Inflammation often promotes formation of tertiary lymphoid tissue, containing B cell foci which cause autoimmune pathology and occasionally transform into malignancy. In these sites, a DNA-modifying enzyme, activation-induced cytosine deaminase (AID), has an important role in generating pathogenic autoantibody (autoAb) and inducing oncogenic mutations. This laboratory's recent in vitro discovery that a cyclooxygenase (COX-2) axis within in vitro replicating human B cells significantly augments AID expression/function provide new insights into a mechanism for these events. This proposal's long term goal is to test the hypothesis that in vivo-expressed B cell COX-2 plays a significant role in augmenting AID and downstream pathogenic IgG autoAb in an autoimmune setting. Evidence that COX-2 activity is important for IgG Ab production in normal and autoimmune mice has been reported. Nevertheless, it remains unclear whether COX-2 function in B cells or in neighboring non-B cells is involved. Sjogren's Syndrome (SjS) is an autoimmune disease characterized by salivary gland inflammation, AID-expressing B cells, pathogenic IgG autoAbs that impair salivation, and a high rate of B cell lymphoma. Furthermore, stimuli linked to SjS in humans and/or mouse models are known to be inducers of B cell COX-2 expression in vitro. Thus, SjS is clearly a disease in which B cell COX-2 expression may be relevant. This project will test whether B cell-expressed COX-2 is important in promoting IgG Ab-driven disease manifestations in SjS. Crucial to this is (a) a recently generated SjS- susceptible NOD.B10 mouse line whose floxed COX-2 gene can be a target for Cre-mediated inactivation and (b) a proprietary method for generating mAb-bound nanoparticles (NP) containing biologically active molecules. B cell-targeted, biodegradable NP containing rCre as a """"""""payload"""""""" will be generated with an electrohydrodynamic approach that incorporates mAb into the outer biodegradable shell and Cre into an inner core. Proof of principle studies to confirm in vitro and in vivo NP specificiy and activity will be performed with mice expressing the fluorescence indicator gene (GFP) under the control of a ubiquitous promoter and floxed stop signal. Subsequently, B cell-targeted, Cre-laden nanoparticles will be tested in SjS-susceptible NOD.B10 mice expressing floxed or wild-type COX-2 genes. Evidence that selective Cre-mediated COX-2 inactivation in B cells prevents the hyposalivation characteristic of SjS and impairs the formation of pathogenic IgG Abs to the M3R muscarinic acetylcholine receptor would be important and would suggest that specific NP hold promise in the selective targeting of therapeutic molecules in human disease.
The proposed research is relevant to public health because it will discern whether a newly discovered COX-2 pathway in B lymphocytes is important for generating pathogenic autoantibodies in autoimmune disease. While studies will be performed in a mouse model for Sjogren's Syndrome, a debilitating autoimmune disease which primarily targets women over the age of fifty, the implications of the work will extend to other conditions. Results from this project should show whether B cell COX-2 should be targeted and provide proof of principle evidence supporting an innovative means of targeting therapeutics selectively to B cells.
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