Myocardial Fibrosis In Dilated Cardiomyopathy Research Articles

HTRA1-driven detachment of type I collagen from endoplasmic reticulum contributes to myocardial fibrosis in dilated cardiomyopathy

BackgroundThe aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear.Methods and resultsRNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson’s analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM.ConclusionsThe findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

Early detection of myocardial fibrosis in cardiomyopathy in the absence of late enhancement: role of T1 mapping and extracellular volume analysis.

To analyze myocardial fibrosis in dilated cardiomyopathy (DCM) patients with no late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) using T1 mapping and extracellular volume (ECV) and investigate the potential correlation with left ventricular (LV) dilation and dysfunction. The study included 41 DCM patients without LGE and 79 healthy controls. T1 and ECV were compared between the two groups using multivariable logistic regression analysis. The correlations between histological and functional parameters were evaluated using Pearson's correlation. Mean native myocardial T1 and ECV were significantly higher in the DCM group compared to controls (p ≤ 0.001, respectively). Multivariable logistic regression revealed that ECV (mean, minimum), LV ejection fraction (LVEF), and LV end-diastolic diameter (LVEDD) were independent discriminators for LGE-negative DCM; the area under the curve (AUC) of LVEF, LVEDD, ECV mean, and ECV minimum were 0.97, 0.96, 0.88, and 0.68, respectively. In the DCM group, LVEDD and LVEF were positively and negatively correlated with ECV, respectively. LVEDV index and LV end-systolic volume (LVESV) index were positively correlated with native-T1 and ECV, and the absolute value of LV global strain had a negative correlation with ECV. Early myocardial fibrosis in DCM could be detected by prolonged native T1 and elevated ECV despite the absence of LGE on CMR. Moreover, the change of histological characteristics of myocardium in DCM was correlated with LV dilation and dysfunction. • At an early stage, patients with DCM may have myocardial fibrosis despite the absence of LGE. • T1 mapping and ECV are efficient methods for early detection of potential myocardial fibrosis. • Increased native T1 and ECV are correlated with left ventricular dilation and dysfunction in LGE-negative DCM patients.

Natural history of myocardial fibrosis in dilated cardiomyopathy

Abstract Background It is commonly accepted that myocardial fibrosis (MF) is implicated in the pathology of dilated cardiomyopathy (DCM). However, MF is not a “fixed” abnormality but evolves over time. It is unknown what the natural history of MF is in optimally treated DCM patients. Methods This is a prospective, single-center, observational study. Between May 2019 and September 2020, 90 DCM (81 male, mean age 47.2±9.8 years, mean EF 34.5±12.2%) patients underwent cardiac magnetic resonance (CMR). All patients were optimally treated with heart failure approved medications (beta-blockers in 100%, ACE-I/ARNI/ARB – 98%, MRA – 95%). Both, replacement via late gadolinium enhancement (LGE) and interstitial via T1 mapping MF were assessed. Replacement MF was expressed as LGE mass and LGE extent, whereas interstitial MF as extracellular volume (ECV). Left ventricular (LV) matrix and cell volumes were calculated based on LV mass and ECV as: LV matrix volume = (LV mass/1.05 g/mL) × ECV and LV cell volume = (LV mass/1.05 g/mL) × (1 − ECV). After 12 months CMR studies with MF assessment were repeated. Results Overall, index LV end-diastolic and end-systolic volumes (LVEDvol, LVESvol) and LV mass significantly decreased, whereas EF increased during follow-up (Table 1). Both, LGE mass (8.7±8.1 vs. 8.6±7.7 g; p=0.6) and LGE extent (4.6±4.2 vs. 4.97±4.6%; p=0.14) were similar between two measurements. There was a trend towards ECV decrease between baseline and follow-up studies but it did not reach statistical significance (28.5±4.9 vs. 27.7±4.1%; p=0.09). LV matrix volume significantly decreased during follow-up (49.1±17.8 vs. 46.1±15.7 ml; p<0.05); however LV cell volume remained unchanged (123.1±35.6 vs. 119.7±39.6 ml; p=0.2). Conclusions Beneficial regression of LV volumes and improvement of systolic function is common in DCM over mid-term period (one year). Replacement fibrosis seems to be a “fixed” pathology without much room for improvement. On the other hand, interstitial fibrosis seems to be a subject for substantial change. Left ventricular cells compartment does not change over time. Two types of MF – replacement and interstitial behaved differently during follow-up. Interstitial MF is amenable for treatment, whereas replacement MF does not respond to currently available therapy. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was founded through the National Science Centre, Poland (grant number 2018/29/B/NZ5/02588) and the Department of Scientific Research and Structural Funds of Medical College, Jagiellonian University (grant number K/ZDS/007192)

