Increases in T cell telomere length in HIV infection after antiretroviral combination therapy for HIV-1 infection implicate distinct population dynamics in CD4+ and CD8+ T cells

The Impact of HIV and Parasite Single Infection and Coinfection on Telomere Length: A Systematic Review

HIV and parasite infections accelerate biological aging, resulting in immune senescence, apoptosis and cellular damage. Telomere length is considered to be one of the most effective biomarkers of biological aging. HIV and parasite infection have been reported to shorten telomere length in the host. This systematic review aimed to highlight work that explored the influence of HIV and parasite single infections and coinfection on telomere length. Using specific keywords related to the topic of interest, an electronic search of several online databases (Google Scholar, Web of Science, Scopus, Science Direct and PubMed) was conducted to extract eligible articles. The association between HIV infection or parasite infection and telomere length and the association between HIV and parasite coinfection and telomere length were assessed independently. The studies reported were mostly conducted in the European countries. Of the 42 eligible research articles reviewed, HIV and parasite single infections were independently associated with telomere length shortening. Some studies found no association between antiretroviral therapy (ART) and telomere length shortening, while others found an association between ART and telomere length shortening. No studies reported on the association between HIV and parasite coinfection and telomere length. HIV and parasite infections independently accelerate telomere length shortening and biological aging. It is possible that coinfection with HIV and parasites may further accelerate telomere length shortening; however, this is a neglected field of research with no reported studies to date.

Blood telomere length gain in people living with HIV switching to dolutegravir plus lamivudine versus continuing triple regimen: a longitudinal, prospective, matched, controlled study

BACKGROUND

Blood telomere length (BTL) is a validated biomarker of aging. ART reduces immunosenescence and has benefits in terms of BTL in people living with HIV (PLWH). However, it has also been observed that ART containing NRTIs, such as tenofovir or abacavir, which are potent inhibitors of human telomerase activity in vitro, might negatively affect BTL. Here we investigated the effects on BTL 1 year after switching to a dual therapy (DT) with dolutegravir + lamivudine versus maintaining a standard triple therapy (TT) with a two-NRTI backbone and an anchor drug.

METHODS

This was a longitudinal, prospective, matched, controlled study that included virologically suppressed adults on stable three-drug ART who either switched at baseline (BL) to DT or maintained TT. The DT and TT groups were 1:1 matched for age, sex, years since HIV diagnosis, years on ART and anchor drug. BTL was assessed by a monochrome multiplex qPCR at BL and after 48 weeks (W48).

RESULTS

We enrolled 120 PLWH, i.e. 60 participants in each group. At BL, the BTL means were comparable between the two groups (P = 0.973). At W48, viro-immunological status was stable and an overall increase in the mean BTL was observed, i.e., +0.161 (95%CI, 0.054-0.268) (P = 0.004). However, the within-group analysis showed a significant mean BTL gain in the DT group (P = 0.003) but not in the TT group (P = 0.656).

CONCLUSIONS

In this setting of virologically suppressed PLWH, simplifying to dolutegravir + lamivudine was associated with a higher gain in BTL than maintaining triple therapy after the 1 year follow-up. These findings suggest that as a simplification strategy dolutegravir + lamivudine might have a positive effect on BTL.

Epigenetic ageing accelerates before antiretroviral therapy and decelerates after viral suppression in people with HIV in Switzerland: a longitudinal study over 17 years

BACKGROUND

Accelerated epigenetic ageing can occur in untreated HIV infection and is partially reversible with effective antiretroviral therapy (ART). We aimed to make a long-term comparison of epigenetic ageing dynamics in people with HIV during untreated HIV infection and during suppressive ART.

METHODS

In this longitudinal study, conducted over 17 years in HIV outpatient clinics in Switzerland, we applied 5 established epigenetic age estimators (epigenetic clocks) in peripheral blood mononuclear cells (PBMCs) in Swiss HIV Cohort Study participants before or during suppressive ART. All participants had a longitudinal set of PBMC samples available at four timepoints (T1-T4). T1 and T2 had to be 3 years or longer apart, as did T3 and T4. We assessed epigenetic age acceleration (EAA) and a novel rate of epigenetic ageing.

