Riccardo Donzelli

Histamine mediates behavioural and metabolic effects of 3-iodothyroacetic acid, an endogenous end product of thyroid hormone metabolism

3‐Iodothyroacetic acid (TA1) is an end product of thyroid hormone metabolism. So far, it is not known if TA1 is present in mouse brain and if it has any pharmacological effects.

Modulation of Gene Expression by 3-Iodothyronamine: Genetic Evidence for a Lipolytic Pattern

3-Iodothyronamine (T1AM) is an endogenous biogenic amine, structurally related to thyroid hormone, which is regarded as a novel chemical messenger. The molecular mechanisms underlying T1AM effects are not known, but it is possible to envisage changes in gene expression, since delayed and long-lasting phenotypic effects have been reported, particularly with regard to the modulation of lipid metabolism and body weight. To test this hypothesis we analysed gene expression profiles in adipose tissue and liver of eight rats chronically treated with T1AM (10 mg/Kg twice a day for five days) as compared with eight untreated rats. In vivo T1AM administration produced significant transcriptional effects, since 378 genes were differentially expressed in adipose tissue, and 114 in liver. The reported changes in gene expression are expected to stimulate lipolysis and beta-oxidation, while inhibiting adipogenesis. T1AM also influenced the expression of several genes linked to lipoprotein metabolism suggesting that it may play an important role in the regulation of cholesterol homeostasis. No effect on the expression of genes linked to toxicity was observed. The assay of tissue T1AM showed that in treated animals its endogenous concentration increased by about one order of magnitude, without significant changes in tissue thyroid hormone concentration. Therefore, the effects that we observed might have physiological or pathophysiological importance. Our results provide the basis for the reported effectiveness of T1AM as a lipolytic agent and gain importance in view of a possible clinical use of T1AM in obesity and/or dyslipidaemia.

Quantification of Thyroxine and 3,5,3′-Triiodo-Thyronine in Human and Animal Hearts by a Novel Liquid Chromatography-Tandem Mass Spectrometry Method

Assaying tissue T3 and T4 would provide important information in experimental and clinical investigations. A novel method to determine tissue T3 and T4 by HPLC coupled to mass spectrometry is described. The major difference vs. previously described methods lies in the addition of a derivatization step, that is, to convert T3 and T4 into the corresponding butyl esters. The yield of esterification was ̴ 100% for T3 and 80% for T4. The assay was linear (r>0.99) in the range of 0.2-50 ng/ml, accuracy was in the order of 70-75%, and the minimum tissue amount needed was in the order of 50 mg, that is, about one order of magnitude lower than observed with the same equipment (AB Sciex API 4000 triple quadrupole mass spectrometer) if derivatization was omitted. The method allowed detection of T3 and T4 in human left ventricle biopsies yielding concentrations of 1.51±0.16 and 5.94±0.63 pmol/g, respectively. In rats treated with different dosages of exogenous T3 or T4, good correlations (r>0.90) between plasma and myocardial T3 and T4 concentrations were observed, although in specific subsets different plasma T4 concentrations were not associated with different tissue content in T4. We conclude that this method could provide a novel insight into the relationship between plasma and tissue thyroid hormone levels.

Effect of Hypothyroidism and Hyperthyroidism on Tissue Thyroid Hormone Concentrations in Rat

