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Updated: Jun 20, 2026
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Murine Intrapulmonary Tracheal Transplantation: A Model for Investigating Obliterative Airway Disease After Lung Transplantation
Published on: November 10, 2023
Indoleamine 2,3-dioxygenase in lung allograft tolerance
Federica Meloni1, Serena Giuliano, Nadia Solari
1Department of Haematological, Pneumological and Cardiovascular Sciences, Section of Pneumology, University of Pavia and IRCCS San Matteo Foundation, Via Taramelli 5, Pavia, Italy. f.meloni@smatteo.pv.it
Summary
Plasma indoleamine 2,3-dioxygenase (IDO) activity in lung transplant recipients does not indicate graft acceptance. Instead, higher IDO activity correlates with chronic inflammation, not graft tolerance.
Area of Science:
- Immunology
- Transplantation Science
- Biochemistry
Background:
- Indoleamine 2,3-dioxygenase (IDO) degrades tryptophan, potentially suppressing T-cell activity.
- Previous studies suggest IDO's role in graft acceptance, but human data are limited.
- This study investigates IDO activity in relation to graft acceptance in lung transplant recipients.
Purpose of the Study:
- To determine if plasma IDO activity reflects graft acceptance in lung transplant recipients (LTRs).
- To explore the relationship between IDO activity and clinical outcomes in LTRs.
Main Methods:
- Measured plasma kynurenine/tryptophan (Kyn/Try) ratio, an indicator of IDO activity, in 90 LTRs and 24 healthy controls using HPLC.
- Classified LTRs into stable recipients and those with bronchiolitis obliterans syndrome (BOS).
Main Results:
- Stable LTRs showed similar Kyn/Try ratios to healthy controls.
- Patients with BOS exhibited increased plasma Kyn/Try ratios compared to stable LTRs and controls.
- BOS patients had reduced regulatory T-cells and dendritic cells, but similar IDO expression in PBMCs.
- BOS was associated with chronic inflammation markers (IL-8, TNF-alpha) and T-cell activation.
Conclusions:
- Plasma IDO activity in lung transplantation does not correlate with graft acceptance.
- IDO activity appears to be linked to the severity of chronic inflammation post-lung transplant.
