The influence of indomethacin on the metabolism and cytokine secretion of human aneurysmal aorta

Inflammation in Abdominal Aortic Aneurysm: cause or co-morbidity?

Aortic aneurysm is a potentially deadly disease. It is chronic degeneration of the aortic wall that involves an inflammatory response and the immune system, aberrant remodeling of the extracellular matrix, and maladaptive transformation of the aortic cells. This review article focuses on the role of the inflammatory cells in abdominal aortic aneurysm. Studies in human aneurysmal specimens and animal models have identified various inflammatory cell types that could contribute to aneurysm formation and or expansion. These include the commonly studied leukocytes (neutrophils and macrophages) as well as the less commonly explored natural killer cells, dendritic cells, T- and B-cells. Despite the well-demonstrated contribution of inflammatory cells and the related signaling pathways to aneurysm development and expansion, anti-inflammatory therapy approaches have demonstrated limitations and may require additional considerations, such as a combinational approach in targeting multiple pathways for significant beneficial outcomes.

A comprehensive painkillers screening by assessing zebrafish behaviors after caudal fin amputation

Recently, the usage of zebrafish for pain studies has increased in the past years, especially due to its robust pain-stimulated behaviors. Fin amputation has been demonstrated to induce a noxious response in zebrafish. However, based on the prior study, although lidocaine, the most used painkiller in zebrafish, has been shown to ameliorate amputated zebrafish behaviors, it still causes some prolonged effects. Therefore, alternative painkillers are always needed to improve the treatment quality of fin-amputated zebrafish. Here, the effects of several analgesics in recovering zebrafish behaviors post-fin amputation were evaluated. From the results, five painkillers were found to have potentially beneficial effects on amputated fish behaviors. Overall, these results aligned with their binding energy level to target proteins of COX-1 and COX-2. Later, based on their sub-chronic effects on zebrafish survivability, indomethacin, and diclofenac were further studied. This combination showed a prominent effect in recovering zebrafish behaviors when administered orally or through waterborne exposure, even with lower concentrations. Next, based on the ELISA in zebrafish brain tissue, although some changes were found in the treated group, no statistical differences were observed in most of the tested biomarkers. However, since heatmap clustering showed a similar pattern between biochemical and behavior endpoints, the minor changes in each biomarker may be sufficient in changing the fish behaviors.

Role of prostaglandin D2 receptors in the pathogenesis of abdominal aortic aneurysm formation

Prostaglandin D2 (PGD2) released from immune cells or other cell types activates its receptors, D prostanoid receptor (DP)1 and 2 (DP1 and DP2), to promote inflammatory responses in allergic and lung diseases. Prostaglandin-mediated inflammation may also contribute to vascular diseases such as abdominal aortic aneurysm (AAA). However, the role of DP receptors in the pathogenesis of AAA has not been systematically investigated. In the present study, DP1-deficient mice and pharmacological inhibitors of either DP1 or DP2 were tested in two distinct mouse models of AAA formation: angiotensin II (AngII) infusion and calcium chloride (CaCl2) application. DP1-deficient mice [both heterozygous (DP1+/-) and homozygous (DP1-/-)] were protected against CaCl2-induced AAA formation, in conjunction with decreased matrix metallopeptidase (MMP) activity and adventitial inflammatory cell infiltration. In the AngII infusion model, DP1+/- mice, but not DP1-/- mice, exhibited reduced AAA formation. Interestingly, compensatory up-regulation of the DP2 receptor was detected in DP1-/- mice in response to AngII infusion, suggesting a potential role for DP2 receptors in AAA. Treatment with selective antagonists of DP1 (laropiprant) or DP2 (fevipiprant) protected against AAA formation, in conjunction with reduced elastin degradation and aortic inflammatory responses. In conclusion, PGD2 signaling contributes to AAA formation in mice, suggesting that antagonists of DP receptors, which have been extensively tested in allergic and lung diseases, may be promising candidates to ameliorate AAA.

