SPRY1 Deficiency in Keratinocytes Induces Follicular Melanocyte Stem Cell Migration to the Epidermis through p53/Stem Cell Factor/C-KIT Signaling.

The function and survival of melanocytes is regulated by an elaborate network of paracrine factors synthesized mainly by epidermal keratinocytes (KCs). KCs and melanocytes respond to UV exposure by eliciting a tanning response. However, how KCs and melanocytes interact in the absence of UV exposure is unknown. In this study, we demonstrate that after SPRY1 knockout in epidermal KCs, melanocyte stem cells in the hair follicle exit the niche without depleting the pool of these cells. We also found that melanocyte stem cells migrate to the epidermis in a p53/stem cell factor/C-KIT-dependent manner induced by a tanning-like response resulting from SPRY1 loss in epidermal KCs. Once there, these cells differentiate into functional melanocytes. These findings provide an example in which the migration of melanocyte stem cells to the epidermis is due to loss of SPRY1 in epidermal KCs and show the potential for developing therapies for skin pigmentation disorders by manipulating melanocyte stem cells.

Biologics protect psoriasis patients from being exacerbated by COVID-19 infection.

Background: Patients with psoriasis may experience an exacerbation in symptoms following COVID-19 infection. After abandoning 'zero COVID' strategies, China experienced a surge of Omicron infections. Objectives: We aimed to investigate psoriasis exacerbation in psoriatic patients with COVID-19, following treatment with three different biologics, adalimumab, secukinumab, and ixekizumab. Methods: We performed a prospective study (n = 209) at our hospital between November 01, 2022, and February 15, 2023. We defined △ PASI as post-COVID-19 PASI minus pre-COVID-19 PASI. Two endpoints were set in this study. △ PASI >0 was defined as exacerbation of psoriasis after infection. △ PASI >3 was defined as a severe exacerbation of psoriasis symptoms after infection. In addition, serum OAS1, OAS2, and OAS3 were also assessed. Results: Results showed that the severity of psoriasis can worsen after COVID-19 infection, and a smaller proportion of patients taking biologics developed worsening psoriasis compared to those not using biologics; however, only the patients taking ixekizumab demonstrated a statistically significant difference (p < 0.05), while those taking adalimumab or secukinumab didn't. What's more, the use of biological agents suppressed the serum OAS2 and OAS3 at low levels and elevated the serum OAS1 level in patients with psoriasis. Conclusions: This study provided new insights into the protective role of biological agents in patients with psoriasis who were infected with COVID-19, and we proposed that psoriatic patients treated with biologics should continue with the treatment during the COVID-19 pandemic.

Glycyl-tRNA Synthetase Induces Psoriasis-Like Skin by Facilitating Skin Inflammation and Vascular Endothelial Cell Angiogenesis.

Psoriasis is characterized by excessive keratinocyte proliferation and immunocyte infiltration, but the underlying pathogenesis remains unclear. Aminoacyl-tRNA synthetases are universally expressed enzymes that catalyze the first step of protein synthesis. Glycyl-tRNA synthetase (GARS) is a member of the aminoacyl-tRNA synthetase family. In addition to its canonical function, we found that GARS was overexpressed in the serum and skin lesions of patients with psoriasis. Moreover, GARS was highly expressed in human skin keratinocytes, and GARS knockdown in keratinocytes suppressed cell proliferation and promoted apoptosis through NF-κB/MAPK signaling pathway. Moreover, intradermal injection of recombinant GARS protein caused skin thickening, angiogenesis, and IFN/TNF-driven skin inflammation. Intriguingly, the reported functional receptor for GARS, cadherin 6 (CDH6), was specifically expressed in vascular endothelial cells, and we found that keratinocyte-derived GARS promotes inflammation and angiogenesis of vascular endothelial cells through CDH6. In addition, intradermal injection of GARS aggravated the phenotype and angiogenesis in imiquimod-induced psoriasiform dermatitis models, whereas the psoriatic phenotype and angiogenesis were relieved after knockdown of GARS by adeno-associated virus. Taken together, the results of this study identify the critical role of GARS in the pathogenesis of psoriasis and suggest that blocking GARS may be a therapeutic approach for alleviating psoriasis.

