Biomedical subjects

Deborah A Witherden

Publications and source records attributed to Deborah A Witherden.

5 recordsLinked to original sources

PubMed2005

Gammadelta T cell-induced hyaluronan production by epithelial cells regulates inflammation.

Nonhealing wounds are a major complication of diseases such as diabetes and rheumatoid arthritis. For efficient tissue repair, inflammatory cells must infiltrate into the damaged tissue to orchestrate wound closure. Hyaluronan is involved in the inflammation associated with wound repair and binds the surface of leukocytes infiltrating damaged sites. Skin gammadelta T cells play specialized roles in keratinocyte proliferation during wound repair. Here, we show that gammadelta T cells are required for hyaluronan deposition in the extracellular matrix (ECM) and subsequent macrophage infiltration into wound sites. We describe a novel mechanism of control in which gammadelta T cell-derived keratinocyte growth factors induce epithelial cell production of hyaluronan. In turn, hyaluronan recruits macrophages to the site of damage. These results demonstrate a novel function for skin gammadelta T cells in inflammation and provide a new perspective on T cell regulation of ECM molecules.

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PubMed2005

Epithelial cells and their neighbors. III. Interactions between intraepithelial lymphocytes and neighboring epithelial cells.

Intraepithelial gammadelta-T cells are present in all epithelial tissues, where they reside in close contact with neighboring epithelial cells. Our data support the idea that the role of these cells is to monitor neighboring cells for signs of damage or disease. Once a problem is detected, the intraepithelial gammadelta-T cells can lyse damaged or malignant epithelial cells, directly participate in tissue repair through production of epithelial growth factors, and play a unique role in the recruitment of inflammatory cells to the site of damage. Intraepithelial gammadelta-T cells play unique roles in homeostasis and disease.

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PubMed2005

Dendritic epidermal T-cell activation.

Although gammadelta T cells compose a small proportion of lymphocytes in lymphoid compartments and peripheral blood, they are the major T-cell population present in epithelial tissues. However, the role played by gammadelta TCR expressing intraepithelial lymphocytes (IEL) has been enigmatic. The location of tissue-resident IEL suggests that they are important members of the first line of defense against insult for organs exposed to the environment, including the skin, gut, lungs, and reproductive system. Dendritic epidermal T cells (DETC) are the skin-resident gammadeltaIEL and serve as a model system for gammadeltaIEL in other locations. DETC have demonstrated importance in the modulation of immune responses, surveillance and repair of tissue, and resistance to infection. This work discusses recent developments in understanding DETC activation.

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PubMed2004

Regulation of skin cell homeostasis by gamma delta T cells.

Although innate T lymphocytes such as gamma delta T cells have been extensively studied, their biological role has remained an enigma to researchers for many years. However, recent advances have begun to explain their complex role in the immune system. Gamma delta T cells are often the major T cell population in epithelial tissues such as the skin, gut, and lung where they have been implicated in maintaining tissue integrity, defending against pathogens, and regulating inflammation. The gamma delta T cells that reside in the skin are a prototypical intra-epithelial lymphocyte (IEL) population. These skin gamma delta T cell receptor (TCR)-expressing cells are named dendritic epidermal T cells (DETC) for their unique dendritic morphology. Using their gamma delta TCR, DETC recognize an unknown ligand expressed by stressed or damaged keratinocytes. Activated DETC exhibit effector functions such as cytokine production, cytolysis, and proliferation in vitro. Recent findings have shown that upon activation by damaged keratinocytes, DETC produce a key keratinocyte growth factor for wound repair called fibroblast growth factor 7 (FGF-7). FGF-7 is produced in vitro and in vivo, suggesting that DETC might play an important role in the biological function of wound repair. Indeed a delay in wound closure and a decrease in the proliferation of keratinocytes at the wound site have been observed in mice lacking gamma delta T cells. In addition to effector functions attributed to DETC, it has also been suggested that gamma delta T cells such as DETC have regulatory roles such as initiating or inhibiting inflammation. This is supported by the findings that DETC produce chemokines and cytokines. Control of the inflammatory response in the epithelium may provide another mechanism to reestablish homeostasis after a biological insult such as wound infliction. Understanding the function of DETC may be useful in the development of future therapies for chronic wounds and the maintenance of skin homeostasis.

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PubMed2004

A keratinocyte-responsive gamma delta TCR is necessary for dendritic epidermal T cell activation by damaged keratinocytes and maintenance in the epidermis.

A unique population of T lymphocytes, designated dendritic epidermal T cells (DETC), homes to the murine epidermis during fetal development. DETC express a canonical gammadelta TCR, Vgamma3/Vdelta1, which recognizes Ag expressed on damaged, stressed, or transformed keratinocytes. Recently, DETC were shown to play a key role in the complex process of wound repair. To examine the role of the DETC TCR in DETC localization to the epidermis, maintenance in the skin, and activation in vivo, we analyzed DETC in the TCRdelta(-/-) mouse. Unlike previous reports in which the TCRdelta(-/-) skin was found to be devoid of any DETC, we discovered that TCRdelta(-/-) mice have alphabeta TCR-expressing DETC with a polyclonal Vbeta chain repertoire. The alphabeta DETC are not retained over the life of the animal, suggesting that the gammadelta TCR is critical for the maintenance of DETC in the skin. Although the alphabeta DETC can be activated in response to direct stimulation, they do not respond to keratinocyte damage. Our results suggest that a keratinocyte-responsive TCR is necessary for DETC activation in response to keratinocyte damage and for DETC maintenance in the epidermis.

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