The effect of risankizumab on achieving minimal clinically important differences in patient-reported outcomes in patients with psoriatic arthritis: results from KEEPsAKE 1 and 2.

BACKGROUND: Psoriatic arthritis (PsA) is a chronic inflammatory disease that reduces the quality of life. This study assessed the effects of risankizumab (RZB) on the achievement of minimal clinically important differences (MCID) in patient-reported outcomes (PROs). METHODS: KEEPsAKE-1 and -2 are randomized, placebo-controlled Phase 3 clinical studies assessing RZB (150 mg) vs. placebo (PBO) in adult patients with PsA with inadequate response or intolerance to disease-modifying antirheumatic drugs and/or biologics. Patients were randomized 1:1 to receive RZB or PBO for 24 weeks; starting at Week 24, all patients received RZB 150 mg through Week 52. PROs assessed were Patient's Global Assessment of Disease Activity (PtGA), Patient's Assessment of Pain, Health Assessment Questionnaire-Disability Index (HAQ-DI), Short-Form 36 Physical and Mental Component Summary scores (PCS and MCS, respectively), 5-Level EQ-5D (EQ-5D-5L), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue), and Work Productivity and Activity Impairment (WPAI). The proportion of patients achieving MCID at Weeks 24 and 52 are reported. Odds ratios of achieving MCID with RZB treatment at Week 24, relative to PBO, were estimated by logistic regression controlling for baseline and stratification factors. RESULTS: In KEEPsAKE-1, RZB- vs. PBO-treated patients were more likely to report MCID in all PROs at Week 24; similar results were obtained in KEEPsAKE-2, except for SF-36 MCS and WPAI presenteeism domain. In KEEPsAKE-1 and KEEPsAKE-2, 65% and 62% of RZB-treated patients, respectively, reported MCID in PtGA at Week 24, which increased to 74% and 68%, respectively, at Week 52. Approximately 48% of all PBO-treated patients reported MCID in PtGA at Week 24 and, after initiating RZB, >65% reported MCID at Week 52. Results were similar in the remaining PROs. CONCLUSIONS: These data demonstrate that patients with PsA receiving RZB treatment are more likely to report clinically important improvements in PROs compared with patients receiving PBO.

tRNA-guanine transglycosylase from Escherichia coli: molecular mechanism and role of aspartate 89.

The enzyme tRNA-guanine transglycosylase (TGT, EC 2.4.2.29) catalyzes a posttranscriptional transglycosylation reaction involved in the incorporation of the modified base queuine [Q, 7-(4,5-cis-dihydroxy-2-cyclopenten-1-ylaminomethyl)-7-deazaguanine] into tRNA. Previously, the crystal structure of the TGT from Zymomonas mobilis was solved in complex with preQ(1) (the substrate for the eubacterial TGT) [Romier et al. (1996) EMBO J. 15, 2850-2857]. An aspartate residue at position 102 (position 89 in the Escherichia coli TGT) was proposed to play a nucleophilic role in an associative catalytic mechanism. Although this is an attractive and precedented mechanism, a dissociative mechanism is equally plausible. In a dissociative mechanism, aspartate 89 would provide electrostatic stabilization of an oxocarbenium ion intermediate that is formed by dissociation of guanine. To clarify the nature of the catalytic mechanism of TGT, we have generated and characterized four mutations of aspartate 89 in the E. coli TGT (alanine, asparagine, cysteine, and glutamate). All four mutant TGTs were able to noncovalently bind tRNA, but only the glutamate mutant was able to form a stable complex with the RNA substrate under denaturing conditions that was comparable to wild type. Furthermore, the glutamate mutant was the only mutant TGT that demonstrated significant activity. Kinetic parameters were determined for this enzyme and shown to be comparable to wild type, revealing that the enzyme is considerably tolerant of the positioning of the carboxylate. Under conditions of high enzyme concentrations and long time courses, the alanine, asparagine, and cysteine mutants showed very low levels (ca. 10(3)-fold lower than wild type) of activity that were linear with respect to enzyme concentration and dependent upon pH in a fashion similar to that of the wild type. However, the observed initial velocities were too low to accurately determine k(cat) and K(m) values. We hypothesize that the activity observed for these mutants is most likely derived from host strain TGT (wt) contamination. These results are most consistent with aspartate 89 acting as a nucleophile in an associative catalytic mechanism.

Lectin binding patterns to terminal sugars of rat lung alveolar epithelial cells.

We used post-embedding cytochemical techniques to investigate the lectin binding profiles of rat lung alveolar epithelial cells. Sections from rat lung embedded in the hydrophilic resin Lowicryl K4M were incubated either directly with a lectin-gold complex or with an unlabeled lectin followed by a specific glycoprotein-gold complex. The binding patterns of the five lectins used could be divided into three categories according to their reactivity with alveolar epithelial cells: (a) the Limax flavus lectin and Ricinus communis I lectin bound to both type I and type II cell plasma membranes; (b) the Helix pomatia lectin and Sambucus nigra L. lectin bound to type II but not type I cells; and (c) the Erythrina cristagalli lectin reacted with type I cells but was unreactive with type II cells. The specificity of staining was assessed by control experiments, including pre-absorption of the lectins with various oligosaccharides and enzymatic pre-treatment of sections with highly purified glycosidases to remove specific sugar residues. The results demonstrate that these lectins can be used to distinguish between type I and type II cells and would therefore be useful probes for investigating cell dynamics during lung development and remodeling.