Elevated IL-1β and Comparable IL-1 Receptor Antagonist Levels Are Characteristic Features of L-PRP in Female College Athletes Compared to Male Professional Soccer Players

Autologous platelet-rich plasma (PRP) therapy has been becoming popular for the treatment of musculotendinous injuries among athletes. However, for individual and practical variations, clinical success is hardly predictable. To overcome this difficulty, we have been exploring possible criterion candidates for monitoring its clinical effectiveness. In this study, we focused on sex-based differences in young elite athletes and compared the biochemical compositions of their PRP. Leukocyte-rich PRP (L-PRP) was manually prepared from blood samples collected from male professional soccer players (mPSPs) (n = 25) and female college athletes (fCAs) (n = 36). Platelet-derived growth factor-BB (PDGF-BB), transforming-growth factor-β1 (TGFβ1), platelet factor-4 (PF4), interleukin-1β (IL-1β), and IL-1 receptor antagonist (IL-1RA) were quantified using an enzyme-linked immunosorbent assay. The levels of PDGF-BB, TGFβ1, and PF4 in L-PRP were significantly higher in mPSPs than in fCAs. Conversely, IL-1β and IL-1RA were detected at significantly and slightly higher levels, respectively, in fCAs than in mPSPs. Our findings suggest that, even though L-PRP from fCAs may have lower potential to induce cell growth and differentiation than that of mPSPs, due to the latter's higher capacity to control inflammation, it does not necessarily imply that PRP treatment in fCAs is less effective. Thus, these cytokine levels should be checked before PRP therapy.

Anti-inflammatory effect of IL-1ra-loaded dextran/PLGA microspheres on Porphyromonas gingivalis lipopolysaccharide-stimulated macrophages in vitro and in vivo in a rat model of periodontitis

Periodontitis is a multifactorial chronic infectious disease leading to a host immune response involving inflammatory cytokines, especially IL-1β, which is the main reason for further developing this disease. IL-1 receptor antagonist (IL-1ra) binds IL-1 receptor, inhibiting IL-1β signaling and reducing the levels of other cytokines closely related to periodontitis, such as IL-6 and TNF-α. Therefore, the use of IL-1ra to inhibit periodontitis development in a system, ensuring its sustained release, might be an effective way to combat this disease. Hence, in this study, a novel IL-1ra-loaded dextran/PLGA microsphere was developed to allow the sustained release of IL-1ra and enhance the anti-inflammatory properties. Therefore, this study's purposes were to develop a novel periodontal treatment for inhibition and treatment of periodontitis and evaluate the sustained-release effect and anti-inflammatory properties of IL-1ra-loaded dextran/PLGA microspheres in vitro by cell experiments and in vivo by animal experiments. The results showed that IL-1ra-loaded dextran/PLGA microspheres were non-toxic both in vitro and in vivo and could be used as a safe and effective treatment. In addition, these microspheres could significantly prolong the half-life of IL-1ra drug, exerting a useful anti-inflammatory effect in macrophages stimulated with P. gingivalis lipopolysaccharide and in rats with periodontitis. In conclusion, IL-1ra-loaded dextran/PLGA microsphere might be a useful tool to combat periodontal disease.

Nanobubbles in Reconstituted Lyophilized Formulations: Interaction With Proteins and Mechanism of Formation

Reconstitution of lyophilized disaccharide formulations results in the formation of nanosized air bubbles that persist in suspension for weeks. If proteins are present, interactions with nanobubbles may cause loss of monomeric protein and formation of subvisible particles. The goals of this work are to determine the mechanism(s) by which nanobubbles form in reconstituted lyophilized formulations and to develop strategies for reducing nanobubble generation. We hypothesize that nanobubbles are created from nanosized gas pockets within lyophilized solids, which become bubbles when the surrounding matrix is dissolved away during reconstitution. Nanosized voids may originate from small ice crystals formed within the concentrated liquid during freezing that subsequently sublime during drying. Nanobubble concentrations are correlated with the extent of mannitol crystallization during freezing. Nanosized ice crystals, induced by the release of water during mannitol crystallization, were responsible for nanobubble formation. The presence of trehalose or sucrose, in formulations with low mannitol concentrations, inhibited excipient crystallization during lyophilization and reduced nanobubble levels following reconstitution. Our results show a correlation between nanobubble formation and concentrations of insoluble IL-1ra aggregates, suggesting that minimizing nanobubble generation may be an effective strategy for reducing protein aggregation following reconstitution.

