Antiviral and lung protective activity of a novel respiratory syncytial virus fusion inhibitor in a mouse model

Respiratory syncytial virus (RSV) causes bronchiolitis in young children and common colds in adults. There is no licensed vaccine, and prophylactic treatment with palivizumab is very expensive and limited to high-risk infants. Ribavirin is used as an antiviral treatment in infants and immunosuppressed patients, and its use is limited due to side-effects, toxicity to the recipient and staff, and evidence of marginal clinical efficacy. Therefore, we studied the in vivo kinetics, and the antiviral and protective properties of a novel candidate for RSV disease treatment. The drug is a small molecule (TMC353121) discovered by screening for fusion inhibitory properties against RSV in a cellular infection model. The pharmacokinetics of TMC353121 was studied in BALB/c mice and antiviral effects determined by testing viral loads in lung tissue by quantitative RT-PCR and plaque assay after intranasal RSV infection. At doses of 0.25-10 mg · kg(-1), TMC353121 significantly reduced viral load, bronchoalveolar lavage cell accumulation and the severity of lung histopathological change after infection. Treatment remained effective if started within 48 h of infection, but was ineffective thereafter. Therefore, TMC353121 is a novel potent antiviral drug, in vivo reducing RSV replication and inhibiting consequential lung inflammation, with a great potential for further clinical development.

Effects of Azadirachta indica on certain hematological parameters during benzo(a)pyrene induced murine forestomach tumorigenesis

OBJECTIVES

Exposure to environmental toxicants/carcinogens, the process of carcinogenesis itself and cancer treatments lead to several secondary pathologies including hematological complications. Considering versatile pharmacological potentials of Azadirachta indica (A. indica), the present study was designed to evaluate its effects on certain hematological parameters in benzo(a)pyrene [B(a)P] induced murine forestomach tumorigenesis bioassay protocol.

METHODS AND RESULTS

For tumor induction, starting from 3rd week of experimentation, female Balb/c mice received B(a)P intragastric instillations (40 mg/kg bwt) twice a week for 4 weeks. Aqueous A. indica leaf extract (AAILE) was orally administered (100 mg/kg bwt) using blunt-tipped canula on alternate days throughout experimentation. The study was continued for 24 weeks and certain hematological parameters were examined at 4 week intervals. In mice receiving only B(a)P, hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs), lymphocytes and monocytes decreased whereas neutrophils increased when compared to controls. However, A. indica reversed these alterations as seen in mice that received AAILE along with B(a)P when compared to only B(a)P receiving mice. In only AAILE receiving mice, increased Hb, RBCs, WBCs, lymphocytes and monocytes with decreased neutrophils were observed in comparison to control. Also, changes in eosinophils and basophils upon B(a)P exposure and their modulation by AAILE was observed.

CONCLUSIONS

These findings strongly suggested the favorable effects of A. indica on hematological parameters studied and their significance with respect to overall well being, process of tumorigenesis and its chemoprevention have been discussed in the current research manuscript.

Celecoxib mitigates cigarette smoke induced oxidative stress in mice

Cigarette smoke (CS) is a rich source of radicals, predisposing the cell to oxidative stress resulting in inflammation. Chronic inflammation is a recognized risk factor for carcinogenesis. Cyclooxygenase-2 (COX-2) is a mediator of inflammatory pathway and may, therefore, contribute to carcinogenesis. There are several reports that suggest the association between CS and COX-2 associated risk to cancer. In the present study, we examined the role of celecoxib (a selective COX-2 inhibitor) in modulating the oxidative stress caused by CS inhalation in mice. CS exposure for a period of 10 weeks caused oxidative stress in the pulmonary and hepatic tissues, as evident from the increase in lipid peroxidation levels (LPO) and decrease in reduced glutathione (GSH) levels. Celecoxib (125 mg/kg body weight for 8 weeks) administration to CS inhaling mice reduced the oxidative stress by decreasing the LPO levels and enhancing the GSH levels in comparison to the CS-exposed group. CS exposure repressed the enzymatic antioxidant defense system, as evident from the decrease in catalase (CAT) and superoxide dismutase (SOD) activities. Co-adminstration of celecoxib considerably reversed the changes in the enzymatic antioxidant defense system. Histopathological studies of lungs showed that CS exposure induced alveolar wall destruction and air space enlargement. In co-treated group, the alveolar septa were thicker than normal with apparent infiltration of inflammatory cells. In CS-exposed group, hepatic tissue exhibited vacuolization and macrophage infiltration. Co-treatment with celecoxib restored the normal histoarchitechture in hepatic tissues of CS inhaling mice. Thus, the present study demonstrated that celecoxib adminstration reduced the oxidative stress-mediated risk to carcinogenesis, due to its ability to boost the antioxidant defense system.

