Overcoming barriers and stigma: new frontiers in solid organ transplantation for people with HIV

There is a growing need for solid organ transplantation (SOT) for people living with human immunodeficiency virus (HIV). With the advent of antiretroviral therapy, people living with HIV are experiencing increased life expectancies and are, therefore, developing more comorbidities, including end-stage organ disease. In cases of advanced organ failure, SOT is often the best therapeutic option to improve quality of life and overall survival. As organ shortages persist, transplantation of organs from donors with HIV to recipients with HIV has become a potential therapeutic option. This article first reviews the current state of organ transplantation from donors without HIV to recipients with HIV (HIV D-/R+) by organ and discusses key lessons learned from these transplant trials, including those about drug-drug interactions, rejection, and opportunistic infections. It then explores transplantation from donors with HIV to recipients with HIV (HIV D+/R+), a new frontier. Finally, it investigates challenges of implementation, including public awareness and regulatory requirements, and explores future directions for SOT in people living with HIV.

Pseudoxanthoma elasticum overlaps hereditary spastic paraplegia type 56

PURPOSE

Pseudoxanthoma elasticum (PXE) is a recessive disorder involving skin, eyes and arteries, mainly caused by ABCC6 pathogenic variants. However, almost one fifth of patients remain genetically unsolved despite extensive genetic screening of ABCC6, as illustrated in a large French PXE series of 220 cases. We searched for new PXE gene(s) to solve the ABCC6-negative patients.

METHODS

First, family-based exome sequencing was performed, in one ABCC6-negative PXE patient with additional neurological features, and her relatives. CYP2U1, involved in hereditary spastic paraplegia type 56 (SPG56), was selected based on this complex phenotype, and the presence of two candidate variants. Second, CYP2U1 sequencing was performed in a retrospective series of 46 additional ABCC6-negative PXE probands. Third, six additional SPG56 patients were evaluated for PXE skin and eye phenotype. Additionally, plasma pyrophosphate dosage and functional analyses were performed in some of these patients.

RESULTS

6.4% of ABCC6-negative PXE patients (n = 3) harboured biallelic pathogenic variants in CYP2U1. PXE skin lesions with histological confirmation, eye lesions including maculopathy or angioid streaks, and various neurological symptoms were present. CYP2U1 missense variants were confirmed to impair protein function. Plasma pyrophosphate levels were normal. Two SPG56 patients (33%) presented some phenotypic overlap with PXE.

CONCLUSION

CYP2U1 pathogenic variants are found in unsolved PXE patients with neurological findings, including spastic paraplegia, expanding the SPG56 phenotype and highlighting its overlap with PXE. The pathophysiology of ABCC6 and CYP2U1 should be explored to explain their respective role and potential interaction in ectopic mineralization.

False-positive hepatitis C virus serology after placement of a ventricular assistance device

BACKGROUND

Ventricular assist devices (VADs) have been associated with immune activation and sensitization. We observed several cases of false-positive (FP) hepatitis C virus (HCV) antibody (Ab) tests in patients being evaluated for orthotopic heart transplant (OHT), prompting us to investigate this further.

METHODS

We reviewed all VAD and OHT cases at Johns Hopkins from 2005 to 2012. FP HCV serology was defined as an equivocal or low-positive HCV Ab, plus either (i) a negative recombinant immunoblot (RIBA) and/or HCV nucleic acid test (NAT), or (ii) an indeterminate RIBA and negative NAT.

RESULTS

In 53 patients with available HCV testing, nearly 40% of patients (21/53: 39.6%) developed FP HCV Ab tests after VAD placement: 4 patients had negative NAT, 12 had negative RIBA, and 5 had an indeterminate RIBA and negative NAT. All patients with indeterminate RIBA tests had isolated reactivity to the same HCV protein, c100p/5-1-1p (NS4b protein). In 3 of 4 VAD patients who had OHT and repeat HCV Ab testing after VAD removal, repeat HCV Ab was negative (699-947 days after OHT); in 1 case, FP HCV serology persisted (5 days after OHT). Thirteen patients had OHT alone and none developed a FP HCV Ab.

