Platelet Abnormalities in CKD and Their Implications for Antiplatelet Therapy

Platelets, Inflammation, and Purinergic Receptors in Chronic Kidney Disease

Platelets are anucleated cells that circulate in the bloodstream. Historically, platelets were thought to perform a singular function-stop bleeding via clotting. While platelets do play a key role in hemostasis and thrombosis, recent studies indicate that platelets also modulate inflammation, and this platelet-induced inflammation contributes to the pathophysiology of various diseases such as atherosclerosis and diabetes mellitus. Thus, in recent years, our understanding of platelet function has broadened. In this review, we revisit the classic role of platelets in hemostasis and thrombosis and describe the newly recognized function of platelets in modulating inflammation. We cover the potential use of purinergic receptor antagonists to prevent platelet-modulated inflammation, particularly in patients with chronic kidney disease, and finally, we define key questions that must be addressed to understand how platelet-modulated inflammation contributes to the pathophysiology of chronic kidney disease.

Association between systemic inflammatory indicators with the survival of chronic kidney disease: a prospective study based on NHANES

Background

systemic inflammation disorders were observed in chronic kidney disease (CKD). Whether the systemic inflammatory indicators could be optimal predictors for the survival of CKD remains less studied.

Methods

In this study, participants were selected from the datasets of the National Health and Nutrition Examination Survey (NHANES) between 1999 to 2018 years. Four systemic inflammatory indicators were evaluated by the peripheral blood tests including systemic immune-inflammation index (SII, platelet*neutrophil/lymphocyte), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR). Kaplan-Meier curves, restricted cubic spline (RCS), and Cox regression analysis were used to evaluate the association between the inflammatory index with the all-cause mortality of CKD. Receiver operating characteristic (ROC) and concordance index (C-index) were used to determine the predictive accuracy of varied systemic inflammatory indicators. Sensitive analyses were conducted to validate the robustness of the main findings.

Results

A total of 6,880 participants were included in this study. The mean age was 67.03 years old. Among the study population, the mean levels of systemic inflammatory indicators were 588.35 in SII, 2.45 in NLR, 133.85 in PLR, and 3.76 in LMR, respectively. The systemic inflammatory indicators of SII, NLR, and PLR were all significantly positively associated with the all-cause mortality of CKD patients, whereas the high value of LMR played a protectable role in CKD patients. NLR and LMR were the leading predictors in the survival of CKD patients [Hazard ratio (HR) =1.21, 95% confidence interval (CI): 1.07-1.36, p = 0.003 (3rd quartile), HR = 1.52, 95%CI: 1.35-1.72, p<0.001 (4th quartile) in NLR, and HR = 0.83, 95%CI: 0.75-0.92, p<0.001 (2nd quartile), HR = 0.73, 95%CI: 0.65-0.82, p<0.001 (3rd quartile), and = 0.74, 95%CI: 0.65-0.83, p<0.001 (4th quartile) in LMR], with a C-index of 0.612 and 0.624, respectively. The RCS curves showed non-linearity between systemic inflammatory indicators and all-cause mortality risk of the CKD population.

Conclusion

Our study highlights that systemic inflammatory indicators are important for predicting the survival of the U.S. population with CKD. The systemic inflammatory indicators would add additional clinical value to the health care of the CKD population.

Systemic Inflammatory Response Index (SIRI) is associated with all-cause mortality and cardiovascular mortality in population with chronic kidney disease: evidence from NHANES (2001-2018)

Objective

To examine the correlation between SIRI and the probability of cardiovascular mortality as well as all-cause mortality in individuals with chronic kidney disease.

Methods

A cohort of 3,262 participants from the US National Health and Nutrition Examination Survey (NHANES) database were included in the study. We categorized participants into five groups based on the stage of chronic kidney disease. A weighted Cox regression model was applied to assess the relationship between SIRI and mortality. Subgroup analyses, Kaplan-Meier survival curves, and ROC curves were conducted. Additionally, restricted cubic spline analysis was employed to elucidate the detailed association between SIRI and hazard ratio (HR).

