Plasma Type I IFN Protein Concentrations in Human Tuberculosis

Area of Science:

• Immunology
• Infectious Diseases
• Biochemistry

Background:

• Tuberculosis (TB) is a major global health threat, with pathogenesis poorly understood, hindering new vaccine and treatment development.
• Type I interferons (IFNs) are crucial for antiviral responses, but their role in bacterial infections like TB is unclear.
• Interferon-stimulated genes (ISGs) have complex immune effects, necessitating clarification of type I IFN's role in TB.

Purpose of the Study:

• To test if active TB patients exhibit elevated circulating type I interferon (IFNα and IFNβ) levels.
• To compare type I IFN levels in active TB, asymptomatic *M. tuberculosis* infection, and acute influenza.

Main Methods:

• Quantification of plasma IFNα and IFNβ proteins using Simoa digital ELISA.
• Comparison of protein levels in patients with active TB, asymptomatic infection, and healthy controls.
• Inclusion of acute influenza infection as a positive control for type I IFN induction.

Main Results:

• No significant difference in plasma IFNα and IFNβ levels was observed between active TB patients and asymptomatic *M. tuberculosis* infected individuals.
• Plasma from patients with acute influenza infection showed significantly higher levels of both IFNα and IFNβ.
• A discordance between ISG mRNA expression in leukocytes and circulating type I IFN levels in TB was suggested.

Conclusions:

• Circulating type I interferon protein levels do not appear to be elevated in active TB disease.
• The study highlights a potential disconnect between systemic IFN protein levels and local immune responses in TB.
• Further research is needed to understand the complex role of type I IFNs in tuberculosis pathogenesis.