Classification model of amino acid sequences prone to aggregation of therapeutic proteins

IAF, QGF, and QDF Peptides Exhibit Cholesterol-Lowering Activity through a Statin-like HMG-CoA Reductase Regulation Mechanism: In Silico and In Vitro Approach

In this study, in silico approaches are employed to investigate the binding mechanism of peptides derived from cowpea β-vignin and HMG-CoA reductase. With the obtained information, we designed synthetic peptides to evaluate their in vitro enzyme inhibitory activity. In vitro, the total protein extract and <3 kDa fraction, at 5000 µg, support this hypothesis (95% and 90% inhibition of HMG-CoA reductase, respectively). Ile-Ala-Phe, Gln-Gly-Phe, and Gln-Asp-Phe peptides were predicted to bind to the substrate binding site of HMGCR via HMG-CoAR. In silico, it was established that the mechanism of HMG-CoA reductase inhibition largely entailed mimicking the interactions of the decalin ring of simvastatin and via H-bonding; in vitro studies corroborated the predictions, whereby the HMG-CoA reductase activity was decreased by 69%, 77%, and 78%, respectively. Our results suggest that Ile-Ala-Phe, Gln-Gly-Phe, and Gln-Asp-Phe peptides derived from cowpea β-vignin have the potential to lower cholesterol synthesis through a statin-like regulation mechanism.

Fabrication of hollow microneedles using liquid crystal display (LCD) vat polymerization 3D printing technology for transdermal macromolecular delivery

The present study aimed to fabricate a hollow microneedle device consisting of an array and a reservoir by means of 3D printing technology for transdermal peptide delivery. Hollow microneedles (HMNs) were fabricated using a biocompatible resin material, while PLA filament was used for the reservoirs. The fabricated microdevice was characterized by means of optical microscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), contact angle measurements and leakage inspection studies to ensure the passageway of liquid formulations. Mechanical failure and penetration tests were carried out and supported by Finite Element Analysis (FEA). The cytocompatibility of the microneedle arrays was assessed to human keratinocytes (HaCaT). Finally, the transport of the model peptide octreotide acetate across artificial membranes was assessed in Franz cells using the aforementioned HMN design.

Aggregates of IVIG or Avastin, but not HSA, modify the response to model innate immune response modulating impurities

Therapeutic proteins can induce immune responses that affect their safety and efficacy. Product aggregates and innate immune response modulating impurities (IIRMI) are risk factors of product immunogenicity. In this study, we use Intravenous Immunoglobulin (IVIG), Avastin, and Human Serum Albumin (HSA) to explore whether increased aggregates activate innate immune cells or modify the response to IIRMI. We show that increased aggregates (shaken or stirred) in IVIG and Avastin, but not HSA, induced activation of MAPKs (pp38, pERK and pJNK) and transcription of immune-related genes including IL8, IL6, IL1β, CSF1, CCL2, CCL7, CCL3, CCL24, CXCL2, IRAK1, EGR2, CEBPβ, PPARg and TNFSF15 in human PBMC. The immunomodulatory effect was primarily mediated by FcγR, but not by TLR. Interestingly, increased aggregates in IVIG or Avastin magnified innate immune responses to TLR2/4 agonists, but diminished responses to TLR3/9 agonists. This study shows that IIRMI and aggregates can modify the activity of immune cells potentially modifying the milieu where the products are delivered highlighting the complex interplay of different impurities on product immunogenicity risk. Further, we show that aggregates could modify the sensitivity of PBMC-based assays designed to detect IIRMI. Understanding and managing immunogenicity risk is a critical component of product development and regulation.

In vitro and in silico studies of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitory activity of the cowpea Gln-Asp-Phe peptide

Previous studies have shown that cowpea protein positively interferes with cholesterol metabolism. In this study, we evaluated the ability of the fraction containing peptides of <3 kDa, as well as that of the Gln-Asp-Phe (QDF) peptide, derived from cowpea β-vignin protein, to inhibit HMG-CoA reductase activity. We established isolation and chromatography procedures to effectively obtain the protein with a purity above 95%. In silico predictions were performed to identify peptide sequences capable of interacting with HMG-CoA reductase. In vitro experiments showed that the fraction containing peptides of <3 kDa displayed inhibition of HMG-CoA reductase activity. The tripeptide QDF inhibits HMG-CoA reductase (IC₅₀ = 12.8 μM) in a dose-dependent manner. Furthermore, in silico studies revealed the binding profile of the QDF peptide and hinted at the molecular interactions that are responsible for its activity. Therefore, this study shows, for the first time, a peptide from cowpea β-vignin protein that inhibits HMG-CoA reductase and the chemical modifications that should be investigated to evaluate its binding profile.

Designing a mutant Candida uricase with improved polymerization state and enzymatic activity

As human uricase has been silenced during evolution, counterparts from other species become an alternative for the treatment of hyperuricemia. Candida uricase is a promising option among them, but its aggregation propensity remains a major obstacle to clinical use. In this study, we designed two mutations according to homology-modeled 3D structure of Candida uricase: Cys249Ser substitution and C-terminal Leu deletion. The wild-type uricase and three mutants containing either or both of the mutations were expressed in Escherichia coli BL21 and validated by mass spectrometry. Size-exclusion chromatography and electrophoresis analysis demonstrated that aggregation was induced by interchain disulfide bonds and could be significantly avoided by Cys249Ser substitution. In combination with Cys249Ser substitution, deletion of Leu increased the enzymatic activity by 8%. Taken together, mutant containing both mutations is chosen as our target protein which is comparatively more suitable for therapeutic use. In addition, homology-modeled 3D structure was proved to be an efficient approach for protein engineering.