Invited review: Dairy intake and bone health: a viewpoint from the state of the art.

The aim of this review was to focus on the complex relationships between milk and dairy products intake and bone health, with particular emphasis on osteoporosis. The literature was extensively examined to provide an objective overview of the most significant achievements on the subject. Osteoporosis can be defined as a disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Although the major determinants of peak bone mass and strength are genetic, major factors during childhood and adolescence may affect the ability to achieve peak bone mass. These include nutrition, particularly calcium and protein intake, physical activity, endocrine status, as well as exposure to a wide variety of risk factors. The role of calcium intake in determining bone mineral mass is well recognized to be the most critical nutritional factor to achieve optimal peak bone mass. The greatest amount of dietary calcium is obtained from milk and dairy foods, which also provide the human diet with vitamin D (particularly for products fortified with vitamin D), potassium, and other macro- and micronutrients. Although studies supporting the beneficial effects of milk or calcium on bone health are predominant in the literature, perplexity or discordance on this subject was expressed by some authors. Discordant data, mainly on the risk of fractures, provided limited proof of the unfavorable effect of dairy intake. More often, discordant works indicate no effect of dairy consumption on bone safety. Some considerations can be drawn from this viewpoint. Milk and dairy products are an optimal source of calcium as well as of other limiting nutrients (e.g., potassium and magnesium), with important effects on bone health. Bioactive components occurring in milk and dairy products may play an essential role on bone metabolism, as shown by in vivo and in vitro studies on colostrum acidic proteins and milk basic proteins. Calcium intake positively affects bone mass and is crucial in childhood and youth for correct bone development. In elderly people, calcium intake as well as vitamin D availability should be carefully checked. As a general conclusion, calcium is essential for bone health, although it will not prevent bone loss due to other factors; in this context, milk and dairy foods are bioavailable, relatively inexpensive sources of calcium for the human diet.

Kinetics of Th1/Th2 cytokines and lymphocyte subsets to predict chronic GVHD after allo-SCT: results of a prospective study.

The role of different cytokines and cells of immune system in the pathogenesis of chronic GVHD (cGVHD) is still controversial. Earlier studies, which were either retrospective or analysed one or a few factors, did not show unequivocal results. We prospectively evaluated cytokine levels and lymphocyte subsets in 30 patients who underwent Allo-SCT to investigate their possible correlation with cGVHD. Levels of IL-4, IL-6, IL-10, IFN-gamma, tumour necrosis factor-alpha (TNF-alpha) and its soluble receptors were assessed by ELISA in 30 patients at different times after SCT. Lymphocyte subsets were evaluated by flow cytometry in peripheral blood at the same times as cytokines. A multivariate analysis was performed using principal component analysis and multi-factor ANOVA (analysis of variance). Eighteen patients developed cGVHD at a median time of 6 months (range, 5-9) after SCT. In multivariate analysis, we observed a correlation between cGVHD and clusters of cytokines and lymphocyte subsets from the third to the sixth month after SCT. These clusters changed their composition over time, but they constantly included natural killer (NK) and CD152+ T cells as negative predictors of cGVHD. TNF-alpha prevailed among other cytokines before the onset of cGVHD. This prevalence could be related partly to the defect of immunoregulatory cells.

HIV p17 reverses the anti-inflammatory activity of IL-4 on IL-15 stimulated monocytes and modulates their ability to secrete MIP-1 alpha.

Monocytes play a central role in the immune system by producing and reacting to different soluble factors. Cytokine dysregulation is an hallmark in HIV-infected individuals and it is one of the most significant factors leading to impaired immunity in HIV/AIDS disease. This study investigates the possibility of modulation in the secretion of some inflammatory cytokines and chemokines induced by HIV p17 in monocytes. The results show that p17, while ineffective on resting monocytes, exerts an inflammatory action on IL-4 mediated inhibition of TNF-alpha and IFN-gamma production induced by IL-15 stimulation. In addition, p17 is able to reduce MIP-1alpha secretion, but unable to influence IL-6 production. The ability of HIV p17 to contribute to an altered pattern of secreted soluble factors might imply a key role for this viral protein in the development of AIDS pathogenesis.

Human stoned B interacts with AP-2 and synaptotagmin and facilitates clathrin-coated vesicle uncoating.

Synaptic vesicle biogenesis involves the recycling of synaptic vesicle components by clathrin-mediated endocytosis from the presynaptic membrane. stoned B, a protein encoded by the stoned locus in Drosophila melanogaster has been shown to regulate vesicle recycling by interacting with synaptotagmin. We report here the identification and characterization of a human homolog of stoned B (hStnB). Human stoned B is a brain-specific protein which co-enriches with other endocytic proteins such as AP-2 in a crude synaptic vesicle fraction and at nerve terminals. A domain with homology to the medium chain of adaptor complexes binds directly to both AP-2 and synaptotagmin and competes with AP-2 for the same binding site within synaptotagmin. Finally we show that the mu 2 homology domain of hStnB stimulates the uncoating of both clathrin and AP-2 adaptors from clathrin-coated vesicles. We hypothesize that hStnB regulates synaptic vesicle recycling by facilitating vesicle uncoating.

Adult human heart microvascular endothelial cells are permissive for non-lytic infection by human cytomegalovirus.

