This study reveals the critical role of INSIG1 in regulating macrophage inflammatory polarization, providing new experimental design ideas for research into the immunometabolic mechanisms of psoriasis, and suggesting that targeting the SREBP2-STAT1 axis may reshape the immune microenvironment.
Literature Overview
This paper, 'Macrophage INSIG1 Deficiency Drives Psoriasiform Dermatitis via the SREBP2-STAT1 Axis,' published in Nature Communications, systematically investigates how INSIG1 deficiency in macrophages promotes psoriasiform inflammation through the SREBP2-STAT1 signaling axis. By integrating bioinformatics analysis, single-cell sequencing, gene knockout mouse models, and in vitro functional experiments, the study uncovers a novel pathway linking cholesterol metabolism to inflammatory responses. Further analysis indicates that INSIG1 not only participates in lipid homeostasis regulation but also exerts non-canonical functions in immune regulation, particularly playing a key role in M1 macrophage polarization.Background Knowledge
Psoriasis is a chronic, relapsing autoimmune skin disorder whose pathogenesis involves aberrant crosstalk between the innate and adaptive immune systems. Although biologics targeting the IL-23/IL-17A axis have significantly improved clinical management, disease recurrence and comorbid metabolic disturbances suggest unresolved pathogenic drivers. In recent years, growing evidence indicates that lipid metabolic reprogramming plays a central role in regulating immune cell function, especially as macrophage polarization states are closely tied to their metabolic phenotypes. In this context, INSIG1, an endoplasmic reticulum-anchored protein, is a key node in regulating cholesterol biosynthesis pathways by inhibiting the activation of SREBP family transcription factors to maintain lipid homeostasis. However, its cell-specific functions in skin inflammation remain unclear, particularly the regulatory mechanisms during pathological M1 polarization. This study addresses this knowledge gap by focusing on the role of INSIG1 in macrophages, aiming to elucidate its immunometabolic crosstalk in psoriasis pathogenesis.
Research Methods and Experiments
The authors first performed correlation analysis using public RNA-seq datasets (GSE54456), revealing a significant negative correlation between INSIG1 expression and key inflammatory cytokines such as IL23A and IL17A. Subsequently, single-cell RNA sequencing (scRNA-seq) analysis of patient skin samples confirmed specific downregulation of INSIG1 in macrophages, with a trend toward reduced expression in dendritic cells. To validate these findings, the research team used immunofluorescence staining and flow cytometry to confirm decreased INSIG1 protein expression in CD68+ and F4/80+ macrophages in both human samples and IMQ-induced mouse models.
To investigate the in vivo function of INSIG1, the researchers generated Lyz2-Cre-mediated myeloid-specific [[Insig1] knockout] mice (Insig1flox/flox; Lyz2-Cre). In the IMQ-induced psoriasiform dermatitis model, Insig1cKO mice exhibited more severe skin thickening, inflammatory infiltration, and higher PASI scores, accompanied by significant expansion of γδ T cells, Th17, and Th1 cells. Using bone marrow-derived macrophages (BMDMs) and the THP-1 cell line, the study further demonstrated that INSIG1 deficiency promotes M1 polarization, upregulates expression of genes such as Nos2, Il12b, and Cxcl10, and enhances surface expression of CD86.Key Conclusions and Perspectives
Research Significance and Prospects
This study not only deepens our understanding of the immunometabolic mechanisms of psoriasis but also identifies the INSIG1-SREBP2-STAT1 axis as a potential therapeutic target. From a drug development perspective, targeting SREBP2 nuclear translocation or its interaction with the STAT1 promoter could become a novel strategy to suppress M1 polarization. Moreover, INSIG1 expression levels may serve as an auxiliary clinical indicator for monitoring disease activity.
In terms of disease modeling, this study supports the use of conditional gene knockout mice to simulate the complex immune-metabolic interactions in human diseases. Future studies could explore the efficacy of INSIG1 agonists or SREBP2 inhibitors in various autoimmune skin disorders, advancing the field from mechanistic research toward translational medicine.
Conclusion
This study systematically reveals the molecular mechanism by which INSIG1 deficiency in macrophages activates SREBP2, subsequently upregulating STAT1 expression, driving M1 polarization, and amplifying psoriasiform inflammation. This finding not only bridges cholesterol metabolism and inflammatory response pathways but also underscores the central role of immunometabolic reprogramming in autoimmune skin diseases. From bench to bedside, this mechanism provides a solid foundation for developing novel targeted therapies, offering new intervention strategies for patients unresponsive to current IL-23/IL-17A-targeted treatments. Future research may further explore the universality of the INSIG1 regulatory network in other chronic inflammatory diseases, advancing precision medicine strategies. This work marks a significant step forward in understanding the pathophysiology of psoriasis and holds promise for reshaping future care paradigms for this condition.
