Middle ear catalase distribution in an animal model of otitis media

Otitis media: recent advances in otitis media vaccine development and model systems

Otitis media is an inflammatory disorder of the middle ear caused by airways-associated bacterial or viral infections. It is one of the most common childhood infections as globally more than 80% of children are diagnosed with acute otitis media by 3 years of age and it is a common reason for doctor's visits, antibiotics prescriptions, and surgery among children. Otitis media is a multifactorial disease with various genetic, immunologic, infectious, and environmental factors predisposing children to develop ear infections. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common culprits responsible for acute otitis media. Despite the massive global disease burden, the pathogenesis of otitis media is still unclear and requires extensive future research. Antibiotics are the preferred treatment to cure middle ear infections, however, the antimicrobial resistance rate of common middle ear pathogens has increased considerably over the years. At present, pneumococcal and influenza vaccines are administered as a preventive measure against otitis media, nevertheless, these vaccines are only beneficial in preventing carriage and/or disease caused by vaccine serotypes. Otitis media caused by non-vaccine serotype pneumococci, non-typeable H. influenza, and M. catarrhalis remain an important healthcare burden. The development of multi-species vaccines is an arduous process but is required to reduce the global burden of this disease. Many novel vaccines against S. pneumoniae, non-typeable H. influenza, and M. catarrhalis are in preclinical trials. It is anticipated that these vaccines will lower the disease burden and provide better protection against otitis media. To study disease pathology the rat, mouse, and chinchilla are commonly used to induce experimental acute otitis media to test new therapeutics, including antibiotics and vaccines. Each of these models has its advantages and disadvantages, yet there is still a need to develop an improved animal model providing a better correlated mechanistic understanding of human middle ear infections, thereby underpinning the development of more effective otitis media therapeutics. This review provides an updated summary of current vaccines against otitis media, various animal models of otitis media, their limitations, and some future insights in this field providing a springboard in the development of new animal models and novel vaccines for otitis media.

Glutathione S-transferase enzyme activity and protein expression in patients with recurrent tonsillitis and idiopathic tonsillar hypertrophy

OBJECTIVES

The palatine tonsil is a significant part of the secondary immune system. Tonsillitis and idiopathic tonsillar hypertrophy (ITH) are the most common pathologies of this component. Although there are studies on their pathogenesis, there is insufficient study of the role of antioxidant agents. Glutathione S-transferase (GST) isozymes contribute to the antioxidation reactions in the tissue via the glutathione pathway. The purpose in this study was to reveal the levels of the GST enzyme activity and protein expression of GSTP1 and GSTA1 isozymes in patients with tonsillitis and tonsil hypertrophy, and to investigate their role in the pathogenesis of these diseases.

MATERIALS AND METHODS

Sixteen patients with recurrent tonsillitis and 5 patients with ITH and were included in the study. Cytosolic extracts were prepared from post-tonsillectomy tissues of both patient groups and GST enzyme activities were measured.

RESULTS

The expression of GSTP1 was found to be significantly higher than GSTA1 in tissue samples of patients with ITH and recurrent tonsillitis (P<0.001). Increased GST activity and GSTP1 isozyme expression were shown in patients with recurrent tonsillitis compared to the idiopathic tonsillar hypertrophy study group. There was a positive correlation between the expressions of GSTP1 (P=0.040; r=0.47).

CONCLUSION

Increased GST activity and GSTP1 isozymes were demonstrated histologically in the pathogenesis of ITH and recurrent tonsillitis. We believe that the data of changes in antioxidant capacity, obtained from studies with more extensive and larger samples, would support our findings.

Animal models of acute otitis media - A review with practical implications for laboratory research

Considerable animal research has focused on developing new strategies for the prevention and treatment of acute otitis media (AOM). Several experimental models of AOM have thus been developed. A PubMed search of the English literature was conducted from 1975 to July 2016 using the search terms "animal model" and "otitis media" from which 91 published studies were included for analysis, yielding 123 animal models. The rat, mouse and chinchilla are the preferred animals for experimental AOM models with their individual advantages and disadvantages. The most common pathogens used to create AOM are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Streptococcus pneumoniae (types 3, 23 and 6A) and non-typeable Haemophilus influenzae (NTHi) are best options for inoculation into rat and mouse models. Adding viral pathogens such as RSV and Influenza A virus, along with creating ET dysfunction, are useful adjuncts in animal models of AOM. Antibiotic prophylaxis may interfere with the inflammatory response without a significant reduction in animal mortality.

