Peptides (v.93, #C)

Lack of effect of prolonged treatment with liraglutide on cardiac remodeling in rats after acute myocardial infarction by Kasper Kyhl; Jacob Lønborg; Bolette Hartmann; Hannelouise Kissow; Steen Seier Poulsen; Henrik El Ali; Andreas Kjær; Flemming Dela; Thomas Engstrøm; Marek Treiman (1-12).
Following the acute phase of a myocardial infarction, a set of structural and functional changes evolves in the myocardium, collectively referred to as cardiac remodeling. This complex set of processes, including interstitial fibrosis, inflammation, myocyte hypertrophy and apoptosis may progress to heart failure. Analogs of the incretin hormone glucagon-like peptide 1 (GLP-1) have shown some promise as cardioprotective agents. We hypothesized that a long-acting GLP-1 analog liraglutide would ameliorate cardiac remodeling over the course of 4 weeks in a rat model of non-reperfused myocardial infarction. In 134 male Sprague Dawley rats myocardial infarctions were induced by ligation of the left anterior descending coronary artery. Rats were randomized to either subcutaneous injection of placebo or 0.3 mg liraglutide once daily. Cardiac magnetic resonance imaging was performed after 4 weeks. Histology of the infarcted and remote non-infarcted myocardium, selected molecular remodeling markers and mitochondrial respiration in fibers of remote non-infarcted myocardium were analyzed. Left ventricular end diastolic volume increased in the infarcted hearts by 62% (from 0.58 ± 0.03 mL to 0.95 ± 0.07 mL, P < 0.05) compared to sham operated hearts and left ventricle ejection fraction decreased by 37% (63 ± 1%–40 ± 3%, P < 0.05). Increased interstitial fibrosis and phosphorylation of p38 Mitogen Activated Protein Kinase were observed in the non-infarct regions. Mitochondrial fatty acid oxidation was impaired. Liraglutide did not affect any of these alterations. Four-week treatment with liraglutide did not affect cardiac remodeling following a non-reperfused myocardial infarction, as assessed by cardiac magnetic resonance imaging, histological and molecular analysis and measurements of mitochondrial respiration.
Keywords: GLP-1 receptor analog; Acute myocardial infarction; Cardiac remodeling; Heart failure; Liraglutide; Cardiac magnetic resonance;

Despite its limited ability to cross the blood-brain barrier, peripherally administered oxytocin (OT) acutely decreases food intake, most likely via the brainstem and hypothalamic mechanisms. Studies performed to date have focused mainly on the effects of subcutaneous or intraperitoneal OT on the consumption of only solid calorie-dense diets (either standard or high-fat), whereas it is unknown whether, similarly to central OT, peripherally administered peptide reduces intake of calorie-dilute and non-caloric palatable solutions. In this project, we established that 0.1 μg/kg intravenous (IV) OT is the lowest anorexigenic dose, decreasing deprivation-induced standard chow intake by ca. 40% in rats and its effect does not stem from aversion. We then used this dose in paradigms in which effects of centrally acting OT ligands on consumption of palatable solutions had been previously reported. We found that IV OT did not change episodic intake of individually presented palatable solutions containing 10% sucrose, 0.1% saccharin, combined 10% sucrose-0.1% saccharin or 4.1%. Intralipid and it failed to affect daily scheduled consumption of a sucrose solution in non-deprived rats. In a two-bottle choice test, IV OT did not shift animals’ preference from sucrose to Intralipid. Finally, OT injected IV prior to the simultaneous presentation chow and a sucrose solution in food-deprived rats significantly decreased chow intake, whereas sugar water consumption remained unchanged. We conclude that IV OT reduces deprivation-induced chow intake without causing aversion, but the dose effective in decreasing energy-driven consumption of high-calorie food fails to affect consumption of palatable calorie-dilute solutions.
Keywords: Oxytocin; Appetite; CTA;

