Sex-dependent aortic valve pathology in patients with rheumatic heart disease

The role of monocytes in thrombotic diseases: a review

Cardiovascular and cerebrovascular diseases are the number one killer threatening people's life and health, among which cardiovascular thrombotic events are the most common. As the cause of particularly serious cardiovascular events, thrombosis can trigger fatal crises such as acute coronary syndrome (myocardial infarction and unstable angina), cerebral infarction and so on. Circulating monocytes are an important part of innate immunity. Their main physiological functions are phagocytosis, removal of injured and senescent cells and their debris, and development into macrophages and dendritic cells. At the same time, they also participate in the pathophysiological processes of pro-coagulation and anticoagulation. According to recent studies, monocytes have been found to play a significant role in thrombosis and thrombotic diseases of the immune system. In this manuscript, we review the relationship between monocyte subsets and cardiovascular thrombotic events and analyze the role of monocytes in arterial thrombosis and their involvement in intravenous thrombolysis. Finally, we summarize the mechanism and therapeutic regimen of monocyte and thrombosis in hypertension, antiphospholipid syndrome, atherosclerosis, rheumatic heart disease, lower extremity deep venous thrombosis, and diabetic nephropathy.

Identification of TNFα-mediated inflammation as potential pathological marker and therapeutic target for calcification progress of congenital bicuspid aortic valve

BACKGROUD

Congenital bicuspid aortic valve (cBAV) develops calcification and stenotic obstruction early compared with degenerative tricuspid aortic valve (dTAV), which requires surgical intervention. Here we report a comparative study of patients with cBAV or dTAV to identify risk factors associated with the rapid development of calcified bicuspid valves.

METHODS

A total of 69 aortic valves (24 dTAV and 45 cBAV) were collected at the time of surgical aortic valve replacement for comparative clinical characteristics. Ten samples were randomly selected from each group for histology, pathology, and inflammatory factors expression and comparison analyses. OM-induced calcification in porcine aortic valve interstitial cell cultures were prepared for illustrating the underlying molecular mechanisms about calcification progress of cBAV and dTAV.

RESULTS

We found that cBAV patients have increased cases of aortic valve stenosis compared with dTAV patients. Histopathological examinations revealed increased collagens deposition, neovascularization and infiltrations by inflammatory cells, especially T-lymphocytes and macrophages. We identified that tumor necrosis factor α (TNFα) and its regulated inflammatory cytokines are upregulated in cBAV. Further in vitro study indicated that TNFα-NFκB and TNFα-GSK3β pathway accelerate aortic valve interstitial cells calcification, while inhibition of TNFα significantly delays this process.

CONCLUSION

The finding of intensified TNFα-mediated inflammation in the pathological cBAV advocates the inhibition of TNFα as a potential treatment for patients with cBAV by alleviating the progress of inflammation-induced valve damage and calcification.

A Rare Case of Congestive Heart Failure due to Isolated Aortic Valve Disease in a Middle-Aged Man Secondary to Rheumatic Fever