Importance of NLRP3 Inflammasome in Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a chronic inflammatory degenerative aortic disease, which particularly affects older people. Nucleotide-binding oligomerization domain-like receptor family protein 3 (NLRP3) inflammasome is a multi-protein complex and mediates inflammatory responses by activating caspase 1 for processing premature interleukin (IL)-1β and IL-18. In this review, we first summarize the principle of NLRP3 inflammasome activation and the functionally distinct classes of small molecule NLRP3 inflammasome inhibitors. Next, we provide a comprehensive literature review on the expression of NLRP3 inflammasome effector mediators (IL-1β and IL-18) and components (caspase 1, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and NLRP3) in clinical and experimental AAAs. Finally, we discuss the influence of genetic deficiency or pharmacological inhibition of individual effector mediators and components of NLRP3 inflammasome on experimental AAAs. Accumulating clinical and experimental evidence suggests that NLRP3 inflammasome may be a promise therapeutic target for developing pharmacological strategies for clinical AAA management.

Quercetin Downregulates Cyclooxygenase-2 Expression and HIF-1α/VEGF Signaling-Related Angiogenesis in a Mouse Model of Abdominal Aortic Aneurysm

Objective

Abdominal aortic aneurysm (AAA) development has been characterized by increased expression of vascular endothelial growth factor (VEGF), which contributes to angiogenesis via cyclooxygenase-2 (COX-2). Quercetin, one of the most common and well-researched flavonoids and abundant in vegetables and fruits, has beneficial effects in inhibiting angiogenesis. This study investigated the antiangiogenic effects of quercetin on experimental aneurysms.

Methods

We utilized the in vivo AAA mouse model induced by the periaortic application of CaCl₂ to examine the effectiveness of quercetin in blocking angiogenesis. Quercetin was administered at 60 mg/kg once daily on the day of the AAA induction and then continued for 6 weeks. Celecoxib, a selective COX-2 inhibitor, was used as the positive control.

Results

Our results demonstrated that quercetin significantly attenuated aneurysm growth in AAA mice and medial neovascularization. Accordingly, quercetin decreased the expression of proangiogenic mediators, including VEGF-A, intercellular adhesion molecule-1, vascular cell adhesion molecule 1, and vascular endothelial cadherin. Quercetin treatment also inhibited the expression of COX-2 and hypoxia-inducible factor 1α (HIF-1α). It was also found that quercetin-3-glucuronide, a major quercetin metabolite, downregulated the expression of COX-2, HIF-1α, VEGF-A, and matrix metalloproteinase activities in aortic vascular smooth muscle cells isolated from AAA mice.

Conclusion

Quercetin attenuates neovascularization during AAA growth, and this effect is mediated via the inhibition of COX-2, which decreases HIF-1α/VEGF signaling-related angiogenesis.

Current Status and Perspectives on Pharmacologic Therapy for Abdominal Aortic Aneurysm

Background:

Abdominal aortic aneurysm (AAA), a common disease involving the segmen-tal expansion and rupture of the aorta, has a high mortality rate. Therapeutic options for AAA are cur-rently limited to surgical repair to prevent catastrophic rupture. Non-surgical approaches, particularly pharmacotherapy, are lacking for the treatment of AAA.

Objective:

We review both basic and clinical studies and discuss the current challenges to developing medical therapy that reduces AAA progression.

Results:

Studies using animal models of AAA progression and human AAA explant cultures have identified several potential targets for preventing AAA growth. However, no clinical studies have con-vincingly confirmed the efficacy of any pharmacologic treatment against the growth of AAA. Thus, there is as yet no strong recommendation regarding pharmacotherapy to reduce the risk of AAA pro-gression and rupture.

Conclusion:

This review identifies concerns that need to be addressed for the field to progress and dis-cusses the challenges that must be overcome in order to develop effective pharmacotherapy to reduce AAA progression in the future.

Pharmacologic Management of Aneurysms

Current management of aortic aneurysms relies exclusively on prophylactic operative repair of larger aneurysms. Great potential exists for successful medical therapy that halts or reduces aneurysm progression and hence alleviates or postpones the need for surgical repair. Preclinical studies in the context of abdominal aortic aneurysm identified hundreds of candidate strategies for stabilization, and data from preoperative clinical intervention studies show that interventions in the pathways of the activated inflammatory and proteolytic cascades in enlarging abdominal aortic aneurysm are feasible. Similarly, the concept of pharmaceutical aorta stabilization in Marfan syndrome is supported by a wealth of promising studies in the murine models of Marfan syndrome-related aortapathy. Although some clinical studies report successful medical stabilization of growing aortic aneurysms and aortic root stabilization in Marfan syndrome, these claims are not consistently confirmed in larger and controlled studies. Consequently, no medical therapy can be recommended for the stabilization of aortic aneurysms. The discrepancy between preclinical successes and clinical trial failures implies shortcomings in the available models of aneurysm disease and perhaps incomplete understanding of the pathological processes involved in later stages of aortic aneurysm progression. Preclinical models more reflective of human pathophysiology, identification of biomarkers to predict severity of disease progression, and improved design of clinical trials may more rapidly advance the opportunities in this important field.

