Endocrine Journal 2006, 53 (5), 639–645

Long-term Effects of Recombinant Human Insulin-like Growth Factor I Treatment on Glucose and Lipid Metabolism and the Growth of a Patient with Congenital Generalized Lipodystrophy

MARI SATOH, ATSUKO YOSHIZAWA, MASAROU TAKESUE, TSUTOMU SAJI AND SUSUMU YOKOYA*

First Department of Pediatrics, Toho University School of medicine, Tokyo 143-8541, Japan *Department of Pediatrics, Toranomon Hospital, Tokyo 105-8470, Japan

Abstract. Congenital generalized lipodystrophy (CGL) is a disease characterized by generalized lack of body fat, insulin resistance, hypertriglyceridemia, and fatty liver. We studied the long-term effects of recombinant human insulin-like growth factor I (rhIGF-I) treatment on glucose and lipid metabolism and the growth in a patient with CGL. During rhIGF- I treatment, the serum triglyceride level was maintained almost within the normal range, and the plasma glycosylated hemoglobin A1c (HbA1c) levels were maintained under 8.0% (5.8%–7.9%). Thus, rhIGF-I treatment was effective in lowering glucose and triglyceride levels over the long-term in a CGL patient. However, it was difficult to suppress the patient’s voracious appetite. Although serum total IGF-I levels were extremely high (1000–1700 ng/ml), growth was not accelerated after the start of rhIGF-I treatment, likely because of normal IGF binding protein 3 (IGFBP-3) levels. During rhIGF-I treatment, the patient developed a recurrence of mild hypertrophic cardiomyopathy and a mild elevation of intraocular pressure.

Key words: Lipodystrophy, IGF-I, mellitus, Hyperlipidemia, Growth (Endocrine Journal 53: 639–645, 2006)

INSULIN-like growth factor I (IGF-I) has insulin-like Patient History effects on glucose metabolism. Therefore, recombinant human IGF-I (rhIGF-I) treatment has been reported to The patient was a 15-year-old female who had been be effective in lowering plasma glucose concentration born to non-consanguineous parents after an unevent- in patients with insulin resistance syndrome, including ful 40 week gestational period. At birth, her height was leprechaunism, type A insulin resistance, and congen- 50 cm (+0.58 SD), and body weight was 3112 g (+0.03 ital generalized lipodystrophy (CGL) [1]. However, SD). Her father’s height was 177 cm (+1.18 SD), her there are few reports dealing with the long-term effects mother’s height was 153 cm (–0.98 SD), and the pa- of rhIGF-I treatment on glucose and lipid metabolism tient’s target height was 158.5 cm (+0.12 SD). She and the growth of patients with CGL. In this study, we was referred to our hospital because of failure to thrive investigated the effects of 9 years of treatment with and hirsutism at the age of 4 months. At that time, her rhIGF-I in a female patient with CGL. height was 66.3 cm (+1.68 SD), her body weight was 5716 g (–1.11 SD), and the kaup score was 13.0 (nor- mal range, 15.0–18.0). She had the characteristic phe- notypic findings of CGL, including a generalized lack Received: January 20, 2006 Accepted: June 13, 2006 of body fat, muscle hypertrophy, hirsutism, and clitoro- Correspondence to: Mari SATOH, M.D., First Department of megaly (Fig. 1). Hypertriglyceridemia and a low se- Pediatrics, Toho University School of Medicine, 6-11-1 Oomori- rum high-density lipoprotein (HDL) cholesterol level nishi, Oota-ku, Tokyo 143-8541, Japan were noted (Table 1), and fatty liver was detected by 640 SATOH et al.

Fig. 1. Phenotypic characteristics at 4 months of age (a, b) and 6 years of age (c). The patient shows characteristic phenotypes, including generalized lack of the body fat, muscle hypertrophy, and hirsutism.

