Degenerative aortic valve disease and diabetes: Implications for a link between proteoglycans and diabetic disorders in the aortic valve

Molecular cues for immune cells from small leucine-rich repeat proteoglycans in their extracellular matrix-associated and free forms

In this review we highlight emerging immune regulatory functions of lumican, keratocan, fibromodulin, biglycan and decorin, which are members of the small leucine-rich proteoglycans (SLRP) of the extracellular matrix (ECM). These SLRPs have been studied extensively as collagen-fibril regulatory structural components of the skin, cornea, bone and cartilage in homeostasis. However, SLRPs released from a remodeling ECM, or synthesized by activated fibroblasts and immune cells contribute to an ECM-free pool in tissues and circulation, that may have a significant, but poorly understood foot print in inflammation and disease. Their molecular interactions and the signaling networks they influence also require investigations. Here we present studies on the leucine-rich repeat (LRR) motifs of SLRP core proteins, their evolutionary and functional relationships with other LRR pathogen recognition receptors, such as the toll-like receptors (TLRs) to bring some molecular clarity in the immune regulatory functions of SLRPs. We discuss molecular interactions of fragments and intact SLRPs, and how some of these interactions are likely modulated by glycosaminoglycan side chains. We integrate findings on molecular interactions of these SLRPs together with what is known about their presence in circulation and lymph nodes (LN), which are important sites of immune cell regulation. Recent bulk and single cell RNA sequencing studies have identified subsets of stromal reticular cells that express these SLRPs within LNs. An understanding of the cellular source, molecular interactions and signaling consequences will lead to a fundamental understanding of how SLRPs modulate immune responses, and to therapeutic tools based on these SLRPs in the future.

Interactive contribution of hyperinsulinemia, hyperglycemia, and mammalian target of rapamycin signaling to valvular interstitial cell differentiation and matrix remodeling

Diabetes and its major key determinants insulin resistance and hyperglycemia are known risk factors for calcific aortic valve disease (CAVD). The processes leading to molecular and structural alterations of the aortic valve are yet not fully understood. In previous studies, we could show that valvular interstitial cells (VIC) display canonical elements of classical insulin signaling and develop insulin resistance upon hyperinsulinemia and hyperglycemia accompanied by impaired glucose metabolism. Analyses of cultured VIC and aortic valve tissue revealed extracellular matrix remodeling and degenerative processes. Since PI3K signaling through mammalian target of rapamycin (mTOR) is involved in fibrotic processes of the heart, we aim at further functional investigation of this particular Akt-downstream signaling pathway in the context of diabetes-induced CAVD. Primary cultures of VIC were treated with hyperinsulinemia and hyperglycemia. Phosphorylation of mTOR(Ser²⁴⁴⁸) was determined by Western blot analysis after acute insulin stimulus. Inhibition of mTOR phosphorylation was performed by rapamycin. Phosphorylation of mTOR complex 1 (MTORC1) downstream substrates 4E-BP1(Thr^37/46) and P70S6K(Thr³⁸⁹), and MTORC2 downstream substrate Akt(Ser⁴⁷³) as well as the PDK1-dependent phosphorylation of Akt(Thr³⁰⁸) was investigated. Markers for extracellular matrix remodeling, cell differentiation and degenerative changes were analyzed by Western blot analysis, semi-quantitative real-time PCR and colorimetric assays. Hyperinsulinemia and hyperglycemia lead to alterations of VIC activation, differentiation and matrix remodeling as well as to an abrogation of mTOR phosphorylation. Inhibition of mTOR signaling by rapamycin leads to a general downregulation of matrix molecules, but to an upregulation of α-smooth muscle actin expression and alkaline phosphatase activity. Comparison of expression patterns upon diabetic conditions and rapamycin treatment reveal a possible regulation of particular matrix components and key degeneration markers by MTORC1 downstream signaling. The present findings broaden the understanding of mitogenic signaling pathways in VIC triggered by hyperinsulinemia and hyperglycemia, supporting the quest for developing strategies of prevention and tailored treatment of CAVD in diabetic patients.

