HAEMOPHILUS-DUCREYI INFECTION CAUSES BASAL KERATINOCYTE CYTOTOXICITY AND ELICITS A UNIQUE CYTOKINE INDUCTION-PATTERN IN AN IN-VITRO HUMAN SKIN MODEL

Haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. Predominantly a cutaneous pathogen, H. ducreyi is present in chancroid ulcers that are characterized by ex tensive neutrophil accumulation in intraepidermal lesions accompanied by a mononuclear infiltrate in the dermis. We used an in vitro human s kin model composed of foreskin fibroblasts and keratinocytes to examin e host skin cell interactions with H. ducreyi 35000. Bacteria replicat ed and persisted in artificial skin for at least 14 days. We observed H. ducreyi inside suprabasal keratinocytes using transmission electron microscopy. Although no bacteria were seen in the basal keratinocyte region, these cells were disrupted in infected cocultures. H. ducreyi infection stimulated increased secretion of interleukin-6 (IL-6) and I L-8 by skin cells. Conversely, tumor necrosis factor alpha and IL-1 al pha levels were not elevated. IL-8 produced in response to H. ducreyi infection may be involved in recruiting polymorphonuclear leukocytes a nd other inflammatory cells, thereby contributing to the tissue necros is and ulcer formation characteristic of chancroid.