FINDINGS

Between March 13, 1990, and Jan 18, 2018, we recruited 81 people with HIV from the Swiss HIV Cohort Study. We excluded one participant because a sample did not meet quality checks (transmission error). 52 (65%) of 80 patients were men, 76 (95%) were white, and the median patient age was 43 (IQR 37·5-47) years. Per year of untreated HIV infection (median observation 8·08 years, IQR 4·83-11·09), mean EAA was 0·47 years (95% CI 0·37 to 0·57) for Horvath's clock, 0·43 years (0·3 to 0·57) for Hannum's clock, 0·36 years (0·27 to 0·44) for SkinBlood clock, and 0·69 years (0·51 to 0·86) for PhenoAge. Per year of suppressive ART (median observation 9·8 years, IQR 7·2-11), mean EAA was -0·35 years (95% CI -0·44 to -0·27) for Horvath's clock, -0·39 years (-0·50 to -0·27) for Hannum's clock, -0·26 years (-0·33 to -0·18) for SkinBlood clock, and -0·49 years (-0·64 to -0·35) for PhenoAge. Our findings indicate that people with HIV epigenetically aged by a mean of 1·47 years for Horvath's clock, 1·43 years for Hannum's clock, 1·36 years for SkinBlood clock, and 1·69 years for PhenoAge per year of untreated HIV infection; and 0·65 years for Horvath's clock, 0·61 years for Hannum's clock, 0·74 years for SkinBlood clock, and 0·51 years for PhenoAge, per year of suppressive ART. GrimAge showed some change in the mean EAA during untreated HIV infection (0·10 years, 0·02 to 0·19) and suppressive ART (-0·05 years, -0·12 to 0·02). We obtained very similar results using the rate of epigenetic ageing. Contribution of multiple HIV-related, antiretroviral, and immunological variables, and of a DNA methylation-associated polygenic risk score to EAA was small.

INTERPRETATION

In a longitudinal study over more than 17 years, epigenetic ageing accelerated during untreated HIV infection and decelerated during suppressive ART, highlighting the importance of limiting the duration of untreated HIV infection.

FUNDING

Swiss HIV Cohort Study, Swiss National Science Foundation, and Gilead Sciences.

Effects of tenofovir on telomeres, telomerase and T cell maturational subset distribution in long-term aviraemic HIV-infected adults

OBJECTIVES

To evaluate whether the negative impact of tenofovir on telomere length (TL) is due to immune reconstitution interference or inhibition of telomerase.

METHODS

One hundred and twenty-eight long-term aviraemic HIV adults treated with tenofovir-containing (n = 79) or tenofovir-sparing regimens (n = 49) were recruited to compare the following: TL in whole blood, PBMCs, CD4+ T cells and CD8+ T cells by quantitative PCR (qPCR); telomerase activity in PBMCs, CD4+ cells and CD8+ T cells using the TRAPeze RT Telomerase Detection Kit; and T cell maturational subset distribution by flow cytometry.

RESULTS

In an adjusted analysis, participants treated with tenofovir for at least 4 years had shorter TL in CD8+ T cells (P = 0.04) and lower telomerase activity in CD4+ (P = 0.012) and CD8+ T cells (P = 0.023). Tenofovir treatment was also associated with lower proportions of recent thymic emigrant (RTE) CD4+ cells (P = 0.031) and PD1 marker expression (P = 0.013).

CONCLUSIONS

In long-term aviraemic HIV adults, the inhibition of telomerase by tenofovir could explain telomere shortening in CD8+ T cells. There is no telomere shortening in the CD4+ compartment and the decrease in telomerase activity could be explained both by the inhibition by tenofovir and by the lower proportion of RTE CD4+cells.

Impact of Delaying Antiretroviral Treatment during Primary HIV Infection on Telomere Length

BACKGROUND

Telomere length (TL) shortens during aging, HIV-seroconversion and untreated chronic HIV infection. It is unknown whether early antiretroviral therapy (ART) start is associated with less TL shortening during primary HIV infection (PHI).

METHODS

We measured TL in peripheral blood mononuclear cells by quantitative PCR in participants of the Zurich PHI Study with samples available for >6 years. We obtained uni-/multivariable estimates from mixed-effects models and evaluated the association of delaying ART start or interrupting ART with baseline and longitudinal TL.

RESULTS

In 105 participants with PHI (median age 36 years, 9% women), median ART delay was 25, 42, and 60 days, respectively, in the 1 st (shortest), 2 nd, and 3 rd (longest) ART delay tertile. First ART delay tertile was associated with longer baseline TL (p for trend=0.034), and longer TL over 6 years, but only with continuous ART (p<0.001), not if ART was interrupted >12 months (p=0.408). In multivariable analysis, participants in the 2 nd and 3 rd ART delay tertile had 17.6% (5.4-29.7%; p=0.004) and 21.5% (9.4-33.5%; p<0.001) shorter TL, after adjustment for age, with limited effect modification by clinical variables.

