Short bowel syndrome: recent clinical outcomes with growth hormone

Expression, Purification and Characterization of Functional Teduglutide Using GST Fusion System in Prokaryotic Cells

Purpose

Teduglutide is the first and only FDA-approved drug for long-term treatment of short bowel syndrome (SBS). The current study aimed to present an approach for production of teduglutide using recombinant DNA technology.

Methods

The coding gene for teduglutide was cloned into pGEX-2T vector, where coding sequence for factor Xa cleavage site was added between GST and teduglutide coding genes. The GST-teduglutide protein was overexpressed in E. coli BL21 (DE3) strain and affinity purified using glutathione sepharose affinity column.

Results

On-column proteolytic activity of factor Xa followed by size exclusion chromatography resulted in the pure teduglutide. Circular dichroism (CD) spectropolarimetry showed that the produced teduglutide folds into mainly α-helical structure (>50%), as expected. In mass spectroscopy analysis, the fragments of teduglutide resulted by cyanogen bromide cleavage as well as those expected theoretically due to mass fragmentation were identified. The functionality of the produced peptide was evaluated by measuring its proliferative effect on Caco2 intestinal epithelial cells, and the results indicated that produced teduglutide induces cell proliferation by 19±0.30 and 33±7.82 % at 1.21 and 3.64 µM concentrations, respectively, compared to untreated cells.

Conclusion

Teduglutide was successfully expressed and purified and its functionality and structural integrity were confirmed by in vitro experiments. We believe that the experimental-scale method presented in the current study can be useful for pilot-scale and also industrial-scale production of teduglutide.

Expression, purification and molecular dynamics simulation of extracellular domain of glucagon-like peptide-2 receptor linked to teduglutide

Teduglutide is the only drug approved for long-term treatment of short bowel syndrome (SBS). This drug exerts its pharmacological effects via binding to the GLP-2 receptors (ECD-GLP2R) located in intestinal tissue. The three dimensional (3D) structure of ECD-GLP2R hasn't been determined yet and hence its mode of interaction with agonists/antagonists is not clear. Therefore, it would be of great importance to develop a structural scaffold for investigation of ECD-GLP2R interactions with its binders. For this, the current study aimed to produce fusion protein of ECD-GLP2R-teduglutide. The ECD-GLP2R-teduglutide protein was expressed in bacterial expression system and purified using affinity and size exclusion chromatography techniques. Using circular dichroism the secondary structure content of purified protein was determined which was comparable to that of theoretical calculations. The low structural stability of purified protein (ΔG = 3.64 kJ.mol^-1) was elucidated by monitoring its fluorescence emission at the presence of various concentrations of GdnHCl as a denaturant. Finally, a 3D model for ECD-GLP2R-teduglutide protein was generated and validated using molecular dynamics simulation whose information alongside the experimental studies can be useful for providing new insight into the mode of interaction of ECD-GLP2R with its specific ligands in order to design potent and specific GLP2R agonists.

Clustering of Zika Viruses Originating from Different Geographical Regions using Computational Sequence Descriptors

BACKGROUND

In this report, we consider a data set, which consists of 310 Zika virus genome sequences taken from different continents, Africa, Asia and South America. The sequences, which were compiled from GenBank, were derived from the host cells of different mammalian species (Simiiformes, Aedes opok, Aedes africanus, Aedes luteocephalus, Aedes dalzieli, Aedes aegypti, and Homo sapiens).

METHODS

For chemometrical treatment, the sequences have been represented by sequence descriptors derived from their graphs or neighborhood matrices. The set was analyzed with three chemometrical methods: Mahalanobis distances, principal component analysis (PCA) and self organizing maps (SOM). A good separation of samples with respect to the region of origin was observed using these three methods.

RESULTS

Study of 310 Zika virus genome sequences from different continents. To characterize and compare Zika virus sequences from around the world using alignment-free sequence comparison and chemometrical methods.

CONCLUSION

Mahalanobis distance analysis, self organizing maps, principal components were used to carry out the chemometrical analyses of the Zika sequence data. Genome sequences are clustered with respect to the region of origin (continent, country). Africa samples are well separated from Asian and South American ones.

