[Effects of PM2.5 and O3 sub-chronic combined exposure on ATP amount and ATPase activities in rat nasal mucosa].

OBJECTIVE: To evaluate the effects of fine particle matter (PM2.5) and ozone (O3) combined exposure on adenosine triphosphate (ATP) amount and ATPase activities in nasal mucosa of Sprague Dawley (SD) rats. METHODS: Twenty male SD rats were divided into control group (n=10) and exposure group (n=10) by random number table method. The rats were fed in the conventional clean environment and the air pollutant exposure system established by our team, respectively, and exposed for 208 d. During the exposure period, the concentrations of PM2.5 and O3 in the exposure system were monitored, and a comprehensive assessment of PM2.5 and O3 in the exposure system was conducted by combining self-measurement and site data. On the 208 d of exposure, the core, liver, spleen, kidney, testis and other major organs and nasal mucosal tissues of the rats were harvested. Each organ was weighed and the organ coefficient calculated. The total amount of ATP was measured by bioluminescence, and the activities of Na+-K+ -ATPase and Ca2+ -ATPase were detected by spectrophotometry. The t test of two independent samples was used to compare the differences among the indicator groups. RESULTS: From the 3rd week to the end of exposure duration, the body weight of the rats in the exposure group was higher than that in the control group (P < 0.05), and there was no significant difference in organ coefficients between the two groups. The average daily PM2.5 concentration in the exposure group was (30.68±19.23) µg/m3, and the maximum 8 h ozone concentration (O3-8 h) was (82.45±35.81) µg/m3. The chemiluminescence value (792.4±274.1) IU/L of ATP in nasal mucosa of the rats in the exposure group was lower than that in the control group (1 126.8±218.1) IU/L. The Na+-K+-ATPase activity (1.53±0.85) U/mg in nasal mucosa of the rats in the exposure group was lower than that in the control group (4.31±1.60) U/mg (P < 0.05). The protein content of nasal mucosa in the control group and the exposure group were (302.14±52.51) mg/L and (234.58±53.49) mg/L, respectively, and the activity of Ca2+-ATPase was (0.81±0.27) U/mg and (0.99±0.73) U/mg, respectively. There was no significant difference between the groups. CONCLUSION: The ability of power capacity decreased in the rat nasal mucossa under the sub-chronic low-concentration exposure of PM2.5 and O3.

Landscape of lipidomic metabolites in gut-liver axis of Sprague-Dawley rats after oral exposure to titanium dioxide nanoparticles.

BACKGROUND: The application of titanium dioxide nanoparticles (TiO2 NPs) as food additives poses a risk of oral exposure that may lead to adverse health effects. Even though the substantial evidence supported liver as the target organ of TiO2 NPs via oral exposure, the mechanism of liver toxicity remains largely unknown. Since the liver is a key organ for lipid metabolism, this study focused on the landscape of lipidomic metabolites in gut-liver axis of Sprague Dawley (SD) rats exposed to TiO2 NPs at 0, 2, 10, 50 mg/kg body weight per day for 90 days. RESULTS: TiO2 NPs (50 mg/kg) caused slight hepatotoxicity and changed lipidomic signatures of main organs or systems in the gut-liver axis including liver, serum and gut. The cluster profile from the above biological samples all pointed to the same key metabolic pathway and metabolites, which was glycerophospholipid metabolism and Phosphatidylcholines (PCs), respectively. In addition, absolute quantitative lipidomics verified the changes of three PCs concentrations, including PC (16:0/20:1), PC (18:0/18:0) and PC (18:2/20:2) in the serum samples after treatment of TiO2 NPs (50 mg/kg). The contents of malondialdehyde (MDA) in serum and liver increased significantly, which were positively correlated with most differential lipophilic metabolites. CONCLUSIONS: The gut was presumed to be the original site of oxidative stress and disorder of lipid metabolism, which resulted in hepatotoxicity through the gut-liver axis. Lipid peroxidation may be the initial step of lipid metabolism disorder induced by TiO2 NPs. Most nanomaterials (NMs) have oxidation induction and antibacterial properties, so the toxic pathway revealed in the present study may be primary and universal.

Combined effect of titanium dioxide nanoparticles and glucose on the blood glucose homeostasis in young rats after oral administration.