CONCLUSIONS

FP HCV Ab results following VAD placement are very common. Reversal of FP serology in several patients after VAD removal is suggestive of a possible association with the VAD hardware. Clinicians should be aware of this phenomenon, as it could lead to delays in determining eligibility for OHT and increased costs.

Challenges and Clinical Decision-Making in HIV-to-HIV Transplantation: Insights From the HIV Literature

Life expectancy among HIV-infected (HIV+) individuals has improved dramatically with effective antiretroviral therapy. Consequently, chronic diseases such as end-stage liver and kidney disease are growing causes of morbidity and mortality. HIV+ individuals can have excellent outcomes after solid organ transplantation, and the need for transplantation in this population is increasing. However, there is a significant organ shortage, and HIV+ individuals experience higher mortality rates on transplant waitlists. In South Africa, the use of organs from HIV+ deceased donors (HIVDD) has been successful, but until recently federal law prohibited this practice in the United States. With the recognition that organs from HIVDD could fill a critical need, the HIV Organ Policy Equity (HOPE) Act was passed in November 2013, reversing the federal ban on the use of HIV+ donors for HIV+ recipients. In translating this policy into practice, the biologic risks of using HIV+ donors need to be carefully considered. In this mini-review, we explore relevant aspects of HIV virology, antiretroviral treatment, drug resistance, opportunistic infections and HIV-related organ dysfunction that are critical to a transplant team considering HIV-to-HIV transplantation.

Management of hepatitis C infection among patients with renal failure

Hepatitis C virus (HCV) infection is a rising global public health burden with an estimated 130-150 million infected people worldwide and 350,000 to 500,000 HCV-related deaths each year. Chronic kidney disease (CKD) is also a highly prevalent public health issue as the escalating numbers of patients worldwide are developing type 2 diabetes mellitus and hypertension due to high fat diets and a growing obesity epidemic. The high incidence and prevalence of HCV infection leads to substantial morbidity and mortality among renal dialysis patients. Recommendations are to screen for HCV infection among all patients with renal failure especially prior to initiation of hemodialysis and renal transplant evaluation. HCV-antibody enzyme immunoassay (EIA) followed by confirmation with HCV RNA nucleic acid test (NAT) is recommended for low prevalence regions, but in dialysis centers with a high prevalence of HCV, initial testing with NAT is recommended due to higher false positive EIA rates. Liver biopsy is used to assess of liver disease severity. Transjugular liver biopsy, as an effective and safe technique in patients with ESRD can be considered instead of percutaneous approach. Non-invasive approaches to staging fibrosis, including liver stiffness measurement by transient elastography and panels of serum fibrosis biomarkers, are also widely used. Although difficult to manage, combined pegylated- interferon (PEG IFN) and ribavirin therapy was the only treatment modality available for HCV-positive patients until the recently introduced new direct-acting antiviral agents. However, except boceprevir, there are no currently available data to suggest that these new anti-viral drugs are safe and effective among end-stage renal failure patients. IFN-containing regimens were also associated with high rates of renal graft loss in post-renal transplant patients. Therefore, management of HCV infection in renal failure patients is unique and should be tailored individually with calculated risk/benefit ratio. New studies are immediately warranted to determine the safety profile and efficacy of newer anti-HCV drugs not only in patients with end-stage renal failure prior to kidney transplantation but also among kidney transplant recipients.

Epidemiology, outcomes, and mortality predictors of invasive mold infections among transplant recipients: a 10-year, single-center experience

BACKGROUND

The epidemiology of invasive mold infections (IMI) in transplant recipients differs based on geography, hosts, preventative strategies, and methods of diagnosis.

METHODS

We conducted a retrospective observational study to evaluate the epidemiology of proven and probable IMI, using prior definitions, among all adult hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients in the era of "classic" culture-based diagnostics (2000-2009). Epidemiology was evaluated before and after an initiative was begun to increase bronchoscopy in HSCT recipients after 2005.

