Fractalkine-induced smooth muscle cell proliferation in pulmonary hypertension

ERK pathway and sheddases play an essential role in ethanol-induced CX3CL1 release in pancreatic stellate cells

The clinical course of chronic pancreatitis (CP) worsens with drinking, and pancreatic stellate cells (PSCs) have an important role in the pathogenesis of alcoholic CP. Chemokines recruit inflammatory cells, resulting in chronic pancreatic inflammation. Although serum levels of fractalkine (CX3CL1) are significantly elevated in patients with alcoholic CP, the mechanism of this elevation remains unclear. This study aims to determine the effects of cytokines, pathogen-associated molecular patterns (PAMPs), and ethanol and its metabolites on CX3CL1 secretion by PSCs. Male Wistar/Bonn Kobori (WBN/Kob) rats aged 15 to 20 weeks were used as rodent models of CP in vivo. PSCs were isolated from 6-week-old male Wistar rats. The effects of cytokines, PAMPs, and ethanol and its metabolites on chemokine production and activation of signaling pathways in PSCs in vitro were examined by real-time reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and enzyme-linked immunosorbent assay. Expression of CX3CL1 and matrix metalloprotease (MMP)-2 was increased in the pancreas of WBN/Kob rats. The rat PSCs expressed CX3CL1, MMP-2, and a disintegrin and metalloprotease domain (ADAM) 17. Cytokines and PAMPs induced CX3CL1 release and activated extracellular signal-regulated kinase (ERK), MMP-9, and ADAM17. CX3CL1 release was suppressed by specific inhibitors of ERK, MMP, and ADAM, and ERK was associated with CX3CL1 transcription. Ethanol and phorbol myristate acetate synergistically increased CX3CL1 release. Real-time PCR and western blotting confirmed the synergistic activation of ERK and ADAM17. Ethanol synergistically increased CX3CL1 release via ERK and ADAM17 activation in PSCs. In conclusion, we demonstrated for the first time that ethanol synergistically increased CX3CL1 release from PSCs at least in part through activation of ERK mitogen-activated protein kinase and ADAM17. This might be one of the mechanisms of serum CX3CL1 elevation and disease progression in patients with alcoholic CP.

Varicella-zoster virus vasculopathy: immune characteristics of virus-infected arteries

OBJECTIVE

Pathologic changes in varicella-zoster virus (VZV)-infected arteries include inflammation, thickened intima, and paucity of smooth muscle cells. Since no criteria have been established for early vs late VZV vasculopathy, we examined inflammatory cells and their distribution in 6 normal arteries, and 2 VZV-infected arteries 3 days after onset of disease (early) and 10 months after protracted neurologic disease (late).

METHODS

VZV-infected temporal artery obtained 3 days after onset of ischemic optic neuropathy from an 80-year-old man, VZV-infected middle cerebral artery (MCA) obtained 10 months after protracted disease from a 73-year-old man, and 5 MCAs and 1 temporal artery from normal subjects, age 22-60 years, were examined histologically and immunohistochemically using antibodies against VZV and inflammatory cell subsets.

RESULTS

In both early and late VZV vasculopathy, T cells, activated macrophages, and rare B cells were found in adventitia and intima. In adventitia of early VZV vasculopathy, neutrophils and VZV antigen were abundant and a thickened intima was associated with inflammatory cells in vaso vasorum vessels. In media of late VZV vasculopathy, viral antigen, but not leukocytes, was found. VZV was not seen in inflammatory cells. Inflammatory cells were absent in control arteries.

CONCLUSIONS

Both VZV and neutrophils exclusively in adventitia in early VZV vasculopathy indicate that disease begins there. Late VZV vasculopathy is distinguished by viral antigen without inflammation in media, revealing a human virus in an immunoprivileged arterial media. Association of thickened intima and inflammation in vaso vasorum vessels in early VZV vasculopathy support the role of virus-induced inflammation in vessel wall remodeling.

Immune and inflammatory mechanisms in pulmonary arterial hypertension

Altered immunity and inflammation are increasingly recognized features of pulmonary arterial hypertension (PAH). This is suggested by infiltration of various inflammatory cells (e.g., macrophages, T and B lymphocytes), increased cytokine and growth factor (e.g., VEGF and PDGF) expression in remodeled pulmonary vessels, and the presence of circulating chemokines and cytokines. In certain diseases associated with PAH, increased expression of growth and transcriptional (e.g., nuclear factor of activated T cells or NFAT) factors, and viral protein components (e.g., HIV-1 Nef), appear to contribute directly to recruitment of inflammatory cells in remodeled vessels, and may potentially serve as specific therapeutic targets. This section provides an overview of inflammatory pathways highlighting their potential role in pulmonary vascular remodeling in PAH and the possibility of future targeted therapy.

Molecular pathogenesis of pulmonary arterial hypertension

Recent clinical and experimental studies are redefining the cellular and molecular bases of pulmonary arterial hypertension (PAH). The genetic abnormalities first identified in association with the idiopathic form of PAH--together with a vast increase in our understanding of cell signaling, cell transformation, and cell-cell interactions; gene expression; microRNA processing; and mitochondrial and ion channel function--have helped explain the abnormal response of vascular cells to injury. Experimental and clinical studies now converge on the intersection and interactions between a genetic predisposition involving the BMPR2 signaling pathway and an impaired metabolic and chronic inflammatory state in the vessel wall. These deranged processes culminate in an exuberant proliferative response that occludes the pulmonary arterial (PA) lumen and obliterates the most distal intraacinar vessels. Here, we describe emerging therapies based on preclinical studies that address these converging pathways.

Type I interferon induces CX3CL1 (fractalkine) and CCL5 (RANTES) production in human pulmonary vascular endothelial cells

Type I interferon (IFN) medications cause various adverse reactions, including vascular diseases. Although an association between chemokines and vascular diseases has also been reported, the relationship between type I IFN and chemokines in vascular endothelial cells (VEC) remains unclear. To provide clues to pathogenesis of the diseases, we analysed the effects of type I IFN on chemokine production in human VEC. Type I IFN induced higher CX3CL1 (fractalkine) mRNA expression and protein secretion in pulmonary arterial VEC than in umbilical vein VEC. Type I IFN also induced CCL5 [regulated upon activation normal T cell expressed and secreted (RANTES)] production in VEC, especially in lung micro-VEC. IFN-β induced much higher chemokine production than IFN-α, and Janus protein tyrosine kinase (JAK) inhibitor I prevented type I IFN-induced chemokine secretion. Type I IFN-induced chemokines may be involved in the pathophysiology of pulmonary vascular diseases, and the JAK inhibitor may serve as a therapeutic option for these diseases.

