Publications by authors named "Sean Agbor-Enoh"

30 Publications

  • Page 1 of 1

Integrated cell-free DNA and cytokine analysis uncovers distinct tissue injury and immune response patterns in solid organ transplant recipients with COVID-19.

Res Sq 2022 Jan 20. Epub 2022 Jan 20.

COVID-19 pathogenesis is associated with an exuberant inflammatory response. However, the tissue injury pattern and immune response in solid-organ transplant recipients (SOTRs) taking immunosuppressive therapy have not been well characterized. Here, we perform both cfDNA and cytokine profiling on plasma samples to map tissue damage, including allograft injury and delineate underlying immunopathology. We identified injuries from multiple-tissue types, including hematopoietic cells, vascular endothelium, hepatocyte, adipocyte, pancreas, kidney, heart, and lung in SOTRs with COVID-19 that correlates with disease severity. SOTRs with COVID-19 have higher plasma levels of cytokines such as IFN-λ1, IFN-γ, IL-15, IL-18 IL-1RA, IL-6, MCP-2, and TNF-α as compared to healthy controls, and the levels of GM-CSF, IL-15, IL-6, IL-8, and IL-10 were associated with disease severity in SOTRs. Strikingly, IFN-λ and IP-10 were markedly increased in SOTRs compared to immunocompetent patients with COVID-19. Correlation analyses showed a strong association between monocyte-derived cfDNA and inflammatory cytokines/chemokines in SOTRs with COVID-19. Moreover, compared to other respiratory viral infections, COVID-19 induced pronounced injury in hematopoitic, vascular endothelial and endocrine tissues. Allograft injury, measured as donor-derived cfDNA was elevated in SOTRs with COVID-19, including allografts distant from the primary site of infection. Allograft injury correlated with inflammatory cytokines and cfDNA from immune cells. Furthermore, longitudinal analysis identified a gradual decrease of cfDNA and inflammatory cytokine levels in patients with a favorable outcome. Our findings highlight distinct tissue injury and cytokine features in SOTRs with COVID-19 that correlate with disease severity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.21203/rs.3.rs-1262270/v1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8786231PMC
January 2022

Donor-derived cell-free DNA as a composite marker of acute lung allograft dysfunction in clinical care.

J Heart Lung Transplant 2021 Dec 26. Epub 2021 Dec 26.

Laborarory of Applied Precision Omics (APO) and Genomic Research Alliance for Transplantation (GRAfT), National Institutes of Health, Bethesda, Maryland. Electronic address:

Background: As a marker of underlying lung allograft injury, donor-derived cell-free DNA (dd-cfDNA) may be used to identify episodes of acute allograft injury in lung transplant recipients. We investigated the utility of dd-cfDNA to monitor subjects at risk of acute rejection or infection in routine clinical practice.

Methods: This multicenter, retrospective cohort study collected data from lung transplant recipients within 3 years of transplant at 4 centers between March 24, 2020 and September 1, 2020. During this period, as part of routine care during the COVID-19 pandemic, these centers implemented a home-based surveillance program using plasma dd-cfDNA in preference to surveillance bronchoscopy. Dd-cfDNA was used to detect acute lung allograft dysfunction (ALAD) - a composite endpoint of acute rejection and infection. dd-cfDNA levels in patients with ALAD were compared to stable patients. The performance characteristics of dd-cfDNA ≥ 1.0% to detect ALAD were estimated.

Results: A total of 175 patients underwent 380 dd-cfDNA measurements, of which 290 were for routine surveillance purposes. dd-cfDNA was higher in patients with ALAD than stable patients (Median (IQR) 1.7% (0.63, 3.1) vs 0.35% (0.22, 0.79), p < 0.001). As an indication of underlying ALAD during surveillance testing, the estimated sensitivity of dd-cfDNA ≥1% was 73.9%, specificity of 87.7%, positive predictive value of 43.4% and negative predictive value of 96.5%.

Conclusions: dd-cfDNA identified acute lung allograft dysfunction in asymptomatic lung transplant patients that may not have been identified by using a clinically indicated biopsy strategy alone. dd-cfDNA <1.0% may be useful in ruling out acute rejection and infection, supporting its use as a potential noninvasive marker for surveillance monitoring.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.12.009DOI Listing
December 2021

Biological Variation of Donor-Derived Cell-Free DNA in Stable Lung Transplant Recipients.

J Appl Lab Med 2022 Jan 12. Epub 2022 Jan 12.

Laboratory of Applied Precision Omics (APO) and Genomic Research Alliance for Transplantation (GRAfT), National Institutes of Health, Bethesda, MD, USA.

Background: Prior studies demonstrate that donor-derived cell-free DNA (dd-cfDNA) in lung transplant recipients may serve as a marker of allograft injury for detecting allograft rejection and infection. Clinical interpretation of dd-cfDNA requires understanding its biological variation in stable lung transplant patients in order to identify abnormal results suggesting underlying allograft dysfunction. This study establishes the biological variation and reference change values (RCV) of dd-cfDNA in stable lung transplant recipients using an analytically validated assay with an established analytic coefficient of variation (CVA).

Methods: The AlloSure® assay, a targeted, sequencing-based approach, was used to measure plasma dd-cfDNA in a cohort of lung transplant patients at 4 centers that used dd-cfDNA to monitor for allograft dysfunction in preference to surveillance transbronchial biopsy. Patients with stable allograft function and ≥3 dd-cfDNA samples were included. Intraindividual coefficient of variation (CVI), interindividual CV (CVG), index of individuality (II) and the RCV were calculated.

Results: Thirty-five patients with a combined 124 dd-cfDNA samples were included in the final analysis. The median dd-cfDNA was 0.31% (interquartile range 0.18%-0.68%), the 97.5th percentile and 95th percentile were 1.3% and 1.0%, respectively. In 30 stable patients with an average of 3.7 tests, the CVI was 25%, CVG 19%, II 1.33, and RCV 70%.

