Precision medicine: myocardial fibrosis burden and genotype predict outcome in non-ischemic dilated cardiomyopathy (DCM)

Introduction

Myocardial fibrosis occurs during pathological remodeling of the heart and can be associated with worse outcome in affected patients. Genetic background is also known to affect patients' survival. In this study we sought to estimate patients' overall fibrosis burden by combining independent modalities including left ventricular endomyocardial biopsy (LV-EMB), circulating biomarkers, and cMRI. We also aimed to use patients' genetics information to predict outcome. Furthermore, we investigated the correlation between cardiac fibrosis and genetic variations to detect novel susceptibility loci for fibrosis in DCM.

Methods

A total number of 542 DCM patients were included. Collagen volume fraction (CVF) was automatically estimated from biopsies. 13 circulating fibrosis biomarkers were measured using Human Magnetic Luminex Screening Assays, and the cMRIs were screened for presence of LGE. Whole exome sequencing (WES) was performed in 410 patients of the cohort using illumina HiSeq 2000. Common (MAF ≥0.05 in the study population OR gnomAD NFE AF ≥0.01) and non-common missense variants (MAF <0.05 in the study population AND gnomAD NFE AF <0.01) in 42 DCM genes were tested for associations with end points using single variants and burden analyses respectively. Analyses were adjusted for age and sex and performed using R and SKAT. End points were all-cause mortality and a composite of heart failure (HF) associated events.

Results

The median follow-up time was 43.2 months (2084 patient-years). Sixty-two patients reached the composite end point and 55 died. LV-EMB proved to be a safe procedure with a total complication rate of 2.3%. Machine learning based characterization of biopsies was highly accurate. Although the 3 different modalities did not significantly correlate with one another, the extent of CVF, levels of MMP-2, TIMP-1, OPN, and GDF-15, and presence of LGE were each significantly associated with worse outcome. Four possible susceptibility loci for cardiac fibrosis in DCM were introduced and underwent eQTL analyses. Rare missense variants in a list of 11 DCM-related genes showed to be associated with the 2 outcome measures or fibrosis burden.

Conclusions

LV-EMB, fibrosis biomarkers, and cMRI likely capture different aspects of a detrimental fibrosis process and may be combined to estimate patients' prognosis and monitor therapeutic success. Phenotype-genotype association studies help elucidate novel disease pathomechanisms and individualize patients' treatment.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): German Centre for Cardiovascular Research: DZHK

Altered density, composition and microanatomical distribution of infiltrating immune cells in cutaneous squamous cell carcinoma of organ transplant recipients

BACKGROUND

The inflammatory tumour microenvironment is crucial for effective tumour control, and long-term immunosuppression has been identified as a major risk factor for skin carcinogenesis. In solid organ transplant recipients (OTRs) undergoing long-term pharmacological immunosuppression, an increased incidence of cutaneous squamous cell carcinoma (SCC) and more aggressive tumour growth compared with immunocompetent patients has been reported.

OBJECTIVES

To determine the density and phenotype of immune cells infiltrating SCC and surrounding skin in OTRs, and to characterize the microanatomical distribution patterns in comparison with immunocompetent patients.

METHODS

We analysed immune cell infiltrates within SCC and at defined regions of interest (ROIs) of tumour-surrounding skin in formalin-fixed paraffin-embedded tissue of 20 renal transplant patients and 18 carefully matched immunocompetent patients by high-resolution semiautomated microscopy on complete tissue sections stained for CD4, CD8, CD20 and CD68.

RESULTS

The overall immune cell density of SCC arising in OTRs was significantly reduced compared with immunocompetent patients. Particularly CD4⁺ infiltrates at the directly invasive margin and tumour vicinity, intratumoral CD8⁺ T-cell densities and the overall density of CD20⁺ tumour-infiltrating B cells were significantly reduced in the tissue of OTRs.

CONCLUSIONS

Immune cell infiltrates within SCC and at defined ROIs of tumour-surrounding skin in OTRs differ markedly in their composition and microanatomical distribution compared with tumours arising in immunocompetent patients. Our findings substantially broaden the understanding of how long-term systemic immunosuppression modulates the local inflammatory microenvironment in the skin and at the site of invasive SCC.

Patch-Based Nonlinear Image Registration for Gigapixel Whole Slide Images

OBJECTIVE

Image registration of whole slide histology images allows the fusion of fine-grained information-like different immunohistochemical stains-from neighboring tissue slides. Traditionally, pathologists fuse this information by looking subsequently at one slide at a time. If the slides are digitized and accurately aligned at cell level, automatic analysis can be used to ease the pathologist's work. However, the size of those images exceeds the memory capacity of regular computers.

METHODS

We address the challenge to combine a global motion model that takes the physical cutting process of the tissue into account with image data that is not simultaneously globally available. Typical approaches either reduce the amount of data to be processed or partition the data into smaller chunks to be processed separately. Our novel method first registers the complete images on a low resolution with a nonlinear deformation model and later refines this result on patches by using a second nonlinear registration on each patch. Finally, the deformations computed on all patches are combined by interpolation to form one globally smooth nonlinear deformation. The NGF distance measure is used to handle multistain images.

RESULTS

The method is applied to ten whole slide image pairs of human lung cancer data. The alignment of 85 corresponding structures is measured by comparing manual segmentations from neighboring slides. Their offset improves significantly, by at least 15%, compared to the low-resolution nonlinear registration.

CONCLUSION/SIGNIFICANCE

The proposed method significantly improves the accuracy of multistain registration which allows us to compare different antibodies at cell level.