Monty Montano

Human Immunodeficiency Virus Type 1 Subtypes Differ in Disease Progression

At least 10 different genetic human immunodeficiency virus type 1 (HIV-1) subtypes (A-J) are responsible for the AIDS pandemic. Much of the understanding of HIV-1 disease progression derives from studies in the developed world where HIV infection is almost exclusively subtype B. This has led many to question whether the properties and consequences of HIV-1 infection can be generalized across subtypes that afflict the majority of infected persons in the developing world. From 1985 to 1997, a prospective study of registered female sex workers in Senegal tracked the introduction and spread of HIV-1 subtypes A, C, D, and G. In clinical follow-up, the AIDS-free survival curves differed by HIV-1 subtype. Women infected with a non-A subtype were 8 times more likely to develop AIDS than were those infected with subtype A (hazard ratio=8.23; P=. 009), the predominant subtype in the study. These data suggest that HIV-1 subtypes may differ in rates of progression to AIDS.

Genetic Signatures of Exceptional Longevity in Humans

Like most complex phenotypes, exceptional longevity is thought to reflect a combined influence of environmental (e.g., lifestyle choices, where we live) and genetic factors. To explore the genetic contribution, we undertook a genome-wide association study of exceptional longevity in 801 centenarians (median age at death 104 years) and 914 genetically matched healthy controls. Using these data, we built a genetic model that includes 281 single nucleotide polymorphisms (SNPs) and discriminated between cases and controls of the discovery set with 89% sensitivity and specificity, and with 58% specificity and 60% sensitivity in an independent cohort of 341 controls and 253 genetically matched nonagenarians and centenarians (median age 100 years). Consistent with the hypothesis that the genetic contribution is largest with the oldest ages, the sensitivity of the model increased in the independent cohort with older and older ages (71% to classify subjects with an age at death>102 and 85% to classify subjects with an age at death>105). For further validation, we applied the model to an additional, unmatched 60 centenarians (median age 107 years) resulting in 78% sensitivity, and 2863 unmatched controls with 61% specificity. The 281 SNPs include the SNP rs2075650 in TOMM40/APOE that reached irrefutable genome wide significance (posterior probability of association = 1) and replicated in the independent cohort. Removal of this SNP from the model reduced the accuracy by only 1%. Further in-silico analysis suggests that 90% of centenarians can be grouped into clusters characterized by different “genetic signatures” of varying predictive values for exceptional longevity. The correlation between 3 signatures and 3 different life spans was replicated in the combined replication sets. The different signatures may help dissect this complex phenotype into sub-phenotypes of exceptional longevity.

BET bromodomain inhibition as a novel strategy for reactivation of HIV-1

The persistence of latent HIV‐1 remains a major challenge in therapeutic efforts to eradicate infection. We report the capacity for HIV reactivation by a selective small molecule inhibitor of BET family bromodomains, JQ1, a promising therapeutic agent with antioncogenic properties. JQ1 reactivated HIV transcription in models of latent T cell infection and latent monocyte infection. We also tested the effect of exposure to JQ1 to allow recovery of replication‐competent HIV from pools of resting CD4+ T cells isolated from HIV‐infected, ART‐treated patients. In one of three patients, JQ1 allowed recovery of virus at a frequency above unstimulated conditions. JQ1 potently suppressed T cell proliferation with minimal cytotoxic effect. Transcriptional profiling of T cells with JQ1 showed potent down‐regulation of T cell activation genes, including CD3, CD28, and CXCR4, similar to HDAC inhibitors, but JQ1 also showed potent up‐regulation of chromatin modification genes, including SIRT1, HDAC6, and multiple lysine demethylases (KDMs). Thus, JQ1 reactivates HIV‐1 while suppressing T cell activation genes and up‐regulating histone modification genes predicted to favor increased Tat activity. Thus, JQ1 may be useful in studies of potentially novel mechanisms for transcriptional control as well as in translational efforts to identify therapeutic molecules to achieve viral eradication.