Conclusion: In stable lung transplant patients, fluctuations in dd-cfDNA levels of up to 70% or levels less than 1% are within normal biological variation. With further validation, these thresholds may be incorporated into surveillance monitoring algorithms to identify potentially abnormal results indicating allograft dysfunction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jalm/jfab171DOI Listing
January 2022

Higher levels of allograft injury in black patients early after heart transplantation.

J Heart Lung Transplant 2021 Dec 23. Epub 2021 Dec 23.

Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; Laborarory of Applied Precision Omics (APO), Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland; Department of Medicine, Stanford University School of Medicine, Palo Alto, California. Electronic address:

Black patients suffer higher rates of antibody-mediated rejection and have worse long-term graft survival after heart transplantation. Donor-derived cell free DNA (ddcfDNA) is released into the blood following allograft injury. This study analyzed %ddcfDNA in 63 heart transplant recipients categorized by Black and non-Black race, during the first 200 days after transplant. Immediately after transplant, %ddcfDNA was higher for Black patients (mean [SE]: 8.3% [1.3%] vs 3.2% [1.2%], p = 0.001). In the first week post-transplant, the rate of decay in %ddcfDNA was similar (0.7% [0.68] vs 0.7% [0.11], p = 0.78), and values declined in both groups to a comparable plateau at 7 days post-transplant (0.46% [0.03] vs 0.45% [0.04], p = 0.78). The proportion of Black patients experiencing AMR was higher than non-Black patients (21% vs 9% [hazard ratio of 2.61 [95% confidence interval: 0.651-10.43], p = 0.18). Black patients were more likely to receive a race mismatched organ than non-Black patients (69% vs 35%, p = 0.01), which may explain the higher levels of early allograft injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.12.006DOI Listing
December 2021

Noninvasive biomarkers in heart transplant: 2020-2021 year in review.

Curr Opin Organ Transplant 2022 Feb;27(1):7-14

Genomic Research Alliance for Transplantation (GRAfT).

Purpose Of Review: Endomyocardial biopsy (EMB), the current gold standard for cardiac allograft monitoring is invasive, may have a low sensitivity and is associated with significant variability in histopathologic interpretation. Fortunately, on-going research is identifying noninvasive biomarkers that address some of these limitations. This review provides an update on noninvasive blood-based methods for rejection surveillance and diagnosis in heart transplantation.

Recent Findings: Recent studies highlight good test performance to detect acute rejection for donor-derived cell-free DNA (dd-cfDNA) and microRNAs (miR). dd-cfDNA is sensitive, nonspecific, and has a high negative predictive value for acute cellular and antibody-mediated rejection. Clinical utility trials are being planned to test its role as a rule-out test for acute rejection as compared to the EMB. miRs may have an added advantage as it may phenotype the subtypes of rejection alleviating the need for an EMB or permitting the initiation of targeted therapy while awaiting the results of the EMB.

Summary: In this review, we discuss recent advances in the field of noninvasive biomarkers to detect allograft rejection after heart transplant. We provide a perspective of additional studies needed to prove their clinical utility and bring these biomarkers to widescale clinical use.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MOT.0000000000000945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8711631PMC
February 2022

The effect of the cystic fibrosis care center on outcomes after lung transplantation for cystic fibrosis.

J Heart Lung Transplant 2021 Nov 25. Epub 2021 Nov 25.

Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.

Background: The purpose of this study was to evaluate outcomes in people with cystic fibrosis (CF) who underwent lung transplant (LT) at a transplant center with an accredited Cystic Fibrosis Care Center (CFCC) in the United States.

Methods: We reviewed the Scientific Registry of Transplant Recipients for all adult patients with CF who received a first-time LT from 2005 to 2018. The primary outcome was graft failure. Unadjusted Kaplan-Meier analysis and adjusted multilevel Cox proportional hazards models were used to evaluate outcomes in CF patients undergoing lung transplantation at a CFCC.

Results: 2,573 patients with CF underwent a first time LT during the study period. Of the 68 lung transplantation centers, 50 were CFCCs (73.5%). After adjustment for potential confounders, patients who underwent lung transplantation at a hospital with an accredited CFCC had a 33% reduction in risk of death or re-transplantation compared to those transplanted at a hospital without an accredited CFCC (HR: 0.67, 95% CI: 0.56-0.82, p < 0.001).

Conclusions: People with CF who undergo LT at a transplant center with a CFCC have improved graft survival and decreased need for re-transplantation compared to those who undergo LT at a non-CFCC, independent of volume.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.11.013DOI Listing
November 2021

Donor-Derived Cell-Free DNA for Acute Rejection Monitoring in Heart and Lung Transplantation.

Curr Transplant Rep 2021 Nov 5:1-8. Epub 2021 Nov 5.

Laborarory of Applied Precision Omics (APO) and Genomic Research Alliance for Transplantation (GRAfT), National Institute of Health, Bethesda, MD USA.

Purpose Of Review: Acute allograft rejection is a common cause of morbidity and mortality in heart and lung transplantation. Unfortunately, the current monitoring gold standard-biopsy plus histopathology-has several limitations. Plasma donor-derived cell-free DNA (dd-cfDNA) has emerged as a potentially valuable biomarker for rejection that addresses some of the limitations of biopsy. This review covers the current state of the evidence and future directions for the use of dd-cfDNA in the monitoring of acute rejection.

Recent Findings: The results of several observational cohort studies demonstrate that levels of dd-cfDNA increase in the setting of acute cellular rejection and antibody-mediated rejection in both heart and lung transplant recipients. dd-cfDNA demonstrates acceptable performance characteristics, but low specificity for the detection of underlying injury from rejection or infection. In particular, the high negative predictive value of the test in both heart and lung transplant patients provides the potential for its use as a screening tool for the monitoring of allograft health rather than tissue biopsy alone.

