In this work, we studied whether chondroitin sulfates and dextran sulfates (DXSs) can influence hypochlorite-induced peroxidation of phosphatidylcholine (PC) liposomes. Multilamellar liposomes (2 mg lipid/ml) were prepared in phosphate buffer, pH 7.4, with NaCl or not and exposed to reagent HOCl/ClO- (1mM) at 37 degrees C in the presence of different concentrations of chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), DXS 8000, DXS 40,000, and DXS 500,000. Lipid peroxidation was assessed by thiobarbituric acid-reactive substance (TBARS) production. DXSs and C6S enhanced TBARS production in a dose-dependent manner. The decline in TBARS production at the relatively high C6S concentrations may be attributed to C4S present in C6S, since in contrast to C6S, C4S is known to react with hypochlorite. Dextrans, nonsulfated analogues of DXS, failed to modulate TBARS production. This fact indicates the important role of negatively charged sulfate groups for DXS to facilitate hypochlorite-induced peroxidation of PC liposomes. The electrostatic nature of the mechanism providing for the pro-oxidative effect of DXS was also supported by the influence of liposome surface charge and solution ionic strength on the extent of liposome peroxidation. The addition of calcium ions to the incubation mixture did not prevent the pro-oxidative action of DXS. The relevance of the results to atherogenesis is discussed.
Chitosan (CS) nanoparticles have been extensively studied for siRNA delivery; however, their stability and efficacy are highly dependent on the types of cross-linker used. To address this issue, three common cross-linkers; tripolyphosphate (TPP), dextran sulphate (DS) and poly-D-glutamic acid (PGA) were used to prepare siRNA loaded CS-TPP/DS/PGA nanoparticles by ionic gelation method. The resulting nanoparticles were compared with regard to their physicochemical properties including particle size, zeta potential, morphology, binding and encapsulation efficiencies. Among all the formulations prepared with different cross linkers, CS-TPP-siRNA had the smallest particle size (ranged from 127 ± 9.7 to 455 ± 12.9 nm) with zeta potential ranged from +25.1 ± 1.5 to +39.4 ± 0.5 mV, and high entrapment (>95%) and binding efficiencies. Similarly, CS-TPP nanoparticles showed better siRNA protection during storage at 4˚C and as determined by serum protection assay. TEM micrographs revealed the assorted morphology of CS-TPP-siRNA nanoparticles in contrast to irregular morphology displayed by CS-DS-siRNA and CS-PGA-siRNA nanoparticles. All siRNA loaded CS-TPP/DS/PGA nanoparticles showed initial burst release followed by sustained release of siRNA. Moreover, all the formulations showed low and concentration-dependent cytotoxicity with human colorectal cancer cells (DLD-1), in vitro. The cellular uptake studies with CS-TPP-siRNA nanoparticles showed successful delivery of siRNA within cytoplasm of DLD-1 cells. The results demonstrate that ionically cross-linked CS-TPP nanoparticles are biocompatible non-viral gene delivery system and generate a solid ground for further optimization studies, for example with regard to steric stabilization and targeting.
Patients with inflammatory bowel disease (IBD) are at increased risk for developing ulcerative colitis-associated colorectal cancer (CRC). The interleukin-6 (IL-6)/signal transducer and activator of transcription (STAT)-3 signaling regulates survival and proliferation of intestinal epithelial cells and play an important role in the pathogenesis of IBD and CRC. Cocoa is enriched with polyphenols that known to possess antioxidant, anti-inflammatory and antitumor activities. Here, we explored the antitumor effects and mechanisms of cocoa diet on colitis-associated cancer (CAC) using the azoxymethane/dextran sulfate sodium model, with a particular focus on whether cocoa exerts its anticancer effect through the IL-6/STAT3 pathway. We found that cocoa significantly decreased the tumor incidence and size in CAC-induced mice. In addition to inhibiting proliferation of tumor epithelial cells, cocoa suppressed colonic IL-6 expression and subsequently activation of STAT3. Thus, our findings demonstrated that cocoa diet suppresses CAC tumorigenesis, and its antitumor effect is partly mediated by limiting IL-6/STAT3 activation. In addition, cocoa induces apoptosis by increased the expressions of Bax and caspase 3 and decreased Bcl-xl. Thus, we conclude that cocoa may be a potential agent in the prevention and treatment of CAC.
