Population attitude and access to the healthcare system during the COVID-19 pandemic / Actitud de la población y acceso al sistema de salud durante la pandemia de COVID-19

Abstract The COVID-19 pandemic elicited important changes in community habits and behaviors, including a distancing of people from the healthcare system. The objective of this work was to understand the causes that gave rise to changes in behavior from an individual perspective in the Argentine Republic. We performed a cross-sectional, web-based survey using an online questionnaire. The survey was distributed via the WhatsApp application for smartphones among subjects across the Argentine territory using a combination of convenience and snowball sampling. We received 6176 responses. Almost 70% of respondents manifested fear of visiting a physician. One third of respondents manifested having a desire or need in at least one occasion of visiting a physician but, of these, 48% avoided it. The main reasons for avoiding visits were: 1) a recommenda tion of staying home (40%); 2) lack of access to the physician (35%); and 3) fear of contagion (26%). The most common form of consultation was through unconventional means (e-mail, telephone, or WhatsApp). One of 5 respondents had difficulties to obtain a medication prescription and 5% stopped the use of at least one medica tion. Regarding healthy habits, almost 2/3 of those surveyed stated that they became more sedentary; 11% of hypertensive patients increased their consumption of salt and 15% saw their blood pressure values increase, while 16% of dyslipidemic patients showed increased consumption of fats.

Resumen La pandemia de COVID-19 determinó un importante cambio de los hábitos y comportamientos comu nitarios, entre ellos se observó un distanciamiento de la gente del sistema de salud y el abandono de hábitos saludables. El objetivo de este trabajo fue comprender las causas que dieron lugar a dichos cambios de com portamiento desde una perspectiva individual y evaluar el impacto en el control de los factores de riesgo car diovasculares. Realizamos una encuesta utilizando un cuestionario en línea y distribuida mediante la aplicación WhatsApp entre personas de la Argentina utilizando una combinación de muestreo por conveniencia y en "bola de nieve". Recibimos 6176 respuestas, casi el 70% de los encuestados manifestaron temor de realizar una con sulta médica. Un tercio de los encuestados manifestó haber tenido necesidad de ir al médico en al menos una oportunidad desde el inicio de la pandemia, pero de éstos, el 48% evitó la visita. Las principales razones para evitarla: 1) la recomendación de quedarse en casa (40%); 2) dificultad para acceder al sistema de salud (35%); y 3) miedo al contagio (26%). La forma de consulta más común fue a través de medios no convencionales (correo electrónico, teléfono o WhatsApp). Uno de cada 5 encuestados tuvo dificultades para obtener una receta y el 5% dejó de tomar al menos un medicamento. En cuanto a los hábitos saludables, casi 2/3 de los encuestados afirmaron volverse más sedentarios, el 11% de los hipertensos aumentó su consumo de sal y el 15% aumentó sus valores de presión arterial, mientras que el 16% de los dislipidémicos mostró un mayor consumo de grasas.

Population attitude and access to the healthcare system during the COVID-19 pandemic.

The COVID-19 pandemic elicited important changes in community habits and behaviors, including a distancing of people from the healthcare system. The objective of this work was to understand the causes that gave rise to changes in behavior from an individual perspective in the Argentine Republic. We performed a cross-sectional, web-based survey using an online questionnaire. The survey was distributed via the WhatsApp application for smartphones among subjects across the Argentine territory using a combination of convenience and snowball sampling. We received 6176 responses. Almost 70% of respondents manifested fear of visiting a physician. One third of respondents manifested having a desire or need in at least one occasion of visiting a physician but, of these, 48% avoided it. The main reasons for avoiding visits were: 1) a recommendation of staying home (40%); 2) lack of access to the physician (35%); and 3) fear of contagion (26%). The most common form of consultation was through unconventional means (e-mail, telephone, or WhatsApp). One of 5 respondents had difficulties to obtain a medication prescription and 5% stopped the use of at least one medication. Regarding healthy habits, almost 2/3 of those surveyed stated that they became more sedentary; 11% of hypertensive patients increased their consumption of salt and 15% saw their blood pressure values increase, while 16% of dyslipidemic patients showed increased consumption of fats.

La pandemia de COVID-19 determinó un importante cambio de los hábitos y comportamientos comunitarios, entre ellos se observó un distanciamiento de la gente del sistema de salud y el abandono de hábitos saludables. El objetivo de este trabajo fue comprender las causas que dieron lugar a dichos cambios de comportamiento desde una perspectiva individual y evaluar el impacto en el control de los factores de riesgo cardiovasculares. Realizamos una encuesta utilizando un cuestionario en línea y distribuida mediante la aplicación WhatsApp entre personas de la Argentina utilizando una combinación de muestreo por conveniencia y en "bola de nieve". Recibimos 6176 respuestas, casi el 70% de los encuestados manifestaron temor de realizar una consulta médica. Un tercio de los encuestados manifestó haber tenido necesidad de ir al médico en al menos una oportunidad desde el inicio de la pandemia, pero de éstos, el 48% evitó la visita. Las principales razones para evitarla: 1) la recomendación de quedarse en casa (40%); 2) difi cultad para acceder al sistema de salud (35%); y 3) miedo al contagio (26%). La forma de consulta más común fue a través de medios no convencionales (correo electrónico, teléfono o WhatsApp). Uno de cada 5 encuestados tuvo dificultades para obtener una receta y el 5% dejó de tomar al menos un medicamento. En cuanto a los hábitos saludables, casi 2/3 de los encuestados afirmaron volverse más sedentarios, el 11% de los hipertensos aumentó su consumo de sal y el 15% aumentó sus valores de presión arterial, mientras que el 16% de los dislipidémicos mostró un mayor consumo de grasas.