Table 1. Laboratory findings before the start of rhIGF-I treatment

4 months 6years Age 6 months 1 year 4 years (diagnosis) (start of rhIGF-I) Total-cholesterol (mg/dl) 243 247 158 164 166 HDL-cholesterol (mg/dl) 20 18 27 ND 37 Triglyceride (mg/dl) 1445 779 237 187 48 Free fatty acid (mEq/l) 0.89 1.05 0.79 ND 0.29 HOMA-R 1.54 9.26 9.48 9.82 1.76 Insulinogenic Index 0.55 3.03 0.64 ND 0.29 HbA1c (%) ND 4.1 4.2 5.1 6.1 Urinary C-peptide (µg/day) ND ND ND 133 25 Minimum glucose level (mg/dl) in insulin tolerance test O.1 U/kg, insulin ND 80 72 65 43 0.5 U/kg, insulin 25 48 52 32 18 IGF-I (ng/ml) ND ND ND 230 320 HDL, high-density lipoprotein; HOMA-R, homeostasis model assessment; HbA1c, glycosylated hemoglobin A1c; ND, not detected; IGF-I, insulin-like growth factor I Blood samples were obtained after an overnight fast. abdominal ultrasonography. Therefore, the patient was at the age of 1 year, glucose intolerance was recog- diagnosed as having CGL. Since failure to thrive was nized, and the patient was diagnosed as having diabetes thought to be due to acute cardiac failure caused by hyper- mellitus at the age of 4 years. Therefore, her calorie in- trophic cardiomyopathy, a diuretic (furosemide) and a take was restricted to 80% of the calorie intake appro- β-blocker (propranolol hydrochloride) were started. priate for her chronological age. Since the patient’s The patient’s hypertriglyceridemia and fatty liver cardiac function and hypertrophic cardiomyopathy had improved gradually with only a low fat diet. However, gradually improved, furosemide and propranolol hy- IGF-I THERAPY IN A PATIENT WITH LIPODYSTROPHY 641

Table 2. Oral glucose tolerance test (1.75 g/kg)

Time (min) Age 0 306090120 4 months Glucose (mg/dl) 78 103 88 106 108 IRI (µU/ml) 8.0 21.8 12.7 23.9 27.0 6 months Glucose (mg/dl) 85 130 136 131 120 IRI (µU/ml) 44.1 180.5 225.7 185.4 137.4 1 year Glucose (mg/dl) 79 105 135 151 145 IRI (µU/ml) 48.6 65.3 106.0 151.1 171.5 4 years Glucose (mg/dl) 114 219 204 203 174 IRI (µU/ml) 34.9 ND 151.3 ND 197.2 6 years Glucose (mg/dl) 115 235 265 204 156 IRI (µU/ml) 6.2 41.1 35.9 21.1 10.2 ND, not detected

10 years, the patient had a recurrence of hypertrophic cardiomyopathy, and an angiotensin converting en- zyme inhibitor (enalapril maleate) was started. The patient’s plasma HbA1c levels increased at the age of 13 years, because the patient could not maintain her low-calorie diet since she was about 11 years old (Table 3). The dosage of rhIGF-I was increased grad- ually and the maximum dose was 0.24 mg/kg/day. She developed localized fatty change of the liver and an elevated intraocular pressure, but tonsillar hypertrophy, renal hypertrophy, retinopathy, and polycystic ovaries were not present (Table 4). Fig. 2. Effect of rhIGF-I administration on plasma glycosylated From birth, she showed accelerated growth (Fig. 3). HbA1c and serum IGF-I. Although GH secretion was normal or slightly de- creased (Table 5), serum total IGF-I levels were high (Table 1) before the start of rhIGF-I. Serum total drochloride were stopped at the age of 4 years. At the IGF-I levels were extremely high after the start of age of 6 years, a subcutaneous injection of rhIGF-I rhIGF-I treatment (Table 3). However, the patient’s once a day before the breakfast at a dose of 0.15 mg/kg growth rate did not change after the start of rhIGF-I was started, since the plasma glycosylated hemoglobin treatment. The patient’s bone age was estimated using A1c (HbA1c) level had increased to 6.1%. The results the Tanner-Whitehouse 2 RUS method standardized of oral glucose tolerance tests are shown in Table 2. for Japanese children; accelerated bone maturation was The reason why we did not try the high dose insulin seen both before and after the start of rhIGF-I treat- treatment was that hyperinsulinemia was supposed to ment. budding started at the age of 7 years and worsen hyperlipidemia and hirsutism. 6 months (mean age for Japanese girls, 10 years), and Due to re-evaluation of its effect on glucose metabo- she reached her adult height of 156.0 cm (–0.38 SD) lism, rhIGF-I treatment was discontinued 1 year later. at the age of 13 years and 6 months. Although her Plasma HbA1c increased from 6.0% to 7.9% 4 months menarche was at the age of 13 years (mean age for after the cessation of rhIGF-I treatment; as rhIGF-I Japanese girl, 12 years and 4 months), she had oligo- treatment appeared to be effective in lowering her plas- menorrhea. Although she had good social skills, she ma glucose concentration and decreasing the plasma was a poor student. As a junior high school student, HbA1c level, it was resumed (Fig. 2). At the age of her intellectual abilities were at the primary school level. 642 SATOH et al.

