Serum levels of insulin-like growth factor-1 and insulin-like growth factor binding protein-3 in relapsing and primary progressive multiple sclerosis

Insulin-like growth factor-1 (IGF-1) levels in multiple sclerosis patients: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Multiple sclerosis (MS) is a chronic progressive autoimmune disorder of the central nervous system (CNS) that can cause inflammation, demyelination, and axon degeneration. Insulin-like growth factor-1 (IGF-1) is a single-chain polypeptide mainly synthesized in the liver and brain. IGF-1 causes neuronal and non-neuronal cell proliferation, survival, and differentiation. Therefore, it can be used in treating neuro-demyelinating diseases such as MS. The current systematic review and meta-analysis aims to compare the levels of IGF-1 in MS patients and healthy controls and also investigates IGF binding proteins (IGF-BP) and growth hormone (GH) levels between MS patients and healthy controls.

METHODS

In this study, we systematically searched electronic databases of PubMed, Scopus, Web of Science (WOS), and Google Scholar, up to December 2022. Studies that measured IGF-1, GH, IGFBP-1, IGFBP-2, or IGFBP-3 in MS patients and healthy controls in either blood or cerebral spinal fluid (CSF) were identified. We calculated Standardized mean differences (SMD) to compare levels of IGF-1, GH, IGFBP-1, IGFBP-2, or IGFBP-3 in MS patients and controls.

RESULTS

Finally, we included 11 eligible studies from 1998 to 2018. The sample size of included studies varied from 20 to 200 resulting in a total sample size of 1067 individuals, 531 MS patients, and 536 healthy controls. The mean age of the patient and control groups were 38.96 and 39.38, respectively. The average EDSS among patients was 4.56. We found that blood levels of IGF-1 (SMD = 0.20, 95% CI = -0.20 to 0.59, I2 = 82.4%, K = 8, n = 692), CSF level of IGF-1 (SMD = 0.25, 95% CI = -0.06 to 0.56, I2 = 0.0%, K = 3 n = 164) and blood levels of GH were not significantly higher in MS patients than controls (SMD = 0.08, 95% CI = -0.33 to 0.49, I2 = 77.0% K = 3, n = 421). Moreover, the blood levels of IGFBP-1 (SMD = 0.70, 95% CI = 0.01 to 1.40, I2 = 77%, K = 4, n = 255) were significantly higher in MS cases than in controls. However, the blood levels of IGFBP-2 (SMD = 0.43, 95% CI = -0.34 to 1.21, I2 = 64.2%, K = 3, n = 78) and blood levels of IGFBP-3 (SMD = 1.04, 95% CI = -0.09 to 2.17, I2 = 95.6%, K = 6, n = 443) were not significantly higher in patients than controls.

CONCLUSION

Our meta-analysis revealed no significant difference in serum levels of IGF-1, GH, IGFBP-2, and IGFBP-3 between the MS group and healthy controls, except for IGFBP1. However, our systematic review showed that the studies were controversial for IGFBP-3 serum levels. Some studies found an increase in serum level of IGFBP-3 in MS patients compared to the healthy group, while others showed a decrease.

The neurobiology of insulin-like growth factor I: From neuroprotection to modulation of brain states

After decades of research in the neurobiology of IGF-I, its role as a prototypical neurotrophic factor is undisputed. However, many of its actions in the adult brain indicate that this growth factor is not only involved in brain development or in the response to injury. Following a three-layer assessment of its role in the central nervous system, we consider that at the cellular level, IGF-I is indeed a bona fide neurotrophic factor, modulating along ontogeny the generation and function of all the major types of brain cells, contributing to sculpt brain architecture and adaptive responses to damage. At the circuit level, IGF-I modulates neuronal excitability and synaptic plasticity at multiple sites, whereas at the system level, IGF-I intervenes in energy allocation, proteostasis, circadian cycles, mood, and cognition. Local and peripheral sources of brain IGF-I input contribute to a spatially restricted, compartmentalized, and timed modulation of brain activity. To better define these variety of actions, we consider IGF-I a modulator of brain states. This definition aims to reconcile all aspects of IGF-I neurobiology, and may provide a new conceptual framework in the design of future research on the actions of this multitasking neuromodulator in the brain.

