Moderately High Tenofovir Diphosphate in Dried Blood Spots Indicates Drug Resistance in Viremic Persons Living with HIV

BACKGROUND

Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a strong predictor of viral suppression in persons living with HIV (PLWH). Its association with antiretroviral therapy (ART) resistance remains unknown.

METHODS

Blood was collected in PLWH receiving TDF-containing ART enrolled in a 48-week study. Tenofovir diphosphate/emtricitabine triphosphate (FTC-TP) were quantified from the same sample as HIV viral load (VL) in PLWH who developed resistance within ≤12 months.

RESULTS

The study enrolled 807 participants, of whom 10 had new resistance-conferring mutations. Among these, median (interquartile range) TFV-DP and HIV VL were 956 (407-1510) fmol/punch and 9840 (513-68,200) copies/mL, respectively. Five had quantifiable FTC-TP in DBS. Based on previously published data, a TFV-DP concentration of 956 fmol/punch would have an adjusted odds of virologic suppression of 32.8 versus TFV-DP <350 fmol/punch, making viremia of ∼10,000 copies/mL an unexpected outcome.

CONCLUSION

Moderately high TFV-DP in DBS (700-1249 fmol/punch) in PLWH with high viremia suggest that antiretroviral drug resistance might be present.

Quality of life assessment among HIV-positive persons entering the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial

OBJECTIVES

With HIV treatment prolonging survival and HIV infection now managed as a chronic illness, quality of life (QOL) is important to evaluate in persons living with HIV (PLWH). We assessed at study entry the QOL of antiretroviral-naïve PLWH with CD4 counts > 500 cells/μL in the Strategic Timing of AntiRetroviral Treatment (START) clinical trial.

METHODS

QOL was assessed with: (1) a visual analogue scale (VAS) for self-assessment of overall current health; (2) the Short-Form 12-Item Version 2 Health Survey(®) (SF-12V2), for which responses are summarized into eight individual QOL domains plus component summary scores for physical health [the Physical Health Component Summary (PCS)] and mental health [the Mental Health Component Summary (MCS)]. The VAS and eight domain scores were scaled from 0 to 100. Mean QOL measures were calculated overall and by demographic, clinical and behavioural factors.

RESULTS

A total of 4631 participants completed the VAS and 4119 the SF-12. The mean VAS score (with standard deviation) was 80.9 ± 15.7. Mean SF-12 domain scores were lowest for vitality (66.3 ± 26.4) and mental health (68.6 ± 21.4), and highest for physical functioning (89.3 ± 23.0) and bodily pain (88.0 ± 21.4). Using multiple linear regression, PCS scores were lower (P < 0.001) for Asians, North Americans, female participants, older participants, and those with less education, longer duration of known HIV infection, alcoholism/substance dependence and body mass index ≥ 30 kg/m(2) . MCS scores were highest (P < 0.001) for Africans, South Americans and older participants, and lowest for female participants, current smokers and those with alcoholism/substance dependence.

CONCLUSIONS

In this primarily healthy population, QOL was mostly favourable, emphasizing that it is important that HIV treatments do not negatively impact QOL. Self-assessed physical health summary scores were higher than mental health scores. Factors such as older age and geographical region had different effects on perceived physical and mental health.

A simple self-reported adherence tool as a predictor of viral rebound in people with viral suppression on antiretroviral therapy

OBJECTIVES

The aim of the study was to investigate the relationship between self-reported antiretroviral therapy (ART) adherence and virological outcomes in the multinational Strategies for Management of Antiretroviral Therapy (SMART) study.

METHODS

Eligible participants were from the continuous ART arm and had at least one viral load (VL) ≤ 50 HIV-1 RNA copies/mL and a subsequent VL value (VL pair). Self-reported adherence was measured at each visit using a five-point Likert scale which employed a 7-day recall. High adherence was defined as taking 'all pills every day' (level 1) for every regimen component; all others had suboptimal adherence (levels 2 - 5). In individuals with VL suppression (≤ 50 copies/mL), the association between adherence (at the time of VL suppression) and VL rebound (> 200 copies/mL at next visit) was assessed using multivariable logistic regression with generalized estimating equations.

RESULTS

A total of 10 761 sets of VL pairs from 1986 participants were included in the study. For 1220 (11%) VL pairs, adherence was suboptimal. For 507 VL pairs (5%), VL rebound occurred. The risk of rebound generally increased as adherence decreased: 4.2% for level 1, 7.7% for level 2, 16.3% for level 3, 9.4% for level 4 and 12.9% for level 5. In multivariable analysis, suboptimal adherence at the time of suppression was associated with a 50% increased odds of experiencing subsequent VL rebound [odds ratio (OR) 1.51; 95% confidence interval (CI) 1.19-1.92; P = 0.0023], compared with high adherence.

