Subject(s)
Factor XII , Protein Binding , Humans , Factor XII/metabolism , Factor XII/genetics , Blood Coagulation , Animals , Binding SitesABSTRACT
It is well-established that dysfunction of megalin-mediated albumin endocytosis by proximal tubule epithelial cells (PTECs) and the activation of the Renin-Angiotensin System (RAS) play significant roles in the development of Diabetic Kidney Disease (DKD). However, the precise correlation between these factors still requires further investigation. In this study, we aimed to elucidate the potential role of angiotensin II (Ang II), a known effector of RAS, as the mediator of albumin endocytosis dysfunction induced by high glucose (HG) in PTECs. To achieve this, we utilized LLC-PK1 and HK-2 cells, which are well-established in vitro models of PTECs. Using albumin-FITC or DQ-albumin as tracers, we observed that incubation of LLC-PK1 and HK-2 cells with HG (25 mM for 48 h) significantly reduced canonical receptor-mediated albumin endocytosis, primarily due to the decrease in megalin expression. HG increased the concentration of Ang II in the LLC-PK1 cell supernatant, a phenomenon associated with an increase in angiotensin-converting enzyme (ACE) expression and a decrease in prolyl carboxypeptidase (PRCP) expression. ACE type 2 (ACE2) expression remained unchanged. To investigate the potential impact of Ang II on HG effects, the cells were co-incubated with angiotensin receptor inhibitors. Only co-incubation with 10-7 M losartan (an antagonist for type 1 angiotensin receptor, AT1R) attenuated the inhibitory effect of HG on albumin endocytosis, as well as megalin expression. Our findings contribute to understanding the genesis of tubular albuminuria observed in the early stages of DKD, which involves the activation of the Ang II/AT1R axis by HG.
Subject(s)
Albumins , Angiotensin II , Endocytosis , Epithelial Cells , Glucose , Kidney Tubules, Proximal , Receptor, Angiotensin, Type 1 , Endocytosis/drug effects , Kidney Tubules, Proximal/metabolism , Kidney Tubules, Proximal/pathology , Kidney Tubules, Proximal/drug effects , Angiotensin II/pharmacology , Glucose/metabolism , Glucose/pharmacology , Receptor, Angiotensin, Type 1/metabolism , Animals , Epithelial Cells/metabolism , Epithelial Cells/drug effects , Epithelial Cells/pathology , Humans , Albumins/metabolism , Swine , Diabetic Nephropathies/metabolism , Diabetic Nephropathies/pathology , Low Density Lipoprotein Receptor-Related Protein-2/metabolism , Renin-Angiotensin System/drug effects , Signal Transduction/drug effects , Cell Line , Losartan/pharmacologyABSTRACT
Tubular proteinuria is a common feature in COVID-19 patients, even in the absence of established acute kidney injury. SARS-CoV-2 spike protein (S protein) was shown to inhibit megalin-mediated albumin endocytosis in proximal tubule epithelial cells (PTECs). Angiotensin-converting enzyme type 2 (ACE2) was not directly involved. Since Toll-like receptor 4 (TLR4) mediates S protein effects in various cell types, we hypothesized that TLR4 could be participating in the inhibition of PTECs albumin endocytosis elicited by S protein. Two different models of PTECs were used: porcine proximal tubule cells (LLC-PK1) and human embryonic kidney cells (HEK-293). S protein reduced Akt activity by specifically inhibiting of threonine 308 (Thr308) phosphorylation, a process mediated by phosphoinositide-dependent kinase 1 (PDK1). GSK2334470, a PDK1 inhibitor, decreased albumin endocytosis and megalin expression mimicking S protein effect. S protein did not change total TLR4 expression but decreased its surface expression. LPS-RS, a TLR4 antagonist, also counteracted the effects of the S protein on Akt phosphorylation at Thr308, albumin endocytosis, and megalin expression. Conversely, these effects of the S protein were replicated by LPS, an agonist of TLR4. Incubation of PTECs with a pseudovirus containing S protein inhibited albumin endocytosis. Null or VSV-G pseudovirus, used as control, had no effect. LPS-RS prevented the inhibitory impact of pseudovirus containing the S protein on albumin endocytosis but had no influence on virus internalization. Our findings demonstrate that the inhibitory effect of the S protein on albumin endocytosis in PTECs is mediated through TLR4, resulting from a reduction in megalin expression.