Proteoglycans in Toll-like receptor responses and innate immunity

The extracellular matrix (ECM) is an active and dynamic feature of tissues that not only provides gross structure but also plays key roles in cellular responses. The ever-changing microenvironment responds dynamically to cellular and external signals, and in turn influences cell fate, tissue development, and response to environmental injury or microbial invasion. It is therefore paramount to understand how the ECM components interact with each other, the environment and cells, and how they mediate their effects. Among the ECM components that have recently garnered increased attention, proteoglycans (PGs) deserve special note. Recent evidence strongly suggests that they play a crucial role both in health maintenance and disease development. In particular, proteoglycans dictate whether homeostasis or cell death will result from a given injury, by triggering and modulating activation of the innate immune system, via a conserved array of receptors that recognize exogenous (infectious) or endogenous (tissue damage) molecular patterns. Innate immune activation by proteoglycans has important implications for the understanding of cell-matrix interactions in health and disease. In this review, we will summarize the current state of knowledge of innate immune signaling by proteoglycans, discuss the implications, and explore future directions to define progress in this area of extracellular matrix biology.

The role of biglycan in the healthy and thoracic aneurysmal aorta

The class I small leucine-rich proteoglycan biglycan is a crucial structural extracellular matrix component that interacts with a wide range of extracellular matrix molecules. In addition, biglycan is involved in sequestering growth factors such as TGF-β and BMPs and thereby regulating pathway activity. Biglycan consists of a 42-kDa core protein linked to two glycosaminoglycan side chains and both are involved in protein interactions. Biglycan is encoded by the BGN gene located on the X-chromosome and is expressed in various tissues, including vascular tissue, skin, brain, kidney lung, the immune system and the musculoskeletal system. Although an increasing amount of data on the biological function of biglycan in the vasculature has been produced, its role in thoracic aortic aneurysms is still not fully elucidated. This review focusses on the role of biglycan in the healthy thoracic aorta and the development of thoracic aortic aneurysm and dissections in both mice and humans.

Diabetes Is Associated With Rapid Progression of Aortic Stenosis: A Single-Center Retrospective Cohort Study

Background

Mounting evidence indicates that rapid progression of aortic stenosis (AS) is significantly associated with poor prognosis. Whether diabetes accelerates the progression of AS remains controversial.

Objectives

The purpose of the present study was to investigate whether diabetes was associated with rapid progression of AS.

Methods

We retrospectively analyzed 276 AS patients who underwent transthoracic echocardiography at least twice with a maximum interval ≥ 180 days from January 2016 to June 2021. AS severity was defined by specific threshold values for peak aortic jet velocity (V_max) and/or mean pressure gradient. An increase of V_max ≥ 0.3 m/s/year was defined as rapid progression. The binary Logistic regression models were used to determine the association between diabetes and rapid progression of AS.

Results

At a median echocardiographic follow-up interval of 614 days, the annual increase of V_max was 0.16 (0.00–0.41) m/s. Compared with those without rapid progression, patients with rapid progression were older and more likely to have diabetes (P = 0.040 and P = 0.010, respectively). In the univariate binary Logistic regression analysis, diabetes was associated with rapid progression of AS (OR = 2.02, P = 0.011). This association remained significant in the multivariate analysis based on model 2 and model 3 (OR = 1.93, P = 0.018; OR = 1.93, P = 0.022). After propensity score-matching according to V_max, diabetes was also associated rapid progression of AS (OR = 2.57, P = 0.045).

Conclusions

Diabetes was strongly and independently associated with rapid progression of AS.

Additive effect of aortic regurgitation degree on left ventricular strain in patients with type 2 diabetes mellitus evaluated via cardiac magnetic resonance tissue tracking

Background

Type 2 diabetes mellitus causes left ventricular (LV) remodeling and increases the risk of aortic regurgitation (AR), which causes further heart damage. This study aimed to investigate whether AR aggravates LV deformation dysfunction and to identify independent factors affecting the global peak strain (PS) of LV remodeling in patients with type 2 diabetes mellitus (T2DM) who presented with AR and those without T2DM.