Gallic acid (GA) is a polyhydroxy phenolic compound that has been detected in various natural products, such as green tea, strawberries, grapes, bananas, and many other fruits. In inflammatory bowel disease, inflammation is promoted by oxidative stress. GA is a strong antioxidant; thus, we evaluated the cytoprotective and anti-inflammatory role of GA in a dextran sulfate sodium (DSS)-induced mouse colitis model. Experimental acute colitis was induced in male BALB/c mice by administering 2.5% DSS in the drinking water for 7 days. The disease activity index; colon weight/length ratio; histopathological analysis; mRNA expressions of IL-21 and IL-23; and protein expression of nuclear erythroid 2-related factor 2 (Nrf2) were compared between the control and experimental mice. The colonic content of malondialdehyde and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activity were examined as parameters of the redox state. We determined that GA significantly attenuated the disease activity index and colon shortening, and reduced the histopathological evidence of injury. GA also significantly (P<0.05) reduced the expressions of IL-21 and IL-23. Furthermore, GA activates/upregulates the expression of Nrf2 and its downstream targets, including UDP-GT and NQO1, in DSS-induced mice. The findings of this study demonstrate the protective effect of GA on experimental colitis, which is probably due to an antioxidant nature of GA.
The objective of this study is to evaluate the effect of allicin (10 mg/kg body weight, orally) in an experimental murine model of UC by administering 2.5% dextran sodium sulfate (DSS) in drinking water to BALB/c mice. DSS-induced mice presented reduced body weight, which was improved by allicin administration. We noted increases in CD68 expression, myeloperoxidase (MPO) activities, and Malonaldehyde (MDA) and mRNA levels of proinflammatory cytokines, such as tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and IL-17, and decrease in the activities of enzymic antioxidants such as superoxide dismutase (SOD), Catalase (CAT), Glutathione reductase (GR), and Glutathione peroxidase (GPx) in DSS-induced mice. However, allicin treatment significantly decreased CD68, MPO, MDA, and proinflammatory cytokines and increased the enzymic antioxidants significantly (P < 0.05). In addition, allicin was capable of reducing the activation and nuclear accumulation of signal transducer and activator of transcription 3 (STAT3), thereby preventing degradation of the inhibitory protein IκB and inducing inhibition of the nuclear translocation of nuclear factor (NF)-κB-p65 in the colonic mucosa. These findings suggest that allicin exerts clinically useful anti-inflammatory effects mediated through the suppression of the NF-κB and IL-6/p-STAT3(Y705) pathways.
Colorectal cancer is the third leading cause of cancer-related deaths in the United States and the third most common cancer in men and women. Around 20% colon cancer cases are closely linked with colitis. Both environmental and genetic factors are thought to contribute to colon inflammation and tumor development. However, the genetic factors regulating colitis and colon tumorigenesis remain elusive. Since reactive oxygen species (ROS) is vitally involved in tissue inflammation and tumorigenesis, here we employed a genome-wide CRISPR knockout screening approach to systemically identify the genetic factors involved in the regulation of oxidative stress. Next generation sequencing (NGS) showed that over 600 gRNAs including the ones targeting LGALS2 were highly enriched in cells survived after sublethal H2O2 challenge. LGALS2 encodes the glycan-binding protein Galectin 2 (Gal2), which is predominantly expressed in the gastrointestinal tract and downregulated in human colon tumors. To examine the role of Gal2 in colitis, we employed the dextran sodium sulfate (DSS)-induced acute colitis model in mice with (WT) or without Lgals2 (Gal2-KO) and showed that Gal2 deficiency ameliorated DSS-induced colitis. We further demonstrated that Gal2-KO mice developed significantly larger tumors than WT mice using Azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colorectal cancer model. We found that STAT3 phosphorylation was significantly increased in Gal2-deficient tumors as compared to those in WT mice. Gal2 overexpression decreased the proliferation of human colon tumor epithelial cells and blunted H2O2-induced STAT3 phosphorylation. Overall, our results demonstrate that Gal2 plays a suppressive role in colon tumor growth and highlights the therapeutic potential of Gal2 in colon cancer.