Subject(s)
Endocytosis , Kidney Tubules, Proximal , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Toll-Like Receptor 4 , Toll-Like Receptor 4/metabolism , Endocytosis/drug effects , Humans , Kidney Tubules, Proximal/metabolism , Kidney Tubules, Proximal/virology , Animals , Spike Glycoprotein, Coronavirus/metabolism , SARS-CoV-2/metabolism , HEK293 Cells , Swine , Proto-Oncogene Proteins c-akt/metabolism , Phosphorylation , COVID-19/metabolism , COVID-19/virology , COVID-19/pathology , Albumins/metabolism , LLC-PK1 Cells , Epithelial Cells/metabolism , Epithelial Cells/virologyABSTRACT
The essence of difference between hemostasis and thrombosis is that the clotting reaction is a highly fine-tuned process. Vascular protein disulfide isomerase (PDI) represents a critical mechanism regulating the functions of hemostatic proteins. Herein we show that histidine-rich glycoprotein (HRG) is a substrate of PDI. Reduction of HRG by PDI enhances the procoagulant and anticoagulant activities of HRG by neutralization of endothelial heparan sulfate (HS) and inhibition of factor XII (FXIIa) activity, respectively. Murine HRG deficiency (Hrg-/-) leads to delayed onset but enhanced formation of thrombus compared to WT. However, in the combined FXII deficiency (F12-/-) and HRG deficiency (by siRNA or Hrg-/-), there is further thrombosis reduction compared to F12-/- alone, confirming HRG's procoagulant activity independent of FXIIa. Mutation of target disulfides of PDI leads to a gain-of-function mutant of HRG that promotes its activities during coagulation. Thus, PDI-HRG pathway fine-tunes thrombosis by promoting its rapid initiation via neutralization of HS and preventing excessive propagation via inhibition of FXIIa.
Subject(s)
Protein Disulfide-Isomerases , Proteins , Thrombosis , Animals , Mice , Disulfides , Factor XII/metabolism , Heparitin Sulfate , Protein Disulfide-Isomerases/genetics , Proteins/metabolism , Thrombosis/genetics , Thrombosis/metabolismABSTRACT
Purpose: To report a patient with severe hemophilia A who received intravitreal antivascular endothelial growth factor (anti-VEGF) for exudative age-related macular degeneration (AMD). Methods: A case and its findings were analyzed. A systematic literature was performed. Results: A patient with severe hemophilia A received intravitreal anti-VEGF for exudative AMD, after which he developed a severe subconjunctival hemorrhage requiring hemostatic intervention. The effects of anti-VEGF in patients with preexisting blood-clotting disorders, such as classic hemophilia, have not been widely reported in the current literature. Conclusions: This case illustrates that precautions must be taken when performing ocular procedures on patients with serious hemostasis disorders.
Subject(s)
Glycoproteins , Thrombosis , Humans , Hemorrhage/etiology , Thrombosis/drug therapy , Thrombosis/etiologyABSTRACT
Malaria is a parasitic disease of global health significance and a leading cause of death in children living in endemic regions. Although various Plasmodium species are responsible for the disease, Plasmodium falciparum infection accounts for most severe cases of the disease in humans. The mechanisms of cerebral malaria pathogenesis have been studied extensively in humans and animal malaria models; however, it is far from being fully understood. Recent discoveries indicate a potential role of bradykinin and the kallikrein kinin system in the pathogenesis of cerebral malaria. The aim of this review is to highlight how bradykinin is formed in cerebral malaria and how it may impact cerebral blood-brain barrier function. Areas of interest in this context include Plasmodium parasite enzymes that directly generate bradykinin from plasma protein precursors, cytoadhesion of P. falciparum infected red blood cells to brain endothelial cells, and endothelial cell blood-brain barrier disruption.
