Development of a scalable single process for producing SARS-CoV-2 RBD monomer and dimer vaccine antigens.

We have developed a single process for producing two key COVID-19 vaccine antigens: SARS-CoV-2 receptor binding domain (RBD) monomer and dimer. These antigens are featured in various COVID-19 vaccine formats, including SOBERANA 01 and the licensed SOBERANA 02, and SOBERANA Plus. Our approach involves expressing RBD (319-541)-His6 in Chinese hamster ovary (CHO)-K1 cells, generating and characterizing oligoclones, and selecting the best RBD-producing clones. Critical parameters such as copper supplementation in the culture medium and cell viability influenced the yield of RBD dimer. The purification of RBD involved standard immobilized metal ion affinity chromatography (IMAC), ion exchange chromatography, and size exclusion chromatography. Our findings suggest that copper can improve IMAC performance. Efficient RBD production was achieved using small-scale bioreactor cell culture (2 L). The two RBD forms - monomeric and dimeric RBD - were also produced on a large scale (500 L). This study represents the first large-scale application of perfusion culture for the production of RBD antigens. We conducted a thorough analysis of the purified RBD antigens, which encompassed primary structure, protein integrity, N-glycosylation, size, purity, secondary and tertiary structures, isoform composition, hydrophobicity, and long-term stability. Additionally, we investigated RBD-ACE2 interactions, in vitro ACE2 recognition of RBD, and the immunogenicity of RBD antigens in mice. We have determined that both the monomeric and dimeric RBD antigens possess the necessary quality attributes for vaccine production. By enabling the customizable production of both RBD forms, this unified manufacturing process provides the required flexibility to adapt rapidly to the ever-changing demands of emerging SARS-CoV-2 variants and different COVID-19 vaccine platforms.

Could a Non-Cellular Molecular Interactome in the Blood Circulation Influence Pathogens' Infectivity?

We advance the notion that much like artificial nanoparticles, relatively more complex biological entities with nanometric dimensions such as pathogens (viruses, bacteria, and other microorganisms) may also acquire a biomolecular corona upon entering the blood circulation of an organism. We view this biomolecular corona as a component of a much broader non-cellular blood interactome that can be highly specific to the organism, akin to components of the innate immune response to an invading pathogen. We review published supporting data and generalize these notions from artificial nanoparticles to viruses and bacteria. Characterization of the non-cellular blood interactome of an organism may help explain apparent differences in the susceptibility to pathogens among individuals. The non-cellular blood interactome is a candidate therapeutic target to treat infectious and non-infectious conditions.

Could Endogenous Glucocorticoids Influence SARS-CoV-2 Infectivity?

Endogenous glucocorticoids and their synthetic analogues, such as dexamethasone, stimulate receptor-mediated signal transduction mechanisms on target cells. Some of these mechanisms result in beneficial outcomes whereas others are deleterious in the settings of pathogen infections and immunological disorders. Here, we review recent studies by several groups, including our group, showing that glucocorticoids can directly interact with protein components on SARS-CoV-2, the causative agent of COVID-19. We postulate an antiviral defence mechanism by which endogenous glucocorticoids (e.g., cortisol produced in response to SARS-CoV-2 infection) can bind to multiple sites on SARS-CoV-2 surface protein, Spike, inducing conformational alterations in Spike subunit 1 (S1) that inhibit SARS-CoV-2 interaction with the host SARS-CoV-2 receptor, ACE2. We suggest that glucocorticoids-mediated inhibition of S1 interaction with ACE2 may, consequently, affect SARS-CoV-2 infectivity. Further, glucocorticoids interactions with Spike could protect against a broad spectrum of coronaviruses and their variants that utilize Spike for infection of the host. These notions may be useful for the design of new antivirals for coronavirus diseases.

Glucocorticoids Bind to SARS-CoV-2 S1 at Multiple Sites Causing Cooperative Inhibition of SARS-CoV-2 S1 Interaction With ACE2.

