Lack of association between fluoroquinolone and aortic aneurysm or dissection.

BACKGROUND AND AIMS: An increased risk of aortic aneurysm and aortic dissection (AA/AD) has been reported with fluoroquinolone (FQ) use. However, recent studies suggested confounding factors by indication. This study aimed to investigate the risk of AA/AD associated with FQ use. METHODS: This nationwide population-based study included adults aged ≥20 years who received a prescription of oral FQ or third-generation cephalosporins (3GC) during outpatient visits from 2005 to 2016. Data source was the National Health Insurance Service reimbursement database. The primary outcome was hospitalization or in-hospital death with a primary diagnosis of AA/AD. A self-controlled case series (SCCS) and Cox proportional hazards model were used. Self-controlled case series compared the incidence of the primary outcome in the risk period vs. the control periods. RESULTS: A total of 954 308 patients (777 109 with FQ and 177 199 with 3GC use) were included. The incidence rate ratios for AA/AD between the risk period and the pre-risk period were higher in the 3GC group [11.000; 95% confidence interval (CI) 1.420-85.200] compared to the FQ group (2.000; 95% CI 0.970-4.124). The overall incidence of AA/AD among the patients who received FQ and 3GC was 5.40 and 8.47 per 100 000 person-years. There was no significant difference in the risk between the two groups (adjusted hazard ratio 0.752; 95% CI 0.515-1.100) in the inverse probability of treatment-weighted Cox proportional hazards model. Subgroup and sensitivity analysis showed consistent results. CONCLUSIONS: There was no significant difference in the risk of AA/AD in patients who were administered oral FQ compared to those administered 3GC. The study findings suggest that the use of FQ should not be deterred when clinically indicated.

Fluoroquinolones and Risk of Aortic Aneurysm or Dissection in Patients With Congenital Aortic Disease and Marfan Syndrome.

BACKGROUND: Fluoroquinolone use can be associated with an increased risk of aortic aneurysm (AA) or aortic dissection (AD). The US Food and Drug Administration recently warned against fluoroquinolone use for high-risk patients, such as those with Marfan syndrome. However, the association between fluoroquinolone use and AA/AD risk was unknown in these high-risk patients and therefore it was studied in this work.Methods and Results: Data were collected from a national database between 2000 and 2017 for 550 patients with AA/AD and any congenital aortic disease (mean age 41.5 years; 415 with Marfan syndrome). A case cross-over study was conducted to compare the risk of aortic events (AA/AD) associated with fluoroquinolone and amoxicillin use between the hazard period (from -60 days to -1 day) and a randomly selected reference period (-180 to -121 days; -240 to -181 days; and -300 to -241 days). Compared to the reference period without fluoroquinolone use, fluoroquinolone use during the hazard period was not associated with a greater risk of AA/AD (1.09% vs. 1.09%; odds ratio [OR] 1.000; 95% confidence interval [CI] 0.32-3.10), AA (OR 0.67; 95% CI 0.11-3.99), or AD (OR 1.33; 95% CI 0.30-5.96) in patients with congenital aortic disease or Marfan syndrome. This lack of association was maintained in subgroup analysis, including Marfan syndrome or not, age (≤50 vs. >50 years) and sex. CONCLUSIONS: Fluoroquinolone use was not associated with an increased risk of AA/AD in patients with congenital aortic disease, including Marfan syndrome. More evidence is required for a fluoroquinolone pharmacovigilance plan in these patients.

Moxifloxacin induces aortic aneurysm and dissection by increasing osteopontin in mice.

