RNA-sequencing indicates immune cell signaling and inflammatory gene expression in cardiac fibroblasts increases with developmental age

Background Cardiac fibroblasts are responsible for extracellular matrix turnover and repair in the cardiac environment and serve to help facilitate immune responses. However, it is well established that they have significant phenotypic heterogeneity with respect to location, physiological conditions, and developmental age. The goal of this study was to provide an in-depth transcriptomic profile of cardiac fibroblasts derived from rat hearts at fetal, neonatal, and adult developmental ages to ascertain variations in gene expression that may drive functional differences in these cells at these specific stages of development. Results We performed RNA-seq of cardiac fibroblasts isolated from fetal, neonatal, and adult rats was performed and compared to the rat genome. Principal component analysis of RNA-seq data suggested data variance was predominantly due to developmental age. Differential expression and Gene set enrichment analysis against Gene Ontology and Kyoto Encyclopedia of Genes and Genomes datasets indicated an array of differences across developmental ages, including significant decreases in cardiac development and cardiac function-associated genes with age, and a significant increase in immune and inflammatory-associated functions - particularly immune cell signaling, and cytokine and chemokine production - with respect to increasing developmental age. Conclusion These results reinforce established evidence of diverse phenotypic heterogeneity of fibroblasts with respect to developmental age. Further, based on our analysis of gene expression, age-specific alterations in cardiac fibroblasts may play a crucial role in observed differences in cardiac inflammation and immune response observed across developmental ages. ### Competing Interest Statement The authors have declared no competing interest. * cDNA : complementary deoxyribonucleic acid CF : cardiac fibroblast CM : cardiomyocyte DAPI : 4’,6-diamidino-2-phenylindole DDR2 : discoidin domain receptor 2 DNA : deoxyribonucleic acid ECM : extracellular matrix FBS : fetal bovine serum GAPDH : glyceraldehyde 3-phosphate dehydrogenase GO : gene ontology IL : interleukin KEGG : Kyoto Encyclopedia of Genes and Genomes logFC : log fold change LPS : lipopolysaccharide MMP : matrix metalloproteinase MYH : myosin heavy chain mRNA : messenger ribonucleic acid PBS : phosphate buffered saline PCA : principal component analysis RNA : ribonucleic acid RNA-seq : RNA sequencing RT-qPCR : reverse transcriptase quantitative polymerase chain reaction