Cathelicidins

Antimicrobial peptides (also known as alarmins) found in the lysosomes of neutrophil granulocytes (PMN) and macrophages are detectable in many mammals. Cathelicidins are translated from a precursor peptide (hCAP 18) in these cells after their activation by bacteria, viruses, fungi or hormones (e.g. vitamin D3: questionable influence by UV irradiation) and further processed by the serine proteases Kallikrein 5 and Kallikrein 7 to the active cathelicin peptide LL37 .

Cathelicidins have less than 100 amino acids and are found on the skin and in the colon. They have a broad spectrum of activity and can render Gram-positive and Gram-negative bacteria and fungi harmless. Together with the defensins they are among the most important representatives of the so-called antimicrobial peptides.

Cathelicidins are only slightly expressed in healthy skin. High concentrations are found in barriauterine disorders of the skin, caused by wounds or infections. Certain skin diseases such as atopic eczema or psoriasis are characterized by a misregulation of the cathelicidins.

In patients with rosacea, elevated levels of cathelicidin have been found, an indication of a disorder of innate immunity.

1. Dombrowski Y et al (2010) Alarmine and its significance for inflammatory skin diseases. Act Dermatol 36: 467-470
2. Elias PM et al (2005) Interactions among stratum corneum defensive functions. Experimental Dermatol 14: 719-726