Rohan Hazra

Tenofovir disoproxil fumarate and an optimized background regimen of antiretroviral agents as salvage therapy: impact on bone mineral density in HIV-infected children.

OBJECTIVE. Tenofovir disoproxil fumarate, a nucleotide analog HIV reverse transcriptase inhibitor with demonstrated activity against nucleoside-resistant HIV, is approved for use in adults but not children. Metabolic bone abnormalities have been seen in young animals given high-dose tenofovir and HIV-infected adults that were treated with oral tenofovir disoproxil fumarate. However, tenofovir disoproxil fumarate is being used in children despite a lack of bone safety data. We hypothesized that, given the higher rate of bone turnover that is associated with normal skeletal growth, the potential for TDF-related bone toxicity may be greater in children than in adults. METHODS. Fifteen highly antiretroviral-experienced HIV-infected children who were 8 to 16 years of age (mean ± SD: 12 ± 2) and required a change in therapy received tenofovir disoproxil fumarate 175 to 300 mg/m2 per day (adult dose equivalent) as part of highly active antiretroviral therapy for up to 96 weeks. Bone mineral density of the lumbar spine, femoral neck, and total hip by dual-energy x-ray absorptiometry and blood and urine markers of bone metabolism were measured at 0, 24, 48, 72, and 96 weeks. RESULTS. Median z score (SD score compared with age, gender, and ethnicity-matched control subjects) of the lumbar spine, femoral neck, and total hip were decreased from baseline at 24 weeks and 48 weeks and then stabilized. Lumbar spine bone mineral apparent density (which estimates volumetric bone mineral density independent of bone size) z scores also decreased at 24 weeks. Absolute decreases in bone mineral density were observed in 6 children; the mean age of these children was significantly younger than the bone mineral density stable group (10.2 ± 1.1 vs 13.2 ± 1.8 years). The change in lumbar spine bone mineral density correlated with decreases in HIV plasma RNA during treatment. Metabolic markers of bone formation and resorption were variable. Two children in whom tenofovir disoproxil fumarate was discontinued because of bone loss that exceeded protocol allowances demonstrated partial or complete recovery of bone mineral density by 96 weeks. CONCLUSIONS. Tenofovir disoproxil fumarate use in children seems to be associated with decreases in bone mineral density that, in some children, stabilize after 24 weeks. Increases in bone markers and calcium excretion suggest that tenofovir disoproxil fumarate may stimulate bone resorption. Bone turnover is higher in children than in older adolescents and adults because of skeletal growth, potentially explaining the greater effect seen in young children. Decreases in bone mineral density correlate with decreases in viral load and young age, suggesting that young responders may be at greater risk for bone toxicity.

Lymphadenitis Due to Nontuberculous Mycobacteria in Children: Presentation and Response to Therapy

The most common manifestation of infection due to nontuberculous mycobacteria (NTM) in children is cervical lymphadenitis in an otherwise healthy patient. We identified and reviewed 19 cases of proven or presumptive lymphadenitis due to NTM seen at our hospital over the course of 13 months. Nine patients underwent initial surgical excision of involved lymph nodes. Ten children did not have involved lymph nodes excised initially and were treated with macrolide-containing antibiotic regimens. Of these patients, five required subsequent surgical excision and five were cured with combination chemotherapy. Six patients underwent radiographic imaging of the head and neck that revealed asymmetrical adenopathy with ring-enhancing masses but minimal inflammatory stranding of the subcutaneous fat, a finding that may distinguish adenitis caused by NTM from staphylococcal and streptococcal adenitis. Our data suggest that if surgical excision is not considered feasible, antimicrobial therapy for adenitis due to NTM may be beneficial for some patients.

Growing Up with HIV: Children, Adolescents, and Young Adults with Perinatally Acquired HIV Infection

Tremendous success in the prevention and treatment of pediatric HIV in high-resource countries has changed the face of the epidemic. A perinatally HIV-infected child now faces a chronic disease rather than a progressive, fatal one. However, these successes pose new challenges as perinatally HIV-infected youth survive into adulthood. These include maintaining adherence to long-term, likely life-long therapy; selecting successive antiretroviral drug regimens, given the limited availability of pediatric formulations and the lack of pharmacokinetic and safety data in children; and overcoming extensive drug resistance in multi-drug-experienced children. Pediatric HIV care now focuses on morbidity related to long-term HIV infection and its treatment. Survival into adulthood of perinatally HIV-infected youth in high-resource countries encourages expansion of pediatric treatment programs in low-resource countries, where most HIV-infected children live, and provides important lessons about how the epidemic changes with increasing access to antiretroviral therapy for children.

