Filter clotting with continuous renal replacement therapy in COVID-19.

Coronavirus disease 2019 (COVID-19) appears to be associated with increased arterial and venous thromboembolic disease. These presumed abnormalities in hemostasis have been associated with filter clotting during continuous renal replacement therapy (CRRT). We aimed to characterize the burden of CRRT filter clotting in COVID-19 infection and to describe a CRRT anticoagulation protocol that used anti-factor Xa levels for systemic heparin dosing. Multi-center study of consecutive patients with COVID-19 receiving CRRT. Primary outcome was CRRT filter loss. Sixty-five patients were analyzed, including 17 using an anti-factor Xa protocol to guide systemic heparin dosing. Fifty-four out of 65 patients (83%) lost at least one filter. Median first filter survival time was 6.5 [2.5, 33.5] h. There was no difference in first or second filter loss between the anti-Xa protocol and standard of care anticoagulation groups, however fewer patients lost their third filter in the protocolized group (55% vs. 93%) resulting in a longer median third filter survival time (24 [15.1, 54.2] vs. 17.3 [9.5, 35.1] h, p = 0.04). The rate of CRRT filter loss is high in COVID-19 infection. An anticoagulation protocol using systemic unfractionated heparin, dosed by anti-factor Xa levels is reasonable approach to anticoagulation in this population.

Development of an electronic health record-based chronic kidney disease registry to promote population health management.

BACKGROUND: Electronic health record (EHR) based chronic kidney disease (CKD) registries are central to population health strategies to improve CKD care. In 2015, Partners Healthcare System (PHS), encompassing multiple academic and community hospitals and outpatient care facilities in Massachusetts, developed an EHR-based CKD registry to identify opportunities for quality improvement, defined as improvement on both process measures and outcomes measures associated with clinical care. METHODS: Patients are included in the registry based on the following criteria: 1) two estimated glomerular filtration rate (eGFR) results < 60 ml/min/1.73m2 separated by 90 days, including the most recent eGFR being < 60 ml/min/1.73m2; or 2) the most recent two urine protein values > 300 mg protein/g creatinine on either urine total protein/creatinine ratio or urine albumin/creatinine ratio; or 3) an EHR problem list diagnosis of end stage renal disease (ESRD). The registry categorizes patients by CKD stage and includes rates of annual testing for eGFR and proteinuria, blood pressure control, use of angiotensin converting enzyme inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs), nephrotoxic medication use, hepatitis B virus (HBV) immunization, vascular access placement, transplant status, CKD progression risk; number of outpatient nephrology visits, and hospitalizations. RESULTS: The CKD registry includes 60,503 patients and has revealed several opportunities for care improvement including 1) annual proteinuria testing performed for 17% (stage 3) and 31% (stage 4) of patients; 2) ACE-I/ARB used in 41% (stage 3) and 46% (stage 4) of patients; 3) nephrotoxic medications used among 23% of stage 4 patients; and 4) 89% of stage 4 patients lack HBV immunity. For advanced CKD patients there are opportunities to improve vascular access placement, transplant referrals and outpatient nephrology contact. CONCLUSIONS: A CKD registry can identify modifiable care gaps across the spectrum of CKD care and enable population health strategy implementation. No linkage to Social Security Death Master File or US Renal Data System (USRDS) databases limits our ability to track mortality and progression to ESRD.

Twin pregnancy and the risk of preeclampsia: bigger placenta or relative ischemia?

OBJECTIVE: Twin pregnancies are a risk factor for preeclampsia with a reported incidence of 2-3 times higher than singleton pregnancies. Soluble fms-like tyrosine kinase 1 (sFlt1), which is a circulating antiangiogenic molecule of placental origin, plays a central role in preeclampsia by antagonizing placental growth factor (PlGF) and vascular endothelial growth factor signaling in the maternal vasculature. Increased sFlt1 and the ratio sFlt1/free PlGF have been shown to antedate clinical signs in preeclampsia. Although the cause of the upregulated sFlt1 in preeclampsia still is not understood clearly, placental ischemia with accompanying hypoxia is thought to play an important role. We therefore hypothesized that the higher risk of preeclampsia in twin pregnancies results from high sFlt1 (or sFlt1/PlGF) and that the sFlt1 upregulation was due to either relative placental hypoxia and/or increased placental mass. STUDY DESIGN: Maternal serum samples and placentas from third-trimester twin and singleton pregnancies without preeclampsia were used. Serum samples were analyzed for levels of sFlt1 and free PlGF by enzyme-linked immunosorbent assay and reported as means (in nanograms per milliliter and picograms per milliliter, respectively). Placentas were weighed and examined for content of sFlt1 and PlGF messenger RNA (mRNA) by quantitative polymerase chain reaction and hypoxia inducible factor-1alpha (HIF-1alpha) protein by Western blot. RESULTS: Soluble Flt1 concentrations in twin pregnancy maternal serum were 2.2 times higher than those that were measured in singleton pregnancy maternal serum samples (30.98 +/- 9.78 ng/mL vs 14.14 +/- 9.35 ng/mL, respectively; P = .001). Free PlGF concentrations were not significantly different between twin and singleton maternal serum samples, but the mean sFlt1/PlGF ratio of twin pregnancy maternal serum samples was 2.2 times higher than the equivalent ratio in singleton pregnancy samples (197.58 +/- 126.86 ng/mL vs 89.91 +/- 70.63 ng/mL, respectively; P = .029). Quantitative polymerase chain reaction for sFlt1 and PlGF mRNA revealed no significant differences between the 2 study groups. Western blot analysis of placental samples for HIF-1alpha revealed a mean ratio HIF-1alpha/actin of 0.53 vs 0.87, for the twins vs singletons placental samples respectively (twins showed lower HIF-1alpha, not higher). The mean weights of twin and singleton placentas were 1246 vs 716 g, respectively (P < .001). Importantly, the placental weights correlated very well with the circulating sFlt1 levels (R(2) = .75). CONCLUSION: In twin pregnancies, circulating sFlt1 levels and sFlt1/PlGF ratios were twice as high as those in singleton pregnancies. The increased serum sFlt1 levels in twin pregnancies were not accompanied by any changes in the levels of sFlt1 mRNA and HIF-1alpha protein in the twin placentas but were correlated with increased placental weight. These findings suggest that the increased risk of preeclampsia in twin pregnancies may be due to increased placental mass that leads to increased circulating levels of sFlt1.

