SummaryIn amyotrophic lateral sclerosis (ALS) and animal models of ALS, including SOD1-G93A mice, disassembly of the neuromuscular synapse precedes motor neuron loss and is sufficient to cause a decline in motor function that culminates in lethal respiratory paralysis. We treated SOD1-G93A mice with an agonist antibody to MuSK, a receptor tyrosine kinase essential for maintaining neuromuscular synapses, to determine whether increasing muscle retrograde signaling would slow nerve terminal detachment from muscle. The agonist antibody, delivered after disease onset, slowed muscle denervation, promoting motor neuron survival, improving motor system output, and extending the lifespan of SOD1-G93A mice. These findings suggest a novel therapeutic strategy for ALS, using an antibody format with clinical precedence, which targets a pathway essential for maintaining attachment of nerve terminals to muscle.

IntroductionPsoriatic arthritis (PsA) is a heterogeneous chronic inflammatory musculoskeletal disorder that manifests as peripheral arthritis, dactylitis, enthesitis and spondylitis. PsA results in significant burden that impacts quality of life of patients. We examined the signs, symptoms and impacts reported by patients with PsA, to characterise the patient experience of PsA and develop a conceptual model representing this patient experience.MethodsSemi-structured interviews were conducted with patients with PsA recruited through the FORWARD databank. Spontaneous and probed signs, symptoms and impacts of PsA were assessed. Patients rated the disturbance of these concepts on their lives using a scale from 0 (‘does not disturb’) to 10 (‘greatly disturbs’). Signs, symptoms and impacts reported by >80% of patients with a disturbance rating of ≥5 were defined as salient concepts. Recruitment continued until concept saturation was achieved.Results19 patients with PsA were interviewed. The interviews elicited 42 symptoms of which 8 had not been identified in a previous literature review encompassing 15 relevant articles. The most salient signs and symptoms elicited in the interviews were joint pain, skin symptoms, stiffness, swollen/inflamed joints and fatigue all with moderate to high disturbance ratings (range: 5.5–7.8). The most salient impacts were sleep disturbance, physical disability, effects on daily activities and feelings of frustration with also moderate to high disturbance ratings (range: 6.1–7.4).ConclusionsThe interviews highlighted the adverse impact PsA has on the patient’s life and may inform on outcome variables or areas suitable to be assessed in PsA studies.

Spinal muscular atrophy (SMA) is a motor neuron disease caused by insufficient levels of the survival motor neuron (SMN) protein. One of the most prominent pathological characteristics of SMA involves defects of the neuromuscular junction (NMJ), such as denervation and reduced clustering of acetylcholine receptors (AChRs). Recent studies suggest that upregulation of agrin, a crucial NMJ organizer promoting AChR clustering, can improve NMJ innervation and reduce muscle atrophy in the delta7 mouse model of SMA. To test whether the muscle-specific kinase (MuSK), part of the agrin receptor complex, also plays a beneficial role in SMA, we treated the delta7 SMA mice with an agonist antibody to MuSK. MuSK agonist antibody #13, which binds to the NMJ, significantly improved innervation and synaptic efficacy in denervation-vulnerable muscles. MuSK agonist antibody #13 also significantly increased the muscle cross-sectional area and myofiber numbers in these denervation-vulnerable muscles but not in denervation-resistant muscles. Although MuSK agonist antibody #13 did not affect the body weight, our study suggests that preservation of NMJ innervation by the activation of MuSK may serve as a complementary therapy to SMN-enhancing drugs to maximize the therapeutic effectiveness for all types of SMA patients.

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Background and Aims Patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD) experience various symptoms due to increasing kidney volume and its associated complications. To understand symptom burden, qualitative interviews were conducted to characterize the ADPKD patient experience pertaining to the most common and disturbing symptoms. Method Combined concept elicitation and cognitive debriefing interviews were performed by trained interviewers following a preliminary conceptual model based on a targeted literature review. We currently report on the concept elicitation component, which explored relevant and bothersome symptoms in ADPKD patients, due to either the disease or associated treatments. Nineteen telephone interviews were conducted in four waves of 5, 4, 6, and 4 patients, respectively. Results The mean age of patients was 47 years (SD: 9 years); 68% (n=13) were female, and the mean estimated glomerular filtration rate (eGFR) was 41 ml/min/1.73m2 (SD: 25 ml/min/1.73m2), with the majority 47% (n=9) in stage 3 chronic kidney disease (CKD). The classes of treatments included antihypertensives (74%, n=14), vasopressin receptor antagonists (21%, n=4); diuretics (16%, n=3), analgesics (16%, n=3) and erythropoietin (5%, n=1). The most frequently mentioned symptoms were fatigue (89%, n=17), pain (84%, n=16), and nocturia (74%, n=14); all were considered at least moderately disturbing to patients’ lives. Most patients experienced constant fatigue (74%, n=14) that worsened over time. Patients’ descriptions of pain were variable, including back and side pain, severe cystic pain, and muscle pain; a few patients also mentioned shoulder pain, or pain due to kidney stones. Among patients reporting nocturia (n=14), about half (57%, n=8) rated nocturia on the upper end of the disturbance scale, regardless of number of voids per night, often accompanied by sleep disruption. While less frequently occurring, itchy skin, muscle cramping, abdominal swelling, and inability to eat were spontaneously mentioned among the most disturbing symptoms. Conclusion The novel component of this study is the significant disruption of nocturia in patients with ADPKD even in the absence of vasopressin receptor antagonist administration. In addition, it confirms the findings of the literature review and highlights the patient experience in ADPKD, most notably fatigue, nocturia, and pain as the most frequent and bothersome symptoms experienced by patients. Subjective evaluation of the ADPKD patient experience is critical to understand symptom severity and the burden of disease, to potentially quantify disease progression, and to assess the impact of emerging therapies.