[Pulmonary hypertension: from molecular pathophysiology to haemodynamic abnormalities]

Pulmonary hypertension (PH) is a complex disorder resulting from many etiologies that cause disturbances of normal pulmonary haemodynamics. Recent breakthroughs have led to a better understanding of the pathophysiology of the disease. In PH, haemodynamic disturbances are closely linked to structural changes and excessive remodeling of pulmonary vessels, leading to progressive narrowing of the pulmonary vascular lumen. Imbalances between pulmonary vasoconstrictors and vasodilators on the one hand, and factors favoring cell proliferation and apoptosis on the other hand, probably account for most cases of PH. This review aims to update readers with the current knowledge on the molecular physiopathology of PH and how this can progress the therapeutic of this disorder.

Hypoxia-induced endothelial CX3CL1 triggers lung smooth muscle cell phenotypic switching and proliferative expansion

Distal arterioles with limited smooth muscles help maintain the high blood flow and low pressure in the lung circulation. Chronic hypoxia induces lung distal vessel muscularization. However, the molecular events that trigger alveolar hypoxia-induced peripheral endothelium modulation of vessel wall smooth muscle cell (SMC) proliferation and filling of nonmuscular areas are unclear. Here, we investigated the role of CX3CL1/CX3CR1 system in endothelial-SMC cross talk in response to hypoxia. Human lung microvascular endothelial cells responded to alveolar oxygen deficiency by overproduction of the chemokine CX3CL1. The CX3CL1 receptor CX3CR1 is expressed by SMCs that are adjacent to the distal endothelium. Hypoxic release of endothelial CX3CL1 induced SMC phenotypic switching from the contractile to the proliferative state. Inhibition of CX3CR1 prevented CX3CL1 stimulation of SMC proliferation and monolayer expansion. Furthermore, CX3CR1 deficiency attenuated spiral muscle expansion, distal vessel muscularization, and pressure elevation in response to hypoxia. Our findings indicate that the capillary endothelium relies on the CX3CL1-CX3CR1 axis to sense alveolar hypoxia and promote peripheral vessel muscularization. These results have clinical significance in the development of novel therapeutics that target mechanisms of distal arterial remodeling associated with pulmonary hypertension induced by oxygen deficiency that is present in people living at high altitudes and patients with obstructive lung diseases.

CX3CL1 in allergic diseases: not just a chemotactic molecule

Allergic asthma and atopic dermatitis (AD) are two allergic diseases that are primarily driven by the activation of T helper (Th)2 cells. Th2 cells produce cytokines that directly contribute to the symptoms of these diseases. The recruitment and maintenance of Th2 cells into the target tissues are two key events in the pathogenesis of allergic asthma and AD. While migration is mediated by both chemokines and lipid mediators such as leukotrienes and prostaglandins, very little is known about the molecules involved in lymphocyte survival and maintenance in inflamed tissues. However, chemokines could also play a role in this phenomenon. An example of this could be illustrated by CX3CL1, also known as fractalkine. CX3CL1 is a chemokine that is upregulated in some inflammatory diseases including allergic pathologies and that was recently demonstrated to provide a survival signal upon binding to its unique receptor CX3CR1.

Comparação de dois modelos experimentais de hipertensão pulmonar

OBJETIVO: Comparar dois modelos de hipertensão pulmonar (monocrotalina e monocrotalina+pneumonectomia) em relação à gravidade hemodinâmica, estrutura de artérias pulmonares, marcadores inflamatórios (IL-1 e PDGF) e sobrevida em 45 dias. MÉTODOS: Foram utilizados 80 ratos Sprague-Dawley em dois protocolos de estudo: análise estrutural e de sobrevida. Os animais foram divididos em quatro grupos: controle, monocrotalina (M), pneumonectomia (P) e monocrotalina+pneumonectomia (M+P). Para a análise estrutural, 40 animais (10/grupo) foram cateterizados após 28 dias para a medição dos valores hemodinâmicos e sacrificados, obtendo-se tecidos cardíaco e pulmonar. O ventrículo direito (VD) foi dissecado do septo interventricular (SI), e a relação do peso do VD e do peso do ventrículo esquerdo (VE) com o SI foi obtida como índice de hipertrofia de VD. No tecido pulmonar, foram realizadas análises histológicas e dosados IL-1 e PDGF por ELISA. Para o estudo de sobrevida, 40 animais (10/grupo) foram observados por 45 dias. RESULTADOS: Os grupos M e M+P apresentaram hipertensão pulmonar em relação aos demais. Houve um aumento significativo da relação VD/VE+S no grupo M+P em relação aos demais. Não houve diferenças significativas entre os grupos M e M+P quanto à área da camada média das artérias pulmonares, dosagens de IL-1 e PDGF ou sobrevida. CONCLUSÕES: Baseados nos resultados, não podemos afirmar que o modelo de monocrotalina+pneumonectomia é superior ao modelo de monocrotalina.

siRNA-based targeting of fractalkine overexpression suppresses inflammation development in a severe acute pancreatitis rat model

Fractalkine (FKN), a chemokine that acts as both an adhesion molecule and a chemoattractant, is expressed in many inflammatory diseases. Chemokines play a crucial role in severe acute pancreatitis (SAP). This study used adenovirus-mediated siRNA to target FKN overexpression and assessed its ability to suppress inflammation development in a SAP rat model. Adenovirus-mediated FKN siRNA was transfected into cerulein-stimulated AR42J cells. The growth of cerulein-stimulated AR42J cells was determined by colony formation and MTT assays. The inhibitory effect of the FKN siRNA was studied in a SAP rat model in vivo and detected by ELISA, RT-PCR, western blot analysis and immunohistochemistry. FKN, IL-8 and TNF-α were found to be overexpressed in cerulein-stimulated AR42J cells by ELISA and western blot analysis (P<0.05). The animal experiments confirmed that FKN siRNA could inhibit inflammation development in SAP. The values of serum FKN, TNF-α and IL-8 levels were decreased after FKN siRNA treatment (P<0.05). Furthermore, western blotting and RT-PCR analysis showed that FKN protein and mRNA levels were decreased after injection with FKN siRNA (P<0.05). Immunohistochemistry also showed that inflammation was decreased after injection with FKN-siRNA in the SAP rat model. Treatment with siRNA can inhibit FKN overexpression and also suppresses inflammation development in a SAP rat model. More importantly, this study indicated that FKN, which is overexpressed in the SAP rat model, may serve as a novel and effective therapeutic target for SAP.

Antagonism of CXCR7 attenuates chronic hypoxia-induced pulmonary hypertension

INTRODUCTION

Chemokines may directly participate in the pathogenesis of neonatal chronic hypoxia-induced pulmonary hypertension (PH). Although stromal-derived factor-1 (SDF-1) has been shown to be involved in PH, the role of its most recently discovered receptor, chemokine receptor type 7 (CXCR7), remains unclear. We sought to determine whether antagonism of the CXCR7 receptor would decrease pulmonary vascular remodeling in newborn mice exposed to chronic hypoxia by decreasing pulmonary vascular cell proliferation.