First trimester placental growth factor and soluble fms-like tyrosine kinase 1 and risk for preeclampsia.

An imbalance of pro- and antiangiogenic factors may lead to preeclampsia (PE). In this prospective nested case-control study, we investigated whether first trimester serum levels of placental growth factor (PlGF), a potent angiogenic factor, and its soluble inhibitor, soluble fms-like tyrosine kinase 1 (sFlt1), distinguished women who developed PE (n = 40) from those who developed gestational hypertension (n = 40), delivered a small for gestational age (SGA) newborn (n = 40), or completed a full term normal pregnancy (n = 80). Compared with controls, serum PlGF levels were lower among women who developed PE (23 +/- 24 pg/ml vs. 63 +/- 145 pg/ml; P < 0.01) or gestational hypertension (27 +/- 19 pg/ml; P = 0.03), or who delivered a SGA newborn (21 +/- 16 pg/ml; P < 0.01). In contrast, serum sFlt1 levels did not markedly differ between the groups: PE, 1048 +/- 657 pg/ml; gestational hypertension, 942 +/- 437 pg/ml; SGA newborns, 1011 +/- 479 pg/ml; and normal controls, 973 +/- 490 pg/ml. Multivariable analysis adjusting for potential confounders and serum sFlt1 levels demonstrated a 3.7-fold (95% confidence interval, 1.2-12.5) increase in risk for PE for every log unit decrease in serum levels of PlGF compared with controls. Analyses for gestational hypertension and SGA were not significant. Examined in tertiles, the risk for PE was increased 28.7-fold (95% confidence interval, 2.3-351.0) in the third (<12 pg/ml) compared with the first (>39 pg/ml) PlGF tertile. First trimester serum levels of PlGF and sFlt1 may identify women at high risk for PE.

Soluble erythropoietin receptor contributes to erythropoietin resistance in end-stage renal disease.

BACKGROUND: Erythropoietin is a growth factor commonly used to manage anemia in patients with chronic kidney disease. A significant clinical challenge is relative resistance to erythropoietin, which leads to use of successively higher erythropoietin doses, failure to achieve target hemoglobin levels, and increased risk of adverse outcomes. Erythropoietin acts through the erythropoietin receptor (EpoR) present in erythroblasts. Alternative mRNA splicing produces a soluble form of EpoR (sEpoR) found in human blood, however its role in anemia is not known. METHODS AND FINDINGS: Using archived serum samples obtained from subjects with end stage kidney disease we show that sEpoR is detectable as a 27kDa protein in the serum of dialysis patients, and that higher serum sEpoR levels correlate with increased erythropoietin requirements. Soluble EpoR inhibits erythropoietin mediated signal transducer and activator of transcription 5 (Stat5) phosphorylation in cell lines expressing EpoR. Importantly, we demonstrate that serum from patients with elevated sEpoR levels blocks this phosphorylation in ex vivo studies. Finally, we show that sEpoR is increased in the supernatant of a human erythroleukaemia cell line when stimulated by inflammatory mediators such as interleukin-6 and tumor necrosis factor alpha implying a link between inflammation and erythropoietin resistance. CONCLUSIONS: These observations suggest that sEpoR levels may contribute to erythropoietin resistance in end stage renal disease, and that sEpoR production may be mediated by pro-inflammatory cytokines.

Molecular mechanisms of preeclampsia.

