Salivary levels of interleukin-6 and tumor necrosis factor-α in patients undergoing hemodialysis

Characterization of the internal working-life exposome using minimally and non-invasive sampling methods - a narrative review

During recent years, we are moving away from the 'one exposure, one disease'-approach in occupational settings and towards a more comprehensive approach, taking into account the totality of exposures during a life course by using an exposome approach. Taking an exposome approach however is accompanied by many challenges, one of which, for example, relates to the collection of biological samples. Methods used for sample collection in occupational exposome studies should ideally be minimally invasive, while at the same time sensitive, and enable meaningful repeated sampling in a large population and over a longer time period. This might be hampered in specific situations e.g., people working in remote areas, during pandemics or with flexible work hours. In these situations, using self-sampling techniques might offer a solution. Therefore, our aim was to identify existing self-sampling techniques and to evaluate the applicability of these techniques in an occupational exposome context by conducting a literature review. We here present an overview of current self-sampling methodologies used to characterize the internal exposome. In addition, the use of different biological matrices was evaluated and subdivided based on their level of invasiveness and applicability in an occupational exposome context. In conclusion, this review and the overview of self-sampling techniques presented herein can serve as a guide in the design of future (occupational) exposome studies while circumventing sample collection challenges associated with exposome studies.

Targeted biomarkers of progression in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is an increasingly significant health issue worldwide. Early stages of CKD can be asymptomatic and disease trajectory difficult to predict. Not everyone with CKD progresses to kidney failure, where kidney replacement therapy is the only life-sustaining therapy. Predicting which patients will progress to kidney failure would allow better use of targeted treatments and more effective allocation of health resources. Current diagnostic tests to identify patients with progressive disease perform poorly but there is a suite of new and emerging predictive biomarkers with great clinical promise.

METHODS

This narrative review describes new and emerging biomarkers of pathophysiologic processes of CKD development and progression, accessible in blood or urine liquid biopsies. Biomarkers were selected based on their reported pathobiological functions in kidney injury, inflammation, oxidative stress, repair and fibrosis. Biomarker function and evidence of involvement in CKD development and progression are reported.

CONCLUSION

Many biomarkers reviewed here have received little attention to date, perhaps because of conflicting conclusions of their utility in CKD. The functional roles of the selected biomarkers in the underlying pathobiology of progression of CKD are a powerful rationale for advancing and validating these molecules as prognosticators and predictors of CKD trajectory.

Aptamers Targeting Cardiac Biomarkers as an Analytical Tool for the Diagnostics of Cardiovascular Diseases: A Review

The detection of cardiac biomarkers is used for diagnostics, prognostics, and the risk assessment of cardiovascular diseases. The analysis of cardiac biomarkers is routinely performed with high-sensitivity immunological assays. Aptamers offer an attractive alternative to antibodies for analytical applications but, to date, are not widely practically implemented in diagnostics and medicinal research. This review summarizes the information on the most common cardiac biomarkers and the current state of aptamer research regarding these biomarkers. Aptamers as an analytical tool are well established for troponin I, troponin T, myoglobin, and C-reactive protein. For the rest of the considered cardiac biomarkers, the isolation of novel aptamers or more detailed characterization of the known aptamers are required. More attention should be addressed to the development of dual-aptamer sandwich detection assays and to the studies of aptamer sensing in alternative biological fluids. The universalization of aptamer-based biomarker detection platforms and the integration of aptamer-based sensing to clinical studies are demanded for the practical implementation of aptamers to routine diagnostics. Nevertheless, the wide usage of aptamers for the diagnostics of cardiovascular diseases is promising for the future, with respect to both point-of-care and laboratory testing.

Evaluation of TNF-α and IL-6 in saliva among diabetic retinopathy patients in East Coast Malaysia

OBJECTIVE

To compare tumor necrosis factor-alpha (TNF) and interleukin (IL)-6 levels in saliva between different stages of diabetic retinopathy (DR).

METHODS

This comparative cross-sectional study was conducted between January 2018 and November 2020. This study included diabetes mellitus (DM) patients with no DR, non-proliferative DR (NPDR), and proliferative DR (PDR). None of the patients with DM were included in the control group. Unstimulated saliva samples were then collected. TNF-α and IL-6 levels were measured.

