Some reflections on immunosuppressants and their delivery to the lungs by aerosol in the treatment of COVID-19

Abstract

Disorders of immune homeostasis represent the key pathogenetic link of COVID-19, which often manifests as a hyperimmune response to the pathogen, leading to severe uncontrolled inflammation in lungs, followed by complications and death. Accordingly, a certain therapeutic potential is provided by different pharmacological drugs with distinct mechanisms of action, This class of drugs should, however, act in common direction by suppressing the immune response, thus being often classified as immunosuppressants (IS). Of them, the most promising are immunobiological preparations, which include monoclonal antibodies, as well as purinergic regulatory agents. There are several attempts to use the “classical” IS by a certain way, e.g., cytostatics and calcineurin inhibitors which found clinical application in transplantology and oncology. However, their usage for treatment of uncontrolled inflammation of respiratory tract was abandoned by the end of XX century. Meanwhile, the aerosol route of drug administration optimizes treatment, both in terms of their effectiveness, and the reduction of side effects thus promoting usage of IS for treatment of uncontrolled airway inflammation. Previously, the analysis of therapeutic opportunities for some IS delivered as aerosols to the lungs in COVID-19 therapy was not carried out, thus bein the purpose of our work. Methodological analysis was carried out using various databases of biomedical scientific information, including Index Medicus, PubMed, Embase, Cohrane Clinical Trials gov registry and patent databases.The efficiency of the impact of various IS subgroups in COVID-19, including their administration by inhalations into the respiratory ways, was assessed. The role of regulatory T cells considered the central regulator of immune response, in pathogenesis of COVID-19 was considered, and their therapeutic potential was characterized, dependent on phase and severity of the disease as well as drug dose dependence. Methods and approaches to the use of IP, advantages and disadvantages are discussed. The expediency and future prospects of their application are considered.One may conclude that the effectiveness of cytostatics and calcineurin inhibitors in the treatment of airway inflammation in COVID-19 remains unconfirmed and seems to be unpromising. Meanwhile, biological preparations, including monoclonal antibodies and purinergic regulatory agents, offer great promise in this respect.