Spontaneous and tetracosactide-induced anti-ACTH antibodies in man

CONTEXT

During a clinical trial of regular tetracosactide depot injections, four of 13 patients with autoimmune Addison's disease (AAD) developed adverse reactions immediately following tetracosactide injections. We wished to investigate whether these adverse effects could be due to the production of circulating antitetracosactide (ACTH1-24 ) antibodies.

DESIGN

Anti-ACTH binding activity was investigated using immunoblotting and ELISA on sera from participants in the trial (n = 13; baseline and after tetracosactide exposure), 131 unrelated patients with AAD, 92 patients with Graves' disease (GD), 15 patients with isolated ACTH deficiency and 102 controls. Immunohistochemistry of human pituitary tissue sections was also performed using pooled sera.

RESULTS

Bands at approximately 4 and 6 kDa, corresponding to ACTH1-24 and full-length ACTH1-39, respectively, were found in 10 of 13 (77%) of sera from trial patients exposed to tetracosactide, including all those who had an adverse reaction. This is in contrast with healthy control sera, which showed no binding. The same 10 subjects also showed high levels of binding to tetracosactide by ELISA, along with 21% of patients with AAD, 14% of patients with GD (both P < 0·001 compared to controls) and 1 isolated ACTH deficiency patient (7% of 15). These sera also recognized native ACTH in human pituitary sections.

CONCLUSION

Our study demonstrates that repeated administration of depot tetracosactide can lead to anti-ACTH1-24 autoreactivity. In addition, a significant number of patients with AAD and GD also had similar, spontaneous, anti-ACTH reactivity. The presence of these antibodies could mediate some of the adverse effects or explain the well-described phenomenon of resistance to chronic ACTH therapy.

Linkage Analysis in Autoimmune Addison's Disease: NFATC1 as a Potential Novel Susceptibility Locus

Background

Autoimmune Addison’s disease (AAD) is a rare, highly heritable autoimmune endocrinopathy. It is possible that there may be some highly penetrant variants which confer disease susceptibility that have yet to be discovered.

Methods

DNA samples from 23 multiplex AAD pedigrees from the UK and Norway (50 cases, 67 controls) were genotyped on the Affymetrix SNP 6.0 array. Linkage analysis was performed using Merlin. EMMAX was used to carry out a genome-wide association analysis comparing the familial AAD cases to 2706 UK WTCCC controls. To explore some of the linkage findings further, a replication study was performed by genotyping 64 SNPs in two of the four linked regions (chromosomes 7 and 18), on the Sequenom iPlex platform in three European AAD case-control cohorts (1097 cases, 1117 controls). The data were analysed using a meta-analysis approach.

Results

In a parametric analysis, applying a rare dominant model, loci on chromosomes 7, 9 and 18 had LOD scores >2.8. In a non-parametric analysis, a locus corresponding to the HLA region on chromosome 6, known to be associated with AAD, had a LOD score >3.0. In the genome-wide association analysis, a SNP cluster on chromosome 2 and a pair of SNPs on chromosome 6 were associated with AAD (P <5x10^-7). A meta-analysis of the replication study data demonstrated that three chromosome 18 SNPs were associated with AAD, including a non-synonymous variant in the NFATC1 gene.

Conclusion

This linkage study has implicated a number of novel chromosomal regions in the pathogenesis of AAD in multiplex AAD families and adds further support to the role of HLA in AAD. The genome-wide association analysis has also identified a region of interest on chromosome 2. A replication study has demonstrated that the NFATC1 gene is worthy of future investigation, however each of the regions identified require further, systematic analysis.

Residual adrenal function in autoimmune Addison's disease: improvement after tetracosactide (ACTH1-24) treatment

CONTEXT

Despite lifelong steroid hormone replacement, there is excess morbidity and mortality associated with autoimmune Addison's disease. In health, adrenocortical cells undergo continuous self-renewal from a population of subcapsular progenitor cells, under the influence of ACTH, suggesting a therapeutic possibility.

OBJECTIVE

We aimed to determine whether tetracosactide (synthetic ACTH1-24) could revive adrenal steroidogenic function in autoimmune Addison's disease.

DESIGN, SETTING, AND PATIENTS

Thirteen patients (aged 16-65 y) with established autoimmune Addison's disease for more than 1 year were recruited at the Newcastle University Clinical Research Facility.

