EXTRACELLULAR VESICLES AS MARKERS OF INFLAMMATION AND HYPERCOAGULABILITY DURING THE FIRST MONTH OF SARS-COV-2 INFECTION IN OUTPATIENTS AND HOSPITALIZED PATIENTS

Introduction

During SARS-CoV-2 infection, a severe hypercoagulability state is observed due to the stimulus of multiple mechanisms of hemostasis, such as coagulation, activation of platelets, endothelial cells, monocytes and neutrophils and impaired fibrinolysis. As a consequence, thrombotic complications are common in the course of COVID-19. Microvesicles (MVs) are intracellular transmitters that participate in pathological conditions, such as inflammatory and infectious processes, and are capable of triggering prothrombotic mechanisms. Since MVs release is potentially associated with COVID-19-induced coagulopathy, our aim was to identify during the course of the disease when the stimulus for MVs release occurs and whether this was associated with adverse outcomes.

Objective

We evaluated changes in the levels of MVs markers during the first month of SARS-CoV-2 infection in patients (pts) with severe disease (hospitalized in an Intensive Care Unit ‒ ICU) as compared to outpatients. We also evaluated the association between MVs markers with: inflammatory biomarkers (C-reactive protein, CRP), hypercoagulability (D-dimer) and death.

Methods

Blood samples were collected on three occasions: before the 10^th day of symptoms, in the 3^rd week of symptoms and in the 4^th week of symptoms for the quantification of the following MVs markers by flow cytometry: CD41A (platelet activation), CD162 (PSGL-1; leukocyte-platelet interaction), CD31 (endothelium-platelet interaction) and CD142 (tissue factor). Statistical tests of ANOVA with repeated measures, Mann-Whitney and regression methods were used.

Results

The population studied was 85 pts, being 25 from ICU. Mostly were men (51%), with a median age of 41 years. The concentration of MVs expressing CD31+, CD41+, CD162+ and CD142+ were persistently elevated in pts who required ICU compared to outpatients at the 3 moments studied, except for the levels of MVs-CD31+ and MVs-CD142+ that were similar between ICU and outpatients in the 4^th week of symptoms. However, despite the differences between the groups, there were no significant changes in the levels of MVs during the course of the disease within the groups. In subgroup analysis, we observed that increases in the levels of MVs-CD162+ and MVs-CD142+ in the 3^rd week of symptoms were associated with the risk of death (p=0.02 and p=0.06, respectively). We also observed that during the course of the disease an association between MVs, coagulability and inflammation was evident. In the 3rd week of symptoms, D-dimer levels were correlated with MV-CD31+ (r=0.52, p<0.0001), MV-CD162+ (r=0.35, p=0.001), MV-CD41A+ (r=0.44, p<0.0001) and MV-CD142+ (r=0.47, p<0.0001) and CRP values were correlated with MV-CD31+ (r=0.56, p=<0.0001), MV-CD162+ (r=0.48, p<0.0001), MV-CD41A+ (r= 0.41, p=0.0001), and MV-CD142+ (r=0.56, p<0.0001). By the 4^th week of symptoms, both D-dimers and CRP correlations with the above MVs remained unchanged.

Conclusion

To conclude, MVs that express antigens related to platelet activation, leukocyte-platelet interaction and endothelium-platelet interaction, as well as those related to tissue factor are released during the course of COVID-19 in pts with severe disease. After the 4^th week of symptoms, the release of these MVs was associated with signs of inflammation and hypercoagulability. Additionally, MVs that express tissue factor and leukocyte-platelet interaction antigens were particularly high among non-survivors, suggesting that these MVs may serve as markers of the risk of death. Finally, these findings suggest the participation of innate immunity and tissue factor pathways in the prognosis of COVID-19, and point towards a possible role of MVs as biomarkers of disease prognosis.

Stem Cell Transplantation for Diamond-Blackfan Anemia. A Retrospective Study on Behalf of the Severe Aplastic Anemia Working Party of the European Blood and Marrow Transplantation Group (EBMT)

Data on stem cell transplantation (SCT) for Diamond-Blackfan Anemia (DBA) is limited. We studied patients transplanted for DBA and registered in the EBMT database. Between 1985 and 2016, 106 DBA patients (median age, 6.8 years) underwent hematopoietic stem cell transplantation from matched-sibling donors (57%), unrelated donors (36%), or other related donors (7%), using marrow (68%), peripheral blood stem cells (20%), both marrow and peripheral blood stem cells (1%), or cord blood (11%). The cumulative incidence of engraftment was 86% (80% to 93%), and neutrophil recovery and platelet recovery were achieved on day +18 (range, 16 to 20) and +36 (range, 32 to 43), respectively. Three-year overall survival and event-free survival were 84% (77% to 91%) and 81% (74% to 89%), respectively. Older patients were significantly more likely to die (hazard ratio, 1.4; 95% confidence interval, 1.06 to 1.23; P < .001). Outcomes were similar between sibling compared to unrelated-donor transplants. The incidence of acute grades II to IV of graft-versus-host disease (GVHD) was 30% (21% to 39%), and the incidence of extensive chronic GVHD was 15% (7% to 22%). This study shows that SCT may represent an alternative therapeutic option for transfusion-dependent younger patients.

