Immunological biomarkers: catalysts for translational advances in autoimmune diabetes

In a recent workshop organized by the JDRF focused on the 'Identification and Utilization of Robust Biomarkers in Type1 Diabetes', leaders in the field of type 1 diabetes (T1D)/autoimmunity and assay technology came together from academia, government and industry to assess the current state of the field, evaluate available resources/technologies and identify gaps that need to be filled for moving the field of T1D research forward. The highlights of this workshop are discussed in this paper, as well as the proposal for a larger, planned consortium effort, incorporating a JDRF Biomarker Core, to foster collaboration and accelerate progress in this critically needed area of T1D research.

Teplizumab treatment may improve C-peptide responses in participants with type 1 diabetes after the new-onset period: a randomised controlled trial

AIMS/HYPOTHESIS

Type 1 diabetes results from a chronic autoimmune process continuing for years after presentation. We tested whether treatment with teplizumab (a Fc receptor non-binding anti-CD3 monoclonal antibody), after the new-onset period, affects the decline in C-peptide production in individuals with type 1 diabetes.

METHODS

In a randomised placebo-controlled trial we treated 58 participants with type 1 diabetes for 4-12 months with teplizumab or placebo at four academic centres in the USA. A central randomisation centre used computer generated tables to allocate treatments. Investigators, patients, and caregivers were blinded to group assignment. The primary outcome was a comparison of C-peptide responses to a mixed meal after 1 year. We explored modification of treatment effects in subgroups of patients.

RESULTS

Thirty-four and 29 subjects were randomized to the drug and placebo treated groups, respectively. Thirty-one and 27, respectively, were analysed. Although the primary outcome analysis showed a 21.7% higher C-peptide response in the teplizumab-treated group (0.45 vs 0.371; difference, 0.059 [95% CI 0.006, 0.115] nmol/l) (p = 0.03), when corrected for baseline imbalances in HbA(1c) levels, the C-peptide levels in the teplizumab-treated group were 17.7% higher (0.44 vs 0.378; difference, 0.049 [95% CI 0, 0.108] nmol/l, p = 0.09). A greater proportion of placebo-treated participants lost detectable C-peptide responses at 12 months (p = 0.03). The teplizumab group required less exogenous insulin (p < 0.001) but treatment differences in HbA(1c) levels were not observed. Teplizumab was well tolerated. A subgroup analysis showed that treatment benefits were larger in younger individuals and those with HbA(1c) <6.5% at entry. Clinical responders to teplizumab had an increase in circulating CD8 central memory cells 2 months after enrolment compared with non-responders.

CONCLUSIONS/INTERPRETATIONS

This study suggests that deterioration in insulin secretion may be affected by immune therapy with teplizumab after the new-onset period but the magnitude of the effect is less than during the new-onset period. Our studies identify characteristics of patients most likely to respond to this immune therapy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00378508

FUNDING

This work was supported by grants 2007-502, 2007-1059 and 2006-351 from the JDRF and grants R01 DK057846, P30 DK20495, UL1 RR024139, UL1RR025780, UL1 RR024131 and UL1 RR024134 from the NIH.

Relapsing and remitting severe hypoglycemia due to a monoclonal anti-insulin antibody heralding a case of multiple myeloma

CONTEXT

We report a novel case of insulin autoimmune syndrome (IAS) presenting with hypoglycemia due to production of a monoclonal anti-insulin antibody in a patient subsequently found to have multiple myeloma (MM).

OBJECTIVE

The aim of the study was to describe the 5-yr clinical course of a patient with IAS and MM and to characterize the origin and function of the pathogenic antibody.

METHODS

We conducted a longitudinal case history with laboratory investigations to characterize the anti-insulin antibody subtype, specificity, affinity, and origin.

RESULTS

The patient presented with IAS, which worsened during treatment of hepatitis C. The patient was then discovered to have a monoclonal gammopathy that progressed to MM. Treatment of the MM induced remission of the neoplasia and IAS, which then followed a synchronized course of progression and response to therapy. An anti-insulin IgG(3)-λ that bound specifically but with low affinity to the insulin B chain (amino acids 9-30) and that was distinct from the primary MM IgG(3)-κ clone was recovered from the patient and cloned. The antibody bound insulin and showed mutations of normal affinity maturation.

CONCLUSIONS

We describe a case of MM heralded by IAS, where full characterization of the pathogenic antibody revealed that the monoclonal anti-insulin antibody had originated from a self-reactive clone.

