Comparison of thymic function-related markers to predict early CD4 T-cell repopulation in adult HIV-infected patients on HAART

The aim of this work was to compare thymic function-related markers for predicting early CD4 T-cell repopulation in adult HIV-infected patients under HAART. Forty-three consecutive antiretroviral-naive patients were prospectively analysed for clinical, biochemical, immunological and virological parameters at starting HAART, and followed for 4 weeks and every 12 weeks thereafter. At baseline, all patients underwent a thoracic computer tomography scan, in order to measure thymic volume, as well, T-cell phenotype (naive CD4 and CD8 T cells) and the number of TREC-bearing cells were obtained. CD4 cell repopulation was considered as an increase > or = 200 cells/mm3 above baseline count. Twenty-seven patients (62.8%) increased > or = 200 cells/mm3 above baseline levels during the follow-up. The median time to event was 182 days (84-537 days). On the univariate analysis, to be younger than 36 years, showing a CD4 cell count > or = 272 cells/mm3, a total naive T-cell count > or = 128 cells/mm3, a TREC-bearing cell count > or = 0.74 cells/mm3, and a thymic volume > or =3.07 cc at baseline were statistically associated to the event studied. However, when the multivariate analysis was performed, only thymic volume at baseline was independently associated (P=0.002) to CD4 cell recovery. This co-variable was identified as a positive predictor [hazard ratio, 1.22 (95% confidence interval: 1.16-1.28)]. In summary, data presented herewith show that thymic volume is the best thymic function-related marker for predicting early CD4 T-cell recovery in adult HIV-infected patients under HAART.

Endogenous IL-7 is associated with increased thymic volume in adult HIV-infected patients under highly active antiretroviral therapy

OBJECTIVE

Immune reconstitution after highly active antiretroviral therapy (HAART) in HIV-infected patients has led to an increase in the number of new CD4 T lymphocytes. Neolymphopoiesis in the thymus has been proposed as a mechanism in T-cell regeneration. Nevertheless, factors involved in the regeneration of T cells by thymic-dependent pathways in HIV-infected patients under HAART are still unknown and might be of relevance in HIV infection. The aim of this work was to study the role of IL-7 in the thymic rebound of HIV-infected adults under HAART.

DESIGN

To study the association between IL-7 and thymic function-related markers, these variables were measured in 49 antiretroviral-naive HIV-infected patients at baseline and at weeks 12, 24, 36 and 48 of treatment.

METHODS

Thymic function-related markers: thymic volume, naive phenotype, and T-cell receptor excision circles (TREC) bearing-cells, were evaluated by computed tomography, flow cytometry, and quantitative polymerase chain reaction, respectively. IL-7 levels were evaluated using a high sensitivity colorimetric enzyme-linked immunosorbent assay.

RESULTS

At baseline, we found an inverse correlation between IL-7 levels and thymic function-associated parameters: thymic volume, naive T cells and TREC-bearing cells. After 48 weeks of therapy increased levels of thymic function-related markers along with a significant decrease in IL-7 levels were found. IL-7 levels at baseline were the only independently associated variable with respect to changes in thymic volume at weeks 12, 24 and 48 of follow-up.

CONCLUSION

These data suggest that IL-7 plays an important role in thymic rebound in adult HIV-infected patients under HAART.

Comparison of Thymic Function-Related Markers to Predict Early Cd4 T-Cell Repopulation in Adult HIV-Infected Patients on Haart

The aim of this work was to compare thymic function-related markers for predicting early CD4 T-cell repopulation in adult HIV-infected patients under HAART. Forty-three consecutive antiretroviral-naive patients were prospectively analysed for clinical, biochemical, immunological and virological parameters at starting HAART, and followed for 4 weeks and every 12 weeks thereafter. At baseline, all patients underwent a thoracic computer tomography scan, in order to measure thymic volume, as well, T-cell phenotype (naive CD4 and CD8 T cells) and the number of TREC-bearing cells were obtained. CD4 cell repopulation was considered as an increase ≥200 cells/mm3 above baseline count. Twenty-seven patients (62.8%) increased ≥200 cells/mm3 above baseline levels during the follow-up. The median time to event was 182 days (84–537 days). On the univariate analysis, to be younger than 36 years, showing a CD4 cell count ≥272 cells/mm3, a total naive T-cell count ≥128 cells/mm3, a TREC-bearing cell count ≥0.74 cells/mm3, and a thymic volume ≥3.07 cc at baseline were statistically associated to the event studied. However, when the multivariate analysis was performed, only thymic volume at baseline was independently associated ( P=0.002) to CD4 cell recovery. This co-variable was identified as a positive predictor [hazard ratio, 1.22 (95% confidence interval: 1.16–1.28)]. In summary, data presented herewith show that thymic volume is the best thymic function-related marker for predicting early CD4 T-cell recovery in adult HIV-infected patients under HAART.

Baseline thymic volume is a predictor for CD4 T cell repopulation in adult HIV-infected patients under highly active antiretroviral therapy

The objective of the present study was to assess the impact of baseline thymic volume on the CD4 cell repopulation induced by highly active antiretroviral therapy (HAART) in HIV-infected adults. Therefore, 37 previously untreated HIV-1-infected adults were prospectively followed from August 1998 to September 2001. All patients underwent a thorax CT scan at starting HAART to measure thymic volume. The median follow-up time was 189 [87.5-498.5] days. CD4 cell repopulation was considered as an increase > or = 200 cells/mm3 above baseline count. Twenty-one (57%) patients achieved this CD4 repopulation. Baseline thymic volume was the main independent factor associated with CD4 repopulation (P = 0.016); this factor was a positive predictor (adjusted hazard ratio: 1.25 [95% confidence interval 1.1-1.4]). Although, CD4 cell count and non-AIDS diagnosis at baseline were associated with CD4 cell repopulation on the univariate analysis (P = 0.03 and P = 0.02, respectively), no statistical signification was found on the multivariate test. In summary, baseline thymic volume is a predictor of early CD4 cell repopulation in adult HIV-1-infected patients taking HAART.

Protein kinase C mu selectively activates the mitogen-activated protein kinase (MAPK) p42 pathway

Here we show that human protein kinase C mu (PKC mu) activates the mitogen-activated protein kinase (MAPK). Transient expression of constitutive active PKC mu leads to an activation of Raf-1 kinase as demonstrated by in vitro phosphorylation of MAPK. PKC mu enhances transcriptional activity of a basal thymidine kinase promotor containing serum response elements (SREs) as shown by luciferase reporter gene assays. SRE driven gene activation by PKC mu is triggered by the Elk-1 ternary complex factor. PKC mu-mediated activation of SRE driven transcription can be inhibited by the MEK1 inhibitor PD98059. In contrast to the activation of the p42/ERK1 MAPK cascade, transient expression of constitutive active PKC mu does neither affect c-jun N-terminal kinase nor p38 MAPK.