INTERVENTION

The intervention included a 20-week study of regular sc tetracosactide (ACTH1-24) therapy.

MAIN OUTCOME MEASURES

Serum and urine corticosteroids were measured during medication withdrawal at baseline and every 5 weeks during the study.

RESULTS

Serum cortisol levels remained less than 100 nmol/L in 11 of 13 participants throughout the study. However, two women achieved peak serum cortisol concentrations greater than 400 nmol/L after 10 and 29 weeks of tetracosactide therapy, respectively, allowing withdrawal of corticosteroid replacement. Concurrently, urine glucocorticoid and mineralocorticoid metabolite excretion increased from subnormal to above the median of healthy controls. One of these responders remains well with improving peak serum cortisol (672 nmol/L) 28 months after stopping all treatments. The other responder showed a gradual reduction in serum cortisol and aldosterone over time, and steroid therapy was recommenced after a 28-week period without glucocorticoid replacement.

CONCLUSION

This is the first study to demonstrate that established autoimmune Addison's disease is amenable to a regenerative medicine therapy approach.

Evc Regulates a Symmetrical Response to Shh Signaling in Molar Development

Tooth morphogenesis involves patterning through the activity of epithelial signaling centers that, among other molecules, secrete Sonic hedgehog (Shh). While it is known that Shh responding cells need intact primary cilia for signal transduction, the roles of individual cilia components for tooth morphogenesis are poorly understood. The clinical features of individuals with Ellis-van Creveld syndrome include various dental anomalies, and we show here that absence of the cilial protein Evc in mice causes various hypo- and hyperplasia defects during molar development. During first molar development, the response to Shh signaling is progressively lost in Evc-deficient embryos and, unexpectedly, the response consistently disappears in a buccal to lingual direction. The important role of Evc for establishing the buccal-lingual axis of the developing first molar is also supported by a displaced activity of the Wnt pathway in Evc mutants. The observed growth abnormalities eventually manifest in first molar microdontia, disruption of molar segmentation and symmetry, root fusions, and delayed differentiation. Analysis of our data indicates that both spatially and temporally disrupted activities of the Shh pathway are the primary cause for the variable dental anomalies seen in patients with Ellis-van Creveld syndrome or Weyers acrodental dysostosis.

The role of functionally defective rare germline variants of sialic acid acetylesterase in autoimmune Addison's disease

BACKGROUND

Autoimmune Addison's disease (AAD) is a rare condition with a complex genetic basis. A panel of rare and functionally defective genetic variants in the sialic acid acetylesterase (SIAE) gene has recently been implicated in several common autoimmune conditions. We performed a case-control study to determine whether these rare variants are associated with a rarer condition, AAD.

METHOD

We analysed nine SIAE gene variants (W48X, M89V, C196F, C226G, R230W, T312M, Y349C, F404S and R479C) in a United Kingdom cohort of 378 AAD subjects and 387 healthy controls. All samples were genotyped using Sequenom iPlex chemistry to characterise primer extension products.

RESULTS

A heterozygous rare allele at codon 312 (312*M) was found in one AAD patient (0.13%) but was not detected in the healthy controls. The commoner, functionally recessive variant at codon 89 (89*V) was found to be homozygous in two AAD patients but was only found in the heterozygous state in controls. Taking into account all nine alleles examined, 4/378 (1.06%) AAD patients and 1/387 (0.25%) healthy controls carried the defective SIAE alleles, with a calculated odds ratio of 4.13 (95% CI 0.44-97.45, two-tailed P value 0.212, NS).

CONCLUSION

We demonstrated the presence of 89*V homozygotes and the 312*M rare allele in the AAD cohort, but overall, our analysis does not support a role for rare variants in SIAE in the pathogenesis of AAD. However, the relatively small collection of AAD patients limits the power to exclude a small effect.

Evc2 is a positive modulator of Hedgehog signalling that interacts with Evc at the cilia membrane and is also found in the nucleus

BACKGROUND

Evc is essential for Indian Hedgehog (Hh) signalling in the cartilage growth plate. The gene encoding Evc2 is in close proximity in divergent orientation to Evc and mutations in both human genes lead to the chondrodysplasia Ellis-van Creveld syndrome.

