IGF-1 gene therapy prevents spatial memory deficits and modulates dopaminergic neurodegeneration and inflammation in a parkinsonism model.

Cognitive impairment in Parkinson's disease is considered an indicator of the prodromal stages of this condition, occurring prior to the onset of classic and pathognomonic motor symptoms. Among other factors, neuroinflammation is increasingly recognized as a potential mediator of this neurodegenerative process, and glial cells are directly involved. However, the use of neurotrophic factors is associated with neuroprotection and cognitive improvements. Among all those factors, insulin-like growth factor 1 (IGF-1) has attracted considerable attention. In this study, we aimed to investigate the effect of IGF-1 gene therapy in an early animal model of 6-hydroxidopamine (6-OHDA)- induced parkinsonism. For this purpose, we employed male Wistar rats. The animals were first divided into two groups according to the bilateral injection into de Caudate Putamen unit (CPu):(a) VEH group (vehicle solution) and (b) 6-OHDA group (neurotoxic solution). After that, the animals in each group were divided, according to the bilateral injection into the dorsal hippocampus, in a control group (who received a control virus RAd-DSRed) and an experimental group (who received a therapeutic virus (RAd-IGF1). After three weeks of exposure to 6-OHDA, our study showed that IGF-1 gene therapy improved cognitive deficits related to short-term and spatial working memory, it also increased expression levels of tyrosine hydroxylase in the CPu. In addition, the therapy resulted in significant changes in several parameters (area, perimeter, roundness, ramification, and skeleton ́s analyses) related to microglia and astrocyte phenotypes, particularly in the CPu and dorsal hippocampal areas. Our data support the use of IGF-1 as a therapeutic molecule for future gene transfer interventions, that will contribute to a better understanding of the mechanisms correlating cognitive function and inflammatory process.

Brain and spinal cord trauma: what we know about the therapeutic potential of insulin growth factor 1 gene therapy.

Although little attention has been paid to cognitive and emotional dysfunctions observed in patients after spinal cord injury, several reports have described impairments in cognitive abilities. Our group also has contributed significantly to the study of cognitive impairments in a rat model of spinal cord injury. These findings are very significant because they demonstrate that cognitive and mood deficits are not induced by lifestyle changes, drugs of abuse, and combined medication. They are related to changes in brain structures involved in cognition and emotion, such as the hippocampus. Chronic spinal cord injury decreases neurogenesis, enhances glial reactivity leading to hippocampal neuroinflammation, and triggers cognitive deficits. These brain distal abnormalities are recently called tertiary damage. Given that there is no treatment for Tertiary Damage, insulin growth factor 1 gene therapy emerges as a good candidate. Insulin growth factor 1 gene therapy recovers neurogenesis and induces the polarization from pro-inflammatory towards anti-inflammatory microglial phenotypes, which represents a potential strategy to treat the neuroinflammation that supports tertiary damage. Insulin growth factor 1 gene therapy can be extended to other central nervous system pathologies such as traumatic brain injury where the neuroinflammatory component is crucial. Insulin growth factor 1 gene therapy could emerge as a new therapeutic strategy for treating traumatic brain injury and spinal cord injury.

IGF1 gene therapy in middle-aged female rats delays reproductive senescence through its effects on hypothalamic GnRH and kisspeptin neurons.

The process of aging is the result of progressive loss of homeostasis and functional body impairment, including the central nervous system, where the hypothalamus plays a key role in regulating aging mechanisms. The consequences of aging include a chronic proinflammatory environment in the hypothalamus that leads to decreased secretion of gonadotropin-releasing hormone (GnRH) and impairs kisspeptin neuron functionality. In this work, we investigated the effect of insulin-like growth factor 1 (IGF1) gene therapy on hypothalamic kisspeptin/GnRH neurons and on microglial cells, that mediate the inflammatory process related with the aging process. The results show that IGF1 rats have higher kisspeptin expression in the anteroventral periventricular (AVPV) nucleus and higher immunoreactivity of GnRH in the arcuate nucleus and median eminence. In addition, IGF1-treated animals exhibit increased numbers of Iba1+ microglial cells and MHCII+/Iba1+ in the AVPV and arcuate nuclei. In conclusion, IGF1 gene therapy maintains kisspeptin production in the AVPV nucleus, induces GnRH release in the median eminence, and alters the number and reactivity of microglial cells in middle-aged female rats. We suggest that IGF1 gene therapy may have a protective effect against reproductive decline.

