This is the first-in-human phase 1 trial of TQC2731 injection in healthy subjects and in patients with severe asthma to evaluate the safety, tolerability, pharmacokinetic characteristics and immunogenicity.

Inclusion Criteria:

• Healthy subjects:Sign the informed consent form before the trial, fully understand the trial purpose, process and possible adverse reactions.
• Healthy subjects:Aged between 18 and 60 years old, both men and women;
• Healthy subjects:Female ≥45kg, male ≥50kg, body mass index (BMI) is 18-28 kg/m^2 (including the critical value), BMI=weight (kg)/height^2 (m^2);
• Asthma subjects:Aged between 18 and 70 years old, both men and women;
• Asthma subjects:Female ≥45kg, male ≥50kg;
• Asthma subjects:according to the GINA guidelines (GINA 2020), subjects who received middle, or high-dose ICS in asthma control drugs prescribed by the doctor at least 6 months prior to Visit 1;

Exclusion Criteria:

• Healthy subjects: Pregnant and lactating women;
• Healthy subjects:preexisting or existing heart, endocrine, metabolism, kidney, liver, gastrointestinal, skin, infection, blood, nerve, mental diseases or abnormalities, or related chronic or acute diseases, the investigator assesses that it is not appropriate to participate in the trial;
• Healthy subjects:Those whose vital signs, physical examination, laboratory examination, 12-lead electrocardiogram, and chest radiograph during the screening period are abnormal and have clinical significance;
• Healthy subjects:Hepatitis B virus surface antigen (HBsAg), hepatitis C virus antibody (Anti-HCV), human immunodeficiency virus antibody (Anti-HIV) and Treponema pallidum antibody (Anti-TP), any of the above positive subjects;
• Healthy subjects:A history of clinically significant infections before and during screening, including upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI), and requires antibiotic or antiviral treatment;
• Healthy subjects:Those who have undergone surgery within 4 weeks before screening, or plan to undergo surgery during the study period;
• Asthma subjects: Pregnant and lactating women;
• Asthma subjects:Patients with abnormal vital signs, physical examination, 12-lead electrocardiogram results and clinical significance during the screening period;
• Asthma subjects:preexisting or existing heart, endocrine, metabolism, kidney, liver, gastrointestinal, skin, infection, blood, nerve, or mental illness, etc., or related chronic or acute diseases, the investigator's assessment should not participate in the trial; (except for the target disease)
• Asthma subjects:Accompanied by clinically major lung diseases other than asthma (for example, active lung infection, non-asthmatic chronic obstructive pulmonary disease (COPD), bronchiectasis, pulmonary fibrosis, cystic fibrosis, obesity-related Hypoventilation syndrome, lung cancer, α1 antitrypsin deficiency, and primary ciliary dyskinesia) or accompanied by pulmonary or systemic diseases other than asthma that lead to increased peripheral blood eosinophil counts (for example, allergic Bronchopulmonary aspergillosis/mycosis, Churg-Strauss syndrome, eosinophilia syndrome). COPD with mainly asthma can be included;
• Asthma subjects:Any disease that has not been stabilized by the investigator, including but not limited to unstable cardiovascular, gastrointestinal, liver, kidney, nervous system, musculoskeletal, infectious, endocrine, metabolic, hematology, mental illness or major physical injury , May: affect the safety of the subject during the entire study period, affect the research results or interpretation of the results, and hinder the subject's ability to complete the entire study period.