Brian S. Schwartz

Selective inhibition of BET bromodomains

Epigenetic proteins are intently pursued targets in ligand discovery. So far, successful efforts have been limited to chromatin modifying enzymes, or so-called epigenetic ‘writers’ and ‘erasers’. Potent inhibitors of histone binding modules have not yet been described. Here we report a cell-permeable small molecule (JQ1) that binds competitively to acetyl-lysine recognition motifs, or bromodomains. High potency and specificity towards a subset of human bromodomains is explained by co-crystal structures with bromodomain and extra-terminal (BET) family member BRD4, revealing excellent shape complementarity with the acetyl-lysine binding cavity. Recurrent translocation of BRD4 is observed in a genetically-defined, incurable subtype of human squamous carcinoma. Competitive binding by JQ1 displaces the BRD4 fusion oncoprotein from chromatin, prompting squamous differentiation and specific antiproliferative effects in BRD4-dependent cell lines and patient-derived xenograft models. These data establish proof-of-concept for targeting protein–protein interactions of epigenetic ‘readers’, and provide a versatile chemical scaffold for the development of chemical probes more broadly throughout the bromodomain family.

Expansion of a unique CD57+NKG2Chi natural killer cell subset during acute human cytomegalovirus infection

During human CMV infection, there is a preferential expansion of natural killer (NK) cells expressing the activating CD94–NKG2C receptor complex, implicating this receptor in the recognition of CMV-infected cells. We hypothesized that NK cells expanded in response to pathogens will be marked by expression of CD57, a carbohydrate antigen expressed on highly mature cells within the CD56dimCD16+ NK cell compartment. Here we demonstrate the preferential expansion of a unique subset of NK cells coexpressing the activating CD94–NKG2C receptor and CD57 in CMV+ donors. These CD57+NKG2Chi NK cells degranulated in response to stimulation through their NKG2C receptor. Furthermore, CD57+NKG2Chi NK cells preferentially lack expression of the inhibitory NKG2A receptor and the inhibitory KIR3DL1 receptor in individuals expressing its HLA-Bw4 ligand. Moreover, in solid-organ transplant recipients with active CMV infection, the percentage of CD57+NKG2Chi NK cells in the total NK cell population preferentially increased. During acute CMV infection, the NKG2C+ NK cells proliferated, became NKG2Chi, and finally acquired CD57. Thus, we propose that CD57 might provide a marker of “memory” NK cells that have been expanded in response to infection.

A population-based study of the incidence and molecular epidemiology of methicillin-resistant Staphylococcus aureus disease in San Francisco, 2004-2005.

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) infections have become a major public health problem in both the community and hospitals. Few studies have characterized the incidence and clonal composition of disease-causing strains in an entire population. Our objective was to perform a population-based survey of the clinical and molecular epidemiology of MRSA disease in San Francisco, California. METHODS We prospectively collected 3985 MRSA isolates and associated clinical and demographic information over a 12-month period (2004-2005) at 9 San Francisco-area medical centers. A random sample of 801 isolates was selected for molecular analysis. RESULTS The annual incidence of community-onset MRSA disease among San Francisco residents was 316 cases per 100,000 population, compared with 31 cases per 100,000 population for hospital-onset disease. Persons who were aged 35-44 years, were men, and were black had the highest incidence of community-onset disease. The USA300 MRSA clone accounted for 234 cases of community-onset disease and 15 cases of hospital-onset disease per 100,000 population, constituting an estimated 78.5% and 43.4% of all cases of MRSA disease, respectively. Patients with community-onset USA300 MRSA versus non-USA300 MRSA disease were more likely to be male, be of younger age, and have skin and soft-tissue infections. USA300 strains were generally more susceptible to multiple antibiotics, although decreased susceptibility to tetracycline was observed in both community-onset (P = .008) and hospital-onset (P = .03) USA300 compared to non-USA300 strains. CONCLUSIONS The annual incidence of community-onset MRSA disease in San Francisco is substantial, surpassing that of hospital-onset disease. USA300 is the predominant clone in both the community and hospitals. The dissemination of USA300 from the community into the hospital setting has blurred its distinction as a community-associated pathogen.