Inflammatory 'double hit' model of temporomandibular joint disorder with elevated CCL2, CXCL9, CXCL10, RANTES and behavioural hypersensitivity in TNFR1/R2-/- mice

BACKGROUND

Patients with temporomandibular joint disorders (TMD), reactive arthritis and rheumatoid arthritis often have combined etiology of hereditary and microenvironmental factors contributing to joint pain. Multiple clinical and animal studies indicate 'double-hit' inflammatory insults can cause chronic inflammation. The first inflammatory insult primes the immune system and subsequent insults elicit amplified responses. The present 'double hit' study produced a chronic orofacial pain model in mice with genetic deletion of both TNFα receptors (TNFR1/R2-/-), investigating the main nociceptive signalling pathways in comparisons to wild type mice.

METHODS

An initial inflammatory insult was given unilaterally into the temporomandibular joint (TMJ). Secondary hypersensitivity was tested on the skin over the TMJ throughout the experiment. Three weeks later after complete reversal of hypersensitivity, a second inflammatory insult was imposed on the colon. Pharmacological interventions were tested for efficacy after week 10 when hypersensitivity was chronic in TNFR1/R2-/- mice. Serum cytokines were analysed at Days 1, 14, and Week 18.

RESULTS

The double hit insult produced chronic hypersensitivity continuing through the 4-month experimental timeline in the absence of TNFα signalling. P2X7 and NMDA receptor antagonists temporarily attenuated chronic hypersensitivity. Serum cytokine/chemokine analysis on Day 14 when CFA induced hypersensitivity was resolved identified increased levels of pro-inflammatory cytokines CCL2, CXCL9, CXCL10, RANTES and decreased levels of anti-inflammatory cytokines IL-1ra and IL-4 in TNFR1/R2-/- compared to WT mice.

CONCLUSIONS

These data suggest a causal feed-forward signalling cascade of these little studied cytokines have the potential to cause recrudescence in this orofacial inflammatory pain model in the absence of TNFα signalling.

SIGNIFICANCE

Using a mouse model of chronic inflammatory temporomandibular joint disorder, we determined that absence of functional TNFR1/R2 induces aberrant inflammatory signalling caused by other increased pro-inflammatory and decreased anti-inflammatory cytokines that could serve as blood biomarkers and may predict disease progression.

Effects of phosphorylatable short peptide-conjugated chitosan-mediated IL-1Ra and igf-1 gene transfer on articular cartilage defects in rabbits

Previously, we reported an improvement in the transfection efficiency of the plasmid DNA-chitosan (pDNA/CS) complex by the utilization of phosphorylatable short peptide-conjugated chitosan (^pSP-CS). In this study, we investigated the effects of ^pSP-CS-mediated gene transfection of interleukin-1 receptor antagonist protein (IL-1Ra) combined with insulin-like growth factor-1 (IGF-1) in rabbit chondrocytes and in a rabbit model of cartilage defects. pBudCE4.1-IL-1Ra+igf-1, pBudCE4.1-IL-1Ra and pBudCE4.1-igf-1 were constructed and combined with ^pSP-CS to form pDNA/^pSP-CS complexes. These complexes were transfected into rabbit primary chondrocytes or injected into the joint cavity. Seven weeks after treatment, all rabbits were sacrificed and analyzed. High levels of IL-1Ra and igf-1 expression were detected both in the cell culture supernatant and in the synovial fluid. In vitro, the transgenic complexes caused significant proliferation of chondrocytes, promotion of glycosaminoglycan (GAG) and collagen II synthesis, and inhibition of chondrocyte apoptosis and nitric oxide (NO) synthesis. In vivo, the exogenous genes resulted in increased collagen II synthesis and reduced NO and GAG concentrations in the synovial fluid; histological studies revealed that pDNA/^pSP-CS treatment resulted in varying degrees of hyaline-like cartilage repair and Mankin score decrease. The co-expression of both genes produced greater effects than each single gene alone both in vitro and in vivo. The results suggest that ^pSP-CS is a good candidate for use in gene therapy for the treatment of cartilage defects and that igf-1 and IL-1Ra co-expression produces promising biologic effects on cartilage defects.

