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Proteomic Profiling of Growth Hormone-Responsive Proteins in Human Peripheral Blood Leukocytes

Hormones and Cancer Group (L.C., R.C.B.), Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, Sydney NSW 2065, Australia; and Pituitary Research Unit (A.E.N., K.K.Y.H.), Garvan Institute of Medical Research and Department of Endocrinology, St. Vincent’s Hospital, Sydney, NSW 2010 Australia

Address all correspondence and requests for reprints to: Robert C. Baxter, D.Sc., Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards, 2065 Australia. E-mail: robaxter{at}med.usyd.edu.au.

Context: GH is a known modulator of the immune system, but the effect of exogenous GH administration on white blood cell proteins has not been investigated. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a powerful platform for the study of GH effects on immune system proteins.

Objective: Our objective was to explore a novel approach for the detection of GH-responsive proteins in human leukocytes by proteomic analysis using SELDI-TOF MS.

Design: We conducted a randomized double-blind, placebo-controlled GH administration study of 8 wk treatment followed by 6 wk washout. Pre- and posttreatment samples from 30 subjects were used for biomarker discovery.

Setting: The study was performed at a clinical research facility.

Participants: We studied 30 recreationally trained healthy athletes.

Intervention: Subjects received either recombinant human GH (2 mg/d sc; n = 22) or placebo (n = 8) for 8 wk.

Main Outcome Measures: Proteomic profiles were determined using CM10 weak cation-exchange protein chips, and some GH-regulated proteins were purified and identified by mass spectrometry and/or immunoblotting.

Results: SELDI-TOF analysis revealed a number of GH-regulated peptides/proteins in the 3- to 22-kDa range that are either up- or down-regulated by GH. Several of these may be useful as biomarkers of GH action. The calcium-binding, proinflammatory calgranulins S100A8, S100A9, and S100A12 were all significantly down-regulated in response to GH treatment.

Conclusion: This study illustrates the novel use of human leukocyte proteomic profiling by SELDI-TOF MS and reveals the negative regulation of proinflammatory S100 proteins by GH in human white blood cells.