Facilitated Engraftment of Isolated Islets Coated With Expanded Vascular Endothelial Cells for Islet Transplantation.

BACKGROUND: Diabetes is complex disease, which involves primary metabolic changes followed by immunological and vascular pathophysiological adjustments. However, it is mostly characterized by an unbalanced decreased number of the ß-cells unable to maintain the metabolic requirements and failure to further regenerate newly functional pancreatic islets. The objective of this study was to analyze the properties of the endothelial cells to facilitate the islet cells engraftment after islet transplantation. METHODS: We devised a co-cultured engineer system to coat isolated islets with vascular endothelial cells. To assess the cell integration of cell-engineered islets, we stained them for endothelial marker CD31 and nuclei counterstained with DAPI dye. We comparatively performed islet transplantations into streptozotocin-induced diabetic mice and recovered the islet grafts for morphometric analyses on days 3, 7, 10, and 30. Blood glucose levels were measured continuously after islet transplantation to monitor the functional engraftment and capacity to achieve metabolic control. RESULTS: Cell-engineered islets showed a well-defined rounded shape after co-culture when compared with native isolated islets. Furthermore, the number of CD31-positive cells layered on the islet surface showed a direct proportion with engraftment capacities and less TUNEL-positive cells on days 3 and 7 after transplantation. CONCLUSIONS: We observed that vascular endothelial cells could be functional integrated into isolated islets. We also found that islets that are coated with vascular endothelial cells increased their capacity to engraft. These findings indicate that islets coated with endothelial cells have a greater capacity of engraftment and thus establish a definitely vascular network to support the metabolic requirements.

1236 C/T and 3435 C/T polymorphisms of the ABCB1 gene in Mexican breast cancer patients.

MDR1, which is encoded by the ABCB1 gene, is involved in multidrug resistance (hydrophobic), as well as the elimination of xenotoxic agents. The association between ABCB1 gene polymorphisms and breast cancer risk in different populations has been described previously; however, the results have been inconclusive. In this study, we examined the association between polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene and breast cancer development in Mexican women according to their menopausal status and molecular classification. Molecular subtypes as well as allele and genotype frequencies were analyzed. A total of 248 women with initial breast cancer diagnosis and 180 ethnically matched, healthy, unrelated individuals were enrolled. Polymerase chain reaction-restriction fragment length polymorphism was performed to detect polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene. Premenopausal T allele carriers of the 3435 C/T polymorphism showed a 2-fold increased risk of breast cancer with respect to the reference and postmenopausal groups, as well as triple-negative expression regarding the luminal A/B molecular subrogated subtypes. In contrast, the CT genotype of the 1236 polymorphism was a protective factor against breast cancer. We conclude that the T allele carrier of the 3435 C/T polymorphism in the ABCB1 gene in combination with an estrogen receptor-negative status may be an important risk factor for breast cancer development in premenopausal women.

Association between polymorphisms in the thymidylate synthase gene and risk of breast cancer in a Mexican population.

Breast cancer (BC) is the leading cause of cancer-related deaths among women in Mexico. Two single-nucleotide polymorphisms (SNPs) in the thymidylate synthase (TS) gene, the 28-base pair (bp) tandem repeat in the TS 5'-untranslated enhanced region (TSER) and the 6-bp insertion/deletion in the TS 3'-untranslated region (TS 3'-UTR), increase the rate of misincorporation of uridylate into DNA and may lead to chromosomal damage. We examined the association between these polymorphisms and BC risk in Mexican women according to menopause status. Mexican patients with initial BC diagnosis (N = 230) and 145 individuals from a reference general population group (RGP) were included. For statistical analysis, the BC group was divided into pre- and post-menopause groups (PRE and POST groups, respectively). We analyzed both TS polymorphisms (TSER and TS 3'-UTR) using polymerase chain reaction. Finetti analysis was used to evaluate inter-and intra-group differences. The results showed a high frequency for the 3R and ins6 alleles in the BC, RGP, PRE, and POST groups. No significant differences were observed for the TS and TSER genotype and allele frequency distributions between groups. We found that the TSER and TS 3'-UTR SNPs are not associated with BC risk in Mexican patients.

Associations of killer cell immunoglobulin- like receptor genes with rheumatoid arthritis.

OBJECTIVE: Rheumatoid Arthritis (RA) is an autoimmune and chronic inflammatory disease of unknown etiology. Killer cell immunoglobulin-like receptors are expressed on the surface of natural killer cells and CD28null T-cells, both present in synovial membrane of RA. Therefore we evaluated the associations of KIR genes with RA. METHODS: 16 KIR genes were genotyped in 100 healthy subjects (HS) and 100 RA patients from Western Mexico using PCR-SSP. Differences in KIR genotypes and gene frequencies were assessed using the X^{2} test. RESULTS: Gene frequency of KIR2DL3 was lower in RA than in HS (p= 0.0019), whereas KIR2DL2 and KIR2DS2 were higher in RA than HS (p =0.0004 and p = 0.0487, respectively). In addition were identified 38 genotypes (from G1-G38) in both studied groups, and the genotype frequencies of G1, G6 and G14 showed significant differences (p =0.0001, p =0.0208 and p =0.0300, respectively). CONCLUSIONS: The presence of KIR2DL2, KIR2DS2 and absence of KIR2DL3 are associated with RA. Moreover, two genotypes BX are associated with RA. These results suggest that KIRs can be involved in RA susceptibility.

