Leveraging advanced spatial proteomics, scientists have identified the JAK/STAT pathway as a critical target for treating toxic epidermal necrolysis, offering new hope for patients with this life-threatening skin disease.
Disease course in a patient with TEN (SCORTEN 4) associated with cancer treatment. Disease progression was observed during high-dose intravenous methylprednisolone treatment and the patient developed persistent hyperglycaemia. JAK1i rescue therapy with abrocitinib was initiated on day 4, resulting in visible cessation of progression within 48 h and initial re-epithelialization within 4 days. Top, photographs of the back of the patient, showing the degree of re-epithelialization at the indicated timepoints after hospital admission. Bottom, Treatment schedule. Arrow marks start of abrocitinib treatment. Study: Spatial proteomics identifies JAKi as treatment for a lethal skin disease
In a recent study published in the journal Nature, researchers tested Janus kinase inhibitors (JAKi) as potential treatments for drug-induced skin reactions, including toxic epidermal necrolysis (TEN), using deep visual proteomics (DVP) to analyze skin biopsies from patients. They identified them as key drivers of TEN (JAK/STAT [signal transducers and activators of transcription] and interferon signaling pathways) and showed that JAKi reduced disease severity and promoted recovery in both mouse models and human patients.
Background
The skin is highly affected by adverse drug reactions (ADRs), with about 2% of these being severe and fatal. Cutaneous adverse drug reactions (CADRs) range from mild maculopapular rashes (MPRs) to serious conditions like Stevens–Johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), and TEN. In TEN, researchers noted a significant increase in inflammatory proteins, especially those related to interferon signaling and oxidative stress markers. TEN involves over 30% skin detachment and has a mortality rate of one-third, while the SJS–TEN overlap affects 10–30% of the skin. Despite various proposed mechanisms, the exact causes of cytotoxicity remain unclear, with treatment primarily focusing on supportive care.
Spatial omics have emerged as a valuable method for analyzing intact tissue samples at the single-cell level. In this study, spatial proteomics revealed key proteomic signatures associated with TEN that were distinct from less severe conditions like DRESS. DVP provides spatial proteomics data from formalin-fixed paraffin-embedded (FFPE) biopsies using imaging, artificial intelligence-based cell segmentation, laser microdissection, and advanced mass spectrometry (MS) for proteomic analysis. In the present study, researchers employed DVP to explore the molecular characteristics and mechanisms behind various CADRs and functionally validated targeted small-molecule inhibitors for the treatment of TEN, the most severe form of CADR.
About the study
Skin biopsies from seven patients with TEN or SJS-TEN overlap were collected during routine diagnostic procedures, along with patient characteristics.A multiplexed data-independent acquisition (mDIA) workflow utilizing the Astral mass analyzer was employed to investigate immune cells, specifically CD163+ macrophages, CD4+ T helper cells, and CD8+ cytotoxic T cells in the samples.
Spatial proteome analysis examined the differences between detached and attached keratinocytes from the same biopsy, highlighting proteins associated with the complement system and inflammation. This analysis revealed that macrophages showed the highest expression of interferon-driven proteins, such as STAT1, compared to CD4+ and CD8+ T cells.
Additionally, the JAK/STAT pathway was analyzed by identifying six upregulated proteins common to keratinocytes and immune cells. Targeted transcriptomics assessed cytokine gene expression, confirming broad upregulation of JAK and STAT molecules in TEN.
An autologous co-culture model was developed to replicate aspects of CADRs, testing the pan-JAK inhibitor tofacitinib. The efficacy of JAK1 inhibitors abrocitinib and upadacitinib was evaluated in established mouse models of TEN and a humanized mouse model using peripheral blood mononuclear cells from a TEN survivor.
Further, in human studies, off-label JAKi treatment was administered to seven patients with TEN or SJS–TEN overlaps, monitoring recovery and STAT1 phosphorylation levels. Patients with infections were excluded.
Results and discussion
A median of 2,104 proteins were identified. The proteomic findings highlighted distinct signatures between TEN and DRESS. DRESS and TEN showed distinct proteomic profiles in lesional keratinocytes. In TEN, there was a notable increase in antimicrobial proteins and a decrease in superoxide dismutase 1, indicating worsened oxidative stress. DRESS keratinocytes showed more than double the levels of major histocompatibility complex class I proteins, suggesting enhanced antigen presentation.
In lesional immune cells, DRESS was enriched in viral pathways and had the highest number of differentially expressed proteins, including the unique histone methylase EZH2. In contrast, TEN showed a dominant interferon signature driven by STAT1. The study also highlighted that interferon pathway activation was especially pronounced in macrophages, which play a key role in the immune response in TEN. DRESS cells were enriched for deoxyribonucleic acid (DNA) replication processes, while TEN cells were associated with type I and II interferon (IFN) signaling.
The proteomic analysis revealed that macrophages exhibited the highest expression of interferon pathway proteins, particularly STAT1, compared to CD4+ and CD8+ T cells. In spatial proteome analysis, proteins linked to the complement system and inflammation were upregulated in both attached and detached keratinocytes, indicating active inflammatory pathways.
In the JAK/STAT pathway investigation, six proteins—WARS1, STAT1, S100A9, LYZ, GBP1, and APOL2—were significantly upregulated in both keratinocytes and immune cells in TEN, confirming pathway activation.
Among cytokine genes, IFNG showed the most significant elevation. The paper demonstrated that this upregulation was linked to keratinocyte-directed cytotoxicity and epidermal detachment, contributing to the severe pathology observed in TEN. The in vitro and in vivo models demonstrated that PBMCs effectively killed keratinocytes, inhibited by the pan-JAK inhibitor tofacitinib.
In mouse models of TEN, JAKi treatment reduced disease severity, keratinocyte death, and immune cell infiltration. In clinical applications, all the seven patients treated with JAKi survived, showing significant clinical improvement within days. Cutaneous levels of phosphorylated STAT1 decreased after treatment, highlighting the potential of JAK inhibitors for managing TEN.
Conclusion
In conclusion, the study demonstrates the utility of integrating emerging cell-type-resolved spatial omics technologies, particularly spatial proteomics, to discover new treatment options that benefit patients.
The spatial proteomics approach allowed researchers to identify critical molecular targets like STAT1, which was upregulated in both keratinocytes and immune cells, offering new insights into the pathogenesis of TEN. This approach could potentially revolutionize the treatment of various inflammatory and oncological conditions by identifying key druggable targets and enabling more precise treatment selection.
The findings highlight the potential of JAKi therapy as a candidate for clinical trials to improve outcomes among patients with TEN.