Biology subjects

Miyamoto, E.

Publications and source records attributed to Miyamoto, E..

2 recordsLinked to original sources

bioRxiv2026

Characterization of central carbon metabolism of Acinetobacter sp. Tol 5 based on 13C-metabolic flux analysis

Acinetobacter sp. strain Tol 5 is an attractive microorganism because of its ability to utilize various aromatic compounds, including toluene. However, because Tol 5 is a non-model microorganism, the utilization of carbon sources in central carbon metabolism remains unclear. In this study, the activity of the central carbon metabolism was characterized using 13C-metabolic flux analysis (13C-MFA). Tol 5 was cultured in synthetic medium using ethanol or acetate as the sole carbon source. In addition, because toluene is degraded into pyruvate and acetyl-CoA via the toluene dioxygenase pathway, this situation was mimicked by culturing with ethanol and lactate as co-substrates. The 13C-MFA confirmed flux through the glyoxylate shunt, which bypasses part of the TCA cycle when either ethanol or acetate was used as the sole carbon source. In ethanol, the flux ratio of isocitrate dehydrogenase at the isocitrate branch point decreased markedly. Unlike acetate, the conversion of ethanol to acetyl-CoA is accompanied by NADH production. Therefore, the observed change in this flux ratio was influenced by the excess NADH generated. Under ethanol-lactate conditions, Tol 5 simultaneously utilized ethanol and lactate. The ethanol consumption rate decreased to less than half of that observed when ethanol was the sole carbon source. Most of the lactate uptake was converted to pyruvate and metabolized via the TCA cycle. The glyoxylate shunt flux was lower than that in ethanol. These metabolic characteristics provide valuable insights into the use of Tol 5 as a next-generation microbial cell factory.

microbiology↗

bioRxiv2021

Ex vivo delivery of regulatory T cells for control of alloimmune priming in the donor lung

Survival after lung transplantation (LTx) is hampered by uncontrolled inflammation and alloimmunity. Regulatory T cells (Tregs) are being studied for post-implantation cell therapy in solid organ transplantation. Whether these systemically administered Tregs can function at the appropriate location and time is an important concern. We hypothesized that in vitro expanded, recipient-derived Tregs can be delivered to donor lungs prior to LTx via ex vivo lung perfusion (EVLP), maintaining their immunomodulatory ability. In a rat model, Wistar Kyoto (WKy) CD4+CD25high Tregs were expanded in vitro prior to EVLP. Expanded Tregs were administered to Fisher 344 (F344) donor lungs during EVLP; left lungs were transplanted into WKy recipients. Treg localization and function post-transplant were assessed. In a proof-of-concept experiment, cryopreserved expanded human CD4+CD25+CD127low Tregs were thawed and injected into discarded human lungs during EVLP. Rat Tregs entered the lung parenchyma and retained suppressive function. Expanded Tregs had no adverse effect on donor lung physiology during EVLP; lung water as measured by wet- to-dry weight ratio was reduced by Treg therapy. The administered cells remained in the graft at 3 days post-transplant where they reduced activation of intragraft effector CD4+ T cells; these effects were diminished by day 7. Human Tregs entered the lung parenchyma during EVLP where they expressed key immunoregulatory molecules (CTLA4+, 4-1BB+, CD39+, and CD15s+). Pre-transplant Treg administration can inhibit alloimmunity within the lung allograft at early time points post- transplant. Our organ-directed approach has potential for clinical translation.

immunology↗