Folate-conjugated organic CO prodrugs: Synthesis and CO release kinetic studies.

Carbon monoxide (CO) is an endogenous produced molecule and has shown efficacy in animal models of inflammation, organ injury, colitis and cancer metastasis. Because of its gaseous nature, there is a need for developing efficient CO delivery approaches, especially those capable of targeted delivery. In this study, we aim to take advantage of a previously reported approach of enrichment-triggered prodrug activation to achieve targeted delivery by targeting the folate receptor. The general idea is to exploit folate receptor-mediated enrichment as a way to accelerate a biomolecular Diels-Alder reaction for prodrug activation. In doing so, we first need to find ways to tune the reaction kinetics in order to ensure minimal rection without enrichment and optimal activation upon enrichment. In this feasibility study, we synthesized two diene-dienophile pairs and studied their reaction kinetics and ability to target the folate receptor. We found that folate conjugation significantly affects the reaction kinetics of the original diene-dienophile pairs. Such information will be very useful in future designs of similar targeted approaches of CO delivery.

Self-reactive germline-like TCR alpha chains shared between blood and pancreas.

Human islet antigen reactive CD4 + memory T cells (IAR T cells) from peripheral blood have been studied extensively for their role in the pathogenesis of autoimmune type 1 diabetes (T1D). However, IAR T cells are rare, and it remains poorly understood how they affect T1D progression in the pancreas. Using single cell RNA-sequencing coupled with a multiplexed activation induced marker (AIM) enrichment assay, we identified paired TCR alpha/beta (TRA/TRB) T cell receptors (TCRs) in IAR T cells from the blood of healthy, at-risk, new onset, and established T1D donors. Using TCR sequences as barcodes, we measured infiltration of IAR T cells from blood into pancreas of organ donors with and without T1D. We detected extensive TCR sharing between IAR T cells from peripheral blood and pancreatic infiltrating T cells (PIT), with perfectly matched or single mismatched TRA junctions and J gene regions, comprising ~ 34% of unique IAR TCRs. PIT-matching IAR T cells had public TRA chains that showed increased use of germline-encoded residues in epitope engagement and a propensity for cross-reactivity. The link with T cells in the pancreas implicates autoreactive IAR T cells with shared TRA junctions and increased levels in blood with the prediabetic and new onset phases of T1D progression.

Click chemistry and drug delivery: A bird's-eye view.

Click chemistry has been proven to be very useful in drug delivery. Due to the availability of a large number of click reactions with a various characteristics, selection of appropriate chemistry for a given application is often not a trivial task. This review is written for pharmaceutical researchers who are interested in click chemistry applications and yet may not be click chemistry experts. For this, the review gives an overview of available click reactions organized by application types. Further, the general understanding of click reactions being fast and high yielding sometimes overshadows the need to analyze reaction kinetics in assessing suitability of a given reaction for certain applications. For this, we highlight the need to analyze the relationship among reaction kinetics, concentration effects, and reaction time scales, knowing that lack of such analysis could easily lead to failures. Further, possible issues such as chemical stability with various click reagents are also discussed to aid experimental designs. Recent examples and extensive references are also provided to aid in-depth understanding of technical details. We hope this review will help those interested in using click chemistry in drug delivery to select the appropriate reactions/reagents and minimize the number of pitfalls.