IgE has a key role in the pathogenesis of allergic responses through its ability to activate mast cells via the receptor FcεR1. In addition to mast cells, many cell types implicated in atherogenesis express FcεR1, but whether IgE has a role in this disease has not been determined. Here, we demonstrate that serum IgE levels are elevated in patients with myocardial infarction or unstable angina pectoris. We found that IgE and the FcεR1 subunit FcεR1α were present in human atherosclerotic lesions and that they localized particularly to macrophagerich areas. In mice, absence of FcεR1α reduced inflammation and apoptosis in atherosclerotic plaques and reduced the burden of disease. In cultured macrophages, the presence of TLR4 was required for FcεR1 activity. IgE stimulated the interaction between FcεR1 and TLR4, thereby inducing macrophage signal transduction, inflammatory molecule expression, and apoptosis. These IgE activities were reduced in the absence of FcεR1 or TLR4. Furthermore, IgE activated macrophages by enhancing Na + /H + exchanger 1 (NHE1) activity. Inactivation of NHE1 blocked IgE-induced macrophage production of inflammatory molecules and apoptosis. Cultured human aortic SMCs (HuSMCs) and ECs also exhibited IgE-induced signal transduction, cytokine expression, and apoptosis. In human atherosclerotic lesions, SMCs and ECs colocalized with IgE and TUNEL staining. This study reveals what we believe to be several previously unrecognized IgE activities that affect arterial cell biology and likely other IgE-associated pathologies in human diseases.

We recently found that low-molecular-weight hyaluronan was induced by cyclic stretch in lung fibroblasts and accumulated in lungs from animals with ventilator-induced lung injury. The low-molecularweight hyaluronan produced by stretch increased interleukin-8 production in epithelial cells, and was accompanied by an upregulation of hyaluronan synthase-3 mRNA. We hypothesized that lowmolecular-weight hyaluronan induced by high VT was dependent on hyaluronan synthase 3, and was associated with ventilator-induced lung injury. Effects of high VT ventilation in C57BL/6 wild-type and hyaluronan synthase-3 knockout mice were compared. Significantly increased neutrophil infiltration, macrophage inflammatory protein-2 production, and lung microvascular leak were found in wild-type animals ventilated with high VT. These reactions were significantly reduced in hyaluronan synthase-3 knockout mice, except the capillary leak. Wild-type mice ventilated with high VT were found to have increased low-molecular-weight hyaluronan in lung tissues and concomitant increased expression of hyaluronan synthase-3 mRNA, neither of which was found in hyaluronan synthase-3 knockout mice. We conclude that high VT induced lowmolecular-weight hyaluronan production is dependent on de novo synthesis through hyaluronan synthase 3, and plays a role in the inflammatory response of ventilator-induced lung injury.Keywords: hyaluronic acid; knockout mice; mechanical ventilation; tidal volumeThe management of acute lung injury and acute respiratory distress syndrome (ARDS) requires the use of positive-pressure ventilation to provide adequate oxygenation. When ARDS develops, the lungs are affected nonhomogeneously, which leads to areas with different compliance. As the low compliant areas increase, the uneven distribution delivered by traditional or even smaller tidal volumes (Vt) will result in overdistension of those normal, compliant areas. A clinical trial by the ARDS Network has documented that mechanical ventilation with a smaller Vt (6 m/kg) decreased the mortality rate in patients with ARDS (1), suggesting the potential role of conventional Vt in lung injury. Ventilator-induced lung injury (VILI) has been studied in different animal models with high Vt ventilation (2-4). It has been characterized by neutrophil sequestration, increased vascular permeability, and elevated levels of chemoattractant cytokines, particularly macrophage inflammatory protein 2 (MIP-2), the (Received in original form May 19, 2004; accepted in final form March 18, 2005) Supported by the National Institutes of Health grants HL03920, 2T32HL07874, and funds from the Texas A&M University System Health Science Center to A.P.S. rodent equivalent for human interleukin 8 (IL-8) (5-10). Furthermore, MIP-2 receptor knockout mice have been shown to have less VILI than wild-type mice (9). However, the mechanisms of VILI during large Vt ventilation are not fully understood.Several studies of fetal lung cells have documented that cyclic stretch led to increased extracellular matrix sy...

