Long-term evaluation of response to omalizumab therapy in real life by a novel multimodular approach: The Real-life Effectiveness of Omalizumab Therapy (REALITY) study.

BACKGROUND: The evidence on long-term real-life response measures to omalizumab therapy in moderate to severe asthma is limited. A universal assessment tool is needed to adequately evaluate response to omalizumab in these patients. OBJECTIVE: To design a multimodular response assessment tool and use it to measure and define response to omalizumab therapy in real-world settings. METHODS: The Real-life Effectiveness of Omalizumab Therapy (REALITY) study is a retrospective, long-term, real-life clinical study that evaluates response in individuals with allergic asthma who received omalizumab between 2004 and 2011. The Standardized Measure to Assess Response to Therapy (SMART) tool was designed to define response (1 year before to after treatment) by 3 modules: (1) physician's subjective assessment of asthma symptoms and control; (2) objective assessment of 6 parameters: improvement by 50% or more for asthma exacerbation, steroid bursts, emergency department visits, and hospitalizations; increase in forced expiratory volume in 1 second of 200 mL or greater; and improved Asthma Control Test score of 3 or higher; -and (3) true responders (patient meeting both module 1 and 2 criteria). Response was assessed and compared for 3 modules at desired time points. RESULTS: A total of 198 patients (mean age, 31.7 years [range, 3-77 years]; 98 [49%] female; mean omalizumab therapy duration, 2.49 years [range, 3 months to 8 years]; mean omalizumab dosage, 473 mg every 4 weeks; median baseline IgE level, 433 IU/mL) were included in this analysis. Overall visit adherence was 78%, although the adherence rate decreased annually by 20%. Response rates assessed by SMART modules were 61.3%, 60.8%, and 41.8% at 16 weeks, 84.8%, 72.2%, and 64.6% at 1 year, 82.4%, 71.2%, and 63.2% at 2 years, and 95.1%, 87.8%, and 85.4% at 5 years for modules 1, 2, and 3, respectively. There were no significant adverse reactions. CONCLUSION: The REALITY study has demonstrated long-term effectiveness of omalizumab therapy in individuals with allergic asthma in real-life settings. The SMART tool is promising as a potential standard assessment tool to measure and define response to asthma therapy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01776177.

Multiple polymer architectures of human polyhomeotic homolog 3 sterile alpha motif.

The self-association of sterile alpha motifs (SAMs) into a helical polymer architecture is a critical functional component of many different and diverse array of proteins. For the Drosophila Polycomb group (PcG) protein Polyhomeotic (Ph), its SAM polymerization serves as the structural foundation to cluster multiple PcG complexes, helping to maintain a silenced chromatin state. Ph SAM shares 64% sequence identity with its human ortholog, PHC3 SAM, and both SAMs polymerize. However, in the context of their larger protein regions, PHC3 SAM forms longer polymers compared with Ph SAM. Motivated to establish the precise structural basis for the differences, if any, between Ph and PHC3 SAM, we determined the crystal structure of the PHC3 SAM polymer. PHC3 SAM uses the same SAM-SAM interaction as the Ph SAM sixfold repeat polymer. Yet, PHC3 SAM polymerizes using just five SAMs per turn of the helical polymer rather than the typical six per turn observed for all SAM polymers reported to date. Structural analysis suggested that malleability of the PHC3 SAM would allow formation of not just the fivefold repeat structure but also possibly others. Indeed, a second PHC3 SAM polymer in a different crystal form forms a sixfold repeat polymer. These results suggest that the polymers formed by PHC3 SAM, and likely others, are dynamic. The functional consequence of the variable PHC3 SAM polymers may be to create different chromatin architectures.

The growth-suppressive function of the polycomb group protein polyhomeotic is mediated by polymerization of its sterile alpha motif (SAM) domain.

