Infection in Organ Transplantation.

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Prolonged Survival Following Pig-to-Primate Liver Xenotransplantation Utilizing Exogenous Coagulation Factors and Costimulation Blockade.

Since the first attempt of pig-to-primate liver xenotransplantation (LXT) in 1968, survival has been limited. We evaluated a model utilizing α-1,3-galactosyltransferase knockout donors, continuous posttransplant infusion of human prothrombin concentrate complex, and immunosuppression including anti-thymocyte globulin, FK-506, methylprednisone, and costimulation blockade (belatacept, n = 3 or anti-CD40 mAb, n = 1) to extend survival. Baboon 1 remained well until postoperative day (POD) 25, when euthanasia was required because of cholestasis and plantar ulcers. Baboon 2 was euthanized following a seizure on POD 5, despite normal liver function tests (LFTs) and no apparent pathology. Baboon 3 demonstrated initial stable liver function but was euthanized on POD 8 because of worsening LFTs. Pathology revealed C4d positivity, extensive hemorrhagic necrosis, and a focal cytomegalovirus inclusion. Baboon 4 was clinically well with stable LFTs until POD29, when euthanasia was again necessitated by plantar ulcerations and rising LFTs. Final pathology was C4d negative and without evidence of rejection, inflammation, or thrombotic microangiopathy. Thus, nearly 1-mo rejection-free survival has been achieved following LXT in two of four consecutive recipients, demonstrating that the porcine liver can support life in primates for several weeks and has encouraging potential for clinical application as a bridge to allotransplantation for patients with acute-on-chronic or fulminant hepatic failure.

Tropospheric Emissions: Monitoring of Pollution (TEMPO).

TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution (~2.1 km N/S×4.4 km E/W at 36.5°N, 100°W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide),water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the North American component of the global geostationary constellation of pollution monitoring together with the European Sentinel-4 (S4) and Korean Geostationary Environment Monitoring Spectrometer (GEMS) instruments.

A systematic review of the surgical techniques for the treatment of internal nasal valve collapse: where do we stand?

BACKGROUND: A myriad of interventions have been described to address the restoration or preservation of the internal nasal valve, the narrowest portion of nasal airway. OBJECTIVE OF REVIEW: To review systematically available knowledge and evidence about management options of the collapse of the internal nasal valve area. TYPE OF REVIEW: Systematic review. SEARCH STRATEGY: A MEDLINE, EMBASE, Cochrane Library and CENTRAL database search, followed by extensive hand searching for the identification of relevant studies. EVALUATION METHOD: Review of all English-language studies addressing the treatment of the internal nasal valve collapse. RESULTS: Fifty-three studies were eventually identified and systematically reviewed. The majority (50 of 53) of the included articles are graded as level IV evidence and only one randomised trial was identified. The included randomised study reported no significant difference in improvement between the intervention group (autospreader flap) and placebo arms. The majority of the included studies presented in this systematic review provide level IV evidence concerning the optimal approach for cases of nasal valve collapse. Current research is driven more by reports of techniques than patient outcomes. CONCLUSIONS: Proper evaluation and identification of the cause of the internal nasal valve collapse is paramount prior to selection of the preferred surgical solution. The three-dimensional construction of the nasal valve implies that many pathologies cannot be restored by a single solution. Treatment approaches should be directed at specific involved sites. Present systematic review of the literature revealed that the available evidence is based on low-level studies and focuses more on the description of various surgical techniques rather than on patient-reported outcome measures. Future studies are needed, including homogenous patient groups, comparing different surgical techniques and incorporating patient-reported outcome measures.

The Cell Biology of Cytomegalovirus: Implications for Transplantation.

Interpretation of clinical data regarding the impact of cytomegalovirus (CMV) infection on allograft function is complicated by the diversity of viral strains and substantial variability of cellular receptors and viral gene expression in different tissues. Variation also exists in nonspecific (monocytes and dendritic cells) and specific (NK cells, antibodies) responses that augment T cell antiviral activities. Innate immune signaling pathways and expanded pools of memory NK cells and γδ T cells also serve to amplify host responses to infection. The clinical impact of specific memory T cell anti-CMV responses that cross-react with graft antigens and alloantigens is uncertain but appears to contribute to graft injury and to the abrogation of allograft tolerance. These responses are modified by diverse immunosuppressive regimens and by underlying host immune deficits. The impact of CMV infection on the transplant recipient reflects cellular changes and corresponding host responses, the convergence of which has been termed the "indirect effects" of CMV infection. Future studies will clarify interactions between CMV infection and allograft injury and will guide interventions that may enhance clinical outcomes in transplantation.

