Non-fibrotic Areas Research Articles

Lesion delivery and scar formation in catheter ablation for atrial fibrillation: The DECAAF II trial

BackgroundThe Efficacy of Delayed Enhancement MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation of Atrial Fibrillation randomized trial showed no difference in atrial fibrillation (AF) recurrence with additional delayed enhancement magnetic resonance imaging (DE-MRI) fibrosis-targeted ablation to pulmonary vein isolation (PVI) in persistent AF. ObjectiveWe evaluated the effect of lesion delivery on ablation-induced scarring and AF recurrence. MethodsLesions delivered, targeting fibrotic and nonfibrotic areas identified from preablation DE-MRI, were studied in relation to ablation-induced scarring on 3-month DE-MRI, including their association with arrhythmia recurrence. ResultsA total of 593 patients treated with radiofrequency were analyzed: 293 (49.4%) underwent PVI and 300 (50.6%) underwent additional fibrosis-guided ablation. Lesion analysis showed that 80.9% in the MRI fibrosis-guided group vs 16.5% in the PVI group (P < .001) had ≥40% of baseline fibrosis targeted. MRI assessment of ablation-induced scar showed that 44.8% of fibrosis-guided ablation and 15.5% of PVI had ≥40% of their fibrosis covered by scar (P < .001), demonstrating significant attenuation from lesions delivered to scar formed. In the overall population, fibrosis coverage with scar was not associated with recurrence (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.80–1.01; P = .08 per 20% increase). In patients with baseline fibrosis < 20%, fibrosis coverage with scar was associated with lower recurrence than PVI (HR 0.85; 95% CI 0.73–0.97; P = .03), whereas the association was not significant when baseline fibrosis ≥ 20% (HR 0.97; 95% CI 0.80–1.17; P = .77). Significant center variation was observed in fibrosis targeting and coverage with scarring. ConclusionRadiofrequency ablation lesions do not uniformly result in scar formation. A post hoc analysis suggests reduced arrhythmia recurrence when ablation-induced scarring covers fibrotic regions in patients with low baseline fibrosis.

Imaging mass cytometry analysis of Becker muscular dystrophy muscle samples reveals different stages of muscle degeneration

Becker muscular dystrophy (BMD) is characterised by fiber loss and expansion of fibrotic and adipose tissue. Several cells interact locally in what is known as the degenerative niche. We analysed muscle biopsies of controls and BMD patients at early, moderate and advanced stages of progression using Hyperion imaging mass cytometry (IMC) by labelling single sections with 17 markers identifying different components of the muscle. We developed a software for analysing IMC images and studied changes in the muscle composition and spatial correlations between markers across disease progression. We found a strong correlation between collagen-I and the area of stroma, collagen-VI, adipose tissue, and M2-macrophages number. There was a negative correlation between the area of collagen-I and the number of satellite cells (SCs), fibres and blood vessels. The comparison between fibrotic and non-fibrotic areas allowed to study the disease process in detail. We found structural differences among non-fibrotic areas from control and patients, being these latter characterized by increase in CTGF and in M2-macrophages and decrease in fibers and blood vessels. IMC enables to study of changes in tissue structure along disease progression, spatio-temporal correlations and opening the door to better understand new potential pathogenic pathways in human samples.

Angiopoietin-like 4 Is a Critical Regulator of Fibroblasts during Pulmonary Fibrosis Development.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible interstitial pneumonia caused by the excessive production and deposition of extracellular matrix components, including type I collagen. Activated fibroblasts, called α-SMA (α-smooth muscle actin)-expressing myofibroblasts, are the major source of type I collagen in pulmonary fibrosis (PF), but the mechanisms underlying disease progression have not been fully elucidated. Here, we obtained lung fibroblasts from patients with IPF from both nonfibrotic and fibrotic areas as determined by a lung computed tomography scan and compared gene expression between these areas by DNA microarray. We found that ANGPTL4 (angiopoietin-like 4) was highly expressed only in fibroblasts from the fibrotic area. ANGPTL4 was selectively expressed in the fibroblastic area of IPF lungs, where the myofibroblast marker α-SMA was also expressed. ANGPTL4 also regulates the gene expression of fibrosis-related markers, cell migration, and proliferation. In addition, ANGPTL4 expression in a murine model of PF induced by treatment with bleomycin was significantly induced in the lungs from the acute to the chronic phase. Single-cell transcriptome analysis during the course of bleomycin-induced PF revealed that Angptl4 was predominantly expressed in the activated fibroblasts and myofibroblasts. Moreover, the administration of recombinant ANGPTL4 to the bleomycin-induced fibrosis model significantly increased collagen deposition and exacerbated the PF. In contrast, the pathogenesis of PF in Angptl4-deficient mice was improved. These results indicate that ANGPTL4 is critical for the progression of PF and might be an early diagnostic marker and therapeutic target for IPF.

