Vitamin C elicits the activation of immunological responses in swimming crab (Portunus trituberculatus) hemocytes against Mesanophrys sp.

Under suitable conditions, Vitamin C (vit. C) is essential for immunological responses and positively influences the function of stimulated immune cells. Therefore, this study evaluated the specific mechanisms of innate immunity in crab after supplementing the cell culture media with vit. C. We used the primary culture media of swimming crab hemocytes to detect some immune factors and immune-related signaling pathways via 24 h stimulation in vitro assays. Besides, we evaluated the anti-parasitic action of these hemocytes. Herein, the cellular and humoral factors, including intra- and extracellular phenol oxidase, nitrite oxidase synthase, lysozyme, and intracellular O-2(-) were significantly (P < 0.05) enhanced after the culture media was supplemented with vit. C as compared to control. A two-slope broken-line analysis indicated that the optimum vit. C level for intracellular O-2(-) was 118.91 mu g mL(-1) of the cell culture media (R-2 = 0.73). However, for the extracellular O-2(-), the vit. C supplementation showed a downward quadratic relationship (R-2 = 0.59). qRT-PCR demonstrated that relative mRNA expression of immune-related genes, including proPO, serine proteases, a(2)M, and alf-1 was significantly (P < 0.05) increased with vit. C media supplementation. Further, the results indicated that the anti-parasitic response and survival rate (%) of hemocytes after Mesanophrys sp. challenge was also significantly (P < 0.05) augmented in media supplemented with vit. C, relative to the control. Thus, the different vit. C in vitro levels were necessary for optimal immunological responses of crab hemocytes. In summary, vit. C supplementation enhanced and modulated the innate immune response of hemocytes against Mesanophrys sp., highlighting its potential application as an immunostimulant.

Automated summary

The study found that supplementing cell culture media with Vitamin C significantly enhanced immunological responses and anti-parasitic actions in crab hemocytes. Intracellular O-2(-) levels peaked at 118.91 mu g mL(-1) of the cell culture media. Overall, Vitamin C supplementation modulated the innate immune response and improved survival rates of hemocytes, indicating its potential as an immunostimulant.