Effect of Ciprofloxacin on Susceptibility to Aortic Dissection and Rupture in Mice

Importance

Fluoroquinolones are among the most commonly prescribed antibiotics. Recent clinical studies indicated an association between fluoroquinolone use and increased risk of aortic aneurysm and dissection (AAD). This alarming association has raised concern, especially in patients with AAD with risk of rupture and in individuals at risk for developing AAD.

Objective

To examine the effect of ciprofloxacin on AAD development in mice.

Design, Setting, and Participants

In a mouse model of moderate, sporadic AAD, 4-week-old male and female C57BL/6J mice were challenged with a high-fat diet and low-dose angiotensin infusion (1000 ng/min/kg). Control unchallenged mice were fed a normal diet and infused with saline. After randomization, challenged and unchallenged mice received ciprofloxacin (100 mg/kg/d) or vehicle through daily gavage during angiotensin or saline infusion. Aortic aneurysm and dissection development and aortic destruction were compared between mice. The direct effects of ciprofloxacin on aortic smooth muscle cells were examined in cultured cells.

Results

No notable aortic destruction was observed in unchallenged mice that received ciprofloxacin alone. Aortic challenge induced moderate aortic destruction with development of AAD in 17 of 38 mice (45%) and severe AAD in 9 (24%) but no rupture or death. However, challenged mice that received ciprofloxacin had severe aortic destruction and a significantly increased incidence of AAD (38 of 48 [79%]; P = .001; χ2 = 10.9), severe AAD (32 of 48 [67%]; P < .001; χ2 = 15.7), and rupture and premature death (7 of 48 [15%]; P = .01; χ2 = 6.0). The increased AAD incidence was observed in different aortic segments and was similar between male and female mice. Compared with aortic tissues from challenged control mice, those from challenged mice that received ciprofloxacin showed decreased expression of lysyl oxidase, an enzyme that is critical in the assembly and stabilization of elastic fibers and collagen. These aortas also showed increased matrix metalloproteinase levels and activity, elastic fiber fragmentation, and aortic cell injury. In cultured smooth muscle cells, ciprofloxacin treatment significantly reduced lysyl oxidase expression and activity, increased matrix metalloproteinase expression and activity, suppressed cell proliferation, and induced cell death. Furthermore, ciprofloxacin-a DNA topoisomerase inhibitor-caused nuclear and mitochondrial DNA damage and the release of DNA into the cytosol, subsequently inducing mitochondrial dysfunction, reactive oxygen species production, and activation of the cytosolic DNA sensor STING, which we further showed was involved in the suppression of lysyl oxidase expression and induction of matrix metalloproteinase expression.

Conclusions and Relevance

Ciprofloxacin increases susceptibility to aortic dissection and rupture in a mouse model of moderate, sporadic AAD. Ciprofloxacin should be used with caution in patients with aortic dilatation, as well as in those at high risk for AAD.

Abstract 317: Inflammasome Inhibitor MCC950 Prevents the Development of Sporadic Thoracic and Abdominal Aortic Aneurysms and Dissections in Mice

Background: Aortic aneurysms and dissections (AAD) are common interrelated cardiovascular diseases that cause more than 10,000 deaths in the United States each year and are a leading cause of death in people 55 years of age or older. Currently, surgery is the only effective treatment; thus, there is a critical need to develop pharmacological agents that can prevent the initiation or progression of AAD. Increasing evidence suggests that the NLRP3 inflammasome plays a critical role in aortic destruction. In this study, we aimed to test the therapeutic potential of MCC950, a potent and specific NLRP3 inhibitor, for preventing AAD.

Methods/Results: In a sporadic AAD model induced by a high-fat diet and angiotensin II infusion,, aortic challenge induced significant aortic enlargement and the development of a range of AAD manifestations, including aneurysm without dissection, dissection, and rupture. Importantly, MCC950 treatment significantly inhibited aortic enlargement and the development of AAD, particularly in the ascending and suprarenal aorta. The overall incidence of AAD decreased from 86% in the challenged control group to 40% in the challenged MCC950 treatment group ( P <0.001). The incidence of ascending AAD decreased from 56% in the challenged control group to 18% in the challenged MCC950 treatment group ( P =0.0001), and the incidence of suprarenal AAD decreased from 60% in the challenged control group to 20% in the challenged MCC950 treatment group ( P <0.001). The reduction in AAD incidence was similar in male and female mice. Furthermore, aortas from the MCC950 group showed reductions in inflammasome activation, macrophage infiltration, MMP-9 activity, and elastic fiber destruction. Likewise, in the cultured macrophages, MCC950 treatment inhibited H 2 O 2 -induced activation of the NLRP3 inflammasome, IL-1β secretion, and MMP-9 activation.