Designing Novel Teduglutide Analogues with Improved Binding Affinity: An In Silico Peptide Engineering Approach

INTRODUCTION

Short bowel syndrome (SBS) is a disabling condition that occurs following the loss of substantial portions of the intestine, leading to inadequate absorption of nutrients and fluids. Teduglutide is the only drug that has been FDA-approved for long-term treatment of SBS. This medicine exerts its biological effects through binding to the GLP-2 receptor.

METHODS

The current study aimed to use computational mutagenesis approaches to design novel potent analogues of teduglutide. To this end, the constructed teduglutide-GLP2R 3D model was subjected to the alanine scanning mutagenesis where ARG²⁰, PHE²², ILE²³, LEU²⁶, ILE²⁷ and LYS³⁰ were identified as the key amino acids involved in ligand-receptor interaction. In order to design potent teduglutide analogues, using MAESTROweb machine learning method, the residues of teduglutide were virtually mutated into all naturally occurring amino acids and the affinity improving mutations were selected for further analysis using PDBePISA methodology which interactively investigates the interactions established at the interfaces of macromolecules.

RESULTS

The calculations resulted in D15I, D15L, D15M and N24M mutations, which can improve the binding ability of the ligand to the receptor. The final evaluation of identified mutations was performed by molecular dynamics simulations, indicating that D15I and D15M are the most reliable mutations to increase teduglutide affinity towards its receptor.

CONCLUSION

The findings in the current study may facilitate designing more potent teduglutide analogues leading to the development of novel treatments in short bowel syndrome.

GLP-2 Analogues as First Specific Treatment of Intestinal Failure

Growth factors and other trophic hormones play an important role in the specific treatment of intestinal failure, with teduglutide being the first approved medication specifically for use in patients with intestinal failure in conjunction with specialized nutritional support. This article focusses on the mode of action, the pivotal study data, treatment response prediction as well as new substances in phase clinical trials.

Management and Complications of Short Bowel Syndrome: an Updated Review

Short bowel syndrome (SBS) is defined as loss of bowel mass from surgical resection, congenital defects, or disease. Intestinal failure (IF) includes the subset of SBS unable to meet nutrition needs with enteral supplements and requires parenteral nutrition (PN). The parenteral treatment of SBS is now a half-century old. Recent pharmacologic treatment (GLP-2 analogues) has begun to make a significant impact in the care and ultimate management of these patients such that the possibility of reducing PN requirements in formerly PN-dependent patients is a now a real possibility. Finally, newer understanding and possible treatment for some of the complications related to IF have more recently evolved and will be an emphasis of this report. This review will focus on developments over the last 10 years with the goal of updating the reader to new advances in our understanding of the care and feeding of the SBS patient.

The future developments in nutrition

Malnutrition is both a cause and consequence of disease. It is imperative that evidence-based approaches to detect and treat malnutrition are embedded into routine practice; these can range from routine malnutrition screening, the safe and appropriate use of enteral feeding and managing more complex patients with intestinal failure. This article outlines service developments over the next 5 years that may enable all hospitals to achieve optimal standards of care for a malnourished patient and examines the role of developments in clinical nutrition over the next 5-10 years.

Short bowel syndrome

Treatment of short bowel syndrome (SBS) is often a difficult endeavor due to the high variability among patients with SBS in regard to remaining anatomical structure and functional capacity. Research efforts to substantiate the use of existing therapies in the treatment of SBS are ongoing, with newer developments yet to be fully explored. Current therapy for SBS begins with the implementation of a modified diet based on the presence or absence of the colon. Patients with difficulty ingesting enough nutrients and fluids for weight maintenance and fluid balance may benefit from nocturnal enteral nutrition and hydration. Those with inadequate absorptive capacity despite maximization of oral and enteral intake will need parenteral nutrition (PN) or hydration. Medications, including antisecretory agents, antidiarrheals, pancreatic enzymes, bile acid sequestrants, and antibiotics, often are useful in abating symptoms commonly associated with SBS. Growth factors, including recombinant human growth hormone and glucagon-like peptide 2, may be trialed to stimulate intestinal adaptation and enhance absorption in PN-dependent SBS patients. The gradual refinement of surgical procedures for SBS, including small bowel transplantation, has led to improved outcomes, and early referral of SBS patients to centers of excellence will optimize care.