Assessment of Cytomegalovirus-Specific Cell-Mediated Immunity for the Prediction of Cytomegalovirus Disease in High-Risk Solid-Organ Transplant Recipients: A Multicenter Cohort Study

BACKGROUND Cytomegalovirus (CMV) disease remains an important problem in solid-organ transplant recipients, with the greatest risk among donor CMV-seropositive, recipient-seronegative (D(+)/R(-)) patients. CMV-specific cell-mediated immunity may be able to predict which patients will develop CMV disease. METHODS We prospectively included D(+)/R(-) patients who received antiviral prophylaxis. We used the Quantiferon-CMV assay to measure interferon-γ levels following in vitro stimulation with CMV antigens. The test was performed at the end of prophylaxis and 1 and 2 months later. The primary outcome was the incidence of CMV disease at 12 months after transplant. We calculated positive and negative predictive values of the assay for protection from CMV disease. RESULTS Overall, 28 of 127 (22%) patients developed CMV disease. Of 124 evaluable patients, 31 (25%) had a positive result, 81 (65.3%) had a negative result, and 12 (9.7%) had an indeterminate result (negative mitogen and CMV antigen) with the Quantiferon-CMV assay. At 12 months, patients with a positive result had a subsequent lower incidence of CMV disease than patients with a negative and an indeterminate result (6.4% vs 22.2% vs 58.3%, respectively; P < .001). Positive and negative predictive values of the assay for protection from CMV disease were 0.90 (95% confidence interval [CI], .74-.98) and 0.27 (95% CI, .18-.37), respectively. CONCLUSIONS This assay may be useful to predict if patients are at low, intermediate, or high risk for the development of subsequent CMV disease after prophylaxis. CLINICAL TRIALS REGISTRATION NCT00817908.

Screening and Treatment of Chagas Disease in Organ Transplant Recipients in the United States: Recommendations from the Chagas in Transplant Working Group

Donor‐derived transmission of Trypanosoma cruzi, the etiologic agent of Chagas disease, has emerged as an issue in the United States over the past 10 years. Acute T. cruzi infection causes substantial morbidity and mortality in the posttransplant setting if not recognized and treated early. We assembled a working group of transplant infectious disease specialists, laboratory medicine specialists, organ procurement organization representatives and epidemiologists with expertise in Chagas disease. Based on review of published and unpublished data, the working group prepared evidence‐based recommendations for donor screening, and follow‐up testing and treatment of recipients of organs from infected donors. We advise targeted T. cruzi screening of potential donors born in Mexico, Central America and South America. Programs can consider transplantation of kidneys and livers from T. cruzi‐infected donors with informed consent from recipients. However, we recommend against heart transplantation from infected donors. For other organs, we recommend caution based on the anticipated degree of immunosuppression. Our recommendations stress the need for systematic monitoring of recipients by polymerase chain reaction, and microscopy of buffy coat and advance planning for immediate antitrypanosomal treatment if recipient infection is detected. Data on management and outcomes of all cases should be collected to inform future guidelines and to assist in coordination with public health authorities.

Parasitic Infections in Solid Organ Transplantation

Abbreviations: BAL, bronchoalveolar lavage; CDC, Centers for Disease Control and Prevention; CMV, cytomegalovirus; CNS, central nervous system; CSF, cerebral spinal fluid; DD, disseminated disease; DS, double strength; EIA, Enzyme Immunoassay; ELISA, Enzyme-linked immunosorbent assay; FDA, Food and Drug Administration; FIA, Fluorescence Immunoassay; HIS, hyperinfection syndrome; SOT, solid organ transplant; TMP/SMX, trimethoprim/ sulfamethoxazole; WHO, World Health Organization.

