Immunity and inflammation in the uterus

Area of Science:

• Veterinary Immunology
• Reproductive Immunology
• Infectious Disease

Background:

• Uterine infections are common in animals, causing inflammation and infertility.
• Adaptive immunity's role is known, but innate immunity's endometrial function is emerging.
• Infections are linked to natural service, pregnancy, and postpartum periods, involving cytokine and prostaglandin release.

Purpose of the Study:

• To review the emerging role of innate immunity in the animal endometrium.
• To explain how pattern recognition receptors detect microbes and initiate immune responses.
• To emphasize the endometrial epithelial and stromal cells' role in early defense.

Main Methods:

• Review of existing literature on innate immunity in the endometrium.
• Focus on pattern recognition receptors (PRRs) and their ligands.
• Examination of specific examples like Toll-like receptor 4 (TLR4) in endometrial cells.

Main Results:

• Innate immunity relies on PRRs detecting pathogen-associated molecular patterns (PAMPs).
• Key PRR families include Toll-like receptors (TLRs), NOD-like receptors, RIG-I-like receptors, and C-type lectin receptors.
• Endometrial epithelial and stromal cells express functional PRRs, such as TLR4, which recognizes Gram-negative bacterial lipopolysaccharide.

Conclusions:

• Endometrial epithelial and stromal cells act as a first line of defense against uterine microbes.
• Activation of PRRs like TLR4 leads to the secretion of inflammatory mediators (e.g., IL-6, IL-8, PGE2).
• This innate immune response is critical for alerting hematopoietic cells and initiating defense against uterine infections, impacting animal fertility.