Using human iPS cell-derived enterocytes as novel in vitro model for the evaluation of human intestinal mucosal damage

OBJECTIVE AND DESIGN

The primary component in gut mucus is mucin 2 (MUC2) secreted by goblet cells. Fluctuations in MUC2 expression are considered a useful indicator for evaluating mucosal damage and protective effect of various agents using animal studies. However, there are few in vitro studies evaluating mucosal damage using MUC2 as the indicator. Hence, we attempted to establish a novel in vitro model with MUC2 as the indicator for evaluating drug-induced mucosal damage and protective effect using enterocytes derived from human iPS cells.

METHODS

Compounds were added into enterocytes derived from human iPS cells, and MUC2 mRNA and protein expression levels were evaluated. Further, the effect of compounds on membrane permeability was investigated.

RESULTS

Nonsteroidal anti-inflammatory drugs were found to decrease MUC2 mRNA expression in enterocytes, whereas mucosal protective agents increased mRNA levels. Changes in MUC2 protein expression were consistent with those of mRNA. Additionally, our results indicated that indomethacin caused mucosal damage, affecting membrane permeability of the drug. Moreover, we observed protective effect of rebamipide against the indomethacin-induced permeability increase.

CONCLUSIONS

The developed model could facilitate evaluating drug-induced mucosal damage and protective effects of various agents and could impact drug development studies regarding pharmacological efficacy and safety.

Complexes of Indomethacin with 4-Carbomethoxy-pyrrolidone PAMAM Dendrimers Show Improved Anti-inflammatory Properties and Temperature-Dependent Binding and Release Profile

COX-2 inhibitors such as nonsteroidal anti-inflammatory drugs (NSAIDs) are the most common treatment for chronic inflammatory diseases like arthritis and atherosclerosis. However, they are associated with severe side effects such as cardiovascular events or stomach bleeding, due to coinhibition of other enzymes (COX1) and off-target accumulation. PAMAM dendrimers can solubilize lipophilic drugs and increase their circulation time; furthermore, PAMAM dendrimers seem to have some accumulation in inflammatory sides. Three different generations of 4-carbomethoxypyrrolidone (Pyr) surface-modified PAMAM dendrimers were complexed with the NSAID drug indomethacin, and their in-solution thermodynamic profiles were studied by means of NMR experiments. The binding stoichiometry was found dependent on solvent system and dendrimer generation. Larger dendrimers (G3-Pyr) were found to bind indomethacin through entropy driven binding mode, while G1-Pyr and G2-Pyr expressed an enthalpy driven complex formation, which means that the binding constants have a generational temperature dependency. G1/2-Pyr showed reduced binding with increasing temperature, which could be important for drug release at inflammatory sites, which have, in general, elevated temperatures. In vitro studies elucidated that the indomethacin drug remained its activity when delivered as a dendrimer-indomethacin complex. A slight reduction in toxicity profile was noticed for G2/G3-Pyr-indomethacin dendrimers. Both free indomethacin and dendrimer-indomethacin complex inhibited a variety of pro-inflammatory cytokines in LPS treated cells. However, only the indo-dendrimer complexes showed a significant reduction of IL-1β in LPS-treated THP-1 cells, which was not present in the control with free indomethacin.

