The Insulin-Like Growth Factor System in Human Immunodeficiency Virus Infection:
  Relations to Immunological Parameters, ...
0021-972X/01/$03.00/0                                                                                                     ...
228                                                                   HELLE ET AL.                                        ...
THE IGF SYSTEM AND HIV INFECTION                                                            229

evaluated by densitometri...
230                                                       HELLE ET AL.                                                    ...
THE IGF SYSTEM AND HIV INFECTION                                                                    231

F IG . 3. Alte...
232                                                                  HELLE ET AL.                                         ...
THE IGF SYSTEM AND HIV INFECTION                                                                               233

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  1. 1. The Insulin-Like Growth Factor System in Human Immunodeficiency Virus Infection: Relations to Immunological Parameters, Disease Progression, and Antiretroviral Therapy S. I. Helle, T. Ueland, D. Ekse, S. S. Frøland, J. M. P. Holly, P. E. Lønning and P. Aukrust J. Clin. Endocrinol. Metab. 2001 86: 227-233, doi: 10.1210/jc.86.1.227 To subscribe to Journal of Clinical Endocrinology & Metabolism or any of the other journals published by The Endocrine Society please go to: Copyright © The Endocrine Society. All rights reserved. Print ISSN: 0021-972X. Online
  2. 2. 0021-972X/01/$03.00/0 Vol. 86, No. 1 The Journal of Clinical Endocrinology & Metabolism Printed in U.S.A. Copyright © 2001 by The Endocrine Society The Insulin-Like Growth Factor System in Human Immunodeficiency Virus Infection: Relations to Immunological Parameters, Disease Progression, and Antiretroviral Therapy* S. I. HELLE, T. UELAND, D. EKSE, S. S. FRØLAND, J. M. P. HOLLY, P. E. LØNNING, AND P. AUKRUST Department of Oncology, Haukeland University Hospital (S.I.H., D.E., P.E.L.), N-5021 Bergen, Norway; Sections of Clinical Immunology and Infectious Diseases (P.A., S.S.F.), Endocrinology (T.U.), Medical Department, and Research Institute for Internal Medicine (P.A., S.S.F.), National Hospital-Rikshospitalet, Oslo, Norway; and Department of Surgery (J.M.P.H.), Bristol Royal Infirmary, Bristol, United Kingdom ABSTRACT correlated positively to virus load (P 0.001) and tumor necrosis Endocrine dysfunctions have previously been reported in human factor- (P 0.025) and negatively to CD4 and CD8 cell counts (P immunodeficiency virus (HIV) infection. In this study we evaluated 0.001). AIDS patients with wasting (n 13) had lower IGF-II levels the relation of immunological parameters, virus load, clinical stage, (P 0.001) and higher IGFBP-2 levels (P 0.001) than other AIDS and wasting to several parameters of the insulin-like growth factor patients. Although no significant change in any of the IGF-parame- (IGF) system in 76 patients with HIV infection, of whom 37 had ters was observed in patients during antiretroviral therapy, patients developed acquired immune deficiency syndrome (AIDS). A subgroup with elevated IGFBP-3 protease activity before therapy (5 of 34) all of 26 untreated patients was followed during longitudinal testing, had a decrease during treatment. During longitudinal testing in pa- while the effects of antiretroviral therapy were evaluated in 34 pa- tients followed without antiretroviral therapy, disease progression tients (nucleoside analogs in 9, nucleoside analogs in combination was associated with increases in IGFBP-3 protease activity and with protease inhibitors in 25). Twenty healthy sex- and age-matched IGFBP-2 levels. Our results reveal several alterations in the IGF controls were analyzed for comparison. system during HIV infection with decreased IGF-II levels, increased IGF-II was decreased (P 0.03) and