Titanium dioxide nanoparticles (TiO2 NPs) were usually consumed with a high content of sugar, and children were identified as having the highest exposures due to sweet food preferences. Research on the combined effect of ingested TiO2 NPs and glucose has great significance, particularly in young people. We examined young Sprague-Dawley rats administered TiO2 NPs (0, 2, 10 and 50 mg/kg) orally with and without glucose (1.8 g/kg) for 90 days. Blood glucose homeostasis was assessed by monitoring blood glucose and detecting glycoproteins. Glucose tolerance was also evaluated by the oral glucose tolerance test. The levels of blood glucose-related hormones such as insulin, C-peptide and glucagon were measured. We found that subchronic co-exposure of TiO2 NPs and glucose caused slight imbalance of blood glucose homeostasis in vivo. Mild and temporary hypoglycemia, impaired glucose tolerance and changes of glucose-regulating hormones were shown in the exposure groups. The combined effect of TiO2 NPs and glucose was more apparent than that of TiO2 NPs alone, which may be due to the effects of excess glucose and the interactions between TiO2 NPs and glucose. The antagonistic effect of TiO2 NPs with glucose did exist in the level of glycosylated hemoglobin in female rats. Gender differences were apparent in these effects induced by TiO2 NPs and glucose. Female rats seemed to be more susceptible for blood glucose disorders. Co-exposure of TiO2 NPs and excessive glucose could induce gender-dependent imbalance of blood glucose homeostasis in rats. It may be the reason that these consumers face greater health risks glycosylated hemoglobin.

[Effect of subacute combined oral exposure of titanium dioxide nanoparticles and glucose on blood glucose homeostasis in young SD rats].

OBJECTIVE: To explore the effect of combined oral exposure of titanium dioxide nanoparticles(TiO_2 NPs) and glucose on blood glucose homeostasis in young SD rats. METHODS: Eighty 4-week-old young SD rats were randomly divided into 8 groups(10 rats in each group, half male and half female). The rats were exposed to TiO_2 NPs through intragastric administration at 0, 2, 10 and 50 mg/kg with or without 1. 8 g/kg glucose daily for 30 days. Blood glucose was monitored weekly during the experiment. Oral glucose tolerance test(OGTT) was carried out after subacute exposure(30 days), and the biomarkers related to blood glucose homeostasis were detected, including the contents of glycosylated serum protein(GSP), glycosylated hemoglobin(HbA1 c), insulin, C-peptide and glucagon. At the same time, the pancreatic pathology of rats was observed. RESULTS: TiO_2 NPs were anatase crystals, closely spherical shape, with an average particle size of(24±5)nm. Exposure of TiO_2 NPs alone had little effect on blood glucose homeostasis. Blood glucose decreased on the 16 th exposure day at dose of 10 mg/kg TiO_2 NPs, and postprandial blood glucose(2 h) decreased after 30 days of TiO_2 NPs exposure at doses of 2 and 50 mg/kg in male rats(P<0. 05). The combined effect of oral exposure of TiO_2 NPs and glucose on blood glucose homeostasis was more obvious than that of TiO_2 NPs alone. Blood glucose decreased on the 9 th exposure day at dose of 10 mg/kg TiO_2 NPs+glucose in female rats, and postprandial blood glucose(2 h) decreased at dose of 2 and 50 mg/kg TiO_2 NPs+glucose after 30 days of exposure in male rats(P<0. 05). Blood glucose decreased on the 9 th day after 10 mg/kg TiO_2 NPs+glucose exposure in female rats. The glycosylated serum protein decreased and postprandial blood glucose(30 and 60 min) as well as the area under curve of OGTT increased in male rats after 30 days of exposure(P<0. 05). The changes of blood glucose-regulating hormones were only found after the combined exposure of 10 mg/kg TiO_2 NPs+glucose for 30 days, including the decrease of insulin in female rats, as well as the decrease of insulin and the increase of glucagon in male rats(P<0. 05). The interaction analysis showed that TiO_2 NPs and glucose had significant synergistic effect on postprandial blood glucose(60 min) in male rats(P<0. 05). No abnormality was found in the pathological observation of pancreas in rats of experimental groups. CONCLUSION: Subacute combined oral exposure of TiO_2 NPs and glucose could affect the blood glucose homeostasis of young SD rats, resultsing in temporary hypoglycemia and impaired glucose tolerance, as well as adaptive changes of blood glucose-regulating hormones. The male rats were more sensitive. Compared with the exposure of TiO_2 NPs alone, the combined exposure of TiO_2 NPs and glucose induced more significant effects. Significant synergistic effect between them occurred on postprandial blood glucose.

Hepatotoxicity and the role of the gut-liver axis in rats after oral administration of titanium dioxide nanoparticles.

