Mycoplasma hyopneumoniae J elicits an antioxidant response and decreases the expression of ciliary genes in infected swine epithelial cells

Abstract

Mycoplasma hyopneumoniae is the most costly pathogen for swine production. Although several studies have focused on the host-bacterium association, little is known about the changes in gene expression of swine cells upon infection. To improve our understanding of this interaction, we infected swine epithelial nptr cells with M. hyopneumoniae strain J to identify differentially expressed mRNAs and miRNAs. The levels of 1,268 genes and 170 miRNAs were significantly modified postinfection. Up-regulated mRNAs were enriched in genes related to redox homeostasis and antioxidant defense, known to be regulated by the transcription factor NRF2 in related species. Down-regulated mRNAs were enriched in genes associated with cytoskeleton and ciliary functions. Bioinformatic analyses suggested a correlation between changes in miRNA and mRNA levels, since we detected down-regulation of miRNAs predicted to target antioxidant genes and up-regulation of miRNAs targeting ciliary and cytoskeleton genes. Interestingly, most down-regulated miRNAs were detected in exosome-like vesicles suggesting that M. hyopneumoniae infection induced a modification of the composition of NPTr-released vesicles. Taken together, our data indicate that M. hyopneumoniae elicits an antioxidant response induced by NRF2 in infected cells. In addition, we propose that ciliostasis caused by this pathogen is partially explained by the down-regulation of ciliary genes. Respiratory diseases are among the major health problems in the pig farming industry. Mycoplasma hyopneumoniae is the causative agent of swine enzootic pneumonia, a chronic respiratory disease that affects herds worldwide. Although M. hyopneumoniae does not cause high mortality, it is considered the most expensive pathogen for swine production 1. This is mainly due to the costs of treatment and vaccination and to losses related to decreased animal performance. In addition, M. hyopneumoniae is essential for the establishment of secondary pathogens in the host, which leads to a significant increase in mortality 2. M. hyopneumoniae attaches to the cilia of the tracheal epithelial cells with participation of adhesins 3 , resulting in ciliostasis and cell death 4. Besides adhesins, virulence factors are not well understood in this bacterium. Nevertheless, a recent study from our group indicated hydrogen peroxide production from glycerol and myo-inositol metabolism as important traits that might be related with pathogenesis and with the predominance of M. hyopneumoniae in the swine respiratory tract 5 .

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

“…A recent study concluded that the most significant histological changes recorded were thickening of alveolar septa caused by neutrophilic cellular infiltration with intraluminal cellular exudate. The majority of pulmonary lesions were chronic (75.81%) (Mucha et al, 2020). Gilts are considered the main source of pathogen inlets because they are mostly exposed to the pathogen during the lactation period (Patterson and Foxcroft, 2019).…”

Transcriptomic Analysis of Long-Term Protective Immunity Induced by Vaccination With Mycoplasma gallisepticum Strain ts-304

“…Feature cytoskeleton was similar in both young and mature birds (28) (Table 6), suggesting that the effect of infection on the cilia and cytoskeleton of tracheal epithelial cells is independent of the age of the birds, but that the effects on intercellular junctional complexes may be age dependent. The significant downregulation of genes involved in the formation of cilia and the cytoskeleton and in ciliary beating indicates that the loss of cilia and ciliostasis after infection with M. gallisepticum is not just an effect of the loss of intercellular adhesion, but rather is modulated at the transcriptional level, as similar transcriptional changes have been seen in the respiratory tracts of sheep and pigs after infection with mycoplasmas (62)(63)(64). Subsequent impaired functioning of the mucociliary apparatus (1), which is a primary mode of defense against respiratory pathogens, may enable these pathogens to withstand mucociliary clearance.…”

“…An earlier study that investigated the age-related differences in the immune response to infection with M. gallisepticum in chickens between 1 and 6 weeks of age found that the lesions were most severe in the younger birds ( 59 ), suggesting that older birds are less susceptible to disease caused by infection with M. gallisepticum . The inflammatory response in the trachea has more recently been shown to result from the immune dysregulation caused by M. gallisepticum ( 26 , 27 , 46 , 47 , 60 ) and similar transcriptional changes in genes involved in a robust inflammatory response have been detected after infection with M. ovipneumoniae in sheep ( 61 , 62 ) and M. hyopneumoniae in pigs ( 63 , 64 ). The coincidental development of enhanced, macrophage-driven phagocytosis and of the humoral response ( Table 6 ) towards the end of the second week after infection suggests the establishment of a protective immune response from this time point on in unvaccinated birds, after an acute phase of immune dysregulation.…”

Interaction between alveolar macrophages and epithelial cells during Mycoplasma pneumoniae infection

“…It was found that the swine epithelial NPTr cells infected with Mycoplasma hyopneumoniae were differentially expressed in microRNAs (miRNAs) related to antioxidant response and mRNA related to ciliary function. These differentially expressed genes were detected in the exosomes secreted by epithelial cells ( Mucha et al., 2020 ). Exosomes, as an effective cellular signal and a communication system, is an important regulator of various pathophysiological conditions ( Cho et al., Silverman and Reiner, 2011 ).…”