CONCLUSIONS

Self-reported suboptimal adherence in people with VL suppression is associated with an increased risk of VL rebound. Our findings highlight the importance of continued adherence counselling, even in people with VL suppression, and to ensure that people with HIV infection maintain excellent adherence in order to minimize the risk of VL rebound.

Intact T cell receptor signaling by CD4(+) T cells cultured in the rotating wall-vessel bioreactor

T lymphocytes fail to proliferate or secrete cytokines in response to T cell receptor (TCR) agonists during culture in spaceflight or ground-based microgravity analogs such as rotating wall-vessel (RWV) bioreactors. In RWVs, these responses can be rescued by co-stimulation with sub-mitogenic doses of the diacyl glycerol (DAG) mimetic phorbol myristate acetate. Based on this result we hypothesized that TCR activation is abrogated in the RWV due to impaired DAG signaling downstream of the TCR. To test this hypothesis we compared TCR-induced signal transduction by primary, human, CD4(+) T cells in RWV, and static culture. Surprisingly, we found little evidence of impaired DAG signaling in the RWV. Upstream of DAG, the tyrosine phosphorylation of several key components of the TCR-proximal signal was not affected by culture in the RWV. Similarly, the phosphorylation and compartmentalization of ERK and the degradation of IkappaB were unchanged by culture in the RWV indicating that RAS- and PKC-mediated signaling downstream of DAG are also unaffected by simulated microgravity. We conclude from these data that TCR signaling through DAG remains intact during culture in the RWV, and that the loss of functional T cell activation in this venue derives from the affect of simulated microgravity on cellular processes that are independent of the canonical TCR pathway.

Tuberculosis testing in correctional officers: a national random survey of jails in the United States

SETTING

The correctional system in the United States is large and growing. The Centers for Disease Control and Prevention recommend baseline and annual testing of employees in correctional facilities for latent tuberculosis infection (LTBI).

OBJECTIVE

To describe the extent of and factors associated with LTBI testing practices for jail correctional officers.

DESIGN

A national survey of 1760 randomly selected jails was conducted. We used multivariable logistic regression models to examine factors associated with testing officers in a guideline-concordant manner and having a written policy.

RESULTS

A total of 1174 (67%) surveys were returned. Only 52% of jails had a written policy on LTBI testing of officers, and 51% screened officers at least annually (guideline concordance). Large jails (OR 2.41, 95%CI 1.67-3.49) and jails in states with a high tuberculosis incidence (OR 1.67, 95%CI 1.17-2.38) and in the Midwest (OR 1.58, 95%CI 1.07-2.33) were more likely to screen in a guideline-concordant manner.

CONCLUSION

Screening for LTBI among correctional officers in the United States was inconsistent. Strategies to improve LTBI testing among correctional officers are needed.

A randomized comparison of two instruments for measuring self-reported antiretroviral adherence

A randomised trial compared two instruments for assessing self-reported adherence to antiretroviral medications: (1) a day-by-day recall instrument that elicited the number of missed doses in each of the prior three days (3-day instrument; n=64) and (2) a general recall instrument that elicited an estimate of proportion of pills taken during the prior seven days (7-day instrument; n=70). Adherence was measured at study visits over 12 months among participants in a clinical trial assessing treatment strategies for individuals with virologic failure and multidrug-resistant HIV. Participants had a median (interquartile range) of 133 (41-264) CD4 cells/ml(3) and a median of 10 major HIV resistance mutations at baseline. Mean adherence levels were 90-98% throughout the study. There was a greater trend in the likelihood of 100% adherence when measured by the 3-day versus the 7-day instrument (odds ratio (OR)=1.45; p=0.06). The likelihood of consistent 100% adherence measured by either instrument decreased over time (p<0.001). Participants reporting 100% adherence at more than half of study visits had better virologic and immunologic outcomes at month-12 compared to those reporting 100% adherence at half or fewer visits (HIV RNA decline of 0.96 versus 0.51 log, respectively, p=0.02; and CD4 cell increase of 51.0 versus 17.8 cells, p=0.04). This study demonstrated the utility of the general 7-day recall adherence self-report instrument as well as the 3-day day-by-day recall adherence self-report instrument for measuring antiretroviral adherence. Self-reported adherence was significantly associated with virologic and immunologic outcomes in this population with advanced drug-resistant HIV disease.

