Biomedical subjects

E Zanelli

Publications and source records attributed to E Zanelli.

50 records · Page 3Linked to original sources

PubMed1995

Could HLA-DRB1 be the protective locus in rheumatoid arthritis?

Extensive studies in different ethnic groups have associated the susceptibility to development of rheumatoid arthritis (RA) with the third hypervariable region of the major histocompatibility complex (MHC) HLA-DR beta 1 molecule. On the basis of recent findings in the experimental mouse model of collagen-induced arthritis, Eric Zanelli, Miguel Gonzalez-Gay and Chella David propose that the HLA-DRB1 locus is associated with protection to RA and that the actual arthritogenic peptide-presenting molecule is HLA-DQ. Thus, the development of RA would depend upon the expression of the susceptible DQ allele and the nonprotective DRB1 alleles, along with environmental factors that trigger the autoimmune process.

Alleles↗

PubMed1995

Implantable defibrillation and thromboembolic events.

In ICD patients thromboembolic events (TEEs) are described as possible complications at implant or during the follow-up. We report four cases of TEEs (two peripheral and two cerebral; 6.5% of patients) that occurred in our series during a mean follow-up of 19.4 months. The patients had chronic postinfarction LV aneurysm (3) and idiopathic dilated cardiomyopathy (1). None had previous embolisms nor evidence of left atrial or LV clots at standard preoperative transthoracic echocardiography. No paroxysms of atrial fibrillation were documented prior or after ICD implant. We discuss the possible causes of embolization and the suitability of anticoagulant therapy in ICD patients.

Aged↗

PubMed1994

Protective role of major histocompatibility complex class II Ebd transgene on collagen-induced arthritis.

Collagen-induced arthritis (CIA) is an animal model of autoimmune inflammatory polyarthritis that has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC), H-2, and restricted to the H-2q and H-2r haplotypes. Whereas the role of the H-2A molecule in susceptibility to CIA is well established, little is known about the role of H-2E molecule in the disease. In this study, we analyzed the effect of a transgenic E beta d molecule on CIA susceptibility in a recombinant mouse B10.RQB3, which expresses the CIA susceptible Aq genes and an Eak gene, but does not produce an E molecule since Ebq is nonfunctional. In the presence of an Ebd transgene, a viable E molecule is generated. Whereas B10.RQB3 were susceptible to CIA, B10.RQB3-E beta d+ showed a dramatic reduction in the incidence of arthritis as well as a decrease in the level of anti-mouse and anti-bovine CII antibodies in their serum. No clear cut differences in the expression of T cell receptor (TCR) V beta was observed between E beta d+ and E beta d- transgenic mice. Mechanisms underlying the protective effect of E beta d transgenic molecule on CIA may shed light on how HLA-DR molecules influence human RA.

Animals↗

PubMed1993

Genomic organization and tissue expression of mouse proteasome gene Lmp-2.

The mouse Lmp-2 gene is located within the major histocompatibility complex (MHC) class II region and encodes a subunit of the 20S cytosolic proteasome. Previous studies indicated that the 20S proteasome is a catalytic core of the 26S proteolytic complex that possesses a latent multicatalytic proteinase activity and catalyzes an ATP-dependent, selective breakdown of proteins ligated to ubiquitin. This complex has recently been postulated to be involved in the processing of endogenous antigenic peptides for the MHC class I pathway. Here, we report the genomic organization and tissue expression of the mouse Lmp-2 gene. We have cloned and sequenced the entire mouse Lmp-2 gene, including 5'- and 3'-flanking regions. The gene consists of six exons, and its genomic organization is very similar to that of the recently described human LMP2 gene. Putative promoter and enhancer elements were identified in the 5'-flanking region by sequence comparison with known consensus sequences. The Lmp-2 gene is expressed in most tissues of unstimulated mice, except for brain tissue. The comparison of the 5'-flanking region of human and mouse sequences is discussed.

3T3 Cells↗

PubMed1993

Genomic organization and tissue expression of the mouse proteasome gene Lmp-7.

LMP7 is one of the two proteasome subunits encoded in the major histocompatibility complex and is speculated to play a role in the generation of endogenous peptides for presentation by class I molecules to cytotoxic T cells. Here we report the genomic organization of the mouse Lmp-7 gene and the tissue distribution of its messenger RNA. In contrast to human LMP7 which is composed of seven exons and six introns, the mouse Lmp-7 gene is organized in six exons and five introns. Interestingly, the region corresponding to the first exon of human LMP7 is highly modified by numerous insertions and deletions and contains two in frame stop codons. Consequently, the mouse Lmp-7 gene does not allow the alternative exon usage described in humans and most likely encodes for only one LMP7 protein. Thus, the Tap-1 3' end gene region and the Lmp-7 initial translation codon are separated by an 1182 nucleotide region which contains a TATA-box, a cAMP regulatory element, two SP1 sites, and two G-C-rich regions. Expression of the Lmp-7 messenger RNA was analyzed on different tissues from unstimulated mice. Lmp-7 messenger RNA is expressed in spleen, thymus, lung, liver, heart, and, at a very low level, in kidney but not in brain and testis. The possible role of Lmp genes in antigen processing is discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

Epitope mapping of human thyroid peroxidase defined seven epitopes recognized by sera from patients with thyroid pathologies.

