Expression of Hypoxia-Inducible Factor (HIF)-1a-Vascular Endothelial Growth Factor (VEGF)-Inhibitory Growth Factor (ING)-4- axis in sarcoidosis patients

Argyris Tzouvelekis,George Zacharis,Anastasios Koutsopoulos,Andreas Karameris,Andreas Koulelidis,Demosthenes Bouros,Paschalis Steiropoulos,Kostas Archontogeorgis,Fotis Drakopanagiotakis,Dimitrios Mikroulis,Stavros Anevlavis,Panagiotis Boglou,Vlassis Polychronopoulos,Paschalis Ntolios

doi:10.1186/1756-0500-5-654

Abstract

BackgroundSarcoidosis is a granulomatous disorder of unknown etiology. The term of immunoangiostasis has been addressed by various studies as potentially involved in the disease pathogenesis. The aim of the study was to investigate the expression of the master regulator of angiogenesis hypoxia inducible factor (HIF)-1a – vascular endothelial growth factor (VEGF)- inhibitor of growth factor 4-(ING4) - axis within sarcoid granuloma.MethodsA total of 37 patients with sarcoidosis stages II-III were recruited in our study. Tissue microarray technology coupled with immunohistochemistry analysis were applied to video-assisted thoracoscopic surgery (VATS) lung biopsy samples collected from 37 sarcoidosis patients and 24 controls underwent surgery for benign lesions of the lung. Computerized image analysis was used to quantify immunohistochemistry results. qRT-PCR was used to assess HIF-1a and ING4 expression in 10 sarcoidosis mediastinal lymph node and 10 control lung samples.ResultsHIF-1a and VEGF-ING4 expression, both in protein and mRNA level, was found to be downregulated and upregulated, respectively, in sarcoidosis samples compared to controls. Immunohistochemistry coupled with computerized image analysis revealed minimal expression of HIF-1a within sarcoid granulomas whereas an abundant staining of ING4 and VEGF in epithelioid cells was also visualized.ConclusionsOur data suggest an impairment of the HIF-1a – VEGF axis, potentialy arising by ING4 overexpression and ultimately resulting in angiostasis and monocyte recruitment within granulomas. The concept of immunoangiostasis as a possible protection mechanism against antigens of infectious origin needs further research to be verified.

Highlights

Sarcoidosis is a granulomatous disorder of unknown etiology
QRT-PCR in 10 sarcoidosis and 10 control lung samples revealed abundant vascular endothelial growth factor (VEGF) expression (Figure 1B) in sarcoidosis mediastinal lymph nodes compared to controls evidence that was further corroborated by semi-quantitative computerized immunohistochemistry analysis in tissue microarray sections of sarcoidosis patients revealing a diffuse cytoplasmic strong staining intensity, indicating increased VEGF expression (Figure 3A-F)
In line with the above existing literature, Inhibitor of Growth Family member 4 (ING4) protein and mRNA levels were extensively expressed in areas of diminished Hypoxia Inducible Factor-1a (HIF-1a) expression, as assessed by Quantitative Real-Time reverse transcriptase-polymerase chain reaction (qRT-PCR) (Figure 1C), and tissue microarray immunohistochemical computerized image analysis, respectively

Summary

Introduction

Sarcoidosis is a granulomatous disorder of unknown etiology. The term of immunoangiostasis has been addressed by various studies as potentially involved in the disease pathogenesis. Sarcoidosis is an immunologic, granulomatous disorder affecting multiple systems. It is pathologically characterized by the presence of non-caseating granulomas in involved organs [1]. Seminal observations by Strieter et al [10] implicated angiogenesis in the pathogenesis of granulomatous and fibrotic lung disorders. A regulation of T cell migration and activation by angiostatic chemokines, such as IP-10, resulting in granulomas formation has been demonstrated [10]. Further extending the latter observations, a distinct angiogenic and angiostatic profile between sarcoidosis and idiopathic pulmonary fibrosis (IPF) has been recently reported [8]

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