Joint degeneration: Somatic mosaic analysis in a transgenic mouse

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DESCRIPTION (provided by applicant): Osteoarthritis (OA) is the most common form of arthritis and a major cause of activity limitation and physical disability in the elderly: 80%-90% of humans over the age of 65 suffer from OA. Available treatments for OA are mostly palliative with limited specificity. In fact, the recently identified serious side effects of some intra- oral COX-2 selective inhibitors (i.e. Vioxx, Bextra) underscore the need for the development of novel anti- inflammatory therapies for OA. The purpose of this research proposal is to characterize a mouse model of degenerative joint disease following the conditional induction of intra-articular, low level IL-1beta expression in the adult mouse and to explore the utility of siRNA-based anti-inflammatory therapy in the management of temporomandibular joint (TMJ) osteoarthritis. To this end, we will employ somatic mosaic analysis in the Col1-IL1beta-XAT transgenic mouse model recently developed in our laboratory, which utilizes a Cre/loxP based molecular genetic method to temporally and spatially activate a germline-transmitted recombinational substrate containing a dormant IL-1beta transcription unit. Preliminary data demonstrate the development of OA-like pathology in the knees and TMJ of Col1-IL1beta-XAT transgenic mice after intra-articular Cre administration as assessed by histopathological, immunohistochemical and behavioral studies. The following specific aims are proposed to further develop and characterize this model: (1) Characterize the development of TMJ arthritis following somatic mosaic analysis in the Col1- IL1beta-XAT transgenic mouse in terms of joint pathology and orofacial pain; (2) evaluate the effectiveness of intra-articular anti-mPGES-1 and anti-COX-2 siRNA therapy versus available pharmacologic inhibitors in the TMJ of Col1-IL1beta-XAT transgenic mice. We have recently developed small inhibitory RNA (siRNA) constructs capable of attenuating COX-2, as well as other members of the cyclooxygenase-prostaglandin pathway, including COX-1, mPGES-1 and cPGES. We propose to express these siRNA constructs intra-articulalry using a feline immuno-deficiency viral platform, FIV(siRNA). The proposed studies will contribute in the evaluation of novel therapeutic targets (i.e. mPGES- 1) as well as contribute to the development of new therapeutic tools (siRNA). Our proposal is submitted in response to the NIDCR program announcement PA-04-139 entitled "Joint degeneration: Mouse models", which solicits research proposals employing genetically defined and genetically modified mouse models to explore the biological mechanisms underlying OA and novel therapeutics such as siRNA technology. To this end, we have brought together a multidisciplinary team of experts from the University of Rochester that have successfully collaborated and published in the past and who will contribute the necessary expertise for the completion of this project.