Engineering AMR-on-a-chip to probe rejection and accommodation pathways

About This Grant

TITLE: Engineering AMR-on-a-chip to probe rejection and accommodation pathways Abstract Kidney transplantation is the preferred treatment for patients with end-stage renal disease (ESRD), offering improved quality of life, reduced long-term mortality and morbidity, and lower healthcare costs compared to dialysis. However, antibody-mediated rejection (AMR) remains a major obstacle to achieve long-term graft survival. Despite its clinical significance, investigating the pathogenesis of AMR remains challenging due to the immunological and physiological complexities of the disease in vivo, and the lack of in vitro models that faithfully replicate its pathological features. To address this unmet need, we aim to develop and validate an AMR-on-a- chip platform to recapitulate key features of AMR in vitro (Aim 1). We have developed a glomerulus-on-a-chip model using human induced pluripotent stem cell (iPSC)-derived renal endothelial cells (ECs) and podocytes. This model successfully mimics the structure and function of the glomerular filtration barrier. To induce AMR, we will incorporate immune components required to its pathogenesis, including pathological antibodies (single anti- HLA Ab, patient derived serum DSA anti-ABO Ab, and autoimmune Ab targeting podocytes), complement, and innate immune cells. Our preliminary data also demonstrate that targeting complement pathways can provide transient protection against AMR in the presence of high levels of donor-specific antibodies (DSAs), suggesting the possibility of inducing a state of accommodation. In addition, we have developed novel endopeptidases capable of selectively cleaving IgM alone or both IgG and IgM. In Aim 2, we will evaluate therapeutic strategies targeting complement and immunoglobulins using our AMR-on-a-chip platform reconstructed with the full spectrum of immune components. Specifically, we will test the efficacy of complement inhibitors (anti-C3 and anti-C5) and novel endopeptidases (IdeS, IceM and IceMG) in mitigating AMR and promoting durable protection of renal endothelial cells and podocytes upon re-exposure to pathological antibodies, a process referred to as accommodation. We hypothesize that downstream signaling triggered by HLA, ABO, or autoimmune antigens, in the absence of complement-mediated injury, may upregulate protective genes in target cells, rendering them resistant to subsequent immune challenges. This study will clarify the roles of pathological antibodies, complement, and innate immune cells in AMR; explore the possibility of antibody-independent mechanisms; and assess the local efficacy of therapeutic agents in preventing AMR in the transplant setting.