Changes in platelet volume, morphology and RNA content in subjects treated with haemodialysis

Immature platelet fraction in rheumatoid arthritis with interstitial lung disease

BACKGROUND

Platelets have an effect on the hemostatic defense of the lung. Immature platelet fractions (iPF) reflects the number of young platelets containing ribonucleic acid in the circulation and real-time production. Information about their roles in rheumatic diseases is limited and there are no studies on iPF in RA with interstitial lung disease (ILD). Our aim is to investigate the association between the iPF level and occurrence of ILD in RA and the correlation of iPF with disease activity in general or only in RA with ILD.

METHODS

The study included 50 RA patients without ILD, 33 RA patients with ILD, and 30 healthy controls. Demographic data, Disease Activity Score 28 (DAS28), autoantibodies, and iPF were evaluated. ILD was diagnosed by using high-resolution computed tomography with clinical findings and chest X-ray. The samples were analyzed for complete blood count with platelet indices included, on Mindray BC-6800 hematology analyzer, Hamburg, Germany.

RESULTS

iPF levels were higher in RA patients with ILD compared to healthy controls and RA patients without ILD. A weakly positive correlation between DAS28 with iPF was found in all RA patients. iPF levels were found as 2.85 to detect ILD with 66.7% sensitivity and 65% specificity.

CONCLUSIONS

Our results showed that the iPF was detected higher in RA with ILD compared to RA without ILD. iPF, a routine cheap and easy test during hemogram, can provide important information in terms of disease activity and lung involvement in RA.

Significance of mild thrombocytopenia in maintenance hemodialysis patients; a retrospective cohort study

Platelet activation in the hemodialysis (HD) circuit often causes thrombocytopenia. However, its clinical and pathophysiological significance has rarely been explored. Herein, we investigated the predictive value of thrombocytopenia for cardiovascular events (CVE) in maintenance HD patients and attempted to explore its mechanistic background considering recent knowledge of platelet dynamics. We conducted a retrospective cohort study on HD patients with the composite primary endpoint of predicting CVE, i.e., myocardial infarction, ischemic stroke, and cardiovascular death. Baseline clinical data were analyzed and explored. Multivariate Cox regression analysis showed that platelet decrease was independently associated with CVE. Thrombocytopenia was correlated with the disuse of antiplatelet therapy (APT) and macrocytosis. These findings are possibly associated with platelet activation and senescent hematopoiesis. The prognostic significance of thrombocytopenia was more prominent in patients undergoing APT, implying the presence of APT-resistant platelets in such patients. To fully explain these results, we hypothesized that HD-activated platelets induce the biological aging of hematopoiesis, which is presumably extramedullary in the lung, where activated platelets could deliver massive amounts of inflammatory cytokines and reactive oxidative species. This results in the production of qualitatively altered and hyper-reactive platelets, a process that could form a vicious cycle that induces CVE-associated thrombocytopenia. Further investigations focusing on the dynamics of the biological aging of platelets in HD patients are warranted.

Immature Platelet Fraction in Rheumatoid Arthritis with Interstitial Lung Disease

BACKGROUND

Platelets have an effect on the hemostatic defense of the lung. Immature platelet fractions (iPF) reflects the number of young platelets containing ribonucleic acid in the circulation and real-time production. Information about their roles in rheumatic diseases is limited and there are no studies on iPF in RA with interstitial lung disease (ILD). Our aim is to investigate the association between the iPF level and occurrence of ILD in RA and the correlation of iPF with disease activity in general or only in RA with ILD.

METHODS

The study included 50 RA patients without ILD, 33 RA patients with ILD, and 30 healthy controls. Demographic data, Disease Activity Score 28 (DAS28), autoantibodies, and iPF were evaluated. ILD was diagnosed by using high-resolution computed tomography with clinical findings and chest X-ray. The samples were analyzed for complete blood count with platelet indices included, on Mindray BC-6800 hematology analyzer, Hamburg, Germany.

RESULTS

iPF levels were higher in RA patients with ILD compared to healthy controls and RA patients without ILD. A weakly positive correlation between DAS28 with iPF was found in all RA patients. iPF levels were found as 2.85 to detect ILD with 66.7% sensitivity and 65% specificity.

CONCLUSIONS

Our results showed that the iPF was detected higher in RA with ILD compared to RA without ILD. iPF, a routine cheap and easy test during hemogram, can provide important information in terms of disease activity and lung involvement in RA.

Hematological Parameters and Clinical Features in Patients with Advanced Chronic Kidney Disease

Background

Hematological parameters like red cell distribution width (RDW) and mean platelet volume (MPV) were reported to be associated with inflammation, atherosclerosis, and chronic kidney disease (CKD) progression. In this study, we evaluated RDW and MPV along with clinical features in patients with advanced CKD. We also aimed to detect clues for causative relations concerning these parameters, renal function and comorbidities.

Methods

Stage 3-5 CKD patients (627 total) were included (mean age 63.1 years, 48.3% male). Patients with malignancies, cirrhosis, infections, severe anemia, and systemic inflammation were excluded. Patients were evaluated for clinical features and grouped for comparison using median RDW and MPV. Linear regression models were generated to predict potential influences on RDW and MPV.

