Analysis on promotive effect of rocking culture on keratinocyte differentiation in 3-dimensional reconstitution human epidermis.

A 3-dimensional culture system of keratinocytes achieves cornification as a terminal differentiation that can mimic the formation of stratified epidermis. At the onset of keratinocyte differentiation, air-exposure treatment is essential for promotion. We have previously reported that the stimulation of differentiation is accompanied by downregulation of the transcriptional activity of the hypoxia-inducible factor (HIF) and also found that rocking treatment of cultured keratinocytes in the submerged condition restored their differentiation. A comparative study of cultured keratinocytes with and without rocking was then carried out to investigate the characteristics of the recovered differentiation by morphological and biochemical analyses. In addition, transcriptome analysis revealed the expected similar pattern between air-exposed and rocking cultures, including HIF-regulating transcripts. Furthermore, the promotive effect of rocking treatment was impaired under hypoxic culture conditions (1% O2). We showed that the restored promotion of differentiation by rocking culture is mainly due to the abrogation of transcriptional events by hypoxia.

Substrate profiling of human transglutaminase 1 using cDNA display and next-generation sequencing.

Human transglutaminase 1 (TG1) modulates skin development, while its involvement in diseases remains poorly understood, necessitating comprehensive exploration of its substrate interactions. To study the substrate profile of TG1, an in vitro selection system based on cDNA display technology was used to screen two peptide libraries with mutations at varying distance from the reactive glutamine. Next-generation sequencing and bioinformatics analysis of the selected DNA pools revealed a detailed TG1 substrate profile, indicating preferred and non-preferred amino acid sequences. The peptide sequence, AEQHKLPSKWPF, was identified showing high reactivity and specificity to TG1. The position weight matrix calculated from the per amino acid enrichment factors was employed to search human proteins using an in-house algorithm, revealing six known TG1 substrate proteins with high scores, alongside a list of candidate substrates currently under investigation. Our findings are expected to assist in future medical diagnoses and development of treatments for skin disorders.

Tofacitinib ameliorates skin inflammation in a patient with severe autosomal recessive congenital ichthyosis.

Autosomal recessive congenital ichthyosis (ARCI) is a genetically heterogeneous disorder with aberrant skin scaling and increased transepidermal water loss (TEWL). Current treatments for ARCI are limited and suboptimal. We present the case of a 27-year-old man with ARCI resulting from a homozygous missense variant in TGM1. RNA-sequencing of lesional skin revealed aberrant Janus kinase-signal transducer and activator of transcription signalling, providing a rationale for innovative treatment with a Janus kinase inhibitor. We prescribed oral tofacitinib (11 mg daily) for 26 weeks. Rapid improvements in erythema and fissuring occurred within the first month. Sustained reductions in 5-D itch scale and Dermatology Life Quality Index scores were also observed. TEWL decreased for the first 10 weeks but increased thereafter. Tofacitinib downregulated inflammatory genes and pathways, while enhancing skin barrier markers. Moreover, transglutaminase 1 distribution was normalized although enzymatic activity remained deficient. This study suggests that oral tofacitinib may be a useful therapy to consider for patients with ARCI.