94 - Increased TGF-β Contributes to Neonatal Hyperoxia Induced Early Cardio-renal Fibrosis and Systemic Vascular Stiffness in 1 Year Old Rats

Poster Number: 94

Merline Benny, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Elaine L. Shelton, Vanderbilt University Medical Center, Nashville, TN, United States; Augusto F. Schmidt, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Shathiyah Kulandavelu, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Pingping Chen, University of Miami, Miami, FL, United States; Runxia Tian, University of Miami Leonard M. Miller School of Medicine, miami, FL, United States; Carolyn A. Abitbol, University of Miami Leonard M. Miller School of Medicine, MIAMI, FL, United States; Shu Wu, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Karen Young, University of Miami, Miami, FL, United States

Background: There is a fundamental knowledge gap in the mechanistic underpinnings linking neonatal hyperoxia (O2)- exposure and its contribution to cardio-renal dysfunction in adults born preterm. TGF-β, a pro-fibrotic cytokine plays a crucial role in cardio-renal fibrosis and vascular stiffness. Here, we test the hypothesis that neonatal hyperoxia induces cardio-renal dysfunction and systemic vascular stiffness in adulthood and this is associated with increased TGF-β levels.

Objective: To determine the association between cardio-renal dysfunction, systemic vascular stiffness and TGF-β levels in adult rats exposed to neonatal hyperoxia.

Design/Methods: Newborn rats (Nf22) randomly assigned to normoxia (RA) or hyperoxia (85% O2) from postnatal day 1 to 14 (P1 to P14), were recovered in normoxic conditions until 1 year of life. At 1 year of life, left ventricular (LV) function was assessed by echocardiography. Aortic and mesenteric arterial stiffness was assessed by wire myography. RNA-seq of the aorta and kidney was done to assess the transcriptional profile of neonatal hyperoxia at 1 year. TGF-β expression was assessed by multiplex cytokine analysis in heart, aorta and kidney. Data are expressed as mean ± SEM, and analyzed by Student’s T test.

Results: At 1 year, there was no evidence of LV dysfunction in rats exposed to neonatal hyperoxia. In contrast, wire myography of medium and large sized systemic vessels revealed that rats exposed to neonatal O2 had significantly increased stiffness of mesenteric artery (Figure 1A-C) and aorta (Figure 1D). Neonatal hyperoxia exposure differentially regulated genes in 1 year old aorta and kidney. Gene set enrichment analysis showed that genes most induced in the aorta by hyperoxia were "connective tissue development", "extracellular matrix remodeling" (Figure 2A) and in the kidney were "actin cytoskeleton", "regulation of epithelial cell differentiation" (Figure 2B). As compared to the normoxia group, rodents exposed to neonatal hyperoxia had significantly increased TGF-β1 and TGF-β2 expression in LV (Figure 3A-B) and increased TGF-β1 and similar TGF-β2 expression in kidney (Figure 3C-D) at 1 year of age. Conclusion(s): Although LV function was normal in neonatal hyperoxia exposed 1 year old rats, these animals had increased systemic vascular stiffness. These findings were accompanied by increased TGF-β expression in LV, aorta and kidney. Further mechanistic studies elucidating the mechanistic role of TGF-β signaling in cardio-renal dysfunction in adult rodents exposed to neonatal hyperoxia would be necessary.
Fig. 1A-D Neonatal hyperoxia increases systemic vascular stiffness in 1 year old rats.Arterial stiffness measured by wire myography in normoxia (black) and hyperoxia (red) exposed rats in mesentric artery and aorta. *P < 0.05
Fig. 2A-B Neonatal hyperoxia induces changes in transcription profile in aorta and kidney.Gene Set Enrichment Analysis in Aorta and Kidney of 1 year rats exposed to normoxia and hyperoxia