Differentiation-regulated expression of Toll-like receptors 2 and 4 in HaCaT keratinocytes

Abstract

Toll-like receptors (TLRs) play an important role in the recognition of pathogens in keratinocytes. In this study, we investigated whether the differentiation state of HaCaT keratinocytes correlates with the expression of TLR2 and TLR4 genes. The expression levels of TLR2 and TLR4 in a HaCaT differentiation model system were determined using quantitative real-time RT-PCR (Q-RT-PCR) and flow cytometry. The progression of keratinocyte differentiation was monitored by determining the level of involucrin gene expression using Q-RT-PCR. The expression levels of TLR2 and TLR4 increased with the stage of differentiation and there were strong correlations between the expression level of the involucrin gene and those of the TLR2 gene ( r=0.809, P<0.0001) and the TLR4 gene ( r=0.568, P<0.02). Increased cell surface expression of TLR2 and TLR4 was also found in differentiated HaCaT keratinocytes by flow cytometric analysis. Our findings suggest that upregulation of TLR expression during differentiation in keratinocytes could be a part of the differentiation process of keratinocytes and could have biological significance in protecting skin against microbes.

Low Molecular Weight Hyaluronic Acid Increases the Self-Defense of Skin Epithelium by Induction of β-Defensin 2 via TLR2 and TLR4

“…1A), as previously observed on other keratinocyte cell lines and primary keratinocytes (17,18). An intense production of DEFB2, assessed by PCR and immunofluorescence analysis, was observed when cells were stimulated with the TLR2-and TLR4-specific bacterial ligands PGN and LPS, respectively, for 18 h (Fig.…”

Role of IRF6 in epithelial cell-mediated host defence and inflammation

“…This result contradicts the previous study in HaCaT cells that reported differences in TLR2 and TLR4 mRNA levels between undifferentiated and differentiated keratinocytes (Pivarcsi, Koreck et al 2004). This may be because HaCaT cell lines are immortalized keratinocytes obtained from adult skin, whilst the differentiation studies in this chapter were performed using primary keratinocytes from neonatal skin.…”

“…A previous study in HaCaT cells showed that TLR2 and TLR4 mRNA was upregulated during keratinocyte differentiation (Pivarcsi, Koreck et al 2004). Cell surface expression of TLR2 and TLR4 also increased.…”

TGF-α Regulates TLR Expression and Function on Epidermal Keratinocytes

“…Cytokines, chemokines, and antimicrobial peptides produced by epithelial cells enable them to participate in innate and acquired immune responses (1)(2)(3)(4)(5)(6). In addition, epithelia express certain TLRs, which may contribute to their ability to sense and respond to invading pathogens (3,(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”