Dihydropyrrolo[2,3‑<i>d</i>]pyrimidines: Selective Toll-Like Receptor 9 Antagonists from Scaffold Morphing Efforts

Toll-like receptors (TLRs) play important roles in the innate immune system. In fact, recognition of endogenous immune complexes containing self-nucleic acids as pathogen- or damage-associated molecular patterns contributes to certain autoimmune diseases, and inhibition of these recognition signals is expected to have therapeutic value. We identified dihydropyrrolo­[2,3-<i>d</i>]­pyrimidines as novel selective TLR9 antagonists with high aqueous solubility. A structure–activity relationship study of a known TLR9 antagonist led to the promising compound <b>18</b>, which showed potent TLR9 antagonistic activity, sufficient aqueous solubility for parenteral formulation, and druggable properties. Compound <b>18</b> suppressed the production of the proinflammatory cytokine IL-6 in CpG-induced mouse model. It is therefore believed that compound <b>18</b> has great potential in the treatment of TLR9-mediated systemic uncontrollable inflammatory response like sepsis

Discovery of a Highly Specific Anti-methotrexate (MTX) DNA Aptamer for Antibody-Independent MTX Detection

High-dose methotrexate (MTX) therapy is used to treat a wide variety of cancers such as leukemia and lymphoma, while the resulting high blood concentration of MTX faces a risk of life-threatening side effects, so it is essential to monitor the concentration carefully. Currently, the MTX concentration is measured using antibody-based kits in a clinical setting; however, the heterogeneity and batch-to-batch variation of antibodies potentially compromise the detection limit. Here, we developed MTX detection systems with chemically synthesizable homogeneous oligonucleotides. Microbead-assisted capillary electrophoresis (MACE)-SELEX against MTX successfully identified MSmt7 with a similar level of specificity to anti-MTX antibodies within three rounds. The 3′-end of MSmt7 was coupled to a peroxidase-like hemin-DNAzyme to construct a bifunctional oligonucleotide for MTX sensing, where MTX in 50% human serum was detected with a limit of detection (LoD) of 118 nM. Furthermore, amplifying the DNAzyme region with rolling circle amplification significantly improved the sensitivity with an LoD of 290 pM. Presented oligonucleotide-based MTX detection systems will pave the way for antibody-independent MTX detection with reliability and less cost in the laboratory and the clinic