RACCOVID-19: primer Registro Argentino de Complicaciones Cardiovasculares en pacientes con COVID-19 / RACCOVID-19: First Argentine Registry of Cardiovascular Complications in COVID-19 Patients

RESUMEN Introducción: La enfermedad por coronavirus (COVID-19) ha causado una de las mayores pandemias conocidas al día de la fecha. La Sociedad Argentina de Cardiología (SAC) y la Federación Argentina de Cardiología (FAC) elaboraron el primer Registro Argentino de Complicaciones Cardiovasculares en pacientes con COVID-19 (RACCOVID-19), con el propósito de relevar, a nivel nacional, su impacto en la evolución hospitalaria de estos pacientes. Objetivos: Documentar la aparición de complicaciones cardiovasculares en pacientes internados por COVID-19 y evaluar predictores de riesgo de dichas complicaciones y su impacto pronóstico. Material y Métodos: Se incluyen datos de 2750 pacientes en 50 centros de 11 provincias del país, desde el 18 de mayo hasta el 31 de octubre de 2020. Resultados: La edad promedio fue de 57±18 años y hubo predominio de sexo masculino (60,2%). La tasa de complicaciones cardiovasculares fue del 15,3%. La insuficiencia cardíaca (43,5%), las arritmias (33,5%) y el daño miocárdico (31,1%) fueron las complicaciones más frecuentes. La mortalidad fue del 19,3%. Un modelo de predicción de sobrevida en la etapa hospitalaria incluyó las siguientes variables: edad, sexo masculino, valores de hematocrito y creatinina al ingreso, existencia de antecedentes patológicos, formas de presentación de COVID-19 graves y presencia de complicaciones cardiovasculares. Conclusiones: El registro RACCOVID-19 mostró una tasa de complicaciones cardiovasculares del 15,3%. La mortalidad total del registro fue del 19,3% y las complicaciones cardiovasculares junto con otras variables de presentación, así como la gravedad del cuadro clínico de COVID-19, forman parte de un perfil de riesgo clínico asociado a mayor mortalidad.

ABSTRACT Background: Coronavirus disease (COVID-19) has caused one of the largest pandemics known to date. The Argentine Society of Cardiology (SAC) and the Argentine Federation of Cardiology (FAC) have developed the First Argentine Registry of Cardiovascular Complications in COVID-19 patients (RACCOVID-19) with the purpose of performing a nationwide review of their impact in the in-hospital evolution of these patients. Objectives: The aim of this study was to record cardiovascular complications in hospitalized patients for COVID-19, and to evaluate risk predictors of these complications and their prognostic impact. Methods: A total of 2750 patients from 50 centers in 11 provinces of the country were included from May 18 to October 31, 2020. Results: Mean age was 57±18 years, with a prevalence of male gender (60.2%). Cardiovascular complications occurred in 15.3% of cases. Heart failure (43.5%), arrhythmias (33.5%) and myocardial injury (31.1%) were the most relevant complications. Mortality was 19.3%, and a predictive model of in-hospital survival included age, male gender, admission hematocrit and creatinine, history of previous diseases, severe forms of COVID-19 presentation and cardiovascular complications. Conclusions: The RACCOVID-19 registry showed 15.3% of cardiovascular complications. Overall mortality was 19.3% and cardiovascular complications together with other presentation variables as well as the clinical severity of COVID-19, are part of a clinical risk profile associated with higher mortality.

Discontinuación de la anticoagulación y sus factores asociados en la fibrilación auricular / Discontinuation of Anticoagulation and Associated Factors in Atrial Fibrillation