Fluoroquinolones are one of the most frequently prescribed antibiotics. However, their use increases the risk of Aortic aneurysm and dissection (AAD). The mechanism underlying this effect remains unclear. AAD are caused by weakening of the aortic wall and loss of vascular smooth muscle cells. Osteopontin is involved in the occurrence and development of AAD. The aim of the present study was to examine the role of moxifloxacin, a fluoroquinolone, in the occurrence of AAD using a moderate-severity AAD mouse model. Four-week-old male C57BL/6J mice were fed a high-fat diet. At 8 weeks of age, the mice were infused with saline or angiotensin II (1000 ng kg-1 min-1) via osmotic minipumps for 4 weeks, and then orally administered water (vehicle) or moxifloxacin (30 and 100 mg kg-1 day-1) for another 3 weeks. Moxifloxacin (30 and 100 mg kg-1 day-1) induced AAD and elastin degradation in aortic tissues, as revealed by hematoxylin and eosin staining and elastica-van Gieson staining. Additionally, immunohistochemical staining and Western blot analyses showed that moxifloxacin 100 mg kg-1 day-1 decreased the protein expression of smooth muscle protein 22α, one of the markers of the contractile phenotype of vascular smooth muscle cells, in aortic tissues compared to vehicle and moxifloxacin 30 mg kg-1 day-1. Furthermore, moxifloxacin (100 mg kg-1 day-1) increased the protein expression of osteopontin and matrix metalloproteinases-2 in the aortic tissues when compared to control. Moxifloxacin may induce the onset of AAD and weakening of the aortic media by increasing the expression of osteopontin and matrix metalloproteinase-2 and decreasing that of smooth muscle protein 22α in aortic tissue.

Early Detection of Aortic Degeneration in a Mouse Model of Sporadic Aortic Aneurysm and Dissection Using Nanoparticle Contrast-Enhanced Computed Tomography.

[Figure: see text].

Risk of aortic aneurysm and aortic dissection with the use of fluoroquinolones in Korea: a nested case-control study.

BACKGROUND: Recent studies have raised concern about the association of fluoroquinolones with an increased risk of aortic aneurysm and aortic dissection. We aimed to evaluate such risk in a Korean population. METHODS: We conducted a nested case-control study using data from the National Health Insurance Service collected from 2013 to 2017 in Korea. The study cohort included patients older than 40 years and excluded patients who had used fluoroquinolones or been diagnosed with aortic aneurysm, aortic dissection, or related diseases 1 year prior to the cohort entry date. We randomly matched four controls in the risk set with each case of aortic aneurysm and aortic dissection (same sex, age, and cohort entry date). We assessed the risk of aortic aneurysm and aortic dissection from fluoroquinolones and adjusted for potential confounders using a conditional logistic regression model. RESULTS: A total of 29,638 aortic aneurysm and aortic dissection patients were identified between 2014 and 2017. The use of fluoroquinolones within a year was associated with a 10% increased risk of aortic aneurysm and aortic dissection (adjusted odds ratio: 1.10, 95% CI 1.07-1.14, p < 0.05) compared with nonusers. The risk was higher in patients who had used fluoroquinolones within 60 days (adjusted odds ratio: 1.53, 95% CI 1.46-1.62, p < 0.05). The risk of aortic aneurysm and aortic dissection positively correlated with the cumulative dose and duration of fluoroquinolone therapy (p < 0.001). CONCLUSIONS: Our study provides real-world evidence of the risk of aortic aneurysm and aortic dissection from fluoroquinolones in Korea. Patients and medical professionals should be aware that fluoroquinolones can increase the risk of aortic aneurysm and aortic dissection, which may be acerbated by high dosage and duration of use.

Fluoroquinolones vs. amoxicillin-clavulanate or ampicillin-sulbactam were not linked to aortic aneurysm or dissection.

SOURCE CITATION: Dong YH, Chang CH, Wang JL, et al. Association of infections and use of fluoroquinolones with the risk of aortic aneurysm or aortic dissection. JAMA Intern Med. 2020;180:1587-95. 32897358.

Current progress of fluoroquinolones-increased risk of aortic aneurysm and dissection.

