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V Colizzi

Publications and source records attributed to V Colizzi.

At least 55 records · Page 3Linked to original sources
PubMed1995

Interaction of HIV-1 gp120 molecule fragments with human monocytes: different requirements for tumor necrosis factor-alpha and IL-6 production.

The HIV-1 gp120 recombinant protein fragment encompassing aa residues 410-511, that contains the CD4 binding region (rp120cd), and fragment aa 446-511, which lacks the sequence responsible for CD4 binding (rp120), were synthesized to study their ability to induce TNF synthesis in human monocytes. The rp120cd stimulated TNF alpha secretion by monocytes while the rp120 and full-length recombinant protein (FL gp120), used as control, failed to do so. However, FL gp120 stimulated peripheral blood mononuclear cells (PBMC) and lymphocytes for TNF production and this was inhibited by anti-CD4 MAb. The rp120cd also caused TNF secretion by PBMC that was not blocked by this antibody. Furthermore, FL gp120 but not rp120cd inhibited anti-CD4 mAb binding to CEM cells. Hence, FL gp120 may cause TNF release from lymphocytes by binding to CD4, while rp120cd interacts with monocytes but not lymphocytes and induces TNF production by a mechanism not involving CD4 binding. Unexpectedly, FL gp120 but not rp120cd stimulated IL-6 secretion and IL-6 mRNA synthesis in monocytes. The FL gp120-induced production of IL-6 by monocytes was inhibited by anti-CD4 monoclonal antibody (MAb). Thus, there may be different requirements for TNF induction in lymphocytes and monocytes stimulated with various preparations of gp120 and for the selective induction of cytokines in monocytes. The enhanced production of TNF in HIV infection and AIDS may involve distinct cellular sources and different mechanisms.

Antibodies, Monoclonal↗
PubMed1995

Characterization of human pancreatic adenocarcinoma cell line with high metastatic potential in SCID mice.

The CD44 molecule and CD44 isoforms are expressed on some malignant tumours and it has been suggested that their expression may correlate with tumour spread. Human pancreatic carcinoma cell line (HPC-4) expressing CD44 was established from a patient with adenocarcinoma of pancreas. This line showed a rapid growth in vitro, several chromosome abnormalities and surface expression of some adhesion molecules (ICAM-1, LFA-3, beta 1-chain of VLA integrins, VNR). Xenotransplanted HPC-4 cells were able to grow rapidly in SCID mice as subcutaneous tumour, leading to 100% mortality within 3-5 weeks when 1 x 10(5)-1 x 10(7) cells were inoculated. Spontaneous metastases in the liver, lung, spleen and kidney of SCID mice were observed. Interestingly enough, HPC-4 cells in vivo and ex vivo also expressed HLA-DR molecules, but these were rapidly lost upon culture in vitro. It is suggested that the appearance of HLA-DR may be the result of interaction of the tumour with a local environment of the host, while CD44 expression may explain the rapid growth and occurrence of distant metastases in SCID mice. The ability of HPC-4 cells to form spontaneous metastases in SCID mice may prove to be a potentially interesting model of human carcinoma for testing new treatment modalities.

Adenocarcinoma↗
PubMed1994

HIV-1 gp120-dependent induction of apoptosis in antigen-specific human T cell clones is characterized by 'tissue' transglutaminase expression and prevented by cyclosporin A.

We investigated the effect of cyclosporin (CsA) on HIV-gp120-dependent induction of cell death by apoptosis of human T cell clones specific for influenza virus haemagglutinin and restricted by HLA-DR1. Preincubation of the clones with gp120 induced a large inhibition of their proliferation which was paralleled by the induction of apoptosis. Exposure to the specific antigen alone was able to trigger apoptosis in a significant fraction of cells, this effect was potentiated by pretreatment with gp120. Apoptosis was characterized by the typical morphological changes and by the expression of 'tissue' Transglutaminase (tTG), one of the few characterized effector elements of programmed cell death. Interestingly, the tTG protein induction was detectable within the first 24 hours following the gp120 treatment and preceded the appearance of the typical apoptotic phenotype. Noteworthy, CsA treatment prevented the gp120-dependent induction of apoptosis by blocking the activation of the Ca(2+)-dependent effector elements such as tTG.

Apoptosis↗
PubMed1994

The MHC class-II and CD44 molecules are involved in the induction of tumour necrosis factor (TNF) gene expression by human monocytes stimulated with tumour cells.

