Cellulose nanocrystal preparation from Gelidium amansii and analysis of its anti-inflammatory effect on the skin in vitro and in vivo

Treated Gelidium amansii cellulose nanocrystal (TGa CNC) was prepared from treated Gelidium amansii (TGa) and evaluated for its anti-inflammatory effect on human keratinocytes and mice skin. Using three independent cell lines, TGa CNC showed no cytotoxicity in HaCaT, Beas-2B, and Raw 264.7 cells. A non-toxic dose of TGa CNC suppressed ultraviolet (UV) B-induced AP (activated protein)-1, and subsequent cyclooxygenase (COX)-2 gene and protein expression in HaCaT cells. TGa CNC suppressed translocation of c-Jun from the cytosol to the nucleus responds to UVB irradiation. Additionally, TGa CNC suppressed UVB-induced extracellular signal-regulated kinases (ERKs)1/2/MEK/2/B-Raf, c-Jun N-terminal kinase (JNK)1/2/MKK4/7, Akt, and epidermal growth factor receptor (EGFR) phosphorylation in HaCaT cells. Dorsal treatment of TGa CNC significantly suppressed acute UVB-induced increase in epidermal thickness and COX-2 expression in mice skin. Overall, these results indicate that TGa CNC exerts potent anti-inflammatory activity through the inhibition of abnormal COX-2 expression and mitogen-activated protein kinases (MAPK)s signaling pathways.

Let-7b and miR-495 stimulate differentiation and prevent metaplasia of pancreatic acinar cells by repressing HNF6

BACKGROUND & AIMS

Diseases of the exocrine pancreas are often associated with perturbed differentiation of acinar cells. MicroRNAs (miRNAs) regulate pancreas development, yet little is known about their contribution to acinar cell differentiation. We aimed to identify miRNAs that promote and control the maintenance of acinar differentiation.

METHODS

We studied mice with pancreas- or acinar-specific inactivation of Dicer (Foxa3-Cre/Dicer(loxP/-) mice), combined (or not) with inactivation of hepatocyte nuclear factor (HNF) 6 (Foxa3-Cre/Dicer(loxP/-)/Hnf6-/- mice). The role of specific miRNAs in acinar differentiation was investigated by transfecting cultured cells with miRNA mimics or inhibitors. Pancreatitis-induced metaplasia was investigated in mice after administration of cerulein.

RESULTS

Inhibition of miRNA synthesis in acini by inactivation of Dicer and pancreatitis-induced metaplasia were associated with repression of acinar differentiation and with induction of HNF6 and hepatic genes. The phenotype of Dicer-deficient acini depends on the induction of HNF6; overexpression of this factor in developing acinar cells is sufficient to repress acinar differentiation and to induce hepatic genes. Let-7b and miR-495 repress HNF6 and are expressed in developing acini. Their expression is inhibited in Dicer-deficient acini, as well as in pancreatitis-induced metaplasia. In addition, inhibiting let-7b and miR-495 in acinar cells results in similar effects to those found in Dicer-deficient acini and metaplastic cells, namely induction of HNF6 and hepatic genes and repression of acinar differentiation.

CONCLUSIONS

Let-7b, miR-495, and their targets constitute a gene network that is required to establish and maintain pancreatic acinar cell differentiation. Additional studies of this network will increase our understanding of pancreatic diseases.