METHODS

Neonatal mice were exposed to hypoxia (fractional inspired oxygen concentration = 0.12) or room air (RA) for 2 wk. After 1 wk of exposure, mice received daily injections of placebo or a CXCR7 antagonist (CCX771) from postnatal day 7 (P7) to P14. Right ventricular systolic pressure (RVSP), the ratio of the weight of the right ventricle to left ventricle + septum (RV/LV + S), and pulmonary vascular cell proliferation and remodeling were determined at P14.

RESULTS

As compared with mice exposed to RA, hypoxia placebo mice had a significant increase in the lung protein expression of CXCR7. Although hypoxic placebo-treated mice had a significant increase in RVSP, RV/LV+S, and pulmonary vascular cell proliferation and remodeling, the administration of CCX771 markedly decreased these changes.

DISCUSSION

These results indicate that antagonism of CXCR7 may be a potent strategy to decrease PH and vascular remodeling.

Inflammation in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling of the precapillary pulmonary arteries, with excessive proliferation of vascular cells. Although the exact pathophysiology remains unknown, there is increasing evidence to suggest an important role for inflammation. Firstly, pathologic specimens from patients with PAH reveal an accumulation of perivascular inflammatory cells, including macrophages, dendritic cells, T and B lymphocytes, and mast cells. Secondly, circulating levels of certain cytokines and chemokines are elevated, and these may correlate with a worse clinical outcome. Thirdly, certain inflammatory conditions such as connective tissue diseases are associated with an increased incidence of PAH. Finally, treatment of the underlying inflammatory condition may alleviate the associated PAH. Underlying pathologic mechanisms are likely to be "multihit" and complex. For instance, the inflammatory response may be regulated by bone morphogenetic protein receptor type 2 (BMPR II) status, and, in turn, BMPR II expression can be altered by certain cytokines. Although antiinflammatory therapies have been effective in certain connective-tissue-disease-associated PAH, this approach is untested in idiopathic PAH (iPAH). The potential benefit of antiinflammatory therapies in iPAH is of importance and requires further study.

Fractalkine as a marker for assessment of severe acute pancreatitis

OBJECTIVE

The aim of this study was to study the role of fractalkine (FKN) in the development of severe acute pancreatitis (SAP) in animal model.

METHODS

Serum FKN levels in rat model (control, SAP6 h, 16 h, 24 h and 48 h) were determined by enzyme-linked immunosorbent assay. FKN mRNA and protein levels in the pancreas tissue were measured by reverse transcription polymerase chain reaction (RT-PCR), Western blot and immunohistochemistry.

RESULTS

Serum FKN level in the SAP rat increased significantly (P < 0.05 compared with the control group). FKN mRNA and protein levels in pancreas and lung increased significantly and reached the peak at 16 h after the induction of SAP, while those in kidney reached the peak at 48 h. Immunohistochemistry showed the overexpression of FKN in pancreas, lung and kidney tissue.

CONCLUSION

FKN involves in the progression of SAP and might be a valuable marker for the assessment of SAP.

Macrophage migration inhibitory factor contributes to hypoxic pulmonary vasoconstriction in rats

BACKGROUND

Hypoxic pulmonary vasoconstriction may lead to pulmonary hypertension, but the underlying mechanisms of persistent vasoconstriction are still unclear. There is evidence that pulmonary inflammation contributes to the abnormalities of function in the pulmonary artery (PA) following chronic hypoxia exposure. Macrophage migration inhibitory factor (MIF) is an important pro-inflammatory cytokine, and we found that expression of MIF was increased in the smooth muscle of PA from hypoxic pulmonary hypertensive rats. Therefore, the aim of the study was to investigate the role of MIF in modulating vasoreactivity of isolated PA rings.

METHODS

Sprague-Dawley rats were challenged by intermittent chronic hypoxia exposure for 4 weeks to establish hypoxic pulmonary hypertension models. Subsequently, immunohistochemistry and western blot assay were used to examine the MIF expression in pulmonary artery. Moreover, isometric force displacement was measured in isolated intrapulmonary artery.

RESULTS

In the isolated PA, our results showed that MIF mediated the enhanced pulmonary arterial vasoconstriction in response to chronic hypoxia, and the delayed hypoxic constriction in a biphasic pattern of constriction occurs in response to acute hypoxia. We also present the finding that MIF had no effect on force on its own, but concentration-dependently potentiated constrictions pre-evoked by phenylephrine under normoxic condition. The potentiation was independent of the endothelium. MIF-induced potentiation of phenylephrine-evoked constriction was partially inhibited by PKC inhibitor chelerythrine, p38 inhibitor SB 203580, ERK1/2 inhibitor U0126, respectively.

CONCLUSIONS

Our results suggested that MIF enhanced vasoconstriction of pulmonary artery elicited by agonist through PKC, p38 and ERK1/2 signal pathways, which may contributes to hypoxic pulmonary vasoconstriction.

Role of macrophage migration inhibitory factor in the proliferation of smooth muscle cell in pulmonary hypertension

Pulmonary hypertension (PH) contributes to the mortality of patients with lung and heart diseases. However, the underlying mechanism has not been completely elucidated. Accumulating evidence suggests that inflammatory response may be involved in the pathogenesis of PH. Macrophage migration inhibitory factor (MIF) is a critical upstream inflammatory mediator which promotes a broad range of pathophysiological processes. The aim of the study was to investigate the role of MIF in the pulmonary vascular remodeling of hypoxia-induced PH. We found that MIF mRNA and protein expression was increased in the lung tissues from hypoxic pulmonary hypertensive rats. Intensive immunoreactivity for MIF was observed in smooth muscle cells of large pulmonary arteries (PAs), endothelial cells of small PAs, and inflammatory cells of hypoxic lungs. MIF participated in the hypoxia-induced PASMCs proliferation, and it could directly stimulate proliferation of these cells. MIF-induced enhanced growth of PASMCs was attenuated by MEK and JNK inhibitor. Besides, MIF antagonist ISO-1 suppressed the ERK1/2 and JNK phosphorylation induced by MIF. In conclusion, the current finding suggested that MIF may act on the proliferation of PASMCs through the activation of the ERK1/2 and JNK pathways, which contributes to hypoxic pulmonary hypertension.