A randomized cross-over study of the effects of macronutrient composition and meal frequency on GLP-1, ghrelin and energy expenditure in humans by Simon Ingves; Nathalie Vilhelmsson; Edvin Ström; Mats Fredrikson; Hans Guldbrand; Fredrik H. Nystrom (20-26).
Little is known about human postprandial increase of energy expenditure and satiety-associated hormones in relation to both meal frequency and macronutrient composition.Randomized cross-over study with four conditions for each participant.Seven men and seven women (mean age 23 ± 1.5 years) were randomly assigned to the order of intake of a 750 kcal drink with the same protein content while having either 20 energy-percent (E%) or 55 E% from carbohydrates and the remaining energy from fat. Participants were also randomized to consume the drinks as one large beverage or as five 150 kcal portions every 30 min, starting in the fasting state in the morning. Energy expenditure (EE) was determined every 30 min by indirect calorimetry. Hormonal responses and suppression of hunger (by visual-analogue scales) were also studied. A p < 0.013 was considered statistically significant following Bonferroni-correction.The area under the curve (AUC) for EE was higher during the 2.5 h after the high-carbohydrate drinks (p = 0.005 by Wilcoxon) and also after ingesting one drink compared with five (p = 0.004). AUC for serum active GLP-1 was higher after single drinks compared with five beverages (p = 0.002). Although GLP-1 levels remained particularly high at the end of the test during the low-carbohydrate meals, the AUC did not differ compared with the high-carbohydrate occasions (low-carbohydrate: 58.9 ± 18 pg/ml/h, high-carbohydrate: 45.2 ± 16 pg/ml/h, p = 0.028). Hunger sensations were suppressed more after single beverages compared with five small drinks (p = 0.009).We found higher EE during 2.5 h following one large drink compared with five smaller beverages. Since hunger was also suppressed more efficiently, and serum GLP-1 levels were higher after one compared with five smaller drinks, our findings do not support nibbling to avoid hunger or to keep up EE from morning to noon.
Keywords: Ghrelin; GLP-1; Hunger; Indirect calorimetry; Low-carbohydrate; Meal frequency;

Low plasma leptin level at admission predicts delirium in critically ill patients: A prospective cohort study by Guicheng Li; Xiaobao Lei; Chenmu Ai; Tao Li; Zhongqing Chen (27-32).
The pathophysiology of delirium remains poorly understood. Low leptin level has been associated with features leading to delirium such as dysregulated immune functions and loss of neuroprotective effects. The purpose of the present study was to investigate the relationship between plasma leptin level at intensive care unit (ICU) entry and subsequent occurrence of delirium in critically ill patients. This single-center prospective cohort study in China allocated 336 critically ill patients admitted to ICU between 05/2015 and 05/2016 into a delirium group (n = 102) and non-delirium group (n = 234) based on whether delirium occurred during their stay at the ICU. Patients were examined at least twice daily and delirium was diagnosed using the Confusion Assessment Method for the ICU (CAM-ICU). Blood samples were obtained after ICU entry. Plasma leptin concentrations were measured by ELISA. Delirium occurred in 30.4% (102/336) of patients. Patients who developed delirium showed significantly lower leptin level at ICU entry than those who did not (6.1 ± 3.2 vs. 9.2 ± 5.9 ng/mL; P  < 0.001). Low plasma leptin level at ICU entry was independently associated with subsequent occurrence of delirium (OR, 0.865; 95%CI, 0.802–0.934; P  < 0.001). Other independent risk factors for delirium included increasing age (OR, 1.050; 95%CI, 1.020–1.080; P  = 0.001) and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score (OR, 1.148; 95%CI, 1.092–1.208; P  < 0.001). Patients who developed delirium had a prolonged duration of ICU stay and higher mortality. Low plasma leptin level at ICU entry was associated with the occurrence of delirium in critically ill patients.
Keywords: Delirium; Leptin; Intensive care; Critically ill;

Antimicrobial peptide KSL-W promotes gingival fibroblast healing properties in vitro by Hyun-Jin Park; Mabrouka Salem; Abdelhabib Semlali; Kai P Leung; Mahmoud Rouabhia (33-43).
We investigated the effect of synthetic antimicrobial decapeptide KSL-W (KKVVFWVKFK) on normal human gingival fibroblast growth, migration, collagen gel contraction, and α-smooth muscle actin protein expression. Results show that in addition to promoting fibroblast adhesion by increasing F-actin production, peptide KSL-W promoted cell growth by increasing the S and G2/M cell cycle phases, and enhanced the secretion of metalloproteinase (MMP)-1 and MMP-2 by upregulating MMP inhibitors, such as tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 in fibroblasts. An in vitro wound healing assay confirmed that peptide KSL-W promoted fibroblast migration and contraction of a collagen gel matrix. We also demonstrated a high expression of α-smooth muscle actin by gingival fibroblasts being exposed to KSL-W. This work shows that peptide KSL-W enhances gingival fibroblast growth, migration, and metalloproteinase secretion, and the expression of α-smooth muscle actin, thus promoting wound healing.
Keywords: Antimicrobial peptide; KSL-W; Gingival fibroblasts; F-actin; Cell migration; Cell cycle; α-SMA;