RESUMEN Introducción: El objetivo del estudio fue comparar si existe diferencia en la discontinuación de los antagonistas de la vitamina K y los anticoagulantes directos y evaluar sus factores asociados en la fibrilación auricular de reciente diagnóstico. Material y métodos: Se realizó un estudio de cohortes prospectivo. El período de seguimiento fue de 12 meses. Debido a que la asignación del tratamiento no fue al azar, se realizó una ponderación por puntaje de propensión considerando las características basales potencialmente asociadas a la exposición y al resultado. Se evaluaron factores asociados a la discontinuación del anticoagulante mediante un modelo de Cox ponderado. Se incluyeron 379 pacientes con una edad media de 78 años (DE ± 9) y una prevalencia de sexo femenino del 58%. La mediana de seguimiento fue de 362 días (rango intercuartilo: 347-370 días). La pérdida de seguimiento fue del 1%. Resultados: El modelo de tiempo a la discontinuación del tratamiento anticoagulante ponderado evidenció un HR crudo de 1,40 (IC 95%: 0,79-2,48) y uno ajustado por edad, tipo de fibrilación auricular, ablación por radiofrecuencia, sangrado, cantidad de fármacos crónicos y de consultas médicas durante el seguimiento de 1,26 (IC 95%: 0,75-2,12) para el grupo tratado con anticoagulantes directos en comparación con el tratado con antagonistas de la vitamina K. Conclusiones: En nuestro medio, la discontinuación de los anticoagulantes en la fibrilación auricular no se asociaría con el tipo de fármaco empleado, la edad o el tipo de arritmia. La ablación por radiofrecuencia, la ocurrencia de sangrado y el número de consultas médicas se asociaron con la discontinuación.

ABSTRACT Background: The aim of the study was to compare if there were any differences between discontinuation of vitamin K antagonists and direct oral anticoagulants and evaluate the factors associated with such discontinuation in newly diagnosed nonvalvular atrial fibrillation. Methods: We conducted a prospective cohort study. Patients were followed-up for 12 months. Since the assignment of anticoagulation treatment was not randomized, propensity score weighting was used considering the baseline characteristics potentially associated with the exposure and result. Factors associated with the discontinuation of anticoagulant treatment were analyzed with a weighted Cox proportional hazards model. A total of 379 patients were included; mean age was 78 years (SD ± 9) and 58% were women. Median follow-up was 362 days (interquartile range: 347-370 days) and 1% was lost to follow-up. Results: The model of time to discontinuation based on inverse probability treatment weighting showed a crude HR of 1.40 (95% CI, 0.79-2.48, and of 1.26 (95% CI, 0.75-2,12, after adjustment for age, type of atrial fibrillation, radiofrequency catheter ablation, bleeding, number of chronic medications and number of medical visits during follow-up for the group treated with direct oral anticoagulants compared with the vitamin K antagonists. Conclusions: In our setting, anticoagulant discontinuation in nonvalvular atrial fibrillation would not be associated with the type of drug used, age or type of atrial fibrillation. Radiofrequency catheter ablation, bleeding events and the number of medical visits were associated with treatment discontinuation.

Anti-C5 Antibody Tesidolumab Reduces Early Antibody-mediated Rejection and Prolongs Survival in Renal Xenotransplantation.

OBJECTIVE: Pig-to-primate renal xenotransplantation is plagued by early antibody-mediated graft loss which precludes clinical application of renal xenotransplantation. We evaluated whether temporary complement inhibition with anti-C5 antibody Tesidolumab could minimize the impact of early antibody-mediated rejection in rhesus monkeys receiving pig kidneys receiving costimulatory blockade-based immunosuppression. METHODS: Double (Gal and Sda) and triple xenoantigen (Gal, Sda, and SLA I) pigs were created using CRISPR/Cas. Kidneys from DKO and TKO pigs were transplanted into rhesus monkeys that had the least reactive crossmatches. Recipients received anti-C5 antibody weekly for 70 days, and T cell depletion, anti-CD154, mycophenolic acid, and steroids as baseline immunosuppression (n = 7). Control recipients did not receive anti-C5 therapy (n = 10). RESULTS: Temporary anti-C5 therapy reduced early graft loss secondary to antibody-mediated rejection and improved graft survival (P < 0.01). Deleting class I MHC (SLA I) in donor pigs did not ameliorate early antibody-mediated rejection (table). Anti-C5 therapy did not allow for the use of tacrolimus instead of anti-CD154 (table), prolonging survival to a maximum of 62 days. CONCLUSION: Inhibition of the C5 complement subunit prolongs renal xenotransplant survival in a pig to non-human primate model.

The Influence of Larval Stage and Density on Oviposition Site-Selection Behavior of the Afrotropical Malaria Mosquito Anopheles coluzzii (Diptera: Culicidae).

In the selection of oviposition sites female mosquitoes use various cues to assess site quality to optimize survival of progeny. The presence of conspecific larvae influences this process. Interactive effects of oviposition site selection were studied in the malaria mosquito Anopheles coluzzii Coetzee & Wilkerson in dual- and no-choice assays, by exposing single gravid mosquitoes to oviposition cups containing 1) larvae of different developmental stages, 2) larvae-conditioned water (LCW), and 3) cups where visual cues of conspecific larvae were absent. Early-stage conspecific larvae had a positive effect on the oviposition response. By contrast, late stages of conspecific larvae had a negative effect. Oviposition choice was dependent on larval density. Moreover, in oviposition cups where larvae were hidden from view, late-stage larvae had a significant negative effect on oviposition suggesting the involvement of olfactory cues. LCW had no effect on oviposition response, indicating involvement of chemicals produced by larvae in vivo. It is concluded that the presence of larvae in a breeding site affects the oviposition response depending on the development stage of the larvae. These responses appear to be mediated by olfactory cues emitted by the larval habitat containing live larvae, resulting in the enhanced reproductive fitness of the females.

