Peptides: important tools for the treatment of central nervous system disorders

Exploring the Molecular Tapestry: Organ-Specific Peptide and Protein Ultrafiltrates and Their Role in Therapeutics

This study aims to characterize the proteome composition of organ-derived protein extracts from rabbits. Protein isolation was performed using soft homogenization and size exclusion via ultrafiltration. The proteome analysis of the ultrafiltrates was conducted using gel electrophoresis, and the mass spectrometry data were subjected to gene ontology analysis. Proteomic profiling revealed comprehensive protein profiles associated with RNA regulation, fatty acid binding, inflammatory response, oxidative stress, and metabolism. Additionally, our results demonstrate the presence of abundant small proteins, as observed in the mass spectrometry datasets. Small proteins and peptides are crucial in transcription modulation and various biological processes. The protein networks identified in the ultrafiltrates have the potential to enhance and complement biological therapeutic interventions. Data are available via ProteomeXchange with identifier PXD050039.

Death-associated protein kinase 1 as a therapeutic target for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly and represents a major clinical challenge in the ageing society. Neuropathological hallmarks of AD include neurofibrillary tangles composed of hyperphosphorylated tau, senile plaques derived from the deposition of amyloid-β (Aβ) peptides, brain atrophy induced by neuronal loss, and synaptic dysfunctions. Death-associated protein kinase 1 (DAPK1) is ubiquitously expressed in the central nervous system. Dysregulation of DAPK1 has been shown to contribute to various neurological diseases including AD, ischemic stroke and Parkinson's disease (PD). We have established an upstream effect of DAPK1 on Aβ and tau pathologies and neuronal apoptosis through kinase-mediated protein phosphorylation, supporting a causal role of DAPK1 in the pathophysiology of AD. In this review, we summarize current knowledge about how DAPK1 is involved in various AD pathological changes including tau hyperphosphorylation, Aβ deposition, neuronal cell death and synaptic degeneration. The underlying molecular mechanisms of DAPK1 dysregulation in AD are discussed. We also review the recent progress regarding the development of novel DAPK1 modulators and their potential applications in AD intervention. These findings substantiate DAPK1 as a novel therapeutic target for the development of multifunctional disease-modifying treatments for AD and other neurological disorders.

Designing Formulation Strategies for Enhanced Stability of Therapeutic Peptides in Aqueous Solutions: A Review

Over the past few decades, there has been a tremendous increase in the utilization of therapeutic peptides. Therapeutic peptides are usually administered via the parenteral route, requiring an aqueous formulation. Unfortunately, peptides are often unstable in aqueous solutions, affecting stability and bioactivity. Although a stable and dry formulation for reconstitution might be designed, from a pharmaco-economic and practical convenience point of view, a peptide formulation in an aqueous liquid form is preferred. Designing formulation strategies that optimize peptide stability may improve bioavailability and increase therapeutic efficacy. This literature review provides an overview of various degradation pathways and formulation strategies to stabilize therapeutic peptides in aqueous solutions. First, we introduce the major peptide stability issues in liquid formulations and the degradation mechanisms. Then, we present a variety of known strategies to inhibit or slow down peptide degradation. Overall, the most practical approaches to peptide stabilization are pH optimization and selecting the appropriate type of buffer. Other practical strategies to reduce peptide degradation rates in solution are the application of co-solvency, air exclusion, viscosity enhancement, PEGylation, and using polyol excipients.

Deciphering the molecular mechanism and crosstalk between Parkinson's disease and breast cancer through multi-omics and drug repurposing approach

Epidemiological studies indicate a higher occurrence of breast cancer (BRCA) in patients with Parkinson's disease. However, the exact molecular mechanism is still not precise. Herein, we tested the hypothesis that this inverse comorbidity result from shared genetic and molecular processes. We conducted an integrated omics analysis to identify the common gene signatures associated with PD and BRCA. Secondly, several dysregulated biological processes in both indications were analyzed by functional enrichment methods, and significant overlapping processes were identified. To establish common regulatory mechanisms, information about transcription factors and miRNAs associated with both the disorders was extracted. Finally, disease-specific gene expression signatures were compared through LINCS L1000 analysis to identify potential repurposing drugs for PD. The potential repurposed drug candidates were then correlated with PD-specific gene signatures by Cmap analysis. In conclusion, this study highlights the shared genes, biological pathways and regulatory signatures associated with PD and BRCA with an improved understanding of crosstalk involved. Additionally, the role of therapeutics was investigated in context with their comorbid associations. These findings could help to explain the complex molecular patterns of associations between PD and BRCA.

Metabolism of a New Dipeptide Neuroprotector in Rats

Metabolism of a new neuroprotector GZK-111 (N-phenylacetylglycyl-L-proline ethyl ester) in rat blood plasma was studied by HPLC-mass spectrometry. Four biotransformation products were identified. It is concluded that the main ways of GZK-111 biotransformation are hydrolysis of the ester bond by esterases followed by degradation of the resulting metabolite, as well as reactions leading to the formation of phenylacetic acid and cycloprolylglycine that exhibits neuropsychotropic activity.