Summary: Existing evidence shows that dd-cfDNA is a safe, convenient, and reliable method of acute rejection monitoring in heart and lung transplant recipients. Further studies are required to validate threshold values for clinical use and determine its role in the diagnosis of alternative forms of allograft injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s40472-021-00349-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8570240PMC
November 2021

Molecular Approaches to Transplant Monitoring; Is the Horizon Here?

Clin Chem 2021 Nov;67(11):1443-1449

Genomic Research Alliance for Transplantation (GRAfT), National Heart, Lung, and Blood Institute Division of Intramural Research, Bethesda, MD.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/clinchem/hvab183DOI Listing
November 2021

The NIH Lipo-COVID Study: A Pilot NMR Investigation of Lipoprotein Subfractions and Other Metabolites in Patients with Severe COVID-19.

Biomedicines 2021 Aug 26;9(9). Epub 2021 Aug 26.

Lipoprotein Metabolism Section, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, MD 20892, USA.

A complex interplay exists between plasma lipoproteins and inflammation, as evidenced from studies on atherosclerosis. Alterations in plasma lipoprotein levels in the context of infectious diseases, particularly respiratory viral infections, such as SARS-CoV-2, have become of great interest in recent years, due to their potential utility as prognostic markers. Patients with severe COVID-19 have been reported to have low levels of total cholesterol, HDL-cholesterol, and LDL-cholesterol, but elevated levels of triglycerides. However, a detailed characterization of the particle counts and sizes of the different plasma lipoproteins in patients with COVID-19 has yet to be reported. In this pilot study, NMR spectroscopy was used to characterize lipoprotein particle numbers and sizes, and various metabolites, in 32 patients with severe COVID-19 admitted to the intensive care unit. Our study revealed markedly reduced HDL particle (HDL-P) numbers at presentation, especially low numbers of small HDL-P (S-HDL-P), and high counts of triglyceride-rich lipoprotein particle (TRL-P), particularly the very small and small TRL subfractions. Moreover, patients with severe COVID-19 were found to have remarkably elevated GlycA levels, and elevated levels of branched-chain amino acids and beta-hydroxybutyrate. Finally, we detected elevated levels of lipoproteins X and Z in most participants, which are distinct markers of hepatic dysfunction, and that was a novel finding.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/biomedicines9091090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8471250PMC
August 2021

Response by Shah et al to Letter Regarding Article, "Cell-Free DNA to Detect Heart Allograft Acute Rejection".

Circulation 2021 09 7;144(10):e198-e199. Epub 2021 Sep 7.

Genomic Research Alliance for Transplantation (GRAfT), Bethesda, MD (P.S., S.A-E., I.T., S.H., E.F., K.S., M.E.R., S.S.N., H.K., U.F., A.B., A.M., K.B., Y.Y., M.K.J., C.Marboe, G.J.B., H.A.V.).

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCULATIONAHA.121.055697DOI Listing
September 2021

Donor derived cell free DNA% is elevated with pathogens that are risk factors for acute and chronic lung allograft injury.

J Heart Lung Transplant 2021 11 30;40(11):1454-1462. Epub 2021 May 30.

Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore; Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland. Electronic address:

Background: Acute and chronic forms of lung allograft injury are associated with specific respiratory pathogens. Donor-derived cell free DNA (ddcfDNA) has been shown to be elevated with acute lung allograft injury and predictive of long-term outcomes. We examined the %ddcfDNA values at times of microbial isolation from bronchoalveolar lavage (BAL).

Methods: Two hundred and six BAL samples from 51 Lung Transplant Recipients (LTRs) with concurrently available plasma %ddcfDNA were analyzed along with microbiology and histopathology. Microbial species were grouped into bacterial, fungal, and viral and "higher risk" and "lower risk" cohorts based on historical association with downstream allograft dysfunction. Analyses were performed to determine pathogen category association with %ddcfDNA, independent of inter-subject variability.

Results: Presence of microbial isolates in BAL was not associated with elevated %ddcfDNA compared to samples without isolates. However, "higher risk" bacterial and viral microbes showed greater %ddcfDNA values than lower risk species (1.19% vs. 0.65%, p < 0.01), independent of inter-subject variability. Histopathologic abnormalities concurrent with pathogen isolation were associated with higher %ddcfDNA compared to isolation episodes with normal histopathology (medians 1.23% and 0.66%, p = 0.05). Assessments showed no evidence of correlation between histopathology or bronchoscopy indication and presence of higher risk vs. lower risk pathogens.

Conclusion: %ddcfDNA is higher among cases of microbial isolation with concurrent abnormal histopathology and with isolation of higher risk pathogens known to increase risk of allograft dysfunction. Future studies should assess if %ddcfDNA can be used to stratify pathogens for risk of CLAD and identify pathogen associated injury prior to histopathology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.05.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8571060PMC
November 2021

Donor-derived cell-free DNA accurately detects acute rejection in lung transplant patients, a multicenter cohort study.

J Heart Lung Transplant 2021 08 24;40(8):822-830. Epub 2021 Apr 24.

Genomic Research Alliance for Transplantation (GRAfT), 10 Center Drive, 7S261, Bethesda, Maryland; Division of Intramural Research, National Heart, Lung and Blood Institute, 10 Center Drive, 7S261, Bethesda, Maryland; Division of Pulmonary and Critical Care Medicine, The Johns Hopkins School of Medicine, 1830 East Monument Street, Baltimore, Maryland. Electronic address:

Background: Acute rejection, which includes antibody-mediated rejection and acute cellular rejection, is a risk factor for lung allograft loss. Lung transplant patients often undergo surveillance transbronchial biopsies to detect and treat acute rejection before irreversible chronic rejection develops. Limitations of this approach include its invasiveness and high interobserver variability. We tested the performance of percent donor-derived cell-free DNA (%ddcfDNA), a non-invasive blood test, to detect acute rejection.