Conformation and Side Chains Environments of Recombinant Human Interleukin-1 Receptor Antagonist (rh-IL-1ra) Probed by Raman, Raman Optical Activity, and UV-Resonance Raman Spectroscopy

The conformation and local environments of the side chains cysteines and aromatics of recombinant human interleukin-1 receptor antagonist (rh-IL-1ra) have been studied by visible Raman, Raman optical activity (ROA) and UVRR spectroscopy. The results reveal that the secondary structure of rh-IL-1ra is predominantly beta-sheet, which is consistent with conclusions from multinuclear NMR in solutions and X-ray diffraction analysis of crystals. It confirms that all four cysteines are in reduced state. Three cysteines are not hydrogen bonded and exposed. One cysteine is moderately hydrogen bonded and buried. This explains the earlier observation that only three cysteines were detectable using DTNB titration. No characteristic Raman band of disulfide bond was observed in the Raman spectra of rh-IL-1ra in both solution and in crystals. It rules out the supposition that there is one disulfide bond in rh-IL-1ra crystals based on X-ray diffraction. Raman and UVRR spectra of rh-IL-1ra exhibit canonical marker bands of tryptophan. They do not support the proposal that there is cation-pi interaction involving tryptophans in solutions and crystals. These results demonstrate that Raman spectroscopy offers certain advantages over X-ray diffraction for studies of detailed local environment and intermolecular interactions of side chains of proteins in solution and in crystals.

Measurement of the second osmotic virial coefficient for protein solutions exhibiting monomer-dimer equilibrium

The second osmotic virial coefficient (B) is a measure of solution nonideality that is useful for predicting conditions favorable for protein crystallization and for inhibition of aggregation. Static light scattering is the technique most commonly used to determine B values, typically using protein concentrations less than 5 mg/mL. During static light scattering experiments at low protein concentrations, frequently the protein is assumed to exist either as a single nonassociating species or as a combination of assembly states independent of protein concentration. In the work described here, we examined the limit for ignoring weak reversible dimerization (Kd > or =1 mM) by comparing B values calculated with and without accounting for self-association. Light scattering effects for equilibrium dimer systems with Kd <20 mM and Kd <1 mM will significantly affect apparent B values measured for 20 and 150-kDa proteins, respectively. To interpret correctly light scattering data for monomer-dimer equilibrium systems, we use an expanded coefficient model to account for separate monomer-monomer (B(22)), monomer-dimer (B(23)), and dimer-dimer (B(33)) interactions.

The fine transformation between the oxidized and reduced forms of interleukin-1 receptor antagonist

The active and pure recombinant forms of human interleukin-1 receptor antagonist (rHIL-1ra) were obtained from inclusion body expressed in Escherichia coli BL21 (DE3). However, the final purified protein was found to be in an unstable reduced form and easily converted to the other forms. Which form of the protein was involved and precisely how this occurred remained obscure. Therefore, we changed oxidizing and reducing conditions to delineate the subtle change between the reduced and oxidized states of rHIL-1ra based on high-pressure liquid chromatography (HPLC). The fine transformation between the two states was further verified through matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectroscopy. Meanwhile, which form might be beneficial to the protein was also investigated by testing its full bioactivity based upon methyl thiazolyl tetrazolium (MTT) method.