BACKGROUND: Due to its excellent physicochemical properties and wide applications in consumer goods, titanium dioxide nanoparticles (TiO2 NPs) have been increasingly exposed to the environment and the public. However, the health effects of oral exposure of TiO2 NPs are still controversial. This study aimed to illustrate the hepatotoxicity induced by TiO2 NPs and the underlying mechanisms. Rats were administered with TiO2 NPs (29 nm) orally at exposure doses of 0, 2, 10, 50 mg/kg daily for 90 days. Changes in the gut microbiota and hepatic metabolomics were analyzed to explore the role of the gut-liver axis in the hepatotoxicity induced by TiO2 NPs. RESULTS: TiO2 NPs caused slight hepatotoxicity, including clear mitochondrial swelling, after subchronic oral exposure at 50 mg/kg. Liver metabolomics analysis showed that 29 metabolites and two metabolic pathways changed significantly in exposed rats. Glutamate, glutamine, and glutathione were the key metabolites leading the generation of energy-related metabolic disorders and imbalance of oxidation/antioxidation. 16S rDNA sequencing analysis showed that the diversity of gut microbiota in rats increased in a dose-dependent manner. The abundance of Lactobacillus_reuteri increased and the abundance of Romboutsia decreased significantly in feces of TiO2 NPs-exposed rats, leading to changes of metabolic function of gut microbiota. Lipopolysaccharides (LPS) produced by gut microbiota increased significantly, which may be a key factor in the subsequent liver effects. CONCLUSIONS: TiO2 NPs could induce slight hepatotoxicity at dose of 50 mg/kg after long-term oral exposure. The indirect pathway of the gut-liver axis, linking liver metabolism and gut microbiota, played an important role in the underlying mechanisms.

Gender difference in hepatic toxicity of titanium dioxide nanoparticles after subchronic oral exposure in Sprague-Dawley rats.

Existing literature pointed out that the liver may be the target organ of toxicity induced by titanium dioxide nanoparticles (TiO2 NPs) via oral exposure. Gender differences in health effects widely exist and relevant toxicological research is important for safety assessment. To explore the gender susceptibility of TiO2 NP-induced hepatic toxicity and the underlying mechanism, we examined female and male Sprague-Dawley rats administrated with TiO2 NPs orally at doses of 0, 2, 10 and 50 mg/kg body weight per day for 90 days. The serum biochemical indicators and liver pathological observation were used to assess hepatic toxicity. We found significant hepatic toxicity could be induced by subchronic oral exposure to TiO2 NPs, which was more obvious and severe in female rats. No accumulation of TiO2 NPs in the liver was observed, indicating that hepatic toxicity may not be caused through direct pathways. Oxidized glutathione, lipid peroxidation products increased significantly and reduced glutathione decreased significantly in the liver of rats in repeated TiO2 NP-exposed groups. Hematological parameters of white blood cells and inflammatory cytokines in serum including interleukin 1α, interleukin 4 and tumor necrosis factor also increased significantly. Indirect pathways through initiating oxidative stress and inflammatory responses were suggested as the possible mechanism of the hepatic toxicity in this experiment. The higher sensitivity to redox homeostasis imbalance and inflammation of female rats may be the main reason for gender differences. Our research suggested that gender should be a susceptible factor for identifying and monitoring long-term oral toxicity of TiO2 NPs.

Combined effect of titanium dioxide nanoparticles and glucose on the cardiovascular system in young rats after oral administration.

Titanium dioxide nanoparticles (TiO2 NPs) have already been used as food additive in various products and are usually consumed with a considerable amount of sugar. Oral consumption of TiO2 NPs poses concerning health risks; however, research on the combined effect of ingested TiO2 NPs and glucose is limited. We examined young Sprague-Dawley rats administrated TiO2 NPs orally at doses of 0, 2, 10 and 50 mg/kg body weight per day with and without 1.8 g/kg body weight glucose for 30 and 90 days. Heart rate, systolic and diastolic blood pressure, blood biochemical parameters and histopathology of cardiac tissues was assessed to quantify cardiovascular damage. The results showed that oral exposure to TiO2 NPs and high doses of glucose both could induce cardiovascular injuries. The toxic effects were dose-, time- and gender-dependent. The interaction effects between oral-exposed TiO2 NPs and glucose existed and revealed to be antagonism in most of the biological parameters. However, toxic effects of the high-dose glucose seemed to be more severe than TiO2 NPs and the interaction of TiO2 NPs with glucose. These results suggest that it may be more important to control the sugar intake than TiO2 NPs for protecting the health of TiO2 NP consumers.

Preclinical PK/PD model for combined administration of erlotinib and sunitinib in the treatment of A549 human NSCLC xenograft mice.

