Genetically engineered CD4 T cells as a novel immunotherapy against drug resistant Klebsiella pneumoniae infections

Abstract With mortality rates ranging from 30% to 70%, carbapenem-resistant Klebsiella pneumoniae (Kp) is a significant public health threat. With growing incidence of drug resistance, it is imperative to develop alternative strategies to combat these severe infections. One novel immunotherapy is adoptive T cell transfer therapy using T cells genetically modified to express a T cell receptor (TCR) specific to an antigen of interest. Though successful against cancers and viral infections, this strategy has yet to be utilized for bacterial infections. Our study’s objective was to validate adoptive transfer as an immunotherapy against Kp infections using CD4 T cells from immunized mice. Further, we sought to identify TCRs specific to Kp epitopes for the generation of engineered Kp specific T cells. CD45.1 WT mice were intratracheally vaccinated with outer membrane protein X (OmpX) adjuvanted with heat-labile enterotoxin A1 twice at three weeks apart. Lung and splenic CD4 T cells from immunized mice were transferred into CD45.2 WT mice, followed by a challenge with Kp ST258 C4 strain. Immunized CD4 T cells were sequenced by single cell TCRseq to identify Kp specific TCR sequences. OmpX immunization resulted in a robust population of Kp specific Th17 cells in the lungs. Adoptive transfer of lung, but not splenic T cells from immunized mice significantly reduced bacterial burdens in challenged mice. Additionally, we identified 7 enriched TCR sequences that may be Omp specific. We have confirmed the efficacy of adoptive T cell transfer therapy against Kp infections using T cells from immunized mice. Moving forward we will validate our TCR sequences as Kp specific to genetically engineer both primary and cell line T cells for future therapeutic studies.