Posted in HIV, Resource

Molecular Signatures of a TLR4 Agonist-Adjuvanted HIV-1 Vaccine Candidate in Humans

Molecular signatures associated with early (A) and late (B) humoral responses. Source from Anderson et al., 2018, Frontiers in Immunology

Immunisation with the stable trimeric recombinant HIV-1 envelope glycoprotein, CN54gp140, has been shown to induce potent humoral immune responses, especially when adjuvanted with TLR4 agonist adjuvants, such as monophosphoryl lipid A or GLA-AF (glucopyranosol lipid adjuvant-aqueous formulation). These adjuvants exert their adjuvanticity, at least in part, by activating the myeloid differentiation factor 88 (MyD88) and toll-interleukin 1 receptor domain-containing adapter inducing interferon-β (TRIF) pathways. However, the clinical efficacy to the CN54gp140 adjuvanted with GLA-AF is variable between individuals. Anderson et al characterised the host responses after vaccinating subjects with CN54gp140 adjuvanted with GLA-AF, and examined the gene signatures linked to vaccine immunogenicity. 

Healthy male (n = 8) or female (n = 6) volunteers aged between 18 and 45 and with no history of HIV-1 and HIV-2 infection received the vaccine, and whole blood was collected from these subjects at 6 hours, 1, 3 and 7 days after vaccination. 

Majority of total DEGs were observed within 24 h post vaccination compared to later time points at 3 days and 7 days post-immunisation. 

The DEGs reveal an enrichment of BTMs related to cell cycle regulation and signaling as well as those related to innate and adaptive immune responses.

NK cell-related enriched BTMs (M7.2, M61.0, and S1) were significantly repressed in the gene expression profiles from individuals with either late high serum IgA or IgG4 responders (See Figure on top). 

In particular, we identified a repression in BTM modules related to NK cells, especially at 3 and 7 days post-vaccination, for high serum IgM, IgA, and IgG4 antibody responders.

Flow cytometry was performed to determine that the changes were due to NK cell numbers or expression levels of proteins upon vaccination.

In the limited number of analyzed samples, frequency of CD3–CD56dim NK cell population in the blood of high antibody responder subjects was increased on 14 days post vaccination compared to the 0 h baseline. While more studies need to be done, the authors speculate that the repression of BTMs related to NK cells observed in the first 7 days post-vaccination reflects NK cells leaving the circulation early in the response. Given that NK cells are short lived, the enhanced frequency of NK cells for 14  days post vaccination is presumably attributed to secondary induction of NK cell differentiation processes in response to vaccination.

Posted in Adenovirus, Resource

Merck Ad5/HIV induces broad innate immune activation that predicts CD8+ T-cell responses but is attenuated by preexisting Ad5 immunity

Figure (top) showing the protein–protein interaction network that links between CD8+ T-cell response-associated genes and constituents of functional gene modules differentially regulated by MRKAd5/HIV. Study is done by Zak DE et al., PNAS, 2012.

The Step Study revealed that the MRKAd5/HIV had poor efficacy in protecting against HIV-1 infection, especially in subjects with pre-existing Ad5 immunity. However, no clear mechanisms have been identified to date why the seropositive subjects showed reduced efficacy. In this manuscript, Zak DE et al., describe the possible mechanisms of vaccine failure using a systems biology approach

35 healthy HIV-1-uninfected adults, 20–50 years old were recruited for the study. 10 subjects (3 seropositive and 7 seronegative subjects) PBMCs were isolated and transcript levels were analysed by microarray at 4–6, 24, 72, and 168 h post-vaccination.

Strong induction of innate immune responses were detected at the gene and protein level, peaking at 24 hours post-vaccination and resolving at 72 hours post-vaccination. In addition, protein levels of CXCL-10, ITAC, monocyte chemoattractant protein-1 (MCP-1), and MCP-2, as well as immunoregulatory IL-10 and IL-1Ra, were upregulated.

92% concordance between the in vivo and in vitro induction of IFN response genes was observed, indicating that these immune responses observed were modulated by viral infection. Genes not captured in vitro are related to cell lineages, possibly due to lack of cell trafficking in vitro.

When comparing subjects with Ad5 nAb titers ≤ 200 and >200, significant attenuation of the innate immune responses were seen in seropositive subjects compared to the seronegative subjects.

Two chemokines, MCP-1 and MCP-2, discriminated between the strong and moderate CD8-responders as compared to those subjects with poor or no CD8 responses.

Interestingly, the gene signatures that correlated with CD8 T-cell responses were seen at day 3, where members of the “Cytotoxicity,” “T cells,” and “Lymphoid lineage” modules were positively correlated (see above figure). This finding may support the notion that prolonged upregulation of the innate immune gene transcripts could influence CD8 responses.

Data is deposited in the Gene Expression Omnibus (GEO) database, GSE22822.