Induction of inflammatory reactions by lipopolysaccharide in hamster sebaceous glands and pilosebaceous units in vivo and in vitro

Lipopolysaccharide (LPS) from Gram-negative bacteria has been reported to exert inflammatory reactions in epidermis, dermis, and sebaceous glands. Here, we demonstrated that the intradermal administration of Escherichia coli-derived LPS, three times a week for 4 weeks, to hamster auricle skin did not influence sebaceous morphology or sebum accumulation in sebaceous glands but in fact induced epidermal thickness. In addition, the administration of LPS, once a day for 2 days, augmented the production of cyclooxygenase 2 (COX-2) in sebaceous glands. Furthermore, LPS increased the production of prostaglandin F-2 alpha (PGF(2 alpha)) in hamster sebocytes. Moreover, the production of progelatinase A/promatrix metalloproteinase 2 (proMMP-2) was transcriptionally augmented by LPS and PGF(2 alpha) in hamster sebocytes. Therefore, these results suggest that LPS directly increases inflammation by augmenting COX-2, PGF(2 alpha), and the PGF(2 alpha)-mediated proMMP-2 production in sebaceous glands as well as epidermal inflammatory events in skin disorders including acne and folliculitis.