Conclusion: The NLRP3 inhibitor MCC950 is effective at preventing inflammasome activation, aortic destruction, inflammation, and the development of AAD in a mouse model of sporadic disease. Further studies are needed to determine whether MCC950 has similar effects in other AAD models.

How can genetic diagnosis inform the decision of when to operate?

Genetic discovery for heritable thoracic aortic disease (HTAD) has been progressing at a brisk pace. Surgical management of thoracic aortic aneurysms and dissections has become more personalized, with genetic factors increasingly informing the decision of when to operate on patients. An improved understanding of genotype-phenotype correlations in patients with HTAD will ultimately lead to gene- and mutation-specific recommendations for surgical repair. Until more robust data from larger cohorts can inform our decisions, patients with HTAD should be seen by an aortic specialist for a tailored approach to elective surgical repair.

Aortic Dilatation Associated With Bicuspid Aortic Valve: Relation to Sex, Hemodynamics, and Valve Morphology (the National Heart Lung and Blood Institute-Sponsored National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions)

This study analyzed the impact of sex, hemodynamic profile, and valve fusion pattern on aortopathy associated with bicuspid aortic valve (BAV). The National Heart Lung and Blood Institute-sponsored National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC) provided comprehensive information on a large population of well-characterized patients with BAV. Of 969 enrolled patients with BAV, 551 (57%, 77% male) had already undergone valvular and/or aortic surgery. Echocardiographic imaging data were available on 339 unoperated or preoperative participants who formed the basis of this study. BAV function was normal in 45 (14%), with a predominant aortic regurgitation (AR) in 127 (41%) and a predominant aortic stenosis (AS) in 76 (22%). Moderate-severe AR was associated with larger sinus of Valsalva (SOV) diameters compared with normal function and AS (all p <0.01). Moderate-severe AS was associated with a larger ascending aortic (AscAo) diameter compared with normal function (p = 0.003) but not with AR. The SOV diameter was larger in men than in women (3.7 ± 0.7 vs 3.3 ± 0.6 cm, p <0.0001), whereas AscAo diameters were comparable (3.9 ± 0.9 vs 3.7 ± 0.9 cm, p = 0.08). Right-left commissural fusion was associated with a larger SOV diameter (3.7 ± 0.7 vs 3.3 ± 0.6 cm, p <0.0001) compared with a right-noncoronary fusion pattern. Predominant AR was more common in men (45% vs 27%, p = 0.004), whereas AS was more common in women (29% vs 18%, p = 0.04). In conclusion, in the GenTAC Registry, AR was associated with diffuse (annular, SOV, and AscAo) enlargement, whereas moderate-severe AS was only associated with AscAo enlargement. Male sex and right-left cusp pattern of cusp fusion were associated with larger SOV diameters and a greater likelihood of AR, whereas women had a higher prevalence of AS.

Critical Role of ADAMTS-4 in the Development of Sporadic Aortic Aneurysm and Dissection in Mice

Sporadic aortic aneurysm and dissections (AADs) are common vascular diseases that carry a high mortality rate. ADAMTS-4 (a disintegrin-like and metalloproteinase with thrombospondin motifs-4) is a secreted proteinase involved in inflammation and matrix degradation. We previously showed ADAMTS-4 levels were increased in human sporadic descending thoracic AAD (TAAD) samples. Here, we provide evidence that ADAMTS-4 contributes to aortic destruction and sporadic AAD development. In a mouse model of sporadic AAD induced by a high-fat diet and angiotensin II infusion, ADAMTS-4 deficiency (Adamts-4−/−) significantly reduced challenge-induced aortic diameter enlargement, aneurysm formation, dissection and aortic rupture. Aortas in Adamts-4−/− mice showed reduced elastic fibre destruction, versican degradation, macrophage infiltration, and apoptosis. Interestingly, ADAMTS-4 was directly involved in smooth muscle cell (SMC) apoptosis. Under stress, ADAMTS-4 translocated to the nucleus in SMCs, especially in apoptotic SMCs. ADAMTS-4 directly cleaved and degraded poly ADP ribose polymerase-1 (a key molecule in DNA repair and cell survival), leading to SMC apoptosis. Finally, we showed significant ADAMTS-4 expression in aortic tissues from patients with sporadic ascending TAAD, particularly in SMCs. Our findings indicate that ADAMTS-4 induces SMC apoptosis, degrades versican, promotes inflammatory cell infiltration, and thus contributes to sporadic AAD development.

Are outcomes of thoracoabdominal aortic aneurysm repair different in men versus women? A propensity-matched comparison

OBJECTIVE

Women fare worse than men after many cardiovascular operations, including coronary artery bypass grafting and valve surgery. We sought to determine whether sex affects outcomes after open thoracoabdominal aortic aneurysm repair.

