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IL-2 Therapy Effective in Acute HIV & HAART
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"IL-2 therapy restores CD8 cell non-cytotoxic anti-HIV responses in primary infection subjects receiving HAART"
AIDS: Volume 18(15), 21 October 2004
Martinez-Mariño, Beatriz; Shiboski, Stevea; Hecht, Frederick M; Kahn, James O; Levy, Jay A
From the Department of Medicine, University of California, San Francisco, and the aDepartment of Epidemiology and Biostatistics, University of San Francisco San Francisco, CA, USA.
Note from Jules Levin: the final study data examining the clinical benefit of IL-2 associated increases in CD4 are not in yet, but anecdotal reports I hear continue to support that IL-2 associated Cd4 increases are clinically beneficial. In France, IL-2 is used to treat patients with low CD4s who do not achieve adequate CD4 increases from HAART.
Abstract
Objective: To determine the effect of interleukin-2 (IL-2) therapy on immunologic and virologic responses in subjects with acute or recent HIV infection already receiving highly active antiretroviral therapy (HAART).
Methods: The effect of IL-2 therapy on immunologic and virologic responses was studied in 21 acutely infected individuals who had been receiving HAART for 48 weeks following acute or recent HIV infection. Nine subjects receiving no therapy served as controls. Viral loads, as well as CD4 and CD8 cell counts were monitored and the CD8 cell non-cytotoxic anti-HIV response (CNAR) was measured.
Results:
IL-2 therapy led to significant increases in CD4 cell numbers (P = 0.005) that were maintained for 6 months after discontinuation of the IL-2 treatment.
Subjects receiving antiretroviral therapy (HAART + IL-2 or HAART alone) showed substantial increases in CD4 cell numbers (mean) from baseline to 96 weeks compared to untreated subjects (P = 0.009, Kruskal-Wallis test). The observed increases in CD4 cell levels among HAART + IL-2 treated subjects were also significantly greater than those noted for subjects treated with HAART alone (P = 0.04, Kruskal-Wallis test). These differences were already noticeable by week 72 (after receiving three cycles of IL-2) in the HAART + IL-2 treated individuals with a mean CD4 cell count of 1108 × 106 cells/l compared to 721 × 106 cells/l for the HAART-treated subjects (P = 0.005, Kruskal-Wallis test). No substantial differences were observed in the CD8 cell numbers for the three treatment groups through week 120 (Table 2) (P = 0.3, Kruskal-Wallis test).
No effect of IL-2 was observed on viral loads or the CD8 cell numbers as compared to subjects receiving HAART alone.
CNAR activity was restored among subjects receiving HAART and IL-2 whereas CNAR declined among those receiving HAART alone and in untreated infected subjects.
The percentage of HAART subjects with CD8 cells showing at least 50% suppression of HIV replication increased significantly following IL-2 therapy (P = 0.02) and persisted for 6 months.
Conclusions: In primary HIV infection administering IL-2 concomitant with HAART following 1 year of treatment with HAART gives a significant increase in CD4 cells and a previously unrecognized beneficial effect on the CD8 cell non-cytotoxic anti-HIV response.
Author's Discussion
In subjects receiving HAART for 1 year after the diagnosis of primary HIV-1 infection, the effect of the subsequent concomitant administration of IL-2 was evaluated on CD4/CD8 cell numbers, viral load and the CNAR. CNAR involves suppression of HIV replication by CD8 lymphocytes without killing the infected CD4 cells; it is not MHC-restricted, and is observed with a very low CD8 cell/CD4 cell input. CNAR can be demonstrated with a wide variety of HIV-1 and HIV-2 isolates. All of these features suggest that this anti-HIV activity is an innate immune response.
Individuals who initiated the joint therapy had stable CD8 cell counts and showed CD4 cell numbers that increased progressively with each IL-2 cycle accounting for an overall CD4 cell count increase of 205% after receiving the final IL-2 injection (cycle six). High CD4 cell numbers were even detectable 6 months after completion of the HAART + IL-2 therapy (data not shown). No dramatic changes associated with viral load were observed throughout the length of the study. In most cases viral RNA was below the level of detection. These results with CD4 cell counts and viral load confirm previously reported data on the effect of IL-2 on acutely and chronically infected subjects and the ability of IL-2 to restore or enhance certain HIV-specific immune functions. Importantly, our results demonstrate that cellular anti-HIV activity, mirrored by CNAR, was improved (mean activity, 59%) with the addition of subcutaneous IL-2 therapy among subjects who had been on HAART for 1 year after primary HIV-1 infection (Figs 1 and 2).
