Inhibitory Effects of Polyphenol- and Flavonoid-Enriched Rice Seed Extract on Melanogenesis in Melan-a Cells via MAPK Signaling-Mediated MITF Downregulation.

Melanin production is an important process that prevents the host skin from harmful ultraviolet radiation; however, an overproduction of melanin results in skin diseases. In the present study, we determined the antioxidative and anti-melanogenic activities of polyphenol- and flavonoid-enriched rice seed extracts in melan-a cells. The polyphenol and flavonoid content of Hopum (HP) and Sebok (SB) rice seed extracts was measured. The antioxidant capacity was determined using the ABTS radical scavenging method. SB contained high amounts of polyphenols and flavonoids, which significantly increased antioxidative activity compared with HP. Various concentrations of these extracts were evaluated in a cytotoxicity using melan-a cells. At 100 µg/mL, there was no significant difference for all treatments compared with untreated cells. Therefore, 100 µg/mL was selected as a concentration for the further experiments. SB significantly suppressed the phosphorylation/activation of p-38 MAPK, increased the expression of phosphorylated ERK 1/2 and Akt, and downregulated the microphthalmia-associated transcription factor (MITF). This resulted in decreased levels of tyrosinase and tyrosinase-related protein-1 and -2. These results indicate the potential of polyphenol- and flavonoid-enriched rice seed as a treatment for hyperpigmentation.

Cationic Nanoliposomes Are Efficiently Taken up by Alveolar Macrophages but Have Little Access to Dendritic Cells and Interstitial Macrophages in the Normal and CpG-Stimulated Lungs.

The purpose of this study was to assess whether cationic nanoliposomes could address tumor vaccines to dendritic cells in the lungs in vivo. Nanoliposomes were prepared using a cationic lipid, dimethylaminoethanecarbamoyl-cholesterol (DC-cholesterol) or dioleoyltrimethylammoniumpropane (DOTAP), and dipalmitoylphosphatidylcholine (DPPC), the most abundant phospholipid in lung surfactant. The liposomes presented a size below 175 nm and they effectively entrapped tumor antigens, an oligodeoxynucletotide containing CpG motifs (CpG) and the fluorescent dye calcein used as a tracer. Although the liposomes could permanently entrap a large fraction of the actives, they could not sustain their release in vitro. Liposomes made of DOTAP were safe to respiratory cells in vitro, while liposomes composed of DC-cholesterol were cytotoxic. DOTAP nanoliposomes were mainly taken up by alveolar macrophages following delivery to the lungs in mice. Few dendritic cells took up the liposomes, and interstitial macrophages did not take up liposomal calcein more than they took up soluble calcein. Stimulation of the innate immune system using liposomal CpG strongly enhanced uptake of calcein liposomes by all phagocytes in the lungs. Although a small percentage of dendritic cells took up the nanoliposomes, alveolar macrophages represented a major barrier to dendritic cell access in the lungs.

Artificial human antigen-presenting cells are superior to dendritic cells at inducing cytotoxic T-cell responses.

Peptide recognition through the MHC class I molecule by cytotoxic T lymphocytes (CTLs) leads to the killing of cancer cells. A potential challenge for T-cell immunotherapy is that dendritic cells (DCs) are exposed to the MHC class I-peptide complex for an insufficient amount of time. To improve tumour antigen presentation to T cells and thereby initiate a more effective T-cell response, we generated artificial antigen-presenting cells (aAPCs) by incubating human immature DCs (imDCs) with poly(lactic-co-glycolic) acid nanoparticles (PLGA-NPs) encapsulating tumour antigenic peptides, followed by maturation with lipopolysaccharide. Tumour antigen-specific CTLs were then induced using either peptide-loaded mature DCs (mDCs) or aAPCs, and their activities were analysed using both ELISpot and cytotoxicity assays. We found that the aAPCs induced significantly stronger tumour antigen-specific CTL responses than the controls, which included both mDCs and aAPCs loaded with empty nanoparticles. Moreover, frozen CTLs that were generated by exposure to aAPCs retained the capability to eradicate HLA-A2-positive tumour antigen-bearing cancer cells. These results indicated that aAPCs are superior to DCs when inducing the CTL response because the former are capable of continuously presenting tumour antigens to T cells in a sustained manner. The development of aAPCs with PLGA-NPs encapsulating tumour antigenic peptides is a promising approach for the generation of effective CTL responses in vitro and warrants further assessments in clinical trials.

Circulating CD4+ T cells that produce IL4 or IL17 when stimulated by melan-A but not by NY-ESO-1 have negative impacts on survival of patients with stage IV melanoma.

PURPOSE: We initially observed that the presence of circulating NY-ESO-1- and/or Melan-A-specific T cells in patients with stage IV melanoma was significantly associated with prolonged survival. Here, we report the ways in which the phenotypes and functions of these T cells differentially affect survival in patients preselected for NY-ESO-1 and/or Melan-A reactivity. EXPERIMENTAL DESIGN: We assayed functional antigen-reactive T cells recognizing NY-ESO-1 and/or Melan-A after in vitro stimulation using overlapping peptide pools. After restimulation, we assayed six cytokines simultaneously by intracellular cytokine staining. This allowed us to analyze the functional antigen response of both CD4(+) and CD8(+) T cells at the single-cell level. RESULTS: We observed that NY-ESO-1 stimulated mainly CD4(+) T cells, whereas Melan-A more often stimulated CD8(+) T cells. NY-ESO-1 reactivity was not associated with an additional impact on survival, whether CD4(+) T cells, CD8(+) T cells, or both types of T cells were responding. In contrast, recognition of Melan-A by CD4(+) T cells was associated with reduced survival in our cohort of patients preselected for NY-ESO-1 and/or Melan-A reactivity (that is, in patients with exceptionally long survival). We further observed a negative effect on survival in patients with CD4(+) T cells producing IL4 and IL17 upon Melan-A stimulation. Their prognosis was comparable to patients without any Melan-A reactivity. CONCLUSIONS: The nature and prognostic impact of specific T-cell responses is different according to targeted antigen. Independent from phenotype and functional aspects, NY-ESO-1 reactivity is associated with good prognosis. In terms of Melan-A, antigen-specific CD8(+) but not CD4(+) responses are associated with prolonged survival. Clin Cancer Res; 20(16); 4390-9. ©2014 AACR.