Results

This study included a cohort of 3,262 individuals, of whom 1,535 were male (weighted proportion: 42%), and 2,216 were aged 60 or above (weighted proportion: 59%). Following adjustments for covariates like age, sex, race, and education, elevated SIRI remained a significant independent risk factor for cardiovascular mortality (HR=2.50, 95%CI: 1.62-3.84, p<0.001) and all-cause mortality (HR=3.02, 95%CI: 2.03-4.51, p<0.001) in CKD patients. The restricted cubic spline analysis indicated a nonlinear relationship between SIRI and cardiovascular mortality, with SIRI>1.2 identified as an independent risk factor for cardiovascular mortality in CKD patients.

Conclusion

Heightened SIRI independently poses a risk for both all-cause and cardiovascular mortality in chronic kidney disease patients, with potentially heightened significance in the early stages (Stage I to Stage III) of chronic kidney disease.

Increased cardiovascular risk in patients with chronic kidney disease

Cardiovascular disease (CVD) is highly prevalent in patients suffering from chronic kidney disease (CKD). The risk of patients with CKD developing CVD is manifested already in the early stages of CKD development. The impact of declined kidney function on increased cardiovascular risk and the underlying mechanisms are complex and multifactorial. This review discusses the impact of (a) traditional cardiovascular risk factors such as smoking, dyslipidemia, diabetes, and hypertension as well as (b) CKD-specific pathophysiological and molecular mechanisms associated with an increased cardiovascular risk. The latter include uremic toxins, post-translational modifications and uremic lipids, innate immune cell activation and inflammation, oxidative stress, endothelial cell dysfunction, increased coagulation and altered platelet responses, vascular calcification, renin-angiotensin-aldosterone-system (RAAS) and sympathetic activation, as well as anemia. Unraveling the complex interplay of different risk factors, especially in the context of patient subcohorts, will help to find new therapeutic approaches in order to reduce the increased cardiovascular risk in this vulnerable patient cohort.

Are Platelet-Related Parameters Prognostic Predictors of Renal and Cardiovascular Outcomes in IgA Nephropathy?

Background: IgA nephropathy (IgAN) is associated with chronic inflammation. Platelet-related parameters, such as the platelet (PLT) count, platelet-to-albumin ratio (PAR), and platelet-to-lymphocyte ratio (PLR), were examined as potential prognostic indicators for renal and cardiovascular (CV) outcomes in IgAN. We were interested in whether platelet-related parameters are risk factors for ESKD and CV events in IgAN patients. Methods: In a monocentric retrospective study, 124 IgAN patients were divided into two groups based on the cut-off value of the PAR. All-cause mortality, major CV events, and end-stage renal disease were the primary combined endpoints. Secondary endpoints, such as CV or renal endpoints, were also analyzed separately. Results: The patients' mean age was 43.7 ± 13.5 years, and the follow-up time was 124 ± 67 months. The K-M curve showed that the PLR, PAR, and PLT were strongly associated with primary combined (p = 0.002, p = 0.004, p = 0.001) and renal outcomes (p < 0.001, p < 0.001, p < 0.001), but not with CV outcomes in IgAN. However, when combined with left ventricular hypertrophy (LVH) or metabolic syndrome (MetS), the PAR was found to be a significant predictor of both primary (p < 0.001, p < 0.001) and secondary outcomes (p = 0.001 and p = 0.038; p = 0.001 and p = 0.015). Additionally, the PLR correlated with albuminuria (r = -0.165, p = 0.033) and LVH (r = -0.178, p = 0.025), while PLT correlated with eGFR (r = 0.158, p = 0.040). Conclusions. Elevated PARs and PLRs may predict progression to end-stage kidney disease, but in combination with LVH and MetS, they were related to CV events in IgAN. The determination of PARs and PLRs can be useful and cost-effective parameters for assessing both cardiovascular and renal risks in IgAN.

Factors influencing DVT formation in sepsis

INTRODUCTION

Sepsis is a global public health burden. Deep vein thrombosis (DVT) is the third most common cause of death from cardiovascular disease after heart attacks and strokes. We designed this experiment to investigate the factors influencing DVT formation in patients with sepsis.

METHODS

In this survey, 918 septic patients admitted to Peking Union Medical College Hospital, who underwent DVT screening were enrolled. The data were collected from June 8, 2013 to October 12, 2022. The differences between septic patients with and without DVT were studied from following aspects: basic information, comorbidities, inflammatory cytokines, albumin, source of infection, sequential organ failure assessment (SOFA) score, coagulation and prognosis.

