Dietary lipids and Experimental IgA Nephropathy

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Chronic inflammatory diseases impact millions of people in the U.S. annually and contribute extensively to morbidity, mortality and health care costs. Clinical studies suggest that consumption of n-3 polyunsaturated fatty acids (PUFAs) from fish oil is efficacious for both prevention and treatment of inflammatory diseases such as IgA nephropathy (IgAN), rheumatoid arthritis, psoriasis, atherosclerosis and lupus. Although nearly 26 million U.S. adults currently consume n-3 PUFAs, mechanisms of action of these supplements remain incompletely understood. Specifically, a critical gap exists in our knowledge of how n-3 PUFAs attenuate expression of inflammatory genes that contribute to inflammatory diseases. Recent studies of mycotoxin- induced mouse model of IgAN suggest that n-3 PUFAs target transcriptional regulation of interleukin-6 (IL-6) which is critical for aberrant IgA hyperelevation. The objective of this proposal is to elucidate the specific mechanisms by which n-3 PUFAs suppress activation of the transcription factor CREB and resultant gene transcription. Our central hypothesis is that n-3 PUFAs disrupt regulation of CREB activation and downstream CRE-mediated gene transcription in the macrophage. To test this hypothesis, ourresearch team will use macrophages exposed to n-3 PUFAs via diet or in culture to elucidate how CREB phosphorylation and downstream transcription of IL-6 and other genes are suppressed. The central hypothesis will be tested by pursuing the following (1) Relate effects of n-3 PUFA intake on CREB kinases to CREB activation in the macrophage; (2) Relate effects of n-3 PUFA intake on Ser/Thr protein phosphatases CREB activation in the macrophage; (3) Characterize specificity of n-3 PUFA effects on CRE-mediated transcription relative to target genes and tissue. Several outcomes are anticipated to arise from this work. First, we expect to have an improved understanding of the molecular basis by which n-3 PUFAs interfere with inflammatory gene transcription. Second, the models developed here will directly inform medical care workers on the applicability of n-3 PUFA supplementation for prophylaxis/treatment of IgAN and other diseases that involve inflammatory gene induction as well as appropriate n-3 PUFA tissue levels and dosages. Third, this research will yield important new safety information regarding potential deleterious affects of n-3 PUFAs in tissue not related to the innate immune system. Collectively, these outcomes will positively impact human health by providing a scientific basis for generating sound public health recommen- dations relative to an important class of nutritional supplements consumed by a large number of Americans.