Dynamic culture in a rotating-wall vessel bioreactor differentially inhibits murine T-lymphocyte activation by mitogenic stimuli upon return to static conditions in a time-dependent manner

Depressed immune function is a well-documented effect of spaceflight. Both in-flight studies and ground-based studies using microgravity analogs, such as rotating wall vessel (RWV) bioreactors, have demonstrated that mitogen-stimulated T lymphocytes exhibit decreased proliferation, IL-2 secretion, and activation marker expression in true microgravity and the dynamic RWV-culture environment. This study investigates the kinetics of RWV-induced T lymphocyte inhibition by monitoring the ability of Balb/c mouse splenocytes to become activated under static culture conditions after concanavalin A (Con A) stimulation in an RWV. Splenocytes were stimulated with Con A and cultured for up to 24 h in the RWV before being allowed to “recover” under static culture conditions in the continued presence of Con A. The T-lymphocyte fraction of splenocytes was assayed during the recovery period for IL-2 secretion, expansion of the T-lymphocyte population, and expression of the activation marker CD25. Our results indicate that CD25 expression was not affected by any duration of RWV exposure. In contrast, proliferation and IL-2 secretion were inhibited by >8 and 12 h of exposure, respectively. Culture in the RWV for 24 h resulted in a near-complete loss of cellular viability during the recovery period, which was not seen in cells maintained in the RWV for 16 h or less. Taken together, these results indicate that for up to 8 h of RWV culture activation is not significantly impaired upon return to static conditions; longer duration RWV culture results in a gradual loss of activation during the recovery period most likely because of decreased T-cell viability and/or IL-2 production.

Characterization of antibody responses to annual influenza vaccination over four years in a healthy elderly population

The effects of yearly influenza immunization on the level of antibody responses were assessed in 92 healthy elderly subjects immunized over four contiguous years (1993-1996) with a trivalent influenza vaccine that included A/Texas annually. Anti-A/Texas antibodies increased significantly and similarly post-vaccination each year, but returned to comparable baseline levels annually. Percentages of subjects with anti-A/Texas titers > or =40 post-vaccination were comparable over four years. Importantly, post-vaccination titers > or =40 to A/Texas in 1993-1994 predicted anti-A/Texas titers > or =40 in subsequent years. Thirty percent of individuals produced four-fold rises to any vaccine component the first year it was included in the vaccine, however, this percentage decreased to about 10% after subsequent vaccination with the same component. This study clearly supports the concept that annual immunization with the same influenza vaccine component over multiple years does not significantly decrease antibody titers in a healthy elderly population.

Age-related changes in interferon-alpha/beta receptor expression, binding, and induction of apoptosis in natural killer cells from C57BL/6 mice

Natural killer (NK) cells are a critical first line of defense against viral infections and tumors. We showed previously that basal NK cytotoxicity was comparable in adult (6 month) and aged (24 month) C57BL/6 (B6) mice. However, NK activity was significantly higher in adult compared with aged B6 mice after either in vitro or in vivo stimulation with IFN-alpha/beta. The present study explored whether age-related decreases in inducible NK activity after stimulation with IFN-alpha/beta were due to differences in (1) IFN-alpha/beta receptor expression or IFN-alpha/beta binding to NK cells or (2) apoptosis of NK cells. Flow cytometry revealed that, despite significantly higher IFN-alpha/beta receptor expression (P</=0.03) on NK cells of aged mice, IFN-alpha/beta binding to NK cells was comparable between adult and aged mice. In addition, IFN-alpha/beta treatment significantly increased Fas (CD95) expression (P</=0.05) on NK cells from both adult and aged mice. However, after IFN-alpha/beta stimulation, NK cells from aged mice demonstrated significantly higher CD95 expression (P</=0.03) and percent apoptosis (P</=0.05) relative to adult mice. These results suggest possible mechanisms for age-associated decreases in inducible NK cytotoxicity after IFN-alpha/beta stimulation may include altered IFN-alpha/beta receptors and/or increased percentages of NK cells undergoing apoptosis.

