French cohort of children and adolescents with neurofibromatosis type 1 and symptomatic inoperable plexiform neurofibromas: CASSIOPEA study.

Surgery is a treatment option for neurofibromatosis type 1 (NF1)-related plexiform neurofibromas (PN), but complete resection is often not feasible. Real-world studies are warranted to understand disease burden, progression, and need for medical treatment in patients with inoperable PN. CASSIOPEA was a retrospective study of French pediatric patients (aged ≥3 to <18 years) presenting at a national multidisciplinary team (MDT) review with NF1 and ≥1 symptomatic, inoperable PN. Medical records were reviewed from the time of MDT review and over a follow-up period of up to 2 years. Primary objectives were to describe patient characteristics and target PN-associated therapy patterns. A secondary objective was evolution of target PN-related morbidities. Patients with prior, ongoing, or MDT recommendation of mitogen-activated protein kinase kinase (MEK) inhibitor treatment were excluded. Overall, 78 target PN were identified in 76 patients. At MDT review, median age was 8.4 years, with approximately 30% of patients aged 3-6 years. Target PN were primarily internal (77.3%), and 43.2% were progressive. Target PN location was evenly distributed. 34 target PN had documented MDT recommendations; of these, a majority (76.5%) were for non-medication management, including surveillance. At least one follow-up visit was recorded for 74 target PN. Despite initially being considered inoperable, 12.3% of patients underwent surgery for target PN. At MDT review, most (98.7%) target PN were associated with ≥1 morbidity, primarily pain (61.5%) and deformity (24.4%); severe morbidities were identified in 10.3%. Of 74 target PN with follow-up data, 89.2% were associated with ≥1 morbidity, primarily pain (60.8%) and deformity (25.7%). Of 45 target PN associated with pain, pain improved in 26.7%, was stable in 44.4%, and deteriorated in 28.9%. Deformity improved in 15.8% and remained stable in 84.2% of 19 target PN associated with deformity. None deteriorated. In this real-world study in France, NF1-PN disease burden was considerable, and a considerable proportion of patients were very young. Most patients received only supportive care without medication for target PN management. Target PN-related morbidities were frequent, heterogeneous, and generally did not improve during follow-up. These data highlight the importance of effective treatments that target PN progression and improve disease burden.

Lipin1 deficiency causes sarcoplasmic reticulum stress and chaperone-responsive myopathy.

As a consequence of impaired glucose or fatty acid metabolism, bioenergetic stress in skeletal muscles may trigger myopathy and rhabdomyolysis. Genetic mutations causing loss of function of the LPIN1 gene frequently lead to severe rhabdomyolysis bouts in children, though the metabolic alterations and possible therapeutic interventions remain elusive. Here, we show that lipin1 deficiency in mouse skeletal muscles is sufficient to trigger myopathy. Strikingly, muscle fibers display strong accumulation of both neutral and phospholipids. The metabolic lipid imbalance can be traced to an altered fatty acid synthesis and fatty acid oxidation, accompanied by a defect in acyl chain elongation and desaturation. As an underlying cause, we reveal a severe sarcoplasmic reticulum (SR) stress, leading to the activation of the lipogenic SREBP1c/SREBP2 factors, the accumulation of the Fgf21 cytokine, and alterations of SR-mitochondria morphology. Importantly, pharmacological treatments with the chaperone TUDCA and the fatty acid oxidation activator bezafibrate improve muscle histology and strength of lipin1 mutants. Our data reveal that SR stress and alterations in SR-mitochondria contacts are contributing factors and potential intervention targets of the myopathy associated with lipin1 deficiency.

Effective arteriovenous fistula alternative for hemodialysis access.

BACKGROUND: The use of autologous arteriovenous fistulae (AVF) for hemodialysis (HD) is the gold standard; however, for many patients at tertiary referral centers, this is not an option. METHODS: We conducted a four year retrospective cohort study to evaluate HD access outcomes with AVF, bovine carotid artery (BCA), and polytetrafluoroethylene arteriovenous graft (PTFE). RESULTS: The study contained 416 AVF, 175 BCA, and 58 PTFE, N = 649. There was statistical difference between rates of infection (AVF 3.4%, BCA 2.9%, PTFE 11.9%), P = 0.02. Maturation failed in 7.5% of AVF but in none of the BCA or PTFE (P = 0.001). Accesses were abandoned with AVF (1.9%), BCA (1.5%), and PTFE (9.5%), P = 0.01. CONCLUSION: Bovine carotid artery can be an effective alternative form of HD access with lower infection, abandonment, and failure to maturation rates when autologous arteriovenous fistula is not an option.

KAT2B Is Required for Pancreatic Beta Cell Adaptation to Metabolic Stress by Controlling the Unfolded Protein Response.

The endoplasmic reticulum (ER) unfolded protein response (UPR(er)) pathway plays an important role in helping pancreatic ß cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPR(er) gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germline and ß cell-specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome-wide analysis of Kat2b-regulated genes and functional assays reveal a critical role for Kat2b in maintaining UPR(er) gene expression and subsequent ß cell function. Importantly, Kat2b expression is decreased in mouse and human diabetic ß cells and correlates with UPR(er) gene expression in normal human islets. In conclusion, Kat2b is a crucial transcriptional regulator for adaptive ß cell function during metabolic stress by controlling UPR(er) and represents a promising target for T2D prevention and treatment.