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Biomedical subjects

T Velu

Publications and source records attributed to T Velu.

At least 55 records · Page 3Linked to original sources
PubMed1996

Loss of tumorigenicity and increased immunogenicity induced by interleukin-10 gene transfer in B16 melanoma cells.

Because interleukin-10 (IL-10) has potent immunosuppressive and anti-inflammatory properties and is produced by some cancers, we hypothesized that its production might play a role in carcinogenesis by inhibiting adequate antitumoral immune responses. To test this hypothesis, retroviral vectors containing the IL-10 cDNA were generated and used to infect B16F1 melanoma cells that were injected subcutaneously in syngeneic mice. Surprisingly, IL-10 gene transfer resulted in a loss of tumorigenicity that was proportional to the amount of IL-10 secreted. Histological analysis showed massive area of necrosis of these tumor cells, with infiltration of polymorphic inflammatory cells. Parental cells simultaneously implanted had decreased tumorigenicity only when mixed with IL10-producing cells, but not when injected contralaterally, suggesting that their eradication is mediated mostly by a local phenomenon. Host T lymphocytes and natural killer (NK) cells were involved in this eradication because IL-10-producing cells grew in nude mice and in CD8+ or NK-depleted mice. Finally, mice injected with IL-10-secreting cells developed an antitumoral systemic immune response able to protect them against a subsequent challenge with parental cells. These results demonstrate that, in some settings, IL10 may have in vivo immunostimulating and proinflammatory properties that need to be considered in its therapeutic development.

3T3 Cells↗
PubMed1995

In vitro transformation of murine pro-B and pre-B cells by v-mpl, a truncated form of a cytokine receptor.

v-mpl is a constitutively activated, truncated form of a cytokine receptor that has been transduced in a murine retrovirus, the myeloproliferative leukemia virus (MPLV). Expression of this oncogene results in the factor-independent proliferation of myeloid, erythroid, megakaryocytic, and mast precursor cells, which retain the ability to differentiate. However, no lymphoid disease was ever reported. To determine whether MPLV could infect and transform very early B cells and their precursors (BCPs), lymphoid long-term bone marrow cultures were infected with a helper-free MPLV. Within 3 wk after infection, highly proliferating BCPs could be isolated. These cells were able to clone spontaneously in semi-solid cultures, grown in the absence of feeder cell layer or exogenous growth factor and rapidly produced tumors after s.c. injection into synegic irradiated mice. In addition, MPLV transformation of pre-B cells led to the induction of an autocrine activity. Immunophenotypic and molecular analysis indicated that MPLV transformed early pro-B, pro-B, and pre-B cells, according to the expression of HSA, CD43, B220, Thy1, s-IgM and BP1 Ags, and to the rearrangements of Ig genes. Interestingly, MPLV-transformed BCPs expressed Mac1 Ag without acquiring further characteristics of macrophagic differentiation. Although the v-mpl cytoplasmic domain is devoid of tyrosine kinase consensus sequence, MPLV-transformed pre-B cells contained a major approximately 105-kDa tyrosine-phosphorylated protein that was not detected in uninfected cells or in cells transformed by the Abelson viral oncogene (v-abl). These results demonstrate that, like v-abl, the truncated cytokine receptor v-mpl is able to transform BCPs in vitro and suggest that the oncogenic transformation of BCPs by either v-mpl or v-abl use different pathways.

Animals↗
PubMed1995

Interleukin-10 differentially regulates B7-1 (CD80) and B7-2 (CD86) expression on human peripheral blood dendritic cells.

Most of the immunosuppressive effects of interleukin-10 (IL-10) are related to functional inhibition of antigen-presenting cells (APC). Herein, we investigate the influence of recombinant (r)IL-10 on human dendritic cells (DC) purified from peripheral blood of healthy volunteers. First, we found that rIL-10 inhibited in a dose-dependent manner the proliferative responses as well as the production of IL-2 and interferon-gamma (IFN-gamma) in mixed lymphocyte reaction (MLR) between purified T cells and DC. This rIL-10 effect could be attributed to a direct effect on DC, as DC preincubated with rIL-10 were found to be deficient in the induction of alloreactive T cells even when anti-IL-10 neutralizing mAb was added at the time of MLR. Flow cytometric analysis indicated that rIL-10 did not modify the expression of ICAM-1 (CD54) and B7-1 (CD80), but decreased HLA-DR and B7-2 (CD86) expression at the DC surface. We conclude that the inhibitory effect of rIL-10 on primary alloreactive T cell responses involves down-regulation of class II MHC and B7-2 expression at the DC surface.

Antigens, CD↗
PubMed1995

Interleukin 10 prevents necrosis in murine experimental acute pancreatitis.