Diagnosis and management of tuberculosis in transplant donors: a donor-derived infections consensus conference report.

Mycobacterium tuberculosis is a ubiquitous organism that infects one‐third of the worlds population. In previous decades, access to organ transplantation was restricted to academic medical centers in more developed, low tuberculosis (TB) incidence countries. Globalization, changing immigration patterns, and the expansion of sophisticated medical procedures to medium and high TB incidence countries have made tuberculosis an increasingly important posttransplant infectious disease. Tuberculosis is now one of the most common bacterial causes of solid‐organ transplant donor‐derived infection reported in transplant recipients in the United States. Recognition of latent or undiagnosed active TB in the potential organ donor is critical to prevent emergence of disease in the recipient posttransplant. Donor‐derived tuberculosis after transplantation is associated with significant morbidity and mortality, which can best be prevented through careful screening and targeted treatment. To address this growing challenge and provide recommendations, an expert international working group was assembled including specialists in transplant infectious diseases, transplant surgery, organ procurement and TB epidemiology, diagnostics and management. This working group reviewed the currently available data to formulate consensus recommendations for screening and management of TB in organ donors.

Concurrent Epidemics of Skin and Soft Tissue Infection and Bloodstream Infection Due to Community-Associated Methicillin-Resistant Staphylococcus aureus

BACKGROUND Since its emergence in 2000, epidemic spread of the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 has led to a high burden of skin and soft tissue infections (SSTIs) in the United States, yet its impact on MRSA bloodstream infections (BSIs) is poorly characterized. METHODS To assess clonality of the MRSA isolates causing SSTI and BSI during the epidemic period, a stratified, random sample of 1350 unique infection isolates (from a total of 7252) recovered at the Community Health Network of San Francisco from 2000 to 2008 were selected for genotyping. Risk factors and outcomes for 549 BSI cases caused by the USA300 epidemic clone and non-USA300 MRSA clones were assessed by retrospective review of patient medical records. RESULTS From 2000 to 2008, secular trends of USA300 SSTI and USA300 BSI were strongly correlated (Pearson r = 0.953). USA300 accounted for 55% (304/549) of BSIs as it was the predominant MRSA clone that caused community-associated (115/160), healthcare-associated community-onset (125/207), and hospital-onset (64/182) BSIs. Length of hospitalization after BSI diagnosis and mortality rates for USA300 and non-USA300 were similar. Two independent risk factors for USA300 BSI were identified: concurrent SSTI (adjusted relative risk, 1.4 [95% confidence interval {CI}, 1.2-1.6]) and anti-MRSA antimicrobial use in the preceding 30 days (0.7 [95% CI, .6-.8]). Isolates from concurrent SSTI were indistinguishable genotypically from the USA300 isolates that caused BSI. CONCLUSIONS USA300 SSTIs serve as a source for BSI. Strategies to control the USA300 SSTI epidemic may lessen the severity of the concurrent USA300 BSI epidemic.

Interleukin-12 Receptor β1 Deficiency Predisposing to Disseminated Coccidioidomycosis

Severe disseminated Coccidioides is rare while localized, contained disease is common. We report a family with disseminated coccidioidomycosis due to a novel homozygous C186Y mutation in interleukin (IL)-12 receptor β1. This family confirms the centrality of the IL-12/IFN-γ axis to human immunity to Coccidioides spp.

Coccidioidomycosis during pregnancy: a review and recommendations for management.

Pregnancy is an established risk factor for the development of severe and disseminated coccidioidomycosis, particularly when infection is acquired during the later stages of gestation. Although recent studies suggest that the incidence of symptomatic coccidioidomycosis during pregnancy is decreasing and that outcome has improved, management is complicated by the observations that azole antifungal agents can be teratogenic when given to some women, particularly at high doses, early in pregnancy. This article summarizes the data on these issues and offers guidance on the management of coccidioidomycosis during pregnancy.