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An engineered cyclic peptide alleviates symptoms of inflammation in a murine model of inflammatory bowel disease.

ABSTRACT: Inflammatory bowel diseases (IBDs) are a set of complex and debilitating diseases for which there is no satisfactory treatment. Recent studies have shown that small peptides show promise for reducing inflammation in models of IBD. However, these small peptides are likely to be unstable and rapidly cleared from the circulation, and therefore, if not modified for better stability, represent non-viable drug leads. We hypothesized that improving the stability of these peptides by grafting them into a stable cyclic peptide scaffold may enhance their therapeutic potential. Using this approach, we have designed a novel cyclic peptide that comprises a small bioactive peptide from the annexin A1 protein grafted into a sunflower trypsin inhibitor cyclic scaffold. We used native chemical ligation to synthesize the grafted cyclic peptide. This engineered cyclic peptide maintained the overall fold of the naturally occurring cyclic peptide, was more effective at reducing inflammation in a mouse model of acute colitis than the bioactive peptide alone, and showed enhanced stability in human serum. Our findings suggest that the use of cyclic peptides as structural backbones offers a promising approach for the treatment of IBD and potentially other chronic inflammatory conditions.

SUBMITTER: Cobos Caceres C

PROVIDER: S-EPMC5473231 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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An engineered cyclic peptide alleviates symptoms of inflammation in a murine model of inflammatory bowel disease.

Cobos Caceres Claudia C Bansal Paramjit S PS Navarro Severine S Wilson David D Don Laurianne L Giacomin Paul P Loukas Alex A Daly Norelle L NL

The Journal of biological chemistry 20170504 24

Inflammatory bowel diseases (IBDs) are a set of complex and debilitating diseases for which there is no satisfactory treatment. Recent studies have shown that small peptides show promise for reducing inflammation in models of IBD. However, these small peptides are likely to be unstable and rapidly cleared from the circulation, and therefore, if not modified for better stability, represent non-viable drug leads. We hypothesized that improving the stability of these peptides by grafting them into ...[more]

PMID: 28473469

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Project description:UnlabelledIn adult inflammatory bowel disease (IBD) patients, there is a strong discrepancy between symptoms and biomarkers of inflammation. Data on pediatric IBD patients are conflicting. Therefore, we aimed to investigate the relationship between clinical symptoms and biomarkers of inflammation in pediatric IBD. Patients aged <18 years with previously diagnosed Crohn's disease (CD) or ulcerative colitis (UC) were included. Clinical disease activity was determined using the abbreviated Pediatric CD Activity Index (aPCDAI) or Pediatric UC Activity Index (PUCAI). Biochemical disease activity was assessed using fecal calprotectin (FC) and C-reactive protein (CRP). In total, 127 patients (62 male; median age 14.9 years) were included (82 CD, 45 UC). FC correlated weakly with total aPCDAI score (r s = 0.32; 95 % CI 0.12-0.51; p = 0.003) and total PUCAI score (r s = 0.36; 95 % CI 0.07-0.62; p = 0.015). Only aPCDAI components abdominal examination and perirectal disease and PUCAI component activity level had a significant correlation with levels of FC. CRP correlated weakly with total aPCDAI score (r s = 0.28; 95 % CI 0.05-0.46; p = 0.012) and aPCDAI components abdominal examination and activity level. No significant correlation was observed between CRP and total PUCAI score (r s = 0.01; 95 % CI -0.34-0.29; p = 0.961) or individual PUCAI components.ConclusionThere is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.What is known• A substantial proportion of asymptomatic pediatric inflammatory bowel disease (IBD) patients have elevated biomarkers of inflammation. • There is a strong discrepancy between symptoms and biomarkers of inflammation in adults with IBD. What is New: • Clinical symptoms are only weakly associated with levels of fecal calprotectin and serum C-reactive protein in children and adolescents with previously diagnosed IBD. • Similarly to adult IBD patients, there is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.

Project description:Inflammatory bowel disease (IBD) is an immunoinflammatory illness of the gut initiated by an immune response to bacteria in the microflora. The resulting immunopathogenesis leads to lesions in epithelial lining of the colon through which bacteria may infiltrate the tissue causing recurring bouts of diarrhea, rectal bleeding, and malnutrition. In healthy individuals such immunopathogenesis is avoided by the presence of regulatory cells that inhibit the inflammatory pathway. Highly relevant to the search for treatment strategies is the identification of components of the inflammatory pathway that allow regulatory mechanisms to be overridden and immunopathogenesis to proceed. In vitro techniques have identified cellular interactions involved in inflammation-regulation crosstalk. However, tracing immunological mechanisms discovered at the cellular level confidently back to an in vivo context of multiple, simultaneous interactions has met limited success. To explore the impact of specific interactions, we have constructed a system of 29 ordinary differential equations representing different phenotypes of T-cells, macrophages, dendritic cells, and epithelial cells as they move and interact with bacteria in the lumen, lamina propria, and lymphoid tissue of the colon. Simulations revealed the positive inflammatory feedback loop formed by inflammatory M1 macrophage activation of T-cells as a driving force underlying the immunopathology of IBD. Furthermore, strategies that remove M1 from the site of infection, by either (i) increasing its potential to switch to a regulatory M2 phenotype or (ii) increasing the rate of reversion (for M1 and M2 alike) to a resting state, cease immunopathogenesis even as bacteria are eliminated by other inflammatory cells. Based on these results, we identify macrophages and their mechanisms of plasticity as key targets for mucosal inflammation intervention strategies. In addition, we propose that the primary mechanism behind the association of PPARgamma mutation with IBD is its ability to mediate the M1 to M2 switch.