Comparative Evaluation of Radiochemical and Biological Properties of 131I- and [99mTc]Tc(CO)3-Labeled RGD Analogues Planned to Interact with the αvβ3 Integrin Expressed in Glioblastoma

Radiolabeled peptides with high specificity for overexpressed receptors in tumor cells hold great promise for diagnostic and therapeutic applications. In this work, we aimed at comparing the radiolabeling efficiency and biological properties of two different RGD analogs: GRGDYV and GRGDHV, labeled with iodine-131 (¹³¹I) and technetium-99m-tricarbonyl complex [^99mTc][Tc(CO)₃]⁺. Additionally, we evaluated their interaction with the α_vβ₃ integrin molecule, overexpressed in a wide variety of tumors, including glioblastoma. Both peptides were chemically synthesized, purified and radiolabeled with ¹³¹I and [^99mTc][Tc(CO)₃]⁺ using the chloramine-T and tricarbonyl methodologies, respectively. The stability, binding to serum proteins and partition coefficient were evaluated for both radioconjugates. In addition, the binding and internalization of radiopeptides to rat C6 glioblastoma cells and rat brain homogenates from normal animals and a glioblastoma-induced model were assessed. Finally, ex vivo biodistribution studies were carried out. Radiochemical yields between 95–98% were reached for both peptides under optimized radiolabeling conditions. Both peptides were stable for up to 24 h in saline solution and in human serum. In addition, the radiopeptides have hydrophilic characteristics and a percentage of binding to serum proteins around 35% and 50% for the [¹³¹I]I-GRGDYV and [^99mTc]Tc(CO)₃-GRGDHV fragments, respectively. Radiopeptides showed the capacity of binding and internalization both in cell culture (C6) and rat brain homogenates. Biodistribution studies corroborated the results obtained with brain homogenates and confirmed the different binding characteristics due to the exchange of radionuclides and the presence of the tricarbonyl complex. Thereby, the results showed that both radiopeptides might be considered for future clinical applications.

Preclinical Pharmacokinetics of GZK-111, a Dipeptide with Neuroprotective Activity

We studied the pharmacokinetics of GZK-111 (N-phenylacetyl-glycyl-L-proline ethyl ether), a compound with neuroprotective activity, and its metabolite CPG (cyclo-L-prolylglycine) in rat blood plasma after single intravenous and intragastric administration in a dose of 20 mg/kg. It was found that the parent drug undergoes intensive biotransformation; its metabolite CPG persists in the circulation more than twice as long as GZK-111 and its plasma concentrations were higher by 50-70 times than the concentrations of the parent compound.

Lipidized Prolactin-Releasing Peptide as a New Potential Tool to Treat Obesity and Type 2 Diabetes Mellitus: Preclinical Studies in Rodent Models

Obesity and type 2 diabetes mellitus (T2DM) are preconditions for the development of metabolic syndrome, which is reaching pandemic levels worldwide, but there are still only a few anti-obesity drugs available. One of the promising tools for the treatment of obesity and related metabolic complications is anorexigenic peptides, such as prolactin-releasing peptide (PrRP). PrRP is a centrally acting neuropeptide involved in food intake and body weight (BW) regulation. In its natural form, it has limitations for peripheral administration; thus, we designed analogs of PrRP lipidized at the N-terminal region that showed high binding affinities, increased stability and central anorexigenic effects after peripheral administration. In this review, we summarize the preclinical results of our chronic studies on the pharmacological role of the two most potent palmitoylated PrRP31 analogs in various mouse and rat models of obesity, glucose intolerance, and insulin resistance. We used mice and rats with diet-induced obesity fed a high-fat diet, which is considered to simulate the most common form of human obesity, or rodent models with leptin deficiency or disrupted leptin signaling in which long-term food intake regulation by leptin is distorted. The rodent models described in this review are models of metabolic syndrome with different severities, such as obesity or morbid obesity, prediabetes or diabetes and hypertension. We found that the effects of palmitoylated PrRP31 on food intake and BW but not on glucose intolerance require intact leptin signaling. Thus, palmitoylated PrRP31 analogs have potential as therapeutics for obesity and related metabolic complications.

Radiochemical and biological properties of peptides designed to interact with EGF receptor: Relevance for glioblastoma

Radiolabeled peptides with high specificity to receptors expressed on tumor cells hold a great promise as diagnostic and therapeutic tracers. The main objective of this study was to evaluate the radiochemical and biological properties of two [¹³¹I]I-peptides, as well as their interaction with the epidermal growth factor receptor (EGFR), overexpressed in a wide variety of tumors, including glioblastoma. The EEEEYFELV peptide and its analogue DEDEYFELV, both designed to interact with EGFR, were chemically synthesized, purified and radiolabeled with iodine-131 ([¹³¹I]NaI). The radioiodination was evaluated and optimized using the chloramine-T methodology. The stability, serum proteins binding and partition coefficient were assessed for both radioconjugates. Moreover, the binding and internalization of synthesized radiopeptides with rat glioblastoma cells (C6) and with rat brain homogenates from a glioblastoma induced model were evaluated and ex vivo biodistribution studies were performed. Under optimized radiolabeling conditions, the peptides showed an average radiochemical yield of 90-95%. The stability studies showed that both peptides were stable up to 24 h in reaction medium, saline, and human serum. Furthermore, [¹³¹I]I-peptides have hydrophilic features and showed binding percentage to serum proteins of around 50%, which is highly compatible with clinical applications. Moreover, the radiopeptides presented capacity for binding and internalization in both tumor cells (C6) and rat brain tissues after tumor induction. Biodistribution studies corroborated the cell culture studies and confirmed the different binding characteristics derived from a simple change of two amino acids (Glu ➔ Asp^1,3) in their sequences. The results obtained are consistent enough to motivate further studies. Thereby, these radiolabeled peptides might be useful for diagnostic applications.