Results

Mean estimated glomerular filtration rate (eGFR) was 27.3 mL/min/1.73m². Mean Charlson Comorbidity Index (CCI) score was 5.83 ± 2.06. Patients with high RDW (n = 303) were older with higher CRP and CCI, they also had lower eGFR, hemoglobin, and albumin (P < 0.001 for all). Patients with low MPV (n = 311) had lower eGFR, and platelet counts (P = 0.015 and 0.017). eGFR was negatively correlated with RDW after adjusting for age, gender and comorbidities. In a further adjusted model RDW was associated with CRP, CCI, hemoglobin and albumin (P < 0.05 for all), not with eGFR. MPV was positively correlated with eGFR in our adjusted, and fully adjusted regression models (P = 0.003).

Conclusion

In this study, we found that high RDW is associated with comorbidity burden, anemia, and inflammatory status in patients with advanced CKD. Meanwhile, low MPV seems to be associated with worse renal function.

Understanding Serotonin 5-HT2A Receptors-regulated cellular and molecular Mechanisms of Chronic Kidney Diseases

Chronic kidney diseases (CKD) are an economic burden and occur worldwide in all age groups, and the advancement of kidney disease at some point leads to deregulate or influence the function of other body organs and to find a specific target to halt the disease progression which is a tedious challenge. Regardless of the underlying mechanisms, it is essential to consider and evaluate the involvement and association of individual endogenous mediators and environmental factors in the progression of CKD to accumulate the required knowledge. More than a dozen pathways leading to relentless progression of CKD have been identified so far, but the association of serotonin 5-HT2A receptor with progressive renal injury is still under process.

Scientific reports demonstrated that the 5-HT2A receptor plays a significant role in renal metabolism, glomerular function, and renal vascular tone. So a better understanding of the evolving role of serotonin 5-HT2A-mediated pathophysiological mechanisms of CKD may be a helpful tool to identify new therapeutic targets. In this review, we will discuss recent interventions, pharmacological target, and the possible implication of serotonin 5-HT2A receptors with associated mechanistic trails leading to CKD.

Impact of renal function on mean platelet volume and its relationship with coronary artery disease: A single-centre cohort study

BACKGROUND

Mean platelet volume (MPV) has been proposed as a marker of platelet reactivity and cardiovascular disease. Chronic kidney disease (CKD) significantly favors the occurrence of cardiovascular events, by increasing the circulating levels of a wide spectrum of pro-oxidant and pro-thrombotic mediators. However, opposite alterations of platelet function, both enhanced aggregability and increased bleeding diathesis have been reported in these patients, with contrasting results on the effects of renal function on MPV and coronary artery disease, that were assessed in present study.

METHODS

In patients undergoing coronary angiography, MPV and renal function (serum creatinine and estimated Glomerular Filtration Rate, eGFR, by MDRD formula) were assessed at admission. Coronary artery disease (CAD) was defined as a stenosis >50% in at least 1 coronary vessel, while severe CAD as left main or trivessel disease.

RESULTS

Among 3712 patients, 1044 (28.1%) had chronic kidney disease. CKD was related with age, female gender, diabetes and glycemic control, history of myocardial infarction, cerebrovascular accidents, coronary artery bypass grafting and left ventricular dysfunction or arrhythmias as indication to angiography, therapy with angiotensin-receptor blockers, nitrates, diuretics and calcium-antagonists, but lower rate of smoking, lower fibrinogen levels, haemoglobin, total and HDL cholesterol (p<0.001, respectively). CKD patients displayed increased severity and complexity of CAD (p<0.001) and significantly larger platelet volume (p<0.001), with CKD resulting as independent predictor of MPV above the median (≥10.85fl; Adjusted OR[95%CI]=1.56[1.23,1.99], p=0.002). Moreover, in the 1044 patients with renal failure, higher platelet volume (above the median value; ≥10.85fl) was associated with age (p=0.05), haemoglobin levels and platelet count (p<0.001), but not to a higher prevalence or extent of coronary artery disease (CAD: adjusted OR[95%CI]=0.80[0.58-1.09], p=0.16; severe CAD, adjusted OR[95%CI]=1.07[0.81-1.41], p=0.65).

CONCLUSIONS

Higher values of MPV are observed among patients with chronic kidney disease, inversely relating to eGFR. However, larger platelet size does not contribute to explain the increased severity of coronary artery disease observed among these patients.