Cyclooxygenase-2 expression and its association with increased angiogenesis in human abdominal aortic aneurysms

Although the mechanism whereby non-steroidal anti-inflammatory drugs may reduce abdominal aortic aneurysm (AAA) development is unknown, one potential route is via inhibition of the cyclooxygenase (COX) enzyme. Despite the fact that evidence from animal models suggests a role for the COX-2 isoform in promotion of AAA development, only very limited data exist on COX-2 expression in human AAAs. Semiquantitative immunohistochemistry for COX-2 was performed on a series of formalin-fixed, paraffin-embedded human AAAs (n = 49). Associated clinicopathological data, including the degree of inflammatory cell infiltration and neorevascularization, were obtained. COX-2 protein was detected in 46 of 49 (94%) human AAAs. Expression of COX-2 protein varied widely between AAAs. COX-2 protein localized to cells in the inflammatory infiltrate with a morphology characteristic of macrophages. COX-2 expression increased with the extent of inflammatory cell infiltration (P < 0.001) and with the degree of AAA neorevascularization (P < 0.001). Logistic regression analysis identified neorevascularization (P < 0.001) as the only significant independent predictor of COX-2 positivity in human AAAs. COX-2 protein is present at increased levels in the majority of human AAAs and is expressed by mononuclear cells in the inflammatory cell infiltrate. Promotion of angiogenesis by COX-2 may play a role in AAA development.

Nonsteroidal antiinflammatory drugs are associated with increased aortic stiffness

OBJECTIVES

Nonsteroidal antiinflammatory drugs (NSAIDS) have been shown to retard aneurysm growth in animal models. In vitro studies have shown an inhibitory effect of NSAIDS on matrix metalloproteinase-9, interleukin-1beta, and IL-6 mediated arterial wall elastolysis. The aim of this study was to investigate the effects of NSAIDs on arterial stiffness, a surrogate marker of elastolysis.

METHODS

447 subjects enrolled in a community-based abdominal aortic aneurysm (AAA) screening program were assessed for age, blood pressure, smoking status, and drug history. Aortic diameter and stiffness were measured by M-Mode ultrasound. The concentration of the amino-terminal propeptide of type III procollagen was used as a proxy measurement of type III collagen turnover.

RESULTS

NSAID ingestion was significantly (p = 0.006) associated with increased aortic wall stiffness after adjusting for age, aortic diameter, blood pressure, and smoking status. No such effect was seen for beta-blockers, calcium channel antagonists, nitrates, angiotensin-converting enzyme inhibitors, diuretics, or antiplatelet agents.

DISCUSSION

These novel data show that NSAIDS are associated with increased aortic stiffness, possibly through the effects of cytokine mediated elastolysis. This in turn may prevent aortic expansion and the development of AAA.

Aortic aneurysms secrete interleukin-6 into the circulation

OBJECTIVE

Circulating plasma interleukin-6 (IL-6) concentrations are elevated in patients with abdominal aortic aneurysms (AAAs) compared with controls. In vitro studies suggest that the aneurysm is the source of the IL-6. Because IL-6 is an independent risk factor for cardiovascular mortality, elevation of this cytokine may be significant in these patients, who represent a group at increased risk from cardiovascular death. The aim of this study was to directly measure in vivo aortic IL-6 concentrations, testing the hypothesis that aneurysms secrete IL-6 into the circulation.

METHODS

Before endovascular aneurysm repair took place, blood was sampled from the entire length of the aorta in 27 patients with AAA and nine with thoracic aneurysms (TAs). A control group consisted of 15 patients without aneurysms undergoing angiography. Plasma IL-6 was determined using enzyme-linked immunosorbent assay, and high-sensitivity C-reactive protein (hs-CRP) was measured turbidimetrically. Aneurysm surface area was calculated from axial computed tomography scans.

RESULTS

Mean IL-6 concentrations (pg/mL) were higher in the TA and AAA groups compared with controls (10.4 +/- 3.7 and 4.9 +/- 0.5 vs 2.7 +/- 0.5, P = .002). There was a significant difference in plasma IL-6 concentration corresponding to aneurysm position in the AAA (P = .002) and TA (P = .008) groups, with both patterns conforming to a linear trend. This pattern was not observed in the control group, in which no significant difference in IL-6 concentrations was found throughout the aorta. Peak IL-6 occurred earlier in TAs compared with AAAs (descending aorta vs iliac artery) corresponding to aneurysm position (P = .0007). Linear regression revealed a positive correlation between aneurysm surface area and mean plasma IL-6 (Spearman's correlation, P = .003). The mean surface areas of the TAs, at 0.07 m2 (interquartile range [IQR], 0.06 to 0.09), were higher than those of the AAAs at 0.03 m2 (IQR, 0.02 to 0.04; P = .002). High-sensitivity CRP was within normal limits, and no significant differences were found between the AAA group and the controls.