The combination of carboxy-terminal propeptide of procollagen type I blood levels and late gadolinium enhancement at cardiac magnetic resonance provides additional prognostic information in idiopathic dilated cardiomyopathy-A multilevel assessment of myocardial fibrosis in dilated cardiomyopathy.

AimsTo determine the prognostic value of multilevel assessment of fibrosis in dilated cardiomyopathy (DCM) patients.Methods and resultsWe quantified fibrosis in 209 DCM patients at three levels: (i) non‐invasive late gadolinium enhancement (LGE) at cardiac magnetic resonance (CMR); (ii) blood biomarkers [amino‐terminal propeptide of procollagen type III (PIIINP) and carboxy‐terminal propeptide of procollagen type I (PICP)], (iii) invasive endomyocardial biopsy (EMB) (collagen volume fraction, CVF). Both LGE and elevated blood PICP levels, but neither PIIINP nor CVF predicted a worse outcome defined as death, heart transplantation, heart failure hospitalization, or life‐threatening arrhythmias, after adjusting for known clinical predictors [adjusted hazard ratios: LGE 3.54, 95% confidence interval (CI) 1.90–6.60; P < 0.001 and PICP 1.02, 95% CI 1.01–1.03; P = 0.001]. The combination of LGE and PICP provided the highest prognostic benefit in prediction (likelihood ratio test P = 0.007) and reclassification (net reclassification index: 0.28, P = 0.02; and integrated discrimination improvement index: 0.139, P = 0.01) when added to the clinical prediction model. Moreover, patients with a combination of LGE and elevated PICP (LGE+/PICP+) had the worst prognosis (log‐rank P < 0.001). RNA‐sequencing and gene enrichment analysis of EMB showed an increased expression of pro‐fibrotic and pro‐inflammatory pathways in patients with high levels of fibrosis (LGE+/PICP+) compared to patients with low levels of fibrosis (LGE‐/PICP‐). This would suggest the validity of myocardial fibrosis detection by LGE and PICP, as the subsequent generated fibrotic risk profiles are associated with distinct cardiac transcriptomic profiles.ConclusionThe combination of myocardial fibrosis at CMR and circulating PICP levels provides additive prognostic value accompanied by a pro‐fibrotic and pro‐inflammatory transcriptomic profile in DCM patients with LGE and elevated PICP.

Native T1 Mapping and Extracellular Volume Mapping for the Assessment of Diffuse Myocardial Fibrosis in Dilated Cardiomyopathy

ObjectivesThe purpose of this study was to examine the histological correlation of native myocardial T1 and extracellular volume fraction (ECV) measurement at 3-T for the assessment of diffuse pathological changes in the myocardial tissue, including myocardial fibrosis and extracellular space in dilated cardiomyopathy (DCM). BackgroundCardiac magnetic resonance T1 techniques allow the quantification of diffuse myocardial fibrosis. However, there are no definitive head-to-head studies of native T1 versus ECV for the detection, quantification, and characterization of pathological changes in the myocardial tissue in DCM by using histological samples for confirmation. MethodsA total of 36 subjects with DCM (31 men, mean age 56 ± 16 years) underwent pre- and post-contrast T1 mapping as well as late gadolinium enhancement (LGE) cardiac magnetic resonance at 3-T. Biopsy samples were used for the quantification of collagen volume fraction using picrosirius red staining and an extracellular space component from hematoxylin and eosin–stained myocardium. ResultsNonischemic LGE was observed in 14 of 36 patients. Although patients with LGE had significantly greater biopsy-proven collagen volume fraction than those without LGE (21 ± 12% vs. 11 ± 8%; p < 0.01), there was substantial overlap of collagen volume fraction values between patients with and without LGE. Both native T1 value and ECV were similarly and significantly associated with biopsy-proven collagen volume fraction (r = 0.77 and r = 0.66, respectively; p < 0.05). Furthermore, ECV had a strong correlation with the biopsy-proven extracellular space component (r = 0.86), whereas native T1 had only a moderate correlation (r = 0.55). Interobserver and intraobserver reproducibility for native T1 and ECV were 0.89, 0.95, 0.96, and 0.98, respectively. ConclusionsNative T1 exhibited comparable ability as ECV measurement in the detection and quantification of histological collagen volume fraction, with high reproducibility, and therefore diffuse myocardial fibrosis in DCM may be reliably assessed by native T1 mapping without the administration of gadolinium contrast agent. In addition, cardiac magnetic resonance–derived ECV showed excellent agreement with histological extracellular space.

