May Azzawi

Interleukin-5 mRNA in Mucosal Bronchial Biopsies from Asthmatic Subjects

Using in situ hybridization, we have investigated the expression of interleukin-5 (IL-5) mRNA in bronchial biopsies from asthmatics (n = 10) and controls (n = 9). The number of IL-5-nRNA-positive cells were compared with the number of CD25+ and EG2+ cells and total eosinophil counts. Specific hybridization signals for IL-5 mRNA were demonstrated in 6 out of the 10 asthmatic subjects but in none of the controls. The 6 IL-5-mRNA-positive asthmatics tended to have more severe disease and showed a significant increase in the degree of infiltration of the bronchial mucosa by activated T lymphocytes and eosinophils.

Tumor necrosis factor-alpha gene polymorphism and death due to acute cellular rejection in a subgroup of heart transplant recipients

Irreversible acute rejection of the transplanted heart usually has a fatal outcome. Predicting which recipients are most likely to reject might allow closer monitoring and modification of treatment protocols to prevent graft loss. Recipients genetically predisposed to produce more TNF-alpha are those who suffer the most acute rejection episodes. Here we show that TNF-alpha genotype is strongly associated with death due to acute cell-mediated heart transplant rejection (Chi-square = 28.57, p < 0.0001). This subgroup of recipients should be given optimally tissue matched transplants and should be treated with the most effective immunosuppressive regimens.

Tumour necrosis factor alpha and the cardiovascular system: its role in cardiac allograft rejection and heart disease

Time for primary review 32 days. Tumour necrosis factor alpha (TNFα) is a pleiotropic cytokine that has many proinflammatory actions with negative inotropic effects. It has been implicated in the pathogenesis of many non-infectious disorders, from rheumatoid disease [1], to multiple sclerosis [2]. This cytokine also affects the heart [3] where it is produced by immune cells and the myocardium in some diseases. Raised serum TNFα is seen in patients with cardiomyopathy, myocardial infarction, and chronic heart failure [4], thus implicating TNFα in disease pathogenesis. Raised serum levels of this cytokine have also been identified in transplant patients following episodes of acute cellular rejection. There is a correlation between TNFα expression and rejection grade [5] suggesting that the cytokine is a candidate marker of rejection. In this review, we consider the basic biology of TNFα in relation to certain cardiac diseases. There are interrelationships between some of the conditions described, but these have been arbitrarily divided into three main groups: allograft rejection, coronary artery disease, and heart failure. Tumor necrosis factor alpha, cachectin (TNFα), was originally identified for its potent toxicity against tumour cells, hence its name [6]. Today, TNFα is recognised as a pleiotropic cytokine functioning within a complex and tightly regulated cytokine network. It activates multiple transduction pathways, inducing or suppressing a wide variety of genes, including those encoding the production of cytokines, adhesion molecules, and inducible nitric oxide synthase (iNOS). TNFα has many proinflammatory actions: orchestrating the inflammatory response through activation of proinflammatory cytokine genes, such as IL-1 and IL-6, as well as its own production [7]. This section will summarise our current understanding of the biology and function of TNFα with particular emphasis on the heart, and review recent work on the regulation of its production. ### 2.1 TNFα molecule The TNFα molecule (a 157 … * Corresponding author. Tel.: +44-161-282-1261; fax: +44-161-718-7167

The distribution of cardiac macrophages in myocardial ischaemia and cardiomyopathy

Aims : Recent evidence has implicated the macrophage as an effector cell in the inflammatory processes in transplant rejection, as well as cardiac disease, including coronary atherosclerosis. Although the latter is a vascular disease, the entire myocardium is affected. We have previously demonstrated the presence and distribution of macrophages in the ‘normal’ human heart. In this paper the distribution of myocardial macrophages, in the various chambers of the failing human heart, from cases of coronary atheroma and cardiomyopathy undergoing heart transplantation is documented.

