429 Elevated Phosphate Levels Induce Lung Inflammation and Exacerbate Pulmonary Fibrosis

Abstract

OBJECTIVES/GOALS: Using a cell culture model, we will determine the effects of phosphate on primary lung cell cultures and use our results to delineate a pathway through which these changes are carried out. Using animal models, we will determine the effects of phosphate on inflammatory and fibrotic lung injury, both in the presence and absence of CKD. METHODS/STUDY POPULATION: For our in vitro experiments, human lung fibroblasts were treated with concentrations of 1 to 5 mM sodium phosphate and FGFR inhibitors. Expression levels of interleukin (IL)-1beta, IL-6, and IL-8 were analyzed by qPCR and secretion of these cytokines was measured by ELISA. Phosphorylation of PLCy and ERK was measured by western blot. Using an in vivo approach, we placed C57Bl/6 mice on a high phosphate (3%) diet to elevate serum phosphate levels in the absence of kidney injury and administered bleomycin via oropharyngeal aspiration to generate an acute inflammatory response. Serum FGF23 levels were measured by ELISA and serum analysis for phosphate and renal function were obtained. Furthermore, expression of FGF23 pathway and inflammatory markers were analyzed in murine lung tissue using qPCR and western blotting. RESULTS/ANTICIPATED RESULTS: Augmented phosphate concentrations led to increased cytokine expression and secretion from human lung fibroblasts as well as a concomitant increase in PLCy and ERK phosphorylation. Inhibition of FGFR1 reversed the effects of phosphate on the inflammatory cytokines and PLCy/ERK phosphorylation. Serum FGF23 levels were significantly upregulated in mice on a high phosphate diet and further increased in mice subjected to a high phosphate diet with exposure to bleomycin. Both serum phosphate and creatinine levels were significantly elevated as well. Additionally, high phosphate and bleomycin increased local FGF23 expression in murine lung tissue, when compared to controls or each stimulus alone. DISCUSSION/SIGNIFICANCE: Phosphate has a significant impact on inflammation and fibrosis in the lung, indicating that the existence of pulmo-renal crosstalk exaggerates pulmonary injury and that there are biological pathways that may be targeted therapeutically to mediate these effects. These results could have a substantial impact on the quality of life for CKD patients.