal fibroblasts and keratinocytes from healthy donors. We hypothesized that specific microvascular endothelial low grade inflammation could change fibroblasts phenotype and be involved in extracellular matrix (ECM) modification and skin alteration. Following IFNγ, TNFα, IL-1β pro-inflammatory stress on Human Dermal Endothelial Cells (HDMEC) we observed the increased release of Chemokine ligand 2 (CCL2), IL-6 and IL-8 but not VEGF-A in the conditioned medium (CM). The subsequent addition of this endothelial pro-inflammatory CM in dermal fibroblasts revealed an upregulation of IL6, IL8 and CCL2 but no NF-κB gene expression. The resulting ECM formation was impaired with a reduction of the collagen 1 network and a decrease in COL1A1 gene expression in 2D and 3D models. Collagen 1 and pro-LOX protein expression were significantly reduced confirming an impairment of the collagen network related to endothelial inflammation secretion. To conclude, this work showed that, without any immune cells, the endothelial secretion in response to a pro-inflammatory stress is able to activate the fibroblasts that will maintain the pro-inflammatory environment and exacerbate ECM degradation.

Cytokine Research in Depression: Principles, Challenges, and Open Questions

Cytokines have been implicated in the pathology of depression. Currently, the evidence is based on cross-sectional studies and meta-analytic research comparing blood concentrations of T helper type 1 (TH1), T helper type 2 (TH2), pro-inflammatory or anti-inflammatory cytokines of patients with a depressive disorder to those of healthy controls. Additionally, multiple longitudinal studies have investigated cytokine levels during antidepressant treatment. According to the current literature, it seems that peripheral levels of interleukin (IL)-6, IL-10, IL-12, IL-13, and tumor necrosis factor (TNF)-α are elevated and that interferon (IFN)-γ levels are lower in patients with depression compared to healthy controls. However, the overlap of cytokine values between acutely depressed patients, remitted and recovered patients and healthy controls is considerable. Thus, the discriminative power of cytokine concentrations between depressed and non-depressed people is likely weak. Treatment with certain antidepressants appears to decrease peripheral levels of IL-6, IL-10, and TNF-α. However, weight gain-inducing psychopharmacological substances, such as the antidepressant mirtazapine, have been reported to potentially increase the production of pro-inflammatory cytokines. Even though cytokines are often discussed as biomarkers for depression, they have also been shown to be altered in other psychiatric disorders. Moreover, many environmental, social, psychological, biological, and medical factors are also associated with cytokine changes. Thus, cytokine alterations seem extremely unspecific. The interpretation of the results of these studies remains a challenge because it is unknown which type of cells are most responsible for cytokine changes measured in the blood nor have the main target cells or target tissues been identified. The same cytokine can be produced by multiple cell types, and the same cell can produce various cytokines. Additionally, redundancy, synergy, antagonism, and signaling cascades of cytokine signaling must be considered. Cytokines might not be associated with the diagnosis of depression according to the currently used diagnostic manuals, but rather with specific subtypes of depression, or with depressive symptoms across different psychiatric diagnoses. Therefore, the currently available diagnostic systems may not be the ideal starting point for psychiatric cytokine research.

Performance of marrow stromal cell-seeded small-caliber multilayered vascular graft in a senescent sheep model