AIM: Combined therapy of EGFR TKI and VEGFR TKI may produce a greater therapeutic benefit and overcome EGFR TKI-induced resistance. However, a previous study shows that a combination of EGFR TKI erlotinib (ER) with VEGFR TKI sunitinib (SU) did not improve the overall survival in patients with non-small-cell lung cancer (NSCLC). In this study we examined the anticancer effect of ER, SU and their combination in the treatment of A549 human NSCLC xenograft mice, and conducted PK/PD modeling and simulations to optimize the dose regimen. METHODS: ER (20, 50 mg·kg(-1)·d(-1)) or SU (5, 10, 20 mg·kg(-1)·d(-1)) alone, or their combination were administered to BALB/c nude mice bearing A549 tumors for 22 days. The tumor size and body weight were recorded daily. The experimental data were used to develop PK/PD models describing the quantitative relationship between the plasma concentrations and tumor suppression in different dose regimens. The models were further evaluated and validated, and used to predict the efficacy of different combination regimens and to select the optimal regimen. RESULTS: The in vivo anticancer efficacy of the combination groups was much stronger than that of either drug administered alone. A PK/PD model was developed with a combination index (φ) of 4.4, revealing a strong synergistic effect between ER and SU. The model simulation predicted the tumor growth in different dosage regimens, and showed that the dose of SU played a decisive role in the combination treatment, and suggested that a lower dose of ER (≤5 mg·kg(-1)·d(-1)) and adjusting the dose of SU might yield a better dosage regimen for clinical research. CONCLUSION: The experimental data and modeling confirm synergistic anticancer effect of ER and SU in the treatment of A549 xenograft mice. The optimal dosage regimen determined by the PK/PD modeling and simulation can be used in future preclinical study and provide a reference for clinical application.

[Reconstitution of mast cell population in gastrointestinal tract by bone marrow transplantation in mast cell deficient rats].

OBJECTIVE: To explore whether bone marrow transplantation (BMT) can restore gastrointestinal mast cells in mast cell deficient (Ws/Ws) rats and understand the features of these reconstituted mast cells. METHODS: Thirty-six Ws/Ws rats were subjected to Co(60) radiation at 6 gradient doses (6.0, 7.0, 8.0, 9.0, 10.0 and 11.0 Gy, n = 6) to confirm the appropriate dosage. And another 6 rats served as non-radiated controls. Sixteen Ws/Ws rats were exposed to a 7.5 Gy radiation and sacrificed at Day 1, 5, 8 and 12 (n = 4) to obtain hemogram and myelogram. And 4 non-radiated Ws/Ws rats served as control. Ws/Ws rats received an intravenous injection of bone marrow cells harvested from healthy congenic Brown Norway (BN) rats after a dosage of 7.5 Gy radiation. Y-chromosome fluorescence in situ hybridization (Y-FISH) was used to identify the survival and differentiation of bone marrow cells of male BN rats in female BMT-Ws/Ws rats (n = 4). Another set of 24 male BMT-Ws/Ws rats were sacrificed Weeks 5, 8, 13 and 23 post-BMT (n = 6). Tissues from esophagus, stomach, ileum and colon were harvested to perform mast cell quantification by Alcian blue staining. And mast cell derived proteinases (tryptase and chymase) were quantified by Western blotting. RESULTS: Y-FISH showed bone marrow cells from male BN rats survived in female BMT-Ws/Ws rats and mast cells were restored in gastrointestinal tract. Compared with control, the highest level of mast cell number (103 ± 6) vs (35 ± 4)/mm(2) for esophagus, (271 ± 23) vs (124 ± 13)/mm(2) for stomach, (200.1 ± 13.3) vs (103.2 ± 6.6)/mm(2), all P < 0.05) and mast cell proteinases (1.3 ± 0.3 vs 0.6 ± 0.2 for esophagus, 3.6 ± 0.8 vs 1.9 ± 0.4 for ileum, both P < 0.05) in BMT-Ws/Ws rats were observed at Week 8 post-BMT. The number of mast cell and proteinases decreased at Week 13 post-BMT. CONCLUSIONS: BMT may restore mast cells in Ws/Ws rats. The best time period for using BMT-Ws/Ws rats in the study of mast cell function is between Weeks 8-13 post-BMT.

DNA damage, serum metabolomic alteration and carcinogenic risk associated with low-level air pollution.

