George A. Werther

Linkage disequilibrium of a type 1 diabetes susceptibility locus with a regulatory IL12B allele

Type 1 diabetes (T1D; or insulin-dependent diabetes mellitus, IDDM) is an autoimmune disease with both genetic and environmental components. In addition to the human leukocyte antigen (HLA) complex, the single major genetic contributor of susceptibility, an unknown number of other unidentified genes are required to mediate disease. Although many loci conferring susceptibility to T1D have been mapped, their identification has proven problematic due to the complex nature of this disease. Our strategy for finding T1D susceptibility genes has been to test for human homologues of loci implicated in diabetes-prone NOD (non-obese diabetic) mice, together with application of biologically relevant stratification methods. We report here a new susceptibility locus, IDDM18, located near the interleukin-12 (IL-12)p40 gene, IL12B. Significant bias in transmission of IL12B alleles was observed in affected sibpairs and was confirmed in an independent cohort of simplex families. A single base change in the 3′ UTR showed strong linkage disequilibrium with the T1D susceptibility locus. The IL12B 3′ UTR alleles showed different levels of expression in cell lines. Variation in IL-12p40 production may influence T-cell responses crucial for either mediating or protecting against this and other autoimmune diseases.

Central Nervous System Function in Youth With Type 1 Diabetes 12 Years After Disease Onset

OBJECTIVE—In this study, we used neurocognitive assessment and neuroimaging to examine brain function in youth with type 1 diabetes studied prospectively from diagnosis. RESEARCH DESIGN AND METHODS—We studied type 1 diabetic (n = 106) and control subjects (n = 75) with no significant group difference on IQ at baseline 12 years previously by using the Wechsler Abbreviated Scale of General Intelligence, magnetic resonance spectroscopy and imaging, and metabolic control data from diagnosis. RESULTS—Type 1 diabetic subjects had lower verbal and full scale IQs than control subjects (both P < 0.05). Type 1 diabetic subjects had lower N-acetylaspartate in frontal lobes and basal ganglia and higher myoinositol and choline in frontal and temporal lobes and basal ganglia than control subjects (all P < 0.05). Type 1 diabetic subjects, relative to control subjects, had decreased gray matter in bilateral thalami and right parahippocampal gyrus and insular cortex. White matter was decreased in bilateral parahippocampi, left temporal lobe, and middle frontal area (all P < 0.0005 uncorrected). T2 in type 1 diabetic subjects was increased in left superior temporal gyrus and decreased in bilateral lentiform nuclei, caudate nuclei and thalami, and right insular area (all P < 0.0005 uncorrected). Early-onset disease predicted lower performance IQ, and hypoglycemia was associated with lower verbal IQ and volume reduction in thalamus; poor metabolic control predicted elevated myoinositol and decreased T2 in thalamus; and older age predicted volume loss and T2 change in basal ganglia. CONCLUSIONS—This study documents brain effects 12 years after diagnosis in a type 1 diabetic sample whose IQ at diagnosis matched that of control subjects. Findings suggest several neuropathological processes including gliosis, demyelination, and altered osmolarity.

Co-ordinated and cellular specific induction of the components of the IGF/IGFBP axis in the rat brain following hypoxic-ischemic injury

Insulin-like growth factor 1 (IGF-1) is induced after hypoxic-ischemic (HI) brain injury, and therapeutic studies suggest that IGF-1 may restrict delayed neuronal and glial cell loss. We have used a well-characterised rat model of HI injury to extend our understanding of the modes of action of the IGF system after injury. The induction of the IGF system by injury was examined by in situ hybridization, immunohistochemistry, Northern blot analysis, RNase protection assay and reverse transcriptase-polymerase chain reaction (RT-PCR). IGF-1 accumulated in blood vessels of the damaged hemisphere within 5 h after a severe injury. By 3 days, IGF-1 mRNA was expressed by reactive microglia in regions of delayed neuronal death, and immunoreactive IGF-1 was associated with these microglia and reactive astrocytes juxtaposed to surviving neurones surrounding the infarct. Total IGF-1 receptor mRNA was unchanged by the injury. IGFBP-2 mRNA was strongly induced in reactive astrocytes throughout the injured hemisphere, and IGFBP-3 and IGFBP-5 mRNA were moderately induced in reactive microglia and neurones of the injured hippocampus, respectively. IGFBP-6 mRNA was induced in the damaged hemisphere by 3 days and increased protein was seen on the choroid plexus, ependyma and reactive glia. In contrast, insulin II was not induced. These results indicate cell type-specific expression for IGF-1, IGFBP-2,3,5 and 6 after injury. Our findings suggest that the IGF-1 produced by microglia after injury is transferred to perineuronal reactive astrocytes expressing IGFBP-2. Thus, modulation of IGF-1 action by IGFBP-2 might represent a key mechanism that restricts neuronal cell loss following HI brain injury.