MAIN RESULTS

In this study, the prevalence of DVT in patients with sepsis was 0.23. Elderly patients with sepsis were prone to DVT (p value < 0.001). In terms of comorbidities, septic patients with hypertension and atrial fibrillation were prone to DVT (p value 0.045 and 0.048). Inflammatory cytokines, such as procalcitonin (PCT), C-reactive protein (CRP), interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, had no significant correlation with DVT in patients with sepsis (p value 0.364, 0.882, 0.912, 0.789, 0.245, and 0.780). Levels of serum albumin correlated with DVT in patients with sepsis (p value 0.003). The SOFA total score had no relationship with DVT formation (p value 0.254). Coagulation and respiration function were negatively correlated with DVT (p value 0.018). Liver function was positively correlated with DVT (p value 0.020). Patients in the DVT group had longer duration of mechanical ventilation and longer intensive care unit (ICU) stays (p value < 0.001 and 0.006). There was no significant difference in survival in septic patients with and without DVT (p value 0.868).

CONCLUSIONS

The SOFA total score had no relationship with DVT formation. The function of each organ had different effects on DVT formation. Better coagulation and respiration function, easier DVT formation. Poorer liver function, easier DVT formation. DVT was associated with longer duration of mechanical ventilation and longer ICU stays.

Updates on New Therapies for Patients with CKD

Individuals diagnosed with chronic kidney disease (CKD) continue to increase globally. This group of patients experience a disproportionately higher risk of cardiovascular (CV) events compared to the general population. Despite multiple guidelines-based medical management, patients with CKD continue to experience residual cardiorenal risk. Several potential mechanisms explain this excessive CV risk observed in individuals with CKD. Several new drugs have become available that could potentially transform CKD care, given their efficacy in this patient population. Nevertheless, use of these drugs presents certain benefits and challenges that are often underrecognized by prescribing these drugs. In this review, we aim to provide a brief discussion about CKD pathophysiology, limiting our discussion to recent published studies. We also explore benefits and limitations of newer drugs, including angiotensin receptor/neprilysin inhibitors (ARNI), sodium glucose transporter 2 inhibitors (SGLT2i), glucagon-like peptides-1 (GLP-1) agonists and finerenone in patients with CKD. Despite several articles covering this topic, our review provides an algorithm where subgroups of patients with CKD might benefit the most from such drugs based on the selection criteria of the landmark trials. Patients with CKD who have nephrotic range proteinuria beyond 5000 mg/g, or those with poorly controlled blood pressure (systolic ≥160 mm Hg or diastolic ≥100 mm Hg) remain understudied.

Medical Management of Coronary Artery Disease in Patients with Chronic Kidney Disease

Chronic kidney disease patients are at increased risk of cardiovascular disease, which is the leading cause of mortality among this population. In addition, chronic kidney disease is a major risk factor for the development of coronary artery disease and is widely regarded as a coronary artery disease risk equivalent. Medical therapy is the cornerstone of coronary artery disease management in the general population. However, there are few trials to guide medical therapy of coronary artery disease in chronic kidney disease, with most data extrapolated from clinical trials of mainly non-chronic kidney disease patients, which were not adequately powered to evaluate this subgroup. There is some evidence to suggest that the efficacy of certain therapies such as aspirin and statins is attenuated with declining estimated glomerular filtration rate, with questionable benefit among end-stage renal disease (ESRD) patients. Furthermore, chronic kidney disease and ESRD patients are at higher risk of potential side effects with therapy, which may limit their use. In this review, we summarize the available evidence supporting the safety and efficacy of medical therapy of coronary artery disease in chronic kidney disease and ESRD patients. We also discuss the data on new emerging therapies, including PCSK9i, SGLT2i, GLP1 receptor agonists, and nonsteroidal mineralocorticoid receptor antagonists, which show promise at reducing risk of cardiovascular events in the chronic kidney disease population and may offer additional treatment options. Overall, dedicated studies directly evaluating chronic kidney disease patients, particularly those with advanced chronic kidney disease and ESRD, are greatly needed to establish the optimal medical therapy for coronary artery disease and improve outcomes in this vulnerable population.

The Association between the Platelet to White Blood Cell Ratio and Chronic Kidney Disease in an Aging Population: A Four-Year Follow-Up Study

INTRODUCTION

The platelet to white blood cell ratio (PWR) has been reported to be a prognostic factor for some diseases, such as subarachnoid hemorrhage. However, the association between the PWR and chronic kidney disease (CKD) remains unknown. To investigate the cross-sectional and longitudinal association between the PWR and CKD, this study was performed.

