Growth hormone in the presence of laminin modulates interaction of human thymic epithelial cells and thymocytes in vitro

BACKGROUND: Several evidences indicate that hormones and neuropeptides function as immunomodulators. Among these, growth hormone (GH) is known to act on the thymic microenvironment, supporting its role in thymocyte differentiation. The aim of this study was to evaluate the effect of GH on human thymocytes and thymic epithelial cells (TEC) in the presence of laminin. RESULTS: GH increased thymocyte adhesion on BSA-coated and further on laminin-coated surfaces. The number of migrating cells in laminin-coated membrane was higher in GH-treated thymocyte group. In both results, VLA-6 expression on thymocytes was constant. Also, treatment with GH enhanced laminin production by TEC after 24 h in culture. However, VLA-6 integrin expression on TEC remained unchanged. Finally, TEC/thymocyte co-culture model demonstrated that GH elevated absolute number of double-negative (CD4-CD8-) and single-positive CD4+ and CD8+ thymocytes. A decrease in cell number was noted in double-positive (CD4+CD8+) thymocytes. CONCLUSIONS: The results of this study demonstrate that GH is capable of enhancing the migratory capacity of human thymocytes in the presence of laminin and promotes modulation of thymocyte subsets after co-culture with TEC.

Efeito da desnutriçäo protéica sobre a matriz extracelular da medula óssea de camundongos / Effect of the protein malnutrition on the extracellular matrix of the bone marrow of mices

As células sangüíneas originam-se da medula óssea através da célula tronco que sofre processo de proliferação, diferenciação e maturação no microambiente hematopoiético. O microambiente hematopoiético é uma estrutura altamente organizada composta de células estromais, moléculas da matriz extracelular (MEC) e citocinas. A desnutrição protéico-energética diminui a produção de células sangüíneas e interfere na defesa do organismo. Neste trabalho estudamos os efeitos da desnutrição protéica (dieta contendo 4 por cento de caseína) sobre a MEC da medula óssea em camundongos. Avaliamos a composição da MEC através de SDS-PAGE 7,5 por cento e Western blot para fibronectina (FN), laminina (LN) e trombospondina (TSP)...

Caracterização e implicações fisiológicas das interações da proteína prion celular com o seu receptor de 60-66 kDa e com a laminina / Caracterization and physiological implications of the cellular prion protein interactions with its 60-66 kDa receptor and with laminin

Prions são definidos como partículas protéicas infecciosas compostas, quase que exclusivamente, por uma proteína conhecida como prion scrapie (PrPsc). O envolvimento dessas partículas na etiologia de doenças neurodegenerativas, tanto em homens como em animais, já está bem determinado. Acredita-se que o PrPsc seja sintetizado através de modificações pós-traducionais que ocorreriam na isoforma celular da proteína prion (PrPc), uma glicoproteína expressa constitutivamente na superfície de vários tipos celulares, principalmente de neurônios, ancorada na membrana plasmática por glicosil-fosfatidil inositol (GPI). Apesar de ser uma molécula conservada em várias espécies, a função de PrPc ainda permanece desconhecida. Interessados nos possíveis papéis fisiológicos desempenhados pelo PrPc, decidimos investigar certas interações que o PrPc poderia realizar com outras moléculas, na tentativa de se encontrar pistas sobre a função dessa proteína em células normais...

biological significance of laminin and fibronectin in bladder cancer

Laminin [LnP1] and fibronectin [Fn] were estimated in the sera of 27 cases with bladder carcinoma of different histopathological types: Papillary superficial transitional cell carcinoma [TCC] [nine cases], invasive TCC [12 cases] and squamous cell carcinoma [six cases]. Only 18 patients were followed up after treatment. Ten normal individuals and 12 cases suffering from benign bladder lesions were included in the study for comparison. Serum LnP1 was significantly higher compared with controls in all groups except in the benign bladder lesions group. It was noticed that a progressive increase in the mean value of serum LnP1 accompanied a change in the grade of the disease. Tissue detection for LnP1 by immunoperoxidase revealed a continuous intact basement membrane [BM]. BM loss was directly proportional to the grade of bladder carcinoma. Serum Fn values revealed no significant difference compared with controls in all the studied groups. Fn immunoperoxidase staining showed negative or weak results in all the studied groups. Serum LnP1 may be a diagnostic and prognostic parameter in TCC after the exclusion of other diseases that increase its expression. It may also be used for monitoring and detecting the recurrence

Immunohistochemical detection of laminin in various breast lesions

The distribution of laminin, a structural glycoprotein specific for basement membranes, was studied in 52 breast lesions with antilaminin and the avidin-biotin peroxidase complex method. Laminin was observed within vascular and epithelial basement membranes. It displayed a continuous linear pattern in normal breast tissue, fibrocystic disease and in benign tumors. In malignant tumors, laminin was heterogeneously distributed, with a discontinuous linear pattern. No intracellular laminin staining was detected. Laminin may be a valuable aid in the differentiation between benign and malignant breast lesions. Absence of basement membrane and lack of the linear pattern of laminin at the boundaries of malignant ducts may be of value in exclusion of carcinoma in situ