Melaleuca alternifolia essential oil prevents alterations to purinergic enzymes and ameliorates the innate immune response in silver catfish infected with Aeromonas hydrophila

Abstract

Aeromonas hydrophila infection represents a major impediment to the development of aquaculture, leading to important economic losses. Over the last few years, different methods have been used to counteract and minimize the negative effects of this infection, such as the use of Melaleuca alternifolia essential oil, popularly known as tea tree oil (TTO), that possess a bactericide action against A. hydrophila. The purinergic system develops an important role in the inflammatory response, principally due to involvement of adenosine triphosphate (ATP) in the inflammatory process, as well as by the anti-inflammatory properties of adenosine (Ado), a molecule that is controlled by NTPDase, 5'-nucleotidase and adenosine deaminase (ADA) enzymes. Thus, the aim of this study was to investigate the involvement of purinergic enzymes in the pathogenesis of A. hydrophila infection, and whether the purinergic pathway and innate immune response are involved in the protective effects of TTO in silver catfish (Rhamdia quelen) experimentally infected with A. hydrophila. Our results revealed that A. hydrophila infection increased seric NTPDase and 5'-nucleotidase activity, while ADA activity decreased. Also, the seric levels of pro-inflammatory cytokines such as interleukin-1 (IL-1), IL-6, tumor necrosis factor alpha (TNF-α) and interferon gamma (INF-γ) increased in the infected fish, while the seric level of anti-inflammatory interleukin-10 (IL-10) decreased. Treatment with TTO was able to prevent the impairment of purinergic enzymes and improve the innate immune response through the modulation of cytokine response during A. hydrophila infection. In summary, prophylactic therapy with TTO can be considered an important approach to improve the immune response and consequently avoid the inflammatory process in fish infected with A. hydrophila.

Purinergic signalling displays an anti‐inflammatory profile in the spleen of fish experimentally infected with Aeromonas caviae: Modulation of the immune response

“…The upregulation of splenic NTPDase activity may be related to a compensatory organic response or to an important physiological adjustment of the nucleotidase pathway to hydrolyse the excessive ATP in the extracellular environment, in agreement with the observations of Baldissera, Souza¸ Doleski et al. () in serum samples of silver catfish experimentally infected with A. hydrophila . It is important to emphasize that excessive extracellular ATP levels can interact with type P2 purine receptors to induce the release of proinflammatory cytokines and reduce the release of anti‐inflammatory cytokines (Borowiec, Lechward, Tkacz‐Stachowska, & Skladanowski, ).…”

“…However, the immunological pathways involved in the immune response during A. caviae infection remain unknown. Therefore, we decided to evaluate the activities of enzymes belonging to the purinergic system, which play a fundamental role in fish immunity (Baldissera, Souza¸ Doleski et al., ; Cekic & Linden, ).…”

The effects of essential oils and their major compounds on fish bacterial pathogens – a review

“…This EO also prevents oxidative damage in liver proteins and lipids, as well as maintaining the purinergic system (Baldissera et al . ,). The use of the EOs of H. ringens and O. americanum in preventive baths increased the complement system activity compared with control, but there was no significant difference in survival of silver catfish challenged with Aer.…”

Effects of black mustard (Brassica nigra) seed oil on growth performance, digestive enzyme activities and immune responses in rainbow trout (Oncorhynchus mykiss)

“…Terpene content of the BM may be responsible for this. Previously, Baldissera et al (2017) demonstrated an increased transcription of IL‐6 in catfish treated with Melaleuca alternifolia essential oil. They also correlated that the elevated IL‐6 gene must be related to the terpene content of the oil.…”