METHODS

This study used datasets from a national prospective cohort in China (China Health and Retirement Longitudinal Study). A retrospective cohort from 2011 to 2015 was constructed. The PWR was stratified as a categorical variable according to tertiles (T1-T3 groups). CKD was defined as an estimated glomerular filtration rate < 60 mL min-1/1.73/m2. Univariate and multivariate logistic regressions and restricted cubic spline regression were adopted to assess the linear and non-linear association between the PWR and CKD. Propensity score matching was used to balance the discrepancies between covariates. Subgroup and interactive analyses were performed to explore potential interactive effects of covariates. Missing values were interpolated using random forest. The PWR was also stratified according to the median and quartiles as sensitivity analyses.

RESULTS

A total of 8600 participants were included in this study. In the full model, the odds ratios (ORs) of prevalent CKD were 0.78 (95% CI = 0.62-0.97, p < 0.05) for the T2 group and 0.59 (95% CI = 0.46-0.76, p < 0.001) for the T3 group. There were significant interactive effects of marital status and smoking in the PWR-CKD association (both p for interaction < 0.05). An L-shaped, non-linear association was detected between the PWR and prevalent CKD in the overall population, participants ≥ 60 years, and females subgroups (all p for non-linear < 0.05). All sensitivity analyses supported the negative association between the PWR and prevalent CKD. In the 2011-2015 follow-up cohort, the ORs of incident CKD were 0.73 (95% CI = 0.49-1.08, p > 0.05) and 0.31 (95% CI = 0.18-0.51, p < 0.001) for the T2 and T3 groups, respectively, in the full model.

CONCLUSIONS

A high PWR is associated with a reduced risk of prevalent and incident CKD. The PWR may serve as a predictor for CKD, facilitating the early identification and intervention of kidney function decline.

Platelets in Renal Disease

Kidney disease is a major global health concern, affecting millions of people. Nephrologists have shown interest in platelets because of coagulation disorders caused by renal diseases. With a better understanding of platelets, it has been found that these anucleate and abundant blood cells not only play a role in hemostasis, but also have important functions in inflammation and immunity. Platelets are not only affected by kidney disease, but may also contribute to kidney disease progression by mediating inflammation and immune effects. This review summarizes the current evidence regarding platelet abnormalities in renal disease, and the multiple effects of platelets on kidney disease progression. The relationship between platelets and kidney disease is still being explored, and further research can provide mechanistic insights into the relationship between thrombosis, bleeding, and inflammation related to kidney disease, and elucidate targeted therapies for patients with kidney disease.

Management of hemorrhagic pleural effusion with intrapleural streptokinase in a patient on peritoneal dialysis and dual antiplatelet therapy

Key Clinical Message

Intrapleural streptokinase can be an option for loculated hemorrhagic pleural effusion among patients receiving CAPD and under DAPT. Its use can be individualized based on risk benefit analysis by the treating clinician.

Abstract

Pleural effusion is seen in up to 10 percent of patients on peritoneal dialysis (PD). A hemorrhagic pleural effusion is a diagnostic dilemma and a therapeutic challenge. We report a complicated case of 67 years old man with end stage renal disease, with coronary artery disease and stent in situ under dual antiplatelet therapy and continuous ambulatory peritoneal dialysis. The patient presented with left-sided loculated hemorrhagic pleural effusion. He was managed with intrapleural streptokinase therapy. His loculated effusion resolved without any local and systemic bleeding manifestations. Therefore, in poor resource settings, Intrapleural streptokinase can be an option for loculated hemorrhagic pleural effusion among patients receiving CAPD and under DAPT. Its use can be individualized based on risk benefit analysis by the treating clinician.

Pathophysiological Changes in the Hemostatic System and Antithrombotic Management in Kidney Transplant Recipients

Nowadays, the main cause for early graft loss is renal graft thrombosis because kidney transplant outcomes have improved drastically owing to advances in immunological techniques and immunosuppression. However, data regarding the efficacy of antithrombotic therapy in the prevention of renal graft thrombosis are scarce. Adequate antithrombotic management requires a good understanding of the pathophysiological changes in the hemostatic system in patients with end-stage kidney disease (ESKD). Specifically, ESKD and dialysis disrupt the fine balance between pro- and anticoagulation in the body, and further changes in the hemostatic system occur during kidney transplantation. Consequently, kidney transplant recipients paradoxically are at risk for both thrombosis and bleeding. This overview focuses on the pathophysiological changes in hemostasis in ESKD and kidney transplantation and provides a comprehensive summary of the current evidence for antithrombotic management in (adult) kidney transplant recipients.