IGF-binding protein-2 concentration of IGFBP-2, and an increased IGFBP-3 protease ac- (IGFBP-2) and IGFBP-3 protease activity were increased (P 0.001) tivity in advanced disease. (J Clin Endocrinol Metab 86: 227–233, in AIDS patients compared with other HIV-infected individuals and 2001) controls. Plasma levels of IGFBP-2 and IGFBP-3 protease activity I NFECTION WITH human immunodeficiency virus (HIV) causes progressive immunodeficiency, predisposing to a number of secondary diseases. These include a variety of quired immune deficiency syndrome (AIDS) patients with wasting and in children who fail to thrive (9, 10). IGF-I plays a pivotal role in many physiological processes opportunistic infections, malnourishment, and diarrhea (1) as the mediator of the effects of GH (11). Although it executes as well as an elevated risk for different malignancies, in its function as a ligand to the IGF-I receptor, its action is particular lymphoma (2) and Kaposi’s sarcoma (3). Several modified by six IGF-binding proteins (IGFBPs), which have factors may be involved in the pathogenesis of these condi- been shown to enhance or inhibit its biological activity de- tions including numerical and functional disturbances of pending on experimental conditions (12). The major IGFBP CD4 T cells (4), increased production of proinflammatory in the circulation is IGFBP-3. Together with another protein, cytokines (5), and altered function of monocytes/macro- the acid-labile subunit, IGFBP-3 forms a 150-kDa ternary phages (4). complex with IGF-I or -II that binds more than 90% of cir- Although these immunological factors may be responsible culating IGF-I in normal subjects. IGFBP-3 is subject to pro- for the bulk of the pathological changes observed, HIV in- teolysis (13), resulting in fragments still able to complex with fection is also associated with various endocrine abnormal- acid-labile subunit and IGFs, but with a significantly reduced ities, such as altered bone homeostasis, hypogonadism, ad- affinity. Protease activity for IGFBP-3 has been found to be renal and thyroid dysfunction as well as hyperinsulinemia elevated in pregnancy (14), but also after major surgery (15, (6 – 8). There are also some pilot studies indicating distur- 16) and in patients suffering from septicemia (17) or cancer bances in the insulin-like growth factor (IGF) system in ac- (18, 19). Several previous findings indicate a role for the IGF system Received May 2, 2000. Revision received September 12, 2000. in the pathogenesis of HIV infection. In addition to potent Accepted September 19, 2000. anabolic effects, recent studies suggest that the IGF system Address all correspondence and requests for reprints to: Prof. Per E. Lønning, Department of Oncology, Haukeland University Hospital, may be involved in various immunological and inflamma- N-5021 Bergen, Norway. tory processes, such as monocyte chemotaxis and activation, * This work was supported by the Norwegian Cancer Society. induction of inflammatory cytokines [e.g. tumor necrosis fac- 227
  3. 3. 228 HELLE ET AL. JCE & M • 2001 Vol. 86 • No. 1 tor- (TNF )] (20), and regulation of apoptosis (21). De- 106/L], and 13 were defined as nonprogressors (none had developed creased levels of IGF-I may enhance lymphocyte apoptosis. AIDS, and all had CD4 T cell counts 150 106/L). Previous studies have described a reduction in serum IGF-I Group 3. Another subgroup of 34 patients from group 1 was followed and IGFBP-3 as well as increased IGFBP-3 protease activity during antiretroviral therapy. For these patients, the pretreatment sam- in HIV-infected patients (9, 10). We hypothesize that alter- ple was the one used in the cross-sectional analysis. Twenty-five patients ations in the IGF system during HIV infection, in particular received highly active antiretroviral therapy (HAART) with a protease inhibitor in combination with 2 nucleoside analogs. For comparison 9 increased IGFBP-3 protease activity, are secondary events patients