How Ancestry Influences the Chances of Finding Unrelated Donors: An Investigation in Admixed Brazilians

A match of HLA loci between patients and donors is critical for successful hematopoietic stem cell transplantation. However, the extreme polymorphism of HLA loci - an outcome of millions of years of natural selection - reduces the chances that two individuals will carry identical combinations of multilocus HLA genotypes. Further, HLA variability is not homogeneously distributed throughout the world: African populations on average have greater variability than non-Africans, reducing the chances that two unrelated African individuals are HLA identical. Here, we explore how self-identification (often equated with "ethnicity" or "race") and genetic ancestry are related to the chances of finding HLA compatible donors in a large sample from Brazil, a highly admixed country. We query REDOME, Brazil's Bone Marrow Registry, and investigate how different criteria for identifying ancestry influence the chances of finding a match. We find that individuals who self-identify as "Black" and "Mixed" on average have lower chances of finding matches than those who self-identify as "White" (up to 57% reduction). We next show that an individual's African genetic ancestry, estimated using molecular markers and quantified as the proportion of an individual's genome that traces its ancestry to Africa, is strongly associated with reduced chances of finding a match (up to 60% reduction). Finally, we document that the strongest reduction in chances of finding a match is associated with having an MHC region of exclusively African ancestry (up to 75% reduction). We apply our findings to a specific condition, for which there is a clinical indication for transplantation: sickle-cell disease. We show that the increased African ancestry in patients with this disease leads to reduced chances of finding a match, when compared to the remainder of the sample, without the condition. Our results underscore the influence of ancestry on chances of finding compatible HLA matches, and indicate that efforts guided to increasing the African component of registries are necessary.

2665. Intestinal Microbiome of Patients Submitted to Hematopoietic Stem Cell Transplantation Using Lactobacillus plantarum to Decolonized Multidrug-Resistant Bacteria

Background

Patients colonized by multidrug-resistant bacteria (MDR) have high risk for infection after hematopoietic stem cell transplantation (HSCT). Probiotic is a strategy that can be used to decolonize patients. Our aim was to describe the impact of use of Lactobacillus plantarum (LP) on decolonization, MDR infections and intestinal microbiome (IM) of autologous HSCT patients colonized by vancomycin-resistant Enterococcus (VRE) and carbapenem-resistant Gram-negative (CRGN).

Methods

A prospective study was conducted at Hospital das Clinicas of University of Sao Paulo Brazil from 2017 to 2018. Candidates for auto-HSCT colonized by MDR received LP in capsules, 5 × 10⁹ CFU twice daily until neutropenia (NP). Rectal swabs were performed and cultured using selective media as well as PCR for carbapenemases, vanA and vanB. Stool samples for IM analysis were collected weekly as baseline (before LB use) until the NP. The V4 region of 16S rDNA gene were sequenced by Ion Torrent PGM and analyzed using alpha and β diversities by Qiime. Demographic and clinical data including previous antibiotics use were evaluated; CDC criteria was applied for colonization and infection.

Results

All of seven patients were colonized by VRE and CRGN (Table 1). Only one patient remained colonized by CRGN after 61 days of LP. Four patients developed seven bloodstream infections (BSI) during the NP, two of them by CRGN. There was no infection caused by VRE neither by LP. One patient, with low adherence to LP use (66%), died due to MDR K. pneumoniae BSI. We observed a decrease of Clostridia, Verrucomicrobiae, Blautia and an increase of Enterobacteriaceae. Baseline samples from patients who used TMP/SMX had higher concentrations of Bacteroidetes when compared with those who had not use it. The Shannon index in controls ranged 1.98–5.55 and during NP 1.15–5.99. The β diversity analysis showed no clear patterns between patients.

Conclusion

We observed a heterogeneity among IM of auto-HSCT patients prior and after LP. It was not possible to establish an IM pattern, probably, because of small number of patients. Although, clinical infections by CRGN occurred despite of LP use, no cases of colonization and infection by VRE were identified. Thus, it seems that LP is a good and safe strategy to decolonized HSCT.

Disclosures

All authors: No reported disclosures.

RHD and RHCE genotyping by next-generation sequencing is an effective strategy to identify molecular variants within sickle cell disease patients

BACKGROUND

The complexity of Rh genetic variation among sickle cell disease (SCD) patients is high. Conventional molecular assays cannot identify all genetic variants already described for the RH locus as well as foresee novel alleles. Sequencing RHD and RHCE is indicated to broaden the search for Rh genetic variants.