BACKGROUND/AIMS: Inflammatory events are believed to play an important role in the pathogenesis of acute pancreatitis. Interleukin 10 (IL-10) recently emerged as a major anti-inflammatory cytokine, inhibiting the secretion of proinflammatory cytokines by monocytes and/or macrophages. The potential protective role of IL-10 in a model of acute necrotizing pancreatitis in mice was tested. METHODS: Animals received two intraperitoneal injections of either 1000 U recombinant IL-10 or control supernatant before and during induction of acute pancreatitis with repeated cerulein injections (seven intraperitoneal injections of 50 micrograms/kg at hourly intervals). RESULTS: Systemic amylase and lipase release peaked 9 hours after the first cerulein injection. This peak was significantly reduced by IL-10 treatment. Histologically, edema and inflammation of the pancreas were observed in both groups, whereas necrosis was dramatically reduced in IL-10-treated animals. Serum tumor necrosis factor levels were undetectable in this model; reverse-transcriptase polymerase chain reaction analysis of resected pancreatic tissues performed at the time of maximal morphological alterations showed a dramatically decreased expression of tumor necrosis factor alpha messenger RNA after IL-10 treatment compared with control pancreatitis. CONCLUSIONS: IL-10 is able to decrease the severity of experimental acute pancreatitis, mainly by inhibiting the development of acinar necrosis. Inhibition of local tumor necrosis factor alpha might explain, at least in part, the protective effect of IL-10.

Acute Disease↗
PubMed1995

Spontaneous and cycloheximide-induced interleukin-10 mRNA expression in human mononuclear cells.

Interleukin-10 (IL-10) is known to be spontaneously produced by human peripheral blood mononuclear cells. In order to define the cell type in which IL-10 gene is spontaneously expressed we used the reverse polymerase chain reaction for IL-10 mRNA expression, which was also used to study the effects of cycloheximide (CHX). First, we found that IL-10 mRNA is spontaneously expressed in monocytes and B cells but not T cells from healthy donors, and second, we demonstrated that CHX superinduces IL-10 mRNA in monocytes and B cells. Experiments including nuclear run-on analyses established that the effects of CHX on IL-10 gene expression involve both gene transcription and mRNA stabilization.

B-Lymphocytes↗
PubMed1995

A case of pleomorphic T-cell lymphoma with a high content of reactive histiocytes presented with hypereosinophilia.

A case of peripheral T-cell lymphoma classified, according to the updated Kiel classification, as a large pleomorphic T-cell lymphoma with a high content of reactive histiocytes and blood hypereosinophilia is reported. Light microscopic examination revealed a diffuse effacement of the lymph node structure by large pleomorphic lymphoma cells mixed with eosinophils and many histiocytes, some of them presenting discrete features of hemophagocytosis. The neoplastic cells were CD3, CD5, CD8 and HLA-DR positive but failed to show CD30 antigen. DNA molecular analysis displayed simultaneous rearrangements of the genes coding for the delta chain of the T-cell receptor and for the Ig heavy chain. Increased serum levels of angiotensin converting enzyme and ferritin were found and probably induced by the reactive histiocytes. Immunoassays (ELISA) with antibodies directed against some cytokines and against the Tac peptide (sIL-2R) were performed. They demonstrated high serum levels of sIL-2R and a slight increase in GM-CSF, but neither IL-5 nor IL-3. The association of blood hypereosinophilia and histiocytic hyperplasia with a peripheral T-cell lymphoma is discussed.

Adult↗
PubMed1995

Absence of Epstein-Barr virus in medullary carcinoma of the breast as demonstrated by immunophenotyping, in situ hybridization and polymerase chain reaction.

Medullary carcinoma of the breast is an epithelial malignant proliferation that shares many characteristics (macroscopic, microscopic, epidemiologic, and prognostic) with lymphoepithelioma-like carcinomas of various sites. The authors hypothesized that they could also share the same etiologic agent, the Epstein-Barr virus (EBV). Epstein-Barr virus, a virus of the herpesvirus family, is to be associated with lymphoepithelioma-like carcinomas of the nasopharynx, stomach, lung, thymus, and salivary gland. Therefore, the authors looked for the virus in a series of 10 medullary carcinomas of the breast. Using immunohistochemistry, in situ hybridization and polymerase chain reaction, this investigation failed to show evidence of EBV. Similar negative results have been reported in lymphoepithelioma-like carcinomas arising in the skin and in the uterine cervix, which like the breast do not originate in the foregut. These results suggest that the pathogenesis of these tumors is not unique, implicating probably different etiopathogenic entities.

Base Sequence↗
PubMed1995

[Chorioretinal lymphoproliferative disorder induced by Epstein-Barr virus in lung transplantation].

