Nicolas C. Issa

Assessing Glomerular Filtration Rate by Estimation Equations in Kidney Transplant Recipients

Surveillance of glomerular filtration rate (GFR) is crucial in the management of kidney transplant recipients. With especial emphasis on serum creatinine (SCr) calibration assay, we assessed the performance of estimation equations as compared to iothalamate GFR (iGFR) in 209 patients using the modification of diet in renal disease (MDRD), Nankivell and Cockcroft‐Gault methods. Fifty‐five percent of patients were treated with a calcineurin inhibitor (CNI) and all were taken trimethroprim‐sulfametoxazole at the time of SCr measurement. The mean iGFR was 44 ± 26 mL/min/1.73 m2. The MDRD equation showed a median difference of 0.9 mL/min/1.73 m2 with 53% of estimated GFR within 20% of iGFR. Median differences were 7.5 and 7.0 mL/min/1.73 m2 for Nankivell and Cockcroft‐Gault formulas, respectively. The accuracy of the Nankivell and Cockcroft‐Gault formulas was such that only 38% and 37% of estimations, respectively, fell within 20% of iGFR. The performance of all equations was not uniform throughout the whole range of GFR, with some deterioration at the extremes of GFR levels. In addition, good performance of the MDRD equation was seen in subjects taking CNI. In conclusion, the overall performance of the MDRD equation was superior to the Nankivell and Cockcroft‐Gault formulas in renal transplant recipients including subjects treated with CNI.

Infectious Complications of Antilymphocyte Therapies in Solid Organ Transplantation

Antilymphocyte therapies are widely used for immunosuppression in solid organ transplantation. These agents have varied mechanisms of action, with resulting differences in the intensity and duration of immunosuppression and in associated infectious complications. Induction therapy with antithymocyte globulins is associated with a greater incidence of cytomegalovirus, Epstein-Barr virus, and BK polyomavirus infections, compared with therapy with interleukin (IL)-2a receptor antagonists. However, long-term experience with the IL-2a receptor antagonists is lacking. By contrast, the treatment of graft rejection with T cell-depleting antibodies is associated with an increased risk of opportunistic infections. This is likely a reflection of the intensification of immunosuppression in the treatment of graft rejection and, often, a failure to link the use of antilymphocyte agents to prophylaxis for infection. The use of T cell-depleting agents, especially in the treatment of acute graft rejection, must be linked to monitoring and risk-adjusted prophylaxis for Pneumocystis, other fungi, Epstein-Barr virus, BK polyomavirus, and cytomegalovirus infection.

Infection in Organ Transplantation: Risk Factors and Evolving Patterns of Infection

The nature of infections after solid-organ transplantation has changed with increasingly potent immunosuppressive regimens, routine use of antimicrobial prophylaxis, and improved microbiologic diagnostic tools. New pathogens have been identified in this population including many with significant antimicrobial resistance. Intensification of immunosuppressive regimens, including the use of T- and B-lymphocyte depleting agents, presents an increased risk for infection and requires linkage to microbiologic monitoring and prophylaxis against opportunistic infections. The effect of these regimens is reflected in the increased recognition of viral and fungal infections beyond 1 year after transplantation. Donor-derived infections represent a challenge to organ transplantation in terms of microbiologic screening of donors and the need for communication among clinical centers, organ procurement organizations, and public health authorities. New approaches to microbiologic assessment of organ donors and recipients are needed. In the future, improved assays for microbiologic and immunologic monitoring will allow individualization of prophylactic strategies to reduce the risk of infection in this highly susceptible population.

Seroprotective titers against 2009 H1N1 influenza A virus after vaccination in allogeneic hematopoietic stem cell transplantation recipients.

