CFTR interactome mapping using the mammalian membrane two-hybrid high-throughput screening system.

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a chloride and bicarbonate channel in secretory epithelia with a critical role in maintaining fluid homeostasis. Mutations in CFTR are associated with Cystic Fibrosis (CF), the most common lethal autosomal recessive disorder in Caucasians. While remarkable treatment advances have been made recently in the form of modulator drugs directly rescuing CFTR dysfunction, there is still considerable scope for improvement of therapeutic effectiveness. Here, we report the application of a high-throughput screening variant of the Mammalian Membrane Two-Hybrid (MaMTH-HTS) to map the protein-protein interactions of wild-type (wt) and mutant CFTR (F508del), in an effort to better understand CF cellular effects and identify new drug targets for patient-specific treatments. Combined with functional validation in multiple disease models, we have uncovered candidate proteins with potential roles in CFTR function/CF pathophysiology, including Fibrinogen Like 2 (FGL2), which we demonstrate in patient-derived intestinal organoids has a significant effect on CFTR functional expression.

Performance of different criteria for refractory myasthenia gravis.

BACKGROUND AND PURPOSE: Defining refractory myasthenia gravis is important, as this can drive clinical decision making, for example, by escalating treatments in refractory individuals. There are several definitions of refractory myasthenia, and their performances have not been compared. Having valid and reliable criteria can help select patients in whom more aggressive treatments may be needed. METHODS: We applied five different refractory myasthenia criteria (Drachman, Mantegazza, Suh, the International Consensus Guideline (ICG), and the randomised controlled trial of eculizumab in refractory, anti-acetylcholine receptor positive, generalised myasthenia gravis (REGAIN), to a cohort of 237 patients. We compared the proportion of refractory patients among different criteria and their scores on disease severity, fatigue, and quality-of-life (QoL) scales. We also assessed the agreement for each criterion between two trained assessors. RESULTS: The Drachman, Mantegazza, and Suh criteria resulted in high proportions of refractory individuals (40.1%, 39.2%, and 38.8%, respectively), compared with the ICG and REGAIN criteria (9.7% and 3.0%, respectively). Refractory patients by the ICG and REGAIN criteria had worse disease severity, QoL, and fatigue scores, compared with patients classified as refractory by other criteria. All criteria had high agreement between raters (between 70% and 100%). CONCLUSIONS: There is high variability in the proportion of refractory myasthenia gravis patients depending on the criteria used, with ICG and REGAIN criteria capturing patients with worse disease severity. This reflects conceptual differences as to what refractory means. Further multicenter studies are needed to determine appropriate criteria for refractory myasthenia gravis.

Efficacy and safety of high infusion rate IVIG in CIDP.

BACKGROUND: We aimed to determine the safety and tolerance of higher rates of infusion of intravenous immunoglobulin (IVIG) in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: Patients began infusions with 10% IVIG at the standard rate of 0.08 mL/kg/min. If tolerated, infusion rates were incrementally increased to 0.14 mL/kg/min. We considered the frequency of infusions with adverse events (AEs) as the primary outcome. RESULTS: Nineteen of 25 patients safely tolerated the maximum rate of 0.14 mL/kg/min. We observed 25 treatment-related AEs (TAEs) over 13 infusions at standard or transitional rates, across seven patients. We observed no TAEs associated with the maximum infusion rate. CONCLUSIONS: We found that 10% IVIG can be safely administered at a high infusion rate (0.14 ml/kg/min) in most CIDP patients, reducing the treatment time and burden on healthcare resources.

Symptom and Treatment Satisfaction in Members of the US and Canadian GBS/CIDP Foundations with a Diagnosis of Chronic Inflammatory Demyelinating Polyneuropathy.

INTRODUCTION: Current guidelines for defining good outcomes in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) are predominately defined by experts. At present, we do not have a patient-anchored definition of what constitutes a "good" outcome. Our study aimed to assess the symptom burden of people living with CIDP, as well as satisfaction with treatments and clinical outcomes. METHODS: We conducted an online-survey in CIDP patients registered with the US and Canadian GBS/CIDP foundations. Respondents answered general demographic and clinical questions, as well as satisfaction with current symptom burden and treatments, plus validated outcome measures. RESULTS: A total of 318 individuals with self-reported CIDP completed the online survey, of whom 128 (40%) considered their current disease burden as satisfactory while 190 (60%) did not. Of 305 patients who answered the treatment satisfaction question, 222(74%) were satisfied with their treatments. Patients who were satisfied with their current symptoms had, on average, better scores in quality of life and disease severity scales, although regression modeling showed that only ability to walk, stable symptoms, and health utility scores were associated with symptom satisfaction. Treatment satisfaction was associated with stable symptoms, use of IVIG, and use of one versus no medication. CONCLUSIONS: A high proportion of members of the US and Canadian GBS/CIDP Foundations reporting a diagnosis of CIDP were unsatisfied with current symptoms, despite a high level of overall satisfaction with treatments. There is an unmet need for improving long-term outcomes in people with a diagnosis of CIDP, and for studying patient-centered long-term treatment goals.