Background and Objective: The present study was aimed at determining the effects of experimental hypothyroidism and hyperthyroidism on tissue thyroid hormones by a mass spectrometry-based technique. Methods: Rats were subjected to propylthiouracil treatment or administration of exogenous triiodothyronine (T₃) or thyroxine (T₄). Tissue T₃ and T₄ were measured by liquid chromatography tandem mass spectrometry in the heart, liver, kidney, visceral and subcutaneous adipose tissue, and brain. Results: Baseline tissue T₃ and T₄ concentrations ranged from 0.2 to 20 pmol ∙ g^-1 and from 3 to 125 pmol ∙ g^-1, respectively, with the highest values in the liver and kidney, and the lowest values in the adipose tissue. The T₃/T₄ ratio (expressed as a percentage) was in the 7-20% range in all tissues except the brain, where it averaged 75%. In hypothyroidism, tissue T₃ was more severely reduced than serum free T₃, averaging 1-6% of the baseline versus 30% of the baseline. The extent of tissue T₃ reduction, expressed as percentage of the baseline, was not homogeneous (p < 0.001), with liver = kidney > brain > heart > adipose tissue. The tissue T₃/T₄ ratio significantly increased in all organs except the kidney, averaging 330% in the brain and 50-90% in the other tissues. By contrast, exogenous T₃ and T₄ administration produced similar increases in serum free T₃ and in tissue T₃, and the relative changes were not significantly different between different tissues. Conclusions: While the response to increased thyroid hormones availability was similar in all tissues, decreased thyroid hormone availability induced compensatory responses, leading to a significant mismatch between changes in serum and in specific tissues.

Thyroid hormone levels in the cerebrospinal fluid correlate with disease severity in euthyroid patients with Alzheimer's disease

Several reports suggest that subclinical abnormalities in thyroid function may play a role in Alzheimer’s disease (AD) [1–3]. Because of the complexity of thyroid hormone (TH) transport and metabolism in the brain, this hypothesis should be tested by assaying TH in cerebrospinal fluid (CSF). Reduced T3 and increased 3,3 0,50-triiodothyronine (rT3) [4], or decreased T4 with unchanged T3 [5], were reported in CSF of AD patients. A limitation of these studies is the use of immunological methods, which were only validated for plasmatic TH. In the present investigation, we used mass spectrometry (MS) coupled to highperformance liquid chromatography (HPLC), a highly specific and sensitive analytical technique [6], to assay CSF T4, T3 and rT3 in a retrospective series of 35 patients (9 males, 26 females, age 66 ± 2 years), observed at the Neurological Unit of Pisa University. CSF TH concentrations were related to serum TH concentration, and to other laboratory and clinical variables. Subjects and methods

Quantitative antibody-free LC-MS/MS analysis of sTRAIL in sputum and saliva at the sub-ng/mL level

Soluble tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL) induces apoptosis via the extrinsic death receptor pathway and may be a biomarker in the pathogenesis of a broad range of diseases. To investigate the role of sTRAIL in asthma, we developed a quantitative LC-MS/MS method with a lower limit of quantitation (LLOQ) of ≈3pM in induced sputum (174pg/mL) and saliva (198pg/mL) without the use of antibodies. sTRAIL was enriched by immobilized metal affinity chromatography (IMAC) solid-phase extraction (SPE) followed by tryptic digestion and subsequent enrichment of a signature peptide by strong cation exchange (SCX) SPE. The method was validated with respect to stability, accuracy and precision using the standard addition approach and fully metabolically (15)N-labelled hrTRAIL as internal standard. Our results indicate that it is possible to quantify cytokines like sTRAIL at the pM level by LC-MS/MS without the use of antibodies, which has, to our knowledge, never been shown before.

Highly sensitive antibody-free μLC–MS/MS quantification of rhTRAIL in serum

BACKGROUND We describe an antibody-free approach to quantify rhTRAIL(WT) (wild-type) and its closely related death receptor 4 selective variant rhTRAIL(4C7) in human and murine serum by multiplex LC-MS/MS on a microfluidics interface. METHODOLOGY Enrichment of rhTRAIL was performed by strong cation-exchange (SCX) followed by immobilized metal affinity (IMAC) solid-phase extraction. This was followed by trypsin digestion and using methionine-containing signature peptides after fully oxidizing the methionine residue with 0.25% (w/w) hydrogen peroxide. CONCLUSION Absolute quantification was reaching down to 0.5 ng/ml for rhTRAIL(WT) (8.5 pM) and 2 ng/ml for rhTRAIL(4C7) (34 pM) in 100 μl human serum. To support preclinical studies in mice, the analysis was optimized further, for a sample volume of 20 μl murine serum.