Neuropeptides and oligopeptidases in schizophrenia

Schizophrenia (SCZ) is a complex psychiatric disorder with severe impact on patient's livelihood. In the last years, the importance of neuropeptides in SCZ and other CNS disorders has been recognized, mainly due to their ability to modulate the signaling of classical monoaminergic neurotransmitters as dopamine. In addition, a class of enzymes coined as oligopeptidases are able to cleave several of these neuropeptides, and their potential implication in SCZ was also demonstrated. Interestingly, these enzymes are able to play roles as modulators of neuropeptidergic systems, and they were also implicated in neurogenesis, neurite outgrowth, neuron migration, and therefore, in neurodevelopment and brain formation. Altered activity of oligopeptidases in SCZ was described only more recently, suggesting their possible utility as biomarkers for mental disorders diagnosis or treatment response. We provide here an updated and comprehensive review on neuropeptides and oligopeptidases involved in mental disorders, aiming to attract the attention of physicians to the potential of targeting this system for improving the therapy and for understanding the neurobiology underlying mental disorders as SCZ.

[Molecular mechanisms of brain peptide-containing drugs: cortexin]

The goal of treatment of brain pathologies may be regarded as re-establishment of optimal brain plasticity. Disturbances in neuroplasticity are associated with the appearance of multiple targets that should be subjects for pharmacological correction. Peptide hydrolysates derived from animal brain became a basis for multi-component organ-specific drugs which are widely used for treatment of cerebral pathologies. Potentially, the presence of many components in such drugs may be beneficial for simultaneous effects on different targets. In this article, new data are analyzed related to relevant molecular mechanisms underlying neuroprotective properties of cortexin. On a model of accelerated aging in rats, cortexin restored the ratio of pro- and antioxidative systems and demonstrated a significant anti-inflammatory effect both in the brain and at the systemic level. In in vitro experiments cortexin effectively and tissue-specifically inhibited brain caspase-8. Neuron-specific proteins β5-tubulin, creatine kinase B and protein 14-3-3 α/β were shown to be molecular partners of cortexin peptides in the brain. Thus, potential molecular mechanisms of cortexin neuroprotective effects are various and associated with key processes underlying neuroplasticity: signal transduction, energy metabolism, proteolytic protein modification, cell structure, as well as neuroinflammation. The pleiotropicity of mechanisms of cortexin action is based on the composition of the drug containing a variety of neuropeptides. The tissue specificity of these mechanisms determines to a significant degree the efficacy of the drug in treatment of cerebral pathologies.

The impact of anorexigenic peptides in experimental models of Alzheimer's disease pathology

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder in the elderly population. Numerous epidemiological and experimental studies have demonstrated that patients who suffer from obesity or type 2 diabetes mellitus have a higher risk of cognitive dysfunction and AD. Several recent studies demonstrated that food intake-lowering (anorexigenic) peptides have the potential to improve metabolic disorders and that they may also potentially be useful in the treatment of neurodegenerative diseases. In this review, the neuroprotective effects of anorexigenic peptides of both peripheral and central origins are discussed. Moreover, the role of leptin as a key modulator of energy homeostasis is discussed in relation to its interaction with anorexigenic peptides and their analogs in AD-like pathology. Although there is no perfect experimental model of human AD pathology, animal studies have already proven that anorexigenic peptides exhibit neuroprotective properties. This phenomenon is extremely important for the potential development of new drugs in view of the aging of the human population and of the significantly increasing incidence of AD.

Chelating and antioxidant properties of l-Dopa containing tetrapeptide for the treatment of neurodegenerative diseases

Neurodegenerative diseases share a common pathogenetic mechanism involving aggregation and deposition of misfolded proteins, oxidative stress, metal dyshomeostasis, and glutamate exicitotoxicity, which lead to progressive dysfunction of central nervous system (CNS). A potential strategy to counteract these deleterious events at neuronal level is represented by the employment of a novel class of multi-target therapeutic agents that selectively and simultaneously hit these targets In this paper, we report the metal binding and antioxidant properties of a novel metal-protein attenuating peptide, GSH-LD, a tetrapeptide obtained by linking glutathione, a well-known antioxidant tripeptide, to L-Dopa. Results demonstrated that GSH-LD possesses chelating capabilities in order to selectively target the excess of metals without interfere with metal-containing antioxidant enzymes. Moreover, antioxidant assays revealed a large contribution of GSH-LD to restore the antioxidant defences of damaged neuronal cells.

