Clinical Approach to a Suspected Case of First Branchial Arch Syndrome

First branchial arch syndrome is a congenital disorder characterized by a wide spectrum of anomalies in the first branchial arch, mainly affecting the lower jaw, ear, or mouth, during early embryonic development. We sought to confirm a suspected case of this syndrome by making differential diagnosis and taking an intensive clinical approach. A 12-year-6-month-old girl with a horizontally impacted left canine in the maxilla had the history of digital fusion in her hands and feet and has been suffering from hearing impairment of her left ear. To diagnose this case and make her careful treatment plan, we further carried out cephalometric analysis and mutation analysis. Her face looks like asymmetry and is not apparently symmetric by cephalometric analysis. Mutation analysis of the patient was conducted by direct DNA sequencing of the goosecoid gene, which is an excellent candidate for determination of hemifacial microsomia, but no changes in this gene were identified. We could not precisely diagnose this case as first branchial arch syndrome. However, certain observations in this case, including hearing impairment of the left ear, allow us to suspect this syndrome

Dysfunction of fibroblasts of extrarenal origin underlies renal fibrosis and renal anemia in mice

In chronic kidney disease, fibroblast dysfunction causes renal fibrosis and renal anemia. Renal fibrosis is mediated by the accumulation of myofibroblasts, whereas renal anemia is mediated by the reduced production of fibroblast-derived erythropoietin, a hormone that stimulates erythropoiesis. Despite their importance in chronic kidney disease, the origin and regulatory mechanism of fibroblasts remain unclear. Here, we have demonstrated that the majority of erythropoietin-producing fibroblasts in the healthy kidney originate from myelin protein zero–Cre (P0-Cre) lineage-labeled extrarenal cells, which enter the embryonic kidney at E13.5. In the diseased kidney, P0-Cre lineage-labeled fibroblasts, but not fibroblasts derived from injured tubular epithelial cells through epithelial-mesenchymal transition, transdifferentiated into myofibroblasts and predominantly contributed to fibrosis, with concomitant loss of erythropoietin production. We further demonstrated that attenuated erythropoietin production in transdifferentiated myofibroblasts was restored by the administration of neuroprotective agents, such as dexamethasone and neurotrophins. Moreover, the in vivo administration of tamoxifen, a selective estrogen receptor modulator, restored attenuated erythropoietin production as well as fibrosis in a mouse model of kidney fibrosis. These findings reveal the pathophysiological roles of P0-Cre lineage-labeled fibroblasts in the kidney and clarify the link between renal fibrosis and renal anemia