Dexamethasone may reduce mortality in COVID-19 patients. Whether dexamethasone or endogenous glucocorticoids, such as cortisol, biochemically interact with SARS-CoV-2 spike 1 protein (S1), or its cellular receptor ACE2, is unknown. Using molecular dynamics (MD) simulations and binding energy calculations, we identified 162 druggable pockets in various conformational states of S1 and all possible binding pockets for cortisol and dexamethasone. Through biochemical binding studies, we confirmed that cortisol and dexamethasone bind to S1. Limited proteolysis and mass spectrometry analyses validated several MD identified binding pockets for cortisol and dexamethasone on S1. Interaction assays indicated that cortisol and dexamethasone separately and cooperatively disrupt S1 interaction with ACE2, through direct binding to S1, without affecting ACE2 catalytic activity. Cortisol disrupted the binding of the mutant S1 Beta variant (E484K, K417N, N501Y) to ACE2. Delta and Omicron variants are mutated in or near identified cortisol-binding pockets in S1, which may affect cortisol binding to them. In the presence of cortisol, we find increased inhibition of S1 binding to ACE2 by an anti-SARS-CoV-2 S1 human chimeric monoclonal antibody against the receptor binding domain. Whether glucocorticoid/S1 direct interaction is an innate defence mechanism that may have contributed to mild or asymptomatic SARS-CoV-2 infection deserves further investigation.

Matrix Metalloproteinases in Health and Disease in the Times of COVID-19.

Much has been written about matrix metalloproteinases (MMPs) in health and disease conditions, but their roles in the setting of COVID-19 and associated illnesses remain understudied [...].

Targeting MMP-Regulation of Inflammation to Increase Metabolic Tolerance to COVID-19 Pathologies: A Hypothesis.

Many individuals infected with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) develop no or only mild symptoms, but some can go on onto develop a spectrum of pathologies including pneumonia, acute respiratory distress syndrome, respiratory failure, systemic inflammation, and multiorgan failure. Many pathogens, viral and non-viral, can elicit these pathologies, which justifies reconsidering whether the target of therapeutic approaches to fight pathogen infections should be (a) the pathogen itself, (b) the pathologies elicited by the pathogen interaction with the human host, or (c) a combination of both. While little is known about the immunopathology of SARS-CoV-2, it is well-established that the above-mentioned pathologies are associated with hyper-inflammation, tissue damage, and the perturbation of target organ metabolism. Mounting evidence has shown that these processes are regulated by endoproteinases (particularly, matrix metalloproteinases (MMPs)). Here, we review what is known about the roles played by MMPs in the development of COVID-19 and postulate a mechanism by which MMPs could influence energy metabolism in target organs, such as the lung. Finally, we discuss the suitability of MMPs as therapeutic targets to increase the metabolic tolerance of the host to damage inflicted by the pathogen infection, with a focus on SARS-CoV-2.

Comparative Serum Analyses Identify Cytokines and Hormones Commonly Dysregulated as Well as Implicated in Promoting Osteolysis in MMP-2-Deficient Mice and Children.

Deficiency of matrix metalloproteinase 2 (MMP-2) causes a complex syndrome characterized by multicentric osteolysis, nodulosis, and arthropathy (MONA) as well as cardiac valve defects, dwarfism and hirsutism. MMP-2 deficient (Mmp2 -/-) mice are a model for this rare multisystem pediatric syndrome but their phenotype remains incompletely characterized. Here, we extend the phenotypic characterization of MMP-2 deficiency by comparing the levels of cytokines and chemokines, soluble cytokine receptors, angiogenesis factors, bone development factors, apolipoproteins and hormones in mice and humans. Initial screening was performed on an 8-year-old male presenting a previously unreported deletion mutation c1294delC (Arg432fs) in the MMP2 gene and diagnosed with MONA. Of eighty-one serum biomolecules analyzed, eleven were upregulated (>4-fold), two were downregulated (>4-fold) and sixty-eight remained unchanged, compared to unaffected controls. Specifically, Eotaxin, GM-CSF, M-CSF, GRO-α, MDC, IL-1ß, IL-7, IL-12p40, MIP-1α, MIP-1ß, and MIG were upregulated and epidermal growth factor (EGF) and ACTH were downregulated in this patient. Subsequent analysis of five additional MMP-2 deficient patients confirmed the upregulation in Eotaxin, IL-7, IL-12p40, and MIP-1α, and the downregulation in EGF. To establish whether these alterations are bona fide phenotypic traits of MMP-2 deficiency, we further studied Mmp2 -/- mice. Among 32 cytokines measured in plasma of Mmp2 -/- mice, the cytokines Eotaxin, IL-1ß, MIP-1α, and MIG were commonly upregulated in mice as well as patients with MMP-2 deficiency. Moreover, bioactive cortisol (a factor that exacerbates osteoporosis) was also elevated in MMP-2 deficient mice and patients. Among the factors we have identified to be dysregulated in MMP-2 deficiency many are osteoclastogenic and could potentially contribute to bone disorder in MONA. These new molecular phenotypic traits merit being targeted in future research aimed at understanding the pathological mechanisms elicited by MMP-2 deficiency in children.

