Background: Psoriasis is a chronic inflammatory skin disease regulated by autoimmunity, and pyroptosis plays an important role in this condition. This research sought to examine the function and potential molecular pathway of Gasdermin D (GSDMD) in psoriasis.
Methods: GSDMD expression was examined by immunohistochemistry in biopsied skin tissues from patients with psoriasis. Pyroptosis-related genes and inflammatory factors were quantified using qRT-PCR and ELISA, respectively. HaCaT cells were treated with M5 cytokines to develop an in vitro psoriasis model, while imiquimod (IMQ) was administered to construct an in vivo psoriasis model. To counteract the inhibition of the NOD-like receptor (NLR) pathway caused by GSDMD knockdown, the pathway activator M-TriDAP was employed.
Results: In the lesional skin tissues of patients with psoriasis, GSDMD expression was highly expressed. The levels of pro-pyroptosis mediators were increased, whereas the level of anti-inflammatory factor was lowered. GSDMD knockdown and disulfiram treatment inhibited pyroptosis and promoted apoptosis in M5-induced HaCaT cells. In the IMQ-induced psoriasis-like mouse model, GSDMD knockdown suppressed pyroptosis and improved skin lesion severity, alleviating erythema, epidermal thickness, and inflammatory cell infiltration. Mechanistically, GSDMD knockdown inhibited the NLR pathway, accompanied by reduced protein levels of NLRP3, NOD1, NOD2, and PYCARD. NLR pathway activator, M-TriDAP treatment significantly reversed the effects of GSDMD knockdown on psoriasis progression.
Conclusions: Knockdown of GSDMD inhibits pyroptosis in psoriasis by blocking the NLR signaling pathway, presenting a novel potential strategy for psoriasis treatment.
Sepsis is the leading cause of death among critically ill patients in clinical practice, making it urgent to reduce its incidence and mortality rates. In sepsis, macrophage dysfunction often worsens and complicates the condition. M1 and M2 macrophages, two distinct types, contribute to pro-inflammatory and anti-inflammatory effects, respectively. An imbalance between them is a major cause of sepsis. The aim of this study was to explore the potential of a differential metabolite between M1 and M2 macrophages in mitigating septic colonic injury via multiomics in combination with clinical data and animal experiments. Using nontargeted metabolomics analysis, we found that Kynurenic acid (KYNA), a metabolite of tryptophan metabolism, was significantly upregulated in the supernatant of M2 macrophages. Furthermore, we discovered that the level of KYNA was significantly decreased in sepsis in both human and mouse serum and was negatively correlated with inflammatory factor levels. In vivo experiments demonstrated that KYNA can effectively alleviate septic colon injury and reduce inflammatory factor levels in mice, indicating that KYNA plays a very important protective role in sepsis. Mechanistically, KYNA promotes the transition of M1 macrophages to M2 macrophages by inhibiting the NF-κB signaling pathway and alleviates septic colonic injury through the PPARγ/NF-κB axis. This article reveals that KYNA, a differentially abundant metabolite between M1 and M2 macrophages, can become a new strategy for alleviating septic colon injury.