Table 1.
General characteristics of scleroderma patients (SSc) and healthy controls (HC): age, sex, plasma content of tryptophan (TRP), kynurenine (KYN), and kynurenic acid (KYNA) and enzyme activity indicators.
| SSc Patients (n = 48) | HC (n = 53) | t- or χ2-Test | p < | |
|---|---|---|---|---|
| Age | 51.17 (13.15) | 46.77 (13.36) | 1.66 | 0.100 |
| Sex (m/f) | 19/29 | 27/26 | 1.31 | 0.252 |
| Plasma content | ||||
| [TRP] | 29,524.88 (7282.10) | 38,284.19 (7240.42) | −6.06 | <0.001 |
| [KYN] | 4452.07 (1673.82) | 3453.23 (1359.69) | 3.30 | 0.001 |
| [KYNA] | 47.87 (14.05) | 49.00 (15.93) | −0.38 | 0.706 |
| Enzyme activity * | ||||
| IDO and TDO | 0.16 (0.06) | 0.09 (0.03) | 7.28 | <0.001 |
| KATs | 0.01 (0.004) | 0.02 (0.006) | −3.64 | <0.001 |
| KYNA/TRP | 0.002 (0.0004) | 0.0013 (0.0005) | 3.93 | <0.001 |
Data are presented as a mean ± SD (in brackets) except for sex; n—number of subjects; * enzyme activity was calculated as a metabolite to precursor ratio, IDO and TDO = [KYN]/[TRP]; KATs = [KYNA/KYN]. Differences between SSc patients and HC were calculated using independent samples t-test, with the exception of sex differences (χ2-test). Values of all metabolites are in nM (nanomoles). Abbreviations: IDO = indoleamine-2,3-dioxygenase; KATs = kynurenine aminotransferases; KYN = kynurenine; KYNA = kynurenic acid; TDO = tryptophan 2,3-dioxygenase; TRP = tryptophan.