Psychiatric morbidity and health outcome in Type 1 diabetes--perspectives from a prospective longitudinal study.

Aims  To describe psychiatric status and relationship to metabolic control in adolescents with Type 1 diabetes studied prospectively from diagnosis.

Neuropsychological Complications of IDDM in Children 2 Years After Disease Onset

OBJECTIVE To compare the neuropsychological profiles of children with IDDM with a community control group at two time points: 3 months after disease onset and 2 years after the baseline assessment. RESEARCH DESIGN AND METHODS A total of 123 children (age 3–14 years) with recent IDDM onset were compared with 129 community control subjects, stratified for age and sex, on standardized measures of general intelligence, attention, speed of processing, memory, learning, executive skills, and behavioral adjustment soon after diagnosis and 2 years later. Exclusion criteria were premorbid evidence of central nervous system disease or trauma, or English not spoken in the home. RESULTS There were no differences between children with IDDM and control subjects on any measure at the initial assessment 3 months after disease onset. Two years later, children with IDDM tended to show a less positive change, relative to control subjects, in their standardized scores on measures of general intelligence, and significantly so on the vocabulary (P < 0.01) and block design (P < 0.05) subtests. Multivariate group differences were also apparent on speed of processing (P < 0.05) and learning (P < 0.01) subtests, reflecting smaller developmental gains in the children with IDDM when compared with control subjects. CONCLUSIONS The findings are consistent with previous reports, suggesting that IDDM is associated with an increased risk of mild neuropsychological dysfunction. The skills most affected in this cohort were information processing speed, acquisition of new knowledge, and conceptual reasoning abilities. Clinicians and educators should be made aware of the risk of specific neuropsychological deficits in children with IDDM.

Age-specific stabilization in obesity prevalence in German children: A cross-sectional study from 1999 to 2008

OBJECTIVE Trends of overweight (ov)/obesity (ob) prevalence among German children aged 4-16 years were studied between 1999 and 2008. SUBJECTS Body mass index (BMI) data (>P90 [ov] and >P97 [ob]) from the national CrescNet database were analysed in three age groups: 4-7.99, 8-11.99, and 12-16 years. RESULTS Trend analyses. Data from 272 826 children were analyzed. a) Whole study population aged 4-16 years old. A significant upward trend for ov/ob prevalence was found between 1999 and 2003, and a significant downward trend between 2004 and 2008. b) Subgroup analyses. Ov/Ob prevalence increased in most subgroups studied until 2004. Between 2004 and 2008, a downward trend for ov/ob prevalence was found in children, aged 4-7.99 years, whereas it stabilized in most other subgroups studied. Cross-sectional analyses. Data from 93 028 children were analyzed. Ov/ob prevalence was significantly higher in 2004 compared with 2000 in girls aged 12-16 years and in boys aged 8-16 years. Ov/ob obesity prevalence was significantly lower in 2008 compared with 2004 in children aged 4-7.99 years. CONCLUSION Ov/ob prevalence increased between 1999 and 2003 in German children. Since 2004, this trend has been stabilizing or turning into a downward trend. Our data confirm the global trend of stabilizing prevalence rates of childhood obesity at a high level and add important information for individual age groups. Intervention programs targeted to prevent childhood obesity may have had beneficial effects, and a new balance between factors favouring obesity and those favouring leanness may have been reached recently. Age- and gender-specific differences found in trends of ov/ob prevalence may help optimise preventive and therapeutic measures.

