Unraveling Transcriptome Profile, Epigenetic Dynamics, and Morphological Changes in Psoriasis-like Keratinocytes: "Insights into Similarity with Psoriatic Lesional Epidermis".

Keratinocytes are one of the primary cells affected by psoriasis inflammation. Our study aimed to delve deeper into their morphology, transcriptome, and epigenome changes in response to psoriasis-like inflammation. We created a novel cytokine mixture to mimic mild and severe psoriasis-like inflammatory conditions in cultured keratinocytes. Upon induction of inflammation, we observed that the keratinocytes exhibited a mesenchymal-like phenotype, further confirmed by increased VIM mRNA expression and results obtained from confocal microscopy. We performed RNA sequencing to achieve a more global view, revealing 858 and 6987 DEGs in mildly and severely inflamed keratinocytes, respectively. Surprisingly, we found that the transcriptome of mildly inflamed keratinocytes more closely mimicked that of the psoriatic epidermis transcriptome than the severely inflamed keratinocytes. Genes involved in the IL-17 pathway were a major contributor to the similarities of the transcriptomes between mildly inflamed KCs and psoriatic epidermis. Mild and severe inflammation led to the gene regulation of epigenetic modifiers such as HATs, HDACs, DNMTs, and TETs. Immunofluorescence staining revealed distinct 5-hmC patterns in inflamed versus control keratinocytes, and consistently low 5-mC intensity in both groups. However, the global DNA methylation assay detected a tendency of decreased 5-mC levels in inflamed keratinocytes versus controls. This study emphasizes how inflammation severity affects the transcriptomic similarity of keratinocytes to psoriatic epidermis and proves dynamic epigenetic regulation and adaptive morphological changes in inflamed keratinocytes.

Are the Cutaneous Microbiota a Guardian of the Skin's Physical Barrier? The Intricate Relationship between Skin Microbes and Barrier Integrity.

The skin is a tightly regulated, balanced interface that maintains our integrity through a complex barrier comprising physical or mechanical, chemical, microbiological, and immunological components. The skin's microbiota affect various properties, one of which is the establishment and maintenance of the physical barrier. This is achieved by influencing multiple processes, including keratinocyte differentiation, stratum corneum formation, and regulation of intercellular contacts. In this review, we summarize the potential contribution of Cutibacterium acnes to these events and outline the contribution of bacterially induced barrier defects to the pathogenesis of acne vulgaris. With the combined effects of a Westernized lifestyle, microbial dysbiosis, epithelial barrier defects, and inflammation, the development of acne is very similar to that of several other multifactorial diseases of barrier organs (e.g., inflammatory bowel disease, celiac disease, asthma, atopic dermatitis, and chronic rhinosinusitis). Therefore, the management of acne requires a complex approach, which should be taken into account when designing novel treatments that address not only the inflammatory and microbial components but also the maintenance and strengthening of the cutaneous physical barrier.

Psoriatic Resolved Skin Epidermal Keratinocytes Retain Disease-Residual Transcriptomic and Epigenomic Profiles.

The disease-residual transcriptomic profile (DRTP) within psoriatic healed/resolved skin and epidermal tissue-resident memory T (TRM) cells have been proposed to be crucial for the recurrence of old lesions. However, it is unclear whether epidermal keratinocytes are involved in disease recurrence. There is increasing evidence regarding the importance of epigenetic mechanisms in the pathogenesis of psoriasis. Nonetheless, the epigenetic changes that contribute to the recurrence of psoriasis remain unknown. The aim of this study was to elucidate the role of keratinocytes in psoriasis relapse. The epigenetic marks 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) were visualized using immunofluorescence staining, and RNA sequencing was performed on paired never-lesional and resolved epidermal and dermal compartments of skin from psoriasis patients. We observed diminished 5-mC and 5-hmC amounts and decreased mRNA expression of the ten-eleven translocation (TET) 3 enzyme in the resolved epidermis. SAMHD1, C10orf99, and AKR1B10: the highly dysregulated genes in resolved epidermis are known to be associated with pathogenesis of psoriasis, and the DRTP was enriched in WNT, TNF, and mTOR signaling pathways. Our results suggest that epigenetic changes detected in epidermal keratinocytes of resolved skin may be responsible for the DRTP in the same regions. Thus, the DRTP of keratinocytes may contribute to site-specific local relapse.

Quinone binding site in a type VI sulfide:quinone oxidoreductase.

Monotopic membrane-bound flavoproteins, sulfide:quinone oxidoreductases (SQRs), have a variety of physiological functions, including sulfide detoxification. SQR enzymes are classified into six groups. SQRs use the flavin adenine dinucleotide (FAD) cofactor to transfer electrons from sulfide to quinone. A type VI SQR of the photosynthetic purple sulfur bacterium, Thiocapsa roseopersicina (TrSqrF), has been previously characterized, and the mechanism of sulfide oxidation has been proposed. This paper reports the characterization of quinone binding site (QBS) of TrSqrF composed of conserved aromatic and apolar amino acids. Val331, Ile333, and Phe366 were identified near the benzoquinone ring of enzyme-bound decylubiquinone (dUQ) using the TrSqrF homology model. In silico analysis revealed that Val331 and Ile333 alternately connected with the quinone head group via hydrogen bonds, and Phe366 and Trp369 bound the quinones via hydrophobic interactions. TrSqrF variants containing alanine (V331A, I333A, F366A) and aromatic amino acid (V331F, I333F, F366Y), as well as a C-terminal α-helix deletion (CTD) mutant were generated. These amino acids are critical for quinone binding and, thus, catalysis. Spectroscopic analyses proved that all mutants contained FAD. I333F replacement resulted in the lack of the charge transfer complex. In summary, the interactions described above maintain the quinone molecule's head in an optimal position for direct electron transfer from FAD. Surprisingly, the CTD mutant retained a relatively high level of specific activity while remaining membrane-anchored. This is a unique study because it focuses on the QBS and the oxidative stage of a type VI sulfide-dependent quinone reduction. KEY POINTS: • V331, I333, F366, and W369 were shown to interact with decylubiquinone in T. roseopersicina SqrF • These amino acids are involved in proper positioning of quinones next to FAD • I333 is essential in formation of a charge transfer complex from FAD to quinone.