Efficacy of topotecan treatment on antioxidant enzymes and TBA-RS levels in submandibular glands of rabbits: An experimental study

OBJECTIVE:

The aim of this study was to investigate the effects of topotecan (Hycamtin), a topoisomerase I inhibiting anticancer agent, on antioxidant enzymes (SOD, CAT, and GSH-Px) and TBA-RS values of the submandibular glands of the rabbits.

STUDY DESIGN AND SETTING:

The study was conveyed in two groups (Group I, II) and control with a total of 24 rabbits. Eight rabbits in group I received intravenous (i.v.) topotecan (0.25 mg/kg once daily) for 3 days. Eight rabbits in group II received i.v. topotecan (0.5 mg/kg once daily) for 3 days. On the 15th day after administration of topotecan, sub-mandibular glands were removed and levels of the SOD, CAT, and GSH-Px and the TBA-RS in the sub-mandibular glands of the rabbits were examined.

RESULTS:

SOD, CAT, and GSH-Px values were significantly higher in high-dose topotecan group compared to control group ( P < 0.05). SOD and TBA-RS values were significantly higher in high-dose topotecan group compared to low-dose topotecan group ( P < 0.05).

CONCLUSION:

It was concluded that, to prevent the hazardous effects of oxygen free radicals due to topotecan, antioxidant enzymes SOD, CAT, and GSH-Px were increased. The higher levels of the TBA-RS values in group II showed that permanent damage was present because of high-dose topotecan administration in the submandibular glands of the rabbits.

Heparin binding-epidermal growth factor-like growth factor for the regeneration of chronic tympanic membrane perforations in mice

We aim to explore the role of epidermal growth factor (EGF) ligand shedding in tympanic membrane wound healing and to investigate the translation of its modulation in tissue engineering of chronic tympanic membrane perforations. Chronic suppurative otitis media (CSOM) is an infected chronic tympanic membrane perforation. Up to 200 million suffer from its associated hearing loss and it is the most common cause of pediatric hearing loss in developing countries. There is a need for nonsurgical treatment due to a worldwide lack of resources. In this study, we show that EGF ligand shedding is essential for tympanic membrane healing as it's inhibition, with KB-R7785, leads to chronic perforation in 87.9% (n=58) compared with 0% (n=20) of controls. We then show that heparin binding-EGF-like growth factor (5 μg/mL), which acts to shed EGF ligands, can regenerate chronic perforations in mouse models with 92% (22 of 24) compared with 38% (10 of 26), also with eustachian tube occlusion with 94% (18 of 19) compared with 9% (2 of 23) and with CSOM 100% (16 of 16) compared with 41% (7 of 17). We also show the nonototoxicity of this treatment and its hydrogel delivery vehicle. This provides preliminary data for a clinical trial where it could be delivered by nonspecialist trained healthcare workers and fulfill the clinical need for a nonsurgical treatment for chronic tympanic membrane perforation and CSOM.

Effect of orange peel essential oil on oxidative stress in AOM animals

The processing parameters of pump speed, inlet air temperature, outlet air temperature and homogenization pressure were evaluated. Encapsulation efficiency is high with a satisfied releasing rate. Then, acute otitis media (AOM) animal model was built and diet containing orange peel essential oil microcapsules were administrated to AOM animals. Pharmacological test showed that orange peel essential oil treatment could decrease serum and cochlea malondialdehyde (MDA), immunoglobulins A (IgA), immunoglobulins G (IgG), immunoglobulins M (IgM) levels and increase antioxidant enzymes activities. It can be concluded that orange peel essential oil treatment could decrease oxidative injury in acute otitis media rats.

Catalase as a source of both X- and V-factor for Haemophilus influenzae

Haemophilus influenzae requires two growth factors, designated factor X (porphyrin) and factor V (NAD). Mammalian catalases contain both bound heme and NADPH. This study shows that catalase can supply both factors X and V to H. influenzae in vitro, thus representing a potential in vivo source of these essential growth factors.

Oxidative stress and enzymic–non-enzymic antioxidant responses in children with acute pneumonia

In this article, oxidative stress and enzymic-non-enzymic antioxidants status were investigated in children with acute pneumonia. Our study included 28 children with acute pneumonia and 29 control subjects. The age ranged from 2 to 11 years (4.57+/-2.13 years) and 2 to 12 years (4.89+/-2.22 years) in the study and control groups, respectively. Whole blood malondialdehyde (MDA) and reduced glutathione (GSH), serum beta-carotene, retinol, vitamin C, vitamin E, catalase (CAT), ceruloplasmin (CLP), total bilirubin, erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels were studied in all subjects. There was a statistically significant difference between the groups for all parameters except for serum CAT. Whole blood MDA, serum CLP and total bilirubin levels were higher in the study group than those of the control group. However, SOD, GPx, beta-carotene, retinol, vitamin C, vitamin E and GSH levels were lower in the study group compared with the control group. All antioxidant vitamin activities were decreased in children with acute pneumonia. Our study demonstrated that oxidative stress was increased whereas enzymic and non-enzymic antioxidant activities were significantly decreased in children with acute pneumonia.

