| 1. |
- Truedsson, Lennart
(författare)
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Classical pathway deficiencies - A short analytical review.
- 2015
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 68:1, s. 14-19
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Forskningsöversikt (refereegranskat)abstract
- Deficiencies in the classical pathway of complement activation have some common features but show also great differences. Deficiencies of each of the components (C1q, C1s, C1r, C4 and C2) imply increased susceptibility to bacterial infections. They are also associated with increased risk to develop systemic lupus erythematosus where deficiency of C1q is strongly associated to the disease while C4 less and C2 much less. Deficiency of C1q affects only activation of the classical pathway while deficiency of C4 and C2 also prevent activation of the lectin pathway. Bypass mechanisms may result in complement activation also in absence of C2 but not in absence of C1q or C4. The genes for C2 and C4 isotypes are closely located within the MHC class III region on chromosome 6p and the genes for the 3 C1q chains are on chromosome 1p. Deficiencies of C1q and of C4 show genetic heterogeneity while deficiency of C2 in the great majority of cases is caused by a specific deletion. The production of C4 and C2 is mainly by the hepatocytes in the liver while C1q is produced by monocytic bone marrow derived cells. This has implications for the possibility to treat the deficiency and hematopoietic stem cell transplantation has been tried in C1q deficiency.
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| 2. |
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| 3. |
- Amano, Mariane T, et al.
(författare)
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Genetic analysis of complement C1s deficiency associated with systemic lupus erythernatosus highlights alternative splicing of normal C1s gene
- 2008
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 45:6, s. 1693-1702
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Tidskriftsartikel (refereegranskat)abstract
- Deficiencies of complement proteins of the classical pathway are strongly associated with the development of autoimmune diseases. Deficiency of Clr has been observed to occur concomitantly with deficiency in Cls and 9 out of 15 reported cases presented systemic lupus erythernatosus (SLE). Here, we describe a family in which all four children are deficient in Cls but only two of them developed SLE. Hemolytic activity mediated by the alternative and the lectin pathways were normal, but classical pathway activation was absent in all children's sera. Cls was undetectable, while in the parents' sera it was lower than in the normal controls. The levels of Clr observed in the siblings and parents sera were lower than in the control, while the concentrations of other complement proteins (C3, C4, MBL and MASP-2) were normal in all family members. Impairment of Cls synthesis was observed in the patients' fibroblasts when analyzed by confocal microscopy. We show that all four siblings are homozygous for a mutation at position 938 in exon 6 of the Cls cDNA that creates a premature stop codon. Our investigations led us to reveal the presence of previously uncharacterized splice variants of Cls mRNA transcripts in normal human cells. These variants are derived from the skipping of exon 3 and from the use of an alternative 3' splice site within intron I which increases the size of exon 2 by 87 nucleotides.
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| 4. |
- Andersson, Mattias K., et al.
(författare)
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Extended cleavage specificity of mMCP-1, the major mucosal mast cell protease in mouse - High specificity indicates high substrate selectivity
- 2008
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 45:9, s. 2548-2558
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Tidskriftsartikel (refereegranskat)abstract
- Mucosal mast cells are in the mouse predominantly found in the epithelium of the gastrointestinal tract. They express the beta-chymases mMCP-1 and mMCP-2. During nematode infections these intraepithelial mast cells increase in numbers and high amounts of mMCP-1 appear in the jejunal lumen and in the circulation. A targeted deletion of this enzyme leads to decreased ability to expel the intraepithelial nematode Trichinella spiralis. A suggested role for mMCP-1 is alteration of epithelial permeability by direct or indirect degradation of epithelial and endothelial targets, however, no such substrates have yet been identified. To enable a screening for natural substrates we performed a detailed analysis of the extended cleavage specificity of mMCP-1, using substrate phage display technology. In positions P1 and P1' distinct preferences for Phe and Ser, respectively, were observed. In position P2 a high selectivity for large hydrophobic amino acids Phe, Trp and Leu was detected, and in position P2' aliphatic amino acids Leu, Val and Ala was preferred. In positions P3 and P4, N-terminal of the cleaved bond, mMCP-1 showed specificity for aliphatic amino acids. The high selectivity in the P2, P1, P1' and P2' positions indicate that mMCP-1 has a relatively narrow set of in vivo substrates. The consensus sequence was used to screen the mouse protein database for potential substrates. A number of mouse extracellular or membrane proteins were identified and cell adhesion and connective tissue components were a dominating subfamily. This information, including the exact position of potential cleavage sites, can now be used in a more focused screening to identify which of these target molecules is/are responsible for the increased intestinal permeability observed in parasite infected mice.