receiving only 2 nucleoside analogs (i.e. lamivudine and zidovu- related to disease activity and thus are potentially reversible dine) were also selected for the study. They had immunological and by specific therapy similar to our previous findings in breast virological responses similar to those of the patients receiving HAART. cancer patients (22). To test this hypothesis, we evaluated Blood samples were obtained before treatment and later at 3-month intervals. alteration in the IGF system in relation to virus load and clinical and immunological parameters in different stages of Blood sampling protocol HIV infection in a cross-sectional study as an attempt to find any mechanistic links among these parameters. We also ex- Venous blood was sampled into pyrogen-free blood collection tubes amined the influence of antiretroviral therapy as well as the (Becton Dickinson and Co., San Jose, CA) with ethylenediamine tet- raacetate as anticoagulant. Tubes were immediately immersed in melt- natural course of the disease on the IGF system in subgroups ing ice and centrifuged (1000 g for 10 min) within 30 min. Plasma was of the patients included. stored at 80 C, and samples were thawed only once. Subjects and Methods Materials Patients and controls Human recombinant IGF-I and IGF-II were purchased from GroPep Group 1: cross-sectional analysis. Seventy-six HIV-seropositive patients Pty. Ltd. (Adelaide, Australia). IGF-I and IGF -II were iodinated using were included in the study (59 men and 17 women; median age, 37 yr; the chloramine-T method. Labeled peptide was separated from nonin- range, 17– 65 yr). Patients with ongoing acute or exacerbation of chronic corporated 125I by AcA 202 columns (BioSepra, Villeneuve, France) using infection at the time of blood collection were not included. Based on their 1 40-cm columns. clinical symptoms, the patients were classified according to the revised criteria from Center for Disease Control and Prevention (CDC): 1) Assays asymptomatic HIV-infected patients (n 26; CDC group A), 2) symp- tomatic non-AIDS HIV-infected patients (n 13; CDC group B), and 3) Plasma levels of IGF-I (23) and IGF-II (17) were measured by RIA after patients suffering from AIDS (n 37; CDC group C). Clinical and acid-acetone extraction (24). Intra- and interassay coefficients of varia- immunological characteristics of the patients are shown in Table 1. tions were 3.5% and 6.2% for IGF-I and 5.5% and 12.9% for IGF-II, Serum levels of alanine aminotransferase were less than 50 U/L, and respectively. Free IGF-I, IGFBP-3, and IGFBP-2 were measured by com- serum creatinine levels were less than 100 mol/L in all patients. Fifty mercial kits (immunoradiometric assay/RIA) purchased from Diagnos- patients received antiretroviral therapy with nucleoside analog(s), but tics Systems Laboratories, Inc. (Webster, TX) according to the manu- none received HIV protease inhibitors, and none had initiated or facturer’s instructions. changed therapy during the last 5 months before blood sampling. The IGFBP profile in the plasma was analyzed by Western ligand Twenty healthy HIV-seronegative sex- and age-matched blood donors blotting (WLB) using a modified version (25) of the technique originally were included as controls (Table 1). Oral informed consent for partic- developed by Hossenlopp (26). Radiolabeled IGFBPs were visualized by ipating in the study was obtained from all patients and controls ac- autoradiography and quantified using a densitometric scanner (Phar- cording to Norwegian regulations (6). macia Biotech, Uppsala, Sweden). The IGFBP pattern was compared with the profile of a normal plasma pool (NP), and samples from each Group 2. A subgroup of 26 patients (all included in group 1) were patient were analyzed in the same run for comparison. After WLB, the observed over several years without antiretroviral therapy. These pa- membranes were immunoblotted using a polyclonal antiserum against tients had blood samples taken at