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T-cell accumulation in atherosclerotic plaques contributes to plaque destabilization. We found that several chemokine receptors are differentially expressed on peripheral blood compared to plaque-resident T cells and corresponding ligands are upregulated in plaques. These data indicate that T-cell migration into human atherosclerotic plaques may predominantly occur via CCR5-CCL3 and CX3CR1-CX3CL1 interactions.

The vast majority of new HIV infections in male-to-female transmission occurs through semen, where HIV-1 is present in two different forms: as free and as cell-associated virus. In the female lower genital tract, semen mixes with female genital secretions that contain various factors, some of which facilitate or inhibit HIV-1 transmission. Next, HIV-1 crosses the genital epithelia, reaches the regional lymph nodes, and disseminates through the female host. Cervico-vaginal mucosa contains multiple barriers, resulting in a low probability of vaginal transmission. However, in some cases, HIV-1 is able to break these barriers. Although the exact mechanisms of how these barriers function remain unclear, their levels of efficiency against cell-free and cell-associated HIV-1 are different, and both cell-free and cell-associated virions seem to use different strategies to overcome these barriers. Understanding the basic mechanisms of HIV-1 vaginal transmission is required for the development of new antiviral strategies to contain HIV-1 epidemics.

Problem Although it is established that the levels of individual cytokines are altered by HIV-1 infection, the changes in cytokine interrelations that organize them into networks have been poorly studied. Here, we evaluated these networks in HIV-infected and HIV-uninfected individuals in fluid compartments that are critical for HIV-1 pathogenesis and transmission, namely blood and semen. Method of Study In samples collected from therapy-naive HIV-1-infected and HIV-1-uninfected individuals, we measured HIV-1-load, CD4 cell count, and levels of 21 cytokines using a multiplex bead assay. Results Cytokine networks in blood and semen were different for HIV-1-infected and HIV-1-uninfected individuals. In both compartments of HIV-1-infected individuals, the cytokine networks were more interlocked than in controls: HIV-1 infection resulted in the establishment of new correlations and in the strengthening of pre-existing correlations between different cytokines. In blood and semen of HIV-infected patients, there were, respectively, 68 and 72 statistically significant correlations between cytokines, while in uninfected individuals, there were 18 and 21 such correlations. Conclusion HIV-1 infection reorganizes the cytokine networks, establishing new strong correlations between various cytokines and thus imposes a high rigidity on the cytokine network. This rigidity may reflect the impairment of the ability of the immune system to respond to microbial challenges.

Vaginal intercourse remains the most prevalent route of infection of women. In spite of many efforts the detailed mechanisms of HIV-1 transmission in the female lower genital tract, remain largely unknown. With all the obvious restrictions on studying these mechanisms in humans, their understanding depends on the development of adequate experimental models. Isolated cell cultures do not faithfully reproduce important aspects of cell-cell interactions in living tissues and tissue responses to pathogens. Explants and other types of ex vivo tissue models serve as a bridge between cell culture and tissues in vivo. Here, we discuss various cervico-vaginal tissue models and their use in studying HIV vaginal transmission and consider future directions of such studies.

Under physiological conditions significant amounts of low-density lipoprotein LDL particles ar taken up by cells independently of specific high affinity LDL receptors (apo-B receptors). Previously it was established that some cells contain surface sites capable of binding liposomes. We proposed that liposome-binding sites could contribute to LDL interaction with the cell surface via phospholipid molecules of LDL particles. To check this hypothesis we studied the competitive interaction of human LDL and DPPC liposomes with mouse embryo fibroblasts depleted of apo-B receptors by preliminary incubation with LDL. We have found that after removal of the liposome-binding sites from cell lamellae these areas of the cell surface lose their ability to bind LDL.

A novel technique for modulating the spreading of ascites cells has been developed. Plasma membranes of Ehrlich ascites carcinoma cells were modified in two different ways: 1) biotin residues were covalently coupled to membrane components; 2) biotinylated lipid was introduced into plasma membrane. Adhesion and spreading of modified cells on avidin-coated substrates were studied and compared to those of non-modified cells. Both types of membrane alteration were shown to induce specific (biotin-dependent) interaction with immobilized avidin with resultant cell spreading. Spread cells attained epithelioid-like morphology with the formation of wide thin lamellae, focal contacts with substrate, and circular actin bundles. The process of spreading was shown to be energy-dependent: it could be blocked by metabolic inhibitors and by low temperature. Formation of extended lamellae was prevented by preincubation of cells in the presence of cytochalasin B. The effects of metabolic poisons, low temperature, and microfilament--disruptive drugs were reversible and after the restoration of physiological conditions the cells resumed the spreading process. Immunoprecipitation of biotinylated cell lysates with antiserum to cytoplasmic domain of beta 1-integrin subunit revealed a major 110 kD avidin-binding component. We conclude that lack of spreading of ascites carcinoma cells may be explained by the lack of functionally active adhesion- and spreading-competent cell-surface receptors, but may not be attributed to the defects in intracellular function or organization. Intracellular machinery of cell spreading is preserved in these ascites cells and could be turned on by cell attachment to the substrate via artificial adhesive site incorporated into plasma membrane.

Closed lipid vesicles (liposomes) have been widely used in recent years for introducing biologically active substances into cells. The spectrum of substances which have been thus entrapped ranges from small ions and molecules to large macromolecules including polylnosinic-polycytidylic acid [l] and 4 S-23 S RNA [2,3]. However up to now no attempts to incorporate DNA into liposomes have been reported in the literature. Such DNA-containing liposomes could be potentially useful as carriers for introducing foreign DNA into cells and could also serve as models for the study of membrane interactions. We demonstrate here that high molecular weight DNA of more than 10 000 base-pairs can be associated with egg lecithin and entrapped in liposomes. Such DNA becomes DNase-resistant. Incorporation of DNA into the liposomes seems to be the result of both electrostatic binding and mechanical entrapment of macromolecules.