Peptide based therapy for neurological disorders

: Peptides are small molecules composed of amino acids linked together by peptide bonds. The targeted action of these peptides along with their magnificent ability to reach locations in body that are complicated to access, is being considered of tremendous potential in disease modifying therapies. Synthetic as well as natural peptides like Carnosine are currently under research for treatment of neurodegenerative disorders (NDDs). Peptide based vaccines are currently under immense research for diseases like dementia. Toxicity of peptide-based drugs tfigureowards eukaryotic cells due to their increased haemolytic activity is of major concern and this is being tackled by introducing modifications into the peptide structure. Some crucial peptide inhibitors currently in use for neurodegenerative disorders include Aβ (16-20) KLVFF for Alzheimer’s disease, NAPVSIPQ (NAP) for Parkinson’s disease, towards eukaryotic cells Vasoactive Intestinal Peptides (VIP) for Huntington’s disease, Polyglutamine Binding Peptide-1(QBP1) for Dentatorubral-paiidoluysial atrophy (DRPLA). Certain peptides are involved in inhibition of mitochondrial permeability transition (MPT) that plays a prominent part in the materialization of neurodegenerative diseases, one such example of peptides being Ba-V which is obtained from Bothrops atrox snake venom. New therapeutic peptides are being identified using bioinformatics tools like high throughput screening (HTS). These tools are being used to explore the selectivity, stability, extent of immune response and toxic side effects of peptides. Apart from neurodegenerative diseases, the potential of bioactive peptides is also being tested against cancer, diabetes and microbes. This review focuses on the recent advances in peptide therapeutics and novel peptides discovered for treatment of the NDs.

Intestinal lymph as a readout of meal-induced GLP-1 release in an unrestrained rat model

Intestinal lymph supposedly provides a readout for the secretion of intestinal peptides. We here assessed how mesenteric lymph duct (MLD) lymph levels of glucagon-like peptide (GLP-1), insulin, and metabolites [glucose and triglycerides (TG)] evolve after isocaloric high- and low-fat diet (HFD and LFD) meals and how they compare with hepatic portal vein (HPV) plasma levels. Moreover, we examined the effects of intraperitoneally administered GLP-1 (1 or 10 nmol/kg) on these parameters. At 20 min after the HFD meal onset, GLP-1 levels were higher in MLD lymph than in HPV plasma. No such difference occurred with the LFD meal. Intraperitoneal injections of 10 nmol/kg GLP-1 before meals enhanced the meal-induced increases in MLD lymph and HPV plasma GLP-1 levels except for the MLD lymph levels after the HFD meal. Intraperitoneal injection of 1 nmol/kg GLP-1 only increased HPV plasma GLP-1 levels at 60 min after the HFD meal. GLP-1 injections did not increase the MLD lymph or HPV plasma GLP-1 concentrations beyond the physiological range, suggesting that intraperitoneal GLP-1 injections can recapitulate the short-term effects of endogenous GLP-1. Dipeptidyl peptidase IV (DPP-IV) activity in MLD lymph was lower than in HPV plasma, which presumably contributed to the higher levels of GLP-1 in lymph than in plasma. Insulin and glucose showed similar profiles in MLD lymph and HPV plasma, whereas TG levels were higher in lymph than in plasma. These results indicate that intestinal lymph provides a sensitive readout of intestinal peptide release and potential action, in particular when fat-rich diets are consumed.

Relationship between serum levels of VIP, but not of CGRP, and cranial autonomic parasympathetic symptoms: A study in chronic migraine patients

Background Cranial autonomic parasympathetic symptoms (CAPS) appear in at least half of migraine patients theoretically as a result of the release of peptides by the trigemino-vascular system (TVS). Cranial pain pathways become sensitised by repeated episodes of TVS activation, leading to migraine chronification. Objective The objective of this article is to correlate the presence of CAPS with serum levels of vasoactive intestinal peptides (VIP) and calcitonin gene-related peptide (CGRP). Patients and methods Patients with chronic migraine (CM) were asked about the presence – during migraine attacks – of five CAPS, which were scored from 0 to 10 by using a quantitative scale. Serum VIP and CGRP levels were determined by ELISA. Results We interviewed 87 CM patients (82 females; mean age 44.7 ± 10.6 years). Seventeen had no CAPS, while 70 reported at least one CAPS. VIP levels ranged from 20.8 to 668.2 pg/ml (mean 154.5 ± 123.2). There was a significant positive correlation between scores in the CAPS scale and VIP levels (Spearman correlation coefficient = 0.227; p = 0.035). VIP levels were significantly higher in CM patients by at least one point in the scale vs those with 0 points ( p = 0.002). Analysing symptoms individually, VIP levels were numerically higher in those patients with symptoms, though they were significantly higher only in those patients with lacrimation vs those without it ( p = 0.013). There was no significant correlation between CGRP levels and the score in the CAPS scale. Conclusions Serum VIP, but not CGRP, levels seem to reflect the rate of activation of the parasympathetic arm of the TVS in migraine.

Effect of the ingestion of the palm oil and glutamine in serum levels of GLP-1, PYY and glycemia in diabetes mellitus type 2 patients submitted to metabolic surgery

BACKGROUND: Incretins are hormones produced by the intestine and can stimulate the secretion of insulin, helping to diminish the post-prandial glycemia. The administration of an emulsion of palm oil can help in the maintenance of the weight, and can increase circulating incretins levels. Glutamine increases the concentration of incretins in diabetic people. Both can help in metabolic syndrome. AIM: To analyze the effects of ingestion of palm oil and glutamine in glycemia and in incretins in patients with diabetes submitted to surgical duodenojejunal exclusion with ileal interposition without gastrectomy. METHODS: Eleven diabetic type 2 patients were included and were operated. They were called to laboratory follow-up without eating anything between eight and 12 hours. They had there blood collected after the stimulus of the palm oil and glutamine taken in different days. For the hormonal doses were used ELISA kits. RESULTS: The glycemia showed a meaningful fall between the fast and two hours after the stimulus of the palm oil (p=0,018). With the glutamine the GLP-1 showed an increase between the fast and one hour (p=0,32), the PYY showed an important increase between the fast and one hour after the stimulus (p=0,06), the glycemia showed a meaningful fall after two hours of the administration of the stimulus (p=0,03). CONCLUSION: Palm oil and glutamine can influence intestinal peptides and glucose

Nutrient sensing and signalling by the gut

Recent advances highlight that nutrient receptors (such as T1R1/T1R3 heterodimer, Ca sensing receptor and GPR93 for amino acids and protein, GPR40, GPR41, GPR43 and GPR120 for fatty acids, T1R2/T1R3 heterodimer for monosaccharides) are expressed in the apical face of the gut and sense nutrients in the lumen. They transduce signals for the regulation of nutrient transporter expressions in the apical face. Interestingly, they are also localised in enteroendocrine cells (EEC) and mainly exert a direct control on the secretion in the lamina propria of gastro-intestinal peptides such as cholecystokinin, glucagon-like peptide-1 and peptide YY in response to energy nutrient transit and absorption in the gut. This informs central nuclei involved in the control of feeding such as the hypothalamus and nucleus of the solitary tract of the availability of these nutrients and thus triggers adaptive responses to maintain energy homoeostasis. These nutrient receptors then have a prominent position since they manage nutrient absorption and are principally the generator of the first signal of satiation mechanisms mainly transmitted to the brain by vagal afferents. Moreover, tastants are also able to elicit gut peptides secretion via chemosensory receptors expressed in EEC. Targeting these nutrient and tastant receptors in EEC may thus be helpful to promote satiation and so to fight overfeeding and its consequences.