IGF-1 Gene Transfer Modifies Inflammatory Environment and Gene Expression in the Caudate-Putamen of Aged Female Rat Brain.

Brain aging is characterized by chronic neuroinflammation caused by activation of glial cells, mainly microglia, leading to alterations in homeostasis of the central nervous system. Microglial cells are constantly surveying their environment to detect and respond to diverse signals. During aging, microglia undergoes a process of senescence, characterized by loss of ramifications, spheroid formation, and fragmented processes, among other abnormalities. Therefore, the study of changes in microglia during is of great relevance to understand age-related declines in cognitive and motor function. We have targeted the deleterious effects of aging by implementing IGF-1 gene transfer, employing recombinant adenoviral vectors (RAds) as a delivery system. In this study, we performed intracerebroventricular (ICV) RAd-IGF-1 or control injection on aged female rats and evaluated its effect on caudate-putamen unit (CPu) gene expression and inflammatory state. Our results demonstrate that IGF-1 overexpression modified aged microglia of the CPu towards an anti-inflammatory condition increasing the proportion of double immuno-positive Iba1+Arg1+ cells. We also observed that phosphorylation of Akt was increased in animals treated with RAd-IGF-1. Moreover, IGF-1 gene transfer was able to regulate CPu pro-inflammatory environment in female aged rats by down-regulating the expression of genes typically overexpressed during aging. RNA-Seq data analysis identified 97 down-modulated DEG in the IGF-1 group as compared to the DsRed one. Interestingly, 12 of these DEG are commonly overexpressed during aging, and 9 out of 12 are expressed in microglia/macrophages and are involved in different processes that lead to neuroinflammation and/or neuronal loss. Finally, we observed that IGF-1 overexpression led to an improvement in motor functions. Although further studies are necessary, with the present results, we conclude that IGF-1 gene transfer is modifying both the pro-inflammatory environment and activation of microglia/macrophages in CPu. In this regard, IGF-1 gene transfer could counteract the neuroinflammatory effects associated with aging and improve motor functions in senile animals.

Intramuscular insulin-like growth factor-1 gene therapy modulates reactive microglia after traumatic brain injury.

Reactive gliosis is a key feature and an important pathophysiological mechanism underlying chronic neurodegeneration following traumatic brain injury (TBI). In this study, we have explored the effects of intramuscular IGF-1 gene therapy on reactive gliosis and functional outcome after an injury of the cerebral cortex. Young adult male rats were intramuscularly injected with a recombinant adenoviral construct harboring the cDNA of human IGF-1 (RAd-IGF1), with a control vector expressing green fluorescent protein (RAd-GFP) or PBS as control. Three weeks after the intramuscular injections of adenoviral vectors, animals were subjected to a unilateral penetrating brain injury. The data revealed that RAd-IGF1 gene therapy significantly increased serum IGF1 levels and improved working memory performance after one week of TBI as compared to PBS or RAd-GFP lesioned animals. At the same time, when we analyzed the effects of therapy on glial scar formation, the treatment with RAd-IGF1 did not modify the number of glial fibrillary acidic protein (GFAP) positive cells, but we observed a decrease in vimentin immunoreactive astrocytes at 7 days post-lesion in the injured hemisphere compared to RAd-GFP group. Moreover, IGF-1 gene therapy reduced the number of Iba1+ cells with reactive phenotype and the number of MHCII + cells in the injured hemisphere. These results suggest that intramuscular IGF-1 gene therapy may represent a new approach to prevent traumatic brain injury outcomes in rats.

IGF1 Gene Therapy Reversed Cognitive Deficits and Restored Hippocampal Alterations After Chronic Spinal Cord Injury.

