Gasdermin E-mediated keratinocyte pyroptosis participates in the pathogenesis of psoriasis by promoting skin inflammation.

Psoriasis is a common chronic inflammatory disease with an unclear aetiology. Keratinocytes in psoriasis are susceptible to exogenous triggers that induce inflammatory cell death. To investigate whether gasdermin E (GSDME)-mediated pyroptosis in keratinocytes contributes to the pathogenesis of psoriasis. Skin samples from patients with psoriasis and from healthy controls were collected to evaluate the expression of GSDME, cleaved caspase-3 and inflammatory factors. We then analysed the data series GSE41662 to further compare the expression of GSDME between lesional and nonlesional skin samples in those with psoriasis. In vivo, a caspase-3 inhibitor and GSDME-deficient mice (Gsdme-/-) were used to block caspase-3/GSDME activation in an imiquimod-induced psoriasis model. Skin inflammation, disease severity and pyroptosis-related proteins were analysed. In vitro, tumour necrosis factor (TNF)-α-induced caspase-3/GSDME-mediated pyroptosis in the HACAT cell line was explored. Our analysis of the GSE41662 data series found that GSDME was upregulated in psoriasis lesions vs. normal skin. High levels of inflammatory cytokines such as interleukin (IL)-1β, IL-6 and TNF-α were also found in psoriasis lesions. In mice in the Gsdme-/- and caspase-3 inhibitor groups, the severity of skin inflammation was attenuated and GSDME and cleaved caspase-3 levels decreased after imiquimod treatment. Similarly, IL-1β, IL-6 and TNF-α expression was decreased in the Gsdme-/- and caspase-3 inhibitor groups. In vitro, TNF-α induced HACAT cell pyroptosis through caspase-3/GSDME pathway activation, which was suppressed by blocking caspase-3 or silencing Gsdme. Our study provides a novel explanation of TNF-α/caspase-3/GSDME-mediated keratinocyte pyroptosis in the initiation and -acceleration of skin inflammation and the progression of psoriasis.

Li Y ，He Y ，Yang F ，Liang R ，Xu W ，Li Y ，Cheng J ，Liang B ，Tang M ，Shi X ，Zhuang J ，Luo M ，Li L ，Zhang R ，Liu H ，Jie H ，Li X ，Han X ，Sun E ，Zhai Z ... -  《-》

Gasdermin E promotes translocation of p65 and c-jun into nucleus in keratinocytes for progression of psoriatic skin inflammation.

Gasdermin E (GSDME) has recently been identified as a critical executioner to mediate pyroptosis. While epidermal keratinocytes can initiate GSDME-mediated pyroptosis, the role of keratinocyte GSDME in psoriatic dermatitis remains poorly characterized. Through analysis of GEO datasets, we found elevated GSDME levels in psoriatic lesional skin. Additionally, GSDME levels correlated with both psoriasis severity and response to biologics treatments. Single-cell RNA sequencing (scRNA-seq) from a GEO dataset revealed GSDME upregulation in keratinocytes of psoriasis patients. In the imiquimod (IMQ)-induced psoriasis-like dermatitis mouse model, both full-length and cleaved forms of caspase-3 and GSDME were elevated in the epidermis. Abnormal proliferation and differentiation of keratinocytes and dermatitis were attenuated in Gsdme-/- mice and keratinocyte-specific Gsdme conditional knockout mice after IMQ stimulation. Exposure of keratinocytes to mixed cytokines (M5), mimicking psoriatic conditions, led to GSDME cleavage. Moreover, the interaction between GSDME-FL and p65 or c-jun was significantly increased after M5 stimulation. GSDME knockdown inhibited nuclear translocation of p65 and c-jun and decreased upregulation of psoriatic inflammatory mediators such as IL1β, CCL20, CXCL1, CXCL8, S100A8, and S100A9 in M5-challenged keratinocytes. In conclusion, GSDME in keratinocytes contributes to the pathogenesis and progression of psoriasis, potentially in a pyroptosis-independent manner by interacting and promoting translocation of p65 and c-jun. These findings suggest that keratinocyte GSDME could serve as a potential therapeutic target for psoriasis treatment.

