Search

Understanding the host immune response during cryptococcal meningitis (CM) is of critical importance for the development of immunomodulatory therapies. We profiled the cerebrospinal fluid (CSF) immune-response in ninety patients with HIV-associated CM, and examined associations between immune phenotype and clinical outcome. CSF cytokine, chemokine, and macrophage activation marker concentrations were assayed at disease presentation, and associations between these parameters and microbiological and clinical outcomes were examined using principal component analysis (PCA). PCA demonstrated a co-correlated CSF cytokine and chemokine response consisting primarily of Th1, Th2, and Th17-type cytokines. The presence of this CSF cytokine response was associated with evidence of increased macrophage activation, more rapid clearance of Cryptococci from CSF, and survival at 2 weeks. The key components of this protective immune-response were interleukin (IL)-6 and interferon-γ, IL-4, IL-10 and IL-17 levels also made a modest positive contribution to the PC1 score. A second component of co-correlated chemokines was identified by PCA, consisting primarily of monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α). High CSF chemokine concentrations were associated with low peripheral CD4 cell counts and CSF lymphocyte counts and were predictive of immune reconstitution inflammatory syndrome (IRIS). In conclusion CSF cytokine and chemokine profiles predict risk of early mortality and IRIS in HIV-associated CM. We speculate that the presence of even minimal Cryptococcus-specific Th1-type CD4+ T-cell responses lead to increased recruitment of circulating lymphocytes and monocytes into the central nervous system (CNS), more effective activation of CNS macrophages and microglial cells, and faster organism clearance; while high CNS chemokine levels may predispose to over recruitment or inappropriate recruitment of immune cells to the CNS and IRIS following peripheral immune reconstitution with ART. These results provide a rational basis for future studies of immune modulation in CM, and demonstrate the potential of baseline immune profiling to identify CM patients most at risk of mortality and subsequent IRIS.

One potential strategy for the prevention of HIV infection is to induce virus specific mucosal antibody that can act as an immune barrier to prevent transmission. The mucosal application of chemokines after immunisation, termed "prime-pull", has been shown to recruit T cells to mucosal sites. We wished to determine whether this strategy could be used to increase B cells and antibody in the vaginal mucosa following immunisation with an HIV antigen. BALB/c mice were immunised intranasally with trimeric gp140 prior to vaginal application of the chemokine CCL28 or the synthetic TLR4 ligand MPLA, without antigen six days later. There was no increase in vaginal IgA, IgG or B cells following the application of CCL28, however vaginal application of MPLA led to a significant boost in antigen specific vaginal IgA. Follow up studies to investigate the effect of the timing of the "pull" stimulation demonstrated that when given 14 days after the initial immunisation MPLA significantly increased systemic antibody responses. We speculate that this may be due to residual inflammation prior to re-immunisation. Overall we conclude that in contrast to the previously observed effect on T cells, the use of "prime-pull" has only a modest effect on B cells and antibody.

CD8+ T cell responses and particularly cytotoxic T lymphocyte (CTL) activity are critical factors in controlling SHIV, SIV or HIV replication during natural infection and represent key parameters which need to be monitored during vaccine development. In order to improve the methodology for measuring CD8+ T cell responses, retroviral vectors expressing the full-length SIV-Gag or HIV-Env proteins were constructed and used to transduce B lymphoblastoid cell lines (BLCL) from cynomolgus monkeys infected with SHIV89.6P. Continuous expression of Gag and Env proteins was detected in stably transduced BLCL, which induced Gag- or Env-specific T cell responses, as measured by both IFNγ-ELISPOT and chromium release assays, upon in vitro stimulation of PBMC from the SHIV89.6P-infected monkeys. Moreover, induction of Gag-specific CTL using BLCL transduced with retroviral vector expressing the SIV-Gag protein was more efficient and specific compared to that obtained using BLCL infected with a recombinant vaccinia virus (rVV) encoding for the same antigen. Assays on purified CD4+ and CD8+ T cells indicated that both populations specifically produced IFNγ, but only the CD8+ T cells mediated Gag- and Env-specific cytotoxicity, indicating preferential expansion of these effector cells. Thus, this method represents an alternative tool for the analysis of CTL responses during vaccination protocols in those animal models where little information is available on MHC class I alleles or CTL epitopes. [Copyright &y& Elsevier]

Abstract: Several studies have shown the importance of evaluating Recent Thymic Emigrants (RTEs) by quantification of T cell receptor-rearrangement excision circles (TRECs), as a measure of de novo T cell generation during human immunodeficiency virus-1 (HIV-1) infection. To determine whether acute viral infection may have an impact on TRECs, cynomolgus monkeys (Macaca fascicularis) were infected intrarectally with simian human immunodeficiency virus (SHIV) 89.6Pcy11 and the number of signal-joint (sj) TRECs was determined in purified CD4+ and CD8+ populations for up to 28 weeks post-infection. Four weeks after infection, TRECs levels significantly decreased in both CD3+CD4+ and in CD3+CD8+ T lymphocytes of infected monkeys, whereas they remained unchanged in uninfected animals. This reduction was followed by a progressive TRECs number recovery in CD3+CD4+ T lymphocytes that positively correlated with changes in the levels of circulating CD3+CD4+ T cells. In the CD3+CD8+ T cell subset, TRECs number remained significantly low and inversely correlated with the increase in the percentages of CD3+CD8+ T cells. These data suggest that SHIV89.6Pcy11 intrarectal infection of cynomolgus monkeys differently affects TRECs content in CD3+CD4+ and CD3+CD8+ T cell subsets. [Copyright &y& Elsevier]