Enhanced platelet apoptosis in chronic uremic patients

Indoxyl sulfate impairs in vitro erythropoiesis by triggering apoptosis and senescence

Anemia is a major complication in over 50% of chronic kidney disease (CKD) patients. One of the main causes of anemia in CKD is the reduction of erythropoietin (EPO) synthesis from renal tubular cells. Therefore, first-line treatment of CKD is EPO administration; however, EPO unresponsiveness in several patients is frequently found. More undefined causes of anemia in CKD are under interest, especially uremic toxins, which are a group of solutes accumulated in CKD patients. The highly detectable protein-bound uremic toxin, indoxyl sulfate (IS) was investigated for its effects on in vitro erythropoiesis in this study. CD34+ hematopoietic stem cells were isolated from human umbilical cord blood and differentiated toward erythrocyte lineage for 14 days in various concentrations of IS (12.5, 25, 50, and 100 µg/mL). The effects of IS on cell proliferation, differentiation, apoptosis, and senescence were determined. Cell proliferation was investigated by manual cell counting. Cell surface marker expression was analyzed by flow cytometry. Wright's staining was performed to evaluate cell differentiation capacity. Apoptosis and senescence marker expression was measured using reverse transcription polymerase chain reaction (RT-PCR). TUNEL assay was performed to detect apoptotic DNA fragmentation. Our results demonstrated that IS reduced cell proliferation and impaired erythrocyte differentiation capacity. In addition, this study confirmed the effects of IS on cell apoptosis and senescence during erythropoietic differentiation. Therefore, the promotion of apoptosis and senescence might be one of the possible mechanisms caused by uremic toxin accumulation leading to anemia in CKD patients.

Association of Platelet Desialylation and Circulating Follicular Helper T Cells in Patients With Thrombocytopenia

Thrombocytopenia is a multifactorial condition that frequently involves concomitant defects in platelet production and clearance. The physiopathology of low platelet count in thrombocytopenia remains unclear. Sialylation on platelet membrane glycoprotein and follicular helper T cells (TFHs) are thought to be the novel platelet clearance pathways. The aim of this study was to clarify the roles of platelet desialylation and circulating TFHs in patients with immune thrombocytopenia (ITP) and non-ITP thrombocytopenia. We enrolled 190 patients with ITP and 94 patients with non-ITP related thrombocytopenia including case of aplastic anemia (AA) and myelodysplastic syndromes (MDS). One hundred and ten healthy volunteers were included as controls. We found significantly increased desialylated platelets in patients with ITP or thrombocytopenia in the context of AA and MDS. Platelet desialylation was negatively correlated with platelet count. Meanwhile, the circulating TFH levels in patients with thrombocytopenia were significantly higher than those of normal controls, and were positively correlated with desialylated platelet levels. Moreover, TFHs-related chemokine CXCL13 and apoptotic platelet levels were abnormally high in ITP patients. The upregulation of pro-apoptotic proteins and the activation of the MAPK/mTOR pathway were observed in the same cohort. These findings suggested that platelet desialylation and circulating TFHs may become the potential biomarkers for evaluating the disease process associated with thrombocytopenia in patients with ITP and non-ITP.

Abdominal hemorrhage after peritoneal dialysis catheter insertion: A rare cause of luteal rupture: A case report

BACKGROUND

Abdominal hemorrhage is a complication of peritoneal dialysis catheter (PDC) insertion that cannot be neglected, and its causes are mainly related to surgical injury. This article reports a case of massive abdominal hemorrhage that was caused by a rare rupture of corpus luteum shortly after PDC during the initiation of peritoneal dialysis (PD) insertion.

CASE SUMMARY

A 37-year-old woman was surgically placed a Tenckhoff catheter because of end-stage renal disease. On the third postoperative day, the color of the abdominal drainage fluid was pink, and deepened gradually. It turned pale after initiating conservative treatment. On the tenth postoperative day, the color of the abdominal drainage fluid suddenly turned dark red, and the color progressively deepened. The patient’s hemoglobin dropped from 88 g/L to 57 g/L. Abdominal computed tomography (CT) indicated abdominal effusion and a high-density shadow in the abdominal cavity. The surgeon performed a laparotomy and found that the corpus luteum had ruptured on the right side and a left ovarian blood body had formed. The gynecologist repaired the ovary and performed a bilateral oophoroplasty. After the operation, the patient stopped bleeding and hemodialysis was temporarily stopped. PD was resumed after half a month. The patient’s condition improved, and she was discharged 14 d after the laparotomy.

CONCLUSION

If abdominal hemorrhage occurs in women of childbearing age after PDC insertion, luteal rupture should be considered as the cause.

Platelet Function in CKD: A Systematic Review and Meta-Analysis

BACKGROUND

Patients with CKD are at high risk for thrombotic and hemorrhagic complications. Abnormalities in platelet function are central to these complications, but reports on platelet function in relation to CKD are conflicting, and vary from decreased platelet reactivity to normal or increased platelet responsiveness. The direct effects of uremic toxins on platelet function have been described, with variable findings.