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| 5. |
- Andersson, Mattias K., et al.
(författare)
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The extended cleavage specificity of the rodent β-chymases rMCP-1 and mMCP-4 reveal major fumctional similarities to the human mast cell chymase
- 2008
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 45:3, s. 766-775
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Tidskriftsartikel (refereegranskat)abstract
- In rat and mouse the phylogenetic homologues of the human mast cell alpha-chymase (rMCP-5 and mMCP-5) have lost their chymase activity and instead become elastases. To investigate whether rodents hold enzymes with equivalent function as the primate alpha-chymases, we have determined the extended cleavage specificity of the major connective tissue mast cell beta-chymases in rat and mouse, rMCP-1 and mMCP-4. By using a phage display approach we determined the enzyme/substrate interaction in seven positions, both N- and C-terminal of the cleaved bond. The two proteases were found to display rather similar specificities. Both enzymes prefer Phe in position P1, and aliphatic amino acids are favoured N-terminal of the cleaved bond, i.e. Leu in P2 and Val in P3 and P4. Val and Leu are overrepresented also in positions P1' and P3'. The two enzymes differ clearly only in one position, the P2' residue, where mMCP-4 strongly prefers negatively charged amino acids while rMCP-1 favours Ser. Interestingly, Asp and Glu are often present in position P2' of known substrates for the human chymase. Overall, these two rodent beta-chymases have very similar amino acid preferences as the human chymase, particularly mMCP-4, which most likely have a very similar function as the human chymase. This finding indicates that rodent and primate connective tissue mast cells seem to have relatively similar proteolytic repertoires, although they express different sets of serine proteases.
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| 6. |
- Apcher, Sebastien, et al.
(författare)
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mRNA translation from an antigen presentation perspective: A tribute to the works of Nilabh Shastri
- 2022
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Ingår i: Molecular Immunology. - : Elsevier. - 0161-5890 .- 1872-9142. ; 141, s. 305-308
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Forskningsöversikt (refereegranskat)abstract
- The field of mRNA translation has witnessed an impressive expansion in the last decade. The once standard model of translation initiation has undergone, and is still undergoing, a major overhaul, partly due to more recent technical advancements detailing, for example, initiation at non-AUG codons. However, some of the pioneering works in this area have come from immunology and more precisely from the field of antigen presentation to the major histocompatibility class I (MHC-I) pathway. Despite early innovative studies from the lab of Nilabh Shastri demonstrating alternative mRNA translation initiation as a source for MHC-I peptide substrates, the mRNA translation field did not include these into their models. It was not until the introduction of the ribo-sequence technique that the extent of non-canonical translation initiation became widely acknowledged. The detection of peptides on MHC-I molecules by CD8 + T cells is extremely sensitive, making this a superior model system for studying alternative mRNA translation initiation from specific mRNAs. In view of this, we give a brief history on alternative initiation from an immunology perspective and its fundamental role in allowing the immune system to distinguish self from non-self and at the same time pay tribute to the works of Nilabh Shastri.
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| 7. |
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| 8. |
- Barbu, Andreea, et al.