Suppression of intestinal mucosal apoptosis by ghrelin in fasting rats

Ghrelin is mainly produced in the stomach and has several physiologic functions. The aim of this study was to investigate whether ghrelin regulates apoptosis in the small intestinal mucosa of fasting rats. Intestinal mucosal apoptosis was evaluated as the percentage of fragmented DNA, villus height, and terminal deoxynucleotidyl transferase-mediated dUDP-biotin nick end-labeling (TUNEL) staining and by Western blot analysis of caspase-3 in 48-hr fasting rats. Crypt cell proliferation was evaluated by counting the number of 5-bromo-2-deoxyuridine (BrdU) positive cells. Ghrelin was administered intraperitoneally at dosages of 2.5, 25, and 250 microg/kg per 48 hrs by continuous infusion via an Alzet micro-osmotic pump or injections at 12-hr intervals. Ghrelin was also infused in rats that underwent truncal vagotomy. The lowest dosage of ghrelin (2.5 microg/kg per 48 hrs) was administered into the third cerebroventricle. Ghrelin treatment attenuated the percentage of fragmented DNA in the small intestinal mucosa in 48-hr fasting rats in a dose-dependent manner. Continuous infusion of ghrelin and injections of ghrelin at 12-hr intervals suppressed intestinal apoptosis almost equally. This effect on apoptosis was not attenuated by truncal vagotomy. Cerebroventricular infusion of ghrelin also attenuated intestinal apoptosis. The antiapoptotic effect of ghrelin was confirmed by decreased TUNEL staining, recovery of the villus height, and decreased expression of caspase-3. BrdU uptake indicated that ghrelin enhanced cell proliferation in the intestinal crypt. Taken together, these data indicate that ghrelin enhanced intestinal growth with the suppression of small intestinal mucosal apoptosis in 48-hr fasting rats, suggesting that ghrelin controls intestinal function through the regulation of intestinal apoptosis.

The essential role of insulin-like growth factor-1 in the intestinal tropic effects of glucagon-like peptide-2 in mice

BACKGROUND & AIMS

Glucagon-like peptide-2 (GLP-2) is an intestinal hormone that acts through unknown pathways to induce intestinal growth. We investigated the role of the insulin-like growth factors (IGF-1 and IGF-2) as mediators of GLP-2-enhanced growth in the murine intestine.

METHODS

IGF-1 expression and secretion were determined in GLP-2-responsive primary intestinal cultures treated with GLP-2. Parameters of intestinal growth were assessed in wild-type (CD1, Igf1(+/+) and Igf2+), heterozygous (Igf1(+/-)), and null (Igf1(-/-) and Igf2(-P)) mice treated chronically with saline, GLP-2, IGF-1, or R-Spondin1.

RESULTS

GLP-2 increased IGF-1 messenger RNA expression and IGF-1 secretion in intestinal cultures and increased expression of IGF-1 messenger RNA in mouse small intestine in vivo. Igf1(+/+) and Igf2+ mice responded to .1 microg/g(-1) per day(-1) GLP-2 with increased intestinal weights, morphometric parameters, and proliferative indices. In contrast, Igf1(-/-) mice were unresponsive to the same dose of GLP-2, failing to demonstrate changes in intestinal weight, morphometry, or proliferation. However, a significant effect of 1 microg/g(-1) per day(-1) GLP-2 was observed in Igf1(-/-) mice, but only in terms of small intestinal weight when normalized for body weight. Furthermore, Igf2(-P) mice demonstrated a partially impaired response in terms of small intestinal growth. Both Igf1(-/-) and Igf2(-P) mice exhibited normal-enhanced intestinal growth in response to IGF-1 and/or R-Spondin1.

CONCLUSIONS

GLP-2 enhances intestinal IGF-1 expression and secretion, and IGF-1 is required for small and large intestinal growth in response to GLP-2. These findings identify IGF-1 as an essential mediator of the intestinotropic actions of GLP-2.