CONCLUSIONS

Circulating IL-6 is elevated within the aorta in patients with aneurysms and corresponds to aneurysm position. Furthermore, aneurysm surface area and mean plasma IL-6 are correlated. In the absence of any evidence of systemic inflammation in the form of elevated hs-CRP, these data support the hypothesis that aneurysms secrete IL-6 into the circulation. This may contribute to the high cardiovascular mortality observed in patients with aneurysms.

Abdominal aortic aneurysm: pathogenesis and implications for management

Abdominal aortic aneurysm (AAA) affects approximately 5% of elderly men and is responsible for a significant number of deaths in Western Countries. At present surgery by open or endovascular means is the only widely used therapy for this condition. In this review we examine the risk factors, serum, and genetic associations of AAA. Epidemiology studies suggest that smoking cessation and control of cholesterol and blood pressure should reduce the number of patients developing AAA. Natural history studies suggest that smoking cessation should reduce the rate of progression of AAA. Clear level 1 evidence for drug treatments of AAA are presently lacking; however, animal and human in vitro studies suggest that medication targeted at reducing inflammation and proteolysis are most likely to be beneficial, with limited data to support the use of statins, Angiotensin II inhibitors, and macrolides. Work has commenced in understanding which patients, identified by clinical, serum, and genotype, are more at risk of AAA progression and thus should be selected out for aggressive treatment. Well designed large multicenter randomized controlled trials are required to examine the medical treatment of AAA.

Influence of Indomethacin in the Rat Aneurysm Model

The objective of this study was to trigger the formation of rat abdominal aortic aneurysm by applying calcium chloride periarterially and then to detect the degree of prevention of aneurysm occurrence by oral introduction of indomethacin in some of the rats. Thirty-one rats were divided into three groups. The infrarenal aorta above the iliac bifurcation of rats was treated with sodium chloride in group 1 (control, n = 7), calcium chloride in group 2 (n = 12), and calcium chloride-indomethacin in group 3 (n = 12) periarterially. The rats of each group were randomly selected at the end of the first, second, and third weeks postoperatively; and vessel diameters of abdominal aortas were measured by digital photography using a micrometer. Aneurysmal development was not observed in any of the rats in the control group. None of the comparisons was statistically significant (p > 0.05). Aneurysmal development was observed in all of the rats in the calcium chloride group. Results from the first, second, and third weeks postoperatively were statistically significant (p < 0.05). A middle aneurysmal development was observed in all rats in the calcium chloride-indomethacin group. Only results from the second and third weeks postoperatively were statistically significant (p < 0.05). Measurements in groups 2 and 3 were statistically significant when compared to group 1 (p < 0.001). However, the mean increase in the indomethacin-treated group (group 3) was only 26.1%. The macroscopic appearance of the control group and an aneurysm induced by calcium-chloride application are shown.

A Review of Biological Factors Implicated in Abdominal Aortic Aneurysm Rupture

Abdominal aortic aneurysm (AAA) rupture is the 13th commonest cause of death in the Western World. Although considerable research has been applied to the aetiology and mechanism of aneurysm expansion, little is known about the mechanism of rupture. Aneurysm rupture was historically considered to be a simple physical process that occurred when the aortic wall could no longer contain the haemodynamic stress of the circulation. However, AAAs do not conform to the law of Laplace and there is growing evidence that aneurysm rupture involves a complex series of biological changes in the aortic wall. This paper reviews the available data on patient variables associated with aneurysm rupture and presents the evidence implicating biological factors in AAA rupture.

Inflammatory Abdominal Aortic Aneurysms

BACKGROUND

Inflammatory abdominal aortic aneurysms (IAAA) are a variant of aortic aneurysm characterised by extensive peri-aneurysmal fibrosis, thickened walls and dense adhesions and represent between 3 and 10% of all abdominal aortic aneurysms (AAA). Surgery is technically challenging and is still associated with an increased morbidity and mortality. Controversy exists about aetiology and pathogenesis.

METHODS

We review the literature on the current theories, the available imaging modalities and the current thinking on management of IAAA. A Medline database search was performed. Articles were cross-referenced.

