1.
Andersson, C, et al.
(author)
The three ZNT8 autoantibody variants together improve the diagnostic sensitivity of childhood and adolescent type 1 diabetes
2011
In: Autoimmunity. - : Taylor & Francis. - 0891-6934 .- 1607-842X. ; 44:5, s. 394-405
Journal article (peer-reviewed) abstract
Aims: We tested whether autoantibodies to all three ZnT8RWQ variants, GAD65, insulinoma-associated protein 2 (IA-2), insulin and autoantibodies to islet cell cytoplasm (ICA) in combination with human leukocyte antigen (HLA) would improve the diagnostic sensitivity of childhood type 1 diabetes by detecting the children who otherwise would have been autoantibody-negative.Methods: A total of 686 patients diagnosed in 1996–2005 in Skåne were analyzed for all the seven autoantibodies [arginin 325 zinc transporter 8 autoantibody (ZnT8RA), tryptophan 325 zinc transporter 8 autoantibody (ZnT8WA), glutamine 325 Zinc transporter 8 autoantibody (ZnT8QA), autoantibodies to glutamic acid decarboxylase (GADA), Autoantibodies to islet-antigen-2 (IA-2A), insulin autoantibodies (IAA) and ICA] in addition to HLA-DQ genotypes.Results: Zinc transporter 8 autoantibody to either one or all three amino acid variants at position 325 (ZnT8RWQA) was found in 65% (449/686) of the patients. The frequency was independent of age at diagnosis. The ZnT8RWQA reduced the frequency of autoantibody-negative patients from 7.5 to 5.4%—a reduction by 28%. Only 2 of 108 (2%) patients who are below 5 years of age had no autoantibody at diagnosis. Diagnosis without any islet autoantibody increased with increasing age at onset. DQA1-B1*X-0604 was associated with both ZnT8RA (p = 0.002) and ZnT8WA (p = 0.01) but not with ZnT8QA (p = 0.07). Kappa agreement analysis showed moderate (>0.40) to fair (>0.20) agreement between pairs of autoantibodies for all combinations of GADA, IA-2A, ZnT8RWQA and ICA but only slight ( < 0.19) agreement for any combination with IAA.Conclusions: This study revealed that (1) the ZnT8RWQA was common, independent of age; (2) multiple autoantibodies were common among the young; (3) DQA1-B1*X-0604 increased the risk for ZnT8RA and ZnT8WA; (4) agreement between autoantibody pairs was common for all combinations except IAA. These results suggest that ZnT8RWQA is a necessary complement to the classification and prediction of childhood type 1 diabetes as well as to randomize the subjects in the prevention and intervention of clinical trials.
2.
Brorsson, Caroline, et al.
(author)
Correlations between islet autoantibody specificity and the SLC30A8 genotype with HLA-DQB1 and metabolic control in new onset type 1 diabetes
2011
In: Autoimmunity. - : Taylor & Francis. - 0891-6934 .- 1607-842X. ; 44:2, s. 107-114
Journal article (peer-reviewed) abstract
We hypothesised that the correlation between autoantibody specificity for the ZnT8 Arg325Trp isoforms and the type 2 diabetes-associated rs13266634 may affect beta-cell function at type 1 diabetes (T ID) onset. To study this, we tested 482 newly diagnosed diabetic probands and 478 healthy siblings from the Danish population-based T1D registry for autoantibodies to ZnT8 (ZnT8A) in addition to GAD65 and IA-2. The prevalence and titres of autoantibodies were correlated with genotypes for rs13266634 and HLA-DQB1, age at diagnosis (AAD) and insulin dose-adjusted HbA1c (IDAA1c), as a proxy for residual beta-cell function. We replicated the correlation between rs13266634 genotypes and specificity for the ZnT8-Argenine (ZnT8R) and ZnT8-Tryptophan (ZnT8W) isoforms previously reported. ZnT8A overlapped substantially with autoantibodies to glutamate decarboxylase 65 (GADA) and IA-2 (IA-2A) and correlated significantly with IA-2A prevalence (p < 2e-16). No effect on IDAA1c was demonstrated for ZnT8A or rs13266634. We found a correlation between ZnT8R positivity and HLA-DQB1*0302 genotypes (p = 0.016), which has not been shown previously. Furthermore, significantly lower ZnT8R and GADA prevalence and titres was found among probands with AAD < 5 years (prevalence: p = 0.004 and p = 0.0001; titres: p = 0.002 and p = 0.001, respectively). The same trend was observed for IA-2A and ZnT8W; however, the difference was non-significant. Our study confirms ZnT8 as a major target for autoantibodies at disease onset in our Danish T1D cohort of children and adolescents, and we have further characterised the relationship between autoantibody specificity for the ZnT8 Arg325Trp epitopes and rs13266634 in relation to established autoantibodies, AAD, measures of beta-cell function and HLA-DQB1 genotypes in T1D.
