Bronchial asthma induced by an antithyroid drug

The Significance of Hypothiocyanite Production via the Pendrin/DUOX/Peroxidase Pathway in the Pathogenesis of Asthma

Inhaled corticosteroids (ICSs) are used as first-line drugs for asthma, and various novel antiasthma drugs targeting type 2 immune mediators are now under development. However, molecularly targeted drugs are expensive, creating an economic burden on patients. We and others previously found pendrin/SLC26A4 as a downstream molecule of IL-13, a signature type 2 cytokine critical for asthma, and showed its significance in the pathogenesis of asthma using model mice. However, the molecular mechanism of how pendrin causes airway inflammation remained elusive. We have recently demonstrated that hypothiocyanite (OSCN⁻) produced by the pendrin/DUOX/peroxidase pathway has the potential to cause airway inflammation. Pendrin transports thiocyanate (SCN⁻) into pulmonary lumens at the apical side. Peroxidases catalyze SCN⁻ and H₂O₂ generated by DUOX into OSCN⁻. Low doses of OSCN⁻ activate NF-κB in airway epithelial cells, whereas OSCN⁻ in high doses causes necrosis of the cells, inducing the release of IL-33 and accelerating inflammation. OSCN⁻ production is augmented in asthma model mice and possibly in some asthma patients. Heme peroxidase inhibitors, widely used as antithyroid agents, diminish asthma-like phenotypes in mice, indicating the significance of this pathway. These findings suggest the possibility of repositioning antithyroid agents as antiasthma drugs.

Telangiectasia as a presenting sign of Graves' disease

Acquired nevoid telangiectasia (ANT) is observed in several conditions including primary cutaneous disorders, systemic autoimmune disease and hyperestrogenism occurring in puberty, pregnancy and chronic liver disease. We describe a patient in whom ANT was a presenting sign of autoimmune hyperthyroidism, which improved after thyroidectomy. A 43-year-old Caucasian woman experienced an asymptomatic development of multiple widespread red skin lesions, diagnosed to be ANT. Blood tests revealed increased serum levels of free tri-iodothyronine and thyroxine and suppressed thyroid-stimulating hormone. Other causes of ANT were excluded. ANT improved but did not disappear after thyroidectomy. The possible pathogenetic factors linking ANT and Graves' disease, such as an immune-mediated process, altered estrogen metabolism or vasodilatation associated with hyperdynamic circulation, are discussed.