Patient-acceptable symptom states in myasthenia gravis.

OBJECTIVES: To estimate patient-acceptable symptom state (PASS) cut points for myasthenia gravis (MG) health scales. METHODS: We conducted an electronic survey that included the Myasthenia Gravis Impairment Index (MGII), EuroQol 5-Dimension (EQ5D), and a simple PASS question. PASS-anchored thresholds were estimated for the MGII questionnaire through receiver operating characteristic curves. We used the MGII PASS cut point in a validation cohort of 257 patients to estimate PASS thresholds for other clinically relevant health scales such as the Quantitative Myasthenia Gravis Scale (QMGS), Myasthenia Gravis Activities of Daily Living (MG-ADL), Myasthenia Gravis Composite (MGC), and Myasthenia Quality of Life (MG-QoL15). RESULTS: One hundred twenty-four of ≈250 invited patients answered the electronic survey (49% response rate), and 80 considered their current symptom state acceptable (PASS-positive). They had lower MGII scores than PASS-negative patients (7.76 ± 9.37 vs 25.0 ± 13.7, p < 0.0001) and better EQ5D scores (0.86 ± 0.17 vs 0.69 ± 0.18, p < 0.0001). The MGII questionnaire threshold for PASS was ≤10 points. With the use of this threshold in an independent dataset of 257 patients, all patients in remission or minimal manifestation status were PASS-positive. In addition, some patients in Classes I, II, and IIIA also achieved PASS status. PASS thresholds for the QMGS, MG-ADL, MGC, and MG-QoL15 were ≤7, 2, 3, and 8 points, respectively. CONCLUSIONS: We have estimated thresholds for commonly used myasthenia health scales reflecting patient-acceptable states in patients with MG. These thresholds indicate a global state of well being, rather than a change in scores, or being better. Therefore, PASS thresholds can be used as secondary endpoints for myasthenia research.

Components of yeast (Sacchromyces cervisiae) extract as defined media additives that support the growth and productivity of CHO cells.

Yeast and plant hydrolysates are used as media supplements to support the growth and productivity of CHO cultures for biopharmaceutical production. Through fractionation of a yeast lysate and metabolic analysis of a fraction that had bioactivity equivalent to commercial yeast extract (YE), bioactive components were identified that promoted growth and productivity of two recombinant CHO cell lines (CHO-Luc and CHO-hFcEG2) equivalent to or greater than YE-supplemented media. Autolysis of the yeast lysate was not necessary for full activity, suggesting that the active components are present in untreated yeast cells. A bioactive fraction (3KF) of the yeast lysate was isolated from the permeate using a 3kDa molecular weight cut-off (MWCO) filter. Supplementation of this 3KF fraction into the base media supported growth of CHO-Luc cells over eight passages equivalent to YE-supplemented media. The 3KF fraction was fractionated further by a cation exchange spin column using a stepwise pH elution. Metabolomic analysis of a bioactive fraction isolated at high pH identified several arginine and lysine-containing peptides as well as two polyamines, spermine and spermidine, with 3.5× and 4.5× higher levels compared to a fraction showing no bioactivity. The addition of a mixture of polyamines and their precursors (putrescine, spermine, spermidine, ornithine and citrulline) as well as increasing the concentration of some of the components of the original base medium resulted in a chemically-defined (CD) formulation that produced an equivalent viable cell density (VCD) and productivity of the CHO-Luc cells as the YE-supplemented medium. The VCD of the CHO-hFcEG2 culture in the CD medium was 1.9× greater and with equivalent productivity to the YE-supplemented media.

The clathrin adaptor AP-1 complex and Arf1 regulate planar cell polarity in vivo.

A key step in generating planar cell polarity (PCP) is the formation of restricted junctional domains containing Frizzled/Dishevelled/Diego (Fz/Dsh/Dgo) or Van Gogh/Prickle (Vang/Pk) complexes within the same cell, stabilized via Flamingo (Fmi) across cell membranes. Although models have been proposed for how these complexes acquire and maintain their polarized localization, the machinery involved in moving core PCP proteins around cells remains unknown. We describe the AP-1 adaptor complex and Arf1 as major regulators of PCP protein trafficking in vivo. AP-1 and Arf1 disruption affects the accumulation of Fz/Fmi and Vang/Fmi complexes in the proximo-distal axis, producing severe PCP phenotypes. Using novel tools, we demonstrate a direct and specific Arf1 involvement in Fz trafficking in vivo. Moreover, we uncover a conserved Arf1 PCP function in vertebrates. Our data support a model whereby the trafficking machinery plays an important part during PCP establishment, promoting formation of polarized PCP-core complexes in vivo.