Methods

In total, 215 patients with T2DM and 83 age- and sex-matched healthy controls who underwent cardiac magnetic resonance examination were included. Based on the echocardiogram findings, T2DM patients with AR were divided into three groups (mild AR [n = 28], moderate AR [n = 21], and severe AR [n = 17]). LV function and global strain parameters were compared, and multivariate analysis was performed to identify the independent indicators of LV PS.

Results

The T2DM patients with AR had a lower LV global PS, peak systolic strain rate (PSSR), and peak diastolic strain rate (PDSR) in three directions than those without AR and non-T2DM controls. Patients without AR had a lower PS (radial and longitudinal) and PDSR in three directions and higher PSSR (radial and longitudinal) than healthy controls. Further, regurgitation degree was an independent factor of LV global radial, circumferential, and longitudinal PS.

Conclusion

AR may aggravate LV stiffness in patients with T2DM, resulting in lower LV strain and function. Regurgitation degree and sex were independently correlated with LV global PS in patients with T2DM and AR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01471-2.

Degenerative changes of the aortic valve during left ventricular assist device support

AIMS

Donor heart shortage leads to increasing use of left ventricular assist device (LVAD) as bridge-to-transplant or destination therapy. Prolonged LVAD support is associated with aortic valve insufficiency, representing a relevant clinical problem in LVAD patients. Nevertheless, the impact of LVAD support on inflammation, remodelling, and chondro-osteogenic differentiation of the aortic valve is still not clearly understood. The aim of the study is to evaluate the impact of LVAD support on structural and molecular alterations of the aortic valve.

METHODS AND RESULTS

During heart transplantation, aortic valves of 63 heart failure patients without (n = 22) and with LVAD support (n = 41) were collected and used for analysis. Data on clinical course as well as echocardiographic data were analysed. Calcification and markers of remodelling, chondro-osteogenic differentiation, and inflammation were evaluated by computed tomography, by mRNA analysis and by histology and immunohistochemistry. Expression of inflammation markers of the LVAD group was analysed with regard to levels of C-reactive protein and driveline infections. Calcium accumulation and mRNA expression of determined markers were correlated with duration of LVAD support. Data were also analysed relating to aortic valve opening and aortic valve insufficiency. There was no difference in the frequency of cardiovascular risk factors or comorbidities between the patient groups. Expression of matrix metalloproteinase-9 (P = 0.007), alpha-smooth muscle actin (P = 0.045), and osteopontin (P = 0.003) were up-regulated in aortic valves of LVAD patients. Histological appearance of the aortic valve was similar in patients with or without LVAD, and computed tomography-based analysis not yet revealed significant difference in tissue calcification. Expression of interferon gamma (P = 0.004), interleukin-1 beta (P < 0.0001), and tumour necrosis factor alpha (P = 0.04) was up-regulated in aortic valves of LVAD patients without concomitant inflammatory cell infiltration and independent from unspecific inflammation. Expression of matrix metalloproteinase-2 (P = 0.038) and transforming growth factor beta (P = 0.0504) correlated negatively with duration of LVAD support. Presence of aortic valve insufficiency led to a significantly higher expression of interferon gamma (P = 0.007) in LVAD patients. There was no alteration in the determined markers in relation to aortic valve opening in LVAD patients.

CONCLUSIONS

Left ventricular assist device support leads to signs of early aortic valve degeneration independent of support duration. Thus, the aortic valve of patients with LVAD support should be closely monitored, particularly in patients receiving destination therapy as well as in the prospect of using aortic valves of LVAD patients as homografts in case of bridge-to-transplant therapy.

