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Published online March 10, 2007
Diabetes Care 30:1615-1617, 2007
DOI: 10.2337/dc06-1905
© 2007 by the American Diabetes Association
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Pathophysiology/Complications
Brief Report

Insulin-Like Growth Factor Binding Protein–Related Protein 1 (IGFBP-rP1/MAC25) Is Linked to Endothelial-Dependent Vasodilation in High-Ferritin Type 2 Diabetes

Abel López-Bermejo, MD1, Javad Khosravi, PHD2, Wifredo Ricart, MD1, Antoni Castro, MD, PHD3, Vivian Hwa, PHD4, Katherine L. Pratt, MS4, Roser Casamitjana, PHD5, Ron G. Rosenfeld, MD4,6 and José Manuel Fernández-Real, MD, PHD1

1 Department of Endocrinology, Dr. Josep Trueta Hospital, Girona, Spain
2 Diagnostic System Laboratories, Toronto, Ontario, Canada
3 Department of Internal Medicine, Dr. Josep Trueta Hospital, Girona, Spain
4 Department of Pediatrics, Oregon Health and Sciences University, Portland, Oregon
5 Endocrine Laboratory, University Clinical Hospital, Barcelona, Spain
6 Lucile Packard Foundation for Children's Health, Palo Alto, California

Address correspondence and reprint requests to Abel López-Bermejo, Dr. Josep Trueta Hospital, Av. Francia s/n, 17007 Girona, Spain. E-mail: uden.alopez{at}htrueta.scs.es

Abbreviations: EDV, endothelium-dependent vasodilation • EIV, endothelial-independent vasodilation • IGFBP-rP1, insulin-like growth factor binding protein–related protein 1


   INTRODUCTION
TOP
 INTRODUCTION
RESEARCH DESIGN AND METHODS--
 RESULTS--
 CONCLUSIONS--
 References
 
Type 2 diabetes is characterized by variable degrees of vascular dysfunction (1,2). We have recently reported improved vasomotor responses in high-ferritin type 2 diabetic patients following bloodletting (3), an intervention that is believed to reduce the deleterious effects of circulating iron on vascular function (4,5).

Insulin-like growth factor binding protein–related protein 1 (IGFBP-rP1) is a 30 kDa modular glycoprotein known to be secreted by vascular and nonvascular cells (6–8). Besides its involvement in developmental processes and tumor growth (9,10), IGFBP-rP1 may play a role in the vasculature, given its abundance as an endothelial marker (11–13), its stimulatory actions on prostacyclin synthesis (7), and its vasodilatory effects on the retina of diabetic rats (14).

To our knowledge, no clinical studies have examined the role of serum IGFBP-rP1 as a vascular factor. We hypothesized that circulating IGFBP-rP1 is linked to the vasomotor responses that follow iron depletion in high-ferritin type 2 diabetes.


   RESEARCH DESIGN AND METHODS—
TOP
 INTRODUCTION
 RESEARCH DESIGN AND METHODS--
RESULTS--
 CONCLUSIONS--
 References
 
The study subjects (n = 24 male patients, mean ± SD age 55.5 ± 8.1 years, BMI 29.1 ± 3.6 kg/m2, and A1C 6.2 ± 0.9%), are part of a well-characterized sample of high-ferritin type 2 diabetic patients subjected to bloodletting as previously reported by us (3,15). In the original cohort, 28 diabetic patients with elevated serum ferritin concentrations were randomized to either iron depletion (intervention group; n = 13) or to observation (n = 15) according to a randomization table that included age, BMI, and A1C. The two groups were also matched for pharmacological treatment and chronic diabetes complications. The iron depletion intervention consisted of three blood extractions (each 500 ml) at 2-week intervals. The patients were studied at baseline and 3 months after the last phlebotomy. In the present study, available serum samples were used for measuring IGFBP-rP1 in 10 patients in the intervention group and 14 patients in the observation group (online appendix Table 1 [available at http://dx.doi.org/10.2337/dc06-1905]). The clinical and biochemical characteristics of these subjects were comparable with those of the initial cohort (3).

Subjects were studied in the postabsorptive state. Anthropometry, blood pressure, and insulin sensitivity (KITT, from insulin tolerance tests) were assessed as previously reported (15). Brachial artery vascular reactivity was assessed by a high-resolution external ultrasound (Toshiba SSH-140A) in response both to reactive hyperemia (flow-mediated endothelium-dependent vasodilation [EDV]) and to 400 µg sublingual glyceryl trinitrate, a direct smooth muscle dilator (endothelial-independent vasodilation [EIV]), as previously described (3,16).