3.
Kjellerås, Jennifer, et al.
(author)
Improved efficacy by using the pTnT-rhtTG plasmid for the detection of celiac disease specific tissue transglutaminase autoantibodies in radioligand binding assays
2011
In: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa Healthcare. - 0036-5513 .- 1502-7686. ; 71:8, s. 701-704
Journal article (peer-reviewed) abstract
Background: Tissue transglutaminase (tTG) autoantibodies are serological markers for celiac disease. The aim was to study the efficacy of the pTnT-rhtTG plasmid and subsequent diagnostic accuracy of tTG autoantibodies for childhood celiac disease using radioligand binding assays.Methods: Coupled in vitro transcription and translation of tTG were performed by pTnT-rhtTG as well as by the pGEMt Easy-rhtTG vectors using the TNT SP6 Coupled Reticulocyte Lysate System in the presence of [(35)S] methionine. Sera from 190 celiac disease children and 74 controls were measured for tTG autoantibodies in two separate radioligand binding assays using anti-human IgA agarose and protein A sepharose beads for the detection of IgA-tTG and IgG-tTG, respectively.Results: Median incorporation of [(35)S] methionine into the pTnT-rhtTG was 26% compared to 16% for the pGEMt Easy-rhtTG plasmid (p = 0.0016). Using pTnT-rhtTG (as compared to pGEMt Easy-rhtTG), sensitivities were IgA-tTG = 96.3% (95.7%) and IgG-tTG = 95.8% (97.3%) and specificities were IgA-tTG = 91.9% (90.5%) and IgG-tTG = 94.6% (98.4%). According to receiver operator characteristics for the pTnT (pGEMt Easy) assays, area under the curves were IgA-tTG = 98.4% (98.4%) and IgG-tTG = 97.7% (97.2%), respectively.Conclusion: The pTnT-rhtTG plasmid increased the efficacy of tTG antigen usage without reducing the diagnostic accuracy of IgA-tTG and IgG-tTG for childhood celiac disease. The pTnT-rhtTG plasmid is therefore recommended over the pGEMt Easy-rhtTG for the assessment of IgA-tTG and IgG-tTG using radioligand binding assays.
4.
Bjermo, Helena, 1981-
(author)
Dietary Fatty Acids and Inflammation : Observational and Interventional Studies
2011
Doctoral thesis (other academic/artistic) abstract
Dietary fat quality influences the risk of type 2 diabetes and cardiovascular disease. A low-grade inflammation is suggested to contribute to the disease development, often accompanied by obesity. Whereas n-3 polyunsaturated fatty acids (PUFA) have been considered anti-inflammatory, n-6 PUFA have been proposed to act pro-inflammatory. Saturated fatty acids (SFA) act pro-inflammatory in vitro. This thesis aimed to investigate effects of different fatty acids on low-grade inflammation in observational and interventional studies. In Paper I and II, fatty acid composition in serum cholesterol esters was used as objective marker of dietary fat quality and related to serum C-reactive protein (CRP) and other circulating inflammatory markers in two population-based cohorts, conducted in middle-aged men and elderly men and women, respectively. In Paper III and IV, the impact of diets differing in fat quality on inflammation and oxidative stress was investigated in randomised controlled studies, in subjects with metabolic syndrome and abdominal obesity. In Paper I and II, a low proportion of linoleic acid (18:2 n-6) in serum was associated with higher CRP concentrations, indicating that a low intake of vegetable fats may be related to low-grade inflammation. High CRP concentrations were also associated with high proportions of palmitoleic (16:1) and oleic (18:1) acids and high stearoyl coenzymeA desaturase index, possibly reflecting altered fat metabolism and/or high SFA intake in this population. When comparing two high-fat diets rich in either saturated or monounsaturated fat, and two low-fat diets with or without long-chain n-3 PUFA supplementation during 12 weeks (Paper III), no differences in inflammation or oxidative stress markers were observed. Moreover, a 10-week intervention (Paper IV) with high linoleic acid intake showed no adverse effects on inflammation or oxidative stress. Instead, interleukin-1 receptor antagonist and tumor necrosis factor receptor-2 decreased after linoleic acid intake compared with a diet high in SFA. The results in this thesis indicate that dietary n-6 PUFA found in vegetable fats is associated with lower inflammation marker levels, and to some extent reduces systemic inflammation when compared with SFA. Supplementation of n-3 PUFA did not exert any systemic anti-inflammatory effects, maybe due to a relatively low dose.
