Antibacterial effect of porcine PTX3 against Streptococcus suis type 2 infection
Jueqiong Xu1, Yanjuan Mu1, Yue Zhang1
1OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
Abstract:
Pentraxin 3 (PTX3), a soluble pattern recognition receptor, plays an important role in innate immunity and has been implicated to be a candidate resistance gene against Streptococcus suis 2 infection. To discover the antibacterial effect of porcine PTX3 against S. suis 2, the 42-kDa PTX3 protein was expressed by Chinese hamster ovary cells (CHO), and an additional eukaryotic expression vector pVAX-ptx3 was constructed. The expressed porcine PTX3 mediated a range of antibacterial activities including increasing phagocytic capacity of primary porcine alveolar macrophages (PAM) against S. suis 2 and inhibiting adhesion of S. suis 2 to human epidermoid cancer cells (Hep-2). In mouse model, pre-intramuscular injecting with pVAX-ptx3 reduced mortality and reduced bacteria loads in blood, spleen, lung and brain compared with that of control group during 2-12 h following intraperitoneal injection (i.p.) with S. suis 2. Meanwhile, the expressions of IL-6 and IL-8 in blood were increased in pVAX-ptx3 group, whereas no obvious changes about IL-10. In piglet model, bacteria load in blood of pVAX-ptx3 group was significantly lower than that of control group after i.p. with S. suis 2, correspondingly, expression of IL-6 and IL-8 were significantly increased in pVAX-ptx3 group. In contrast, white blood cell (WBC) and neutrophil cell (NEU) count of peripheral blood in pVAX-ptx3 group were lower than that of control group. These studies described a novel antibacterial role for porcine PTX3 against S. suis 2 both in vitro and in vivo and suggested that porcine PTX3 may be a potential biological agent against S. suis 2 in pig and be used for the clinical prevention and treatment of streptococcosis caused by S. suis 2.
Insights
Porcine Pentraxin 3 (PTX3) demonstrates antibacterial effects against Streptococcus suis 2. This study shows PTX3 enhances macrophage activity and reduces bacterial load in vivo, suggesting its potential as a therapeutic agent.
Area of Science:
- Immunology
- Microbiology
- Veterinary Medicine
Background:
- Pentraxin 3 (PTX3) is a pattern recognition receptor crucial for innate immunity.
- PTX3 is a potential candidate gene for resistance against Streptococcus suis 2 (S. suis 2) infection.
Purpose of the Study:
- To investigate the antibacterial effects of porcine PTX3 against S. suis 2.
- To evaluate the therapeutic potential of porcine PTX3 in animal models.
Main Methods:
- Porcine PTX3 protein was expressed using Chinese hamster ovary (CHO) cells.
- Antibacterial activity was assessed in vitro using porcine alveolar macrophages (PAMs) and Hep-2 cells.
- Efficacy was evaluated in vivo using mouse and piglet models challenged with S. suis 2.
Main Results:
- Expressed porcine PTX3 increased PAM phagocytosis and inhibited S. suis 2 adhesion to Hep-2 cells.
- In vivo studies showed reduced mortality and bacterial loads in PTX3-treated mice and piglets.
- Treatment with PTX3 modulated cytokine expression (IL-6, IL-8) and affected white blood cell counts.
Conclusions:
- Porcine PTX3 exhibits significant antibacterial activity against S. suis 2 in vitro and in vivo.
- Porcine PTX3 shows promise as a biological agent for preventing and treating streptococcosis in pigs.
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