ABSTRACT
A leishmaniose é considerada como um grupo de doenças, causadas por parasitos do gênero Leishmania. O gênero inclui mais de 20 espécies de parasitos que são transmitidas ao homem pela picada da fêmea, infectada, dos insetos da família dos flebotomíneos e as diferentes espécies estão associadas a diferentes manifestações clínicas da doença. Uma característica marcante na infecção é a presença de macrófagos infectados no sítio de inoculação do parasito e em órgãos internos do hospedeiro. Estudos prévios, demonstraram que a infecção de fagócitos mononucleares com Leishmania amazonensis, L. infantum ou L. braziliensis promove uma diminuição na adesão celular ao tecido conjuntivo inflamado da pele. Esta diminuição da adesão é decorrente, principalmente, de mecanismos envolvidos na regulação da molécula VLA-4, uma integrina da família beta 1 que se liga à VCAM-1...
Leishmaniasis is considered a group of diseases, caused by parasites of the genus Leishmania. The genus includes more than 20 species of parasites that are transmitted to humans by the bite of vector female insect, of the phlebotomine family, and the different species are associated with different clinical manifestations of the disease. A striking feature of infection is the presence of infected macrophages at the site of inoculation of the parasite and internal organs of the host. Previous studies have demonstrated that infection of mononuclear phagocytes with Leishmania amazonensis, L. infantum or L. braziliensis promotes a decrease in cellular adhesion to the inflamed connective tissue of the skin. This decrease in adhesion results mainly from mechanisms involved in the regulation of the VLA-4 molecule, a beta 1 integrin that binds to VCAM-1...
Subject(s)
Humans , Leishmania/growth & development , Leishmania/immunology , Leishmania/parasitology , Leishmania/pathogenicity , Monocytes/immunologyABSTRACT
Objective To investigate the effects of stromal cell-derived factor-1 (SDF-1) on the adherence of mononuclear cells (MNC). Methods Mononuclear cells were isolated from cord blood and the adherent rate was assayed by using MTT with fibronectin coated in different concentration of SDF-1. Then the expression of adherent molecule VLA-4 by FACS as well as the adherent rate when MNC were cultured in vitro. Results The adherent rate of fresh cord blood MNC was (110.2±2.10) %, (128.3±2.09) %, (141.6±2.62) %, (160.8±3.84) %, (162.3±3.60) %, (165.4±2.73) %, (165.1±2.33) %. When the mass concentration of SDF-1 was 50, 100, 150, 200, 250 ng/ml. When MNC were cultured in vitro,the expression of VLA-4 was 26.37te was (160.2±6.38) %, (194.6±6.09) %, (147.5±6.86) %, (144.7±4.96) %, (118.1±3.64) %. The correlation coefficient between the adherent rate and the expression of VLA-4 is 0.826. Conclusion The adherent rate of fresh cord blood MNC increases along with the concentration of SDF-1, however, it tends to be stable when the concentration of SDF-1 reaches 100 ng/ml. When MNC were cultured in vitro with hemopoietic growth factors, the expression of VLA-4 and the adherent rate of MNC increased in the initial stage, however, the expression of VLA-4 and the adherent rate of MNC both decreased gradually along with time extending. There is positive correlation between the adherent rate of MNC and the expression of adherent molecule VLA-4.
ABSTRACT
Very late antigen-4 (VLA-4), which binds to the extracellular matrix protein fibronectin, is an integrin molecule known to be modulated during mobilization of CD34+ cells, and to be involved in signaling the mobilization stimuli. On the hypothesis that cell cycling status might be different depending on the level of VLA-4 expression, we investigated the DNA contents of human cord blood CD34+ cells during ex vivo expansion by recombinant human thrombopoietin and flt3-ligand with simultaneous measurement of surface VLA-4 at the 1st and 4th week. During this ex vivo expansion, expression of VLA-4 increased and almost all cells became VLA-4+ until the 4th day of culture. Expression of VLA-4 was maintained in the major population of the cultured cells until the 4th week. The cells in S/G2/M phase were greater in number in VLA-4 high fraction than in VLA-4 low fraction (n=4, p<.001). Furthermore, the fraction of cells in S/G2/M phase increased as the expression of VLA-4 became higher. These results suggest that cord blood CD34+ cells expressing high levels of VLA-4 have more proliferative activities.