Chemopreventive activity of Azadirachta indica on two-stage skin carcinogenesis in murine model

The present study reports the chemopreventive activity of aqueous Azadirachta indica leaf extract (AAILE) in a murine two-stage skin carcinogenesis model. Skin tumors were induced by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) (500 nmol/100 µL for 2 weeks) followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) (1.7 nmol/100 µL of acetone, twice weekly) as a promoter. Male LACA mice were divided into four groups: control, DMBA/TPA, AAILE and AAILE + DMBA/TPA. AAILE was administered orally at a dose level of 300 mg/kg body weight thrice a week for 20 weeks. 100% tumor incidence was observed in the DMBA/TPA treated animals, whereas the AAILE + DMBA treated animals exhibited a tumor incidence of 58.3% only. A significant reduction in the mean tumor burden (54.5%) and mean tumor volume (45.6%) was observed in the mice that received AAILE along with DMBA/TPA. Topical application of DMBA/TPA to the skin resulted in well-developed carcinomas associated with decreased expression of pro-apoptotic protein such as caspase 3 and enhanced expression of antiapoptotic protein such as bcl-2 when compared with the control counterparts. However, adminstration of AAILE inhibited skin carcinogenesis with induction of pro-apoptotic proteins such as bax, caspase 3, caspase 9 and inhibition of antiapoptotic proteins such as bcl-2. These results suggest that the induction of apoptosis may be one of the mechanisms underlying the chemopreventive effects of A. indica.

Anti-clastogenic activity of Azadirachta indica against benzo(a)pyrene in murine forestomach tumorigenesis bioassay

Abstract: Present study evaluated the anti-clastogenic efficacy of Azadirchta indica (A. indica) against benzo(a)pyrene [B(a)P] in murine forestomach tumorigenesis bioassay protocol. Female Balb/c mice were divided into four groups (n = 8). Each mouse from B(a)P and B(a)P + A. indica groups received intragastric instillations of B(a)P at a dose of 40 mg/kg b. w. in 0.2 mL olive oil twice a week, starting from 3rd week to the end of 6th week of the experiment. Mice of control and A. indica groups received 0.2 mL olive oil in the same schedule as for B(a)P and B(a)P + A indica groups. Mice of A. indica and B(a)P + A. indica groups received oral doses of 100 mg/kg b. w. aqueous A. indica leaf extract (AAILE) on alternate days throughout the experiment. Two weeks after the last B(a)P instillation, mice were sacrificed and spleens were processed for micronucleus (MN) assay, while liver tissues were analyzed for lipid peroxidation (LPO), as well as antioxidant defense enzymes, namely: catalase, superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx). The incidence of MN formation increased in spleen cells of mice that received only B(a)P instillations. In hepatic tissues, the extent of oxidative stress increased upon B(a)P instillations as was evidenced from enhanced LPO levels with concomitant decrease in antioxidant defense enzyme activities in mice that received only B(a)P instillations. Interestingly, A. indica treatment significantly reversed these effects as observed in mice receiving AAILE along with B(a)P when compared to only B(a)P receiving mice. Moreover, in only AAILE receiving mice, enhanced antioxidant defense with slightly decreased levels of LPO as well as MN incidences were observed. Observations of the present study suggest that A. indica exert anticlastogenic effects against B(a)P by modulating oxidative stress and antioxidant defense.