Subject(s)
Bradykinin , Malaria, Cerebral , Malaria, Falciparum , Animals , Humans , Brain , Endothelial CellsSubject(s)
Blood Coagulation Disorders , Liver Diseases , Thrombosis , Humans , Hemostasis/physiologyABSTRACT
BACKGROUND: We examined how prekallikrein (PK) activation on human microvascular endothelial cells (HMVECs) is regulated by the ambient concentration of C1 inhibitor (C1INH) and prolylcarboxypeptidase (PRCP). OBJECTIVE: We sought to examine the specificity of PK activation on HMVECs by PRCP and the role of C1INH to regulate it, high-molecular-weight kininogen (HK) cleavage, and bradykinin (BK) liberation. METHODS: Investigations were performed on cultured HMVECs. Immunofluorescence, enzymatic activity assays, immunoblots, small interfering RNA knockdowns, and cell transfections were used to perform these studies. RESULTS: Cultured HMVECs constitutively coexpressed PK, HK, C1INH, and PRCP. PK activation on HMVECs was modulated by the ambient C1INH concentration. In the absence of C1INH, forming PKa on HMVECs cleaved 120-kDa HK completely to a 65-kDa H-chain and a 46-kDa L-chain in 60 minutes. In the presence of 2 µM C1INH, only 50% of the HK became cleaved. C1INH concentrations (0.0-2.5 µM) decreased but did not abolish BK liberated from HK by activated PK. Factor XII did not activate when incubated with HMVECs alone for 1 hour. However, if incubated in the presence of HK and PK, factor XII became activated. The specificity of PK activation on HMVECs by PRCP was shown by several inhibitors to each enzyme. Furthermore, PRCP small interfering RNA knockdowns magnified C1INH inhibitory activity on PK activation, and PRCP transfections reduced C1INH inhibition at any given concentration. CONCLUSIONS: These combined studies indicated that on HMVECs, PK activation and HK cleavage to liberate BK were modulated by the local concentrations of C1INH and PRCP.
Subject(s)
Factor XII , Prekallikrein , Humans , Endothelial Cells , Bradykinin/pharmacology , Kininogen, High-Molecular-Weight , RNA, Small Interfering/geneticsABSTRACT
The Kinin 2022 meeting took place at the Imperial Palace, Annecy, France, from 5-8 June 2022 [...].
ABSTRACT
Elevated neutrophil-to-lymphocyte ratio (NLR) in patients who undergo elective vascular surgery (EVS) have increased mortality independent of perioperative surgical outcome. To understand why high NLR is associated with higher mortality, we investigated neutrophil and lymphocyte transcriptome expression in patients undergoing EVS. Blood samples were collected from patients undergoing EVS and healthy donors for NLR calculation. RNA samples were isolated from patients' neutrophils and lymphocytes and divided into NLR_Low (<3) and NLR_High (≥3) groups (n = 6 each). Paired samples with the highest RNA integrity number (mean = 9.8 ± 0.4) were sequenced and analyzed for differential expression. Normalized data were inputted for downstream analysis using iPathwayGuide (AdvaitaBio) and gene set enrichment analysis using GenePattern and MSigDB (Broad Institute). There was no clinical difference between the patient groups with regard to clinical diagnosis, age, sex, history of hypertension, lipid abnormalities, diabetes mellitus, smoking, or statin use. The mean NLR was 4.37 ± 0.27 SEM in the NLR_High and 1.88 ± 0.16 for the NLR_Low groups. Significantly differentially expressed gene sets identified in the RNA sequence data were enriched highly (P = 1E-24) in the humoral immunity and complement systems. Neutrophils from NLR_High patients downregulated complement genes (C1QA, C1QB, C1QC, C1S, C2, CR2, C3AR1, C3, C8G, and C9 and complement regulatory genes CD59, SERPING1, C4BPA, CFH, and CFI). Downregulation of gene expressions of humoral immunity and complement within the neutrophils are associated with elevated NLR. It remains to be determined whether and how these changes contribute to increased late mortality previously observed in patients undergoing EVS.