Lipidized prolactin-releasing peptide improved glucose tolerance in metabolic syndrome: Koletsky and spontaneously hypertensive rat study

Background/Objectives

Prolactin-releasing peptide (PrRP) has a potential to decrease food intake and ameliorate obesity, but is ineffective after peripheral administration. We have previously shown that our novel lipidized analogs PrRP enhances its stability in the circulation and enables its central effect after peripheral application. The purpose of this study was to explore if sub-chronic administration of novel PrRP analog palmitoylated in position 11 (palm¹¹-PrRP31) to Koletsky-spontaneously hypertensive obese rats (SHROB) could lower body weight and glucose intolerance as well as other metabolic parameters.

Subjects/Methods

The SHROB rats (n = 16) were used for this study and age-matched hypertensive lean SHR littermates (n = 16) served as controls. Palm¹¹-PrRP31 was administered intraperitoneally to SHR and SHROB (n = 8) at a dose of 5 mg/kg once-daily for 3 weeks. During the dosing period food intake and body weight were monitored. At the end of the experiment the oral glucose tolerance test was performed; plasma and tissue samples were collected. Thereafter, arterial blood pressure was measured.

Results

At the end of the experiment, vehicle-treated SHROB rats showed typical metabolic syndrome parameters, including obesity, glucose intolerance, dyslipidemia, and hypertension. Peripheral treatment with palm¹¹-PrRP31 progressively decreased the body weight of SHR rats but not SHROB rats, though glucose tolerance was markedly improved in both strains. Moreover, in SHROB palm¹¹-PrRP31 ameliorated the HOMA index, insulin/glucagon ratio, and increased insulin receptor substrate 1 and 2 expression in fat and insulin signaling in the hypothalamus, while it had no effect on blood pressure.

Conclusions

We demonstrated that our new lipidized PrRP analog is capable of improving glucose tolerance in obese SHROB rats after peripheral application, suggesting that its effect on glucose metabolism is independent of leptin signaling and body weight lowering. These data suggest that this analog has the potential to be a compound with both anti-obesity and glucose-lowering properties.

(R)-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester as dual acting agent for the treatment of Alzheimer's disease

In this study, effects of LA-GPE (R-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester) and GPE (Gly-L-Pro-L-Glu) on the cytotoxic action of Aβ_1-42 were tested with differentiated human neuroblastoma SH-SY5Y cells as cellular Alzheimer model via measurements of mitochondrial viability (MTT assay) and lactate dehydrogenase release (LDH assay). Effects of LA-GPE and GPE on acetylcholinesterase (AChE) activity, total antioxidant capacity (TAC) and total oxidative status (TOS) levels, and neural cell apoptosis and necrosis were also determined. In addition, biological safety of these novel formulations was evaluated in human blood cells using different cytotoxicity and genotoxicity assays. Our results indicated that both compounds could block Aβ_1-42 induced cell death. LA-GPE reduced Aβ-induced AChE activity and oxidative stress, suggesting it as a multifunctional compound potentially valuable for the treatment of Alzheimer's disease (AD).

Spinal neuropeptide modulation, functional assessment and cartilage lesions in a monosodium iodoacetate rat model of osteoarthritis

BACKGROUND AND AIMS

Characterising the temporal evolution of changes observed in pain functional assessment, spinal neuropeptides and cartilage lesions of the joint after chemical osteoarthritis (OA) induction in rats.

METHODS AND RESULTS

On day (D) 0, OA was induced by an IA injection of monosodium iodoacetate (MIA). Rats receiving 2mg MIA were temporally assessed at D3, D7, D14 and D21 for the total spinal cord concentration of substance P (SP), calcitonin gene related-peptide (CGRP), bradykinin (BK) and somatostatin (STT), and for severity of cartilage lesions. At D21, the same outcomes were compared with the IA 1mg MIA, IA 2mg MIA associated with punctual IA injection of lidocaine at D7, D14 and D21, sham (sterile saline) and naïve groups. Tactile allodynia was sequentially assessed using a von Frey anaesthesiometer. Non-parametric and mixed models were applied for statistical analysis. Tactile allodynia developed in the 2mg MIA group as soon as D3 and was maintained up to D21. Punctual IA treatment with lidocaine counteracted it at D7 and D14. Compared to naïve, [STT], [BK] and [CGRP] reached a maximum as early as D7, which plateaued up to D21. For [SP], the increase was delayed up to D14 and maintained at D21. No difference in levels of neuropeptides was observed between MIA doses, except for higher [STT] in the 2mg MIA group (P=0.029). Neuropeptides SP and BK were responsive to lidocaine treatment. The increase in severity of cartilage lesions was significant only in the 2mg MIA groups (P=0.01).

CONCLUSION

In the MIA OA pain model, neuropeptide modulation appears early, and confirms the central nervous system to be an attractive target for OA pain quantification. The relationship of neuropeptide release with severity of cartilage lesions and functional assessment are promising and need further validation.