The hippocampus is implicated in the generation of memory and learning, processes which involve extensive neuroplasticity. The generation of hippocampal adult-born neurons is particularly regulated by glial cells of the neurogenic niche and the surrounding microenvironment. Interestingly, recent evidence has shown that spinal cord injury (SCI) in rodents leads to hippocampal neuroinflammation, neurogenesis reduction, and cognitive impairments. In this scenario, the aim of this work was to evaluate whether an adenoviral vector expressing IGF1 could reverse hippocampal alterations and cognitive deficits after chronic SCI. SCI caused neurogenesis reduction and impairments of both recognition and working memories. We also found that SCI increased the number of hypertrophic arginase-1 negative microglia concomitant with the decrease of the number of ramified surveillance microglia in the hilus, molecular layer, and subgranular zone of the dentate gyrus. RAd-IGF1 treatment restored neurogenesis and improved recognition and working memory impairments. In addition, RAd-IGF1 gene therapy modulated differentially hippocampal regions. In the hilus and molecular layer, IGF1 gene therapy recovered the number of surveillance microglia coincident with a reduction of hypertrophic microglia cell number. However, in the neurogenic niche, IGF1 reduced the number of ramified microglia and increased the number of hypertrophic microglia, which as a whole expressed arginase-1. In summary, RAd-IGF1 gene therapy might surge as a new therapeutic strategy for patients with hippocampal microglial alterations and cognitive deficits such as those with spinal cord injury and other neurodegenerative diseases.

Sex frailty differences in ageing mice: Neuropathologies and therapeutic projections.

It is well-established that females live longer than males. Paradoxically, women tend to have poorer health, a condition often named sex frailty. The aim of this study was to evaluate possible frailty predictors in older mice in a sex-specific manner, in order to employ these predictors to follow-up therapy efficiency. To further evaluate therapy effects, we also investigated the use of neurotrophic insulin-like growth factor 1 (IGF-1) gene therapy and its correlation with the expression of this frailty and emotional behaviour. In order to evaluate frailty, we employed two different approaches. We performed a frailty assessment through a 31-Item Clinical Frailty Index and through a Performance-Based 8-Item Frailty Index. Our results show that both indexes are in concordance to evaluate sex differences, but they do not correlate when evaluating IGF-1 therapy effects. Moreover, in order to reduce test-to-test variability for measures of dependent variables, we compared open field results across studies assessing sex and treatment by means of the z-score normalization. The data show that regular open field parameters submitted to z-score normalization analysis could be a useful tool to identify sex differences in ageing mice after growth factor therapies. Taking this into account, sex is a factor that influences the incidence and/or nature of all major complex diseases; the main outcome of our investigation is the development of an efficient tool that compares the use of different frailty index calculations. This represents an important strategy in order to identify sex differences and therapy efficiency in ageing models.

Novel adenoviral IGF-1 administration modulates the association between depressive symptoms and aging: Does gender matter?

Depression is an illness of multifactorial origin and it seems to involve the dysregulation of many physiological processes. It also has been associated with age and a decreased in the expression of some neurotrophins. However, there are not unique animal models to assay depressive-like behavior, with male and females responding differently. In this study, we report the effects of gender on aged associated depressive signs as frailty, muscular strength and motor activity, as well as the role of intramuscular IGF-1 gene therapy in these processes. We found that male mice had higher general discomfort than females. Moreover, we observed that IGF-1 treatment did not modify this index in females. Regarding male mice, adenoviral IGF-1 injection reduced frailty scores compared to its adenoviral control. According to data, IGF-1 gene therapy had a positive effect on depressive associated hypo-locomotion activity as indicate by delta of total distance and the increment observed in time of mobility in male mice. This neurotrophic factor also increased the latency of time to fall in grip strength in male mice compared to female mice. Moreover, we observed that, while the therapy had no effect on the digging behavior, IGF-1 treatment diminished the latency to dig and increase the number of buried marbles in male mice, having no effect on female. The present study demonstrates that, in order to establish an animal model of depression both, gender and age are relevant variables/factors to consider. We also conclude that a frailty phenotype underlies depressive-like symptoms in an experimental mouse model. Furthermore, we demonstrated that intramuscular injection represents a less invasive, feasible and controllable route of IGF-1 gene delivery for the treatment of the depressive phenotype in old mice.