Gradually increasing the dosing interval of Secukinumab for moderate to severe plaque psoriasis: A single-center, uncontrolled, prospective study in 36 weeks.

Secukinumab is a recombinant, fully human monoclonal anti-IL-17A antibody approved to treat moderate-to-severe psoriasis and psoriatic arthritis. Its effectiveness and safety have been confirmed, but a gradual increase in the secukinumab dosing interval has not been investigated. To assess the feasibility, efficacy, and safety of gradually increasing the secukinumab dosing interval; the interval duration was determined by changes in the Psoriasis Area and Severity Index scores. Patients with moderate-to-severe plaque psoriasis received secukinumab 300 mg subcutaneously at baseline and weeks 0, 1, 2, and 3. At week 4, the improvement from baseline PASI guided the next injection time until week 36. In total, 83 patients were recruited. PASI 75 was achieved by 80%, 96%, and 95% of patients at weeks 4, 12, and 36, respectively. PASI 90 was achieved by 54%, 95%, and 84% of patients at weeks 4, 12, and 36, respectively. PASI 100 was achieved by 28%, 89%, and 68% of patients at weeks 4, 12, and 36, respectively. The average PASI score (1.05 ± 1.83) was significantly lower at week 36 than at baseline. Most patients reached PASI 75 at week 36 in our modified study. This study may provide information for future biotherapies.

The role of Sprouty1 in the proliferation, differentiation and apoptosis of epidermal keratinocytes.

OBJECTIVES: Sprouty (SPRY) 1 is one of the SPRY proteins that inhibits signalling from various growth factors pathways and has also been known as a tumour suppressor in various malignancies. However, no study elucidates the role of SPRY1 in the skin. Our study was conducted to determine the function of SPRY1 in human keratinocytes and the epidermis. MATERIALS AND METHODS: In vitro primary cultured epidermal keratinocytes were used to investigate the proliferation, differentiation and apoptosis of these cells. We also established overexpression of SPRY1 in vitro and K14-SPRY1 transgenic mice. RESULTS: SPRY1 was mainly located in the cytoplasm of the epidermal keratinocytes from the granular epidermal layer of the skin and cultured cells. Overexpressed SPRY1 in keratinocytes resulted in up-regulation of P21, P27 and down-regulation of cyclin B1; decrease in MMP3 and integrin α6. SPRY1-overexpressed primary keratinocytes exhibited a lower proliferation and migration capability and higher rates of apoptosis. Epidermis of SPRY1-TG mice represented delayed wound healing. Proteomics analysis and GO enrichment showed DEPs of SPRY1 TG mice epidermis is significantly enriched in immune- and inflammatory-associated biological process. CONCLUSIONS: In summary, SPRY1 expression was inversely correlated with cell proliferation, migration and promote cell apoptosis of keratinocytes. SPRY1 maybe a negative feedback regulator in normal human epidermal keratinocytes and cutaneous inflammatory responses. Our study raised the possibility that enhancing expression of SPRY1 may have the potential to promote anti-inflammatory effects.

Role of keratin 24 in human epidermal keratinocytes.

Keratin 24 (K24) is a new kind of keratin genes, which encodes a novel keratin protein, K24 that bears high similarity to the type I keratins and displays a unique expression profile. However, the role of K24 is incompletely understood. In our study, we investigated the localization of K24 within the epidermis and possible functions. Keratin 24 was found to be modestly overexpressed in senescent keratinocytes and was mainly restricted to the upper stratum spinosum of epidermis. The protein was required for terminal differentiation upon CaCl2-induced differentiation. In vitro results showed that increased K24 in keratinocytes dramatically changed the differentiation of primary keratinocytes. It also inhibited cell survival by G1/S phase cell cycle arrest and induced senescence, autophagy and apoptosis of keratinocytes. In addition, K24 activated PKCδ signal pathway involving in cellular survival. In summary, K24 may be suggested as a potential differentiation marker and anti-proliferative factor in the epidermis.

