Statin therapy in peritoneal dialysis patients: effects beyond lipid lowering

Dissecting the mechanisms of left ventricular diastolic dysfunction and inflammation in peritoneal dialysis patients

OBJECTIVE

Patients with symptoms of heart failure and preserved left ventricular (LV) systolic function are commonly encountered in clinical practice especially in peritoneal dialysis (PD) patients. We hypothesized that adiposity might influence LV diastolic function through systemic inflammation in this specific group.

METHODS

We designed a cross-sectional study in 173 prevalent PD patients. LV diastolic dysfunction was diagnosed by echocardiography. PD patient without LV diastolic dysfunction served as the control group. Serum inflammatory biomarkers were examined including tissue necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). The location and amount of adipose tissue were assessed by computerized tomography (CT) at the level of the fourth lumbar vertebra.

RESULTS

Subjects with LV diastolic dysfunction had higher levels of the pro-inflammation cytokines and more visceral and peritoneal fat (all P<0.001) than control subjects. A significant correlation was found between visceral adipose tissue and pro-inflammatory cytokines (r = 0.70; P<0.001). Multivariable regression analysis found that the relationship between visceral adipose tissue and LV diastolic dysfunction became insignificant when either TNF-α or IL-6 were introduced into the model, although TNF-α and IL-6 were both significantly associated with LV diastolic dysfunction even after adjusting for visceral fat (OR = 1.51; 95% CI = 1.09-2.02; P = 0.033 and OR = 1.62; 95% CI = 1.09-1.82; P = 0.031, respectively).

CONCLUSIONS

Larger amounts of adipose tissue were associated with higher serum pro-inflammatory levels in PD patients, which might be related to the development of LV diastolic dysfunction. Modulating inflammatory reactions in PD patients can be a useful therapeutic approach for managing LV diastolic dysfunction.

Differential association of proinflammatory cytokines with left ventricular diastolic dysfunction in subjects with and without continuous ambulatory peritoneal dialysis

BACKGROUND AND AIMS

The association between inflammation and left ventricular (LV) diastolic dysfunction in continuous ambulatory peritoneal dialysis (CAPD) and non-CAPD patients is not established. The objective of this study was to test the above association and whether inflammation interacts with CAPD to increase LV diastolic dysfunction risks.

METHODS AND RESULTS

120 subjects with normal creatinine levels and 101 CAPD patients were recruited. Echocardiographic parameters were assessed in all patients. The participants were classified as having LV diastolic dysfunction by echocardiographic findings including mitral inflow E/A ratio < 1, deceleration time > 220 cm/s, or decreased peak annular early diastolic velocity in tissue Doppler imaging. Blood was sampled at the baseline for measurement of inflammation markers, including tissue necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Subjects with LV diastolic dysfunction had higher proinflammation cytokines levels in both groups. Inflamed markers correlated significantly with echocardiography parameters for LV diastolic dysfunction in patients receiving CAPD. In a multivariate regression analysis adjusting for all the factors associated with LV diastolic dysfunction, inflammation is still significantly associated with left ventricular diastolic dysfunction (TNF-alpha, OR: 2.6, 95% CI: 2.0-3.35, p < 0.001; IL-6, OR: 1.26, 95% CI: 1.25-1.26, p = 0.01). In addition, the interaction of CAPD and inflammation significantly contributed to the development of LV diastolic dysfunction (CAPD∗ TNF-α: OR: 1.45, 95% CI: 1.13-1.79, P = 0.004).

CONCLUSION

We found inflammation plays a vital role for LV diastolic dysfunction especially in CAPD patients. A synergistic effect between CAPD and inflammation, especially TNF-α, would further aggravate LV diastolic dysfunction.

Atorvastatin Reduces High Glucose Toxicity in Rat Peritoneal Mesothelial Cells

Objective

Continuous exposure of the peritoneal membrane to high glucose dialysis solutions can produce functional alterations in this membrane. We studied the toxic effects of high glucose (50 mmol/L and 83 mmol/L) and its reversal by atorvastatin (0.5 – 5 μmol/L) on cultures of rat peritoneal mesothelial cells (PMCs).

Methods

Rat PMCs were harvested from the peritonea of male Sprague–Dawley rats and grown in M199 medium supplemented with 10% fetal bovine serum. The effects of high glucose (50 mmol/L and 83 mmol/L) on levels of reactive oxygen species (ROS), on caspase 3 activity, and on phospho-p38 mitogen-activated protein kinase (MAPK) in the cultures were evaluated.

Results

Exposure to high glucose (for 4, 8, and 24 hours) increased intracellular levels of ROS and phospho-p38 MAPK (indices of cellular toxicity). Atorvastatin blocked these toxic effects of high glucose, being more effective against 50 mmol/L glucose (protective effects were observed above 0.5 μmol/L) than against 83 mmol/L (protective effects were observed above 2.5 μmol/L). Atorvastatin was also able to prevent glucose-induced increase in caspase 3 activity.

Conclusions

The present study shows that high glucose may promote oxidative stress and may activate apoptotic pathways in rat PMCs. These toxic effects could be reversed by atorvastatin.

Cardiovascular disease in end-stage renal disease: the challenge of assessing and managing cardiac disease in dialysis patients

Cardiovascular disease (CVD) is the leading cause of mortality in end-stage renal disease (ESRD), approximating a 10- to 20-fold higher risk of death in dialysis patients than in the general population. Despite this, dialysis patients often undergo fewer investigations, receive less invasive procedures, and are prescribed fewer medications compared with age-matched non-ESRD patients. A lack of randomized control trials for evidence-based treatment strategies in this population may explain some of these discrepancies, but there is concern that an attitude of "therapeutic nihilism" may be impacting on the medical care of these patients. In this review, we will explore CVD in the ESRD population. Specifically, we will try to address the following issues in patients with ESRD: (1) mechanisms of CVD, (2) cardiac evaluation and the role of coronary revascularization with percutaneous or coronary artery bypass procedures, and (3) cardiac pharmacotherapy use.