DISCUSSION

In PHI, delaying ART start for even a matter of weeks was associated with significant and sustained TL shortening.

Correlation between blood telomere length and CD4+ CD8+ T-cell subsets changes 96 weeks after initiation of antiretroviral therapy in HIV-1-positive individuals

In 31 participants who started first-line antiretroviral therapy in the NEAT 001/ANRS 143 clinical trial, we found after 96 weeks a statistically significant increase in blood telomere length (TL) of 0.04 (T/S Ratio) (p = 0.03). This increase was positively correlated with both the change in the percentage of CD4+ T-cells and with the decrease of CD38+ molecules on Central Memory CD8+ and negatively correlated with the change in the percentage of CD4+ Effector Memory cells. Increase in TL could be an expression of immune reconstitution and the associated decrease in immune activation. We acknowledge for the low statistical power due to the small sample size and the potential for false positive results due to multiple testing. Hence, further studies are needed to confirm these observations.

Impact of Nucleos(t)ide Reverse Transcriptase Inhibitors on Blood Telomere Length Changes in a Prospective Cohort of Aviremic HIV-Infected Adults

Background

Tenofovir is a potent inhibitor of human telomerase. The clinical relevance of this inhibition is unknown.

Methods

A prospective cohort of human immunodeficiency virus (HIV)-infected participants with suppressed virological replication was recruited to compare whole-blood telomere length (measured by quantitative multiplex polymerase chain reaction analysis) in participants with current exposure to tenofovir disoproxil fumarate (TDF) to that in participants never exposed to TDF.

Results

A total of 172 participants were included: 67 were in the TDF group, and 105 were in the non-TDF group (75 were receiving 2 nucleosides [of whom 69 were receiving abacavir], 25 were receiving a nucleos[t]ide reverse transcriptase inhibitor [N{t}RTI]-sparing regimen, and 5 were receiving lamivudine as the only nucleoside). After 2 years, the mean blood telomere length increased significantly in the whole cohort. The TDF group had significantly smaller gains in telomere length than the non-TDF group. In the analysis restricted to participants receiving N(t)RTIs, TDF exposure was not associated with an independent negative effect. In the non-TDF group, participants treated with 2 nucleosides also had significantly smaller gains in telomere length than those receiving N(t)RTI-sparing regimens or lamivudine as the only nucleoside.

Discussion

In HIV-infected adults with prolonged virological suppression, treatment with TDF or abacavir was associated with smaller gains in blood telomere length after 2 years of follow-up.

Blood Telomere Length Changes After Ritonavir-Boosted Darunavir Combined With Raltegravir or Tenofovir-Emtricitabine in Antiretroviral-Naive Adults Infected With HIV-1

Background

Tenofovir is a potent inhibitor of human telomerase. The clinical relevance of this inhibition is unknown.

Methods

NEAT001/ANRS143 is a randomized trial that showed noninferiority over 96 weeks of ritonavir-boosted darunavir plus raltegravir versus tenofovir disoproxil fumarate/emtricitabine in 805 antiretroviral antiretrovrial-naive HIV-infected adults. We compared changes in whole-blood telomere length measured with quantitative polymerase chain reaction in 201 randomly selected participants (104 raltegravir and 97 tenofovir disoproxil fumarate/emtricitabine). We performed multivariable estimative and predictive linear regression.

Results

At week 96, participants receiving tenofovir disoproxil fumarate/emtricitabine had a statistically significant higher gain in telomere length than participants receiving raltegravir. Difference in mean telomere length change between groups (tenofovir disoproxil fumarate/emtricitabine minus raltegravir) from baseline to week 96 adjusted by baseline telomere length was 0.031 (P = .009). This difference was not significantly confounded by age, gender, known duration of HIV infection, CD4 (baseline/nadir), CD8 cells, CD4/CD8 ratio, HIV viral load (baseline/week 96), tobacco and alcohol consumption, statins, or hepatitis C.

Conclusion

Antiretroviral-naive HIV-infected adults receiving ritonavir-boosted darunavir and tenofovir disoproxil fumarate/emtricitabine had a significant higher gain in blood telomere length than those receiving ritonavir-boosted darunavir and raltegravir, suggesting a better initial recovery from HIV-associated immunosenescence.