Neuropeptide Y neuronal network dysfunction in the frontal lobe of a genetic mouse model of schizophrenia

Neuropeptide Y (NPY) has been found to play a critical role in various mental functions as a neurotransmitter and is involved in the development of schizophrenia, a particularly intractable psychiatric disease whose precise etiology remains unknown. Recent molecular biological investigations have identified several candidate genes which may be associated with this disease, including disrupted-in-schizophrenia 1 (DISC1). The role of DISC1 would involve neurogenesis and neuronal migration. However, the functional consequences of this gene defect have not yet been fully clarified in neuronal systems. In the present study, to clarify the neuropathological changes associated with the function of DISC1, we explored how DISC1 dysfunction can induce abnormalities in the NPY neuronal network in the central nervous system. We performed immunohistochemical analyses (including the observation of the distribution and density) of prefrontal cortex specimens from DISC1-knockout (KO) mice, which are considered to be a novel animal model of schizophrenia. We then evaluated the number and size of NPY-immunoreactive (NPY-IR) neurons and the length of NPY-IR fibers. The number of NPY-IR neurons and the length of the fibers were decreased in the prefrontal cortex of DISC1-KO mice. The decrease was particularly prominent in the superficial regions, and the distribution of NPY-IR neurons differed between wild-type and DISC1-KO mice. However, the size of the neurons in the cortices of the DISC1-KO and wild-type mice did not differ markedly. Our findings suggest that dysfunction of DISC1 may lead to the alteration of NPY neurons and neurotransmission issues in NPY-containing neuron systems, which seem to play important roles in both the mental function and neuronal development. DISC1 dysfunction may be involved in the pathogenesis of schizophrenia through the impairment of the NPY neuronal network.

Chronic administration of [Pyr1] apelin-13 attenuates neuropathic pain after compression spinal cord injury in rats

Apelin is an endogenous ligand for apelin receptor (APJ) with analgesic effect on visceral, analgesic and proanalgesic influences on acute pains in animal models. The purpose of this study was to determine the possible analgesic effects of [Pyr¹] apelin-13 on chronic pain after spinal cord injury (SCI) in rats. Animals were randomly divided into three major groups as intact, sham and SCI. The SCI group randomly allocated to four subgroups as no treatment, vehicle-treatment (normal saline: 10μl, intrathecally) and two subgroups with intrathecal injection (i.t) of 1μg and 5μg of [Pyr¹] apelin-13. After laminectomy at T6-T8 level, spinal cord compression injury was induced using an aneurysm clip. Vehicle or [Pyr¹] apelin-13 injected from day1 post SCI and continued for a week on a daily basis. Pain behaviors and locomotor activity were monitored up to 8weeks. At the end of the experiments, intracardial paraformaldehyde perfusion was made under deep anesthesia in some animals for histological and immunohistochemistry evaluations. Western blot technique was also done to detect caspase-3 in fresh spinal cord tissues. SCI decreased nociceptive thresholds and locomotor scores. Administration of [Pyr¹] apelin-13 (1μg and 5μg) improved locomotor activity and reduced pain symptoms, cavity size and caspase-3 levels. Results showed long-term beneficial effects of [Pyr¹] apelin-13 on neuropathic pain and locomotion. Therefore, we may suggest [Pyr¹] apelin-13 as a new option for further neuropathic pain research and a suitable candidate for ensuing clinical trials in spinal cord injury arena.

Prolactin-releasing peptide: a new tool for obesity treatment

Obesity is an escalating epidemic, but an effective noninvasive therapy is still scarce. For obesity treatment, anorexigenic neuropeptides are promising tools, but their delivery from the periphery to the brain is complicated because peptides have a low stability and limited ability to cross the blood-brain barrier. In this review, we summarize results of several studies with our newly designed lipidized analogs of prolactin-releasing peptide (PrRP). PrRP is involved in feeding and energy balance regulation as demonstrated by obesity phenotypes of both PrRP- and PrRP-receptor-knockout mice. Lipidized PrRP analogs showed binding affinity and signaling in PrRP receptor-expressing cells similar to natural PrRP. Moreover, these analogs showed high binding affinity also to anorexigenic neuropeptide FF (NPFF)-2 receptor. Acute peripheral administration of myristoylated and palmitoylated PrRP analogs to mice and rats induced strong and long-lasting anorexigenic effects and neuronal activation in the brain areas involved in food intake regulation. Two-week-long subcutaneous administration of palmitoylated PrRP31 and myristoylated PrRP20 lowered food intake, body weight, improved metabolic parameters and attenuated lipogenesis in mice with diet-induced obesity. A strong anorexigenic, body weight-reducing and glucose tolerance-improving effect of palmitoylated-PrRP31 was shown also in diet-induced obese rats after its repeated 2-week-long peripheral administration. Thus, the strong anorexigenic and body weight-reducing effects of palmitoylated PrRP31 and myristoylated PrRP20 make these analogs attractive candidates for antiobesity treatment. Moreover, PrRP receptor might be a new target for obesity therapy.

Improvement of autism spectrum disorder symptoms in three children by using gastrin-releasing peptide

OBJECTIVE

To evaluate the safety, tolerability and potential therapeutic effects of gastrin-releasing peptide in three children with autistic spectrum disorder.