Methods: This multicenter cohort study monitored 148 lung transplant subjects over a median of 19.6 months. We collected serial plasma samples contemporaneously with TBBx to measure %ddcfDNA. Clinical data was collected to adjudicate for acute rejection. The primary analysis consisted of computing the area-under-the-receiver-operating-characteristic-curve of %ddcfDNA to detect acute rejection. Secondary analysis determined %ddcfDNA rule-out thresholds for acute rejection.

Results: ddcfDNA levels were high after transplant surgery and decayed logarithmically. With acute rejection, ddcfDNA levels rose six-fold higher than controls. ddcfDNA levels also correlated with severity of lung function decline and histological grading of rejection. %ddcfDNA area-under-the-receiver-operating-characteristic-curve for acute rejection, AMR, and ACR were 0.89, 0.93, and 0.83, respectively. ddcfDNA levels of <0.5% and <1.0% showed a negative predictive value of 96% and 90% for acute rejection, respectively. Histopathology detected one-third of episodes with ddcfDNA levels ≥1.0%, even though >90% of these events were coincident to clinical complications missed by histopathology.

Conclusions: This study demonstrates that %ddcfDNA reliably detects acute rejection and other clinical complications potentially missed by histopathology, lending support to its use as a non-invasive marker of allograft injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8319066PMC
August 2021

Cell-free DNA beyond a biomarker for rejection: Biological trigger of tissue injury and potential therapeutics.

J Heart Lung Transplant 2021 06 24;40(6):405-413. Epub 2021 Mar 24.

Lasker Clinical Research Tenure Track Investigator and Laboratory Chief, Laboratory of Applied Precision Omics, National Heart, Lung, and Blood Institute, Bethesda, Maryland; Lung Transplantation Program, Johns Hopkins School of Medicine, Baltimore, M. Electronic address:

Cell-free DNA, measured as donor-derived cell-free DNA is developed as a non-specific biomarker for allograft injury and transplant rejection. However, cell-free DNA characteristics are more specific, its fragment length, nucleotide content, and composition, as well as the tissue source of origin, are intrinsically linked to the underlying disease pathogenesis, showing distinct features in acute cellular rejection and antibody-mediated rejection for example. Further, cell-free DNA and cell-free mitochondrial DNA can directly trigger tissue injury as damage-associated molecular patterns through three major intracellular receptors, toll-like receptor 9 , cyclic guanosine monophosphate-adenosine monophosphate synthase, and inflammasomes (i.e., absent in melanoma 2: AIM2). Therefore, in addition to its role as a non-specific marker for allograft injury, cell-free DNA analysis may be used to phenotype transplant rejection, and to non-invasively point the underlying molecular mechanisms with allograft injury. Novel treatment approaches targeting these cell-free DNA pathways may be useful to treat transplant rejection and prevent end-organ dysfunction. In this review, we discuss the link between cell-free DNA characteristics and disease, the role of cell-free DNA as a damage-associated molecular pattern, and novel therapeutics targeting these cell-free DNA molecular pathways and their potential utility to treat transplant rejection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.03.007DOI Listing
June 2021

Use of donor-derived-cell-free DNA as a marker of early allograft injury in primary graft dysfunction (PGD) to predict the risk of chronic lung allograft dysfunction (CLAD).

J Heart Lung Transplant 2021 06 20;40(6):488-493. Epub 2021 Feb 20.

Laborarory of Applied Precision Omics (APO), Lung and Blood Institute (NHLBI), National Institutes of Health, Bethesda, Maryland; Genomic Research Alliance for Transplantation (GRAfT), National Heart, Lung and Blood Institute, Bethesda, Maryland; Department of Surgery, Johns Hopkins Hospital, Baltimore, Maryland. Electronic address:

Background: Primary graft dysfunction (PGD) is a risk factor for chronic lung allograft dysfunction (CLAD). However, the association between PGD and degree of allograft injury remains poorly defined. In this study, we leverage a novel biomarker for allograft injury, percentage donor-derived cell-free DNA (%ddcfDNA), to study the association between PGD, degree of allograft injury, and the development of CLAD.

Methods: This prospective cohort study recruited 99 lung transplant recipients and collected plasma samples on days 1, 3, and 7 for %ddcfDNA measurements. Clinical data on day 3 was used to adjudicate for PGD. %ddcfDNA levels were compared between PGD grades. In PGD patients, %ddcfDNA was compared between those who developed CLAD and those who did not.

Results: On posttransplant day 3, %ddcfDNA was higher in PGD than in non-PGD patients (median [IQR]: 12.2% [8.2, 22.0] vs 8.5% [5.6, 13.2] p = 0.01). %ddcfDNA correlated with the severity grade of PGD (r = 0.24, p = 0.02). Within the PGD group, higher levels of %ddcfDNA correlated with increased risk of developing CLAD (log OR(SE) 1.38 (0.53), p = 0.009). PGD patients who developed CLAD showed ∼2-times higher %ddcfDNA levels than patients who did not develop CLAD (median [IQR]: 22.4% [11.8, 27.6] vs 9.9% [6.7, 14.9], p = 0.007).

Conclusion: PGD patients demonstrated increased early posttransplant allograft injury, as measured by %ddcfDNA, in comparison to non-PGD patients, and these high %ddcfDNA levels were associated with subsequent development of CLAD. This study suggests that %ddcfDNA identifies PGD patients at greater risk of CLAD than PGD alone.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2021.02.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8169618PMC
June 2021

Applications of genetic-epigenetic tissue mapping for plasma DNA in prenatal testing, transplantation and oncology.

Elife 2021 03 23;10. Epub 2021 Mar 23.

Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.