Outdoor air pollution has been classified as carcinogenic to humans (Group 1) for lung cancer, but the underlying mechanism and key toxic components remain incompletely understood. Since DNA damage and metabolite alterations are associated with cancer progression, exploring potential mechanisms linking air pollution and cancer might be meaningful. In this study, a real-time ambient air exposure system was established to simulate the real-world environment of adult male SD rats in Beijing from June 13th, 2018, to October 8th, 2018. 8-OHdG in the urine, γ-H2AX in the lungs and mtDNA copy number in the peripheral blood were analyzed to explore DNA damage at different levels. Serum non-targeted metabolomics analysis was performed. Pair-wise spearman was used to explore the correlation between DNA damage biomarkers and serum differential metabolites. Carcinogenic risks of heavy metals and PAHs via inhalation were assessed according to US EPA guidelines. Results showed that PM2.5 and O3 were the major air pollutants in the exposure group and not detected in the control group. Compared with control group, higher levels of 8-OHdG, mtDNA copy number, γ-H2AX and PCNA-positive nuclei cells were observed in the exposure group. Histopathological evaluation suggested ambient air induced alveolar wall thickening and inflammatory cell infiltration in lungs. Perturbed metabolic pathways identified included glycolysis/gluconeogenesis metabolism, purine and pyrimidine metabolism, etc. γ-H2AX was positively correlated with serum ADP, 3-phospho-D-glyceroyl phosphate and N-acetyl-D-glucosamine. The BaPeq was 0.120 ng/m3. Risks of Cr(VI), As, V, BaP, BaA and BbF were above 1 × 10-6. We concluded that low-level air pollution was associated with DNA damage and serum metabolomic alterations in rats. Cr(VI) and BaP were identified as key carcinogenic components in PM2.5. Our results provided experimental evidence for hazard identification and risk assessment of low-level air pollution.

Exposure to the real ambient air pollutants alters the composition of nasal mucosa bacteria in the rat model.

Studies have indicated that ambient pollutant exposure correlates with nasal disease, in which nasal mucosa microbiota play a crucial role. However, the association between exposure to real-ambient air pollutants and the composition of nasal mucosa microbiota has not been well studied. This study aimed to explore the composition of nasal mucosa microbiota after exposure to real-ambient air pollutants with a special system. We monitored PM2.5, O3, etc. in the system and confirmed PM2.5 and O3 were the main pollutants. SD rats were exposed to the system for 16 weeks in summer or 22 weeks in autumn-winter. The concentrations of PM2.5 were 24.00 µg/m3 in the Summer stage and 22.21 µg/m3 in the autumn-winter stage. The O3 concentrations were 25.46 and 13.55 µg/m3, respectively. Exposure altered bacterial beta diversity in the summer stage. There were 4 and 3 different bacteria at the king, order, family and genus levels between the two groups at the two stages, respectively. The abundance of opportunistic pathogens changed, Pseudomonas decreased in summer stage, and Bifidobacterium increased in the autumn-winter stage. The influence of the season on the nasal mucosa microbiota was analyzed. The alpha diversity of the autumn-winter stage was higher than that of the summer stage. LEfSe analysis revealed 34 differential bacterial taxa at the king, order, family and genus level in the two control groups and 31 of the two exposure groups, which were not the same as the bacteria between the control groups and exposure groups. We found that PM2.5 combined with O3 exposure was associated with the composition of the nasal mucosa microbiota and the abundance of opportunistic pathogens, in which season likely impacted the microbiota.

Effect of oral exposure to titanium dioxide nanoparticles on lipid metabolism in Sprague-Dawley rats.

Ingestion of titanium dioxide nanoparticles (TiO2 NPs) via dietary and environmental exposure may pose health risks. The research about the potential effect of orally ingested nanoparticles on nutritional metabolism has been limited. We conducted an animal experiment to investigate the effect of oral exposure to TiO2 NPs on lipid metabolism in Sprague-Dawley rats. The rats were treated with TiO2 NPs (29 ± 9 nm) orally at doses of 0, 2, 10, 50 mg per kg bw daily for 90 days. Lipid metabolism is evaluated by biomarkers of serum lipids and lipidomics. TiO2 NPs caused a significant decrease of body weight in rats after exposure at doses of 10 and 50 mg kg-1 from the 8th to 13th week. The level of triglycerides (TG) decreased (0.398 ± 0.114 vs. 0.248 ± 0.058 nmol L-1) and the lipidomic signature changed significantly in the serum of rats treated with TiO2 NPs (50 mg kg-1). Sixty-nine well-matched lipophilic metabolites were differentially expressed and the glycerophospholipid metabolism pathway significantly changed. The concentrations of 32 metabolites including 19 kinds of phosphatidylcholines (PCs) increased and 37 metabolites including lysophosphatidylcholines (LysoPCs) and glycerophosphocholine decreased significantly in the TiO2 NP exposed group (50 mg kg-1). The accumulation of the lipid peroxidation product (malondialdehyde, MDA) and the decreased activity of the antioxidant enzyme SOD were observed and closely related to differential metabolites. In conclusion, orally ingested TiO2 NPs (50 mg kg-1) could have an impact on lipid metabolism, for which the strong induction of oxidative stress may be the main reason. The present study led to a better understanding of the oral toxicity of food-related TiO2 NPs.

