Toxicological evaluation and preliminary exposure assessment on glycerol monocaprylate.

As a commonly used food preservative, glycerol monocaprylate (GMC) has limited information and lacked a comprehensive risk assessment. In this study, we conducted in vitro genotoxicity tests, a 90-day subchronic toxicity study, and dietary exposure assessment in China. Rats (n=10/sex/group) were orally administered GMC at doses of 1.02, 2.04, and 4.08 g/kg BW/day along with a water and corn oil for 90 days, including satellite groups (n =5/sex/group) in the control groups and 4.08 g/kg BW dose group for observation after 90 days. Body weight, food consumption, hematology, serum biochemistry, urinalysis, endocrine hormone level and other metrics were examined. GMC did not exhibit genotoxicity based on the genotoxicity tests results, and an acceptable daily intake (ADI) of 40.8 mg/kg BW/day was established based on the 90-day subchronic toxicity study. Estimated daily intake of GMC for general population and consumer population in China were 0.99 mg/kg BW/day and 3.19 mg/kg BW/day respectively, which were significantly lower than the ADI. Our findings suggest that GMC does not pose a known health risk to Chinese consumers at the current usage level.

Genotoxicity evaluation of food additive titanium dioxide using a battery of standard in vivo tests.

The increasing use of titanium dioxide (TiO2) nanoparticles (NPs) has raised concern about the safety of food additive TiO2. TiO2 has been considered no longer safe by EFSA due to concerns over genotoxicity, however, there are conflicting opinions upon the safety of TiO2 as a food additive, and the number of in vivo genotoxicity studies conducted on food additive TiO2 was limited. In order to investigate the potential genotoxicity of food additive TiO2, we evaluated the genotoxicity of a commercial food additive TiO2 (average size of 135.54 ± 41.01 nm, range from 60.83 to 230.16 nm, NPs account for 30% by number) using a battery of standard in vivo tests, including mammalian erythrocyte micronucleus test, mammalian bone marrow chromosomal aberration test and in vivo mammalian alkaline comet test. After 15 days of consecutive intragastric administration at doses of 250, 500, and 1000 mg/kgBW, food additive TiO2 neither increased the frequencies of bone marrow micronuclei or chromosomal aberration in mice, nor induced DNA strand breakage in rat liver cells. These results indicate that under the condition of this study, food additive TiO2 does not have genotoxic potential although it contains a fraction of NPs.

Toxicokinetics of zinc oxide nanoparticles and food grade bulk-sized zinc oxide in rats after oral dosages.

The increasing application of zinc oxide nanoparticles (ZnO NPs) in consumer products has raised concerns about the potential health risks in human. It is crucial to understand the toxicokinetic information of ZnO NPs, especially the differences between NPs and non-nano form material. This study investigated the toxicokinetic profile of ZnO NPs and food grade bulk-sized ZnO in rats after single or repeated oral dosages. For single oral administration of ZnO suspensions at 350 mg/kgbw, the Zn content in blood and tissues showed no elevation, the majority of ZnO particles were eliminated via feces within 48 h. For repeated oral exposure to ZnO suspensions at 350 mg/kgbw or ZnSO4 solution at 700 mg/kgbw for 90 days, elevated Zn levels were observed in liver, kidney, and bone in all three treatment groups, the Zn level recovered to normal level in liver and kidney, but not in bone, after a recovery period. ZnO NPs and bulk-sized ZnO showed similarity in toxicokinetics in rats, regardless of exposure duration or gender. ZnO particles shared a similar biodistribution profile with ZnSO4, and were likely to be absorbed mostly in ionic forms.

Safety assessment of phytase transgenic maize 11TPY050 in Sprague-Dawley rats by 90-day feeding study.