Subjective evaluation of intraoperative performance of DisCoVisc in complex ocular environments

PURPOSE

To subjectively evaluate the intraoperative characteristics of DisCoVisc during phacoemulsification in complex ocular environments.

PATIENTS AND METHODS

In this prospective observational study, two experienced surgeons (ARV and CZ) performed phacoemulsification on 100 consecutive patients with cataract associated with complex ocular environments. Inclusion criteria were eyes with shallow anterior chambers (anterior chamber depth (ACD) of <2.1 mm), inadequate pupillary dilation (3 mm), dense cataract, and white mature cataract. The surgeons subjectively assessed the endpoints at each phase of phacoemulsification and various behavioural aspects of the ophthalmic viscosurgical devices (OVDs) were subsequently evaluated.

RESULTS

The distribution was as follows: eyes with white mature cataract (n=18), eyes with grades 4 and 5 cataract (n=56), eyes with co-existing shallow ACD <2 mm (n=24), and co-existing small pupil size <2 mm (n=18). DisCoVisc behaved like a moderately cohesive viscoelastic in 94% of the cases. Injection of viscoelastic was easy in 38 (38%) eyes and very easy in 62 (62%) eyes. Visualization after the viscoelastic injection was excellent in 74% of the eyes. During phacoemulsification, DisCoVisc was moderately dispersive at all the stages of emulsification. The bag maintenance during IOL implantation was excellent in 56% eyes; IOL implantation was easy in 26% of the eyes and difficult in 20% of the eyes. Surgeons found viscoelastic removal easy in 68% of the eyes. At the time of OVD removal, DisCoVisc behaved like both a dispersive and a cohesive viscoelastic in 96% of the eyes.

CONCLUSION

DisCoVisc provides both cohesive and dispersive properties. DisCoVisc alone, even in complex ocular environments, enabled the surgeon to achieve good intraoperative performance.

Lycopene mediated modulation of 7,12 Dimethlybenz (a) anthracene induced hepatic clastogenicity in male Balb/c mice

The present study was designed to evaluate the modulatory effects of lycopene against 7, 12 Dimethylbenz (a) anthracene induced clastogenicity and oxidative stress in male Balb/c mice. The animals were divided into four groups; group I served as control (vehicle treated). Animals of group III and IV were administered lycopene orally at a dose of 4 mg/kg body weight for 10 weeks. Groups II and IV were administered DMBA, i.p., at a dose level of 40 mg/kg body weight, 48 hrs before the sacrifice of animals. Exposure to DMBA clearly induced hepatic cell injury as was evident by an increase in micronucleated cell score, lactate dehydrogenase and alkaline phosphatase activities, and Lipid Peroxidation levels. When the lycopene pre-treated animals were challenged with DMBA, a decrease in micronucleated cell score was observed, which was in corroboration with the observed decrease in LDH and ALP activities and LPO levels. DMBA treatment caused an increase in the oxidative stress with consequent alterations in enzymatic antioxidant defense system. Lycopene pre-treatment boosted the antioxidant defense in group IV. Thus, the antioxidant role of lycopene could be plausible in the protective action conferred by lycopene, enabling it to be used an effective natural free radical scavenger.

Celecoxib administration exhibits tissue specific effect on 3H-benzo(a)pyrene-DNA adduct formation in cigarette smoke inhaling mice

In the present study, cigarette smoke (CS) exposure significantly enhanced 3H-B(a)P-DNA adduct formation in both the pulmonary and hepatic tissues. Mice co-treated with CS and celecoxib (a specific COX-2 inhibitor) exhibited a significant decrease in hepatic carcinogen-DNA adduct formation in comparison to the smoke exposed group, however the lungs of the co-treated animals exhibited a significant increase in carcinogen-DNA adduct formation when compared to the control group and smoke exposed group. CS exposure enhanced the activity of carcinogen activation enzymes in both the tissues and decreased the activity of carcinogen detoxification enzymes in the hepatic tissue only, when compared to the control group. Celecoxib administration to CS inhaling mice modulated the carcinogen biotransformation considerably when compared to the CS exposed group. Celecoxib administration to CS inhaling mice produced a low index of carcinogenesis in the hepatic tissue but increased the index of carcinogenesis in the pulmonary tissue. These observations seem to be critical and tissue specific when related to carcinogenesis.

