Table 1

Structure, anti-microbial and immunomodulatory activities of innate immunity proteins and peptides

Protein

Structure

pI

Pulmonary Source

Antimicrobial activity

Immunomodulatory activity


Lactoferrin

Iron- binding glycoprotein MW 80 kDa

8.7

Neutrophil secondary specific granules and submucosal gland epithelial cells

Bactericidal Bacteriostatic Inhibits biofilm formation Anti-fungal Anti-viral

Binds LPS and can prevent septic shock.

Binds CPG motifs.

Anti-oxidant.

SLPI

11.7 kDA non-glcosylated protein

>9.2

Macrophages, epithelial cells, neutrophils

Bactericidal Bacteriostatic Anti-viral

Powerful anti-protease Inhibits LPS-induced NF-κB activation.

Attenuates pulmonary recruitment of neutrophils in sepsis models.

Impairs LTA and LPS induced proinflammatory gene expression in monocytes and macrophages.

Lysozyme

14 kDA enzyme

10.5

Neutrophil secondary specific granules and submucosal gland epithelial cells

Bactericidal Bacteriostatic

Unknown

Human Defensins

3–5 kDA peptides

8.8–9.5

Neutrophil azurophil granules and pulmonary epithelial cells

Bactericidal Bacteriostatic Anti-parasitic Anti-fungal Anti-viral

Mitogenic and chemotactic activities.

Contribute to epithelial repair in the lung by enhancing epithelial cell proliferation.

LL-37

Peptide that requires proteolytic processing to liberate the mature functional antimicrobial peptide.

Neutrophil secondary specific granules and submucosal gland epithelial cells

Bactericidal Bacteriostatic Anti-fungal Anti-viral

Reduced production of the pro-inflammatory cytokine TNF-α from macrophages stimulated with LPS and may be responsible for the migration of immune cells to areas of inflammation and infection

BPI

55-kDa protein

9.6

Neutrophil primary granules

Bactericidal Bacteriostatic Act as an opsonin to enhance neutrophil phagocytosis.

Downregulates LPS and other endotoxins in vivo

Surfactant proteins A and D

Lipoprotein complex

4.5–5.4

Type II pneumocytes, airway Clara cells

Key opsonins facilitating phagocytosis of bactaeria and viruses. Bactericidal Bacteriostatic Anti-fungal Anti-viral

Both SP-A and SP-D have the capacity to modulate multiple leucocyte functions

Lactoperoxidase

Enzyme

Airway epithelium

Bactericidal Anti-fungal Anti-viral

CCL20

Chemokine with similar structure to HBD

Airway epithelium

Bactericidal against Gram negative bacteria

Stimulates the migration of B-cells, immature dendritic cells, and a subset of memory T cells


Rogan et al. Respiratory Research 2006 7:29   doi:10.1186/1465-9921-7-29

Open Data