Renal Function and Outcomes With Dabigatran Dual Antithrombotic Therapy in Atrial Fibrillation Patients After PCI.

OBJECTIVES: The study sought to evaluate the effect of dabigatran dual therapy versus warfarin triple therapy across categories of renal function in the RE-DUAL PCI (Randomized Evaluation of Dual Antithrombotic Therapy with Dabigatran versus Triple Therapy with Warfarin in Patients with Nonvalvular Atrial Fibrillation Undergoing Percutaneous Coronary Intervention) trial. BACKGROUND: The RE-DUAL PCI (NCT02164864) trial of patients with atrial fibrillation undergoing percutaneous coronary intervention reported that dabigatran dual therapy (110 or 150 mg twice daily, plus clopidogrel or ticagrelor) reduced the primary endpoint of major bleeding events (MBE) or clinically relevant nonmajor bleeding events (CRNMBE) compared with warfarin triple therapy, with noninferiority in overall thromboembolic events. METHODS: Risk of a first MBE or CRNMBE and the composite of death or thromboembolic event (DTE) or unplanned revascularization were evaluated in 2,725 patients according to baseline creatinine clearance (CrCl) categories: 30 to <50, 50 to <80, and ≥80 ml/min. RESULTS: Compared with warfarin, dabigatran 110 mg dual therapy reduced risk of MBE or CRNMBE across all categories of CrCl (p for interaction = 0.19). Dabigatran 150 mg dual therapy reduced risk of MBE or CRNMBE regardless of the CrCl category (p for interaction = 0.31). Risk of DTE or unplanned revascularization was similar to warfarin triple therapy for dabigatran 110 mg dual therapy across all CrCl categories. Dabigatran 150 mg dual therapy versus warfarin triple therapy had similar risk for DTE or unplanned revascularization in patients with CrCl 30 to <80 ml/min and lower risk at CrCl ≥80 ml/min (p for interaction = 0.02). CONCLUSIONS: In the RE-DUAL PCI trial, dabigatran dual therapy reduced bleeding events versus warfarin triple therapy irrespective of renal function, with overall similar risks of thromboembolic events but lower risks with dabigatran 150 mg in patients with normal CrCl.

Xenoantigen Deletion and Chemical Immunosuppression Can Prolong Renal Xenograft Survival.

OBJECTIVE: Xenotransplantation using pig organs could end the donor organ shortage for transplantation, but humans have xenoreactive antibodies that cause early graft rejection. Genome editing can eliminate xenoantigens in donor pigs to minimize the impact of these xenoantibodies. Here we determine whether an improved cross-match and chemical immunosuppression could result in prolonged kidney xenograft survival in a pig-to-rhesus preclinical model. METHODS: Double xenoantigen (Gal and Sda) knockout (DKO) pigs were created using CRISPR/Cas. Serum from rhesus monkeys (n = 43) was cross-matched with cells from the DKO pigs. Kidneys from the DKO pigs were transplanted into rhesus monkeys (n = 6) that had the least reactive cross-matches. The rhesus recipients were immunosuppressed with anti-CD4 and anti-CD8 T-cell depletion, anti-CD154, mycophenolic acid, and steroids. RESULTS: Rhesus antibody binding to DKO cells is reduced, but all still have positive CDC and flow cross-match. Three grafts were rejected early at 5, 6, and 6 days. Longer survival was achieved in recipients with survival to 35, 100, and 435 days. Each of the 3 early graft losses was secondary to IgM antibody-mediated rejection. The 435-day graft loss occurred secondary to IgG antibody-mediated rejection. CONCLUSIONS: Reducing xenoantigens in donor pigs and chemical immunosuppression can be used to achieve prolonged renal xenograft survival in a preclinical model, suggesting that if a negative cross-match can be obtained for humans then prolonged survival could be achieved.

CRISPR/Cas and recombinase-based human-to-pig orthotopic gene exchange for xenotransplantation.

BACKGROUND: Tools for genome editing in pigs are improving rapidly so that making precise cuts in DNA for the purposes of deleting genes is straightforward. Development of means to replace pig genes with human genes with precision is very desirable for the future development of donor pigs for xenotransplantation. MATERIALS AND METHODS: We used Cas9 to cut pig thrombomodulin (pTHBD) and replace it with a plasmid containing a promoterless antibiotic selection marker and the exon for human thrombomodulin. PhiC31 recombinase was used to remove the antibiotic selection marker to create porcine aortic endothelial cells expressing human instead of pTHBD, driven by the endogenous pig promoter. RESULTS: The promoterless selection cassette permitted efficient enrichment of cells containing correctly inserted transgene. Recombinase treatment of selected cells excised the resistance marker permitting expression of the human transgene by the endogenous pTHBD promoter. Gene regulation was maintained after gene replacement because pig endogenous promoter was kept intact in the correct position. CONCLUSIONS: Cas9 and recombinase technology make orthotopic human for pig gene exchange feasible and pave the way for creation of pigs with human genes that can be expressed in the appropriate tissues preserving gene regulation.