Azadirachta indica modulates carcinogen biotransformation and reduced glutathione at peri-initiation phase of benzo(a)pyrene induced murine forestomach tumorigenesis

The present study evaluated the effects of aqueous Azadirachta indica leaf extract (AAILE) on the activities of certain phase I (cytochrome P450, cytochrome b(5) and aryl hydrocarbon hydroxylase) as well as phase II (glutathione-S-transferase and UDP-glucuronosyl transferase) biotransformation enzymes; and reduced glutathione (GSH) (in forestomach and hepatic tissues) during/after intra-gastric instillations of B(a)P in murine forestomach tumorigenesis bioassay protocol. The activities of phase I biotransformation enzymes were found to increase, whereas a decrease in GSH content as well as glutathione-S-transferase was observed in mice receiving only B(a)P during as well as 2 weeks after B(a)P instillations. The activity of UDP-glucuronosyltransferase decreased during B(a)P instillations, whereas after the latter, the activity increased when compared with the control mice. However, in mice that received AAILE along with B(a)P instillations, a decrease in phase I enzymes was accompanied by an increase in phase II enzymes as well as GSH contents. Only AAILE treatment reduced the activities of phase I biotransformation enzymes and enhanced the GSH contents as well as the activities of phase II enzymes. Observations of the present study seem to be quite significant and (when taken together with our earlier findings) provides evidence for A. indica mediated modulation of the peri-initiation phase of the process of forestomach tumorigenesis.

Inhibition of endotoxin-induced hepatotoxicity by melatonin in rats

Bacterial endotoxin or lipopolysaccharide causes extensive damage to various organs including the liver. This is due to an increased production of tumor necrosis factor α induced- reactive intermediates. These intermediates are known to cause extensive damage to a variety of cellular biomolecules leading to oxidative stress. In the present study, the role of the pineal hormone melatonin was evaluated as an antioxidant against endotoxin induced- hepatotoxicity using Wistar rats. Bacterial endotoxin was injected (i.v) and animals were sacrificed 8h post-challenge. Endotoxemia was associated with a statistically significant rise in the serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and also caused histopathological changes. Administration of melatonin could significantly attenuate these enzymatic and associated histological alterations. Melatonin was administered (i.p) pre and/or post endotoxin challenge. A significant reduction in the levels of malondialdehyde and tumor necrosis factor-α in the hepatic tissue was also observed with melatonin supplementation. Reduction in the levels of endogenous antioxidants such as superoxide dismutase, catalase and reduced glutathione after endotoxin challenge was effectively attenuated by the administration of melatonin. Endotoxin challenge caused a marked increases in the levels of nitrite, and this was significantly lowered by melatonin administration. The above mentioned changes might have resulted in endotoxin associated hepatocellular necrosis which was minimized by melatonin supplementation in the present study.

Interaction between the UCP2-866G/A, mtDNA 10398G/A and PGC1alpha p.Thr394Thr and p.Gly482Ser polymorphisms in type 2 diabetes susceptibility in North Indian population

