Core Signature of Rejection-Associated Cytokines and Chemokines in Endomyocardial Biopsies after Heart Transplantation

Lena ML Radomsky¹Jenny F Kuehne¹Kerstin Beushausen¹Jana Keil¹Ludmilla Knigina²Yves Scheibner²Adelheid Görler²Arjang Ruhparwar²Fabio Ius²Christoph L Bara²Christine S Falk^1,3*

• ¹Institute of Transplant Immunology, Hannover Medical School, Hanover, Germany
• ²Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hanover, Germany
• ³German Center for Infection Research (DZIF), partner-site Hannover-Braunschweig, Hannover, Germany

Background: Rejection remains a limiting factor for survival after heart transplantation (HTx) and predictive biomarkers are still missing. Therefore, our aim was to define the cytokine/chemokine microenvironment in endomyocardial biopsies (EMB) and plasma after HTx and to identify patterns, which reflect ischemia/reperfusion injury as well as allograft rejection. Therefore, we hypothesize distinct cytokine/chemokine patterns in heart biopsies with histopathologically proven rejection compared to the microenvironment in unsuspicious biopsies.Methods: EMB (n=181; n=52 patients) and peripheral blood samples (n=147; n=52 patients) were obtained between 6 days and 5 years after HTx. 50 immune proteins in EMB tissue lysates and plasma were quantified and concentrations were compared between EMB with and without histopathologically defined acute rejection (AR) and correlation analyses between tissue and plasma were performed.Results: Regarding rejection status, distinct cytokine/chemokine patterns were identified with significantly higher concentrations of CCL4, CXCL9 and CXCL10 in EMB with acute rejection (p<0.001). In addition, we identified individual long-term dynamics of patients after HTx associated with rejection. Elevated chemokine concentrations were detected also in EMB of patients with DSA. Moreover, significantly different patterns were observed between heart tissue and plasma without direct correlations.A core signature was defined for EMB with histopathologically proven AR, consisting of high concentrations of CXCL9, CXCL10, CCL3 and CCL4. This EMB chemokine signature was clearly distinct from plasma samples arguing for a local protein microenvironment associated with AR. Further research is needed also with the help of AI to translate the different approaches for detection and prediction of AR into clinical practice.