Subject(s)
Lymphocytes , Neutrophils , Humans , Vascular Surgical Procedures , Elective Surgical ProceduresABSTRACT
Since the outbreak of COVID-19 disease, a bidirectional interaction between kidney disease and the progression of COVID-19 has been demonstrated. Kidney disease is an independent risk factor for mortality of patients with COVID-19 as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leading to the development of acute kidney injury (AKI) and chronic kidney disease (CKD) in patients with COVID-19. However, the detection of kidney damage in patients with COVID-19 may not occur until an advanced stage based on the current clinical blood and urinary examinations. Some studies have pointed out the development of subclinical acute kidney injury (subAKI) syndrome with COVID-19. This syndrome is characterized by significant tubule interstitial injury without changes in the estimated glomerular filtration rate. Despite the complexity of the mechanism(s) underlying the development of subAKI, the involvement of changes in the protein endocytosis machinery in proximal tubule (PT) epithelial cells (PTECs) has been proposed. This paper focuses on the data relating to subAKI and COVID-19 and the role of PTECs and their protein endocytosis machinery in its pathogenesis.
Subject(s)
Acute Kidney Injury , COVID-19 , Renal Insufficiency, Chronic , Humans , COVID-19/complications , SARS-CoV-2 , Acute Kidney Injury/metabolism , Renal Insufficiency, Chronic/metabolism , Kidney Tubules, Proximal/metabolismABSTRACT
As per the classical view of the coagulation system, it functions solely in plasma to maintain hemostasis. An experimental approach modeling vascular reconstitution was used to show that vascular endothelial cells (ECs) endogenously synthesize coagulation factors during angiogenesis. Intracellular thrombin generated from this synthesis promotes the mitotic function of vascular endothelial cell growth factor A (VEGF-A). The thrombin concurrently cleaves C5a from EC-synthesized complement component C5 and unmasks the tethered ligand for EC-expressed protease-activated receptor 4 (PAR4). The two ligands jointly trigger EC C5a receptor-1 (C5ar1) and PAR4 signaling, which together promote VEGF receptor 2 growth signaling. C5ar1 is functionally associated with PAR4, enabling C5a or thrombin to elicit Gαi and/or Gαq signaling. EC coagulation factor and EC complement component synthesis concurrently down-regulate with contact inhibition. The connection of these processes with VEGF receptor 2 signaling provides new insights into mechanisms underlying angiogenesis. Knowledge of endogenous coagulation factor/complement component synthesis and joint PAR4/C5ar1 signaling could be applied to other cell types.
Subject(s)
Blood Coagulation Factors/biosynthesis , Endothelial Cells/metabolism , Neovascularization, Physiologic , Receptor, Anaphylatoxin C5a/metabolism , Receptors, Proteinase-Activated/metabolism , Signal Transduction , Animals , Blood Coagulation Factors/genetics , Female , Male , Mice , Mice, Knockout , Receptor, Anaphylatoxin C5a/genetics , Receptors, Proteinase-Activated/geneticsABSTRACT
Disseminated intravascular coagulation (DIC) is a rare complication of endovascular aortic repair, commonly associated with type I or type III endoleaks. DIC is also known as consumption coagulopathy because excessive thrombin formation and secondary fibrinolysis leads to consumption of coagulation factors with hyperfibrinolysis and activation of platelets, which can lead to excessive bleeding. We present the case of an 80-year-old woman who had undergone thoracic endovascular aortic repair for a type B aortic dissection that was complicated by a series of recurrent endoleak-induced DICs requiring multiple thoracic endovascular aortic repair extensions to cover the entire thoracoabdominal aorta. The DIC persisted despite the resolution of the endoleaks.