Tissue-specific oxidative stress and element distribution after oral exposure to titanium dioxide nanoparticles in rats.

Dietary and environmental exposure to titanium dioxide nanoparticles (TiO2 NPs) can cause low-dose and long-term oral exposure in the population, posing a potential adverse health risk. Oxidative stress is considered to be the primary effect of TiO2 NPs through biological interaction. In the present study, we conducted an animal experiment to investigate the element distribution and oxidative stress in Sprague-Dawley rats after oral exposure to TiO2 NPs at daily doses of 0, 2, 10, and 50 mg kg-1 for 90 days. Through the detection of Ti element content in various tissues, limited absorption and distribution of TiO2 NPs in rats was found. However, orally ingested TiO2 NPs still induced tissue-specific oxidative stress and imbalance of elements. Liver tissue was the most sensitive tissue to TiO2 NP-induced oxidative stress, showing decreased reduced glutathione (GSH), increased oxidized glutathione (GSSG) and decreased ratio of GSH/GSSG as well as accumulation of lipid peroxidation (malondialdehyde, MDA) in liver tissues of rats after TiO2 NP exposure (10 and 50 mg kg-1). Meanwhile, oral exposure to TiO2 NPs caused a significant reduction in metal elements such as Mg, Ca and Co in various tissues. Through bioinformatics analysis, the tissue specificity and correlation between the imbalance of elements and oxidative stress were statistically confirmed, but it was difficult to understand the causal relationship. Disorder of element distribution and oxidative stress may lead to a series of subsequent adverse health effects and the tissue specificity would partly explain the target effects of TiO2 NPs.

Stearoyl-CoA desaturase 1 deficiency protects mice from immune-mediated liver injury.

Immunity and metabolism are closely linked. The liver is an important metabolic organ in the body. However, the interactions between hepatocytes and the immune system are poorly understood. In mice developing concanavalin A (ConA)-induced hepatitis (CIH), we found extensive lipid accumulation in hepatocytes. Critical enzyme involved in fat synthesis such as stearoyl-CoA desaturase 1 (SCD1) was upregulated. When we injected ConA to SCD1-deficient mice, we found these mice to be highly resistant to CIH. The mechanisms of the protective effect of SCD1 deficiency might be attributed to the reduced leptin levels in those mice, which modulated critical cytokines and signaling pathways in CIH pathogenesis. In conclusion, our study suggests that SCD1 deficiency protects mice from liver injury in a leptin-dependent manner.

[Establishment of irritable bowel syndrome rat model by combination of intestinal infection with Trichinella spiralis and acute stress].

OBJECTIVE: To establish the irritable bowel syndrome (IBS) rat model by the combination of acute stress and transient intestinal infection with Trichinella spiralis (T.S.). METHODS: The rat model of acute cold restraint stress post-infection (PI + ACRS) was established as following: the intestinal infection with 1500 T.S. in 1 ml saline to adult male BN rats was performed at Day 0 by gastric lavage. Then a 2-hour stimulus of ACRS was administered at Day 100. Age matched transiently infected without stress rats (PI) and normal rats served as controls (CON) (n = 6, for each). After anesthesia, all the rats underwent colonic manometry in vivo at Day 100. The colonic pressures at 3 different states (baseline for 20 min; 1 ml balloon distension stimulation for 5 min and 2 ml balloon distension stimulation for 20 min) were traced with a 5-minute interval between each two. The following parameters were recorded: (1) Duration (Dur.): total time of contractions during each state. (2) Maximum (Max.): highest amplitude of constructional waves (mm Hg). (3) Area: area under contraction waves. (4) Number (Num.): frequencies of contraction wave during each state. The visceromoter response to colorectal distension (CRD) was analyzed at Day 100 post-infection. And the distension volume of AWR 3 was detected for 5 times with a 20-min interval in each rat. RESULTS: The histological damage of intestine induced by T.S. infection is transient. Although such acute infectious features as epithelial edema, hyperemia and marked eosinophil infiltration appeared at Day 10 PI, the histological changes almost recovered at Day 100 PI in both the PI group and the PI + ACRS group. Both the stimuli of transient infection and the ACRS post-infection induced intestinal dysmotility and visceral hypersensitivity. The ACRS post infection further worsened the transiently induced infection. The parameters of Num, Max and Area in the PI + ACRS group were all significantly higher than those of the PI group [Max: (41 +/- 17) mm Hg vs (22 +/- 6) mm Hg, P = 0.000; Area: (7693 +/- 2822) mm Hg.s vs (5092 +/- 1687) mm Hgxs, P = 0.000; Num: 9.5 +/- 2.6 vs 6.6 +/- 3.1, P = 0.000]; so was the distension volume of AWR3 [(2.25 +/- 0.29) ml vs (2.52 +/- 0.32) ml, P = 0.004]. As compared with the range of normal values from controls, the abnormality rates of motility parameters and visceral threshold in PI + ACRS group also had an larger increment than those of the PI group (PI + ACRS: 50.0% - 87.5% and 100% respectively, PI: 25.0% - 37.5% and 90.0% respectively). CONCLUSION: The pathophysiological changes in the PI + ACRS rats are consistent with those of IBS. Aggravated by psychological factors, these rats reproduce the symptoms of intestinal dysmotility and visceral hypersensitivity. A proper animal model has been established for the investigation of IBS.