Use of Computation Ecosystems to Analyze the Kidney-Heart Crosstalk

The identification of mediators for physiologic processes, correlation of molecular processes, or even pathophysiological processes within a single organ such as the kidney or heart has been extensively studied to answer specific research questions using organ-centered approaches in the past 50 years. However, it has become evident that these approaches do not adequately complement each other and display a distorted single-disease progression, lacking holistic multilevel/multidimensional correlations. Holistic approaches have become increasingly significant in understanding and uncovering high dimensional interactions and molecular overlaps between different organ systems in the pathophysiology of multimorbid and systemic diseases like cardiorenal syndrome because of pathological heart-kidney crosstalk. Holistic approaches to unraveling multimorbid diseases are based on the integration, merging, and correlation of extensive, heterogeneous, and multidimensional data from different data sources, both -omics and nonomics databases. These approaches aimed at generating viable and translatable disease models using mathematical, statistical, and computational tools, thereby creating first computational ecosystems. As part of these computational ecosystems, systems medicine solutions focus on the analysis of -omics data in single-organ diseases. However, the data-scientific requirements to address the complexity of multimodality and multimorbidity reach far beyond what is currently available and require multiphased and cross-sectional approaches. These approaches break down complexity into small and comprehensible challenges. Such holistic computational ecosystems encompass data, methods, processes, and interdisciplinary knowledge to manage the complexity of multiorgan crosstalk. Therefore, this review summarizes the current knowledge of kidney-heart crosstalk, along with methods and opportunities that arise from the novel application of computational ecosystems providing a holistic analysis on the example of kidney-heart crosstalk.

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Iron Deficiency and Iron Deficiency Anemia: Potential Risk Factors in Bone Loss

Iron is one of the essential mineral elements for the human body and this nutrient deficiency is a worldwide public health problem. Iron is essential in oxygen transport, participates in many enzyme systems in the body, and is an important trace element in maintaining basic cellular life activities. Iron also plays an important role in collagen synthesis and vitamin D metabolism. Therefore, decrease in intracellular iron can lead to disturbance in the activity and function of osteoblasts and osteoclasts, resulting in imbalance in bone homeostasis and ultimately bone loss. Indeed, iron deficiency, with or without anemia, leads to osteopenia or osteoporosis, which has been revealed by numerous clinical observations and animal studies. This review presents current knowledge on iron metabolism under iron deficiency states and the diagnosis and prevention of iron deficiency and iron deficiency anemia (IDA). With emphasis, studies related to iron deficiency and bone loss are discussed, and the potential mechanisms of iron deficiency leading to bone loss are analyzed. Finally, several measures to promote complete recovery and prevention of iron deficiency are listed to improve quality of life, including bone health.

Effects of aspirin on cardiovascular outcomes in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) carry a high cardiovascular (CV) risk. Since whether this risk is reduced by aspirin is unclear, we examined if the effect of aspirin on cardiovascular outcomes varied by baseline kidney function in a primary cardiovascular disease prevention trial. The International Polycap Study-3 (TIPS-3) trial had randomized people without previous cardiovascular disease to aspirin (75 mg daily) or placebo. We now examined aspirin versus placebo on cardiovascular events in participants grouped by estimated glomerular filtration rate (eGFR), using a threshold of 60 ml/min/1.73 m2, and by using tertiles of eGFR. The primary outcome was a composite of non-fatal myocardial infarction, non-fatal stroke or cardiovascular death. A total of 5712 participants were randomized with a mean follow-up of 4.6 years. Of these, 983 (17.2%) had an eGFR under 60 ml/min/1.73 m2 (mean eGFR 49 ml/min/1.73 m2) and 4,729 over 60 ml/min/1.73 m2 (mean 84 ml/min/1.73 m2). In participants with an eGFR under 60 ml/min/1.73 m2 there were 26 primary outcomes in 502 participants on aspirin and 39/481 on placebo (hazard ratio 0.57; 95% confidence interval 0.34-0.94). In participants with an eGFR over 60 ml/min/1.73 m2 there were 90 primary outcomes in 2357 participants on aspirin and 95/2372 on placebo (0.95; 0.71-1.27). With tertiles of eGFR under 70, 70-90, and over 90 ml/min/1.73 m2, risk reductions with aspirin for the primary outcome were larger at lower eGFR levels (0.62; 0.43-0.91) for the lowest tertile, (0.96; 0.62-1.49) for the middle, and (1.30; 0.77-2.18) for the highest tertile. Thus, our findings support aspirin may reduce cardiovascular events in people with moderate to advanced stage CKD.