ABSTRACT
Extracellular vesicles (EV) have been implicated in diverse biological processes, including intracellular communication, transport of nucleic acids, and regulation of vascular function. Levels of EVs are elevated in cancer, and studies suggest that EV may stimulate thrombosis in patients with cancer through expression of tissue factor. However, limited data also implicate EV in the activation of the contact pathway of coagulation through activation of factor XII (FXII) to FXIIa. To better define the ability of EV to initiate contact activation, we compared the ability of EV derived from different cancer cell lines to activate FXII. EV from all cell lines activated FXII, with those derived from pancreatic and lung cancer cell lines demonstrating the most potent activity. Concordant with the activation of FXII, EV induced the cleavage of high molecular weight kininogen (HK) to cleaved kininogen. We also observed that EVs from patients with cancer stimulated FXII activation and HK cleavage. To define the mechanisms of FXII activation by EV, EV were treated with calf intestinal alkaline phosphatase or Escherichia coli exopolyphosphatase to degrade polyphosphate; this treatment blocked binding of FXII to EVs and the ability of EV to mediate FXII activation. In vivo, EV induced pulmonary thrombosis in wild-type mice, with protection conferred by a deficiency in FXII, HK, or prekallikrein. Moreover, pretreatment of EVs with calf intestinal alkaline phosphatase inhibited their prothrombotic effect. These results indicate that polyphosphate mediates the binding of contact factors to EV and that EV-associated polyphosphate may contribute to the prothrombotic effects of EV in cancer.
Subject(s)
Extracellular Vesicles , Neoplasms , Animals , Factor XII , Factor XIIa , Humans , Mice , Polyphosphates , PrekallikreinABSTRACT
OBJECTIVE: Management of carotid artery stenosis (CAS) remains controversial and proper patient selection critical. Elevated neutrophil to lymphocyte ratio (NLR) has been associated with poor outcomes after vascular procedures. The effect of NLR on outcomes after carotid endarterectomy (CEA) in asymptomatic and symptomatic patients is assessed. MATERIALS AND METHODS: A retrospective review was conducted of all patients between 2010 and 2018 with carotid stenosis >70% as defined by CREST 2 criteria. A total of 922 patients were identified, of whom 806 were treated with CEA and 116 non-operatively with best medical therapy (BMT). Of patients undergoing CEA, 401 patients (290 asymptomatic [aCEA], 111 symptomatic [sCEA]) also had an available NLR calculated from a complete blood count with differential. All patients treated with BMT were asymptomatic and had a baseline NLR available. Kaplan-Meier analysis assessed composite ipsilateral stroke or death over 3 years. RESULTS: In sCEA group, the 3-year composite stroke/death rates did not differ between NLR < 3.0 (22.9%) vs NLR > 3.0 (38.1%) (P=.10). In aCEA group, patients with a baseline NLR >3.0 had an increased risk of 3-year stroke/death (42.6%) compared to both those with NLR <3.0 (9.3%, P<.0001) and those treated with BMT (23.6%, P=.003). In patients with NLR <3.0, aCEA showed a superior benefit over BMT with regard to stroke or death (9.3% vs. 26.2%, P=.02). However, in patients with NLR >3.0, there was no longer a benefit to prophylactic CEA compared to BMT (42.6% vs. 22.2%, P=.05). Multivariable analysis identified NLR >3.0 (HR, 3.23; 95% CI, 1.93-5.42; P<.001) and congestive heart failure (HR, 2.18; 95% CI, 1.33-3.58; P=.002) as independent risk factors for stroke/death in patients with asymptomatic carotid artery stenosis. CONCLUSIONS: NLR >3.0 is associated with an increased risk of late stroke/death after prophylactic CEA for asymptomatic carotid artery stenosis, with benefits not superior to BMT. NLR may be used to help with selecting asymptomatic patients for CEA. The effect of NLR and outcomes in symptomatic patients requires further study. Better understanding of the mechanism(s) for NLR elevation and medical intervention strategies are needed to modulate outcome risk in these patients.
