Interleukin-6 Production In Fibroblasts Research Articles

Treponema pallidum recombinant protein Tp47 enhanced interleukin-6 secretion in human dermal fibroblasts through the toll-like receptor 2 via the p38, PI3K/Akt, and NF-κB signalling pathways

Interleukin-6 (IL-6) is a multi-effective cytokine involved in multiple immune responses. Whether fibroblasts also turn out to be a cytokine IL-6 factory during interaction with Treponema pallidum is not yet understood. To explore whether fibroblasts participate in inflammation due to syphilis, a series of experiments were performed to explore the role of T. pallidum lipoprotein Tp47 in IL-6 production in human dermal fibroblasts. The Toll-like receptor 2 (TLR2) and participating signalling pathways in this process were also evaluated. The results showed that the expressions of IL-6 and the protein levels of TLR2 in fibroblasts were upregulated after stimulation with Tp47, and this effect was impeded by the TLR2 inhibitor C29. In addition, Tp47 promoted the phosphorylation of p38, PI3K/Akt, and nuclear factor-kappaB (NF-κB), and the translocation of NF-κB in fibroblasts. Moreover, p38, PI3K, and NF-κB inhibitors significantly reduced IL-6 production in fibroblasts stimulated with Tp47. Furthermore, the TLR2 inhibitor C29 inhibited the phosphorylation of p38, Akt, and NF-κB, and the translocation of NF-κB in fibroblasts. In conclusion, our results showed that Tp47 enhanced IL-6 secretion in human dermal fibroblasts through TLR2 via p38, PI3K/Akt, and NF-κB signalling pathways. These findings contribute to our understanding of syphilis inflammation.

Interleukin-6 increases expression of serine protease inhibitor Kazal type 1 through STAT3 in colorectal adenocarcinoma.

Inflammation promotes colorectal cancer (CRC) tumorigenesis, but the underlying molecular mechanisms are still being uncovered. Proinflammatory cytokine interleukin-6 (IL-6) stimulates survival signaling in CRC; inflammatory signals also regulate production and activity of proteases and their inhibitors. Over-expression of serine protease inhibitor Kazal type 1 (SPINK1) predicts an unfavorable outcome in colon cancer. The SPINK1 gene contains an IL-6 responsive element, suggesting it could act as an acute phase reactant. We assessed the connection between IL-6 and SPINK1, and the function and mechanism of this signaling. Our results show that Colo205 and HT-29 cells express and secrete SPINK1, and both fibroblast-derived and recombinant IL-6 further increased the SPINK1 levels. Concurrently CRC cells augmented the IL-6 production in fibroblasts. In CRC tissues cancer cells were positive for SPINK1, whereas IL-6 was found in stromal cells. In Colo205 cells IL-6 also stimulated the secretion of trypsin-1 and -2, the key targets of SPINK1 protease inhibition, whereas in HT-29 cells trypsin-1 and -2 levels remained constantly low. Functionally, both IL-6 and SPINK1 increased the motility of the CRC cells. Mechanistically, IL-6 activated the canonical STAT3 pathway and inhibition of STAT3 phosphorylation decreased the levels of SPINK1, trypsin-1 and -2. Taken together, our results indicate a novel link between inflammatory signals originating from the tumor microenvironment and increased SPINK1 levels. This finding has potential therapeutic implications for targeted therapy, as it confirms that SPINK1 acts as an acute phase reactant and that it participates in the paracrine crosstalk with the tumor microenvironment of colon cancer. © 2015 Wiley Periodicals, Inc.

Modulation of IL-6 Production of IL-1 Activity by Keratinocyte-Fibroblast Interaction

The present study was undertaken to investigate whether modulation of interleukin-6 and interleukin-1 production occurs owing to keratinocyte-fibroblast interaction. Normal human keratinocytes or squamous carcinoma cells were cultured either alone or in the presence of human foreskin fibroblasts or murine 3T3 cells. All cells tested produced interleukin-6, and interleukin-6 levels were markedly increased when normal or malignant keratinocytes were co-cultured with fibroblasts. The bioassay (species independent) and enzyme-linked immunosorbent assay (specific for human interleukin-6) together with use of complementary DNA probes specific for human or murine interleukin-6 revealed that fibroblasts are responsible for increased interleukin-6 levels. Moreover, interleukin-6 levels were increased when fibroblasts were cultured in conditioned media derived from normal human keratinocytes and squamous carcinoma cells-4 cultures. Interleukin-1 alpha secreted by normal human keratinocytes and squamous carcinoma cells-4 cells was mainly responsible for the increased interleukin-6 production in fibroblasts. Although interleukin-1 activity increased linearly with the incubation time in squamous carcinoma cells-4 monocultures, interleukin-1 activity was low and remained unchanged in squamous carcinoma cells-4/3T3 co-cultures. Low interleukin-1 activity was most probably not due to inhibition of interleukin-1 alpha production in squamous carcinoma cells-4/3T3 co-cultures because interleukin-1 alpha messenger RNA expression in squamous carcinoma cells-4 cells remained unchanged in the presence of 3T3 cells. Furthermore, when 3T3 cells were incubated in conditioned medium derived from squamous carcinoma cells-4 cells, high interleukin-1 activity decreased to an undetectable level, suggesting that fibroblasts are involved in the suppression of interleukin-1 activity. The remaining interleukin-1 activity, however, was sufficient for maximal induction of interleukin-6 production in fibroblasts. These results suggest that the interaction between epithelial and mesenchymal cells is at least partly initiated by interleukin-1 alpha secreted by the activated epithelial cell during skin injury or tumor invasion. Interleukin-1 in turn can induce modulation of the synthesis of various pro-inflammatory mediators and proteases in surrounding fibroblasts. An enhanced proteolytic activity and/or a possible induced production of an interleukin-1 inhibitor in fibroblasts and/or a receptor-mediated interleukin-1 consumption by fibroblasts will cause a decrease in interleukin-1 activity and thus exert a negative feedback.