Destroy to Rebuild: The Connection Between Bone Tissue Remodeling and Matrix Metalloproteinases.

Bone is a dynamic organ that undergoes constant remodeling, an energetically costly process by which old bone is replaced and localized bone defects are repaired to renew the skeleton over time, thereby maintaining skeletal health. This review provides a general overview of bone's main players (bone lining cells, osteocytes, osteoclasts, reversal cells, and osteoblasts) that participate in bone remodeling. Placing emphasis on the family of extracellular matrix metalloproteinases (MMPs), we describe how: (i) Convergence of multiple protease families (including MMPs and cysteine proteinases) ensures complexity and robustness of the bone remodeling process, (ii) Enzymatic activity of MMPs affects bone physiology at the molecular and cellular levels and (iii) Either overexpression or deficiency/insufficiency of individual MMPs impairs healthy bone remodeling and systemic metabolism. Today, it is generally accepted that proteolytic activity is required for the degradation of bone tissue in osteoarthritis and osteoporosis. However, it is increasingly evident that inactivating mutations in MMP genes can also lead to bone pathology including osteolysis and metabolic abnormalities such as delayed growth. We argue that there remains a need to rethink the role played by proteases in bone physiology and pathology.

Identification of fibrinogen as a natural inhibitor of MMP-2.

Non-genetic MMP-2 insufficiency is a relatively unexplored condition which could be induced by pathological overexpression of endogenous MMP-2 inhibitors such as TIMPs and/or the acute phase reactant alpha-2-macroglobulin. Here, we investigate the hypothesis that human fibrinogen (FBG) - an acute phase reactant - inhibits human MMP-2. Following an unexpected observation where sera from human donors including arthritis patients with increased levels of serum FBG exhibited reduced binding of serum proMMP-2 to gelatin, we found that human FBG (0 to 3.6 mg/mL i.e., 0 to 10.6 µM) concentration-dependently inhibited human proMMP-2 and MMP2 from binding to gelatin. Moreover, at normal physiological concentrations, FBG (5.29-11.8 µM) concentration-dependently inhibited (40-70% inhibition) the cleavage of fluorescein-conjugated gelatin by MMP-2, but not MMP-9. Indicative of a mixed-type (combination of competitive and non-competitive) inhibition mechanism, FBG reduced the Vmax (24.9 ± 0.7 min-1 to 17.7 ± 0.9 min-1, P < 0.05) and increased the Michaelis-Menten constant KM (204 ± 6 nM to 478 ± 50 nM, P < 0.05) for the reaction of MMP-2 cleavage of fluorescein-conjugated gelatin. In silico analyses and studies of FBG neutralization with anti-FBG antibodies implicated the domains D and E of FBG in the inhibition of MMP-2. In conclusion, FBG is a natural selective MMP-2 inhibitor, whose pathological elevation could lead to MMP-2 insufficiency in humans.

MMP-2: is too low as bad as too high in the cardiovascular system?