Failure of small-caliber grafts, used as bypass or reconstructive grafts in cardiovascular treatments, is often caused by thrombosis and stenosis. We have developed a multilayered, compliant graft with an electrospun heparin-encapsulated core and collagen-chitosan shell. Herein, the performances of acellular and cell-seeded grafts were evaluated in adult sheep for preclinical assessment. Allogeneic ovine marrow stroma cells (MSCs) were uniformly attached to the lumen of cell-seeded grafts. Interposition grafts were used for carotid arteries. Four grafts were tested for each type. Upon implantation, all grafts successfully restored perfusion and rhythmically deformed under pulsatile arterial flow. Weekly ultrasonography and Doppler revealed that all grafts remained patent for perfusion during the course of one-month study. No formation of blood clots or other complications were found. The diameter of graft lumen did not vary significantly over the time or with the graft type, while narrowing at anastomosis and significant thickening of graft wall were found in both types of grafts. More significant neotissue formation was found at anastomotic sections of acellular controls compared to cell-seeded grafts. Results from histological and immunofluorescent analyses revealed moderate intimal hyperplasia (IH) at anastomosis. When compared to cell-seeded grafts, acellular controls presented thicker IH composed of α-smooth muscle actin positive cells and ground substances, which correlated with reduced and more disturbing flow. IH was thickest at anastomosis and tapered off to a minimum in the mid-section. Few PECAM-positive cells appeared on cell-seeded grafts but not acellular controls. Additionally, lesser graft thickening was found in cell-seed grafts, which might be associated with the function of stromal cells in altering the fibrotic process during tissue repair. Results suggest that MSCs held the potential to reduce hyperplasia and improve healing in an aged, large animal model for vascular grafting.

Urotensin II promotes aldosterone expression in rat aortic adventitial fibroblasts

Urotensin II (UII) contributes to cardiovascular diseases by activating vasoactive peptides. The present study aimed to determine the effect of UII on aldosterone (ALD) and its receptor in cultured adventitial fibroblasts (AFs) and the tunica adventitia of rat vessels to explore the possible mechanisms underlying vascular remodeling. Expression levels of aldosterone and its receptor on tunica adventitia were determined using immunohistochemistry. Growth‑arrested AFs and tunica adventitia from rat vessels were incubated with UII and inhibitors of various signal transduction pathways. ALD receptor (ALD‑R) mRNA expression levels and ALD protein exoression levels were determined by reverse transcription‑quantitative polymerase chain reaction and ELISA, respectively. Aldosterone and its receptors were expressed on tunica adventitia. UII promoted ALD protein secretion from cells in a dose‑ and time‑dependent manner. ALD‑R mRNA expression in cells was also dysregulated. Furthermore, the effects of UII were substantially inhibited by treatment with the inhibitors PD98059, Y‑27632, H‑7, CSA and nicardipine. These results were further verified in the tunica adventitia of rat vessels. The present findings indicated that UII stimulated ALD protein secretion and ALD‑R mRNA expression in AFs and in the tunica adventitia of rat vessels; moreover, this effect may be mediated by signal transduction pathways involving MAPK, Rho, PKC, calcineurin and Ca2+. UII may also contribute to vascular remodeling by stimulating the production of ALD and its receptor.

Adventitial Activation in the Pathogenesis of Injury-Induced Arterial Remodeling: Potential Implications in Transplant Vasculopathy

Transplant vasculopathy is one of the major causes of chronic rejection after solid organ transplantation. The pathogenic mechanisms of transplant vasculopathy are still poorly understood. Herein, we summarize current evidence suggesting that activation of the tunica adventitia may be involved in the pathogenesis of transplant vasculopathy. Adventitia is an early responder to various vascular injuries and plays an integral role in eliciting vascular inflammation and remodeling. Accumulation of macrophages in the adventitia promotes the development of vascular remodeling by releasing a variety of paracrine factors that have profound impacts on vascular mural cells. Targeting adventitial macrophages has been shown to be effective for repressing transplantation-induced arterial remodeling in animal models. Adventitia also fosters angiogenesis, and neovascularization of the adventitial layer may facilitate the transport of inflammatory cells through the arterial wall. Further investigations are warranted to clarify whether inhibiting adventitial oxidative stress and/or adventitial neovascularization are better strategies for preventing transplant vasculopathy.