Correlates of telomere length shortening in peripheral leukocytes of HIV-infected individuals and association with leukoaraiosis

Telomere length (TL) is a marker of cellular and biological aging. Human immunodeficiency virus (HIV) infection has been reported to be associated with short TLs, which suggests that accelerated biological aging occurs in some cellular compartments of HIV+ individuals. In this study, we measured the TLs of peripheral leukocytes of HIV+ and healthy individuals and examined the biological and environmental correlates of TL. We also investigated the influence of TL on leukoaraiosis, an indicator of cerebral small vessel disease, in HIV+ individuals. Three hundred and twenty-five HIV+ individuals who received stable combination antiretroviral therapy (cART) for >1 year and achieved viral loads of <40 RNA copies/mL were enrolled along with 147 healthy individuals. Relative TLs of leukocytes were estimated by quantitative real-time polymerase chain reaction. Leukoaraiosis was assessed in 184 HIV+ individuals by fluid-attenuated inversion recovery magnetic resonance imaging. We analyzed several covariates, including markers of HIV infection, cART, and social/environmental factors; variables associated with TL length in univariate analyses were incorporated into multivariate models. The TLs of peripheral leukocytes of HIV+ individuals were significantly shorter than those of healthy individuals, and the rate of LT length decline with increasing age was greater. Linear regression analysis showed that in HIV+ individuals, increasing age, cART without integrase-stand transfer inhibitors (INSTI), failure to achieve viral loads of <40 copies/mL within 1 year of initiating cART, and substance use were significantly associated with shorter TLs, even after adjustment for the effects of age. Logistic regression analysis indicated an increasing risk of leukoaraiosis was associated with older age, shorter TLs, hypertension, and carotid artery plaque. Multivariate regression analysis indicated that older age and shorter TLs were significant risk factors for leukoaraiosis. In summary, our data showed that TL shortening in HIV+ individuals was independently associated with leukoaraiosis, and was associated with age, control of viral loads, use of INSTI, and substance use. Our results suggest that effective viral control and less toxic cART can help reduce TL shortening and improve outcomes among HIV+ individuals.

Dynamics of leukocyte telomere length in pregnant women living with HIV, and HIV-negative pregnant women: A longitudinal observational study

Background

HIV-mediated inflammation and immune activation can accelerate telomere attrition. In addition, antiretrovirals can inhibit telomerase, possibly shortening telomeres. We examined the longitudinal dynamics of leukocyte telomere length (LTL) during pregnancy in a unique cohort of women living with HIV (WLWH) treated with combination antiretroviral therapy (cART), and HIV-negative control women.

Methods

Blood was collected at three visits during pregnancy, at 13–23, >23–30, and >30–40 weeks of gestation, and for WLWH only, at 6 weeks post-partum. LTL was measured by qPCR and both cross-sectional and longitudinal (MANOVA) models were used to examine possible predictors of LTL among participants who attended all three visits during pregnancy.

Results

Among WLWH (n = 64) and HIV-negative women (n = 41), within participant LTL were correlated throughout pregnancy (p<0.001). LTL was shorter among WLWH at first visit, but this difference waned by the second visit. WLWH who discontinued cART post-partum experienced a decrease in LTL. Longitudinally, LTL was similar in both groups and increased as gestation progressed, a change that was more pronounced among women under 35 years. Among WLWH, both smoking throughout pregnancy (p = 0.04) and receiving a ritonavir-boosted protease inhibitor-based regimen (p = 0.03) were independently associated with shorter LTL.

Conclusions

LTL increases as pregnancy progresses; the reasons for this are unknown but may relate to changes in blood volume, hormones, and/or cell subset distribution. While our observations need confirmation in an independent cohort, our data suggest that although some cART regimens may influence LTL, being on cART appears overall protective and that stopping cART post-partum may negatively impact LTL. The effect of smoking on LTL is clearly negative, stressing the importance of smoking cessation.

