Effect of metal catalyzed oxidation in recombinant viral protein assemblies

Rapid assessment of changes in phage bioactivity using dynamic light scattering

Extensive efforts are underway to develop bacteriophages as therapies against antibiotic-resistant bacteria. However, these efforts are confounded by the instability of phage preparations and a lack of suitable tools to assess active phage concentrations over time. In this study, we use dynamic light scattering (DLS) to measure changes in phage physical state in response to environmental factors and time, finding that phages tend to decay and form aggregates and that the degree of aggregation can be used to predict phage bioactivity. We then use DLS to optimize phage storage conditions for phages from human clinical trials, predict bioactivity in 50-y-old archival stocks, and evaluate phage samples for use in a phage therapy/wound infection model. We also provide a web application (Phage-Estimator of Lytic Function) to facilitate DLS studies of phages. We conclude that DLS provides a rapid, convenient, and nondestructive tool for quality control of phage preparations in academic and commercial settings.

Neuropeptide substance P: A promising regulator of wound healing in diabetic foot ulcers

In the past, neuropeptide substance P (SP) was predominantly recognized as a neuroinflammatory factor, while its potent healing activity was overlooked. This paper aims to review the regulatory characteristics of neuropeptide SP in both normal and diabetic wound healing. SP actively in the regulation of wound healing-related cells directly and indirectly, exhibiting robust inflammatory properties, promoting cell proliferation and migration and restoring the activity and paracrine ability of skin cells under diabetic conditions. Furthermore, SP not only regulates healing-related cells but also orchestrates the immune environment, thereby presenting unique and promising application prospects in wound intervention. As new SP-based preparations are being explored, SP-related drugs are poised to become an effective therapeutic intervention for diabetic foot ulcers (DFU).

Rapid assessment of changes in phage bioactivity using dynamic light scattering

Extensive efforts are underway to develop bacteriophages as therapies against antibiotic-resistant bacteria. However, these efforts are confounded by the instability of phage preparations and a lack of suitable tools to assess active phage concentrations over time. Here, we use Dynamic Light Scattering (DLS) to measure changes in phage physical state in response to environmental factors and time, finding that phages tend to decay and form aggregates and that the degree of aggregation can be used to predict phage bioactivity. We then use DLS to optimize phage storage conditions for phages from human clinical trials, predict bioactivity in 50-year-old archival stocks, and evaluate phage samples for use in a phage therapy/wound infection model. We also provide a web-application (Phage-ELF) to facilitate DLS studies of phages. We conclude that DLS provides a rapid, convenient, and non-destructive tool for quality control of phage preparations in academic and commercial settings.

Manipulation of Oxidative Stress Responses by Non-Thermal Plasma to Treat Herpes Simplex Virus Type 1 Infection and Disease

Herpes simplex virus type 1 (HSV-1) is a contagious pathogen with a large global footprint, due to its ability to cause lifelong infection in patients. Current antiviral therapies are effective in limiting viral replication in the epithelial cells to alleviate clinical symptoms, but ineffective in eliminating latent viral reservoirs in neurons. Much of HSV-1 pathogenesis is dependent on its ability to manipulate oxidative stress responses to craft a cellular environment that favors HSV-1 replication. However, to maintain redox homeostasis and to promote antiviral immune responses, the infected cell can upregulate reactive oxygen and nitrogen species (RONS) while having a tight control on antioxidant concentrations to prevent cellular damage. Non-thermal plasma (NTP), which we propose as a potential therapy alternative directed against HSV-1 infection, is a means to deliver RONS that affect redox homeostasis in the infected cell. This review emphasizes how NTP can be an effective therapy for HSV-1 infections through the direct antiviral activity of RONS and via immunomodulatory changes in the infected cells that will stimulate anti-HSV-1 adaptive immune responses. Overall, NTP application can control HSV-1 replication and address the challenges of latency by decreasing the size of the viral reservoir in the nervous system.

