Rationally designed strings of promiscuous CD4(+) T cell epitopes provide help to Haemophilus influenzae type b oligosaccharide: a model for new conjugate vaccines.

The age-related and T cell-independent immunological properties of most capsular polysaccharides limit their use as vaccines, especially in children under 2 years of age. To overcome these limitations, polysaccharide antigens have been successfully conjugated to a variety of carrier proteins, such as diphtheria toxoid or tetanus toxoid (TT) and the diphtheria mutant (CRM197) to produce very successful glycoconjugate vaccines. The increasing demand for new conjugate vaccines requires the availability of additional carriers providing high and long-lasting T helper cell immunity. Here we describe the design and construction of three recombinant carrier proteins (N6, N10, N19) constituted by strings of 6, 10 or 19 human CD4(+) T cell epitopes from various pathogen-derived antigens, including TT and proteins from Plasmodium falciparum, influenza virus and hepatitis B virus. Each of these epitopes is defined as universal in that it binds to many human MHC class II molecules. When conjugated to Haemophilus influenzae type b (Hib) oligosaccharide, these carriers elicit a potent anti-Hib antibody response in mice. In the case of the N19-Hib conjugate, this response is at least as good as that observed with CRM197-Hib, a conjugate vaccine currently used for mass immunization. We also show that some of the universal epitopes constituting the recombinant carriers are specifically recognized by two human in vitro systems, suggesting that T cell memory is provided by the selected epitopes. The data indicate that rationally designed recombinant polyepitope proteins represent excellent candidates for the development and clinical testing of new conjugate vaccines.

Role of statins in the management of dyslipidemia after cardiac transplant: randomized controlled trial comparing the efficacy and the safety of atorvastatin with pravastatin.

BACKGROUND: Cardiac transplant patients are at increased risk of dyslipidemia, a known pathogenetic factor in chronic rejection. The aim of this study was to compare the efficacy and the safety of treatment with atorvastatin (AT) and treatment with pravastatin (PV) in a population of dyslipidemic transplant patients. METHODS: Thirty-nine transplant patients were randomized to receive a 4-month cycle of therapy with AT or PV, in a cross-over sequence. We analyzed the effects on their lipid profiles using Student t-test for paired data. RESULTS AND CONCLUSION: Atorvastatin was significantly more effective than PV in reducing total cholesterol (33% vs 21%, p < 0.001), LDL cholesterol (45% vs 30%, p = 0.001), and triglycerides (24% vs 7.7%, p < 0.001), at lower doses and with comparable tolerability and safety.

Increasing plasma homocysteine during follow-up in heart transplant recipients: effects of folate and renal function.

BACKGROUND: Hyperhomocysteinemia is a common finding in heart transplant recipients and may represent a risk factor for graft failure. However, the time-course, determinants and effects of medical therapy on total homocysteine plasma levels after heart transplantation remain undetermined. The aim of this study was to prospectively analyze 1) the time-course of total homocysteine in heart transplant recipients; 2) the effects of folate supplements and cyclosporine A on total homocysteine; 3) the relation among renal function, serum vitamin levels, and total homocysteine. METHODS: Fifty-two heart transplant recipients consecutively evaluated for routine follow-up during 1998 were included in the study (mean age 54 +/- 12 years; 28% female). Among the 52 patients, 10 patients were treated with folate for the entire period of the study (Group F), while 26 patients never received folate (Group NF). The remaining 16 patients who did not take folate on a regular basis were excluded from subgroup analysis. Total homocysteine and creatinine plasma levels were assayed at entry into the study (time 0) and at the end of the study, 12 months later (time 12). RESULTS: Homocysteinemia increased significantly from time 0 to time 12 (p < 0.001), regardless of creatinine plasma levels (p = 0.03) and folate intake (p < 0.01). However, total homocysteine levels were lower in Group F compared to Group NF at time 0 and time 12 (p < 0.02). On multivariate analysis, time of follow-up, serum creatinine and lack of folate intake were positive independent predictors of total homocysteine. CONCLUSIONS: Homocysteinemia increased over time in heart transplant recipients, regardless of renal function and folate administration. Lower total homocysteine levels were associated with folate intake, suggesting that folate supplements may play a role in the prevention of vascular allograft disease.

Size determination of bacterial capsular oligosaccharides used to prepare conjugate vaccines.

