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Abstract Background COVID-19 is a pandemic respiratory and vascular disease caused by SARS-CoV-2 virus. There is a growing number of sensory deficits associated with COVID-19 and molecular mechanisms underlying these deficits are incompletely understood. Methods We report a series of ten COVID-19 patients with audiovestibular symptoms such as hearing loss, vestibular dysfunction and tinnitus. To investigate the causal relationship between SARS-CoV-2 and audiovestibular dysfunction, we examine human inner ear tissue, human inner ear in vitro cellular models, and mouse inner ear tissue. Results We demonstrate that adult human inner ear tissue co-expresses the angiotensin-converting enzyme 2 (ACE2) receptor for SARS-CoV-2 virus, and the transmembrane protease serine 2 (TMPRSS2) and FURIN cofactors required for virus entry. Furthermore, hair cells and Schwann cells in explanted human vestibular tissue can be infected by SARS-CoV-2, as demonstrated by confocal microscopy. We establish three human induced pluripotent stem cell (hiPSC)-derived in vitro models of the inner ear for infection: two-dimensional otic prosensory cells (OPCs) and Schwann cell precursors (SCPs), and three-dimensional inner ear organoids. Both OPCs and SCPs express ACE2, TMPRSS2, and FURIN, with lower ACE2 and FURIN expression in SCPs. OPCs are permissive to SARS-CoV-2 infection; lower infection rates exist in isogenic SCPs. The inner ear organoids show that hair cells express ACE2 and are targets for SARS-CoV-2. Conclusions Our results provide mechanistic explanations of audiovestibular dysfunction in COVID-19 patients and introduce hiPSC-derived systems for studying infectious human otologic disease.

Plastic pollution is increasing at an alarming rate yet the impact of this pollution on human health is poorly understood. Because human induced pluripotent stem cells (hiPSC) are frequently derived from dermal fibroblasts, these cells offer a powerful platform for the identification of molecular biomarkers of environmental pollution in human cells. Here, we describe a novel proof-of-concept for deriving hiPSC from human dermal fibroblasts deliberately exposed to polystyrene (PS) nanoplastic particles; unexposed hiPSC served as controls. In parallel, unexposed hiPSC were exposed to low and high concentrations of PS nanoparticles. Transcriptomic and epigenomic signatures of all fibroblasts and hiPSCs were defined using RNA-seq and whole genome methyl-seq, respectively. Both PS-treated fibroblasts and derived hiPSC showed alterations in expression of ESRRB and HNF1A genes and circuits involved in the pluripotency of stem cells, as well as in pathways involved in cancer, inflammatory disorders, gluconeogenesis, carbohydrate metabolism, innate immunity, and dopaminergic synapse. Similarly, the expression levels of identified key transcriptional and DNA methylation changes (DNMT3A, ESSRB, FAM133CP, HNF1A, SEPTIN7P8, and TTC34) were significantly affected in both PS-exposed fibroblasts and hiPSC. This study illustrates the power of human cellular models of environmental pollution to narrow down and prioritize the list of candidate molecular biomarkers of environmental pollution. This knowledge will facilitate the deciphering of the origins of environmental diseases.

Primitive extraembryonale Endoderm (pXEN) Stam-Zelllinien der Ratte repraesentieren wahrscheinlich die festgelegten Vorläufer des extraembryonalen. Die im mesenchymalen Zustand gehaltenen pXEN-Zellen können in vitro weiter zu parietalen und viszeralen Endoderm-ähnlichen Zellen differenzieren. pXEN-Zellen zusätzlich halten moderate Konzentrationen des ICM-Markers Oct4 aufrecht. Die Bedeutung von Oct4 in pXEN-Zellen ist jedoch unbekannt. Bei höheren Zelldichten, beobachteten wir eine erhöhte Oct4-Expression und gleichzeitig eine Tendenz zu Epithelialisierung (MET) und viszeral endodermaler (VE) Differenzierung. Um zu klären, ob die Oct4-Expression kausal beteiligt ist, modulierten wir die Oct4-Konzentration. Transienter Knockdown von Oct4 reduzierte tendenziell die Expression von MET / VE-assoziierten Genen; umgekehrt förderte die Doxycycline-induzierte Expression eines menschlichen Oct4-Transgens die MET / VE-Differenzierung und verhinderte die Bildung charakteristischer Gang-Strukturen. Im letzteren Fall ging dem MET eine anfängliche Zell-Verlängerung und eine erhöhte Zellmotilität voraus. Da ein GSK3-Inhibitor und Activin A auch den MET / VE-Phänotyp stimulierten, fragten wir uns, ob Oct4 über die Wnt/β-Catenin oder TGFβ Signalwege wirkt. Die verschiedene Schritte der Wnt/β-Catenin Signalgebung hemmen, blockierten die hOct4-induzierte MET- und VE-Expression nicht. Im Gegensatz dazu verhinderte Repsox, ein Inhibitor von Alk5 (TGFBR1), das hOct4-induzierte MET und die Expression von MET- und VE-Genen und stimulierte eher die Expression von parietalen Endoderm (PE) Genen. Zusammengefasst zeigen diese Daten eine Rolle für Oct4 bei der MET / VE-Differenzierung auf, wahrscheinlich durch Stimulation eines TGFβ Signalweges. Weiterführende Experimente sind erforderlich um zu bestimmen, wie die zwei Prozesse der MET- und VE-Differenzierung innerhalb der extraembryonalen Endoderm-Linie unterschieden und in Beziehung gesetzt werden., Rat primitive extraembryonic endoderm (pXEN) cell lines appear to represent the committed precursors of the extraembryonic endoderm. The pXEN cells maintained in the mesenchymal state can further differentiate to the parietal endoderm and visceral endoderm like-cells in vitro. In addition, pXEN cells maintain moderate levels of the ICM marker Oct4, a transcription factor that plays important roles in pluripotency, plasticity, and differentiation. However, the significance of Oct4 in pXEN cell lineage specification is unknown. We observed that rat pXEN cells show increased Oct4 expression at higher densities, a condition that also promotes their epithelialization (MET) and visceral endodermal (VE) differentiation. In order to elucidate whether the Oct4 expression is causally involved, we modulated the Oct4 levels. Transient knockdown of Oct4 tended to reduce the expression of MET/VE-associated genes; conversely, the doxycycline-induced expression of a human Oct4 transgene promoted MET/VE differentiation and prevented the formation of characteristic duct structures. In the latter case, the MET was preceded by an initial elongation and increased cell motility. Since GSK3 inhibitor and Activin A also stimulated the MET/VE phenotype, we then asked whether Oct4 acts through the Wnt/β-catenin or TGFβ pathways. Wnt inhibitors did not block the hOct4-induced MET and VE expression. By contrast, Repsox, an inhibitor of Alk5 (TGFBR1), prevented the hOct4-induced MET and the expression of MET and VE genes and rather stimulated the expression of parietal endoderm (PE) genes. Taken together, these data indicate a role for Oct4 in MET/VE differentiation via stimulation of TGFβ signaling. Further work is needed to determine how the two MET and VE differentiation processes are distinguished and related within the extraembryonic endoderm lineage.