CRP Involved in Nile Tilapia (Oreochromis niloticus) against Bacterial Infection

Abstract

C-reactive protein (CRP) is an acute-phase protein that can be used as an early diagnostic marker for inflammation, which is also an evolutionarily conserved protein and has been identified from arthropods to mammals. However, the roles of CRP during the immune response of Nile tilapia (Oreochromis niloticus) remain unclear. In this study, a CRP gene from Nile tilapia (On-CRP) was identified, and its roles in response to bacterial infection were investigated in vivo or in vitro. On-CRP was found to contain an open reading frame of 675 bp, encoding a polypeptide of 224 amino acids with the conservative pentraxin domain. On-CRP shares more than 50% of its identity with other fish species, and 30% of its identity with mammals. The transcriptional level of On-CRP was most abundant in the liver and its transcripts can be remarkably induced following Streptococcus agalactiae and Aeromonas hydrophila infection. Furthermore, in vitro analysis indicated that the recombinant protein of On-CRP improved phagocytic activity of monocytes/macrophages, and possessed a bacterial agglutination activity in a calcium-dependent manner. Both in vivo and in vitro experiments indicated that On-CRP could promote inflammation and activate the complement pathway. However, a direct relationship between CRP and several immune pathways could not be confirmed. The present data lays a theoretical foundation to further explore the mechanism of how CRP protects fish against bacterial infection.

Effectiveness of endophytic bacteria for some medicinal plants as probiotics for Nile tilapia (Oreochromis niloticus)

“…Results also indicated that about 50% of treatments reported similar creatinine levels to the control group (0.19 mg/dL). It is interesting that C-reactive protein (CRP) was <0.6 for all treatments, and was lower than the serum CRP level of normal O. niloticus (2.51 mg/L) as Julinta et al (2019) reported, indicating that no inflammation occurred in all of the studied fish, where Li et al (2022) reported that Creactive protein is an acute-phase protein that can be used as an early diagnostic marker for inflammation. In addition, direct bilirubin was not detected, with minimal values for total bilirubin.…”

The cytoplasmic sensor, the AIM2 inflammasome: A precise therapeutic target in vascular and metabolic diseases

“…Numerous studies have shown that both IL‐1β and IL‐18 are expressed in human atheroma and exhibit an adverse effect on cardio‐cerebrovascular diseases by causing local inflammation, elevating adhesion molecule expression and boosting procoagulant activity (Y. Jin et al, 2022). The production of IL‐1β and IL‐18 results in elevations of IL‐6 and C‐reactive protein (CRP) (Calabrese & Rose‐John, 2014; Q. Li et al, 2022). IL‐6 and C‐reactive protein are mediators of inflammation.…”

“…IL‐6 and C‐reactive protein are mediators of inflammation. In an atherosclerosis‐prone model, alterations in the levels of IL‐1β and IL‐18 are associated with changes in the expression of the AIM2 inflammasome and atherosclerosis (Calabrese & Rose‐John, 2014; Q. Li et al, 2022). Consistently, IL‐1β induced by overexpression of AIM2 worsened AAA, while AIM2 deficiency alleviated that phenomenon (X. Wu et al, 2016).…”

Biological significance of C-reactive protein, the ancient acute phase functionary

“…CRP has been observed in animals other than humans, including the freshwater fish Channa punctatus ( 9 ) and the Nile tilapia Oreochromis niloticus ( 10 ). Based on amino acid sequence analysis and the number of subunits, the main structure of human and rabbit CRP has been identified.…”

“…Nile tilapia’s CRP gene has also been discovered ( 10 ). The data clearly demonstrate that CRP in Nile tilapia is a robust and active participant in the anti-bacterial immune response beginning with the agglutination of bacteria as well as the regulation of phagocytosis and inflammation.…”