A Narrative Review on Axonal Neuroprotection in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) resulting in demyelination and neurodegeneration. The therapeutic strategy is now largely based on reducing inflammation with immunosuppressive drugs. Unfortunately, when disease progression is observed, no drug offers neuroprotection apart from its anti-inflammatory effect. In this review, we explore current knowledge on the assessment of neurodegeneration in MS and look at putative targets that might prove useful in protecting the axon from degeneration. Among them, Bruton's tyrosine kinase inhibitors, anti-apoptotic and antioxidant agents, sex hormones, statins, channel blockers, growth factors, and molecules preventing glutamate excitotoxicity have already been studied. Some of them have reached phase III clinical trials and carry a great message of hope for our patients with MS.

The effect of combined functional training on BDNF, IGF-1, and their association with health-related fitness in the multiple sclerosis women

OBJECTIVE

Exercise-induced changes in the neurotrophic factors and the physical function are essential for the rehabilitation of the multiple sclerosis (MS) persons. The aim of this study was investigating of effectiveness of the combined functional training (CFT) on brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and their association with health-related fitness in the MS women.

DESIGN

Twenty women with relapsing-remitting MS randomly assigned to CFT and control (CON) groups. The CFT consisted of 8 weeks (3 days per week) rhythmic aerobic exercise, TRX suspension training, elastic band training, and bodyweight training. BDNF, IGF-1, and health-related fitness components were assessed before and after the intervention.

RESULTS

There was no significant difference in BDNF level between the CFT and the CON group. In contrast, IGF-1, walking speed, and strength of the right- and left-hand was significantly increased in the CFT compared with the CON group. Furthermore, there was a significant and positive correlation between IGF-1 and some fitness components.

CONCLUSIONS

The findings indicated that CFT might a useful training mode in the rehabilitation of the MS women. CFT improved IGF-1 level that is a neuroprotective agent in MS. Positive and significant association between IGF-1 and some health-related fitness components indicates of the importance of IGF-1 in the rehabilitation of the MS persons than BDNF.

The Role of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Nervous System

The insulin-like growth factors (IGF-I and IGF-II) and their receptors are widely expressed in nervous tissue from early embryonic life. They also cross the blood brain barriers by active transport, and their regulation as endocrine factors therefore differs from other tissues. In brain, IGFs have paracrine and autocrine actions that are modulated by IGF-binding proteins and interact with other growth factor signalling pathways. The IGF system has roles in nervous system development and maintenance. There is substantial evidence for a specific role for this system in some neurodegenerative diseases, and neuroprotective actions make this system an attractive target for new therapeutic approaches. In developing new therapies, interaction with IGF-binding proteins and other growth factor signalling pathways should be considered. This evidence is reviewed, gaps in knowledge are highlighted, and recommendations are made for future research.

Insulin-Like Growth Factor Binding Proteins in Autoimmune Diseases

Insulin-like growth factor binding proteins (IGFBPs) are a family of proteins binding to Insulin-like growth factors (IGFs), generally including IGFBP1, IGFBP2, IGFBP3, IGFBP4, IGFBP5, and IGFBP6. The biological functions of IGFBPs can be classified as IGFs-dependent actions and IGFs-independent effects. In this review, we will discuss the structure and function of various IGFBPs, particularly IGFBPs as potential emerging biomarkers and therapeutic targets in various autoimmune diseases, and the possible mechanisms by which IGFBPs act on the pathogenesis of autoimmune diseases.

The role of growth factors as a therapeutic approach to demyelinating disease

A variety of growth factors are being explored as therapeutic agents relevant to the axonal and oligodendroglial deficits that occur as a result of demyelinating lesions such as are evident in Multiple Sclerosis (MS). This review focuses on five such proteins that are present in the lesion site and impact oligodendrocyte regeneration. It then presents approaches that are being exploited to manipulate the lesion environment affiliated with multiple neurodegenerative diseases and suggests that the utility of these approaches can extend to demyelination. Challenges are to further understand the roles of specific growth factors on a cellular and tissue level. Emerging technologies can then be employed to optimize the use of growth factors to ameliorate the deficits associated with demyelinating degenerative diseases.

Role of metabolism in neurodegenerative disorders

Along with the increase in life expectancy over the last century, the prevalence of age-related disorders, such as neurodegenerative diseases continues to rise. This is the case of Alzheimer's, Parkinson's, Huntington's diseases and Multiple sclerosis, which are chronic disorders characterized by neuronal loss in motor, sensory or cognitive systems. Accumulating evidence has suggested the presence of a strong correlation between metabolic changes and neurodegeneration. Indeed epidemiologic studies have shown strong associations between obesity, metabolic dysfunction, and neurodegeneration, while animal models have provided insights into the complex relationships between these conditions. In this context, hormones such as leptin, ghrelin, insulin and IGF-1 seem to play a key role in the regulation of neuronal damage, toxic insults and several other neurodegenerative processes. This review aims to presenting the most recent evidence supporting the crosstalk linking energy metabolism and neurodegeneration, and will focus on metabolic manipulation as a possible therapeutic tool in the prevention and treatment of neurodegenerative diseases.