Rotavirus VP6: involvement in immunogenicity, adjuvant activity, and use as a vector for heterologous peptides, drug delivery, and production of nano-biomaterials

The first-generation, live attenuated rotavirus (RV) vaccines, such as RotaTeq and Rotarix, were successful in reducing the number of RV-induced acute gastroenteritis (AGE) and child deaths globally. However, the low efficacy of these first-generation oral vaccines, coupled with safety concerns, required development of improved RV vaccines. The highly conserved structural protein VP6 is highly immunogenic, and it can generate self-assembled nano-sized structures, including tubes and spheres (virus-like particles; VLPs). Amongst the RV proteins, only VP6 shows these features. Interestingly, VP6-assembled structures, in addition to being highly immunogenic, have several other useful characteristics that could allow them to be used as adjuvants, immunological carriers, and drug-delivery vehicles as well as acting a scaffold for production of valuable nano-biomaterials. This review provides an overview of the self-assembled nano-sized structures of VP6-tubes/VLPs and their various functions.

Triosephosphate isomerase as a therapeutic target against trichomoniasis

Trichomoniasis is the most common non-viral sexually transmitted infection, caused by the protozoan parasite Trichomonas vaginalis, affecting millions of people worldwide. The main treatment against trichomoniasis is metronidazole and other nitroimidazole derivatives, but up to twenty percent of clinical cases of trichomoniasis are resistant to these drugs. In this study, we used high-performance virtual screening to search for molecules that specifically bind to the protein, triosephosphate isomerase from T. vaginalis (TvTIM). By in silico molecular docking analysis, we selected six compounds from a chemical library of almost 500,000 compounds. While none of the six inhibited the enzymatic activity of recombinant triosephosphate isomerase isoforms, one compound (A4; 3,3'-{[4-(4-morpholinyl)phenyl]methylene}bis(4- hydroxy-2H-chromen-2-one) altered their fluorescence emission spectra, suggesting that this chemical might interfere in an important non-glycolytic function of TvTIM. In vitro assays demonstrate that A4 is not cytotoxic but does have trichomonacidal impact on T. vaginalis cultures. With these results, we propose this compound as a potential drug with a new therapeutic target against Trichomonas vaginalis.

A multifunctional substance P-conjugated chitosan hydrochloride hydrogel accelerates full-thickness wound healing by enhancing synchronized vascularization, extracellular matrix deposition, and nerve regeneration

Due to the native skin limitations and the complexity of reconstructive microsurgery, advanced biomaterials are urgently required to promote wound healing for severe skin defects caused by accidents and disasters. Accumulating evidence has supported that substance P (SP) has a potential effect on skin regeneration. However, SP application is seriously impeded by its poor stability and oxidative reactions occurring during production, transportation, and storage. An SP-conjugated chitosan hydrochloride hydrogel (CSCl-SP) fabricated in this study demonstrated an enhanced capacity to repair full-thickness skin defects. CSCl-SP provided a stable in vitro delivery system for SP. The dissolution of CSCl-SP promoted the proliferation, migration, and tube formation, as well as angiogenesis-related gene and protein expression in human umbilical vein endothelial cells. CSCI-SP also stimulated the proliferation, migration, and production of anabolic growth factor in human fibroblasts. Moreover, CSCl-SP significantly promoted the neurite outgrowth in Neuro-2A cells. In vivo, CSCl-SP dramatically strengthened the vascularization, extracellular matrix deposition and remodeling, and nerve regeneration, thereby promoting efficient recovery of the full-thickness skin defect. Thus, synchronized multifunction of the CSCl-SP hydrogel makes it a promising and smart material for intractable skin defects.

Gelatin methacryloyl hydrogels functionalized with endothelin-1 for angiogenesis and full-thickness wound healing

Natural polymer hydrogels are widely used as wound dressings, but they do not have enough bioactivity to accelerate angiogenesis and re-epithelialization. Herein, a therapeutic system was firstly constructed in which endothelin-1 (ET-1), as an endogenous vasoconstrictor peptide, was embedded in a photo-crosslinking gelatin methacryloyl (GelMA) hydrogel for full-thickness wound healing. The multifunctional GelMA-ET-1 hydrogels contained the arginine-glycine-aspartate (RGD) motifs of gelatin that provided adhesive sites for cell proliferation and migration. The ET-1 was wrapped within the network of crosslinked GelMA hydrogels via intermolecular hydrogen bonding interactions, effectively avoiding oxidization by atmospheric oxygen and in vivo enzymatic biodegradation. Notably, the ET-1 in the functional hydrogels significantly promoted the proliferation, migration and angiogenesis-related gene expression of human umbilical vein endothelial cells (HUVECs) and fibroblasts. The full-thickness skin defect model of rats further revealed that the GelMA-ET-1 hydrogels significantly accelerated new blood vessel formation, collagen deposition and re-epithelialization. After 14 days, the full-thickness skin defects almost closed and were filled with the newly formed tissue. Hence, the photo-crosslinking GelMA-ET-1 hydrogels functionalized with ET-1 can be employed as a promising therapeutic system for wound healing.