Fibrosis of extracellular matrix is related to the duration of the disease but is unrelated to the dynamics of collagen metabolism in dilated cardiomyopathy.

BackgroundFibrosis of extracellular matrix (ECM) in dilated cardiomyopathy (DCM) corresponds to the myocardial over-production of various types of collagens. However, mechanism of this process is poorly understood.ObjectiveTo investigate whether enhanced metabolism of ECM occur in DCM.MethodsSeventy consecutive DCM patients (pts) (48 ± 12.1 years, EF 24.4 ± 7.4 %) and 20 healthy volunteers were studied. Based on symptoms duration, pts were divided into new-onset (n = 35, 6 months) and chronic DCM (n = 35, >6 months). Markers of collagen type I and III synthesis-procollagen type I carboxy- and amino-terminal peptides (PICP and PINP) and procollagen type III carboxy- and amino-terminal peptides (PIIICP and PIIINP), collagen 1 (col-1), ECM metabolism controlling factors—tumor growth factor beta-1 (TGF1-β), connective tissue growth factor (CTGF), and ECM degradation enzymes—matrix metalloproteinases (MMP-2, MMP-9) and their tissue inhibitor (TIMP-1) were measured in serum. All pts underwent right ventricular endomyocardial biopsy to study ECM fibrosis.ResultsThe presence of fibrosis was detected in 24 (34.3 %) pts and was more prevalent in chronic DCM [17 (48.6 %) vs. 7 (20 %), p < 0.01]. The levels of PIIINP [4.41 (2.17–6.08) vs. 3.32 (1.69–5.02) ng/ml, p < 0.001], CTGF [3.82 (0.48–23.87) vs. 2.37 (0.51–25.32) ng/ml, p < 0.01], MMP-2 [6.06 (2.72–14.8) vs. 4.43 (2.27–7.4) ng/ml, p < 0.001], MMP-9 [1.98 (0.28–9.25) vs. 1.01 (0.29–3.59) ng/ml, p < 0.002)], and TIMP-1 [15.29 (1.8–36.17) vs. 2.61 (1.65–24.09) ng/ml, p < 0.004] were significantly higher in DCM, whereas levels of col-1 [57.7 (23.1–233.4) vs. 159.4 (31.2–512.9) pg/ml, p < 0.001] were significantly lower in DCM compared to controls. There were no differences in all measured serum markers of ECM metabolism between newonset and chronic DCM and as well as fibrosis positive and negative pts. Fibrosis was weakly correlated only with the duration of DCM (r = 0.23, p < 0.05), however, not a single serum marker of fibrosis correlated with fibrosis. Neither unadjusted nor adjusted models, constructed from serum markers of ECM metabolism, predicted the probability of myocardial fibrosis.ConclusionsDynamics of ECM turnover in DCM is high, which is reflected by the increased levels CTGF and degradation enzymes. Synthesis of collagen type III prevailed over collagen type I. ECM metabolism was not different in DCM regardless of the duration of the disease and status of myocardial fibrosis. Serum markers of ECM metabolism were found not to be useful for the prediction of myocardial fibrosis in DCM.

