Depletion of PD-1 or PD-L1 did not affect the mortality of mice infected with Mycobacterium avium

Area of Science:

• Immunology
• Microbiology
• Infectious Diseases

Background:

• The PD-1/PD-L1 pathway regulates T cell activity and impacts antimicrobial immunity.
• Blocking PD-1/PD-L1 exacerbates Mycobacterium tuberculosis infection.
• The role of PD-1/PD-L1 in pulmonary Mycobacterium avium complex (MAC) infection remains unclear.

Purpose of the Study:

• To investigate the effect of PD-1 and PD-L1 deficiency on susceptibility to pulmonary MAC infection.
• To analyze immune responses, including T cell infiltration and gene expression, in MAC-infected mice lacking PD-1 or PD-L1.

Main Methods:

• Intranasal infection of wild-type, PD-1-deficient, and PD-L1-deficient mice with Mycobacterium avium.
• Assessment of mortality and bacterial burden.
• Analysis of lung immune cell infiltration (CD8 T lymphocytes).
• Comprehensive transcriptome analysis of lung tissues.

Main Results:

• PD-1 or PD-L1 deficiency did not affect mortality or bacterial burden in MAC-infected mice.
• Increased infiltration of CD8 T lymphocytes was observed in the lungs of PD-1 and PD-L1-deficient mice.
• Gene expression related to CD8 T cell activity and chemokine signaling was upregulated in PD-1/PD-L1-deficient mice.
• No significant differences in Th1 immune response gene expression were found across genotypes.

Conclusions:

• The PD-1/PD-L1 pathway does not appear to be a major determinant of susceptibility to pulmonary MAC infection.
• Enhanced CD8 T cell activity in PD-1/PD-L1-deficient mice did not translate to improved control of MAC infection.
• The Th1 immune response is likely not significantly altered by PD-1/PD-L1 deficiency in this model.