Chronic kidney disease patients who smoke have higher serum phosphorus

Phosphate toxicity and SERCA2a dysfunction in sudden cardiac arrest

Almost half of the people who die from sudden cardiac arrest have no detectable heart disease. Among children and young adults, the cause of approximately one-third of deaths from sudden cardiac arrest remains unexplained after thorough examination. Sudden cardiac arrest and related sudden cardiac death are attributed to dysfunctional cardiac ion-channels. The present perspective paper proposes a pathophysiological mechanism by which phosphate toxicity from cellular accumulation of dysregulated inorganic phosphate interferes with normal calcium handling in the heart, leading to sudden cardiac arrest. During cardiac muscle relaxation following contraction, SERCA2a pumps actively transport calcium ions into the sarcoplasmic reticulum, powered by ATP hydrolysis that produces ADP and inorganic phosphate end products. Reviewed evidence supports the proposal that end-product inhibition of SERCA2a occurs as increasing levels of inorganic phosphate drive up phosphate toxicity and bring cardiac function to a sudden and unexpected halt. The paper concludes that end-product inhibition from ATP hydrolysis is the mediating factor in the association of sudden cardiac arrest with phosphate toxicity. However, current technology lacks the ability to directly measure this pathophysiological mechanism in active myocardium, and further research is needed to confirm phosphate toxicity as a risk factor in individuals with sudden cardiac arrest. Moreover, phosphate toxicity may be reduced through modification of dietary phosphate intake, with potential for employing low-phosphate dietary interventions to reduce the risk of sudden cardiac arrest.

Phosphate induces inflammation and exacerbates injury from cigarette smoke in the bronchial epithelium

An elevation in serum phosphate-also called hyperphosphatemia-is associated with reduced kidney function in chronic kidney disease (CKD). Reports show CKD patients are more likely to develop lung disease and have poorer kidney function that positively correlates with pulmonary obstruction. However, the underlying mechanisms are not well understood. Here, we report that two murine models of CKD, which both exhibit increased serum levels of phosphate and fibroblast growth factor (FGF) 23, a regulator of phosphate homeostasis, develop concomitant airway inflammation. Our in vitro studies point towards a similar increase of phosphate-induced inflammatory markers in human bronchial epithelial cells. FGF23 stimulation alone does not induce a proinflammatory response in the non-COPD bronchial epithelium and phosphate does not cause endogenous FGF23 release. Upregulation of the phosphate-induced proinflammatory cytokines is accompanied by activation of the extracellular-signal regulated kinase (ERK) pathway. Moreover, the addition of cigarette smoke extract (CSE) during phosphate treatments exacerbates inflammation as well as ERK activation, whereas co-treatment with FGF23 attenuates both the phosphate as well as the combined phosphate- and CS-induced inflammatory response, independent of ERK activation. Together, these data demonstrate a novel pathway that potentially explains pathological kidney-lung crosstalk with phosphate as a key mediator.

Curcumin alleviated oxidation stress injury by mediating osteopontin in nephrolithiasis rats

PURPOSE

To explore the role and mechanism of curcumin (Cur) in reducing oxidative stress damage in rats with nephrolithiasis induced by ethylene glycol (EG).

METHODS

Thirty male rats were divided into normal control, model, positive (10% potassium citrate), Cur-10 (10 mg/kg curcumin) and Cur-20 (20 mg/kg curcumin) groups.

RESULTS

The results of kidney tissue section stained by hematoxylin-eosin and von Kossa showed that curcumin treatment can inhibit the formation of kidney stones. The biochemical test results showed that the urea (Ur), creatinine (Cr), uric acid (UA), inorganic phosphorus and Ca2+ concentrations in urine decreased after being treated with curcumin. There were significant differences between different doses of curcumin (P < 0.05). Compared with the Cur-10 group, Cur-20 had a more significant inhibitory effect on malondialdehyde (MDA) (P < 0.05). In addition, reverse transcription polymerase chain reaction (PCR) detection and immunohistochemical results indicated that the osteopontin (OPN) in the kidney was significantly reduced after curcumin treatment.

CONCLUSIONS

Curcumin could reduce the oxidative stress damage caused by EG-induced kidney stones.

Routine laboratory testing in hemodialysis: how frequently is it needed?

Background:

Hemodialysis patients are followed by routine laboratory testing. There is uncertainty whether these tests always lead to a change in decision-making. This study aims to discover the number of yearly interventions/changes in prescription based on these tests and depict the group of patients who would benefit from reduced or increased laboratory blood tests.

Methods:

This is a multi-center retrospective study that included patients on hemodialysis for more than one year. Laboratory data collected included yearly average of hemoglobin, urea reduction ratio (URR), serum phosphate, calcium, potassium, parathormone (PTH), ferritin and transferrin saturation (TSAT); changes in prescription of erythropoietin-stimulating agents (ESAs), intravenous (IV) iron, alfacalcidol, phosphate binders and dialysis parameters were retrieved from medical records. A multivariate regression analysis assessed factors associated with high number of interventions.

Results:

A total of 210 hemodialysis patients were included: 62.4% males, 47.1% diabetics. Their median age was 72 (62,78.5) years. Their laboratory parameters were within KDIGO targets. The median number of yearly interventions was 5 (3,7) for ESAs, 4 (2,6) for IV iron, 1 (0,2.25) for phosphate binders, 0 (0,1) for alfacalcidol. Based on the multivariate analysis, patients with higher ferritin, frequent changes in ESA, more changes in alfacalcidol and higher PTH had higher number of prescription’s changes in ESA, IV iron, phosphate binders and alfacalcidol respectively.

Conclusion:

While maintaining KDIGO targets, therapeutic interventions following routine laboratory testing did not exceed six times yearly for all parameters. This suggests that a reduced testing frequency in hemodialysis patients is possible without any impact on quality of care. A personalized approach remains safe for hemodialysis patients while reducing the cost. This is very relevant in low-resource settings and during economic crises and needs to be evaluated in prospective studies.

Bone Quality in Chronic Kidney Disease Patients: Current Concepts and Future Directions - Part II

Background

Patients with chronic kidney disease (CKD) have an increased risk of osteoporotic fractures, which is due not only to low bone volume and mass but also poor microarchitecture and tissue quality. The pharmacological and nonpharmacological interventions detailed, herein, are potential approaches to improve bone health in CKD patients. Various medications build up bone mass but also affect bone tissue quality. Antiresorptive therapies strikingly reduce bone turnover; however, they can impair bone mineralization and negatively affect the ability to repair bone microdamage and cause an increase in bone brittleness. On the other hand, some osteoporosis therapies may cause a redistribution of bone structure that may improve bone strength without noticeable effect on BMD. This may explain why some drugs can affect fracture risk disproportionately to changes in BMD.

Summary

An accurate detection of the underlying bone abnormalities in CKD patients, including bone quantity and quality abnormalities, helps in institution of appropriate management strategies. Here in this part II, we are focusing on advancements in bone therapeutics that are anticipated to improve bone health and decrease mortality in CKD patients.

Key Messages

Therapeutic interventions to improve bone health can potentially advance life span. Emphasis should be given to the impact of various therapeutic interventions on bone quality.