METHODS

We evaluated data on 3353 consecutive patients (1281 women, 38.2%) who underwent open thoracoabdominal aortic aneurysm repair between October 1986 and July 2015. We compared preoperative characteristics, surgical variables, and outcomes between men and women in the overall group. A propensity-matching analysis was performed to adjust for preoperative and intraoperative differences. A multivariable analysis was conducted to identify predictors of poor outcomes using relevant preoperative and intraoperative factors.

RESULTS

Men had a significantly higher prevalence of comorbid conditions, including coronary artery disease, and presented more often with dissection; women were slightly older than men (median age, 69 [62-74] years vs 67 [57-73] years; P < .001) and more often symptomatic. Men underwent extent II and IV repairs more often, whereas women more often had extent I and III repairs. The propensity analysis resulted in 958 matched pairs. Overall, women and men had similar early mortality (7.9% vs 7.2%, P = .5) and adverse event rates (14.8% vs 14.1%, P = .6), which were similar in propensity-matched groups. Multivariable analysis showed that predictors of operative death and adverse event differed between the sexes. Survival and freedom from repair failure were similar between the overall and matched groups.

CONCLUSIONS

Men and women who undergo thoracoabdominal aortic aneurysm repair have similar outcomes, but there are important differences in several perioperative factors and predictors of poor outcomes.

Associations of Age and Sex With Marfan Phenotype: The National Heart, Lung, and Blood Institute GenTAC (Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions) Registry

BACKGROUND

The associations of age and sex with phenotypic features of Marfan syndrome have not been systematically examined in a large cohort of both children and adults.

METHODS AND RESULTS

We evaluated 789 Marfan patients enrolled in the National Heart, Lung, and Blood Institute GenTAC (Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions) Registry (53% male; mean age 31 [range: 1-86 years]). Females aged ≥15 and males aged ≥16 years were considered adults based on average age of skeletal maturity. Adults (n=606) were more likely than children (n=183) likely to have spontaneous pneumothorax, scoliosis, and striae but were comparable in revised Ghent systemic score, ectopia lentis, and most phenotypic features, including prevalence of aortic root dilatation. Prophylactic aortic root replacement and mitral valve surgery were rare during childhood versus adulthood (2% versus 35% and 1% versus 9%, respectively, both P<0.0001). Adult males were more likely than females to have aortic root dilatation (92% versus 84%), aortic regurgitation (55% versus 36%), and to have undergone prophylactic aortic root replacement (47% versus 24%), all P<0.001. Prevalence of previous aortic dissection tended to be higher in males than females (25% versus 18%, P=0.06); 44% of dissections were type B. Type B dissection was strongly associated with previous prophylactic aortic root replacement.

CONCLUSIONS

Pulmonary, skeletal, and aortic complications, but not other phenotypic features, are more prevalent in adults than children in Marfan syndrome. Aortic aneurysms and prophylactic aortic surgery are more common in men. Aortic dissection, commonly type B, occurs in an appreciable proportion of Marfan patients, especially in men and after previous prophylactic aortic root replacement.

STING-IRF3 Triggers Endothelial Inflammation in Response to Free Fatty Acid-Induced Mitochondrial Damage in Diet-Induced Obesity

OBJECTIVE

Metabolic stress in obesity induces endothelial inflammation and activation, which initiates adipose tissue inflammation, insulin resistance, and cardiovascular diseases. However, the mechanisms underlying endothelial inflammation induction are not completely understood. Stimulator of interferon genes (STING) is an important molecule in immunity and inflammation. In the present study, we sought to determine the role of STING in palmitic acid-induced endothelial activation/inflammation.

APPROACH AND RESULTS

In cultured endothelial cells, palmitic acid treatment activated STING, as indicated by its perinuclear translocation and binding to interferon regulatory factor 3 (IRF3), leading to IRF3 phosphorylation and nuclear translocation. The activated IRF3 bound to the promoter of ICAM-1 (intercellular adhesion molecule 1) and induced ICAM-1 expression and monocyte-endothelial cell adhesion. When analyzing the upstream signaling, we found that palmitic acid activated STING by inducing mitochondrial damage. Palmitic acid treatment caused mitochondrial damage and leakage of mitochondrial DNA into the cytosol. Through the cytosolic DNA sensor cGAS (cyclic GMP-AMP synthase), the mitochondrial damage and leaked cytosolic mitochondrial DNA activated the STING-IRF3 pathway and increased ICAM-1 expression. In mice with diet-induced obesity, the STING-IRF3 pathway was activated in adipose tissue. However, STING deficiency (Stinggt/gt ) partially prevented diet-induced adipose tissue inflammation, obesity, insulin resistance, and glucose intolerance.