Different patterns of pulmonary vascular disease induced by type 1 diabetes and moderate hypoxia in rats

Although type 1 and type 2 diabetes are strongly associated with systemic cardiovascular morbidity, the relationship with pulmonary vascular disease had been almost disregarded until recent epidemiological data revealed that diabetes might be a risk factor for pulmonary hypertension. Recent experimental studies suggest that diabetes induces changes in lung function insufficient to elevate pulmonary pressure. The aim of this study was to assess the effects of diabetes on the sensitivity to other risk factors for pulmonary hypertension. We therefore analysed the effects of the combination of diabetes with exposure to moderate hypoxia on classical markers of pulmonary hypertension. Control (saline-treated) and diabetic (70 mg kg(-1) streptozotocin-treated) male Wistar-Kyoto rats were followed for 4 weeks and exposed to normoxia or moderate normobaric hypoxia (14%) for another 2 weeks. Hypoxia, but not diabetes, strongly reduced voltage-gated potassium currents, whereas diabetes, but not hypoxia, induced pulmonary artery endothelial dysfunction. Both factors independently induced pulmonary vascular remodelling and downregulated the lung bone morphogenetic protein receptor type 2. However, diabetes, but not hypoxia, induced pulmonary infiltration of macrophages, which was markedly increased when both factors were combined. Diabetes plus hypoxia induced a modest increase in diastolic and mean pulmonary artery pressure and right ventricular weight, while each of the two factors alone had no significant effect. The pattern of changes in markers of pulmonary hypertension was different for moderate hypoxia and diabetes, with no synergic effect except for macrophage recruitment, and the combination of both factors was required to induce a moderate elevation in pulmonary arterial pressure.

Pulmonary lymphoid neogenesis in idiopathic pulmonary arterial hypertension

RATIONALE

Patients with idiopathic pulmonary arterial hypertension (IPAH) present circulating autoantibodies against vascular wall components. Pathogenic antibodies may be generated in tertiary (ectopic) lymphoid tissues (tLTs).

OBJECTIVES

To assess the frequency of tLTs in IPAH lungs, as compared with control subjects and flow-induced PAH in patients with Eisenmenger syndrome, and to identify local mechanisms responsible for their formation, perpetuation, and function.

METHODS

tLT composition and structure were studied by multiple immunostainings. Cytokine/chemokine and growth factor expression was quantified by real-time polymerase chain reaction and localized by immunofluorescence. The systemic mark of pulmonary lymphoid neogenesis was investigated by flow cytometry analyses of circulating lymphocytes.

MEASUREMENTS AND MAIN RESULTS

As opposed to lungs from control subjects and patients with Eisenmenger syndrome, IPAH lungs contained perivascular tLTs, comprising B- and T-cell areas with high endothelial venules and dendritic cells. Lymphocyte survival factors, such as IL-7 and platelet-derived growth factor-A, were expressed in tLTs as well as the lymphorganogenic cytokines/chemokines, lymphotoxin-α/-β, CCL19, CCL20, CCL21, and CXCL13, which might explain the depletion of circulating CCR6(+) and CXCR5(+) lymphocytes. tLTs were connected with remodeled vessels via an ER-TR7(+) stromal network and supplied by lymphatic channels. The presence of germinal center centroblasts, follicular dendritic cells, activation-induced cytidine deaminase, and IL-21(+)PD1(+) follicular helper T cells in tLTs together with CD138(+) plasma cell accumulation around remodeled vessels in areas of immunoglobulin deposition argued for local immunoglobulin class switching and ongoing production.

CONCLUSIONS

We highlight the main features of lymphoid neogenesis specifically in the lungs of patients with IPAH, providing new evidence of immunological mechanisms in this severe condition.

Paigen diet-fed apolipoprotein E knockout mice develop severe pulmonary hypertension in an interleukin-1-dependent manner

Inflammatory mechanisms are proposed to play a significant role in the pathogenesis of pulmonary arterial hypertension (PAH). Previous studies have described PAH in fat-fed apolipoprotein E knockout (ApoE(-/-)) mice. We have reported that signaling in interleukin-1-receptor-knockout (IL-1R1(-/-)) mice leads to a reduction in diet-induced systemic atherosclerosis. We subsequently hypothesized that double-null (ApoE(-/-)/IL-1R1(-/-)) mice would show a reduced PAH phenotype compared with that of ApoE(-/-) mice. Male IL-1R1(-/-), ApoE(-/-), and ApoE(-/-)/IL-1R1(-/-) mice were fed regular chow or a high-fat diet (Paigen diet) for 8 weeks before phenotyping for PAH. No abnormal phenotype was observed in the IL-1R1(-/-) mice. Fat-fed ApoE(-/-) mice developed significantly increased right ventricular systolic pressure and substantial pulmonary vascular remodeling. Surprisingly, ApoE(-/-)/IL-1R1(-/-) mice showed an even more severe PAH phenotype. Further molecular investigation revealed the expression of a putative, alternatively primed IL-1R1 transcript expressed within the lungs but not aorta of ApoE(-/-)/IL-1R1(-/-) mice. Treatment of ApoE(-/-) and ApoE(-/-)/IL-1R1(-/-) mice with IL-1-receptor antagonist prevented progression of the PAH phenotype in both strains. Blocking IL-1 signaling may have beneficial effects in treating PAH, and alternative IL-1-receptor signaling in the lung may be important in driving PAH pathogenesis.

Identification of the chemokine CX3CL1 as a new regulator of malignant cell proliferation in epithelial ovarian cancer

Background

Little is known about the molecules that contribute to the growth of epithelial ovarian carcinomas (EOC), which remain the most lethal gynecological cancer in women. The chemokine Fractalkine/CX₃CL1 has been widely reported to play a biologically relevant role in tumor growth and spread. We report here the first investigation of the expression and role of CX₃CL1 in EOC.

Results

Epithelial cells from the surface of the ovary and the Fallopian tubes and from benign, borderline and malignant tumors all stained positive for CX₃CL1. In tumor specimens from 54 women who underwent surgical treatment for EOC diagnosis, CX₃CL1 immunoreactivity was unevenly distributed in epithelial tumor cells, and ranged from strong (33%) to absent (17%). This uneven distribution of CX₃CL1 did not reflect the morphological heterogeneity of EOC. It was positively correlated with the proliferation index Ki-67 and with GILZ (glucocorticoid-induced leucine zipper), previously identified as an activator of the proliferation of malignant EOC cells. Hierarchical clustering analysis, including age at diagnosis, tumor grade, FIGO stage, Ki-67 index, CX₃CL1, SDF-1/CXCL12 and GILZ immunostaining scores, distinguished two major clusters corresponding to low and high levels of proliferation and differing in terms of GILZ and CX₃CL1 expression. GILZ overexpression in the carcinoma-derived BG1 cell line resulted in parallel changes in CX₃CL1 products. Conversely, CX₃CL1 promoted through its binding to CX₃CR1 AKT activation and proliferation in BG1 cells. In a mouse subcutaneous xenograft model, the overexpression of GILZ was associated with higher expression of CX₃CL1 and faster tumor growth.