Proteoglycans and Diseases of Soft Tissues

Proteoglycans consist of protein cores to which at least one glycosaminoglycan chain is attached. They play important roles in the physiology and biomechanical function of tendons, ligaments, cardiovascular system, and other systems through their involvement in regulation of assembly and maintenance of extracellular matrix, and through their participation in cell proliferation together with growth factors. They can be divided into two main groups, small and large proteoglycans. The small proteoglycans are also known as small leucine-rich proteoglycans (SLRPs) which are encoded by 18 genes and are further subclassified into Classes I-V. Several members of Class I and II, such as decorin and biglycan from Class I, and Class II fibromodulin and lumican, are known to regulate collagen fibrillogenesis. Decorin limits the diameter of collagen fibrils during fibrillogenesis. The function of biglycan in fibrillogenesis is similar to that of decorin. Though biomechanical function of tendon is compromised in decorin-deficient mice, decorin can substitute for lack of biglycan in biglycan-deficient mice. New data also indicate an important role for biglycan in disorders of the cardiovascular system, including aortic valve stenosis and aortic dissection. Two members of the Class II of SLRPs, fibromodulin and lumican bind to the same site within the collagen molecule and can substitute for each other in fibromodulin- or lumican-deficient mice.Aggrecan and versican are the major representatives of the large proteoglycans. Though they are mainly found in the cartilage where they provide resilience and toughness, they are present also in tensile portions of tendons and, in slightly different biochemical form in fibrocartilage. Degradation by aggrecanase is responsible for the appearance of different forms of aggrecan and versican in different parts of the tendon where these cleaved forms play different roles. In addition, they are important components of the ventricularis of cardiac valves. Mutations in the gene for versican or in the gene for elastin (which binds to versican ) lead to severe disruptions of normal developmental of the heart at least in mice.

Aortic valve disease in diabetes: Molecular mechanisms and novel therapies

Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non‐diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic‐hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes‐induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD.

Crosstalk of Diabetic Conditions with Static Versus Dynamic Flow Environment-Impact on Aortic Valve Remodeling

Type 2 diabetes mellitus (T2D) is one of the prominent risk factors for the development and progression of calcific aortic valve disease. Nevertheless, little is known about molecular mechanisms of how T2D affects aortic valve (AV) remodeling. In this study, the influence of hyperinsulinemia and hyperglycemia on degenerative processes in valvular tissue is analyzed in intact AV exposed to an either static or dynamic 3D environment, respectively. The complex native dynamic environment of AV is simulated using a software-governed bioreactor system with controlled pulsatile flow. Dynamic cultivation resulted in significantly stronger fibrosis in AV tissue compared to static cultivation, while hyperinsulinemia and hyperglycemia had no impact on fibrosis. The expression of key differentiation markers and proteoglycans were altered by diabetic conditions in an environment-dependent manner. Furthermore, hyperinsulinemia and hyperglycemia affect insulin-signaling pathways. Western blot analysis showed increased phosphorylation level of protein kinase B (AKT) after acute insulin stimulation, which was lost in AV under hyperinsulinemia, indicating acquired insulin resistance of the AV tissue in response to elevated insulin levels. These data underline a complex interplay of diabetic conditions on one hand and biomechanical 3D environment on the other hand that possesses an impact on AV tissue remodeling.

Biglycan: an emerging small leucine-rich proteoglycan (SLRP) marker and its clinicopathological significance

Extracellular matrix (ECM) plays an important role in the structural organization of tissue and delivery of external cues to the cell. Biglycan, a class I small leucine-rich proteoglycans (SLRP), is a key component of the ECM that participates in scaffolding the collagen fibrils and mediates cell signaling. Dysregulation of biglycan expression can result in wide range of clinical conditions such as metabolic disorder, inflammatory disorder, musculoskeletal defects and malignancies. In this review, we aim to update our current understanding regarding the link between altered expression of biglycan and different clinicopathological states. Biglycan interacts with toll like receptors (TLR)-2 and TLR-4 on the immune cells which initiates inflammation and aggravates inflammatory disorders. ECM unbound soluble biglycan acts as a DAMP (danger associated molecular pattern) resulting in sterile inflammation. Dysregulation of biglycan expression is also observed in inflammatory metabolic conditions such as atherosclerosis and obesity. In cancer, high-biglycan expression facilitates tumor growth, invasion and metastasis which is associated with poor clinical outcome. As a pivotal structural component of the ECM, biglycan strengthens the musculoskeletal system and its absence is associated with musculoskeletal defects. Thus, SLRP biglycan is a potential marker which is significantly altered in different clinicopathological states.

