Heme oxygenase-1-derived carbon monoxide enhances the host defense response to microbial sepsis in mice.

Sepsis is characterized by a systemic response to severe infection. Although the inflammatory phase of sepsis helps eradicate the infection, it can have detrimental consequences if left unchecked. Therapy directed against inflammatory mediators of sepsis has shown little success and has the potential to impair innate antimicrobial defenses. Heme oxygenase-1 (HO-1) and the product of its enzymatic reaction, CO, have beneficial antiinflammatory properties, but little is known about their effects on microbial sepsis. Here, we have demonstrated that during microbial sepsis, HO-1-derived CO plays an important role in the antimicrobial process without inhibiting the inflammatory response. HO-1-deficient mice suffered exaggerated lethality from polymicrobial sepsis. Targeting HO-1 to SMCs and myofibroblasts of blood vessels and bowel ameliorated sepsis-induced death associated with Enterococcus faecalis, but not Escherichia coli, infection. The increase in HO-1 expression did not suppress circulating inflammatory cells or their accumulation at the site of injury but did enhance bacterial clearance by increasing phagocytosis and the endogenous antimicrobial response. Furthermore, injection of a CO-releasing molecule into WT mice increased phagocytosis and rescued HO-1-deficient mice from sepsis-induced lethality. These data advocate HO-1-derived CO as an important mediator of the host defense response to sepsis and suggest CO administration as a possible treatment for the disease.

Macrophage depletion reduces monocyte chemotactic protein-1 and transforming growth factor-beta1 in healing rat vein grafts.

OBJECTIVE: We previously showed that treatment with liposomally encapsulated dichloromethylene bisphosphonate reduces intimal hyperplasia development and macrophage accumulation in a rat epigastric vein to femoral artery model of intimal hyperplasia. Our objective in this study was to determine the effect of liposomally encapsulated dichloromethylene bisphosphonate on the expression of two cytokines essential to neointimal development, monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-beta1 (TGF-beta). METHODS: We injected rats both 2 days preoperatively and 2 weeks postoperatively with liposomally encapsulated dichloromethylene bisphosphonate (Lip-Clod), liposomally encapsulated phosphate-buffered saline solution (Vector), or phosphate-buffered saline solution (PBS), and harvested the grafts at 1 and 4 weeks. In the perianastomotic region, MCP-1 and TGF-beta protein expression in the total graft cross-section and in the neointima was determined with immunohistochemistry. In whole-graft lysates, MCP-1 and TGF-beta protein were determined with an enzyme-linked immunosorbent assay, and messenger RNA expression was determined with reverse transcription quantitative polymerase chain reaction. RESULTS: Lip-Clod treatment reduced intimal hyperplasia when compared with Vector or PBS treatment. These reductions were significant (P<.05) at both time points. When compared with the PBS treatment, at 1 week but not at 4 weeks Lip-Clod reduced both MCP-1 and TGF-beta protein (P< or =.01 and P< or =.006) in the perianastomotic region of vein grafts. In whole-graft lysates, no significant difference was seen in MCP-1 protein at either time point; however, TGF-beta protein expression was significantly reduced at both 1 and 4 weeks (P=.02 and P=.004). Message analysis in whole-graft lysates at 1 week showed that MCP-1 message expression increased in the Lip-Clod group compared with the PBS group (P=.02), but no significant differences among groups for TGF-beta message levels. Results with Vector were often intermediate to results with Lip-Clod and PBS. CONCLUSION: The major effect of Lip-Clod treatment on TGF-beta and MCP-1 protein levels in the perianastomotic region is observed at 1 week, and macrophage depletion with Lip-Clod inhibits graft neointimal hyperplasia and TGF-beta protein expression in whole-graft lysates at 1 and 4 weeks. These results support the concept that the infiltrating macrophages contribute a significant portion of the cytokines that facilitate intimal hyperplasia and that reducing these cytokines early after grafting influences the development of intimal hyperplasia at later time points. CLINICAL RELEVANCE: All vascular surgeons have patients who have undergone a technically satisfying vein graft, only to have the bypass fail during the first year due to perianastomotic intimal hyperplasia (IH). We hypothesize that vein graft IH is analogous to aberrant wound healing. Central to wound healing is the recruitment of macrophages with their cytokines. This work raises the question whether clinical strategies designed to either decrease macrophages or the cytokines released by macrophages at the time of vein graft placement will be efficacious for limiting the development of IH.

