Targeting Immune-Fibroblast Crosstalk in Myocardial Infarction and Cardiac Fibrosis.

Inflammation and tissue fibrosis co-exist and are causally linked to organ dysfunction. However, the molecular mechanisms driving immune-fibroblast crosstalk in human cardiac disease remains unexplored and there are currently no therapeutics to target fibrosis. Here, we performed multi-omic single-cell gene expression, epitope mapping, and chromatin accessibility profiling in 38 donors, acutely infarcted, and chronically failing human hearts. We identified a disease-associated fibroblast trajectory marked by cell surface expression of fibroblast activator protein (FAP), which diverged into distinct myofibroblasts and pro-fibrotic fibroblast populations, the latter resembling matrifibrocytes. Pro-fibrotic fibroblasts were transcriptionally similar to cancer associated fibroblasts and expressed high levels of collagens and periostin (POSTN), thymocyte differentiation antigen 1 (THY-1), and endothelin receptor A (EDNRA) predicted to be driven by a RUNX1 gene regulatory network. We assessed the applicability of experimental systems to model tissue fibrosis and demonstrated that 3 different in vivo mouse models of cardiac injury were superior compared to cultured human heart and dermal fibroblasts in recapitulating the human disease phenotype. Ligand-receptor analysis and spatial transcriptomics predicted that interactions between C-C chemokine receptor type 2 (CCR2) macrophages and fibroblasts mediated by interleukin 1 beta (IL-1ß) signaling drove the emergence of pro-fibrotic fibroblasts within spatially defined niches. This concept was validated through in silico transcription factor perturbation and in vivo inhibition of IL-1ß signaling in fibroblasts where we observed reduced pro-fibrotic fibroblasts, preferential differentiation of fibroblasts towards myofibroblasts, and reduced cardiac fibrosis. Herein, we show a subset of macrophages signal to fibroblasts via IL-1ß and rewire their gene regulatory network and differentiation trajectory towards a pro-fibrotic fibroblast phenotype. These findings highlight the broader therapeutic potential of targeting inflammation to treat tissue fibrosis and restore organ function.

Single-cell transcriptomics reveals cell-type-specific diversification in human heart failure.

Heart failure represents a major cause of morbidity and mortality worldwide. Single-cell transcriptomics have revolutionized our understanding of cell composition and associated gene expression. Through integrated analysis of single-cell and single-nucleus RNA-sequencing data generated from 27 healthy donors and 18 individuals with dilated cardiomyopathy, here we define the cell composition of the healthy and failing human heart. We identify cell-specific transcriptional signatures associated with age and heart failure and reveal the emergence of disease-associated cell states. Notably, cardiomyocytes converge toward common disease-associated cell states, whereas fibroblasts and myeloid cells undergo dramatic diversification. Endothelial cells and pericytes display global transcriptional shifts without changes in cell complexity. Collectively, our findings provide a comprehensive analysis of the cellular and transcriptomic landscape of human heart failure, identify cell type-specific transcriptional programs and disease-associated cell states and establish a valuable resource for the investigation of human heart failure.

Disparities in Deceased Organ Donor Research Authorization: Experience at One Organ Procurement Organization and Call for National Conversations.

INTRODUCTION: Research with deceased donor organs can provide an important platform for studying interventions to improve organ use and outcomes after authorization from the next-of-kin (NOK) or before death by the decedent (i.e., first-person authorization [FPA]). To date, information on authorization rates across donor subgroups is lacking. METHODS: We performed a retrospective chart review of all 690 deceased organ donors from January 2017 to December 2019 at a midsized Midwestern organ procurement organization (OPO). Multivariable logistic regression was used to assess associations between donor factors and research decline (adjusted odds ratio [aOR], 95% confidence interval [CI]). RESULTS: Electronic records for all 690 deceased donors were reviewed. Of these, 659 (95.5%) yielded at least one transplanted organ. Overall, research was declined in 10.8% of donations. Compared to White donors, research decline was higher for Black (16.0% vs. 8.9%; aOR, 1.87; 95% CI, 1.03-3.40; P = 0.04) and other non-White donors (24.0% vs. 8.9%; aOR, 4.21; 95% CI, 1.02-17.39; P = 0.05). Unadjusted research decline trended higher for Hispanic donors versus non-Hispanic donors (23.1% vs. 10.5%; P = 0.14). Compared to donors age <40 years, research decline trended higher for donors age ≥65 years (16.7% vs. 11.8%; aOR, 4.87; 95% CI, 1.12-21.05; P = 0.03), whereas research decline was 55% lower when donors provided FPA (7.3% vs 15.0%; aOR, 0.45; 95% CI, 0.27-0.76; P = 0.003). CONCLUSIONS: Deceased donor research authorization decline is higher for Black, other non-White, and older donors, but lower when the descendent provides FPA. Identification of disparities in research authorization may stimulate educational strategies to reduce barriers to scientific investigations directed at optimizing the outcomes of organ donation.