Add-on Pyridostigmine Enhances CD4+ T-Cell Recovery in HIV-1-Infected Immunological Non-Responders: A Proof-of-Concept Study

Abstract

Background: In human immunodeficiency virus (HIV)-infection, persistent T-cell activation leads to rapid turnover and increased cell death, leading to immune exhaustion and increased susceptibility to opportunistic infections. Stimulation of the vagus nerve increases acetylcholine (ACh) release and modulates inflammation in chronic inflammatory conditions, a neural mechanism known as the cholinergic anti-inflammatory pathway (CAP). Pyridostigmine (PDG), an ACh-esterase inhibitor, increases the half-life of endogenous ACh, therefore mimicking the CAP. We have previously observed that PDG reduces ex vivo activation and proliferation of T-cells obtained from people living with HIV.

Methods: We conducted a 16-week proof-of-concept open trial using PDG as add-on therapy in seven HIV-infected patients with discordant immune response receiving combined antiretroviral therapy, to determine whether PDG would promote an increase in total CD4+ T-cells. The trial was approved by the Institutional Research and Ethics Board and registered in ClinicalTrials.gov (NCT00518154).

Results: Seven patients were enrolled after signing informed consent forms. We observed that addition of PDG induced a significant increase in total CD4+ T-cells (baseline = 153.1 ± 43.1 vs. week-12 = 211.9 ± 61.1 cells/µL; p = 0.02). Post hoc analysis showed that in response to PDG, four patients (57%) significantly increased CD4+ T-cell counts (responders = 257.8 ± 26.6 vs. non-responders = 150.6 ± 18.0 cells/µL; p = 0.002), and the effect persisted for at least 1 year after discontinuation of PDG.

Conclusion: Our data indicate that in patients with HIV, add-on PDG results in a significant and persistent increase in circulating CD4+ T-cells.

Keywords: CD4+ T-cell; HIV; cholinergic anti-inflammatory pathway; immune reconstitution; pyridostigmine.

Figures

Figure 1

CONSORT flowchart of patient enrollment, follow-up, and analysis.

Figure 2

CD4+ cell increase before, during, and after pyridostigmine (PDG). Total CD4+ cell counts were determined by flow cytometry as CD3+, CD4+, and CD8neg cells. (A) The solid line shows the dynamic increase of total CD4+ T-cells [median (p25–p75)] during PDG administration; for comparison, the broken lines depict predicted increase in circulating CD4+ cells of 35 cells/mL/year (4). (B) A subgroup of patients showed a significant, rapid, and persistent elevation in CD4+ cells, and this increase persisted after washout, and 1-year after PDG (each symbol represents and individual value). (C) Total T-cells were determined by flow cytometry as CD3+ cells (mean ± SD). (D) The ratio of CD4+ and CD8+ cells was determined by gating from total (CD3+) T-cells (each symbol represents and individual value). n = 7 for panel (A); n = 3–4 subjects/group for panels (B–D). *p ≤ 0.05; **p ≤ 0.01 vs. baseline.