Human thyroid peroxidase (hTPO) is the major component of the microsomal antigen. In almost cases, antibodies against this protein are found in sera from patients with autoimmune thyroid diseases. Overlapping cDNAs which correspond to the complete hTPO mRNA obtained from a thyroid library or by polymerase chain reaction were cloned and expressed as fusion proteins in a prokaryotic vector. Seven antigenic determinants between 21 and 49 amino acids were defined by cloning, subcloning of the immunoreactive regions and screenings with the two rabbit polyclonal anti hTPO antibodies. This study confirms the antigenic nature of the sequences 70-160 and 590-675 but above all refines the localization of three shorter distinct antigenic peptides corresponding to the sequences 68-105, 106-126 and 574-621. Moreover, four other determinants were characterized on the sequences 233-277, 467-515, 641-685 and 701-730. Analysis of sera from patients with autoimmune thyroid diseases (AITD) against the seven immunoreactive peptides confirms the heterogeneous nature of autoantibodies to hTPO.

Autoantibodies↗

PubMed1992

A major human thyroglobulin epitope defined with monoclonal antibodies is mainly recognized by human autoantibodies.

The antigenic nature of 15 anti-human thyroglobulin (hTg) monoclonal antibody (mAb) epitopes was studied by two different approaches. First, we tested two successive protease-digest products of hTg. Only four mAb from the same cluster of reactivity recognized a low-molecular weight peptide, the other mAb only bound native hTg or high-molecular weight digest fractions. Second, these 15 mAb were used to immunoscreen hTg expression libraries. Only the same four mAb revealed immunoreactive clones corresponding to region 1149-1295 on the hTg primary sequence. After subcloning, this antigenic determinant was reduced to a 102-amino acid peptide (hTg region 1149-1250). The two different methodologies were coherent and complementary, and demonstrated that hTg sequence 1149-1250 is the target for this cluster of four mAb. Moreover, anti-hTg autoantibodies which cross-reacted with these mAb bound the 102-amino acid peptide. This epitope was the one most frequently detected by sera from autoimmune thyroid disease. The data confirm the presence of an immunodominant domain in the central part of the hTg molecule and suggest that this mAb epitope may be a powerful probe for the diagnosis of autoimmune thyroid disorders.

Amino Acid Sequence↗

PubMed1992

Use of recombinant epitopes to study the heterogeneous nature of the autoantibodies against thyroid peroxidase in autoimmune thyroid disease.

Microsomal antigen is often recognized by the sera from patients with autoimmune thyroid disease (AITD). Human thyroid peroxidase (hTPO) is the main component of this antigen. In a previous study, we expressed hTPO cDNA as fusion proteins in prokaryotic vector; we thereby defined seven antigenic peptides by using two rabbit polyclonal anti-hTPO antibodies. In the present study we used the seven epitopes and three widened peptides to define the reactivity pattern of 61 sera from patients with AITD. Thirty-eight of them reacted against at least one of the seven hTPO-restricted epitopes; 14 were negative against the seven determinants but recognized one or two of the extended peptides. Thus, the antibody response against hTPO appeared to be highly heterogeneous in AITD patient sera. Moreover, we demonstrated that the immunodetection of the hTPO on Western blotting with deoxycholate solubilized microsomes can be perfectly correlated with the recognition of one of the epitopes in the region 554-735.

Autoantibodies↗

PubMed1991

Low doses of l-sulpiride down-regulate striatal and cortical dopamine receptors and beta-adrenoceptors.

There is now clinical evidence that l-sulpiride has antidepressant effects when administered at low, non-neuroleptic doses. Down-regulation of beta-receptor-linked adenylate cyclase is a well-documented adaptive response to chronic administration of antidepressant drugs. In this study, we investigated dopamine receptor and beta-adrenoceptor changes induced by chronic administration of low doses of l-sulpiride. The data indicate that striatal D1 and D2 receptor function was desensitized by the treatment, which suggests that at low doses l-sulpiride preferentially blocks D2 autoreceptors, leading to increased dopamine release. l-Sulpiride also induced a selective down-regulation of beta-receptor-associated adenylate cyclase activity in the frontal cortex, but not in the striatum, which does not receive norepinephrine projections. Taken together these data suggest that cortical noradrenergic terminals may be endowed with dopamine D2 receptors controlling norepinephrine release and that blockade of this dopaminergic inhibitory modulation may be involved in the antidepressant effects of l-sulpiride.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1991

Epitope mapping of human thyroglobulin reveals a central immunodominant region.