Matrix metalloproteinase (MMP)-2 cleaves a broad spectrum of substrates, including extracellular matrix components (responsible for normal tissue remodeling) and cytokines (modulators of the inflammatory response to physiological insults such as tissue damage). MMP-2 expression is elevated in many cardiovascular pathologies (e.g., myocardial infarction, hypertensive heart disease) where tissue remodeling and inflammatory responses are perturbed. Thus, it has generally been assumed that blockade of MMP-2 activity will yield therapeutic effects. Here, we provide a counterargument to this dogma based on 1) preclinical studies on Mmp2-null ( Mmp2-/-) mice and 2) clinical studies on patients with inactivating MMP2 gene mutations. Furthermore, we put forward the hypothesis that, when MMP-2 activity falls below baseline, the bioavailability of proinflammatory cytokines normally cleaved and inactivated by MMP-2 increases, leading to the production of cytokines and cardiac secretion of phospholipase A2 activity into the circulation, which stimulate systemic inflammation that perturbs lipid metabolism in target organs. Finally, we suggest that insufficient understanding of the consequences of MMP-2 deficiency remains a major factor in the failure of MMP-2 inhibitor-based therapeutic approaches. This paucity of knowledge precludes our ability to effectively intervene in cardiovascular and noncardiovascular pathologies at the level of MMP-2.

A New Science Publishing System for a Budding Science Publishing Crisis.

The current science publishing system is in need of a positive transformation for the good of scientists and society as a whole. Herein, we propose features that, in our view, will distinguish the science publishing system of the future.

Lipopolysaccharide aggregates in native agarose gels detected by reversible negative staining with imidazole and zinc salts.

We investigated the use of imidazole and zinc salts for the detection of lipopolysaccharide (LPS) aggregates separated by native agarose gel electrophoresis (NAGE). As a result, a new staining procedure was established by which as little as 1.5 µg of Escherichia coli O55:B5 LPS aggregates was detected by means of inducing a clear, transparent pattern, contrasted against an opaque background. E. coli O55:B5 LPS preparations treated with nucleases and proteinase K proved that the reverse-stained LPS pattern is not related to any potential artifacts caused by unrelated biomolecules (e.g., nucleic acids, proteins). After this, we showed that the procedure is applicable to two-dimensional LPS separation using NAGE/SDS-PAGE, while at the same time confirming that real polydisperse LPS aggregates are represented by the stained profile. Also, we demonstrated the general applicability of this stain to the detection of different NAGE-separated LPS aggregates (e.g., from E. coli 026:B6, E. coli 0111:B4, Salmonella minnesota Re595). Finally, using lysozyme as a model protein, we found that imidazole-zinc may be combined with Coomassie brilliant blue R-250 into a double-staining process to enable the use of NAGE for investigating the interaction of cationic proteins and LPS aggregates and protein or LPS concentration effects on protein-LPS binding.

Implantable controlled release devices for BMP-7 delivery and suppression of glioblastoma initiating cells.

Designing therapeutic devices capable of manipulating glioblastoma initiating cells (GICs) is critical to stop tumor recurrence and its associated mortality. Previous studies have indicated that bone morphogenetic protein-7 (BMP-7) acts as an endogenous suppressor of GICs, and thus, it could become a treatment for this cancer. In this work, we engineer an implantable microsphere system optimized for the controlled release of BMP-7 as a bioinspired therapeutic device against GICs. This microsphere delivery system is based on the formation of a heparin-BMP-7 nanocomplex, first coated with Tetronic(®) and further entrapped in a biodegradable polyester matrix. The obtained microspheres can efficiently encapsulate BMP-7, and release it in a controlled manner with minimum burst effect for over two months while maintaining protein bioactivity. Released BMP-7 showed a remarkable capacity to stop tumor formation in a GICs cell culture model, an effect that could be mediated by forced reprogramming of tumorigenic cells towards a non-tumorigenic astroglial lineage.

Nanoaggregates of micropurified lipopolysaccharide identified using dynamic light scattering, zeta potential measurement, and TLR4 signaling activity.