Abstract 10850: Epicardial Adipose Tissue is Associated With Left Atrial Volume and Fibrosis in Patients With Atrial Fibrillation

Background : Obesity is a risk factor for atrial fibrillation (AF) and strongly influences response to treatment. Atrial fibrosis shows similar associations. Epicardial adipose tissue (EAT) may be a link between these associations. We sought to assess whether EAT is associated with body mass index (BMI), left atrial (LA) volume and fibrosis. Methods: LA fibrosis and EAT were assessed using Late Gadolinium Enhancement, and Dixon MRI sequences, respectively. We derived 3D models incorporating fibrosis and EAT to assess spatial colocalization: we measured the distance of fibrotic and non-fibrotic areas to the nearest EAT, and calculated the volume of EAT within a radius of 5 mm for every LA surface point. Results: 103 AF patients (64% paroxysmal, 73% male) were analyzed. LA volume index was 54.9 [41.2, 69.7] mL/m 2 , LA EAT index was 17.4 [12.7, 22.9] mL/m 2 , and LA fibrosis was 17.1 [12.4, 23.1] %. LA EAT was significantly correlated with BMI (R=0.557, p&lt;0.001); as well as with LA volume and LA fibrosis after BSA adjustment (R=0.579 and R=0.432 respectively, p&lt;0.001 for both) (Panel A). Multivariable analysis showed LA EAT to be independently associated with LA volume and fibrosis. Aggregation of local EAT proximity values in all models revealed that the minimum distance to fat was significantly greater for fibrotic LA surface regions compared to non-fibrotic areas (6.97 mm [3.28, 12.13] vs 5.71 mm [2.58, 10.35], p&lt;0.001) (Panel C). The proportion of LA surface points having fat within a radius of 5 mm was greater for non-fibrotic compared to fibrotic regions (37.6% [23.4, 48] vs 41.6% [31.2, 58.1] respectively, p=0.021). Thus, 3D registration of fat and fibrosis around the LA showed no clear spatial overlap between EAT and fibrotic LA regions (Panel B). Conclusion: LA EAT is associated with obesity (BMI) as well as LA volume and fibrosis. Regions of LA EAT are not colocalized with fibrotic areas, suggesting a systemic or paracrine mechanism rather than EAT infiltration of fibrotic areas.

Epicardial adipose tissue is associated with left atrial volume and fibrosis in patients with atrial fibrillation.

Obesity is a risk factor for atrial fibrillation (AF) and strongly influences the response to treatment. Atrial fibrosis shows similar associations. Epicardial adipose tissue (EAT) may be a link between these associations. We sought to assess whether EAT is associated with body mass index (BMI), left atrial (LA) fibrosis and volume. LA fibrosis and EAT were assessed using late gadolinium enhancement, and Dixon MRI sequences, respectively. We derived 3D models incorporating fibrosis and EAT, then measured the distance of fibrotic and non-fibrotic areas to the nearest EAT to assess spatial colocalization. One hundred and three AF patients (64% paroxysmal, 27% female) were analyzed. LA volume index was 54.9 (41.2, 69.7) mL/m2, LA EAT index was 17.4 (12.7, 22.9) mL/m2, and LA fibrosis was 17.1 (12.4, 23.1)%. LA EAT was significantly correlated with BMI (R = 0.557, p < 0.001); as well as with LA volume and LA fibrosis after BSA adjustment (R = 0.579 and R = 0.432, respectively, p < 0.001 for both). Multivariable analysis showed LA EAT to be independently associated with LA volume and fibrosis. 3D registration of fat and fibrosis around the LA showed no clear spatial overlap between EAT and fibrotic LA regions. LA EAT is associated with obesity (BMI) as well as LA volume and fibrosis. Regions of LA EAT did not colocalize with fibrotic areas, suggesting a systemic or paracrine mechanism rather than EAT infiltration of fibrotic areas.

Atrial fibrosis identification with unipolar electrogram eigenvalue distribution analysis in multi-electrode arrays