METHODS

Case series study with the intravenous administration of gastrin-releasing peptide in the dose of 160pmol/kg for four consecutive days. To evaluate the results, parental impressions the Childhood Autism Rating Scale (CARS) and the Clinical Global Impression (CGI) Scale. Each child underwent a new peptide cycle after two weeks. The children were followed for four weeks after the end of the infusions.

RESULTS

The gastrin-releasing peptide was well tolerated and no child had adverse effects. Two children had improved social interaction, with a slight improvement in joint attention and the interaction initiatives. Two showed reduction of stereotypes and improvement in verbal language. One child lost his compulsion to bathe, an effect that lasted two weeks after each infusion cycle. Average reduction in CARS score was 2.8 points. CGI was "minimally better" in two children and "much better" in one.

CONCLUSIONS

This study suggests that the gastrin-releasing peptide is safe and may be effective in improving key symptoms of autism spectrum disorder, but its results should be interpreted with caution. Controlled clinical trials-randomized, double-blinded, and with more children-are needed to better evaluate the possible therapeutic effects of gastrin-releasing peptide in autism.

Brain angiotensin-(1-7)/Mas axis: A new target to reduce the cardiovascular risk to emotional stress

Emotional stress is now considered a risk factor for several diseases including cardiac arrhythmias and hypertension. It is well known that the activation of neuroendocrine and autonomic mechanisms features the response to emotional stress. However, its link to cardiovascular diseases and the regulatory mechanisms involved remain to be further comprehended. The renin-angiotensin system (RAS) plays an important role in homeostasis on all body systems. Specifically in the brain, the RAS regulates a number of physiological aspects. Recent data indicate that the activation of angiotensin-converting enzyme/angiotensin II/AT1 receptor axis facilitates the emotional stress responses. On the other hand, growing evidence indicates that its counterregulatory axis, the angiotensin-converting enzyme 2 (ACE2)/(Ang)iotensin-(1-7)/Mas axis, reduces anxiety and attenuates the physiological responses to emotional stress. The present review focuses on angiotensin-(1-7)/Mas axis as a promising target to attenuate the physiological response to emotional stress reducing the risk of cardiovascular diseases.

Novel delivery systems for improving the clinical use of peptides

Peptides have long been recognized as a promising group of therapeutic substances to treat various diseases. Delivery systems for peptides have been under development since the discovery of insulin for the treatment of diabetes. The challenge of using peptides as drugs arises from their poor bioavailability resulting from the low permeability of biological membranes and their instability. Currently, subcutaneous injection is clinically the most common administration route for peptides. This route is cost-effective and suitable for self-administration, and the development of appropriate dosing equipment has made performing the repeated injections relatively easy; however, only few clinical subcutaneous peptide delivery systems provide sustained peptide release. As a result, frequent injections are needed, which may cause discomfort and additional risks resulting from a poor administration technique. Controlled peptide delivery systems, able to provide required therapeutic plasma concentrations over an extended period, are needed to increase peptide safety and patient compliancy. In this review, we summarize the current peptidergic drugs, future developments, and parenteral peptide delivery systems. Special emphasis is given to porous silicon, a novel material in peptide delivery. Biodegradable and biocompatible porous silicon possesses some unique properties, such as the ability to carry exceptional high peptide payloads and to modify peptide release extensively. We have successfully developed porous silicon as a carrier material for improved parenteral peptide delivery. Nanotechnology, with its different delivery systems, will enable better use of peptides in several therapeutic applications in the near future.

Effect of palmitoylated prolactin-releasing peptide on food intake and neural activation after different routes of peripheral administration in rats

Obesity is an escalating epidemic, but an effective non-invasive therapy is still scarce. For obesity treatment, anorexigenic neuropeptides are promising tools, but their delivery from the periphery to the brain is complicated by their peptide character. In order to overcome this unfavorable fact, we have applied the lipidization of neuropeptide prolactin-releasing peptide (PrRP), whose strong anorexigenic effect was demonstrated. A palmitoylated analog of human PrRP (h palm-PrRP31) was injected in free-fed Wistar rats by three routes: subcutaneous (s.c.), intraperitoneal (i.p) (both 5 mg/kg) and intravenous (i.v.) (from 0.01 to 0.5 mg/kg). We found a circulating compound in the blood after all three applications with the highest concentration after i.v. administration. This corresponds to the effect on food intake, which was also strongest after i.v. injection. Moreover, this is in agreement with the fact that the expression of c-Fos in specific brain regions involved in food intake regulation was also highest after intravenous application. Pharmacokinetic data are further supported by results obtained from dynamic light scattering and CD spectroscopy. Human palm-PrRP31 analog showed a strong tendency to micellize, and formation of aggregates suggested lower availability after i.p. or s.c. application. We have demonstrated that palm-PrRP influenced food intake even in free fed rats. Not surprisingly, the maximal effect was achieved after the intravenous application even though two orders of magnitude lower dose was used compared to both two other applications. We believe that palm-PrRP could have a potential as an antiobesity drug when its s.c. application would be improved.