Biological Interaction Between Human Gingival Fibroblasts and Vascular Endothelial Cells for Angiogenesis: A Co-culture Perspective

Advancement in cell culture protocols, multidisciplinary research approach, and the need of clinical implication to reconstruct damaged or diseased tissues has led to the establishment of three-dimensional (3D) test systems for regeneration and repair. Regenerative therapies, including dental tissue engineering, have been pursued as a new prospect to repair and rebuild the diseased/lost oral tissues. Interactions between the different cell types, growth factors, and extracellular matrix components involved in angiogenesis are vital in the mechanisms of new vessel formation for tissue regeneration. In vitro pre-vascularization is one of the leading scopes in the tissue-engineering field. Vascularization strategies that are associated with co-culture systems have proved that there is communication between different cell types with mutual beneficial effects in vascularization and tissue regeneration in two-dimensional or 3D cultures. Endothelial cells with different cell populations, including osteoblasts, smooth muscle cells, and fibroblasts in a co-culture have shown their ability to advocate pre-vascularization. In this review, a co-culture perspective of human gingival fibroblasts and vascular endothelial cells is discussed with the main focus on vascularization and future perspective of this model in regeneration and repair.

Bacillus Calmette-Guerin alleviates airway inflammation and remodeling by preventing TGF-β1 induced epithelial-mesenchymal transition

Bacillus Calmette-Guerin (BCG) is a potent agent for the prevention of tuberculosis. Current studies have regarded BCG as an immunomodulator. However, there is little information on whether it can be used to inhibit airway inflammation and airway remodeling caused by asthma. Therefore, in this study, we investigate the role of epithelial-mesenchymal transition (EMT) in airway inflammation and airway remodeling as well as the possible therapeutic mechanism of BCG for the treatment of asthma. Wistar rats were sensitized and challenged by ovalbumin for 2 weeks or 8 weeks. BCG was subcutaneously administered daily before every ovalbumin challenge to determine its therapeutic effects. The 2 weeks model group showed extensive eosinophilia, chronic inflammatory responses, bronchial wall thickening, airway epithelium damage, increased levels of transforming growth factor β 1 (TGF-β₁) in both bronchoalveolar lavage fluid and sera, decreased expression of epithelial marker E-cadherin, and increased expressions of mesenchymal markers α-smooth muscle actin (α-SMA) and Fibronectin (Fn). Except for inflammatory responses, all responses were more significant in the 8 weeks model group which displayed characteristics of airway remodeling including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. When compared with the model groups, BCG administration inhibited airway inflammation and airway remodeling, decreased TGF-β₁ levels, upregulated expression of E-cadherin, and downregulated expression of α-SMA and Fn. The present study suggests for the first time that increased secretion of TGF- β₁ induced by asthmatic chronic inflammation may result in EMT, which is one of the most important mechanisms of airway inflammation and airway remodeling seen with asthma. BCG alleviates airway inflammation and airway remodeling by preventing TGF-β₁ induced EMT, therefore BCG may be a new therapy for treating asthma.

Adventitial Fibroblast Nox4 Expression and ROS Signaling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease arising from remodeling and narrowing of pulmonary arteries (PA) resulting in high pulmonary arterial blood pressure and ultimately right ventricular failure. Elevated production of reactive oxygen species (ROS) by NADPH oxidase 4 (Nox4), a constitutively active enzyme, has been associated with oxygen sensing, vasomotor control, cellular proliferation, differentiation, migration, apoptosis, senescence, fibrosis, and angiogenesis. Further, elevated expression of Nox4 has been reported in a number of cardiovascular diseases, including atherosclerosis, hypertension, cardiac failure, ischemic stroke, and PAH. However, the cellular location of Nox4 and its contribution to aberrant vascular remodeling in PAH remains poorly understood. The goal of this review is to summarize the recent literature on the enzymatic regulation of Nox4 in the production of ROS in PAH. In the vascular wall, Nox4 is present in fibroblasts, a primary cell of the adventitia, and matches the adventitial location of ROS production in PAH. Further, in adventitial fibroblasts, Nox4 overexpression stimulates migration and proliferation as well as matrix gene expression. Collectively, reports indicate that Nox4 contributes to altered fibroblast behavior, ROS production leading to hypertensive vascular remodeling and the development of PAH. Finally, we address the functional significance of Nox4 in fibroblasts, and also suggest an "outside in" (adventitial) process of vascular remodeling that is mediated by Nox4, which although has physiological roles in the intimal layer (i.e., endothelium), may also have pathologic importance in the adventitial layer of the vascular wall through signaling in fibroblasts.