Atrial fibrosis plays a key role in the initiation and progression of atrial fibrillation (AF). Atrial fibrosis is typically identified by a peak-to-peak amplitude of bipolar electrograms (b-EGMs) lower than 0.5 mV, which may be considered as ablation targets. Nevertheless, this approach disregards signal spatiotemporal information and b-EGM sensitivity to catheter orientation. To overcome these limitations, we propose the dominant-to-remaining eigenvalue dominance ratio (EIGDR) of unipolar electrograms (u-EGMs) within neighbor electrode cliques as a waveform dispersion measure, hypothesizing that it is correlated with the presence of fibrosis. A simulated 2D tissue with a fibrosis patch was used for validation. We computed EIGDR maps from both original and time-aligned u-EGMs, denoted as mathcal {R} and mathcal{R}^{mathcal{A}}, respectively, also mapping the gain in eigenvalue concentration obtained by the alignment, Delta mathcal{R}^{mathcal{A}}. The performance of each map in detecting fibrosis was evaluated in scenarios including noise and variable electrode-tissue distance. Best results were achieved by mathcal{R}^{mathcal{A}}, reaching 94% detection accuracy, versus the 86% of b-EGMs voltage maps. The proposed strategy was also tested in real u-EGMs from fibrotic and non-fibrotic areas over 3D electroanatomical maps, supporting the ability of the EIGDRs as fibrosis markers, encouraging further studies to confirm their translation to clinical settings.Graphical Upper panels: map of mathcal {R}^{mathcal {A}} from 3×3 cliques for Ψ= 0∘ and bipolar voltage map Vb-m, performed assuming a variable electrode-to-tissue distance and noisy u-EGMs (noise level σv = 46.4 μV ). Lower panels: detected fibrotic areas (brown), using the thresholds that maximize detection accuracy of each map

Mosaic attenuation in non-fibrotic areas as a predictor of non-usual interstitial pneumonia pathologic diagnosis

The new radiological diagnostic criteria for diagnosing idiopathic pulmonary fibrosis (IPF) seek to optimize the indications for surgical lung biopsy (SLB). We applied the new criteria to a retrospective series of patients with interstitial lung disease (ILD) who underwent SLB in order to analyse the correlation between the radiological findings suggestive of another diagnosis (especially mosaic attenuation and its location with respect to fibrotic areas) and the usual interstitial pneumonia (UIP) pathologic diagnosis. Two thoracic radiologists reviewed the HRCT images of 83 patients with ILD and SLB, describing the radiological findings and patterns based on the new criteria. The association of each radiological finding with radiological patterns and histology was analysed. Mosaic attenuation is highly prevalent in both the UIP and non-UIP pathologic diagnosis and with similar frequency (80.0% vs. 78.6%). However, the presence of significant mosaic attenuation (≥ 3 lobes) only in non-fibrotic areas was observed in 60.7% of non-UIP pathologic diagnosis compared to 20.0% in UIP. This finding was associated with other diagnoses different from IPF, mostly connective tissue disease-associated interstitial lung disease (CTD-ILD) and hypersensitivity pneumonitis (HP). In our series of pathologically confirmed ILD, mosaic attenuation in non-fibrotic areas was a predictor of non-UIP pathologic diagnosis, and was associated with other diagnoses different from UIP, mostly CTD-ILD and HP. If confirmed in larger series, this finding could constitute a valuable tool for improving the interpretation of radiological patterns.

Decline in Mast Cell Density During Diffuse Alveolar Damage in Idiopathic Pulmonary Fibrosis

Mast cells (MCs) are known to be involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF), although their role in acute exacerbations of IPF has not been investigated. The aims of the study were to evaluate the numbers of MCs in fibrotic and non-fibrotic areas of lung tissue specimens of idiopathic pulmonary fibrosis (IPF) patients with or without an acute exacerbation of IPF, and to correlate the MC density with clinical parameters. MCs of IPF patients were quantified from surgical lung biopsy (SLB) specimens (n = 47) and lung tissue specimens taken at autopsy (n = 7). MC density was higher in the fibrotic areas of lung tissue compared with spared alveolar areas or in controls. Female gender, low diffusion capacity for carbon monoxide, diffuse alveolar damage, and smoking were associated with a low MC density. MC densities of fibrotic areas had declined significantly in five subjects in whom both SLB in the stable phase and autopsy after an acute exacerbation of IPF had been performed. There were no correlations of MC densities with survival time or future acute exacerbations. The MC density in fibrotic areas was associated with several clinical parameters. An acute exacerbation of IPF was associated with a significant decline in MC counts. Further investigations will be needed to clarify the role of these cells in IPF and in the pathogenesis of acute exacerbation as this may help to identify some potential targets for medical treatment for this serious disease.

OP0272 68GA-FAPI-04 PET/CT STUDY EXTENSION FOR THE ASSESSMENT OF FIBROBLAST ACTIVATION AND RISK EVALUATION IN SYSTEMIC SCLEROSIS-RELATED INTERSTITIAL LUNG DISEASE