Long F ，Wei X ，Chen Y ，Li M ，Lian N ，Yu S ，Chen S ，Yang Y ，Li M ，Gu H ，Chen X ... -  《Cell Death & Disease》

Gasdermin D-mediated keratinocyte pyroptosis as a key step in psoriasis pathogenesis.

Gasdermin D (GSDMD)-mediated pyroptosis has a significant pro-inflammation characteristic due to dramatic secretion of pro-inflammatory substances. However, its role remains unclear in psoriasis as one chronic inflammatory skin disorder with high prevalence. We found that N-terminal GSDMD (N-GSDMD) was aberrantly expressed in epidermis of skin lesion in psoriasis patients and imiquimod-induced psoriasis-like dermatitis (IIPLD) mice. In epidermis of IIPLD mice and M5 (simulating psoriatic inflammatory challenge)-treated keratinocytes cultured in vitro, cleavage products of caspase-1, GSDMD and IL-1β were increased. M5-stimulated keratinocyte presented typical pyroptosis morphology accompanied with PI-staining. Gsdmd-/- keratinocytes could not present pyroptosis morphology while stimulated with M5. Electroporation of recombinant N-GSDMD could make the pyroptosis morphology reappear. In Gsdmd-/- mice or keratinocyte-specific Gsdmd conditional knockout mice, we observed the alleviation of psoriatic inflammation and epidermal aberrant expression of Ki-67 and differentiation markers (loricrin and keratin 5) after imiquimod stimulation. Transplanting skin tissue from control mice to Gsdmd-/- mice can evoke the response to imiquimod stimulation in the background of Gsdmd-/- mice (not limited in transplanting area). In M5-stimulated keratinocytes, disulfiram or GSDMD siRNA transfection can inhibit pyroptosis and eliminate disproportionate increases of Ki-67 and PI. We further validated that topically application of disulfiram (pyroptosis inhibitor) also alleviated IIPLD in mice. These findings indicate a novel mechanism that GSDMD-mediated keratinocyte pyroptosis facilitates hyperproliferation and aberrant differentiation induced by immune microenvironment in psoriatic skin inflammation, which contributes to pathogenesis of psoriasis. Our study provides an innovative insight that targeting pyroptosis can be considered as a therapeutic strategy against psoriasis.

Lian N ，Chen Y ，Chen S ，Zhang Y ，Chen H ，Yang Y ，Gu H ，Chen Q ，Li M ，Chen X ... -  《Cell Death & Disease》

Wogonin ameliorates the proliferation, inflammatory response, and pyroptosis in keratinocytes via NOD-like receptor family pyrin domain containing 3/Caspase-1/Gasdermin-D pathway.

Psoriasis refers to a highly prevalent and immunologically mediated dermatosis with considerable deterioration in life quality. Wogonin, a sort of flavonoid, has been mentioned to elicit protective activities in skin diseases. However, whether Wogonin is implicated in the treatment of psoriasis and its specific mechanisms are not fully understood. The present work attempted to elaborate the role of Wogonin during the process of psoriasis and to concentrate on the associated action mechanism. Cell counting kit-8 (CCK-8) method was initially applied to assay the viability of human keratinocyte HaCaT cells treated by varying concentrations of Wogonin. To mimic psoriasis in vitro, HaCaT cells were exposed to M5 cytokines. CCK-8 and 5-Ethynyl-2'-deoxyuridine  assays were adopted for the measurement of cell proliferation. Inflammatory levels were examined with enzyme-linked immunosorbent assay. Immunofluorescence staining tested nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) and Caspase-1 expressions. Western blot examined the protein expressions of proliferation-, inflammation-, pyroptosis-associated factors, and NLRP3. Wogonin treatment antagonized the proliferation, inflammatory response, and NLRP3/caspase-1/Gasdermin-D (GSDMD)-mediated pyroptosis in M5-challenged HaCaT cells. Besides, NLRP3 elevation partially abrogated the effects of Wogonin on M5-induced proliferation, inflammatory response, and NLRP3/caspase-1/GSDMD-mediated pyroptosis in HaCaT cells. In a word, Wogonin might exert anti-proliferation, anti-inflammatory and anti-pyroptosis activities in M5-induced cell model of psoriasis and the blockade of NLRP3/Caspase-1/GSDMD pathway might be recognized as a potential mechanism underlying the protective mechanism of Wogonin in psoriasis, suggesting Wogonin as a prospective anti-psoriasis drug.