CONCLUSIONS

The mitochondrial damage-cGAS-STING-IRF3 pathway is critically involved in metabolic stress-induced endothelial inflammation. STING may be a potential therapeutic target for preventing cardiovascular diseases and insulin resistance in obese individuals.

Cardiac Arrhythmia After Open Thoracoabdominal Aortic Aneurysm Repair

BACKGROUND

Cardiac arrhythmias commonly arise after cardiac surgery and are associated with poor prognosis. In thoracoabdominal aortic aneurysm (TAAA) repair, these complications are poorly understood. We assessed characteristics, incidence, outcomes, and potential predictors of postoperative arrhythmia (PA) after open TAAA repair.

METHODS

From 2010 to 2014, 403 consecutive open TAAA replacement operations were performed in patients without preoperative cardiac rhythm abnormalities at a single tertiary center. We compared preoperative characteristics, operative factors, and postoperative outcomes in patients with and without PA, and we used multivariable logistic regression to identify predictors of PA.

RESULTS

PA occurred after 107 (26.5%) procedures. Atrial fibrillation (23%) was the most common type of PA. Length of hospital stay and operative mortality were greater in patients with PA than in patients without it (p < 0.01 for both). Kaplan-Meier cumulative survival for patients with PA was lower than for patients without PA: 69.2% ± 4.6% versus 88.3% ± 2.0% at 1 year and 59.0% ± 5.3% versus 85.0% ± 2.3% at 3 years (p < 0.001 for both). The odds of PA increased with advancing age (1.07 per year; p < 0.001). In addition, the odds of developing PA were higher in patients who received visceral perfusion (odds ratio, 2.58; p = 0.001) and were lower in patients who underwent extent IV repair (odds ratio, 0.44; p = 0.01).

CONCLUSIONS

Postoperative cardiac arrhythmia was common after open TAAA repair. Older patients and patients who underwent visceral perfusion were more likely to develop PA. Cardiac arrhythmia after TAAA repair was associated with prolonged hospital stay, higher early mortality, and lower midterm survival.

The seven attributes of the academic surgeon: Critical aspects of the archetype and contributions to the surgical community

BACKGROUND

"Academic surgeon" describes a member of a medical school department of surgery, but this term does not fully define the important role of such physician-scientists in advancing surgical science through translational research and innovation.

METHODS

The curriculum vitae and self-descriptive vignettes of the records of achievement of seven surgeons possessing documented records of academic leadership, innovation, and dissemination of knowledge were reviewed.

RESULTS

Out analysis yielded seven attributes of the archetypal academic surgeon: 1) identifies complex clinical problems ignored or thought unsolvable by others, 2) becomes an expert, 3) innovates to advance treatment, 4) observes outcomes to further improve and innovate, 5) disseminates knowledge and expertise, 6) asks important questions to further improve care, and 7) trains the next generation of surgeons and scientists.

CONCLUSION

Although alternative pathways to innovation and academic contribution also exist, the academic surgeon typically devotes years of careful observation, analysis, and iterative investigation to identify and solve challenging or unexplored clinical problems, ideally leverages resources available in academic medical centers to support these endeavors.

NLRP3 (Nucleotide Oligomerization Domain-Like Receptor Family, Pyrin Domain Containing 3)-Caspase-1 Inflammasome Degrades Contractile Proteins: Implications for Aortic Biomechanical Dysfunction and Aneurysm and Dissection Formation

OBJECTIVE

Increasing evidence suggests that contractile dysfunction in smooth muscle cells (SMCs) plays a critical role in aortic biomechanical dysfunction and aortic aneurysm and dissection (AAD) development. However, the mechanisms underlying SMC contractile dysfunction in sporadic AAD are poorly understood. In this study, we examined the role of the NLRP3 (nucleotide oligomerization domain-like receptor family, pyrin domain containing 3)-caspase-1 inflammasome, a key inflammatory cascade, in SMC contractile dysfunction in AAD.

APPROACH AND RESULTS

We observed significant SMC contractile protein degradation in aortas from patients with sporadic thoracic AAD. The contractile protein degradation was associated with activation of the NLRP3-caspase-1 inflammasome cascade. In SMCs, caspase-1 bound and directly cleaved and degraded contractile proteins, leading to contractile dysfunction. Furthermore, Nlrp3 or caspase-1 deficiency in mice significantly reduced angiotensin II-induced contractile protein degradation, biomechanical dysfunction, and AAD formation in both thoracic and abdominal aortas. Finally, blocking this cascade with the inflammasome inhibitor, glyburide (an antidiabetic medication), reduced angiotensin II-induced AAD formation.

CONCLUSIONS

Inflammasome-caspase-1-mediated degradation of SMC contractile proteins may contribute to aortic biomechanical dysfunction and AAD development. This cascade may be a therapeutic target in AAD formation. In addition, glyburide may have protective effects against AAD development.