Email updates

Keep up to date with the latest news and content from BMC Infectious Diseases and BioMed Central.

Open Access Research article

Circulating levels of insulin-like growth factor-I (IGF-I) correlate with disease status in leprosy

Luciana Silva Rodrigues1, Mariana Andrea Hacker2, Ximena Illarramendi2, Maria Fernanda Miguens Castelar Pinheiro3, José Augusto da Costa Nery2, Euzenir Nunes Sarno2 and Maria Cristina Vidal Pessolani1*

Author Affiliations

1 Laboratory of Cellular Microbiology, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil

2 Leprosy Laboratory, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil

3 Sérgio Franco Laboratory, Rio de Janeiro, RJ, Brazil

For all author emails, please log on.

BMC Infectious Diseases 2011, 11:339  doi:10.1186/1471-2334-11-339

Published: 13 December 2011

Abstract

Background

Caused by Mycobacterium leprae (ML), leprosy presents a strong immune-inflammatory component, whose status dictates both the clinical form of the disease and the occurrence of reactional episodes. Evidence has shown that, during the immune-inflammatory response to infection, the growth hormone/insulin-like growth factor-I (GH/IGF-I) plays a prominent regulatory role. However, in leprosy, little, if anything, is known about the interaction between the immune and neuroendocrine systems.

Methods

In the present retrospective study, we measured the serum levels of IGF-I and IGBP-3, its major binding protein. These measurements were taken at diagnosis in nonreactional borderline tuberculoid (NR BT), borderline lepromatous (NR BL), and lepromatous (NR LL) leprosy patients in addition to healthy controls (HC). LL and BL patients who developed reaction during the course of the disease were also included in the study. The serum levels of IGF-I, IGFBP-3 and tumor necrosis factor-alpha (TNF-α) were evaluated at diagnosis and during development of reversal (RR) or erythema nodosum leprosum (ENL) reaction by the solid phase, enzyme-labeled, chemiluminescent-immunometric method.

Results

The circulating IGF-I/IGFBP-3 levels showed significant differences according to disease status and occurrence of reactional episodes. At the time of leprosy diagnosis, significantly lower levels of circulating IGF-I/IGFBP-3 were found in NR BL and NR LL patients in contrast to NR BT patients and HCs. However, after treatment, serum IGF-I levels in BL/LL patients returned to normal. Notably, the levels of circulating IGF-I at diagnosis were low in 75% of patients who did not undergo ENL during treatment (NR LL patients) in opposition to the normal levels observed in those who suffered ENL during treatment (R LL patients). Nonetheless, during ENL episodes, the levels observed in RLL sera tended to decrease, attaining similar levels to those found in NR LL patients. Interestingly, IGF-I behaved contrary to what was observed during RR episodes in R BL patients.

Conclusions

Our data revealed important alterations in the IGF system in relation to the status of the host immune-inflammatory response to ML while at the same time pointing to the circulating IGF-I/IGFBP-3 levels as possible predictive biomarkers for ENL in LL patients at diagnosis.

Keywords:
Leprosy; IGF-I; IGFBP-3; Leprosy reactions; Mycobacterium leprae; Biomarker; Neuroendocrine system; Immune-inflammatory response