Conclusion

Our findings highlight the previously unappreciated constitutive expression of CX₃CL1 preceding tumorigenesis in ovarian epithelial cells. Together with GILZ, this chemokine emerges as a regulator of cell proliferation, which may be of potential clinical relevance for the selection of the most appropriate treatment for EOC patients.

Mechanisms of disease: pulmonary arterial hypertension

Our understanding of, and approach to, pulmonary arterial hypertension has undergone a paradigm shift in the past decade. Once a condition thought to be dominated by increased vasoconstrictor tone and thrombosis, pulmonary arterial hypertension is now seen as a vasculopathy in which structural changes driven by excessive vascular cell growth and inflammation, with recruitment and infiltration of circulating cells, play a major role. Perturbations of a number of molecular mechanisms have been described, including pathways involving growth factors, cytokines, metabolic signaling, elastases, and proteases, that may underlie the pathogenesis of the disease. Elucidating their contribution to the pathophysiology of pulmonary arterial hypertension could offer new drug targets. The role of progenitor cells in vascular repair is also under active investigation. The right ventricular response to increased pressure load is recognized as critical to survival and the molecular mechanisms involved are attracting increasing interest. The challenge now is to integrate this new knowledge and explore how it can be used to categorize patients by molecular phenotype and tailor treatment more effectively.

Pediatric pulmonary arterial hypertension: current and emerging therapeutic options

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a rare disease in neonates, infants and children that is associated with significant morbidity and mortality. An adequate understanding of the controlling pathophysiologic mechanisms is lacking and although mortality has decreased as therapeutic options have increased over the past several decades, outcomes remain unacceptable.

AREAS COVERED

This review summarizes the currently available therapies for neonates, infants and children with PAH and describes emerging therapies in the context of what is known about the underlying pathophysiology of the disease.

EXPERT OPINION

All of the currently approved PAH therapies impact one of three endothelial-based pathways: nitric oxide-guanosine-3'-5'cyclic monophosphate, prostacyclin or endothelin-1. The beneficial effects of these agents may relate to their impact on pulmonary vascular tone, and/or their antiproliferative and antithrombotic properties. Fundamental advances in PAH therapy are likely to relate to: i) a better understanding of PAH subpopulations, allowing for therapies to be better tailored to individual patients and pathophysiologic processes; and ii) therapies that promote the regression of advanced structural remodeling.

[Novel immunopathological approaches to pulmonary arterial hypertension]

Inflammation is important for the initiation and the maintenance of vascular remodeling in the most commun animal models of pulmonary hypertension (PH), and its therapeutical targeting blocks PH development in these models. In human, pulmonary vascular lesions of PH are also the source of an intense chemokine production, linked to inflammatory cell recruitment. However, arteritis is uncommon in PH patients. Of note, current PH treatments have immunomodulatory properties. In addition, some studies have shown a correlation between levels of circulating inflammatory mediators and patients' survival. The study of autoimmunity in the pathophysiology of pulmonary arterial hypertension is becoming an area of intense investigation. New immunopathological approaches to PH should allow the development of innovative treatments for this very severe condition.

Pulmonary vascular disease associated with parasitic infection--the role of schistosomiasis

Parasitic diseases have been known to cause pulmonary vascular lesions. Schistosomiasis is the most common parasitic disease associated with pulmonary arterial hypertension, although other trematodes have been implicated. Systematic evaluation of and interest in this problem have been rekindled because of the current availability of pulmonary arterial hypertension treatment.

Lack of CCR7 induces pulmonary hypertension involving perivascular leukocyte infiltration and inflammation

The chemokine receptor CCR7 regulates lymphocyte trafficking, and CCR7 deficiency induces infiltration of T and B cells adjacent to vessels in mouse lungs. Perivascular infiltration of T and B cells has also been found in human pulmonary arterial hypertension, and downregulation of the CCR7 receptor in circulating leukocytes of such patients has been observed. To investigate whether changes in the CCR7 system contribute to the pathogenesis of pulmonary hypertension, we utilized mice deficient of the CCR7 receptor. The cardiopulmonary and inflammatory responses of CCR7 depletion were evaluated in CCR7-deficient and wild-type mice. Measurements of cytokines upregulated in the animal model were also performed in patients with pulmonary hypertension and controls and in vascular smooth muscle cells. We found that mice lacking CCR7 had increased right ventricular systolic pressure, reduced pulmonary artery acceleration time, increased right ventricular/tibial length ratio, Rho kinase-mediated pulmonary vasoconstriction, and increased muscularization of distal arteries, indicating pulmonary hypertension. These mice also showed increased perivascular infiltration of leukocytes, consisting mainly of T and B cells, and increased mRNA levels of the inflammatory cytokines interleukin-12 and CX3CL1 within pulmonary tissue. Increased serum levels of interleukin-12 and CX3CL1 were also observed in patients with pulmonary hypertension, particularly in those with pulmonary hypertension associated with connective tissue disorder. In smooth muscle cells, interleukin-12 induced secretion of the angiogenic cytokine interleukin-8. We conclude that these results suggest a role for CCR7 in the development of pulmonary arterial hypertension, at least in some subgroups, possibly via pulmonary infiltration of lymphocytes and secretion of interleukin-12 and CX3CL1.

Delta chemokine (fractalkine)--a novel mediator of pulmonary arterial hypertension in children undergoing cardiac surgery

BACKGROUND

Fractalkine (FKN), a unique chemokine associated with pulmonary hypertension, may be involved in the acute stress response that regulates inflammation after cardiopulmonary bypass (CPB) surgery. We characterized FKN levels and correlated them with clinical parameters in children undergoing cardiac surgery involving CPB.

METHODS

Twenty-seven consecutive patients, aged 30 days to 11.5 years, who underwent surgery for correction of congenital heart defects, were prospectively studied. Serial blood samples were collected preoperatively, upon termination of CPB, and at six points postoperatively. Plasma was recovered immediately, aliquoted, and frozen at -70° C until assayed. Clinical and laboratory data were collected.

RESULTS

Baseline FKN levels were skewed between patients. Patients with low FKN levels showed significantly higher levels of oxygen saturation in room air compared to patients with high FKN levels (p<0.05). Moreover, there was a positive correlation between preoperative pulmonary arterial hypertension and FKN levels (p<0.05). Surprisingly, FKN elevation from preoperative to postoperative levels displayed no discernible pattern.

CONCLUSIONS

FKN levels significantly correlate with preoperative hypoxemia and PAH, suggesting that FKN may be up-regulated during hypoxemia. CPB is not associated with acute changes in circulating FKN levels. The role of FKN in the postoperative course should be further investigated.