The present study aimed to evaluate the subchronic toxicity of feeding with phytase-transgenic maize line 11TPY050 in Sprague-Dawley (SD) rats. Rats (n = 10/sex/group) were fed with 12.5%, 25% or 50% (w/w) transgenic maize diet, 12.5%, 25% or 50% (w/w) non-transgenic isoline OSL940 maize diet, or 50% (w/w) commercially available Zhengdan958 maize diet for 90 days. Daily clinical observations and weekly measurements of body weights and food consumption were conducted. Blood samples were collected on day 46 and day 91 for hematology and clinical chemistry evaluations. At the end of the study, macroscopic and microscopic examinations were performed. No effects on body weight and food consumption were observed. The results of hematology, clinical chemistry, and absolute and relative organ weights in the transgenic maize group were comparable to those in the parental maize group. Several statistical differences were not dose-related and were not considered to be biologically significant. Furthermore, the terminal necropsy and histopathological examination showed no treatment-related changes among the groups. The results from the present 90-day feeding study of phytase-transgenic maize 11TPY050 indicated no unexpected adverse effects in SD rats. The phytase transgenic maize 11TPY050 has substantial equivalence with non-transgenic maize.

Safety evaluation of BPL9K-4 rice in a subchronic rodent feeding study.

In the present study, a new genetically modified rice producing phytase-lactoferricin fusion protein, BPL9K-4, was evaluated for safety in a 90-day rat feeding study. Rats were fed rodent diets formulated with BPL9K-4 rice, and were compared with rats fed diets formulated with its corresponding non-transgenic parental rice 9 K, commercially available non-transgenic rice Weiyou64, and a basal diet. BPL9K-4 and 9 K rice were formulated into diets at concentrations of 15%, 30% and 60%, and Weiyou64 common rice was added to diets at concentration of 60%. AIN93G diet was set as a basal-diet control. Diets of all groups were fed to rats (10/sex/group) for 90 days. Compared with rats in the 9 K, Weiyou64 and the basal-diet group, rats fed the BPL9K-4 diet did not show any treatment-related adverse effects on mortality, body weights, feed consumption, clinical chemistry, hematology, organ weights and gross and microscopic pathology. Under the conditions of this study, the genetically modified BPL9K-4 diets did not cause any toxicologically significant effects in rats following 90 days of dietary administration as compared with rats fed diets with the corresponding non-transgenic control diet and the basal-diet group. The results indicated that BPL9K-4 rice is as safe as its conventional comparators.

CCL2-CCR2 axis recruits tumor associated macrophages to induce immune evasion through PD-1 signaling in esophageal carcinogenesis.

BACKGROUND: The poor prognosis of esophageal squamous cell carcinoma (ESCC) highlights the need for novel strategies against this disease. Our previous study suggested the involvement of CCL2 and tumor associated macrophages (TAMs) in esophageal carcinogenesis. Despite the recognition of TAMs as a promising target for cancer treatment, mechanisms underlying its infiltration, activation and tumor-promotive function in ESCC remain unknown. METHODS: Human esophageal tissue array and TCGA database were used to evaluate the clinical relevance of CCL2 and TAMs in ESCC. F344 rats and C57BL/6 mice were treated with N-nitrosomethylbenzylamine (NMBA) to establish orthotopic models of esophageal carcinogenesis. CCL2/CCR2 gene knockout mice and macrophage-specific PPARG gene knockout mice were respectively used to investigate the role of infiltration and polarization of TAMs in ESCC. CCL2-mediated monocyte chemotaxis was estimated in malignantly transformed Het-1A cells. THP-1 cells were used to simulate TAMs polarization in vitro. RNA-sequencing was performed to uncover the mechanism. RESULTS: Increasing expression of CCL2 correlated with TAMs accumulation in esophageal carcinogenesis, and they both predicts poor prognosis in ESCC cohort. Animal studies show blockade of CCL2-CCR2 axis strongly reduces tumor incidence by hindering TAMs recruitment and thereby potentiates the antitumor efficacy of CD8+ T cells in the tumor microenvironment. More importantly, M2 polarization increases PD-L2 expression in TAMs, resulting in immune evasion and tumor promotion through PD-1 signaling pathway. CONCLUSION: This study highlights the role of CCL2-CCR2 axis in esophageal carcinogenesis. Our findings provide new insight into the mechanism of immune evasion mediated by TAMs in ESCC, suggesting the potential of TAMs-targeted strategies for ESCC prevention and immunotherapy.

Tocopherols inhibit esophageal carcinogenesis through attenuating NF-κB activation and CXCR3-mediated inflammation.