Inflammatory bowel diseases (IBD), such as ulcerative colitis and Crohn's disease, are an important cause of morbidity and impact significantly on quality of life. Overall, current treatments do not sustain a long-term clinical remission and are associated with adverse effects, which highlight the need for new treatment options. Fucoidans are complex sulphated, fucose-rich polysaccharides, found in edible brown algae and are described as having multiple bioactivities including potent anti-inflammatory effects. Therefore, the therapeutic potential of two different fucoidan preparations, fucoidan-polyphenol complex (Maritech Synergy) and depyrogenated fucoidan (DPF) was evaluated in the dextran sulphate sodium (DSS) mouse model of acute colitis. Mice were treated once daily over 7 days with fucoidans via oral (Synergy or DPF) or intraperitoneal administration (DPF). Signs and severity of colitis were monitored daily before colons and spleens were collected for macroscopic evaluation, cytokine measurements and histology. Orally administered Synergy and DPF, but not intraperitoneal DPF treatment, significantly ameliorated symptoms of colitis based on retention of body weight, as well as reduced diarrhoea and faecal blood loss, compared to the untreated colitis group. Colon and spleen weight in mice treated with oral fucoidan was also significantly lower, indicating reduced inflammation and oedema. Histological examination of untreated colitis mice confirmed a massive loss of crypt architecture and goblet cells, infiltration of immune cells and oedema, while all aspects of this pathology were alleviated by oral fucoidan. Importantly, in this model, the macroscopic changes induced by oral fucoidan correlated significantly with substantially decreased production of at least 15 pro-inflammatory cytokines by the colon tissue. Overall, oral fucoidan preparations significantly reduce the inflammatory pathology associated with DSS-induced colitis and could therefore represent a novel nutraceutical option for the management of IBD.
Inflammatory bowel diseases, such as ulcerative colitis, cause significant morbidity and decreased quality of life. The currently available treatments are not effective in all patients, can be expensive and have potential to cause severe side effects. This prompts the need for new treatment modalities. Enoxaparin, a widely used antithrombotic agent, is reported to possess anti-inflammatory properties and therefore we evaluated its therapeutic potential in a mouse model of colitis. Acute colitis was induced in male C57BL/6 mice by administration of dextran sulfate sodium (DSS). Mice were treated once daily with enoxaparin via oral or intraperitoneal administration and monitored for colitis activities. On termination (day 8), colons were collected for macroscopic evaluation and cytokine measurement, and processed for histology and immunohistochemistry. Oral but not intraperitoneal administration of enoxaparin significantly ameliorated DSS-induced colitis. Oral enoxaparin-treated mice retained their body weight and displayed less diarrhea and fecal blood loss compared to the untreated colitis group. Colon weight in enoxaparin-treated mice was significantly lower, indicating reduced inflammation and edema. Histological examination of untreated colitis mice showed a massive loss of crypt architecture and goblet cells, infiltration of immune cells and the presence of edema, while all aspects of this pathology were alleviated by oral enoxaparin. Reduced number of macrophages in the colon of oral enoxaparin-treated mice was accompanied by decreased levels of pro-inflammatory cytokines. Oral enoxaparin significantly reduces the inflammatory pathology associated with DSS-induced colitis in mice and could therefore represent a novel therapeutic option for the management of ulcerative colitis.
