Systemic inflammation modulates the ability of serum ferritin to predict all-cause and cardiovascular mortality in peritoneal dialysis patients

Peritoneal Dialysis Aggravates and Accelerates Atherosclerosis in Uremic ApoE-/- Mice

BACKGROUND

Atherosclerosis is highly prevalent in people with chronic kidney disease (CKD), including those receiving peritoneal dialysis (PD). Although it is lifesaving, PD induces profound systemic inflammation, which may aggravate atherosclerosis. Therefore, the hypothesis is that this PD-induced inflammation aggravates atherosclerosis via immune cell activation.

METHODS AND RESULTS

ApoE-/- mice were subjected to a 5/6 nephrectomy to induce CKD. Three weeks later, mice were fed a high-cholesterol diet. Half of the nephrectomized mice then received daily peritoneal infusions of 3.86% Physioneal for 67 further days (CKD+PD) until the end of the experiment, and were compared with mice without CKD. Sham operated and PD-only mice were additional controls. CKD+PD mice displayed more severe atherosclerotic disease than control mice. Plaque area increased, and plaques were more advanced with a vulnerable phenotype typified by decreased collagen content and decreased fibrous cap thickness. Increased CD3+ T-cell numbers were present in plaques and perivascular adipose tissue of CKD and CKD+PD mice. Plaques of CKD+PD mice contained more iNOS+ immune cells. Spleens of CKD+PD mice showed more CD4+ central memory, terminally differentiated type 1 T-helper (Th1), Th17, and CX3C motif chemokine receptor 1+ (CX3CR1) CD4+ T-cells with less regulatory and effector T-cells.

CONCLUSIONS

PD-fluid exposure in uremic mice potentiates systemic and vascular T-cell-driven inflammation and aggravates atherosclerosis. PD polarized CD4+ T-cells toward an inflammatory Th1/Th17 phenotype, and increased CX3CR1+ CD4+ T-cells, which are associated with vascular homing in CKD-associated atherosclerosis. Targeting CD4+ T-cell activation and CX3CR1+ polarization has the potential to attenuate atherosclerosis in PD patients.

New Perspectives on Circulating Ferritin: Its Role in Health and Disease

The diagnosis of iron disturbances usually includes the evaluation of serum parameters. Serum iron is assumed to be entirely bound to transferrin, and transferrin saturation-the ratio between the serum iron concentration and serum transferrin-usually reflects iron availability. Additionally, serum ferritin is commonly used as a surrogate of tissue iron levels. Low serum ferritin values are interpreted as a sign of iron deficiency, and high values are the main indicator of pathological iron overload. However, in situations of inflammation, serum ferritin levels may be very high, independently of tissue iron levels. This presents a particularly puzzling challenge for the clinician evaluating the overall iron status of the patient in the presence of an inflammatory condition. The increase in serum ferritin during inflammation is one of the enigmas regarding iron metabolism. Neither the origin, the mechanism of release, nor the effects of serum ferritin are known. The use of serum ferritin as a biomarker of disease has been rising, and it has become increasingly diverse, but whether or not it contributes to controlling the disease or host pathology, and how it would do it, are important, open questions. These will be discussed here, where we spotlight circulating ferritin and revise the recent clinical and preclinical data regarding its role in health and disease.

Associations between liver function parameters and poor clinical outcomes in peritoneal dialysis patients

Patients with end-stage renal disease (ESRD) have significantly lower survival rates compared with the general population of the same age. Peritoneal dialysis (PD) is an effective treatment for patients with ESRD, but the clinical outcome of PD patients is still not promising. The survival of PD patients is associated with various clinical factors, and exploring some valid risk predictors may be beneficial for this population. In this review, by integrating the latest research, we summarized the association of some common and novel liver function parameters (ALT, AST, ALP, GGT, serum bilirubin, pre-albumin, albumin, albumin-globulin ratio [AGR], serum ferritin, and hyaluronic acid) with clinical outcomes in PD patients. It may contribute to a better understanding of potential risk factors and help to develop strategies to prevent the disease progression.