Little data are available regarding the safety and immunologic response to pandemic H1N1 influenza vaccine in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). We measured serum antibody titers against A/California/7/2009 H1N1 using a hemagglutination inhibition assay in 82 allogeneic HSCT recipients who received the 2009 H1N1 vaccine between November 2009 and January 2010 after it became available at our institution. The median time between HSCT and vaccination was 19 months (range, 2.5-94 months), and the median time from vaccination to specimen collection was 56 days (range, 14-140 days). Seroprotective antibody titers (hemagglutination inhibition titer ≥1:40) against 2009 H1N1 influenza A virus were detected in 51% of patients. The presence of chronic graft-versus-host disease and type of conditioning regimen did not affect the rate of detection of seroprotective titers after vaccination. Patients were more likely to have a seroprotective titer the farther away from HSCT they were (adjusted odds ratio, 1.79 per year; 95% confidence interval, 1.12-2.85). Rituximab administration in the year before vaccination was associated with a lack of seroprotective titer (adjusted odds ratio, 0.11; 95% confidence interval, 0.01-0.97). The vaccine was safe and well tolerated. Strategies are needed to improve the influenza vaccine response in this population, especially those receiving immunotherapy.

Clinical potential of DAS181 for treatment of parainfluenza-3 infections in transplant recipients.

Parainfluenza virus (PIV) infections can cause serious respiratory infections and death in immunocompromised patients. No antiviral agents have proven efficacy against PIV, and therapy generally consists of supportive care. DAS181, a novel sialidase fusion protein that temporarily disables airway epithelial PIV receptors by enzymatic removal of sialic acid moieties, has been shown to inhibit infection with PIV strains in vitro and in an animal model. We describe here the clinical course of 2 immunocompromised patients with PIV‐3 infection, one with a history of lung transplantation and the other neutropenic after autologous hematopoietic stem cell transplantation for multiple myeloma. Both patients had substantial clinical improvement in respiratory and systemic symptoms after a 5‐day DAS181 treatment course, although the clinical improvement in the autologous stem cell transplantation patient also paralleled neutrophil engraftment.

Absence of Replication of Porcine Endogenous Retrovirus and Porcine Lymphotropic Herpesvirus Type 1 with Prolonged Pig Cell Microchimerism after Pig-to-Baboon Xenotransplantation

ABSTRACT Porcine endogenous retrovirus (PERV), porcine cytomegalovirus (PCMV), and porcine lymphotropic herpesvirus (PLHV) are common porcine viruses that may be activated with immunosuppression for xenotransplantation. Studies of viral replication or transmission are possible due to prolonged survival of xenografts in baboon recipients from human decay-accelerating factor transgenic or α-1,3-galactosyltransferase gene knockout miniature swine. Ten baboons underwent xenotransplantation with transgenic pig organs. Graft survival was 32 to 179 days. Recipient serial samples of peripheral blood mononuclear cells (PBMC) and plasma were analyzed for PCMV, PERV, and PLHV-1 nucleic acids and viral replication using quantitative PCR assays. The PBMC contained PERV proviral DNA in 10 animals, PLHV-1 DNA in 6, and PCMV in 2. PERV RNA was not detected in any PBMC or serum samples. Plasma PLHV-1 DNA was detected in one animal. Pig cell microchimerism (pig major histocompatibility complex class I and pig mitochondrial cytochrome c oxidase subunit II sequences) was present in all recipients with detectable PERV or PLHV-1 (85.5%). Productive infection of PERV or PLHV-1 could not be demonstrated. The PLHV-1 viral load did not increase in serum over time, despite prolonged graft survival and pig cell microchimerism. There was no association of viral loads with the nature of exogenous immune suppression. In conclusion, PERV provirus and PLHV-1 DNA were detected in baboons following porcine xenotransplantation. Viral detection appeared to be due to persistent pig cell microchimerism. There was no evidence of productive infection in recipient baboons for up to 6 months of xenograft function.

Infections Following Facial Composite Tissue Allotransplantation—Single Center Experience and Review of the Literature

We reviewed medical records of all patients (n = 4) who underwent facial composite tissue allotransplantation (FCTA) at our center between April 2009 and May 2011; data were censored in June 2012. We searched for FCTA publications and reviewed them for infectious complications and prophylaxis strategies.

