The Autoimmune Regulator AIRE in Thymoma Biology: Autoimmunity and Beyond

Abstract:Thymomas are tumors of thymic epithelial cells. They associate more often than any other human tumors with various autoimmune diseases; myasthenia gravis is the commonest, occurring in 10–50% of thymoma patients, depending on the World Health Organization-defined histologic subtype. Most thymomas generate many polyclonal maturing T lymphocytes but in disorganized microenvironments Failure to induce self-tolerance may be a key factor leading to the export of potentially autoreactive CD4+ progeny, thus predisposing to autoimmune diseases. Normally, the master Autoimmune Regulator promotes expression of peripheral tissue-restricted antigens such as insulin by medullary thymic epithelial cells and induction of tolerance to them. The failure of ∼95% of thymomas to express autoimmune regulator is another feature potentially contributing to autoimmunity

4-Pyridoxic Acid/Pyridoxine Ratio in Patients with Type 2 Diabetes is Related to Global Cardiovascular Risk Scores

Background: Vascular diseases are multifactorial and several risk factors may have synergetic effect on the global vascular risk. Among patients with diabetes, we investigated whether vitamin B6 species differ according to global cardiovascular risk. Methods: The present observational study included 122 patients with type 2 diabetes (mean (SD) age = 69.9 (9.1) years; 50% men). Concentrations of vitamin B6 vitamers were measured. Classical blood biomarkers and risk factors were used to compute a multivariate risk score. Results: Plasma concentrations of 4-pyridoxic acid were higher in patients with high risk versus those with low risk scores (48.2 (63.7) vs. 31.9 (15.0) nmol/L; p = 0.031). Plasma pyridoxine was significantly lowered in patients at high risk (2.8 (28.4) vs. 38.1 (127.8) nmol/L; p = 0.003). PAr index (4-pyridoxic acid/pyridoxal + pyridoxal 5′-phosphate) (1.05 (0.07) vs. 0.84 (0.06); p = 0.017) and the ratio of 4-pyridoxic acid/pyridoxine (7.0 (4.8) vs. 3.9 (3.2); p < 0.001) were higher in patients at high risk. After adjustment for cystatin C and C-reactive protein, only pyridoxine and 4-pyridoxic acid/pyridoxine ratio remained significantly different according to vascular risk scores. 4-Pyridoxic acid/pyridoxine ratio was the best marker to discriminate between patients according to their risk scores—area under the curve (AUC) (95% confidence intervals (CI)) = 0.72 (0.62–0.81). 4-Pyridoxic acid/pyridoxine ratio was directly related to plasma levels of soluble vascular cell adhesion molecule 1. Conclusion: Vitamin B6 metabolism was shifted in patients with multiple vascular risk factors. The catabolism to 4-pyridoxic acid was enhanced, whereas the catabolism to pyridoxine was lowered. High 4-Pyridoxic acid/pyridoxine ratio is independently associated with global cardiovascular risk

Vitamin B status in patients with type 2 diabetes mellitus with and without incipient nephropathy

AbstractAimTo investigate the vitamin B status, with particular focus on vitamin B6, in adults with and without incipient nephropathy secondary to type 2 diabetes mellitus.MethodsPlasma and/or urine concentrations of vitamins B6, B1, B12, related vitamers and biomarkers (including total homocysteine, methylmalonic acid) were measured in 120 adults with type 2 diabetes (including 46 patients with microalbuminuria) and 52 non-diabetic control subjects.ResultsPlasma concentrations of pyridoxal 5′-phosphate (PLP) were significantly lower in patients with type 2 diabetes than in control subjects (median: 22.7nmol/L, diabetes with microalbuminuria; 26.8nmol/L, diabetes without microalbuminuria; 39.5nmol/L, non-diabetic control; p<0.0001). The prevalence of low PLP (<30nmol/L) was 63%, 58%, and 25% in the diabetes groups with and without microalbuminuria and the control group, respectively. Plasma levels of pyridoxine and pyridoxal were also lower (p<0.0001), but levels of pyridoxamine, pyridoxamine 5′-phosphate, and pyridoxic acid were higher in both groups with diabetes compared to the control group (p<0.001). Thiamine deficiency was highly prevalent in all groups, whereas low vitamin B12 and elevated methylmalonic acid were rare. Increased levels of C-reactive protein and soluble vascular cell adhesion molecule-1 were observed in the groups with diabetes (p<0.05, versus healthy control).ConclusionsDeficiency of vitamin B6 (PLP, pyridoxine, pyridoxal) and vitamin B1 (thiamine) was prevalent in type 2 diabetes. Incipient nephropathy was associated with more pronounced alterations in vitamin B6 metabolism and stronger indications of endothelial dysfunction and inflammation

A prospective multicentre study on sural nerve action potentials in ALS.