Humoral Reactivity of Renal Transplant-Waitlisted Patients to Cells From GGTA1/CMAH/B4GalNT2, and SLA Class I Knockout Pigs.

BACKGROUND: Antipig antibodies are a barrier to clinical xenotransplantation. We evaluated antibody binding of waitlisted renal transplant patients to 3 glycan knockout (KO) pig cells and class I swine leukocyte antigens (SLA). METHODS: Peripheral blood mononuclear cells from SLA identical wild type (WT), α1, 3-galactosyltransferase (GGTA1) KO, GGTA1/ cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) KO, and GGTA1/ CMAH /b1,4 N-acetylgalactosaminyl transferase (B4GalNT2) KO pigs were screened for human antibody binding using flow cytometric crossmatch (FCXM). Sera from 820 patients were screened on GGTA1/CMAH/B4GalNT2 KO cells and a subset with elevated binding was evaluated further. FCXM was performed on SLA intact cells and GGTA1/SLA class I KO cells after depletion with WT pig RBCs to remove cell surface reactive antibodies, but leave SLA antibodies. Lastly, human and pig reactive antibodies were eluted and tested for cross-species binding and reactivity to single-antigen HLA beads. RESULTS: Sequential glycan KO modifications significantly reduce antibody binding of waitlisted patients. Sera exhibiting elevated binding without reduction after depletion with WT RBCs demonstrate reduced binding to SLA class I KO cells. Human IgG, eluted from human and pig peripheral blood mononuclear cells, interacted across species and bound single-antigen HLA beads in common epitope-restricted patterns. CONCLUSIONS: Many waitlisted patients have minimal xenoreactive antibody binding to the triple KO pig, but some HLA antibodies in sensitized patients cross-react with class I SLA. SLA class I is a target for genome editing in xenotransplantation.

Eliminating Xenoantigen Expression on Swine RBC.

BACKGROUND: The rapidly improving tools of genetic engineering may make it possible to overcome the humoral immune barrier that prevents xenotransplantation. We hypothesize that levels of human antibody binding to donor tissues from swine must approximate the antibody binding occurring in allotransplantation. It is uncertain if this is an attainable goal. Here we perform an initial analysis of this issue by comparing human antibody binding to red blood cells (RBC) isolated from knockout swine and to allogeneic or autologous human RBC. METHODS: Human sera were incubated with RBC isolated from various genetically engineered swine or from humans. The level of IgG and IgM binding to these cells were compared using either flow cytometry or a novel mass spectrometric assay. RESULTS: Mass spectroscopic quantitation of human antibody binding demonstrated that as few as 3 gene inactivations can reduce the levels human antibody binding to swine RBC that is as low as autologous human RBC. Flow cytometry showed that RBC from 2-gene knockout swine exhibited less human antibody binding than human blood group O allogeneic RBC in 22% of tested sera. Deletion of a third gene from pigs resulted in 30% of human samples having less IgG and IgM RBC xenoreactivity than alloreactivity. CONCLUSIONS: Xenoantigenicity of swine RBC can be eliminated via gene disruption. These results suggest that the gene knockout approach may be able reduce antigenicity in other pig tissues to levels that enable the xenotransplantation humoral barrier to be overcome.

Silencing porcine genes significantly reduces human-anti-pig cytotoxicity profiles: an alternative to direct complement regulation.

UNLABELLED: The future of solid organ transplantation is challenged by an increasing shortage of available allografts. Xenotransplantation of genetically modified porcine organs offers an answer to this problem. Strategies of genetic modification have 'humanized' the porcine model towards clinical relevance. Most notably, these approaches have aimed at either antigen reduction or human transgene expression. The object of this study was to evaluate the relative effects of both antigen reduction and direct complement regulation on the human-anti-porcine complement dependent cytotoxicity response. Genetically modified animals were created through CRISPR/Cas9-directed mutation and human transgene delivery. Pigs doubly deficient in GGTA1 and CMAH genes were compared to pigs of the same background that expressed a human complement regulatory protein (hCRP). A third animal was made deficient in GGTA1, CMAH and B4GalNT2 gene expression. Cells from these animals were subjected to measures of human antibody binding and antibody-mediated complement-dependent cytotoxicity by flow cytometry. Human IgG and IgM antibody binding was unchanged between the double knockout and the transgenic hCRP double knockout pig. IgG and IgM binding was reduced by 49.1 and 43.2 % respectively by silencing the B4GalNT2 gene. Compared to the double knockout, human anti-porcine cytotoxicity was reduced by 8 % with the addition of a hCRP (p = .032); It was reduced by 21 % with silencing the B4GalNT2 gene (p = .012). CONCLUSIONS: Silencing the GGTA1, CMAH and B4GalNT2 genes in pigs achieved a significant antigen reduction. Changing the porcine carbohydrate profile effectively mediates human antibody-mediated complement dependent cytoxicity.

Silencing the porcine iGb3s gene does not affect Galα3Gal levels or measures of anticipated pig-to-human and pig-to-primate acute rejection.

