A novel thymoma-associated autoimmune disease: Anti-PIT-1 antibody syndrome

Hironori Bando,Yasuhiko Okimura,Wataru Ogawa,Atsuko Mokubo,Kentaro Suda,Yoshimasa Maniwa,Ryusaku Matsumoto,Katsuyoshi Tojo,Genzo Iguchi,Yutaka Takahashi,Yukiko Odake,Hitoshi Nishizawa,Kenichi Yoshida,Hidenori Fukuoka

doi:10.1038/srep43060

Abstract

Anti-PIT-1 antibody syndrome has recently been reported and characterized by acquired growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies associated with autoimmunity to a pituitary specific transcription factor PIT-1, which plays an essential role in GH-, PRL-, and TSH-producing cells. Although circulating anti-PIT-1 antibody and PIT-1-reactive cytotoxic T cells (CTLs) were detected in the patients, the pathophysiology and precise mechanisms for the autoimmunity remain unclarified. During the follow up, thymoma was diagnosed in all 3 cases with anti-PIT-1 antibody syndrome. Immunohistochemical analysis revealed that PIT-1 was strongly expressed in neoplastic cortical thymic epithelial cells. Importantly, after thymectomy, the titer of anti-PIT-1 antibody decreased and reactivity of CTLs toward PIT-1 diminished. These data strongly suggest that the aberrant expression of PIT-1 in the thymoma plays a causal role in the development of this syndrome. Thus, we define that this syndrome is a novel thymoma-associated autoimmune disease.

Highlights

Anti-PIT-1 antibody syndrome has recently been reported and characterized by acquired growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies associated with autoimmunity to a pituitary specific transcription factor PIT-1, which plays an essential role in GH, PRL, and TSH-producing cells
Because of the advanced age, the tumor has been carefully observed in this patient. These data indicate that one case has not been histologically proven, all the patients with anti-PIT-1 antibody syndrome were associated with thymomas, suggesting that thymoma plays a role in the pathogenesis of this syndrome
We have demonstrated that thymoma was associated with all patients with anti-PIT-1 antibody syndrome

Summary

Introduction

Anti-PIT-1 antibody syndrome has recently been reported and characterized by acquired growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies associated with autoimmunity to a pituitary specific transcription factor PIT-1, which plays an essential role in GH-, PRL-, and TSH-producing cells. After thymectomy, the titer of antiPIT-1 antibody decreased and reactivity of CTLs toward PIT-1 diminished These data strongly suggest that the aberrant expression of PIT-1 in the thymoma plays a causal role in the development of this syndrome. The pituitary-specific transcriptional factor-1 (PIT-1, known as POU1F1) is a member of the Pit-Oct-Unc (POU) homeodomain family that plays an essential role in the differentiation of somatotrophs, lactotrophs, and thyrotrophs in the anterior pituitary[8] It regulates the expression of growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) and mutations in PIT-1 gene cause congenital GH, PRL, and TSH deficiencies[9].

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Conclusion