Effects of oral exposure to titanium dioxide nanoparticles on gut microbiota and gut-associated metabolism in vivo.

The antibacterial activity of titanium dioxide nanoparticles (TiO2 NPs) has been extensively documented and applied to food packaging or environmental protection. Ingestion of TiO2 NPs via dietary and environmental exposure may pose potential health risks by interacting with gut microbiota. We conducted an animal experiment to investigate the effects of oral exposure to TiO2 NPs on gut microbiota and gut-associated metabolism in Sprague-Dawley rats. Rats were administered with TiO2 NPs (29 ± 9 nm) orally at population-related exposure doses (0, 2, 10, 50 mg kg-1) daily for 30 days. Changes in the gut microbiota and feces metabolomics were analyzed through bioinformatics. TiO2 NPs caused significant changes of colon morphology in rats, manifested as pathological inflammatory infiltration and mitochondrial abnormalities. 16S rDNA sequencing analysis showed that the structure and composition of gut microbiota in rats were modulated after exposure to TiO2 NPs. Monitoring data demonstrated that differentially expressed bacterial strains were obtained until exposure for 14 days and 28 days, including increased L. gasseri, Turicibacter, and L. NK4A136_group and decreased Veillonella. Fecal metabolomics analysis showed that 25 metabolites and the aminoacyl-tRNA biosynthesis metabolic pathway have changed significantly in exposed rats. The increased metabolites were represented by N-acetylhistamine, caprolactam, and glycerophosphocholine, and the decreased metabolites were represented by 4-methyl-5-thiazoleethanol, l-histidine, and l-ornithine. Metabolic disorders of gut microbiota and subsequently produced lipopolysaccharides (LPS) led to oxidative stress and an inflammatory response in the intestine, which was considered to be a key and primary indirect pathway for toxicity induced by oral exposure to the TiO2 NPs. In conclusion, orally ingested TiO2 NPs could induce disorders of gut microbiota and gut-associated metabolism in vivo. The indirect pathway of oxidative stress and inflammatory response, probably due to dysbiosis of gut microbiota primarily, played an important role in the mechanisms of toxicity induced by oral exposure to TiO2 NPs. This may be a common mechanism of toxicity caused by oral administration of most nanomaterials, as they usually have potential antimicrobial activity.

Identification of new cytotoxic T-lymphocyte epitopes from cancer testis antigen HCA587.

The cancer testis (CT) antigen HCA587 is highly expressed in human hepatocellular carcinoma (HCC) and induces specific T-cell responses in a significant proportion of HCC patients. To explore its potential in cancer immunotherapy, a reverse immunology approach was adopted to identify HCA587-derived HLA-A( *)0201-restricted epitopes. Multiple peptides with a top ranking in various prediction programs were thus synthesized and three of them-p248-256, p140-149 and p144-152-were found to bind to HLA-A(*)0201 molecules with a high affinity and effectively induced a recall response of CD8+ T cells, which were either primed in vitro with the HCA587 antigen or directly isolated from HCC patients bearing HCA587+ tumors. Notably, these peptide-specific CD8+ T cells exhibited potent cytotoxic activity over HCA587+ tumor cells. Taken together, the present study has identified three new HLA-A(*)0201-restricted cytotoxic T cell epitopes in the CT antigen HCA587, which may serve as targets for peptide-based immunotherapy for HCC patients.

Alterations in hemorheological properties of erythrocytes in nude mice with erythroleukemia and the treatment effects of etoposide.

