Modulation and Interaction of Immune‐Associated Parameters with Antioxidant in the Immunocytes of Crab Scylla paramamosain Challenged with Lipopolysaccharides

Abstract

Invertebrates are dependent on cellular and humoral immune defences against microbial infection. Scylla paramamosain is an important commercial species, but the fundamental knowledge on its immune defense related to the antioxidant and immune-associated reactions is still lacking. The study was to differentiate the responses of immune-associated parameters of haemolymph components in S. paramamosain when challenged with bacterial lipopolysaccharides (LPSs). The immunostimulating effects of LPS in crab by triggering various immune parameters (phagocytosis, lysozyme, antibacterial activity, phenoloxidase, and the generation of superoxide and nitric oxide) were investigated. Results showed that the generation of free radicals, phenoloxidase, lysozyme and antibacterial activities was significantly increased through the exposure periods. Conversely, total hemocyte count and lysosomal membrane stability decreased significantly as the exposure period extended to 96 h. The relationship between the antioxidant enzymes and immune reactions due to LPS was highly significant. In addition, ROS production was positively correlated with antioxidant showing immediate response of antioxidant defense to the oxyradicals generated. Overall, the study indicated that nonspecific immune components in hemocytes of crab showed active response to the LPS stimulation, and their responses suggested that many immune-associated parameters could be modulated and interrelated with the influence of antioxidants in crustaceans.

Molecular cloning and expression profiles of nitric oxide synthase (NOS) in mud crab Scylla paramamosain

“…Their responses suggested that many immune-associated parameters could be modulated and interrelated with the influence of antioxidants. Our results indicated that the NOS mRNA transcripts had most significant induction from 24 h to 48 h, that were a little different from the report from Gopalakrishnan et al [36], which showed LPSs injection also stimulated an increased level of nitric oxide, reaching the highest NO content during 6 he12 h time period. So NOS expression level showed significantly up-regulated after LPS injection, demonstrating that the immune system may intensify in S. paramamosain defense against to LPS stimulation [37].…”

Immune Response of Mud Crab, Scylla Paramamosain, to Bacterial Lipopolysaccharide

“…The recovery of the number of circulating hemocytes occurs because of the production or release of immature hemocytes from hematopoietic tissue (Sequeira et al 1996;van de Braak et al 2002;Söderhäll 2003). Previous studies have also confirmed that S. paramamosain exhibited increased PO activity when challenged with LPS at 0.1 and 0.5 mg/kg doses (Gopalakrishnan et al 2011). In this study, the PO activity in crabs challenged with LPS increased significantly at 2 and 6 hpi.…”

“…The immune defenses in crustaceans largely rely on cellular and humoral defenses (Johansson and Söderhäll 1989). Here, the THCs were restored to their original levels 6 h after injection, and the results indicate that LPS at a dose of 0.05 mg/kg was less toxic to S. paramamosain compared with that at 0.5 mg/kg (Gopalakrishnan et al 2011). Here, the THCs were restored to their original levels 6 h after injection, and the results indicate that LPS at a dose of 0.05 mg/kg was less toxic to S. paramamosain compared with that at 0.5 mg/kg (Gopalakrishnan et al 2011).…”

“…Serum enzyme activities are critical humoral defense components in crustaceans and can be activated by non-self-material (Kimbrell and Beutler 2001). LYZ activity increases in S. paramamosain during phagocytosis, and it has a major bacteriolytic characteristic in the immune system of crustaceans against pathogenic bacteria (Gopalakrishnan et al 2011). Previous studies have also confirmed that S. paramamosain exhibited increased PO activity when challenged with LPS at 0.1 and 0.5 mg/kg doses (Gopalakrishnan et al 2011).…”

“…Our previous study ) demonstrated that Vibrio parahaemolyticus was one of the main pathogens of crabs in southern China, inducing high disease prevalence and levels of mortality. Gopalakrishnan et al (2011) showed that bacterial LPS was able to trigger various rapid and dose-dependent immune responses in S. paramamosain, such as increased phagocytosis, lysozyme (LYZ) and antibacterial activity, and increased phenoloxidase (PO) activity, superoxide and nitric oxide generation. For example, Zhang et al (2013) found that V. parahaemolyticus infection induced elevated total hemocyte counts (THCs) and increasing levels of superoxide dismutase (SOD), peroxidase (POD), and nitric oxidase synthethase (NOS) activity.…”