Harnessing CD8+ T Cells Under HIV Antiretroviral Therapy

Antiretroviral therapy (ART) has transformed HIV from a fatal disease to a chronic condition. In recent years there has been considerable interest in strategies to enable HIV-infected individuals to cease ART without viral rebound, either by purging all cells infected harboring replication-competent virus (HIV eradication), or by boosting immune responses to allow durable suppression of virus without rebound (HIV remission). Both of these approaches may need to harness HIV-specific CD8⁺ T cells to eliminate infected cells and/or prevent viral spread. In untreated infection, both HIV-specific and total CD8⁺ T cells are dysfunctional. Here, we review our current understanding of both global and HIV-specific CD8⁺ T cell immunity in HIV-infected individuals with durably suppressed viral load under ART, and its implications for HIV cure, eradication or remission. Overall, the literature indicates significant normalization of global T cell parameters, including CD4/8 ratio, activation status, and telomere length. Global characteristics of CD8⁺ T cells from HIV⁺ART⁺ individuals align more closely with those of HIV-seronegative individuals than of viremic HIV-infected individuals. However, markers of senescence remain elevated, leading to the hypothesis that immune aging is accelerated in HIV-infected individuals on ART. This phenomenon could have implications for attempts to prime de novo, or boost existing HIV-specific CD8⁺ T cell responses. A major challenge for both HIV cure and remission strategies is to elicit HIV-specific CD8⁺ T cell responses superior to that elicited by natural infection in terms of response kinetics, magnitude, breadth, viral suppressive capacity, and tissue localization. Addressing these issues will be critical to the success of HIV cure and remission attempts.

Assessing immune aging in HIV-infected patients

Many of the alterations that affect innate and adaptive immune cell compartments in HIV-infected patients are reminiscent of the process of immune aging, characteristic of old age. These alterations define the immunological age of individuals and are likely to participate to the decline of immune competence with HIV disease progression. It is therefore important to characterize these changes, which point toward the accumulation of highly differentiated immunocompetent cells, associated with overall telomere length shortening, as well as understanding their etiology, especially related to the impact of chronic immune activation. Particular attention should be given to the exhaustion of primary immune resources, including haematopoietic progenitors and naïve cells, which holds the key for effective hematopoiesis and immune response induction, respectively. The alteration of these compartments during HIV infection certainly represents the foundation of the immune parallel with aging.

HIV-DNA content in different CD4+ T-cell subsets correlates with CD4+ cell : CD8+ cell ratio or length of efficient treatment

OBJECTIVES

HIV establishes a latent infection at different degrees within naïve (TN) or central (TCM) and effector memory (TEM) CD4 T cell. Studying patients in whom HIV production was suppressed by combined antiretroviral therapy, our main aim was to find which factors are related or can influence intracellular viral reservoir in different CD4 T-cell subsets.

METHODS

We enrolled 32 HIV patients successfully treated for more than 2 years, with a CD4 T-cell count more than 500 cells/μl and plasma viremia undetectable from at least 1 year. Proviral HIV-DNA, the amount of cells expressing signal-joint T-cell receptor rearrangement excision circles and telomere length were quantified by droplet digital PCR in highly purified, sorted CD4 T-cell subsets; plasma IL-7 and IL-15 were measured by ELISA.

RESULTS

HIV-DNA was significantly lower in TN cells compared with TCM or to TEM. Conversely, TN cells contained more signal-joint T-cell receptor rearrangement excision circles compared with TCM or to TEM; no appreciable changes were observed in telomere length. HIV-DNA content was significantly higher in TN and TCM cells, but not in TEM, from patients with shorter time of treatment, or in those with lower CD4 : CD8 ratio.

CONCLUSION

Length of treatment or recovery of CD4 : CD8 ratio significantly influences viral reservoir in both TN and TCM. Measuring HIV-DNA in purified lymphocyte populations allows a better monitoring of HIV reservoir and could be useful for designing future eradication strategies.

Telomere length is associated with sleep duration but not sleep quality in adults with human immunodeficiency virus

BACKGROUND AND STUDY OBJECTIVE

Telomere length provides an estimate of cellular aging and is influenced by oxidative stress and health behaviors such as diet and exercise. This article describes relationships between telomere length and sleep parameters that included total sleep time (TST), wake after sleep onset (WASO), and self-reported sleep quality in a sample of adults with chronic illness.

DESIGN AND PARTICIPANTS

Cross-sectional study of 283 adults (74% male, 42% Caucasian) infected with human immunodeficiency virus (HIV) while living in the San Francisco Bay area, CA, USA. Ages ranged from 22-77 y.

MEASUREMENTS AND RESULTS

TST and WASO were estimated with wrist actigraphy across 72 h; self-reported sleep quality was assessed with the Pittsburgh Sleep Quality Index. Relative telomere length (RTL) in leukocytes was estimated by quantitative polymerase chain reaction assays. Shorter RTL was associated with older age, and RTL was shorter in males than females. RTL was unrelated to HIV disease characteristics. RTL was not associated with WASO or self-reported sleep quality. Participants with at least 7 h sleep had longer RTL than those with less than 7 h, even after controlling for the effects of age, sex, race, education, body mass index, metabolic hormones (i.e., leptin, ghrelin, adiponectin, and resistin), depression and anxiety, and sleep quality.

