Ludewig, Burkhard

The major barrier to clinical translation of αCD137 immunotherapy is separating antitumor efficacy from hepatotoxicity driven by IFN-γ–producing CD8 T cells. We propose a strategy to limit toxicity by promoting contraction of excessively expanded CD8 T cells. We identify CD11c + KLRG1 + effector CD8 T cells (CD11c + T E ) as the primary source of IFN-γ, recirculating between blood and secondary lymphoid organs (SLOs), where they undergo apoptosis during contraction. We show that lymphotoxin β receptor (LTβR) signaling restrains this contraction. Mechanistically, lymphotoxin-expressing B cells activate LTβR in fibroblastic reticular cells (FRCs), suppressing apoptosis of CD11c + T E cells in the spleen and sustaining their systemic circulation and liver infiltration. Pharmacological LTβR blockade abrogates hepatotoxicity by reducing the accumulation of IFN-γ–producing CD11c + T E cells while preserving tumor-specific CD8 T cell responses. These findings identify LTβR as a key regulator of effector CD8 T cell persistence and support the use of LTβR antagonists to improve the safety of αCD137-based immunotherapy.

Abstract Background and Aims Acute myocarditis (AM) is a T cell-mediated myocardial disease with clinical manifestations ranging from mild chest pain to cardiogenic shock. Reliable biomarkers to stratify patients and guide therapy are currently lacking. In particular, the extent of the dysregulation of inflammatory pathways, and the impact on myocardial dysfunction, remain elusive. Methods Serum analyses were performed in prospectively recruited AM patients (n = 103) from two independent cohorts. Multimodal data integration combining profiling of cytokine and chemokine dysregulation with clinical biomarkers was used to define clinical phenotypes with distinct inflammatory signatures. Machine-learning and regression models were applied to determine biomarkers that indicate clinical severity. Results Immuno-proteomic profiling revealed conserved inflammatory patterns across AM cohorts, dominated by T cell-related cytokines and chemokines. In addition, AM patients showed dysregulation of fibroblast-derived cytokines, including hepatocyte growth factor (HGF), bone morphogenic protein 4 (BMP4) and the BMP4 inhibitors Gremlin-1 (GREM1) and Gremlin-2 (GREM2). Data integration and unsupervised clustering revealed two immuno-clinical phenotypes, linking T cell activation and fibroblast dysregulation to disease severity. Machine learning-based analysis identified CXCL10, GREM2 and LVEF as critical parameters for stratifying disease severity. Conclusions These findings highlight a systemic T cell activation signature as diagnostic hallmark of AM. In addition, dysregulation of fibroblast-derived tissue cytokines serves as an indicator for distinct immuno-clinical phenotypes in myocardial inflammatory disease. Thus, the clinically relevant link between T cell-driven immune activation, myocardial inflammation and fibroblast-driven remodelling provides a versatile set of parameters to identify severe manifestations of AM. Graphical Abstract Key Question: Are serological immune signatures linked to clinical severity in acute myocarditis and do they enable patient stratification? Key Findings: T cell- and fibroblast associated proteomic signatures indicate disease severity in acute myocarditis. Novel immuno-clinical phenotypes stratify patients according to distinct immune responses and clinical manifestations. CXCL10, GREM2 and LVEF are the most important parameters to identify immuno-clinical phenotypes. Take Home Message: CXCL10, GREM2 and LVEF emerge as key determinants for a severe immuno-clinical phenotype in acute myocarditis, highlighting the role of T cell-fibroblast interaction in the disease process and linking T cell activation, fibroblastic tissue remodelling and impaired cardiac function.