Nanoaggregates composed of selected glycoforms from Escherichia coli 055:B5 lipopolysaccharide (LPS) were prepared by combining sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, zinc-imidazole reverse staining, zinc chelation after cutting gel slices, elution with either 0.5% triethylamine (TEA) or 0.4% to 0.5% surfactant (SDS or deoxycholate [DOC]) from extrusion-generated gel microparticles, and centrifugal diafiltration after appropriate surfactant dilution. Dynamic light scattering allows detecting these aggregates, giving a size distribution from 10 to 100nm in diameter. The formation of the aggregates prepared with selected DOC-eluted LPS glycoforms was notably improved over those prepared with TEA-eluted glycoforms. As the O-side chain length increased in the composition of the former aggregates, there was a gradual decrease in the electrophoretic mobility (from -1.2 to 0.0110(-8)m(2)/Vs), giving a calculated zeta potential from -15 to 0.1mV at pH6.8. These aggregates were further characterized for their abilities to elicit agonistic effects on human Toll-like receptor 4, as shown by in vitro activation of nuclear factor kappa light chain enhancer of activated B cells (NF-κB) in engineered HEK293 cells.

Microencapsulation of alpha interferons in biodegradable microspheres.

The immunomodulatory, antiproliferative, and antiviral properties of interferons alpha (IFN-α) have made these cytokines attractive for numerous clinical applications. However, most of the current available IFN pharmaceutical dosage forms need to be injected frequently and may provoke adverse reactions in patients. This problem might be overcome by using biodegradable microspheres loaded with IFN. The encapsulation of IFN-α in microspheres and the current status of this technology are the main subjects reviewed here. To this end, we describe (i) the main methods and experimental parameters used to obtain IFN-loaded microspheres and (ii) characterization of these microspheres in terms of morphology, particle size, loading/encapsulation efficiency, residual water content, residual solvent content, release profile, and sterility. Also, we discuss both the characterization of the encapsulated IFN and the stabilization/protection of IFN during microencapsulation. Finally, a brief overview of preclinical and clinical studies using IFN-containing microspheres is given.

Detection of PEGylated proteins in polyacrylamide gels by reverse staining with zinc and imidazole salts.

The reverse staining, with imidazole-SDS-zinc, of PEG-linked proteins separated by SDS-PAGE was studied. Using model conjugates (interferon-alpha 2b (IFN-alpha2b) reacted with either a branched-chain (40,000) PEG (PEG2,40) or a linear monomethoxy PEG polymer (Mr of 12,000) and chromatographically purified monoPEG2,40-IFN-alpha2b), conventional small-format analytical gels (<1 mm thick) showed typical detection patterns (i.e., transparent, colorless bands clearly discernible against a zinc imidazolate-generated white gel background), in less than 20 min. Nonreacted (free) PEG was almost undetected, as expected. The reverse-stained PEGylated IFN-alpha2b patterns were qualitatively indistinguishable from those of parallel gels stained with iodine (I2). The LOD was estimated in the low nanogram range (e.g., at about 7 ng for mono- or bi-PEG2,40 IFN-alpha2b per lane on gradient (4-17%) gels). Also, this stain allowed the visualization of Coomassie blue-undetected PEG-IFN bands, and could be restained with I2. PEGylated species of lysozyme, a low-molecular-weight peptide, ovalbumin, and chymotrypsin were used to demonstrate the generality of this stain. We also show (i) how to counteract the adverse effect of some parameters (e.g., gel thickness above 1 mm, long gel length, low (e.g., 4-6%) acrylamide concentration) on the reverse staining process and (ii) that the properties of the reverse-stained PEGylated proteins remain unchanged, as judged by analyzing both the ion exchange chromatography-based positional isomer separation profile and enzyme-linked immunosorbent response of PEG-IFN recovered from gels. Consequently, this technique may be useful for the rapid analysis or the small-scale preparation of PEGylated proteins.

Isolation of smooth-type lipopolysaccharides to electrophoretic homogeneity.

The high structural heterogeneity of smooth-type lipopolysaccharides (LPS) enormously complicates the isolation of their constituent molecular species. Proof of concept is given here on the feasibility of using preparative slab-PAGE to isolate highly homogeneous smooth-type LPS glycoforms. LPS species (from 3.6 to 14.2 kDa) from Escherichia coli K-235 were separated by preparative slab-PAGE and recovered by utilizing the combined on-gel LPS reverse staining, extrusion, and passive elution techniques. As a result, 15 electrophoretically pure LPS fractions were obtained. The LPS content in the recovered fractions ranged from 280 ng (intermediate mobility glycoforms) to 411 mug (highest mobility glycoforms). The quantities of LPS fractions were sufficient to allow quantitation of the Limulus amebocyte lysate (LAL) activities of these distinct-molecular-mass LPS species, in the range from (1.1 +/- 0.1)x10(3) to (8.7 +/- 0.3)x10(5) endotoxin units (EU)/mL, by standard LAL assay. We have thus definitively demonstrated that slab-PAGE may be a suitable platform to more selectively purify individual glycoform fractions from smooth-type LPS.