RESULTS

Altogether, 120 patients were included in the study (DM without DR, 33 patients; DM with NPDR, 30 patients; DM with PDR, 32 patients; non-DM, 25 patients). The mean IL-6 level in saliva was significantly higher in the DM group (0.033±0.005 pg/ml) than in the non-DM group (0.027±0.001 pg/ml) (p<0.001 after adjusting for covariates). There was no significant difference in mean salivary TNF-α between patients with DM and those without DM after adjusting for covariates. The mean IL-6 in saliva was significantly higher in the NPDR (0.036±0.003 pg/ml) and PDR (0.093±0.023 pg/ml) groups than in the no DR group (0.027±0.001 pg/ml) (p<0.001 and p<0.001, respectively). Mean TNF-α in saliva was significantly higher in the NPDR (0.086±0.022 pg/ml) and PDR (0.093±0.023 pg/ml) groups than in the no DR group (0.049±0.011 pg/ml) (p=0.015 and p=0.003, respectively).

CONCLUSION

There is an association between inflammatory biomarkers in saliva (IL-6 and TNF-α) and severity of DR among patients with DM, suggesting that these salivary biomarkers are potential biomarkers for screening, monitoring, and predicting the progression of DR.

Crosstalk of fibroblast growth factor 23 and anemia-related factors during the development and progression of CKD (Review)

Fibroblast growth factor 23 (FGF23) plays an important role in the development of chronic kidney disease-mineral bone disorder (CKD-MBD). Abnormally elevated levels of 1,25-dihydroxyvitamin D cause osteocytes to secrete FGF23, which subsequently induces phosphaturia. Recent studies have reported that iron deficiency, erythropoietin (EPO) and hypoxia regulate the pathways responsible for FGF23 production. However, the molecular mechanisms underlying the interactions between FGF23 and anemia-related factors are not yet fully understood. The present review discusses the associations between FGF23, iron, EPO and hypoxia-inducible factors (HIFs), and their impact on FGF23 bioactivity, focusing on recent studies. Collectively, these findings propose interactions between FGF23 gene expression and anemia-related factors, including iron deficiency, EPO and HIFs. Taken together, these results suggest that FGF23 bioactivity is closely associated with the occurrence of CKD-related anemia and CKD-MBD.

Biomarkers and the role of mast cells as facilitators of inflammation and fibrosis in chronic kidney disease

Chronic kidney disease (CKD) is a clinical syndrome with many adverse sequelae and is currently a major global health and economic burden. Regardless of aetiology, inflammation and fibrosis are common manifestations of CKD. Unfortunately, the underlying pathophysiological mechanisms are poorly understood, and robust prognostic and early diagnostic biomarkers of CKD are lacking. One immune cell population that has received little attention in the context of CKD is mast cells (MCs). This mini review will examine the role of MCs as facilitators of kidney inflammation and fibrosis, propose a mechanistic structure for MCs in CKD, and give consideration to biomarkers specific for MC activation that can be deployed clinically. MCs are derived from haematopoietic stem cells. They are characterised by electron-dense granules in the cytoplasm, filled with preformed mediators. MCs can synthesise a range of bio-active compounds. Activation of MCs modulates an innate immune and adaptive effector response. Increased MC counts have been observed in animal models of kidney disease and a range of kidney diseases in humans where MC presence has been linked to biomarkers of kidney function and tissue damage. To further implicate MCs in CKD, several chemokines, cytokines and proteases released by MCs have been observed in their own right in various kidney diseases and linked to progressive CKD. One compound released by MCs that is of particular interest is the MC-specific protease tryptase. This protease is capable of activating the G-protein coupled receptor (GPCR) protease activated receptor-2 (PAR-2). PAR-2 is widely expressed throughout the kidney and highly expressed in the tubular epithelial cells where its activation induces robust inflammatory and fibrotic responses. Novel prognostic and diagnostic biomarkers of CKD are needed. MC-specific proteases [tryptase, chymase and carboxypeptidase A3 (CPA3)] are easily detectable in the blood but questionably in the urine. This review aims to promote these as prognostic and diagnostic biomarkers in the context of CKD.