regular intervals for up to 6 yr. For each IGFBP-3 (Diagnostics Systems Laboratories, Inc., Webster, TX) at a final of these patients, the last sample obtained was the one used in the dilution of 1:10,000. The membranes were then developed using en- cross-sectional analysis (group 1). At the time of the first blood sampling hanced chemiluminescent reagents supplied by Amersham Pharmacia all patients were in CDC group A or B, and all had CD4 T cell counts Biotech (Aylesbury, UK) according to the manufacturer’s instructions, between 200 –500 106/L. At the end of the observation period, 13 of and the films were subjected to densitometric scanning. IGFBP-3 pro- the patients were defined as progressors [all developed AIDS (8 had died tease activity was measured indirectly as IGFBP-3 fragmentation, de- of HIV-related events) and all had a fall in CD4 T cell counts to 50 fined as the ratio of the major IGFBP-3 fragment (30 kDa) to total IGFBP-3 TABLE 1. Clinical characteristics of the 76 patients and 20 controls included in the study): CDC group A (asymptomatic HIV infected patients), CDC group B (symptomatic non-AIDS HIV-infected patients), and CDC group C (patients suffering from AIDS) Controls CDC group A CDC group B CDC group C No. of patients 20 26 13 37 Median age (range) 38 (22– 60) 41 (22–57) 38 (23– 65) 39 (17– 62) Males/females 15/5 18/8 11/2 32/5 CD4 lymphocytes ( 106/L) 608 (539 – 685) 257 (214 –311) 114 (59 –221) 15 (10 –25) CD8 lymphocytes ( 106/L) 286 (238 –344) 772 (654 –912) 558 (403–772) 202 (138 –296) HIV-1 RNA (103 copies/mL plasma) 24.9 (9.7– 64.4) 60.4 (14.4 –253.2) 364.0 (219.5– 604.4) TNF (pmol/L) 0.4 (0.3– 0.5) 1.3 (1.1–1.5) 1.5 (1.0 –2.2) 4.6 (3.2– 6.7) Glucose (mmol/L)a 5.0 (4.7–5.4) 5.0 (4.6 –5.4) 5.1 (4.7–5.5) Triglycerides (mmol/L)a 1.6 (1.1–2.0) 1.9 (1.3–2.5) 3.6 (2.9 – 4.2) Cholesterol (mmol/L)a 5.2 (4.8 – 6.2) 5.5 (5.0 – 6.0) 5.1 (4.7–5.6) Values of laboratory parameters are given as mean (with 95% confidence intervals of the mean value). a Fasting blood samples.
  4. 4. THE IGF SYSTEM AND HIV INFECTION 229 evaluated by densitometric scanning on immunoblots. A ratio above 0.5 was arbitrarily considered elevated IGFBP-3 protease activity. Plasma HIV ribonucleic acid levels were measured by quantitative reverse PCR (Amplicor HIV Monitor, Roche, Branchburg, NJ; detection limit, 200 copies/mL). The numbers of CD4 and CD8 T cells in peripheral blood were determined by immunomagnetic quantification. Plasma TNF , triglycerides, and cholesterol were measured as previous described (27). Statistical analysis In a previous study we found plasma levels of IGF-I and -II to be well fitted to a log normal distribution, whereas IGFBP-3 was normally dis- tributed (22). Thus, parameters are given as their geometric mean value with 95% confidence intervals of the mean, with the exception of IGFBP-3 RIA for which arithmetic mean values are given. The measured parameters obtained in different patient groups were compared using ANOVA or Student’s t test. Correlations between different parameters were tested using the SYSTAT program (Systat, Evanston, IL) on a Macintosh computer. Univariate analyses were performed using the Pearson correlation coefficient. Results Group 1: the IGF system in relation to clinical, immunological, and virological parameters in HIV-infected patients: cross-sectional analysis Comparing the control group (n 20), CDC group A (n 26), CDC group B (n 13), and patients with AIDS (CDC group C; n 37) revealed significant differences among the groups in plasma levels of IGF-II and IGFBP-2 as well as IGFBP-3 protease activity (Fig. 1, see P values in footnote). In summary, IGF-II levels were higher in normal subjects, whereas IGFBP-2 and IGFBP-3 protease activities were increased in AIDS patients compared with the other groups. Correlations between virological and immunological pa- rameters and IGF parameters are shown in Table 2. Signif- icant correlations were observed between the IGFBP-2 levels