In the recent past, we have observed a possible role of 10398A and 16189C mtDNA and PGC1alpha p.Thr394Thr (rs2970847) and p.Gly482Ser (rs8192673) variant genotypes providing susceptibility/protection against type 2 diabetes mellitus (T2DM) in two North Indian population groups. These initial observations encouraged us to look at the candidate genes in combination with -866G/A (rs659366) polymorphism in uncoupling protein 2 (UCP2) in a single study of a relatively large sample size, constituted of both the cohorts, to unravel an interesting outcome of an additive interaction in-between the studied genes. In a total of 1,686 individuals (762 cases and 924 controls) belonging to Indo-European linguistic group from North India, a comparison of risk genotype combinations of: UCP2-866GG, mtDNA 10398A and PGC1alpha p.Thr394Thr or p.Gly482Ser against the protective genotypes: UCP2-866XA, mtDNA 10398G and PGC1alpha p.Thr394Thr (nominal P value = 1.75 x 10(-14), Odds ratio, OR = 5.29, 3.40-8.22 at 95% CI) or PGC1alpha p.Gly482Ser (nominal p value = 4.42 x 10(-24), OR = 8.59, 5.53-13.35 at 95% CI), showed a highly significant difference and increased ORs. In a complex disease, it is always encouraging to find an additive interaction of multiple small effects of the studied candidate gene variations.

Azadirachta indica leaf extract modulates initiation phase of murine forestomach tumorigenesis

The effects of aqueous Azadirachta indica leaf extract (AAILE) on benzo(a)pyrene [B(a)P]-induced forestomach tumorigenesis, B(a)P-DNA adduct formation and certain parameters of carcinogen biotransformation system in mice have been reported earlier from our laboratory. In this study, the effects of AAILE on the enzymes of B(a)P biotransformation, which play crucial role in initiation of chemical carcinogenesis - aryl hydrocarbon hydroxylase (AHH) and uridinediphosphoglucuronosyltransferase (UDP-glucuronosyltransferase) have been evaluated in murine forestomach and liver. In addition, lipid peroxidation (LPO) levels in forestomach as well as liver and the activities of tissue injury marker enzymes - lactate dehydrogenase, aspartate aminotransferase and alkaline phosphatase in the serum have also been evaluated. Oral administration of AAILE (100 mg/kg body wt for 2 weeks) reduces the AHH activity and enhances the UDP-glucuronosyltransferase activity in both the tissues, suggesting its potential in decreasing the activation and increasing the detoxification of carcinogens. The LPO levels decrease upon AAILE treatment in the hepatic tissue, suggesting its antioxidative and hence anti-carcinogenic effects. Non-significant alterations have been observed in tissue injury marker enzymes upon AAILE treatment, suggesting its safety at the given dose. In conclusion, AAILE appears to modulate initiation phase of carcinogenesis and may be suggested as safe and an effective agent for chemoprevention.

Impediment of diethylnitrosamine induced hepatotoxicity in male Balb/c mice by pretreatment with aqueous Azadirachta indica leaf extract

Considering the hepatoprotective properties of Azadirachta indica, the present study was designed to evaluate its preventive effects against diethylnitrosamine (NDEA) induced hepatotoxicity in male Balb/c mice. Exposure of NDEA caused a significant increase in micronucleated cell score, lipid peroxidation levels (LPO) and activity of lactate dehydrogenase (LDH). A significant decrease in reduced glutathione (GSH) contents and activity of glutathione-S-transferase (GST) was also observed upon NDEA treatment, whereas their activities of cytochrome P450 and cytochrome b5 showed non-significant alterations. Aqueous A. indica leaf extract (AAILE) pretreatment showed protective effects against NDEA induced toxicity by decreasing the frequency of micronucleated cell, levels of LPO and LDH activity. Also, a decreased activity of GST, cytochrome P450 and an increased activity of cytochrome b5, GSH contents was observed when AAILE pretreated mice were injected with NDEA. Only AAILE treatment caused a noticeable decrease in the frequency of micronuclei, activity of cytochrome P450 and cytochrome b5, but a significant increase in the activity of GST and GSH contents, whereas, non significant alterations were observed in the activity of LDH and levels of LPO. Significance of these observations with respect to hepatoprotective efficacy of A. indica has been discussed in the present manuscript.

