Decrease in catalase activity of cultured cells by Mycoplasma gallisepticum infection

Mycoplasma hominis Causes DNA Damage and Cell Death in Primary Human Keratinocytes

Mycoplasma hominis can be isolated from the human urogenital tract. However, its interaction with the host remains poorly understood. In this study, we aimed to assess the effects of M. hominis infection on primary human keratinocytes (PHKs). Cells were quantified at different phases of the cell cycle. Proteins involved in cell cycle regulation and apoptosis progression were evaluated. The expression of genes encoding proteins that are associated with the DNA damage response and Toll-like receptor pathways was evaluated, and the cytokines involved in inflammatory responses were quantified. A greater number of keratinocytes were observed in the Sub-G0/G1 phase after infection with M. hominis. In the viable keratinocytes, infection resulted in G2/M-phase arrest; GADD45A expression was increased, as was the expression of proteins such as p53, p27, and p21 and others involved in apoptosis regulation and oxidative stress. In infected PHKs, the expression of genes associated with the Toll-like receptor pathways showed a change, and the production of IFN-γ, interleukin (IL) 1β, IL-18, IL-6, and tumour necrosis factor alpha increased. The infection of PHKs by M. hominis causes cellular damage that can affect the cell cycle by activating the response pathways to cellular damage, oxidative stress, and Toll-like receptors. Overall, this response culminated in the reduction of cell proliferation/viability in vitro.

Effects of a Bacterial Infection on Mitochondrial Function and Oxidative Stress in a Songbird

AbstractAs a major physiological mechanism involved in cellular renewal and repair, immune function is vital to the body's capacity to support tissue maintenance and organismal survival. Because immune defenses can be energetically expensive, the activities of metabolically active organs, such as the liver, are predicted to increase during infection by most pathogens. However, some pathogens are immunosuppressive, which might reduce the metabolic capacities of select organs to suppress immune response. Mycoplasma gallisepticum (MG) is a well-known immunosuppressive bacterium that infects domestic chickens and turkeys as well as songbirds. In the house finch (Haemorhous mexicanus), which is the primary host for MG among songbird species, MG infects both the respiratory system and the conjunctiva of the eye, causing conspicuous swelling. To study the effect of a systemic bacterial infection on cellular respiration and oxidative damage in the house finch, we measured mitochondrial respiration, mitochondrial membrane potential, reactive oxygen species production, and oxidative damage in the livers of house finches that were wild caught and either infected with MG, as indicated by genetic screening for the pathogen, or free of MG infection. We observed that MG-infected house finches showed significantly lower oxidative lipid and protein damage in liver tissue compared with their uninfected counterparts. Moreover, using complex II substrates, we documented a nonsignificant trend for lower state 3 respiration of liver mitochondria in MG-infected house finches compared with uninfected house finches (P=0.07). These results are consistent with the hypothesis that MG suppresses organ function in susceptible hosts.

Mycoplasma gallisepticum infection in the grey partridge Perdix perdix: outbreak description, histopathology, biochemistry and antioxidant parameters

Background

The grey partridge is an important game bird in Europe that has declined considerably over the last decades. The production and release of farm-bred birds can be threatened by infectious agents. The objective of this study was to describe the outbreak, pathology, and blood and tissue biochemical responses in a flock of grey partridges naturally infected with Mycoplasma gallisepticum.

Results

Morbidity and mortality rates were 100% and 60%, respectively. Necropsy revealed an accumulation of caseous exudate within the infraorbital sinuses, tracheitis, pneumonia and airsacculitis. There were significant increases in activities of lactate dehydrogenase, creatine kinase and amylase, and levels of total protein and glucose in Mycoplasma-infected birds when compared to control. Catalase showed significantly lower activity in the heart, lungs, liver and gonads of Mycoplasma-infected birds. Glutathione-S-transferase activity was elevated in the eye and the associated infraorbital sinus and kidneys, and decreased in the liver. Decreased levels of reduced glutathione were found in the heart, kidneys, liver and gonads. The activity of glutathione reductase was lower only in the lungs. Compared to healthy birds, mycoplasmosis in the grey partridge caused significant differences in the level of lipid peroxidation in lungs and plasma (p < 0.05), while the ferric reducing antioxidant power was lower in the heart and kidneys (p < 0.01). Significant correlations among responses of the antioxidant parameters were found namely in the heart, lungs, spleen, liver and plasma. There were also numerous significant inter-tissue correlations of all the studied antioxidant parameters.

Conclusions

The present study demonstrates the high susceptibility of grey partridges to natural infection by M. gallisepticum, the severity of the disease based on histopathology, and the modulation of blood chemical profiles and oxidative stress-associated parameters in the avian hosts, thus enhancing the understanding of the pathogenesis of mycoplasmosis in birds. Moreover, the reported reference values can be useful for the evaluation of the state of health in grey partridges.

Occurrence of keratoconjunctivitis apparently caused by Mycoplasma gallisepticum in layer chickens

Natural cases of keratoconjunctivitis, apparently caused by Mycoplasma gallisepticum (MG), in layer chickens are described. The disease occurred in a commercial flock consisting of 36,000 pullets (Babcock), first appearing around 30 days of age. Clinically, affected chickens showed unilateral or bilateral swelling of the facial skin and the eyelids, increased lacrimation, congestion of conjunctival vessels, and respiratory rales. Some of the severely affected chickens closed their eyes. The morbidity reached 27.8%, and it was estimated that approximately 10% died from reduced feed intake due to impaired vision. Ten 70-day-old chickens with clinical diseases were examined for lesions. There was acute to subacute keratoconjunctivitis in all of the chickens, and some exhibited laryngitis. Adherence of mycoplasma organisms to epithelial cells of the conjunctiva, cornea, and larynx was frequently observed. These organisms had an ultrastructure characteristic of MG and showed a positive reaction with rabbit polyclonal antibodies against the S6 strain of MG by immunohistochemical analysis. MG was isolated from tissue homogenates of the eyelids and tracheas of the affected chickens. Many of the chickens had atrophic bursae, and infectious bursal disease virus antigens were detected in necrotic bursal follicles by immunostaining. Therefore, immunosuppression due to infectious bursal disease was implicated in the pathogenesis of keratoconjunctivitis in the present cases.

Primary culture of chicken bursal plical epithelium

Plical epithelial cells were obtained by trypsin-EDTA treatment of chicken bursa of Fabricius and cultured in the presence of type IV collagen. The culture became confluent six to seven days after seeding. The grown cells showed a positive reaction for cytokeratin by immunostaining and had ultrastructural characteristics of the epithelial cells in vivo. The cell culture will be useful for parasitological and virological studies.

Evidence for superoxide dismutase and catalase in mollicutes and release of reactive oxygen species

The presence of superoxide dismutase was demonstrated in 21 strains of mollicutes, including achuloplasmas, mycoplasmas, and ureaplasmas. No superoxide dismutase activities or only traces were detectable in fresh prepared cell lysates, whereas activities were evident after dialysis of the cell lysates. A further increase in superoxide dismutase activities was observed after the cell lysates were heated to 65 degrees C for 30 s. This might be due to the destruction of enzymatic reactions interfering with the activity tests. Additionally, catalase activities were demonstrated in nearly 50% of the cell lysates, whereas no peroxidase activities were detectable. The production of O2- and H2O2 with glucose as substrate was demonstrated for 8 of 10 strains tested. No correlation to the pathogenicities of the strains was indicated. Anaerobic mycoplasmas showed the highest amount of radical production, whereas superoxide dismutase and catalase activities were in the range of activities estimated for aerobic mollicutes.