Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0001175 (AIDS)
 120,706 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murine AIDS, induced by LP-BM5 murine leukemia retrovirus infection, causes a progressive and profound immunodeficiency in female C57B1/6 mice. Previously, we reported that autoantibodies were elevated during the initiation phases of this murine retrovirus infection and bound peptide determinants corresponding to CDR1 of several TCR V beta-chains. Therefore, we designed studies to determine whether administration of a major autoimmunogenic TCR V beta CDR1 peptide before or after infection with LP-BM5 retrovirus would modulate retrovirus-induced dysregulation of T cell function. Administration of the TCR V beta CDR1 peptide before murine retrovirus infection significantly prevented its suppression of splenic NK cell activity, T and B cell proliferation, and monokine (IL-6 and TNF-alpha) and Th1 cytokine (IL-2 and IFN-gamma) release by splenocytes, and inhibited retrovirus-induced elevation of Th2 cytokine (IL-5 and IL-10). Similar data were obtained with peptide immunization 2 wk after murine retrovirus infection at 6 and 16 wk postinfection. However, delaying peptide immunization until severe suppression of T and B cell mitogenesis had occurred did not restore their functions. Immunization with TCR V beta peptide prevents development of retrovirus-induced immune dysfunction, which suggests a possible pathogenic role of autoreactive T cells as regulatory elements.
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PMID:T cell receptor V beta complementarity-determining region 1 peptide administration moderates immune dysfunction and cytokine dysregulation induced by murine retrovirus infection. 763 74

Autoantibodies (AAbs) directed against particular segments of the variable region of TCR beta chains occur in normal humans and in certain autoimmune diseases, but the factors regulating the appearance of such antibodies are unknown. We report that AAbs binding a peptide determinant corresponding to the CDR1 of the V beta domain are elevated in C57BL/6 mice following infection with the LP-BM5 murine leukemia retrovirus mixture, a treatment used to induce murine AIDS. The elevation of the level of these AAbs is an early event following retroviral infection which corresponds in part to the general polyclonal activation of the B cells, but a selectivity for particular V beta sequences is apparent later. This suggests that the appearance of these antibodies may play a part in the subsequent development of immunodeficiency. Since the antibodies studied are of the IgG isotype, both T cells and B cells are involved in their elaboration.
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PMID:Production of IgG autoantibodies to TCRs in mice infected with the retrovirus LP-BM5. 771 13

Azole antifungal agents, and especially fluconazole, have been used widely to treat oropharyngeal candidiasis in patients with AIDS. An increasing number of cases of clinical resistance against fluconazole, often correlating with in vitro resistance, have been reported. To investigate the mechanisms of resistance toward azole antifungal agents at the molecular level in clinical C. albicans isolates, we focused on resistance mechanisms related to the cellular target of azoles, i.e., cytochrome P450(14DM) (14DM) and those regulating the transport or accumulation of fluconazole. The analysis of sequential isogenic C. albicans isolates with increasing levels of resistance to fluconazole from five AIDS patients showed that overexpression of the gene encoding 14DM either by gene amplification or by gene deregulation was not the major cause of resistance among these clinical isolates. We found, however, that fluconazole-resistant C. albicans isolates failed to accumulate 3H-labelled fluconazole. This phenomenon was reversed in resistant cells by inhibiting the cellular energy supply with azide, suggesting that resistance could be mediated by energy-requiring efflux pumps such as those described as ATP-binding cassette (ABC) multidrug transporters. In fact, some but not all fluconazole-resistant clinical C. albicans isolates exhibited up to a 10-fold relative increase in mRNA levels for a recently cloned ABC transporter gene called CDR1. In an azole-resistant C. albicans isolate not overexpressing CDR1, the gene for another efflux pump named BENr was massively overexpressed. This gene was cloned from C. albicans for conferring benomyl resistance in Saccharomyces cerevisiae. Therefore, at least the overexpression or the deregulation of these two genes potentially mediates resistance to azoles in C. albicans clinical isolates from AIDS patients with oropharyngeal candidiasis. Involvement of ABC transporters in azole resistance was further evidenced with S. cerevisiae mutants lacking specific multidrug transporters which were rendered hypersusceptible to azole derivatives including fluconazole, itraconazole, and ketoconazole.
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PMID:Mechanisms of resistance to azole antifungal agents in Candida albicans isolates from AIDS patients involve specific multidrug transporters. 858 12