Aortic aneurysm (AA) and aortic dissection (AD) are major life-threatening diseases around the world. AA is a localized or diffuse dilation of the aorta, while AD is the separation of the layers creating a false lumen within the aortic wall. Fluoroquinolones (FQ) remain one of the most important kind of antibiotics and have a wider clinical use and broad antibacterial spectrum. FQ were also reported to treat infected AA. The most common adverse events (AEs) of FQ are mild and reversible, like headaches, diarrhea and nausea. Due to FQ-related serious AEs, such as tendonitis and tendon rupture, chondrotoxicity, or retinal detachment, QT-prolongation and dysglycemia, the United States Food and Drug Administration (FDA) issued a black box warning for FQ for systemic use in 2016 and updated warnings for FQ several times since then. Of note, in December 2018, FDA issued several "black box warnings" against FQ with the latest safety announcement warning about an increased risk of ruptures in the aorta blood vessel in certain patients. Recently, many studies have indicated an association between FQ and an increase risk of AA and AD. However, the exact mechanism of FQ-induced AA/AD remains unclear. This review aims to highlight the latest research progress of the alarming association between FQ and AA/AD. Moreover, molecular mechanisms of FQ in increasing risk of AA and AD are explored. Hopefully, this review can provide novel insights into FQ-increased the risk of AA/AD and a starting place for stewardship interventions.

Vascular Smooth Muscle Cell Plasticity and Autophagy in Dissecting Aortic Aneurysms.

Objective- Recent studies suggested the occurrence of phenotypic switching of vascular smooth muscle cells (VSMCs) during the development of aortic aneurysm (AA). However, lineage-tracing studies are still lacking, and the behavior of VSMCs during the formation of dissecting AA is poorly understood. Approach and Results- We used multicolor lineage tracing of VSMCs to track their fate after injury in murine models of Ang II (angiotensin II)-induced dissecting AA. We also addressed the direct impact of autophagy on the response of VSMCs to AA dissection. Finally, we studied the relevance of these processes to human AAs. Here, we show that a subset of medial VSMCs undergoes clonal expansion and that VSMC outgrowths are observed in the adventitia and borders of the false channel during Ang II-induced development of dissecting AA. The clonally expanded VSMCs undergo phenotypic switching with downregulation of VSMC differentiation markers and upregulation of phagocytic markers, indicative of functional changes. In particular, autophagy and endoplasmic reticulum stress responses are activated in the injured VSMCs. Loss of autophagy in VSMCs through deletion of autophagy protein 5 gene ( Atg5) increases the susceptibility of VSMCs to death, enhances endoplasmic reticulum stress activation, and promotes IRE (inositol-requiring enzyme) 1α-dependent VSMC inflammation. These alterations culminate in increased severity of aortic disease and higher incidence of fatal AA dissection in mice with VSMC-restricted deletion of Atg5. We also report increased expression of autophagy and endoplasmic reticulum stress markers in VSMCs of human dissecting AAs. Conclusions- VSMCs undergo clonal expansion and phenotypic switching in Ang II-induced dissecting AAs in mice. We also identify a critical role for autophagy in regulating VSMC death and endoplasmic reticulum stress-dependent inflammation with important consequences for aortic wall homeostasis and repair.

Resveratrol Attenuates Aortic Dissection by Increasing Endothelial Barrier Function Through the SIRT1 Pathway.

Aortic dissection (AD) is a serious condition and a health issue on a global scale. ß-Aminopropionitrile-induced AD in mice is similar to the pathogenesis of AD in humans. Resveratrol (RSV) is a natural polyphenolic substance that provides anti-inflammatory and cardiovascular effects, but the role of RSV in AD is unclear. In this study, we investigated the effects and mechanisms of RSV on ß-aminopropionitrile-induced AD in mice. Our results indicate that RSV can prevent the occurrence of AD. More meaningfully, we found that the protective effect comprises an increase in sirtuin 1 (SIRT1) expression in endothelial cells for the reconstruction of their structure, reducing the recruitment of inflammatory cells by endothelial cells and inhibiting the inflammation response, thereby suppressing the occurrence of AD.

Relationship between fluoroquinolones and the risk of aortic diseases: a meta-analysis of observational studies.

