TY - JOUR

T1 - The Epidermal Growth Factor Receptor Is a Regulator of Epidermal Complement Component Expression and Complement Activation

AU - Abu-Humaidan, Anas H A

AU - Ananthoju, Nageshwar

AU - Mohanty, Tirthankar

AU - Sonesson, Andreas

AU - Alberius, Per

AU - Schmidtchen, Artur

AU - Garred, Peter

AU - Sørensen, Ole E

PY - 2014/4/1

Y1 - 2014/4/1

N2 - The complement system is activated in response to tissue injury. During wound healing, complement activation seems beneficial in acute wounds but may be detrimental in chronic wounds. We found that the epidermal expression of many complement components was only increased to a minor extent in skin wounds in vivo and in cultured keratinocytes after exposure to supernatant from stimulated mononuclear cells. In contrast, the epidermal expression of complement components was downregulated in ex vivo injured skin lacking the stimulation from infiltrating inflammatory cells but with intact injury-induced epidermal growth factor receptor (EGFR)-mediated growth factor response. In cultured primary keratinocytes, stimulation with the potent EGFR ligand, TGF-α, yielded a significant downregulation of complement component expression. Indeed, EGFR inhibition significantly enhanced the induction of complement components in keratinocytes and epidermis following stimulation with proinflammatory cytokines. Importantly, EGFR inhibition of cultured keratinocytes either alone or in combination with proinflammatory stimulus promoted activation of the complement system after incubation with serum. In keratinocytes treated solely with the EGFR inhibitor, complement activation was dependent on serum-derived C1q, whereas in keratinocytes stimulated with a combination of proinflammatory cytokines and EGFR inhibition, complement activation was found even with C1q-depleted serum. In contrast to human keratinocytes, EGFR inhibition did not enhance complement component expression or cause complement activation in murine keratinocytes. These data demonstrate an important role for EGFR in regulating the expression of complement components and complement activation in human epidermis and keratinocytes and, to our knowledge, identify for the first time a pathway important for the epidermal regulation of complement activation.

AB - The complement system is activated in response to tissue injury. During wound healing, complement activation seems beneficial in acute wounds but may be detrimental in chronic wounds. We found that the epidermal expression of many complement components was only increased to a minor extent in skin wounds in vivo and in cultured keratinocytes after exposure to supernatant from stimulated mononuclear cells. In contrast, the epidermal expression of complement components was downregulated in ex vivo injured skin lacking the stimulation from infiltrating inflammatory cells but with intact injury-induced epidermal growth factor receptor (EGFR)-mediated growth factor response. In cultured primary keratinocytes, stimulation with the potent EGFR ligand, TGF-α, yielded a significant downregulation of complement component expression. Indeed, EGFR inhibition significantly enhanced the induction of complement components in keratinocytes and epidermis following stimulation with proinflammatory cytokines. Importantly, EGFR inhibition of cultured keratinocytes either alone or in combination with proinflammatory stimulus promoted activation of the complement system after incubation with serum. In keratinocytes treated solely with the EGFR inhibitor, complement activation was dependent on serum-derived C1q, whereas in keratinocytes stimulated with a combination of proinflammatory cytokines and EGFR inhibition, complement activation was found even with C1q-depleted serum. In contrast to human keratinocytes, EGFR inhibition did not enhance complement component expression or cause complement activation in murine keratinocytes. These data demonstrate an important role for EGFR in regulating the expression of complement components and complement activation in human epidermis and keratinocytes and, to our knowledge, identify for the first time a pathway important for the epidermal regulation of complement activation.

KW - Animals

KW - Apoptosis

KW - Blotting, Western

KW - Cell Line

KW - Cells, Cultured

KW - Complement Activation

KW - Complement System Proteins

KW - Epidermis

KW - Gene Expression

KW - Humans

KW - Keratinocytes

KW - Mice

KW - Microscopy, Fluorescence

KW - Oligonucleotide Array Sequence Analysis

KW - Quinazolines

KW - Receptor, Epidermal Growth Factor

KW - Reverse Transcriptase Polymerase Chain Reaction

KW - Skin

KW - Transcriptome

KW - Transforming Growth Factor alpha

KW - Tyrphostins

U2 - 10.4049/jimmunol.1302305

DO - 10.4049/jimmunol.1302305

M3 - Journal article

C2 - 24591374

VL - 192

SP - 3355

EP - 3364

JO - Journal of Immunology

JF - Journal of Immunology

SN - 0022-1767

IS - 7

ER -