and IGFBP-3 protease activity, on the one side, and virus load, TNF levels (positive correlation), and CD4 and CD8 T cell counts (negative correlations) on the other side. We also observed a strong positive correlation (rp 0.500; P 0.001) between IGFBP-2 concentration and IGFBP-3 protease activ- ity. Plasma levels of triglycerides correlated positively to TNF (rp 0.868; P 0.001), IGFBP-2 (rp 0.542; P 0.001), and IGFBP-3 protease activity (rp 0.482; P 0.001). FIG. 1. Mean values of IGF-II (A), IGFBP-2 (RIA; B), and IGFBP-3 protease activity (C; given as fragmented to total IGFBP-3) with 95% Wasting in AIDS patients confidence intervals in controls (n 20), asymptomatic HIV-infected Thirteen of 37 patients with AIDS had wasting. These patients in (CDC group A; n 26), symptomatic non-AIDS patients (CDC group B; n 13), as well as patients with AIDS (CDC group C; patients had significantly lower levels of IGF-II (mean level, n 37). A, By ANOVA: controls vs. CDC A vs. CDC B vs. CDC C, P 33.2 nmol/L; 95% confidence interval, 25.0 – 44.2; vs. mean, 0.060; controls vs. CDC (A B) vs. CDC C, P 0.028. By paired 55.8 nmol/L; 95% confidence interval, 48.7– 63.8; P 0.001) comparisons: controls vs. CDC (A B), P 0.035 CDC (A B) vs. CDC and IGFBP-3 (P 0.04), but higher levels of IGFBP-2 (P C, P 0.33. B, By ANOVA: controls vs. CDC A vs. CDC B vs. CDC 0.01) compared with AIDS patients without wasting (Fig. 2). C, P 0.001; controls vs. CDC (A B) vs. CDC C, P 0.001. By paired comparisons: controls vs. CDC (A B), P 0.001; CDC (A B) vs. CDC C, P 0.001. C, By ANOVA: controls vs. CDC A vs. CDC B vs. CDC Group 2: longitudinal analysis of IGF parameters in HIV- C, P 0.001; controls vs. CDC (A B) vs. CDC C, P 0.001. By paired infected patients comparisons: controls vs. CDC (A B), P 0.986; CDC (A B) vs. CDC C, P 0.001. Of the 26 patients followed without any antiviral therapy over several years (group B), disease remained stable in 13 nificant increase in the levels of IGFBP-2 and IGFBP-3 pro- but progressed in the others (see Materials and Methods for tease activity and a decrease in intact IGFBP-3 measured by definition). Although no changes were observed in the IGF Western ligand blot among patients with progressive disease parameters in patients with stable disease, we found a sig- (Fig. 3).
  5. 5. 230 HELLE ET AL. JCE & M • 2001 Vol. 86 • No. 1 TABLE 2. Group 1: correlations between immunological parameters and IGF parameters using Pearsons correlation test (rp) CD4 T cells CD8 T cells Virus load TNF (n 76) (n 76) (n 72) (n 72) IGF-I 0.321a 0.157 0.024 0.219 IGF-II 0.090 0.079 0.031 0.245b F-IGF-I 0.106 0.250b 0.067 0.059 IGFBP-2, RIA 0.633c 0.477c 0.482c 0.603c IGFBP-3, RIA 0.153 0.136 0.119 0.220 IGFBP-3, protease 0.572c 0.467c 0.418c 0.525c a P 0.01. b P 0.05. c P 0.001. patients with wasting and in HIV-infected children (9, 10). First, we found that the most marked alteration in the IGF system during HIV infection was a decrease in IGF-II levels accompanied by raised IGFBP-2 levels and increased IGFBP-3 protease activity, as demonstrated in both cross-sectional and longitudinal testing. Second, some of these disturbances in the IGF system (i.e. decreased IGF-II and raised IGFBP-2 levels) were not restricted to AIDS patients, but were also found in HIV-infected patients who had not developed AIDS. Third, the alterations in the IGF system, particularly raised IGFBP-2 levels and IGFBP-3 protease activity, were correlated to advanced clinical, immunological, and virolog- ical disease. Finally, in patients with enhanced IGFBP-3 pro- tease activity, potent antiretroviral therapy induced a FIG. 2. Plasma levels (nanomoles per mL) of IGFBP-2 and IGFBP-3 marked decrease in this protease activity, significantly cor- (with 95% confidence intervals of the mean) in AIDS patients with related with the virological and immunological effects of wasting (n 13) compared with those in AIDS patients without such therapy. wasting (n 24). In the cross-sectional