Dexamethasone attenuates development of monocrotaline-induced pulmonary arterial hypertension

Immunity and inflammation are well established factors in the pathogenesis of pulmonary arterial hypertension (PAH). We aimed to investigate whether dexamethasone (Dex), a potent immunosuppressant, could prevent the development of monocrotaline (MCT)-induced PAH in rats as compared with pyrrolidine dithiocarbamate (PDTC) and its effect on the immune mechanism. PAH in rats (n = 66) was induced by MCT (50 mg/kg) injected intraperitoneally. Two days after MCT treatment, Dex (1.0 mg/kg) and PDTC (100 mg/kg) were administered once daily for 21 days. Samples were collected at 7, 14, and 21 days. Dex effectively inhibited MCT-induced PAH and reduced the T-helper (Th) 1 dominant cytokine response (interferon-γ) but up-regulated the Th2 one (interleukin 4). It increased the number of CD4+ T cells and decreased the number of CD8+ T cells around pulmonary arteries, upregulated the mRNA expression of fractalkine and downregulated that of CX3CR1 in the lung. Serum levels of interferon γ and interleukin 4 did not significantly differ from that of controls. Dex attenuated the process of MCT-induced PAH through its immunomodulatory property. Dex could be an appropriate therapy for PAH, although more studies are needed to define the appropriate treatment regimen.

Role of phosphodiesterases in adult-onset pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by increased mean pulmonary artery pressure (mPAP) due to vasoconstriction and structural changes in the small pulmonary arteries (PAs); proliferation of pulmonary artery smooth muscle cells (PASMCs) contributes to the remodeling. The abnormal pathophysiology in the pulmonary vasculature relates to decreased cyclic nucleotide levels in PASMCs. Phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP and cGMP, thereby PDE inhibitors are effective in vasodilating the PA and decreasing PASMC proliferation. Experimental studies support the use of PDE3, PDE5, and PDE1 inhibitors in PAH. PDE5 inhibitors such as sildenafil are clinically approved to treat different forms of PAH and lower mPAP, increase functional capacity, and decrease right ventricular hypertrophy, without decreasing systemic arterial pressure. New evidence suggests that the combination of PDE inhibitors with other therapies for PAH may be beneficial in treating the disease. Furthermore, inhibiting PDEs in the heart and the inflammatory cells that infiltrate the PA may offer new targets to reduce right ventricular hypertrophy and inhibit inflammation that is associated with and contributes to the development of PAH. This chapter summarizes the advances in the area and the future of PDEs in PAH.

Is peroxisome proliferator-activated receptor gamma (PPARγ) a therapeutic target for the treatment of pulmonary hypertension?

Pulmonary hypertension (PH), a progressive disorder associated with significant morbidity and mortality, is caused by complex pathways that culminate in structural and functional alterations of the pulmonary circulation and increases in pulmonary vascular resistance and pressure. Diverse genetic, pathological, or environmental triggers stimulate PH pathogenesis culminating in vasoconstriction, cell proliferation, vascular remodeling, and thrombosis. We conducted a thorough literature review by performing MEDLINE searches via PubMed to identify articles pertaining to PPARγ as a therapeutic target for the treatment of PH. This review examines basic and preclinical studies that explore PPARγ and its ability to regulate PH pathogenesis. Despite the current therapies that target specific pathways in PH pathogenesis, including prostacyclin derivatives, endothelin-receptor antagonists, and phosphodiesterase type 5 inhibitors, morbidity and mortality related to PH remain unacceptably high, indicating the need for novel therapeutic approaches. Consequently, therapeutic targets that simultaneously regulate multiple pathways involved in PH pathogenesis have gained attention. This review focuses on peroxisome proliferator-activated receptor gamma (PPARγ), a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. While the PPARγ receptor is best known as a master regulator of lipid and glucose metabolism, a growing body of literature demonstrates that activation of PPARγ exerts antiproliferative, antithrombotic, and vasodilatory effects on the vasculature, suggesting its potential efficacy as a PH therapeutic target.

Progenitor cells in pulmonary vascular remodeling

Pulmonary hypertension is characterized by cellular and structural changes in the walls of pulmonary arteries. Intimal thickening and fibrosis, medial hypertrophy and fibroproliferative changes in the adventitia are commonly observed, as is the extension of smooth muscle into the previously non-muscularized vessels. A majority of these changes are associated with the enhanced presence of α-SM-actin+ cells and inflammatory cells. Atypical abundances of functionally distinct endothelial cells, particularly in the intima (plexiform lesions), and also in the perivascular regions, are also described. At present, neither the origin(s) of these cells nor the molecular mechanisms responsible for their accumulation, in any of the three compartments of the vessel wall, have been fully elucidated. The possibility that they arise from either resident vascular progenitors or bone marrow-derived progenitor cells is now well established. Resident vascular progenitor cells have been demonstrated to exist within the vessel wall, and in response to certain stimuli, to expand and express myofibroblastic, endothelial or even hematopoietic markers. Bone marrow-derived or circulating progenitor cells have also been shown to be recruited to sites of vascular injury and to assume both endothelial and SM-like phenotypes. Here, we review the data supporting the contributory role of vascular progenitors (including endothelial progenitor cells, smooth muscle progenitor cells, pericytes, and fibrocytes) in vascular remodeling. A more complete understanding of the processes by which progenitor cells modulate pulmonary vascular remodeling will undoubtedly herald a renaissance of therapies extending beyond the control of vascular tonicity and reduction of pulmonary artery pressure.

New therapies for pulmonary arterial hypertension: an update on current bench to bedside translation

IMPORTANCE OF THE FIELD

Treatments of pulmonary arterial hypertension (PAH) that have so far proven efficacious are all based on the restoration of endothelium control of pulmonary vascular tone and structure, by administration of prostacyclins, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. However, results remain unsatisfactory, with persistent high mortality, insufficient clinical improvement and no convincing report of any reversal of the disease process.

AREAS COVERED IN THIS REVIEW

New antiproliferative approaches that aim to actively limit pulmonary vascular remodeling are being sought. Several such treatments have shown promise in experimental models and in preliminary clinical studies. Noteworthy among these are dichloroacetate, survivin antagonists, nuclear factor of activated T-cell inhibitors, PPAR-gamma agonists, tyrosine kinase inhibitors, Rho-kinase inhibitors, statins, vasoactive intestinal peptide, soluble guanylate cyclase stimulators/activators, adrenomedullin, elastase inhibitors, serotonin reuptake inhibitors, anti-inflammatory agents, and bone marrow-derived progenitor cells.

WHAT THE READER WILL GAIN

Update on various strategies targeting proliferative, inflammatory and regenerating processes currently under evaluation in patients with PAH.

TAKE HOME MESSAGE

In spite of favorable results in experimental models, none of these strategies has achieved the ultimate goal of curing PAH. Further developments will depend on progress made in our pathobiological understanding of the disease and carefully designed randomized, controlled trials.