Preventive effects ofAzadirachta indicaon benzo(a)pyrene-DNA adduct formation in murine forestomach and hepatic tissues

In the present investigation, the effects of aqueous Azadirachta indica leaf extract (AAILE) on (3)H-benzo(a)pyrene-DNA [(3)H-B(a)P-DNA] adduct formation, the status of biotransformation enzymes and reduced glutathione (GSH) content were evaluated in the forestomach and liver of Balb/c mice. Two weeks of AAILE treatment reduced the (3)H-B(a)P-DNA adduct levels by 31.6% in forestomach tissue. Similarly, (3)H-B(a)P-DNA adduct levels were decreased by 34.7% in the liver of AAILE treated mice compared with their control counterparts. After AAILE treatment, the cytochrome P450 content decreased, whereas the GSH content increased significantly in the hepatic tissue. In the forestomach as well as in the liver, the cytochrome b5 content declined, whereas an increase in glutathione-S-transferase (GST) activity was observed in both tissues. These observations suggested that AAILE may have reduced the metabolic activation of (3)H-B(a)P with enhanced detoxification of its active metabolites, hence the observed decrease in the levels of (3)H-B(a)P-DNA adducts. These molecular and biochemical modulations observed at the initiation phase of carcinogenesis seems to be significant and could be correlated with the chemopreventive effects of A. indica against B(a)P induced forestomach tumorigenesis.

Inhibition of early and late phase allergic reactions by Euphorbia hirta L

A 95% ethanol extract from whole aerial parts of Euphorbia hirta (EH A001) showed antihistaminic, antiinflammatory and immunosuppressive properties in various animal models. EH A001 inhibited rat peritoneal mast cell degranulation triggered by compound 48/80. It significantly inhibited dextran-induced rat paw edema. EH A001 prevented eosinophil accumulation and eosinophil peroxidase activity and reduced the protein content in bronchoalveolar lavage fluid (BALF) in a 'mild' model of asthma. Moreover, the CD4/CD8 ratio in peripheral blood was suppressed. EH A001 attenuated the release of interleukin-4 (IL-4) and augmented interferon-gamma (IFN-gamma) in ovalbumin-sensitized mouse splenocytes. The results were compared with the effects of known compounds, ketotifen, cetirizine and cyclophosphamide. These findings demonstrated that Euphorbia hirta possessed significant activity to prevent early and late phase allergic reactions.

Chemomodulatory effects of Azadirachta indica on the hepatic status of skin tumor bearing mice

The liver plays an important role in the modulation of the process of carcinogenesis, as it is the primary site for the biotransformation of xenobiotics including carcinogens as well as anticancer drugs. The present study was designed to evaluate the biochemical alterations occurring in the liver of 7,12-dimethylbenz(a)anthracene (DMBA) induced skin tumor bearing male Balb/c mice and their modulation by aqueous Azadirachta indica leaf extract (AAILE). It was observed that skin tumor induction caused hepatic damage characterized by a decreased hepatosomatic index and significantly increased (p < 0.001) activities of the hepatic tissue injury marker enzymes, namely alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. However, upon treatment with AAILE, the above-mentioned alterations, including the increased activities of hepatic tissue injury marker enzymes, were significantly reversed, which signified the hepato-protective efficacy of Azadirachta indica. Increased oxidative stress was also observed in the hepatic tissue of skin tumor bearing mice as revealed by a significant increase (p < 0.001) in lipid peroxidation levels and a decrease in reduced glutathione contents and activities of various antioxidant enzymes studied, namely glutathione-S-transferase, glutathione peroxidase and glutathione reductase. The AAILE treatment reduced oxidative stress by decreasing lipid peroxidation levels and enhancing the reduced glutathione contents and activities of various antioxidant enzymes. The activities of the xenobiotic biotransformation enzymes, namely cytochrome P450, cytochrome b5 and glutathione-S-transferase, were found to be decreased in the hepatic tissue of tumor bearing mice. Treatment with AAILE further caused a decrease in the activity of cytochrome P450 and cytochrome b5, whereas it up-regulated the activity of glutathione-S-transferase. The significance of these observations with respect to the progress of the process of carcinogenesis is explained in the present research article.