RESULTS AND CONCLUSIONS

Aneurysm development is multifactorial with important genetic and environmental factors. The literature supports the theory that IAAA arise from the same antigenic stimulus that is responsible for the non-IAAA, representing one extreme of an inflammatory spectrum. The results after open repair have improved and there is now little difference in the mortality between non-IAAA and IAAA repair. However, there is likely to be a role for endovascular stenting in IAAA management and this requires further study. It is clear that closer follow-up of patients after IAAA repair with either technique is necessary to monitor the inflammatory process. No evidence-based follow-up protocol exists but three to six-monthly monitoring of renal function and erythrocyte sedimentation rate (ESR) for 24 months post-repair would seem a reasonable regime.

Prostaglandin E2 receptors in abdominal aortic aneurysm and human aortic smooth muscle cells

BACKGROUND

Prostaglandin (PG) E(2) (PGE(2)) appears to have a role in stimulating production of interleukin-6 (IL-6) and apoptosis of smooth muscle cells in diseased aortic tissue. These actions are mediated by cellular receptors for PGE(2) EP receptors.

OBJECTIVE

This study was undertaken to identify EP receptors associated with production of IL-6 by aortic explants.

METHODS

Biopsy specimens of abdominal aortic aneurysm were used for explant culture and preparation of messenger RNA. The presence of EP1, EP2, EP3, and EP4 receptors in tissue and cells was investigated with reverse-transcriptase polymerase chain reaction. IL-6 and cyclic adenosine monophosphate were measured with an enzyme-linked immunosorbent assay.

RESULTS

PGE(2) or 11-deoxy-PGE(1) (EP 2/3/4 agonist) reversed partially the indomethacin suppression of IL-6 secretion from explant cultures, whereas butaprost (EP2 receptor agonist) and sulprostone (EP 1/3 receptor agonist) had no effect. Aortic biopsy specimens expressed EP2, EP3-III, and EP4 receptors. Aortic smooth muscle cells expressed EP2 receptor and four variants of EP3 receptor, ie, EP3-Ib, EP3-II, EP3-III, and EP3-IV, but PGE(2) did not stimulate secretion of IL-6. In contrast, PGE(2) or 11-deoxy-PGE(1) stimulated secretion of IL-6 from aortic macrophages.

CONCLUSIONS

In aortic explants, PGE(2) stimulates IL-6 secretion by activation of EP4 receptors, present in macrophages.

Transient exposure to elastase induces mouse aortic wall smooth muscle cell production of MCP-1 and RANTES during development of experimental aortic aneurysm

PURPOSE

Abdominal aortic aneurysm (AAA) is associated with chronic transmural inflammation and destruction of the elastic media. The purpose of this study was to elucidate molecular mechanisms that might orchestrate leukocyte recruitment into the outer aortic wall by determining whether CC chemokines contribute to development of aneurysm degeneration in an elastase-induced mouse model of AAA.

METHODS

Adult male C57BL/6J mice underwent transient elastase perfusion of the abdominal aorta to induce development of AAA. At various intervals after elastase perfusion (0, 4, 7, 14 days), real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays were used to measure aortic wall expression of the CC (beta) chemokines, monocyte chemoattractant protein-1 (MCP-1) and regulated on activation, normal T-cell expressed and secreted (RANTES). Expression of these chemokines by cultured mouse aortic smooth muscle cells (AoSMC) was similarly assessed after transient (5 minutes) exposure to elastase solutions in vitro.

RESULTS

Mouse aortic diameter (mean +/- SEM) increased to aneurysmal proportions by 14 days after elastase perfusion (from 0.51 +/- 0.03 mm to 1.34 +/- 0.32 mm; 163% increase; P <.05), with macrophage infiltration of the outer aortic wall beginning within 7 to 10 days. Increased aortic wall messenger RNA expression for MCP-1 (28-fold) and RANTES (11-fold) was observed on day 4, with maximal production of chemokine protein on day 7 (MCP-1, from 7.07 +/- 0.06 ng/mL to 19.60 +/- 0.19 ng/mL; P <.001; RANTES, from 0.23 +/- 0.006 ng/mL to 2.03 +/- 0.057 ng/mL; P <.001). Neither MCP-1 nor RANTES was detected in normal mouse aorta with immunohistochemistry, but both chemokines were abundant in AAA. Within 48 hours of transient exposure to elastase, cultured mouse AoSMC exhibited pronounced induction (>90-fold) of MCP-1 and RANTES, despite concomitant decrease in cell numbers.

