Investigation of Kisspeptin Role in Experimental Kidney Ischemia/Reperfusion Injury

Introduction: Kisspeptin is biologically active peptide encoded by the KISS1 gene that is structurally found in the kidney tubule, collecting duct and vein smooth muscle cells.&nbsp; &nbsp; Aim: We aimed to investigate the role of kisspeptin in kidney function and renal pathophysiology in experimental kidney ischemia/reperfusion (I/R) injury.&nbsp; &nbsp; Materials and methods: Male Spraque-Dawley rats were divided into control and I/R groups (n=8). Both kidney vessels of I/R group rats were clamped and subjected to ischemia for 60 minutes and reperfusion for 48 hours. After the reperfusion period blood samples and kidney tissue were collected under anesthesia.&nbsp; &nbsp; Results: Levels of urea, creatinine (p<0.01) in serum, Kim-1 in urine (p<0.05) were increased, creatinine clearance, aldosterone and ANG II levels in serum were decreased in the I/R group compared with the Control group (p<0.05). Kidney kisspeptin levels decreased and urine kisspeptin levels increased (p<0.05).&nbsp; &nbsp; Conclusions: The present study has shown that the levels of kisspeptin change in kidney damage and thus the kisspeptin may play a role in the regulation of renal function and in the pathophysiology of acute kidney injury.

Glucose homeostasis is impaired in mice deficient for the neuropeptide 26RFa (QRFP)

Introduction26RFa (QRFP) is a biologically active peptide that has been found to control feeding behaviour by stimulating food intake, and to regulate glucose homeostasis by acting as an incretin. The aim of the present study was thus to investigate the impact of 26RFa gene knockout on the regulation of energy and glucose metabolism.Research design and methods26RFa mutant mice were generated by homologous recombination, in which the entire coding region of prepro-26RFa was replaced by the iCre sequence. Energy and glucose metabolism was evaluated through measurement of complementary parameters. Morphological and physiological alterations of the pancreatic islets were also investigated.ResultsOur data do not reveal significant alteration of energy metabolism in the 26RFa-deficient mice except the occurrence of an increased basal metabolic rate. By contrast, 26RFa mutant mice exhibit an altered glycemic phenotype with an increased hyperglycemia after a glucose challenge associated with an impaired insulin production, and an elevated hepatic glucose production. 2D and 3D immunohistochemical experiments indicate that the insulin content of pancreatic β cells is much lower in the 26RFa-/- mice as compared to the wild-type littermates.ConclusionDisruption of the 26RFa gene induces substantial alteration in the regulation of glucose homeostasis with, in particular, a deficit in insulin production by the pancreatic islets. These findings further support the notion that 26RFa is an important regulator of glucose homeostasis.Significance of this studyWhat is already known about this subject?26RFa is a biologically active peptide produced in abundance in the gut and the pancreas. 26RFa has been found to regulate glucose homeostasis by acting as an incretin and by increasing insulin sensitivity.What are the new findings?Disruption of the 26RFa gene induces substantial alteration in the regulation of glucose homeostasis with, in particular, a deficit in insulin production by the pancreatic islets, assessing therefore the notion that 26RFa is an important regulator of glucose homeostasis.How might these results change the focus of research or clinical practice?Identification of a novel actor in the regulation of glucose homeostasis is crucial to better understand the general control of glucose metabolism in physiological and pathophysiological conditions, and opens new fields of investigation to develop innovative drugs to treat diabetes mellitus.

Thermally-Responsive Loading and Release of Elastin-Like Polypeptides from Contact Lenses

Contact lenses are widely prescribed for vision correction, and as such they are an attractive platform for drug delivery to the anterior segment of the eye. This manuscript explores a novel strategy to drive the reversible adsorption of peptide-based therapeutics using commercially available contact lenses. To accomplish this, thermo-sensitive elastin-like polypeptides (ELPs) alone or tagged with a candidate ocular therapeutic were characterized. For the first time, this manuscript demonstrates that Proclear CompatiblesTM contact lenses are a suitable platform for ELP adsorption. Two rhodamine-labelled ELPs, V96 (thermo-sensitive) and S96 (thermo-insensitive), were employed to test temperature-dependent association to the contact lenses. During long-term release into solution, ELP coacervation significantly modulated the release profile whereby more than 80% of loaded V96 retained with a terminal half-life of ~4 months, which was only 1–4 days under solubilizing conditions. A selected ocular therapeutic candidate lacritin-V96 fusion (LV96), either free or lens-bound LV96, was successfully transferred to HCE-T cells. These data suggest that ELPs may be useful to control loading or release from certain formulations of contact lenses and present a potential for this platform to deliver a biologically active peptide to the ocular surface via contact lenses.