Reduced Sympathetic Innervation in Endometriosis is Associated to Semaphorin 3C and 3F Expression

Endometriosis is a chronic inflammatory disease and one of the most common causes of pelvic pain. The mechanisms underlying pain emergence or chronic inflammation during endometriosis remain unknown. Several chronic inflammatory diseases including endometriosis show reduced amounts of noradrenergic nerve fibers. The source of the affected innervation is still unclear. Semaphorins represent potential elicitors, due to their known role as axonal guidance cues, and are suggested as nerve repellent factors in different chronic inflammatory diseases. Therefore, semaphorins might influence the progress of neuroinflammatory mechanisms during endometriosis. Here, we analyzed the noradrenergic innervation and the expression of the specific semaphorins and receptors possibly involved in the neuroimmunomodulation in endometriosis. Our studies revealed an affected innervation and a significant increase of semaphorins and their receptors in peritoneal endometriotic tissue. Thereby, the expression of the receptors was identified on the membrane of noradrenergic nerve fibers and vessels. Macrophages and activated fibroblasts were found in higher density levels and additionally express semaphorins in peritoneal endometriotic tissue. Inflammation leads to an increased release of immune cells, which secrete a variety of inflammatory factors capable of affecting innervation. Therefore, our data suggests that the chronic inflammatory condition in endometriosis might contribute to the increase of semaphorins, which could possibly affect the innervation in peritoneal endometriosis.

Development of Antiviral Innate Immunity During In Vitro Differentiation of Mouse Embryonic Stem Cells

The innate immunity of embryonic stem cells (ESCs) has recently emerged as an important issue in ESC biology and in ESC-based regenerative medicine. We have recently reported that mouse ESCs (mESCs) do not have a functional type I interferon (IFN)-based antiviral innate immunity. They are deficient in expressing IFN in response to viral infection and have limited ability to respond to IFN. Using fibroblasts (FBs) as a cell model, the current study investigated the development of antiviral mechanisms during in vitro differentiation of mESCs. We demonstrate that mESC-differentiated FBs (mESC-FBs) share extensive similarities with naturally differentiated FBs in morphology, marker expression, and growth pattern, but their development of antiviral mechanisms lags behind. Nonetheless, the antiviral mechanisms are inducible during mESC differentiation as demonstrated by the transition of nuclear factor kappa B (NFκB), a key transcription factor for IFN expression, from its inactive state in mESCs to its active state in mESC-FBs and by increased responses of mESC-FBs to viral stimuli and IFN during their continued in vitro propagation. Together with our previously published study, the current data provide important insights into molecular basis for the deficiency of IFN expression in mESCs and the development of antiviral innate immunity during mESC differentiation.

Ageing and inflammation - A central role for mitochondria in brain health and disease

To develop successful therapies that prevent or treat neurodegenerative diseases requires an understanding of the upstream events. Ageing is by far the greatest risk factor for most of these diseases, and to clarify their causes will require an understanding of the process of ageing itself. Starting with the question Why do we age as individual organisms, but the line of pluripotent embryonic stem cells and germ cells carried by individuals and transmitted to descendants is immortal? this review discusses how the process of cellular differentiation leads to the accumulation of biological imperfections with ageing, and how these imperfections may be the cause of chronic inflammatory responses to stress that undermine cellular function. Both differentiation and inflammation involve drastic metabolic changes associated with alterations in mitochondrial dynamics that shift the balance between aerobic glycolysis and oxidative phosphorylation. With ageing, mitochondrial dysfunction can be both the cause and consequence of inflammatory processes and elicit metabolic adaptations that might be either protective or become progressively detrimental. It is argued here that an understanding of the relationship between metabolism, differentiation and inflammation is essential to understand the pathological mechanisms governing brain health and disease during ageing.

FKBPL is a critical antiangiogenic regulator of developmental and pathological angiogenesis

OBJECTIVE

The antitumor effects of FK506-binding protein like (FKBPL) and its extracellular role in angiogenesis are well characterized; however, its role in physiological/developmental angiogenesis and the effect of FKBPL ablation has not been evaluated. This is important as effects of some angiogenic proteins are dosage dependent. Here we evaluate the regulation of FKBPL secretion under angiogenic stimuli, as well as the effect of FKBPL ablation in angiogenesis using mouse and zebrafish models.