Infant Morbidity, Mortality, and Breast Milk Immunologic Profiles among Breast-Feeding HIV-Infected and HIV-Uninfected Women in Botswana

BACKGROUND Infants of human immunodeficiency virus (HIV)-infected women have high mortality, but the immunologic integrity and protection afforded by the breast milk of HIV-infected women is unknown. METHODS We determined morbidity and mortality by 24 months among breast-fed infants of 588 HIV-infected and 137 HIV-uninfected women followed-up in a clinical trial in Botswana. A matched case-control study compared clinical, behavioral, and breast milk immunologic parameters among 120 HIV-infected women by infant outcome. Breast milk factors were also compared between HIV-infected and HIV-uninfected women. RESULTS Twenty-four-month mortality was 29.5% among HIV-infected infants, 6.7% among HIV-exposed uninfected infants, and 1.6% among HIV-unexposed infants. No differences were detected in breast milk immunologic profiles of HIV-infected women whose infants were either ill or well. Discontinuation of breast-feeding was the strongest predictor of illness (P<.001). Levels in breast milk of pathogen-specific immunoglobulin (Ig) G and IgA to Haemophilus influenzae, Campylobacter jejuni, Helicobacter pylori, Streptococcus pneumoniae, and innate immune factors were not lower among HIV-infected women than among HIV-uninfected women. CONCLUSIONS Mortality was higher among HIV-infected and HIV-exposed infants than among HIV-unexposed infants. However, the immunologic profiles of breast milk among HIV-infected women were intact, and discontinuation of breast-feeding was the primary risk for infant morbidity. Thus, the breast milk of HIV-infected women may confer protection against common infant pathogens. TRIAL REGISTRATION (ClinicalTrials.Gov) identifiers: NCT00197691 and NCT00197652.

Elevated Tumor Necrosis Factor—α Activation of Human Immunodeficiency Virus Type 1 Subtype C in Southern Africa Is Associated with an NF-κ B Enhancer Gain-of-Function

The human immunodeficiency virus type 1 (HIV-1) epidemic within southern Africa is predominantly associated with the HIV-1C subtype. Functional analysis of the enhancer region within the long terminal repeat (LTR) indicates that HIV-1C isolates have >/=3 NF-kappaB binding sites, unlike other subtypes, which have only 1 or 2 sites. A correlation was shown between NF-kappaB enhancer configuration and responsiveness to the proinflammatory cytokine tumor necrosis factor (TNF)-alpha within the context of naturally occurring subtype LTRs, subtype-specific NF-kappaB enhancer regions cloned upstream of an isogenic HXB2 core promoter or a heterologous SV40 minimal promoter, and full-genome subtype clones. In all cases, TNF-alpha activation was correlated with the subtype configuration of the NF-kappaB enhancer. Whether the naturally occurring gain-of-function in the NF-kappaB enhancer of HIV-1C observed in this study can provide a selective advantage for the virus in vivo remains to be determined and warrants further study.

RNA Editing Genes Associated with Extreme Old Age in Humans and with Lifespan in C. elegans

Background The strong familiality of living to extreme ages suggests that human longevity is genetically regulated. The majority of genes found thus far to be associated with longevity primarily function in lipoprotein metabolism and insulin/IGF-1 signaling. There are likely many more genetic modifiers of human longevity that remain to be discovered. Methodology/Principal Findings Here, we first show that 18 single nucleotide polymorphisms (SNPs) in the RNA editing genes ADARB1 and ADARB2 are associated with extreme old age in a U.S. based study of centenarians, the New England Centenarian Study. We describe replications of these findings in three independently conducted centenarian studies with different genetic backgrounds (Italian, Ashkenazi Jewish and Japanese) that collectively support an association of ADARB1 and ADARB2 with longevity. Some SNPs in ADARB2 replicate consistently in the four populations and suggest a strong effect that is independent of the different genetic backgrounds and environments. To evaluate the functional association of these genes with lifespan, we demonstrate that inactivation of their orthologues adr-1 and adr-2 in C. elegans reduces median survival by 50%. We further demonstrate that inactivation of the argonaute gene, rde-1, a critical regulator of RNA interference, completely restores lifespan to normal levels in the context of adr-1 and adr-2 loss of function. Conclusions/Significance Our results suggest that RNA editors may be an important regulator of aging in humans and that, when evaluated in C. elegans, this pathway may interact with the RNA interference machinery to regulate lifespan.

Whole Genome Sequences of a Male and Female Supercentenarian, Ages Greater than 114 Years

Supercentenarians (age 110+ years old) generally delay or escape age-related diseases and disability well beyond the age of 100 and this exceptional survival is likely to be influenced by a genetic predisposition that includes both common and rare genetic variants. In this report, we describe the complete genomic sequences of male and female supercentenarians, both age >114 years old. We show that: (1) the sequence variant spectrum of these two individuals’ DNA sequences is largely comparable to existing non-supercentenarian genomes; (2) the two individuals do not appear to carry most of the well-established human longevity enabling variants already reported in the literature; (3) they have a comparable number of known disease-associated variants relative to most human genomes sequenced to-date; (4) approximately 1% of the variants these individuals possess are novel and may point to new genes involved in exceptional longevity; and (5) both individuals are enriched for coding variants near longevity-associated variants that we discovered through a large genome-wide association study. These analyses suggest that there are both common and rare longevity-associated variants that may counter the effects of disease-predisposing variants and extend lifespan. The continued analysis of the genomes of these and other rare individuals who have survived to extremely old ages should provide insight into the processes that contribute to the maintenance of health during extreme aging.