Analysis of human biologics with a mouse skin transplant model in humanized mice

Preclinical testing of human therapeutic monoclonal antibodies has been limited in murine models due to species differences in pharmacokinetics and biologic responses. To overcome these constraints we developed a murine skin transplant model in humanized mice and used it to test human monoclonal antibody therapy. Neonatal NOD/SCID/IL2Rγc(null) mice (NSG) were reconstituted with human CD34(+) hematopoietic stem cells (hNSG). When adult, these mice rejected MHC mismatched murine C57BL/6J skin grafts. Rejection required adequate reconstitution with human cells. There was diffuse infiltration of the epidermis and dermis with hCD8 and hCD4 cells in rejected grafts by immunohistochemistry. Studies with B6/MHC class I and II knockout mice donors indicated that neither is required for rejection. Graft rejection was associated with the development of effector and central memory T cells and an increase in serum immunoglobulins. We also tested the effects of teplizumab (anti-CD3 mAb) and found it could delay skin graft rejection, whereas ipilimumab (anti-CTLA-4 [cytotoxic T-lymphocyte antigen-4] mAb) treatment accelerated rejection. These findings demonstrate that hNSG mice reliably and predictably reject a xenogenic mouse skin graft by a human T cell mediated mechanism. The model can be utilized to investigate the ability of human immunotherapies to enhance or suppress functional human immune responses.

High bone turnover in Irish professional jockeys

SUMMARY

Professional jockeys are routinely exposed to high impact trauma and sustain fractures frequently. We found that jockeys restrict their caloric intake in order to maintain regulation weights, and that bone turnover is high. There are significant health and safety implications for the racing industry.

INTRODUCTION

Professional jockeys routinely sustain fractures from high impact falls. Jockeys maintain a low percentage body fat and a low body mass index (BMI) to achieve low weight targets in order to race. We evaluated dietary habits and bone metabolism in jockeys.

METHODS

Bone mineral density (BMD) was measured in 27 male jockeys of the 144 jockeys licensed in Ireland. Fourteen (52%) had BMD T score below -1.0, of whom 12 consented to clinical review, nutritional survey, endocrine studies, and bone turnover markers (BTM). BTM were compared to age- and sex-matched controls (n = 16).

RESULTS

BMI was 20.6 +/- 1.7 kg/m(2); previous fracture frequency was 3.2 +/- 2.0 per rider. All had normal endocrine axes. The jockeys' diet as determined by a 7-day dietary recall was deficient in energy, calcium, and vitamin D intake. Compared with the control group, the jockey group had evidence of increased bone turnover.

CONCLUSIONS

A substantial proportion of the professional jockeys in Ireland have low-normal BMD, low BMI, and high bone turnover that may result from weight and dietary restrictions. These factors seem to have a deleterious effect on their bone health and predispose the jockeys to a high fracture risk that should be remediated.

When a stroke is not a stroke; posterior leukoencephalopathy syndrome mimicking posterior circulation stroke

Posterior leukoencephalopathy syndrome (PLS) is a potentially reversible syndrome that may mimic the clinical and radiological features of posterior circulation cerebral infarction. Three cases of PLS are presented which were erroneously diagnosed as strokes and treated in accordance with recent evidence based guidelines; none of the cases fulfilled the current criteria requiring treatment for hypertension in the acute stroke setting. Once the diagnosis of PLS was made, and the patients blood pressure treated aggressively, all patients had rapid and full clinical resolution of their symptoms. Given the important differences in management and prognosis, rapid and accurate diagnosis is essential. Posterior leukoencephalopathy syndrome needs to be considered in patients presenting with clinical and/or radiological findings that predominantly affect the occipital lobes.

Tumour necrosis factor 5' promoter single nucleotide polymorphisms influence susceptibility to rheumatoid arthritis (RA) in immunogenetically defined multiplex RA families

Tumour necrosis factor (TNF) plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA) and it has been shown that the TNF-lymphotoxin (TNF-LT) region influences susceptibility to RA. To investigate the role of the TNF-LT locus further, inheritance of TNF 5' promoter alleles was determined in multiplex RA families. Six previously defined TNF promoter single nucleotide polymorphisms (SNPs) (-238, -308, -376, -857, -863, -1031) were observed in these families and in addition, a heretofore undocumented adenine (A) to cytosine (C) substitution at position -572 relative to the transcription start site was defined. TNF 5' promoter SNPs were found to co-segregate with specific TNF microsatellite haplotypes. In particular, the SNP -308A allele was found to be inherited with the TNF a2, b3, c1, d1, e3 (H2) microsatellite haplotype (P < 0.001) which had previously been found to be associated with RA in individuals heterozygous for the HLA-DR 'shared epitope' (SE). When the data were stratified by the presence of the SE with further stratification according to SE DR subtypes and analysed by transmission disequilibrium test (TDT) for which offspring were assumed independent, the -308A and -857T alleles were found to be associated with RA in patients carrying the SE (P = 0.0076 and 0.0063 respectively). The data were further stratified to analyse for association in individuals homozygous or heterozygous for SE alleles. Results showed that the -308A allele was significantly associated with RA susceptibility in individuals heterozygous for the SE (P < 0.001) with the significance only occurring in patients carrying HLA-DR4 (P < 0.001), while the -857T allele was significant in individuals homozygous for the SE (P = 0.0039). Further analysis using the pedigree disequilibrium test (PDT) which conservatively adjusts for all sources of familial correlation except that conferred by linkage disequilibrium still indicated a significant role for the -308A and -857T alleles. These data provide evidence that TNF promoter SNPs may play an independent role in RA susceptibility in specific immunogenetically-defined groups of RA patients.