Extracellular Matrix in Calcific Aortic Valve Disease: Architecture, Dynamic and Perspectives

Calcific Aortic Valve Disease (CAVD) is the most common valvular heart disease in developed countries and in the ageing population. It is strongly correlated to median age, affecting up to 13% of the population over the age of 65. Pathophysiological analysis indicates CAVD as a result of an active and degenerative disease, starting with sclerosis and chronic inflammation and then leaflet calcification, which ultimately can account for aortic stenosis. Although CAVD has been firstly recognized as a passive event mostly resulting from a degenerative aging process, much evidences suggests that calcification arises from different active processes, involving both aortic valve-resident cells (valve endothelial cells, valve interstitial cells, mesenchymal stem cells, innate immunity cells) and circulating cells (circulating mesenchymal cells, immunity cells). Moreover, a role for the cell-derived "matrix vesicles" and extracellular matrix (ECM) components has also been recognized. The aim of this work is to review the cellular and molecular alterations occurring in aortic valve during CAVD pathogenesis, focusing on the role of ECM in the natural course of the disease.

Diabetes mellitus is associated with liver metastasis of colorectal cancer through production of biglycan-rich cancer stroma

High morbidity and mortality of cancer, especially colorectal cancer (CRC), in diabetic patients have been reported. In this study, we investigated the relationship between the presence of diabetes mellitus (blood hemoglobin A1C was 6.5% or higher at the time of diagnosis of CRC) and the progression and liver metastasis of CRC. Histopathological findings in the primary lesions, which were preferential to diabetes-complicated CRC (DM-CRC) and the liver metastasis, were also investigated. Of the 473 CRC patients who underwent curative surgical resection, 148 (31%) had diabetes. In DM-CRC cases, the stage was more advanced, with more cases in stage IV or postoperative disease recurrence. Histopathological findings correlated with liver metastasis in DM-CRC, including budding grade, perineural invasion, and myxomatous tumor stroma, and all were highly correlated with the stage. Additionally, myxomatous stroma showed the strongest correlation with liver metastasis in multivariate analysis. Myxomatous stroma in stage III cases correlated with liver recurrence. The myxomatous stroma was abundant in biglycan protein and contained numerous CD90-positive mesenchymal stem cells (MSCs). In human colon cancer cell line HT29, biglycan expression was induced by high sugar concentration, fatty acids, and insulin, and its contact co-culture with MSCs resulted in enhanced stemness and epithelial-mesenchymal transition phenotype. Thus, DM-CRC has higher malignant phenotypes compared to non-DM-CRC, and the involvement of diabetes-induced biglycan may act as a pathogenic factor.

Nano-Polyplexes Mediated Transfection of Runx2-shRNA Mitigates the Osteodifferentiation of Human Valvular Interstitial Cells

Calcific aortic valve disease (CAVD) is a progressive disorder that increases in prevalence with age. An important role in aortic valve calcification is played by valvular interstitial cells (VIC), that with age or in pathological conditions acquire an osteoblast-like phenotype that advances the disease. Therefore, pharmacological interventions aiming to stop or reverse the osteoblastic transition of VIC may represent a therapeutic option for CAVD. In this study, we aimed at developing a nanotherapeutic strategy able to prevent the phenotypic switch of human aortic VIC into osteoblast-like cells. We hypothesize that nanocarriers designed for silencing the Runt-related transcription factor 2 (Runx2) will stop the progress or reverse the osteodifferentiation of human VIC, induced by high glucose concentrations and pro-osteogenic factors. We report here the potential of fullerene (C60)-polyethyleneimine (PEI)/short hairpin (sh)RNA-Runx2 nano-polyplexes to efficiently down-regulate Runx2 mRNA and protein expression leading subsequently to a significant reduction in the expression of osteogenic proteins (i.e. ALP, BSP, OSP and BMP4) in osteoblast-committed VIC. The data suggest that the silencing of Runx2 could represent a novel strategy to impede the osteoblastic phenotypic shift of VIC and the ensuing progress of CAVD.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

Diabetes-induced early molecular and functional changes in aortic heart valves in a murine model of atherosclerosis