It has been reported that treatment of primary HIV-1 infection with HAART augments the numbers of circulating naive and memory CD4 cells and can help preserve their function. IL-2 treatment given concomitantly with HAART further increases these CD4 cell numbers while the viral load remains suppressed. In cell culture studies, IL-2 has been shown to enhance CNAR and in vivo can lead to acute activation of CD8 cells and enhanced expression of costimulatory molecules (e.g., CD25/CD5) detected on CD4 and CD8 cells. Our previous studies indicated that the administration of IL-2 with HAART during the first year of acute infection did not substantially affect CNAR activity associated with antiretroviral therapy. The present studies show dramatic increases in CNAR activity when IL-2 was given after 1 year of HAART. And, among four of five subjects followed up for 6 months after discontinuation of IL-2 therapy, these responses were maintained.
The reason for the beneficial effects of IL-2 after 1 year of HAART but not with initial HAART therapy is unknown but could reflect a maturation of the immune system. A more mature immune system that exists following 1 year of HAART treatment may yield more CD8 cells having CNAR activity or more cells capable of mounting a measurable CNAR effect. With administration of IL-2 therapy, these CD8 cells, already increased in number or adequately recovered from the initial insult induced by HIV infection, might then provide for the enhanced antiviral responses noted in the present studies. Further evaluation with a large number of subjects will be needed to substantiate the long-term beneficial effect of IL-2 if given to acutely infected subjects after 1 year of HAART.
INTRODUCTION
Clinical studies suggest that CD8 cell non-cytotoxic anti-HIV responses (CNAR) play an important role in controlling HIV infection during the acute phase of infection CNAR suppresses HIV replication without killing the infected cells, and this antiviral response is not restricted by class I or class II molecules. CNAR is associated with a healthy clinical state and long-term survival of HIV-infected individuals; it is reduced with progression to disease.
Early initiation of highly active antiretroviral therapy (HAART) is a strategy aimed at protecting key immune responses. However, we and others have previously reported reductions in anti-HIV immune responses in primary infected subjects on HAART treatment suggesting an adverse effect of this treatment on the developing immune system.
The addition of interleukin-2 (IL-2) to HAART in chronically HIV-1 infected patients has been shown to increase CD4 cell numbers and restore or enhance certain HIV-specific immune functions. However, data on the beneficial effects of IL-2 + HAART during the early stages of HIV infection is limited and thus far the results suggest that early treatment of acute/primary HIV infection with this joint therapy leads to only a transient enhancement of HIV-specific immune responses. In this study, we investigated the effect on CD4/CD8 cell numbers, viral loads, and CNAR of subcutaneous IL-2 therapy given 1 year after the acutely HIV-1 infected subjects had been receiving HAART.
Study participants
Subjects were drawn from the UCSF Options study of acute and early HIV-1 infection. Subjects for the university-based study were referred from a variety of sources including physicians, HIV testing sites, and self-referral. We identified persons with acute and early HIV-1 infection if they met at least one of the following criteria: (i) two HIV-1 RNA tests > 3000 copies/ml with a negative HIV-1 or indeterminate antibody test; (ii) a positive HIV-1 antibody test with a history of a negative HIV-1 antibody test within the previous 12 months; or (iii) history compatible with recent HIV infection and a reactive standard HIV antibody test but a non-reactive less sensitive EIA (LS-EIA), providing laboratory evidence of recent infection [27]. Participants in the Options study decided whether or not to start HAART. Those who elected to start HAART were given the option of participating in a randomized study to investigate the optimal timing of receiving IL-2 in addition to HAART once their HIV-1 RNA level was below 500 copies/ml. Those who chose to receive IL-2 were randomized to receive either IL-2 immediately (early) or IL-2 at 48 weeks after starting HAART (delayed). This report covers results with those subjects who were randomized to delayed therapy. IL-2 was given as a subcutaneous injection (7.5 million units, twice daily) for 5 days at 8-week intervals for six cycles. Whole blood samples were collected at regular intervals during the course of the study (weeks 48, 72, 96, 120) following initiation of combined therapy and prior to beginning each IL-2 cycle. In the present study, we compare results on subjects from three groups: 12 patients on HAART who received delayed IL-2 treatment, nine subjects who remained on HAART and elected not to receive IL-2, and nine subjects who chose not to receive any treatment. This study was approved by the UCSF Committee for Human Research and all participants signed an informed consent form prior the study.