HIV-1 Viral Escape in Infancy Followed by Emergence of a Variant-Specific CTL Response

Mutational escape from the CTL response represents a major driving force for viral diversification in HIV-1-infected adults, but escape during infancy has not been described previously. We studied the immune response of perinatally infected children to an epitope (B57-TW10) that is targeted early during acute HIV-1 infection in adults expressing HLA-B57 and rapidly mutates under this selection pressure. Viral sequencing revealed the universal presence of escape mutations within TW10 among B57- and B5801-positive children. Mutations in TW10 and other B57-restricted epitopes arose early following perinatal infection of B57-positive children born to B57-negative mothers. Surprisingly, the majority of B57/5801-positive children exhibited a robust response to the TW10 escape variant while recognizing the wild-type epitope weakly or not at all. These data demonstrate that children, even during the first years of life, are able to mount functional immune responses of sufficient potency to drive immune escape. Moreover, our data suggest that the consequences of immune escape may differ during infancy because most children mount a strong variant-specific immune response following escape, which is rarely seen in adults. Taken together, these findings indicate that the developing immune system of children may exhibit greater plasticity in responding to a continually evolving chronic viral infection.

Decreased Bone Mineral Density with Off-Label Use of Tenofovir in Children and Adolescents Infected with Human Immunodeficiency Virus

5 of 6 children infected with human immunodeficiency virus (HIV) receiving Tenofovir disoproxil fumarate (TDF) experienced absolute decreases in bone mineral density (BMD). 2 pre-pubertal subjects experienced >6% BMD decreases. 1 subject was the smallest child and experienced a 27% decrease, necessitating withdrawal of TDF. Subsequently, her BMD recovered. Monitoring of children infected with HIV who require treatment with TDF is warranted.

Safety of tenofovir use during pregnancy: Early growth outcomes in HIV-exposed uninfected infants

Objective:To evaluate the association of tenofovir disoproxil fumarate (TDF) use during pregnancy with early growth parameters in HIV-exposed, uninfected (HEU) infants. Design:US-based prospective cohort study of HEU children to examine potential adverse effects of prenatal TDF exposure. Methods:We evaluated the association of maternal TDF use during pregnancy with small for gestational age (SGA); low birth weight (LBW, <2.5 kg); weight-for-age z-scores (WAZ), length-for-age z-scores (LAZ), and head circumference-for-age (HCAZ) z-scores at newborn visit; and LAZ, HCAZ, and WAZ at age 1 year. Logistic regression models for LBW and SGA were fit, adjusting for maternal and sociodemographic factors. Adjusted linear regression models were used to evaluate LAZ, WAZ, and HCAZ by TDF exposure. Results:Of 2029 enrolled children with maternal antiretroviral information, TDF was used by 449 (21%) HIV-infected mothers, increasing from 14% in 2003 to 43% in 2010. There was no difference between those exposed to combination regimens with vs. without TDF for SGA, LBW, and newborn LAZ and HCAZ. However, at age 1 year, infants exposed to combination regimens with TDF had significantly lower adjusted mean LAZ and HCAZ than those without TDF (LAZ: −0.17 vs. −0.03, P = 0.04; HCAZ: 0.17 vs. 0.42, P = 0.02). Conclusion:TDF use during pregnancy was not associated with increased risk for LBW or SGA. The slightly lower mean LAZ and HCAZ observed at age 1 year in TDF-exposed infants are of uncertain significance but underscore the need for additional studies of growth outcomes after TDF use during pregnancy.

Transcription Regulation by the Mycobacterium tuberculosis Alternative Sigma Factor SigD and Its Role in Virulence

Mycobacterium tuberculosis, an obligate mammalian pathogen, adapts to its host during the course of infection via the regulation of gene expression. Of the regulators of transcription that play a role in this response, several alternative sigma factors of M. tuberculosis have been shown to control gene expression in response to stresses, and some of these are required for virulence or persistence in vivo. For this study, we examined the role of the alternative sigma factor SigD in M. tuberculosis gene expression and virulence. Using microarray analysis, we identified several genes whose expression was altered in a strain with a sigD deletion. A small number of these genes, including sigD itself, the gene encoding the autocrine growth factor RpfC, and a gene of unknown function, Rv1815, appear to be directly regulated by this sigma factor. By identifying the in vivo promoters of these genes, we have determined a consensus promoter sequence that is putatively recognized by SigD. The expression of several genes encoding PE-PGRS proteins, part of a large family of related genes of unknown function, was significantly increased in the sigD mutant. We found that the expression of sigD is stable throughout log phase and stationary phase but that it declines rapidly with oxygen depletion. In a mouse infection model, the sigD mutant strain was attenuated, with differences in survival and the inflammatory response in the lung between mice infected with the mutant and those infected with the wild type.