Growth hormone and disease severity in early stage of multiple sclerosis

Evidence suggests that neurohormones such as GH and IGF-I are involved in the neuroreparative processes in multiple sclerosis (MS). GH and IGF-I blood levels in naïve MS patients with different disease courses were investigated in this study. Serum GH and IGF-I in untreated MS patients (n = 64), healthy controls (HC, n = 62), and patients affected by other neurological diseases (OND, n = 46) were evaluated with a solid-phase-enzyme-labeled-chemiluminescent-immunometric assay. No differences were detected in GH across MS, OND, and HC (MS = 0.87 ± 1.32 ng/mL; OND = 1.66 ± 3.7; and HC = 1.69 ± 3.35; P = 0.858) when considering gender, disease duration, and disease course. However, GH was lower (P = 0.007) in patients with more severe disease (expanded disability scale score, EDSS ≥ 4.0) compared with milder forms (EDSS < 4). IGF-I l did not differ across the 3 groups (P = 0.160), as far as concern disease course, disability, and gender were. Lower IGF-I levels were detected in subjects older than 50 years compared to younger ones for all 3 groups. Lower GH was detected in patients with more severe MS, and age was confirmed as the main factor driving IGF-I levels in all subjects. These findings, relying on the natural course of the disease, could help in shedding lights on the mechanisms involved in autoreparative failure associated with poorer prognosis in MS.

Insulin-like growth factor (IGF)-I and IGF-binding protein-3 serum levels in relapsing-remitting and secondary progressive multiple sclerosis patients

BACKGROUND

Insulin-like growth factor (IGF)-I has a role in remyelination, and insulin-like growth factor-binding protein-3 (IGFBP-3) might reduce its bioavailability. A role of IGFBP-3 in multiple sclerosis (MS) progression was hypothesized in patients with primary progressive (PP) MS.

OBJECTIVE

To evaluate serum levels of IGF-I and IGFBP-3 in patients with relapsing-remitting (RR) and secondary progressive (SP) MS and their correlations with disease activity and progression.

METHODS

Sixty-three (41 RR and 22 SP) 'naive' MS patients and 60 age-matched healthy controls were enrolled. Patients were assessed through clinical [Expanded Disability Status Scale (EDSS), Multiple Sclerosis Severity Scale (MSSS), number of relapses] and laboratory investigations. IGF-I and IGFBP-3 were measured by ELISA.

RESULTS

Levels of IGF-I and IGFBP-3 were similar in the two MS groups. IGFBP-3 levels were higher in patients with MS than in controls (P < 0.001), with a reduction in IGF-I/BP3 ratio (P < 0.001). Patients showing IGFBP-3 levels higher than 2SD of the normal population had a higher EDSS (mean EDSS 3.7 vs. 2.8, P = 0.021). MSSS was not related to IGF-I or IGFBP-3 serum levels.

CONCLUSIONS

Our patients showed high IGFBP-3 serum levels respect to controls and higher serum levels were associated with a higher EDSS, despite of comparable disease duration. Therefore, MS and higher disability seem to be associated with a reduction in bioavailability of IGF-I. MSSS score was not related to IGFBP-3 levels, suggesting that IGFBP-3 might not have the pathogenetic role previously suggested for PP MS, in the mechanism of progression in the SP form of disease.

Recent clinical trials and future therapies

Immunotherapy for multiple sclerosis (MS) has developed extremely successfully during the past decade and a number of new strategies were developed for the treatment of the disease. Examples include therapeutic strategies targeting leukocyte differentiation molecules, costimulatory molecules, anti-adhesion molecules, chemotaxis, novel immunomodulators, autologous stem cell transplantation, anti-infectious therapies and strategies for neuroprotection, neurorepair and remyelination. Here we describe examples of monoclonal antibodies, a novel immunosuppressant and interesting neuroprotective strategies.

Circulating insulin-like growth factors and related binding proteins are selectively altered in amyotrophic lateral sclerosis and multiple sclerosis

OBJECTIVE

To provide a detailed profile of the peripheral IGF system in the neurological conditions; amyotrophic lateral sclerosis (ALS), post polio syndrome (PPS) and multiple sclerosis (MS). To determine whether subsets of patients within the disease groups could be identified in whom one or more components of the IGF regulatory system are altered compared to healthy control subjects matched for age, sex and BMI.