Background:Interstitial lung disease (ILD) is the most common cause of death in systemic sclerosis (SSc). To date, the progression of SSc-ILD is judged by the accrual of lung damage on computed tomography (CT) and functional decline (forced vital capacity). However, this approach does not directly assess the activity of tissue remodeling. Moreover, prediction of the course of ILD in individual SSc patients remains challenging. Fibroblast Activation Protein (FAP) is a specific, ex vivo validated marker for activated fibroblasts.Objectives:The aims of this study were: 1. To assess differences in the uptake of 68GA-FAPI 04 in SSc-ILD patients compared to controls, to analyze 2. whether 68GA-FAPI 04 uptake at baseline correlates with other risk factors of disease progression and 3. Whether 68GA-FAPI 04 uptake is associated with the course of SSc-ILD.Methods:Between September 2018 and April 2020, 21 patients with SSc-ILD confirmed by HRCT and onset of SSc-ILD within ≤ 5 years or signs of progressive ILD and 21 controls without ILD were consecutively enrolled. All participants underwent 68Ga-FAPI-04 PET/CT imaging and standard-of-care procedures including HRCT and lung function testing (PFT) at baseline. Patients with SSc-ILD patients were followed-up for 6 months with HRCT and PFT. Follow-up 68Ga-FAPI-04 PET/CT scans were obtained in a subset of patients treated with nintedanib. We compared baseline 68Ga-FAPI-04 PET/CT uptake to standard diagnostic tools and currently used predictors of ILD progression. The association of 68Ga-FAPI-04 uptake with changes in FVC was analyzed using mixed-effects models.Results:68Ga-FAPI-04 accumulated in fibrotic areas of the lungs in SSc-ILD compared to controls with a median (q1-q3 interval) wlSUVmean of 0.8 (0.6 to 2.1) in the SSc-ILD group and 0.5 (0.4 to 0.5) in the control group (p&lt;0.0001 with Mann-Whitney test) and a median whole lung maximal standardized uptake value (wlSUVmax) of 4.4 (3.05 to 5.2) in the SSc-ILD group compared to 0.7 (0.65 to 0.7) in the control group (p&lt;0.0001). wlFAPI-MAV and wlTL-FAPI were not measurable in control subjects, as no 68Ga-FAPI-04 uptake above background level was observed. In the SSc-ILD group the median wlFAPI-MAV was 254cm3 (163.4 to 442.3) and the median wlTL-FAPI was 183.6 cm3 (98.04 to 960.7). 68Ga-FAPI-04 uptake was higher in patients with extensive disease, with previous ILD progression or high EUSTAR activity scores. Increased 68Ga-FAPI-04 uptake at baseline was associated with progression of ILD independently of extent of involvement on HRCT scan and the forced vital capacity at baseline. In consecutive 68Ga-FAPI-04-PET/CTs, changes in 68Ga-FAPI-04 uptake was concordant with the observed response to the fibroblast-targeting antifibrotic agent nintedanib.Conclusion:Our study presents first in human evidence that 68Ga-FAPI-04-fibroblast uptake correlates with fibrotic activity and disease progression in the lungs of SSc-ILD patients and that 68Ga-FAPI-04-PET/CT may be of potential to improve risk assessment of SSc-ILD.Figure 1.A and B:68Ga-FAPI-04 PET/CT scan from a patient with SSc-ILD with selective 68Ga-FAPI-04 uptake in fibrotic areas of the left- and right lower lung lobes (red arrows), but not in non-fibrotic areas such as the middle lobe (green arrow). B Corresponding CT component.Acknowledgements:We gratefully acknowledge Prof. Uwe Haberkorn (University Hospital Heidelberg and DKFZ, Heidelberg, Germany) and iTheranostics Inc. (Dulles, VA, USA) for providing the precursor FAPI-04.Disclosure of Interests:Christina Bergmann: None declared, Jörg H.W. Distler Speakers bureau: Actelion, Anamar, ARXX, Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, and UCB, Grant/research support from: Anamar, Active Biotech, Array Biopharma, ARXX, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB, Christoph Treutlein: None declared, Koray Tascilar Speakers bureau: Gilead sciences GmbH, Pfizer Turkey, UCB Turkey, Anna-Theresa Mueller: None declared, Armin Atzinger: None declared, Alexandru-Emil Matei: None declared, Johannes Knitza: None declared, Andrea-Hermina Györfi: None declared, Anja Lueck: None declared, Clara Dees: None declared, Alina Soare: None declared, Andreas Ramming: None declared, Verena Schönau: None declared, Oliver Distler Speakers bureau: Arxx Therapeutics, Baecon Discovery, Blade Therapeutics,Bayer, Böhringer Ingelheim, Catenion,Competitive Drug Development International Ltd, Corbuspharma, CSL Behring, ChemomAb, Horizon Pharmaceuticals, Ergonex, Galaapagos NV, Glenmark Pharmaceuticals,GSK, Inventiva, Italfarmaco, IQvia, Kymera, Lilly, Medac, Medscape, MSD, Novartis, Pfizer, Roche, Sanofi, Taget Bio Sciencec, UCB, Grant/research support from: Bayer,Böhringer Ingelheim, Mitsubishi Tanabe Pharma, Olaf Prante: None declared, Philipp Ritt: None declared, Theresa Ida Goetz: None declared, Markus Koehner: None declared, Michael Cordes: None declared, Tobias Baeuerle: None declared, Torsten Kuwert Speakers bureau: Honoraria for occasional lectures by Siemens Healthineers, Grant/research support from: Research grant to the Clinic of Nuclear Medicine by this entity covering projects in the field of SPECT/CT, Georg Schett: None declared, Christian Schmidkonz: None declared

Inflammation in areas of fibrosis: The DeKAF prospective cohort.