Serum glucose, insulin, C-peptide, transferrin, transferrin saturation index, ferritin, and A1C were measured as previously reported (3,15). Whole-blood hemoglobin and hematocrit were determined by routine laboratory tests (Coulter Electronics, Hialeah, FL). Serum IGFBP-rP1 was measured by an enzyme-linked immunosorbent assay with a coefficient of variation <7% (13).

Statistical analyses were performed using SPSS 12.0 software. The study was powered to detect significant changes in serum IGFBP-rP1 of at least 1 SD (paired-samples t test) following phlebotomy.

The experimental protocol was approved by the ethics committee of the Hospital of Girona. Informed written consent was obtained from the study subjects.


   RESULTS—
TOP
 INTRODUCTION
 RESEARCH DESIGN AND METHODS--
 RESULTS--
CONCLUSIONS--
 References
 
At baseline, circulating IGFBP-rP1 was directly correlated with EDV (r = 0.48, P = 0.018) but not with EIV (r = –0.08, P = NS) in high-ferritin type 2 diabetic subjects studied as a single group. IGFBP-rP1 was also correlated with BMI (r = 0.57, P = 0.003) and metabolic parameters (C-peptide [r = 0.58, P = 0.004] and KITT [r = –0.46, P = 0.034] but not A1C [r = 0.03, P = NS]) in these subjects.

As expected, bloodletting caused significant reductions in hemoglobin, ferritin, and transferrin saturation index in the intervention group (P < 0.05 to P < 0.001). In parallel, both serum IGFBP-rP1 and EIV significantly increased in the intervention group but not in the observation group (P < 0.05 and P < 0.01, respectively; online appendix Table 2). Figure 1 depicts significant differences in the absolute changes at 4 months for hemoglobin, IGFBP-rP1, and both EDV and EIV between the two randomization groups (P < 0.05 to P = 0.001). Of note, the changes in IGFBP-rP1 correlated with those of hemoglobin (r = –0.59, P = 0.009) and of EDV (r = 0.58, P = 0.005) at follow-up.


Figure 1
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  		Figure 1— Changes in hemoglobin (Hb), IGFBP-rP1, EDV, and EIV from baseline following 4 months of bloodletting ({blacksquare}; intervention, n = 10) or no treatment ({diamond}; observation, n = 12). (In the observation group, two outlier subjects with significant decreases in hemoglobin values were not included in the analysis; thus, the resulting n for this group was 12.) Changes are expressed as SD scores (SDS), calculated by dividing the absolute changes during the 4 months by the corresponding baseline SD in the study subjects. Plots represent means ± 95% CI. *P < 0.05, **P < 0.01, ***P < 0.001.

 
The novel association between hemoglobin and IGFBP-rP1 was also documented for baseline values in these subjects (r = 0.61, P = 0.002), as well as in a cross-sectional analysis of a sample of nondiabetic men previously reported by us (n = 113; r = 0.28, P = 0.003 [17]).

On multiple regression analyses, both BMI (ß = 0.47, P = 0.01) and hemoglobin (ß = 0.40, P = 0.03), but not other metabolic parameters or ferritin, were independently associated with baseline serum IGFBP-rP1, explaining 34 and 12% of its variance, respectively. Only age (ß = –0.51, P = 0.004) and IGFBP-rP1 (ß = 0.51, P = 0.004) were significantly associated with baseline EDV, explaining 24 and 20% of its variance, respectively, after adjusting for effect modifiers (basal artery diameter, smoking, BMI, C-peptide, insulin sensitivity, A1C, hemoglobin, or ferritin). Multivariate analyses documented also independent associations between the changes in IGFBP-rP1 and those in hemoglobin and EDV on follow-up (data not shown).


   CONCLUSIONS—
TOP
 INTRODUCTION
 RESEARCH DESIGN AND METHODS--
 RESULTS--
 CONCLUSIONS--
References
 
Our results suggest for the first time that circulating IGFBP-rP1 is related to vascular function in high-ferritin type 2 diabetic patients. Bloodletting is associated with improved vasomotor responses (3) and with positive changes in circulating IGFBP-rP1.