IGF1 Gene Therapy Modifies Microglia in the Striatum of Senile Rats.

Microglial cells become dystrophic with aging; this phenotypic alteration contributes to basal central nervous system (CNS) neuroinflammation being a risk factor for age related neurodegenerative diseases. In previous studies we have observed that insulin like growth factor 1 (IGF1) gene therapy is a feasible approach to target brain cells, and that is effective to modify inflammatory response in vitro and to ameliorate cognitive or motor deficits in vivo. Based on these findings, the main aim of the present study is to investigate the effect of IGF1 gene therapy on microglia distribution and morphology in the senile rat. We found that IGF1 therapy leads to a region-specific modification of aged microglia population.

Aldehyde dehydrogenase 2 in the spotlight: The link between mitochondria and neurodegeneration.

Growing body of evidence suggests that mitochondrial dysfunctions and resultant oxidative stress are likely responsible for many neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). Aldehyde dehydrogenase (ALDH) superfamily plays a crucial role in several biological processes including development and detoxification pathways in the organism. In particular, ALDH2 is crucial in the oxidative metabolism of toxic aldehydes in the brain, such as catecholaminergic metabolites (DOPAL and DOPEGAL) and the principal product of lipid peroxidation process 4-HNE. This review aims to deepen the current knowledge regarding to ALDH2 function and its relation with brain-damaging processes that increase the risk to develop neurodegenerative disorders. We focused on relevant literature of what is currently known at molecular and cellular levels in experimental models of these pathologies. The understanding of ALDH2 contributions could be a potential target in new therapeutic approaches for PD and AD due to its crucial role in mitochondrial normal function maintenance that protects against neurotoxicity.

Estradiol and testosterone regulate arginine-vasopressin expression in SH-SY5Y human female neuroblastoma cells through estrogen receptors-α and -ß.

The expression of arginine-vasopressin (AVP) is regulated by estradiol and testosterone (T) in different neuronal populations by mechanisms that are not yet fully understood. Estrogen receptors (ERs) have been shown to participate in the regulation of AVP neurons by estradiol. In addition, there is evidence of the participation of ERß in the regulation of AVP expression exerted by T via its metabolite 5α-dihydrotestosterone (5α-DHT) and its further conversion in the androgen metabolite and ERß ligand 3ß-diol. In this study we have explored the role of ERs in the regulation exerted by estradiol and T on AVP expression, using the human neuroblastoma cell line SH-SY5Y. Estradiol treatment increased AVP mRNA levels in SH-SY5Y cells in comparison with cells treated with vehicle. The stimulatory effect of estradiol on AVP expression was imitated by the ERα agonist 4,4',4',-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol and blocked by the ER antagonist, ICI 182,780, and the ERα antagonist 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1hpyrazoledihydrochloride. In contrast, the ERß agonist 2,3-bis(4-hydroxyphenyl)-propionitrile reduced AVP expression, whereas the ERß antagonist 4-[2-phenyl-5,7-bis(trifluoromethyl) pyrazolo[1,5-a]pyrimidin-3-yl]phenol enhanced the action of estradiol on AVP expression. T increased AVP expression in SH-SY5Y cells by a mechanism that was dependent on aromatase but not on 5α-reductase activity. The T effect was not affected by blocking the androgen receptor, was not imitated by the T metabolite 5α-DHT, and was blocked by the ERα antagonist 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1hpyrazoledihydrochloride. In contrast, 5α-DHT had a similar effect as the ERß agonists 2,3-bis(4-hydroxyphenyl)-propionitrile and 3ß-diol, reducing AVP expression. These findings suggest that estradiol and T regulate AVP expression in SH-SY5Y cells through ERs, exerting a stimulatory action via ERα and an inhibitory action via ERß.

Prenatal stress increases the expression of proinflammatory cytokines and exacerbates the inflammatory response to LPS in the hippocampal formation of adult male mice.