RESULTS
Thirty subjects with acute/primary HIV infection were monitored in this study for up to 2 years. Of these, six were pre-antibody seroconversion and the remainder were in the early post-seroconversion period. Twelve patients received a combination of HAART plus IL-2, nine patients received HAART and nine elected not to receive HAART. The study participants included three females and 27 males. Seventy-seven percent were Caucasian, and 23% were from non-white ethnic groups. Men who have sex with men was the major HIV risk group in the study. Twelve subjects (57%) received an initial drug regimen consisting of zidovudine/lamivudine (Combivir) and nelfinavir and nine subjects (43%) received other combination therapies that include at least two reverse transcriptase inhibitors and one protease inhibitor. The choice to use IL-2 was given 48 weeks after initiation of HAART. No significant differences in demographic characteristics were observed among the groups with the exception of age (P = 0.05, Kruskal-Wallis test): On average, the HAART + IL-2 group was younger than the other two groups. However, adjusting for age or other demographic characteristics did not significantly change the results observed.
Subjects in the HAART + IL-2 treated group had somewhat higher pre-HAART levels of HIV-1 RNA (mean of 〜130 000 copies/ml) compared to subjects in the HAART-treated group (mean of 〜56 000 copies/ml) and individuals opting not to receive treatment (mean of 〜35 000 copies/ml) (P = 0.17, Kruskal-Wallis test). By week 48 and prior to IL-2 therapy, all but one of the subjects in both the HAART + IL-2-treated and the HAART-treated groups reached undetectable HIV/RNA levels (< 50 copies/ml). The HIV-RNA in the untreated group averaged 27 680 copies/ml. For 96 weeks, individuals on antiretroviral therapy (HAART + IL-2 or HAART alone) demonstrated substantial reductions in HIV-1 RNA levels (on average) in comparison to untreated subjects (Table 2) (P = 0.04, Kruskal-Wallis test). The addition of IL-2 therapy did not significantly impact on HIV-RNA levels among the HAART-treated subjects (P = 0.13, Kruskal-Wallis test).
CD8 cell non-cytotoxic anti-HIV responses (CNAR)
At the initiation of the study (week 48), there was no difference in the mean percentage of CD8 cell suppression between those who declined HAART, those who began HAART, and those who received HAART for 48 weeks and began concomitant treatment with HAART and IL-2. The mean percentage of CD8 cell suppression in all three clinical groups was about 45% (at a 1 : 1 CD4 : CD8 cell input ratio). After three to six cycles of co-administration of IL-2 (week 72 and week 96), CNAR rose in the concomitantly treated subjects to above 50% (mean 59%). In contrast, subjects receiving HAART alone or untreated subjects showed a decrease in CNAR over time (below 30%; mean 29% and 18%, respectively). These latter observed changes were significantly different than the pattern observed for subjects treated with IL-2 (P = 0.02, random effects linear regression). When the percentage of subjects showing CNAR levels of > 50% was considered, IL-2 therapy added to HAART again increased this to > 70% by the 96 week period. None of the untreated subjects and only 25% of the subjects receiving HAART alone showed > 50% of CNAR by week 96. Furthermore, these observed increases in both the mean level of CNAR and the percentage of subjects showing > 50% suppression of HIV replication continued for 6 months after completion of IL-2 therapy. Of the five subjects available for follow-up for this time period on IL-2 therapy, four had CNAR at > 50% whereas none of the three HAART-treated or the one untreated subject studied had this level of CNAR (data not shown). Overall, the changes in CNAR for subjects treated with IL-2 were significantly different than those observed in the other two groups (P = 0.02, random effects logistic regression).
Overall influence of IL-2 therapy on CD4/CD8 cell numbers, viral load and CNAR
After 48 weeks and prior to receiving IL-2, CD4 cell numbers averaged 613 × 106 cells/l in all subjects receiving HAART. This number dramatically increased after each IL-2 cycle reaching 1546 × 106 cells/l by cycle six. The observed increases associated with IL-2 treatment were statistically significant (P = 0.004, signed-rank test). Observed changes in CD8 cell numbers over this same period were less striking (P = 0.07, signed-rank test), suggesting no effect of IL-2 on this cell population. The viral load in these individuals averaged 57 copies/ml before starting IL-2 therapy (week 48) and remained at very low or undetectable levels (< 50 copies/ml) through all the IL-2 cycles with the exception of one subject whose HIV-RNA went up to 1466 copies/ml after the first IL-2 cycle and had reduced levels to below 500 copies/ml afterwards (data not shown).
As noted above, the number of subjects whose CD8 cells showed at least a 50% suppression of HIV replication increased and remained fairly constant after the administration of three cycles of IL-2. A small decrease close to baseline levels occurred at cycle four but the increase was restored and sustained after receiving the fifth and sixth IL-2 injections. Moreover, as cited above, CNAR activity and the percentage of subjects showing appreciable levels of CNAR remained high (mean of 62% and 80% respectively) in four of five subjects who were further evaluated for 6 additional months after completion of IL-2 therapy. These findings suggest a long-term beneficial effect of IL-2 therapy administered 1 year after primary HIV-1 infection had been treated with HAART and the effects were sustained following discontinuation of IL-2 administration.
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