prolyl-glycyl-proline and Disease-Models--Animal

Proline-glycine-proline (PGP) and its acetylated form (Ac-PGP) are neutrophil chemoattractants generated by collagen degradation, and they have been shown to play a role in chronic inflammatory disease. However, the mechanism for matrikine regulation in acute inflammation has not been well established. Here, we show that these peptides are actively transported from the lung by the oligopeptide transporter, PEPT2. Following intratracheal instillation of Ac-PGP in a mouse model, there was a rapid decline in concentration of the labeled peptide in the bronchoalveolar lavage (BAL) over time and redistribution to extrapulmonary sites. In vitro knockdown of the PEPT2 transporter in airway epithelia or use of a competitive inhibitor of PEPT2, cefadroxil, significantly reduced uptake of Ac-PGP. Animals that received intratracheal Ac-PGP plus cefadroxil had higher levels of Ac-PGP in BAL and lung tissue. Utilizing an acute LPS-induced lung injury model, we demonstrate that PEPT2 blockade enhanced pulmonary Ac-PGP levels and lung inflammation. We further validated this effect using clinical samples from patients with acute lung injury in coculture with airway epithelia. This is the first study to our knowledge to determine the in vitro and in vivo significance of active matrikine transport as a mechanism of modulating acute inflammation and to demonstrate that it may serve as a potential therapeutic target.

Topics: Acute Lung Injury; Animals; Anti-Bacterial Agents; Biological Transport, Active; Cefadroxil; Cells, Cultured; Chemotactic Factors; Chemotaxis, Leukocyte; COVID-19; Disease Models, Animal; Extracellular Matrix; Extracellular Matrix Proteins; Humans; Inflammation; Mice; Oligopeptides; Proline; Symporters

It is anticipated that bioactive fragments of the extracellular matrix (matrikines) can influence the development and progression of chronic diseases. The enzyme leukotriene A

Topics: Airway Remodeling; Airway Resistance; Animals; Asthma; Bronchi; Cell Count; Disease Models, Animal; Epithelial Cells; Epoxide Hydrolases; Extracellular Matrix; Humans; Hypersensitivity; Inflammation; Inflammation Mediators; Mice, Inbred C57BL; Mucus; Neutrophils; Oligopeptides; Proline; Pyroglyphidae; Respiratory Hypersensitivity; Sputum; T-Lymphocytes, Helper-Inducer

Human endothelial progenitor cells (hEPCs) are promising therapeutic resources for wound repair through stimulating neovascularization. However, the hEPCs-based cell therapy has been hampered by poor engraftment of transplanted cells. In this study, we explored the effects of N-acetylated Proline-Glycine-Proline (Ac-PGP), a degradation product of collagen, on hEPC-mediated cutaneous wound healing and neovascularization. Treatment of hEPCs with Ac-PGP increased migration, proliferation, and tube-forming activity of hEPCs in vitro. Knockdown of CXCR2 expression in hEPCs abrogated the stimulatory effects of Ac-PGP on migration and tube formation. In a cutaneous wound healing model of rats and mice, topical application of Ac-PGP accelerated cutaneous wound healing with promotion of neovascularization. The positive effects of Ac-PGP on wound healing and neovascularization were blocked in CXCR2 knockout mice. In nude mice, the individual application of Ac-PGP treatment or hEPC injection accelerated wound healing by increasing neovascularization. Moreover, the combination of Ac-PGP treatment and hEPC injection further stimulated wound healing and neovascularization. Topical administration of Ac-PGP onto wound bed stimulated migration and engraftment of transplanted hEPCs into cutaneous dermal wounds. Therefore, these results suggest novel applications of Ac-PGP in promoting wound healing and augmenting the therapeutic efficacy of hEPCs.

Topics: Administration, Topical; Animals; Cell Movement; Cell Proliferation; Disease Models, Animal; Endothelial Progenitor Cells; Mice, Knockout; Mice, Nude; Neovascularization, Physiologic; Oligopeptides; Proline; Rats; Receptors, Interleukin-8B; Treatment Outcome; Wound Healing; Wounds and Injuries

Brain stroke continues to claim the lives of million people every year. To build the effective strategies for stroke treatment it is necessary to understand the neuroprotective mechanisms that are able to prevent the ischemic injury. Consisting of the ACTH

Topics: Adrenocorticotropic Hormone; Animals; Antigen Presentation; Brain Ischemia; Disease Models, Animal; Gene Expression Profiling; Genes, Immunoglobulin Heavy Chain; Immunoglobulin Heavy Chains; Male; Middle Cerebral Artery; Neuroprotective Agents; Oligopeptides; Peptide Fragments; Proline; Rats; Rats, Wistar; Stress, Physiological; Transcriptome

