Reduced Fragmentation of IGFBP-2 and IGFBP-3 as a Potential Mechanism for Decreased Ratio of IGF-II to IGFBPs in Cerebrospinal Fluid in Response to Repeated Intrathecal Administration of Triamcinolone Acetonide in Patients With Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic autoimmune disease of the brain and spinal cord causing a wide range of symptoms such as impaired walking capability, spasticity, fatigue, and pain. The insulin-like growth factor (IGF) system has regulatory functions for the induction of inflammatory pathways in experimental encephalomyelitis. We have therefore assessed expression and regulation of the IGF system on the level of IGFs and IGFBPs in serum and cerebrospinal fluid (CSF) in the course of four repeated triamcinolone acetonide (TCA) administrations in two female and four male MS patients. Sample series of 20 treatment cycles were analyzed. IGF-I and IGF-II were quantified by ELISAs, and IGFBPs were analyzed by quantitative Western ligand (qWLB) and Western immunoblotting (WIB) in order to differentiate intact and fragmented IGFBPs. The ratios of fragmented to intact IGFBP-2 and -3 were calculated in serum and CSF. Finally, the ratios of IGF-I and IGF-II to the total IGF-binding activity, quantified by qWLB, were determined as an indicator of IGF-related bioactivity. After the fourth TCA administration, the average level of IGF-I was increased in serum (p < 0.001). The increase of IGF-I concentrations in serum resulted in an increased ratio of IGF-I to IGFBPs in the circulation. By contrast in CSF, fragmentation of IGFBP-2 and IGFBP-3 and the ratio of IGF-II to intact IGFBPs were decreased at the fourth TCA administration (p < 0.01). Furthermore, reduced fragmentation of IGFBP-3 in CSF was accompanied by increased concentrations of intact IGFBP-3 (p < 0.001). We conclude that reduced fragmentation of IGFBPs and concomitant reduction of IGF-II to IGFBP ratios indicate regulation of bioactivity of IGF-II in CSF during repeated intrathecal TCA administration in MS patients.

Supplementation of Blackcurrant Anthocyanins Increased Cyclic Glycine-Proline in the Cerebrospinal Fluid of Parkinson Patients: Potential Treatment to Improve Insulin-Like Growth Factor-1 Function.

BACKGROUND: Insulin-like growth factor-1 (IGF-1) function is impaired in Parkinson disease. Cyclic glycine-proline (cGP), a metabolite of IGF-1, is neuroprotective through improving IGF-1 function. Parkinson disease patients score lower on Hospital-associated Anxiety and Depression Scale after supplementing blackcurrant anthocyanins (BCA), which may be associated with IGF-1 function. We evaluated the changes of cGP and IGF-1 before and after the supplementation. METHODS: Plasma and cerebrospinal fluid (CSF) were collected from 11 male patients before and after 28 day supplementation of BCA. The concentrations of IGF-1, IGF binding protein (IGFBP)-3, and cGP were measured using ELISA and HPLC-MS assays. The presence of cGP in the BCA was evaluated. RESULTS: cGP presented in the BCA. BCA supplementation increased the concentration of cGP (p < 0.01), but not IGF-1 and IGFBP-3 in the CSF. CSF concentration of cGP was correlated with plasma concentration of cGP (R = 0.68, p = 0.01) and cGP/IGF-1 molar ratio (R = 0.66, p = 0.01). The CSF/plasma ratio was high in cGP and low in IGF-1 and IGFBP-3. CONCLUSION: cGP is a natural nutrient to the BCA. The increased CSF cGP in Parkinson disease patients may result from the central uptake of plasma cGP. Given neurotrophic function, oral availability, and effective central uptake of cGP, the BCA has the potential to be developed to treat neurological conditions with IGF-1 deficiency.

IGF1R as a Key Target in High Risk, Metastatic Medulloblastoma.