CONCLUSION

Results suggest that sleep duration is associated with preserving telomere length in a population of human immunodeficiency virus-infected adults. Getting at least 7 hours of sleep at night may either protect telomeres from damage or restore them on a nightly basis.

Multiparameter evaluation of human thymic function: interpretations and caveats

After the provision of highly active antiretroviral therapy (HAART), the level of circulating CD4+ T cells increases in many adults infected with the human immunodeficiency virus, type 1 (HIV). To study factors involved in immune reconstitution, we have measured thymic abundance by CT scans, circulating naive-phenotype CD4+ T cells by flow cytometry, and T cell receptor (TCR) rearrangement excision circles (TRECs) by quantitative PCR in 40 virologically suppressed, HIV-infected adults and 33 age-matched, HIV-uninfected controls. In HIV-uninfected subjects, naive T cell numbers, thymic abundance, and the frequency of circulating naive CD4+ T cells bearing TRECs decreased with age, as expected. When corrected for this relationship with age, naive T cell numbers correlated significantly with naive T cell TREC frequencies. Virologically suppressed HIV-infected subjects had higher TREC frequencies, and subjects over the age of 39 were more likely to have abundant thymus compared to age-matched, HIV-uninfected adults. Nevertheless, all HIV-infected subjects had reduced absolute numbers of naive T cells, irrespective of thymic size, age, or TREC frequencies. These data illustrate the complex relationship between these measures of thymic size and function and underscore the need to develop more definitive measures of thymic function in the future.

Evaluation of the impact of highly active antiretroviral therapy on immune recovery in antiretroviral naive patients

OBJECTIVES

To examine the extent of immune reconstitution in treatment-naive patients with CD4 T-cell counts <500 cells/microL following 48 weeks of highly active antiretroviral therapy (HAART).

METHODS

Thirteen antiretroviral naive patients were evaluated longitudinally for 48 weeks on HAART utilizing immune functional and lymphocyte phenotyping assays, including lymphocyte proliferation assay, flow cytometric evaluation of cell surface markers, and delayed type hypersensitivity skin tests. Virologic responses were monitored using commercially available viral load assays and gag/pol mRNA quantification using simultaneous immunophenotyping/UltraSensitive fluorescence in situ hybridization (ViroTect In Cell HIV-1 Detection Kit; Invirion, Frankfort, MI). Thymic function was evaluated for a subset of four patients using real-time polymerase chain reaction (PCR) for T-cell receptor excision circle (TREC) quantification and thymic scans using computerized axial tomography (CT) of the thymus.

RESULTS

HAART initiation resulted in a significant decline in plasma viremia and percentage of infected peripheral blood cells, and a rise in CD4 T cells from a baseline median of 207 cells/microL to a week-48 median of 617 cells/microL. The rise was predominately in CD4 memory cells. Naive T cells also increased in number, but at a slower rate. Activated (HLA-DR CD38) CD4 and CD8 T cells were elevated at baseline (24 and 62%, respectively) and declined by week 48 (17 and 36%, respectively) but did not reach normal levels. The number of Fas CD4 T cells increased from a baseline median of 169 to 381 cells/microL at week 48. Both soluble interleukin (IL)-2 and tumour necrosis factor (TNF) II receptors declined by week 48. HIV p24 lymphocyte proliferation assay responses were transiently detected in three patients. TREC values increased from a median 6400 copies/microg at baseline to a week-48 median value of 26 697 copies/microg.

CONCLUSION

Immune functional reconstitution was not achieved in these HAART naive patients.

T-cell receptor excisional circles, telomere length, proliferation and apoptosis in peripheral blood mononuclear cells of human immunodeficiency virus-infected individuals after 18 months of treatment induced viral suppression

This study evaluated the effect of highly active antiretroviral therapy (HAART)-induced viral suppression on T-cell receptor excisional circles (TRECs), telomere length, proliferative responses and spontaneous as well as phytohaemagglutinin (PHA)-stimulated lymphocyte apoptosis in 27 human immunodeficiency virus (HIV)-infected individuals followed for 18 months during HAART. Our results show that HAART significantly increased the level of TRECs in CD4+ cells (P = 0.003) after 18 months of almost continuously suppressed HIV-RNA levels. Lymphocyte proliferative responses and apoptosis levels in patients were significantly lower and significantly higher, respectively, compared with healthy controls. The proliferative response and apoptosis levels did not change during follow up. Changes in telomere length were observed in CD4+ and in CD8+ T cells. The study demonstrated that HAART induces normal TREC levels in the CD4+ T-cell pool. However, the other perturbed functions in T cells indicate that immune reconstitution is incomplete and may need longer viral suppression.