Subject(s)
Carotid Stenosis , Endarterectomy, Carotid , Lymphocytes , Neutrophils , Carotid Stenosis/blood , Carotid Stenosis/surgery , Endarterectomy, Carotid/adverse effects , Humans , Retrospective Studies , Risk Factors , Treatment OutcomeABSTRACT
BACKGROUND: An elevated neutrophil-lymphocyte ratio (NLR) is a biomarker associated with adverse outcomes after cardiovascular surgery. This study evaluates the association of preoperative NLR with clinical outcomes after peripheral vascular intervention (PVI) of the femoropopliteal segments. METHODS: A retrospective review identified 488 patients who underwent percutaneous interventions of femoropopliteal arteries between 2011 and 2018 and had a pre-procedural complete blood count with differential with normal white blood cell count within 30 days prior to intervention. Amputation-free survival (AFS), survival, and freedom from major amputation were assessed using Kaplan-Meier methods. Cohorts of patients with NLR <3 (Low), 3-4 (Mid), and >4 (High) were compared using univariate and multivariable statistical models. In these analyses NLR was analyzed as a continuous variable to correlate with clinical outcomes. RESULTS: Mean age was 71.7±12.8 years and males constituted 55.5%. The majority of patients presented with chronic limb threatening ischemia (CLTI, 78.5%). Increasing NLR was correlated with increasing rates of comorbidities, except for smoking history. The 30-day mortality rates increased with increasing NLR: 1.4%, 4.3%, and 7.0% for low (<3), mid (3-4) and high (>4) NLR groups, respectively (P=0.005). Patients with a lower pre-operative NLR achieved significantly greater amputation-free survival at 4-year follow-up: low NLR, 65.5%; mid NLR, 37.5%; and high NLR, 17.6% (P<0.0001). By multivariable analysis, increasing NLR, advanced age, CLTI, and dialysis-dependent renal failure reduced AFS. CONCLUSIONS: Elevated NLR is an independent predictor of decreased AFS following percutaneous interventions of femoropopliteal segments. Further research on identification and modulation of risk factors for high NLR are warranted.
Subject(s)
Endovascular Procedures , Peripheral Arterial Disease , Aged , Aged, 80 and over , Amputation, Surgical , Endovascular Procedures/adverse effects , Humans , Ischemia/diagnosis , Ischemia/surgery , Limb Salvage , Lymphocytes , Male , Middle Aged , Neutrophils , Peripheral Arterial Disease/diagnosis , Peripheral Arterial Disease/surgery , Retrospective Studies , Risk Factors , Treatment OutcomeABSTRACT
A previously hemostatically asymptomatic patient with common variable hypogammaglobulinemia was given everolimus to prevent growth of her liver. Within several months, the patient developed a severe bleeding disorder. The bleeding was due to fibrin polymerization defect that upon sequencing was shown to be dysfibrinogenemia Krakow III. Elimination of the mTor inhibitor ameliorated the clinical bleeding state.
ABSTRACT
Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder managed with plasma exchange (PLEX) and steroids. Addition of rituximab (RTX) to initial disease treatment has been shown to lower future relapse rates. Information as to whether upfront cyclophosphamide (CTX) treatment is helpful in reducing relapse is not known. Methods: In a retrospective cohort study, we identified all patients at our institution diagnosed with iTTP between 2010 and 2019. We analyzed outcomes of cumulative incidence of relapse (CIR) and duration of remission. Results: Thirty Nine patients were studied. Group A (n = 10) included patients who received upfront PLEX and steroids alone, and Group B (n = 28) included those who received either upfront RTX (n = 23) or CTX (n = 5) in addition to PLEX and steroids. The 2-year CIR was 50% in Group A and 27.7% in Group B, with a median duration of remission of 43.6 months vs. 108.3 months, respectively (p = 0.04). Group A was associated with a HR=8.7 (95% CI: 1.27, 59.45), p = 0.027 for duration of remission. There was no significant difference between CTX and RTX in both outcomes of CIR and duration of remission. We observed a potential impact on remission duration based on the presenting absolute neutrophil count (HR = 0.74, 95% CI: 0.58, 0.96) and serum creatinine (HR = 1.42, 95% CI: 1.03, 1.94). Conclusion: There was no significant difference in iTTP relapse outcomes between upfront RTX and CTX. Absolute neutrophil count and serum creatinine may have a role in predicting relapse. Larger, prospective studies are needed to evaluate these findings.