Systemic corticosteroids as first-line treatment in pulmonary hypertension associated with POEMS syndrome

The POEMS syndrome is a rare plasma cell disease. Pulmonary hypertension is an infrequent respiratory complication of this syndrome and might be associated with increased levels of various cytokines, chemokines and growth factors as part of the inflammatory phenomena that involve the physiopathology of POEMS syndrome. We present the case of a 54-year-old woman diagnosed with POEMS syndrome and pulmonary hypertension, which were treated with corticosteroids as the first-line therapy. The patient presented with the classic symptoms of this syndrome: polyneuropathy (confirmed by electromyography), organomegaly, subclinical hypothyroidism and monoclonal gammopathy detected in urine, together with skin changes. Right heart catheterization revealed a mean pulmonary artery pressure of 48 mmHg, a cardiac output of 4.1 L/min and pulmonary vascular resistance of 8.05 Woods. The serum level of brain natriuretic peptide (BNP) was 150 pg/mL. No other underlying disease was found during the investigation. Prednisone (1 mg/kg for three months) was then initiated, with a dramatic improvement in the clinical and functional condition. Levels of thyroid hormones and urinary protein levels (as determined using electrophoresis) normalized. Mean pulmonary artery pressure decreased to 26 mmHg, cardiac output decreased to 3.8 L/min, and pulmonary vascular resistance decreased to 2.89 Woods. Serum levels of BNP dropped to 8 pg/mL. Our findings suggest that corticosteroids could play a role as a first-line treatment in pulmonary hypertension accompanied by POEMS syndrome. Due to the rarity of this presentation, a multicenter registry should be developed to allow the compilation of additional data to support this practice.

[Eisenmenger syndrome. Pathophysiology]

Eisenmenger syndrome is the most feared complication by patients with congenital heart disorders with left-to-right shunt. This complication became rare in industrial countries thanks to optimized perinatal patient management and precocious elimination of the shunt. The presence of endothelial circulatory cells is a poor prognosis factor.

Role of CX3C-chemokine CX3C-L/fractalkine expression in a model of slowly progressive renal failure

BACKGROUND

The chemokine/chemokine receptor pair CX(3)C-L/CX(3)C-R is suspected to play a role in renal fibrogenesis. The aim of this study was to investigate their function in an animal model of slowly progressive chronic renal failure.

METHODS

Functional data were analysed in folic acid nephropathy (FAN) at different time points (up to day 142 after induction). Immunostaining for CX(3)C-L, CD3, S100A4, collagen type I, fibronectin, alpha-smooth muscle actin, Tamm-horsfall protein, aquaporin 1 and 2 as well as quantitative real-time PCR (qRT-PCR) for CX(3)C-L, CX(3)C-R and fibroblast-specific protein 1 (FSP-1) were performed. Additionally, regulatory mechanisms and functional activity of CX(3)C-L in murine proximal and distal tubular epithelial cells as well as in fibroblasts were investigated.

RESULTS

CX(3)C-L/GAPDH ratio was upregulated in FAN 3.4-fold at day 7 further increasing up to 7.1-fold at day 106. The expression of mRNA CX(3)C-L correlated well with CX(3)C-R (R(2) = 0.96), the number of infiltrating CD3+ cells (R(2) = 0.60) and the degree of tubulointerstitial fibrosis (R(2) = 0.56) and moderately with FSP-1 (R(2) = 0.33). Interleukin-1beta, tumour necrosis factor-alpha, transforming growth factor-beta as well as the reactive oxygen species (ROS) H(2)O(2) were identified by qRT-PCR as inductors of CX(3)C-L/fractalkine (FKN) in tubular epithelial cells. Functionally, CX(3)C-L/FKN chemoattracts peripheral blood mononuclear cells, activates several aspects of fibrogenesis and induces the mitogen-activated protein kinases in renal fibroblasts.

CONCLUSIONS

In FAN, there is a good correlation between the expression of CX(3)C-L with markers of interstitial inflammation and fibrosis which may result from upregulation by pro-inflammatory and pro-fibrotic cytokines as well as by ROS in tubular epithelial cells. The FKN system may promote renal inflammation and renal fibrogenesis.

Inflammation, growth factors, and pulmonary vascular remodeling

Inflammatory processes are prominent in various types of human and experimental pulmonary hypertension (PH) and are increasingly recognized as major pathogenic components of pulmonary vascular remodeling. Macrophages, T and B lymphocytes, and dendritic cells are present in the vascular lesions of PH, whether in idiopathic pulmonary arterial hypertension (PAH) or PAH related to more classical forms of inflammatory syndromes such as connective tissue diseases, human immunodeficiency virus (HIV), or other viral etiologies. Similarly, the presence of circulating chemokines and cytokines, viral protein components (e.g., HIV-1 Nef), and increased expression of growth (such as vascular endothelial growth factor and platelet-derived growth factor) and transcriptional (e.g., nuclear factor of activated T cells or NFAT) factors in these patients are thought to contribute directly to further recruitment of inflammatory cells and proliferation of smooth muscle and endothelial cells. Other processes, such as mitochondrial and ion channel dysregulation, seem to convey a state of cellular resistance to apoptosis; this has recently emerged as a necessary event in the pathogenesis of pulmonary vascular remodeling. Thus, the recognition of complex inflammatory disturbances in the vascular remodeling process offers potential specific targets for therapy and has recently led to clinical trials investigating, for example, the use of tyrosine kinase inhibitors. This paper provides an overview of specific inflammatory pathways involving cells, chemokines and cytokines, cellular dysfunctions, growth factors, and viral proteins, highlighting their potential role in pulmonary vascular remodeling and the possibility of future targeted therapy.

Sustained hypoxia promotes the development of a pulmonary artery-specific chronic inflammatory microenvironment

Recent studies demonstrate that sustained hypoxia induces the robust accumulation of leukocytes and mesenchymal progenitor cells in pulmonary arteries (PAs). Since the factors orchestrating hypoxia-induced vascular inflammation are not well-defined, the goal of this study was to identify mediators potentially responsible for recruitment to and retention and differentiation of circulating cells within the hypoxic PA. We analyzed mRNA expression of 44 different chemokine/chemokine receptor, cytokine, adhesion, and growth and differentiation genes in PAs obtained via laser capture microdissection in adjacent lung parenchyma and in systemic arteries by RT-PCR at several time points of hypoxic exposure (1, 7, and 28 days) in Wistar-Kyoto rats. Analysis of inflammatory cell accumulation and protein expression of selected genes was concomitantly assessed by immunochemistry. We found that hypoxia induced progressive accumulation of monocytes and dendritic cells in the vessel wall with few T cells and no B cells or neutrophils. Upregulation of stromal cell-derived factor-1 (SDF-1), VEGF, growth-related oncogene protein-alpha (GRO-alpha), C5, ICAM-1, osteopontin (OPN), and transforming growth factor-beta (TGF-beta) preceded mononuclear cell influx. With time, a more complex pattern of gene expression developed with persistent upregulation of adhesion molecules (ICAM-1, VCAM-1, and OPN) and monocyte/fibrocyte growth and differentiation factors (TGF-beta, endothelin-1, and 5-lipoxygenase). On return to normoxia, expression of many genes (including SDF-1, monocyte chemoattractant protein-1, C5, ICAM-1, and TGF-beta) rapidly returned to control levels, changes that preceded the disappearance of monocytes and reversal of vascular remodeling. In conclusion, sustained hypoxia leads to the development of a complex, PA-specific, proinflammatory microenvironment capable of promoting recruitment, retention, and differentiation of circulating monocytic cell populations that contribute to vascular remodeling.