Risk or presence of metastasis in medulloblastoma causes substantial treatment-related morbidity and overall mortality. Through the comparison of cytokines and growth factors in the cerebrospinal fluid (CSF) of metastatic medulloblastoma patients with factors also in conditioned media of metastatic MYC amplified medulloblastoma or leptomeningeal cells, we were led to explore the bioactivity of IGF1 in medulloblastoma by elevated CSF levels of IGF1, IGF-sequestering IGFBP3, IGFBP3-cleaving proteases (MMP and tPA), and protease modulators (TIMP1 and PAI-1). IGF1 led not only to receptor phosphorylation but also accelerated migration/adhesion in MYC amplified medulloblastoma cells in the context of appropriate matrix or meningothelial cells. Clinical correlation suggests a peri-/sub-meningothelial source of IGF-liberating proteases that could facilitate leptomeningeal metastasis. In parallel, studies of key factors responsible for cell autonomous growth in MYC amplified medulloblastoma prioritized IGF1R inhibitors. Together, our studies identify IGF1R as a high value target for clinical trials in high risk medulloblastoma.

Serum but not cerebrospinal fluid levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) are increased in Alzheimer's disease.

BACKGROUND: Although insulin-like growth factor-I (IGF-I) is of importance for the adult function of the central nervous system (CNS), little is known of the significance of IGF-I in cerebrospinal fluid (CSF) in relation to Alzheimer's disease (AD). METHODS: A cross-sectional study of 60 consecutive patients under primary evaluation of cognitive impairment and 20 healthy controls. The patients had AD dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n=32), stable MCI (SMCI, n=13), or other dementias (n=15). IGF-I, IGF-binding protein-3 (IGFBP-3), and insulin were measured in serum and CSF. RESULTS: Serum IGF-I level was increased in AD patients and in patients with other dementias compared to healthy controls (P=0.01 and P<0.05, respectively). Serum IGFBP-3 concentration was increased in AD and SMCI patients compared to controls (P=0.001 and P<0.05, respectively). CSF levels of IGF-I and IGFBP-3 as well as serum and CSF levels of insulin were similar in all study groups. In the total study population (n=80), serum levels of IGF-I and IGFBP-3 correlated negatively with CSF ß-amyloid1₋42 (Aß1₋42) level (r=-0.29, P=0.01 and r=-0.27, P=0.02, respectively) and in the AD patients (n=32), the increased CSF/serum IGF-I ratio correlated positively with the CSF level of phosphorylated tau protein (P-tau; r=0.42, P=0.02). CONCLUSION: Patients with AD as well as other dementias had high levels of IGF-I in serum but not in CSF. In AD patients, the IGF-I system was associated with biomarkers of AD disease status.

Early developmental changes in IGF-I, IGF-II, IGF binding protein-1, and IGF binding protein-3 concentration in the cerebrospinal fluid of children.

IGF-I and IGF-II are ubiquitously expressed growth factors that have profound effects on the growth and differentiation of many cell types and tissues, including cells of the CNS. In biologic fluids, most IGFs are bound to one of six IGF binding proteins (IGFBPs 1-6). Increasing evidence strongly supports a role for IGF-I in CNS development, as it promotes neuronal proliferation and survival. However, little is known about IGF-I and its homolog IGF-II and their carrier proteins, IGFBPs, during the neonatal period in which brain size increases dramatically, myelination takes place, and neurons show limited capacity to proliferate. Herein, we have determined the concentrations of IGF-I, IGF-II, IGFBP-1, and IGFBP-3 in cerebral spinal fluid (CSF) samples that were collected from children who were 1 wk to 18 y of age. The concentrations of IGF-I, IGFBP-1, and IGFBP-3 in CSF from children <6 mo of age were significantly higher than in older children, whereas IGF-II was higher in the older group. This is in contrast to what is observed in the peripheral circulation, where IGF-I and IGFBP-3 are low at birth and rise rapidly during the first year, reaching peak levels during puberty. Higher concentrations of IGF-I, IGFBP-1, and IGFBP-3 in the CSF of very young children suggest that these proteins might participate in the active processes of myelination and synapse formation in the developing nervous system. We propose that IGF-I and certain IGFBPs are likely necessary for normal CNS development during critical stages of neonatal brain growth and development.