Distribution of myocardial macrophages in the normal human heart

Macrophages are important in inflammatory processes in heart disease and in transplantation rejection. A resurgence of interest in the macrophage has emanated from recent evidence implicating it as an effector cell in atherosclerosis and transplantation rejection. The detailed distribution of the macrophage within the normal human heart is unknown. We quantified macrophage numbers in the different chambers of the heart. Large tissue blocks (1.5–2.0 cm3) were removed from specific sites in 5 ‘normal’ control hearts (2 males, 3 females, age range 19–46 y). Paraffin‐embedded sections were stained with a CD68 pan macrophage marker. Positive cells were enumerated within 20 random fields. Results were analysed using a generalised linear modelling method using the Poisson distribution. Macrophages were identified within septa, and often close to blood vessels, in the myocardium, and in the majority of areas in all hearts. Macrophage numbers varied significantly between areas (range 0–6 cells/high power field; P<0.001), and between the 5 hearts analysed (P<0.001). In general, there were significantly more macrophages in the ventricles (RV P<0.01, LV P<0.05), but these differences were affected by heart differences. This study provides a baseline for the range of macrophage numbers within normal hearts, thus enabling comparisons with macrophage numbers within diseased and transplanted hearts.

Biocompatibility of amorphous silica nanoparticles: Size and charge effect on vascular function, in vitro.

Synthetic amorphous silica is gaining popularity as the material of choice in the fabrication of nanoparticles for use in imaging diagnostics, medical therapeutics, and tissue engineering because of its biocompatible nature. However, recent evidence suggests that silica nanoparticles (SiNPs) show a concentration‐ and size‐dependent toxic effect that is cell specific. We investigated the direct influence of SiNP uptake on the vasodilator responses of rat aortic vessels, in vitro, using fabricated SiNPs of defined size (97 ± 7.60 and 197 ± 7.50 nm) and charge (positive and nonmodified). Dilator responses to cumulative doses of endothelial‐dependent [acetylcholine (Ach); 0.01 µM–1.0 mM] and endothelial‐independent (sodium nitroprusside; 0.01–10 µM) agonists were determined before and 30 Min after incubation in SiNPs (at 1.1 × 1011 nanoparticles/mL). Acute exposure to SiNPs led to their rapid uptake by the lining endothelial cells (as verified by transmission electron microscopy). SiNP uptake had no significant influence on dilator responses, although a greater degree of attenuation was evident after uptake of the 100 nm and positively charged SiNPs (significant at the highest 1.0 mM Ach concentration between positive and nonmodified 200 nm SiNPs; P < 0.05). In summary, our findings suggest that SiNP surface interactions, rather than mass, affect vasodilator function of aortic vessels.

TNFα mRNA and protein in cardiac transplant biopsies: comparison with serum TNFα levels

Objectives: To examine the role of TNF alpha (TNFα) in cardiac transplant rejection by simultaneous analysis of protein expression and its messenger RNA within serum and grafted tissue. Methods: 54 endomyocardial biopsy specimens were taken from 19 patients at various times after transplantation. TNFα messenger RNA was localised using a digoxygenin labelled complementary DNA probe. An anti-TNFα antibody was used to immunohistochemically label the protein product. Serum TNFα levels at the time of biopsy were analysed using a specific enzyme-linked immunosorbent assay. Results: TNFα mRNA was present in 22/34 endomyocardial biopsies. Eight also contained TNFα protein. None had protein alone. Expression did not relate to the grade of rejection in the present or subsequent biopsies. Serum TNFα was undetectable (assay sensitivity 30–330 pg/ml) for the majority of specimens. In the nine cases with elevated serum levels, eight samples were from cases within the first 30 days post transplant ( r = −0.379; P < 0.05). Conclusions: Neither tissue TNFα mRNA, tissue protein, nor serum TNFα relate to the grade of rejection. Furthermore, TNFα expression within endomyocardial biopsies is not reflected in the serum. These findings argue against the use of serum analysis as an indicator of cytokine profiles within cardiac tissue allografts. The demonstration of a trend in the early expression of TNFα after transplantation suggests that its release may not be specific to the process of rejection.