International audienceOBJECTIVE: To evaluate sensory nerve conduction studies in ALS in a prospective multicentre study involving 7 neurophysiologists from 6 European countries. METHODS: Bilateral sural potentials were obtained in 35 ALS patients and 35 age-matched controls according to a standardised examination protocol using antidromic surface technique. The recordings from the right sural nerve of the controls were used for reference values. A reduction from the mean of controls greater than 2 SDs was considered abnormal. RESULTS: Reduced sensory nerve action potential (SNAP) amplitude or reduced conduction velocity (CV), or both, was found in 6 ALS patients (17%). Decrease in CV was the most frequent finding, and was observed in 8 nerves from 5 patients. Reduced SNAP amplitude was found in 2 nerves from 2 patients. All changes were minor ranging from -2.1 to -3.2 SDs. CONCLUSIONS: This is the first standardised multicentre study on sensory potentials in ALS. It confirms that although normal sensory findings should be expected in the majority of ALS patients, minor abnormalities are not uncommon. SIGNIFICANCE: Mild sensory abnormalities do not necessarily exclude a diagnosis of ALS

Influence of medical audit on electrodiagnostic evaluation of polyneuropathy. A multicentre study.

International audienceOBJECTIVE: Since 1992, 7 European neurophysiologists have participated in the ESTEEM project concerned with improvements in electrodiagnostic medicine. This study assesses whether the collaboration that includes peer review medical audit has influenced the involved physicians' electrodiagnostic criteria for polyneuropathy (PNP) diagnosing and classification. METHODS: Two sets of each physician's PNP examinations performed early and late in the study were examined for changes in (1) number of studies with abnormal electrophysiological findings required for diagnosing PNP, and (2) agreement between the classifications given by the individual physicians and the peer review group. RESULTS: The average number of abnormal motor nerve segments per patient increased from 4.6 to 6.4 during the study. Although most individual changes were minor, the second set of examinations showed an increased homogeneity among the physicians in the number of abnormal motor nerve segments and abnormal F wave studies, and a tendency towards increased homogeneity in the number of abnormal sensory nerve segments. There was also an increased agreement on pathophysiological PNP classification in the second set of examinations compared to the first set. CONCLUSIONS: The participation in the ESTEEM project seems to have impacted the physicians' clinical routine, possibly as they have accustomed themselves to apply criteria more strictly. SIGNIFICANCE: This study support that international collaboration is a useful step towards improvements in electrodiagnostic medicine

cFLIP overexpression in T cells in thymoma-associated myasthenia gravis

Objective: The capacity of thymomas to generate mature CD4+ effector T cells from immature precursors inside the tumor and export them to the blood is associated with thymoma-associated myasthenia gravis (TAMG). Why TAMG (+) thymomas generate and export more mature CD4+ T cells than MG(-) thymomas is unknown. Methods: Unfixed thymoma tissue, thymocytes derived thereof, peripheral blood mononuclear cells (PBMCs), T-cell subsets and B cells were analysed using qRT-PCR and western blotting. Survival of PBMCs was measured by MTT assay. FAS-mediated apoptosis in PBMCs was quantified by flow cytometry. NF-kappa B in PBMCs was inhibited by the NF-kappa B-Inhibitor, EF24 prior to FAS-Ligand (FASLG) treatment for apoptosis induction. Results: Expression levels of the apoptosis inhibitor cellular FLICE-like inhibitory protein (c-FLIP) in blood T cells and intratumorous thymocytes were higher in TAMG(+) than in MG(-) thymomas and non-neoplastic thymic remnants. Thymocytes and PBMCs of TAMG patients showed nuclear NF-kappa B accumulation and apoptosis resistance to FASLG stimulation that was sensitive to NF-kappa B blockade. Thymoma removal reduced cFLIP expression in PBMCs. Interpretation: We conclude that thymomas induce cFLIP overexpression in thymocytes and their progeny, blood T cells. We suggest that the stronger cFLIP overexpression in TAMG(+) compared to MG(-) thymomas allows for the more efficient generation of mature CD4+ T cells in TAMG(+) thymomas. cFLIP overexpression in thymocytes and exported CD4+ T cells of patients with TAMG might contribute to the pathogenesis of TAMG by impairing central and peripheral T-cell tolerance

cFLIP

Funding Information Supported by the IntenC program of the BMBF (grant: 01DL12027 to A. M. and P. S.) and T€UBITAK (grant 110S297 to G. S.-H.)