BACKGROUND: Our aim was to determine the relationship between the use of fluoroquinolones and the risk of aortic diseases. METHODS: PubMed, EMBASE and the Web of Science were searched from inception to July 6, 2019, to identify observational studies that evaluated the risk of aortic diseases associated in users of fluoroquinolones compared with nonusers or users of other antibiotics. The primary outcome was the first occurrence of aortic diseases. We used the GRADE approach to rate the strength of evidence. We used the inverse variance method random-effect model to estimate the odds ratios (ORs) with 95% CIs, and statistical heterogeneity was assessed by the I2 statistic. RESULTS: This meta-analysis enrolled 2,829,385 patients reported the relationship between fluoroquinolones and the risk of aortic diseases. Compared with nonusers or users of other antibiotics, users of fluoroquinolone had a significantly increased risk of aortic diseases (adjusted OR, 2.10; 95% CI, 1.65-2.68; P = .000, I2 = 16.4%). The quality of evidence was moderate, and the number needed to harm (NNH) for aortic diseases among patients was estimated to be 1301. CONCLUSIONS: The fluoroquinolone use in patients significantly increases the risk of new-onset aortic diseases. Clinicians need to pay attention to these severe adverse events when considering fluoroquinolone use.

Preventive Effects of Quercetin against the Onset of Atherosclerosis-Related Acute Aortic Syndromes in Mice.

Atherosclerosis-related acute aortic syndromes, such as aortic aneurysms or aortic dissection are life-threatening diseases. Since they develop suddenly and progress rapidly, the establishment of preventive strategies is urgently needed. Quercetin, a flavonoid abundant in various vegetables and fruits, is suggested to reduce the risk of cardiovascular disease. Therefore, in this study, the preventive effect of quercetin was evaluated using a mouse model of aortic aneurysm and dissection. The model was established by administering angiotensin II (Ang II) and ß-aminopropionitrile (BAPN), a lysyl oxidase inhibitor, to mice to induce hypertension and degeneration of the elastic lamina, which would eventually result in the onset of an aortic aneurysm. Ang II, BAPN, and a nitric oxide synthase inhibitor was administered to induce aortic dissection via endothelial dysfunction. Quercetin (60 mg/kg/day) was administered 2 weeks before inducing aortic diseases by the end of the experiments (8 weeks in the aneurysm model, 6 weeks in the dissection model). It was found to reduce the incidence of aneurysm (from 72 to 45%), dissection (from 17 to 10%), and rupture (from 33 to 15%) in mice. Elastin degradation was ameliorated in the quercetin-treated mice compared to that in the mice without quercetin treatment (degradation score 2.9 ± 0.3 vs 2.2 ± 0.2). Furthermore, quercetin suppressed the expression of vascular cell adhesion molecule-1, macrophage infiltration, and pro-matrix metalloproteinase-9 activity. Our results suggest that quercetin might prevent the onset of atherosclerosis-related acute aortic syndromes through its anti-inflammatory and endothelial cell-protective effects.

Mesenchymal stem cell-derived conditioned medium attenuate angiotensin II-induced aortic aneurysm growth by modulating macrophage polarization.

Mesenchymal stem cells (MSCs) exhibit therapeutic benefits on aortic aneurysm (AA); however, the molecular mechanisms are not fully understood. The current study aimed to investigate the therapeutic effects and potential mechanisms of murine bone marrow MSC (BM-MSCs)-derived conditioned medium (MSCs-CM) on angiotensin II (AngII)-induced AA in apolipoprotein E-deficient (apoE-/- ) mice. Murine BM-MSCs, MSCs-CM or control medium were intravenously administrated into AngII-induced AA in apoE-/- mice. Mice were sacrificed at 2 weeks after injection. BM-MSCs and MSCs-CM significantly attenuated matrix metalloproteinase (MMP)-2 and MMP-9 expression, aortic elastin degradation and AA growth at the site of AA. These treatments with BM-MSCs and MSCs-CM also decreased Ly6chigh monocytes in peripheral blood on day 7 and M1 macrophage infiltration in AA tissues on day 14, whereas they increased M2 macrophages. In addition, BM-MSCs and MSCs-CM reduced MCP-1, IL-1Ra and IL-6 expression and increased IL-10 expression in AA tissues. In vitro, peritoneal macrophages were co-cultured with BM-MSCs or fibroblasts as control in a transwell system. The mRNA and protein expression of M2 macrophage markers were evaluated. IL-6 and IL-1ß were reduced, while IL-10 was increased in the BM-MSC systems. The mRNA and protein expression of M2 markers were up-regulated in the BM-MSC systems. Furthermore, high concentration of IGF1, VEGF and TGF-ß1 was detected in MSCs-CM. Our results suggest that MSCs-CM could prevent AA growth potentially through regulating macrophage polarization. These results may provide a new insight into the mechanisms of BM-MSCs in the therapy of AA.