Clinical Implications of Basic Science Discoveries: Immune Homeostasis and the Microbiome-Dietary and Therapeutic Modulation and Implications for Transplantation.

Links between the human microbiome and the innate and adaptive immune systems and their impact on autoimmune and inflammatory diseases are only beginning to be recognized. Characterization of the complex human microbial community is facilitated by culture-independent nucleic acid sequencing tools and bioinformatics systems. Specific organisms and microbial antigens are linked with initiation of innate immune responses that, depending on the context, may be associated with tolerogenic or effector immune responses. Further complexity is introduced by preclinical data that demonstrate the impacts of dietary manipulation on the prevention of genetically determined, systemic autoimmune disorders and on gastrointestinal microbiota. Investigation of interactions of complex microbial populations with the human immune system may provide new targets for clinical management in allotransplantation.

High incidence of xenogenic bone marrow engraftment in pig-to-baboon intra-bone bone marrow transplantation.

Previous attempts of α-1,3-galactocyltransferase knockout (GalTKO) pig bone marrow (BM) transplantation (Tx) into baboons have demonstrated a loss of macro-chimerism within 24 h in most cases. In order to achieve improved engraftment with persistence of peripheral chimerism, we have developed a new strategy of intra-bone BM (IBBM) Tx. Six baboons received GalTKO BM cells, with one-half of the cells transplanted into the bilateral tibiae directly and the remaining cells injected intravenously (IBBM/BM-Tx) with a conditioning immunosuppressive regimen. In order to assess immune responses induced by the combined IBBM/BM-Tx, three recipients received donor SLA-matched GalTKO kidneys in the peri-operative period of IBBM/BM-Tx (Group 1), and the others received kidneys 2 months after IBBM/BM-Tx (Group 2). Peripheral macro-chimerism was continuously detectable for up to 13 days (mean 7.7 days; range 3-13) post-IBBM/BM-Tx and in three animals, macro-chimerism reappeared at days 10, 14 and 21. Pig CFUs, indicating porcine progenitor cell engraftment, were detected in the host BM in four of six recipients on days 14, 15, 19 and 28. In addition, anti-pig unresponsiveness was observed by in vitro assays. GalTKO/pCMV-kidneys survived for extended periods (47 and 60 days). This strategy may provide a potent adjunct for inducing xenogeneic tolerance through BM-Tx.

Lamivudine compared with newer antivirals for prophylaxis of hepatitis B core antibody positive livers: a cost-effectiveness analysis.

There is concern over the development of de novo hepatitis B in patients receiving liver transplants from hepatitis B surface antigen negative, hepatitis B core antibody positive donors. Current practice is to place such patients on indefinite lamivudine prophylaxis; however, there is a small risk of breakthrough infection and newer antivirals for hepatitis B are available. The objective of this study was to determine the cost-effectiveness of lamivudine compared with the newer agents, tenofovir and entecavir, in the prophylaxis setting using a Markov model. Three strategies were examined which consisted of either lamivudine or entecavir monoprophylaxis with tenofovir add-on therapy after breakthrough or tenofovir monoprophylaxis with emtricitabine add-on therapy after breakthrough. In the base case scenario, lamivudine was the most cost-effective option at a threshold of $100 000 per quality-adjusted life-year and this remained robust despite parameter uncertainty. Tenofovir had an incremental cost-effectiveness ratio of $3 540 194.77 while other strategies were superior to entecavir therapy. Until drug costs decrease, lamivudine remains the most cost-effective option for hepatitis B prophylaxis in the liver transplant setting.

Cost burden of cirrhosis and liver disease progression in metabolic dysfunction-associated steatohepatitis: A US cohort study.