Immune response to influenza vaccine in healthy elderly: lack of association with plasma beta-carotene, retinol, alpha-tocopherol, or zinc

Immunity and nutritional status are compromised with age, yet the relationship between them is unclear. Immune responses and plasma micronutrient levels of 61 healthy elderly (mean 81 years) and 27 young (mean 27 years) were assessed before and after immunization with trivalent influenza vaccine (FLU). FLU-induced proliferation and IFN-gamma levels of elderly were lower than young before and after immunization. Proliferation and IFN-gamma levels increased after immunization of young, but not elderly. FLU-induced IL-6 and IL-10 levels did not change after immunization of either group. While antibody titers to all three FLU components increased after vaccination of young and elderly, post-vaccination titers of elderly were lower than young. Although plasma retinol and zinc levels of young and elderly were similar before and after vaccination, elderly had higher plasma beta-carotene and alpha-tocopherol levels at both assessments that increased after vaccination. Importantly, plasma micronutrient levels were comparable for elderly with or without intact (titers >/=40 and fourfold rise post-vaccination) antibody responses after vaccination. These results suggest that differences in these plasma micronutrients (1) are not required to observe decreased FLU responses of healthy elderly compared to young and (2) are not associated with differences in antibody responses among healthy elderly.

Cytokine production after influenza vaccination in a healthy elderly population

Influenza vaccination is less efficacious in the elderly than in the young. To characterize this age-related decrease in immune response to influenza vaccination, antibody and cell-mediated responses to influenza vaccine were assessed before immunization and 4 weeks after vaccination of a population of 270 healthy elderly individuals (mean age: 80.2 years) living in eight local continuing care retirement communities (CCRCs) and 30 young individuals (mean age: 27.8 years). The antibody titres produced against all three influenza strains increased significantly after vaccination in both the young and elderly (p < 0.0005); however, the young demonstrated significantly higher titres to all three strains than did the elderly (p < 0.03). Peripheral blood mononuclear cells (PBMC) cultured with influenza vaccine demonstrated significantly increased proliferation (elderly: p < 0.00005; young: p < 0.001) after vaccination, with proliferative responses in the young significantly higher than the elderly both before (p < 0.04) and after (p < 0.0005) vaccination. Similarly, IFN gamma production in these PBMC cultures increased significantly pre- to postvaccination in both young and elderly (young: p < 0.006; elderly: p < 0.00005), but the young produced more than the elderly both pre- and postvaccination (p < 0.0001). Following vaccination, PBMC production of IL-10 was higher in the young than in the elderly (p < 0.0015), while IL-6 production was comparable in both young and elderly individuals. Greater than 13% of the elderly population did not produce detectable IL-6, IL-10, or IFN gamma either before or after vaccination. The data show that the decreased cell-mediated and humoral responses to influenza vaccination of this healthy elderly population are accompanied by the production of lower levels of cytokines. A unique finding in this population of 270 healthy elderly was the association between a TH0 cytokine profile and intact immune responses to influenza vaccine. A similar relationship was not seen in the young.

The age-associated decline in immune function of healthy individuals is not related to changes in plasma concentrations of beta-carotene, retinol, alpha-tocopherol or zinc

The decline in the lymphoproliferative response to mitogenic stimuli shows marked heterogeneity in elderly individuals. Adequate nutriture is required for optimal immune function, yet nutritional status may be compromised in the elderly. To address whether this variation in the proliferative response of elderly individuals is related to their nutritional status, we studied 61 elderly (80.5 +/- 5.7 year-old) and 27 young (27.3 +/- 3.8 year-old) individuals participating in an ongoing assessment of their immune response to influenza vaccine. Ambulatory elderly individuals were recruited from five different retirement communities and were in good health upon enrollment in the study. Thirty-three percent of young and 54% of elderly subjects reported consuming micronutrient supplements daily during the study. Plasma and peripheral blood mononuclear cells (PBMC) were isolated from fasting individuals twice, 4-6 weeks apart. At both times, proliferative responses to the mitogens phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) were significantly lower (P < 0.004) in the elderly compared to the young. However, at both times, elderly participants had plasma concentrations of beta-carotene, retinol, alpha-tocopherol and zinc that were either significantly greater than, or equal to, those of young subjects. No significant correlations between plasma concentrations of beta-carotene, retinol, alpha-tocopherol and zinc and level of proliferative responses to each stimuli were observed in elderly individuals at either time. Thus, the heterogeneity in the proliferative response to mitogenic stimuli exhibited by a healthy elderly population cannot be attributed to differences in these nutritional parameters.