Our data concur with previous reports showing stimulatory effects of IGFBP-rP1 on prostacyclin synthesis (7) and on blood flow in the rat retina (14) and suggest that factors associated with endothelial stress, namely obesity and blood hemoglobin, are possible regulators of the serum levels of IGFBP-rP1 in high-ferritin type 2 diabetic subjects (2,18). While it is well known that cell-free hemoglobin acts as a nitric oxide scavenger (19,20), the role of cell-associated hemoglobin (i.e., that carried by erythrocytes) is more complex, as it may act as a nitric oxide generator by virtue of its nitrite reductase activity (21). The current clinical evidence, however, is supportive of a deleterious effect on vascular function also for cell-associated hemoglobin (22,23).

Given the cross-sectional nature of our study, we cannot establish a cause-effect relationship in the sequence of events that follow bloodletting in high-ferritin type 2 diabetic patients, but it is herein suggested that phlebotomy causes increases in circulating IGFBP-rP1 by alleviating the deleterious effects of blood hemoglobin on the vasculature and that increased IGFBP-rP1, in turn, may contribute to improve EDV after bloodletting. Further research will determine whether there is a role for IGFBP-rP1 in the vascular dysfunction of type 2 diabetes.


   Acknowledgments
 
This study was supported by grants PI041407 (to A.L.-B.) and BFU2004-03654/BFI and CB06/03/0010 (to J.M.F.-R.). A.L.-B. is a research investigator of the Fund for Scientific Research "Ramon y Cajal," Spain.


   Footnotes
 
Published ahead of print at http://care.diabetesjournals.org on 10 March 2007. DOI: 10.2337/dc06-1905.

Additional information for this article can be found in an online appendix at http://dx.doi.org/10.2337/dc06-1905.

R.G.R. has received honoraria from Genentech, Lilly, Tercica, Novo, and Pfizer.

A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C Section 1734 solely to indicate this fact.

Received for publication September 12, 2006. Accepted for publication February 15, 2007.


   References
TOP
 INTRODUCTION
 RESEARCH DESIGN AND METHODS--
 RESULTS--
 CONCLUSIONS--
 References
 