Endothelial cells promote pancreatic stem cell activation during islet regeneration in mice.

OBJECTIVES: Diabetes is the clinical consequence of the loss of the majority of the ß-cell population and failure to regenerate new pancreatic ß cells. The current therapies based on ß-cell replacement have failed to achieve ß-cell renewal and thus, long-term insulin freedom. We have hypothesized that early rejection of endothelial elements within the islet grafts may seriously hamper islet regeneration in both native and islet grafts. METHODS: In the present study, we analyzed the role of endothelial cells to activate pancreatic stem cells during islet regeneration. Mice were pretreated with or without endothelial pharmacological ablation of endothelial cells, followed by an acute ß-cell injury using a single intraperitoneal injection of streptozotocin. We performed comparative morphometric analyses of recovered pancreata on days 3, 7, 10, and 30 after streptozotocin injury, staining with bromodeoxyuridine (BrdU) for representative cell types, ß cells, endothelial elements, and stem cells. Blood glucose levels were measured continuously after the injury to monitor the capacity for metabolic control. RESULTS: Morphometric analyses revealed an increasing number of cells over time to be stained with a stem cell and BrdU markers among animals only injured with streptozotocin but not with endothelial ablation. Notably, on day 10, stem cell markers were dramatically decrease nearly to basal levels, with appearance of numerous insulin-positive cells. Intact vessels with cobblestone-shaped endothelial elements were observed in direct proportion to the better outcomes, both by morphometric and by metabolic parameters. In contrast, fewer insulin-positive cells were observed in pancreata that had been ablated of endothelial cells showing extensive collapse of endocrine functions. CONCLUSIONS: We observed that endothelial elements promoted stem cell proliferation and islet regeneration after a ß-cell insult. We believe that preservation of endothelial cells positively affects the process of pancreatic regeneration.

Caspase 3 blocking avoids the expression of autoantigens triggered by apoptosis in neonatal Balb/c mice skin.

OBJECTIVE: To assess the effect of caspase 3 inhibition, in the expression of intracellular antigens induced by apoptosis. MATERIAL AND METHODS: Skin explants of neonatal Balb/c mice were used to assess the autoantigen expression. Skin was obtained by punch biopsies, tissues were cultured in DMEM; cell death was induced by chemicals and assessed by TUNEL. The expression of La, Ro, Sm, RNP, Cajal Bodies and NuMa antigens were monitored by immunohistochemistry using autoantibodies or monoclonal antibodies against these antigens. RESULTS: Chemicals used to induce cell death, successfully produced apoptosis or necrosis in more than 60% of keratinocytes, and viability was significantly decreased when it was compared with those in controls. An increased expression of all skin intracellular antigens in skin biopsies treated with chemicals, major antigenic expression was detected with anti-La and anti-Ro antibodies. The caspase 3 inhibitor DEVD-CMK significantly decreased the expression of antigens induced by chemicals. CONCLUSION: By this result we can infer that caspase inhibitors modify apoptosis and decrease the autoantigens associated to cell death.

Intracellular antigens released from Balb/c mice kidneys under chemically induced apoptosis and/or necrosis.

The present investigation assesses the possible role of apoptosis and necrosis in intracellular antigen exposure of kidneys from Balb/c mice. Renal tissues were cultured and treated with chemicals to induce apoptosis and /or necrosis. The expression of intracellular antigens Sm, RNP, Ro and La were monitored with antibodies against these antigens. Main results confirm that renal intracellular antigens are released and exposed onto the surface of apoptotic and necrotic cells, therefore these antigens become an easy target of autoantibodies. This mechanism may be important in the lupus nephritis pathogenesis.

Addiction of anti-CD28 antibodies restores PBMC proliferation and IFN-gamma production in lepromatous leprosy patients.