APPROACH AND RESULTS

FKBPL is secreted maximally by human microvascular endothelial cells and fibroblasts, and this was specifically downregulated by proangiogenic hypoxic signals, but not by the angiogenic cytokines, VEGF or IL8. FKBPL's critical role in angiogenesis was supported by our inability to generate an Fkbpl knockout mouse, with embryonic lethality occurring before E8.5. However, whilst Fkbpl heterozygotic embryos showed some vasculature irregularities, the mice developed normally. In murine angiogenesis models, including the ex vivo aortic ring assay, in vivo sponge assay, and tumor growth assay, Fkbpl(+/-) mice exhibited increased sprouting, enhanced vessel recruitment, and faster tumor growth, respectively, supporting the antiangiogenic function of FKBPL. In zebrafish, knockdown of zFkbpl using morpholinos disrupted the vasculature, and the phenotype was rescued with hFKBPL. Interestingly, this vessel disruption was ineffective when zcd44 was knocked-down, supporting the dependency of zFkbpl on zCd44 in zebrafish.

CONCLUSIONS

FKBPL is an important regulator of angiogenesis, having an essential role in murine and zebrafish blood vessel development. Mouse models of angiogenesis demonstrated a proangiogenic phenotype in Fkbpl heterozygotes.

NADPH oxidase 4 is expressed in pulmonary artery adventitia and contributes to hypertensive vascular remodeling

OBJECTIVE

Pulmonary hypertension (PH) is a progressive disease arising from remodeling and narrowing of pulmonary arteries (PAs) resulting in high pulmonary blood pressure and ultimately right ventricular failure. Elevated production of reactive oxygen species by NADPH oxidase 4 (Nox4) is associated with increased pressure in PH. However, the cellular location of Nox4 and its contribution to aberrant vascular remodeling in PH remains poorly understood. Therefore, we sought to identify the vascular cells expressing Nox4 in PAs and determine the functional relevance of Nox4 in PH.

APPROACH AND RESULTS

Elevated expression of Nox4 was detected in hypertensive PAs from 3 rat PH models and human PH using qualititative real-time reverse transcription polymerase chain reaction, Western blot, and immunofluorescence. In the vascular wall, Nox4 was detected in both endothelium and adventitia, and perivascular staining was prominently increased in hypertensive lung sections, colocalizing with cells expressing fibroblast and monocyte markers and matching the adventitial location of reactive oxygen species production. Small-molecule inhibitors of Nox4 reduced adventitial reactive oxygen species generation and vascular remodeling as well as ameliorating right ventricular hypertrophy and noninvasive indices of PA stiffness in monocrotaline-treated rats as determined by morphometric analysis and high-resolution digital ultrasound. Nox4 inhibitors improved PH in both prevention and reversal protocols and reduced the expression of fibroblast markers in isolated PAs. In fibroblasts, Nox4 overexpression stimulated migration and proliferation and was necessary for matrix gene expression.

CONCLUSION

These findings indicate that Nox4 is prominently expressed in the adventitia and contributes to altered fibroblast behavior, hypertensive vascular remodeling, and development of PH.

Immune mechanisms in medium and large-vessel vasculitis

Vasculitis of the medium and large arteries, most often presenting as giant cell arteritis (GCA), is an infrequent, but potentially fatal, type of immune-mediated vascular disease. The site of the aberrant immune reaction, the mural layers of the artery, is strictly defined by vascular dendritic cells, endothelial cells, vascular smooth muscle cells and fibroblasts, which engage in an interaction with T cells and macrophages to, ultimately, cause luminal stenosis or aneurysmal wall damage of the vessel. A multitude of effector cytokines, all known as critical mediators in host-protective immunity, have been identified in vasculitic lesions. Two dominant cytokine clusters--the IL-6-IL-17 axis and the IL-12-IFN-γ axis--have been linked to disease activity. These two clusters seem to serve different roles in the vasculitic process. The IL-6-IL-17 cluster is highly responsive to standard corticosteroid therapy, whereas the IL-12-IFN-γ cluster is resistant to steroid-mediated immunosuppression. The information exchange between vascular and immune cells and stabilization of the vasculitic process involves members of the Notch receptor and ligand family. Focusing on elements in the tissue context of GCA, instead of broadly suppressing host immunity, might enable a more tailored therapeutic approach that avoids unwanted adverse effects of aggressive immunosuppression.