Table 3. Laboratory findings during rhIGF-I treatment

Age (Years) 7 9 11 13 15 After the treatment (years) 1 3 5 7 9 Total-cholesterol (mg/dl) 195 138 170 146 180 HDL-cholesterol (mg/dl) 39 32 46 44 46 Triglyceride (mg/dl) 183 192 123 67 83 Free fatty acid (mg/dl) 0.09 0.20 0.31 0.09 0.09 Fasting glucose (mg/dl) 148 131 131 157 166 HbA1c (%) 6.0 5.7 5.7 6.9 7.9 Total IGF-I (ng/ml) 1400 1200 1500 1300 1300 IGFBP-3 (µg/ml) ND ND ND 4.39 3.63 HDL, high-density lipoprotein; HbA1c, glycosylated hemoglobin A1c; ND, not detected; IGF-I, insulin-like growth factor I; IGFBP-3, IGF binding protein 3 Blood samples were obtained after 2 or 3 hours after lunch.

Table 4. Complications of the patient

0.33 14 6 10 15 Age (years) (diagnosis) (start of rhIGF-I) Hypertrophic cardiomyopathy +++ ++ ± – + + Fatty liver ++ + – – – – Localized fatty change of the liver – – – – + + Renal hypertrophy ND ND ND – – – Tonsillar hypertrophy ND ND ND – – – Polycystic ovary ND ND ND – – – Retinopathy – ND ND – – – Intraocular pressure (mmHg, right/left) ND ND ND ND 24/25 18/20 ND, not detected; –, absent; ±, suspected; +, present (mild); ++, present (moderate); +++, present (severe)

Discussion Glucose and lipid metabolism

CGL is a disease characterized by generalized lack The abnormalities of glucose and lipid metabolism of body fat, insulin resistance, hypertriglyceridemia, that are found in CGL patients are thought to be due to and fatty liver [2, 3]. Recently, two causative for a leptin deficiency accompanied by a generalized lack CGL were reported; the Berardinelli-Seip congenital lipo- of body fat [9, 10]. Leptin activates the oxidation of dystrophy 2 (BSCL2) [4] and the 1-acylglycerol- fatty acid by binding to leptin receptors on the surface 3-phosphate O-acyltransferase 2 (AGPAT2) gene [5]. of skeletal muscle cells [11]. Insulin resistance occurs It has been reported that patients with BSCL2 gene due to an increase of fatty acid and triglyceride levels mutations show more severe clinical findings than pa- in skeletal muscle cells, since increased fatty acid and tients with AGPAT2 gene mutations [6, 7]. Only three triglyceride levels suppress substrate-1 patients all of whom had the same homozygous R275X (IRS-1) activity by accelerating serine phosphorylation mutations in the BSCL2 genes have been reported in and decelerating tyrosine phosphorylation of IRS-1 Japan [8]. Our patient was thought to have the [12]. Therefore, in the leptin deficiency state, increased BSCL2 mutation, because she developed diabetes mel- fatty acid and triglyceride levels are thought to cause litus in infancy, had hypertrophic cardiomyopathy, and insulin resistance. showed mental retardation. Hyperinsulinemia secondary to insulin resistance accelerates the synthesis of fatty acid by increasing the expression of the sterol of the regulatory element- binding protein 1c (SREBP1-c) in the liver [13]. There- IGF-I THERAPY IN A PATIENT WITH LIPODYSTROPHY 643

patients with CGL show a leptin deficiency, it is diffi- cult to suppress their voracious appetite. Recently, it has been reported that leptin replacement therapy was effective in normalizing glucose and lipid metabolism and suppressing the voracious appetite seen in patients with CGL [14].

