Biology subjects

Placek, L.

Publications and source records attributed to Placek, L..

8 recordsLinked to original sources

bioRxiv2024

Fast Targeted Metabolomics for Analyzing Metabolic Diversity of Bacterial Indole Derivatives in ME/CFS Gut Microbiome

Disruptions in microbial metabolite interactions due to gut microbiome dysbiosis and metabolomic shifts may contribute to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and other immune-related conditions. The aryl hydrocarbon receptor (AhR), activated upon binding various tryptophan metabolites, modulates host immune responses. This study investigates whether the metabolic diversity--the concentration distribution--of bacterial indole pathway metabolites can differentiate bacterial strains and classify ME/CFS samples. A fast targeted liquid chromatography-parallel reaction monitoring method at a rate of 4 minutes per sample was developed for large-scale analysis. This method revealed significant metabolic differences in indole derivatives among B. uniformis strains cultured from human isolates. Principal component analysis identified two major components (PC1, 68.9%; PC2, 18.7%), accounting for 87.6% of the variance and distinguishing two distinct B. uniformis clusters. The metabolic difference between clusters was particularly evident in the relative contributions of indole-3-acrylate and indole-3-aldehyde. We further measured concentration distributions of indole derivatives in ME/CFS by analyzing fecal samples from 10 patients and 10 healthy controls using the fast targeted metabolomics method. An AdaBoost-LOOCV model achieved moderate classification success with a mean LOOCV accuracy of 0.65 (Control: precision of 0.67, recall of 0.60, F1-score of 0.63; ME/CFS: precision of 0.64, recall of 0.7000, F1-score of 0.67). These results suggest that the metabolic diversity of indole derivatives from tryptophan degradation, facilitated by the fast targeted metabolomics and machine learning, is a potential biomarker for differentiating bacterial strains and classifying ME/CFS samples. Mass spectrometry datasets are accessible at the National Metabolomics Data Repository (ST002308, DOI: 10.21228/M8G13Q; ST003344, DOI: 10.21228/M8RJ9N; ST003346, DOI: 10.21228/M8RJ9N).

biochemistry↗

bioRxiv2024

Engineering programmable CAR-T cells with tunable controls as fail-safe mechanisms during cancer immunotherapy

Chimeric antigen receptor (CAR) T-cell therapies have demonstrated remarkable efficacy in treating various cancers, but significant risks of severe adverse effects remain. In this study, we present a synthetic biology toolbox for engineering CAR-T cells with tunable and controllable features to mitigate these risks. Using this toolbox, we programmed cytotoxic CAR-T cells to be turned on and off using synthetic genes with tetracycline response elements, referred to as iOnCAR and iOffCAR. We achieved temporal regulation of CAR expression using the synthetic Notch receptor system and "AND-gate" programs, which allow for additional control using doxycycline. We also engineered cooperation among T cells through CD4 help to CD8 T cells in targeting cancer cells via synthetic Notch receptors controlled by doxycycline treatment. Additionally, we developed a T cell fratricide system by triggering a genetic "Battle Royale" mechanism that enables CAR-T cells to eliminate each other. In this system, surviving T cells become activated, proliferate, and display high cytotoxicity to target cells. In conclusion, our synthetic biology toolbox provides targeted fail-safe solutions for improving the safety and potency of CAR-T cell therapies by integrating different genetic circuits with a commonly used antibiotic.