Proliferation and telomere length in acutely mobilized blood mononuclear cells in HIV infected patients

The aim of the study was to investigate the mobilization of T cells in response to a stressful challenge (adrenalin stimulation), and to access T cells resided in the peripheral lymphoid organs in HIV infected patients. Seventeen patients and eight HIV seronegative controls received an adrenalin infusion for 1 h. Blood was sampled before, during and 1 h after adrenalin infusion. Proliferation and mean telomere restriction fragment length (telomeres) of blood mononuclear cells (BMNC) and purified CD8+ and CD4+ cells were investigated at all time points. In patients, the proliferation to pokeweed mitogens (PWM) was lower and decreased more during adrenalin infusion. After adrenalin infusion the proliferation to PWM was restored only in the controls. In all subjects telomeres in CD4+ cells declined during adrenalin infusion. Additionally, the patients had shortened telomeres in their CD8+ cells, and particularly HAART treated patients had shortened telomeres in all cell-subtypes. The finding that patients mobilized cells with an impaired proliferation to PWM during and after adrenalin infusion has possible clinical relevance for HIV infected patients during pathological stressful conditions, such as sepsis, surgery and burns. However, this study did not find a correlation between impaired proliferation and telomeres. It is concluded that physiological stress further aggravates the HIV-induced immune deficiency.

T-cell mean telomere lengths changes in treatment naïve HIV-infected patients randomized to G-CSF or placebo simultaneously with initiation of HAART

The effect of highly active antiretroviral therapy (HAART) and granulocyte colony stimulating factor (G-CSF) on mean telomere restriction fragment (TRF) length of peripheral blood mononuclear cells (PBMC) was examined in 11 treatment naïve human immunodeficiency virus (HIV)-infected individuals with a CD4+ T-cell count < 350 cells/mm3. Patients were randomized to HAART combined with G-CSF thrice weekly for 12 weeks (n = 6) or placebo (n = 5). An increase in the mean TRF lengths was observed in PBMC of patients on HAART after 24 weeks of treatment mainly owing to increased mean CD8+ T-cell TRF lengths. However, in the group of patients on HAART combined with G-CSF no changes of PBMC mean TRF length was observed during treatment or during 12 weeks of follow-up. The mean CD4+ T-cell TRF length did not change in any of the two groups. These results confirm that HAART induces mainly the lengthening of the mean CD8+ T-cell TRF length. However, G-CSF given simultaneously with HAART induces an inhibition of the expected lengthening in mean TRF length. These results do therefore not support the use of adjuvant G-CSF treatment simultaneously when initiating HAART and should further be evaluated before use in non-neutropenic HIV-infected patients.

Effects of subcutaneous IL-2 therapy on telomere lengths in PBMC in HIV-infected patients

In this study we investigated the effect of interleukin-2 (IL-2) on mean terminal restriction fragment (TRF) lengths in peripheral blood mononuclear cells (PBMC). Ten human immunodeficiency virus (HIV)-infected individuals were included and IL-2 was administered subcutaneously with 3 x 106 IU three times a week for 24 weeks. Mean TRF length was decreased on average by 267 bp at week 4 (P = 0.03) and 286 bp at week 8 (P = 0.09). Individual TRF changes at weeks 12, 16, 20 and 24 were highly variable. However, in the 12 weeks following therapy, TRF lengths generally increased reaching baseline levels by the end of the study. At baseline, mean TRF lengths were positively correlated to the ratio of naïve and memory phenotype within both CD4+ and CD8+ cells. This study shows that IL-2 treatment induces transient shortened mean TRF lengths in PBMC from HIV-infected individuals, indicating that IL-2 enhances the lymphocyte count by peripheral proliferation or recruitment of memory T cells into the blood.

Simultaneous flow cytometric analysis of cell surface markers and telomere length: analysis of human tonsilar B cells

Telomere Flow FISH is a recently developed method which allows the measurement of telomere length in purified subsets of cells using flow cytometry. However, the harsh conditions required for flow FISH have precluded its use with conventional cell surface staining, thus limiting its utility for large scale clinical studies. We have now developed a method which permits simultaneous analysis of cell surface markers along with telomere length estimation by flow cytometry. This new assay employs the covalent crosslinking of monoclonal antibodies conjugated with a heat stable fluorochrome to the cell surface prior to flow FISH. Using this technique we have confirmed that human germinal center B cells (IgD(-)/CD38(+)) have dramatically longer telomeres than pre-germinal center founder B cells (IgD(+)/CD38(+)). This approach simplifies the analysis of complex cell populations and will facilitate widespread investigation of telomere length in health and disease states.