part of this study we found a close Group 3: the IGF system during antiretroviral therapy relationship between CD4 and CD8 cell counts as well as A total of 34 patients were treated with 2 nucleoside an- viral load, on the one side, and IGFBP-3 protease activity and alogs (n 9) or a combination of a protease inhibitor and 2 plasma IGFBP-2, on the other side. Interestingly, we also nucleoside analogs (HAART; n 25). No difference between observed a strong positive correlation between IGFBP-2 lev- the 2 treatment groups was found, suggesting that any effects els and IGFBP-3 protease activity. The observation that on the IGF system during therapy were not related to the use plasma levels of IGFBP-2 levels, contrary to IGFBP-3 protease of protease inhibitor. The data were therefore pooled for activity, were elevated in HIV-infected patients without statistical analysis. We observed no significant change dur- AIDS suggests this binding protein to be the first IGF pa- ing treatment in any of the IGF parameters, with the excep- rameter to change in this patient group. The mechanism tion of IGFBP-3 measured by Western ligand blot (Table 3). behind this observation is not known. Increased IGFBP-2 However, there was a significant positive correlation be- levels have been found in other conditions, such as prostatic tween alterations in virus load and IGFBP-3 protease activity cancer and lymphoma (28, 29), as well as in diabetes mellitus (rp 0.441; P 0.04) and a negative correlation between (30). Interestingly, the expression of this binding protein has alterations in IGFBP-3 protease activity (rp 0.497; P also been found in monocytes and T cells, with markedly 0.019) and CD8 T cell counts after 3 months of treatment. enhanced expression during activation of these cells (31). Also, we observed a negative correlation between alterations HIV-infected patients are characterized by a sustained acti- in the numbers of CD4 (rp 0.538; P 0.01) and CD8 vation of monocytes and T cells (1, 4). It is tempting to (rp 0.447; P 0.037) T cells, on the one side, and IGFBP-2, hypothesize that the raised IGFBP-2 levels as well as other on the other. All of these correlations, with exception of that alterations in the IGF system during HIV infection may be between CD8 and IGFBP-2 (P 0.066), were still significant related to such a persistent immune activation in vivo. Our when analyzing the HAART group alone. demonstration of a significant correlation between enhanced Only five of the patients receiving antiretroviral therapy TNF levels and several disturbances in the IGF system had an elevated ratio of fragmented to total IGFBP-3 ( 0.5) further support such an idea. before commencing therapy. Each of these patients had a Advanced cancer (18, 29), poorly regulated diabetes mel- decrease in IGFBP-3 protease activity during therapy. litus (32), critical illness (33), and major surgery (15, 16) have all been found to produce elevated IGFBP-3 protease activity. Discussion All of these conditions have in common an increased capil- Our study confirms and extends some observations re- lary permeability in affected organs. IGFBP-3 protease ac- corded in two previous smaller studies by Frost et al. in AIDS tivity is increased in extracellular fluid (34, 35), whereas little
  6. 6. THE IGF SYSTEM AND HIV INFECTION 231 F IG . 3. Alterations in IGF-I (A), IGFBP-2 (B), IGFBP-3 protease activ- ity (C), and IGFBP-3 (D; by Western ligand blot) shown as the percent change from baseline levels with 95% confidence intervals in HIV-infected patients observed without specific an- tiviral treatment, comparing patients with stable disease (open symbols) and progressive disease (closed symbols). For definition of disease progression, see Materials and Methods. TABLE 3. Values of IGF-I, F-IGF-I, IGF-II, IGFBP-2, and IGFBP-3 measured by RIA/IRMA and of IGFBP-2, -3, and -4 by Western ligand blot (WLB) before and percentage of pretreatment levels/percent change at various