The Epstein-Barr virus (EBV) is the causative factor of the posttransplant lymphoproliferative syndromes. Some ocular cases were described. We report the case of a lung-transplanted 59 year old man who presented a chorioretinal lymphoproliferative syndrome. A B-cell monoclonality and numerous EBV genome copies were demonstrated in vitreous material by PCR. We suspect an intermediate stage between polyclonal lymphoproliferative syndrome and malignant lymphoma. A treatment with nucleoside analogs and immunosuppression decrease was successful. The positive clinical evolution was associated with a reduction of the EBV genome quantity.

Chorioretinitis↗
PubMed1994

[Genes, heredity and colorectal cancer].

All cancers result from the accumulation of mutations of proto-oncogenes and tumor suppressor genes. Sporadic and familial colorectal cancers result from the accumulation of the following genes, in a relatively stereotyped chronological order: the tumor suppressor gene apc whose mutations are responsible for the familial adenomatous polyposis; the proto-oncogene K-ras which is mutated in 50% of large adenomas (> 1 cm) and adenocarcinomas; the tumor suppressor gene dcc; and the tumor suppressor gene p53 whose inactivation in a factor of bad prognosis. While some of them are induced by mutagens, others result from an instability of the genome. Two types of instability are observed in both sporadic and familial colorectal cancer. The first type, which is found in 25-50% of cases, appears as cytogenetic abnormalities with aneuploidy and allelic losses. The second type of instability is induced by mutations of the hMSH2 or hMLH1 genes which code for proteins involved in the mechanism of DNA repair.

Chromosome Deletion↗
PubMed1994

Modulation of the release of cytokines and reduction of the shock syndrome induced by anti-CD3 monoclonal antibody in mice by interleukin-10.

Since IL-10 was recently shown to inhibit several T cell functions in vitro, we investigated the effects of IL-10 on the cytokine release syndrome induced in mice by the 145-2C11 anti-CD3 mAb. As OKT3 in man, this mAb induces a massive polyclonal T cell activation before to induce immunosuppression. First, we found that administration of 1000 U of recombinant mouse IL-10 (mIL-10) 30 min before injection of 10 micrograms of the 145-2C11 antimouse CD3 mAb markedly reduced the systemic release of IFN-gamma and TNF. In contrast, IL-10 pretreatment did not significantly modify the release of IL-6. To determine the effect of IL-10 pretreatment on the endogenous secretion of IL-10 induced by the 145-2C11 mAb, mice were injected with human IL-10 (hIL-10) which does not cross-react in the ELISA for mIL-10 determination. While hIL-10 was as efficient as mIL-10 in reducing TNF and IFN-gamma release, it did not modify peak serum levels of IL-10. The modulation of cytokine production by mIL-10 was associated with a significant reduction of the toxicity of the 145-2C11 mAb, as assessed by the attenuation of hypothermia and by the reduced lethality in D-galactosamine-sensitize mice. We conclude that IL-10 differentially regulates the in vivo production of cytokines and decreases the systemic toxicity induced by the 145-2C11 mAb. These observations suggest potential therapeutic applications of IL-10 in organ transplantation, especially in association with anti-CD3 mAb.

Animals↗
PubMed1994

B7/CD28-dependent IL-5 production by human resting T cells is inhibited by IL-10.

We analyzed the effects of rIL-10 on IL-5 production by human resting T cells isolated from peripheral blood. Resting T cells of healthy individuals required activation for 48 h with either anti-CD3 mAb cross-linked on B7/CD32-transfected mouse fibroblasts or PMA in conjunction with anti-CD28 mAb for optimal IL-5 secretion. In each condition, IL-5 secretion measured by ELISA was inhibited in a dose-dependent manner by rIL-10, whereas IFN-gamma production was not suppressed. The inhibitory effect of rIL-10 on IL-5 synthesis induced by PMA and anti-CD28 mAb was also observed at the mRNA level. In contrast with its action on T cells costimulated by B7/CD28 signaling, rIL-10 did not block IL-5 secretion in response to PMA and A23187 calcium ionophore. The inhibition of IL-5 production by rIL-10 was not due to IL-2 deprivation because it was not modified by the addition of exogenous rIL-2. Moreover, cyclosporin A, which inhibited IL-2 more efficiently than rIL-10 in response to anti-CD3 mAb and B7/CD32 transfected fibroblasts, did not reduce and even enhanced IL-5 production. Finally, we analyzed the influence of endogenously produced IL-10 on IL-5 secretion by T cells stimulated by PMA and anti-CD28 mAb. Addition of a neutralizing anti-IL-10 mAb increased IL-5 release in this system, indicating that endogenous IL-10 controls IL-5 production. We conclude that both rIL-10 and endogenous IL-10 inhibit IL-5 production by T cells costimulated by B7/CD28 signaling.

Animals↗