Aspects of platelet disturbances in haemodialysis patients

Patients with mild-to-chronic kidney disease (CKD) exhibit a variety of haemostatic disorders, ranging from an increased clotting tendency and reductions in the levels of natural inhibitors of coagulation to defective fibrinolysis. In addition, platelet (PLT) abnormalities are common. In this minireview, we report on aspects of haemodialysis (HD)-induced PLT activation. It is demonstrated that PLTs from HD patients are exhausted due to repeated stimulation of HD treatment and recurrent release of PLT degranulation products. During HD, additional aberrations of the haemostatic process occur. Besides deviations of coagulation and fibrinolysis, PLT activation and a reduction in their granule content have been observed during HD treatment. As HD treatment is carried out three times per week, month after month, chronic HD patients may suffer persistently from coagulation defects and PLT disorders on top of the alterations induced by the uraemic state itself. PLT activation occurs together with thrombin and fibrin generation. However, macro fibrin depositions in clot devices are not demonstrated, microaggregates occur not only in the extracorporeal circuit (ECC) but are also present in the blood circulation. As vascular access thrombosis is a frequent complication in patients with HD treatment, it is believed that hypercoagulability could result from vascular changes combined with PLTs and activation of coagulation factors.

Coagulation activation, depletion of platelet granules and endothelial integrity in case of uraemia and haemodialysis treatment

Background

During haemodialysis (HD) treatment, increase of platelet (PLT) activation and induction of procoagulant activity is demonstrated. Although the role of the endothelium and its direct interaction with coagulation and homeostasis is known, it is not elucidated how PLT activation markers and activation of coagulation coincide with markers of endothelial integrity during HD treatment. In the present study uraemia and HD induced changes, with particular emphasis on PLT granules depletion, activation of coagulation and endothelial integrity were investigated.

Methods

To detect depletion of PLT granules, peripheral blood slide smears were screened by light microscopy for qualitative evaluation of PLT granule containing cytoplasm, as indicated by its granules staining density. Activation of coagulation was investigated by establishement of thrombin-antithrombin (TAT) and fibrinogen concentrations. To evaluate endothelial integrity proendothelin (proET-1) plasma concentrations were established.

Results

Results of our study demonstrate that proET-1 plasma concentrations were obviously increased in the subjects’ group with end-stage chronic kidney disease (CKD) and renal failure if compared with a group of apparently healthy subjects. The amount of depleted PLT granules was obviously increased in the subjects’ group with end-stage CKD if compared with the group with renal failure. Mean plasma concentrations of TAT and fibrinogen revealed results within the reference range.

Conclusions

It is demonstrated that uraemia is associated with endothelial damage and aberrations in PLT granules morphology in subjects with HD treatment. We hypothesize that increased proET-1 concentrations reflect ongoing stress on endothelial cells amongst others due to uraemia. Biomarkers like proET-1 and aberrations in PLT granules morphology assist in the early detection of procoagulant activity of the endothelium.

Alteration of the platelet transcriptome in chronic kidney disease

Bleeding and thrombotic disorders are major complications affecting patients with chronic kidney disease (CKD). Exposure of circulating platelets to uraemic toxins and contact with artificial surfaces during dialysis induce platelet abnormalities and alter the platelet proteome. We hypothesised that these changes may be subsequent to changes in the composition and/or regulation of the platelet transcriptome. In this study, we investigated the circulating platelets of 10 CKD patients (i.e. five chronic haemodialysis patients and five stage 4 CKD uraemic patients) and five age- and sex-matched healthy subjects. We observed an alteration of the platelet messenger RNA (mRNA) and microRNA transcriptome in CKD patients. Impaired in uraemic platelets, the levels of some mRNAs and of most microRNAs appeared to be corrected by dialysis, which is consistent with a beneficial effect of dialysis and a mRNA regulatory role of platelet microRNAs. Reduced in platelets of uraemic patients, phosphatidylcholine transfer protein (PCTP) and WD repeat-containing protein 1 (WDR1) were found to be regulated by microRNAs, the latter of which involving hsa-miR-19b, a microRNA increased in platelets of uraemic patients and involved in platelet reactivity. These results suggest that an alteration of microRNA-based mRNA regulatory mechanisms may underlie the platelet response to uremia and entail the development of platelet-related complications in CKD.

Electron microscopic observation in case of platelet activation in a chronic haemodialysis subject

During haemodialysis (HD), platelets (PLTs) are activated and release granule contents. As HD treatment occurs three times a week, it has been demonstrated that PLTs are exhausted due to the repetitive character of the treatment. To identify PLT depletion morphologically, PLT evaluation was performed by light microscopy and electron microscopy (EM) in a chronic HD subject and a healthy reference subject. Blood samples were taken before the start of HD treatment for measurement of PLT count, PLT volume and size parameters. Blood smears were screened by light microscopy for qualitative evaluation of PLT granule containing cytoplasm, as indicated by its staining density. Morphological PLT parameters of surface area and size of dense bodies were assessed by EM. Data were compared with results of a group of 20 chronic HD subjects and a group of 20 healthy reference subjects. With respect to the percentage of PLTs with appropriate staining density (>75%), light microscopic evaluation showed that this value (9%) was within the range of a group of chronic HD subjects, but considerably below the reference range (70%). EM evaluation revealed an average PLT surface area and dense bodies area of respectively 42% and 31%, if the healthy reference subject was set on 100%. PLTs from a chronic HD subject are considerably smaller and substantially less granular than PLTs from a healthy reference subject. These findings support the hypothesis of PLT depletion in chronic HD subjects due to frequent PLT activation and/or increased urea concentrations.