intervals in patients with HIV infection during treatment with protease inhibitors and nucleotide analogs (see Materials and Methods) Measured levels (nmol/L) % of pretreatment levels Before treatment (n 34) 3 months (n 22) 6 months (n 20) 9 months (n 9) 12 months (n 21) 18 months (n 13) IGF-I 20.9 (18.6 –22.4) 106 (86 –113) 98 (86 –113) 121 (89 –164) 99 (90 –109) 103 (90 –120) IGF-II 49.7 (43.4 –57.6) 105 (98 –113) 102 (95–109) 105 (94 –117) 112 (99 –127) 108 (89 –132) F-IGF-I 0.20 (0.14 – 0.25) 107 (85–134) 102 (83–125) 101 (71–143) 100 (79 –128) 110 (70 –174) IGFBP-2, RIA 28.9 (25.7–32.4) 95 (85–107) 100 (88 –115) 80 (62–103) 93 (84 –103) 88 (73–105) IGFBP-2,a WLB 12.9 (9.8 –17.1) 94 (82–109) 107 (87–130) 71 (51–98) 90 (74 –109) 97 (63–151) IGFBP-3, RIA 108.6 (94.5–122.7) 106 (96 –115) 109 (101–116) 120 (100 –141) 108 (98 –119) 105 (93–117) IGFBP-3,a WLB 148 (115–190) 121 (106 –138) 121 (103–143) 141 (109 –182) 119 (100 –141) 152 (109 –210) IGFBP-3,b protease 0.29 (0.23– 0.36) 83 (73–94) 97 (78 –120) 64 (45–91) 91 (73–114) 84 (53–134) IGFBP-4,a WLB 2.8 (2.1–3.7) 86 (68 –110) 81 (65–101) 78 (52–116) 92 (68 –124) 99 (66 –146) a Arbitrary units. b Ratio of fragmented to total IGFBP-3. intravascular IGFBP-3 protease activity occurs in healthy HAART. This may be due to several factors. The number of subjects (36). We recently demonstrated endothelial dysfunc- patients with advanced disease in this part of the study was tion during HIV infection (37), possibly secondary to en- limited. We observed a pretreatment mean value of ratio of hanced activation of inflammatory cytokines (38). Notably, fragmented to total IGFBP-3 of 0.29, which does not differ inflammatory cytokines such as IL-1 and TNF have also much from what has been recorded in normal subjects (36). been found to enhance IGFBP-3 protease activity (39), and However, all five patients with a ratio of fragmented to total similar mechanisms may well be operating in HIV-infected IGFBP-3 greater than 0.5 had a decrease in this ratio with a individuals. corresponding increase in IGFBP-3 measured with Western We found no significant impact on the IGF system during ligand blot after 3– 6 months of treatment. Any significant
  7. 7. 232 HELLE ET AL. JCE & M • 2001 Vol. 86 • No. 1 effects may thus be masked by minor alterations in patients 6. Aukrust P, Haug C, Ueland T, et al. 1999 Decreased bone formation and enhanced resorptive markers in human immunodeficiency virus infection: with near-normal IGFBP-3 protease activity. The small num- indication of normalization of the bone-remodeling process during highly ber of observations does not permit any firm conclusion active antiretroviral therapy. J Clin Endocrinol Metab. 84:145–150. regarding this issue, but the decrease in inflammatory cy- 7. Danoff A. 1996 Endocrinological complications of HIV infection. Med Clin North Am. 80:1453–1469. tokines, including TNF (40), during HAART may be one 8. Hadigan C, Miller K, Corcoran C, Anderson E, Basgoz N, Grinspoon S. 1999 possible effector mechanism. Fasting hyperinsulinemia and changes in regional body composition in human Treatment with protease inhibitors is frequently associ- immunodeficiency virus-infected women. J Clin Endocrinol Metab. 84:1932–1937. 9. Frost RA, Nachman SA, Lang CH, Gelato MC. 1996 Proteolysis of insulin-like ated with a syndrome of lipodystropy, hyperlipidemia, and growth factor-binding protein-3 in human immunodeficiency virus-positive insulin resistance (41). Our data do not suggest alterations in children who fail to thrive. J Clin Endocrinol Metab. 81:2957–2962. the IGF system to be involved in its development, but we 10. Frost RA, Fuhrer J, Steigbigel R, Mariuz P, Lang CH, Gelato MC. 1996 Wasting in the aquired immune deficiency syndrome is associated with mul- have not been able to fully evaluate this issue due to lack of tiple defects in the serum insulin-like growth factor system. Clin Endocrinol data on insulin and lipid parameters during treatment. (Oxf). 