AIMS

To standardize the Next Generation Sequencing (NGS) strategy to assertively identify Rh genetic variants among SCD patients with serologic suspicion of Rh variants and evaluate if it can improve the transfusion support.

METHODS

Thirty-five SCD patients with unexplained Rh antibodies were enrolled. A NGS-based strategy was developed to genotype RHD and RHCE using gene-specific primers. Genotype and serological data were compared.

RESULTS

Data obtained from the NGS-based assay were gene-specific. Ten and 25 variant RHD and RHCE alleles were identified, respectively. Among all cases of unexplained Rh antibodies, 62% had been inaccurately classified by serological analysis and, of these, 73.1% were considered as relevant, as were associated with increased risk of hemolytic reactions and shortage of units suitable for transfusion.

CONCLUSION

The NGS assay designed to genotype RH coding regions was effective and accurate in identifying variants. The proposed strategy clarified the Rh phenotype of most patients, improving transfusion support.

Oxaliplatin-related thrombocytopenia

Oxaliplatin is a third generation platinum compound that inhibits DNA synthesis, mainly through intrastrandal cross-links in DNA. Most of the experience with the clinical use of this drug is derived from colorectal cancer but it is also used in other tumor types such as ovary, breast, liver and non-Hodgkin's lymphoma. Thrombocytopenia is a frequent toxicity seen during oxaliplatin treatment, occurring at any grade in up to 70% of patients and leading to delays or even discontinuation of the chemotherapy. Although myelossupression is recognized as the main cause of oxaliplatin-related thrombocytopenia, new mechanisms for this side-effect have emerged, including splenic sequestration of platelets related to oxaliplatin-induced liver damage and immune thrombocytopenia. These new pathophysiology pathways have different clinical presentations and evolution and may need specific therapeutic maneuvers. This article attempts to review this topic and provides useful clinical information for the management of oxaliplatin-related thrombocytopenia.

Direct association of socio-economic status with T-cell acute lymphoblastic leukaemia in children

Lymphoblasts from 186 consecutive untreated children <18 years were analysed by flow cytometry in Brazil. Socio-economic status was defined by family income; undernourishment by height and weight for age standardised z scores below -1.28. The observed frequencies were precursor-B (pre-B) CD10 positive acute lymphoblastic leukaemia (ALL) (CD10+) 65%, pre-B CD10 negative (CD10-) 13%, and T-ALL 18%. The typical incidence peak at age 2-5 years was observed among the CD10 positive cases. Nutritional variables were not associated with immunophenotypes. Low monthly per capita income was associated with T-immunophenotype (P=0.024). In conclusion, a direct association between unfavourable socio-economic status and the T-phenotype indicates a potential role of socio-economic factors on the genesis of ALL in children, thus confirming indirect data of the international literature.

Presence of human immunodeficiency virus (HIV) and T-lymphotropic virus type I and II (HTLV-I/II) in a haemophiliac population in Belo Horizonte, Brazil, and correlation with additional serological results

The aim of this study was to determine the prevalence of human immunodeficiency virus type 1 (HIV-1) and human T lymphotropic virus types I and II (HTLV-I/II) infections in 226 haemophiliac patients treated at Fundação Hemominas in Belo Horizonte, Minas Gerais State, Brazil, and to verify association with other serological results. Patients positive for HTLV-I/II had also a neurological, haematological and ophthalmological evaluation. Fundação Hemominas offers comprehensive care for all haemophiliac patients in Minas Gerais. Thirty-six (15.9%) of the 226 patients showed reactive results to HIV-1 [ELISA, Abbott, USA, confirmed by Western blot (WB), Cambridge Biotech, USA, and/or immunofluorescence, Fiocruz, Brazil] and 16 (7.1%) had reactive sera to HTLV-I/II (ELISA, Ortho). Eleven of these 16 (4.9%) were positive, 3/16 (1.3%) were indeterminate and 2/16 (0.9%) were negative in the HTLV WB (Cambridge Biotech). Neurological, haematological and ophthalmological examination of 9/16 patients revealed no abnormality suggestive of HTLV disease. Of the 16 patients reactive to HTLV-I/II ELISA test, six (37.5%) were also positive to HIV-1 (chi 2 = 5.92; P = 0.01). Seropositivity for HTLV-I/II and HIV-1 was associated with advancing age and positive results for hepatitis C virus (HCV), Chagas' disease (T. cruzi infection) and syphilis. No association between the presence of HTLV with type and severity of haemophilia and hepatitis B results was detected. The prevalence of antibodies against HIV-1 is approximately three times that of HTLV-I/II and a patient positive for HTLV-I/II had a significantly increased risk of being positive for HIV-1, HCV and T. cruzi.