SUMMARYExposure to foreign particles sometimes causes inflammatory reactions through production of cytokines and chemoattractants by phagocytic cells. In this study, we focused on macrophage migration inhibitory factor (MIF ) to evaluate its pathophysiological role in the phagocytic process. Immunohistochemical analysis of human pseudosynovial tissues retrieved at revision of total hip arthroplasty showed that infiltrating mononuclear and multinuclear cells were positively stained by both an anti-CD68 antibody and anti-human MIF antibody. For in vitro study, MIF was released from murine macrophage-like cells (RAW 264.7) in response to phagocytosis of fluorescent-latex beads in a particle dose-dependent manner. Northern blot analysis showed marked elevation of the MIF mRNA level in the phagocytic macrophage-like cells. Moreover, pretreatment of RAW 264.7 cells with rat recombinant MIF increased the extent of phagocytosis by 1·6-fold compared with the control. Taken together, these results suggest that MIF plays an important role by activating macrophages in autocrine and paracrine fashion to phagocytose foreign particles.

SUMMARYBone resorption and formation are dynamic processes that occur in both normal and injured bone tissues. Regulation of these processes is mediated at the local level by cytokines and growth factors. Macrophage migration inhibitory factor (MIF) is one of the proinflammatory cytokines that activates macrophages and regulates production of other cytokines, such as tumour necrosis factor-a and interleukin-1. We here demonstrate, by reverse transcription-polymerase chain reaction, high expression of MIF mRNA in murine osteoblasts obtained from mouse neonatal calvariae and murine osteoblastic MC3T3-E1 cells. The presence of MIF protein in the osteoblasts was confirmed by Western blot analysis using anti-rat MIF antibody. Moreover, the immunohistochemical study revealed that MIF was localized largely in the cytoplasm. The pathophysiological function of MIF remains undefined; however, the present results suggest that MIF takes part in the osseous metabolism as well as in immunological events.

To examine the effects of interleukin-1 beta (IL-1 beta) on collagenase production by human periodontal ligament fibroblasts (PLF) and gingival fibroblasts (GF) in culture, collagenase activity in conditioned media was determined using a novel procedure that circumvented interference by enzyme inhibitors. Fibroblasts obtained from five paired periodontal ligament and gingival tissues were cultured for two weeks, and then incubated for a further 72 h in alpha-MEM supplemented with various concentrations of IL-1 beta (0 to 1250 pg/ml). The conditioned media from individual cultures were harvested and treated with dithiothreitol to inactivate TIMPs, and then with APMA, to activate the latent collagenase. Collagenase activity was measured fluorometrically using FITC-collagen as a substrate. IL-1 beta induced a approximately 2.4 to 5.2-fold increase in collagenase activity in PLF compared to a approximately 1.4 to 2.2-fold increase in GF. These results are in contrast to previous studies in which collagenase activity was measured in the presence of TIMPs, and indicate that PLF are more sensitive to IL-1 beta than GF. Since both PLF and GF are present in periodontal lesions, it is possible that collagenase secretion stimulated by exposure to inflammatory cell products such as IL-1 beta may participate in the destruction of collagen fibers involved in periodontal attachment.

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Little has been known about the reduction of uronic acid to the corresponding aldonic acid. A few examples have been presented of the reduction of hexuronic acids, viz. the reduction of D-glucuronic acid or its lactone by TPNH* (1-4) and that of some keturonic acids by DPNH (5-8). On the other hand, it has been established by several workers that the immediate TPN L-Hexonate Dehydrogenase 619 aldehyde reductase proposed recently by Hers (4) or glucuronate reductase (26). A part of this paper was reported previously (25, 27). METHODS AND MATERIALS Materials•\D-Glucurono-r-lactone, sodium D-glu curonate, ethyl D-glucuronate, and D-glucuronamide were obtained from the Chugai Pharmaceutical Com pany. D-Galacturonate was purchased from the Nutritional Biochemicals Corporation, D-mannurono-ƒÁ-lactone was provided through the courtesy of Dr .