Prevention of peridural fibrosis using a cyclooxygenase-2 inhibitor (nonsteroidal anti-inflammatory drug) soaked in absorbable gelatin sponge: an experimental comparative animal model

STUDY DESIGN

Experimental study.

OBJECTIVE

To evaluate the efficacy and safety of peridural parecoxib-soaked absorbable gelatin sponge, and cellulose membrane on peridural fibrosis prevention in an animal model.

SUMMARY OF BACKGROUND DATA

Postoperative peridural fibrosis is one of the causes of failed back surgery syndrome. Nonsteroidal anti-inflammatory drugs inhibit the inflammatory response, while an absorbable gelatin sponge or cellulose membrane interposes between the dura and the paraspinal muscle to staunch the surgical bleeding. These mechanisms may prevent peridural fibrosis.

METHODS

Forty L5-L6 laminectomized adult Sprague-Dawley rats were randomly allocated into 4 groups. The high parecoxib group received 6 mg of parecoxib soaked into an absorbable gelatin sponge placed over the dura. The low parecoxib group was given 2 mg of parecoxib soaked into an absorbable gelatin sponge. The dura in the cellulose group was covered with a cellulose membrane, while the control group received normal saline drip before surgical wound closure. All rats were killed at 6 weeks for histopathological assessment. The fibroblast density, inflammatory cell density, fibrous adherence, and adverse events were quantified. The obtained results were analyzed statistically.

RESULTS

The respective mean fibroblast density in the high parecoxib, low parecoxib, cellulose, and control groups was 217.77 ± 51.76, 317.51 ± 126.92, 321.80 ± 90.94, and 328.48 ± 73.41 cells/mm², while the respective mean inflammatory cell density was 539.65 ± 236.52, 910.17 ± 242.59, 1011.84 ± 239.30, and 1261.78 ± 319.68 cells/mm². The mean fibroblast and inflammatory cell densities of the high parecoxib group were significantly lower than the control. The high parecoxib group also showed statistically less fibrous adherence than low parecoxib, cellulose, and control groups.

CONCLUSION

The high-dose parecoxib-soaked absorbable gelatin sponge can prevent peridural fibrosis without complications. The low-dose parecoxib and cellulose membrane provided no significant benefit vis-à-vis prevention of peridural fibrosis, as adduced from the lack of any statistically significant difference between the test and control rats.

Pro-angiogenic activity of TLRs and NLRs: a novel link between gut microbiota and intestinal angiogenesis

BACKGROUND & AIMS

In intestinal inflammation the gut microbiota induces an innate immune response by activating epithelial and immune cells that initiate or maintain inflammation. We investigated whether the microbiota also can activate local microvascular cells and induce angiogenesis.

METHODS

Human intestinal microvascular endothelial cells (HIMEC) and human intestinal fibroblasts (HIF) were exposed to bacterial ligands specific for Toll-like receptor (TLR)2/6 and 4, and NOD1 and NOD2, and cell proliferation, migration, transmigration, tube formation, and production of pro-angiogenic factors were measured. The ability of the ligands to induce ex vivo vessel sprouting in an aortic ring assay and in vivo angiogenesis using a collagen gel assay also were assessed.