Tumour necrosis factor alpha (TNF) mRNA is detected in the macrophage infiltrate surrounding the tumour, but the cellular/molecular interactions leading to TNF gene expression in macrophages are unknown. The in vitro system in which human blood monocytes are stimulated with human cancer cells for TNF release was used to study such interactions. Monoclonal antibodies (MAbs) against various adhesion molecules (LFA-1, LFA-3, ICAM-1, VNR, VLA beta I chain) were unable to block TNF production in co-culture of monocytes with a human pancreatic carcinoma (HPC) cell line. However, anti-CD44 and anti-HLA-DR MAbs effectively blocked TNF release and TNF-mRNA induction in monocytes. Pre-incubation of monocytes with anti-HLA-DR and tumour cells with anti-CD44 MAbs had a similar effect. It was concluded that CD44 molecules are involved in tumour-monocyte interactions and that HLA-DR determinants of monocytes are engaged in signal transduction for TNF gene activation. These findings may suggest that certain surface determinants of tumour cells act as ligands for MHC class-II molecules and induce TNF production in monocytes.

Antibodies, Monoclonal↗
PubMed1994

CD4-8- T-cells increase in MRI/lpr mice treated with thymic factors.

The in vivo effect of thymic factors on immature lymphocytes was analysed in MRL/lpr mice. This strain carries a genetic defect that causes during their life cycle a block of T-cell differentiation and abnormal proliferation of CD4-8- (double-negative, DN) T-lymphocytes. In vivo administration of four preparations of thymic factors, thymopentin (TP-1), thymopoietin (TP-5), thymolymphotropin (TLT), and thymomodulin (TMD) into young (2-month-old) MRL/lpr mice induced a significant increase of DN T-cells both in the thymus and in the peripheral lymph nodes, with a concomitant decrease of double-positive (DP) T-cells in the thymus and of single-positive (SP) T-cells in the lymph nodes. The level of DNA fragmentation measured as propidium iodide fluorescence was increased in the thymus population of young mice and in the lymph node population of old mice treated with TLT. SCID mice transplanted with lymph node cells from MRL/lpr donors (MRL-->SCID) developed graft versus host (GvH) reaction due to the activation of MRL CD8+ alloreactive T-cells. This model was used to analyse the effect of TMD/TLT in vivo on MRL cell proliferation and expansion; in fact, spleen cells from MRL-->SCID mice after treatment with TMD/TLT showed an increased cell proliferation, and an expansion of DN T-cells with a concomitant decrease of SP cells (both CD4+ and CD8+ cells). Decreased SP cell numbers in this context could explain why TMD/TLT treatment of SCID mice engrafted with MRL cells increased their survival compared to untreated MRL-->SCID mice.

Animals↗
PubMed1994

Modulation of antigen-presenting capacity of human monocytes by HIV-1 GP120 molecule fragments.

The two fragments of HIV-1 gp120 molecule were synthesized to study their interaction with human monocytes. Previous observations indicated that recombinant gp120 fragment (aa residues 410-511) encompassing CD4 binding region (rp120cd) induced tumour necrosis factor alpha (TNF) production in monocytes, while a similar fragment (rp120) not containing the CD4 binding sequence (aa 446-511) was inactive. This paper shows that rp120cd depressed monocyte ability to present antigen (PPD) to autologous T lymphocytes while rp120 was noninhibitory. The rp120cd interacted with monocytes but not T lymphocytes. Anti-TNF receptor type A antibody (utr-1) prevented the depression of antigen presentation caused by rp120cd, which suggested a role for TNF and its receptor. The depression of antigen presentation was seen only when monocytes were treated with rp120cd before, but not after, pulse with antigen. Parallel changes were observed in PPD-induced IL-6 production. Thus, induction of TNF by gp120 may be associated with impairment of antigen-presenting capacity of monocytes seen in AIDS patients.

Antigen Presentation↗
PubMed1994

Analysis of the adoptive transfer of delayed hypersensitivity and T cell repertoire in severe combined immunodeficiency mice reconstituted with human lymphocytes.

The functional capacity of human T cells to passively transfer delayed hypersensitivity (DH) was analysed in severe combined immunodeficiency (SCID) mice. The tissue distribution of human peripheral blood lymphocytes (PBL) was analysed by 51chromium labelling 1 and 24 h after intravenous cell injection. Labelled PBL from purified protein derivative (PPD)-positive healthy individuals mainly localize in the spleen, liver and lungs, with no arrival in the peripheral lymphoid organs and at the site of antigen challenge (footpad). According to such defective distribution, human PPD-immune cells failed to passively transfer PPD-specific DH to SCID recipients when cells were injected either intravenously or intraperitoneally (systemic transfer). On the contrary, PPD-immune cells were able to transfer DH to PPD when injected directly into the footpad (local transfer). Both memory (CD45RA-) and naive (CD45RA+) enriched subsets were equally able to transfer local DH. The long-term reconstitution of the human immune system in SCID mice was analysed after intraperitoneal PBL transfer (hu-PBL-Scid) by phenotypic analysis, immunoglobulin level, and human DNA detection. Moreover, the reconstitution of the V beta T cell receptor (TCR) repertoire in SCID mice was analysed by anchored polymerase chain reaction (PCR) showing that all the 22 V beta families were expressed in the spleen of hu-PBL-SCID mice. Moreover, scanner analysis of Southern blotting revealed the selective expansion of distinct V beta families (V beta 3, V beta 6, V beta 8, V beta 13.1, V beta 14, V beta 17), suggesting that human lymphocytes could recognize specific antigens or superantigens in the SCID environment.