The relationship between platelet distribution width and new-onset cardiovascular disease events in patients with peritoneal dialysis

Objectives

The global mortality rate from chronic kidney disease (CKD) has increased over the past two decades. Typically, peritoneal dialysis (PD) remains a useful alternative treatment for end-stage renal disease. Cardiovascular disease (CVD) is the main complication in PD patients. In terms of prognosis, it is reported that platelet distribution width (PDW) can predict adverse CVD events. However, the relationship between PDW and new-onset CVD in PD patients is not clear. This study aimed to explore the relationship between PDW and new-onset CVD in PD patients.

Methods

This was a retrospective cohort study, from 4 July 2005 to 31 December 2019, and a total of 1557 patients were recruited. PDW was respectively categorized into two groups: PDW ≤13.2 fL and PDW >13.2 fL. The primary outcome was a new-onset CVD event. Cox proportional hazards models were performed to assess the hazard ratio (HR). Receiver-operating characteristic (ROC) curves were applied to evaluate the predictive accuracy of the PDW on CVD events.

Results

During follow-up, 114 new-onset CVD events were recorded. Cox proportional hazards models showed a higher risk of CVD events in patients with high PDW (HR = 1.862 95%CI 1.205–2.877, p = 0.005). Kaplan–Meier cumulative incidence curves showed the risk of the first occurrence of CVD events was greater in the high PDW group (p = 0.006).

Conclusions

High PDW is associated with new-onset cardiovascular disease events in PD patients.

Renal Klotho safeguards platelet lifespan in advanced chronic kidney disease through restraining Bcl-xL ubiquitination and degradation

BACKGROUND

Thrombosis and hemorrhage as two opposite pathologies are prevalent within the chronic kidney disease (CKD) population. Platelet homeostasis, which positions centrally in their pathogenesis, varies among the CKD population, while the underlying mechanism is poorly understood.

OBJECTIVE

To investigate the change character and mechanism of platelet homeostasis in CKD and its association with renal Klotho deficiency.

METHODS

The change character of platelet homeostasis and its association with renal Klotho deficiency were determined based on a cohort study as well as CKD mice and Klotho-deficient mice with CKD. The effects on thrombopoiesis and platelet lifespan were examined by flow cytometry and platelet transfer. The underlying mechanism was explored by proteomics, flow cytometry, western blot, and immunoprecipitation.

RESULTS

We show that platelet count declines both in patient and mouse models with advanced CKD (Adv-CKD) and is positively associated with circulating Klotho levels. Mechanistically, we identify that ubiquitin ligase UBE2O governs Bcl-xL ubiquitination and degradation in platelets, whereas Adv-CKD-induced oxidative stress in platelets stimulates p38MAPK to promote Bcl-xL phosphorylation, which facilitates UBE2O binding to Bcl-xL and subsequent Bcl-xL degradation. Consequently, platelet lifespan is shortened in Adv-CKD, culminating in platelet count decline. However, kidney-secreted soluble Klotho protein restricts oxidative stress in platelets, thereby preserving Bcl-xL expression and platelet lifespan.

CONCLUSIONS

Our findings uncover the mechanism of platelet count decline in Adv-CKD and identify renal Klotho as a long-range regulator of platelet lifespan, which not only provide a molecular mechanism underlying CKD-associated thrombocytopenia and hemorrhage but also offer a promising therapy choice.

Aspirin for Primary and Secondary Prevention of Mortality, Cardiovascular Disease, and Kidney Failure in the Chronic Renal Insufficiency Cohort (CRIC) Study

Rationale and Objective

Chronic kidney disease is a risk enhancing factor for cardiovascular disease (CVD) and mortality, and the role of aspirin use is unclear in this population. We investigated the risk and benefits of aspirin use in primary and secondary prevention of CVD in the Chronic Renal Insufficiency Cohort Study.

