Synergistic and selective stimulation of gelatinase B production in macrophages by lipopolysaccharide, trans-retinoic acid and CGP 41251, a protein kinase C regulator

AbstractThe production of gelatinase B by macrophages is relevant in the immunological and migratory functions of macrophages. CGP 41251, an inhibitor of protein kinase C (PKC), was found to stimulate the expression of gelatinase B in macrophages, as shown by the study of two different monocytic/macrophagic cell lines, mouse RAW 264.7 and human THP-1 cells. When human monocytis and rat peritoneal macrophages were treated with CGP 41251, insignificant increases of 10 and 25% were obtained. This can possibly be due to the presence of contaminating cells in these two enriched populations, since the CGP 41251 treatment of non-macrophagic cell lines inhibited their PMA-induced gelatinase B production. Taken together, these results suggest that the stimulatory effect of CGP 41251 is specific to cells of the monocytic lineage. Using RAW 264.7 cells as a model, the effect of CGP 41251 is additive to that obtained using lipopolysaccharide (LPS) and phorbol 12-myristate 13-acetate (PMA), as revealed by gelatin zymography and Northern blot analysis. The stimulatory effect of CGP 41251 on gelatinase B production in RAW 264.7 was: (a) inhibited by calphostin C (as is the LPS-induced response), indicating a PKC-dependence; (b) inhibited by dexamethasone (as opposed to the LPS-induced response); and (c) enhanced by addition of trans-retinoic acid (RA). In fact, RA can induce gelatinase B production, either alone or in synergy with LPS and/or CGP 41251, since the combination of the three agents gives the highest gelatinase B response, at both the protein and the mRNA levels. This represents an important observation considering that RA is now being tested as an anti-cancer agent and proposed for prevention studies

Assessing whether progesterone-matured dendritic cells are responsible for retention of fertilization products in missed abortion

We hypothesize that progesterone causes tolerogenic maturation of myeloid dendritic cells (DCs) in human decidua of threatened miscarriage or missed abortion characterized by a distinct phenotype and cytokine production, including reduction of the main NK cell proliferation and cytotoxic factor interleukin (IL)-15. During DC/NK cell interaction, progesterone-shaped DCs cannot efficiently multiply or equip NK cells with the cytotoxic mediators peforin and granulysin, which might harm trophoblasts and induce abortion. We propose that the presence, and maturation stage of decidual myeloid DCs be investigated using semi-quantitative immunohistological analyses and/or double-color immuno-fluorescent labeling of DC lineage and activation markers. The spatial arrangement of granulysin+ cells, NKp46+ NK cells, DCs, and trophoblasts might provide information about their mutual interactions in vivo. Multiple flow cytometry analyses of NK-receptors would provide insight into NK cell activation status. NK cell activation status could be also assessed by cytotoxicity assays against trophoblast cell lines, or isolated cognate extra-villous trophoblast cells. A correlation between decidual progesterone concentration or IL-15 expression, and the degree of DC maturation or the frequency of granulysin+ cells, might help to elucidate the mechanism of abortion retention in utero