Rheumatic heart disease (RHD) is commonly seen in people from developing and low-income countries. More cases are being recorded in developed countries due to migration and globalization. RHD develops in people with a history of rheumatic fever; it is an autoimmune response to group A streptococcal infection due to similarities at the molecular level. Congestive heart failure, arrhythmia, atrial fibrillation, stroke, and infective endocarditis are a few of the many complications associated with RHD. Here we present a case of a 48-year-old male with a past medical history of rheumatic fever at the age of 12 years, who presented to the emergency room (ER) complaining of bilateral ankle swelling, dyspnea on exertion, and palpitations. The patient was tachycardic with a heart rate of 146 beats per minute and tachypneic with a respiratory rate of 22 breaths per minute. On physical exam, there was a harsh systolic and diastolic murmur at the right upper sternal border. A 12-lead electrocardiogram (EKG) revealed atrial flutter with a variable block. Chest X-ray revealed an enlarged cardiac silhouette with a pro-brain natriuretic peptide (proBNP) of 2,772 pg/mL (normal ≤ 125 pg/mL). The patient was stabilized with metoprolol and furosemide and was admitted to the hospital for further investigation. Transthoracic echocardiogram showed left ventricular ejection fraction (LVEF) of 50-55% with severe concentric hypertrophy of the left ventricle with a severely dilated left atrium. Increased thickness of the aortic valve with severe stenosis and a peak gradient of 139 mm Hg and a mean gradient of 82 mm Hg was noted. The valve area was measured to be 0.8 cm². Transesophageal echocardiogram showed a tri-leaflet aortic valve with commissural fusion of valve cusps with severe leaflet thickening consistent with rheumatic valve disease. The patient underwent tissue aortic valve replacement with a bioprosthetic valve. The pathology report showed extensive fibrosis and calcification of the aortic valve. The patient came in for a follow-up visit 6 months later and expressed feeling better and more active.

Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1β and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1β and IL-18 are discussed in this review and may be promising for treating RHD patients.

Atypical Expression of Smooth Muscle Markers and Co-activators and Their Regulation in Rheumatic Aortic and Calcified Bicuspid Valves

Objective

We have previously reported that human calcified aortic cusps have abundant expression of smooth muscle (SM) markers and co-activators. We hypothesised that cells in bicuspid aortic valve (BAV) cusps and those affected by rheumatic heart valve (RHV) disease may follow a similar phenotypic transition into smooth muscle cells, a process that could be regulated by transforming growth factors (TGFs).

Aims

Cusps from eight patients with BAV and seven patients with RHV were analysed for early and late SM markers and regulators of SM gene expression by immunocytochemistry and compared to healthy aortic valves from 12 unused heart valve donors. The ability of TGFs to induce these markers in valve endothelial cells (VECs) on two substrates was assessed.

Results

In total, 7 out of 8 BAVs and all the RHVs showed an increased and atypical expression of early and late SM markers α-SMA, calponin, SM22 and SM-myosin. The SM marker co-activators were aberrantly expressed in six of the BAV and six of the RHV, in a similar regional pattern to the expression of SM markers. Additionally, regions of VECs, and endothelial cells lining the vessels within the cusps were found to be positive for SM markers and co-activators in three BAV and six RHV. Both BAVs and RHVs were significantly thickened and HIF1α expression was prominent in four BAVs and one RHV. The ability of TGFβs to induce the expression of SM markers and myocardin was greater in VECs cultured on fibronectin than on gelatin. Fibronectin was shown to be upregulated in BAVs and RHVs, within the cusps as well as in the basement membrane.

Conclusion

Bicuspid aortic valves and RHVs expressed increased numbers of SM marker-positive VICs and VECs. Concomittantly, these cells expressed MRTF-A and myocardin, key regulators of SM gene expression. TGFβ1 was able to preferentially upregulate SM markers and myocardin in VECs on fibronectin, and fibronectin was found to be upregulated in BAVs and RHVs. These findings suggest a role of VEC as a source of cells that express SM cell markers in BAVs and RHVs. The similarity between SM marker expression in BAVs and RHVs with our previous study with cusps from patients with aortic stenosis suggests the existance of a common pathological pathway between these different pathologies.

Sex-Differences in Aortic Stenosis: Mechanistic Insights and Clinical Implications

Objective

We aim to analyse sex-specific differences in aortic valves (AVs) and valve interstitial cells (VICs) from aortic stenosis (AS) patients.