Polyhomeotic (Ph), a member of the Polycomb Group (PcG), is a gene silencer critical for proper development. We present a previously unrecognized way of controlling Ph function through modulation of its sterile alpha motif (SAM) polymerization leading to the identification of a novel target for tuning the activities of proteins. SAM domain containing proteins have been shown to require SAM polymerization for proper function. However, the role of the Ph SAM polymer in PcG-mediated gene silencing was uncertain. Here, we first show that Ph SAM polymerization is indeed required for its gene silencing function. Interestingly, the unstructured linker sequence N-terminal to Ph SAM can shorten the length of polymers compared with when Ph SAM is individually isolated. Substituting the native linker with a random, unstructured sequence (RLink) can still limit polymerization, but not as well as the native linker. Consequently, the increased polymeric Ph RLink exhibits better gene silencing ability. In the Drosophila wing disc, Ph RLink expression suppresses growth compared with no effect for wild-type Ph, and opposite to the overgrowth phenotype observed for polymer-deficient Ph mutants. These data provide the first demonstration that the inherent activity of a protein containing a polymeric SAM can be enhanced by increasing SAM polymerization. Because the SAM linker had not been previously considered important for the function of SAM-containing proteins, our finding opens numerous opportunities to manipulate linker sequences of hundreds of polymeric SAM proteins to regulate a diverse array of intracellular functions.

Human polyhomeotic homolog 3 (PHC3) sterile alpha motif (SAM) linker allows open-ended polymerization of PHC3 SAM.

Sterile alpha motifs (SAMs) are frequently found in eukaryotic genomes. An intriguing property of many SAMs is their ability to self-associate, forming an open-ended polymer structure whose formation has been shown to be essential for the function of the protein. What remains largely unresolved is how polymerization is controlled. Previously, we had determined that the stretch of unstructured residues N-terminal to the SAM of a Drosophila protein called polyhomeotic (Ph), a member of the polycomb group (PcG) of gene silencers, plays a key role in controlling Ph SAM polymerization. Ph SAM with its native linker created shorter polymers compared to Ph SAM attached to either a random linker or no linker. Here, we show that the SAM linker for the human Ph ortholog, polyhomeotic homolog 3 (PHC3), also controls PHC3 SAM polymerization but does so in the opposite fashion. PHC3 SAM with its native linker allows longer polymers to form compared to when attached to a random linker. Attaching the PHC3 SAM linker to Ph SAM also resulted in extending Ph SAM polymerization. Moreover, in the context of full-length Ph protein, replacing the SAM linker with PHC3 SAM linker, intended to create longer polymers, resulted in greater repressive ability for the chimera compared to wild-type Ph. These findings show that polymeric SAM linkers evolved to modulate a wide dynamic range of SAM polymerization abilities and suggest that rationally manipulating the function of SAM containing proteins through controlling their SAM polymerization may be possible.

Prodan fluorescence mimics the GroEL folding cycle.

The non-covalent fluorescent probe 6-propionyl-2-(dimethylamino) naphthalene sulfonate (prodan) binds to hydrophobic surfaces exposed on the surface of GroEL. Under identical experimental conditions free prodan exhibits a green emission peak of intensity 390,000 cps at 520 nm. However prodan bound to GroEL, GroEL-ATP, and GroEL-ATP-GroES shows emission peaks of intensities 500,000, 540,000, and 480,000 cps at 515, 512 and 515 nm, respectively, thus mimicing the way hydrophobic surfaces on GroEL become exposed during the folding cycle. Other hydrophobic probes like bis-ANS and dansyl lysine were unable to detect the minor changes in hydrophobic exposure of GroEL after it binds to ATP, although they were able to detect hydrophobic exposure in GroEL itself.

Active rhodanese lacking nonessential sulfhydryl groups has increased hydrophobic exposure not observed in wild-type enzyme.

Mutation of all nonessential cysteine residues to serines in rhodanese turns the enzyme into a form (C3S) that is fully active but less stable than wild type (WT). bis-ANS binding studies have shown that C3S has more hydrophobic exposure than WT, although both have similar secondary structures suggesting the flexibility of its structure. Activity of C3S falls once it binds bis-ANS, and covalent binding of bis-ANS to C3S is induced by light. bis-ANS binds to C3S in its C-terminal domain as is shown by gel electophoresis and proteolysis. bis-ANS binding makes the C-terminal domain more susceptible to trypsin cleavage.