The preparation of liposomes bearing human (HLA) transplantation antigens.
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ABSTRACT:
SUBMITTER: Turner MJ
PROVIDER: S-EPMC1183984 | biostudies-other | 1978 May
REPOSITORIES: biostudies-other
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Project description:BackgroundCorneal transplantation is the most frequently performed transplantation in the UK. Despite this, the therapeutic value of matching human leukocyte antigen (HLA) subtypes for transplanted corneas remains controversial. Ocular immune privilege was originally deemed to render matching unnecessary; however, more recently, matching has demonstrated improved outcomes including graft success, amongst others. This systematic review aims to evaluate the effectiveness of major and minor antigen matching on graft outcomes in corneal transplantation.MethodsStandard systematic review methodology will be used to identify, select and extract data from observational studies and clinical trials assessing the effects of HLA matching on corneal graft outcomes. Bibliographic databases (Cochrane Library, EMBASE, MEDLINE, Web of Science, Scopus), clinical trial registers, abstract and conference proceedings, in addition to dissertation, thesis and grey literature will be searched. Neither date of publication nor language will be restricted, and non-English articles will be translated where necessary. The primary outcome will be to assess corneal graft success for different degrees of HLA matching/mismatching. The precise end outcome measure varies amongst studies and includes graft rejection, immunoreaction, failure and survival. Therefore, data will be extracted across all relevant outcome parameters and grouped for subsequent statistical tests. Risk of bias assessment will be completed, appropriate to each study design. Study selection, data extraction and risk of bias assessment will be independently completed by two reviewers. Data will be tabulated, and a narrative synthesis presented. Meta-analysis will be performed where there is sufficient homogeneity between studies to warrant its effective completion. Subgroup and sensitivity analysis will be undertaken if appropriate.DiscussionMany studies have investigated the effectiveness of HLA matching for corneal transplantation. A systematic review is needed to collate and analyse this evidence. Findings of this systematic review may form the basis of evidence-based recommendations on pre-operative HLA typing and matching of corneal grafts for transplantation.Systematic review registrationPROSPERO reference CRD42020198882.
| S-EPMC8136040 | biostudies-literature
Project description:The three-dimensional (3D) structures of human leukocyte antigen (HLA) molecules are indispensable for the studies on the functions at molecular level. We have developed a homology modeling system named HLA-modeler specialized in the HLA molecules. Segment matching algorithm is employed for modeling and the optimization of the model is carried out by use of the PFROSST force field considering the implicit solvent model. In order to efficiently construct the homology models, HLA-modeler uses a local database of the 3D structures of HLA molecules. The structure of the antigenic peptide-binding site is important for the function and the 3D structure is highly conserved between various alleles. HLA-modeler optimizes the use of this structural motif. The leave-one-out cross-validation using the crystal structures of class I and class II HLA molecules has demonstrated that the rmsds of nonhydrogen atoms of the sites between homology models and crystal structures are less than 1.0?Å in most cases. The results have indicated that the 3D structures of the antigenic peptide-binding sites can be reproduced by HLA-modeler at the level almost corresponding to the crystal structures.
| S-EPMC4207409 | biostudies-literature
Project description:Human HepG2 hepatoma cells express a high number of insulin receptors. Growing cells exhibit 70% of their insulin receptors on the plasma membrane. Moreover, cell-surface insulin receptors form molecular complexes with class I major histocompatibility antigens, as determined by co-immunoprecipitation of the receptors by anti-class I monoclonal antibodies. On exposure to saturating concentrations of insulin, the hormone is rapidly internalized into a Pronase-resistant compartment. Internalization of insulin is accompanied by a rapid (t1/2 = 2-3 min) redistribution of insulin receptors from the cell surface to an intracellular compartment. On removal of insulin from the medium, functional receptors recycle back to the plasma membrane, where they can bind insulin again. With chronic exposure of HepG2 cells to insulin, the initial redistribution of receptors is followed by a slow (t1/2 = 9 h) down-regulation of the receptors. Finally, notwithstanding their interaction at the cell surface, insulin receptors and class I major histocompatibility antigens are internalized at different rates and with independent regulation.