Inflammation in areas of fibrosis (i-IFTA) in posttransplant biopsy specimens has been associated with decreased death-censored graft survival (DC-GS). Additionally, an i-IFTA score≥2 is part of the diagnostic criteria for chronic active TCMR (CA TCMR). We examined the impact of i-IFTA and t-IFTA (tubulitis in areas of atrophy) in the first biopsy for cause after 90days posttransplant (n=598); mean (SD) 1.7±1.4years posttransplant. I-IFTA, present in 196 biopsy specimens, was strongly correlated with t-IFTA, and Banff i. Of the 196, 37 (18.9%) had a previous acute rejection episode; 96 (49%) had concurrent i score=0. Unlike previous studies, i-IFTA=1 (vs 0) was associated with worse 3-year DC-GS: (i-IFTA=0, 81.7%, [95% CI 77.7 to 85.9%]); i-IFTA=1, 68.1%, [95% CI 59.7 to 77.6%]; i-IFTA=2, 56.1%, [95% CI 43.2 to 72.8%], i-IFTA=3, 48.5%, [95% CI 31.8 to 74.0%]). The association of i-IFTA with decreased DC-GS remained significant when adjusted for serum creatinine at the time of the biopsy, Banff i, ci and ct, C4d and DSA. T-IFTA was similarly associated with decreased DC-GS. Of these indication biopsies, those with i-IFTA≥2, without meeting other criteria for CA TCMR had similar postbiopsy DC-GS as those with CA TCMR. Those with i-IFTA=1 and t≥2, ti≥2 had postbiopsy DC-GS similar to CA TCMR. Biopsies with i-IFTA=1 had similar survival as CA TCMR when biopsy specimens also met Banff criteria for TCMR and/or AMR. Studies of i-IFTA and t-IFTA in additional cohorts, integrating analyses of Banff scores meeting criteria for other Banff diagnoses, are needed.

Decreased CCN3 in Systemic Sclerosis Endothelial Cells Contributes to Impaired Angiogenesis

Systemic sclerosis (SSc) is a rare and severe connective tissue disease combining autoimmune and vasculopathy features, ultimately leading to organ fibrosis. Impaired angiogenesis is an often silent and life-threatening complication of the disease. We hypothesize that CCN3, a member of the CCN family of extracellular matrix proteins, which is an antagonist of the profibrotic protein CCN2 as well as a proangiogenic factor, is implicated in SSc pathophysiology. We performed skin biopsies on 26 patients with SSc, both in fibrotic and nonfibrotic areas for 17 patients, and collected 18 healthy control skin specimens for immunohistochemistry and cell culture. Histological analysis of nonfibrotic and fibrotic SSc skin shows a systemic decrease of papillary dermis surface as well as disappearance of capillaries. CCN3 expression is systematically decreased in the dermis of patients with SSc compared with healthy controls, particularly in dermal blood vessels. Moreover, CCN3 is decreased invitro in endothelial cells from patients with SSc. We show that CCN3 is essential for endothelial cell migration and angiogenesis invitro. In conclusion, CCN3 may represent a promising therapeutic target for patients with SSc presenting with vascular involvement.

Abstract 494: Role of Slug / PIP Axis in Pulmonary Hypertension Secondary to Pulmonary Fibrosis

Pulmonary hypertension (PH) secondary to pulmonary fibrosis (PF-PH) is the second most common cause of PH. While never studied in detail, pathology reports suggest that vascular remodeling (VR) differs between PF and PF-PH. In PF, VR is mainly limited to fibrotic areas, whereas in PF-PH, it also exist in non-fibrotic areas. These histological differences suggest potential molecular differences. To better understand this mechanism, we investigated the expression of the transcription factor Slug which is known to play a role in PH and PF. Using explanted rat (n=7/group) and human (n=7-14/group) lungs, we compared lung fibrosis, VR and Slug expression between non-fibrotic and fibrotic areas in PF and PF-PH. Online microarray data (GSE24988) were used to find the targets of Slug that are implicated in VR. A new animal model recapitulating our findings in patients was used to test the therapeutic potential of Slug inhibition (n=10/group). This model is based on intra-tracheal instillation of bleomycin (2.5mg/Kg) at day 0 and 2weeks later, an injection of monocrotaline (60mg/kg). PH was assessed by right ventricular systolic pressure (RVSP). P&lt;0.05 are considered significant. In both PF and PF-PH patients, fibrotic areas (PF29±4; PF-PH37±3) exhibit significantly increased VR when compared to non-fibrotic areas of the lung (PF 22±1; PF-PH 31±6). PF-PH patients have increased pulmonary vascular thickening in both areas vs PF patients. This is concomitant with an increased number of Ki67+ vascular cells in PF-PH (12±2%) vs PF (8±1%) as well as an upregulation of Slug in PF-PH patients (2.3±0.5) vs PF (1±0.1). Co-immunolabeling with CD68 demonstrate that macrophages are the main cell type responsible for Slug up-regulation in PF-PH. Human microarray data reveal an up-regulation of the Prolactin-induced protein (PIP) in PF-PH vs PF (9±3 vs 1±0.4). PIP is an extracellular transcriptional target of Slug, known to promote cell proliferation. In-vitro, PIP significantly increases pulmonary arterial smooth muscle cell proliferation in a dose dependent manner. Finally, Slug inhibition decreases RVSP (47±3 vs 62±3mmHg) in an animal model of PF-PH. There are histological differences between PF-PH and PF lungs that are at least in part mediated by a Slug/PIP axis leading to VR.