SPECT/CT imaging of apoptosis in aortic aneurysm with radiolabeled duramycin.

The objective of this research was to estimate whether a [99mTc]duramycin probe can be used for apoptosis imaging in patients with aortic aneurysm (AA). Vascular smooth muscle cell (SMC) apoptosis has an important influence on AA development. Thus, non-invasive imaging of SMC apoptosis may be able to evaluate AA progress and risk stratification. SMCs were treated with hydrogen peroxide (H2O2; 200 µΜ) or culture medium as a control. Apoptosis was measured using flow cytometry and [99mTc]duramycin to detect the binding efficiency to apoptotic SMCs. C57/BL6 mice were administered angiotensin-II and beta-aminopropionitrile (BAPN) subcutaneously to establish an AA model, or saline for controls. Aortic specimens underwent pathological evaluation and their aortic diameters were measured after 6 weeks. Micro-SPECT/CT scanning of [99mTc]duramycin and 18F-FDG PET detection were performed. SMCs treated with H2O2 showed more apoptosis compared with the control group (67.2 ± 3.8% vs. 16.1 ± 0.6%, P < 0.01). The experimental group showed a high rate of AA formation (70%) compared with no AA formation in the control group. The average aorta diameter was higher and [99mTc]duramycin uptake at the AA site was higher in the experimental group compared with the control group. Compared with the normal aorta in the control group, AA in experiment group had more severe medial degeneration, elastic fiber reduction and fracture, and collagen degeneration. TUNEL staining verified the higher apoptosis rate at the AA site in experiment group compared with the control group (63.9 ± 3.7% in ascending AA, 66.4 ± 4.0% in thoracic AA, vs. 3.5 ± 0.3% in normal aorta, P < 0.01). [99mTc]Duramycin may be an effective probe to evaluate apoptosis in AA.

The oral administration of clarithromycin prevents the progression and rupture of aortic aneurysm.

OBJECTIVE: The pathogenesis of aortic aneurysm (AA) is associated with chronic inflammation in the aortic wall with increased levels of matrix metalloproteinases (MMPs). Clarithromycin (CAM) has been reported to suppresses MMP activity. In this study, we investigated whether CAM could prevent the formation and rupture of AA. METHODS: Male apolipoprotein E-deficient mice (28-30 weeks of age) were infused with angiotensin II for 28 days. CAM (100 mg/kg/d) or saline (as a control) was administered orally to the mice every day (CAM group, n = 13; control group, n = 13). After the administration period, the aortic diameter, elastin content, macrophage infiltration, MMP levels, and levels of inflammatory cytokines, including nuclear factor κB (NF-κB), were measured. RESULTS: The aortic diameter was significantly suppressed in the CAM group (P < .001). No rupture death was observed in the CAM group in contrast to five deaths (38%) in the control group (P < .01). CAM significantly suppressed the degradation of aortic elastin (56.3% vs 16.5%; P < .001) and decreased the infiltration of inflammatory macrophages (0.05 vs 0.16; P < .01). Compared with the controls, the enzymatic activity of MMP-2 and MMP-9 was significantly reduced in the CAM group (MMP-2, 0.15 vs 0.56 [P < .01]; MMP-9, 0.12 vs 0.60 [P < .01]), and the levels of interleukin 1ß (346.6 vs 1066.0; P < .05), interleukin 6 (128.4 vs 346.2; P < .05), and phosphorylation of NF-κB were also decreased (0.3 vs 2.0; P < .01). CONCLUSIONS: CAM suppressed the progression and rupture of AA through the suppression of inflammatory macrophage infiltration, a reduction in MMP-2 and MMP-9 activity, and the inhibition of elastin degradation associated with the suppression of NF-κB phosphorylation.