Study Design

Prospective observational cohort.

Setting & Participants

3,664 Chronic Renal Insufficiency Cohort participants.

Exposure

Aspirin use in patients with and without preexisting CVD.

Outcomes

Mortality, composite and individual CVD events (myocardial infarction, stroke, and peripheral arterial disease), kidney failure (dialysis and transplant), and major bleeding.

Analytical Approach

Intention-to-treat analysis and multivariable Cox proportional hazards model to examine associations of time varying aspirin use.

Results

The primary prevention group was composed of 2,578 (70.3%) individuals. Mean age was 57 ± 11 years, 46% women, 42% Black, and 47% had diabetes. The mean estimated glomerular filtration rate was 45 mL/min/1.73 m2. Median follow-up was 11.5 (IQR, 7.4-13) years. Aspirin was not associated with all-cause mortality in those without preexisting cardiovascular disease (CVD) (HR, 0.84; 95% CI, 0.7-1.01; P = 0.06) or those with CVD (HR, 0.88; 95% CI, 0.77-1.02, P = 0.08). Aspirin was not associated with a reduction of the CVD composite in primary prevention (HR, 0.97; 95% CI, 0.77-1.23; P = 0.79) and in secondary prevention because the original study design was not meant to study the effects of aspirin.

Limitations

This is not a randomized controlled trial, and therefore, causality cannot be determined.

Conclusions

Aspirin use in chronic kidney disease patients was not associated with reduction in primary or secondary CVD events, progression to kidney failure, or major bleeding.

Platelet-Dependent Inflammatory Dysregulation in Patients with Stages 4 or 5 Chronic Kidney Disease: A Mechanistic Clinical Study

Background

Chronic kidney disease (CKD) is characterized by dysregulated inflammation that worsens with CKD severity. The role of platelets in modulating inflammation in stage 4 or 5 CKD remains unexplored. We investigated whether there are changes in platelet-derived thromboinflammatory markers in CKD with dual antiplatelet therapy (DAPT; aspirin 81 mg/d plus P2Y12 inhibitor).

Methods

In a mechanistic clinical trial, we compared platelet activation markers (aggregation and surface receptor expression), circulating platelet-leukocyte aggregates, leukocyte composition (monocyte subtypes and CD11b surface expression), and plasma cytokine profile (45 analytes) of non-CKD controls (n=26) and CKD outpatients (n=48) with a glomerular filtration rate (GFR) <30 ml/min per 1.73 m² on 2 weeks of DAPT.

Results

Patients with CKD demonstrated a reduced mean platelet count, elevated mean platelet volume, reduced platelet-leukocyte aggregates, reduced platelet-bound monocytes, higher total non-classic monocytes in the circulation, and higher levels of IL-1RA, VEGF, and fractalkine (all P<0.05). There were no differences in platelet activation markers between CKD and controls. Although DAPT reduced platelet aggregation in both groups, it had multifaceted effects on thromboinflammatory markers in CKD, including a reduction in PDGF levels in all CKD individuals, reductions in IL-1β and TNF-α levels in select CKD individuals, and no change in a number of other cytokines. Significant positive correlations existed for baseline IL-1β, PDGF, and TNF-α levels with older age, and for baseline TNF-α levels with presence of diabetes mellitus and worse albuminuria. Mean change in IL-1β and PDGF levels on DAPT positively correlated with younger age, mean change in TNF-α levels with higher GFR, and mean changes in PDGF, and TRAIL levels correlated with worse albuminuria. Minimum spanning trees plot of cytokines showed platelet-derived CD40L had a large reduction in weight factor after DAPT in CKD. Additionally, platelet-derived IL-1β and PDGF were tightly correlated with other cytokines, with IL-1β as the hub cytokine.

Conclusions

Attenuated interactions between platelets and leukocytes in the CKD state coincided with no change in platelet activation status, an altered differentiation state of monocytes, and heightened inflammatory markers. Platelet-derived cytokines were one of the central cytokines in patients with CKD that were tightly correlated with others. DAPT had multifaceted effects on thromboinflammation, suggesting that there is platelet-dependent and -independent inflammation in stage 4 or 5 CKD.

