Researchers uncover the potential of JAK inhibitors to treat life-threatening skin disease

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.

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

TEN patients often suffer from complications like sepsis, pneumonia, and multiple organ failure, leading to a high mortality rate of 25–50%.

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.

Stevens-Johnson syndrome (SJS) is considered a milder form of TEN, with less than 10% of the body surface area affected.

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

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.

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.