  1. Feener EP, King GL: Vascular dysfunction in diabetes mellitus. Lancet 350 (Suppl. 1):SI9–SI13, 1997
  2. Schalkwijk CG, Stehouwer CD: Vascular complications in diabetes mellitus: the role of endothelial dysfunction. Clin Sci (Lond) 109:143–159, 2005[Medline]
  3. Fernandez-Real JM, Penarroja G, Castro A, Garcia-Bragado F, Lopez-Bermejo A, Ricart W: Blood letting in high-ferritin type 2 diabetes: effects on vascular reactivity. Diabetes Care 25:2249–2255, 2002[Abstract/Free Full Text]
  4. Pieper GM, Siebeneich W: Diabetes-induced endothelial dysfunction is prevented by long-term treatment with the modified iron chelator, hydroxyethyl starch conjugated-deferoxamine. J Cardiovasc Pharmacol 30:734–738, 1997[Medline]
  5. Nitenberg A, Paycha F, Ledoux S, Sachs R, Attali JR, Valensi P: Coronary artery responses to physiological stimuli are improved by deferoxamine but not by L-arginine in non-insulin-dependent diabetic patients with angiographically normal coronary arteries and no other risk factors. Circulation 97:736–743, 1998[Abstract/Free Full Text]
  6. Ono Y, Hashimoto T, Umeda F, Masakado M, Yamauchi T, Mizushima S, Isaji M, Nawata H: Expression of prostacyclin-stimulating factor, a novel protein, in tissues of Wistar rats and in cultured cells. Biochem Biophys Res Commun 202:1490–1496, 1994[Medline]
  7. Yamauchi T, Umeda F, Masakado M, Isaji M, Mizushima S, Nawata H: Purification and molecular cloning of prostacyclin-stimulating factor from serum-free conditioned medium of human diploid fibroblast cells. Biochem J 303:591–598, 1994[Medline]
  8. Swisshelm K, Ryan K, Tsuchiya K, Sager R: Enhanced expression of an insulin growth factor-like binding protein (mac25) in senescent human mammary epithelial cells and induced expression with retinoic acid. Proc Natl Acad Sci U S A 92:4472–4476, 1995[Abstract/Free Full Text]
  9. Sprenger CC, Damon SE, Hwa V, Rosenfeld RG, Plymate SR: Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) is a potential tumor suppressor protein for prostate cancer. Cancer Res 59:2370–2375, 1999[Abstract/Free Full Text]
  10. Burger AM, Leyland-Jones B, Banerjee K, Spyropoulos DD, Seth AK: Essential roles of IGFBP-3 and IGFBP-rP1 in breast cancer. Eur J Cancer 41:1515–1527, 2005[Medline]
  11. St Croix B, Rago C, Velculescu V, Traverso G, Romans KE, Montgomery E, Lal A, Riggins GJ, Lengauer C, Vogelstein B, Kinzler KW: Genes expressed in human tumor endothelium. Science 289:1197–1202, 2000[Abstract/Free Full Text]
  12. Akaogi K, Okabe Y, Sato J, Nagashima Y, Yasumitsu H, Sugahara K, Miyazaki K: Specific accumulation of tumor-derived adhesion factor in tumor blood vessels and in capillary tube-like structures of cultured vascular endothelial cells. Proc Natl Acad Sci U S A 93:8384–8389, 1996[Abstract/Free Full Text]
  13. Lopez-Bermejo A, Khosravi J, Corless CL, Krishna RG, Diamandi A, Bodani U, Kofoed EM, Graham DL, Hwa V, Rosenfeld RG: Generation of anti-insulin-like growth factor-binding protein-related protein 1 (IGFBP-rP1/MAC25) monoclonal antibodies and immunoassay: quantification of IGFBP-rP1 in human serum and distribution in human fluids and tissues. J Clin Endocrinol Metab 88:3401–3408, 2003[Abstract/Free Full Text]
  14. Hata Y, Clermont A, Yamauchi T, Pierce EA, Suzuma I, Kagokawa H, Yoshikawa H, Robinson GS, Ishibashi T, Hashimoto T, Umeda F, Bursell SE, Aiello LP: Retinal expression, regulation, and functional bioactivity of prostacyclin-stimulating factor. J Clin Invest 106:541–550, 2000[Medline]
  15. Fernandez-Real JM, Penarroja G, Castro A, Garcia-Bragado F, Hernandez-Aguado I, Ricart W: Blood letting in high-ferritin type 2 diabetes: effects on insulin sensitivity and beta-cell function. Diabetes 51:1000–1004, 2002[Abstract/Free Full Text]
  16. Celermajer DS, Sorensen KE, Gooch VM, Spiegelhalter DJ, Miller OI, Sullivan ID, Lloyd JK, Deanfield JE: Non-invasive detection of endothelial dysfunction in children and adults at risk of atherosclerosis. Lancet 340:1111–1115, 1992[Medline]
  17. Lopez-Bermejo A, Khosravi J, Fernandez-Real JM, Hwa V, Pratt KL, Casamitjana R, Garcia-Gil MM, Rosenfeld RG, Ricart W: Insulin resistance is associated with increased serum concentration of IGF-binding protein-related protein 1 (IGFBP-rP1/MAC25). Diabetes 55:2333–2339, 2006[Abstract/Free Full Text]
  18. Gow AJ, Luchsinger BP, Pawloski JR, Singel DJ, Stamler JS: The oxyhemoglobin reaction of nitric oxide. Proc Natl Acad Sci U S A 96:9027–9032, 1999[Abstract/Free Full Text]
  19. Rother RP, Bell L, Hillmen P, Gladwin MT: The clinical sequelae of intravascular hemolysis and extracellular plasma hemoglobin: a novel mechanism of human disease. JAMA 293:1653–1662, 2005[Abstract/Free Full Text]
  20. Faivre-Fiorina B, Caron A, Fassot C, Fries I, Menu P, Labrude P, Vigneron C: Presence of hemoglobin inside aortic endothelial cells after cell-free hemoglobin administration in guinea pigs. Am J Physiol 276:H766–H770, 1999[Medline]
  21. Kim-Shapiro DB, Schechter AN, Gladwin MT: Unraveling the reactions of nitric oxide, nitrite, and hemoglobin in physiology and therapeutics. Arterioscler Thromb Vasc Biol 26:697–705, 2006[Abstract/Free Full Text]
  22. Natali A, Toschi E, Baldeweg S, Casolaro A, Baldi S, Sironi AM, Yudkin JS, Ferrannini E: Haematocrit, type 2 diabetes, and endothelium-dependent vasodilatation of resistance vessels. Eur Heart J 26:464–471, 2005[Abstract/Free Full Text]
  23. Madsen PL, Scheuermann Freestone M, Neubauer S, Channon K, Clarke K: Haemoglobin and flow-mediated vasodilation. Clin Sci (Lond) 110:467–473, 2006[Medline]

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