(författare)
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The role of complement factor C3 in lipid metabolism
- 2015
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 67:1, s. 101-107
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Forskningsöversikt (refereegranskat)abstract
- Abundant reports have shown that there is a strong relationship between C3 and C3a-desArg levels, adipose tissue, and risk factors for cardiovascular disease, metabolic syndrome and diabetes. The data indicate that complement components, particularly C3, are involved in lipid metabolism. The C3 fragment, C3a-desArg, functions as a hormone that has insulin-like effects and facilitates triglyceride metabolism. Adipose tissue produces and regulates the levels of complement components, which promotes generation of inflammatory initiators such as the anaphylatoxins C3a and C5a. The anaphylatoxins trigger a cyto/chemokine response in proportion to the amount of adipose tissue present, and induce inflammation and mediate metabolic effects such as insulin resistance. These observations support the concept that complement is an important participant in lipid metabolism and in obesity, contributing to the metabolic syndrome and to the low-grade inflammation associated with obesity.
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| 9. |
- Barrios del Pino, Yvelise, et al.
(författare)
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Clonal repertoire diversification of a neutralizing cytomegalovirus glycoprotein B-specific antibody results in variants with diverse anti-viral properties.
- 2007
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 44:5, s. 680-690
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Tidskriftsartikel (refereegranskat)abstract
- Cytomegalovirus induces a chronic infection that in normal individuals is controlled by the immune system. In the case of humoral immunity, epitopes, in particular antigenic domain-1, in glycoprotein B have proven to be important for the induction of virus-neutralizing activity. Such antibodies can exert potent virus-neutralizing activity but can also block neutralizing antibodies from binding. Furthermore, these antibodies differ in their fine recognition of antigenic domain-1 as determined by epitope mapping. By using combinatorial library and phage display technologies we have now isolated a large array of clonally related antibody fragments to understand the origin of this diversity. This procedure allowed us to demonstrate that much of the diversity in functional activity (virus neutralization) and epitope recognition can arise from a single parental molecule through somatic mutation processes. We have thus demonstrated that the clonal diversification of a single antigen-specific clone can account for much of the diversity in antibody anti-viral activity. These findings have implications on the development of a gB-based subunit vaccine, as an effective vaccine preparation need not only to recruit appropriate clones into the immune response but also to evolve them properly so as to maintain an appropriate biological function.
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| 10. |
- Bergseth, Grethe, et al.
(författare)
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An international serum standard for application in assays to detect human complement activation products
- 2013
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 56:3 SI, s. 232-239
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Forskningsöversikt (refereegranskat)abstract
- The importance of the complement system in clinical medicine has become evident during the last decades and complement therapeutics has now reached the clinic. Thus, there is an increased interest in and need for assays to evaluate complement activity and dysfunction. Pathologically increased complement activation can indirectly be evaluated by quantification of complement components, but in order to exactly measure such activation, assays for quantification of products formed during activation are required. Progress in this field is hampered by lack of standardization. Therefore, members of the International Complement Standardization Committee, a joint initiative of the International Complement Society and the International Union of Immunological Societies (IUIS), prepared a defined standard for application in assays for complement activation products. We here report on the production and properties of this International Complement Standard #2 (ICS#2). ICS#2 was made from a pool of sera from healthy blood donors (ICS#1) that was activated with a combination of heat-aggregated IgG and zymosan, and subsequently stabilized by adding EDTA and nafamostat mesylate. The protocol was optimized to make the standard applicable in the following activation product assays: C1rs-C1-inhibitor complexes, C4a, C4bc, C4d, Bb, C3bBbP, C3a, C3bc, C3dg, C5a and the soluble terminal C5b-9 complement complex (SC5b-9, TCC). ICS#2 was defined as containing 1000 complement activation units (CAU)/mL for all activation products measured. All activation products were stable after 10 times thawing and freezing and most of the activation products were stable during storage at 4 degrees C for up to 21 days. ICS#2 was produced large-scale and is considered a valuable tool for standardization, calibration and reference control for complement activation assays, providing the necessary prerequisite for quality assessments between complement laboratories.
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