Approach and Results

238 patients with severe AS undergoing surgical valve replacement were recruited. Two hundred and two AVs (39.1% women) were used for ex vivo analyses and 36 AVs (33.3% women) for in vitro experiments. AVs from men presented increased levels of the inflammatory molecules interleukin (IL)-1β, IL-6, Rantes, and CD45. Oxidative stress (eNOS, myeloperoxidase, malondialdehyde and nitrotyrosine) was upregulated in male AVs. Concerning fibrosis, similar levels of collagen type I, decreased levels of collagen type III and enhanced fibronectin, active Lox-1 and syndecan-1 expressions were found in AVs from men compared with women. Extracellular matrix (ECM) remodeling was characterized by reduced metalloproteinase-1 and 9 expression and increased tissue inhibitor of metalloproteinase-2 expression in male AVs. Importantly, osteogenic markers (bone morphogenetic protein-9, Rank-L, osteopontin, periostin, osteocalcin and Sox-9) and apoptosis (Bax, Caspase 3, p53, and PARP1) were enhanced in AVs from men as compared to women. Isolated male VICs presented higher myofibroblast-like phenotype than female VICs. Male VICs exhibited increased inflammatory, oxidative stress, fibrotic, apoptosis and osteogenic differentiation markers.

Conclusions

Our results suggest that the mechanisms driving the pathogenesis of AS could be different in men and women. Male AVs and isolated VICs presented more inflammation, oxidative stress, ECM remodeling and calcification as compared to those from women. A better knowledge of the pathophysiological pathways in AVs and VICs will allow the development of sex-specific options for the treatment of AS.

Matters of the heart: Cellular sex differences

Nearly all cardiovascular diseases show sexual dimorphisms in prevalence, presentation, and outcomes. Until recently, most clinical trials were carried out in males, and many animal studies either failed to identify the sex of the animals or combined data obtained from males and females. Cellular sex in the heart is relatively understudied and many studies fail to report the sex of the cells used for in vitro experiments. Moreover, in the small number of studies in which sex is reported, most of those studies use male cells. The observation that cells from males and females are inherently different is becoming increasingly clear - either due to acquired differences from hormones and other factors or due to intrinsic differences in genotype (XX or XY). Because of the likely contribution of cellular sex differences in cardiac health and disease, here, we explore differences in mammalian male and female cells in the heart, including the less-studied non-myocyte cell populations. We discuss how the heart's microenvironment impacts male and female cellular phenotypes and vice versa, including how secretory profiles are dependent on cellular sex, and how hormones contribute to sexually dimorphic phenotypes and cellular functions. Intracellular mechanisms that contribute to sex differences, including gene expression and epigenetic remodeling, are also described. Recent single-cell sequencing studies have revealed unexpected sex differences in the composition of cell types in the heart which we discuss. Finally, future recommendations for considering cellular sex differences in the design of bioengineered in vitro disease models of the heart are provided.

Sex and Race Differences in the Pathophysiology, Diagnosis, Treatment, and Outcomes of Valvular Heart Diseases

Valvular heart diseases have long been considered to be similar in men and women and across races/ethnicities. Recently, studies have demonstrated major differences between sexes. Unfortunately, studies on valvular heart diseases, as on other cardiovascular diseases, are mostly performed in Caucasian men or in cohorts with a vast majority of Caucasian men. Therefore, our knowledge on valvular diseases in women and non-Caucasians remains limited. Nevertheless, aortic stenosis has been shown to be almost as prevalent in women as in men, and less prevalent in African Americans. Men appear to have a more calcified aortic valve lesion, and women tend to have a more fibrosed one. Primary mitral regurgitation is more frequent in women who have more rheumatic and Barlow etiologies, whereas men have more fibroelastic deficiency and posterior leaflet prolapse/flail. Left ventricular remodelling due to valvular heart diseases is sex related in terms of geometry and probably also in composition of the tissue. Outcomes seem to be worse in women after surgical interventions and better than or equivalent to men after transcatheter ones. Regarding other valvular heart diseases, very few studies are available: Aortic regurgitation is more frequent in men, isolated tricuspid regurgitation more frequent in women. Rheumatic valve diseases are more frequent in women and are mostly represented by mitral and aortic stenoses. Many other sex/gender- and race/ethnic-specific studies are still needed in epidemiology, pathophysiology, presentation, management, and outcomes. This review aims to report the available data on sex differences and race specificities in valvular heart diseases, with a primary focus on aortic stenosis and mitral regurgitation.