Esophageal cancer is one of the common causes of cancer mortality in the world. The predominant histological subtype, esophageal squamous cell carcinoma (ESCC), often results in poor prognosis due to the lack of effective approaches for the early diagnosis and treatment, highlighting the need for preventive intervention against this disease. Here we report that dietary tocopherols significantly prevents esophageal carcinogenesis by inhibiting the activation of NF-κB and the subsequent interaction of chemokine CXCL9/10/11 with their receptor CXCR3 in ESCC induced by N-nitrosomethylbenzylamine (NMBA) in murine models. Dietary supplementation with 0.15% α-tocopherol (α-T), δ-tocopherol (δ-T), or γ-tocopherol rich mixture (γ-TmT) markedly suppressed the production of pro-inflammatory cytokines, as well as the induction of CXCR3+ effector T cells (CD4+ Th1 and CD8+ CTLs) infiltration, especially at the early stage of carcinogenesis. In experiments in vivo and in vitro, these events were tightly correlated with the blockade of NF-κB activation. Our results show that tocopherols decrease carcinogenesis through inhibiting NF-κB and CXCR3 signaling, as well as related inflammation in early premalignant lesions. This pathway may offer a novel target for chemoprevention of esophageal cancer.

Alpha-Tocopherol prevents esophageal squamous cell carcinoma by modulating PPARγ-Akt signaling pathway at the early stage of carcinogenesis.

The poor prognosis of esophageal squamous cell carcinoma (ESCC) emphasizes the urgent need to better understand the carcinogenesis and develop prevention strategies. Previous studies have highlighted the potential of using Vitamin E (tocopherols) for cancer chemoprevention, but the preventive activity of α-Tocopherol against ESCC remains to be elucidated. Our data showed that early-stage supplementation with α-Tocopherol significantly prevented esophageal carcinogenesis induced by N-nitrosomethylbenzylamine (NMBA) in ESCC rat model. In the Het-1A cell model, α-Tocopherol markedly suppressed cell proliferation, promoted cell cycle G2-phase arrest and increased apoptosis. Gene microarray and proteins array analysis indicated that Akt signaling was a potential target for α-Tocopherol. We further demonstrated that α-Tocopherol increased the expression of PPARγ and its downstream tumor suppressor PTEN. Knockdown of PPARγ activated Akt signaling transduction, whereas this process was attenuated by the presence of α-Tocopherol and PPARγ agonist Rosiglitazone. In contrast, the effect of α-Tocopherol on Akt inhibition was not observed in established tumors, neither in cancerous cell lines which constitutively expressed higher levels of PPARγ. These results were closely correlated with the ineffectiveness of α-Tocopherol in the late stage of ESCC carcinogenesis. Taken together, our study suggested that α-Tocopherol may serve as a PPARγ agonist for the chemoprevention of esophageal cancer.

A 90-day toxicity study of GmTMT transgenic maize in Sprague-Dawley rats.

GmTMT transgenic maize is a genetically modified maize plant that overexpresses the γ-tocopherol methyltransferase (γ-TMT) from Glycine max (Gm). The γ-TMT gene was introduced into maize line Zhen58 to encode the GmTMT2a protein which can convert γ-tocopherol into α-tocopherol. Overexpression of GmTMT2a significantly increased the α-tocopherol content in transgenic maize. The present study was designed to investigate any potential effects of GmTMT maize grain in a 90-day subchronic rodent feeding study. Maize grains from GmTMT or Zhen58 were incorporated into rodent diets at low (12.5%), medium (25%) or high (50%) concentrations and administered to Sprague-Dawley rats (n = 10/sex/group) for 90 days. The negative control group of rats (n = 10/sex/group) were fed with common maize diets. Results from body weights, feed consumption, clinical chemistry, hematology, absolute and relative organ weights indicated no treatment-related side effects of GmTMT maize grain on rats in comparison with rats consuming diets containing Zhen58 maize grain. In addition, no treatment-related changes were found in necropsy and histopathology examinations. Altogether, our data indicates that GmTMT transgenic maize is as safe and nutritious as its conventional non-transgenic maize.

[Study on sub-chronic toxicity of powered milk containing transgenic human alpha-lactalbumin].