Immunologic memory is established in nursling rats immunized with tetanus toxoid, but is not affected by concurrent supplementation with vitamin A

Experiments were conducted to determine whether nursling rats immunized with tetanus toxoid (TT) are able to produce a specific antibody response and whether oral treatment with retinyl palmitate, concurrent with immunization, affects the magnitude of the anti-TT response. When rats aged 8-15 d and nursed by vitamin A-sufficient dams were immunized with TT, no primary anti-TT immunoglobulin (Ig) M or IgG response was detected. However, nursling rats formed immunologic memory to TT because, when they were reimmunized at 40 d of age, their secondary anti-TT IgG response exceeded the primary response of 40-d-old vitamin A-sufficient rats (P < 0.02). Provision of retinyl palmitate (equal to 37.5 or 150 micrograms retinol equivalents) by mouth with early primary immunization did not change the magnitude of the secondary anti-TT IgG response. However, the age of nursling rats at first immunization significantly affected the magnitude of their secondary anti-TT IgG response, because rats first immunized at 15 d of age and reimmunized at 40 d of age produced a secondary response that was nearly fivefold greater than that of rats immunized at 8 and 40 d of age. In conclusion, nursling rats immunized with TT formed immunologic memory, which was affected significantly by the timing of the primary immunization. However, the administration of retinyl palmitate concurrent with early primary immunization did not significantly affect the development of memory to TT.

The function of vitamin A in cellular growth and differentiation, and its roles during pregnancy and lactation

Recent advances in the molecular biology of the retinoids have provided a mechanistic explanation for the observations, first made several decades ago, that vitamin A profoundly influences the differentiation of tissues throughout the body. A central concept has recently emerged, namely that retinoids seldom exist "free" in solution but, rather, are nearly always associated with specific retinoid-binding proteins. In plasma, these include RBP and the chylomicron whereas, in cells two distinct classes of retinoid-binding proteins exist: the cellular (cytoplasmic) proteins (CRBPs and CRABPs) and the nuclear receptors proteins (RARs and RXRs). Whereas the cellular retinoid-binding proteins serve as buffers and as chaperones during metabolism (Ross, 1993b), the nuclear receptors are now recognized to be the direct mediators of retinoid actions on the genome. Both the cytoplasmic and nuclear classes of retinoid-binding proteins are expressed early in development and are proposed to control the concentration of retinoic acid and the transcription of retinoid-responsive genes, respectively. Given the profound effects of retinoic deficiency or excess on the developing fetus, it is not surprising that mechanisms have evolved to control the placental transfer of vitamin A. Transfer is nearly uniform over a rather wide range of maternal dietary vitamin A intake. The importance of RBP in transporting retinol to tissues is suggested by the observations that the visceral yolk sac and the liver of the fetus transcribe and translate RBP. In comparison to pregnancy, vitamin A transport during lactation is much more responsive to variations in maternal vitamin A intake. The young of mothers with good vitamin A nutriture may thus accumulate significant retinol reserves during the suckling period. Conversely, young nursed by mothers with poor vitamin A status and low intake during lactation may fail to develop adequate stores and be vulnerable to vitamin A deficiency if the post-weaning diet is also poor in vitamin A. In populations with low vitamin A status, the lactation period provides an excellent window of opportunity for supplementing mothers and, indirectly, their offspring, with vitamin A to replenish the mother's vitamin A reserves and assure that the infant's growth and development are not limited by an inadequate quantity of this essential nutrient.

Dietary vitamin A restriction produces marginal vitamin A status in young rats

A model of marginal vitamin A deficiency was developed in young rats by limiting the vitamin A intake of dams and of offspring postweaning. Prior to and throughout pregnancy and lactation, female rats were fed diets in which the vitamin A concentration was either low marginal [0.18 retinol equivalent (RE)/g diet], high marginal (0.4 RE/g) or sufficient (4 RE/g). Vitamin A restriction had no effect on dams' reproduction or litter sizes, but total retinol in liver was depleted by the end of lactation. Pups fed all diets grew steadily from birth through 35 d. The milk curd total retinol concentration of 9-d-old pups' stomachs was significantly different among the low marginal, high marginal and vitamin A-sufficient groups. By 35 d, plasma retinol concentrations of pups in the low marginal group were less than half of those in the high marginal and vitamin A-sufficient groups. The liver total retinol concentrations and lecithin retinol:acyltransferase activity of 35-d-old pups in the low and high marginal groups were much lower than those of vitamin A-sufficient pups. When pups from dams fed low marginal diet were weaned onto vitamin A-free diet, frank vitamin A deficiency was evident by 33 d of age as judged by physical signs and biochemical alterations in vitamin A status. Thus, these dietary protocols are useful in inducing early onset of either marginal or frank vitamin A deficiency.

Effect of abscess milieu on bactericidal activity of LY146032 against staphylococci

The antistaphylococcal activity of LY146032 was tested in human pus in vitro and in a murine abscess model in vivo. The drug was not degraded by pus containing beta-lactamase and had equally good or better activity than nafcillin or vancomycin against Staphylococcus aureus or Staphylococcus epidermidis in vitro and in vivo. Its activity was slightly enhanced when used in combination with rifampin and tobramycin.