Oxidants and antioxidants in tonsillar and adenoidal tissue in chronic adenotonsillitis and adenotonsillar hypertrophy in children

OBJECTIVE

The aim of the study is to determine the possible role of oxidants and antioxidants in the pathogenesis of chronic adenotonsillitis and adenotonsillar hypertrophy in children.

PATIENTS AND METHODS

The children were divided into infection and hypertrophy groups, which were comparable according to age and gender distribution. The infection group was consisted of 20 children with the diagnosis of chronic adenotonsillitis and the hypertrophy group was made up of 19 children with adenotonsillar hypertrophy to whom adenotonsillectomy was performed. Preoperative blood levels of erythrocyte MDA, serum MDA, erythrocyte catalase and serum catalase, and adenoidal and tonsillar tissue levels of MDA and catalase were studied.

RESULTS

There were significant increase in tonsil MDA, adenoid MDA, tonsil catalase and adenoid catalase levels in infection group (p<0.05).

CONCLUSION

Oxidants and antioxidants are found to have an important role in the pathogenesis of adenotonsillar hypertrophy and chronic adenotonsillitis. These findings strengthen the hypothesis that indicates adenotonsillar hypertrophy and chronic adenotonsillitis are different diseases of the same tissues.

Investigation of antioxidant status in children with acute otitis media and tonsillitis

OBJECTIVE

Antioxidant enzymes status was investigated in children with acute otitis media (AOM) and acute tonsillitis. The aim was to determine the effect of oxidative damage due to free radicals on the antioxidant enzymes status in children with AOM and acute tonsillitis.

METHODS

We measured erythrocyte levels of superoxide dismutase and glutathione peroxidase (GPx) and activity of serum catalase, ceruloplasmin, albumin and total bilirubin in 23 children with AOM, 27 with acute tonsillitis and 17 control subjects.

RESULTS

There was statistically significant difference between the groups for all parameters. All antioxidant activities except for albumin level were increased in the studies groups. When the values of AOM and acute tonsillitis were compared, there was statistically significant difference between the groups for erythrocyte GPx.

CONCLUSION

Our findings indicate that not only a few antioxidant enzymes but almost all antioxidant activities showed a significant enhancement in children with AOM and acute tonsillitis.

The effect of local administration of N-acetylcysteine in perforated rat tympanic membrane: an experimental study in myringosclerosis

Myringosclerosis (MyS) is a common sequela of acute and chronic otitis media and ventilation tube treatment of serous otitis media. We aimed to study the effect of topical administration of N -acetylcysteine (NAC) on MyS by assessment of otomicroscopic evaluation, lipid peroxidation and nitric oxide (NO) (nitrite/nitrate) levels in experimental myringotomized rat tympanic membrane. Thirty adult rats were used and the upper posterior quadrant of the tympanic membranes of rats was myringotomized. Thereafter, they were divided into four groups. Group I received no treatment, group II was treated with saline, groups III and IV were treated with topical NAC (0.1 ml of 6 and 12 mg ml(-1), respectively). The levels of nitrite/nitrate and malondialdehyde (MDA) were measured in serum samples. In the otomicroscopic evaluation, non-treated and saline treated ears (controls) showed extensive occurrence of myringosclerotic plaques. Groups III and IV showed fewer occurrences of sclerotic plaques. There was no significant difference between groups III and IV regarding the development of MyS. The development of myringosclerotic lesion was found to be significantly different between NAC treated groups (III and IV) and the control groups (I and II). The levels of nitrite/nitrate of both groups III and IV were significantly lower than the control groups. The levels of MDA of these groups were also significantly lower than the control group. The relationship between groups III and IV was not statistically significant for the levels of nitrite/nitrate and MDA. We conclude that the topical treatment of NAC reduces the levels of MDA and NO products in rats. These results suggest that topical NAC application may be useful for the prevention of MyS.

