Concentrations of downstream TRP metabolites with product to substrate ratios and frequencies of induced regulatory T cells with its ratio to Th17 cells in PAH (baseline and after 6 months) and control group
| PAH group, n=26 | Control group, n=30 | p Value | PAH after 6 months, n=24 | p Value* | |
|---|---|---|---|---|---|
| TRP, µmol/L | 52.9 (46.3–57.5) | 40.3 (35.2–46.3) | 0.00003 | 57.6 (47.1–64.2) | <0.0001 |
| KYN, µmol/L | 2.8 (2.4–3.4) | 1.9 (1.5–2.3) | 0.000007 | 3 (2.2–3.7) | <0.0001 |
| KYN/TRP | 0.051 (0.044–0.064) | 0.043 (0.039–0.055) | 0.03 | 0.049 (0.043–0.064) | 0.03 |
| KYNA, nmol/L | 42 (27.5–67.4) | 40 (28.5–52.4) | 0.5 | 43 (30.7–63.6) | 0.3 |
| AA, nmol/L | 37.4 (28.4–57.3) | 38.9 (31.9–48.4) | 0.9 | 37.1 (23.5–46.4) | 0.3 |
| 3HKYN, nmol/L | 22.9 (16.9–33) | 20.6 (16–24.9) | 0.2 | 23.2 (16.6–32.7) | 0.2 |
| KYNA/KYN | 15.4 (10.7–24.1) | 22.3 (15.8–28.6) | 0.01 | 15 (11.6–23.5) | 0.02 |
| 3HKYN/KYN | 0.008 (0.007–0.01) | 0.01 (0.009–0.013) | 0.002 | 0.008 (0.007–0.009) | 0.001 |
| AA/KYN | 13.6 (9.4–20.9) | 21.2 (17.4–27) | 0.007 | 11.5 (8.1–18.4) | 0.0001 |
| iTreg, % | 10.5 (8.8–13.9) | 6.8 (5.2–9.5) | 0.002 | – | |
| iTreg/Th17 | 1.73 (1.2–2.8) | 0.93 (0.61–1.27) | 0.003 | – |
Data are presented as median (IQR).
iTreg cells (induced regulatory T cells), delineated by CD4+CD25−CD127− phenotype.
Th17 cells (identified by CD4+CD161+CD196+ phenotype).
*Control group vs measurements after 6 months in PAH group.
3HKYN, 3-hydroxykinurenine; AA, anthranilic acid; KYN, kynurenine; KYNA, kynurenic acid; PAH, pulmonary arterial hypertension; TRP, tryptophan.