We developed genetic-epigenetic tissue mapping (GETMap) to determine the tissue composition of plasma DNA carrying genetic variants not present in the constitutional genome through comparing their methylation profiles with relevant tissues. We validated this approach by showing that, in pregnant women, circulating DNA carrying fetal-specific alleles was entirely placenta-derived. In lung transplant recipients, we showed that, at 72 hr after transplantation, the lung contributed only a median of 17% to the plasma DNA carrying donor-specific alleles, and hematopoietic cells contributed a median of 78%. In hepatocellular cancer patients, the liver was identified as the predominant source of plasma DNA carrying tumor-specific mutations. In a pregnant woman with lymphoma, plasma DNA molecules carrying cancer mutations and fetal-specific alleles were accurately shown to be derived from the lymphocytes and placenta, respectively. Analysis of tissue origin for plasma DNA carrying genetic variants is potentially useful for noninvasive prenatal testing, transplantation monitoring, and cancer screening.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.64356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997656PMC
March 2021

Cell-free DNA maps COVID-19 tissue injury and risk of death and can cause tissue injury.

JCI Insight 2021 04 8;6(7). Epub 2021 Apr 8.

Genomic Research Alliance for Transplantation (GRAfT) and Laboratory of Applied Precision Omics, National Heart, Lung, and Blood Institute (NHLBI), NIH, Bethesda, Maryland, USA.

INTRODUCTIONThe clinical course of coronavirus 2019 (COVID-19) is heterogeneous, ranging from mild to severe multiorgan failure and death. In this study, we analyzed cell-free DNA (cfDNA) as a biomarker of injury to define the sources of tissue injury that contribute to such different trajectories.METHODSWe conducted a multicenter prospective cohort study to enroll patients with COVID-19 and collect plasma samples. Plasma cfDNA was subject to bisulfite sequencing. A library of tissue-specific DNA methylation signatures was used to analyze sequence reads to quantitate cfDNA from different tissue types. We then determined the correlation of tissue-specific cfDNA measures to COVID-19 outcomes. Similar analyses were performed for healthy controls and a comparator group of patients with respiratory syncytial virus and influenza.RESULTSWe found markedly elevated levels and divergent tissue sources of cfDNA in COVID-19 patients compared with patients who had influenza and/or respiratory syncytial virus and with healthy controls. The major sources of cfDNA in COVID-19 were hematopoietic cells, vascular endothelium, hepatocytes, adipocytes, kidney, heart, and lung. cfDNA levels positively correlated with COVID-19 disease severity, C-reactive protein, and D-dimer. cfDNA profile at admission identified patients who subsequently required intensive care or died during hospitalization. Furthermore, the increased cfDNA in COVID-19 patients generated excessive mitochondrial ROS (mtROS) in renal tubular cells in a concentration-dependent manner. This mtROS production was inhibited by a TLR9-specific antagonist.CONCLUSIONcfDNA maps tissue injury that predicts COVID-19 outcomes and may mechanistically propagate COVID-19-induced tissue injury.FUNDINGIntramural Targeted Anti-COVID-19 grant, NIH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/jci.insight.147610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8119224PMC
April 2021

Cell-Free DNA to Detect Heart Allograft Acute Rejection.

Circulation 2021 03 13;143(12):1184-1197. Epub 2021 Jan 13.

Genomic Research Alliance for Transplantation, Bethesda, MD (S.A.-E., P.S., I.T., S.H., E.F., K.S., M.E.R., S.S.N., H.K., U.F., A.B., A.M., K.B., Y.Y., M.K.J., C.M., G.J.B., H.A.V.).

Background: After heart transplantation, endomyocardial biopsy (EMBx) is used to monitor for acute rejection (AR). Unfortunately, EMBx is invasive, and its conventional histological interpretation has limitations. This is a validation study to assess the performance of a sensitive blood biomarker-percent donor-derived cell-free DNA (%ddcfDNA)-for detection of AR in cardiac transplant recipients.

Methods: This multicenter, prospective cohort study recruited heart transplant subjects and collected plasma samples contemporaneously with EMBx for %ddcfDNA measurement by shotgun sequencing. Histopathology data were collected to define AR, its 2 phenotypes (acute cellular rejection [ACR] and antibody-mediated rejection [AMR]), and controls without rejection. The primary analysis was to compare %ddcfDNA levels (median and interquartile range [IQR]) for AR, AMR, and ACR with controls and to determine %ddcfDNA test characteristics using receiver-operator characteristics analysis.

Results: The study included 171 subjects with median posttransplant follow-up of 17.7 months (IQR, 12.1-23.6), with 1392 EMBx, and 1834 %ddcfDNA measures available for analysis. Median %ddcfDNA levels decayed after surgery to 0.13% (IQR, 0.03%-0.21%) by 28 days. Also, %ddcfDNA increased again with AR compared with control values (0.38% [IQR, 0.31-0.83%], versus 0.03% [IQR, 0.01-0.14%]; <0.001). The rise was detected 0.5 and 3.2 months before histopathologic diagnosis of ACR and AMR. The area under the receiver operator characteristic curve for AR was 0.92. A 0.25%ddcfDNA threshold had a negative predictive value for AR of 99% and would have safely eliminated 81% of EMBx. In addition, %ddcfDNA showed distinctive characteristics comparing AMR with ACR, including 5-fold higher levels (AMR ≥2, 1.68% [IQR, 0.49-2.79%] versus ACR grade ≥2R, 0.34% [IQR, 0.28-0.72%]), higher area under the receiver operator characteristic curve (0.95 versus 0.85), higher guanosine-cytosine content, and higher percentage of short ddcfDNA fragments.

Conclusions: We found that %ddcfDNA detected AR with a high area under the receiver operator characteristic curve and negative predictive value. Monitoring with ddcfDNA demonstrated excellent performance characteristics for both ACR and AMR and led to earlier detection than the EMBx-based monitoring. This study supports the use of %ddcfDNA to monitor for AR in patients with heart transplant and paves the way for a clinical utility study. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02423070.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCULATIONAHA.120.049098DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8221834PMC
March 2021

The SIRPα-CD47 immune checkpoint in NK cells.