TNF-α-Secreting B Cells Contribute to Myocardial Fibrosis in Dilated Cardiomyopathy

Excessive inflammation responses mediated by CD4(+) T cells contributes to myocardial fibrosis in dilated cardiomyopathy (DCM) resulting from viral myocarditis. Recently, some scholars discovered that B cells harbored an abnormal pro-inflammatory capacity besides the production of autoantibodies. Thus, we aimed to explore whether and which type of B cells act on myocardial fibrosis in DCM. A total of 56 newly hospitalized DCM patients were studied, and among these, 17 patients accepted the gadolinium enhanced cardiovascular magnetic resonance imaging (MRI) for myocardial fibrosis evaluations. B cell functions including the frequency and proliferation were significantly elevated in DCM patients. After screening the important cytokines including IL-1β, IL-6, IL-10, IL-17, TNF-α and TGF-β produced in these B cells by flow cytometry, we found that only the TNF-α-secreting B cells were obviously increased. Furthermore, the TNF-α protein secretion and mRNA levels were also enhanced in LPS-stimulated B cell isolated from DCM patients. In addition, 10 patients (59%) with increased TNF-α-secreting B cells showed late enhancement and boosted serum procollagen type III compared with the other 7 patients (41%) whose enhancement could not be detected. Moreover, the frequencies of TNF-α-secreting B cells were negatively correlated with LVEF and positively correlated with LVEDD, NT-proBNP and procollagen type III in all of the DCM patients. Our study firstly suggested that TNF-α-secreting B cells were involved in myocardial fibrosis, which revealed the new pathogenic mechanism of B cells in DCM, and therapeutic targets against these cells might be valuable.

Characteristics and Prognostic Importance of Myocardial Fibrosis in Patients with Dilated Cardiomyopathy Assessed by Contrast-Enhanced Cardiac Magnetic Resonance Imaging

IntroductionDilated cardiomyopathy (DCM) is associated with significant morbidity and mortality. Contrast-enhanced cardiac MRI (CE-CMR) can detect potentially prognostic myocardial fibrosis in DCM. We investigated the role of CE-CMR in New Zealand patients with DCM, both Maori and non-Maori, including the characteristics and prognostic importance of fibrosis.MethodsOne hundred and three patients (mean age 58 ± 13, 78 male) referred for CMR assessment of DCM were followed for 660 ± 346 days. Major adverse cardiac events (MACE) were defined as death, infarction, ventricular arrhythmias or rehospitalisation. CE-CMR used cines for functional analysis, and delayed enhancement to assess fibrosis.ResultsMyocardial fibrosis was present in 30% of patients, the majority of which was mid-myocardial (63%). Volumetric parameters were similar in patients with or without fibrosis. At 2 years patients with fibrosis had an increased rate of MACE (HR = 0.77, 95% CI 0.3–2.0). Patients with full thickness or subendocardial fibrosis had the highest MACE, even in the absence of CAD). More Maori had fibrosis on CE-CMR (40% vs. 28% for non-Maori), and the majority (75%) was mid-myocardial. Maori and non-Maori had similar outcomes (25% vs. 24% with events during follow-up).ConclusionsDCM patients frequently have myocardial fibrosis detected on CE-CMR, the majority of which is mid-myocardial. Fibrosis is associated with worse outcome in the medium term. The information obtained using CE-CMR in DCM may be of incremental clinical benefit.

Non-Invasive Quantitation of Myocardial Fibrosis Using Combined Tissue Harmonic Imaging and Integrated Backscatter Analysis in Dilated Cardiomyopathy

Background: Echocardiographic modalities have challenged the myocardial tissue characterization, but this reliability has not reached to the clinical use. This study investigated whether combined tissue harmonic imaging (THI) and integrated backscatter analysis (IB) provide the reliable and quantitative information about myocardial fibrosis in idiopathic dilated cardiomyopathy (DCM) in comparison with myocardial biopsy findings. Methods: We studied 56 patients with DCM. All patients underwent left ventricular endomyocardial biopsy and IB with fundamental imaging (FI) and THI. Results: In patients with good echocardiographic image quality, excellent correlations between the percentage of area occupied by myocardial fibrosis (% fibrosis) and the mean of integrated backscatter during a cardiac cycle (m-IB) measured with FI or THI were seen, and the correlation was closer with THI compared with FI. While in patients with poor image quality the correlation between m-IB and % fibrosis was only modest with FI, but the correlation was excellent with THI. Four cut-off values of m-IB with THI obtained from receiver operating characteristic curve discriminated between % fibrosis of more and less than 25, 30, 35, and 40% with high sensitivity and specificity. Multivariate analysis revealed that m-IB with THI was an independent predictor for discrimination of the severity of myocardial fibrosis. Conclusion: Combined IB and THI are a clinically applicable method and may be an alternative to myocardial biopsy in evaluating quantitatively myocardial fibrosis in DCM.

