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Summary: Carbamylation is a post‐translational modification that can be detected on a range of proteins, including immunoglobulin (Ig)G, in several clinical conditions. Carbamylated IgG (ca‐IgG) was reported to lose its capacity to trigger complement activation, but the mechanism remains unclear. Because C1q binds with high affinity to hexameric IgG, we analyzed whether carbamylation of IgG affects binding of C1q, hexamerization and complement‐dependent cytotoxicity (CDC). Synovial tissues of rheumatoid arthritis (RA) patients were analyzed for the presence of ca‐IgG in vivo. Synovial tissues from RA patients were analyzed for the presence of ca‐IgG using mass spectrometry (MS). Monomeric or hexameric antibodies were carbamylated in vitro and quality in solution was controlled. The capacity of ca‐IgG to activate complement was analyzed in enzyme‐linked immunosorbent (ELISAs) and cellular CDC assays. Using MS, we identified ca‐IgG to be present in the joints of RA patients. Using in vitro carbamylated antibodies, we observed that ca‐IgG lost its capacity to activate complement in both solid‐phase and CDC assays. Mixing ca‐IgG with non‐modified IgG did not result in effective inhibition of complement activation by ca‐IgG. Carbamylation of both monomeric IgG and preformed hexameric IgG greatly impaired the capacity to trigger complement activation. Furthermore, upon carbamylation, the preformed hexameric IgG dissociated into monomeric IgG in solution, indicating that carbamylation influences both hexamerization and C1q binding. In conclusion, ca‐IgG can be detected in vivo and has a strongly reduced capacity to activate complement which is, in part, mediated through a reduced ability to form hexamers. [ABSTRACT FROM AUTHOR] more...

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The production, processing, and application of aliphatic isocyanate (NCO)-based thermosets such as polyurethane coatings and adhesives are generally limited by the surprisingly high viscosity of tri-functionality and higher-functionality isocyanurates. These compounds are essential crosslinking additives for network formation. However, the mechanism by which these high viscosities are caused is not yet understood. In this work, model aliphatic isocyanurates were synthesized and isolated in high purity (>99%), and their viscosities were accurately determined. It was shown that the presence of the NCO group has a strong influence on the viscosity of the system. From density functional theory calculations, a novel and significant bimolecular binding potential of −8.7 kJ/mol was identified between NCO groups and isocyanurate rings, confirming the important role of the NCO group. This NCO-to-ring interaction was proposed to be the root cause for the high viscosities observed for NCO-functional isocyanurate systems. Molecular dynamics simulations carried out to further confirm this influence also suggest that the NCO-to-ring interaction causes a significant additional contribution to viscosity. Finally, model functional isocyanurates were further reacted into densely crosslinked polyisocyanurate networks which showed interesting material properties. Copyright © 2016 The Authors Polymers for Advanced Technologies published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...

To cite this article: Gschwandtner M, Rossbach K, Dijkstra D, Bäumer W, Kietzmann M, Stark H, Werfel T, Gutzmer R. Murine and human Langerhans cells express a functional histamine H4script> receptor: modulation of cell migration and function. Allergy 2010; 65: 840–849. Background: Histamine is an important mediator of allergic reactions, and recent studies indicated that the function of different types of antigen presenting cells (APC) can be modulated by histamine, in particular via the newly described histamine H4 receptor (H4R). Therefore, we investigated possible interactions of histamine via the H4R on Langerhans cells (LC), which represent the professional APC in the skin and therefore have an important role in the initiation and maintenance of allergic skin diseases. Methods: The expression of the H4R was evaluated by real-time PCR, flow cytometry and immunofluorescence staining. The function of the H4R was determined by intracellular flow cytometric measurement of chemokine production and LC migration assays. Results: Here, we show H4R expression on in vitro generated monocyte-derived LC (mRNA and protein) and on primary LC from murine and human skin samples (protein). The immunofluorescence staining in murine and human skin samples clearly proved that LC express the H4R in situ. Stimulation with histamine or a H4R agonist downregulated the chemokine (C-C motif) ligand 2 (CCL2) in human monocyte-derived LC and primary LC. Prestimulation with a selective H4R antagonist abolished this effect. Moreover, migration of LC from the epidermis was increased after H4R agonist stimulation in ex vivo migration assays using human epidermis and murine in vivo assays. Conclusion: Our findings show that LC express a functional H4R and point towards a possible pathogenic relevance of the H4R in inflammatory and allergic diseases. [ABSTRACT FROM AUTHOR] more...

Background: Dendritic cells (DC) are the major antigen-presenting cells and play a key role in adaptive immunity as they are able to activate naive T cells. It was recently described, that the histamine H4 receptor (H4R) is present on human monocyte-derived DC and that chemotaxis and T-helper (Th)1–Th2 polarization is mediated by this receptor. However, the distribution of histamine receptors on murine DC has not been studied yet. Methods: The histamine receptor expression on murine bone marrow (BM)-derived DC and effects of histamine and H4R agonism on DC migration through skin were studied. As it was demonstrated in scratching experiments that NMRI mice are more susceptible to H4R-mediated itch than BALB/c mice, DC function of NMRI and BALB/c mice was compared. Results: The mRNA of the H1R, H2R and H4R could be detected in murine BM-derived DC, while mRNA of the H3R was found to be low or undetectable. There were no distinct differences in mRNA expression and in H4R protein level (flow cytometry) between NMRI compared with BALB/c mice indicating, that a higher susceptibility is not associated with a generally higher H4R expression in all cell types. Histamine as well as the H4R agonist clobenpropit induced an enhanced chemotaxis in the skin DC migration assay. The enhanced chemotaxis was blocked by the H4R antagonist JNJ7777120. This finding was confirmed by in vitro migration experiments with BM-derived DC. Conclusion: Referring to DC migration, blocking the H4R on inflammatory cells might be a promising anti-inflammatory, immunomodulatory strategy. [ABSTRACT FROM AUTHOR] more...

The in vitro glucuronidation of seven monohydroxy-2-aminotetralins and two naphthoxazines has been determined using human and rat liver microsomes. All these compounds stimulate the D2ubscript> dopamine receptor. The influence of the position of the phenolic hydroxyl group was studied with rat microsomes in monohydroxy-2-(N,N-dipropylamino)-tretralins. The highest activity and intrinsic clearance was found for 7-OH-DPAT, but the latter values for 5-OH-DPAT and 6-OH-DPAT were much lower by a factor of 9 and 30, respectively. The 8-OH-isomer was not glucuronidated at all. Substitution of a propyl side chain by a thienylethyl-, or phenylethyl side chain, in 5-hydroxy-DPAT, or in (+)-4-propyl-9-hydroxyhexahydronaphthoxazine (PHNO, N-0500), showed a large increase of the UDPGT affinity and intrinsic clearance especially for N-0437. It also resulted for N-0437 in a much higher affinity towards the dopaminergic D2 receptor. Although the glucuronidation activity of human microsomes was found to be considerably lower than that of rat microsomes, the latter phenomenon was clearly visible with human microsomes as well. These findings may have serious implications for the ability of these drugs to adequately reach the brain. [ABSTRACT FROM AUTHOR] more...