J Exp Med 2021 03;218(3)

Department of Surgery, Division of Cardiothoracic Surgery, Transplant and Stem Cell Immunobiology Lab, University of California, San Francisco, San Francisco, CA.

Here we report on the existence and functionality of the immune checkpoint signal regulatory protein α (SIRPα) in NK cells and describe how it can be modulated for cell therapy. NK cell SIRPα is up-regulated upon IL-2 stimulation, interacts with target cell CD47 in a threshold-dependent manner, and counters other stimulatory signals, including IL-2, CD16, or NKG2D. Elevated expression of CD47 protected K562 tumor cells and mouse and human MHC class I-deficient target cells against SIRPα+ primary NK cells, but not against SIRPα- NKL or NK92 cells. SIRPα deficiency or antibody blockade increased the killing capacity of NK cells. Overexpression of rhesus monkey CD47 in human MHC-deficient cells prevented cytotoxicity by rhesus NK cells in a xenogeneic setting. The SIRPα-CD47 axis was found to be highly species specific. Together, the results demonstrate that disruption of the SIRPα-CD47 immune checkpoint may augment NK cell antitumor responses and that elevated expression of CD47 may prevent NK cell-mediated killing of allogeneic and xenogeneic tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1084/jem.20200839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7802363PMC
March 2021

Transcriptomics in transplantation: More than just biomarkers of allograft rejection.

Am J Transplant 2021 06 21;21(6):2000-2001. Epub 2020 Dec 21.

Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ajt.16429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8178244PMC
June 2021

De novo mutations in mitochondrial DNA of iPSCs produce immunogenic neoepitopes in mice and humans.

Nat Biotechnol 2019 10 19;37(10):1137-1144. Epub 2019 Aug 19.

Department of Surgery, Division of Cardiothoracic Surgery, Transplant and Stem Cell Immunobiology Lab, University of California, San Francisco, San Francisco, CA, USA.

The utility of autologous induced pluripotent stem cell (iPSC) therapies for tissue regeneration depends on reliable production of immunologically silent functional iPSC derivatives. However, rejection of autologous iPSC-derived cells has been reported, although the mechanism underlying rejection is largely unknown. We hypothesized that de novo mutations in mitochondrial DNA (mtDNA), which has far less reliable repair mechanisms than chromosomal DNA, might produce neoantigens capable of eliciting immune recognition and rejection. Here we present evidence in mice and humans that nonsynonymous mtDNA mutations can arise and become enriched during reprogramming to the iPSC stage, long-term culture and differentiation into target cells. These mtDNA mutations encode neoantigens that provoke an immune response that is highly specific and dependent on the host major histocompatibility complex genotype. Our results reveal that autologous iPSCs and their derivatives are not inherently immunologically inert for autologous transplantation and suggest that iPSC-derived products should be screened for mtDNA mutations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41587-019-0227-7DOI Listing
October 2019

2018 ATS BEAR Cage Winning Proposal: Cell-Free DNA to Improve Lung Transplant Outcomes.

Authors:
Sean Agbor-Enoh

Am J Respir Crit Care Med 2019 05;199(9):1058-1060

1 Division of Intramural Research National Heart, Lung, and Blood Institute Bethesda, Maryland and.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1164/rccm.201902-0458EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6515866PMC
May 2019

Donor-derived cell-free DNA predicts allograft failure and mortality after lung transplantation.

EBioMedicine 2019 Feb 26;40:541-553. Epub 2019 Jan 26.

Genomic Research Alliance for Transplantation (GRAfT), 10 Center Drive, 7S261, Bethesda, MD 20982, United States; Division of Intramural Research, National Heart, Lung and Blood Institute, 10 Center Drive, 7S261, Bethesda, MD 20982, United States. Electronic address:

Background: Allograft failure is common in lung-transplant recipients and leads to poor outcomes including early death. No reliable clinical tools exist to identify patients at high risk for allograft failure. This study tested the use of donor-derived cell-free DNA (%ddcfDNA) as a sensitive marker of early graft injury to predict impending allograft failure.

Methods: This multicenter, prospective cohort study enrolled 106 subjects who underwent lung transplantation and monitored them after transplantation for the development of allograft failure (defined as severe chronic lung allograft dysfunction [CLAD], retransplantation, and/or death from respiratory failure). Plasma samples were collected serially in the first three months following transplantation and assayed for %ddcfDNA by shotgun sequencing. We computed the average levels of ddcfDNA over three months for each patient (avddDNA) and determined its relationship to allograft failure using Cox-regression analysis.

Findings: avddDNA was highly variable among subjects: median values were 3·6%, 1·6% and 0·7% for the upper, middle, and low tertiles, respectively (range 0·1%-9·9%). Compared to subjects in the low and middle tertiles, those with avddDNA in the upper tertile had a 6·6-fold higher risk of developing allograft failure (95% confidence interval 1·6-19·9, p = 0·007), lower peak FEV1 values, and more frequent %ddcfDNA elevations that were not clinically detectable.

Interpretation: Lung transplant patients with early unresolving allograft injury measured via %ddcfDNA are at risk of subsequent allograft injury, which is often clinically silent, and progresses to allograft failure. FUND: National Institutes of Health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ebiom.2018.12.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412014PMC
February 2019

Environment, Epigenetics, and Differential Responses to Beryllium Exposure: Are We There Yet?

Am J Respir Cell Mol Biol 2019 01;60(1):11-12

2 Division of Intramural Research National Heart, Lung and Blood Institute Bethesda, Maryland.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1165/rcmb.2018-0306EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6348714PMC
January 2019

Circulating cell-free DNA as a biomarker of tissue injury: Assessment in a cardiac xenotransplantation model.