During antigen recognition, T lymphocytes are primed by a physical interaction with antigen-presenting cells (APC). At least two signals are needed to activate T cells. One is provided by T cell receptor (TCR)/CD3 in the context of the mayor histocompatibility complex (MHC), and another signal is mediated by antigen-independent molecules, that is T cell membrane-bound CD28 and its specific ligand B7-1 (CD80) present in APC. Both signals trigger a series of metabolic events initiating right at the cell membrane and ending with activation and proliferation of T cells as well as specific cytokines synthesis. Our main goal was to determine whether deficiency in interferon-gamma (IFN-gamma) production shown by peripheral blood mononuclear cells (PBMC) from lepromatous leprosy (LL) patients, could be overcome by reconstituting in vitro the appropriate signals (by means of addition of anti-CD28 and anti-CD80 monoclonal antibodies). We also determined the stimulation index (SI) in the same PBMC. Our results demonstrated no significant differences in CD80 expression monocytes and B lymphocytes from LL patients when compared with healthy subjects. Nonetheless, CD28 expression significantly decreased in lymphocytes from LL patients (p < 0.01). Regarding IFN-gamma levels and SI, LL-PBMC failure before mitogenic stimuli could be reversed by further incubation with anti-CD28 antibody, but stimulation by specific antigen of Mycobacterium leprae was not changed. Addition of anti-CD80 antibody significantly increased IFN-gamma levels in phytohemagglutinin (PHA)-stimulated PBMC, although proliferation deficiency persisted. Cells stimulated with specific antigen did not modify either their proliferation or IFN-gamma levels.

Urokinase-type plasminogen activator and plasminogen activator inhibitors (PAI-1 and PAI-2) in extracts of invasive cervical carcinoma and precursor lesions.

In a previous study we reported a direct correlation between the degree of total proteolytic activity and the natural history of cervical carcinoma. The present work examined whether an increase in the urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitors (PAIs) is correlated with the natural history of cervical carcinoma. We measured uPA and PAI-1 activities and uPA, PAI-1 and PAI-2 antigen concentrations in cervical extracts from normal, squamous intraepithelial lesions (SIL) or invasive carcinoma patients. The uPA activity in invasive carcinoma extracts was 8.46 times that of normal extracts and 4.9 times that of SIL extracts. The PAI-1 activity in invasive carcinoma extracts was 1.3 times that of normal extracts and 1.24 times that of SIL extracts. uPA, PAI-1 and PAI-2 amounts were 25.7-, 12.1- and 7.9-fold higher, respectively, in invasive carcinoma than in SIL, and 39.1-, 21.38- and 27.3-fold higher, respectively, than in normal extracts. uPA and PAI-1 activities were 2.02- and 1.42-fold higher in extracts from patients with stages II-IV than those from stage I extracts, respectively. uPA, PAI-1 and PAI-2 amounts were 3.06-, 4.2- and 1.4-fold higher in extracts from patients with stages II-IV than those from stage I extracts, respectively. The increase in uPA activity and the antigen levels of uPA and PAIs (PAI-1 and PAI-2) in stages II-IV of invasive carcinoma of the cervix suggests that these components play an important role in invasion and metastasis in advanced stages of this tumour.

Enhanced functional capacity of the peritoneal macrophages as antigen presenting cells after aclacinomycin treatment in mice.

Aclacinomycin (ACM) is an oncostatic of the anthracycline family, largely used in patients and experimentally in mice. ACM has been reported to enhance phagocytosis, secretion of free oxygen radicals and of interleukin 1. Its injection is also followed by an increase of the cytotoxic and cytostatic activity of murine peritoneal macrophages. In the present work we investigated whether ACM modifies the antigen-presenting cell capacity of murine peritoneal macrophages. Purified T lymphocytes were cultured with peritoneal macrophages from either normal or ACM treated mice (4 mg/kg day -4) which were previously incubated with phytohemagglutinin. The T cell proliferative response was greater in cultures with normal macrophages, indicating that macrophages from ACM-treated mice had a better antigen presenting activity than normal untreated macrophages.

L-5178-Y lymphoma associated immunosuppression in Balb/c mice.

Lymphoma L-5178-Y bearing Balb/c mice were unable to mount a delayed-type hypersensitivity reaction to dinitrofluorobenzene (DNFB). A suppressor factor present in the ascitis of these mice inhibited the response if given during DNFB sensitization, but not during challenge. The factor was not present in lymphoma-bearing Balb/c nu/nu mice. It appeared to be a 35-66 kDa protein. Non-specific esterase staining indicated that the spleens of tumor-bearing and ascitis-injected mice contained a large excess of macrophages. Our observation that the suppressor factor prevented the very start of the immune response may indicate why immunostimulation is difficult to obtain in cancer bearing hosts.

Proteolytic activity in extracts of invasive cervical carcinoma and precursor lesions.

In this preliminary report, we showed that proteolytic activity of extracts from 85 cervical samples of patients with normal cervix, low and high-grade squamous intra-epithelial lesions and invasive carcinoma, increased according to the natural history of the cervical cancer when measured with three different substrates. Inhibitor assays for four different catalytic classes of endopeptidases indicated that the predominant catalytic class in extracts of all groups was that of metalloproteinases. Substrate gel electrophoresis revealed that invasive carcinoma extracts had two bands with proteolytic activity (with M(r) of 72 and 52 kDa) which were not present in normal tissue or biopsies with precursor lesions. Immunological and molecular characterization of these bands may provide information relevant to cervical cancer biology and clinical applications.