The purpose of this study was to examine the changes of hemorheological properties of erythrocytes in the nude mice with erythroleukemia and the treatment effects of etoposide (VP16). Thirty mice were randomly divided into three groups: the control group (C group), injected with 1 ml saline solution, the MEL group (M group) injected with 1 ml MEL (murine erythroleukemia cell line) and the MEL + VP16 group (V group) injected with 1 ml MEL and from the 8th day after injection, 20 microl VP16 (1 microg/microl) was injected intraperitoneally every five days. One week after MEL injection, erythroblastic cells increased in the bone marrow and proerythroblasts were found in the peripheral blood, suggesting that erythroleukemia was induced. Abnormalities were also found in spleens and livers later. At around twenty days after injection, the mice in M group died and about four weeks after injection, the mice in V group also died. Compared with C group, the hemorheological indexes [the deformation index DI, orientation index (DI(or)), and the small deformation index (DI(d))], electrophoretic mobility, membrane fluidity as well as osmotic fragility of red blood cells (RBC) in M and V groups changed significantly. But after VP16 administration, the changes of above parameters in V group were less significant than those of M group. The results above suggested that intraperitoneal injection of MEL cells could cause erythroleukemia in nude mice, VP16 could alleviate the erythroleukemia symptom and improve the hemorheological properties, and could prolong V group nude mice survival.

Semi-Mechanism-Based Pharmacokinetic/Pharmacodynamic Model for the Combination Use of Dexamethasone and Gemcitabine in Breast Cancer.

Our study aimed at the investigation of in vivo anticancer effect of the combination use of dexamethasone (DEX) and gemcitabine (GM) as well as the development of pharmacokinetic/pharmacodynamic (PK/PD) models in MCF-7 xenograft model. Further, simulations were conducted to optimize doses and administration schedules. The inhibitory effect of different doses and administration schedules were investigated in MCF-7 xenograft model. Semi-mechanism-based PK/PD models were established based on the preclinical data to characterize the relationship between plasma concentration and the time course of the drug response quantitatively. The PK/PD models were further applied to predict and optimize doses and administration schedules, which would lead to tumor stasis by the end of the treatment. Synergistic effect was observed in the PD study in vivo and further confirmed by the estimated combination index ψ obtained from PK/PD models. The optimum dose regimen was selected as DEX 2 mg/kg, qd and GM 10 mg/kg, q2d based on the simulation results. In summary, the PD interaction between DEX and GM was demonstrated as synergism by both experimental results and modeling approach. Dosage regimens were optimized as predicted by modeling and simulations, which would provide reference for preclinical study and translational research as well.

Alteration of cholinergic and peptidergic neurotransmitters in rat ileum induced by acute stress following transient intestinal infection is mast cell dependent.

BACKGROUND: Mast cells are implicated in the development of irritable bowel syndrome (IBS), which is associated with the activation of the "neural-immune" system. The aim of this study was to investigate the role of mast cells in the remodeling of cholinergic and peptidergic neurotransmitters induced by acute cold restriction stress (ACRS) post infection (PI) using mast cell deficient rats (Ws/Ws) and their wild-type controls (+/+). METHODS: Transient intestinal infection was initiated by giving 1500 Trichinella spiralis (T.S.) larvae by gavage. ACRS was induced for 2 hours at day 100 PI. Samples of terminal ilea were prepared for H&E staining, mast cell counting and activation and assessment of IL-1beta and IL-10. RESULTS: When infected, both strains of rats experienced an acute infectious stage followed by a recovery. Histological scores were significantly higher in infected rats compared with those of the non-infected controls at day 10 PI (10 day-PI vs. control: +/+: 2.75+/-0.17 vs. 0.42+/-0.09; Ws/Ws: 2.67+/-0.67 vs. 0.50+/-0.34; P<0.01). In +/+ rats, post-infection ACRS induced the formation of low-grade inflammation, represented by the imbalance of IL-1beta and IL-10 (IL-1beta: PI+ACRS vs. control: (1812.24+/-561.61) vs. (1275.97+/-410.21) pg/g, P<0.05; IL-10: PI+ACRS vs. control: (251.9+/-39.8) vs. (255.3+/-24.7) pg/g, P>0.05), accompanied by hyperplasia and activation of mast cells (PI+ACRS vs. control: 58.8+/-19.2 vs. 28.0+/-7.6; P<0.01). The balance between acetylcholine (ACh) and substance P (SP) was also disturbed (ACh: PI+ACRS vs. control: (743.94+/-238.72) vs. (1065.68+/-256.46) pg/g, P<0.05; SP: PI+ACRS vs. control: (892.60+/-231.12) vs. (696.61+/-148.61) pg/g, P<0.05). Nevertheless, similar changes of IL-1beta/IL-10 and ACh/SP were not detected in Ws/Ws rats. CONCLUSION: The imbalance of ACh/SP, together with the activation of mucosal immunity induced by post-infection ACRS were lacking in mast cell deficient rats, which supports the premise that mast cells play an important role in cholinergic and peptidergic remodeling in the ileum of rats.