CONCLUSIONS

Increased mouse aortic wall expression of MCP-1 and RANTES occurs early in development of elastase-induced AAA and before onset of the chronic inflammatory response. Moreover, elastase directly stimulates AoSMC chemokine production in vitro. Elastase-induced medial SMC production of CC chemokines may therefore provide an important link between enzymatic injury, leukocyte recruitment, and aneurysmal degeneration of the aortic wall.

Prospects for the medical management of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are a chronic degenerative disease with life-threatening implications. While AAAs are thought to arise through a localized form of arterial wall injury superimposed on various predisposing factors, their natural history is one of progressive structural deterioration, gradual expansion, and eventual rupture. Pathologic processes contributing to the changes observed in AAAs include chronic inflammation, destructive remodeling of the extracellular matrix, and depletion of vascular smooth muscle cells. These changes result in progressive aortic dilatation accompanied by alterations in vessel geometry, redistribution of hemodynamic wall stresses, and diminished tensile strength. As outlined in this review, better understanding of the biological mechanisms underlying these changes will allow design of novel therapeutic strategies to suppress the process of aneurysmal degeneration.

Matrix metalloproteinases and atherosclerotic plaque instability

BACKGROUND

There is growing interest in the role of matrix metalloproteinases in atherosclerosis. Excessive tissue remodelling and increased matrix metalloproteinase activity have been demonstrated during atherosclerotic plaque disruption, a frequent predeterminant of ischaemic cardiac events and stroke. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology.

METHODS

The core of this review is derived from a Medline database literature search.

RESULTS

There is convincing evidence of increased matrix metalloproteinase activity during acute plaque disruption. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in models of vascular disease suggest a potential therapeutic benefit.

CONCLUSION

In vivo studies of matrix metalloproteinase inhibition are required to study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies acute plaque disruption.

The role of matrix metalloproteinases in vascular disease

There is growing interest in the role of matrix metalloproteinases in vascular diseases. These conditions are often characterized by excessive tissue remodelling, and increased matrix metalloproteinase activity has been demonstrated in aneurysms, intimal hyperplasia and atherosclerotic plaque disruption. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology. The core of this review is derived from a MEDLINE database literature search. The review found that there is convincing evidence of increased matrix metalloproteinase activity in a spectrum of vascular disease. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in vascular disease models suggest potential therapeutic benefit. In conclusion, in vivo studies of matrix metalloproteinase inhibition are required to further study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies vascular disorders.

Hospital costs and benefits of screening for abdominal aortic aneurysms. Results from a randomised population screening trial

OBJECTIVES

to analyse the hospital costs and benefits of screening older males for abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

in 1994 a hospital-based screening trial of 12 658 65-73-year-old males was started. AAA >5 cm were referred for surgery. The remaining AAA were offered annual scans. Those with aortic ectasia were rescreened at 5 yearly intervals. AAA-operations and hospital AAA-related deaths were researched. The costs of screening, surveillance, and treatment were also registered.

RESULTS

the attendance rate was 76%; of whom 191 (4.0%) had AAA. Mean observation time was 5.13 years. Sixty in the screened and 41 in the control group were operated (p=0.06), of which 7 and 27 respectively were operated as an emergency (p<0.001), and 6 and 19 respectively died due to AAA (p=0.009). The costs per scan were 83.50 DKK, 81 400 DKK per emergency operation (71 485 DKK after screening), and 117 000 DKK per emergency operation. The cost per prevented hospital death was 67 855 DKK, equivalent to approximately life year saved approx. 7540 DKK (GBP1=12 DKK).

CONCLUSION

screening appears to reduce hospital AAA mortality and to be cost-effective.

Relationship between interleukin-6 levels in gingival crevicular fluid and periodontal status in patients with rheumatoid arthritis and adult periodontitis

BACKGROUND

The aim of this study was to determine and compare interleukin-6 (IL-6) levels in gingival crevicular fluid (GCF) and clinical periodontal findings in patients with rheumatoid arthritis (RA) and adult periodontitis (AP).

METHODS

A total of 45 patients divided into 3 groups (15 patients with RA and AP, 15 patients with AP, and 15 periodontally healthy subjects) were included in this study. Plaque index (PI), gingival index (GI), sulcus bleeding index (SBI), probing depth (PD), and attachment level (AL) values for each patient were recorded. Enzyme-linked immunosorbent assay for quantitative detection of IL-6 in each GCF sample was employed.