Preferential S phase entry and apoptosis of CD4(+) T lymphocytes of HIV-1-infected patients after in vitro cultivation

We have studied the relationship between spontaneous apoptosis and cell cycle perturbations in circulating peripheral blood lymphocytes of HIV-1-infected patients and healthy controls. PBMC obtained from HIV-1-infected patients and healthy controls were incubated in culture medium for 48 h. Cells were separated into CD4(+) and CD8(+) populations using immunomagnetic beads. Apoptosis and cell cycle phases were measured by propidium iodide staining and bromodeoxyuridine (BrdU) incorporation followed by flow cytometric analyses. In experiments using cells obtained from HIV-1-infected patients, spontaneous apoptosis was more frequent in CD4(+) T lymphocytes than in CD8(+) T lymphocytes (17.6% vs 9.5%, P < 0.005). Among healthy controls, spontaneous apoptosis in CD4(+) and CD8(+) T lymphocytes was comparable (4.5% vs 5.1%). Lymphocytes obtained from patients were more frequently in S phase than healthy controls' cells (2.2 +/- 0.9% vs 0.5 +/- 0.2%, P < 0.002) and patients' CD4(+) cells tended to enter S phase more frequently than controls' CD4(+) cells (4.2% +/- 3.5% vs 1.8% +/- 0.5% P < 0.04), whereas the frequency of S phase CD8(+) T cells was not different among patients (2.8% +/- 2.9%) and controls (1.8% +/- 0.5%) (P > 0.4). Kinetic analyses using BrdU and PI staining revealed that S phase cells were more likely to become apoptotic than resting (G(0)-G(1)) cells (28.4% +/- 10.3% vs 11.3% +/- 9.9% in patients, P < 0.04, and 15.3% +/- 2.8% vs 1.8% +/- 0.5% in controls, P < 0.003). Lymphocytes obtained from HIV-1-infected persons are activated in vivo to enter S phase and to undergo spontaneous apoptosis after brief in vitro cultivation. The present studies indicate that most apoptotic cells in this system are CD4(+) and kinetic analyses reveal that S phase cells are more likely to undergo spontaneous apoptosis than G(0)-G(1) cells. Accelerated cell death in HIV-1 disease may contribute to the failure of lymphocyte responsiveness to appropriate T cell receptor stimulation.

Effects of G-CSF on telomere lengths in PBMCs from human immunodeficiency virus-infected patients: results from a randomized, placebo-controlled trial

Telomeres are unique terminal chromosomal structures, the length of which has been shown to decrease with cell division in vitro and with increased age in vivo for human somatic cells. In human immunodeficiency virus (HIV)-1 infection, decrease of telomere length is primarily found in CD8+ T cells, and not in CD4+ T cells. In this double-blind placebo-controlled study, we investigated the effect of granulocyte colony stimulating factor (G-CSF) treatment combined with highly active antiretroviral therapy (HAART) on mean telomere length in peripheral blood mononuclear cells (PBMC). The terminal restriction fragment (TRF) length showed no changes during G-CSF treatment although the number of lymphocytes increased significantly. The mean TRF length correlated positively (R = 0.552, P = 0.009) and negatively (R = -0.503, P = 0.02) to the proportion of CD4+ memory and naïve cells, respectively. Our data suggest that during G-CSF treatment lymphocytes are recruited by a combination of central and peripheral proliferation.

The role of telomerase expression and telomere length maintenance in human and mouse

The molecular regulation of telomere length has been well elucidated by a series of elegant studies over the past decade. More recently, experimental evidence has accrued that addresses the challenging question of if and how telomere length regulation may contribute to normal human aging or to human disease. Recent studies in mice have provided a mammalian precedent indicating that telomerase deficiency can lead to in vivo dysfunction, most probably as a consequence of progressive telomere shortening. In humans, the evidence that telomere shortening might lead to in vivo dysfunction is far less direct, although the recent description of telomerase deficiency and telomere shortening associated with the DKC syndrome is suggestive of such a link. Methodologies exist and continue to be developed that are increasingly capable of manipulating telomerase activity and telomere length in human cells. It remains to be determined whether scientifically rigorous and (equally important) medically ethical approaches will emerge to directly assess the ability of telomere length modulation to correct functional disorders of human cellular function ex vivo or more challenging still, in vivo.