The Effects of Endothelial Factor Inhibition on the Time Course of Responses of Isolated Rat Coronary Arteries to Intraluminal Flow

The aims of this study were to investigate, for the first time, the effects of endothelial factor inhibition on both the magnitude and dynamics of the response of isolated small coronary arteries to intraluminal flow. Isolated rat coronary arteries were mounted on a pressure myograph and left to develop myogenic tone. Flow was introduced and maintained until stable diameters were attained. Dilatory responses were observed which were maximal at low flow rates (5–10 µl/min) and thus shear stresses (1–2 dyn/cm2). These responses were transient in nature. Transient dilations were also observed upon cessation of flow. All responses (to 5 µl/min) were endothelium dependent and were completely abolished by addition of charybdotoxin (100 nM) and apamin (100–500 nM) suggesting an important role for a hyperpolarizing mechanism most likely involving an endothelium-derived hyperpolarizing factor. However, inhibitors of nitric oxide synthase (L-NNA; 100 µM) or cyclo-oxygenase (indomethacin; 10 µM) also modulated the response causing an increase and decrease in maximum vasodilation, respectively. By examining the time course we showed that both agents also made the response significantly more transient in nature. These results show that inhibition of endothelial factor pathways can influence both the magnitude and dynamics of the response of isolated rat coronary arteries to flow.

Attenuation of endothelial-dependent vasodilator responses, induced by dye-encapsulated silica nanoparticles, in aortic vessels

AIM To determine the influence of silica nanoparticle (SiNP) number, size and dye encapsulation on conduit arterial function, in vitro. MATERIALS & METHODS Rhodamine B isothiocyanate (RBITC) dye molecules were encapsulated in a silica shell to produce nanoparticles (silica RBITC nanoparticles) smaller than 100 nm size. Their effects on endothelial-dependent (acetylcholine; 0.01-200 µM) and -independent (sodium nitroprusside; 0.001-10 µM) dilator responses were examined. RESULTS When incubated with 1.96 × 10(12) nanoparticles/ml, both 30 and 70 nm SiNPs and silica RBITC nanoparticles significantly reduced endothelium-dependent, but not -independent, vasodilation. The degree of attenuation was related to nanoparticle surface area, rather than size, and influenced by dye encapsulation. Furthermore, attenuated dilation due to silica RBITC nanoparticles, but not SiNPs, could be partially restored using superoxide dismutase. CONCLUSION Our results suggest that the mechanism of attenuated dilation is different for SiNPs and silica RBITC nanoparticles, which has implications for the future fabrication of biocompatible nanoparticles for imaging diagnostics.

The effects of resveratrol on aging vessels

Aging is a major risk factor for the development of cardiovascular disease. Despite a significant reduction in the mortality and morbidity rates over the last decade, the socio-economic burden of cardiovascular disease is still substantial. Consequently, there is a considerable need for alternative strategies, such as nutraceutical supplementation, that delay the functional vascular decline present in the elderly. Compromised autophagy and oxidative stress (OS) are considered major causes of the age-related endothelial dysfunction. OS reduces the bioavailability of nitric oxide (NO), which has been associated with hypertension, arteriosclerosis, and a reduced vasodilatory response. High levels of free radicals and the low bioavailability of NO lead to a positive feedback loop of further OS, organelle damage, poor repair, and endothelial dysfunction. Here we draw attention to the relationship between OS and autophagy in the aged vasculature. We have reviewed the published literature and provided arguments that support that treatment with resveratrol stimulates autophagy and thereby has the potential to restore oxidative balance in the endothelium, which indicates that treatment with resveratrol might have therapeutic potential to restore endothelial function in the elderly.