RESULTS

No significant difference could be detected between the RA and AP groups in the mean clinical parameter data except PI. Although the mean GCF IL-6 level in the RA group was the highest, no significant difference could be found among the groups. There was only a strong negative correlation between GCF IL-6 levels and GI scores in the RA group.

CONCLUSIONS

In the patients with RA, despite increased local tissue destruction potential due to autoimmunity and higher PI levels than in the AP patients, our findings suggest that medication including corticosteroid and non-steroidal anti-inflammatory drugs may decrease gingival inflammation, but the synthesis and degradation of IL-6 in gingival tissue of RA patients may be different. To our knowledge, this study is the first report determining GCF IL-6 levels in RA patients.

Cytokines as plasma markers of abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysms (AAA) is a complex process in which atherosclerosis and inflammation play a leading role. Cytokines are important mediators of both processes. The aim of our study was to determine whether plasma levels of cytokines which are most involved in AAA pathogenesis can be used as endogenous markers of AAA development, and thus to facilitate the decision on surgical intervention in cases when this is clinically unclear (e.g. small AAA). In the prospective study a total of 90 patients with AAA were examined. These patients were divided into the following groups according to symptoms and AAA diameter: symptomatic AAAs, including ruptures (n=16); asymptomatic AAAs (n=74); AAAs with a diameter of up to 5 cm (n=30), AAAs of 5-8 cm (n=38), and AAAs with a diameter over 8 cm (n=22). The average age of the patients was 70.7 (56-82) years. The male to female ratio was 4:1 (71:19). A control group consisted of 30 healthy individuals of similar age and sex presentation with no manifestation of atherosclerosis. Plasma levels of cytokines were assessed in venous blood by means of radio- or enzymo-immunoassay. Statistical processing of the results was conducted with ANOVA and Wilcoxon tests with Spearman correlation, where p<0.05 was considered to be statistically significant. Plasma concentrations of cytokines were significantly higher in AAA patients than in healthy individuals. In AAA patients the tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL-8) levels were low in large and in symptomatic AAAs. IL-6 levels were increased with increasing AAA diameter and symptoms. IL-8 levels (p<0.05) showed a statistically significant correlation with the diameter, and TNF-alpha (p<0.05) with the symptoms of AAA. IL-1beta, IL-2 and IL-6 did not show any significant changes with different AAA diameter or symptomatology.

IN CONCLUSION

IL-8 and TNF-alpha can be used as endogenous markers of the process of AAA development, in deciding for either surgical or endovascular treatment of patients when the clinical indication is not entirely clear.

Uptake of tetracycline by aortic aneurysm wall and its effect on inflammation and proteolysis

BACKGROUND

Proteolytic degradation of the aortic wall by matrix metalloproteinases (MMPs) is considered important in the pathogenesis of abdominal aortic aneurysms (AAAs). Many of these MMPs are inhibited by tetracycline derivatives, which may have the potential to retard aneurysm growth.

METHODS

Patients undergoing elective repair of an AAA (n = 5) received an intravenous bolus of tetracycline (500 mg) on induction of anaesthesia and levels of tetracycline in serum, aneurysm wall and mural thrombus were assessed by microbiological assay. In a separate series of patients (n = 7) aneurysm biopsies were placed into explant culture (with and without tetracyline) and the accumulation of protein, hydroxyproline, MMP-9, interleukin (IL) 6 and monocyte chemoattractant protein (MCP) 1 in the medium was assessed by colorimetric assay or immunoassay.

RESULTS

At aortic cross-clamping the median concentration of tetracycline was 8.3 microg/ml in serum, 2.9 microg per g tissue in aortic wall and zero in mural thrombus. Tetracycline inhibited, in a concentration-dependent manner, both MMP-9 and MCP-1 secretion (P = 0.022 and P = 0.018 respectively), but did not alter hydroxyproline or IL-6 secretion. At the highest concentration of tetracycline (100 microg/ml) median MMP-9 secretion was reduced from 27 to 5 ng/ml (P = 0.007) and median MCP-1 secretion was reduced from 50 to 10 ng/ml (P = 0.008).

CONCLUSION

Tetracycline rapidly penetrates the aortic wall, but the concentration achieved may be insufficient to alter collagen turnover through limitation of MMP production or activity.