Background/Objectives: The mitochondrial unfolded protein response (UPRmt) is one of the mitochondrial quality control mechanisms that is responsible for reparation and removal of damaged proteins in mitochondria. Methods: Here we investigated the role of the UPRmt in the myocardium of humans with and without heart failure and in the cell culture model. Results: The analysis of myocardial samples by ELISA from patients with ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM), as well as healthy donors, revealed a significantly reduced expression of the UPRmt proteins HSP10, CLPP, LONP1, OMA1, and SPG7 in patients with DCM and ICM. Furthermore, patients with DCM and ICM exhibited elevated levels of myocardial reactive oxygen species (ROS, tested by 4-hydroxynonenal) compared to controls, and a positive correlation between ROS production and mt-HSP70, OMA1, and SPG7 protein expression. The correlation analysis indicated a negative correlation between cardiomyocyte hypertrophy and the expression of several UPRmt genes. The inhibition of four tested UPRmt effector proteins exacerbated the injury of cultured cells under oxidative stress. The patients with ICM, DCM, or both, who showed lower myocardial expression of HSP10, HSP60, HTRA2, OMA1, SPG7, and YME1L, underwent heart transplantation or implantation of a left ventricular assist device earlier in life compared to those with the higher protein expression. Conclusions: In conclusion, our findings indicate that the reduced expression of several UPRmt effector proteins is associated with accelerated heart failure in patients, which, together with other results, indicates that impaired UPRmt may contribute to the pathogenesis of heart failure in humans.

This study was designed to examine the association between myocardial concentrations of the trace elements Cu, Fe, Mn, Mo, and Zn and the expression of mitochondrial unfolded protein response (UPRmt) elements and the age of patients who received heart transplantation or a left-ventricular assist device (ageHTx/LVAD). Inductively coupled plasma mass spectrometry was used to determine the concentration of Cu, Fe, Mn, Mo, and Zn in the myocardium of control subjects and patients undergoing heart transplantation or left-ventricular assist device (LVAD) implantation. We used ELISA to quantify the expression of UPRmt proteins and 4-Hydroxynonenal (4-HNE), which served as a marker of oxidative-stress-induced lipid peroxidation. Concentrations of Cu, Mn, Mo, and Zn were similar in the control and heart failure (HF) myocardium, while Fe showed a significant decrease in the HF group compared to the control. A higher cumulative concentration of Fe and Zn in the myocardium was associated with reduced age_HTx/LVAD, which was not observed for other combinations of trace elements or their individual effects. The trace elements Cu, Mn, and Zn showed positive correlations with several UPRmt proteins, while Fe had a negative correlation with UPRmt effector protease YME1L. None of the trace elements correlated with 4-HNE in the myocardium. The concentrations of the trace elements Mn and Zn were significantly higher in the myocardium of patients with dilated cardiomyopathy than in patients with ischemic cardiomyopathy. A higher cumulative concentration of Fe and Zn in the myocardium was associated with a younger age at which patients received heart transplantation or LVAD, potentially suggesting an acceleration of HF. A positive correlation between myocardial Cu, Mn, and Zn and the expression of UPRmt proteins and a negative correlation between myocardial Fe and YME1L expression suggest that these trace elements exerted their actions on the human heart by interacting with the UPRmt. An altered generation of oxidative stress was not an underlying mechanism of the observed changes.

Cancer cachexia is a syndrome characterized by weight and muscle loss and functional impairment, strongly influencing survival in cancer patients. In this study, we aimed to establish the role of saliva cytokine measurement in cancer cachexia investigation and define two potential independent salivary biomarkers of the condition. Methods: serum and saliva specimens were obtained from 78 patients. Forty-six patients were non-cachectic, and 32 patients were cachectic (per SCRINIO group criteria), all with metastatic solid tumors. Commercial ELISA kits were used to determine the salivary and serum concentrations of interleukin 13 (IL-13) and transforming growth factor beta (TGF-β) in two patient groups and healthy controls. Laboratory values were obtained from the hospital information system, and weight and height were measured at the time of sampling. Results: A statistically significant difference was observed between the groups in saliva IL-13 concentrations but no difference in serum concentrations. Statistically significant differences were also observed between the groups in saliva and serum concentrations of TGF-β. Logistic regression analysis has identified salivary IL-13 and TGF-β as independent factors for cancer cachexia. Conclusions: We demonstrated saliva as a valuable specimen for cachexia investigation and established IL-13 and TGF-β as potential cancer cachexia biomarkers. Further research is needed to evaluate these findings.