Diabetes contributes directly to the development of cardiovascular aortic valve disease. There is currently no drug therapy available for a dysfunctional valve and this urges the need for additional research to identify distinctive mechanisms of cardiovascular aortic valve disease evolution. The aim of this study was to evaluate changes of valvular aortic lesions induced in a hyperlipemic ApoE^-/- mouse model by early type 1 diabetes onset (at 4 and 7 days after streptozotocin induction). The haemodynamic valve parameters were evaluated by echography and blood samples and aortic valves were collected. Plasma parameters were measured, and inflammatory, remodelling and osteogenic markers were evaluated in the aortic valves. Next, correlations between all parameters were determined. The results showed early aortic valve dysfunction detected by echography after 1 week of diabetes; lesions were found in the aortic root. Moreover, increased expression of cell adhesion molecules, extracellular matrix remodelling and osteogenic markers were detected in hyperlipemic ApoE^-/- diabetic mice. Significant correlations were found between tissue valve biomarkers and plasmatic and haemodynamic parameters. Our study may help to understand the mechanisms of aortic valve disease in the diabetic milieu in order to discover and validate new biomarkers of cardiovascular aortic valve disease in diabetes and reveal new possible targets for nanobiotherapies.

Preoperative Anemia and Postoperative Mortality in Patients with Aortic Stenosis Treated with Transcatheter Aortic Valve Implantation (TAVI): A Systematic Review and Meta-Analysis

BACKGROUND Patients with severe aortic stenosis who have comorbidities that prevent general anesthesia and open cardiothoracic surgery are candidates for transcatheter aortic valve implantation (TAVI). However, TAVI can result in patient mortality following the procedure. This systematic review of the literature and meta-analysis aimed to determine the relationship between preoperative anemia and postoperative mortality in patients following TAVI. MATERIAL AND METHODS PubMed, EMBASE, the Cochrane Library, and the Web of Science were systematically searched from their inception to February 2019 for relevant published studies that included patients with bicuspid aortic valve stenosis and tricuspid aortic valve stenosis who underwent TAVI and who had preoperative data on hemoglobin levels. The pooled odds ratios (OR) and 95% confidence interval (CI) were calculated using a random-effects generic inverse variance method. RESULTS Six published studies that involved 6,406 patients with aortic stenosis were included in the meta-analysis. There was no significant difference observed for the final pooled result for patients with and without anemia for the short-term 30-day postoperative mortality (OR, 1.34; 95% CI, 0.77-2.35). However, long-term mortality rates were significantly worse in patients with preoperative anemia compared with those without anemia (OR, 1.77; 95% CI, 1.34-2.35). CONCLUSIONS Systematic review of the literature and meta-analysis showed that pre-procedural anemia reduced long-term mortality following TAVI. This finding supports the need to correct preoperative anemia in patients with aortic stenosis to improve patient outcome following TAVI.

Impact of hyperinsulinemia and hyperglycemia on valvular interstitial cells - A link between aortic heart valve degeneration and type 2 diabetes

Type 2 diabetes is a known risk factor for cardiovascular diseases and is associated with an increased risk to develop aortic heart valve degeneration. Nevertheless, molecular mechanisms leading to the pathogenesis of valve degeneration in the context of diabetes are still not clear. Hence, we hypothesized that classical key factors of type 2 diabetes, hyperinsulinemia and hyperglycemia, may affect signaling, metabolism and degenerative processes of valvular interstitial cells (VIC), the main cell type of heart valves. Therefore, VIC were derived from sheep and were treated with hyperinsulinemia, hyperglycemia and the combination of both. The presence of insulin receptors was shown and insulin led to increased proliferation of the cells, whereas hyperglycemia alone showed no effect. Disturbed insulin response was shown by impaired insulin signaling, i.e. by decreased phosphorylation of Akt/GSK-3α/β pathway. Analysis of glucose transporter expression revealed absence of glucose transporter 4 with glucose transporter 1 being the predominantly expressed transporter. Glucose uptake was not impaired by disturbed insulin response, but was increased by hyperinsulinemia and was decreased by hyperglycemia. Analyses of glycolysis and mitochondrial respiration revealed that VIC react with increased activity to hyperinsulinemia or hyperglycemia, but not to the combination of both. VIC do not show morphological changes and do not acquire an osteogenic phenotype by hyperinsulinemia or hyperglycemia. However, the treatment leads to increased collagen type 1 and decreased α-smooth muscle actin expression. This work implicates a possible role of diabetes in early phases of the degeneration of aortic heart valves.