Speckle-tracking echocardiography combined with imaging mass spectrometry assesses region-dependent alterations

Abstract

Left ventricular (LV) contraction is characterized by shortening and thickening of longitudinal and circumferential fibres. To date, it is poorly understood how LV deformation is altered in the pathogenesis of streptozotocin (STZ)-induced type 1 diabetes mellitus-associated diabetic cardiomyopathy and how this is associated with changes in cardiac structural composition. To gain further insights in these LV alterations, eight-week-old C57BL6/j mice were intraperitoneally injected with 50 mg/kg body weight STZ during 5 consecutive days. Six, 9, and 12 weeks (w) post injections, echocardiographic analysis was performed using a Vevo 3100 device coupled to a 30-MHz linearfrequency transducer. Speckle-tracking echocardiography (STE) demonstrated impaired global longitudinal peak strain (GLS) in STZ versus control mice at all time points. 9w STZ animals displayed an impaired global circumferential peak strain (GCS) versus 6w and 12w STZ mice. They further exhibited decreased myocardial deformation behaviour of the anterior and posterior base versus controls, which was paralleled with an elevated collagen I/III protein ratio. Additionally, hypothesis-free proteome analysis by imaging mass spectrometry (IMS) identified regional-and time-dependent changes of proteins affecting sarcomere mechanics between STZ and control mice. In conclusion, STZ-induced diabetic cardiomyopathy changes global cardiac deformation associated with alterations in cardiac sarcomere proteins. Diabetic cardiomyopathy is an own clinical entity, which occurs in the absence of hypertension and coronary artery disease 1,2. Experimental STZ-induced type 1 diabetes mellitus-associated diabetic cardiomyopathy is associated with enhanced cardiac cytokine levels and collagen I deposition, resulting in cardiac dysfunction 3. Cumulative evidence shows that early diabetic cardiomyopathy manifests in LV diastolic dysfunction accompanied by low-grade inflammation lacking pronounced fibrosis 4. Imaging techniques, like echocardiography 5 facilitate detection of alterations in diastolic performance. In general, LV architecture is composed of longitudinal and circumferential fibres, building the endo-, meso-, and epicardial layers of the heart 6. The orientation of the fibres within those layers is comprised of a right-handed helix in the subendocardium, circumferential oriented fibres in the cardiac midwall, and a left-handed helix in the subepicardium 7. During cardiac contraction, fibres undergo shortening and thickening, whereby contraction of the subendocardial longitudinal fibres mainly determine LV function in longitudinal direction 8. In contrast,

MALDI‐IMS as a Tool to Determine the Myocardial Response to Syndecan‐2‐Selected Mesenchymal Stromal Cell Application in an Experimental Model of Diabetic Cardiomyopathy

“…[ 5,11,17 ] Indeed, we recently demonstrated via MALDI‐IMS that STZ‐induced type 1 diabetic cardiomyopathy is associated with regional‐dependent changes in intensity distribution of α‐actin, myosin light chain 3, and titin, which are all associated with the contractile function of the heart. [ 11 ] In the present study, we detected changes of proteins associated with contractile function (α‐actin, myosin‐6/7, and titin) and cardiac energy metabolism (mitochondrial ATP synthase) in db/db mice compared to db+/db animals. These data agree with previous reports investigating the cardiac proteome in experimental type 1 [ 21 ] and type 2 [ 22 ] diabetes mellitus, which therefore highlights the particular relevance of these signaling pathways in the pathogenesis of diabetic cardiomyopathy.…”

“…Subsequent bottom-up LC-MS was used to identify spatial protein signatures and to assess the therapeutic response to syndecan-2/CD362 + -selected MSC. The LV architecture is composed of differently orientated fibers, building the endo-, meso-, and epicardium; [11,31] extraction of these specific regions via tissue microdissection is still challenging. The process is labor intensive and yields little knowledge about the actual spatial distribution of pathophysiological regions.…”

“…[3][4][5][6] Accumulating evidence shows that even in the absence of prominent cardiac fibrosis, diastolic LV function can be impaired due to changes in cardiac sarcomere proteins. [5,11,17] Indeed, we recently demonstrated via MALDI-IMS that STZ-induced type 1 diabetic cardiomyopathy is associated with regional-dependent changes in intensity distribution of -actin, myosin light chain 3, and titin, which are all associated with the contractile function of the heart. [11] In the present study, we detected changes of proteins associated with contractile function ( -actin, myosin-6/7, and titin) and cardiac energy metabolism (mitochondrial ATP synthase) in db/db mice compared to db+/db animals.…”

“…[9,10] Our own previous data on streptozotocin (STZ)-induced type 1 diabetes mellitus-associated diabetic cardiomyopathy demonstrated that MALDI-IMS, in combination with speckle-tracking echocardiography, is able to assess region-dependent alterations in protein distribution and the associated impairment of global and regional LV deformation. [11] Along with the differentiation and classification of pathophysiological regions, [12] studies in patients revealed the capability of IMS to stratify patients [13] and to characterize the therapeutic response. [14,15] Recent studies on early stage diabetic cardiomyopathy showed that dysfunctionality of the contractile apparatus, [16] including myosin and titin, [5,17] is sufficient to induce diastolic dysfunction without any involvement of cardiac fibrosis.…”

Proteomics in Kidney and Cardiovascular Clinical Research

“…IMS was successfully applied to characterize atrial fibrillation subtypes or in context of echocardiography to determine spatial diabetic cardiomyopathy changes in heart. [27] Pappritz et al [28] investigated myocardial response on a cell application in an experimental model of diabetic by using IMS. Mohamed et.al characterized molecular alteration in aneurysmal aortic tissue specimens.…”