Anti-CXCL8 (aa 21-99) polyclonal antibody

The aim of this work was to investigate the complex phenomena underlying the adsorption of an anti-human IL-8 (anti-IL8) monoclonal antibody (mAb) to m-aminophenylboronate (m-APBA) by Flow Microcalorimetry (FMC) and to understand the role of non-specific interactions in the adsorption process. FMC was exploited as a dynamic on-line method to measure instantaneous heat energy transfers in order to understand the surface phenomena underlying mAb's adsorption towards the synthetic ligand m-APBA under different pH (7.5, 8.5, 9.0, 9.5 and 10.0) and salt concentrations (0 and 150 mM NaCl). Results showed that the adsorption of anti-IL8 mAb to m-APBA is enthalpically driven (Delta H-ads<0), as expected for the predominant reversible esterification reaction between boronates and cis-diolscontaining molecules. For all the pH conditions studied, thermograms presented a first exothermic peak, characteristic of the reversible esterification reaction between mAb (pI >= 9.3) and m-APBA (pKa = 8.8), except at pH 9.0 in the presence of 150 mM NaCI, for which the thermogram presented a first endothermic peak. The heat of adsorption (Delta H-ads) obtained at conditions where cis-diol interactions were predominant was approximately -243 + 38 kiimol against -82 +/- 14 kJ/mol (p-value < 0.05) obtained at pH 9.0 with 150 mM NaCl. The observed shift in the thermogram profile at pH 9.0, 150 mM NaCl, and the consequent decrease of 60-70% in Delta H-ads were indicative of the promotion of electrostatic interactions between the protein and the ligand. Overall, and whereas the binding of the PBA ligand to mAb molecules has been described for decades as being affinity-based, our study demonstrates the multimodal behaviour of this interaction and contributes towards the understanding of the adsorption thermodynamics. (C) 2018 Elsevier B.V. All rights reserved.

Objective: Viscosupplementation has been used for decades to treat mild to moderate osteoarthritis, yet it is unknown if the lubricating function of different pathological synovial fluids (SF) vary, or if they respond differentially to viscosupplementation. The objectives of this study were to (i) evaluate the friction coefficients and induced shear strains in articular cartilage when lubricated with pathological SF, (ii) identify the effect of hyaluronic acid (HA) supplementation on friction coefficients and shear strains, and (iii) identify SF biomarkers that correlate with lubricating function. Method: Human pathological SF was grouped by white blood cell count (inflammatory: >2000 cells/mm(3), n = 6; non-inflammatory: < 2000 cells/mm(3), n = 6). Compositional analyses for lubricin and cytokines were performed. Friction coefficients and local tissue shear strain measurements were coupled using new, microscale rheological analyses by lubricating neonatal bovine cartilage explants with SF alone and in a 1:1 ratio with HA (Hymovis (R)). Results: Friction coefficients were not significantly different between the inflammatory and non-inflammatory pathologies (p = 0.09), and were poorly correlated with peak tissue strains at the cartilage articular surface (R-2 = 0.34). A subset of inflammatory SF samples induced higher tissue strains, and HA supplementation was most effective at lowering friction and tissue strains in this inflammatory subset. Across all pathologies there were clear relationships between polymorphonuclear neutrophil (PMN), IL8, and lubricin concentrations with cartilage tissue strains. Conclusion: These results suggest that pathological SF is characterized by distinct tribological endotypes where SF lubricating behaviors are differentially modified by viscosupplementation and are identifiable by biomarkers. (C) 2020 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.