We recently described the use of ion exchange chromatography for analysis and the industrial scale preparation of pools of oligosaccharides of intermediate chain length from polysaccharides of Haemophilus influenzae type b (Hib) and Neisseria meningitidis groups A and C. These negatively charged "sized" oligosaccharides are activated and conjugated to the carrier protein (CRM197) to prepare the corresponding glycoconjugate vaccines. Characterization and accurate determination of the degree of polymerization (DP) of the pool of oligosaccharides is essential for the consistent production of these conjugate vaccines. This paper describes the colorimetric assays used for determination of the average DP of the Hib and meningococcal oligosaccharides, and the qualification of these assays achieved by size characterization of the respective oligosaccharides by use of physicochemical methods, including liquid chromatography, mass spectrometry (ionspray) and NMR spectroscopy.

Morphometric and tridimensional studies of tubular cystic degeneration in rat kidney following exposure to cisplatin.

Cisplatin, a widely used chemotherapeutic agent, is characterized by a dose-limiting renal toxicity. Cystic tubular dilatation is the most typical histopathological alteration encountered in cisplatin-treated rats. The purpose of the present study was to explore by a morphometric approach the development of cystic degeneration and, in particular, to analyse, by computer-assisted tridimensional reconstructions, the spatial structure and the tubular origin of cisplatin-induced renal cysts. This study was performed on rats given 8 mg/kg cisplatin i.p. for four days and sacrificed 4, 7, 14, 21, 50 and 60 days after last drug administration. The relative area occupied by cystic tubules increased rapidly in the outer stripe of outer medulla (OSOM) and reached a maximum 21 days after the end of treatment. Cystic dilatations appeared later in the kidney cortex and the inner stripe of outer medulla (ISOM). The tridimensional study of cystic tubules located in OSOM confirmed previous reports indicating that they arise from proximal straight tubules and showed that cystic degeneration was not associated with atrophy or degeneration in more proximal parts of the nephron. Moreover, cystic tubules located in ISOM were found to originate from distal straight tubules and/or the loop of Henle, an observation which, to our knowledge, has not been reported so far in cisplatin-treated rats.

Processing of interleukin-1 in cells of monocytic lineage is differentiation-dependent.

The interleukin-1 (IL-1) alpha and beta precursor proteins are processed and released from several cell types in the absence of a canonical signal peptide. To gain some insight into the mechanisms that allow the production of IL-1 alpha and beta, we have investigated by immunoprecipitation the synthesis, their release and processing in a promyeloblastic cell line of tumoral origin, U937, and in peripheral blood monocytes. We show that U937 monocytic cells, on induction with a tumor-promoting agent, synthesize and release into the culture medium proIL-1 beta but do not process it. Similarly, peripheral blood monocytes left in adherence for 24 h or longer, prior to addition of lipopolysaccharide, synthesize and release proIL-1 alpha and beta without detectable processing of either cytokine. Processing and release of IL-1 alpha and beta by peripheral blood monocytes can be observed when monocytes are left to adhere for periods less than 15 h before lipopolysaccharide addition. IL-1 alpha and beta show similar kinetics of release from the cells, suggesting the existence of a common mechanism regulating their secretion. Since peripheral blood monocytes left in adherence in the presence of lipopolysaccharide differentiate into macrophages, we conclude that release and processing of IL-1 can occur independently and that processing depends on the stage of differentiation of monocytes, i.e. only the monocytes at an early stage of differentiation produce 17-kDa IL-1 alpha and beta.

Human interleukin-1 beta gene.

We report the nucleotide sequence of the human chromosomal gene which encodes the interleukin-1 beta protein (IL-1 beta). The gene spans a region of 7.5 kb and the coding part is divided into seven exons. Comparison with the homologous mouse gene reveals that the structural organization is conserved through evolution. In addition to this, human and murine IL-1 beta genes show extensive sequence homology within the intervening sequences.

The murine interleukin 1 beta gene: structure and evolution.

We have isolated from a genomic library a murine recombinant clone containing the gene coding for interleukin-1 beta m-RNA. A 7000 b.p. DNA fragment has been sequenced. Sequences homologous with human IL-1 beta cDNA have been found distributed within 7 exons. The translation of these sequences allows the prediction of a protein 269 aminoacids long. Hybridization of P388D1 RNA from cells stimulated with phorbol myristic acetate with a genomic DNA probe shows the existence of a 1.6 Kb murine IL-1 beta mRNA which is absent in the unstimulated cells. The comparative analysis between the murine IL-1 beta and the human IL-1 alpha genes shows extreme conservation of the aminoacids at the exon junctions. This observation together with the similarity in number and size of the exons suggests that these genes have diverged from a common ancestor.