J Heart Lung Transplant 2018 08 26;37(8):967-975. Epub 2018 Apr 26.

Genomic Research Alliance for Transplantation (GRAfT), Division of Intramural Research, National Institutes of Health, Bethesda, Maryland; Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland. Electronic address:

Background: Observational studies suggest that cell-free DNA (cfDNA) is a biomarker of tissue injury in a range of conditions including organ transplantation. However, the lack of model systems to study cfDNA and its relevance to tissue injury has limited the advancements in this field. We hypothesized that the predictable course of acute humoral xenograft rejection (AHXR) in organ transplants from genetically engineered donors provides an ideal system for assessing circulating cfDNA as a marker of tissue injury.

Methods: Genetically modified pig donor hearts were heterotopically transplanted into baboons (n = 7). Cell-free DNA was extracted from pre-transplant and post-transplant baboon plasma samples for shotgun sequencing. After alignment of sequence reads to pig and baboon reference sequences, we computed the percentage of xenograft-derived cfDNA (xdcfDNA) relative to recipient by counting uniquely aligned pig and baboon sequence reads.

Results: The xdcfDNA percentage was high early post-transplantation and decayed exponentially to low stable levels (baseline); the decay half-life was 3.0 days. Post-transplantation baseline xdcfDNA levels were higher for transplant recipients that subsequently developed graft loss than in the 1 animal that did not reject the graft (3.2% vs 0.5%). Elevations in xdcfDNA percentage coincided with increased troponin and clinical evidence of rejection. Importantly, elevations in xdcfDNA percentage preceded clinical signs of rejection or increases in troponin levels.

Conclusion: Cross-species xdcfDNA kinetics in relation to acute rejection are similar to the patterns in human allografts. These observations in a xenotransplantation model support the body of evidence suggesting that circulating cfDNA is a marker of tissue injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2018.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707066PMC
August 2018

Late manifestation of alloantibody-associated injury and clinical pulmonary antibody-mediated rejection: Evidence from cell-free DNA analysis.

J Heart Lung Transplant 2018 07 31;37(7):925-932. Epub 2018 Jan 31.

Department of Medicine, Stanford University School of Medicine, Palo Alto, California, USA. Electronic address:

Background: Antibody-mediated rejection (AMR) often progresses to poor health outcomes in lung transplant recipients (LTRs). This, combined with the relatively insensitive clinical tools used for its diagnosis (spirometry, histopathology) led us to determine whether clinical AMR is diagnosed significantly later than its pathologic onset. In this study, we leveraged the high sensitivity of donor-derived cell-free DNA (ddcfDNA), a novel genomic tool, to detect early graft injury after lung transplantation.

Methods: We adjudicated AMR and acute cellular rejection (ACR) in 157 LTRs using the consensus criteria of the International Society for Heart and Lung Transplantation (ISHLT). We assessed the kinetics of allograft injury in relation to ACR or AMR using both clinical criteria (decline in spirometry from baseline) and molecular criteria (ddcfDNA); percent ddcfDNA was quantitated via shotgun sequencing. We used a mixed-linear model to assess the relationship between and ddcfDNA levels and donor-specific antibodies (DSA) in AMR LTRs.

Results: Compared with ACR, AMR episodes (n = 42) were associated with significantly greater allograft injury when assessed by both spirometric (0.1 liter vs -0.6 liter, p < 0.01) and molecular (ddcfDNA) analysis (1.1% vs 5.4%, p < 0.001). Allograft injury detected by ddcfDNA preceded clinical AMR diagnosis by a median of 2.8 months. Within the same interval, spirometry or histopathology did not reveal findings of allograft injury or dysfunction. Elevated levels of ddcfDNA before clinical diagnosis of AMR were associated with a concurrent rise in DSA levels.

Conclusion: Diagnosis of clinical AMR in LTRs lags behind DSA-associated molecular allograft injury as assessed by ddcfDNA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2018.01.1305DOI Listing
July 2018

Applying rigor and reproducibility standards to assay donor-derived cell-free DNA as a non-invasive method for detection of acute rejection and graft injury after heart transplantation.

J Heart Lung Transplant 2017 Sep 20;36(9):1004-1012. Epub 2017 May 20.

Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; Laboratory of Transplantation Genomics, National Heart, Lung, and Blood Institute, Bethesda, Maryland. Electronic address:

Background: Use of new genomic techniques in clinical settings requires that such methods are rigorous and reproducible. Previous studies have shown that quantitation of donor-derived cell-free DNA (%ddcfDNA) by unbiased shotgun sequencing is a sensitive, non-invasive marker of acute rejection after heart transplantation. The primary goal of this study was to assess the reproducibility of %ddcfDNA measurements across technical replicates, manual vs automated platforms, and rejection phenotypes in distinct patient cohorts.

Methods: After developing and validating the %ddcfDNA assay, we subjected the method to a rigorous test of its reproducibility. We measured %ddcfDNA in technical replicates performed by 2 independent laboratories and verified the reproducibility of %ddcfDNA patterns of 2 rejection phenotypes: acute cellular rejection and antibody-mediated rejection in distinct patient cohorts.

Results: We observed strong concordance of technical-replicate %ddcfDNA measurements across 2 independent laboratories (slope = 1.02, R > 0.99, p < 10), as well as across manual and automated platforms (slope = 0.80, R = 0.92, p < 0.001). The %ddcfDNA measurements in distinct heart transplant cohorts had similar baselines and error rates. The %ddcfDNA temporal patterns associated with rejection phenotypes were similar in both patient cohorts; however, the quantity of ddcfDNA was significantly higher in samples with severe vs mild histologic rejection grade (2.73% vs 0.14%, respectively; p < 0.001).