Preeclampsia is a major cause of maternal, fetal and neonatal mortality worldwide. The mechanisms that initiate preeclampsia in humans have been elusive, but some parts of the puzzle have begun to come together. A key discovery in the field was the realization that its major phenotypes, such as hypertension and proteinuria, are due to excess circulating soluble fms-like tyrosine kinase-1 (sFlt-1, also referred to as sVEGFR-1). sFlt-1 is an endogenous anti-angiogenic protein that is made by the placenta and acts by neutralizing the pro-angiogenic proteins vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). More recently, soluble endoglin, another circulating anti-angiogenic protein was found to synergize with sFlt-1 and contribute to the pathogenesis of preeclampsia. Abnormalities in these circulating angiogenic proteins are not only present during clinical preeclampsia, but also antedate clinical symptoms by several weeks. This review will summarize our current understanding of the molecular mechanism of preeclampsia, with an emphasis on the recently characterized circulating anti-angiogenic proteins.

Protease activity of urokinase and tumor progression in a syngeneic mammary cancer model.

BACKGROUND: We and others have previously shown that plasminogen activators generate endogenous angiogenesis inhibitors and induce antiangiogenic activity. Here we assessed the effects of plasminogen activator overexpression on tumor progression in a syngeneic mammary cancer model. METHODS: Genes encoding murine tissue plasminogen activator (tPA), urokinase (uPA), and vector controls were stably transfected into 4T1 murine mammary cancer cells, and cell proliferation in vitro was analyzed. Cells were also implanted into female BALB/c mice (n = 12 per group), and tumor growth, lung metastases, and survival were compared. Tumor cell proliferation and microvessel formation were analyzed by immunohistochemistry using antibodies to proliferating cell nuclear antigen and CD31, respectively. 4T1 cells transfected with proteolytically inactive uPA mutants (A and B) were assayed for proliferation in vitro and tumor growth in vivo by using the same syngeneic model (eight to 10 mice per group). All statistical tests were two-sided. RESULTS: In vitro growth of uPA- and tPA-overexpressing and control 4T1 cells was similar. In vivo, however, inhibition of tumor growth and lung metastasis were inhibited in the mice carrying tPA- and uPA-overexpressing tumors, compared with controls (tumor weight at day 34: control, mean = 1760 mg, 95% confidence interval [CI] = 1434 to 2087 mg; tPA, mean = 921, 95% CI = 624 to 1217 mg; P < .001; uPA, mean = 395 mg, 95% CI = 161 to 629 mg; P < .001; number of lung metastases at day 34: control, mean = 117, 95% CI = 74 to 159; tPA, mean = 33, 95% CI = 13 to 52; uPA, mean = 15, 95% CI = 4 to 25; P < .001). Median survival was 42 (95% CI = 36 to 44), 55 (95% CI = 48 to 61), and 73 (95% CI = 51 to 86) days in the control, tPA, and uPA groups, respectively (P < .001). uPA- and tPA-expressing tumors had reduced angiogenesis and cell proliferation compared with controls. Tumors overexpressing uPA mutants grew faster than tumors expressing wild-type uPA (tumor volume at day 30: wild-type uPA, mean = 203, 95% CI = 121 to 285 mm3; control, mean = 534, 95% CI = 460 to 608 mm3; P < .001; mutant A, mean = 600, 95% CI = 520 to 679 mm3; P < .001; and mutant B, mean = 435, 95% CI = 358.9 to 511 mm3; P = .005). CONCLUSIONS: In this mouse model, uPA expression delayed tumor progression and had antiangiogenic and antiproliferative effects that may be mediated by uPA's protease activity. These results challenge the current dogma of proteases being exclusively tumor promoting and provide further rationale for exploring plasminogen activators as antitumor agents.

Insulin resistance and alterations in angiogenesis: additive insults that may lead to preeclampsia.

Altered angiogenesis and insulin resistance, which are intimately related at a molecular level, characterize preeclampsia. To test if an epidemiological interaction exists between these two alterations, we performed a nested case-control study of 28 women who developed preeclampsia and 57 contemporaneous controls. Serum samples at 12 weeks of gestation were measured for sex hormone binding globulin (SHBG; low levels correlate with insulin resistance) and placental growth factor (PlGF; a proangiogenic molecule). Compared with controls, women who developed preeclampsia had lower serum levels of SHBG (208+/-116 versus 256+/-101 nmol/L, P=0.05) and PlGF (16+/-14 versus 67+/-150 pg/mL, P<0.001), and in multivariable analysis, women with serum levels of PlGF < or =20 pg/mL had an increased risk of developing preeclampsia (odds ratio [OR] 7.6, 95% CI 1.4 to 38.4). Stratified by levels of serum SHBG (< or =175 versus >175 mg/dL), women with low levels of SHBG and PlGF had a 25.5-fold increased risk of developing preeclampsia (P=0.10), compared with 1.8 (P=0.38) among women with high levels of SHBG and low levels of PlGF. Formal testing for interaction (PlGFxSHBG) was significant (P=0.02). In a model with 3 (n-1) interaction terms (high PlGF and high SHBG, reference), the risk for developing preeclampsia was as follows: low PlGF and low SHBG, OR 15.1, 95% CI 1.7 to 134.9; high PlGF and low SHBG, OR 4.1, 95% CI 0.45 to 38.2; low PlGF and high SHBG, OR 8.7, 95% CI 1.2 to 60.3. Altered angiogenesis and insulin resistance are additive insults that lead to preeclampsia.