There is increasing evidence that the neutrophil chemoattractant proline-glycine-proline (PGP), derived from the breakdown of the extracellular matrix, plays an important role in neutrophil recruitment to the lung. PGP formation is a multistep process involving neutrophils, metalloproteinases (MMPs), and prolyl endopeptidase (PE). This cascade of events is now investigated in the development of lung emphysema. A/J mice were whole body exposed to cigarette smoke for 20 wk. After 20 wk or 8 wk after smoking cessation, animals were killed, and bronchoalveolar lavage fluid and lung tissue were collected to analyze the neutrophilic airway inflammation, the MMP-8 and MMP-9 levels, the PE activity, and the PGP levels. Lung tissue degradation was assessed by measuring the mean linear intercept. Additionally, we investigated the effect of the peptide L-arginine-threonine-arginine (RTR), which binds to PGP sequences, on the smoke-induced neutrophil influx in the lung after 5 days of smoke exposure. Neutrophilic airway inflammation was induced by cigarette smoke exposure. MMP-8 and MMP-9 levels, PE activity, and PGP levels were elevated in the lungs of cigarette smoke-exposed mice. PE was highly expressed in epithelial and inflammatory cells (macrophages and neutrophils) in lung tissue of cigarette smoke-exposed mice. After smoking cessation, the neutrophil influx, the MMP-8 and MMP-9 levels, the PE activity, and the PGP levels were decreased or reduced to normal levels. Moreover, RTR inhibited the smoke-induced neutrophil influx in the lung after 5 days' smoke exposure. In the present murine model of cigarette smoke-induced lung emphysema, it is demonstrated for the first time that all relevant components (neutrophils, MMP-8, MMP-9, PE) involved in PGP formation from collagen are upregulated in the airways. Together with MMPs, PE may play an important role in the formation of PGP and thus in the pathophysiology of lung emphysema.

Topics: Animals; Bronchoalveolar Lavage Fluid; Collagen; Disease Models, Animal; Female; Lung; Male; Matrix Metalloproteinase 8; Matrix Metalloproteinase 9; Mice; Mice, Inbred A; Mice, Inbred BALB C; Neutrophils; Nicotiana; Oligopeptides; Proline; Prolyl Oligopeptidases; Pulmonary Emphysema; Serine Endopeptidases; Smoke; Smoking

Acetylated Pro-Gly-Pro (Ac-PGP) is an endogenous degradation product of extracellular collagen that binds to leukocyte-expressed chemoattractant receptor CXCR2. Although certain agents that block CXCR2-mediated signaling protect against experimental sepsis, the roles of Ac-PGP and CXCR2 in sepsis are unclear.. To investigate the role of Ac-PGP and its receptor, CXCR2, in murine models of cecal ligation and puncture (CLP)-induced polymicrobial sepsis and organ injury.. The impact of in vivo Ac-PGP treatment on animal survival after induction of experimental sepsis was assessed. Vital organ inflammation and immune cell apoptosis were evaluated by histology, and the modulation of proinflammatory cytokine production and bactericidal activity by Ac-PGP in mouse and human blood leukocytes was measured.. The activation of CXCR2 by tripeptide agonist Ac-PGP dramatically improved survival in three experimental sepsis models. Ac-PGP elicited bactericidal activity via the generation of hydrogen peroxide, inhibited lung inflammation, and reduced immune cell apoptosis. Fluorescein isothiocyanate-labeled PGP bound directly to CXCR2, and the protective effect of Ac-PGP in sepsis was abolished in CXCR2-deficient mice. Ac-PGP treatment enhanced the production of type 1 cytokines (IFN-γ and IL-12) but inhibited the production of proinflammatory cytokines (tumor necrosis factor [TNF]-α, IL-1β, and IL-6) in vivo. In vitro, Ac-PGP directly increased IFN-γ production and decreased the LPS-stimulated production of TNF-α by mouse splenocytes and human leukocytes. Furthermore, direct treatment of LPS-stimulated splenocytes with IFN-γ resulted in diminished secretion of TNF-α and IL-6.. CXCR2 and Ac-PGP are thus novel target and starting molecules, respectively, for the development of therapeutic agents against sepsis.

Topics: Animals; Disease Models, Animal; Humans; Male; Mice; Mice, Inbred C57BL; Oligopeptides; Proline; Receptors, Interleukin-8B; Sepsis