Prediction of Mortality in Patients on Peritoneal Dialysis Based on the Fibrinogen Mannosylation

As we already reported, fibrinogen fucosylation emerged as a prognostic marker of peritoneal membrane function in end-stage renal disease (ESRD) patients on peritoneal dialysis. After a follow-up period of 18 months, we estimated the ability of employed lectins, as well as other biochemical parameters, to serve as mortality predictors in these patients. Following a univariate Cox regression analysis, ferritin, urea clearance, residual diuresis, hyperglycemia, and an increase in the signal intensity obtained with Galanthus nivalis lectin (GNL) emerged as potential mortality predictors, but additional multivariate Cox regression analysis pointed only to glucose concentration and GNL as mortality predictors. Higher signal intensity obtained with GNL in patients that died suggested the importance of paucimannosidic/highly mannosidic N-glycan structures on fibrinogen as factors that are related to unwanted cardiovascular events and all-cause mortality and can possibly be seen as a prediction tool. Altered glycan structures composed of mannose residues are expected to affect the reactivity of mannosylated glycoproteins with mannose-binding lectin and possibly the entire cascade of events linked to this lectin. Since patients with ESRD are prone to cardiovascular complications and the formation of atherosclerotic plaques, one can hypothesize that fibrinogen with increasingly exposed mannose residues may contribute to the unwanted events.

Associations of Air Pollution and Serum Biomarker Abnormalities in Individuals with Hemodialysis-Dependent Kidney Failure

BACKGROUND

Ambient particles with a median aerodynamic diameter of <2.5 µm (PM2.5) is a ubiquitous air pollutant with established adverse health consequences. While postulated to promote a systemic inflammatory response, limited studies have demonstrated changes in serum biomarkers related to PM2.5 exposure. We aim to examine associations between short-term PM2.5 exposure and commonly measured biomarkers known to be affected by inflammation among patients receiving maintenance in-center hemodialysis.

METHODS

We conducted a retrospective open cohort study from January 1, 2008, to December 31, 2014. Adult hemodialysis patients were identified from the United States Renal Data System and linked at the patient level to laboratory data from a large dialysis organization. Daily ambient PM2.5 was estimated on a 1-km grid and assigned to cohort patients based on the ZIP codes of dialysis clinics. Serum albumin, serum ferritin, transferrin saturation (TSAT), and serum hemoglobin were ascertained from the dialysis provider organization database. Mixed-effect models were used to assess the changes in biomarker levels associated with PM2.5 exposure.

RESULTS

The final cohort included 173,697 hemodialysis patients. Overall, the daily ZIP-level ambient PM2.5 averages were 8.4-8.5 µg/m3. A 10-µg/m3 increase in same-day ambient PM2.5 exposure was associated with higher relative risks of lower albumin (relative risk [RR], 1.01; 95% confidence interval [95% CI], 1.01 to 1.02) and lower hemoglobin (RR, 1.02; 95% CI, 1.01 to 1.03). Associations of same-day ambient PM2.5 exposure and higher ferritin and lower TSAT did not reach statistical significance.

CONCLUSIONS

Short-term PM2.5 exposure was associated with lower serum hemoglobin and albumin among patients receiving in-center hemodialysis. These findings lend support to the role of inflammation in PM2.5 exposure-outcome associations.

Abnormal iron status is associated with an increased risk of mortality in patients on peritoneal dialysis

BACKGROUND AND AIMS

Iron deficiency is prevalent, but there is limited data about the relationship between iron status and poor outcomes in chronic kidney disease patients undergoing peritoneal dialysis (PD). We aimed to investigate the association between iron status and mortality in PD patients.

METHODS AND RESULTS

This retrospective study was conducted on incident PD patients from January 2006 to December 2016 and followed up until December 2018. Patients were categorized into four groups according to baseline serum transferrin saturation (percent) and ferritin levels (ng/ml): reference (20-30%, 100-500 ng/ml), absolute iron deficiency (<20%, <100 ng/ml), function iron deficiency (FID) (<20%, >100 ng/ml), and high iron (>30%, >500 ng/ml). Among the 1173 patients, 77.5% had iron deficiency. During a median follow-up period of 43.7 months, compared with the reference group, the FID group was associated with increased risk for all-cause [adjusted hazard ratio (aHR) 1.87, 95% confidence interval (95% CI) 1.05-3.31, P = 0.032], but not cardiovascular (CV) mortality. Additionally, the high iron group had a more than four-fold increased risk of both all-cause and CV mortality [aHR 4.32 (95% CI 1.90-9.81), P < 0.001; aHR 4.41 (95% CI 1.47-13.27), P = 0.008; respectively].

CONCLUSION

FID and high iron predict worse prognosis of patients on PD.