Endogenous IGF-1 regulates the neuronal differentiation of adult stem cells.

Stem cells from the adult forebrain of mice were stimulated to form clones in vitro using fibroblast growth factor‐2 (FGF‐2). At concentrations above 10 ng/ml of FGF‐2, very few clones gave rise to neurons; however, if FGF‐2 was removed after 5 days, 20–30% of clones subsequently gave rise to neurons. The number of neuron‐containing clones and the number of neurons per clone was significantly enhanced, if insulin‐like growth factor (IGF)‐1 or heparin were added subsequent to FGF‐2 removal. The spontaneous production of neurons after FGF‐2 removal was shown to be due to endogenous IGF‐1, since antibodies to IGF‐1 and an IGF‐1 binding protein totally inhibited neuronal production. Similarly, these reagents also abrogated the neuron‐promoting effects of heparin. Thus, it appears that endogenous IGF‐1 may be a major regulator of stem cell differentiation into neurons. Furthermore, it was found that high levels of IGF‐1 or insulin promoted the maturation and affected the neurotransmitter phenotype of the neurons generated. J. Neurosci. Res. 59:332–341, 2000

Insulin-like growth factors and the developing and mature rat small intestine: receptors and biological actions.

To determine if insulin-like growth factor-I (IGF-I) or multiplication stimulating activity (MSA, rat IGF-II) might directly influence small intestinal epithelium, we studied the distribution of IGF binding sites during development of the rat intestine. Cell membranes from suckling rat mucosa bound 2-6 times as much 125I-IGF-I and 3-5 times as much 125I-MSA as did adult membranes. Isolated villus cells from suckling and adult rats specifically bound both IGFs. IGF-I binding tended to remain high during suckling, whereas MSA binding fell progressively from the early suckling period. Competitive displacement studies with insulin, IGF-I and MSA demonstrated the presence of type-I and type-II IGF receptors. In vitro autoradiography of 125I-IGF-I binding sites in adult and suckling rat jejunum showed highest binding in the submucosa with extensions up into the lamina propria. Immunocytochemical localization of type-II receptors showed highest density in villus epithelium and vessel walls. Administration of MSA by oral and IGF-I by oral and parenteral routes (1 microgram/day for 6 days) to suckling rats stimulated jejunal brush border enzymes, but not intestinal growth. Developmental changes in receptor density and effects on brush border enzymes suggest a specific role for IGFs in post-natal development of the rat intestine.

Reversal of epidermal hyperproliferation in psoriasis by insulin-like growth factor I receptor antisense oligonucleotides.

Epidermal hyperplasia is a key feature of the common skin disorder psoriasis. Stimulation of epidermal keratinocytes by insulin-like growth factor I (IGF-I) is essential for cell division, and increased sensitivity to IGF-I may occur in psoriasis. We hypothesized that inhibition of IGF-I receptor expression in the psoriasis lesion would reverse psoriatic epidermal hyperplasia by slowing the rate of keratinocyte cell division. Here we report the use of C5-propynyl-dU,dC-phosphorothioate antisense oligonucleotides to inhibit IGF-I receptor expression in keratinocytes. We identified several inhibitory antisense oligonucleotides and demonstrated IGF-I receptor inhibition in vitro through an mRNA targeting mechanism. Repeated injection of these oligonucleotides into human psoriasis lesions, grafted onto nude mice, caused a dramatic normalization of the hyperplastic epidermis. The findings indicate that IGF-I receptor stimulation is a rate-limiting step in psoriatic epidermal hyperplasia and that IGF-I receptor targeting by cutaneous administration of antisense oligonucleotides forms the basis of a potential new psoriasis therapy.

Neuropsychological profiles of young people with type 1 diabetes 12 yr after disease onset

Lin A, Northam EA, Rankins D, Werther GA, Cameron FJ. Neuropsychological profiles of young people with type 1 diabetes 12 yr after disease onset.