Single cell RNA sequencing used in asthma research

Asthma is an allergic disease characterized by chronic inflammation of the airways, leading to bronchoconstriction and excessive mucus production with symptoms of dyspnea, wheezing, and cough. It involves various underlying mechanisms such as eosinophilic, neutrophilic, mixed, and pauci-cellular, exercise-induced, occupational, and obesity-related asthma. Asthma is a mostly reversible condition involving several cells and cytokines, leading to chronic airway inflammatory responses, and showing the diversity in asthma phenotypes and complexity. Recent advancements using single-cell RNA sequencing allow distinguishing and analyzing RNA sequences at each cellular level within complex and heterogeneous cell groups. This method has also been applied to study asthma mechanisms, enabling us to predict intercellular interactions triggering asthma and identifying cellular changes characterized by specific molecular-cellular phenotypes. In our study, according to the PRISMA (preferred reporting items from systematic review and meta-analysis) guidelines, we systematically reviewed trends in asthma-related immune and structural cell research using single cell RNA sequencing, highlighting potential therapeutic interventions, and pinpointing opportunities for novel biomarker discovery.

Desensitization for the prevention of drug hypersensitivity

Drug desensitization is a treatment strategy for patients with hypersensitivity to essential drugs without alternatives. The gradual increase in the drug dosage from low doses to therapeutic levels induces a transient immune tolerance to the culprit drug. Although desensitization has traditionally been recommended for IgE-mediated immediate hypersensitivity, this indication has recently been expanded to include non-IgE-mediated immediate responses, nonimmunological responses, and T-cell-mediated delayed hypersensitivity reactions. Although the exact mechanism behind desensitization remains unclear, the process is thought to attenuate various intracellular signals in target cells through Fcɛ receptor 1 internalization, alteration in signaling pathways in mast cells and basophils, reduction in Ca 2+ influx, and production of anti-drug IgG4 blocking antibody. Desensitization can be used for the safe administration of anti-neoplastic agents, antibiotics, aspirin, and nonsteroidal anti-inflammatory drugs. Various desensitization protocols have been proposed for each drug. The optimization of drug concentration, target dosage, administration interval, and route of administration is key to successful desensitization. In addition, the desensitization protocol should be individualized for each patient with consideration of the severity of the initial hypersensitivity response, the characteristics of the culprit drug, and the nature of the breakthrough reactions.

Management of hypersensitivity reactions to contrast media

As imaging technologies have become essential for diagnosing various diseases, the use of contrast agents is rapidly expanding. As a result, hypersensitivity reactions (HSRs) to contrast agents have also increased. However, protocols for managing, diagnosing, and preventing these reactions are not fully established yet. Since the guidelines for contrast agent hypersensitivity suggested by domestic and international academic societies are not standardized and sometimes difficult to follow in medical facilities, there is a need for practical recommendations in a real-world setting. This review introduces the strategy to manage, diagnose, and prevent HSRs to contrast agents, which have been successfully implemented at Seoul National University Hospital for a decade. First, every single HSRs should be documented in the medical records because a previous history of hypersensitivity to contrast agents is the most significant risk factor for developing HSR to iodinated contrast media. Secondly, avoidance of culprit agents is the main strategy for preventing recurrences of HSRs to contrast agents. Thirdly, it is important to identify nonsensitized contrast agents using skin tests for future exposure to contrast media. In addition to skin testing, side chains of iodinated contrast media may provide a clue to reactive contrast agents. Fourthly, provocation tests can be performed in selected cases with a nonreactive agent based on the skin testing and side chain commonness. Prior to performing imaging studies, premedication can be applied stratified to the severity of the index HSR. All of these procedures are safe and prove to be executable in the medical facilities.