immunology↗

bioRxiv2024

Epidermal Growth Factor Receptor Regulates Beclin-1 in Hyperoxia

While delivery of supplemental oxygen is a life-saving therapy, exposure to high levels of oxygen, called hyperoxia, is associated with increased mortality in the intensive care unit (ICU). Hyperoxia leads to oxidant-mediated acute lung injury (ALI) and pulmonary cell death, called hyperoxic acute lung injury (HALI). Elucidation of molecular mechanisms in HALI could identify therapeutic targets in ALI. In the current study, we examined in vivo effects of HALI on Beclin-1 (BCN1), a molecule that regulates autophagy and cell death. Effects of HALI on BCN1 and autophagy markers were examined in wildtype mice. Analysis of BCN1 and autophagy was completed via Western blot, RT-qPCR, and immunohistochemistry. In wildtype mice, HALI led to increased BCN1 in the lung and in the alveolar epithelium. HALI resulted in significant alterations in markers of autophagy in the lung, including reduced microtubule-associated protein 1B-light chain (LC3B)-II/-I ratios, suggesting reduced autophagic flux. HALI caused increased LDH release in human alveolar type-II cells derived from induced pluripotent stem cells (AT2siPSC), as well as reduced LC3B-II/-I ratios. We previously showed that inhibition of the tyrosine kinase receptor epidermal growth factor receptor (EGFR) is protective in HALI. EGFRWa5/+ mice, which have genetically reduced EGFR activity and improved survival in HALI, showed increased total BCN1, reduced phosphorylated-(p-)/total BCN1 ratios, and decreased LC3B-II/-I ratios in the lung in HALI compared with wildtype. Administration of wortmannin, a phosphatidylinositol-3 kinase (PI3K) inhibitor which decreases BCN1-mediated autophagy, led to increased mortality in HALI in wildtype mice. These data support that regulation of BCN1 and autophagy by EGFR is a protective mechanism in HALI, a pathway which warrants further study for its therapeutic potential. KEY MESSAGESHALI is associated with increased mortality in the ICU and causes alveolar epithelial cell death, but the role of BCN1 in HALI is not well defined. This study shows that BCN1, a molecule involved in autophagy and cell death, is regulated by EGFR in HALI in vivo. These results are significant because regulation by BCN1 and autophagy by EGFR is a novel pathway in HALI with therapeutic potential that warrants further study.

cell biology↗

bioRxiv2022

Engineering human Mucosal Associated Invariant T (MAIT) cells with chimeric antigen receptors for cancer immunotherapy

Engineering immune cells with chimeric antigen receptors (CAR) is a promising technology in cancer immunotherapy. Besides classical cytotoxic CD8+ T cells, innate cell types such as NK cells have also been used to generate CAR-T or CAR-NK cells. Here we devised an approach to program a non-classical cytotoxic T cell subset called Mucosal Associated Invariant T (MAIT) cells into effective CAR-T cells against B cell lymphoma and breast cancer cells. Accordingly, we expressed anti-CD19 and anti-Her2 CARs in activated primary human MAIT cells and CD8+ T cells, expanded them in vitro and compared their cytotoxicity against tumor cell targets. We show upon activation through CARs, CAR-MAIT cells exhibit high levels of cytotoxicity towards target cells, comparable to CD8+ CAR-T cells, but interestingly expressed lower levels of IFN-{gamma} than conventional CAR CD8+ T cells. Additionally, in the presence of vitamin B2 metabolite 5-ARU, which is a conserved compound that activates MAIT cells through MHC-I related (MR1) protein, MAIT cells killed MR1-expressing target breast cancer and B cell lymphoma cell lines in a dose dependent manner. Thus, MAIT cells can be genetically edited as CAR-T cells or mobilized and expanded by MR1 ligands as an off-the-shelf novel approach to cell-based cancer immunotherapy strategies while being comparable to conventional methods in effectivity. Key PointsO_LIMAIT cells expressing CARs effectively kill CD19 and Her2 expressing targets C_LIO_LICAR-MAITs display strong cytotoxicity with lower TNF-{gamma} compared to CD8+ CAR-T cells C_LI

immunology↗

bioRxiv2022

Modulation of glucose metabolism by 2-Deoxy-D-Glucose (2DG) promotes IL-17 producing human T cell subsets

Activation and differentiation of T cells are closely linked to their cellular metabolic programs. Glycolysis and mitochondrial metabolism are thought to be critical in modulating T cell function. Here we asked to what extent inhibition of glycolysis, using 2-Deoxy-D-Glucose (2DG), regulate activation, effector function, or differentiation of human T cell subsets. We found that glycolysis is required for T cell receptor (TCR) -mediated activation and proliferation of human naive CD4+ T cells but had less of an impact on memory subsets. CD4+ T cells cultured in the presence of 2DG displayed higher level of IL-17-secreting cells (Th17) from memory or in vitro differentiated naive regulatory T cell (Tregs) subsets. Moreover, the mucosal associated invariant T (MAIT) cell subset survived or expanded better and secreted higher IL-17 in the presence of 2DG. Remarkably, we found that the 2DG effect was reversed by mannose but not by glucose. Collectively, these findings suggest that 2DG could enrich IL-17 secreting human effector T cell subsets and their cellular functions. Our finding provides a framework to manipulate glycolytic pathways in human T cells in infectious diseases such as COVID19 and in enhancing cancer immunotherapy.

