There is no known treatment for the dry form of an age-related macular degeneration (AMD). Cell death and inflammation are important biological processes thought to have central role in AMD. Here we show that receptor-interacting protein (RIP) kinase mediates necrosis and enhances inflammation in a mouse model of retinal degeneration induced by dsRNA, a component of drusen in AMD. In contrast to photoreceptor-induced apoptosis, subretinal injection of the dsRNA analog poly(I : C) caused necrosis of the retinal pigment epithelium (RPE), as well as macrophage infiltration into the outer retinas. In Rip3 À / À mice, both necrosis and inflammation were prevented, providing substantial protection against poly(I : C)-induced retinal degeneration. Moreover, after poly(I : C) injection, Rip3 À / À mice displayed decreased levels of pro-inflammatory cytokines (such as TNF-a and IL-6) in the retina, and attenuated intravitreal release of high-mobility group box-1 (HMGB1), a major damage-associated molecular pattern (DAMP). In vitro, poly(I : C)-induced necrosis were inhibited in Rip3-deficient RPE cells, which in turn suppressed HMGB1 release and dampened TNF-a and IL-6 induction evoked by necrotic supernatants. On the other hand, Rip3 deficiency did not modulate directly TNF-a and IL-6 production after poly(I : C) stimulation in RPE cells or macrophages. Therefore, programmed necrosis is crucial in dsRNA-induced retinal degeneration and may promote inflammation by regulating the release of intracellular DAMPs, suggesting novel therapeutic targets for diseases such as AMD.

Detachment of photoreceptors from the retinal pigment epithelium is seen in various retinal disorders, resulting in photoreceptor death and subsequent vision loss. Cell death results in the release of endogenous molecules that activate molecular platforms containing caspase-1, termed inflammasomes. Inflammasome activation in retinal diseases has been reported in some cases to be protective and in others to be detrimental, causing neuronal cell death. Moreover, the cellular source of inflammasomes in retinal disorders is not clear. Here, we demonstrate that patients with photoreceptor injury by retinal detachment (RD) have increased levels of cleaved IL-1β, an end product of inflammasome activation. In an animal model of RD, photoreceptor cell death led to activation of endogenous inflammasomes, and this activation was diminished by Rip3 deletion. The major source of Il1b expression was found to be infiltrating macrophages in the subretinal space, rather than dying photoreceptors. Inflammasome inhibition attenuated photoreceptor death after RD. Our data implicate the infiltrating macrophages as a source of damaging inflammasomes after photoreceptor detachment in a RIP3-dependent manner and suggest a novel therapeutic target for treatment of retinal diseases.

The role of intestinal bacteria in induction and repression of ulcer formation in the ileum of rats treated with one of the nonsteroidal antiinflammatory drugs (NSAIDs), 5-bromo-2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl) thiophene (BFMeT), was examined in this study. BFMeT was administered by intragastric gavage once at doses of 500-1,500 mg/kg of body weight to Wistar rats treated with and without antibiotics (bacitracin, neomycin, streptomycin), germ-free rats and gnotobiotic rats, and 72 hr later their gastrointestinal tracts were examined for ulcer formation. A single oral administration of BFMeT induced ileal ulcers in specific pathogen-free rats. However, the rats given antibiotics to reduce the intestinal bacteria had no ulcers. BFMeT-treated germ-free rats and gnotobiotic rats mono-associated with Bifidobacterium adolescentis or Lactobacillus acidophilus also had no intestinal ulcers. However, the drug induced ileal ulcers in gnotobiotic rats mono-associated with Eubacterium limosum or Escherichia coli. An overnight culture of B. adolescentis or L. acidophilus or yogurt containing Bifidobacterium breve and Streptococcus thermophilus, when given as drinking water, inhibited ulcer formation in the ileum of rats treated with BFMeT. Gram staining of the ileal contents of normal rats revealed that 97.4% of the stained microorganisms were Gram-positive rods and only 1.2 % were Gram-negative rods. In the group of rats with ulcers induced by BFMeT, the Gram-positive rods decreased by 56.4% and the Gram-negative rods including Escherichia coli, Klebsiella, Proteus and Bacteroides increased by 37.3%. However, in the group of rats administered the Bifidobacterium culture, the Lactobacillus culture or yogurt, the percentages of the Gram-negative rods were decreased. Although Lactobacillus was a major bacterium in the ileum of normal rats, the Gram-negative facultatively anaerobic rods E. coli, Klebsiella and Proteus were increased in the ulcerated ileum of rats treated with BFMeT, suggesting that these bacteria are associated with ulcer formation in rats treated with NSAIDs, and that Lactobacillus and Bifidobacterium inhibit it by repressing the growth of ulcer-inducing bacteria.

: The role of the intestinal microbiota in human health is gaining more attention since clear changes in the composition of the intestinal bacteria or environment are seen in patients with inflammatory bowel disease, allergy, autoimmune disease, and some lifestyle-related illnesses. A healthy gut environment is regulated by the exquisite balance of intestinal microbiota, metabolites, and the host's immune system. Imbalance of these factors in genetically susceptible persons may promote a disease state. Manipulation of the intestinal microbiota with prebiotics, which can selectively stimulate growth of beneficial bacteria, might help to maintain a healthy intestinal environment or improve diseased one. In this review, analytical methods for identification of intestinal bacteria and an update on the correlation of the intestinal microbiota with human health and disease were discussed by introducing our recent studies to determine the prebiotic effects of a fiber-rich food in animal model and on healthy people and patients with ulcerative colitis (UC).

Photoreceptor cell death after RD was significantly different among the three strains, suggesting the presence of genetic factors that affect photoreceptor cell death after RD.

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We examined the antitumour effect of a combination of betulinic acid (BA) and vincristine (VCR) on murine melanoma B16F10 cells in vitro and in vivo. Betulinic acid, a pentacyclic triterpene, showed a synergistic cytotoxic effect on melanoma cells by combinational use of VCR. Betulinic acid and VCR induced cell cycle arrest at different points (BA at G1 phase and VCR at G2/M phase) and caused apoptosis in B16F10 melanoma cells. In the in vivo study, VCR inhibited metastasis of tumour cells to the lung. The addition of BA to VCR augmented suppression of the experimental lung metastasis of melanoma cells in C57BL/6 mice. The number of lung nodules of more than 1 mm in diameter in mice treated with BA and VCR was less than that in mice treated with VCR alone. These results suggest that BA is an effective supplement for enhancing the chemotherapeutic effect on malignant melanoma.

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