OBJECTIVE: Human cytomegalovirus (CMV) infection has been linked to chronic heart disease. The mechanism of CMV dissemination to the heart remains unknown. CMV antigens and nucleic acid sequences have been detected in endothelial cells (ECs) in vivo, and ECs are fully permissive hosts to CMV replication in vitro. This report examines the characteristics of CMV replication in primary cultures of human heart microvascular ECs (HHMECs). METHODS: Capillary ECs were isolated from heart tissue biopsies of six patients at the time of heart surgery. HHMECs were infected with CMV and viral antigens were detected by immunofluorescence assay using monoclonal antibodies as specific reagents. Cytokine and chemokine release in the supernatant of sham- and CMV-infected cells was quantitated by ELISA. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to analyse expression of mRNA for adhesion molecules. RESULTS: CMV was found to productively infect HHMECs without cytolytic effects. Infected cultures released high levels of pro-inflammatory chemokines and enhanced their adhesion molecule expression. CONCLUSIONS: Our data provide new insights into the mechanism of CMV dissemination to the heart, signalling the need for further investigation of the pathogenetic role of this virus in cardiac disorders.

Expansion of rare CD8+ CD28- CD11b- T cells with impaired effector functions in HIV-1-infected patients.

The decline in the number of CD4+ T cells in HIV-1-infected patients is known to be related to the increased number of CD8+CD28- T cells. In this paper, we show that CD8+CD28- T cells from HIV-positive patients have an impaired capability to interact with human endothelial cells. This is due to the dramatic expansion, within this subset, of rare CD11b- cells lacking cell-cell adhesion functions. In 50 HIV-positive patients, 19.5% +/- 6.5% of all T cells were CD8+CD28-CD11b-, whereas only 0.8% +/- 0.4% of all T cells from healthy donors showed this uncommon phenotype. The percentage of circulating CD8+CD28-CD11b- T cells was strongly related to the percentage of CD4+ T cells (r = -0.82). This population is peculiar in terms of HIV infection and was found to possess some characteristics associated with effector functions but its cytotoxic properties were impaired. The percentage of target cells lysed by CD8+CD28-CD11b- was significantly lower than that of cells lysed by its CD11b- counterpart (p <.05) both at low (5:1) or at relatively high (20:1) effector/target ratios. CD8+CD28-CD11b- T cells, which lack the ability to interact with endothelial cells, are likely to accumulate and persist in circulation. The biologic properties of CD8+CD28-CD11b- T cells suggest that these cells might be endstage or aberrant differentiated effector cells. Lack of cell-cell adhesion and impaired cytolytic functions favor the hypothesis of a role for CD8+CD28-CD11b- T cells in the development of immunodeficiency.

Generation of CD28- cells from long-term-stimulated CD8+CD28+ T cells: a possible mechanism accounting for the increased number of CD8+CD28- T cells in HIV-1-infected patients.

According to CD28 molecule expression, CD8+ T cells can be classed as CD28bright, CD28dim, and CD28-. The CD28dim T cells were found to derive from mitogenic stimulated CD28-T cells but also from CD28bright T cells through a mechanism of CD28 down-modulation. Moreover, after prolonged in vitro interleukin-2 stimulation, clonal CD28bright, cells showed a CD28dim expression before further evolution to a stable CD28-phenotype. This loss was concomitant with the disappearance of CD28 mRNA. A study of the cytokine production pattern revealed that CD28dim and CD28- T cell clones produced similar levels of type 1 and type 2 cytokines, which differed from those produced by the CD28bright T cell clones. A high percentage of CD28dim and CD28- cells, with similarities in their cytokine production pattern, were found in the blood samples of HIV-infected patients, as compared to healthy donors. The CD28 down-modulation may account for the increased number of CD8+CD28- T cells in HIV-infected patients.

Segregation of type 1 cytokine production in human peripheral blood lymphocytes: phenotypic differences between IFN-gamma and IL-2-producing cells in the CD8+ T cell subset.

T cell clones are classified as type 0, 1 or 2 depending on the lymphokines they produce. However, it has remained unclear whether single cells of a given type produce one or several cytokine species. Flow cytometric analysis of peripheral blood lymphocytes (PBL) obtained from 20 healthy donors for the production of the type 1 cytokines IFN-gamma and IL-2 revealed very few cells that co-expressed both cytokines independently of the mitogenic stimulus used for PBL activation. Similarly, kinetic studies of cytokine synthesis indicated a low percentage of IFN-gamma/IL-2 double-positive T cells at all time points. Reverse transcription-PCR analysis of sorted IL-2- and IFN-gamma-positive T cells showed the presence of IL-2- or IFN-gamma-specific mRNA only in those cells expressing the corresponding cytokine. This segregation of the two type 1 cytokines was lost in long-term cultured T cells and in T cell clones. A high percentage of cells expressing only IL-2 or IFN-gamma was observed even when the production of these cytokines was evaluated on CD4- and CD8+ subsets. Moreover, in some healthy individuals, IFN-gamma and IL-2 production by CD8+ T cells was related to CD8+ expression levels and cell size, i. e. IL-2-expressing cells were generally smaller with more intense CD8+ staining as compared with IFN-gamma-producing T cells. These data indicate that activated T lymphocytes are strongly committed in vivo to produce IFN-gamma or IL-2 and emphasizes the independent regulation of the two cytokine genes.

Contribution of CD4+, CD8+CD28+, and CD8+CD28- T cells to CD3+ lymphocyte homeostasis during the natural course of HIV-1 infection.

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ and CD8+ T cell subsets showed wide intrapatient variation. Variations in the number of CD8+CD28+ cells paralleled those of the CD4+ T cell subset in each patient tested, while the presence of CD8+CD28- T cells correlated inversely with CD4+ and CD8+CD28+ T cells. These data show that changes in the number of circulating CD4+-and CD8+CD28+ T cells are strongly related to the presence of CD8+CD28- T cells in these patients. Insight into the significance of CD8+CD28- T cell expansion will allow us to understand the mechanisms and significance of the HIV-1- driven change in CD4+CD8+ T cell homeostasis and the basic immunopathology of HIV disease.