immunology↗

bioRxiv2022

Targeting SARS-CoV-2 infection through CAR T cells and bispecific T cell engagers

Despite advances in antibody treatments and vaccines, COVID-19 caused by SARS-CoV-2 infection remains a major health problem resulting in excessive morbidity and mortality and the emergence of new variants has reduced the effectiveness of current vaccines. Here, as a proof-of-concept we engineered primary CD8 T cells to express SARS-CoV-2 Spike protein-specific CARs, using extracellular region of ACE2, and demonstrated their highly specific and potent cytotoxicity towards Spike-expressing target cells. To improve on this concept as a potential therapeutic, we developed a bispecific T cell engager combining ACE2 with an anti-CD3 scFv (ACE2-Bite) to target infected cells and the virus. Similar to CAR-T cell approach, ACE2-Bite endowed cytotoxic cells to selectively kill Spike-expressing targets. Furthermore, ACE2-Bite neutralized the pseudoviruses of SARS-CoV, SARS-CoV-2 wild-type and variants including Delta and Omicron, as a decoy protein. Remarkably, ACE2-Bite molecule showed a higher binding and neutralization affinity to Delta and Omicron variants compared to SARS-CoV-2 wild-type Spike proteins, suggesting the potential of this approach as a variant-proof, therapeutic strategy for future SARS-CoV-2 variants, employing both humoral and cellular arms of the adaptive immune response.

bioengineering↗

bioRxiv2019

Perturbation of effector and regulatory T cell subsets in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disorder of unknown etiology, and diagnosis of the disease is largely based on clinical symptoms. We hypothesized that immunological disruption is the major driver of this disease and analyzed a large cohort of ME/CFS patient or control blood samples for differences in T cell subset frequencies and functions. We found that the ratio of CD4+ to CD8+ T cells and the proportion of CD8+ effector memory T cells were increased, whereas NK cells were reduced in ME/CFS patients younger than 50 years old compared to a healthy control group. Remarkably, major differences were observed in Th1, Th2, Th17 and mucosal-associated invariant T (MAIT) T cell subset functions across all ages of patients compared to healthy subjects. While CCR6+ Th17 cells in ME/CFS secreted less IL-17 compared to controls, their overall frequency was higher. Similarly, MAIT cells from patients secreted lower IFN{gamma}, GranzymeA and IL-17 upon activation. Together, these findings suggest chronic stimulation of these T cell populations in ME/CFS patients. In contrast, the frequency of regulatory T cells (Tregs), which control excessive immune activation, was higher in ME/CFS patients. Finally, using a machine learning algorithm called random forest, we determined that the set of T cell parameters analyzed could identify more than 90% of the subjects in the ME/CFS cohort as patients (93% true positive rate or sensitivity). In conclusion, these multiple and major perturbations or dysfunctions in T cell subsets in ME/CFS patients suggest potential chronic infections or microbiome dysbiosis. These findings also have implications for development of ME/CFS specific immune biomarkers and reveal potential targets for novel therapeutic interventions.

immunology↗

bioRxiv2019

Live cell kinetic analysis of the LMO2/LDB1 leukemogenic protein 1 complex reveals a hierarchy of turnover with implications for complex assembly

Multisubunit protein complexes operate in many cellular functions. The LDB1/LMO2 macromolecular complex has been posited to be critical in hematopoietic stem and progenitor cell specification and in the development of acute leukemia. This complex is comprised of core subunits of LMO2 and LDB1 as well as bHLH and GATA transcription factors. We analyzed the steady state abundance and kinetic stability of LMO2 and its partners via HALO protein tagging in conjunction with variant proteins deficient in binding their respective direct protein partners. We discovered a hierarchy of protein stability, with half lives in descending order: LDB1>SSBP>LMO2>TAL1. Importantly, LDB1 conferred enhanced stability upon each and every subunit component and nucleated the formation of the multisubunit protein complex. Our studies provide significant insights into LDB1/LMO2 macromolecular protein complex assembly and stability, which has implications for understanding its role in blood cell formation and for therapeutically targeting this complex in human leukemias.

biochemistry↗