The Potential of Thyroid Hormone Therapy in Severe COVID-19: Rationale and Preliminary Evidence.

Tissue hypoxia is one of the main pathophysiologic mechanisms in sepsis and particularly in COVID-19. Microvascular dysfunction, endothelialitis and alterations in red blood cell hemorheology are all implicated in severe COVID-19 hypoxia and multiorgan dysfunction. Tissue hypoxia results in tissue injury and remodeling with re-emergence of fetal programming via hypoxia-inducible factor-1α (HIF-1a)-dependent and -independent pathways. In this context, thyroid hormone (TH), a critical regulator of organ maturation, may be of relevance in preventing fetal-like hypoxia-induced remodeling in COVID-19 sepsis. Acute triiodothyronine (T3) treatment can prevent cardiac remodeling and improve recovery of function in clinical settings of hypoxic injury as acute myocardial infarction and by-pass cardiac surgery. Furthermore, T3 administration prevents tissue hypoxia in experimental sepsis. On the basis of this evidence, the use of T3 treatment was proposed for ICU (Intensive Care Unit) COVID-19 patients (Thy-Support, NCT04348513). The rationale for T3 therapy in severe COVID-19 and preliminary experimental and clinical evidence are discussed in this review.

Potential Interaction Between SARS-CoV-2 and Thyroid: A Review.

The novel coronavirus disease 2019 (COVID-19) produced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is sweeping the world in a very short time. Although much has been learned about the clinical course, prognostic inflammatory markers, and disease complications of COVID-19, the potential interaction between SARS-CoV-2 and the thyroid is poorly understood. In contrast to SARS-CoV-1, limited available evidence indicates there is no pathological evidence of thyroid injury caused by SARS-CoV-2. However, subacute thyroiditis caused by SARS-CoV-2 has been reported for the first time. Thyroid dysfunction is common in patients with COVID-19 infection. By contrast, certain thyroid diseases may have a negative impact on the prevention and control of COVID-19. In addition, some anti-COVID-19 agents may cause thyroid injury or affect its metabolism. COVID-19 and thyroid disease may mutually aggravate the disease burden. Patients with SARS-CoV-2 infection should not ignore the effect on thyroid function, especially when there are obvious related symptoms. In addition, patients with thyroid diseases should follow specific management principles during the epidemic period.

A Preclinical Safety Study of Thyroid Hormone Instilled into the Lungs of Healthy Rats-an Investigational Therapy for ARDS.

Acute respiratory distress syndrome (ARDS) is a severe, life-threatening form of respiratory failure characterized by pulmonary edema, inflammation, and hypoxemia due to reduced alveolar fluid clearance (AFC). Alveolar fluid clearance is required for recovery and effective gas exchange, and higher rates of AFC are associated with reduced mortality. Thyroid hormones play multiple roles in lung function, and L-3,5,3'-triiodothyronine (T3) has multiple effects on lung alveolar type II cells. T3 enhances AFC in normal adult rat lungs when administered intramuscularly and in normal or hypoxia-injured lungs when given intratracheally. The safety of a commercially available formulation of liothyronine sodium (synthetic T3) administered intratracheally was assessed in an Investigational New Drug Application-enabling toxicology study in healthy rats. Instillation of the commercial formulation of T3 without modification rapidly caused tracheal injury and often mortality. Intratracheal instillation of T3 that was reformulated and brought to a neutral pH at the maximum feasible dose of 2.73 µg T3 in 300 µl for 5 consecutive days had no clinically relevant T3-related adverse clinical, histopathologic, or clinical pathology findings. There were no unscheduled deaths that could be attributed to the reformulated T3 or control articles, no differences in the lung weights, and no macroscopic or microscopic findings considered to be related to treatment with T3. This preclinical safety study has paved the way for a phase I/II study to determine the safety and tolerability of a T3 formulation delivered into the lungs of patients with ARDS, including coronavirus disease 2019-associated ARDS, and to measure the effect on extravascular lung water in these patients. SIGNIFICANCE STATEMENT: There is growing interest in treating lung disease with thyroid hormone [triiodothyronine (T3)] in pulmonary edema and acute respiratory distress syndrome (ARDS). However, there is not any published experience on the impact of direct administration of T3 into the lung. An essential step is to determine the safety of multiple doses of T3 administered in a relevant animal species. This study enabled Food and Drug Administration approval of a phase I/II clinical trial of T3 instillation in patients with ARDS, including coronavirus disease 2019-associated ARDS (T3-ARDS ClinicalTrials.gov Identifier NCT04115514).