| S-EPMC1147719 | biostudies-other
Project description:Ankylosing spondylitis (AS) is the most prevalent form of spondyloarthritis, with a known genetic association with the HLA-B27 molecule. The aim of this study was to assess the contribution of the HLA-G, HLA-E and HLA-F to AS susceptibility/protection in Portuguese patients with HLA-B27 AS and HLA-B27 unaffected controls.High-resolution typing of HLA-G, HLA-E and HLA-F was performed in 228 patients with HLA-B27 AS and 244 HLA-B27 unaffected controls. Allelic, genotypic and haplotypic frequencies were compared between cohorts. To replicate the results, single nucleotide polymorphisms (SNPs) in HLA-E and HLA-F genes were typed in Australian cohorts. For further confirmation, a group of European-descent patients with AS and unaffected controls were genotyped for Major Histocompatibility Complex SNPs using the Illumina microarray.In the Portuguese population, no significant differences were found in HLA-G. For HLA-E, a significant difference was detected for the genotype HLA-E*01:01:01/01:03:01 (p=0.009; pc=0.009; OR=0.51), with a protection effect. For HLA-F, significant differences were detected in the allele HLA-F*01:01:02 (p=0.0049; pc=0.0098; OR=0.60) and corresponding SNP rs2075682 (p=0.0004; pc=0.0008; OR=0.53), suggesting protection and in the genotype HLA-F*01:01:01/01:03:01 (p=0.011; pc=0.043; OR=2.00), suggesting a susceptibility effect. Three G-E-F haplotypes with significant differences were detected but occur in a very small number of individuals. The only significant differences detected in the replication studies were for HLA-E rs1059510 in the Australians and for HLA-F rs1736924 in the European-descent cohorts.Our results reveal suggestive AS protective and susceptibility effects from both HLA-E and HLA-F loci, however with population differences. To our knowledge, this is the first study showing association of HLA-F with AS.
| S-EPMC6045739 | biostudies-literature
Project description:BackgroundPenetrating keratoplasty can commonly restore vision in corneal blindness. However, immunological graft reactions may induce irreversible graft failure in a substantial percentage. Repeat keratoplasties in turn are associated with increased risk of graft failure and possibly irreversible blindness. Topical as well as systemic immunosuppressants are administered for prophylaxis. However, severe adverse effects limit long-term usage. By contrast, matching for transplantation antigens might be effective for a long time.MethodsFANCY is a prospective, controlled, randomised, double-blind, multi-centre clinical trial with two parallel arms. The primary objective is to evaluate superiority of the proposed HLA matching strategy in comparison to random graft assignment with respect to the primary endpoint 'time to first endothelial graft rejection'. Relevant inclusion criteria are age over 18 years and waiting for penetrating or endothelial lamellar keratoplasty. The most important exclusion criteria are abuse of medication and/or drugs and an anticipated waiting time for an HLA match longer than 6 months. After randomisation, patients either receive a HLA-matched graft (experimental intervention) or a random graft (control intervention). The calculated sample size is 620 patients. The trial started in 2009 with a recruitment period of 24 months. A total of 654 patients were included during this time.DiscussionThe primary goal of FANCY is to assess whether histocompatibility matching is feasible and effective in the broad clinical routine. However, during the course of the trial, the landscape of keratoplasty changed due to the rise of Descemet Membrane Endothelial Keratoplasty (DMEK). Nowadays, immune reactions are confined mostly to the 'high-risk' subgroups. If we would design FANCY in 2014, we would narrow down the inclusion criteria to include only the high risk patients and accept longer waiting times for a matching donor here.Trial registrationThe unique identifying number of the FANCY trial is NCT00810472.
| S-EPMC4292991 | biostudies-literature
Project description:Sec1-Munc18 (SM) proteins co-operate with SNAREs {SNAP [soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein] receptors} to mediate membrane fusion in eukaryotic cells. Studies of Munc18a/Munc18-1/Stxbp1 in neurotransmission suggest that SM proteins accelerate fusion kinetics primarily by activating the partially zippered trans-SNARE complex. However, accumulating evidence has argued for additional roles for SM proteins in earlier steps in the fusion cascade. Here, we investigate the function of Munc18a in reconstituted exocytic reactions mediated by neuronal and non-neuronal SNAREs. We show that Munc18a plays a direct role in promoting proteoliposome clustering, underlying vesicle docking during exocytosis. In the three different fusion reactions examined, Munc18a-dependent clustering requires an intact N-terminal peptide (N-peptide) motif in syntaxin that mediates the binary interaction between syntaxin and Munc18a. Importantly, clustering is preserved under inhibitory conditions that abolish both trans-SNARE complex formation and lipid mixing, indicating that Munc18a promotes membrane clustering in a step that is independent of trans-SNARE zippering and activation.
| S-EPMC5651683 | biostudies-literature
Project description:Background: Kidney transplant recipients appear to be at higher risk for critical COVID-19. Our analysis aimed to identify the possible risk factors for a severe course of the COVID-19 disease and to determine the influence of selected human leukocyte antigens (HLAs) on the course of the disease. Methods: This is a retrospective, multicenter analysis that included patients that were confirmed to be severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) positive after kidney transplantation (KT). The group of patients was divided into two subgroups according to the course of the infection, as follows: non-hospitalized and hospitalized. Results: A total of 186 patients (men, 69.4%) with confirmed SARS-CoV-2 positivity were included in the group. The following independent risk factors for the outcome of hospitalization were identified: the age at the time of infection [odds ratio (OR) = 1.19, P < 0.0001], a body mass index (BMI) >29.9 kg/m2 (OR = 7.21, P < 0.0001), <7.5-mg prednisone dose/day (OR = 2.29, P = 0.0008), and HLA-DQ2 with a protective nature (OR = 0.05, P = 0.0034). Conclusions: Higher doses of corticosteroids (>7.5 mg/kg) in standard immunosuppressive regimes and HLA-DQ2 appear to be protective factors in our analysis.
