Leukocyte NADPH Oxidase Variants in Lupus

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This project will examine the connection between variants in the superoxide-generating leukocyte NADPH oxidase 2 (NOX2), genetic susceptibility and pathogenesis of SLE to follow up on our exciting discovery linking leukocyte NADPH oxidase NCF2 H389Q and R395W mutations to human SLE. Our central hypothesis is that SLE is not a single disease entity, but rather represents distinct subtypes based on combination of some of the genetic risk factors. Thus, we hypothesize that lupus linked to reduced NADPH oxidase activity as a consequence of NOX2 functional variants represent a distinct subtype of SLE with specific pathways regulating pathogenesis, unique biomarkers and therefore responsive to specific therapies. In the present study we will determine the overall prevalence of functionally important NADPH oxidase variants in lupus subjects using next generation sequencing (NGS) technologies to detect and validate important new variants in 9 NADPH oxidase genes and determine the extent of the contribution of the NADPH oxidase complex to the genetic predisposition to human SLE (aim 1) and will further analyze the identified and functionally promising H389Q and R395W NCF2 variants (subaims 1.3 and 1.4). In specific aim 2 we will investigate mechanisms by which reduced NADPH oxidase activity promotes lupus pathogenesis using newly created mouse models of lupus with genetic defects in the NADPH oxidase, including partial deficiency (haploinsufficient NCF2, hypomorphic NCF2) and with deletion of NADPH oxidase in selected myeloid lineages. These mechanistic analyses will be done on several levels: gene expression studies (subaim 2.1) to define biological markers and pathways regulating NOX2 associated lupus; role of type I IFNs in driving pathogenesis (subaim 2.2); role of different cell subsets in driving the process (subaim 2.3); role of NETosis in the pathogenesis (subaim 2.4) and finally assessing potential NOX2 agonists as likely specific treatment modality to this subset of lupus (subaim 2.5).