DESIGN

Three cohorts of patients were recruited, 28 with ALS, 18 with PPS and 23 with MS. Patients were individually matched to a healthy control based on sex, age (+/-3 yr), and BMI (+/-2.5 kg m(-2)). The concentration (ng/ml) of serum IGF-I, IGF-II, IGFBP-1, IGFBP-2 and IGFBP-3 and acid-labile subunit (microg/ml) was determined by IRMA.

RESULTS

In ALS patients, there was an increase of 11% in [IGF(TOTAL)] (p=0.042) ([IGF(TOTAL)]=[IGF-I]+[IGF-II]) and [IGFBP-1] was decreased by 34% (p=0.050) compared to matched controls. In "surviving" ALS patients, defined as those ALS patients with long disease duration (+2 SD from the mean survival time for Irish patients post diagnosis), there was an increase in [IGF-I] 36% (p=0.032) and a large decrease in [IGFBP-1] -58% (p=0.020) compared to controls. These differences were not evident in pre-agonal ALS patients. The concentration of serum IGF-I was 38% (p=0.018), acid-labile subunit 17% (p=0.044) and IGFBP-2 43% (p=0.035) higher in MS patients compared to controls. When stratified for interferon-beta (IFN-beta) use, we observed an increase in serum [IGF-I] 52% (p=0.013) and [IGF(TOTAL)] 19% (p=0.043) in MS patients undergoing IFN-beta treatment, but MS patients not undergoing IFN-beta treatment had similar IGF and IGFBP concentration to controls. Serum [IGFBP-3] 18% (p=0.033), [IGFBP-2] 86% (p=0.015) and (acid-labile subunit) 33% (p=0.012) was also higher in IFN-beta patients compared to controls. Stratified by stage of disease the most significant increase in components of the peripheral IGF system was attributed to relapsing-remitting MS patients treated with IFN-beta. All components of the peripheral IGF system in PPS patients were similar to controls.

CONCLUSIONS

The increase in circulating IGF-I and a reduction in regulatory binding protein IGFBP-1 in ALS patients with a "stable" disease profile suggest a potential change in peripheral IGF bioavailability in these subjects. In MS, we report a change in a number of components of the peripheral IGF system, the observed increase in IGF-I in patients treated with IFN-beta being of most significance as a potential therapeutic biomarker.

Primary-progressive multiple sclerosis

About 10-15% of patients with multiple sclerosis (MS) present with gradually increasing neurological disability, a disorder known as primary-progressive multiple sclerosis (PPMS). Compared with relapse-onset multiple sclerosis, people with PPMS are older at onset and a higher proportion are men. Inflammatory white-matter lesions are less evident but diffuse axonal loss and microglial activation are seen in healthy-looking white matter, in addition to cortical demyelination, and quantitative MRI shows atrophy and intrinsic abnormalities in the grey matter and the white matter. Spinal cord atrophy corresponds to the usual clinical presentation of progressive spastic paraplegia. Although neuroaxonal degeneration seems to underlie PPMS, the pathogenesis and the extent to which immune-mediated mechanisms operate is unclear. MRI of the brain and spinal cord, and examination of the CSF, are important investigations for diagnosis; conventional immunomodulatory therapies, such as interferon beta and glatiramer acetate, are ineffective. Future research should focus on the clarification of the mechanisms of axonal loss, improvements to the design of clinical trials, and the development of effective neuroprotective treatments.

Phosphorylated FTY720 promotes astrocyte migration through sphingosine-1-phosphate receptors

Sphingosine-1-phosphate (S1P) receptors are widely expressed in the central nervous system where they are thought to regulate glia cell function. The phosphorylated version of fingolimod/FTY720 (FTY720P) is active on a broad spectrum of S1P receptors and the parent compound is currently in phase III clinical trials for the treatment of multiple sclerosis. Here, we aimed to identify which cell type(s) and S1P receptor(s) of the central nervous system are targeted by FTY720P. Using calcium imaging in mixed cultures from embryonic rat cortex we show that astrocytes are the major cell type responsive to FTY720P in this assay. In enriched astrocyte cultures, we detect expression of S1P1 and S1P3 receptors and demonstrate that FTY720P activates Gi protein-mediated signaling cascades. We also show that FTY720P as well as the S1P1-selective agonist SEW2871 stimulate astrocyte migration. The data indicate that FTY720P exerts its effects on astrocytes predominantly via the activation of S1P1 receptors, whereas S1P signals through both S1P1 and S1P3 receptors. We suggest that this distinct pharmacological profile of FTY720P, compared with S1P, could play a role in the therapeutic effects of FTY720 in multiple sclerosis.