Triiodothyronine for the treatment of critically ill patients with COVID-19 infection: A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: Tissue hypoxia is the main cause of multi-organ dysfunction in sepsis. However, effective pharmacological treatments to combat sepsis-induced tissue hypoxia are not available. Emerging experimental and clinical evidence reveals an evolutionary conserved action of thyroid hormone (TH) to adapt injured tissue to hypoxic conditions via its action on p38 MAPK, Akt signaling pathways. In addition, TH has favorable effects on the immune system and viral load in infected tissue. Non-Thyroid Illness Syndrome is common in sepsis, acute myocardial infarction and trauma and is associated with increased mortality. Thus, TH may be a novel treatment in the setting of critical illness due to viral infection in which hypoxia prevails. The present study aims to address the efficacy and safety of acute administration of triiodothyronine (T3) in critically ill COVID-19 infected patients requiring mechanical respiratory support or Extra Corporeal Membrane Oxygenation (ECMO). TRIAL DESIGN: This study is a phase II, parallel, 2-arm (1:1 ratio), multi-centre, prospective, randomized, double-blind, placebo controlled trial. PARTICIPANTS: Male and female patients aged over 18 years old who are diagnosed with pulmonary infection due to COVID-19, admitted to Intensive Care Unit and requiring mechanical ventilation or ECMO will be enrolled in this trial. Patients will be excluded in cases of pregnancy, severe systemic disease with life expectancy less than 6 months, participation in another trial of an investigational drug or device, corticosteroid and/or sympathomimetic use before initiation of treatment. All data will be collected in electronic CRF files. Participants will start to be recruited from the ICU center of "ATTIKO" University Hospital in Greece. We aim to include two more clinical sites in the trial one from Greece and one from Germany INTERVENTION AND COMPARATOR: Intervention: T3 Solution for injection 10 µg/ml. The dose administered will be 0.8g/kg i.v. bolus and will be followed by an infusion of 0.113g. kg-1.h-1 i.v. for 48 hours (therapeutic dose). After the first 48h, a maintenance dose will be administered corresponding to 50% of the therapeutic dose (0.057g. kg-1.h-1 i.v.). Drug administration will stop after successful weaning or end of follow up (maximum 30 days). Comparator: Placebo with composition and dosage identical apart from the active substance. MAIN OUTCOMES: The primary outcome assessed in the present study will be the percentage of patients successfully weaned after 30 days of follow-up. Successful weaning is defined as no requirement for ventilatory support after extubation (mechanical support) or support from ECMO for 48 hours. RANDOMISATION: An allocation sequence to one of the groups will be prepared by the Sponsor of the study. A 1:1 treatment allocation will be adopted. An electronic CRF will be used incorporating IWRS in order to assure proper randomization and unblinding in emergency cases. The representative of the sponsor will get a copy of randomization codes. The information of the randomization codes will then be locked in the database until the time at which an interim analysis or final analysis is performed. BLINDING (MASKING): Participants, caregivers, and all investigators assessing the outcomes will be blinded to group assignment. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): The sample size of 60 patients (that indicates 30 subjects for each group) will have 84% power to detect the estimated difference between the two study groups. The criterion for significance (alpha) has been set at 0.05 and the test is 2-tailed. TRIAL STATUS: Protocol number T3inj-02/ThySupport, version 03, May 11, 2020. The trial is not recruiting yet. The trial will start recruitment June 18th 2020. Estimated recruitment will finish June 18th, 2021. TRIAL REGISTRATION: Triiodothyronine for the Treatment of Critically Ill Patients With COVID-19 Infection (Thy-Support), ClinicalTrials.gov Identifier: NCT04348513, date of trial registration: April 16, 2020, EudraCT Identifier: 2020-001623-13, date of trial registration: April 22, 2020 FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.