BACKGROUND: Metabolic dysfunction-associated steatohepatitis (MASH), formerly nonalcoholic steatohepatitis, is characterized by fat accumulation and inflammation of the liver and may result in progression to cirrhosis and liver-related events. OBJECTIVE: To characterize the impact of cirrhosis and progression to liver-related events on costs and health care resource use (HCRU) among MASH patients in the United States. METHODS: The study cohort included patients with diagnosed nonalcoholic steatohepatitis (International Classification of Diseases, Tenth Revision, Clinical Modification code K75.81) in Optum's deidentified Clinformatics Data Mart Database (October 2015 to December 2022) and were stratified by baseline cirrhosis status. Among those without cirrhosis at baseline, patients were further stratified by status of progression to cirrhosis during follow-up. Total HCRU and costs per-person per-year (PPPY) were estimated and compared descriptively between the cohorts. In addition, gamma generalized linear models were used to compare costs PPPY between those with vs without cirrhosis at baseline, as well as with vs without progression during follow-up, while adjusting for baseline patient and disease characteristics. Annual costs per person were also longitudinally modeled using gamma generalized linear mixed models to understand longitudinal changes in costs PPPY while accounting for time correlations within individual patients. Lastly, a series of sensitivity analyses were conducted to assess the impact of study design features and clinical variations of total costs PPPY. RESULTS: A total of 28,576 adults were included, and 9,157 (32.0%) had baseline cirrhosis; of the 19,419 without baseline cirrhosis, a total of 4,235 (21.8%) progressed over follow-up. Mean (SD) HCRU and costs PPPY were higher among patients with cirrhosis ($110,403 [$226,037]) than without ($28,340 [$61,472]; P < 0.01) and among those with progression ($58,128 [$102,626]) than without ($20,031 [$39,740]; P < 0.01). Costs remained significantly greater when adjusted for covariates, with a risk ratio (95% CI) of 1.99 (1.89-2.09) when comparing with vs without baseline cirrhosis and 2.28 (2.15-2.42) when comparing with vs without progression over follow-up. Costs increased with each subsequent year, to 21% by year 6 among those with cirrhosis at baseline and 49% among those without baseline cirrhosis who progressed. CONCLUSIONS: The financial burden of MASH is substantial and significantly greater among those with cirrhosis or disease progression. Although patients without cirrhosis incur lower burden, the increase over time is greater and associated with progression. Therapies that slow progression may help alleviate the financial burden, and strategies are needed to identify patients with MASH at risk of progressing to cirrhosis.

What's new and what's hot? Basic science at the American Transplant Congress 2012.

Application of advanced molecular techniques and novel animal models has provided new insights into basic mechanisms underlying clinical transplantation. Investigations in diverse areas, including graft rejection and tolerance, autoimmunity and infectious diseases, have revealed increasing complexity of the mechanisms controlling immune function, notably at the interface of the innate and adaptive immune systems and within secondary lymphoid organs. New roles have been identified for NK and dendritic cells, B-lymphocytes and for Th17 and regulatory T cells, notably in novel animal models of costimulatory blockade and tolerance. Confirmation of these observations will be needed in normal animals and in humans undergoing organ and cell transplantation. The impact of the microbiome, of vaccines, and of antimicrobial therapies on immune memory and reconstitution after lymphocyte depletion is beginning to be defined.

Overview: cytomegalovirus and the herpesviruses in transplantation.

Herpesviruses infect most animal species. Infections due to the eight human herpesviruses (HHV) are exacerbated by immunosuppression in organ transplantation. The special features of the herpesvirus life cycle include the ability to establish latent, nonproductive infection and the life-long capacity for reactivation to productive, lytic infection. Interactions between latent virus and the immune system determine the frequency and severity of symptomatic infections. The immunologic and cellular effects of herpesvirus infections contribute to risk for opportunistic infections and graft rejection. Among the most important advances in transplantation are laboratory assays for the diagnosis and monitoring of herpesvirus infections and antiviral agents with improved efficacy in prophylaxis and therapy. For herpes simplex virus, varicella zoster virus and cytomegalovirus, these advances have significantly reduced the morbidity of infection. The syndromes of EBV-associated posttransplant lymphoproliferative disorders (PTLD) and Kaposi's sarcoma remain important complications of immunosuppression. The epidemiology and essential biology of human herpesvirus is reviewed.

Clinical and radiological features of respiratory syncytial virus in solid organ transplant recipients: a single-center experience.

BACKGROUND: Respiratory syncytial virus (RSV) infections range from upper respiratory illness to severe lower respiratory disease. There is no universally accepted treatment for RSV in solid organ transplant (SOT) recipients. METHODS: Retrospective review of adult SOT patients with RSV infections, between January 2007 and December 2009, in a single transplant center was performed. RESULTS: During the 3-year period, a total of 24 adults developed RSV infection, including 12 (50%) SOT recipients (5 kidneys, 4 livers, and 3 lungs). Most cases were seen in 2009 during the influenza H1N1 pandemic, likely as a result of increased testing. In 83% of the cases, the diagnosis was based on RSV antigen detection, which was also used to follow subsequent shedding (mean duration: 20.6 days). Most of the cases presented with lower respiratory disease and required hospitalization. All the patients were on at least two classes of immunosuppressive drugs. We observed a lower lymphocyte count in patients with lower respiratory tract infection. Computed tomography was superior to chest x-ray in demonstrating pulmonary disease, with the most common findings being pulmonary nodules and ground-glass opacities. Novel radiographic findings were small cavities and pleural effusions. No co-infections were documented, and no mortality could be attributed to RSV. Inhaled or oral ribavirin was administered in 67% of the cases, with variations in the treatment regimens. CONCLUSION: SOT recipients accounted for half of all adult cases of RSV at our institution. Type and length of treatment varied widely, and we cannot conclude that outcomes differed between treatments with oral or inhaled ribavirin. Current therapeutic management of RSV in SOT is empiric, and can be rather expensive and difficult, without clear evidence of effectiveness.