Thyroglobulin is the thyroid hormone precursor and the major antigen frequently involved in autoimmune diseases. The primary structure of human thyroglobulin is known but the spatial structure remains largely undetermined. By using fusion protein produced in prokaryotic system we have characterized seven short immunoreactive peptides carrying at least one epitope. None of them includes hormonogenic sites, but five are concentrated in the central part of the monomeric molecule, which thus emerges as the major immunogenic region of this protein.

Epitopes↗

PubMed1991

Anti-human thyroid peroxidase and anti-human thyroglobulin antibodies present no cross-reactivity on recombinant peptides.

Thyroglobulin (Tg) and thyroid peroxidase (TPO) are two antigens largely recognized by the sera from patients with autoimmune thyroid disease (AITD). Recently, the complete mapping of both antigens was established with rabbit polyclonal antibodies by the use of recombinant proteins expressed in prokaryotic vector. Several investigators have argued for the existence of a cross-reactivity of some hetero- and autologous antibodies versus these two proteins. In the present study, using rabbit polyclonal antibody, mouse polyclonal antibody and autoimmune antibody (aAb), we observed no common epitope on human Tg (hTg) and human TPO (hTPO).

Amino Acid Sequence↗

PubMed1990

Epitope mapping of human thyroglobulin. Heterogeneous recognition by thyroid pathologic sera.

Thyroglobulin is the major Ag of the thyroid gland involved in autoimmune pathologies. Epitope mapping was carried out with a rabbit polyclonal immune serum against fusion proteins expressed in prokaryotic cells. After screening of an initial human thyroglobulin cDNA library and subcloning of immunoreactive clones, seven epitopes were characterized and localized on the human thyroglobulin monomeric molecule. One was close to each extremity of the molecule, and five others were concentrated in the middle, covering a sixth of this 2748-amino-acid chain. The immunoreactivities of 18 autoimmune sera from different thyroid pathologies were tested against the seven previously characterized epitopes. Those from Hashimoto's thyroiditis were the most immunoreactive. Immune responses were heterogeneous for sera from different pathologies as well as for those from the same pathology. The central epitopes and the near-C-terminal epitope, however, were the epitopes most often recognized by the immune sera. These findings show that some autoepitopes overlap accurately with some heteroepitopes characterized by a polyclonal immune serum directed against the mature protein.

Amino Acid Sequence↗

PubMed1990

Evidence for an alternate splicing in the thyroperoxidase messenger from patients with Graves' disease.

An initial lambda gt 11 cDNA library constructed from a human Graves' patient thyroid was screened with an immunopurified rabbit anti-human thyroperoxidase (hTPO) polyclonal antibody. A 869 bp clone was obtained. It presents a 130 bp deletion as compared to the published sequence and a 77 bp insertion in the 3' non-coding region. Screening of a pUC cDNA library from another Graves' patient thyroid exhibited the same 130 bp deletion in two other cDNA clones. PCR analysis of mRNA transcripts confirmed the presence of the two messengers in two other Graves' thyroid tissues. In all the cases, this new spliced mRNA species represents between 40% and 50% of the total hTPO mRNAs. With respect to the structure of the hTPO gene, the present deletion suggests an alternate splicing of exon 16. The juxtaposition of exon 17 to exon 15 encoding the transmembrane domain leads to a shift in the reading frame. By the use of a different stop codon, the spliced mRNA generates a modified 56 - COOH terminal aminoacids (aa) sequence.

Amino Acid Sequence↗

PubMedDate not supplied

An extended HLA-DQ-DR haplotype rather than DRB1 alone contributes to RA predisposition.

In the present study, we tested our hypothesis on the role of a DQ-DR haplotype in rheumatoid arthritis (RA) predisposition. Using two groups of patients and controls, one from The Netherlands and one from Switzerland, we found that DQA1*0301-homozygous and DQA1*0301//DQA1*0101/04-heterozygous individuals are highly predisposed to RA in both populations, while DQA1*0101/04-homozygous are not. The DQA1*0301-DRB1*0403/06/07 and DQA1*0301-DRB1*0901 haplotypes are not associated with RA by themselves but strongly increase the risk of developing disease in DQA1*0301- and DQA1*0101/04-heterozygous. DRB1 alleles carrying the motif DERAA in their third hypervariable region, i.e., *0103, *0402, *1102, *1103, *1301, and *1302, provide a long-lasting protection against RA in DQA1*0101/04- but not in DQA1*0301-positive individuals. These data show that considering both DQ and DR gives a better distinction between patients and controls than the shared epitope hypothesis.

Arthritis, Rheumatoid↗