44:501–514. Alterations in IGF parameters in patients with clinical 11. Jones JI, Clemmons DR. 1995 Insulin-like growth factors and their binding proteins: biological actions. Endocr Rev. 16:3–34. disease progression in the longitudinal part of the study 12. Clemmons DR. 1998 Role of insulin-like growth factor binding proteins in resemble what has been observed in cancer patients with controlling IGF actions. Mol Cell Endocrinol. 140:19 –24. 13. Lassarre C, Binoux M. 1994 Insulin-like growth factor binding protein-3 is progressive disease (22). This may indicate a common final functionally altered in pregnancy plasma. Endocrinology. 134:1254 –1262. pathway behind the increase in IGFBP-3 protease activity. 14. Giudice LC, Farrell EM, Pham H, Lamson G, Rosenfeld RG. 1990 Insulin-like Both AIDS and cancer patients develop wasting in the ad- growth factor binding proteins in maternal serum throughout gestation and in the puerperium: effects of a pregnancy associated serum protease activity. vanced setting. Only plasma levels of IGF-II (decreased) and J Clin Endocrinol Metab. 71:806 – 816. IGFBP-2 (increased) were different between AIDS patients 15. Cotterill AM, Mendel P, Holly JMP, et al. 1996 The differential regulation of with and without wasting. No clear relation to IGFBP-3 pro- the circulating levels of the insulin-like growth factors and their binding proteins (IGFBP) 1,2 and 3 after elective abdominal surgery. Clin Endocrinol tease activity, IGF-I, and free IGF-I could be found. However, (Oxf). 44:91–101. the small number of patients in this part of the analysis, 16. Cwyfan-Hughes SC, Cotterill AM, Molloy AR, et al. 1992 The induction of comparing rather similar groups regarding disease severity, specific proteases for insulin-like growth factor-binding proteins following major heart surgery. J Endocrinol. 135:135–145. does not refute the importance of the IGF system in devel- 17. Davies SC, Wass JAH, Ross RJM, et al. 1991 The induction of a specific opment of wasting. protease for insulin-like growth factor binding protein-3 in the circulation Although it is speculative to draw any firm conclusions during severe illness. J Endocrinol. 130:469 – 473. 18. Frost VJ, Helle SI, Lønning PE, van der Stappen JWJ, Holly JMP. 1996 Effects when evaluating such a complicated system, our data sup- of treatment with megestrol acetate, aminoglutethimide or formestane on port a reduced amount of bioavailable IGFs to the normal insulin-like growth factor (IGF) I and II, IGF-binding proteins (IGFBPs) and tissue in advanced HIV infection due primarily to decreased IGFBP-3 protease status in patients with advanced breast cancer. J Clin En- docrinol Metab. 81:2216 –2221. levels of IGF-II. Furthermore, a decreased amount of intact 19. Muller HL, Oh Y, Gargosky SE, Lehrnbecher T, Hinz RL, Rosenfeld RG. 1993 ¨ IGFBP-3 depletes the normal plasma depot of IGFs in the Concentrations of insulin-like growth factor (IGF)-binding protein-3 (IGFBP- 3), IGF, and IGFBP-3 protease activity in cerebrospinal fluid of children with 150-kDa complex, causing redistribution of these growth leukemia, central nervous system tumor, or meningitis. J Clin Endocrinol factors to IGFBP-2, which may act as an alternative carrier. Metab. 77:1113–1119. However, this low molecular mass complex has a higher 20. Renier G, Clement I, Desfaits A-C, Lambert A. 1996 Direct stimulatory effect of insulin-like growth factor-I on monocyte and macrophage tumor necrosis turnover rate, and most data suggest IGFBP-2 to have pre- factor- production. Endocrinology. 137:4611– 4618. dominantly inhibitory effects on IGF actions (42). Thus, one 21. Isgaard J, Tivesten A. 1999 The role of growth hormone and insulin-like might hypothesize that the combination of low IGF-II and growth factor I in the regulation of apoptosis. Growth Hormone IGF Res. 9(Suppl A):125–128. high IGFBP-2 found in advanced HIV infection may con- 22. 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