Darbepoetin alpha reduces oxidative stress and chronic inflammation in atherosclerotic lesions of apo E deficient mice in experimental renal failure

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.

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Osthole protects against inflammation in a rat model of chronic kidney failure via suppression of nuclear factor-κB, transforming growth factor-β1 and activation of phosphoinositide 3-kinase/protein kinase B/nuclear factor (erythroid-derived 2)-like 2 signaling

Multiple pharmacological applications of osthole have been previously recognized, including antioxidant, anti-inflammatory, anti‑platelet and estrogenic effects, and resistance to pain. The present study investigated the protective effects of osthole against inflammation in a rat model of chronic kidney failure (CRF) and the underlying mechanisms. Osthole treatment with significantly reversed CRF‑induced changes in serum creatinine, calcium, phosphorus and blood urea nitrogen levels in CRF rats. Male Sprague‑Dawley rats (age, 8 weeks) received 200 mg/kg 2% adenine suspension to induce CRF in the model group. In the osthole‑treated group, rats received 200 mg/kg 2% adenine suspension + osthole (40 mg/kg, intravenously). The results revealed that treatment with osthole significantly inhibited CRF‑induced tumor necrosis factor‑α, interleukin (IL)‑8 and IL‑6 expression, and suppressed nuclear factor‑κB (NF‑κB) protein expression in CRF rats. Osthole treatment significantly attenuated the protein expression of transforming growth factor‑β1 (TGF‑β1), reduced monocyte chemoattractant protein‑1 activity and increased the phosphoinositide 3‑kinase (PI3K)/protein kinase B (Akt) ratio in CRF rats. These results suggested that osthole protects against inflammation in a rat model of CRF via suppression of NF‑κB and TGF‑β1, and activation of PI3K/Akt/nuclear factor (erythroid‑derived 2)‑like 2 signaling. Therefore, osthole may represent a potential therapeutic agent for the treatment of CRF.

Possible Inhibitory Effect of Erythropoiesis-Stimulating Agents at the Predialysis Stage on Early-Phase Coronary Events after Hemodialysis Initiation

BACKGROUND

We examined whether the use of erythropoiesis-stimulating agents (ESAs) to correct anemia at the predialysis stage could inhibit early-phase coronary events after hemodialysis initiation.

METHODS

We enrolled 242 patients with chronic kidney disease who had received continued medical treatments and initiated maintenance hemodialysis from 1 September 2000 to 31 December 2014 at Toujinkai Hospital. Patients with a previous history of blood transfusion or any cardiovascular events or interventions were excluded. The coronary events were followed for 1 year after initiation of hemodialysis.

RESULTS

Coronary events occurred in 51 of 242 patients: 10 patients had acute coronary syndrome [9 with percutaneous coronary intervention (PCI), 1 without intervention], and 41 had elective coronary revascularization (38 PCI and 3 coronary artery bypass graft). ESA was administered in 118 of 242 patients (48.8%). In stepwise logistic analysis, coronary events were positively associated with nonuse of ESA at the predialysis stage (odds ratio 2.66, p = 0.005) and diabetes mellitus (odds ratio 5.33, p < 0.001). When dividing the patients into 4 subgroups by blood hemoglobin (Hb) level (8.5 g/dl) and the use/nonuse of ESA, coronary event-free survival rates were higher (p = 0.005) in those with Hb ≥8.5 g/dl, ESA+ (86.6%, n = 82) and tended to be higher (p = 0.055) in those with Hb <8.5 g/dl, ESA+ (86.1%, n = 36) than in patients with Hb <8.5 g/dl, ESA- (68.6%, n = 86) in a Kaplan-Meier analysis.

CONCLUSIONS

The use of ESA to correct anemia at the predialysis stage may inhibit early-phase coronary events after hemodialysis initiation.

Signaling pathway factors expression in renal tissue of apoE-knockout mice

Apolipoprotein E (apoE) is regarded as one of the major plasma lipoproteins, and it plays an important role in the transport and metabolism of lipids. apoE can be found in multiple tissues, such as liver, kidney, jejunum, urinary bladder, ileum, colon, brain, adrenal glands, lung, ovary, spleen, pancreas, and testis, etc. As a secreted protein, it plays an important role in the systemic lipoprotein metabolism and vascular wall homeostasis and in the pathogenesis of renal diseases. apoE-knockout (apoE(-/-)) mice is a classic model of atherosclerosis and renal diseases. However, no review summed up the signaling pathway factors expression in renal tissue of apoE-knockout mice. The literatures were searched extensively and this review was performed to review the signaling pathway factors expression in renal tissue of apoE-knockout mice.