Effect of spironolactone on chamber stiffness and diastolic function associated with regression of myocardial fibrosis in dilated cardiomyopathy

We investigated whether spironolactone-induced regression of myocardial fibrosis is associated with improvement of left ventricular (LV) diastolic function in dilated cardiomyopathy (DCM). Methods and Results: Tissue Doppler echocardiography, LV catheterization and biopsies were performed in 10 DCM patients before and after 12 months of treatment with spironolactone. The biochemical index of coupling between the synthesis (PIP) and degradation (CITP) of collagen type-I revealed the presence of 2 subgroups: 5 with PIP/CITP < 40 (GroupA) and 5 with PIP/CITP > 40 (GroupB). After the treatment, collagen volume fraction (CVF), LV chamber stiffness, and diastolic strain-rate were significantly improved in GroupB accompanied with a reduction of PIP/CITP, but not in GroupA (Table). CVF correlated with PIP/CITP (r = 0.70). Conclusions: Spironolactone improves LV diastolic function and chamber stiffness accompanied with regression of fibrosis in patients with higher PIP/CITP. [Display omitted]

New approach to the estimation of the extent of myocardial fibrosis in patients with dilated cardiomyopathy: Use of signal-averaged electrocardiography

To determine whether the extent of myocardial fibrosis in dilated cardiomyopathy could be estimated noninvasively, signal-averaged electrocardiograms were recorded in 32 patients with dilated cardiomyopathy, followed by left ventricular endomyocardial biopsy. The root mean square voltage for the last 40 msec (V40), the duration of the filted QRS complex (fQRSd) and the duration of low amplitude signals <40 μV (LAS) were obtained by signal-averaged electrocardiography. The extent of fibrosis in all biopsy samples was measured by the point-counting method. The extent of myocardial fibrosis closely correlated with fQRSd ( r = 0.623, p < 0.001), LAS ( r = 0.570, p < 0.001), and V40 ( r = −0.355, p < 0.05). When fibrosis was classified into intercellular and interfascicular types, the extent of intercellular fibrosis more closely correlated with fQRSd ( r = 0.695, p < 0.0001), LAS ( r = 0.640, p < 0.0001), and V40 ( r = −0.533, p < 0.005). These results suggest that signal-averaged electrocardiograms might be useful for estimation of the extent of myocardial fibrosis, especially intercellular fibrosis in patients with dilated cardiomyopathy.

Interstitial cell infiltrate and myocardial fibrosis in dilated cardiomyopathy: A special type of cardiomegaly corresponding to sequelae of myocarditis

We examined the relationship between interstitial cell infiltration and myocardial fibrosis in patients with clinically diagnosed dilated cardiomyopathy (DCM). Forty-two cases of DCM were divided into two groups, according to the mean number of the interstitial round cells per 10.2 x 10(4) square microns (Nic): the inflammatory group (Nic greater than or equal to 5) and noninflammatory group (Nic less than 5). The 12 cases in the inflammatory group were clinically similar to the 30 cases in the non-inflammatory group, but the inflammatory group exhibited a significantly (P less than 0.001) larger area of myocardial fibrosis (34.8% +/- 12.8% vs 17.5% +/- 8.2%), a significantly (P less than 0.01) higher frequency of diffuse perimyocytic-type fibrosis (83% vs 23%), fewer myocardial cells in the left ventricular wall (170 +/- 70 fibers vs 216 +/- 81 fibers), and significantly (P less than 0.01) greater hypertrophy of the myocytes (18.3 +/- 3.4 vs 15.3 +/- 2.7 microns). In addition, cases exhibiting marked fibrosis (fibrosis area greater than or equal to 25% of the myocardium) had a significantly higher Nic score (8.3 +/- 6.8) compared to cases with the less fibrotic type of DCM (4.0 +/- 5.7). We speculate that persistent or preceding inflammatory cell infiltration induces the myocardial fibrosis, especially the diffuse perimyocytic type, in the fibrosis-predominant type of DCM. Therefore, most of these cases may be a sequela of myocarditis, and more correctly termed post-myocarditic cardiomegaly.