Pathways and progress in improving drug delivery through the intestinal mucosa and blood-brain barriers

One of the major hurdles in developing therapeutic agents is the difficulty in delivering drugs through the intestinal mucosa and blood-brain barriers (BBB). The goal here is to describe the general structures of the biological barriers and the strategies to enhance drug delivery across these barriers. Prodrug methods used to improve drug penetration via the transcellular pathway have been successfully developed, and some prodrugs have been used to treat patients. The use of transporters to improve absorption of some drugs (e.g., antiviral agents) has also been successful in treating patients. Other methods, including blocking the efflux pumps to improve transcellular delivery, and modulation of cell-cell adhesion in the intercellular junctions to improve paracellular delivery across biological barriers, are still in the investigational stage.

Role of somatostatin and somatostatin receptor type 2 in postincisional nociception in rats

Somatostatin (SST) and the somatostatin receptor type 2 (sstr2) are expressed in the superficial part (Laminae I-III) of the dorsal horn of the spinal cord. Since the neurons in these laminae also receive nociceptive sensation from the periphery, it was hypothesized that both SST and sstr2 could be involved in the modulation of nociceptive transmission. To the best of knowledge, there are no studies on the involvement of SST and sstr2 in hind paw incision model in rats, which mimics postoperative pain in humans. Sprague-Dawley rats were subjected to hind paw incision under isoflurane anaesthesia and the resulting mechanical allodynia and thermal hyperalgesia were evaluated for 5 days. In another set of animals, the spinal cord was isolated at specified time intervals after incision and examined for SST and sstr2 expression using immunohistochemistry and immunoblotting procedures. Finally, nociceptive parameters were again evaluated in incised rats, which had received SST (400 µg/kg i.p. three times per day). Blood glucose level and locomotor activity were determined after SST treatment. Both allodynia and hyperalgesia were highest immediately after incision. Spinal SST expression increased at 2 h. A further increase was noted on day 3. Expression of sstr2 increased initially but decreased at day 1. These changes could be due to exocytosis of SST and internalization of the ligand-receptor complex. SST injection significantly attenuated mechanical allodynia but not thermal hyperalgesia. Significant change in blood glucose level or locomotor activity was absent. SST appears to contribute to postincisional pain. This finding could be of clinical relevance.

PEP-SiteFinder: a tool for the blind identification of peptide binding sites on protein surfaces

Peptide-protein interactions are important to many processes of life, particularly for signal transmission or regulatory mechanisms. When no information is known about the interaction between a protein and a peptide, it is of interest to propose candidate sites of interaction at the protein surface, to assist the design of biological experiments to probe the interaction, or to serve as a starting point for more focused in silico approaches. PEP-SiteFinder is a tool that will, given the structure of a protein and the sequence of a peptide, identify protein residues predicted to be at peptide-protein interface. PEP-SiteFinder relies on the 3D de novo generation of peptide conformations given its sequence. These conformations then undergo a fast blind rigid docking on the complete protein surface, and we have found, as the result of a benchmark over 41 complexes, that the best poses overlap to some extent the experimental patch of interaction for close to 90% complexes. In addition, PEP-SiteFinder also returns a propensity index we have found informative about the confidence of the prediction. The PEP-SiteFinder web server is available at http://bioserv.rpbs.univ-paris-diderot.fr/PEP-SiteFinder.

The proton permeability of self-assembled polymersomes and their neuroprotection by enhancing a neuroprotective peptide across the blood-brain barrier after modification with lactoferrin

Biotherapeutics such as peptides possess strong potential for the treatment of intractable neurological disorders. However, because of their low stability and the impermeability of the blood-brain barrier (BBB), biotherapeutics are difficult to transport into brain parenchyma via intravenous injection. Herein, we present a novel poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) polymersome-based nanomedicine with self-assembled bilayers, which was functionalized with lactoferrin (Lf-POS) to facilitate the transport of a neuroprotective peptide into the brain. The apparent diffusion coefficient (D*) of H(+) through the polymersome membrane was 5.659 × 10(-26) cm(2) s(-1), while that of liposomes was 1.017 × 10(-24) cm(2) s(-1). The stability of the polymersome membrane was much higher than that of liposomes. The uptake of polymersomes by mouse brain capillary endothelial cells proved that the optimal density of lactoferrin was 101 molecules per polymersome. Fluorescence imaging indicated that Lf101-POS was effectively transferred into the brain. In pharmacokinetics, compared with transferrin-modified polymersomes and cationic bovine serum albumin-modified polymersomes, Lf-POS obtained the greatest BBB permeability surface area and percentage of injected dose per gram (%ID per g). Furthermore, Lf-POS holding S14G-humanin protected against learning and memory impairment induced by amyloid-β25-35 in rats. Western blotting revealed that the nanomedicine provided neuroprotection against over-expression of apoptotic proteins exhibiting neurofibrillary tangle pathology in neurons. The results indicated that polymersomes can be exploited as a promising non-invasive nanomedicine capable of mediating peptide therapeutic delivery and controlling the release of drugs to the central nervous system.