CSF insulin-like growth factor-1 in infantile neuronal ceroid lipofuscinosis.

BACKGROUND: Infantile neuronal ceroid lipofuscinosis (INCL) is a progressive encephalopathy in which the patients are severely disabled by the age of 3 years. It is characterized by cerebral atrophy, selective loss of cortical neurons, and secondary loss of axons and myelin sheaths of the white matter. INCL has been shown to result from a palmitoyl protein thioesterase deficiency. The authors suggested that insulin-like growth hormones and apoptosis might play a role in the pathogenesis of INCL. METHODS: The authors measured insulin-like growth factor-1 (IGF-1) and IGF binding protein 3 (IGFBP-3) in the CSF of patients with INCL by radioimmunoassay at an early stage when myelin was starting to diminish. RESULTS: The authors found low CSF IGF-1 but normal IGFBP-3 in patients with INCL compared with control subjects. Also, they observed apoptotic cell death in biopsies of INCL patients. CONCLUSIONS: Because the IGF system seems to be important for early brain development, myelination, and neuroprotection, the authors suggest that the pathology in INCL may be associated with low CSF IGF-1.

Insulin-like growth factor-I in cerebrospinal fluid and serum in Rett syndrome.

Rett syndrome is a neurodevelopmental disease characterized by failure of somatic and brain growth. The insulin-like growth factor system mediates most actions of growth hormone. Evidence that it plays an important role in early development of the brain is increasing. The aim of the study reported was to assess the role of the insulin-like growth factor system in the pathogenesis of Rett syndrome. We measured insulin-like growth factor-I levels in serum (8 patients, mean age 9.1 years) and cerebrospinal fluid (13 patients, mean age 7 years) using a sensitive radioimmunoassay method and compared them with those in age-matched controls (13 and 26 patients, respectively). Neither serum nor cerebrospinal fluid insulin-like growth factor-I levels differed from those in controls. We also measured insulin-like growth factor binding protein-3 levels in serum (in 9 patients and 8 controls) and in cerebrospinal fluid (in 12 patients and 11 controls) and serum growth hormone levels (in 8 patients and 11 controls); the levels in patients did not differ from those in controls. We found no significant correlation between serum and cerebrospinal fluid insulin-like growth factor-I in Rett syndrome. This may indicate an independent role of insulin-like growth factor system in the central nervous system, making serum insulin-like growth factor-I measurement unreliable as an indicator of disturbed function in the central nervous system. Our results did not support the notion that a defective insulin-like growth factor-I system explains the lack of somatic and brain growth in Rett syndrome.

GH, IGF-I, IGFBP-3 and IGFBP-2 in cerebrospinal fluid of infants, during puberty and in adults.

During diagnostic lumbar punctions cerbrospinal fluid (CSF) was collected for the determination of GH, IGF-I, IGFBP-3 and IGFBP-2. The patients were 0.3 to 68 years od and suffered from viral infections, leukemias, M. Hodgkin or multiple sclerosis. Only CSF samples without any pathological alterations were analysed. In infants and adults CSF GH concentrations significantly declined with age, while IGF-I and the two binding proteins were unrelated to age. GH was not correlated to IGF-I, IGFBP-3 or IGFBP-2. However, IGF-I was strongly related to IGFBP-3 (r = 0.529; < 0.001) and IGFBP-2 (r = 0.796; < 0.001) as was IGFBP-3 to IGFBP-2 (r = 0.685; < 0.001), suggesting dependence of the three variables. With IGFBP-3 or IGFBP-2 as control variables (partial correlation) IGF-I was no longer related to the binding proteins, while the relation of IGFBP-3 to IGFBP-2 remained unchanged with IGF-I as the control variable (r = 0.687; < 0.001). The results suggest that the age-related decrease of CSF GH may contribute to the age-dependent decline of GH receptors in brain, which are up-regulated by GH. Furthermore, in CSF IGF-I concentrations were determined by the two binding proteins. It may be speculated that the transfer of IGF-I through the blood CSF barrier or its production in brain may be closely related to the IGF-binding proteins.