BACKGROUND: The Galα(1,3)Gal epitope (α-GAL), created by α-1,3-glycosyltransferase-1 (GGTA1), is a major xenoantigen causing hyperacute rejection in pig-to-primate and pig-to-human xenotransplantation. In response, GGTA1 gene-deleted pigs have been generated. However, it is unclear whether there is a residual small amount of α-Gal epitope expressed in GGTA1(-/-) pigs. Isoglobotrihexosylceramide synthase (iGb3s), another member of the glycosyltransferase family, catalyzes the synthesis of isoglobo-series glycosphingolipids with an α-GAL-terminal disaccharide (iGb3), creating the possibility that iGb3s may be a source of α-GAL epitopes in GGTA1(-/-) animals. The objective of this study was to examine the impact of silencing the iGb3s gene (A3GalT2) on pig-to-primate and pig-to-human immune cross-reactivity by creating and comparing GGTA1(-/-) pigs to GGTA1(-/-) - and A3GalT2(-/-) -double-knockout pigs. METHODS: We used the CRISPR/Cas 9 system to target the GGTA1 and A3GalT2 genes in pigs. Both GGTA1 and A3GalT2 genes are functionally inactive in humans and baboons. CRISPR-treated cells used directly for somatic cell nuclear transfer produced single- and double-gene-knockout piglets in a single pregnancy. Once grown to maturity, the glycosphingolipid profile (including iGb3) was assayed in renal tissue by normal-phase liquid chromatography. In addition, peripheral blood mononuclear cells (PBMCs) were subjected to (i) comparative cross-match cytotoxicity analysis against human and baboon serum and (ii) IB4 staining for α-GAL/iGb3. RESULTS: Silencing of the iGb3s gene significantly modulated the renal glycosphingolipid profile and iGb3 was not detected. Moreover, the human and baboon serum PBMC cytotoxicity and α-GAL/iGb3 staining were unchanged by iGb3s silencing. CONCLUSIONS: Our data suggest that iGb3s is not a contributor to antibody-mediated rejection in pig-to-primate or pig-to-human xenotransplantation. Although iGb3s gene silencing significantly changed the renal glycosphingolipid profile, the effect on Galα3Gal levels, antibody binding, and cytotoxic profiles of baboon and human sera on porcine PBMCs was neutral.

Immunogenicity of Renal Microvascular Endothelial Cells From Genetically Modified Pigs.

BACKGROUND: Disrupting the porcine GGTA1 and CMAH genes [double knockout (DKO)] that produce the gal-α(1,3)-gal and N-glycolylneuraminic acid xenoantigens reduces human antibody binding to porcine peripheral blood mononuclear cells. It is important to examine rejection pathways at an organ-specific level. The object of this study is to evaluate the human preformed antibody reactivity against DKO renal microvascular endothelial cells (RMEC) in vitro. METHODS: Characteristics of DKO RMEC were analyzed using flow cytometry. Human IgG/M binding to primary RMEC, immortalized RMEC (iRMEC), and iRMEC-deficient in B4GALNT2 genes were examined using flow cytometric crossmatch assay. RESULTS: Porcine RMEC expressed gal-α(1,3)-gal, N-glycolylneuraminic acid, and Dolichos biflorus agglutinin glycans recognized by human preexisting antibodies in humans. Antigenicity of DKO RMEC was lower than GGTA1 KO RMEC. The disruption of B4GALNT2 gene in DKO iRMEC further reduced human IgG/IgM binding. CONCLUSIONS: Silencing the porcine GGTA1, CMAH, and B4GALNT2 genes is an effective strategy to reduce human preformed antibody binding to RMEC. Porcine RMEC will be a useful reagent for the further study of xenoimmunology.

Silencing Porcine CMAH and GGTA1 Genes Significantly Reduces Xenogeneic Consumption of Human Platelets by Porcine Livers.

BACKGROUND: A profound thrombocytopenia limits hepatic xenotransplantation in the pig-to-primate model. Porcine livers also have shown the ability to phagocytose human platelets in the absence of immune-mediated injury. Recently, inactivation of the porcine ASGR1 gene has been shown to decrease this phenomenon. Inactivating GGTA1 and CMAH genes has reduced the antibody-mediated barrier to xenotransplantation; herein, we describe the effect that these modifications have on xenogeneic consumption of human platelets in the absence of immune-mediated graft injury. METHODS: Wild type (WT), ASGR1, GGTA1, and GGTA1CMAH knockout pigs were compared for their xenogeneic hepatic consumption of human platelets. An in vitro assay was established to measure the association of human platelets with liver sinusoidal endothelial cells (LSECs) by immunohistochemistry. Perfusion models were used to measure human platelet uptake in livers from WT, ASGR1, GGTA1, and GGTA1 CMAH pigs. RESULTS: GGTA1, CMAH LSECs exhibited reduced levels of human platelet binding in vitro when compared with GGTA1 and WT LSECs. In a continuous perfusion model, GGTA1 CMAH livers consumed fewer human platelets than GGTA1 and WT livers. GGTA1 CMAH livers also consumed fewer human platelets than ASGR1 livers in a single-pass model. CONCLUSIONS: Silencing the porcine carbohydrate genes necessary to avoid antibody-mediated rejection in a pig-to-human model also reduces the xenogeneic consumption of human platelets by the porcine liver. The combination of these genetic modifications may be an effective strategy to limit the thrombocytopenia associated with pig-to-human hepatic xenotransplantation.

