Pro Inflammatory Cytokines

Upon challenge with microbial compounds ke-ratinocytes express numerous cytokines acting as cytoprotective factors in the processes of the immune response.

In primary keratinocytes, S. aureus-derived PGN induces the secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) [47], a cytokine essential for the survival, differentiation, and maturation of dendritic and Langerhans cells. The effects of GM-CSF on the antigen-presenting cells shift the immune response to the Th2-type. Its mitogenic effect on keratinocytes is partially responsible for epidermal hypertrophy, characteristic of chronic inflammatory skin lesions.

Skin contains a reservoir of preformed IL-1a, leading to the concept that epidermis is a shield of sequestered IL-1 surrounding the host, waiting to be released upon injury. External stimuli such as wounding, burns, and microbial infection, or internal stimuli such as local cytokine release from stimulated leukocytes can induce the release of IL-1 for local or systemic delivery. Although high levels of IL-1RA also coexist within keratinocytes, the amount of IL-1 is sufficient to overcome any potential for inhibition mediated by IL-1RA.

Both heat-killed S. aureus and staphylococcal PGN induce the expression of TNF-a, IL-1|3, and IL-6 of primary keratinocytes [47, 51, 74]. TNF-a enhances the bactericidal effect of neu-trophils and promotes the adhesion of neutro-phils to endothelial cells. Thus, keratinocyte-derived TNF-a plays a crucial role in the recruitment of phagocytic cells into sites of infection. The contribution of IL-6 and TNF-a to granulomatous skin conditions, such as cutaneous leishmaniasis, granuloma annulare, leprosy or HS, is suggested by the occurrence of these cytokines in the granulomatous reactions [1]. Upon contact with pathogens, TNF-a, IL-1a, IL-1p, and IL-6 are also implicated in the autocrine induction of antimicrobial peptide expression (e.g., p-defensins and LL-37) by keratinocytes.

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

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