Animals↗
PubMed1993

New concepts in AIDS pathogenesis.

The concept that HIV causes AIDS only by directly killing CD4 cells has been questioned by a number of investigators. There has been experimental support for a number of indirect mechanisms such as apoptosis, anergy, superantigen-induced cell proliferation and depletion, defective signaling, molecular mimicry, and autoimmunity. In this article we review the available evidence in support of these theories and suggest that in spite of their apparent differences, signaling by HIV through the T cell receptor could initiate the markedly different responses of activation, anergy, and apoptosis. However, the unifying mechanism as to how this is achieved remains unclear. It is likely that more than one of these mechanisms are involved in CD4 cell depletion during different phases of the disease. Understanding these mechanisms and their role in HIV pathogenesis would be important in new vaccine and therapeutic approaches.

Acquired Immunodeficiency Syndrome↗
PubMed1993

An algorithm for the identification of similar oligopeptides between amino acid sequences.

Molecular mimicry is the origin of common structural patterns in sequences of viral and host proteins, and it appears to be related to the development of autoimmune diseases. The identification of structural molecular similarities among viral and host proteins is thus very relevant in the development of engineered antiviral vaccines to avoid potentially dangerous effects. In this respect identifying pairs of similar oligopeptides between given proteins, independently of the overall degree of similarity of their amino acid sequences, is of interest. To this aim we have designed and implemented an algorithm capable of finding and classifying (with respect to their statistical significance) all possible pairs of similar oligopeptides between two proteins irrespective of length, number, location and ordering of the pairs along the sequences. The algorithm is very efficient and much more suited for this kind of local search than standard alignment programs. The latter, dealing with the sequences as a whole, are, in these cases, of very limited applicability. We have used the algorithm to compare a glycoprotein of the human immunodeficiency virus (HIV) type 1 and with the beta-chains of human leukocyte antigen (HLA). Besides a previously identified peptide, we have found a new peptide located in the fusion site of HIV that shares high similarity with the transmembrane domains of HLA.

Algorithms↗
PubMed1993

Epitope specificity, antibody-dependent cellular cytotoxicity, and neutralizing activity of antibodies to human immunodeficiency virus type 1 in autoimmune MRL/lpr mice.

The specificity and functional activity of antibodies to human immunodeficiency virus (HIV) in the sera of MRL/lpr mice were analyzed by peptide-ELISA, antibody-dependent cellular cytotoxicity, and virus neutralization. The specificity of the antibodies in the sera of autoimmune MRL/lpr mice was similar to that of HIV-infected persons; the mouse sera specifically recognized the V3 loop of gp120 and immunodominant regions of gp41 and p24. Moreover, such binding was inhibited both by human HIV-positive sera and by soluble peptides in competition experiments. MRL/lpr sera displayed anti-HIV antibody-dependent cellular cytotoxicity using human peripheral blood lymphocytes as effector cells and HIV-infected H9 cells. Furthermore, the fact that MRL/lpr sera neutralized in vitro infectious HIV (both strains IIIB and MN) suggests these antibodies recognize viral epitopes on the membrane of infected T cells.

Amino Acid Sequence↗
PubMed1993

Characterization of an IS-like element from Mycobacterium tuberculosis.

A DNA sequence, present in members of the Mycobacterium tuberculosis complex, has been identified and characterized. The distribution of this DNA sequence among mycobacterial species was analysed by DNA hybridization and PCR experiments. As the sequence was detected only in bacteria belonging to the M. tuberculosis complex, it may be useful for the rapid discrimination of mycobacteria. Interestingly, the sequence has some characteristics of an insertion element (IS) and codes for a hypothetical protein with significant homologies to proteins encoded by several IS elements of other organisms, namely IS427 and IS869 from Agrobacterium tumefaciens, IS402 from Pseudomonas cepacia, Tn4811 from Streptomyces lividans and ISRm4 from Rhizobium meliloti. Together, these elements form a previously unrecognized family of transposable elements. This finding suggests the possibility of horizontal gene transfer between pathogenic mycobacteria and other organisms including Gram-negative plant-pathogenic bacteria.

