Experimental study on the effect of luteolin on the proliferation, apoptosis and expression of inflammation-related mediators in lipopolysaccharide-induced keratinocytes

Abstract

Objective This study aimed at exploring the effects of luteolin on psoriasis-like cell model proliferation, apoptosis regulation and the expression of inflammation-related mediators. Methods A Cell Counting Kit-8 (CCK-8) assay was used to determine the survival rate of human immortalized keratinocytes (HaCaT cells) and normal human epidermal keratinocytes (NHEK cells) following stimulation with luteolin and lipopolysaccharide (LPS). Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to detect the protein and mRNA expressions of nuclear factor (NF)-κB p65 and interleukin (IL)-6 after LPS stimulation. Then a luteolin stimulation protocol (10 μmol/L, 24 h) was determined and a reasonable LPS stimulation concentration (20 μg/mL, 24 h) was chosen to establish the psoriasis cell model. Keratinocytes in luteolin pre-treatment and control groups were stimulated with 20 μg/mL LPS for 24 h, and the expressions of NF-κB p65 and IL-6 were detected by western blot and RT-qPCR. The apoptosis of HaCaT cells was detected by flow cytometry, and the enzyme-linked immunosorbent assay (ELISA) was used to detect the expression of psoriasis-related inflammatory factors. Results CCK-8 assay indicated that luteolin inhibited the proliferation of keratinocytes. LPS stimulated the proliferation of keratinocytes and upregulated the expression of NF-κB p65 and IL-6 in a concentration-dependent manner, and induced psoriasis-like changes. Furthermore, the protein and mRNA expression levels of NF-κB p65 and IL-6 were decreased in the luteolin pre-stimulation group ( p < 0.05). Treatment with luteolin downregulated the expression of the LPS-induced inflammatory mediators in keratinocytes ( p < 0.05). The flow cytometry results showed that luteolin induced HaCaT cells apoptosis. Finally, ELISA results demonstrated that luteolin inhibited the release of the IL-17, IL-23 and tumor necrosis factor α (TNF-α) in the pre-stimulation group ( p < 0.05). Conclusion This study confirmed that luteolin can effectively relieve inflammatory mediators in LPS-induced keratinocyte models of psoriasis, which suggested the potential of luteolin in treating psoriasis.

Insulin Stimulates IL-23 Expression in Human Adipocytes: A Possible Explanation for the Higher Prevalence of Psoriasis in Obesity

“…Finally, lipopolysaccharide (LPS), a component of the gram-negative bacterial wall that is known to induce inflammatory cytokine secretion by adipocytes and involved in keratinocyte stimulation in psoriasis, 15 , 16 did not stimulate any increase of IL-23 expression in human adipocytes in vitro ( Figure 4 ). All these results further suggest that the stimulatory effect of insulin on IL-23 expression by human adipocytes is selective and specific.…”

“…Given the fact that lipopolysaccharide (LPS), a complex molecule of gram-negative bacteria cellular wall, can stimulate an inflammatory response in adipocytes 15 and keratinocytes, 16 we have compared the effects of insulin on adipocyte expression of IL-23 with those of LPS.…”

Mechanistic Investigation of WWOX Function in NF-kB-Induced Skin Inflammation in Psoriasis

“…These cells release specific inflammatory mediators, such as tumor necrosis factor-alpha, IL-1, and IL-6, which subsequently drive keratinocyte proliferation. The release of these inflammatory mediators activates myeloid dendritic cells, prompting the secretion of IL-12 and IL-23 by naïve T cells, thus facilitating the differentiation of naïve T cells into T helper (Th)1 and Th17 cells [ 51 , 52 , 53 ]. A recent study highlighted correlations between psoriasis severity and TNF-α-related mitogen-activated protein kinase, NF-kB, and Janus kinase pathways [ 54 ].…”

Glycyrol Prevents the Progression of Psoriasis-like Skin Inflammation via Immunosuppressive and Anti-Inflammatory Actions

“…In this study, we demonstrated that GC inhibited the proliferation of HaCaT cells and induced their death. LPS is usually used for stimulating HaCaT cells to make an in vitro inflammation model [45][46][47]. LPS promotes the phosphorylation of JAK1 and STAT3, leading to increased cellular inflammation [45].…”