The frog skin host-defense peptide frenatin 2.1S enhances recruitment, activation and tumoricidal capacity of NK cells by Jelena M. Pantic; Ivan P. Jovanovic; Gordana D. Radosavljevic; Nevena M. Gajovic; Nebojsa N. Arsenijevic; J. Michael Conlon; Miodrag L. Lukic (44-50).
Frog skin is a source of peptides with various biological properties. Frenatin 2.1S, derived from norepinephrine-stimulated skin secretions of the Orinoco lime tree frog Sphaenorhynchus lacteus, exhibits immunostimulatory effects as demonstrated by the promotion of proinflammatory phenotypes of mononuclear cells in mouse peritoneal cavity and spleen. The aim of this study was to identify the populations of host cells sensitive to the action of frenatin 2.1S in vivo and to study its effects on their functional antitumor capacity. A single injection of frenatin 2.1S (100 μg) in BALB/c mice increased the presence of peritoneal CD11c+ dendritic cells and CD3+ T cells 24 h after administration and there was a significant increase in the number of IL-17 and CXCR3 expressing inflammatory T cells. Frenatin 2.1S treatment also increased the number of TNF-α expressing F4/80+ proinflammatory M1 macrophages. The most striking finding of the study is the marked increase of the number of peritoneal natural killer (NK) cells following frenatin 2.1S injection. Further, frenatin 2.1S administration led to activation of NK cells as evaluated by increased expression of NKG2D, FasL, CD69 and CD107a. The increased ratio of interferon-γ vs. IL-10 producing NK cells is further indication of the proinflammatory action of frenatin 2.1S. Peptide treatment enhanced the tumoricidal action of peritoneal NK cells on 4T1 mouse mammary carcinoma cells as revealed by the real-time automated monitoring of cell status. Our data demonstrate that frenatin 2.1S promotes activation and cytotoxic capacity of NK cells and should be regarded as a candidate for antitumor immunotherapy.
Keywords: Frenatin 2.1S; NK cell; Antimicrobial peptide; Immunomodulatory peptide; Cytotoxicity;

Neuropeptides predicted from the transcriptome analysis of the gray garden slug Deroceras reticulatum by Seung-Joon Ahn; Ruth Martin; Sujaya Rao; Man-Yeon Choi (51-65).
The gray garden slug, Deroceras reticulatum (Gastropoda: Pulmonata), is one of the most common terrestrial molluscs. Research for this slug has focused mainly on its ecology, biology, and management due to the severe damage it causes on a wide range of vegetables and field crops. However, little is known about neuropeptides and hormonal signalings. This study, therefore, aimed to establish the transcriptome of D. reticulatum and to identify a comprehensive repertoire of neuropeptides in this slug. Illumina high-throughput sequencing of the whole body transcriptome of D. reticulatum generated a total of 5.9 billion raw paired-end reads. De novo assembly by Trinity resulted in 143,575 transcripts and further filtration selected 120,553 unigenes. Gene Ontology (GO) terms were assigned to 30,588 unigenes, composed of biological processes (36.9%), cellular components (30.2%) and molecular functions (32.9%). Functional annotation by BLASTx revealed 39,987 unigenes with hits, which were further categorized into important functional groups based on sequence abundance. Neuropeptides, ion channels, ribosomal proteins, G protein-coupled receptors, detoxification, immunity and cytoskeleton-related sequences were dominant among the transcripts. BLAST searches and PCR amplification were used to identify 65 putative neuropeptide precursor genes from the D. reticulatum transcriptome, which include achatin, AKH, allatostatin A, B and C, allatotropin, APGWamide, CCAP, cerebrin, conopressin, cysteine-knot protein hormones (bursicon alpha/beta and GPA2/GPB5), elevenin, FCAP, FFamide, FVamide (enterin, fulicin, MIP and PRQFVamide), GGNG, GnRH, insulin, NdWFamide, NKY, PKYMDT, PRXamide (myomodulin, pleurin and sCAP), RFamide (CCK/SK, FMRFamide, FxRIamide, LFRFamide, luqin and NPF), and tachykinin. Over 330 putative peptides were encoded by these precursors. Comparative analysis among different molluscan species clearly revealed that, while D. reticulatum neuropeptide sequences are conserved in Mollusca, there are also some unique features distinct from other members of this species. This is the first transcriptome-wide report of neuropeptides in terrestrial slugs. Our results provide comprehensive transcriptome data of the gray garden slug, with a more detailed focus on the rich repertoire of putative neuropeptide sequences, laying the foundation for molecular studies in this terrestrial slug pest.
Keywords: Deroceras reticulatum; Gray garden slug; Neuropeptide; Transcriptome;