[Update on pathophysiologic and immunotherapeutic approaches for the treatment of multiple sclerosis]

Multiple sclerosis (MS) is a chronic disabling disease with significant implications for patients and society. The individual disease course is difficult to predict due to the heterogeneity of clinical presentation and of radiologic and pathologic findings. Although its etiology still remains unknown, the last decade has brought considerable understanding of the underlying pathophysiology of MS. In addition to its acceptance as a prototypic inflammatory autoimmune disorder, recent data reveal the importance of primary and secondary neurodegenerative mechanisms such as oligodendrocyte death, axonal loss, and ion channel dysfunction. The deepened understanding of its immunopathogenesis and the limited effectiveness of currently approved disease-modifying therapies have led to a tremendous number of trials investigating potential new drugs. Emerging treatments take into account the different immunopathological mechanisms and strategies, to protect against axonal damage and promote remyelination. This review provides a compilation of novel immunotherapeutic strategies and recently uncovered aspects of known immunotherapeutic agents. The pathogenetic rationale of these novel drugs for the treatment of MS and accompanying preclinical and clinical data are highlighted.

The insulin-like growth factor system in multiple sclerosis

Multiple sclerosis (MS) is a chronic disorder of the central nervous system characterized by inflammation, demyelination, and axonal degeneration. Present therapeutic strategies for MS reduce inflammation and its destructive consequences, but are not effective in the progressive phase of the disease. There is a need for neuroprotective and restorative therapies in MS. Insulin-like growth factor-1 (IGF-1) is of considerable interest because it is not only a potent neuroprotective trophic factor but also a survival factor for cells of the oligodendrocyte lineage and possesses a potent myelinogenic capacity. However, the IGF system is complex and includes not only IGF-1 and IGF-2 and their receptors but also modulating IGF-binding proteins (IGFBPs), of which six have been identified. This chapter provides an overview of the role of the IGF system in the pathophysiology of MS, relevant findings in preclinical models, and discusses the possible use of IGF-1 as a therapeutic agent for MS.

Capsaicin-induced inactivation of sensory neurons promotes a more aggressive gene expression phenotype in breast cancer cells

Capsaicin-induced inactivation of sensory neurons has been reported to enhance metastasis of a murine breast cancer cell line, specifically enhancing myocardial metastases. Here we characterized changes in gene expression patterns in primary tumors which developed in capsaicin-treated vs. control mice. We identified a small cohort of genes (17) which all showed significant decreases in expression levels. All of the identified genes have been linked to cell growth, differentiation, and/or cancer progression. Three representative genes, Caspase-7 (an executor of apoptosis), ADAM-10 (A Disintegrin and Metalloprotease), and Elk-3 (a transcriptional repressor of the ternary factor subfamily of the Ets factors) were further investigated. All three showed dramatic downregulation at the protein level in primary tumors from capsaicin-treated animals compared with control (vehicle-treated) animals, and their expression was also lost in cell culture. Elk-3 and Caspase-7 were not expressed in vitro in cultured cell lines, suggesting that their expression was induced by the tumor microenvironment. Loss of Caspase-7 expression can be expected to result in loss of function of apoptotic pathways. At first glance, loss of ADAM-10 expression would be expected to result in decreased invasive capability, due to loss of matrix metalloprotease activity. However, just the opposite appears to be true. We found that ADAM-10 actually hydrolyzes Substance P. Specifically ADAM-10 produces the same growth-inhibitory products from Substance P (i.e., SP (1-7)) that Neprilysin does, so that loss of ADAM-10 expression actually results in loss of production of growth inhibitory peptides from Substance P. Similarly, ADAM-10 also efficiently hydrolyzes Calcitonin Gene-Related Peptide, which may act in concert with Substance P. Finally, overactivity of Ets transcriptional suppressor functions has been linked to inhibition of tumorigenesis (e.g., Erf and Mef), and in addition loss of Elk-3 expression might also be be linked to tumorigenesis via loss of its putative anti-inflammatory activities. There is anecdotal evidence in the literature to indicate that the rest of the down-regulated genes may also contribute to development of a more aggressive phenotype in this breast cancer model.