Inhibition of the hedgehog pathway leads to antifibrotic effects in dermal fibrosis.

Dermal fibrosis is characterized by the activation of the matrix-producing 'positive' myofibroblasts, and the relentless production and deposition of extracellular matrix. The hedgehog pathway has recently been demonstrated to work in a pro-fibrotic manner in systemic sclerosis (SSc). A negative regulator of the hedgehog pathway (Hh), the suppressor of fused (Sufu), was shown to be involved in the activation of fibrotic diseases. However, the exact role of Sufu in fibrosis has not been investigated so far. In our study, we aimed to define the role of sufu in the process of fibrosis using dermal fibroblasts of healthy donors that were cultured in vitro. Cyclopamine, a Smo antagonist, and Sufu lentivector were used to treat or transfect cells. The expression of fibrosis markers and ERK1/2, Smad2, and GSK3ß at the protein level was determined by Western blot. Fibroblast migration was measured by in vitro wound healing assay. Bleomycin-induced dermal fibrosis mouse model was introduced to assess the effect of cyclopamine on dermal fibrosis in vivo. We found that cyclopamine significantly upregulated the expression of Sufu. Both cyclopamine and Sufu lentivector reduced migration and myofibroblast differentiation of human dermal fibroblasts at a statistically significant level. Furthermore, cyclopamine reversed dermal fibrosis induced by TGF-ß1. Cyclopamine and the overexpression of Sufu inhibited the phosphorylation of GSK-3ß and restrained the migration of fibroblasts. Dermal fibrosis was inhibited by intraperitoneal injection of cyclopamine in a mouse model of scleroderma. Our findings suggest that cyclopamine and Sufu-overexpression may effectively inhibit the endogenous as well as the TGF-ß1-induced activation of fibroblasts through subsequent activation of GSK-3ß. Sufu agonists may be a promising approach in the development of antifibrotic medications for dermal fibrosis and systemic sclerosis.

Analysis of epithelial-mesenchymal transition markers in psoriatic epidermal keratinocytes.

Psoriasis is similar to endpoints of epithelial-mesenchymal transition (EMT), a process of epithelial cells transformed into fibroblast-like cells. The molecular epithelial and mesenchymal markers were analysed in psoriatic keratinocytes. No obvious alteration of epithelial markers E-cadherin (E-cad), keratin 10 (K10), K14 and K16 was detected in psoriatic keratinocytes. However, significantly increased expression of Vim, FN, plasminogen activator inhibitor 1 (PAI-1) and Slug was seen. IL-17A and IL-13 at 50 ng ml(-1) strongly decreased expression of K10, Vim and FN. TGF-ß1 at 50 ng ml(-1) promoted the production of N-cad, Vim, FN and PAI-1. Slug was decreased by dexamethasone (Dex), but E-cad was upregulated by Dex. Silencing of ERK partially increased E-cad and K16, but remarkably inhibited K14, FN, Vim, ß-catenin, Slug and α5 integrin. Moreover, inhibition of Rho and GSK3 by their inhibitors Y27632 and SB216763, respectively, strongly raised E-cad, ß-catenin and Slug. Dex decreased Y27632-mediated increase of ß-catenin. Dex at 2.0 µM inhibited SB216763-regulated E-cad, ß-catenin and slug. In conclusion, EMT in psoriatic keratinocytes may be defined as an intermediate phenotype of type 2 EMT. ERK, Rho and GSK3 play active roles in the process of EMT in psoriatic keratinocytes.