Mesh induced fibrosis: The protective role of T regulatory cells

Polypropylene mesh is widely used in urogynecologic surgery, but complications rates (pain and exposure) approach 10%. Emerging evidence implicates the adaptive immune system in regulating the foreign body response to mesh, particularly regulatory T cells (Tregs), which modify macrophage differentiation and down-regulate CD8+ effector T cells. We hypothesize that Tregs protect against a profibrotic response, a likely mechanism of pain complications. Here, thin sections of mesh-tissue complexes removed for the primary complaint of pain (N = 14) or exposure (N = 15) were labeled for CD8, CD4 (Th), and FoxP3 (Tregs) via immunofluorescence. The same sections were analyzed for localized collagen deposition via a customized semi-quantitative assessment (0.25 mm2 grid) after trichrome staining. TGF-β1 concentrations were determined by enzyme-linked immunosorbent assay. Fewer Treg and CD4+ cells were found in fibrotic areas versus non-fibrotic areas (503 and 550/cm2 fewer, respectively, both P < 0.001). TGF-β1 was higher in mesh samples compared to autologous control biopsies. TGF-β 1 inversely correlated with age, r −0.636(p = 0.008). No differences were found in T cell subgroups or fibrotic indices between pain and exposure groups. A moderate inverse relationship was found between TGF-β1 and Tregs (r −0.402, P = 0.009). Tregs were present up to 12 years after mesh implantation, challenging the assumption that the adaptive immune response to a foreign body is transient. In conclusion, the inverse relationship between fibrosis and Tregs, and TGF-β1 and Tregs points to a protective role of these cells. Similar immunologic responses in patients with pain and exposure suggest these complications exist along a spectrum. Statement of SignificanceThe use of polypropylene mesh has been associated with improved outcomes in urogynecologic surgery, but is associated with significant complications, including pain and exposure through the vaginal epithelium. The host immune response features a prolonged inflammatory reaction containing innate immune cells and T lymphocytes clustered in capsules around the mesh fibers. This study uncovers the inverse relationship between T regulatory cells and the extent of fibrosis around the mesh, suggesting an anti-fibrotic effect. In addition, concentrations of T regulatory and T effector cells and levels of fibrosis connect these two most common complications into one mechanistic pathway. These new insights into the immune response to implanted mesh are an important step in understanding the causes of these surgical complications.

Short telomere length in IPF lung associates with fibrotic lesions and predicts survival.

Telomere maintenance dysfunction has been implicated in the pathogenesis of Idiopathic Pulmonary Fibrosis (IPF). However, the mechanism of how telomere length is related to fibrosis in the lungs is unknown. Surgical lung biopsies of IPF patients typically show a heterogeneous pattern of non-fibrotic and fibrotic areas. Therefore, telomere length (TL) in both lung areas of patients with IPF and familial interstitial pneumonia was compared, specifically in alveolar type 2 (AT2) cells.Fluorescent in situ hybridization was used to determine TL in non-fibrotic and fibrotic areas of 35 subjects. Monochrome multiplex quantitative polymerase chain reaction (MMqPCR) was used for 51 whole lung biopsies and blood TL measurements.For sporadic IPF subjects, AT2 cell TL in non-fibrotic areas was 56% longer than in fibrotic areas. No such difference was observed in the surrounding lung cells. In subjects carrying a telomerase reverse transcriptase (TERT) mutation, AT2 cell TL was significantly shorter than in sporadic subjects. However, no difference in surrounding cell TL was observed between these subject groups. Finally, using biopsy MMqPCR TL measurements, it was determined that IPF subjects with shortest lung TL had a significantly worse survival than patients with long TL.This study shows that shortening of telomeres critically affects AT2 cells in fibrotic areas, implying TL as a cause of fibrogenesis. Furthermore, short lung telomere length is associated with decreased survival.