5.
Rutemark, Christian, et al.
(author)
Requirement for complement in antibody responses is not explained by the classic pathway activator IgM
2011
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:43, s. 17589-17590
Journal article (peer-reviewed) abstract
Animals lacking complement factors C1q, C2, C3, or C4 have severely impaired Ab responses, suggesting a major role for the classic pathway. The classic pathway is primarily initiated by antigen-Ab complexes. Therefore, its role for primary Ab responses seems paradoxical because only low amounts of specific Abs are present in naive animals. A possible explanation could be that the classic pathway is initiated by IgM from naive mice, binding with sufficient avidity to the antigen. To test this hypothesis, a knock-in mouse strain, Cμ13, with a point mutation in the gene encoding the third constant domain of the μ-heavy chain was constructed. These mice produce IgM in which proline in position 436 is substituted with serine, a mutation previously shown to abrogate the ability of mouse IgM to activate complement. Unexpectedly, the Ab response to sheep erythrocytes and keyhole limpet hemocyanin in Cμ13 mice was similar to that in WT mice. Thus, although secreted IgM and the classic pathway activation are both required for the normal primary Ab response, this does not require that IgM activate C. This led us to test Ab responses in animals lacking one of three other endogenous activators of the classic pathway: specific intracellular adhesion molecule-grabbing nonintegrin R1, serum amyloid P component, and C-reactive protein. Ab responses were also normal in these animals.
6.
7.
Courtin, David, et al.
(author)
G6PD A-variant influences the antibody responses to Plasmodium falciparum MSP2.
2011
In: Infection, Genetics and Evolution. - : Elsevier BV. - 1567-1348 .- 1567-7257. ; 11:6, s. 1287-1292
Journal article (peer-reviewed) abstract
High antibody levels directed to Plasmodium falciparum merozoite surface proteins (MSP), including MSP2, as well as genetically related red blood cell defects, have previously been found to be associated with protection against malaria. Here, our main objective was to study the changes in MSP2-specific total IgG, IgG1 and IgG3 responses during a malaria transmission season in order to assess the impact of sickle-cell, α(+)-thalassemia and G6PD variants on antibody kinetics. Repeated parasitological assessments of a cohort of children were conducted during an 8-month period. Antibody responses to recombinant MSP2/3D7 and MSP2/FC27 proteins were measured at the beginning and at the end of transmission season. We found that (i) the period of last Plasmodium falciparum infection during the transmission season was associated with IgG3 anti-MSP2 change. Compared to the IgG3 levels of children infected in January 2003 (end of transmission season), the IgG3 level of children decreased with the length of the period without infection, (ii) G6PD A- carriers had a lower increase of IgG3 levels to MSP2/FC27 and MSP2/3D7 during the transmission season than the noncarriers. This latter finding is suggestive of qualitative and/or quantitative reduction of exposure to malarial antigens related to this genetic variant, leading to weaker stimulation of specific antibody responses. We speculate that cell-mediated immune activity may explain the clinical protection afforded by this genetic trait.
8.
Giusti, Pablo, et al.
(author)
Plasmodium falciparum-infected erythrocytes and beta-hematin induce partial maturation of human dendritic cells and increase their migratory ability in response to lymphoid chemokines.
2011
In: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 79:7, s. 2727-2736
Journal article (peer-reviewed) abstract
Acute and chronic Plasmodium falciparum infections alter the immune competence of the host possibly through changes in dendritic cell (DC) functionality. DCs are the most potent activators of T cells, and migration is integral to their function. Mature DCs express lymphoid chemokine receptors (CCRs), expression of which enables them to migrate to the lymph nodes, where they encounter naïve T cells. The present study aimed to investigate the impact of the synthetic analog to malaria parasite pigment hemozoin, i.e., β-hematin, or infected erythrocytes (iRBCs) on the activation status of human monocyte-derived DCs and on their expression of CCRs. Human monocyte-derived DCs partially matured upon incubation with β-hematin as indicated by an increased expression of CD80 and CD83. Both β-hematin and iRBCs provoked the release of proinflammatory and anti-inflammatory cytokines, such as interleukin-6 (IL-6), IL-10, and tumor necrosis factor alpha, but not IL-12, and induced upregulation of the lymphoid chemokine receptor CXCR4, which was coupled to an increased migration to lymphoid ligands. Taken together, these results suggest that the partial and transient maturation of human myeloid DCs upon stimulation with malaria parasite-derived products and the increased IL-10 but lack of IL-12 secretion may lead to suboptimal activation of T cells. This may in turn lead to impaired adaptive immune responses and therefore insufficient clearance of the parasites.