Look Closely, the Beautiful May Be Small: Precursor-Derived Peptides in Plants

During the past decade, a flurry of research focusing on the role of peptides as short- and long-distance signaling molecules in plant cell communication has been undertaken. Here, we focus on peptides derived from nonfunctional precursors, and we address several key questions regarding peptide signaling. We provide an overview of the regulatory steps involved in producing a biologically active peptide ligand that can bind its corresponding receptor(s) and discuss how this binding and subsequent activation lead to specific cellular outputs. We discuss different experimental approaches that can be used to match peptide ligands with their receptors. Lastly, we explore how peptides evolved from basic signaling units regulating essential processes in plants to more complex signaling systems as new adaptive traits developed and how nonplant organisms exploit this signaling machinery by producing peptide mimics.

Apelin as a nociceptive processes regulator

The aim of this paper is to characterize the biologically active peptide – apelin, and its previously identified APJ receptor. Gene and protein expression of apelin/APJ system has been detected in many tissues and organs of the body such as: adipose tissue, stomach, liver, pancreas, heart, lungs, uterus, ovaries, brain or spinal cord. The results of recently published papers show the role of the apelin/APJ system in numerous physiological and pathological processes in the body, including nociceptive processes. This paper discusses the physiological and molecular mechanisms of the apelin/APJ system, with particular emphasis on its role in inflammatory and neuropathic pain, as well as in the effectiveness of opioids. In addition, the clinical aspect of this system in pain processes is presented.

New issues on measurement of B-type natriuretic peptides

The measurement of the active hormone of B-type natriuretic peptide (BNP) system actually has several analytical limitations and difficulties in clinical interpretations compared to that of inactive peptide N-terminal proBNP (NT-proBNP) because of the different biochemical and pathophysiological characteristics of two peptides and quality specifications of commercial immunoassay methods used for their measurement. Because of the better analytical characteristics of NT-proBNP immunoassays and the easier pathophysiological and clinical interpretations of variations of NT-proBNP levels in patients with heart failure (HF), some authors claimed to measure the inactive peptide NT-proBNP instead of the active hormone BNP for management of HF patients. The measurement of the active peptide hormone BNP gives different, but complementary, pathophysiological and clinical information compared to inactive NT-proBNP. In particular, the setup of new more sensitive and specific assays for the biologically active peptide BNP

Influence of soybean bioactive peptides on growth performance, nutrient utilisation, digestive tract development and intestinal histology in broilers

SummaryA biologically active peptide derived from soybeans by enzymatic hydrolysis was evaluated for its potential benefits on chicken growth performance, apparent ileal nutrient digestibility and intestinal histology in young broilers. Seven broiler starter diets, based on maize and soybean meal, were formulated to contain 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg of a commercial soybean bioactive peptide (SBP) product (Fortide, Chengdu Mytech Biotech Co. Ltd., Chengdu, Sichuan, China). All diets were equivalent in respect of energy density, and digestible protein, amino acids, and other nutrients. A total of 336, one-day-old male broilers (Ross 308) were allocated to 42 cages (eight birds/cage), which were randomly assigned to the six dietary treatments. There was no significant effect of SBP on weight gain and feed intake of the birds. A significant (P < 0.01) effect of SBP was observed for FCR. Inclusion of 1.0, 2.0, 3.0 and 4.0 g SBP/kg of feed resulted in similar FCR values to the diet with no SBP, addition of SBP to the diets at 5.0 and 6.0 g/kg of feed resulted in lower (P < 0.05) FCR compared to the diet with no SBP. Inclusion of SBP had no effect (P > 0.05) on apparent ileal digestibility of nutrients and energy utilisation. Though not statistically significant, SBP inclusion, regardless of level, resulted in 5.7% and 6.3% increases in digestibility of dry matter and nitrogen, respectively. Birds receiving no SBP had the shortest villi and those fed SBP at 3.0 and 6.0 g/kg of feed tended (P = 0.075) to have the greatest villus height. The current findings suggested that including SBP in broiler diets may benefit production through improving feed efficiency, and, to some extent, nutrient digestion and intestinal histology parameters.