Early life experiences, such as prenatal stress, may result in permanent alterations in the function of the nervous and immune systems. In this study we have assessed whether prenatal stress affects the inflammatory response of the hippocampal formation of male mice to an inflammatory challenge during adulthood. Pregnant C57BL/6 mice were randomly assigned to stress (n=10) or non-stress (n=10) groups. Animals of the stress group were placed in plastic transparent cylinders and exposed to bright light for 3 sessions of 45min every day from gestational day 12 to parturition. Non-stressed pregnant mice were left undisturbed. At four months of age, non stressed and prenatally stressed male offspring were killed, 24h after the systemic administration of lipopolysaccharide (LPS) or vehicle. Under basal conditions, prenatally stressed animals showed increased expression of interleukin 1ß and tumor necrosis factor-α (TNF-α) in the hippocampus and an increased percentage of microglia cells with reactive morphology in CA1 compared to non-stressed males. Furthermore, prenatally stressed mice showed increased TNF-α immunoreactivity in CA1 and increased number of Iba-1 immunoreactive microglia and GFAP-immunoreactive astrocytes in the dentate gyrus after LPS administration. In contrast, LPS did not induce such changes in non-stressed animals. These findings indicate that prenatal stress induces a basal proinflammatory status in the hippocampal formation during adulthood that results in an enhanced activation of microglia and astrocytes in response to a proinflammatory insult.

Influence on effectiveness of early treatment with anti-TNF therapy in rheumatoid arthritis.

PURPOSE: To evaluate the association between starting early treatment with anti-TNF and effectiveness as well as the possibility of applying therapeutic spacing in daily practice in patients with rheumatoid arthritis (RA). METHODS: Observational, retrospective study conducted in two universitary hospitals in Spain. RA patients who received the first anti-TNF (adalimumab: ADA, etanercept: ETN or infliximab: IFX) during the study period (October 2006-2010) were included. Demographic data, time since diagnosis, disease activity (DAS28-ESR) and anti-TNF dosage were analyzed. Therapeutic objective was defined as DAS28 DAS28 < 2.6. Also the response related to criteria of the European League Against Rheumatism (EULAR) was evaluated. Therapeutic spacing was defined as the use of a lower dose or a higher interval according to label doses. The main endpoint was to assess the association between the effectiveness and the moment when the anti-TNF therapy begins. The secondary target was to evaluate the association between RA activity at the beginning of treatment with anti-TNF and dose used. Results. 82 patients were included. The prescription profile was: ADA (48.8%), ETN (31.7%) and IFX (19.5%). 71.4% of patients treated with anti-TNF during the first year since diagnosis, 57.1% of those who started after 1-5 years and 30.6% of patients who started after 5 years were in remission when the study ended. De-escalation strategy was performed in 25.6% of patients: ETN (38.5%), ADA (20.0%) and IFX (18.8%). The patients treated with a higher dose according to label doses were: IFX (81%), ADA, (12.5%) and ETN (7.7%). CONCLUSIONS: Results suggest that early treatment with anti-TNF can achieve a higher percentage of remissions. Therapeutic spacing is established as a strategy that improves the efficiency in those patients in remission, being the ETN the anti-TNF most susceptible for spacing, although a relation between the early beginning with anti-TNF and the used dose was not found.

Estradiol decreases cortical reactive astrogliosis after brain injury by a mechanism involving cannabinoid receptors.

The neuroactive steroid estradiol reduces reactive astroglia after brain injury by mechanisms similar to those involved in the regulation of reactive gliosis by endocannabinoids. In this study, we have explored whether cannabinoid receptors are involved in the effects of estradiol on reactive astroglia. To test this hypothesis, the effects of estradiol, the cannabinoid CB1 antagonist/inverse agonist AM251, and the cannabinoid CB2 antagonist/inverse agonist AM630 were assessed in the cerebral cortex of male rats after a stab wound brain injury. Estradiol reduced the number of vimentin immunoreactive astrocytes and the number of glial fibrillary acidic protein immunoreactive astrocytes in the proximity of the wound. The effect of estradiol was significantly inhibited by the administration of either CB1 or CB2 receptor antagonists. The effect of estradiol may be in part mediated by alterations in endocannabinoid signaling because the hormone increased in the injured cerebral cortex the messenger RNA levels of CB2 receptors and of some of the enzymes involved in the synthesis and metabolism of endocannabinoids. These findings suggest that estradiol may decrease reactive astroglia in the injured brain by regulating the activity of the endocannabinoid system.