Amino Acid Sequence↗
PubMed1993

DNA HLA-DRB1 analysis in children of positive mothers and estimated risk of vertical HIV transmission.

RFLP HLA-DRB1 analysis was performed on a total of 83 children born from HIV-infected mothers, 35 of whom were shown to be HIV-infected, while 48 reverted from seropositivity to seronegativity, indicating that they were not infected. Moreover, 89 healthy children were used as controls. It has been found that DRB1-14a and DRB1-13a.4 alleles were not present in the HIV-infected children, but were found in the sero-reverted (HIV-uninfected) children (in the proportion of 9.6 per cent and 5.3 per cent, respectively), and in the controls (5.6 per cent and 3.9 per cent, respectively). The possible correlation between DR and risk of HIV transmission from mother to baby was analysed considering every single allele, estimated by the ratio between the number of infected children and the number of all children born from seropositive mothers. There was also introduced a statistic G for the control of 'statistical validity' of data.

Alleles↗
PubMed1993

Augmented passive transfer of contact sensitivity in severe combined immunodeficiency mice and its dependence of V beta 8+ cells in the picryl system.

The passive transfer of contact sensitivity using picryl chloride immune cells from H-2 syngenic BALB/c donors was analyzed in severe combined immunodeficiency (SCID) mice which lack functional T and B lymphocytes. H-2-restricted and antigen-specific contact sensitivity was transferred to SCID mice, and comparison between the level of contact sensitivity and the number of transferred cells showed a significantly more efficient transfer to SCID than to BALB/c mice. The cells passively transferring contact sensitivity were shown to carry the V beta 8 phenotype. Moreover, chromium-labeled cells from BALB/c PC1-primed donors localize normally in peripheral lymphoid organs and an increased percentage of cell arrival in the ears is clearly observed in SCID after challenge with picryl chloride.

Animals↗
PubMed1993

Cytotoxic activity of human lymphocytes against differentiated intestinal tumour cell lines.

The natural killer (NK) and lymphokine-activated killer (LAK) cytotoxic activity of human peripheral blood lymphocytes (PBL) against various human tumour cell lines from intestinal origin (WIDR, HT29, Caco-2) has been investigated. The differentiated Caco-2 cells were then used as a model to investigate the cytotoxic activity against enterocyte-like target cells. Caco-2 were seeded on polycarbonate filters and maintained in culture for at least 15 days to allow the differentiation and formation of tight junctions. The integrity of tight junctions was assayed by measuring [3H]mannitol flux from apical to basolateral compartment. Cytotoxic analysis showed that both differentiated and undifferentiated Caco-2 cells were similarly susceptible to NK and LAK activity. The capacity of cytotoxic lymphocytes to kill enterocyte-like cells with intact junctional complex may suggest a direct role of cytotoxic lymphocytes in causing intestinal lesions under inflammatory conditions.

Cell Line↗
PubMed1992

Recognition and killing of tumour cells expressing heat shock protein 65 kD with immunotoxins containing saporin.

The expression of heat shock proteins (HSP) of the 65 kD family (groEL) has been observed by flow cytometry using murine monoclonal antibody (MoAb) anti-HSP 65 kD (ML30) on the surface of B (Daudi) or T (H9) lymphoma cells, on a monocyte cell line (U937) and also on a primary culture of a human pancreatic carcinoma (HPC). Moreover, the MoAb ML30 was coupled to Saporin 6, a ribosome-inactivating protein recovered from the seeds of Saponaria officinalis, to kill HSP-expressing cells with a specific immunotoxin. An indirect method using first MoAb ML30 and then anti-mouse IgG1 immunotoxin was also performed. With this method a human serum positive for HSP65-antibodies was tested using anti-human IgG1 or IgM immunotoxins. All cell lines were inhibited when preincubated with the specific immunotoxin directed to HSP65 (ML30 SO6), although H9 cells were susceptible to immunotoxin only after thermal stress. Daudi and HPC cells were inhibited both after long-term culture and when freshly explanted from SCID mice. Proliferation of the U937 monocytic cell line, that constitutively expresses high levels of HSP65 on the surface (as determined by flow cytometry), was completely inhibited (100% inhibition) by the ML30 SO6. However, not all tumour cells constitutively express high levels of surface HSP65, as determined by cytometric analysis. For this reason it was not always possible to obtain complete inhibition of cellular proliferation.

Animals↗