Transgenic mice overexpressing desmocollin-2 (DSC2) develop cardiomyopathy associated with myocardial inflammation and fibrotic remodeling.

BackgroundArrhythmogenic cardiomyopathy is an inherited heart muscle disorder leading to ventricular arrhythmias and heart failure, mainly as a result of mutations in cardiac desmosomal genes. Desmosomes are cell-cell junctions mediating adhesion of cardiomyocytes; however, the molecular and cellular mechanisms underlying the disease remain widely unknown. Desmocollin-2 is a desmosomal cadherin serving as an anchor molecule required to reconstitute homeostatic intercellular adhesion with desmoglein-2. Cardiac specific lack of desmoglein-2 leads to severe cardiomyopathy, whereas overexpression does not. In contrast, the corresponding data for desmocollin-2 are incomplete, in particular from the view of protein overexpression. Therefore, we developed a mouse model overexpressing desmocollin-2 to determine its potential contribution to cardiomyopathy and intercellular adhesion pathology.Methods and resultsWe generated transgenic mice overexpressing DSC2 in cardiac myocytes. Transgenic mice developed a severe cardiac dysfunction over 5 to 13 weeks as indicated by 2D-echocardiography measurements. Corresponding histology and immunohistochemistry demonstrated fibrosis, necrosis and calcification which were mainly localized in patches near the epi- and endocardium of both ventricles. Expressions of endogenous desmosomal proteins were markedly reduced in fibrotic areas but appear to be unchanged in non-fibrotic areas. Furthermore, gene expression data indicate an early up-regulation of inflammatory and fibrotic remodeling pathways between 2 to 3.5 weeks of age.ConclusionCardiac specific overexpression of desmocollin-2 induces necrosis, acute inflammation and patchy cardiac fibrotic remodeling leading to fulminant biventricular cardiomyopathy.

Total inflammation in early protocol kidney graft biopsies does not predict progression of fibrosis at one year post-transplant.

There is an uncertainty whether total inflammation in early protocol kidney graft biopsies is associated with fibrosis progression. We investigated whether total inflammation, both in fibrotic and non-fibrotic areas, at week 6 would predict fibrosis progression at oneyr post-transplant. We included 156 single adult ABO compatible kidney recipients with adequate week 6 and oneyr transplant protocol biopsies (312 biopsies). Biopsies were scored according to the current Banff criteria. In addition, fibrosis and inflammation in fibrotic and non-fibrotic areas were scored in a 10-grade semi-quantitative eyeballing system from 0% to 100%. Fibrosis increased significantly from week 6 to oneyr both by the 10-grade scoring system from 0.69±1.07 to 1.45±1.86, (mean±SD), p<0.001 and by Banff interstitial fibrosis (ci) scoring 0.81±0.65 to 1.13±0.87, p<0.001. The 10-grade scoring system detected a larger proportion of fibrosis progressors than the Banff scoring 40.4% vs. 35.5%, p<0.001. No significant positive association was found between inflammation at week 6 and progression of fibrosis in either of the scoring systems. Total inflammation in kidney transplant biopsies at week 6 did not predict progression of fibrosis at oneyr post-transplant.

Histopathologic Features of Explanted Lungs Supported by Veno-Venous Extracorporeal Membrane Oxygenation

Purpose Veno-venous extracorporeal membrane oxygenation (ECMO) is a modality used to support patients with both reversible lung injury and end stage lung disease. In end stage disease, patients are supported until suitable donor lungs become available. The effects of ECMO on native lungs are not well described in the adult population. Methods and Materials We identified all patients in our institution from January 2009 to November 2012 supported with ECMO as a bridge to transplant. The explanted lungs were sectioned, stained and examined under light microscopy. Patterns of injury seen with ECMO supported patients and not typically observed in non-ECMO supported patients are described. Results Twelve patients were identified. Patients were supported for a median of 13 days (range 3-155 days). Patient disease included interstitial pulmonary fibrosis (n=7), emphysema (n=2), cystic fibrosis (n=1), Hermansky-Pudlak syndrome (n=1), and acute respiratory distress syndrome (n=1). Intra-alveolar hemorrhage was present in all cases (n=12) and most prominent in non-fibrotic areas. This was accompanied by chronic interstitial pneumonitis with reactive pneumocyte hyperplasia in all cases (n=12), frequently with patchy acute alveolar injury. Plasma cells were prominent in the interstitial infiltrate of cases with duration of support greater than eight days (n=7). Diffuse hemosiderosis was seen in cases with duration of support greater than eight days (n=7). Organizing pneumonia (OP) pattern was present in the interstitium in seven lungs, with central hemosiderotic fibrosis in areas of OP in three. Airway changes included small airway necrosis in three cases and a bronchiolitis obliterans organizing pneumonia in two. Interstitial neutrophilic infiltrates in areas of hemorrhage were seen in three cases. Conclusions ECMO may cause several patterns of injury not typically present in underlying fibrotic lung disease, which are characterized by acute and organizing lung injury associated with the sequelae of pulmonary hemorrhage.