Sustained delivery of IL-1 Ra from biodegradable microspheres reduces the number of murine B16 melanoma lung metastases

The interleukin-1 receptor antagonist (IL-1Ra) is approved for treating rheumatoid arthritis and has the potential to treat metastatic cancers involving excess amounts of the pro-inflammatory cytokine, interleukin-1 beta (IL-1). To maintain sustained delivery and improve its therapeutic efficacy, IL-1Ra was encapsulated with stabilizers in biodegradable poly-(lactic/glycolic acid) (PLGA) microspheres. In vitro cytokine release and bioactivity studies in cultured melanoma B16 cells revealed the microspheres to be capable of sustained IL-1Ra release on a daily level that could inhibit cell proliferation for at least 7 days. The level of IL-1Ra released from the microspheres was revealed in rat serum. Significant amounts of IL-1Ra were released over the course of 2 weeks, at levels sufficient for the inhibition of exogenously-administered IL-1 beta. In mice injected with B16 melanoma cells, the sustained IL-1Ra delivery from biodegradable microspheres inhibited tumor growth and significantly prolonged mice survival. Furthermore, the tumors were less vascularized and after amputation of the primary tumor, the number of lung metastases was reduced by 70%, as compared to the control groups. Thus, we show that biodegradable microspheres represent an efficient system for sustaining IL-1Ra delivery and improving its therapeutic efficacy. As such, the system can be integrated into therapeutic protocols for treating metastatic cancers.

Investigation on PEGylation strategy of recombinant human interleukin-1 receptor antagonist

Although PEGylation is a potential approach to prolong the half-lives and reduce the dosing frequency of therapeutic proteins, conjugation behaviors of polymer have pivotal effects on the remaining bioactivities of the derivatives. In this study, the PEGylation strategy of recombinant human interleukin-1 receptor antagonist was investigated. The random conjugation of polyethylene glycol to amino groups on the protein resulted in a severe loss of activity and only retained 9.8% of the activity. In contrast, the PEGylation at the thiol groups had moderate effects on the bioactivity of protein and 40% of activity was conserved. The results suggested that the thiol-target PEGylation was more beneficial for IL-1ra.

Oxidation of Methionine Residues in Recombinant Human Interleukin-1 Receptor Antagonist: Implications of Conformational Stability on Protein Oxidation Kinetics

Oxidation of methionine residues is involved in several biochemical processes and in degradation of therapeutic proteins. The relationship between conformational stability and methionine oxidation in recombinant human interleukin-1 receptor antagonist (rhIL-1ra) was investigated to document how thermodynamics of unfolding affect methionine oxidation in proteins. Conformational stability of rhIL-1ra was monitored by equilibrium urea denaturation, and thermodynamic parameters of unfolding (DeltaGH2O, m, and Cm) were estimated at different temperatures. Methionine oxidation induced by hydrogen peroxide at varying temperatures was monitored during "coincubation" of rhIL-1ra with peptides mimicking specific regions of the reactive methionine residues in the protein. The coincubation study allowed estimation of oxidation rates in protein and peptide at each temperature from which normalized oxidation rate constants and activation energies were calculated. The rate constants for buried Met-11 in the protein were lower than for methionine in the peptide with an associated increase in activation energy. The rate constants and activation energy of solvent exposed methionines in protein and peptide were similar. The results showed that conformational stability, monitored using the Cm value, has an effect on oxidation rates of buried methionines. The rate constant of buried Met-11 correlated well with the Cm value but not DeltaGH2O. No correlation was observed for the oxidation rates of solvent-exposed methionines with any thermodynamic parameters of unfolding. The findings presented have implications in protein engineering, in design of accelerated stability studies for protein formulation development, and in understanding disease conditions involving protein oxidation.

