C3 Production of Cultured Human Epidermal Keratinocytes in Enhanced by IFNγ and TNFα through Different Pathways

Abstract

We investigated the regulation of C3 production by human cultured epidermal keratinocytes by enzyme-linked immunosorbent assay. The results showed that IFNgamma and TNFalpha enhanced the synthesis of C3 by epidermal keratinocytes in a concentration-dependent manner. Moreover, a protein kinase C (PKC) inhibitor blocked C3 production, whereas PMA enhanced it. There was a synergistic effect between IFNgamma and TNFalpha. In experiments to investigate the role of protein tyrosine kinase (PTK) in C3 production, we found that treatment with herbimycin A, a specific inhibitor for the c-Src-related PTK, caused significant enhancement of the C3 production induced by IFNgamma or TNFalpha, suggesting that c-Src-type PTK(s) provides a negative signal to C3 production. Each competitive inhibitor of PTK, genistein or tyrphostin, substantially increased the C3 production by IFNgamma at lower concentrations, although each agent had little effect on TNFalpha-associated production of C3 at the same concentrations. The data show that pro-inflammatory cytokines IFNgamma and TNFalpha synergistically augment C3 production by epidermal keratinocytes by different pathways.

Role of neutrophils in induction of acute inflammation in T‐cell‐mediated immune dermatosis, psoriasis: A neutrophil‐associated inflammation‐boosting loop

“…To facilitate the alternative complement pathway, its two essential components, factor B and C3, are produced in the skin by cultured human keratinocytes (77). Furthermore, we recently demonstrated that C3 is more effectively produced by differentiated keratinocytes, such as those found in the upper epidermis, than by actively proliferating keratinocytes comprising the basal cell layer, and that T-cell-derived cytokines such as IFN-g and TNF-a synergistically enhance the generation of C3 from these cells (78). Thus, proinflammatory mediators, IL-8 and C3 may be produced at both the ''acute'' and ''chronic'' inflammatory sites (68, 5 79) as long as there are activated T cells and macrophages.…”

“…Although C3, the key component of the complement system, tends to be produced more in the upper, more differentiated keratinocytes (78), the exact mechanisms that lead to complement activation in skin lesions remain to be elucidated, particularly on the surface of corneocytes. Exocytosis of inflammatory cells into the lesional epidermis, which is prominent in the edematous suprapapillary portion of the lesional epidermis, possibly results in damage of the basement membrane zone and the overlying epidermal cells (80).…”

Cutting Edge: Myeloid Complement C3 Enhances the Humoral Response To Peripheral Viral Infection

“…4), it is most likely that C3 is activated and coupled to viral Ags within the local lymph node that drains the site of infection. Although the regulation of C3 synthesis by macrophages in vivo is not known, studies with human and murine cell lines indicate that C3 secretion can be induced by multiple cytokines such as IFN-␥ (46, 47), IL-6 (48), TNF (38), IL-1 (49), and IL-2 (40). Macrophages secrete other components of complement in addition to C3 and in particular C4, C2, C1r, C1s, and C1q (36,50,51).…”

“…However, a number of extrahepatic sources of C3 synthesis have been described. These include myeloid lineage cells such as monocytic cells (36) and polymorphonuclear leukocytes (37) as well as non-bone marrow (non-BM)-derived sources such as epidermal keratinocytes (38), kidney tubular epithelial cells (39,40), and umbilical vein endothelial cells (41). The potential of macrophage-derived C3 in the humoral response to protein Ag was determined using C3 Ϫ/Ϫ BM chimeras that received wild-type (WT) BM (WT BM3 C3 Ϫ/Ϫ ).…”

Myeloid C3 Determines Induction of Humoral Responses to Peripheral Herpes Simplex Virus Infection

“…Nonhepatic cells, such as keratinocytes (17), kidney tubular epithelial cells (18), and macrophages (19), provide additional sources of C3. The contribution to the circulation from these secondary sources varies greatly depending on the system, from clearly detectable (20,21) to negligible (22,23).…”