A Novel Substance P-Based Hydrogel for Increased Wound Healing Efficiency

The neuropeptide substance P (SP) is known to stimulate wound healing by regulating the production of relevant cytokines as well as cell proliferation and migration. However, the therapeutic application of SP is limited by its low stability under biological conditions and oxidation during purification, formulation, and storage. To address this problem, we developed a novel formulation of SP as an SP gel, and investigated its wound healing activity both in vitro and in vivo. SP in SP gel was stable at various temperatures for up to 4 weeks. In vitro, SP gel exhibited more potential as a candidate wound-healing agent than SP alone, as evidenced by the observed increases in the proliferation and migration of human epidermal keratinocytes and human dermal fibroblasts. In vivo experiments showed that SP gel treatment enhanced the healing of full-thickness wounds in mice as compared to SP alone. These results demonstrate the benefits of SP gel as a promising topical agent for wound treatment.

Effects of Fenton Reaction on Human Serum Albumin: An In Vitro Study

Introduction

Human serum albumin (HSA) is a critical protein in human blood plasma, which can be highly damaged by oxidative stress. The aim of this study was to analyze modifications of this protein after oxidation using a Fenton system.

Methods

In this 2015 experiment, different ratios of Fenton reagent (Fe2+/H₂O₂) was incubated with one concentration of human serum albumin (1mg/ml). Hence, HSA was incubated 30 min with various combinations of a Fenton system and quantified oxidation products such as carbonyl groups, fragmentations, degradations, and oxidized free thiol group using reliable techniques. Image and data analysis were carried out using ImageJ software and Excel (version 2007), respectively.

Results

An SDS-PAGE profile showed no cross link and aggregation. However, protein band intensity has decreased to 50% in the highest ratio of H₂O₂/Fe. Carbonylation assay indicated carbonyl/protein (molc/molp) ratio increased linearly in lower ratios and the values plateau at higher levels of H₂O₂/Fe 2+. The only free sulfhydryl group on HSA was oxidized in all ratios of the Fenton system.

Conclusion

To sum, the structure of HSA has been changed following treatment with Hydroxyl Radical as the main product of Fenton reaction. These data confirm the antioxidant activity of HSA.

Influence of pH control in the formation of inclusion bodies during production of recombinant sphingomyelinase-D in Escherichia coli

BACKGROUND

Inclusion bodies (IBs) are aggregated proteins that form clusters when protein is overexpressed in heterologous expression systems. IBs have been considered as non-usable proteins, but recently they are being used as functional materials, catalytic particles, drug delivery agents, immunogenic structures, and as a raw material in recombinant therapeutic protein purification. However, few studies have been made to understand how culture conditions affect the protein aggregation and the physicochemical characteristics that lead them to cluster. The objective of our research was to understand how pH affects the physicochemical properties of IBs formed by the recombinant sphingomyelinase-D of tick expressed in E. coli BL21-Gold (DE3) by evaluating two pH culture strategies.

RESULTS

Uncontrolled pH culture conditions favored recombinant sphingomyelinase-D aggregation and IB formation. The IBs of sphingomyelinase-D produced under controlled pH at 7.5 and after 24 h were smaller (<500 nm) than those produced under uncontrolled pH conditions (>500 nm). Furthermore, the composition, conformation and β-structure formation of the aggregates were different. Under controlled pH conditions in comparison to uncontrolled conditions, the produced IBs presented higher resistance to denaturants and proteinase-K degradation, presented β-structure, but apparently as time passes the IBs become compacted and less sensitive to amyloid dye binding.

CONCLUSIONS

The manipulation of the pH has an impact on IB formation and their physicochemical characteristics. Particularly, uncontrolled pH conditions favored the protein aggregation and sphingomyelinase-D IB formation. The evidence may lead to find methodologies for bioprocesses to obtain biomaterials with particular characteristics, extending the application possibilities of the inclusion bodies.