Tracking Monocyte Recruitment and Macrophage Accumulation in Atherosclerotic Plaque Progression Using a Novel hCD68GFP/ApoE-/- Reporter Mouse-Brief Report.

OBJECTIVE: To create a model of atherosclerosis using green fluorescent protein (GFP)-targeted monocytes/macrophages, allowing analysis of both endogenous GFP+ and adoptively transferred GFP+ myeloid cells in arterial inflammation. APPROACH AND RESULTS: hCD68GFP reporter mice were crossed with ApoE-/- mice. Expression of GFP was localized to macrophages in atherosclerotic plaques and in angiotensin II-induced aortic aneurysms and correlated with galectin 3 and mCD68 expression. Flow cytometry confirmed GFP+ expression in CD11b+/CD64+, CD11c+/MHC-IIHI, and CD11b+/F4/80+ myeloid cells. Adoptive transfer of GFP+ monocytes demonstrated monocyte recruitment to both adventitia and atherosclerotic plaque, throughout the aortic root, within 72 hours. We demonstrated the biological utility of hCD68GFP monocytes by comparing the recruitment of wild-type and CCR2-/- monocytes to sites of inflammation. CONCLUSIONS: hCD68GFP/ApoE-/- mice provide a new approach to study macrophage accumulation in atherosclerotic plaque progression and to identify cells recruited from adoptively transferred monocytes.

Wnt Signaling Pathway Inhibitor Sclerostin Inhibits Angiotensin II-Induced Aortic Aneurysm and Atherosclerosis.

OBJECTIVE: Sclerostin (SOST) has been identified as an important regulator of bone formation; however, it has not been previously implicated in arterial disease. The aim of this study was to assess the role of SOST in aortic aneurysm (AA) and atherosclerosis using human samples, a mouse model, and in vitro investigations. APPROACH AND RESULTS: SOST protein was downregulated in human and mouse AA samples compared with controls. Transgenic introduction of human SOST in apolipoprotein E-deficient (ApoE-/-) mice (SOSTTg .ApoE-/-) and administration of recombinant mouse Sost inhibited angiotensin II-induced AA and atherosclerosis. Serum concentrations of several proinflammatory cytokines were significantly reduced in SOSTTg .ApoE-/- mice. Compared with controls, the aortas of mice receiving recombinant mouse Sost and SOSTTg .ApoE-/- mice showed reduced matrix degradation, reduced elastin breaks, and preserved collagen. Decreased inflammatory cell infiltration and a reduction in the expression of wingless-type mouse mammary virus integration site/ß-catenin responsive genes, including matrix metalloproteinase-9, osteoprotegerin, and osteopontin, were observed in the aortas of SOSTTg .ApoE-/- mice. SOST expression was downregulated and the wingless-type mouse mammary virus integration site/ß-catenin pathway was activated in human AA samples. The cytosine-phosphate-guanine islands in the SOST gene promoter showed significantly higher methylation in human AA samples compared with controls. Incubation of vascular smooth muscle cells with the demethylating agent 5-azacytidine resulted in upregulation of SOST, suggesting that SOST is epigenetically regulated. CONCLUSIONS: This study identifies that SOST is expressed in the aorta and downregulated in human AA possibly because of epigenetic silencing. Upregulating SOST inhibits AA and atherosclerosis development, with potential important implications for treating these vascular diseases.

Nitrosonifedipine, a Photodegradation Product of Nifedipine, Suppresses Pharmacologically Induced Aortic Aneurysm Formation.