SPARC Oppositely Regulates Inflammation and Fibrosis in Bleomycin-Induced Lung Damage

Fibrosis results from inflammatory tissue damage and impaired regeneration. In the context of bleomycin-induced pulmonary fibrosis, we demonstrated that the matricellular protein termed secreted protein acidic and rich in cysteine (SPARC) distinctly regulates inflammation and collagen deposition, depending on its cellular origin. Reciprocal Sparc(-/-) and wild-type (WT) bone marrow chimeras revealed that SPARC expression in host fibroblasts is required and sufficient to induce collagen fibrosis in a proper inflammatory environment. Accordingly, Sparc(-/-) >WT chimeras showed exacerbated inflammation and fibrosis due to the inability of Sparc(-/-) macrophages to down-regulate tumor necrosis factor production because of impaired responses to tumor growth factor-β. Hence, the use of bone marrow cells expressing a dominant-negative form of tumor growth factor-β receptor type II under the monocyte-specific CD68 promoter, as a decoy, phenocopied Sparc(-/-) donor chimeras. Our results point to an unexpected dual role of SPARC in oppositely influencing the outcome of fibrosis.

Iron deposition and increased alveolar septal capillary density in nonfibrotic lung tissue are associated with pulmonary hypertension in idiopathic pulmonary fibrosis

BackgroundEarly diagnosis of pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) has potential prognostic and therapeutic implications but can be difficult due to the lack of specific clinical manifestations or accurate non-invasive tests. Histopathologic parameters correlating with PH in IPF are also not known. Remodeling of postcapillary pulmonary vessels has been reported in the nonfibrotic areas of explanted lungs from IPF patients. We hypothesized that iron deposition and increased alveolar capillaries, the findings often seen in postcapillary PH, might predict the presence of clinical PH, independent of the severity of fibrosis or ventilatory dysfunction in IPF patients. To test this hypothesis, we examined the association between these histologic parameters and the degree of PH, with consideration of the severity of disease in IPF.MethodsIron deposition and alveolar septal capillary density (ASCD) were evaluated on histologic sections with hematoxylin-eosin, iron, elastin and CD34 stainings. Percentage of predicted forced vital capacity (FVC%) was used for grading pulmonary function status. Fibrosis score assessed on high resolution computed tomography (HRCT) was used for evaluating overall degree of fibrosis in whole lungs. Right ventricular systolic pressure (RVSP) by transthoracic echocardiography was used for the estimation of PH. Univariate and multivariate regression analyses were performed.ResultsA cohort of 154 patients was studied who had the clinicopathological diagnosis of IPF with surgical lung biopsies or explants during the period of 1997 to 2006 at Mayo Clinic Rochester. In univariate analysis, RVSP in our IPF cases was associated with both iron deposition and ASCD (p < 0.001). In multivariate analysis with FVC% and HRCT fibrosis score included, iron deposition (p = 0.02), but not ASCD (p = 0.076), maintained statistically significant association with RVSP. FVC% was associated with RVSP on univariate analysis but not on multivariate analysis, while fibrosis score lacked any association with RVSP by either univariate or multivariate analyses.ConclusionsIron deposition and ASCD in non fibrotic lung tissue showed an association with RVSP, suggesting that these features are possible morphologic predictors of PH in IPF.

Pulmonary vascular lesions in end-stage idiopathic pulmonary fibrosis: histopathologic study on lung explant specimens and correlations with pulmonary hemodynamics

In patients presenting with idiopathic pulmonary fibrosis (IPF), modifications of pulmonary vessels are well defined in fibrotic areas but have not been accurately assessed in the intervening patches of preserved lung. Moreover, the relation between pulmonary vessel lesions and pulmonary hemodynamics is not well known. We therefore designed a retrospective study on lung explant specimens from 26 patients with a firm diagnosis of IPF who had undergone lung transplantation. Our aim was to (1) describe the vascular lesions, especially in preserved lung areas, and (2) correlate them with pulmonary hemodynamics. In dense fibrotic zones, thickening of the arterial and venous wall with severe luminal narrowing was present in each patient. In architecturally preserved lung zones, occlusion of venules and small pulmonary veins was observed in 65% of the patients, although there were only mild changes of muscular pulmonary arteries. We found a significant positive correlation between the macroscopic extent of lung fibrosis and mean pulmonary artery pressure, but we failed to find a relation between mean pulmonary artery pressure and venous/venular lesions in nonfibrotic areas. Our study points out that in many patients with IPF, nonfibrotic lung areas demonstrate an occlusive venopathy, the signification of which remains undetermined.