Rationale: Our previous studies found that Na 1 /H 1 exchanger (NHE) activity played an essential role in pulmonary artery smooth muscle cell (PASMC) proliferation and in the development of hypoxiainduced pulmonary hypertension and vascular remodeling. Other investigators recently observed increased expression of the NHE isoform 1 (NHE1) gene in rodents with pulmonary hypertension induced by hypoxia. However, a causal role for the NHE1 gene in pulmonary hypertension has not been determined. Objectives: To determine the causal role of the NHE1 gene in pulmonary hypertension and vascular remodeling. Methods: We used NHE1-null mice to define the role of the NHE1 gene in the development of pulmonary hypertension and remodeling induced by hypoxia and to delineate the NHE1 regulatory pathway. Measurements and Main Results: After 2 weeks of exposure to hypoxia, in contrast to wild-type hypoxic littermates, there was no significant increase in right ventricular systolic pressure, in the ratio of right ventricular to left ventricular plus septal weight [RV/(LV 1 S)], or in medial wall thickness of the pulmonary arterioles in homozygous mice (NHE1 2/2 ). There was a significant decrease in Rho kinase (ROCK1 and ROCK2) expression, accompanied by an increase in p27 expression in NHE1 2/2 mice. Conclusions: Our study demonstrated that deficiency of the NHE1 gene prevented the development of hypoxia-induced pulmonary hypertension and vascular remodeling in mice and revealed a novel regulatory pathway associated with NHE1 signaling. Keywords: Na 1 /H 1 exchanger isoform 1; pulmonary hypertension; vascular remodeling; hypoxia; mouseThe Na 1 /H 1 exchanger (NHE) expressed in many mammalian cell types is a protein localized to the plasma and the mitochondrial inner membrane (1). The function of NHE is to regulate intracellular pH and cell volume by extruding H 1 from and taking up Na 1 into cells (2). Since NHE was first analyzed in 1976 (3) and the first NHE cDNA was cloned in 1989 (4), nine NHE isoforms have been identified and cloned (2), of which NHE isoform 1 (NHE1) is ubiquitously expressed.Pulmonary hypertension caused by many chronic lung diseases associated with prolonged hypoxia can result in right ventricular hypertrophy and heart failure (5). An important pathological feature of pulmonary hypertension is increased medial thickening of the pulmonary artery resulting from hypertrophy and hyperplasia of the pulmonary artery smooth muscle cells (PASMCs) (6, 7). In previous studies, we reported that NHE activity played a significant role in regulation of intracellular pH in PASMCs (8) and found that the inhibition of NHE activity was related to the inhibition of bovine PASMC proliferation induced by growth factors (9, 10). We also found that inhibition of NHE activity significantly reduced pulmonary hypertension and vascular remodeling induced by chronic hypoxia in rats (11). Our studies suggested that NHE activity might play an important role in development of pulmonary hypertension and vascular remodeling.Recently, incre...

Mechanical ventilation has been shown to cause ventilator-induced lung injury (VILI), probably by overdistending or stretching the lung. Hyaluronan (HA), a component of the extracellular matrix, in low molecular weight (LMW) forms has been shown to induce cytokine production. LMW HA is produced by hyaluronan synthase 3 (HAS 3). We found that HAS 3 mRNA expression was upregulated and that LMW HA accumulated in an animal model of VILI. We hypothesized that stretch-induced LMW HA production that causes cytokine release in VILI was dependent on HAS 3 mRNA expression. We explored this hypothesis with in vitro lung cell stretch. Cell stretch induced HAS 3 mRNA expression and LMW HA in fibroblasts. Nonspecific inhibitors of HAS 3 (cyclohexamide and dexamethasone), a nonspecific inhibitor of protein tyrosine kinases (genistein), and a janus kinase 2 inhibitor (AG490) blocked stretch-induced HAS 3 expression and synthesis of LMW HA. Stretch-induced LMW HA from fibroblasts caused a significant dose-dependent increase in interleukin-8 production both in static and stretched epithelial cells. These results indicated that de novo synthesis of LMW HA was induced in lung fibroblasts by stretch via tyrosine kinase signaling pathways, and may play a role in augmenting induction of proinflammatory cytokines in VILI.

Positive pressure ventilation with large VTs has been shown to cause release of cytokines, including macrophage inflammatory protein-2 (MIP-2), a functional equivalent of human interleukin-8. The mechanisms regulating ventilation-induced cytokine production are unclear. Based on our previous in vitro model of lung cell stretch, we hypothesized that high VT ventilation-induced MIP-2 production is dependent on the activation of the c-Jun N-terminal kinase (JNK). We exposed C57BL/6 mice to high VT (30 ml/kg) or low VT (6 ml/kg) mechanical ventilation for 5 hours. High VT ventilation-induced neutrophil migration into the lung, MIP-2 protein production, MIP-2 messenger RNA expression, and JNK activation. Large VT ventilation of JNK knockout mice and pharmacologic JNK inhibition with SP600125 attenuated neutrophil sequestration and blocked MIP-2 messenger RNA expression and MIP-2 production. We conclude that lung cell stretch in vivo results in increased lung neutrophil sequestration and increased MIP-2 production, which was, at least in part, dependent upon the JNK pathway.