9.
Simone, Olivia, et al.
(author)
TLRs innate immunereceptors and Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) CIDR1α-driven human polyclonal B-cell activation.
2011
In: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 119:2-3, s. 144-150
Journal article (peer-reviewed) abstract
Chronic malaria severely affects the immune system and causes polyclonal B-cell activation, as evidenced by the presence of hypergammaglobulinemia, elevated levels of autoantibodies, loss of B-cell memory and the frequent occurrence of Burkitt's lymphomas (BL) in children living in malaria endemic areas. Previous studies have shown that the cysteine-rich interdomain region 1α (CIDR1α) of the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) of the FCR3S1.2 strain, subsequently named CIDR1α, interacts with B cells partially through the binding to the B-cell receptor (BCR). This interaction leads to an activated phenotype, increased survival, and a low degree of proliferation. CIDR1α preferentially activates the memory B-cell compartment, therefore PfEMP1 is considered to act as a polyclonal B-cell activator and its role in memory maintenance has been suggested. In this report, we extend the analysis of the PfEMP1-CIDR1α B-cell interaction and demonstrate that PfEMP1-CIDR1α increases the expression of TLR7 and TLR10 mRNA transcripts and sensitizes B cells to TLR9 signalling via the MyD88 adaptor molecule. Furthermore, despite its ability to bind to surface Igs, PfEMP1-CIDR1α-induced B-cell activation does not seem to proceed through the BCR, since it does not induce Lyn and/or phospho-tyrosine mediated signalling pathways. Rather PfEMP1-CIDR1α induces the phosphorylation of downstream kinases, such as ERK1/2, p38 and IKBα, in human B cells. These findings indicate that PfEMP1-CIDR1α induces a persistent activation of B cells, which in turn can contribute to the exhaustion and impairment of B-cell functions during chronic malaria infection.
10.
Vaziri Sani, Fariba, et al.
(author)
A novel triple mix radiobinding assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes
2011
In: JIM - Journal of Immunological Methods. - : Elsevier. - 0022-1759 .- 1872-7905. ; 371:1-2, s. 25-37
Journal article (peer-reviewed) abstract
Background and aims: Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoantigen at amino acid position 325 representing ZnT8-R (Arginine), ZnT8-W (Tryptophan) and ZnT8-Q (Glutamin). The aims of the study were: 1) to develop an autoantigen triple mix Radio-Binding Assay (RBA) for ZnT8A: 2) to identify the individual ZnT8-R,-W,-QA reactivity and 3) to validate the triple mix ZnT8A RBA in children with newly diagnosed T1D. less thanbrgreater than less thanbrgreater thanMethods: Serum samples were obtained from 2664 (56% males, n = 1436) patients in the Swedish nationwide Better Diabetes Diagnosis (BDD) study representing patients with T1D (97%, n = 2582), T2D (1.7%, n = 46), MODY (1.0%, n = 28) and secondary diabetes (0.3%, n = 8). cDNA coding for the C-terminal end of each variant was prepared by site-directed mutagenesis and subcloned into a high efficiency in vitro transcription translation vector. The ZnT8 variants were labeled with 35S-methionine and used in a standard RBA separating free from autoantibody-bound autoantigen with Protein A-Sepharose. less thanbrgreater than less thanbrgreater thanResults: ZnT8-TripleA was detected in 1678 (65%) patients with T1D, 4 (9%) T2D, 3 (11%) MODY and in none (0%) of the patients with secondary diabetes. Among the T1D patients ZnT8-RA was detected in 1351 (52%) patients, ZnT8-WA in 1209(47%) and ZnT8-QA in 790(31%) demonstrating that 1661 (64%) had one or several ZnT8A. The ZnT8-TripleA assay showed a false positive rate of 1.9% (n = 49). Only 1.2% (n = 32) of the T1D patients were false negative for ZnT8-TripleA compared to 0/46(0%) of the T2D patients. The precision (intra assay CV) and reproducibility (inter assay CV) of the ZnT8-TripleA assay did not differ from the RBA of the individual ZnT8 variants. less thanbrgreater than less thanbrgreater thanConclusion: We conclude that the ZnT8-TripleA assay had low false positive and false negative rates. The ZnT8-TripleA assay would therefore be highly suitable not only to analyze patient with newly diagnosed diabetes but also for screening the general population since this assay demonstrated high sensitivity and very high specificity.