A targeted peritransplant antifungal strategy for the prevention of invasive fungal disease after lung transplantation: a sequential cohort analysis.

Background Lung transplant recipients are at high risk of invasive fungal disease (IFD), particularly invasive aspergillosis and candidiasis. The antifungal strategy that optimally balances effective reduction of IFD with a minimum of toxicity remains undefined; universal triazole prophylaxis is common at lung transplantation (LT) centers, despite the well-known toxicities and costs of this approach. Methods We implemented an antifungal strategy in March 2007 targeted at LT recipients at highest risk for IFD based on our institutional epidemiology. All patients received inhaled amphotericin B during their initial LT hospitalization, bilateral lung transplant recipients received 7 to 10 days of micafungin, and only patients with growth of yeast or mold in their day-of-transplant cultures received further oral antifungal therapy tailored to their fungal isolate. Results IFD events were assessed in sequential cohorts composed of 82 lung transplant recipients before and 83 patients after the implementation of this targeted antifungal strategy. We observed a sharp decline in IFD; in the second cohort, 87%, 91%, and 96% of patients were free of IFD, invasive candidiasis, and invasive aspergillosis at 1 year. Only 19% of patients in the second cohort received systemic antifungal therapy beyond the initial LT hospitalization, and no patients experienced antifungal drug-related toxicity or IFD-associated mortality. Conclusions The targeted antifungal strategy studied seems to be a reasonable approach to reducing post-LT IFD events while limiting treatment-related toxicities and costs.

Posttransplant Lymphoproliferative Disorder Following Pancreas Transplantation

The incidence, risk factors and impact on patient and graft survival were evaluated for posttransplant lymphoproliferative disorder (PTLD) among 212 pancreas transplant recipients. Thirteen (6.1%) developed PTLD during 71 ± 27 months follow‐up. Cumulative incidences of PTLD at 1, 3, 5 and 10 years posttransplant were 4.2%, 5.3%, 6.0% and 7.0%, respectively. Incidence of PTLD was lower for recipients of simultaneous pancreas kidney compared to pancreas after kidney transplant or pancreas transplant alone, though not significantly so. Recipient Epstein–Barr virus (EBV) seronegativity and number of doses of depleting antibody therapy administered at transplant were associated with increased risk of PTLD, while recipient age, gender, transplant type, cytomegalovirus mismatch maintenance immunosuppression type and treated acute rejection were not. All 13 cases underwent immunosuppression reduction, and 10 received anti‐CD20 monoclonal antibody. During follow‐up, 10/13 (77%) responded to treatment with complete remission, while 3 (23%) died as a result of PTLD. Patient and graft survivals did not differ for recipients with and without PTLD. The strong association of PTLD with EBV‐seronegativity requires considering this risk factor when evaluating and monitoring pancreas transplant recipients. With reduction of immunosuppression and anti‐CD20 therapy, survival for pancreas transplant recipients with PTLD was substantially better than previously reported.

Sequencing and Resolution of Amplified Herpes Simplex Virus DNA with Intermediate Melting Curves as Genotype 1 or 2 by LightCycler PCR Assay

ABSTRACT DNA from 101 specimens containing herpes simplex virus (HSV) produced atypical intermediate melting curves compared with those expected for HSV type 1 or HSV type 2 subsequent to real-time PCR. Nucleic acid sequence analysis of amplified target DNA revealed 1- or 3-bp polymorphisms in the probe region which allowed designation of these viruses as HSV genotype 1 or HSV genotype 2. These two subpopulations of HSV were also identified as HSV genotype 1 or HSV genotype 2 using another commercially available PCR method. Amplified HSV target DNA producing intermediate melting curves could be designated as HSV genotype 1 or HSV genotype 2 without performing sequencing or another PCR method with 96/101 (95%) specimens by adding known intermediate HSV DNA characteristic for the two subpopulations as controls.