OBJECTIVE: To investigate the potential toxic or adverse effect of transgenic human alpha-lactalbumin powered milk on rats. METHODS: Weanling Wistar rats were randomly divided into seven groups according the weight: three transgenic milk powder (T) groups, three non-transgenic milk powder (N) groups and the control (C) group. The diets of T groups contain 15%, 30% and 60% transgenic human alpha-lactalbumin milk powder. The diets of N groups contain 15%, 30% and 60% non-transgenic human alpha-lactalbumin milk powder for 90 days. The diet of C group contains only basic feed. Haematological and biochemical parameters was measured during the study (at 45th and 90th of the experiment). At the end of the 90th day, organ tissues analysis was performed. RESULTS: There were no transgenic human alpha-lactalbumin related adverse effects on the body weight, food intake, food consumption, hematology,serum biochemistry, as well as histopathology. CONCLUSION: There were no signs of toxic and adverse effects for transgenic human alpha-lactalbumin powdered milk on rats.

[Effect of diisobutyl phthalate on antioxidase activity and DNA damage in mice].

OBJECTIVE: To investigate the oxidative damage of mice induced by diisobutyl phthalate (DiBP) and the mechanism of free radical oxidative damage caused by DiBP. METHODS: Sixty KunMing mice were divided by weight into 5 groups after accommodation to the experimental animal room for 3 days. The control group and 4 DiBP groups, group I, II, III and IV, were given DiBP in corn oil by gavages at the dosage of 0, 50, 250, 500 and 1000 mg/kg respectively. The mice were fed with normal diets and drinking water freely for 8 weeks. By the end of the experiment, the comet assay of blood and SOD, GSH-Px, MDA and 8-OHdG of liver were tested. RESULTS: The activities of SOD and GSH-Px in DiBP groups were significantly lower than the control group (P < 0.05); the MDA contents of DiBP group III and group IV were significantly higher than the control group (P < 0.05) and the 8-OHdG content of group II was significantly higher than the control group (P < 0.01). The comet assay showed that the oxidative damage of DNA in DiBP groups was significant in comparison with the control group (P < 0.05). CONCLUSION: Oxidative stress induced by diisobutyl phthalate can decrease the activities of antioxidative enzymes and result in oxidative damage of tissues.

[90-day subchronic toxicity study of aloe whole-leaf powder].

90-day subchronic toxicity study of aloe whole-leaf powder was conducted to observe the effect of aloe whole-leaf powder on health. 88 SD rats were divided randomly into 4 groups, and each group consisted of 11 males and 11 females. The animals in group 2-4 received aloe whole-leaf powder mixed in regular rodent diet at doses of 2, 4 and 8 g/kg BW (by rate of 2.5, 5 and 10 percent in diet) for 90 days. The animals in group 1 received the regular rodent diet. The results showed that aloe whole-leaf powder promoted defecation of rats. Food efficiency and body weight males exposed to 8 g/kg BW were significantly less than those of the controls. Food efficiency males exposed to 4 g/kg BW was significantly decreased, but body weight was not affected. No adverse effect were observed on food efficiency and body weight by males exposed to 2 g/kg BW and all exposed groups of females. Relative kidney weight was significnatly increased in males exposed to 8 g/kg BW and females exposed to 2 g/kg BW or greater. Relative testis weight of rats exposed to 4 and 8 g/kg BW were significantly increased compared to the control groups. Aloe whole-leaf powder at the dose of 2, 4 and 8 g/kg BW did not have adverse effect on hematology, serum AST, ALT, TC, TG, Cr as well as NAG activity of urine, serum BUN was significantly increased at the dose of 8 g/kg BW. Pathology findings: the incidences of pigmentation in renal tubular, mesenteric lymph nodes and lamina propria of the colonic mucosa, and proliferation in mesenteric lymph nodes were significantly increased at all of the exposed groups, but no pigmentation in colonic mucosa was observed at the dose of 2 g/kg BW. No pathological changes were observed in livers, spleens, testes (or ovaries). It was concluded that observed adverse effect level of aloe whole-leaf powder was 2 g/kg BW (LOAEL of aloin was 11.8 g/kg BW).