RESULTS

In total, 106 patients with one IMI were identified. Invasive aspergillosis (IA) was the most common IMI (69; 65.1%), followed by mucormycosis (9; 8.5%). The overall rate of IMI (and IA) was 3.5% (2.5%) in allogeneic HSCT recipients. The overall incidence for IMI among lung, kidney, liver, and heart transplant recipients was 49, 2, 11, and 10 per 1000 person-years, respectively. The observed rate of IMI among human leukocyte antigen-matched unrelated and haploidentical HSCT recipients increased from 0.6% annually to 3.0% after bronchoscopy initiation (P < 0.05). The 12-week mortality among allogeneic HSCT, liver, kidney, heart, and lung recipients with IMI was 52.4%, 47.1%, 27.8%, 16.7%, and 9.5%, respectively. Among allogeneic HSCT (odds ratio [OR]: 0.07, P = 0.007) and SOT (OR: 0.22, P = 0.05) recipients with IA, normal platelet count was associated with improved survival. Male gender (OR: 14.4, P = 0.007) and elevated bilirubin (OR: 5.7, P = 0.04) were significant predictors of mortality for allogeneic HSCT and SOT recipients with IA, respectively.

CONCLUSIONS

During the era of culture-based diagnostics, observed rates of IMI were low among all transplants except lung transplant recipients, with relatively higher mortality rates. Diagnostic aggressiveness and host variables impact the reported incidence and outcome of IMI and likely account for institutional variability in multicenter studies. Definitions to standardize diagnoses among SOT recipients are needed.

SHANK3 mutations identified in autism lead to modification of dendritic spine morphology via an actin-dependent mechanism

Genetic mutations of SHANK3 have been reported in patients with intellectual disability, autism spectrum disorder (ASD) and schizophrenia. At the synapse, Shank3/ProSAP2 is a scaffolding protein that connects glutamate receptors to the actin cytoskeleton via a chain of intermediary elements. Although genetic studies have repeatedly confirmed the association of SHANK3 mutations with susceptibility to psychiatric disorders, very little is known about the neuronal consequences of these mutations. Here, we report the functional effects of two de novo mutations (STOP and Q321R) and two inherited variations (R12C and R300C) identified in patients with ASD. We show that Shank3 is located at the tip of actin filaments and enhances its polymerization. Shank3 also participates in growth cone motility in developing neurons. The truncating mutation (STOP) strongly affects the development and morphology of dendritic spines, reduces synaptic transmission in mature neurons and also inhibits the effect of Shank3 on growth cone motility. The de novo mutation in the ankyrin domain (Q321R) modifies the roles of Shank3 in spine induction and morphology, and actin accumulation in spines and affects growth cone motility. Finally, the two inherited mutations (R12C and R300C) have intermediate effects on spine density and synaptic transmission. Therefore, although inherited by healthy parents, the functional effects of these mutations strongly suggest that they could represent risk factors for ASD. Altogether, these data provide new insights into the synaptic alterations caused by SHANK3 mutations in humans and provide a robust cellular readout for the development of knowledge-based therapies.

Rapidly progressive cutaneous Rhizopus microsporus infection presenting as Fournier's gangrene in a patient with acute myelogenous leukemia

Members of the genus Rhizopus within the class Zygomycetes can cause devastating opportunistic infections. Cutaneous disease arising from direct inoculation of fungal spores has the potential to disseminate widely. Here, we describe a dramatic case of cutaneous Rhizopus infection involving the penis in a patient with acute myelogenous leukemia. Despite aggressive surgical debridement, systemic antifungal therapy, and donor lymphocyte infusion, the infection was ultimately fatal. This case illustrates the unique diagnostic and therapeutic challenges in the clinical management of cutaneous Rhizopus infection.

