title: Inducible nitric oxide synthase (iNOS) expression in autoimmune thyroid disorders (AITD).
abstract: BACKGROUND
  Nitric oxide is synthesized by different cell types through the action of the enzyme nitric oxide synthase (NOS). There are four isoforms of this enzyme: the neuronal, the endothelial, the mitochondrial, and the inducible (iNOS) forms. Although NO production may play an important role in the pathogenesis of inflammation and tissue damage, its possible role in autoimmune thyroiditis has not been adequately explored.
  
  
  OBJECTIVE
  To study protein and mRNA expression of iNOS in human autoimmune thyroid disorders (AITD).
  
  
  METHODS
  We evaluated the expression of iNOS in thyroid gland specimens from 10 patients with Graves' disease (GD), from five patients with Hashimoto's thyroiditis (HT) and from 10 controls by immunohistochemical and reverse transcription-polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  Both immunohistochemistry and PCR techniques showed up-regulated expression of iNOS in the thyroid glands of patients with GD and HT. iNOS expression was higher in GD than in HT. In contrast, no iNOS expression was detected in normal thyroid tissue. In both GD and HT, iNOS was detected in thyrocytes, mainly in those localized in areas close to the inflammatory cell infiltrate. In addition, upregulated expression of iNOS was observed in endothelial cells and thyroidinfiltrating mononuclear cells in both GD and HT.
  
  
  CONCLUSIONS
  The enhanced expression of iNOS in autoimmune thyroiditis suggests that NO synthesis may play an important role in the inflammatory phenomena and tissue damage observed in this disease.
authors.affiliation: Servicio de Endocrinología. Hospital Universitario de La Princesa. Universidad Autónoma de Madrid. Madrid. España; Departamento de Inmunología. Facultad de Medicina. Universidad Autónoma de San Luis Potosí. San Luis Potosí. México.
authors.forename: Nicté
authors.initials: N
authors.lastname: Figueroa-Vega
authors.forename: Pedro
authors.initials: P
authors.lastname: Majano
authors.forename: Eduardo
authors.initials: E
authors.lastname: Larrañaga
authors.forename: José
authors.initials: J
authors.lastname: Miguel Bravo
authors.forename: Rosario
authors.initials: R
authors.lastname: Rodríguez-Ramos
authors.forename: Roberto
authors.initials: R
authors.lastname: González-Amaro
authors.forename: Mónica
authors.initials: M
authors.lastname: Marazuela