RESULTS

Bioinformatic analysis reveals that the Evc and Evc2 genes arose through a duplication event early in metazoan evolution and were subsequently lost in arthropods and nematodes. Here we demonstrate that Evc2 is essential for Hh pathway activation in response to the Smo agonist purmorphamine. A yeast two-hybrid screen using Evc as bait identified Evc2 as an Evc binding partner and we confirmed the interaction by immunoprecipitation. We developed anti-Evc2 antibodies and show that Evc2 and Evc co-localize at the basal body and also on primary cilia. In transfected cells, basal body and cilia localization is observed when Evc and Evc2 constructs are co-transfected but not when either construct is transfected individually. We show that Evc and Evc2 are cilia transmembrane proteins, the C-terminus for both being intracellular and Evc2, but not Evc, having an extracellular portion. Furthermore, Evc is absent at the basal body in Evc2 null cells. Using Western blots of cytoplasmic and nuclear protein, we also demonstrate that full length Evc2 but not Evc, is located in the nucleus.

CONCLUSIONS

We demonstrate for the first time that Evc2 is a positive regulator of the Hh signalling pathway and that it is located at the basal body of primary cilia. We show that the presence of Evc and Evc2 at the basal body and cilia membrane is co-dependent. In addition, Evc2, but not Evc, is present in the cell nucleus suggesting movement of Evc2 between the cilium and nucleus.

Randomized controlled trial of stented and stentless aortic bioprotheses: hemodynamic performance at 3 years

A randomized prospective trial was undertaken to compare the hemodynamic performance and left ventricular regression after aortic valve replacement with the Toronto SPV stentless bioprosthesis and the Carpentier Edwards SAV (CE) bioprosthesis. Forty patients were randomized after the annular and sinotubular diameters had been measured. Early hemodynamic measurements were made with a thermodilution cardiac output catheter, and echocardiography was used thereafter. Left ventricular mass was assessed using magnetic resonance imaging (MRI) at 1 week, 6 months, and 32 months. The mean annular size was 25.3+/-2.2 mm (CE) and 25.5+/-1.5 mm (Toronto), although it was possible to implant valves with a mean diameter 3 mm larger in the stentless group (26.0+/-1.7 mm cf. 23.0+/-1.7 mm). Hemodynamic performance in the first 24 hours showed no significant difference between the groups, but there was a trend for shorter ventilation time and shorter stays in the intensive therapy unit in the stentless group. Echocardiography showed superior transvalvular gradients in the stentless group at 1 week (mean 5.5+/-3.1 mm Hg cf. 8.9+/-2.5 mm Hg), and this difference was maintained at a mean follow-up time of 32 months (3.5+/-0.6 mm Hg cf. 6.3+/-0.6 mm Hg). Similar regression of left ventricular mass was seen in both groups at 6 months, but at 32 months, measurement in diastole showed a reduction of 38% (P<.01) in the stentless group compared with 20% (P = ns) in the stented group, and measurements in systole showed a 23% (P<.01) and 13% (P = ns) reduction, respectively. This study confirms that a larger stentless valve can be implanted into a given size of aortic annulus with superior residual aortic valve gradients. These lower gradients seem to result in improved long-term regression of left ventricular mass as measured by MRI.

Effects of the renin inhibitor H77 on angiotensin II, arterial pressure and cardiac function in conscious dogs: comparison with captopril

The renin inhibitor H77 and the angiotensin I converting enzyme (ACE) inhibitor captopril were compared in separate experiments with infusion of 5% dextrose as a control for the effects on plasma angiotensin II (Ang II) concentration, arterial pressure and cardiac function, measured by Swan-Ganz catheter, in conscious dogs. The effects of a high dose of H77 (10 mg/kg per h) were similar to those of high-dose captopril (6 mg/kg per h). Both reduced plasma Ang II concentration, systemic vascular resistance and arterial pressure; both increased the heart rate; both increased cardiac output but the change was significant only with captopril; neither affected stroke volume, pulmonary artery pressure or pulmonary vascular resistance; both reduced left and right atrial pressures. The similar pattern of effects for the two inhibitors suggests that the mechanism by which they act is the same--reduction in Ang II--and that the cardiovascular effects of H77 are not a specific action of the peptide that is unrelated to the reduction in plasma Ang II concentrations.