A Role for Neuronal Alpha-Synuclein in Gastrointestinal Immunity.

BACKGROUND: Alpha-synuclein (αS) is a nerve cell protein associated with Parkinson disease (PD). Accumulation of αS within the enteric nervous system (ENS) and its traffic from the gut to the brain are implicated in the pathogenesis and progression of PD. αS has no known function in humans and the reason for its accumulation within the ENS is unknown. Several recent studies conducted in rodents have linked αS to immune cell activation in the central nervous system. We hypothesized that αS in the ENS might play a role in the innate immune defenses of the human gastrointestinal (GI) tract. METHODS: We immunostained endoscopic biopsies for αS from children with documented gastric and duodenal inflammation and intestinal allograft recipients who contracted norovirus. To determine whether αS exhibited immune-modulatory activity, we examined whether human αS induced leukocyte migration and dendritic cell maturation. FINDINGS: We showed that the expression of αS in the enteric neurites of the upper GI tract of pediatric patients positively correlated with the degree of acute and chronic inflammation in the intestinal wall. In intestinal allograft subjects who were closely monitored for infection, expression of αS was induced during norovirus infection. We also demonstrated that both monomeric and oligomeric αS have potent chemoattractant activity, causing the migration of neutrophils and monocytes dependent on the presence of the integrin subunit, CD11b, and that both forms of αS stimulate dendritic cell maturation. INTERPRETATION: These findings strongly suggest that αS is expressed within the human ENS to direct intestinal inflammation and implicates common GI infections in the pathogenesis of PD.

Nucleotide excision repair deficiency increases levels of acrolein-derived cyclic DNA adduct and sensitizes cells to apoptosis induced by docosahexaenoic acid and acrolein.

The acrolein derived cyclic 1,N(2)-propanodeoxyguanosine adduct (Acr-dG), formed primarily from ω-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA) under oxidative conditions, while proven to be mutagenic, is potentially involved in DHA-induced apoptosis. The latter may contribute to the chemopreventive effects of DHA. Previous studies have shown that the levels of Acr-dG are correlated with apoptosis induction in HT29 cells treated with DHA. Because Acr-dG is shown to be repaired by the nucleotide excision repair (NER) pathway, to further investigate the role of Acr-dG in apoptosis, in this study, NER-deficient XPA and its isogenic NER-proficient XAN1 cells were treated with DHA. The Acr-dG levels and apoptosis were sharply increased in XPA cells, but not in XAN1 cells when treated with 125µM of DHA. Because DHA can induce formation of various DNA damage, to specifically investigate the role of Acr-dG in apoptosis induction, we treated XPA knockdown HCT116+ch3 cells with acrolein. The levels of both Acr-dG and apoptosis induction increased significantly in the XPA knockdown cells. These results clearly demonstrate that NER deficiency induces higher levels of Acr-dG in cells treated with DHA or acrolein and sensitizes cells to undergo apoptosis in a correlative manner. Collectively, these results support that Acr-dG, a ubiquitously formed mutagenic oxidative DNA adduct, plays a role in DHA-induced apoptosis and suggest that it could serve as a biomarker for the cancer preventive effects of DHA.

Antioxidative effects of the spice cardamom against non-melanoma skin cancer by modulating nuclear factor erythroid-2-related factor 2 and NF-κB signalling pathways.

The role of dietary factors in inhibiting or delaying the development of non-melanoma skin cancer (NMSC) has been investigated for many years. Cardamom, which is a dietary phytoproduct, has been commonly used in cuisines for flavour and has numerous health benefits, such as improving digestion and stimulating metabolism and having antitumorigenic effects. We have investigated the efficacy of dietary cardamom against 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin papillomatogenesis in Swiss albino mice that closely resembles human NMSC. Mice were grouped into normal wild type (untreated), vehicle-treated (acetone), carcinogen-treated (DMBA), and DMBA and cardamom-treated (DMBA+CARD) to delineate the role of cardamom against DMBA-induced papillomatogenesis. Oral administration of cardamom to DMBA-treated mice up-regulated the phase II detoxification enzymes, such as glutathione-S-transferase and glutathione peroxidase, probably via activation of nuclear factor erythroid-2-related factor 2 transcription factor in 'DMBA+CARD' mice. Furthermore, reduced glutathione, glutathione reductase, superoxide dismutase and catalase were also up-regulated by cardamom in the same 'DMBA+CARD' group of mice compared with DMBA-treated mice. Cardamom ingestion in DMBA-treated mice blocked NF-κB activation and down-regulated cyclo-oxygenase-2 expression. As a consequence, both the size and the number of skin papillomas generated on the skin due to the DMBA treatment were reduced in the 'DMBA+CARD' group. Thus, the results from the present study suggest that cardamom has a potential to become a pivotal chemopreventive agent to prevent papillomagenesis on the skin.

Identification of novel substrates for the serine protease HTRA1 in the human RPE secretome.

PURPOSE. To define the role of the serine protease HTRA1 in age-related macular degeneration (AMD) by examining its expression level and identifying its potential substrates in the context of primary RPE cell extracellular milieu. METHODS. Primary RPE cell cultures were established from human donor eyes and screened for CFH, ARMS2, and HTRA1 risk genotypes by using an allele-discrimination assay. HTRA1 expression in genotyped RPE cells was determined by using real-time PCR and quantitative proteomics. Potential HTRA1 substrates were identified by incubating RPE-conditioned medium with or without human recombinant HTRA1. Selectively cleaved proteins were quantified by using the differential stable isotope labeling by amino acids in cell culture (SILAC) strategy. RESULTS. HTRA1 mRNA levels were threefold higher in primary RPE cells homozygous for the HTRA1 promoter risk allele than in RPE cells with the wild-type allele, which translated into a twofold increase in HTRA1 secretion by RPE cells with the risk genotype. A total of 196 extracellular proteins were identified in the RPE secretome, and only 8 were found to be selectively cleaved by the human recombinant HTRA1. These include fibromodulin with 90% cleavage, clusterin (50%), ADAM9 (54%), vitronectin (54%), and alpha2-macroglobulin (55%), as well as some cell surface proteins including talin-1 (21%), fascin (40%), and chloride intracellular channel protein 1 (51%). CONCLUSIONS. Recombinant HTRA1 cleaves RPE-secreted proteins involved in regulation of the complement pathway (clusterin, vitronectin, and fibromodulin) and of amyloid deposition (clusterin, alpha2-macroglobulin, and ADAM9). These findings suggest a link between HTRA1, complement regulation, and amyloid deposition in AMD pathogenesis.