RESULTS

Bacterial ligands induced proliferation, migration, transmigration, tube formation of HIMEC, vessel sprouting, and in vivo angiogenesis; they also stimulated production of angiogenic factors from HIMEC and HIF, and HIF-derived angiogenic factors promoted HIMEC proliferation. To various degrees, all ligands induced angiogenic responses, but these were ligand- and cell type-dependent. Responses were mediated through receptor interacting protein-2 (RIP2)- and tumor necrosis factor receptor-associated factor 6 (TRAF6)-dependent signaling, involved the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways and the up-regulation of vascular endothelial growth factor receptor 2 (VEGF-R2) and focal adhesion kinase (FAK). Knockdown of RIP2 and TRAF6 by RNA interference and neutralization of interleukin-8, basic fibroblast growth factor, and vascular endothelial growth factor inhibited TLR-/NOD-like receptor-induced HIMEC angiogenesis.

CONCLUSIONS

The gut microbiota can selectively activate mucosal endothelial and mesenchymal cells to promote specific angiogenic responses in a TLR- and NOD-like receptor-dependent fashion. This innate immunity-mediated response may expand the mucosal microvascular network, foster immune cell recruitment, and contribute to chronic intestinal inflammation.

Hyperhomocysteinemia exaggerates adventitial inflammation and angiotensin II-induced abdominal aortic aneurysm in mice

RATIONALE

A number of epidemiological studies have suggested an association of hyperhomocysteinemia (HHcy) and abdominal aortic aneurysm (AAA), but discrepancies exist. In addition, we lack direct evidence supporting a causal role.

OBJECTIVE

We determined the association and contribution of HHcy to AAA formation.

METHODS AND RESULTS

We first performed a meta-analysis of studies involving 1489 subjects and found a strong association of HHcy and AAA (odds ratio, 7.39). Next, we used angiotensin II-infused male apolipoprotein E-deficient mice and tested whether HHcy contributes to AAA pathogenesis. Homocysteine (Hcy) supplement (1.8 g/L) in drinking water resulted in mild HHcy. Intriguingly, HHcy greatly increased the incidence of angiotensin II-induced AAA and aortic dissection in apolipoprotein E-deficient mice (vehicle versus Hcy: 50% versus 100%; P<0.05). Histology indicated HHcy markedly exaggerated aortic adventitial inflammation. Increased levels of proinflammatory interleukin-6 and monocyte chemoattractant protein-1 were preferentially colocalized within adventitial fibroblasts in HHcy plus angiotensin II mice, which suggested the importance of adventitial fibroblasts activation in Hcy-aggravated AAA. Hcy sequentially stimulated adventitial fibroblasts transformation into myofibroblasts, secretion of interleukin-6 and monocyte chemoattractant protein-1, and consequent recruitment of monocytes/macrophages to adventitial fibroblasts, which was abolished by the NADPH oxidase inhibitor diphenyliodonium. NADPH oxidase 4, but not other homologs of NADPH oxidase, was significantly upregulated by Hcy in adventitial fibroblasts, whereas NADPH oxidase 4 small interfering RNA silencing diminished Hcy-induced adventitial fibroblasts activation. Finally, folic acid supplement (0.071 μg/g per day) markedly reduced HHcy-aggravated angiotensin II-induced AAA formation in apolipoprotein E-deficient mice.

CONCLUSIONS

HHcy may aggravate AAA formation at least partially via activating adventitial fibroblast NADPH oxidase 4.

Signaling required for blood vessel maintenance: molecular basis and pathological manifestations

As our understanding of molecular mechanisms leading to vascular formation increases, vessel maintenance including stabilization of new vessels and prevention of vessel regression began to be considered as an active process that requires specific cellular signaling. While signaling pathways such as VEGF, FGF, and angiopoietin-Tie2 are important for endothelial cell survival and junction stabilization, PDGF and TGF-β signaling modify mural cell (vascular smooth muscle cells and pericytes) functions, thus they fortify vessel integrity. Breakdown of these signaling systems results in pathological hyperpermeability and/or genetic vascular abnormalities such as vascular malformations, ultimately progressing to hemorrhage and edema. Hence, blood vessel maintenance is fundamental to controlling vascular homeostasis and tissue functions. This paper discusses signaling pathways essential for vascular maintenance and clinical conditions caused by deterioration of vessel integrity.