Helios is a key transcriptional regulator of outer hair cell maturation

The sensory cells that are responsible for hearing include the cochlear inner hair cells (IHCs) and outer hair cells (OHCs), with the OHCs being necessary for sound sensitivity and tuning1. Both cell types are thought to arise from common progenitors; however, our understanding of the factors that control the fate of IHCs and OHCs remains limited. Here we identify Ikzf2 (which encodes Helios) as an essential transcription factor in mice that is required for OHC functional maturation and hearing. Helios is expressed in postnatal mouse OHCs, and in the cello mouse model a point mutation in Ikzf2 causes early-onset sensorineural hearing loss. Ikzf2cello/cello OHCs have greatly reduced prestin-dependent electromotile activity, a hallmark of OHC functional maturation, and show reduced levels of crucial OHC-expressed genes such as Slc26a5 (which encodes prestin) and Ocm. Moreover, we show that ectopic expression of Ikzf2 in IHCs: induces the expression of OHC-specific genes; reduces the expression of canonical IHC genes; and confers electromotility to IHCs, demonstrating that Ikzf2 can partially shift the IHC transcriptome towards an OHC-like identity

The rise of cochlear gene therapy

Recent evidence provides strong support for the safe and effective use of gene therapy in humans with hearing loss. By means of a single local injection of a set of adeno-associated virus (AAV) vectors, hearing was partially restored in several children with neurosensory nonsyndromic autosomal recessive deafness 9 (DFNB9), harboring variants in the OTOF gene. Current research focuses on refining endoscopic and transmastoid injection procedures to reduce risks of side effects, as emerging evidence suggests bidirectional fluid exchanges between the ear and the brain. Moreover, gene editing approaches and novel AAV capsids are successfully tested in animal models and will likely lead to enhanced targeting of the cochlea. Here, we cover the recent advances in cochlear gene therapy, provide an overview of the translational potential of these new approaches for existing and future clinical trials, and highlight the translational implications that remain to be determined for their application in humans

Modulation of HLA-DR in dry eye patients following 30 days of treatment with a lubricant eyedrop solution

Karen B Fernandez, Seth P Epstein, Geoffrey S Raynor, Alan T Sheyman, Morgan L Massingale, Peter G Dentone, Lukas D Landegger, Penny A Asbell Department of Ophthalmology, Mount Sinai School of Medicine, New York, NY, USA Purpose: To determine the changes in dry eye disease (DED) severity and the percentage of cells expressing HLA-DR on the ocular surface following treatment with lubricant eyedrops containing polyethylene glycol and propylene glycol (PEG/PG) and the gelling agent hydroxypropyl guar (HP-Guar).Patients and methods: Nineteen patients with DED used PEG/PG + HP-Guar eyedrops four times per day for 30 days. Assessments included DED severity (Ocular Surface Disease Index [OSDI], corneal staining, conjunctival staining, tear film break-up time [TFBUT], and Schirmer testing) and impression cytology of the conjunctiva with masked flow cytometry at baseline and at 30 days.Results: There was a significant decrease in corneal staining (P<0.01), OSDI (P=0.02), and TFBUT (P<0.01) following treatment with PEG/PG + HP-Guar. Results from flow cytometry revealed a significant decrease in cells expressing HLA-DR (P=0.02).Conclusion: Treatment with PEG/PG + HP-Guar eyedrops showed improvement in dry eye severity and reduction in surface inflammation as indicated by a reduction in HLA-DR expression. Keywords: artificial tears, dry eye disease, hydroxypropyl guar, inflammation, lubricating eyedrops, polyethylene glycol, propylene glyco