Modulation of the pro-inflammatory cytokines and matrix metalloproteinases production in co-cultivated human keratinocytes and melanocytes

Abstract

The human epidermis exerts immunoregulatory functions through the variety of cytokines and other molecules elaborated by keratinocytes and melanocytes. Their constitutive production is very low; however, considerably increased upon stimulation. In vivo, keratinocytes and melanocytes have a typical exposure in the skin, referred as melanocyte epidermal unit. In the present study we co-cultivated these cells in vitro proposing to elucidate some communication links in close cell-to-cell association. We assessed the amounts of IL-6, IL-8, and matrix metalloproteinases (MMP-2 and MMP-9) in individually and co-cultured cells, exposed or not to UVB radiation. Normal human epidermal keratinocytes and melanocytes were grown in specific media and supplements. Cells were exposed to UVB radiation (100 mJ/cm(2)) to create comparable stress to the environmental one. Cytokines were determined with ELISA and confirmed with Western blot and metalloproteinases with gel zimography. Pure cultures of keratinocytes and melanocytes released low amounts of cytokines and metalloproteinases, these secretions being enhanced by UVB irradiation. In co-cultures, the cell-to-cell proximity triggered signals which markedly augmented the cytokines' secretions, whereas metalloproteinases were down-regulated. UVB irradiation did not influence either of these secretions in co-cultures. Concurrently with the highest levels of the pro-inflammatory cytokines, MMP-9 was up-regulated creating pro-inflammatory conditions and premises for changes in cellular survival, differentiation and phenotype. A complex network of interactions occurred between keratinocytes and melanocytes in co-cultures, resulting in modulated pro-inflammatory cytokines and metalloproteinases productions. Therefore, any disturbances in the microenvironmental signaling system and its molecular constituents may result in inflammation or even tumorigenesis in the epidermis.

Paracrine regulation of melanogenesis

“…1). 3,[6][7][8] Furthermore, several studies have shown that extracellular matrix (ECM) proteins, which are responsible for structure formation and the transduction of cellular signalling pathways in the skin, can affect melanogenesis. 9,10 In addition, an intimate relationship between the cutaneous nervous system and melanocytes has been reported.…”

“…Neighbouring cells around melanocytes, such as keratinocytes, fibroblasts and immune cells, positively or negatively influence melanogenesis by secreting paracrine factors in response to UV irradiation or inflammatory conditions (Fig. ) . Furthermore, several studies have shown that extracellular matrix (ECM) proteins, which are responsible for structure formation and the transduction of cellular signalling pathways in the skin, can affect melanogenesis .…”

Low-dose radiations derived from cone-beam CT induce transient DNA damage and persistent inflammatory reactions in stem cells from deciduous teeth

“…41 Similar to the current findings a dose-dependent manner of CKs increase after irradiation of keratinocytes and melanocytes was described earlier by authors from the present group. 42 In the blood cells of Hiroshima 11 survivors, chronically exposed to IR, transcriptional modulations of several CKs were measured, including IL-1β, IL-2, IL-8, IL-10, IL-12β, TNFα/β, and macrophage colony-stimulating factor. In another study, 43 IL-6 and IL-8 were identified in the growth medium of human dermal fibroblasts after exposure to 2 Gy, IL-6 being reported to promote γH2AX foci formation.…”

Morphological Characterization of Local Defence System in the Skin of Psoriasis Patients. Summary of the Doctoral Thesis

“…Along with these inflammatory cytokines was observed also increase of MMP-9 factor. Thus, presumably, tissue degeneration markers create the conditions for the development of the inflammation and combined with IL-6 and IL-8 affect cellular differentiation and even phenotype (Decean et al, 2013). MMPs in serum and synovial fluid have become valuable diagnostic biomarkers for evaluation of psoriatic arthritis and its treatment with TNF-α blocking agents used also in the treatment of psoriasis (Giannelli et al, 2004;Chandran et al, 2013).…”