Modelling the major histocompatibility complex susceptibility to RA using the MASC method

To explain the association between HLA-DRB1 gene and rheumatoid arthritis (RA), two main hypotheses have been proposed. The first, the shared epitope hypothesis, assumes a direct role of DRB1 in RA susceptibility. The second hypothesis assumes a recessive disease susceptibility gene in linkage disequilibrium with DRB1. To investigate these two hypotheses, we analysed data on the HLA-DRB1 and TNF-LT loci in 49 affected sib-pairs. We used the Marker Association Segregation Chi-square (MASC) method in which the genotype distribution of markers among index cases and the haplotype sharing in affected sib-pairs are jointly taken into account. With DRB1 data alone, both hypotheses were shown to fit but with analysis of TNF data, both hypotheses were strongly rejected. Thus the TNF data provided additional information for a better understanding of genetic susceptibility to RA than was previously possible using only HLA-DR data. A theoretical standpoint is addressed here on the advisability of using different linked markers in a candidate region for modelling the contribution of this region in disease susceptibility.

Genetic analysis of the 3' untranslated region of the tumour necrosis factor shows a highly conserved region in rheumatoid arthritis affected and unaffected subjects

Tumour necrosis factor (TNF) is a key proinflammatory mediator in rheumatoid arthritis (RA). The TNF locus, situated in the class III region of the MHC, is flanked by five microsatellite markers. It has previously been shown that this region influences susceptibility to RA; two TNF microsatellite haplotypes were found to be associated with RA. Evidence from murine studies has indicated that variation in the TNF 3' untranslated region (UTR) could be associated with altered regulation of TNF biosynthesis. In order to identify possible RA associated polymorphisms, more than 800 bp of the TNF 3' UTR was genetically analysed in RA affected and unaffected subjects possessing specific RA and non-RA associated TNF microsatellite haplotypes. The TNF 3' UTR region was analysed using two mutation detection methods, PCR-SSCP and NIRCA analysis and DNA sequencing. No genetic differences were observed in the human TNF 3' UTR between subjects, that is, irrespective of RA status or TNF haplotype, and also compared with previously published TNF sequences from human sources. Therefore it can be concluded that the TNF 3' UTR in this population was highly conserved and did not influence susceptibility to RA.

Exclusion of the familial Mediterranean fever locus as a susceptibility region for autosomal dominant familial Hibernian fever

Autosomal dominant periodic fevers constitute a range of syndromes characterised by recurrent attacks of fever and abdominal pain. Familial Hibernian fever (FHF) has been described in only one United Kingdom based family, but two other Irish families have been found with similar clinical features. FHF resembles familial Mediterranean fever (FMF) in several clinical features, but the mode of inheritance of FHF is dominant whereas FMF is recessive. We have investigated whether autosomal dominant periodic fevers, in particular FHF, map to the FMF susceptibility locus (MEFV) on chromosome 16p13.3. We have used informative microsatellite markers flanking this locus to genotype members of the three families mentioned above. Two point and multipoint lod scores definitively excluded linkage to MEFV in the two larger families. A haplotype study confirmed these findings, indicating that FHF is genotypically as well as phenotypically distinct from FMF.

Genetic variability in the tumor necrosis factor-lymphotoxin region influences susceptibility to rheumatoid arthritis

The major histocompatibility complex class III tumor necrosis factor-lymphotoxin (TNF-LT) region (6p21.3) was investigated as a possible susceptibility locus for rheumatoid arthritis (RA). Inheritance of five TNF microsatellite markers was determined in 50 multiplex families. Overall, 47 different haplotypes were observed. One of these, the TNF a6, b5, c1, d3, e3 (H1) haplotype, was present in 35.3% of affected, but in only 20.5% of unaffected, individuals (P < .005). This haplotype accounted for 21.5% of the parental haplotypes transmitted to affected offspring and only 7.3% not transmitted to affected offspring (P = .0003). The TNF a6 and TNF c1 alleles were individually associated with RA (P = .0005 and .0008, respectively), as were the HLA-DRB1 "shared epitope" (SE) (P = .0001) and HLA-DRB1*0401 (P = .0018). Both univariate and bivariate conditional logistic regression analysis showed significant effects of TNF c1 and SE in increasing risk to RA (P < .001). Stratification by the presence of SE indicated an independent effect of the TNFc1 allele (P = .0003) and the HLA A1, B8, DR3 extended haplotype (always TNFa2, b3, c1, d1, e3) (P = .0027) in SE heterozygotes, while the H1 haplotype was associated with RA in SE homozygotes (P = .0018). The TNF-LT region appears to influence susceptibility to RA, distinct from HLA-DR.