C57BL/6 mice were injected with different doses of human T-cell receptor (TCR) V beta 8.1 CDR1 peptide at different times after murine retrovirus (LP-BM5) infection. Injection with TCR V beta 8.1 CDR1 peptide largely prevented the retrovirus-induced reduction in B- and T-cell proliferation, and T-helper 1 (Th1) cytokines [interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)] secretion. It also suppressed T-helper 2 (Th2) cytokines (IL-6 and IL-10) production, which was stimulated by retrovirus infection. These effects were accomplished using at least 100 micrograms of peptide per mouse and the most effective dose of peptide had to be given within 4 weeks after retrovirus infection. Immunization with doses above 100 micrograms/mouse as long as 4 weeks postinfection maintained natural killer (NK) cell activity during retrovirus infection. Reducing the dose of peptide or delaying it until the disease progressed towards early murine acquired immune deficiency syndrome (AIDS) allowed development of immune dysfunction. These studies provide data suggesting that immune dysfunction, induced by murine retrovirus infection, was largely prevented by TCR V beta CDR1 peptide injection.
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PMID:T-cell-receptor dose and the time of treatment during murine retrovirus infection for maintenance of immune function. 869 80

Some Candida albicans isolates from AIDS patients with oropharyngeal candidiasis are becoming resistant to the azole antifungal agent fluconazole after prolonged treatment with this compound. Most of the C. albicans isolates resistant to fluconazole fail to accumulate this antifungal agent, and this has been considered a cause of resistance. This phenomenon was shown to be linked to an increase in the amounts of mRNA of a C. albicans ABC (ATP-binding cassette) transporter gene called CDR1 and of a gene conferring benomyl resistance (BENr), the product of which belongs to the class of major facilitator multidrug efflux transporters (D. Sanglard, K. Kuchler, F. Ischer, J. L. Pagani, M. Monod, and J. Bille, Antimicrob. Agents Chemother. 39:2378-2386, 1995). To analyze the roles of these multidrug transporters in the efflux of azole antifungal agents, we constructed C. albicans mutants with single and double deletion mutations of the corresponding genes. The mutants were tested for their susceptibilities to these antifungal agents. Our results indicated that the delta cdr1 C. albicans mutant was hypersusceptible to the azole derivatives fluconazole, itraconazole, and ketoconazole, thus showing that the ABC transporter Cdr1 can use these compounds as substrates. The delta cdr1 mutant was also hypersusceptible to other antifungal agents (terbinafine and amorolfine) and to different metabolic inhibitors (cycloheximide, brefeldin A, and fluphenazine). The same mutant was slightly more susceptible than the wild type to nocodazole, cerulenin, and crystal violet but not to amphotericin B, nikkomycin Z, flucytosine, or pradimicin. In contrast, the delta ben mutant was rendered more susceptible only to the mutagen 4-nitroquinoline-N-oxide. However, this mutation increased the susceptibilities of the cells to cycloheximide and cerulenin when the mutation was constructed in a delta cdr1 background. The assay used in the present study could be implemented with new antifungal agents and is a powerful tool for assigning these substances as putative substrates of multidrug transporters.
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PMID:Susceptibilities of Candida albicans multidrug transporter mutants to various antifungal agents and other metabolic inhibitors. 889 Nov 34

Individuals seropositive for human immunodeficiency virus type 1 (HIV) express elevated levels of autoantibodies (AAbs) directed against recombinant T-cell receptors (TCRs) and synthetic peptide epitopes duplicating beta chain markers. We performed longitudinal studies of anti-TCR AAbs in HIV-1-infected individuals, making comparisons with uninfected sera and sera from other individuals infected with a nonviral agent. We determined levels of autoantibodies by titration using enzyme-linked immunosorbent assay (ELISA) and developed a means for characterizing "autoantibody CDR recognition spectrotypes" for individual sera. Antibody levels against certain defined synthetic epitopes were substantially elevated in HIV-infected subjects relative to reactivities by control groups. Individual sera showed relatively high AAb levels to a subset of CDR1 peptide epitopes. Two patients who subsequently developed AIDS showed particular reactivity to Vbeta2.1, 8.1, 10.1, and 22.1 epitopes. Our results show that production AAbs to TCR Vbeta epitopes is a general consequence of HIV infection. The response is individual but shows some restriction and shifts in AAb subpopulations often occur with time.
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PMID:Analysis of autoantibodies to T-cell receptors among HIV-infected individuals: epitope analysis and time course. 900 Apr 86

