Tenascin in pregnant and non-pregnant rat uterus: unique spatio-temporal expression during decidualization.

Tenascin is a large extracellular matrix (ECM) protein generally restricted to developing embryonic tissues and tissues undergoing remodelling in the adult, but it has been suggested that tenascin is immunomodulatory. In this study we have used indirect immunofluorescence to investigate the distribution of tenascin within the uteri of pregnant and non-pregnant rats. The non-pregnant uterus expressed tenascin in the stroma around the glands, but only the subluminal stroma showed cyclical variations. Dependence of the latter on progesterone was verified in ovariectomized animals supplemented with steroid hormones. During early pregnancy, the uterine circular smooth muscle maintained an intense expression of tenascin. In the decidualizing endometrium, tenascin expression showed dramatic changes that reflected the regionalization of the decidualization process. On Day 6 (blastocyst attachment), tenascin immunoreactivity was prominent in the primary decidualization zone immediately surrounding the conceptus. On Day 7, expression had increased within the secondary decidua that had developed throughout the antimesometrial endometrium. By Day 8, the antimesometrial decidua showed diminished tenascin immunoreactivity; expression became largely confined to the ECM of the developing decidua in the mesometrial region, where levels were high. On Day 10, the well-developed mesometrial decidua was negative. Interestingly, tenascin expression was up-regulated in the walls of the vessels in the metrial gland within the mesometrial triangle beginning on Day 10 of pregnancy. From these studies we conclude that tenascin expression may be an important reflection of the dynamics involved with tissue restructuring during early pregnancy and may play a role in immunomodulation, since expression of this protein in the mesometrial decidua coincides with the presence of differentiating natural killer cell lineage lymphocytes in the same region.

Phagocyte function and cytokine production in community acquired pneumonia.

BACKGROUND: It is possible that many deaths from pneumonia may involve the generation of inflammatory mediators and tissue damage by activated phagocytes. To test this hypothesis phagocyte function, plasma levels of interleukin 6 (IL-6), tumour necrosis factor alpha (TNF alpha), and soluble interleukin 2 receptor (IL-2R), disease severity, and outcome have been examined in 46 patients with community acquired pneumonia. METHODS: Polymorphonuclear leucocyte (PMNL) and monocyte function were measured daily by chemiluminescence in these patients during the first week of admission, and cytokine levels were subsequently determined by ELISA. A series of 61 healthy individuals were used as a control group for the chemiluminescence results. RESULTS: There was evidence of phagocyte, particularly PMNL, activation on admission in 76% of the patients. Most patients (86%) also had raised IL-2R levels on admission. IL-6 and unbound TNF alpha were present in 23% and 41% of patients at varying times during the course of the disease. There was little correlation between measurements of cytokine or phagocyte levels and outcome or indicators of disease severity, although this may be because of the small number of patients included in this preliminary study. CONCLUSIONS: These results are consistent with the hypothesis that activated phagocyte function and raised levels of circulating cytokines may contribute to the pathogenesis of community acquired pneumonia. There are striking similarities in this respect between pneumonia, adult respiratory distress syndrome, and sepsis.

The DEBR rat: an animal model of human alopecia areata.

The Dundee experimental bald rat (DEBR) is reported as a model for human alopecia areata. Parallels with human alopecia areata were observed in relation to the gradual and patchy loss of hair and the penetration of both pelage and vibrissa follicles by mononuclear cells. In particular, the apparent disruption of the follicles within the precortical region of the epidermal component and consequent alterations of normal geometrical relationships between dermal and epidermal components relate directly to similar studies on human alopecia areata. In comparison with other previously described hypotrichotic rodent mutants, the DEBR rat exhibits a unique mechanism of hair loss which may provide important information regarding the pathomechanism of human alopecia areata.

Immunobiological studies on the alopecic (DEBR) rat.

The Dundee experimental bald rat (DEBR) has been proposed as an animal model of human alopecia areata, which is suspected of being an autoimmune disease. This study was carried out to establish whether the immunological changes observed in the lesional DEBR rat correlated with studies of human alopecia areata. The immune infiltrate was characterized using immunoperoxidase techniques on cryostat sections of vibrissa follicles. Indirect immunofluorescence was used to quantify the peripheral blood leucocytes. Some parallels were observed in the infiltration of human and DEBR rat follicles by T lymphocytes. In contrast, pre-lesional DEBR rat follicles, which are not available for investigation in human alopecia areata, were not penetrated by leucocytes and MHC class II antigens were expressed in the precortical region of the epidermal component of these follicles. Quantification of peripheral blood leucocytes showed significant increases in both T-lymphocyte subsets during lesional expression. We consider that the pre-lesional form of the rat may provide important information as a model for the pre-lesional and uninvestigated form of alopecia areata in man.