HLA-E-expressing pluripotent stem cells escape allogeneic responses and lysis by NK cells

Abstract

Polymorphisms in the human leukocyte antigen (HLA) class I genes can cause the rejection of pluripotent stem cell (PSC)-derived products in allogeneic recipients. Disruption of the Beta-2 Microglobulin (B2M) gene eliminates surface expression of all class I molecules, but leaves the cells vulnerable to lysis by natural killer (NK) cells. Here we show that this ‘missing self’ response can be prevented by forced expression of minimally polymorphic HLA-E molecules. We use adeno-associated virus (AAV)-mediated gene editing to knock in HLA-E genes at the B2M locus in human PSCs in a manner that confers inducible, regulated, surface expression of HLA-E single-chain dimers (fused to B2M) or trimers (fused to B2M and a peptide antigen), without surface expression of HLA-A, B or C. These HLA-engineered PSCs and their differentiated derivatives are not recognized as allogeneic by CD8+ T cells, do not bind anti-HLA antibodies, and are resistant to NK-mediated lysis. Our approach provides a potential source of universal donor cells for applications where the differentiated derivatives lack HLA class II expression.

T-cells “à la CAR-T(e)” – Genetically engineering T-cell response against cancer

“…Alternatively, to prevent the rejection of the transferred cells, Ren et al demonstrated the feasibility of knocking down β2microglobulin, an essential component of all class I MHC molecules [347]. Though this approach might expose the HLA-knocked out engineered cells to NK activity, the latter may be neutralized if forcing the expression of regulatory HLA-E molecules [348].…”

Toward the development of true “off‐the‐shelf” synthetic T‐cell immunotherapy

“…Other strategy actively considered is generation of “the universal donor” iPSC by disrupting HLA genes. In addition to HLA deletion, a recent report showed that overexpression of HLA‐E in HLA‐deficient iPSCs reduced natural killer cell‐mediated rejection, which is augmented when HLA genes are disrupted …”

Next-Generation Chimeric Antigen Receptor T-Cell Therapy: Going off the Shelf

“…To prevent activation of natural killer cells through “missing self” recognition would be circumvented by enforced expression of non-classical HLA molecules such as HLA-E and HLA-G that can protect universal CART from NK-cell–mediated lysis. [62, 65] Another recent approach to reduce NK-cell toxicity to HLA-negative universal T cells is the overexpression of Siglec-7 and -9 ligands. [66] Another strategy to avoid rejection of HLA mismatched CART is the use of HLA homozygous donors to generate a bank of universal CART products.…”