Culture of mouse peritoneal macrophages with mouse serum induces lipid bodies that associate with the parasitophorous vacuole and decrease their microbicidal capacity against Toxoplasma gondii

Lipid bodies [lipid droplets (LBs)] are lipid-rich organelles involved in lipid metabolism, signalling and inflammation. Recent findings suggest a role for LBs in host response to infection; however, the potential functions of this organelle in Toxoplasma gondii infection and how it alters macrophage microbicidal capacity during infection are not well understood. Here, we investigated the role of host LBs in T. gondii infection in mouse peritoneal macrophages in vitro. Macrophages cultured with mouse serum (MS) had higher numbers of LBs than those cultured in foetal bovine serum and can function as a model to study the role of LBs during intracellular pathogen infection. LBs were found in association with the parasitophorous vacuole, suggesting that T. gondii may benefit from this lipid source. Moreover, increased numbers of macrophage LBs correlated with high prostaglandin E2 (PGE2) production and decreased nitric oxide (NO) synthesis. Accordingly, LB-enriched macrophages cultured with MS were less efficient at controlling T. gondii growth. Treatment of macrophages cultured with MS with indomethacin, an inhibitor of PGE2 production, increased the microbicidal capacity against T. gondii. Collectively, these results suggest that culture with MS caused a decrease in microbicidal activity of macrophages against T. gondii by increasing PGE2 while lowering NO production.

Síndrome hemofagocítico reactivo en pacientes graves: Comunicación de 4 casos / Reactive hemophagocytic syndrome in critical care patients. Report of 4 cases

El síndrome hemofagocítico reactivo, o linfohistiocitosis hemofagocítica secundaria, comprende un grupo numeroso de enfermedades, muchas de ellas de causa infecciosa, caracterizado por hemofagocitosis con citopenia de al menos dos de las tres series sanguíneas, aumento de los niveles de citoquinas y de la ferritina sérica. El cuadro clínico comprende manifestaciones inflamatorias sistémicas semejantes a la sepsis, entidad muy frecuente en las unidades de Terapia Intensiva, y posee elementos fisiopatológicos en común con ella. Proponemos mediante la presentación de cuatro casos clínicos, considerar al síndrome hemofagocítico reactivo como una entidad frecuente en los pacientes graves, con pruebas sencillas para orientar a qué pacientes realizar un procedimiento diagnóstico. Por último actualizamos los tratamientos específicos conocidos.

Reactive hemophagocytic syndrome or hemophagocytic lymphohistiocytosis comprises a variety of disorders, many of them associated with infection. It is characterized by hemophagocytosis, with cytopenia involving at least two cellular lines, increase in cytokines and serum ferritin. The clinical course resembles sepsis, sharing similar physiopathological features. We propose that hemophagocytic syndrome is an underdiagnosed entity in the critical care setting; simple tests aid to identify which patients should undergo diagnostic procedures. We discuss current therapeutic approaches.

Plasma clearance and biodistribution of oxidatively modified 99mTc-Beta-VLDL in rabbits

The biodistribution and removal from plasma (measured as fractional clerance rate, FCR, per hour) of native and oxidatively modified (99m)technetium-labeled Beta-very low density lipoprotein ((99m)Tc-Beta-VLDL)) were investigated in hypercholesterolemic (HC) and control (C) three-month old New Zealand rabbits. The intracellular accumulation of Beta-VLDL labeled with (99m)Tc was studied in vitro in THP-1 cells and monocyte-derived macrophages isolated from rabbits. After intravenous injection into C rabbits, copper-oxidized Beta-VLDL ((99m)Tc-ox-Beta-VLDL)) was cleared from the circulation faster (0.362 + 0.070/h) than native Beta-VLDL ((99m)Tc-nat-Beta-VLDL, 0.241 + 0.070/h)). In contrast, the FCR of (99m)Tc-ox-Beta-VLDL in HC rabbits was lower (0.100 + 0.048/h) than that of (99m)Tc-nat-Beta-VLDL (0.163 + 0.043/h). The hepatic uptake of radiolabeled lipoproteins was lower in HC rabbits (0.114 + 0.071 percent injected dose/g tissue for (99m)Tc-nat-Beta-VLDL and 0.116 + 0.057 percent injected dose/g tissue for (99m) Tc-ox-Beta-VLDL) than in C rabbits (0.301 + 0.113 percent injected dose/g tissue for (99m)Tc-nat-Beta-VLDL and 0.305 + 0.149 percent injected dose/g tissue for ((99m)Tc-ox-Beta-VLDL). The uptake of (99m)Tc-nat-Beta-VLDL and (99m)Tc-ox-Beta-VLDL by atherosclerotic aorta lesions isolated from HC rabbits ((99m)Tc-nat-Beta-VLDL:0.033 + 0.012 percent injected dose/g tissue and (99m)Tc-ox-Beta-VLDL: 0.039 + 0.017 percent injected dose/g tissue) was higher in comparison to that of non-atherosclerotic aortas from C rabbits (99m)Tc-nat-Beta-VLDL: 0.023 + 0.010 percent injected dose/g tissue and (99m)Tc-ox-Beta VLDL: 0.019 + 0.010 percent injected dose/g tissue). However, (99m) Tc-nat-Beta-VLDL and (99m)Tc-ox-Beta-VLDL were taken up by atherosclerotic lesions at similar rates. In vitro studies showed that both monocyte-derived macrophages isolated from rabbits and THP-1 macrophages significantly internalized more (99m)Tc-ox-Beta-VLDL than (99m)Tc-nat-Beta-VLDL. These results indicate that in cholesterol-fed rabbits (99m)Tc-ox-Beta-VLDL is slowly cleared from plasma and accumulates in atherosclerotic lesions. However, although the extent of in vitro uptake of (99m)Tc-ox-Beta-VLDL by macrophages was high, the in vivo accumulation of this radiolabeled lipoprotein by atherosclerotic lesions did not differ from that of (99m)Tc-nat-Beta-VLDL.

Activation of macrophage functions by growth factor present in uterus and embryo extract of pregnant mouse

A pregnant mouse uterus and embryo extract (PMUE) that contains growth hematopoietic factor (M-CSF or CSF-1), was used to test its action on the phagocytic and digestive functions of macrophage. Macrophages incubated with and without PMUE for 24 hours previous to each experiment were compared. A good phagocytosis of Trypanosoma cruzi by macrophages incubated with PMUE, was observed on video microscopy. No phagocytic activity was observed in the macrophages deprived of PMUE 24 hours before. The studies of phagocytic and degradative behavior of macrophages by both soluble and particulated (S. aureus) complex 125I-antibodies showed that total binding of soluble ligands was almost double in the group of macrophages incubated with PMUE. Both the soluble and particulated ligands were digested more efficiently by the macrophages stimulated by PMUE. Counting the macrophages with trypan blue, an equal viability was found, of the cells incubated with and without PMUE. From the experimental data obtained, we may conclude that the hematopoietic growth factor present in PMUE is essential for phagocytic and degradative functions of macrophages.