Project description:PurposeTo evaluate ultrasonography (US) by using contrast agent microbubbles (MBs) targeted to P-selectin (MB(P-selectin)) to quantify P-selectin expression levels in inflamed tissue and to monitor response to therapy in a murine model of chemically induced inflammatory bowel disease (IBD).Materials and methodsAll procedures in which laboratory animals were used were approved by the institutional administrative panel on laboratory animal care. Binding affinity and specificity of MB(P-selectin) were tested in cell culture experiments under flow shear stress conditions and compared with control MBs (MB(Control)). In vivo binding specificity of MB(P-selectin) to P-selectin was tested in mice with trinitrobenzenesulfonic acid-induced colitis (n = 22) and control mice (n = 10). Monitoring of anti-tumor necrosis factor α antibody therapy was performed over 5 days in an additional 30 mice with colitis by using P-selectin-targeted US imaging, by measuring bowel wall thickness and perfusion, and by using a clinical disease activity index score. In vivo targeted contrast material-enhanced US signal was quantitatively correlated with ex vivo expression levels of P-selectin as assessed by quantitative immunofluorescence.ResultsAttachment of MB(P-selectin) to endothelial cells was significantly (P = .0001) higher than attachment of MB(Control) and significantly (ρ = 0.83, P = .04) correlated with expression levels of P-selectin on endothelial cells. In vivo US signal in mice with colitis was significantly higher (P = .0001) with MB(P-selectin) than with MB(Control). In treated mice, in vivo US signal decreased significantly (P = .0001) compared with that in nontreated mice and correlated well with ex vivo P-selectin expression levels (ρ = 0.69; P = .04). Colonic wall thickness (P ≥ .06), bowel wall perfusion (P ≥ .85), and clinical disease activity scoring (P ≥ .06) were not significantly different between treated and nontreated mice at any time.ConclusionTargeted contrast-enhanced US imaging enables noninvasive in vivo quantification and monitoring of P-selectin expression in inflammation in murine IBD.

Project description:BackgroundFormylated peptide receptor (FPR)-1 is a G-coupled receptor that senses foreign bacterial and host-derived mitochondrial formylated peptides (FPs), leading to innate immune system activation.AimWe sought to investigate the role of FPR1-mediated inflammation and its potential as a therapeutic target in inflammatory bowel disease (IBD).MethodsWe characterized FPR1 gene and protein expression in 8 human IBD (~1000 patients) datasets with analysis on disease subtype, mucosal inflammation, and drug response. We performed in vivo dextran-sulfate sodium (DSS) colitis in C57/BL6 FPR1 knockout mice. In ex vivo studies, we studied the role of mitochondrial FPs and pharmacological blockade of FPR1 using cyclosporin H in human peripheral blood neutrophils. Finally, we assess mitochondrial FPs as a potential mechanistic biomarker in the blood and stools of patients with IBD.ResultsDetailed in silico analysis in human intestinal biopsies showed that FPR1 is highly expressed in IBD (n = 207 IBD vs 67 non-IBD controls, P < .001), and highly correlated with gut inflammation in ulcerative colitis (UC) and Crohn's disease (CD) (both P < .001). FPR1 receptor is predominantly expressed in leukocytes, and we showed significantly higher FPR1+ve neutrophils in inflamed gut tissue section in IBD (17 CD and 24 UC; both P < .001). Further analysis in 6 independent IBD (data available under Gene Expression Omnibus accession numbers GSE59071, GSE206285, GSE73661, GSE16879, GSE92415, and GSE235970) showed an association with active gut inflammation and treatment resistance to infliximab, ustekinumab, and vedolizumab. FPR1 gene deletion is protective in murine DSS colitis with lower gut neutrophil inflammation. In the human ex vivo neutrophil system, mitochondrial FP, nicotinamide adenine dinucleotide dehydrogenase subunit-6 (ND6) is a potent activator of neutrophils resulting in higher CD62L shedding, CD63 expression, reactive oxygen species production, and chemotactic capacity; these effects are inhibited by cyclosporin H. We screened for mitochondrial ND6 in IBD (n = 54) using ELISA and detected ND6 in stools with median values of 2.2 gg/mL (interquartile range [IQR] 0.0-4.99; range 0-53.3) but not in blood. Stool ND6 levels, however, were not significantly correlated with paired stool calprotectin, C-reactive protein, and clinical IBD activity.ConclusionsOur data suggest that FPR1-mediated neutrophilic inflammation is a tractable target in IBD; however, further work is required to clarify the clinical utility of mitochondrial FPs as a potential mechanistic marker for future stratification.

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An engineered cyclic peptide alleviates symptoms of inflammation in a murine model of inflammatory bowel disease.

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An engineered cyclic peptide alleviates symptoms of inflammation in a murine model of inflammatory bowel disease.

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