The fate of human platelets exposed to porcine renal endothelium: a single-pass model of platelet uptake in domestic and genetically modified porcine organs.

BACKGROUND: Thrombocytopenia may represent a significant challenge to the clinical application of solid-organ xenotransplantation. When studied in a pig-to-primate model, consumptive coagulopathy has challenged renal xenografts. New strategies of genetic manipulation have altered porcine carbohydrate profiles to significantly reduce human antibody binding to pig cells. As this process continues to eliminate immunologic barriers to clinical xenotransplantation, the relationship between human platelets and pig organs must be considered. METHODS: Genetically modified pigs that were created by the CRISPR/Cas9 system with α-1,3-galactosyltransferase (GGTA1)(-/-) or GGTA1(-/-) cytidine monophosphate-N-acetylneuraminic acid hydroxylase(-/-) phenotype, as well as domestic pigs, were used in this study. Autologous porcine platelets were isolated from donor animal blood collection, and human platelets were obtained from a blood bank. Platelets were fluorescently labeled and in a single-pass model, human, or autologous platelets were perfused through porcine organs at a constant concentration and controlled temperature. Platelet uptake was measured by sampling venous output and measuring sample florescence against input florescence. In vitro study of the interaction between human platelets and porcine endothelial cells was accomplished by immunohistochemical stain and confocal microscopy. RESULTS: Differences between human and autologous platelet loss through the porcine kidney were not significant in any genetic background tested (WT P = 0.15, GGTA1(-/-)P = 0.12, GGTA1(-/-) cytidine monophosphate-N-acetylneuraminic acid hydroxylase(-/-)P = 0.25). The unmodified porcine liver consumed human platelets in a single-pass model of platelet perfusion in fewer than 10 min. WT suprahepatic inferior vena cava fluoresce reached a maximum of 76% of input fluoresce within the human platelet cohort and was significantly lower than the autologous platelet control cohort (P = 0.001). Confocal microscopic analysis did not demonstrate a significant association between human platelets and porcine renal endothelial cells compared with porcine liver endothelial positive controls. CONCLUSIONS: Our results suggest that in the absence of immunologic injury, human platelets respond in a variable fashion to organ-specific porcine endothelial surfaces. Human platelets are not removed from circulation by exposure to porcine renal endothelium but are removed by unmodified porcine hepatic endothelium. Kidneys possessing genetic modifications currently relevant to clinical xenotransplantation failed to consume human platelets in an isolated single-pass model. Human platelets did not exhibit significant binding to renal endothelial cells by in vitro assay.

Reduced human platelet uptake by pig livers deficient in the asialoglycoprotein receptor 1 protein.

BACKGROUND: The lethal thrombocytopenia that accompanies liver xenotransplantation is a barrier to clinical application. Human platelets are bound by the asialoglycoprotein receptor (ASGR) on pig sinusoidal endothelial cells and phagocytosed. Inactivation of the ASGR1 gene in donor pigs may prevent xenotransplantation-induced thrombocytopenia. METHODS: Transcription activator-like effector nucleases (TALENs) were targeted to the ASGR1 gene in pig liver-derived cells. ASGR1 deficient pig cells were used for somatic cell nuclear transfer (SCNT). ASGR1 knock out (ASGR1-/-) fetal fibroblasts were used to produce healthy ASGR1 knock out piglets. Human platelet uptake was measured in ASGR1+/+ and ASGR1-/- livers. RESULTS: Targeted disruption of the ASGR1 gene with TALENs eliminated expression of the receptor. ASGR1-/- livers phagocytosed fewer human platelets than domestic porcine livers during perfusion. CONCLUSIONS: The use of TALENs in liver-derived cells followed by SCNT enabled the production of healthy homozygous ASGR1 knock out pigs. Livers from ASGR1-/- pigs exhibit decreased human platelet uptake. Deletion of the ASGR1 gene is a viable strategy to diminish platelet destruction in pig-to-human xenotransplantation.

Evaluation of human and non-human primate antibody binding to pig cells lacking GGTA1/CMAH/ß4GalNT2 genes.