| S-EPMC8591240 | biostudies-literature
Project description:Composite endpoints that not only encompass mortality and relapse, but other critical post-transplant events such as graft-versus-host disease, are being increasingly utilized to quantify survival without significant morbidity after allogeneic blood or marrow transplantation. High-dose, post-transplantation cyclophosphamide reduces severe graft-versus-host disease with allogeneic marrow transplantation, making composite endpoints after this management particularly interesting. We retrospectively analyzed 684 adults with hematologic malignancies who received T-cell-replete bone marrow grafts and cyclophosphamide after myeloablative HLA-matched related (n=192) or unrelated (n=120), or non-myeloablative HLA-haploidentical (n=372) donor transplantation. The median follow up was 4 (range, 0.02-11.4) years. Graft-versus-host disease-free, relapse-free survival was defined as the time after transplantation without grade III-IV acute graft-versus-host disease, chronic graft-versus-host disease requiring systemic treatment, relapse, or death. Chronic graft-versus-host disease-free, relapse-free survival was defined as the time after transplantation without moderate or severe chronic graft-versus-host disease, relapse, or death. One-year graft-versus-host disease-free, relapse-free survival and chronic graft-versus-host disease-free, relapse-free survival estimates were, respectively, 47% (95% CI: 41-55%) and 53% (95% CI: 46-61%) after myeloablative HLA-matched related, 42% (95% CI: 34-52%) and 52% (95% CI: 44-62%) after myeloablative HLA-matched unrelated, and 45% (95% CI: 40-50%) and 50% (95% CI: 45-55%) after non-myeloablative HLA-haploidentical donor transplantation. In multivariable models, there were no differences in graft-versus-host disease-free, or chronic graft-versus-host disease-free, relapse-free survival after either myeloablative HLA-matched unrelated or non-myeloablative HLA-haploidentical, compared with myeloablative HLA-matched related donor transplantation. Although limited by inclusion of dissimilar cohorts, we found that post-transplantation cyclophosphamide-based platforms yield comparable composite endpoints across conditioning intensity, donor type, and HLA match.
| S-EPMC5286947 | biostudies-literature
Project description:The antigenicity of cells is demarcated by the peptides bound by their Human Leucocyte Antigen (HLA) molecules. Through this antigen presentation, T cell specificity response is controlled. As a fraction of the expressed mutated peptides is presented on the HLA, these neo-epitopes could be immunogenic. Such neo-antigens have recently been identified through screening for predicted mutated peptides, using synthetic peptides or ones expressed from minigenes, combined with screening of patient tumor-infiltrating lymphocytes (TILs). Here we present a time and cost-effective method that combines whole-exome sequencing analysis with HLA peptidome mass spectrometry, to identify neo-antigens in a melanoma patient. Of the 1,019 amino acid changes identified through exome sequencing, two were confirmed by mass spectrometry to be presented by the cells. We then synthesized peptides and evaluated the two mutated neo-antigens for reactivity with autologous bulk TILs, and found that one yielded mutant-specific T-cell response. Our results demonstrate that this method can be used for immune response prediction and promise to provide an alternative approach for identifying immunogenic neo-epitopes in cancer.
| S-EPMC4868674 | biostudies-literature
Project description:Objective: This study aimed to develop a new polyethylene glycol (PEG)ylated ?-elemene liposome (PEG-Lipo-?-E) and evaluate its characterization, pharmacokinetics, antitumor effects and safety in vitro and in vivo. Methods: The liposomes were prepared by ethanol injection and high-pressure micro-jet homogenization. Characterization of the liposomes was conducted, and drug content, entrapment efficiency (EE), in vitro release and stability were studied by ultra-fast liquid chromatography (UFLC) and a liquid surface method. Blood was drawn from rats to establish the pharmacokinetic parameters. The anticancer effect was evaluated in a KU-19-19 bladder cancer xenograft model. Histological analyses were performed to evaluate safety. Results: The PEG-Lipo-?-E showed good stability and was characterized as 83.31 ± 0.181 nm in size, 0.279 ± 0.004 in polydispersity index (PDI), -21.4 ± 1.06 mV in zeta potential, 6.65 ± 0.02 in pH, 5.024 ± 0.107 mg/mL in ?-elemene (?-E) content, and 95.53 ± 1.712% in average EE. The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated the formation of PEG-Lipo-?-E. Compared to elemene injection, PEG-Lipo-?-E demonstrated a 1.75-fold decrease in clearance, a 1.62-fold increase in half-life, and a 1.76-fold increase in area under the concentration-time curves (AUCs) from 0 hour to 1.5 hours (P < 0.05). PEG-Lipo-?-E also showed an enhanced anticancer effect in vivo. Histological analyses showed that there was no evidence of toxicity to the heart, kidney, liver, lung or spleen. Conclusions: The present study demonstrates PEG-Lipo-?-E as a new formulation with ease of preparation, high EE, good stability, improved bioavailability and antitumor effects.
| S-EPMC7142831 | biostudies-literature