Introduction: The development and progression of diabetic kidney disease (DKD) is thought to involve a combination of hemodynamic, metabolic, ischemic, and inflammatory factors; however, the exact mechanism remains to be elucidated. Given the pro-inflammatory component of DKD, gene expression of leukocytes is thought to provide additional insight into the disease. Here we describe microarray analysis of peripheral blood mononuclear cells (PBMCs) in diabetic patients with varying levels of albuminuria. Moreover, the findings were compared against publicly available gene expression data from human diabetic kidney biopsies in order to find candidate genes critical for disease progression.

Methods: Microarray experiments were performed on PBMCs isolated from a cohort (Cohort I) of 40 patients (10 healthy controls, 11 with DM and normoalbuminuria, 7 with DM and micro albuminuria, and 5 with DM and macroalbuminuria, 7 with DM and ESRD). Gene expression across different levels of proteinuria were measured and ranked. From an independent cohort (Cohort II) of 4 publicly available microarray experiments, a total of 67 (25 with DN and 42 control) microarray experiments of kidney glomeruli were analyzed using a computation meta-analysis. Genes determined to be significantly expressed in kidney tissue were compared with those from PBMCs. Immunohistochemistry was performed on tissue biopsies from a separate diabetic cohort to validate protein expression of the candidate genes.

Results and Discussion: From Cohort I, there were 859 genes significant (p < 0.05) for increasing expression with higher levels of albuminuria. The meta-analysis of Cohort II, revealed 326 significant up regulated and 249 down regulated genes. There were 28 genes were found to have increased expression in PBMCs and glomeruli with. hypergeometric enrichment significant p value of 5E-04. Pathway analysis revealed a strong pro-inflammatory signature regulated though tumor necrosis factor (TNF), toll like receptor (TLR), with contribution from chemokine signaling and pathways dysregulated in innate immunity. The most significant hub genes were identified to be a chemokine gene CCR1 and a gene involved in atopy called FcER1. Immunohistochemistry validated increased expression of both proteins in DKD biopsies.

Conclusion: Integrative genomic analysis of blood and kidney samples in DKD uncover novel targets for rational drug design. In vivo studies are underway to evaluate the efficacy of blocked of CCR1 and FcER1 for improving proteinuria in animal models of DKD.

CITATION INFORMATION: Nguyen M, Kodama K, Sarwal M. Novel Therapies for Diabetic Kidney Disease. Am J Transplant. 2017;17 (suppl 3).

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