A detailed analysis of cyclin A accumulation at the G(1)/S border in normal and transformed cells.

The temporal relationship between cyclin A accumulation and the onset of DNA replication was analyzed in detail. Five untransformed and nine transformed asynchronously growing cell cultures were investigated using a triple immunofluorescence staining protocol combined with computerized evaluation of staining intensities in individual cells. The simultaneous staining of BrdU, cyclin A, and cyclin E made it possible to determine the cell cycle position of each cell investigated. Cells at the G(1)/S border were identified on the basis of cyclin E content and were further analyzed with respect to cyclin A and BrdU content. A method was developed to calculate objective thresholds defining the highest staining intensity found in the negative cells in the population. Using the thresholds we could distinguish cells with minute amounts of cyclin A and BrdU from truly negative cells. We show that the onset of cyclin A accumulation and the start of DNA replication occurs at the same time, or deviating by a few minutes at the most. We also show that cyclin A accumulates continuously during S. This study clearly demonstrates that nuclear cyclin A can be used as a reliable marker for the S and G(2) phases in both normal and transformed interphase cells.

Olfactory epithelium consisting of supporting cells and horizontal basal cells in the posterior nasal cavity of mice.

The olfactory epithelium of mice generally consists of olfactory cells, progenitors of olfactory cells (globose basal cells), supporting cells, and horizontal basal cells. However, in the dorsal fossa (the roof) of the posterior nasal cavity of mice, we found seven epithelial patches consisting of only non-neuronal cell types, i.e., supporting cells and horizontal basal cells, among the normal olfactory epithelium. The supporting cells occupied three or four layers in the apical to middle regions; in the basal region, horizontal basal cells were localized in a single row adjacent to the basement membrane. Bowman's gland ducts were also present in the epithelium. Neuronal cells (olfactory cells and globose basal cells) were totally absent. The ultrastructure of the supporting cells, horizontal basal cells, and Bowman's glands was essentially similar to that in the normal olfactory epithelium. In the early postnatal period (P1-P7), cell types in the epithelium were the same as those in the normal olfactory epithelium. From P10 to P21, olfactory cells and globose basal cells had disappeared from the olfactory epithelium. At this period, the number of TUNEL-positive cells was significantly higher than that in the surrounding olfactory epithelium; ultrastructurally, many apoptotic figures were observed. This suggests that the epithelium consisting of supporting cells and horizontal basal cells is generated by the apoptotic death of olfactory cells and globose basal cells during postnatal development.

Energy transfer between fluorescein isothiocyanate and propidium iodide--a problem in the estimation of Tpot with the bromodeoxyuridine-DNA flow cytometry technique?

Energy transfer in flow cytometry can occur when two fluorochromes are bound in close proximity (generally within 100 A) and the emission spectrum of one fluorochrome overlaps significantly with the excitation spectrum of the other. The latter criterium is fulfilled for the fluorochromes fluorescein isothiocyanate and propidium iodide and also the former when they, e.g., are used in bromodeoxyuridine - DNA flow cytometry methods. In the present growth kinetic study using this method, we show that energy transfer does take place between fluorescein isothiocyanate and propidium iodide which results in a detected increase in DNA content with 2-3%. Despite the erroneous increase in the obtained DNA content values, this does not seem to have any influence on the calculation of DNA synthesis time and potential doubling time where the DNA content, based on the relative movement principle of the labelled cells, is used.

Immunological aspects of practolol toxicity.

It is unfortunate that there is conflicting immunological data relating to the practolol syndrome. It has not been established if "practolol patients" have some altered T cell function. The work of Behan et al. (1976) strongly supports this interpretation but other groups have not come to the same conclusion. The role of the antibody specific for a practolol metabolite needs to be determined. In practice this is going to be very difficult to do; the drug is no longer used and patients, for obvious reaons, are unwilling to take part in clinical experiments. It is likely that the nature of the metabolite will eventiually be defined and it would be a significant step forward if it could be shown that the antigenic determinant was not formed by other structurally related beta-blocking drugs. Meanwhile the stimulus to further research must be to produce an animal model system, but, for various political and economic reasons, support for such a research effort is difficult to justify.