Reconstitution of Intestinal CD4 and Th17 T Cells in Antiretroviral Therapy Suppressed HIV-Infected Subjects: Implication for Residual Immune Activation from the Results of a Clinical Trial

Introduction
During HIV infection the severe depletion of intestinal CD4+ T-cells is associated with microbial translocation, systemic immune activation, and disease progression. This study examined intestinal and peripheral CD4+ T-cell subsets reconstitution under combined antiretroviral therapy (cART), and systemic immune activation markers.
Methods
This longitudinal single-arm pilot study evaluates CD4+ T cells, including Th1 and Th17, in gut and blood and soluble markers for inflammation in HIV-infected individuals before (M0) and after eight (M8) months of cART. From January 2010 to December 2011, 10 HIV-1 naïve patients were screened and 9 enrolled. Blood and gut CD4+ T-cells subsets and cellular immune activation were determined by flow-cytometry and plasma soluble CD14 by ELISA. CD4+ Th17 cells were detected in gut biopsies by immunohistochemistry. Microbial translocation was measured by limulus-amebocyte-lysate assay to detect bacterial lipopolysaccharide (LPS) and PCR Real Time to detect plasma bacterial 16S rDNA.
Results
Eight months of cART increased intestinal CD4+ and Th17 cells and reduced levels of T-cell activation and proliferation. The magnitude of intestinal CD4+ T-cell reconstitution correlated with the reduction of plasma LPS. Importantly, the magnitude of Th17 cells reconstitution correlated directly with blood CD4+ T-cell recovery.
Conclusion
Short-term antiretroviral therapy resulted in a significant increase in the levels of total and Th17 CD4+ T-cells in the gut mucosa and in decline of T-cell activation. The observation that pre-treatment levels of CD4+ and of CD8+ T-cell activation are predictors of the magnitude of Th17 cell reconstitution following cART provides further rationale for an early initiation of cART in HIV-infected individuals.
Trial Registration
ClinicalTrials.gov NCT02097381

引言
HIV感染过程中，肠道CD4+T细胞的严重耗竭与微生物易位、全身免疫激活及疾病进展密切相关。本研究探讨了联合抗反转录病毒治疗（combined antiretroviral therapy, cART）下肠道及外周CD4+T细胞亚群的重建情况，以及全身免疫激活标志物的变化。

方法
本项纵向单臂先导研究评估了HIV感染者在接受cART治疗前（M0）及治疗8个月后（M8）时，肠道与血液中包括Th1、Th17在内的CD4+T细胞亚群，以及炎症相关可溶性标志物水平。2010年1月至2011年12月期间，研究共筛选出10名初治HIV-1感染者，最终纳入9名受试者。研究采用流式细胞术检测血液与肠道CD4+T细胞亚群及细胞免疫激活状态，采用酶联免疫吸附试验（enzyme-linked immunosorbent assay, ELISA）检测血浆可溶性CD14水平；采用免疫组织化学法检测肠道活检组织中的CD4+Th17细胞。采用鲎试剂法（limulus amebocyte lysate assay, LAL assay）检测细菌脂多糖（lipopolysaccharide, LPS）以评估微生物易位，采用实时荧光定量PCR检测血浆细菌16S核糖体DNA（16S rDNA）。

结果
接受8个月cART治疗后，肠道CD4+T细胞及Th17细胞数量显著升高，同时T细胞激活与增殖水平降低。肠道CD4+T细胞的重建幅度与血浆LPS水平的降低呈显著相关。尤为重要的是，Th17细胞的重建幅度与血液CD4+T细胞的恢复程度呈直接正相关。

结论
短期抗反转录病毒治疗可显著提升肠道黏膜中总CD4+T细胞及Th17细胞的水平，并降低T细胞激活状态。研究发现，治疗前CD4+及CD8+T细胞的激活水平可预测cART治疗后Th17细胞的重建幅度，这一发现为HIV感染者尽早启动cART治疗提供了进一步的理论依据。

临床试验注册
ClinicalTrials.gov NCT02097381