Multidisciplinary team management of tracheostomy procedures in neurocritical care patients: our experience over 17 years in a quaternary centre.

OBJECTIVE: Tracheostomy in the neurocritical care population is associated with poorer outcomes. This study hypothesised that a multidisciplinary approach to tracheostomy care can improve outcomes. METHODS: This study was a prospective longitudinal study of all tracheostomised patients in the neurocritical care units of a quaternary centre over 17 years. All patients were managed by a tracheostomy team with a constant core membership of an intensive care consultant, speech and language therapist, and physiotherapist with consultant ENT input. RESULTS: A total of 51 per cent of patients were decannulated in hospital at an average of 48 (neuromedical) and 57.6 (neurosurgical) days. Of the 42 per cent of patients transferred to another facility with a tracheostomy tube in situ, 37.5 per cent were at an advanced stage of tracheostomy weaning. Complication rates were low at 4.8 per cent with no tracheostomy associated mortalities. CONCLUSION: A multidisciplinary approach can enable good outcomes in the neurocritical care population. Consistency of care spanning the step-down from critical to ward-level care is crucial to improving outcomes.

Utility of exercise testing to assess athletes for post COVID-19 myocarditis.

Purpose: This study assessed a functional protocol to identify myocarditis or myocardial involvement in competitive athletes following SARS-CoV2 infection. Methods: We prospectively evaluated competitive athletes (n = 174) for myocarditis or myocardial involvement using the Multidisciplinary Inquiry of Athletes in Miami (MIAMI) protocol, a median of 18.5 (IQR 16-25) days following diagnosis of COVID-19 infection. The protocol included biomarker analysis, ECG, cardiopulmonary stress echocardiography testing with global longitudinal strain (GLS), and targeted cardiac MRI for athletes with abnormal findings. Patients were followed for median of 148 days. Results: We evaluated 52 females and 122 males, with median age 21 (IQR: 19, 22) years. Five (2.9%) had evidence of myocardial involvement, including definite or probable myocarditis (n = 2). Three of the 5 athletes with myocarditis or myocardial involvement had clinically significant abnormalities during stress testing including ventricular ectopy, wall motion abnormalities and/or elevated VE/VCO2, while the other two athletes had resting ECG abnormalities. VO2max, left ventricular ejection fraction and GLS were similar between those with or without myocardial involvement. No adverse events were reported in the 169 athletes cleared to exercise at a median follow-up of 148 (IQR108,211) days. Patients who were initially restricted from exercise had no adverse sequelae and were cleared to resume training between 3 and 12 months post diagnosis. Conclusions: Screening protocols that include exercise testing may enhance the sensitivity of detecting COVID-19 related myocardial involvement following recovery from SARS-CoV2 infection.

Disseminated Mycobacterium kansasii infection with hepatic abscesses in a renal transplant recipient.

Mycobacterium kansasii is the second most frequent cause of non-tuberculous mycobacterial disease in the United States after Mycobacterium avium complex. While primarily it is a pulmonary disease, extrapulmonary manifestations are common. This case report describes a recent renal transplant recipient with disseminated M. kansasii infection presenting with hepatic abscesses, with discussion of clinical management issues and strategies, and a review of the literature.

Retroviral restriction factors and infectious risk in xenotransplantation.

The clinical application of xenotransplantation poses immunologic, ethical, and microbiologic challenges. Significant progress has been made in the investigation of each of these areas. Among concerns regarding infectious risks for human xenograft recipients is the identification in swine of infectious agents including porcine endogenous retroviruses (PERV) that are capable of replication in some human cell lines. PERV replication has, however, been difficult to demonstrate in primate-derived cell lines and in preclinical studies of non-human primates receiving porcine xenografts. Endogenous 'retroviral restriction factors' are intracellular proteins and components of the innate immune system that act at various steps in retroviral replication. Recent studies suggest that some of these factors may have applications in the management of endogenous retroviruses in xenotransplantation. The risks of PERV infection and the potential role of retroviral restriction factors in xenotransplantation are reviewed in detail.