METHODS

To help clarify how CKD affects platelet function, we conducted a systematic review and meta-analysis of platelet activity in CKD, with a focus on nondialysis-induced effects. We also performed an extensive literature search for the effects of individual uremic toxins on platelet function.

RESULTS

We included 73 studies in the systematic review to assess CKD's overall effect on platelet function in patients; 11 of them described CKD's effect on ex vivo platelet aggregation and were included in the meta-analysis. Although findings on platelet abnormalities in CKD are inconsistent, bleeding time was mostly prolonged and platelet adhesion mainly reduced. Also, the meta-analysis revealed maximal platelet aggregation was significantly reduced in patients with CKD upon collagen stimulation. We also found that relatively few uremic toxins have been examined for direct effects on platelets ex vivo; ex vivo analyses had varying methods and results, revealing both platelet-stimulatory and inhibitory effects. However, eight of the 12 uremic toxins tested in animal models mostly induced prothrombotic effects.

CONCLUSIONS

Overall, most studies report impaired function of platelets from patients with CKD. Still, a substantial number of studies find platelet function to be unchanged or even enhanced. Further investigation of platelet reactivity in CKD, especially during different CKD stages, is warranted.

Bisphenol AF elevates procoagulant platelets by inducing necroptosis via RIPK1-inflammasome axis

Bisphenol AF, an analogue of Bisphenol A, is an important raw material used in the production of plastic and rubber substances like plastic bottles and containers, toys, and medical supplies. Increased contamination of air, water, dust, and food with BPA/BPAF, poses an enormous threat to humans, globally. BPAF/BPA are endocrine-disrupting chemicals that mimic estrogen hormone, thus increasing the risks of various metabolic and chronic disorders. Exposure of human blood cells to BPA/BPAF induces oxidative stress and genotoxicity. However, its effects on platelets, which play central roles in hemostasis and thrombosis, are not well-documented. In this study, we demonstrate that BPAF induces RIPK1-inflammasome axis-mediated necroptosis in platelets, increasing procoagulant platelet levels in vivo and in vitro. We also show that BPAF-induced rise in procoagulant platelets worsens pulmonary thromboembolism in vivo. The elevated procoagulant platelets are shown to increase platelet-neutrophil/monocyte aggregates that mediate pathogenesis of CVD, thrombosis, and chronic inflammatory diseases. Our results demonstrate the toxic effects of BPAF on platelets and how it propagates the clinical complications by elevating procoagulant platelet numbers. Altogether, our study sends a cautionary message against extensive use of BPAF in the plastic and rubber industries, resulting in frequent human exposure to it, thus endangering platelet functions.

Pediatric Endoscopy and High-risk Patients: A Clinical Report From the NASPGHAN Endoscopy Committee

Pediatric gastrointestinal endoscopy has been established as safe and effective for diagnosis and management of many pediatric gastrointestinal diseases. Nevertheless, certain patient and procedure factors should be recognized that increase the risk of intra- and/or postprocedural adverse events (AEs). AEs associated with endoscopic procedures can broadly be categorized as involving sedation-related physiological changes, bleeding, perforation, and infection. Factors which may increase patient risk for such AEs include but are not limited to, cardiopulmonary diseases, anatomical airway or craniofacial abnormalities, compromised intestinal luminal wall integrity, coagulopathies, and compromised immune systems. Examples of high-risk patients include patients with congenital heart disease, craniofacial abnormalities, connective tissues diseases, inflammatory bowel disease, and children undergoing treatment for cancer. This clinical report is intended to help guide clinicians stratify patient risks and employ clinical practices that may minimize AEs during and after endoscopy. These include use of CO2 insufflation, endoscopic techniques for maneuvers such as biopsies, and endoscope loop-reduction to mitigate the risk of such complications such as bleeding and intestinal perforation. Endoscopic infection risk and guidance regarding periprocedural antibiotics are also discussed.

Para-tertiary butyl catechol (PTBC), an industrial antioxidant induces human platelet apoptosis

The catecholic derivative para-tertiary butyl catechol (PTBC) is a conventional antioxidant and polymerization inhibitor, which exhibits melanocytotoxic effects and contact dermatitis often leading to occupational leucoderma or vitiligo. Although numerous industrial workers will be in constant exposure to PTBC and its chances of getting entry into blood are most expected, its effect on blood components is still undisclosed. As platelets play a prominent role in dermatitis, inflammation, and immunity, in this study we have evaluated the effect of PTBC on human platelets in vitro. Exposure of platelets to PTBC showed increased reactive oxygen species (ROS), intracellular calcium, cardiolipin oxidation, mitochondrial permeability transition pore (MPTP) formation, activation of caspases, phosphatidylserine (PS) externalization and decreased mitochondrial membrane potential. In addition, there was a significant decrease in cellular glutathione level, increased γ-glutamyltransferase (GGT) activity and cell death. These findings demonstrate that PTBC could induce toxic effects on blood components, which is often ignored field of research. Since dermal exposure of humans to toxic chemicals covers an important issue in various industries, there is a need of such work to understand and update the long-term toxicities induced by PTBC usage in industrial sectors and public domain.