Characterization of N-Boc/Fmoc/Z-N'-formyl-gem-diaminoalkyl derivatives using electrospray ionization multi-stage mass spectrometry

N-Boc/Fmoc/Z-N'-formyl-gem-diaminoalkyl derivatives, intermediates particularly useful in the synthesis of partially modified retro-inverso peptides, have been characterized by both positive and negative ion electrospray ionization (ESI) ion-trap multi-stage mass spectrometry (MS(n)). The MS(2) collision induced dissociation (CID) spectra of the sodium adduct of the formamides derived from the corresponding N-Fmoc/Z-amino acids, dipeptide and tripeptide acids show the [M + Na-NH2CHO](+) ion, arising from the loss of formamide, as the base peak. Differently, the MS(2) CID spectra of [M + Na](+) ion of all the N-Boc derivatives yield the abundant [M + Na-C4H8](+) and [M + Na-Boc + H](+) ions because of the loss of isobutylene and CO2 from the Boc protecting function. Useful information on the type of amino acids and their sequence in the N-protected dipeptidyl and tripeptidyl-N'-formamides is provided by MS(2) and subsequent MS(n) experiments on the respective precursor ions. The negative ion ESI mass spectra of these oligomers show, in addition to [M-H](-), [M + HCOO](-) and [M + Cl](-) ions, the presence of in-source CID fragment ions deriving from the involvement of the N-protecting group. Furthermore, MS(n) spectra of [M + Cl](-) ion of N-protected dipeptide and tripeptide derivatives show characteristic fragmentations that are useful for determining the nature of the C-terminal gem-diamino residue. The present paper represents an initial attempt to study the ESI-MS behavior of these important intermediates and lays the groundwork for structural-based studies on more complex partially modified retro-inverso peptides.

Novel surface modified polymer-lipid hybrid nanoparticles as intranasal carriers for ropinirole hydrochloride: in vitro, ex vivo and in vivo pharmacodynamic evaluation

Here we report fabrication and evaluation of novel surface modified polymer-lipid hybrid nanoparticles (PLN) as robust carriers for intranasal delivery of ropinirole hydrochloride (ROPI HCl). Sustained release, avoidance of hepatic first pass metabolism, and improved therapeutic efficacy are the major objectives of this experiment. PLN were fabricated by emulsification-solvent diffusion technique and evaluated for physicochemical parameters, in vitro mucoadhesion, in vitro diffusion, ex vivo permeation, mucosal toxicity and stability studies. Box-Behnken experimental design approach has been employed to assess the influence of two independent variables, viz. surfactant (Pluronic F-68) and charge modifier (stearylamine) concentration on particle size, ζ-potential and entrapment efficiency of prepared PLN. Numerical optimization techniques were used for selecting optimized formulation sample, further confirmed by three dimensional response surface plots and regression equations. Results of ANOVA demonstrated the significance of suggested models. DSC and SEM analysis revealed the encapsulation of amorphous form of drug into PLN system, and spherical shape. PLN formulation had shown good retention with no severe signs of damage on integrity of nasal mucosa. Release pattern of drug-loaded sample was best fitted to zero order kinetic model with non-Fickian super case II diffusion mechanism. In vivo pharmacodynamic studies were executed to compare therapeutic efficacy of prepared nasal PLN formulation against marketed oral formulation of same drug. In summary, the PLN could be potentially used as safe and stable carrier for intranasal delivery of ROPI HCl, especially in treatment of Parkinson's disease.

Drugs from slugs. Part II--conopeptide bioengineering

The biological transformation of toxins as research probes, or as pharmaceutical drug leads, is an onerous and drawn out process. Issues regarding changes to pharmacological specificity, desired potency, and bioavailability are compounded naturally by their inherent toxicity. These often scuttle their progress as they move up the narrowing drug development pipeline. Yet one class of peptide toxins, from the genus Conus, has in many ways spearheaded the expansion of new peptide bioengineering techniques to aid peptide toxin pharmaceutical development. What has now emerged is the sequential bioengineering of new research probes and drug leads that owe their lineage to these highly potent and isoform specific peptides. Here we discuss the progressive bioengineering steps that many conopeptides have transitioned through, and specifically illustrate some of the biochemical approaches that have been established to maximize their biological research potential and pharmaceutical worth.

PEP-FOLD: an updated de novo structure prediction server for both linear and disulfide bonded cyclic peptides

In the context of the renewed interest of peptides as therapeutics, it is important to have an on-line resource for 3D structure prediction of peptides with well-defined structures in aqueous solution. We present an updated version of PEP-FOLD allowing the treatment of both linear and disulphide bonded cyclic peptides with 9-36 amino acids. The server makes possible to define disulphide bonds and any residue-residue proximity under the guidance of the biologists. Using a benchmark of 34 cyclic peptides with one, two and three disulphide bonds, the best PEP-FOLD models deviate by an average RMS of 2.75 Å from the full NMR structures. Using a benchmark of 37 linear peptides, PEP-FOLD locates lowest-energy conformations deviating by 3 Å RMS from the NMR rigid cores. The evolution of PEP-FOLD comes as a new on-line service to supersede the previous server. The server is available at: http://bioserv.rpbs.univ-paris-diderot.fr/PEP-FOLD.