Ma J ，Ji C ，Sun Y ，Liu D ，Pan K ，Wei Y ... -  《Immunity Inflammation and Disease》

Inhibiting apoptosis and GSDME-mediated pyroptosis attenuates hepatic injury in septic mice.

Sepsis is characterized by severe inflammation and organ dysfunction resulting from a dysregulated organismal response to infection. Although pyroptosis has been presumably shown to be a major cause of multiple organ failure and septic death, whether gasdermin E (GSDME)-mediated pyroptosis occurs in septic liver injury and whether inhibiting apoptosis and GSDME-mediated pyroptosis can attenuate septic liver injury remain unclear. This study investigated the role of apoptosis and GSDME-mediated pyroptosis in septic liver injury. Adult male C57BL/6 mice were randomly divided into four groups: sham, cecal ligation puncture (CLP), CLP + Z-DEVD-FMK (a caspase-3 inhibitor, 5 mg/kg), and CLP + Ac-DMLD-CMK (a GSDME inhibitor, 5 mg/kg). Sepsis severity was assessed using the murine sepsis score (MSS). Hepatic tissue damage was observed by the hematoxylin-eosin staining method, the activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the levels of malondialdehyde (MDA), the concentrations of interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were measured according to the related kits, and the changes in the hepatic tissue reactive oxygen species (ROS) levels were detected by immunofluorescence (IF). The protein expression levels of cleaved caspase-3, GSDME-N, IL-1β, B-cell lymphoma-2 (Bcl-2), cytochrome C (Cyt-c), and acetaldehyde dehydrogenase 2 (ALDH2) were detected using western blotting. GSDME expression was detected by immunohistochemistry. Compared with the Sham group, CLP mice showed high sepsis scores and obvious liver damage. However, in the CLP + Z-DEVD-FMK and CLP + Ac-DMLD-CMK groups, the sepsis scores were reduced and liver injury was alleviated. Compared with the Sham group, the serum ALT and AST activities, MDA and ROS levels, and IL-1β and TNF-α concentrations were increased in the CLP group, as well as the protein expression of cleaved caspase-3, GSDME-N, IL-1β, Cyt-c, and GSDME positive cells (P < 0.05). However, the expression levels of Bcl-2 and ALDH2 protein were decreased (P < 0.05). Compared with the CLP group, the CLP + Z-DEVD-FMK and CLP + Ac-DMLD-CMK groups showed low sepsis scores, ALT and AST activities, MDA and ROS levels, decreased IL-1β and TNF-α concentrations, and decreased expression of cleaved caspase-3, GSDME-N, IL-1β protein expression, and GSDME positive cells (P < 0.05). The expression levels of Bcl-2 and ALDH2 protein were increased (P < 0.05). Apoptosis and GSDME-mediated pyroptosis are involved in the development of sepsis-induced hepatic injury. Inhibition of apoptosis and GSDME-mediated pyroptosis attenuates injury. ALDH2 plays a protective role by inhibiting apoptosis and pyroptosis.

Lu N ，Qin H ，Meng Z ，Yu Y ，Gao Q ，Cheng Z ，Liu C ，Hu J ... -  《-》