Comparative Prediction of Perinatal Human Immunodeficiency Virus Type 1 Transmission, Using Multiple Virus Load Markers

Maternal plasma human immunodeficiency virus (HIV) type 1 RNA load has a role in perinatal transmission, but significant overlap in the range of plasma virus loads among transmitters and nontransmitters is often observed, which makes it difficult to predict transmission outcome. We measured several virus markers in a drug-naive population of HIV-1-infected mothers in Botswana. Maternal plasma HIV-1 RNA load, peripheral blood mononuclear cell-associated blood HIV-1 DNA load, and cervicovaginal fluid (CVF) HIV-1 DNA load were determined using quantitative real-time polymerase chain reaction. The overall rate of transmission among these mother-infant pairs was 35.7%. Median infant age was 2.5 months. An association between increased plasma HIV-1 RNA load and perinatal transmission was observed (odds ratio [OR], 2.20/1-log virus load; 95% confidence interval [CI], 1.15-4.18). However, the association between increased blood HIV-1 DNA load and perinatal transmission was stronger (OR, 10.30; 95% CI, 2.11-50.38). When blood HIV-1 DNA load was combined with CVF HIV-1 DNA load, the association with transmission increased (OR, 25.0; 95% CI 2.73-228.60).

A novel library screen identifies immunosuppressors that promote osteoblast differentiation.

Bone homeostasis can be compromised by an increase in osteoclast-mediated resorption and/or a decrease in osteoblast-mediated bone deposition. While many efforts have focused on treating osteoclast resorption, there has been less emphasis on identifying strategies for promoting osteoblast function. Herein, we describe a high-throughput screening assay to select for small molecules that augment bone morphogenetic protein-2 (BMP-2)-mediated osteoblast lineage commitment. After an initial screen of 5405 compounds; consisting of FDA-approved drugs, known bioactives, and compounds with novel chemical makeup, we identified 45 small molecules that promoted osteoblast commitment. Of the 45 candidates, there was a broad array of classes that included nine retinoid analogs/derivatives and four immunosuppressants, notably rapamycin and FK-506, which were chosen for further study. Treatment of osteoblast precursor cells with rapamycin or FK-506, either alone, or synergistically with BMP-2, increased levels of phospho-Smad 1/5/8 protein and transcription of Runx-2, Osx and Smad-7, consistent with a role in promoting osteoblast differentiation. Only FK-506 was able to enhance osteocalcin transcripts and Alizarin Red staining, both late markers for differentiation. When osteoblast differentiation was suppressed with exogenous TGF-β1 treatment, rapamycin (but not FK-506) was able to rescue expression of differentiation markers, indicating distinct but overlapping activity of these compounds. Collectively, these data add to an understanding of pathways engaged in osteoblastogenesis, support a role for non-redundant immunosuppressant signaling, and provide a novel approach for the discovery of potentially therapeutic compounds that affect bone remodeling.

MicroRNAs: miRRORS of health and disease

The review articles in this issue provide an improved appreciation for microRNA (miRNA) as an essential feature of lineage commitment and regulatory guidance during tissue development that, when absent or hampered, often lead to disease states. In the coming years, there is much to be learned about adaptive (and maladaptive) states by examining how the expression of miRNAs is influenced by the genetic architecture of miR genes, clusters, and mirtrons, as well as miRNA polymorphism and polymorphism in their mRNA targets. We are also introduced to several modes of miRNA regulation (negative feedback, positive feedback, and cross regulatory) that monitor, modulate, or resolve signaling pathways in a variety of biologic processes that include sepsis response, fibrosis, acute exercise, and steroid biology. Perhaps the homeostasis or micromanagement of these miRNA regulatory systems, when perturbed, arrive at new stable networked interactions that have an undesired effect of promoting or antagonizing disease severity and cancer progression. Clearly, a better understanding of these miRNA regulatory networks, as well as improved therapeutic tools for guiding miRNA expression and their targets toward desired outcomes, will be the subject of many advances in miRNA biology over the coming years.