Postdoctoral Trainee University of California Los Angeles, CA
Aim: Ischemia-reperfusion injury (IRI) significantly contributes to graft dysfunction and rejection risk in orthotopic liver transplantation (OLT). Interactions between post-transplant cytokine dynamics, immune cell activation, and the formation of donor-specific antibodies (DSAs), particularly de novo DSAs (dnDSAs), remain unclear. This study investigated immune signatures, including dnDSAs, and their clinical impact on patient outcomes.
Methods: Longitudinal PBMCs (n=55 OLT patients; IRI+=27, IRI-=28) underwent multicolor flow cytometry, Luminex cytokine profiling, HEK-Blue assays and DSA analysis at pre-op, early (1-4 months), and late (>6 months) post-OLT timepoints. Monocyte differentiation, T-cell activation, and humoral responses (circulating T-follicular helper [Tfh] cells and plasma B-cells) were evaluated. PCA and clustering analyses correlated immune profiles, cytokines, and dnDSA formation with IRI status and survival.
Results: IRI+ patients had significantly higher early pro-inflammatory cytokines (IL-17A, IL-1b, IL-17E/IL-25, IFNa2, IL-1a, IL-4, MIP-1a; p<0.05). PCA distinguished acute-phase inflammation from late-stage inflammation. Late-stage survivors exhibited significantly lower TNF-α (p=0.0057), IL-8 (p=0.0009), and IL-15 (p=0.0184) versus non-survivors. IRI+ patients demonstrated enhanced early classical monocyte activation (HLADR+cMO) correlating with disulfide-HMGB1 levels (r=0.43; p=0.04). Plasma reactivity to TLR4 and TLR9 correlated with increased HLADR+cMO (r=0.40; p=0.05) and CD40L+cMO (r=0.47; p=0.01). IRI+ patients exhibited increased alloreactive memory CD4+ T-cell expansion and sustained CD69+, IFN-γ, and IL-17A activation upon donor cell stimulation. Critically, dnDSAs were significantly elevated in IRI+ patients, with marked fold-changes correlating with increased circulating Tfh and plasma B-cell populations, underscoring a potent humoral response linked to poor clinical outcomes.
Conclusion: IRI initiates a cascade of early monocyte activation and heightened TLR4/TLR9 plasma responsiveness promoting dnDSA formation through expansion of circulating Tfh and plasma B-cell populations. Targeting IRI may be a critical strategy to mitigate early inflammation and dnDSA development, thereby improving graft function and long-term patient outcomes.
