Murine C3 of the complement system affects infection by Leptospira interrogans

Area of Science:

• Immunology
• Infectious Diseases
• Microbiology

Background:

• Leptospirosis is a neglected infectious disease affecting over a million people annually.
• The complement system is vital for pathogen elimination, but its role in leptospirosis is not fully understood.
• Complement component 3 (C3) is a key player in innate and adaptive immunity.

Purpose of the Study:

• To investigate the role of C3 in Leptospira interrogans serovar Kennewicki strain Pomona Fromm (LPF) infection.
• To understand how C3 influences the host's immune response and bacterial clearance.
• To explore C3's impact on antibody production and bacterial shedding.

Main Methods:

• Utilized a mouse model lacking the C3 gene.
• Infected C3-deficient and wild-type mice with LPF.
• Assessed immune cell populations, inflammatory markers, bacterial load, and antibody responses.
• Monitored bacterial shedding in urine.

Main Results:

• C3 deficiency resulted in reduced leukocyte numbers and impaired inflammatory responses.
• Lack of C3 led to a failure in early bacterial elimination and delayed urinary clearance of LPF.
• Antibody production against Leptospira was compromised in C3-deficient mice.
• Lower levels of local opsonins were observed in the absence of C3.

Conclusions:

• C3 protein is essential for orchestrating an effective inflammatory response against LPF infection.
• C3 plays a critical role in the early elimination of Leptospira during the acute phase.
• The complement system, particularly C3, is vital for controlling leptospirosis and preventing long-term complications like interstitial nephritis.