Molecular pathogenesis of pulmonary arterial hypertension

Recent investigations have suggested that it might be possible to reverse the pathology of pulmonary arterial hypertension (PAH), a disorder that can be rapidly progressive and fatal despite current treatments including i.v. prostacyclin. This review will address the cellular and molecular processes implicated in clinical, genetic, and experimental studies as underlying the pulmonary vascular abnormalities associated with PAH. Emerging treatments are aimed at inducing apoptosis of abnormal vascular cells that obstruct blood flow and at promoting regeneration of "lost" distal vasculature.

Endothelial cell dysfunction and cross talk between endothelium and smooth muscle cells in pulmonary arterial hypertension

The pathogenesis of pulmonary arterial hypertension (PAH) involves a complex and multifactorial process in which endothelial cell dysfunction appears to play an integral role in mediating the structural changes in the pulmonary vasculature. Disordered endothelial cell proliferation along with concurrent neoangiogenesis, when exuberant, results in the formation of glomeruloid structures known as the plexiform lesions, which are common pathological features of the pulmonary vessels of patients with PAH. In addition, an altered production of various endothelial vasoactive mediators, such as nitric oxide, prostacyclin, endothelin-1, serotonin, chemokines and thromboxane, has been increasingly recognized in patients with PAH. Because most of these mediators affect the growth of the smooth muscle cells, an alteration in their production may facilitate the development of pulmonary vascular hypertrophy and structural remodeling characteristic of PAH. It is conceivable that the beneficial effects of many of the treatments currently available for PAH, such as the use of prostacyclin, nitric oxide, and endothelin receptor antagonists, result at least in part from restoring the balance between these mediators. A greater understanding of the role of the endothelium in PAH will presumably facilitate the evolution of newer, targeted therapies.

Cytokine expression profiling of the myocardium reveals a role for CX3CL1 (fractalkine) in heart failure

Several lines of evidence suggest that inflammatory processes mediated by cytokines are involved in the pathogenesis of heart failure (HF). However, the regulation of cytokine expression and the role of cytokines during HF development are not well understood. To address this issue, we have examined alterations in gene expression during HF progression by microarray technology in non-infarcted left ventricular (LV) murine tissue at various time points after myocardial infarction (MI). The highest number of regulated genes was found five days after MI. In total, we identified 14 regulated genes encoding cytokines with no previous association to HF. The strongest up-regulation was found for the chemokine fractalkine (CX3CL1). In human failing hearts we detected a 3-fold increase in CX3CL1 protein production, and both cardiomyocytes and fibrous tissue revealed immunoreactivity for CX3CL1 and its specific receptor CX3CR1. We also found that the circulating level of CX3CL1 was increased in patients with chronic HF in accordance with disease severity (1.6-fold in NYHA II, 2.2-fold in NYHA III and 2.9-fold in NYHA IV). In vitro experiments demonstrated that CX3CL1 production could be induced by inflammatory cytokines known to be highly expressed in HF. CX3CL1 itself induced the expression of markers of cardiac hypertrophy and protein phosphatases in neonatal cardiomyocytes. Given the increased CX3CL1 production in both an experimental HF model and in patients with chronic HF as well as its direct effects on cardiomyocytes, we suggest a role for CX3CL1 and its receptor CX3CR1 in the pathogenesis of HF.

Remodeling of extra-bronchial lung vasculature following allergic airway inflammation

Background

We previously observed that allergen-exposed mice exhibit remodeling of large bronchial-associated blood vessels. The aim of the study was to examine whether vascular remodeling occurs also in vessels where a spill-over effect of bronchial remodeling molecules is less likely.

Methods

We used an established mouse model of allergic airway inflammation, where an allergic airway inflammation is triggered by inhalations of OVA. Remodeling of bronchial un-associated vessels was determined histologically by staining for α-smooth muscle actin, procollagen I, Ki67 and von Willebrand-factor. Myofibroblasts were defined as and visualized by double staining for α-smooth muscle actin and procollagen I. For quantification the blood vessels were divided, based on length of basement membrane, into groups; small (≤250 μm) and mid-sized (250–500 μm).

Results

We discovered marked remodeling in solitary small and mid-sized blood vessels. Smooth muscle mass increased significantly as did the number of proliferating smooth muscle and endothelial cells. The changes were similar to those previously seen in large bronchial-associated vessels. Additionally, normally poorly muscularized blood vessels changed phenotype to a more muscularized type and the number of myofibroblasts around the small and mid-sized vessels increased following allergen challenge.

Conclusion

We demonstrate that allergic airway inflammation in mice is accompanied by remodeling of small and mid-sized pulmonary blood vessels some distance away (at least 150 μm) from the allergen-exposed bronchi. The present findings suggest the possibility that allergic airway inflammation may cause such vascular remodeling as previously associated with lung inflammatory conditions involving a risk for development of pulmonary hypertension.

Interleukin-15 inhibits smooth muscle cell proliferation and hyaluronan production in rat ductus arteriosus

Neointimal cushion formation (NCF) is an important vascular remodeling for anatomical closure of the ductus arteriosus (DA). Inflammatory responses to vascular injury or atherosclerosis are known to be associated with the pathogenesis of NCF. We found that the expression of interleukin (IL)-15 mRNA was significantly higher in rat DA than in the aorta. IL-15 immunoreactivity was detected predominantly in the internal elastic laminae (IEL) and to a lesser extent in smooth muscle cells (SMCs) in rat DA. Prostaglandin E (PGE) increased the expression of IL-15 mRNA in cultured DA SMCs. IL-15 significantly attenuated the platelet-derived growth factor (PDGF)-BB-mediated SMC proliferation, but did not change SMC migration. IL-15 significantly attenuated PGE1-induced hyaluronic acid (HA) production in a dose-dependent manner, which is a potent stimulator of NCF. Accordingly, IL-15 might have an inhibitory effect on the physiologic vascular remodeling processes in closing the DA.