Inflammation and compromised immune responses often increase colorectal cancer (CRC) risk. The immune-modulating effects of limonin on carcinogen/inflammation-induced colorectal cancer (CRC) were studied in mice. Male Balb/c mice were randomly assorted into three groups (n = 6): healthy control, non-treated CRC-induced (azoxymethane/dextran-sulfate-sodium AOM/DSS) control, and CRC-induced + 50 mg limonin/kg body weight. The CRC developments were monitored via macroscopic, histopathological, ELISA, and mRNA expression analyses. Limonin downregulated inflammation (TNF-α, tumor necrosis factor-α), enhanced the adaptive immune responses (CD8, CD4, and CD19), and upregulated antioxidant defense (Nrf2, SOD2) mRNA expressions. Limonin reduced serum malondialdehyde (MDA, lipid peroxidation biomarker), prostaglandin E2, and histopathology inflammation scores, while increasing reduced glutathione (GSH) in CRC-induced mice. Limonin significantly (p
Zika virus (ZIKV) is an arthropod-borne flavivirus that causes newborn microcephaly and Guillian-Barré syndrome in adults. No therapeutics are available to treat ZIKV infection or other flaviviruses. In this study, we explored the inhibitory effect of glycosaminoglycans and analogues against ZIKV infection. Highly sulfated heparin, dextran sulfate and suramin significantly inhibited ZIKV infection in Vero cells. De-sulfated heparin analogues lose inhibitory effect, implying that sulfonate groups are critical for viral inhibition. Suramin, an FDA-approved anti-parasitic drug, inhibits ZIKV infection with 3-5 log10 PFU viral reduction with IC50value of ∼2.5-5 μg/ml (1.93 μM-3.85 μM). A time-of-drug-addition study revealed that suramin remains potent even when administrated at 1-24 hpi. Suramin inhibits ZIKV infection by preventing viral adsorption, entry and replication. Molecular dynamics simulation revealed stronger interaction of suramin with ZIKV NS3 helicase than with the envelope protein. Suramin warrants further investigation as a potential antiviral candidate for ZIKV infection. Heparan sulfate (HS) is a cellular attachment receptor for multiple flaviviruses. However, no direct ZIKV-heparin interaction was observed in heparin-binding analysis, and downregulate or removal of cellular HS with sodium chlorate or heparinase I/III did not inhibit ZIKV infection. This indicates that cell surface HS is not utilized by ZIKV as an attachment receptor.
Colorectal cancer (CRC) is the third most common malignancy in males and the second most common cancer worldwide. Chronic colonic inflammation is a known risk factor for CRC. Cocoa contains many polyphenolic compounds that have beneficial effects in humans. The objective of this study is to explore the antioxidant properties of cocoa in the mouse model of azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis-associated cancer, focusing on the activation of Nrf2 signaling. Mice were treated with AOM/DSS and randomized to receive either a control diet or a 5 and 10% cocoa diet during the study period. On day 62 of the experiment, the entire colon was processed for biochemical and histopathological examination and further evaluations. Increased levels of malondialdehyde (MDA) were observed in AOM/DSS-induced mice; however, subsequent administration of cocoa decreased the MDA. Enzymatic and nonenzymatic antioxidants, such as superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, were decreased in the AOM/DSS mice. Cocoa treatment increases the activities/levels of enzymatic and nonenzymatic antioxidants. Inflammatory mediators, such as inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, were elevated during AOM/DSS-induction, and treatment with 5 and 10% cocoa effectively decreases the expression of iNOS and COX-2. The NF-E2-related factor 2 and its downstream targets, such as NQO1 and UDP-GT, were increased by cocoa treatment. The results of our study suggest that cocoa may merit further clinical investigation as a chemopreventive agent that helps prevent CAC.