Age, Sex, and Valve Phenotype Differences in Fibro-Calcific Remodeling of Calcified Aortic Valve

Background

In calcific aortic valve disease on tricuspid aortic valves (TAVs), men have higher aortic valve calcification and less fibrosis than women. However, little is known in bicuspid aortic valves (BAV). We thus aimed to investigate the impact of age, sex, and valve phenotype (TAVs versus BAVs) on fibro‐calcific remodeling in calcific aortic valve disease.

Methods and Results

We included 2 cohorts: 411 patients who underwent multidetector computed tomography (37% women) for aortic valve calcification density assessment and 138 explanted aortic valves (histological cohort; 50% women). The cohorts were divided in younger (<60 years old) or older patients with BAV (≥60 years old), and TAV patients. In each group, women and men were matched. Women presented less aortic valve calcification density than men in each group of the multidetector computed tomography cohort (all P≤0.01). Moreover, in women, younger patients with BAV had the lowest aortic valve calcification density (both P=0.02). In multivariate analysis, aortic valve calcification density correlated with age (β estimate±standard error: 6.5±1.8; P=0.0004) and male sex (109.2±18.4; P<0.0001), and there was a trend with TAVs (41.5±23.0; P=0.07). Women presented a higher collagen content than men (77.8±10.8 versus 69.9±12.9%; P<0.001) in the entire cohort. In women, younger patients with BAV had denser connective tissue than TAV and older patients with BAV (both P≤0.05), while no difference was observed between men.

Conclusions

In calcific aortic valve disease, women had less calcification and more fibrotic remodeling than men, regardless of the phenotype of the valve or age of the patient. Moreover, younger women with BAVs had less valve calcification. Thus, mineralization/fibrosis of the aortic valve is likely to have sex/age‐specific mechanisms and be influenced by the valve morphology.

Comparative Clinical Characteristics of Rheumatic Heart Disease Patients Undergoing Surgical Valve Replacement

Background

To assess the prevalence patterns of isolated/mixed rheumatic valvular lesions and associated risk factors among rheumatic heart disease (RHD) patients undergoing surgical valve replacement.

Methods

An analytical cross-sectional design was used. Purposive sampling was used to select 87 RHD patients who underwent a first-time valve replacement for mitral, aortic, or both valves between April 1 and October 20, 2016, at Punjab Institute of Cardiology, Lahore, Pakistan. Patients with systemic hypertension, diabetes mellitus type-II, congenital heart defects, coronary artery disease, non-rheumatic valvular degeneration, positive test for hepatitis C, or undergoing concomitant coronary artery bypass graft or a ‘redo’ valve replacement procedure were excluded.

A proforma was used to collect preoperative data on patients’ demographics, laboratory investigations, electrocardiogram (ECG), and transthoracic echocardiography reports.

Results

Age (mean ± S.D.) was 32.79 ± 13.06 years, which was divided into four quartile-based groups. Forty-six (52.9%) cases were males. The majority (56.3%) of patients underwent mitral valve replacement. Mitral regurgitation (MR, 80%) was the most common lesion. Of 71 available ECGs, atrial fibrillation was observed in 46.5% cases. Increasing age group was negatively correlated with MR severity (τ_c = -0.188, p-value = 0.033) and positively with aortic stenosis (AS) severity (τ_c = 0.141, p-value = 0.010).

No significant elevations were observed for anti-streptolysin O titer, C-reactive protein, and leukocyte count, though the erythrocyte sedimentation rate was abnormally high in 46.94% cases.

Conclusions

MR was the most common lesion. MR was more severe in younger patients whilst AS was more severe in older cases. There is little evidence of ongoing residual inflammation.