Tenofovir Disoproxil Fumarate and an Optimized Background Regimen of Antiretroviral Agents as Salvage Therapy for Pediatric HIV Infection

Objectives. Highly active antiretroviral therapy has altered the course of HIV infection among children, but new antiretroviral agents are needed for treatment-experienced children with drug-resistant virus. Tenofovir disoproxil fumarate (DF) is a promising agent for use in pediatric salvage therapy, because of its tolerability, efficacy, and resistance profile. We designed this study to provide preliminary pediatric safety and dosing information on tenofovir DF, while also providing potentially efficacious salvage therapy for heavily treatment-experienced, HIV-infected children. Methods. Tenofovir DF, alone and in combination with optimized background antiretroviral regimens, was studied among 18 HIV-infected children (age range: 8.3–16.2 years) who had progressive disease with ≥2 prior antiretroviral regimens, in a single-center, open-label trial. Tenofovir DF monotherapy for 6 days was followed by the addition of individualized antiretroviral regimens. Subjects were monitored with HIV RNA reverse transcription-polymerase chain reaction, flow cytometry, and routine laboratory studies; monitoring for bone toxicity included measurement of lumbar spine bone mineral density (BMD) with dual-energy x-ray absorptiometry. Subjects were monitored through 48 weeks. Results. Two subjects developed grade 3 elevated hepatic transaminase levels during monotherapy and were removed from the study. The remaining 16 subjects had a median of 4 antiretroviral agents (range: 3–5 agents) added to tenofovir DF. HIV plasma RNA levels decreased from a median pretreatment level of 5.4 log10 copies per mL (range: 4.1–5.9 log10 copies per mL) to 4.21 log10 copies per mL at week 48 (n = 15), with 6 subjects having <400 copies per mL, including 4 with <50 copies per mL. The overall median increases in CD4+ T cell counts were 58 cells per mm3 (range: −64 to 589 cells per mm3) at week 24 and 0 cells per mm3 (range: −274 to 768 cells per mm3) at week 48. The CD4+ cell responses among the virologic responders were high and sustained. The major toxicity attributed to tenofovir DF was a >6% decrease in BMD for 5 of 15 subjects evaluated at week 48, necessitating the discontinuation of tenofovir DF therapy for 2; all 5 subjects experienced >2 log10 copies per mL decreases in HIV plasma RNA levels. Conclusions. Tenofovir DF-containing, individualized, highly active antiretroviral therapy regimens were well tolerated and effective among heavily treatment-experienced, HIV-infected children. Loss of BMD may limit tenofovir DF use among prepubertal patients.

Cognitive Functioning in School-Aged Children With Vertically Acquired HIV Infection Being Treated With Highly Active Antiretroviral Therapy (HAART)

In todays era of highly active antiretroviral therapy (HAART), few children with HIV-1 infection experience severe central nervous system (CNS) manifestations indicative of encephalopathy. However, little is known about the neurocognitive strengths and weaknesses of HIV-infected children treated with HAART. This cross-sectional study is the first to systematically investigate the relation between cognitive functioning and medical markers in HIV-infected children and adolescents treated with HAART with varying levels of computed tomography (CT) brain scan abnormalities. The Wechsler Intelligence Scale for Children–Third Edition was administered to 41 vertically infected children (mean age = 11.2 years) treated with HAART for at least 1 year. Other procedures at the time of testing included CT brain scans and collection of CD4 cell counts and plasma HIV–1 RNA PCR. Although global cognitive functioning among participants was in the Average range, children with minimal to moderate CT brain scan abnormalities scored significantly lower than children with normal scans on composite measures of cognitive functioning and five specific subtests, especially tasks involving executive functions. Furthermore, children with worse immune status (CD4+ counts ≤ 500) scored lower on subtests measuring processing speed. Viral load was unrelated to cognitive test scores. Thus, children with HIV being treated with HAART remain at risk for developing CNS disease. Findings emphasize the importance of conducting neuropsychological assessments in this population, particularly for children with cortical atrophy and absolute CD4+ cell counts ≤ 500.

Combination antiretroviral use and preterm birth.

BACKGROUND Use of antiretroviral drugs (ARVs) during pregnancy has been associated with higher risk of preterm birth. METHODS The Pediatric HIV/AIDS Cohort Study networks Surveillance Monitoring for ART Toxicities study is a US-based cohort of human immunodeficiency virus (HIV)-exposed uninfected children. We evaluated maternal ARV use during pregnancy and the risk of any type of preterm birth (ie, birth before 37 completed weeks of gestation), the risk of spontaneous preterm birth (ie, preterm birth that occurred after preterm labor or membrane rupture, without other complications), and the risk of small for gestational age (SGA; ie, a birth weight of <10th percentile for gestational age). Multivariable logistic regression models were used to evaluate the association of ARVs and timing of exposure, while adjusting for maternal characteristics. RESULTS Among 1869 singleton births, 18.6% were preterm, 10.2% were spontaneous preterm, and 7.3% were SGA. A total of 89% used 3-drug combination ARV regimens during pregnancy. In adjusted models, the odds of preterm birth and spontaneous preterm birth were significantly greater among mothers who used protease inhibitors during the first trimester (adjusted odds ratios, 1.55 and 1.59, respectively) but not among mothers who used nonnucleoside reverse-transcriptase inhibitor or triple-nucleoside regimens during the first trimester. Combination ARV exposure starting later in pregnancy was not associated with increased risk. No associations were observed between SGA and exposure to combination ARV regimens. CONCLUSIONS Protease inhibitor use early in pregnancy may be associated with increased risk for prematurity.