BACKGROUND: Simultaneous inactivation of pig GGTA1 and CMAH genes eliminates carbohydrate xenoantigens recognized by human antibodies. The ß4GalNT2 glycosyltransferase may also synthesize xenoantigens. To further characterize glycan-based species incompatibilities, we examined human and non-human primate antibody binding to cells derived from genetically modified pigs lacking these carbohydrate-modifying genes. METHODS: The Cas9 endonuclease and gRNA were used to create pigs lacking GGTA1, GGTA1/CMAH, or GGTA1/CMAH/ß4GalNT2 genes. Peripheral blood mononuclear cells were isolated from these animals and examined for binding to IgM and IgG from humans, rhesus macaques, and baboons. RESULTS: Cells from GGTA1/CMAH/ß4GalNT2 deficient pigs exhibited reduced human IgM and IgG binding compared to cells lacking both GGTA1 and CMAH. Non-human primate antibody reactivity with cells from the various pigs exhibited a slightly different pattern of reactivity than that seen in humans. Simultaneous inactivation of the GGTA1 and CMAH genes increased non-human primate antibody binding compared to cells lacking either GGTA1 only or to those deficient in GGTA1/CMAH/ß4GalNT2. CONCLUSIONS: Inactivation of the ß4GalNT2 gene reduces human and non-human primate antibody binding resulting in diminished porcine xenoantigenicity. The increased humoral immunity of non-human primates toward GGTA1-/CMAH-deficient cells compared to pigs lacking either GGTA1 or GGTA1/CMAH/ß4GalNT2 highlights the complexities of carbohydrate xenoantigens and suggests potential limitations of the non-human primate model for examining some genetic modifications. The progressive reduction of swine xenoantigens recognized by human immunoglobulin through inactivation of pig GGTA1/CMAH/ß4GalNT2 genes demonstrates that the antibody barrier to xenotransplantation can be minimized by genetic engineering.

Identification of human semiochemicals attractive to the major vectors of onchocerciasis.

BACKGROUND: Entomological indicators are considered key metrics to document the interruption of transmission of Onchocerca volvulus, the etiological agent of human onchocerciasis. Human landing collection is the standard employed for collection of the vectors for this parasite. Recent studies reported the development of traps that have the potential for replacing humans for surveillance of O. volvulus in the vector population. However, the key chemical components of human odor that are attractive to vector black flies have not been identified. METHODOLOGY/PRINCIPAL FINDINGS: Human sweat compounds were analyzed using GC-MS analysis and compounds common to three individuals identified. These common compounds, with others previously identified as attractive to other hematophagous arthropods were evaluated for their ability to stimulate and attract the major onchocerciasis vectors in Africa (Simulium damnosum sensu lato) and Latin America (Simulium ochraceum s. l.) using electroantennography and a Y tube binary choice assay. Medium chain length carboxylic acids and aldehydes were neurostimulatory for S. damnosum s.l. while S. ochraceum s.l. was stimulated by short chain aliphatic alcohols and aldehydes. Both species were attracted to ammonium bicarbonate and acetophenone. The compounds were shown to be attractive to the relevant vector species in field studies, when incorporated into a formulation that permitted a continuous release of the compound over time and used in concert with previously developed trap platforms. CONCLUSIONS/SIGNIFICANCE: The identification of compounds attractive to the major vectors of O. volvulus will permit the development of optimized traps. Such traps may replace the use of human vector collectors for monitoring the effectiveness of onchocerciasis elimination programs and could find use as a contributing component in an integrated vector control/drug program aimed at eliminating river blindness in Africa.

Efficient generation of genetically distinct pigs in a single pregnancy using multiplexed single-guide RNA and carbohydrate selection.

BACKGROUND: Manipulating the pig genome to increase compatibility with human biology may facilitate the clinical application of xenotransplantation. Genetic modifications to pig cells have been made by sequential recombination in fetal fibroblasts and liver-derived cells followed by cross-breeding or somatic cell nuclear transfer. The generation of pigs for research or organ donation by these methods is slow, expensive and requires technical expertise. A novel system incorporating the bacterial nuclease Cas9 and single-guide RNA targeting a 20 nucleotide site within a gene can be expressed from a single plasmid leading to a double-strand break and gene disruption. Coexpression of multiple unique single-guide RNA can modify several genetic loci in a single step. We describe a process for increasing the efficiency of selecting cells with multiple genetic modifications. METHODS: We used the CRISPR/Cas system to target the GGTA1, CMAH and putative iGb3S genes in pigs that have been naturally deleted in humans. Cells lacking galactose α-1,3 galactose (α-Gal) were negatively selected by an IB4 lectin/magnetic bead. α-Gal negative multiplexed single-guide RNA-treated cells were used for somatic cell nuclear transfer (SCNT) and transferred to fertile sows. We examined the levels of α-Gal and Neu5Gc expression of 32 day fetuses and piglets and analyzed the targeted genes by DNA sequencing. RESULTS: Liver-derived cells treated with multiple single-guide RNA and selected for an α-Gal null phenotype were significantly more likely to also carry mutations in simultaneously targeted genes. Multiplex single-guide RNA-treated cells used directly for SCNT without further genetic selection produced piglets with deletions in the targeted genes but also created double- and triple-gene KO variations. CRISPR/Cas-treated cells grew normally and yielded normal liters of healthy piglets via somatic cell nuclear transfer. CONCLUSIONS: The CRISPR/Cas system allows targeting of multiple genes in a single reaction with the potential to create pigs of one genetic strain or multiple genetic modifications in a single pregnancy. The application of this phenotypic selection strategy with multiplexed sgRNA and the Cas9 nuclease has accelerated our ability to produce and evaluate pigs important to xenotransplantation.