Long-term stabilization of a new freeze-dried and albumin-free formulation of recombinant human interferon alpha 2b.

In this work, we evaluate the stability of a new freeze-dried and albumin-free formulation of recombinant human IFN alpha 2b (rhIFN-alpha2b) to be used in humans. The freeze-dried, albumin-free formulation was stored at the recommended temperature of 4 degrees C, and under accelerated storage conditions (28 degrees C). The stability of this product was also compared with the stability of a liquid albumin-free formulation of this cytokine. Finally, the stability of the freeze-dried albumin-free formulation was examined after reconstitution and storage at 4 degrees C and room temperature (28 degrees C) for 30 days. Samples were periodically subjected to biological activity assay (antiviral titration), reversed phase high-performance liquid chromatography (RP-HPLC), pyrogens, sterility and enzyme-linked immunosorbent assay (ELISA) testing, abnormal toxicity screening, organoleptic evaluation, and measurement of residual moisture and pH. Accelerated storage (28 degrees C) data for the freeze-dried albumin-free formulation showed biochemical stability of the active ingredient throughout the 6-month study, showing activity between 85 and 125% of its nominal value. RP-HPLC-determined purity showed that rhIFN-alpha2b remained above 95%. Additionally, the formulation was non-pyrogenic, non-toxic, sterile, and organoleptically acceptable. The real-time storage data confirmed the good biochemical long-term (30 months) stability of the freeze-dried formulation of this cytokine. Comparison with the liquid rhIFN-alpha2b albumin-free preparation showed that the freeze-dried albumin-free formulation maintained the stability of the active ingredient better than the liquid preparation. The formulation was also stable after reconstitution and storage at 4 degrees C and 28 degrees C, for 30 days.

Phase I clinical evaluation of a synthetic oligosaccharide-protein conjugate vaccine against Haemophilus influenzae type b in human adult volunteers.

Since 1989, we have been involved in the development of a vaccine against Haemophilus influenzae type b. The new vaccine is based on the conjugation of synthetic oligosaccharides to tetanus toxoid. Our main goals have been (i) to verify the feasibility of using the synthetic antigen and (ii) to search for new production alternatives for this important infant vaccine. Overall, eight trials have already been conducted with adults, children (4 to 5 years old), and infants. We have described herein the details from the first two phase I clinical trials conducted with human adult volunteers under double blind, randomized conditions. The participants each received a single intramuscular injection to evaluate safety and initial immunogenicity. We have found an excellent safety profile and an antibody response similar to the one observed for the control vaccine.

Some factors affecting the stability of interferon alpha 2b in solution.

In this paper we evaluated the influence of the protein concentration and a formulation vehicle on the stability of recombinant human Interferon alpha 2b (rhIFN-alpha2b) in solution. The effect of the protein content (from 1 to 100 MIU/ml) at 37 degrees C, showed that higher concentration of this cytokine protected against the loss of bioactivity (antiviral titration) better than the lower concentrations. In contrast, rhIFN-alpha2b at 50 and 100 MIU/ml decreased the SDS/PAGE- and RP-HPLC-determined purity faster than samples at 1 or 10 MIU/ml. According to these results, 10 MIU/ml rhIFN-alpha2b was the best choice to evaluate the influence of a formulation on the stability of this cytokine. Taking this into consideration, we studied the stability of a liquid and albumin-free formulation of this protein at the recommended storage temperature (5+/-3 degrees C) and under accelerated conditions (28+/-2 degrees C). Accelerated storage results showed an acceptable biochemical stability of the active ingredient throughout 2 months. Real-time storage data confirmed the good biochemical stability of this formulation for 30 months.