Neuroinvasion of the enteric nervous system by prions is an important step in dissemination to the brain, yet very little is known about the basic process of enteric neuroinvasion. Using an alimentary model of neonatal disease transmission, neuroinvasion by scrapie prions in the ileum of lambs was detected by immunohistochemical staining for the disease-associated form of the prion protein, PrPSc. Odds ratios (OR) were determined for the frequency of PrPSc staining within enteric somata categorized by plexus location (myenteric, submucosal) and neurochemical staining (PGP 9.5, neural nitric oxide synthase, somatostatin, substance P, and vasoactive intestinal polypeptide). PrPSc was observed in 4.48 +/- 4.26% of myenteric neurons and 2.57 +/- 1.82% of submucosal neurons in five lambs aged 208-226 days but not in a lamb aged 138 days. The relative frequency of PrPSc within enteric somata was interdependent on plexus location and neurochemical type. Interestingly, PrPSc was observed more frequently within myenteric neurons than in submucosal neurons (PGP 9.5; OR = 1.72, 95% confidence interval = 1.21-2.44), and was observed within the myenteric plexus approximately 4x (2.16-6.94) more frequently in somatostatin neurons than in the general neural population stained by PGP 9.5. Nerve fibers stained for somatostatin were present in the mucosa and near PrPSc staining within Peyer's patches. The results suggest that somatostatin-expressing enteric neurons, with fiber projections near Peyer's patches, but with somata present in greatest proportion within the myenteric plexus, are an early target for neuroinvasion by scrapie prions and could serve an important role in neural dissemination.

Topics: Animals; Cell Count; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Ileum; Myenteric Plexus; Nerve Tissue Proteins; Neurons; Odds Ratio; Oligopeptides; Prions; Proline; Scrapie; Sheep; Somatostatin; Time Factors; Vasoactive Intestinal Peptide

Proline-glycine-proline (PGP) peptides have been identified as inflammatory mediators initiating neutrophil invasion into alkali-injured cornea. The complementary peptide, arginine-threonine-arginine (RTR), has been shown to bind to the PGP sequence and impede neutrophil infiltration. A prior study showed that L-RTR tetramer and D-RTR tetramer, used alternately (14 times a day), resulted in significantly reduced incidences of corneal ulceration and severity. The purpose of this experiment is to determine the effectiveness of both tetramers, used separately, compared with control.. Rabbit corneas were exposed to 1 N NaOH for 35 seconds. Sixteen animals were randomly assigned to each of 3 groups: 1) phosphate-buffered saline (PBS), 2) 1.5 mM L-RTR, or 3) 800 microM D-RTR. One drop of each was administered hourly (14 times a day) for 36 days. Additional studies were done to assess neutrophil infiltration into corneas with and without RTR treatment.. The severity of corneal ulceration in both RTR groups was statistically significantly different from the 21st day of the experiment to the end. As a result of ulcers healing in the L-RTR group, there was a statistically significant reduction in the number of ulcers beginning on day 22 versus control. Although there was healing in the D-RTR group, the incidence of ulcers was not significantly different from control or L-RTR. Morphometric analysis revealed decreased neutrophil (PMN) invasion with RTR treatment compared with PBS control.. Binding of the PGP molecules by RTR tetramer seems to deprive the cornea of this neutrophilic chemotactic stimulus, leading to a reduction in the severity and incidence of corneal ulceration.

Topics: Animals; Burns, Chemical; Chemotactic Factors; Chemotaxis, Leukocyte; Cornea; Corneal Ulcer; Disease Models, Animal; Eye Burns; Female; Humans; Isomerism; Male; Neutrophils; Oligopeptides; Proline; Rabbits; Sodium Hydroxide

We investigated the impact of PGP on ethanol-induced mucosal damages and on the development of acetate gastric ulcers in rats for two ways of introduction--intraperitoneal and intragastric. PGP in the dozes of 0.1, 1 and 10 mg/kg authentically reduced the area of ethanol-induced mucosal damages at intraperitoneal introduction by 43, 70 and 65%, respectively; at intragastric introduction--by 64, 66 and 83%, respectively. Intraperitoneal introduction of PGP in the doze of 1 mg/kg and its intragastric introduction in the doze of 0.1 mg/kg equally reduced the development of acetate gastric ulcers by 73%. Thus, irrespective of the way of its introduction (intraperitoneal or intragastric) and its doze, PGP has a significant protective anti-ulcerous effect and reduces the development of acetate gastric ulcers in rats.

Topics: Acetic Acid; Administration, Oral; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Ethanol; Gastric Mucosa; Injections, Intraperitoneal; Male; Oligopeptides; Proline; Protective Agents; Rats; Stomach Ulcer

Stress increased secretory activity of mast cells in the mesentery and subcutaneous fat of rats. Intraperitoneal injection of Semax and prolyl-glycyl-proline in doses of 0.05 and 1 mg/kg, respectively, 1 h before stress abolished this effect. The test preparations did not modulate secretory activity of mast cells in unstressed animals. Semax and prolyl-glycyl-proline in vitro prevented activation of mast cells with synacten and acetylcholine. The stabilizing effect of peptides on mast cells probably determines their antiulcer activity.

Topics: Acetylcholine; Adrenocorticotropic Hormone; Animals; Animals, Outbred Strains; Disease Models, Animal; Injections, Intraperitoneal; Male; Mast Cells; Mesentery; Oligopeptides; Peptide Fragments; Proline; Rats; Stress, Psychological