Measurement and Clinical Significance of Biomarkers of Oxidative Stress in Humans

Oxidative stress is the result of the imbalance between reactive oxygen species (ROS) formation and enzymatic and nonenzymatic antioxidants. Biomarkers of oxidative stress are relevant in the evaluation of the disease status and of the health-enhancing effects of antioxidants. We aim to discuss the major methodological bias of methods used for the evaluation of oxidative stress in humans. There is a lack of consensus concerning the validation, standardization, and reproducibility of methods for the measurement of the following: (1) ROS in leukocytes and platelets by flow cytometry, (2) markers based on ROS-induced modifications of lipids, DNA, and proteins, (3) enzymatic players of redox status, and (4) total antioxidant capacity of human body fluids. It has been suggested that the bias of each method could be overcome by using indexes of oxidative stress that include more than one marker. However, the choice of the markers considered in the global index should be dictated by the aim of the study and its design, as well as by the clinical relevance in the selected subjects. In conclusion, the clinical significance of biomarkers of oxidative stress in humans must come from a critical analysis of the markers that should give an overall index of redox status in particular conditions.

The Biology of Hemodialysis Vascular Access Failure

Arteriovenous fistulas (AVFs) are essential for patients and clinicians faced with end-stage renal disease (ESRD). While this method of vascular access for hemodialysis is preferred to others due to its reduced rate of infection and complications, they are plagued by intimal hyperplasia. The pathogenesis of intimal hyperplasia and subsequent thrombosis is brought on by uremia, hypoxia, and shear stress. These forces upregulate inflammatory and proliferative cytokines acting on leukocytes, fibroblasts, smooth muscle cells, and platelets. This activation begins initially with the progression of uremia, which induces platelet dysfunction and primes the body for an inflammatory response. The vasculature subsequently undergoes changes in oxygenation and shear stress during AVF creation. This propagates a strong inflammatory response in the vessel leading to cellular proliferation. This combined response is then further subjected to the stressors of cannulation and dialysis, eventually leading to stenosis and thrombosis. This review aims to help interventional radiologists understand the biological changes and pathogenesis of access failure.

Platelet apoptosis in patients with acute coronary syndromes

Platelet apoptosis occurs commonly under various conditions such as physical and chemical stimuli. Acute coronary syndrome (ACS), one of most important cardiovascular and cerebrovascular diseases, severely threats people's health and is usually accompanied with various complications especially bleeding. There might be platelet apoptosis in ACS, which might be responsible for the complication of bleeding. The objective of the present study was to explore whether there were apoptotic platelets in ACS patients. Vein blood was drawn from eleven ACS patients and eleven health people. Platelet-rich plasma was prepared and subjected to apoptotic events analysis including increased expression of pro-apoptotic proteins and decreased expression of anti-apoptotic proteins, exposure of phosphatidylserine (PS), mitochondrial inner membrane potential depolarization and caspase-3 activation by Western blot and flow cytometry. In addition, washed platelets from the normal people were prepared and treated with the platelet-poor plasma (PPP) of the ACS patients, and were further examined apoptotic cascades. Paired Student's t test was used in the data comparisons. There were more platelets with depolarized mitochondrial inner membrane potential in the ACS patients than those of the health donors. Levels of Bax and Bak increased, while expression of Bcl-2 and Bcl-XL decreased in platelets from ACS patients. Caspase-3 activation was observed in platelets from the patients with ACS. Interestingly, there were significant differences in PS exposure between the platelets from the ACS patients and the normal controls. Furthermore, apoptotic events were observed in the normal platelets incubated with PPP from the ACS patients. In addition, pretreatment of healthy platelets with anti-oxidants N-acetyl cysteine (NAC) or dithiothreitol (DTT) significantly reduced ACS patients-derived PPP-induced platelet apoptosis. Platelets from the ACS patients are incurred apoptosis. Antioxidants NAC or DTT can reduce ACS patients-derived PPP-induced platelet apoptosis in vitro.

Aging and uremia: Is there cellular and molecular crossover?

Many observers have noted that the morphological changes that occur in chronic kidney disease (CKD) patients resemble those seen in the geriatric population, with strikingly similar morbidity and mortality profiles and rates of frailty in the two groups, and shared characteristics at a pathophysiological level especially in respect to the changes seen in their vascular and immune systems. However, whilst much has been documented about the shared physical characteristics of aging and uremia, the molecular and cellular similarities between the two have received less attention. In order to bridge this perceived gap we have reviewed published research concerning the common molecular processes seen in aging subjects and CKD patients, with specific attention to altered proteostasis, mitochondrial dysfunction, post-translational protein modification, and senescence and telomere attrition. We have also sought to illustrate how the cell death and survival pathways apoptosis, necroptosis and autophagy are closely interrelated, and how an understanding of these overlapping pathways is helpful in order to appreciate the shared molecular basis behind the pathophysiology of aging and uremia. This analysis revealed many common molecular characteristics and showed similar patterns of cellular dysfunction. We conclude that the accelerated aging seen in patients with CKD is underpinned at the molecular level, and that a greater understanding of these molecular processes might eventually lead to new much needed therapeutic strategies of benefit to patients with renal disease.