Are the increases in local tumour necrosis factor and lipid peroxidation observed in pre-starved mice infected with Salmonella typhimurium markers of increased liver damage?

Pathogenic microorganisms are known to sense and process signals within their hosts, including those resulting from starvation. Therefore, an attempt was made to evaluate the extent and the possible underlying mechanism of Salmonella typhimurium-induced hepatic damage using pre-starved laboratory mice. The following parameters were analysed, comparing control, fed infected, starved, and starved infected mice: the bacterial load in the liver, fluctuations in liver-derived enzymes alanine-aminotransferase and aspartate-aminotransferase, histopathological changes, lipid peroxidation as well as estimation of reduced glutathione, superoxide dismutase and catalase, along with the TNF content in livers. The number of bacterial cells recovered from starved infected livers at 3 days post-S. typhimurium inoculation was comparable to the number recovered from fed infected livers at 5 days post-Salmonella inoculation, indicating an early increase in the development of the bacteria in starved mice. A marked elevation in liver-derived enzymes in mouse serum and significant histopathological changes are markers of liver damage of higher amplitude in starved infected mice. Analysis of the liver indicated a significant increase in lipid peroxidation in starved infected mice compared to their control counterparts, a process coupled with increased TNF level. Although the reduced glutathione levels showed a marked increase in the starved infected mice, there was a significant decrease in superoxide dismutase and catalase activities in this group.

Modulatory effects of Azadirachta indica on benzo(a)pyrene-induced forestomach tumorigenesis in mice

AIM

To evaluate the chemopreventive effects of aqueous Azadirachta indica (A indica) leaf extract (AAILE) against benzo(a)pyrene [B(a)P]-induced forestomach tumorigenesis in Balb/c mice.

METHODS

Female Balb/c mice were divided into four groups of 10-12 animals each. For induction of forestomach tumors, starting from d 14 of the experi-ment, mice of B(a)P and B(a)P+A indica groups were given intra-gastric instillations of B(a)P (40 mg/kg), twice a week for four weeks. Mice of A indica and B(a)P+A indica groups were orally administered with AAILE (100 mg/kg), two weeks prior to B(a)P instillations till the end of the experiment. After 22 wk of the first B(a)P instillation, mice were sacrificed and the forestomachs were analyzed for development of tumors, scanning electron microscopy (SEM) and histopathology.

RESULTS

Tumor incidence was observed to be 100% in mice that received only B(a)P. However, treatment with AAILE reduced the tumor incidence by 58.4% as observed in mice of B(a)P+A indica group when compared to that of B(a)P group. Similarly, the tumor burden and multiplicity were seen to decrease by 87.3% and 69.6% respectively in mice of B(a)P+A indica group when compared to those of B(a)P group. Scanning electron microscopy analysis showed that AAILE treatment itself did not cause any abnormalities on the surface architecture of forestomach epithelium. In tumorous forestomach, surface disruption was observed. Over the forestomach tumors of B(a)P group of mice certain rounded structures were seen in addition to closely placed tongue-shaped squamous cells. Interestingly, these rounded structures were not observed in B(a)P + A indica group of mice. Histopathalogically, the tumors were identical and diagnosed to be papillomas. Mice from control and A indica groups of mice did not develop any forestomach tumors and showed normal histo-architecture.

CONCLUSION

The present data suggest that A indica exerts chemopreventive effects against B(a)P-induced forestomach tumors in murine model. Because of lack of toxicity and ubiquitous bioavailability, A indica may play a promising role in future drug discovery and development as far as chemoprevention of cancer is concerned.