Shrinkage of lung after chemical fixation for analysis of pulmonary structure-function relations

Glutaraldehyde is widely used to chemically fix lungs for analysis of pulmonary structure-function relations. Accurate interpretation of observations on fixed tissue requires a clear definition of any artifacts, such as tissue shrinkage, resulting from fixation with glutaraldehyde. Two experimental procedures were used in this study to examine possible shrinkage artifacts resulting from fixation of lung by glutaraldehyde. In the first, isolated perfused dog lungs were rapidly frozen at different transpulmonary pressures. Samples were then freeze substituted at -50 degrees C using 70% ethylene glycol with and without fixatives present. In the second series of experiments, the left lungs of mongrel dogs were fixed by vascular perfusion with glutaraldehyde at different transpulmonary pressures. In both series of experiments any changes in linear dimensions resulting from the fixation procedure were measured. Also, the presence of aldehyde was demonstrated by a positive reaction with Schiff reagent. The results demonstrate that lung tissue fixed either by vascular perfusion or freeze substitution tends to shrink to about the same extent. This shrinkage is reasonably constant at about 9% for transpulmonary pressures of 5 and 15 cmH2O and increases to about 15% when the transpulmonary pressure reaches 25 cmH20.

Electron micropscopic appearances of rapidly frozen lung

Analysis of pulmonary structure-function relationships by microscopy requires that the lung be fixed under carefully controlled physiological conditions, since lung structure is extremely responsive to the relationship between airway and vascular pressures. Unfortunately, standard post-mortem fixation techniques leave some doubt as to the exact relationship between these pressures during fixation. This problem can be circumvented by stabilizing lung structure by rapid freezing under carefully controlled physiologic conditions. Using ethylene glycol in a freeze substitution technique we have developed procedures which yield a degree of preservation compatible with the high degree of resolution of the electron microscope. These can be used to obtain a more detailed understanding of pulmonary structure-function relationships under well-defined physiological conditions.

Electron microscopy of lung rapidly frozen under controlled physiological conditions

Light microscopy of lung rapidly frozen under controlled physiological conditions has been very successful in correlating pulmonary structure and function. However, to study some aspects of pulmonary capillary morphology, the higher resolution of electron microscopy (EM) is necessary. To date, most EM of lung has involed the instillation of a fixative through the airways or vascular system, techniques that probably alter the normal pressure relationships of the capillaries and therefore their morphology. We describe here a technique for rapidly freezing lung to a depth of 1--2 mm below the pleural surface and preparing sections for EM. Lungs from open-chest rats were frozen at various transpulmonary pressures with cold (--80 degrees C) 70% ethylene glycol. Small pieces were then fixed with a solution containing glutaraldehyde and paraformaldehyde for 24 h at --50 degrees C. Staining was with osmium tetroxide and uranyl acetate. Lung frozen at high volumes showed marked stretching of the alveolar septa with severe deformation of the capillaries. Lung frozen at low inflation pressures revealed open capillaries containing numerous red blood cells; in addition, infolding of the alveolar wall was frequently seen. We conclude that this technique gives a level of preservation of rapidly frozen lung suitable for electron microscopy.

Distribution of red and white blood cells in alveolar walls

Dog lungs were perfused with blood and rapidly frozen with liquid Freon gas at various pulmonary artery and venous pressures. The numbers of red and white blood cells per mm-2 of alveolar wall were counted in lung sections and, in addition, the proportion (by area) of the wall occupied by the cells was measured by point counting. The number and proportional area of the red blood cells rapidly increased as perfusing pressure was raised. These findings are consistent with earlier observations of capillary recruitment and distension. An unexpected observation was the large number of leukocytes in the capillaries especially at low perfusing pressures. For example when arterial exceeded alveolar pressure by 5 cmH2O (as occurs near the apex of the upright human lung), there were about 5,000 red cells and 4,000 white cells per mm-2 of alveolar wall. As perfusing pressure was increased, the number of leukocytes paradoxically decreased in zone 3 but remained constant in zone 2. Most of the white cells were mononuclear cells. These results suggest that the lung behaves as a mechanical sieve for large cells and that the number of trapped cells depends on the capillary pressure.