A 12-week placebo-controlled study of rupatadine 10 mg once daily compared with cetirizine 10 mg once daily, in the treatment of persistent allergic rhinitis

BACKGROUND

With the current increasing incidence of allergies worldwide, new treatments showing efficacy and long term safety are needed for chronic conditions such as persistent allergic rhinitis (PER). New generation H1-antihistamines have demonstrated anti-allergic properties, which could possibly enhance their effectiveness in long-term periods of treatment.

OBJECTIVE

To investigate the efficacy of rupatadine, in controlling symptoms of PER over a 12-week period.

METHODS

A randomized, double blind, parallel-group, placebo-controlled study was carried out in patients aged older than 12 years with PER. Main inclusion criteria were: instantaneous total symptom score (i6TSS) >or=45, nasal obstruction score <or=12, and overall assessment of PER >or=2 as moderate during the first visit. The primary efficacy endpoint was the 12-week average change from baseline of the patients' i6TSS.

RESULTS

In all, 736 patients were selected. Of them, 543 (73.8%) were randomized in three different groups: placebo (n = 185), cetirizine (n = 175) and rupatadine (n = 183). Rupatadine (P = 0.008) but not cetirizine (P = 0.07) statistically reduced the baseline i6TSS vs placebo (47.8%, 44.7% and 38.8%, respectively), after 12 weeks. Onset of action was observed at the first 24 h for both treatments (rupatadine vs placebo, P = 0.013; cetirizine vs placebo, P = 0.015). Furthermore, instantaneous total nasal symptoms score (iTNSS) (including nasal blockage) mean change from baseline showed a significant reduction with rupatadine 10 mg in comparison with placebo, along all treatment duration of 12 weeks. Study treatments were well tolerated.

CONCLUSION

Rupatadine significantly relieves symptoms of PER, providing a rapid onset of action and maintains its effects over a long period of 12-weeks.

Collision Induced Unfolding Classifies Ligands Bound to the Integral Membrane Translocator Protein

Membrane proteins represent most current therapeutic targets, yet remain understudied due to their insolubility in aqueous solvents and generally low yields during purification and expression. Ion mobility-mass spectrometry and collision induced unfolding experiments have recently garnered attention as methods capable of directly detecting and quantifying ligand binding within a wide range of membrane protein systems. Despite prior success, ionized surfactant often creates chemical noise patterns resulting in significant challenges surrounding the study of small membrane protein-ligand complexes. Here, we present a new data analysis workflow that overcomes such chemical noise and then utilize this approach to quantify and classify ligand binding associated with the 36 kDa dimer of translocator protein (TSPO). Following our denoising protocol, we detect separate gas-phase unfolding signatures for lipid and protoporphyrin TSPO binders, molecular classes that likely interact with separate regions of the protein surface. Further, a detailed classification analysis reveals that lipid alkyl chain saturation levels can be detected within our gas-phase protein unfolding data. We combine these data and classification schemes with mass spectra acquired directly from liquid-liquid extracts to propose an identity for a previously unknown endogenous TSPO ligand.

Bicelles Rich in both Sphingolipids and Cholesterol and Their Use in Studies of Membrane Proteins

How the distinctive lipid composition of mammalian plasma membranes impacts membrane protein structure is largely unexplored, partly because of the dearth of isotropic model membrane systems that contain abundant sphingolipids and cholesterol. This gap is addressed by showing that sphingomyelin and cholesterol-rich (SCOR) lipid mixtures with phosphatidylcholine can be cosolubilized by n-dodecyl-β-melibioside to form bicelles. Small-angle X-ray and neutron scattering, as well as cryo-electron microscopy, demonstrate that these assemblies are stable over a wide range of conditions and exhibit the bilayered-disc morphology of ideal bicelles even at low lipid-to-detergent mole ratios. SCOR bicelles are shown to be compatible with a wide array of experimental techniques, as applied to the transmembrane human amyloid precursor C99 protein in this medium. These studies reveal an equilibrium between low-order oligomer structures that differ significantly from previous experimental structures of C99, providing an example of how ordered membranes alter membrane protein structure.

Collision-Induced Unfolding Differentiates Functional Variants of the KCNQ1 Voltage Sensor Domain

The KCNQ1 voltage-gated potassium channel regulates the repolarization of cardiac cells, and a plurality of point mutations in its voltage-sensing domain (VSD) are associated with toxic gain or loss of pore function, resulting in disease. As is the case with many disease-associated membrane proteins, there are hundreds of human variants of interest identified for KCNQ1; however, a significant portion of these variants have not been characterized in relation to their functional and disease associations. Additionally, as the VSD consists of four transmembrane helices, studies into dynamic structural differences among KCNQ1 VSD variants are hindered by the current limitations and deficits in the high-resolution structure determination of membrane proteins. Here, we use native ion mobility-mass spectrometry and collision-induced unfolding (CIU) to address the need for a high throughput-compatible method for the structural characterization of membrane protein variants of unknown significance using the KCNQ1 VSD as a model system. We perform CIU on wild-type and three mutant KCNQ1 VSD forms associated with the toxic gain or loss of function and show through both automated feature detection and comprehensive difference analysis of the CIU data sets that the variants are clearly grouped by function and disease association. We also construct a classification scheme based on the CIU data sets, which is able to differentiate the variant functional groups and classify a recently characterized variant to its correct grouping. Further, we probe the stability of the KCNQ1 VSD variants when liberated from C12E8 micelles at pH 8.0 and find preliminary evidence that the R231C mutation associated with the gain of the pore function is destabilized relative to the wild-type and loss of function variants.

Evaluation of Membrane Mimetics for the Native Ion Mobility─Mass Spectrometry Analysis of Membrane Proteins

Membrane protein (MP) structures and functions are intricately linked to their surrounding membrane environments and their respective lipid compositions in addition to influences exerted by unique membrane microdomains (i.e., lipid rafts). Owing to the complexity of their native environments, MPs pose significant challenges to structural biology due to their intrinsic hydrophobic nature rendering them incompatible with aqueous conditions commonly deployed during sample preparation. To overcome these solubility issues, MP studies commonly utilize detergent micelles. In recent years, numerous efforts have been directed toward developing membrane mimetics to facilitate successful solubilization and stabilization of MPs. Collision-induced dissociation (CID) can be employed to remove surrounding molecules from MPs during native mass spectrometry (nMS) experiments, and such methods can be used to evaluate previously inaccessible MPs. However, the differential effects of various membrane mimetics on MP structure and stability remain largely unexplored. In this study, we evaluate a range of MPs, including both transmembrane and monotopic variants, solubilized in detergent micelles, mixed lipid bicelles, and nanodisc mimetics. Our findings reveal significant differences in collision induced unfolding (CIU) features, stabilities, collision cross sections (CCS), and RMSD comparisons with values exceeding 26%. These results underscore the importance of considering the choice of membrane mimetics when studying MP structure.