Multiple drug resistance is becoming a major problem in the treatment of AIDS patients with oropharyngeal candidosis. Candida albicans strains isolated from candidosis patients who do not respond to fluconazole therapy often show azole drug resistance which usually correlates with the expression of C. albicans CDR1, CDR2 or BENr genes, encoding potential drug efflux pumps. The objective of this study was to develop a yeast secretory vesicle transport assay and use this system to study the pumping function of Cdr1 and Benr. The C. albicans CDR1 and BEN r genes were cloned separately into plasmid pVT101-U, to form plasmids pKY1011 and pKN5001 respectively. Plasmids pVT101-U, pKY1011 and pKN5001 were transformed into Saccharomyces cerevisiae SY1, a sec6-4 mutant with a temperature-sensitive mutation in the secretory pathway. SY1 cells transformed with pKY1011 or pKN5001, were more resistant to fluconazole (MICs in both cases 64 microg/ml) than SY1 cells (MIC 32 microg/ml). In addition, cells transformed with pKY1011 were more resistant to cycloheximide (MIC 16 microg/ml) than SY1 cells (MIC 2 microg/ml). Intact secretory vesicles were isolated from SY1 cells expressing Cdr1 and these vesicles accumulated fluconazole in a time dependent manner. These experiments demonstrated that S. cerevisiae secretory vesicles can be used to examine the mechanism of fluconazole transport by putative C. albicans membrane pumps.
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PMID:Drug pumping mechanisms in Candida albicans. 958 31

Candida dubliniensis is a recently described Candida species associated with oral candidosis in human immunodeficiency virus (HIV)-infected and AIDS patients, from whom fluconazole-resistant clinical isolates have been previously recovered. Furthermore, derivatives exhibiting a stable fluconazole-resistant phenotype have been readily generated in vitro from fluconazole-susceptible isolates following exposure to the drug. In this study, fluconazole-resistant isolates accumulated up to 80% less [3H] fluconazole than susceptible isolates and also exhibited reduced susceptibility to the metabolic inhibitors 4-nitroquinoline-N-oxide and methotrexate. These findings suggested that C. dubliniensis may encode multidrug transporters similar to those encoded by the C. albicans MDR1, CDR1, and CDR2 genes (CaMDR1, CaCDR1, and CaCDR2, respectively). A C. dubliniensis homolog of CaMDR1, termed CdMDR1, was cloned; its nucleotide sequence was found to be 92% identical to the corresponding CaMDR1 sequence, while the predicted CdMDR1 protein was found to be 96% identical to the corresponding CaMDR1 protein. By PCR, C. dubliniensis was also found to encode homologs of CDR1 and CDR2, termed CdCDR1 and CdCDR2, respectively. Expression of CdMDR1 in a fluconazole-susceptible delta pdr5 null mutant of Saccharomyces cerevisiae conferred a fluconazole-resistant phenotype and resulted in a 75% decrease in accumulation of [3H]fluconazole. Northern analysis of fluconazole-susceptible and -resistant isolates of C. dubliniensis revealed that fluconazole resistance was associated with increased expression of CdMDR1 mRNA. In contrast, most studies showed that overexpression of CaCDR1 was associated with fluconazole resistance in C. albicans. Increased levels of the CdMdr1p protein were also detected in fluconazole-resistant isolates. Similar results were obtained with fluconazole-resistant derivatives of C. dubliniensis generated in vitro, some of which also exhibited increased levels of CdCDR1 mRNA and CdCdr1p protein. These results demonstrate that C. dubliniensis encodes multidrug transporters which mediate fluconazole resistance in clinical isolates and which can be rapidly mobilized, at least in vitro, on exposure to fluconazole.
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PMID:Identification and expression of multidrug transporters responsible for fluconazole resistance in Candida dubliniensis. 966 Oct 28

