Safety and Immunological Evaluation of Interleukin-21 Plus Anti-α4β7 mAb Combination Therapy in Rhesus Macaques

Therapeutic effect of (5R)-5-hydroxytriptolide (LLDT-8) in SIV infected rhesus monkeys

BACKGROUNDS

Human immunodeficiency virus (HIV) infections induce robust, generalized inflammatory responses and lead to pathological systemic immune activation. This abnormal immune status persists despite successful antiretroviral therapy (ART). Immune modulating strategies in conjunction with ART were tried to reduce abnormal immune activation. Previously, we demonstrated that Tripterygium Wilfordii Hook F has been shown immunosuppressive activity in HIV patients. (5R)-5-hydroxytriptolide (LLDT-8), a new analog of triptolide, and the most active ingredient of Tripterygium Wilfordii Hook F, has been shown to have lower cytotoxicity. However, the role of LLDT-8 in HIV or simian immunodeficiency virus (SIV) needs to be explored.

METHODS

Six male adult Chinese rhesus monkeys were enrolled in our study. All of them were healthy and negative for SIV, and chronically SIVmac239 infected macaques were treated with LLDT-8 combined with ART (n = 4) or ART only (n = 2) after 14 weeks of infection. ART was determined at week 33, and LLDT-8 was continued until week 48. T cell immune activation and inflammation were compared during the period, and viral rebound time and reservoir were supervised after stopping ART.

RESULTS

The RNA level of the two groups continued to decline after initiating ART, RNA of 4 rhesus monkeys declined to the lower limit of detection at week 20. LLDT-8 administration combined with ART did not affect T cell activation and plasma levels of IL-6 and CRP. The viral load of all the macaques in both groups was rebounded 2 weeks after ART discontinuation. Furthermore, no significant decrease of SIV DNA was observed in the LLDT-8 treatment group.

CONCLUSIONS

LLDT-8 administration during chronic SIV infection had no effect on T cell activation and plasma levels; Furthermore, LLDT-8 may not contribute to suppression of viral rebound and reservoir. These results suggest that LLDT-8 is unlikely to reduce immune activation and viral persistence without additional interventions.

Interests of the Non-Human Primate Models for HIV Cure Research

Non-human primate (NHP) models are important for vaccine development and also contribute to HIV cure research. Although none of the animal models are perfect, NHPs enable the exploration of important questions about tissue viral reservoirs and the development of intervention strategies. In this review, we describe recent advances in the use of these models for HIV cure research and highlight the progress that has been made as well as limitations using these models. The main NHP models used are (i) the macaque, in which simian immunodeficiency virus (SIVmac) infection displays similar replication profiles as to HIV in humans, and (ii) the macaque infected by a recombinant virus (SHIV) consisting of SIVmac expressing the HIV envelope gene serving for studies analyzing the impact of anti-HIV Env broadly neutralizing antibodies. Lessons for HIV cure that can be learned from studying the natural host of SIV are also presented here. An overview of the most promising and less well explored HIV cure strategies tested in NHP models will be given.