Interaction of pyridostigmine and physical stress on antioxidant defense system in skeletal muscle of mice

Pyridostigmine bromide (PB), a reversible anticholinesterase drug, had been used against possible nerve gas exposure during the Persian Gulf War. The Gulf War veterans used PB and they were under physical stress. This study investigated the delayed and interactive effects of pyridostigmine and physical stress on the antioxidant defense system in triceps muscle of mice. Male NIH Swiss mice were divided into four groups and treated as follows: sedentary control; pyridostigmine (1.2 mg kg(-1) p.o.); exercise; and PB plus exercise. Mice were exercised for 10 weeks, but PB was administered daily during the 5th and 6th weeks. Mice were sacrificed 24 h after the last treatments and the triceps muscle was isolated and analyzed. There was a significant increase in total superoxide dismutase (CuZn-SOD + Mn-SOD) activity (141% of control) with PB plus exercise, suggesting that any influx of superoxide anions was scavenged efficiently. The Mn-SOD enzyme protein levels were reduced significantly (63% of control) by PB plus exercise. Catalase enzyme protein levels were increased significantly by exercise (132% of control) as well as by PB plus exercise (139% of control). Glutathione levels were increased significantly by exercise alone (123% of control). Pyridostigmine bromide plus exercise significantly increased the malondialdehyde concentration (124% of control) in the triceps muscle, indicating an oxidative stress response of the combination. The data indicate that a combination of PB ingestion and exercise training significantly altered the antioxidant enzyme activities, enzyme protein levels and lipid peroxidation, leading to oxidative injury. Physical stress amplified the delayed effects of PB in the skeletal muscle of mice.

Lipoperoxidation as a measure of free radical injury in otitis media

Free radical damage, as evidenced by lipoperoxidation, has previously been demonstrated to contribute to the inflammatory changes associated with acute otitis media. The present study was undertaken to evaluate whether lipoperoxidation continues to be present for a period of time after middle ear infection. Eighty-two 300- to 400-g guinea pigs were injected with Streptococcus pneumoniae in the left ear and sterile saline in the right ear as a control. Animals were examined and sacrificed on day 5, 10, 20, or 30; middle ear mucosa was harvested and assayed for lipid hydroperoxide content. A statistically significant increase in lipoperoxidation was seen at each time point studied, compared with controls. Lipoperoxidation was highest at days 5 and 10; a significant decrease was seen at days 20 and 30. Histologic sections of middle ear mucosa of two animals per group were prepared and evaluated for inflammation. These results demonstrate that lipoperoxidation may contribute to middle ear inflammation for a significant period of time after acute infection; the findings are discussed in light of other work on the role of free radicals in otitis media.

Effects of 21-aminosteroid U-74389G on acute otitis media in a guinea pig model

Free radicals participate in the development of disease under inflammatory conditions. Lipid peroxides such as malondialdehyde are regarded as markers of cell membrane damage by oxidative stresses. Previous work from our laboratory has demonstrated that lipidperoxidation is increased in acute otitis media in guinea pigs, implicating a role for free radicals as contributors to inflammation. In this study we examined the effect of lazaroid U-74389G, a 21-aminosteroid, on acute otitis media in guinea pigs. Streptococcus pneumoniae organisms were inoculated into the right tympanic cavity; sterilized phosphate-buffered saline solution was injected into the left ear to serve as a control. The guinea pigs were given intraperitoneal injections of 40 mg/kg of a lazaroid compound or its vehicle every 12 hours. Middle ear mucosa was collected and used for assay. We quantified lipid peroxide by means of the methylene blue-hemoglobin method and by means of measurement of thiobarbituric acid reactive substance. Lazaroid significantly (p < 0.05) suppressed production of lipid hyproperoxide of the middle ear mucosa of the guinea pigs with acute otitis media for up to 24 hours. These results suggest that lazaroid may reduce lipoperoxidation in the middle ear at an early stage of acute otitis media.

Hydrogen peroxide in acute otitis media in guinea pigs

Evidence has emerged that oxygen free radicals contribute to middle-ear mucosa damage in acute otitis media (AOM). Streptococcus pneumoniae is the most common pathogen in AOM and produces hydrogen peroxide, a free radical intermediate, as it grows. To better characterize the mechanism of free radical damage in AOM, an experiment was conducted to examine the production of hydrogen peroxide. Thirty-two guinea pigs were injected transtympanically with bacteria in the left (infected) middle ear and sterile saline into the right (control) middle ear. Middle-ear fluid was removed and analyzed for quantity of hydrogen peroxide. Results indicated significantly greater hydrogen peroxide levels in infected versus control middle-ear fluid at 6, 12, and 24 h. Likely sources of hydrogen peroxide include both the neutrophil response to infection and pneumococcal growth and death.