Actions of estrogens on glial cells: Implications for neuroprotection.

Glial cells are directly or indirectly affected by estradiol and by different estrogenic compounds, such as selective estrogen receptor modulators. Acting on oligodendrocytes, astrocytes and microglia, estrogens regulate remyelination, edema formation, extracellular glutamate levels and the inflammatory response after brain injury. In addition, estradiol induces the expression and release of growth factors by glial cells that promote neuronal survival. Therefore, glial cells are important players in the neuroprotective and reparative mechanisms of estrogenic compounds.

Protective effect of estrogens on the brain of rats with essential and endocrine hypertension.

Estrogen neuroprotection has been shown in pathological conditions damaging the hippocampus, such as trauma, aging, neurodegeneration, excitotoxicity, oxidative stress, hypoglycemia, amyloid-ß peptide exposure and ischemia. Hypertensive encephalopathy also targets the hippocampus; therefore, hypertension seems an appropriate circumstance to evaluate steroid neuroprotection. Two experimental models of hypertension, spontaneously hypertensive rats (SHR) and deoxycorticosterone (DOCA)-salt hypertensive rats, develop hippocampal abnormalities, which include decreased neurogenesis in the dentate gyrus, astrogliosis, low expression of brain-derived neurotrophic factor (BDNF) and decreased number of neurons in the hilar region, with respect of their normotensive strains Wistar Kyoto (WKY) and Sprague-Dawley rats. After estradiol was given for 2 weeks to SHR and DOCA-treated rats, both hypertensive models normalized their faulty hippocampal parameters. Thus, estradiol treatment positively modulated neurogenesis in the dentate gyrus of the hippocampus, according to bromodeoxyuridine incorporation and doublecortin immunocytochemistry, decreased reactive astrogliosis, increased BDNF mRNA and protein expression in the dentate gyrus and increased neuronal number in the hilar region of the dentate gyrus. A role of local estrogen biosynthesis is suggested in SHR, because basal aromatase mRNA in the hippocampus and immunoreactive aromatase protein in cell processes of the dentate gyrus were highly expressed in these rats. Estradiol further stimulated aromatase-related parameters in SHR but not in WKY. These observations strongly support that a combination of exogenous estrogens to those locally synthesized might better alleviate hypertensive encephalopathy. These studies broaden estrogen neuroprotective functions to the hippocampus of hypertensive rat models.

The thymus-neuroendocrine axis: physiology, molecular biology, and therapeutic potential of the thymic peptide thymulin.

Thymulin is a thymic hormone exclusively produced by the thymic epithelial cells. It consists of a nonapeptide component coupled to the ion zinc, which confers biological activity to the molecule. After its discovery in the early 1970s, thymulin was characterized as a thymic hormone involved in several aspects of intrathymic and extrathymic T cell differentiation. Subsequently, it was demonstrated that thymulin production and secretion is strongly influenced by the neuroendocrine system. Conversely, a growing core of information, to be reviewed here, points to thymulin as a hypophysotropic peptide. In recent years, interest has arisen in the potential use of thymulin as a therapeutic agent. Thymulin was shown to possess anti-inflammatory and analgesic properties in the brain. Furthermore, an adenoviral vector harboring a synthetic gene for thymulin, stereotaxically injected in the rat brain, achieved a much longer expression than the adenovirally mediated expression in the brain of other genes, thus suggesting that an anti-inflammatory activity of thymulin prevents the immune system from destroying virus-transduced brain cells. Other studies suggest that thymulin gene therapy may also be a suitable therapeutic strategy to prevent some of the endocrine and metabolic alterations that typically appear in thymus-deficient animal models. The present article briefly reviews the literature on the physiology, molecular biology, and therapeutic potential of thymulin.