No abstract

Onasemnogene abeparvovec is an adeno-associated virus vector-based gene therapy for spinal muscular atrophy (SMA). Although several cases of drug-induced thrombotic microangiopathy due to onasemnogene abeparvovec have been reported, none has been confirmed pathologically. Here, we present renal histopathologic findings of TMA due to onasemnogene abeparvovec. On day 5 after receiving onasemnogene abeparvovec, a 23-month-old girl with SMA type 1 developed thrombocytopenia, microangiopathic hemolytic anemia, liver dysfunction, acute kidney injury, and hypertension. She was diagnosed with TMA and received an increased dose of prednisolone, antihypertensives, diuretics, packed red blood cell and platelet transfusion, a single dose of eculizumab, four cycles of plasmapheresis, and intermittent and continuous hemodialysis. Her TMA resolved by day 30. On day 49, renal biopsy was performed. Light microscopy revealed proliferation of glomerular mesangial cells and matrix, with mesangiolysis, endothelial cell swelling, and partial double contours of the glomerular basement membrane. Electron microscopy showed endothelial injury, with edematous changes of the subendothelial spaces and neoformation of the basement membrane, without electron-dense depositions. These findings are compatible with the recovery phase of TMA. One year after drug administration, her motor function is improved. She can hold her posture against gravity and has neither dysphagia nor respiratory disturbance, but mild hypertension persists. Physicians should be vigilant regarding TMA as a severe side effect of onasemnogene abeparvovec treatment, especially when thrombocytopenia, hemolytic anemia, increased lactate dehydrogenase, or acute kidney injury is present.

Figure 1 (a-d) Immunofluorescence staining using anti-human catalase antibody revealed the presence of larger and fewer peroxisomes in cultured skin fibroblasts from (a) the patient than in those from (b) the control. Analysis using anti-d-bifunctional protein (DBP) revealed the absence of punctate fluorescence in the fibroblasts from (c) the patient, although the punctate pattern was normal in (d) the control sample. Bar = 10 mm. (e) Real-time quantitative polymerase chain reaction of DBP in a healthy control subject, in the patient, and in two other Japanese patients with DBP-deficiency.

Neonates and infants are particularly susceptible to infections, for which outcomes tend to be severe. Vaccination is a key strategy for preventing infectious diseases, but the protective immunity achieved through vaccination typically is weaker in infants than in healthy adults. One possible explanation for the poor acquisition of vaccine-induced immunity in infants is that their innate immune response, represented by toll-like receptors, is immature. The current system for developing pediatric vaccines relies on the confirmation of their safety and effectiveness in studies involving the use of mature animals or adult humans. However, creating vaccines for neonates and infants requires an understanding of their uniquely immature innate immunity. Here we review current knowledge regarding the innate immune system of neonates and infants and challenges in developing vaccine adjuvants for those children through analyses of cord blood.

Highlights •Neonates have limited innate immune responses to infection. •We compared cord blood (CD14 + CD16 high) and adult (CD14 + CD16 intermediate) monocytes. •Cord blood monocytes had low basal expression of MHC class II, CD80, and CD11b. •TLR4 or TLR2/6 stimulation increased the antigens more in cord than adult monocytes.