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.

A cytotoxic survey on 2-amino-1H-imidazol based synthetic marine sponge alkaloid analogues.

Here, we describe the synthesis and biologic activity evaluation of 20 novel synthetic marine sponge alkaloid analogues with 2-amino-1H-imidazol (2-AI) core. Cytotoxicity was tested on murine 4T1 breast cancer, A549 human lung cancer, and HL-60 human myeloid leukemia cells by the resazurin assay. A total of 18 of 20 compounds showed cytotoxic effect on the cancer cell lines with different potential. Viability of healthy human fibroblasts and peripheral blood mononuclear cells upon treatment was less hampered compared to cancer cell lines supporting tumor cell specific cytotoxicity of our compounds. The most cytotoxic compounds resulted the following IC50 values 28: 2.91 µM on HL-60 cells, and 29: 3.1 µM on 4T1 cells. The A549 cells were less sensitive to the treatments with IC50 15 µM for both 28 and 29. Flow cytometry demonstrated the apoptotic effect of the most active seven compounds inducing phosphatidylserine exposure and sub-G1 fragmentation of nuclear DNA. Cell cycle arrest was also observed. Four compounds caused depolarization of the mitochondrial membrane potential as an early event of apoptosis. Two lead compounds inhibited tumor growth in vivo in the 4T1 triple negative breast cancer and A549 human lung adenocarcinoma xenograft models. Novel marine sponge alkaloid analogues are demonstrated as potential anticancer agents for further development.

Could basement membrane alterations, resembling micro-wounds at the dermo-epidermal junction in psoriatic non-lesional skin, make the skin susceptible to lesion formation?

Current data suggest that tissue microenvironment control immune functions. Therefore, understanding the tissue environment in which immune activation occurs will enhance our capability to interfere with abnormal immune pathology. Here, we argue that studying the constitutively abnormal functions of clinically uninvolved psoriatic skin in patients with plaque type psoriasis is very important to better understand psoriasis pathobiology, because non-lesional skin provides the tissue environment in which the psoriatic lesion develops. A key question in psoriasis is what initiates the abnormal, uncontrolled immune activation in the first place and the answer may lie in the skin. In light of this concept, we summarize abnormalities at the dermal-epidermal junction region which shows a special "non-healing-like" micro-wound phenotype in the psoriatic non-lesional skin that may act as a crucial susceptibility factor in the development of the disease.

Abnormal basement membrane results in increased keratinocyte-derived periostin expression in psoriasis similar to wound healing.

The psoriatic skin resembles wound healing, and it shows abnormalities at the basement membrane (BM), also in the non-lesional skin. Fibroblast-derived dermal periostin has well-known functions in wound healing and Th2-mediated diseases, such as atopic dermatitis. Here we show that serum periostin level was elevated in psoriatic patients, remarkably in the systemically treated ones. Obvious periostin positivity was detected in basal keratinocytes of the non-lesional, lesional, and previously-lesional psoriatic vs. healthy skin. Ex vivo skin models were generated to examine how different skin injuries affect periostin expression during wound healing. Our newly developed cultured salt-split model demonstrated that BM-injury induced periostin expression in basal keratinocytes, and periostin levels in the supernatant were also increased upon healing. In wound healing models, ß1-integrin expression was similarly induced. ß1-integrin blocking caused reduced periostin expression in in vitro scratch assay, indicating that ß1-integrin can mediate periostin production. In contrast to atopic dermatitis, psoriatic basal keratinocytes are in an activated state and show a stable wound healing-like phenotype with the overexpression of periostin. This abnormal BM-induced wound healing as a potential compensatory mechanism can be initiated already in the non-lesional skin present in the lesion and keratinocytes can remain activated in the healed skin.

Phenotypic plasticity of melanocytes derived from human adult skin.

We previously described a novel in vitro culture technique for dedifferentiated human adult skin melanocytes. Melanocytes cultured in a defined, cholera toxin and PMA free medium became bipolar, unpigmented, and highly proliferative. Furthermore, TRP-1 and c-Kit expression disappeared and EGFR receptor and nestin expression were induced in the cells. Here, we further characterized the phenotype of these dedifferentiated cells and by comparing them to mature pigmented melanocytes we detected crucial steps in their phenotype change. Our data suggest that normal adult melanocytes easily dedifferentiate into pluripotent stem cells given the right environment. This dedifferentiation process described here for normal melanocyte is very similar to what has been described for melanoma cells, indicating that phenotype switching driven by environmental factors is a general characteristic of melanocytes that can occur independent of malignant transformation.

Stress-Related Regulation Is Abnormal in the Psoriatic Uninvolved Skin.

Keratinocyte stress-response of the uninvolved psoriatic epidermis is known to be altered compared to healthy cells. Therefore, we aimed to reveal potential mechanisms underlying this alteration. We compared the expression of annotated cell-stress-related proteins between uninvolved psoriatic and healthy skin using the protein array method. Data were analyzed by the Reactome over-representation test. We found that p27/CDKN1B and cytochrome C showed at least a two-fold increase, while cyclooxygenase-2, indolamine-2,3-dioxygenase-1, serum paraoxonase 1, serum paraoxonase 3, serine-46-phosphorylated tumor protein p53, and superoxide-dismutase-2 showed a two-fold decrease in expression in the uninvolved skin. Over-representation analysis suggested the Forkhead-box protein O (FOXO)-mediated transcription as the most significant pathway affected by the differently expressed cell-stress-related proteins (DECSRPs). DECSRPs indicate increased FOXO-mediated transcription of cell-cycle genes and reduced interleukin-signaling in the psoriatic uninvolved skin. Nuclear positivity of the FOXO-signaling-related p27/CDKN1B and FOXO1 are negatively correlated with the disease severity and showed increased expression in the uninvolved epidermis and also in healthy primary keratinocytes, which were grown on cartilage oligomeric matrix protein-coated surfaces. Our results indicate a cell-cycle inhibitory process, as a stress-related compensatory mechanism in the uninvolved epidermis, that could be responsible for blocking keratinocyte hyperproliferation in the psoriatic uninvolved skin, thus maintaining the symptomless skin phenotype.