[Heart and diabetes : Platelet function and antiplatelet therapy in chronic kidney disease]

Patients with chronic kidney disease (CKD) have an increased risk of thrombosis and approximately 50% of patients with advanced CKD die because of a cardiovascular disease. In addition to an increased risk of thrombosis, patients with CKD and particularly with advanced CKD, have an increased risk of hemorrhage, which increases parallel to the decline of kidney function. Due to this parallel existence of the prohemorrhagic and prothrombotic phenotype, antiplatelet treatment is difficult in the daily routine and data show that CKD patients with acute coronary syndrome (ACS) are less likely to receive guideline-conform treatment. The underlying mechanisms are currently insufficiently understood and both platelet-dependent mechanisms and also platelet-independent mechanisms are under discussion. Accordingly, there is currently no specific treatment or treatment strategy for patients with CKD. In addition, CKD patients are underrepresented in registration studies on antiplatelet treatment and there are no data from randomized trials for patients with advanced CKD (CKD ≥ 4). Current guideline recommendations are therefore based on subgroup analyses and observational studies. In addition, questions on the duration of treatment, on risk scores for estimation of the risk of hemorrhage and on potential benefits of escalation and de-escalation strategies remain largely unanswered and should therefore be the focus of future studies.

Platelet-to-Albumin Ratio: A Novel IgA Nephropathy Prognosis Predictor

Background

Chronic inflammation is related to the development of IgA nephropathy (IgAN). Emerging studies have reported that platelet-related parameters including platelet (PLT), platelet-to-albumin ratio (PAR), and platelet-to-lymphocyte ratio (PLR) are proved to be novel prognostic indicators for several inflammatory diseases. Whether platelet-related parameters could serve as predictors for IgAN remains unknown.

Methods

A total of 966 IgAN patients were enrolled in this retrospective study and were divided into several groups based on the optimal cut-off value of the platelet-related parameters. End-stage renal disease was used as the renal endpoint. A 1:2 propensity score (PS) match was then carried out to eliminate significant differences at baseline. The area under the receiver operating characteristic curve (AUROC), Kaplan–Meier (K-M) curve, and Cox proportional hazards analyses were performed to evaluate their predictive effect.

Results

Without considering the effect of covariates, the K-M curve showed that PLT, PLR, and PAR were strongly correlated with the renal outcomes of IgAN. However, the AUROC revealed that the PAR and PLR had better predictive power than the PLT. Multivariate Cox regression adjusting for demographic data, pathological findings, treatment, and laboratory results indicated that compared with PLR, albumin and PLT, PAR seemed to be a better marker of adverse renal outcome, implying that PAR was the only platelet-related parameter that could be used as an independent risk factor. Notably, high PAR patients seemed to have more severe clinical manifestations and pathological lesions. However, after eliminating the influence of different baselines on outcome variables, the PAR could still predict the poor prognosis of IgAN. To more accurately evaluate the predictive power of the PAR, we analyzed the predictive effect of the PAR on patients with different clinicopathological characteristics through subgroup analysis. It was indicated that the PAR might better predict the prognosis and outcome of patients whose disease was already very severe.

Conclusion

PAR might be used as an independent risk factor for IgAN progression.

Effect of Near-Infrared Blood Photobiomodulation on Red Blood Cell Damage from the Extracorporeal Circuit during Hemodialysis In Vitro

The contact of blood with the bioincompatible membranes of the dialyzer, which is part of the extracorporeal circuit during hemodialysis (HD), causes upregulation of various cellular and non-cellular processes, including massive generation and release of reactive oxygen species (ROS), (which is one of the primary causes of anemia in chronic renal failure). We hypothesize that near-infrared (NIR) radiation possesses antioxidant properties and is considered to protect the red blood cell (RBC) membrane by enhancing its resilience to negative pressures. Our experimental setup consisted of an HD machine equipped with a dialyzer with a polyamide membrane; whole bovine blood was examined in vitro in blood-treated circulation. Blood samples were taken at 0, 5, 15, and 30 min during the HD therapy. We also assessed osmotic fragility, hematocrit, hemolysis, and oxidative stress as a concentration of reactive thiobarbituric acid substances (TBARS). Our results have shown that RBC membrane peroxidation increased significantly after 30 min of circulation, whereas the TBARS level in NIR-treated blood remained relatively steady throughout the experiment. The osmotic fragility of NIR-irradiated samples during dialysis was decreased compared to control samples. Our studies confirm that in vitro, blood photobiomodulation using NIR light diminishes oxidative damage during HD and can be considered a simultaneous pretreatment strategy for HD.