Failures of drug treatment in fungal infections combined with improvements in performances and standardization of antifungal susceptibility testing have drawn attention to the problem of antifungal resistance and its underlying mechanisms. Resistance of Candida species and Cryptococcus neoformans to flucytosine (5FC) develops during monotherapy. Acquired resistance results from a failure to metabolize 5FC to 5FUTP and 5FdUMP, or from the loss of feedback control of pyrimidine biosynthesis. A combination of 5FC and amphotericin B (AmB) reduces the appearance of resistant C. albicans isolates. Resistance to AmB is unusual. C. lusitaniae is the most susceptible to AmB resistance. C. neoformans with decreased AmB susceptibility has been isolated from an HIV-infected patient. Acquired resistance to AmB is often associated with alteration of membrane lipids, especially ergosterol. Concomitant with the widespread use of fluconazole there have been increasing reports of fluconazole resistance in Candida species and C. neoformans. Fluconazole resistance was mostly associated with prior use of fluconazole as intermittent therapy or prophylactic continuous treatment for recurrent thrush. In contrast to fluconazole, itraconazole is active against C. krusei. Decreased susceptibility to itraconazole is observed over time in C. albicans isolates becoming resistant to fluconazole. Decreased susceptibility to itraconazole and SCH-56592 was also observed in a few Aspergillus fumigatus isolates. Failure to accumulate azole antifungals has been identified as a cause of resistance in several post-treatment C. albicans, C. glabrata and C. krusei isolates. In azole-resistant C. albicans isolates from AIDS patients with oropharyngeal candidiasis, multidrug efflux transporters of the ATP-binding cassette (ABC) superfamily and of the class of major facilitators (MF) have been shown to be responsible for the low level of accumulation of azole antifungal agents. Two genes for these transporters, the ABC-transporter gene CDR1 and the MF gene, CaMDR1 (BEN) were shown to be overexpressed in resistant C. albicans isolates. Overexpression of BEN in Saccharomyces cerevisiae conferred resistance to fluconazole and terbinafine. CDR1 overexpression in S. cerevisiae conferred cross-resistance to fluconazole, itraconazole, ketoconazole and terbinafine. C. albicans clinical isolates resistant to azole antifungal agents over-expressing the ABC-transporter genes CDR1 and CDR2 were less susceptible to the morpholine derivative amorolfine. In C. glabrata isolates azole resistance is based on over-expression of the CgCDR gene. A reduced susceptibility of ergosterol biosynthesis is another mechanism of resistance described in a number of post-treatment C. albicans, C. neoformans and Histoplasma capsulatum isolates. Mutations have been reported in the CYP51A1 genes of resistant C. albicans isolates. Over-expression of CYP51A1 in C. albicans and C. glabrata may also account for a decreased susceptibility to azole antifungal agents.
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PMID:Antifungal drug resistance in pathogenic fungi. 998

The resistance mechanisms to azole antifungal agents were investigated in this study with two pairs of Candida glabrata clinical isolates recovered from two separate AIDS patients. The two pairs each contained a fluconazole-susceptible isolate and a fluconazole-resistant isolate, the latter with cross-resistance to itraconazole and ketoconazole. Since the accumulation of fluconazole and of another unrelated substance, rhodamine 6G, was reduced in the azole-resistant isolates, enhanced drug efflux was considered as a possible resistance mechanism. The expression of multidrug efflux transporter genes was therefore examined in the azole-susceptible and azole-resistant yeast isolates. For this purpose, C. glabrata genes conferring resistance to azole antifungals were cloned in a Saccharomyces cerevisiae strain in which the ATP binding cassette (ABC) transporter gene PDR5 was deleted. Three different genes were recovered, and among them, only C. glabrata CDR1 (CgCDR1), a gene similar to the Candida albicans ABC transporter CDR genes, was upregulated by a factor of 5 to 8 in the azole-resistant isolates. A correlation between upregulation of this gene and azole resistance was thus established. The deletion of CgCDR1 in an azole-resistant C. glabrata clinical isolate rendered the resulting mutant (DSY1041) susceptible to azole derivatives as the azole-susceptible clinical parent, thus providing genetic evidence that a specific mechanism was involved in the azole resistance of a clinical isolate. When CgCDR1 obtained from an azole-susceptible isolate was reintroduced with the help of a centromeric vector in DSY1041, azole resistance was restored and thus suggested that a trans-acting mutation(s) could be made responsible for the increased expression of this ABC transporter gene in the azole-resistant strain. This study demonstrates for the first time the determinant role of an ABC transporter gene in the acquisition of resistance to azole antifungals by C. glabrata clinical isolates.
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PMID:The ATP binding cassette transporter gene CgCDR1 from Candida glabrata is involved in the resistance of clinical isolates to azole antifungal agents. 1054 59


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