Cu and Zn isotope ratio variations in plasma for survival prediction in hematological malignancy cases

We have examined potential changes in the isotopic compositions of Fe, Cu and Zn (using multi-collector inductively coupled plasma-mass spectrometry) and the corresponding concentrations (using inductively coupled plasma-atomic emission spectrometry) in plasma from hematological malignancy (HM) patients and assessed their prognostic capability. Together with clinical laboratory test values, data were examined in view of a 5-years survival prediction. Plasma Cu and Zn isotope ratios and their concentrations were significantly different in HM patients compared to matched controls (P < 0.05). Both δ⁶⁵Cu and δ⁶⁶Zn values showed significant mortality hazard ratios (HRs) in HM. The group of patients with decreased δ⁶⁵Cu and increased δ⁶⁶Zn values showed significantly poorer survival from the early phase (HR 3.9; P = 0.001), forming a unique cohort not identified based on laboratory test values. Well-known prognostic factors for HM, such as the creatinine level, and anemia-related values were highly correlated with the δ⁶⁶Zn value (P < 0.05). Time-dependent ROC curves based on the δ⁶⁵Cu or δ⁶⁶Zn value were similar to that based on the creatinine concentration (a well-known prognostic factor in HM), indicating that δ⁶⁵Cu or δ⁶⁶Zn values are useful for prognosis of HM. Variations in stable isotope ratios of essential mineral elements have thus been shown to reflect alterations in their homeostasis due to physiological changes in malignancies with higher sensitivity than concentrations do.

Body distribution of stable copper isotopes during the progression of cholestatic liver disease induced by common bile duct ligation in mice

Patients with chronic liver disease from different aetiologies show a light serum Cu isotopic composition compared to the reference population, with the enrichment in the 63Cu isotope correlating with the severity of the disease. However, the mechanisms underlying Cu isotope fractionation at the onset and during progression of the disease are still unclear. In this work, a common bile duct ligation (CBDL) murine model was used to investigate the effect of cholestasis-induced liver disease on the Cu isotopic composition. Wild type male and female mice underwent surgical ligation of the common bile duct and were sacrificed 2, 4 and 6 weeks, and 4, 6 and 8 weeks after the surgical intervention, respectively. The age- and gender-matched control mice underwent sham surgery. Disease progression was evaluated using serum bilirubin levels, hepatic pro-inflammatory chemokine levels and Metavir fibrosis score. CBDL-operated mice show an overall body enrichment in the light isotope 63Cu. The Cu isotopic composition of organs, bone and serum becomes gradually lighter compared to the sham-operated mice with increasing severity of the disease. The light Cu isotopic composition of the CBDL-operated mice might result from an altered Cu intake and/or excretion. As the intestinal uptake of dietary Cu is largely mediated by transporters of Cu(i), mRNA and protein expression levels of two major metal transporters (CTR1 and DMT1) and Cu reductases (STEAP proteins and duodenal cytochrome B) were examined in the duodenal tissues as potential factors inducing Cu isotope fractionation. However, no significant differences in protein expression levels were observed between the CBDL- and sham-operated mice.

Lighter serum copper isotopic composition in patients with early non-alcoholic fatty liver disease

Objective

The occurrence of non-alcoholic fatty liver disease (NAFLD) is globally increasing. To challenge the current incidence of NAFLD, non-invasive markers that could identify patients at risk or monitor disease progression are an important need. Copper intake and organ copper concentrations have earlier been linked to NAFLD progression, but serum copper does not adequately represent the disease state. Cu atoms occur under the form of two stable isotopes, ⁶³Cu and ⁶⁵Cu, and the ratio of both (expressed as δ⁶⁵Cu, in  ‰) in blood serum has been shown to be altered in chronic liver disease. To assess whether the Cu isotope ratio might predict disease occurrence and progression of NAFLD, the serum Cu isotopic composition of patients with different stages of NAFLD was determined.

Results

Our results showed that serum δ⁶⁵Cu values were lower in NAFLD patients, already at the level of simple steatosis, and remained stable during further disease progression. ROC analysis shows an almost perfect diagnostic ability of serum δ⁶⁵Cu values for NAFLD, but no discrimination between different severity degrees could be made. Therefore, the serum Cu isotopic composition might show potential for early diagnosis of NAFLD patients.

High-precision isotopic analysis of serum and whole blood Cu, Fe and Zn to assess possible homeostasis alterations due to bariatric surgery

Bariatric surgery is an effective procedure to achieve weight loss in obese patients. However, homeostasis of essential metals may be disrupted as the main absorption site is bypassed. In this study, we determined Cu, Fe and Zn isotopic compositions in paired serum and whole blood samples of patients who underwent Roux-en-Y gastric bypass (RYGB) surgery for evaluation of longitudinal changes and their potential relation to mineral element concentrations and relevant clinical parameters used for monitoring the patient's condition. Samples from eight patients were collected pre-surgery and at 3, 6 and 12 months post-surgery. Multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) was used for high-precision isotope ratio measurements. Alterations in metal homeostasis related to bariatric surgery were reflected in the serum and whole blood Cu, Fe and Zn isotopic compositions. The serum and whole blood Cu became isotopically lighter (lower δ⁶⁵Cu values) after bariatric surgery, reaching statistical significance at 6 months post-surgery (p < 0.05). The difference between the serum and the whole blood Zn isotopic composition increased after surgery, reaching significance from 6 months post-surgery onwards (p < 0.05). Those changes in Cu, Fe and Zn isotopic compositions were not accompanied by similar changes in their respective concentrations, making isotopic analysis more sensitive to physiological changes than elemental content. Furthermore, the Zn isotopic composition correlates with blood glycaemic and lipid parameters, while the Fe isotopic composition correlates with glycaemic parameters. Graphical Abstract.