Elevated Markers of ECM Reorganization, Fibrosis, and Inflammation Uncovered in Accelerated Aging and Renal Dysfunction of Kidney Cortex and Medulla in Non-Human Primates Exposed to Ionizing Radiation

Whole-body ionizing radiation (IR) causes damage to DNA, lipids, and proteins which leads to oxidative stress, inflammation, and cellular senescence, processes that accelerate biological aging. Slowly reproducing tissues, including kidney, are more likely to react to DNA damage, which may exacerbate aging processes.

Kidney cortex and medulla tissues (N=38 each) were obtained from the Wake Forest Non-Human Primate Radiation Late Effects Cohort and experiments were conducted in compliance with state and federal animal welfare laws. Tissues were homogenized, proteins were digested using S-Trap, desalted by HLB C18-cartridges, then analyzed on a timsTOF HT mass spectrometer (Bruker) in data-independent acquisition (DIA) mode using parallel accumulation serial fragmentation (PASEF) to quantify dynamic protein changes across the following conditions: control with no kidney disease (CTL), irradiated with no kidney disease (IR), irradiated with kidney disease (IR KD), and control with kidney disease (KD). Raw data were analyzed using Spectronaut v18 (Biognosys) and significantly-altered proteins were subjected to bioinformatic analysis.

We leveraged this NHP cohort, a unique national resource, to study accelerated aging and heterogeneity in resilience and aging in the kidney after ionizing radiation exposure. In this analysis, 5,472 and 5,411 M. mulatta protein groups with at least two unique peptides were identified in the kidney cortex and medulla, respectively. As the M. mulatta proteome is not well annotated, proteins from this dataset were mapped to homologous human proteins, thus providing a better annotation of the biological processes and associated gene ontology. Groupwise comparisons were performed to study the influence of 1) kidney disease in irradiated individuals (IR KD vs. IR), 2) only kidney disease (KD vs. CTL), and 3) only irradiation (IR vs. CTL). Interestingly, in almost all comparisons in both the cortex and medulla, over 75% of significantly-altered proteins (i.e., Q value < 0.01 and absolute average log2fold change > 0.58) are significantly upregulated. This includes the extracellular matrix and SASP proteins tenascin, upregulated in all conditions in the cortex and medulla, and periostin, upregulated in all conditions in the cortex. In both tissues, proteins that were significantly-altered and associated with kidney disease in irradiated and non-irradiated animals included SASP proteins and were linked to biological processes involving proteolysis, EGF pathways, integrin signaling, fibrosis, and inflammation. In both tissues, irradiation exposure, regardless of kidney disease status, was linked to significantly-altered SASP proteins involved in fibrosis and proteolytic pathways. Similarities in the fibrotic and proteolytic processes from significantly-altered proteins in either kidney disease or irradiation highlight a potential synergistic effect of irradiation on kidney disease. Overall results from this study will be presented.