Vitronectin in bacterial pathogenesis: a host protein used in complement escape and cellular invasion

Area of Science:

• Molecular Biology
• Immunology
• Microbiology
• Pathogenesis

Background:

• Vitronectin (Vn) is a multifunctional human glycoprotein involved in cell migration, tissue repair, and regulating the membrane attack complex (MAC).
• Vn plays a crucial role in maintaining host homeostasis by neutralizing self-reactivity of the MAC.
• Vn also promotes inflammation by enhancing neutrophil infiltration during infections.

Purpose of the Study:

• To review the significant roles of vitronectin in bacterial pathogenesis.
• To describe pathogen strategies for evading host responses using vitronectin.
• To elucidate the dual function of vitronectin in host defense and bacterial virulence.

Main Methods:

• Literature review focusing on vitronectin's interactions with host cells and pathogens.
• Analysis of molecular mechanisms involving vitronectin in bacterial adhesion and immune evasion.
• Examination of specific bacterial species utilizing vitronectin, including Gram-negative and Gram-positive pathogens.

Main Results:

• Vitronectin binding to bacterial surfaces protects pathogens from MAC-mediated lysis and enhances adhesion.
• Gram-negative pathogens (Moraxella catarrhalis, Haemophilus influenzae, Neisseria gonorrhoeae) recruit Vn to prevent MAC deposition.
• Gram-positive pathogens (Streptococcus pneumoniae, S. pyogenes) use Vn for adhesion and host cell internalization via integrin binding.

Conclusions:

• Vitronectin acts as a molecular bridge, cross-linking bacteria and host epithelial cells through its RGD sequence and bacterial-binding domain.
• Pathogens strategically utilize vitronectin to promote their adhesion, invasion, and survival, thereby subverting host immune defenses.
• Understanding vitronectin's role in pathogenesis is crucial for developing novel therapeutic strategies against bacterial infections.