Conclusions: The %ddcfDNA assay is precise and reproducible across laboratories and in samples from 2 distinct types of heart transplant rejection. These findings pave the way for larger studies to assess the clinical utility of %ddcfDNA as a marker of acute rejection after heart transplantation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.healun.2017.05.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988434PMC
September 2017

Single-stranded DNA library preparation uncovers the origin and diversity of ultrashort cell-free DNA in plasma.

Sci Rep 2016 06 14;6:27859. Epub 2016 Jun 14.

Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.

Circulating cell-free DNA (cfDNA) is emerging as a powerful monitoring tool in cancer, pregnancy and organ transplantation. Nucleosomal DNA, the predominant form of plasma cfDNA, can be adapted for sequencing via ligation of double-stranded DNA (dsDNA) adapters. dsDNA library preparations, however, are insensitive to ultrashort, degraded cfDNA. Drawing inspiration from advances in paleogenomics, we have applied a single-stranded DNA (ssDNA) library preparation method to sequencing of cfDNA in the plasma of lung transplant recipients (40 samples, six patients). We found that ssDNA library preparation yields a greater portion of sub-100 bp nuclear genomic cfDNA (p 10(-5), Mann-Whitney U Test), and an increased relative abundance of mitochondrial (10.7x, p 10(-5)) and microbial cfDNA (71.3x, p 10(-5)). The higher yield of microbial sequences from this method increases the sensitivity of cfDNA-based monitoring for infections following transplantation. We detail the fragmentation pattern of mitochondrial, nuclear genomic and microbial cfDNA over a broad fragment length range. We report the observation of donor-specific mitochondrial cfDNA in the circulation of lung transplant recipients. A ssDNA library preparation method provides a more informative window into understudied forms of cfDNA, including mitochondrial and microbial derived cfDNA and short nuclear genomic cfDNA, while retaining information provided by standard dsDNA library preparation methods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/srep27859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906518PMC
June 2016

Lie down and breathe.

Ann Am Thorac Soc 2014 Sep;11(7):1155-8

1 Division of Pulmonary and Critical Care Medicine, Johns Hopkins Hospital, Baltimore, Maryland; and.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1513/AnnalsATS.201402-073CCDOI Listing
September 2014

Rat spongiotrophoblast-specific protein is predominantly a unique low sulfated chondroitin sulfate proteoglycan.

J Biol Chem 2006 Oct 5;281(43):32327-34. Epub 2006 Sep 5.

Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033-0850, USA.

We have previously demonstrated that the human placenta contains a uniquely low sulfated extracellular aggrecan family chondroitin sulfate proteoglycan (CSPG). This CSPG is a major receptor for the adherence of Plasmodium falciparum-infected red blood cells (IRBCs) in placentas, causing pregnancy-specific malaria. However, it is not known whether such low sulfated CSPGs occur in placentas of other animals and, if so, whether IRBCs bind to those CSPGs. In this study, we show that rat placenta contains a uniquely low sulfated extracellular CSPG bearing chondroitin sulfate (CS) chains, which comprise only approximately 2% 4-sulfated and the remainder nonsulfated disaccharides. Surprisingly, the core protein of the rat placental CSPG, unlike that of the human placental CSPG, is a spongiotrophoblast-specific protein (SSP), which is expressed in a pregnancy stage-dependent manner. The majority of rat placental SSP is present in the CSPG form, and only approximately 10% occurs without CS chain substitution. Of the total SSP-CSPG in rat placenta, approximately 57% is modified with a single CS chain, and approximately 43% carries two CS chains. These data together with the previous finding on human placental CSPG suggest that the expression of low sulfated CSPG is a common feature of animal placentas. Our data also show that the unique species-specific difference in the biology of the rat and human placentas is reflected in the occurrence of completely different CSPG core protein types. Furthermore, the rat SSP-CSPG binds P. falciparum IRBCs in a CS chain-dependent manner. Since IRBCs have been reported to accumulate in the placentas of malaria parasite-infected rodents, our results have important implications for exploiting pregnant rats as a model for studying chondroitin 4-sulfate-based therapeutics for human placental malaria.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M605841200DOI Listing
October 2006

Chondroitin sulfate proteoglycan expression and binding of Plasmodium falciparum-infected erythrocytes in the human placenta during pregnancy.

Infect Immun 2003 May;71(5):2455-61

Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D.C. 20007, USA.

A characteristic feature of malaria during pregnancy is the sequestration of Plasmodium falciparum-infected red blood cells (IRBCs) in the intervillous spaces of the placenta. We have recently shown that unusually low-sulfated chondroitin sulfate proteoglycans (CSPGs) present in the intervillous spaces mediate the adherence of IRBCs in the placenta. In areas of endemicity, the prevalence of P. falciparum infection in pregnant women peaks during weeks 13 to 20 and then gradually declines, implying that the placental CSPGs are available for IRBC adhesion early during the pregnancy. However, there is no information on the expression and composition of CSPGs during pregnancy. In this study, the expression pattern of CSPGs during the course of pregnancy was investigated. The CSPGs were purified from placentas of various gestational ages, characterized, and tested for the ability to bind IRBCs. The data demonstrate that the CSPGs are present in the intervillous spaces throughout the second and third trimesters. The levels of CSPGs expressed per unit tissue weight were similar in placentas of various gestational ages. However, the structures of the intervillous-space CSPGs changed considerably during the course of pregnancy. In particular, the molecular weight was decreased, with an accompanying gradual increase in the CSPG size polydispersity, from 16 weeks until 38 weeks. The sulfate content was increased considerably after 24 weeks. Despite these structural changes, the CSPGs of placentas of various gestational ages efficiently supported the binding of IRBCs. These results demonstrate that CSPGs can mediate the sequestration of IRBCs in the intervillous spaces of the placenta during the entire second and third trimesters and possibly during the later part of the first trimester as well.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC153269PMC
http://dx.doi.org/10.1128/IAI.71.5.2455-2461.2003DOI Listing
May 2003
-->