Inhibitory effects of Azadirachta indica on DMBA-induced skin carcinogenesis in Balb/c mice

Male Balb/c mice were divided into four groups on the basis of their respective treatments wherein mice of Group I served as controls. For induction of skin tumors, mice of Group II and IV were injected sub-cutaneously with 7,12-dimethylbenz(a)anthracene (DMBA). Mice of Group III and IV were administered aqueous Azadirachta indica leaf extract (AAILE) thrice a week throughout the experiment. After 14 weeks of the first DMBA injection, Group II and IV mice developed tumors. In the tumor-bearing mice that received AAILE (Group IV), a significant reduction in mean tumor burden and tumor volume was observed. The tumors were confirmed to be papillomas and interestingly, the extent of hyper-chromatia was observed to be much more in skin tumors of Group II mice vis a vis the mice receiving AAILE. An increase in the extent of lipid peroxidation was observed in tumorous tissue of Group IV when compared to that of Group II mice. Glutathione (GSH) content and the activities of GSH-based antioxidant enzymes viz. glutathione peroxidase (GPx) and glutathione reductase (GR) increased significantly in the skin tissues of all the groups of mice when compared to control counterparts. Catalase activity was found to decrease significantly in the skin of mice, which received AAILE treatment only (Group III). Activity of super-oxide dismutase (SOD) decreased significantly in all the tumorous tissues (Group II and IV mice). In light of the above observations, the role of AAILE in inhibition of DMBA-induced skin carcinogenesis is discussed in the present study.

Modulatory effects of different doses of alpha-tocopherol on benzo(a)pyrene-DNA adduct formation in the pulmonary tissue of cigarette smoke inhaling mice

Cigarette smoke (CS) has been established as one of the major risk factors for many pathologies including lung cancer in humans and experimental animals. In view of the discrepancy about the role of alpha-tocopherol (AT) in carcinogenesis, the present study was designed to investigate the effects of different doses of AT on benzo(a)pyrene-DNA [B(a)P-DNA] adduct formation in lungs of CS inhaling mice. Extent of carcinogen-DNA adduct formation has been considered as an index for carcinogenesis. Feeding of 35 IU AT/kg body weight increased B(a)P-DNA adducts formation significantly whereas feeding of 5 IU AT/kg body weight did not altered much the B(a)P-DNA adduct levels when both were compared to the control counterparts. With CS inhalation, the B(a)P-DNA adducts formation increased in all the groups when compared to their respective sham counterparts. Interestingly, in CS exposed groups, there was least increase in B(a)P-DNA adducts formation in 5 IU AT/kg fed animals followed by the control and 35 IU AT/kg body weight fed groups respectively. The results suggest that higher doses of AT accentuate DNA adduct formation in CS inhaling mice.

Role of Salmonella surface components in immunomodulation of inflammatory mediators

Salmonella enterica serovar Typhimurium and its surface components were assessed for their inflammatory potential by footpad oedema test using plethysmometer. Inflammation was found to be the highest when outer membrane proteins (OMPs) were used as inflammagen followed by lipid associated protein-lipopolysaccharide complex (LAP-LPS) and lipopolysaccharides (LPS). Inflammation produced by OMPs was found to be comparable to that by carrageenan (a known positive inflammagen). However, injection of L-histidine (an antioxidant) prior to administration of carrageenan or Salmonella enterica serovar Typhimurium inhibited the inflammation, which indicated the involvement of oxidants during inflammatory response. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and nitric oxide (NO) production by peritoneal macrophages from infected mice exhibited a significant increase as compared to those of the immunized mice. In contrast, glutathione production was found to be the maximum in the macrophages taken from OMPs-immunized mice followed by LAP-LPS and LPS alone. The biochemical studies correlated well with histopathological studies of intestinal tissue of animals from various groups. Based upon these parameters, inflammation seems to be modulated by OMPs and LAP-LPS, which may be because of the protein moieties present in the components. Hence, immunization with protein moieties having L-histidine or L-histidine-like structures may suggest an alternative to the potential therapeutic values of anti-inflammatory drugs. Thus the results of this study form the basis for evaluating these antigens (either alone or in combination with polysaccharides) for preventive intervention rather than therapeutic.