Rapid detection of ciguatoxins in Gambierdiscus and Fukuyoa with immunosensing tools

Consumption of seafood contaminated with ciguatoxins (CTXs) leads to a foodborne disease known as ciguatera. Primary producers of CTXs are epibenthic dinoflagellates of the genera Gambierdiscus and Fukuyoa. In this study, thirteen Gambierdiscus and Fukuyoa strains were cultured, harvested at exponential phase, and CTXs were extracted with an implemented rapid protocol. Microalgal extracts were obtained from pellets with a low cell abundance (20,000 cell/mL) and were then analyzed with magnetic bead (MB)-based immunosensing tools (colorimetric immunoassay and electrochemical immunosensor). It is the first time that these approaches are used to screen Gambierdiscus and Fukuyoa strains, providing not only a global indication of the presence of CTXs, but also the ability to discriminate between two series of congeners (CTX1B and CTX3C). Analysis of the microalgal extracts revealed the presence of CTXs in 11 out of 13 strains and provided new information about Gambierdiscus and Fukuyoa toxin profiles. The use of immunosensing tools in the analysis of microalgal extracts facilitates the elucidation of further knowledge regarding these dinoflagellate genera and can contribute to improved ciguatera risk assessment and management.

Abstract B29: Innate immune modulation: The novel immunotherapeutic Imprime PGG triggers the anti-cancer immunity cycle in concert with tumor-targeting, anti-angiogenic and checkpoint inhibitor antibodies

Cancer immunotherapeutics largely focus on awakening T cell mediated recognition and eradication of tumor cells. Indeed, checkpoint inhibitor antibodies (e.g. pembrolizumab) unleash T cells already involved in anti-cancer responses and have shown remarkable clinical activity, though only in ~20-30% of solid tumor patients. Numerous approaches are being explored to enhance the percent of patients who benefit from checkpoint inhibitor therapies. Chief amongst these are the innate immune modulating therapies collectively designated as PAMPs- pathogen- associated molecular patterns. PAMPs operate as the critical non-self signals that, in response to pathogen infection, ignite the function of the innate immune system to trigger the immunity cycle. TLR and STING agonists acts as PAMPs and reflect bacterial and viral danger signals that can drive dendritic cell maturation, enhancing T cell function. These agents are in development in combination with other immunotherapies, including checkpoint inhibitors, but inspire intolerable cytokine storms and are thereby limited to direct intra-tumoral delivery approaches. We therefore sought to discover and develop a novel, systemically administered PAMP- Imprime PGG (Imprime). Ex vivo studies with whole blood from healthy human donors show that Imprime consistently elicits the activation of innate immune cells. M2 state macrophages repolarize, showing increased expression of M1 markers (CD86, PD-L1) with coincident reduction in M2 markers (CD163, CD206). Dendritic cells (DCs) mature, showing enhanced surface expression of CD80, CD86 and MHC class II. Functionally, the antigen presentation capability of these re-polarized macrophages and activated DCs is substantially enhanced and drives the robust expansion of co-cultured CD8 T cells as well as the marked upregulation of the potent anti-tumor cytokine interferon gamma. In preclinical tumor studies, Imprime is administered IV and profoundly enhances the efficacy of numerous antibody therapies. Using the B16 experimental metastasis model, we show that Imprime (administered IV) synergizes with the anti-TRP1 tumor-targeting antibody TA-99, nearly eradicating B16 metastases as measured by visual counts, TRP-1 RT-PCR and in situ immunofluorescence for TRP1. In the H441 and H1299 non-small cell lung cancer xenografts, Imprime synergizes with the anti-VEGFR2 antibody DC101 to flat-line tumor growth. In the MC-38, CT-26 and 4T-1 syngeneic tumor models, Imprime synergizes with both anti-PD-1 and PD-L1 checkpoint inhibitor antibodies to repress tumor growth and/or to eradicate cancer lesions. In situ imaging of these preclinical tumor tissues repeatedly shows that Imprime instigates a re-orientation of the immune microenvironment, promoting an M1 state (e.g. increased iNOS2, decreased Arginase 1), as well as the influx of myeloid cells and, in the syngenic models, CD8 T cells. In clinical trials in > 400 total patients to date, Imprime has been safely administered by IV infusion (4mg/kg over 2 hours) and has repeatedly shown evidence for efficacy in combination with tumor targeting or anti-angiogenic antibodies. Studies with checkpoint inhibitor antibodies are slated to begin summer of 2016. We now provide the first evidence in healthy human volunteers that Imprime (IV- 4mg/kg, 2 hours) drives the same innate immune activation events evident in the preclinical studies (e.g. chemokine and cytokine release, PD-L1 and CD86 upregulation) verifying that the clinical dose activates the innate immune system. Together, these preclinical and clinical studies provide evidence that the novel PAMP, Imprime PGG, can be safely administered systemically and can drive the critical innate immune activation necessary to spark the anti-cancer immunity cycle.

Citation Format: N Bose, K Gorden, A Chan, A Jonas Bykowski, N Ottoson, D Walsh, X Qiu, B Harrison, T Kangas, K Fraser, R Fulton, S Leonardo, M Uhlik, J Graff. Innate immune modulation: The novel immunotherapeutic Imprime PGG triggers the anti-cancer immunity cycle in concert with tumor-targeting, anti-angiogenic and checkpoint inhibitor antibodies. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B29.

Relationship between Changes in Thymic Emigrants and Cell-Associated HIV-1 Dna in HIV-1-Infected Children Initiating Antiretroviral Therapy

Objectives and methods

To investigate the relationship between cell-associated HIV-1 dynamics and recent thymic T-cell emigrants, HIV-1 DNA and T-cell receptor rearrangement excision circles (TREC, a marker of recent thymic emigrants) were measured in peripheral blood mononuclear cells in 181 samples from 33 HIV-1-infected children followed for 96 weeks after antiretroviral therapy (ART) initiation.

Results

At baseline, HIV-1 DNA was higher in children with higher TREC ( P=0.02) and was not related to age, CD4 or HIV-1 RNA in multivariate analyses ( P>0.3). Overall, TREC increased and HIV-1 DNA decreased significantly after ART initiation, with faster HIV-1 DNA declines in children with higher baseline TREC ( P=0.009). The greatest decreases in HIV-1 DNA occurred in children with the smallest increases in TREC levels during ART ( P=0.002). However, this inverse relationship between changes in HIV-1 DNA and TREC tended to vary according to the phase of HIV-1 RNA decline ( P=0.13); for the same increase in TREC, HIV-1 DNA decline was much smaller during persistent or transient viraemia compared with stable HIV-1 RNA suppression.

Conclusions

Overall, these findings indicate that TREC levels predict HIV-1 DNA response to ART and suggest that immune repopulation by thymic emigrants adversely affects HIV-1 DNA decline in the absence of persistent viral suppression, possibly by providing a cellular source for viral infection and replication.