Growth

Leprechaunism [15], which is caused by mutations in both alleles of the insulin receptor gene, is associated with severe insulin resistance and growth retardation. It is reported that insulin enhances hepatic GH respon- siveness by positively regulating GH receptors in the liver, as well as increasing the production of IGF-I and IGF binding protein 3 (IGFBP-3). Therefore, lep- rechaunism, in which insulin activity is completely lacking, shows GH resistance and impaired production of IGF-I and IGFBP-3, which leads to growth retarda- tion [16]. Although patients with CGL show accelerated growth, the cause of the growth acceleration is unclear [17]. Our patient showed growth acceleration from Fig. 3. Growth chart of the patient. Arrows indicate the bone birth. Her GH secretion was normal or slightly de- age of the patient. creased, but her serum IGF-I levels were high before the start of rhIGF-I treatment. In patients with CGL, an insulin resistant state (glucose intolerance and dia- fore, hyperinsulinemia causes hyperlipidemia and fatty betes mellitus) coexists with a hyperinsulinemic state liver. Since SREBP1-c also accelerates the synthesis (hypertriglyceridemia and fatty liver). Therefore, in of glucose by suppressing the production of IRS-2, the contrast to leprechaunism, hyperinsulinemia in patients hyperinsulinemia itself tends to aggravate the insulin with CGL may enhance GH sensitivity in the liver and resistance [13]. increase IGF-I production, which leads to growth ac- Our patient’s hyperlipidemia and fatty liver im- celeration. proved on a low-fat diet, and her insulin resistance im- Although our patient’s serum total IGF-I levels proved gradually. However, her glucose intolerance during rhIGF-I treatment were extremely high (1000– worsened and she finally developed diabetes mellitus. 1700 ng/ml), her growth rate did not change after the This was thought to be caused by a decrease in insulin start of rhIGF-I treatment. Since serum IGFBP-3 lev- secretion, as urinary C-peptide excretion decreased els were high but within the normal range, normal gradually. The decrease of insulin secretion could have levels of serum IGFBP-3 may accelerate the urinary been due to secondary exhaustion of pancreatic β-cells. excretion of excessive free IGF-I. Therefore, growth During rhIGF-I treatment, serum triglyceride levels after the start of rhIGF-I treatment may not be acceler- were maintained almost within the normal range, and ated. The low levels of IGFBP-3 observed in patients plasma HbA1c levels were under 8.0% (5.8%–7.9%). with leprechaunism and GH insensitivity syndrome In fact, in patients with CGL, long-term rhIGF-I treat- (Laron syndrome) are supposed to be the cause of the ment is supposed to be effective for maintaining lower lower growth rate that occurs during rhIGF-I treatment, glucose and triglyceride concentrations. However, the contrary to what would be expected [16, 18]. It has dose of rhIGF-I had to be increased gradually to been reported that patients with leprechaunism require maintain HbA1c levels in the normal range, because a high dose of rhIGF-I (1.6 mg/kg/day) to maintain the the patient could not adhere to a low-calorie diet. Since growth rate within the normal range [16]. Also, it is 644 SATOH et al.

Table 5. Growth levels in provocation test

1. Insulin provocation test at 4 years of age (0.5 U/kg, insulin) Time (min) 0 30 60 90 120 Glucose (mg/dl) 86 32 43 68 76 (ng/ml) 2.56 1.57 2.51 1.89 1.02

2. Insulin provocation test at 6 years of age (0.1 U/kg, insulin) Time (min) 0 30 60 90 120 Glucose (mg/dl) 91 60 82 87 85 Growth hormone (ng/ml) 2.69 1.84 4.36 9.26 10.27

3. Insulin provocation test at 6 years of age (0.5 U/kg, insulin) Time (min) 0 30 60 90 120 Glucose (mg/dl) 72 18 37 37 48 Growth hormone (ng/ml) 5.68 3.48 1.14 4.10 5.86

4. Growth hormone releasing factor (GRF) provocation test at 6 years of age (1 µg/kg, GRF) Time (min) 0 15 30 60 90 120 Growth hormone (ng/ml) 3.46 17.59 11.20 9.43 6.91 6.08 supposed that circulating IGF-I mainly produced in the During rhIGF-I treatment, hypertrophic cardiomyopathy liver is not essential for the growth, but that IGF-I pro- recurred, and her intraocular pressure became elevated; duced locally by GH stimulation is more important for these manifestations may be complications of long- the growth. Therefore, our patient may not have shown term rhIGF-I treatment. the accelerated growth during rhIGF-I treatment de- In conclusion, long-term rhIGF-I treatment is sup- spite high serum total IGF-I concentrations. posed to be effective in lowering glucose and triglycer- ide concentrations in patients with CGL if the patients Adverse events maintain a low-calorie diet. We found that the growth was not accelerated after the start of rhIGF-I treatment. Although it has been reported that the administration Our patient developed recurrence of mild hypertrophic of rhIGF-I causes tonsillar hypertrophy, renal hyper- cardiomyopathy and a mild elevation of intraocular trophy, retinopathy, and polycystic ovaries [16, 18], pressure during rhIGF-I treatment. these complications were not present in our patient.

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