A human tissue-based functional assay platform to evaluate the immune function impact of small molecule inhibitors that target the immune system

[Functional immunoassays in the setting of infectious risk and immunosuppressive therapy of non-HIV immunocompromised patients]

The holistic approach of the human immune system is based on the study of its components collectively driving a functional response to an immunogenic stimulus. To appreciate a specific immune dysfunction, a condition is mimicked ex vivo and the immune response induced is assessed. The application field of such assays are broad and expanding, from the diagnosis of primary and secondary immunodeficiencies, immunotherapy for cancer to the management of patients at-risk for infections and vaccination. These assays are immune monitoring tools that may contribute to a personalised and precision medicine. The purpose of this review is to describe immune functional assays available in the setting of non-HIV acquired immune deficiency. First, we will address the use of theses assays in the diagnosis of opportunistic infections such as viral reactivation. Secondly, we will report the usefulness of these assays to assess vaccine efficacy and to manage immunosuppressive therapies.

An ex vivo multiparametric flow cytometry assay using human whole blood to simultaneously measure cytotoxicity and leishmanicidal activities

Therapeutic options for the treatment of leishmaniasis are insufficient and need improvements owing to their low efficiency and high toxicity as well as the emergence of resistant strains. The limited number of new drugs for neglected diseases and lack of innovation in your development are still challenges. In this context, the process of discovery and development of biological assays play a pivotal role for the identification of bioactive compounds. The assays currently used for screening of drugs with cytotoxic activity against Leishmania parasites, include different processes that utilize intact parasite (free or intracellular) or specific enzymes of metabolism as a target cell. These assays allow the screening of large numbers of samples followed by more detailed secondary confirmatory assays to confirm the observed activity and assess their toxicity. In the present study, we described the development of a new functional and more complete assay that enables simultaneous assessment of potential anti-Leishmania compounds through evaluation of internalization of fluorescein-labeled L. braziliensis promastigotes by human peripheral blood monocytes and their cytotoxicity by flow cytometry. We standardized the conditions for parasite labeling to achieve better phagocytosis analysis by setting the ratio of number of parasites per cell as 1 to 2, at incubation time of 6h. The cytotoxicity assessment was performed by the quantification of cells undergoing early/late apoptosis and necrosis using a double labelling platform employing 7AAD for late apoptosis and necrosis analysis and Annexin-V for early apoptosis evaluation. Hemolysis analysis was an additional parameter to test cytotoxicity. Two drugs used on clinic (Amphotericin B and Glucantime®) were used to validate the proposed methodology, and the assay was able to detect their known leishmanicidal activity and immunotoxicity properties. This new predictive assay will contribute to the development of translational medicine strategies in drug discovery for neglected diseases such as leishmaniasis.

Target Identification Using Chemical Probes

Chemical probes are small molecules with potency and selectivity for a single or small number of protein targets. A good chemical probe engages its target intracellularly and is accompanied by a chemically similar, but inactive molecule to be used as a negative control in cellular phenotypic screening. The utility of these chemical probes is ultimately governed by how well they are developed and characterized. Chemical probes either as single entities, or in chemical probes sets are being increasingly used to interrogate the biological relevance of a target in a disease model. This chapter lays out the core properties of chemical probes, summarizes the seminal and emerging techniques used to demonstrate robust intracellular target engagement. Translation of target engagement assays to disease-relevant phenotypic assays using primary patient-derived cells and tissues is also reviewed. Two examples of epigenetic chemical probe discovery and utility are presented whereby target engagement pointed to novel disease associations elucidated from poorly understood protein targets. Finally, a number of examples are discussed whereby chemical probe sets, or "chemogenomic libraries" are used to illuminate new target-disease links which may represent future directions for chemical probe utility.