Inflammatory responses are an important part of host defenses against pathogens. These responses are principally mediated by leukocytes that release proteases, cytokines, and other inflammatory mediators. Since many of these proteases can degrade components of the extracellular matrix, this inflammatory mechanism of host defense can lead to host tissue destruction when inflammation is chronic. Chronic inflammation causes extensive tissue damage in diseases such as rheumatoid arthritis, atherosclerosis, cystic fibrosis and COPD. We study the regulation of proteases involved in the inflammatory response and seek to develop inhibitors that could control tissue destruction.

Southern Appalachian Ethnopharmacology

The common treatments for rheumatoid arthritis (non-steroidal anti-inflammatory drugs, steroids, and immunosuppressants) produce negative side effects including gastrointestinal disorders and immunodeficiency. Consequently there is a need for the development of therapeutic agents that can be used for long-term administration. Since inflammatory diseases such as rheumatoid arthritis are among the most common health problems treated with traditional remedies, these remedies are a promising source of leads for the development of new therapeutics. Our research focuses on the evaluation of traditional Cherokee remedies that are used to treat rheumatism and/or inflammation and are derived from plants native to the Southern Appalachians. In these mechanistic studies we apply the written and oral history of Cherokee medicine, a rich source of practical knowledge of Southern Appalachian plants. This history includes information on how to achieve the optimal desired medicinal activity, including 1) which environments produce plants with the highest activity 2) which parts of the plants to harvest and at what time in their growing cycle 3) how to preserve the plants and 4) how to prepare the medicine without destroying the activity. We are currently studying the anti-proteolytic and anti-oxidant activities in Cherokee remedies. Inflammation is accompanied by leukocyte activation and subsequently the secretion of proteases and the activation of the oxidative burst. The resulting extracellular proteases and the reactive oxygen intermediates can cause extensive tissue damage in diseases of chronic inflammation.

Students are responsible for plant collection and the development of extraction methods followed by chromogenic and fluorogenic assays for protease and anti-oxidant activities.

Role of HA-CD44 interactions in rheumatoid arthritis

The upregulation of certain proteases during an inflammatory response can lead to proteolytic degradation of the extracellular matrix. In rheumatoid arthritis, a chronic autoimmune inflammatory disorder, matrix metalloprotease 13 (MMP-13) is one of two proteases primarily responsible for the destruction of type II collagen in cartilage. The regulation of MMP-13 in chondrocytes is partly mediated through CD44, a cell-surface receptor for hyaluronan (HA). It has been proposed that CD44 receptors can cluster on the cell surface, thus influencing downstream intracellular signaling events. We hypothesize that the clustering of CD44 is facilitated by high molecular weight HA and promotes extracellular matrix homeostasis, while low molecular weight HA inhibits CD44 clustering thus promoting increased MMP-13 production. Currently no effective clinical inhibitors of MMP-13 exist. A better understanding of the molecular mechanisms that control MMP-13 could provide opportunities for the development of new therapeutics.

Students are responsible for maintaining a CD44-expressing cell line and performing cell-based assays using confocal microscopy and fluorescence spectroscopy. Students also frequently use ELISAs, chromogenic assays, and zymographic assays to study protease activity.

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