Effects of mucopolysaccharide polysulphate on tight junction barrier in human epidermal keratinocytes

mTOR signaling pathway regulation HIF-1 α effects on LPS induced intestinal mucosal epithelial model damage

BACKGROUND

Sepsis-induced small-intestinal injury is associated with increased morbidity and mortality. Our previous study and other papers have shown that HIF-1α has a protective effect on intestinal mucosal injury in septic rats. The purpose of this study is to further verify the protective effect of HIF-1α on intestinal mucosa and its molecular mechanism in vitro experiments.

METHODS

Caco-2 cells were selected and experiment was divided into 2 parts. Part I: HIF-1α activator and inhibitor were used to treat lipopolysacchrides (LPS)-stimulated Caco-2 cells respectively, to explore the effect of HIF-1α on LPS induced Caco-2 cell epithelial model; Part II: mTOR activator or inhibitor combined with or without HIF-1α activator, inhibitor to treat LPS-stimulated Caco-2 cells respectively, and then the molecular mechanism of HIF-1α reducing LPS induced Caco-2 cell epithelial model damage was detected.

RESULTS

The results showed that HIF-1α activator decreased the permeability and up regulated tight junction (TJ) expression, while HIF-1α inhibitor had the opposite effect with the HIF-1α activator. mTOR activation increased, while mTOR inhibition decreased HIF-1α protein and expression of its downstream target molecules, which can be attenuated by HIF-1α activator or inhibitor.

CONCLUSION

This study once again confirmed that HIF-1α alleviates LPS-induced mucosal epithelial model damage through P70S6K signalling pathway. It is of great value to explore whether HIF-2α plays crucial roles in the regulation of mucosal epithelial model functions in the future.

Development of tight junction-strengthening compounds using a high-throughput screening system to evaluate cell surface-localized claudin-1 in keratinocytes

Tight junctions (TJs) are important factors constituting the physical barriers of the skin, and their suppression has been described in various conditions, such as aged skin and atopic dermatitis lesions. However, the methods for improving skin TJ function remain insufficient. Therefore, to obtain compounds that can improve TJ function, we developed a novel high-throughput screening system termed live-cell immunostaining to evaluate cell surface-localized claudin-1 (CLDN1) with high selectivity using normal human epidermal keratinocytes (NHEKs). Heparinoid and phospho-pyridoxal (p-Pyr), a metabolite of pyridoxine, were identified as hit compounds. In addition, heparinoid was strongly suggested to increase CLDN1 expression by inhibiting epidermal growth factor receptor signaling. By contrast, p-Pyr did not enhance CLDN1 expression, but it accelerated the translocation of CLDN1 to the cell surface. Finally, we confirmed that heparinoid and p-Pyr improved barrier function in NHEKs in a transepithelial electrical resistance assay. In conclusion, heparinoid and p-Pyr could potentially ameliorate skin conditions by improving TJ function.

Use of a Silkworm (Bombyx mori) Larvae By-Product for the Treatment of Atopic Dermatitis: Inhibition of NF-κB Nuclear Translocation and MAPK Signaling

Atopic dermatitis (AD) is a long-lasting inflammatory skin disease that contributes to the global health burden and impacts 10–20% of the world’s population. In this study, we determined the anti-AD effect of a by-product of silkworm (Bombyx mori) larval powder, strain Yeonnokjam (SLPY), as a sustainable, natural source for the development of therapeutic agents for AD. HaCaT cells were used to assess the in vitro anti-inflammatory activity of SLPY, and a 1-chloro-2,4-dinitrobenzene (DNCB)-induced mouse model was used to study the in vivo anti-AD effects. SLPY treatment downregulated the expression of the inflammatory cytokines TNF-α, IL1β, IL-8, and Cox-2 in stimulated HaCaT cells. Similarly, the topical application of SLPY in DNCB-treated mice downregulated the expression of inflammatory cytokines and proteins while ameliorating the clinical features of AD. Further, SLPY treatment inhibited the nuclear translocation of NF-κb p65, thereby supporting the efficacy of SLPY in the treatment of AD.

The Effects of Mucopolysaccharide Polysulfate on Steroid-Induced Tight Junction Barrier Dysfunction in Human Epidermal Keratinocytes and a 3D Skin Model

INTRODUCTION

The long-term use of topical corticosteroids (TCS) is associated with side effects such as skin atrophy and barrier deterioration. Moisturizers, such as mucopolysaccharide polysulfate (MPS), have been reported to prevent relapses in atopic dermatitis (AD) when used in combination with TCS. However, the mechanisms underlying the positive effects of MPS in combination with TCS in AD are poorly understood. In the present study, we investigated the effects of MPS in combination with clobetasol 17-propionate (CP) on tight junction (TJ) barrier function in human epidermal keratinocytes (HEKa) and 3D skin models.

METHODS

The expression of claudin-1, which is crucial for TJ barrier function in keratinocytes, and transepithelial electrical resistance (TEER) was measured in CP-treated human keratinocytes incubated with and without MPS. A TJ permeability assay, using Sulfo-NHS-Biotin as a tracer, was also conducted in a 3D skin model.

RESULTS

CP reduced claudin-1 expression and TEER in human keratinocytes, whereas MPS inhibited these CP-induced effects. Moreover, MPS inhibited the increase in CP-induced TJ permeability in a 3D skin model.

CONCLUSION

The present study demonstrated that MPS improved TJ barrier impairment induced by CP. The improvement of TJ barrier function may partially be responsible for the delayed relapse of AD induced by the combination of MPS and TCS.