Discovery and implementation of transcriptional biomarkers of synthetic LXR agonists in peripheral blood cells

<p>Abstract</p> <p>Background</p> <p>LXRs (Liver X Receptor α and β) are nuclear receptors that act as ligand-activated transcription factors. LXR activation causes upregulation of genes involved in reverse cholesterol transport (RCT), including ABCA1 and ABCG1 transporters, in macrophage and intestine. Anti-atherosclerotic effects of synthetic LXR agonists in murine models suggest clinical utility for such compounds.</p> <p>Objective</p> <p>Blood markers of LXR agonist exposure/activity were sought to support clinical development of novel synthetic LXR modulators.</p> <p>Methods</p> <p>Transcript levels of LXR target genes ABCA1 and ABCG1 were measured using quantitative reverse transcriptase/polymerase chain reaction assays (qRT-PCR) in peripheral blood from mice and rats (following a single oral dose) and monkeys (following 7 daily oral doses) of synthetic LXR agonists. LXRα, LXRβ, ABCA1, and ABCG1 mRNA were measured by qRT-PCR in human peripheral blood mononuclear cells (PBMC), monocytes, T- and B-cells treated <it>ex vivo </it>with WAY-252623 (LXR-623), and protein levels in human PBMC were measured by Western blotting. ABCA1/G1 transcript levels in whole-blood RNA were measured using analytically validated assays in human subjects participating in a Phase 1 SAD (Single Ascending Dose) clinical study of LXR-623.</p> <p>Results</p> <p>A single oral dose of LXR agonists induced ABCA1 and ABCG1 transcription in rodent peripheral blood in a dose- and time-dependent manner. Induction of gene expression in rat peripheral blood correlated with spleen expression, suggesting LXR gene regulation in blood has the potential to function as a marker of tissue gene regulation. Transcriptional response to LXR agonist was confirmed in primates, where peripheral blood ABCA1 and ABCG1 levels increased in a dose-dependent manner following oral treatment with LXR-623. Human PBMC, monocytes, T- and B cells all expressed both LXRα and LXRβ, and all cell types significantly increased ABCA1 and ABCG1 expression upon <it>ex vivo </it>LXR-623 treatment. Peripheral blood from a representative human subject receiving a single oral dose of LXR-623 showed significant time-dependent increases in ABCA1 and ABCG1 transcription.</p> <p>Conclusion</p> <p>Peripheral blood cells express LXRα and LXRβ, and respond to LXR agonist treatment by time- and dose-dependently inducing LXR target genes. Transcript levels of LXR target genes in peripheral blood are relevant and useful biological indicators for clinical development of synthetic LXR modulators.</p

A Calcium‐Activated Chloride Channel Blocker Inhibits Goblet Cell Metaplasia and Mucus Overproduction

We have previously shown that expression of a Ca 2+ ‐activated Cl − channel (mCLCA3 in mice and hCLCA1 in humans) is up‐regulated along with goblet cell metaplasia and mucus overproduction in the lungs of interleukin 9 (IL9) transgenic mice, and in human primary lung cultures by IL4, IL13 and IL9. We show here that hCLCA1 expression in NCI‐H292 cells specifically induces soluble gel‐forming mucin production. Moreover, niflumic acid (NFA), a blocker of hCLCA1‐dependent Cl − efflux, inhibits MUC5A/C production in these cells. NFA treatment during natural antigen‐exposure, where mCLCA3 is greatly up‐regulated in the lung, significantly reduces airway inflammation, goblet cell metaplasia and mucus overproduction in vivo. These data suggest that this Ca 2+ ‐activated Cl − channel plays an important role in epithelial‐regulated inflammatory responses, including goblet cell metaplasia, and represents a potential novel therapeutic target for the control of mucus overproduction in chronic pulmonary disorders

The value of open-source clinical science in pandemic response: lessons from ISARIC

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