Biophysical Characterization of Structural Properties and Folding of Interleukin-1 Receptor Antagonist

Structural properties and folding of interleukin-1 receptor antagonist (IL-1ra), a therapeutically important cytokine with a symmetric beta-trefoil topology, are characterized using optical spectroscopy, high-resolution NMR, and size-exclusion chromatography. Spectral contributions of two tryptophan residues, Trp17 and Trp120, present in the wild-type protein, have been determined from mutational analysis. Trp17 dominates the emission spectrum of IL-1ra, while Trp120 is quenched presumably by the nearby cysteine residues in both folded and unfolded states. The same Trp17 gives rise to two characteristic negative peaks in the aromatic CD. Urea denaturation of the wild-type protein is probed by measuring intrinsic and extrinsic (binding of 1-anilinonaphthalene-8-sulfonic acid) fluorescence, near- and far-UV CD, and 1D and 2D ((1)H-(15)N heteronuclear single quantum coherence (HSQC)) NMR. Overall, the data suggest an essentially two-state equilibrium denaturation mechanism with small, but detectable structural changes within the pretransition region. The majority of the (1)H-(15)N HSQC cross-peaks of the folded state show only a limited chemical shift change as a function of the denaturant concentration. However, the amide cross-peak of Leu31 demonstrates a significant urea dependence that can be fitted to a two-state binding model with a dissociation constant of 0.95+/-0.04 M. This interaction has at least a five times higher affinity than reported values for nonspecific urea binding to denatured proteins and peptides, suggesting that the structural context around Leu31 stabilizes the protein-urea interaction. A possible role of denaturant binding in inducing the pretransition changes in IL-1ra is discussed. Urea unfolding of wild-type IL-1ra is sufficiently slow to enable HPLC separation of folded and unfolded states. Quantitative size-exclusion chromatography has provided a hydrodynamic view of the kinetic denaturation process. Thermodynamic stability and unfolding kinetics of IL-1ra resemble those of structurally and evolutionary close IL-1beta, suggesting similarity of their free energy landscapes.

Structural differences between the putative carbohydrate-recognition domains of human IL-1 alpha, IL-1 beta and IL-1 receptor antagonist obtained by in silico modeling

In a previous report (Cebo et al. J Biol Chem 276 (2001) 5685-5691), it was established that biologically active recombinant human IL-1alpha and IL-1beta had different carbohydrate-binding properties. IL-1alpha recognized a di-antennary N-glycan with two alpha2-3-linked sialic acid residues, whereas IL-1beta recognized the GM(4), a alpha2-3-linked sialylated glycosphingolipid. These different carbohydrate-binding properties of two interleukins binding to the same receptor (IL-1R) could explain why these molecules had different biological effects and cell specificities. Molecular modeling of the ligands and in silico docking experiments defined putative carbohydrate-recognition domains localized in the same area of the two molecules, a domain different from that defined as the type I IL-1R binding domain. The calculated pattern of hydrogen bonding and of van der Waals interactions fulfilled the essential features observed for calcium-independent lectins (mammalian, viral or bacterial). The analysis of the same domain of the third members of this family of molecules, the IL-1R-antagonist, indicated it did not fulfill the criteria for carbohydrate-recognition domains. It is proposed that its role as a pure antagonist is due to the absence of lectin activity and consequently explained its inability to associate IL-1R with other surface molecular complexes necessary for signaling.

Specific volume and adiabatic compressibility measurements of native and aggregated recombinant human interleukin-1 receptor antagonist: Density differences enable pressure-modulated refolding

High hydrostatic pressures have been used to dissociate non-native protein aggregates and foster refolding to the native conformation. In this study, partial specific volume and adiabatic compressibility measurements were used to examine the volumetric contributions to pressure-modulated refolding. The thermodynamics of pressure-modulated refolding from non-native aggregates of recombinant human interleukin-1 receptor antagonist (IL-1ra) were determined by partial specific volume and adiabatic compressibility measurements. Aggregates of IL-1ra formed at elevated temperatures (55 degrees C) were found to be less dense than native IL-1ra and refolded at 31 degrees C under 1,500 bar pressure with a yield of 57%. Partial specific adiabatic compressibility measurements suggest that the formation of solvent-free cavities within the interior of IL-1ra aggregates cause the apparent increase in specific volume. Dense, pressure-stable aggregates could be formed at 2,000 bar which could not be refolded with additional high pressure treatment, demonstrating that aggregate formation conditions and structure dictate pressure-modulated refolding yields.