Incomplete immune response to coxsackie B viruses associates with early autoimmunity against insulin.

Viral infections are associated with autoimmunity in type 1 diabetes. Here, we asked whether this association could be explained by variations in host immune response to a putative type 1 etiological factor, namely coxsackie B viruses (CVB). Heterogeneous antibody responses were observed against CVB capsid proteins. Heterogeneity was largely defined by different binding to VP1 or VP2. Antibody responses that were anti-VP2 competent but anti-VP1 deficient were unable to neutralize CVB, and were characteristic of children who developed early insulin-targeting autoimmunity, suggesting an impaired ability to clear CVB in early childhood. In contrast, children who developed a GAD-targeting autoimmunity had robust VP1 and VP2 antibody responses to CVB. We further found that 20% of memory CD4(+) T cells responding to the GAD65247-266 peptide share identical T cell receptors to T cells responding to the CVB4 p2C30-51 peptide, thereby providing direct evidence for the potential of molecular mimicry as a mechanism for GAD autoimmunity. Here, we highlight functional immune response differences between children who develop insulin-targeting and GAD-targeting autoimmunity, and suggest that children who lose B cell tolerance to insulin within the first years of life have a paradoxical impaired ability to mount humoral immune responses to coxsackie viruses.

Tetraspanin 7 autoantibodies in type 1 diabetes.

AIMS/HYPOTHESIS: Autoantibodies to pancreatic beta cell proteins are markers of asymptomatic type 1 diabetes. The aim was to determine whether autoantibodies to the beta cell protein tetraspanin 7 would improve the ability to identify autoimmunity against pancreatic beta cells. METHODS: Full length and external domain fragments of tetraspanin 7 were expressed as luciferase-tagged fusion proteins and used in immunoprecipitation assays to measure autoantibodies in samples from 363 patients with type 1 diabetes at onset of disease, 503 beta cell autoantibody negative first-degree relatives of patients, and 212 relatives with autoantibodies to insulin, glutamic acid decarboxylase, insulinoma antigen 2 or zinc transporter 8. RESULTS: Antibody binding was observed against the full length and external domains of tetraspanin 7, and was strongest against the full length protein. Autoantibodies that could be inhibited by untagged tetraspanin 7 were detected in 5 (1%) of 503 autoantibody negative relatives, 3 (3.2%) of 94 autoantibody negative patients, 95 (35.3%) of 269 autoantibody positive patients, 1 (1%) of 98 single autoantibody positive relatives and 25 (21.9%) of 114 multiple autoantibody positive relatives. Progression to diabetes did not differ between multiple autoantibody positive relatives with and without tetraspanin 7 autoantibodies. CONCLUSIONS/INTERPRETATION: Tetraspanin 7 is an autoantigen in type 1 diabetes. Tetraspanin 7 autoantibodies are a marker of type 1 diabetes, but provide minor additional value to existing autoantibodies in identifying beta cell autoimmunity.

Isolation of human monoclonal autoantibodies derived from pancreatic lymph node and peripheral blood B cells of islet autoantibody-positive patients.

AIMS/HYPOTHESIS: Autoantibodies against pancreatic islets and infections by enteroviruses are associated with type 1 diabetes, but the specificity of immune responses within the type 1 diabetic pancreas is poorly characterised. We investigated whether pancreatic lymph nodes could provide a source of antigen-specific B cells for analysis of immune responses within the (pre)diabetic pancreas. METHODS: Human IgG antibodies were cloned from single B lymphocytes sorted from pancreatic lymph node cells of three organ donors positive for islet autoantibodies, and from the peripheral blood of a patient with type 1 diabetes. Antibodies to insulinoma-associated antigen 2 (IA-2), GAD65, zinc transporter 8 (ZnT8) and Coxsackie B virus proteins were assayed by immunoprecipitation and by immunofluorescence on pancreatic sections. RESULTS: Human IgG antibodies (863) were successfully cloned and produced from 4,092 single B cells from lymph nodes and peripheral blood. Reactivity to the protein tyrosine phosphatase domain of the IA-2 autoantigen was detected in two cloned antibodies: one derived from a pancreatic lymph node and one from peripheral blood. Epitopes for these two antibodies were similar to each other and to those for circulating antibodies in type 1 diabetes. The remaining 861 antibodies were negative for reactivity to IA-2, GAD65 or ZnT8 by both assays tested. Reactivity to a Coxsackie viral protein 2 was detected in one antibody derived from a peripheral blood B cell, but not from lymph nodes. CONCLUSIONS/INTERPRETATION: We show evidence for the infrequent presence of autoantigen-specific IgG+ B lymphocytes in the pancreatic-draining lymph nodes of islet autoantibody-positive individuals.

Macroinvertebrate responses to constructed riffles in the Cache River, Illinois, USA.

Stream restoration practices are becoming increasingly common, but biological assessments of these improvements are still limited. Rock weirs, a type of constructed riffle, were implemented in the upper Cache River in southern Illinois, USA, in 2001 and 2003--2004 to control channel incision and protect high quality riparian wetlands as part of an extensive watershed-level restoration. Construction of the rock weirs provided an opportunity to examine biological responses to a common in-stream restoration technique. We compared macroinvertebrate assemblages on previously constructed rock weirs and newly constructed weirs to those on snags and scoured clay streambed, the two dominant substrates in the unrestored reaches of the river. We quantitatively sampled macroinvertebrates on these substrates on seven occasions during 2003 and 2004. Ephemeroptera, Plecoptera, and Trichoptera (EPT) biomass and aquatic insect biomass were significantly higher on rock weirs than the streambed for most sample periods. Snags supported intermediate EPT and aquatic insect biomass compared to rock weirs and the streambed. Nonmetric multidimensional scaling (NMDS) ordinations for 2003 and 2004 revealed distinct assemblage groups for rock weirs, snags, and the streambed. Analysis of similarity supported visual interpretation of NMDS plots. All pair-wise substrate comparisons differed significantly, except recently constructed weirs versus older weirs. Results indicate positive responses by macroinvertebrate assemblages to in-stream restoration in the Cache River. Moreover, these responses were not evident with more common measures of total density, biomass, and diversity.