Abstract-Heparin has growth inhibitory effects on pulmonary artery smooth muscle cell (PASMC) in vitro and in vivo.However, the mechanism has not been fully defined. In this study, we investigated the role of cyclin-dependent kinase inhibitors, p21 WAF1/cip1 (p21) and p27 Kip1 (p27), in the inhibitory effect of heparin on PASMC proliferation in vitro and on hypoxia-induced pulmonary hypertension in vivo using p21 and p27-null mice. In vitro, loss of the p27 gene negated the inhibitory effect of heparin on PASMC proliferation, but p21 was not critical for this inhibition. In vivo, heparin significantly inhibited the development of hypoxia-induced pulmonary hypertension and remodeling, as evidenced by decreased right ventricular systolic pressure, ratio of right ventricular weight to left ventricle plus septum weight, and percent wall thickness of pulmonary artery, in p21 ϩ/ϩ , p21 Ϫ/Ϫ , p27 ϩ/ϩ , and p27 ϩ/Ϫ , but not in p27 Ϫ/Ϫ mice. We also observed that hypoxia decreased p27 expression significantly in mouse lung, which was restored by heparin. Heparin inhibited Ki67 proliferative index in terminal bronchial vessel walls in p27 ϩ/ϩ and p27 ϩ/Ϫ , but not in p27 Ϫ/Ϫ mice exposed to hypoxia. Therefore, we conclude that the cyclin-dependent kinase inhibitor p27, but not p21, is required for the inhibition of hypoxic pulmonary vascular remodeling by heparin. Kip1 Ⅲ p21 WAF1/cip1 Ⅲ heparin Ⅲ pulmonary hypertension Ⅲ hypoxia Ⅲ mouse H eparin, a glycosaminoglycan, has been used as an anticoagulant for more than 50 years. 1 Besides anticoagulation, heparin has a variety of other biological activities, such as regulation of lipid metabolism, control of cell attachment to various proteins in the extracellular matrix, binding with acid and basic fibroblast growth factors, and inhibition of vascular smooth muscle cell (SMC) proliferation. 2 An important pathological feature of pulmonary hypertension is increased medial thickening of the pulmonary artery attributable to hypertrophy and hyperplasia of pulmonary artery SMC (PASMC). 3,4 Our previous studies have shown that antiproliferative heparins significantly inhibit pulmonary vascular remodeling induced by hypoxia in rodents 5-7 and PASMC proliferation in culture. 8 -10 Other investigators also have reported that heparin inhibits PASMC proliferation in vitro and in vivo. 8,11 To date, however, the mechanism by which heparin inhibits PASMC proliferation has not been elucidated.The balance between cell proliferation and cell quiescence is regulated by a variety of cell cycle modulators. Cyclindependent kinase (CDK) is a major regulator of the transition between the phases of the cell cycle. 12 Cyclin/CDK complexes are composed of a regulatory subunit, cyclin, and an active kinase subunit, CDK. The cyclin/CDK complexes are controlled by both positive and negative regulators. 13 p21 WAF1/cip1

Although high doses of single bioactive agents may have potent anticancer effects, the chemopreventive properties of the Asian diet may result from interactions among several components that potentiate the activities of any single constituent. In Asia, where intake of soy products and tea consumption are very high, aggressive prostate cancer is significantly less prevalent in Asian men. The objective of the present study was to identify possible synergistic effects between soy and tea components on prostate tumor progression in a mouse model of orthotopic androgen-sensitive human prostate cancer. Soy phytochemical concentrate (SPC), black tea and green tea were compared with respect to tumorigenicity rate, primary tumor growth, tumor proliferation index and microvessel density, serum androgen level and metastases to lymph nodes. SPC, black tea and green tea significantly reduced tumorigenicity. SPC and black tea also significantly reduced final tumor weights. Green tea did not reduce final tumor weight, although it tended to elevate (P = 0.14) the serum dihydrotestosterone (DHT) concentration. The combination of SPC and black tea synergistically inhibited prostate tumorigenicity, final tumor weight and metastases to lymph nodes in vivo. The combination of SPC and green tea synergistically inhibited final tumor weight and metastasis and significantly reduced serum concentrations of both testosterone and DHT in vivo. Inhibition of tumor progression was associated with reduced tumor cell proliferation and tumor angiogenesis. This study suggests that further research is warranted to study the role of soy and tea combination as effective nutritional regimens in prostate cancer prevention.

BACKGROUND-Systematic analysis of the influence of diet on the initiation and progression of prostate cancer is often difficult in human populations, for which dietary variables overlap a diversity of genetic backgrounds and social behaviors. Animal models that emulate human prostate cancer allow experimental analysis of the mechanisms of action of nutritional agents that show anti-prostate cancer activity.