BACKGROUND/AIMS: We have reported that nitrosonifedipine (NO-NIF), a photodegradation product of nifedipine, has strong antioxidant and endothelial protective effects, and can suppress several cardiovascular diseases in animal models. The objective of the present study was to investigate the effects of NO-NIF on aortic aneurysm formation. METHODS: The mice were infused with ß-aminopropionitrile for 2 weeks and angiotensin II for 6 weeks to induce aortic aneurysm formation. The oxidative stress was measured by dihydroethidium staining and nitrotyrosine staining. The expressions of inflammation-related genes were assessed by quantitative real-time PCR and immunohistochemical staining. To clarify the mechanisms of how NO-NIF suppresses vascular cell adhesion molecule (VCAM)-1, endothelial cells were used in in vitro system. RESULTS: NO-NIF suppressed pharmacologically induced the aortic aneurysm formation and aortic expansion without blood pressure changes. NO-NIF suppressed elastin degradation and matrix metalloproteinase-2 mRNA expression. NO-NIF suppressed the reactive oxygen species-cyclophilin A positive feedback loop. Upregulated mRNA expressions of inflammation-related genes and endothelial VCAM-1 were suppressed by NO-NIF co-treatment in aortae. CONCLUSION: NO-NIF has the potential to be a new, nifedipine-derived therapeutic drug for suppressing aortic aneurysm formation by directly improving aortic structure with its strong ability to reduce oxidative stress and inflammation.

KLF15 Overexpression Protects ß-Aminopropionitrile-Induced Aortic Rupture in Rodent Model via Inhibiting Connective Tissue Growth Factor.

Background KLF15 (Krüppel-like factor 15) was reported to be involved in a lot of cardiovascular diseases. Little is known about its role in initiation and development of aortic dissection (AD). Methods Samples of the human aorta were collected during AD surgery and aortic valve replacement. Lentivirus was used for in vitro and in vivo KLF15 overexpression in BAPN (ß-aminopropionitrile)-induced rat AD models. The survival times were recorded and compared between the two groups. Autopsy was used for confirming aorta rupture in rat models. qPCR analyses were used for detecting gene expression whereas Western blot and immunostaining were used for detecting protein expression when necessary. Results KLF15 expression was much lower in the aorta walls of AD group patients than the control group subjects. The survival curve showed that the survival time of AD models was prolonged after KLF15 overexpression. qPCR and Western blot showed that connective tissue growth factors (CTGFs) were significantly downregulated in the rat aortas. After KLF15 overexpression in aortic adventitial fibroblasts, the KLF15 mRNA was increased whereas CTGF and its target gene collagens I and III were downregulated. Immunofluorescence staining also showed a decrease in CTGF, collagen I, and III. Lenti-control did not induce a significant change of KLF15, CTGF, collagen I, and III expressions. Conclusions KLF15 is involved in the mechanism of AD formation in human. Overexpression of KLF15 can partially rescue the aorta remodeling and AD formation in animal models. Our research highlighted a potential of KLF15 to serve as a new therapy target of AD.

Thrombospondin-4 knockout in hypertension protects small-artery endothelial function but induces aortic aneurysms.

Thrombospondin-4 (TSP-4) is a multidomain calcium-binding protein that has both intracellular and extracellular functions. As an extracellular matrix protein, it is involved in remodeling processes. Previous work showed that, in the cardiovascular system, TSP-4 expression is induced in the heart in response to experimental pressure overload and infarction injury. Intracellularly, it mediates the endoplasmic reticulum stress response in the heart. In this study, we explored the role of TSP-4 in hypertension. For this purpose, wild-type and TSP-4 knockout (Thbs4(-/-)) mice were treated with angiotensin II (ANG II). Hearts from ANG II-treated Thbs4(-/-) mice showed an exaggerated hypertrophic response. Interestingly, aortas from Thbs4(-/-) mice treated with ANG II showed a high incidence of aneurysms. In resistance arteries, ANG II-treated wild-type mice showed impaired endothelial-dependent relaxation. This was not observed in ANG II-treated Thbs4(-/-) mice or in untreated controls. No differences were found in the passive pressure-diameter curves or stress-strain relationships, although ANG II-treated Thbs4(-/-) mice showed a tendency to be less stiff, associated with thicker diameters of the collagen fibers as revealed by electron microscopy. We conclude that TSP-4 plays a role in hypertension, affecting cardiac hypertrophy, aortic aneurysm formation, as well as endothelial-dependent relaxation in resistance arteries.