Acacetin attenuates Streptococcus suis virulence by simultaneously targeting suilysin and inflammation
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Updated: Oct 10, 2025
Intracranial Subarachnoidal Route of Infection for Investigating Roles of Streptococcus suis Biofilms in Meningitis in a Mouse Infection Model
Published on: July 1, 2018
Shengnan Xie1, Yan Zhang2, Lei Xu2
1Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China.
Abstract:
Streptococcus suis (S. suis), an important zoonotic pathogenic bacterium, can cause multiple diseases and fatal infections in both humans and animals. The emergence of highly virulent and extensively drug-resistant strains of S. suis has raised questions about the efficacy of available therapeutic agents, thereby necessitating novel therapeutic strategies. Suilysin (SLY) is one of the most essential determinants of virulence for the pathogenicity of S. suis capsular type 2 (SS2). In addition, inhibiting the excessive inflammatory response is a strategy to reduce the damage caused by SS2 infection. In this study, we identified acacetin as an effective inhibitor of SLY, which inhibited the oligomerisation of SLY without affecting bacterial growth. Furthermore, the addition of 4-16 μg/ml acacetin to the co-infection system of the cells reduced S. suis-induced inflammation by downregulating the activation of the MAPK signalling pathway, thereby alleviating the S. suis-mediated cell injury. Thus, in addition to the conventional antibiotic therapy, acacetin represent a potential drug candidate and strategy for the treatment of S. suis infections as it simultaneously inhibited the haemolytic activity of SLY and downregulated the inflammatory response.
Insights
Acacetin effectively inhibits Streptococcus suis (S. suis) virulence factor suilysin (SLY) and reduces inflammation. This dual action offers a promising new strategy for treating S. suis infections alongside antibiotics.
Area of Science:
- Microbiology and Immunology
- Infectious Diseases
- Pharmacology
Background:
- Streptococcus suis (S. suis) is a significant zoonotic pathogen causing severe infections in humans and animals.
- Drug-resistant S. suis strains necessitate novel therapeutic approaches.
- Suilysin (SLY) is a key virulence factor in S. suis capsular type 2 (SS2) infections, and controlling inflammation is crucial for mitigating damage.
Purpose of the Study:
- To identify inhibitors of S. suis virulence factor suilysin (SLY).
- To evaluate the potential of acacetin in mitigating S. suis-induced inflammation and cell injury.
- To explore acacetin as a complementary therapeutic strategy for S. suis infections.
Main Methods:
- Acacetin was tested for its inhibitory effect on SLY oligomerization.
- The impact of acacetin on bacterial growth was assessed.
- Acacetin's effect on S. suis-induced inflammation and cell damage was evaluated in a co-infection system, focusing on the MAPK signaling pathway.
Main Results:
- Acacetin effectively inhibited SLY oligomerization without impacting S. suis growth.
- Acacetin (4-16 μg/ml) reduced S. suis-induced inflammation by downregulating MAPK pathway activation.
- Acacetin treatment alleviated S. suis-mediated cell injury.
Conclusions:
- Acacetin is a potent inhibitor of SLY haemolytic activity.
- Acacetin demonstrates anti-inflammatory effects by modulating the MAPK pathway.
- Acacetin represents a promising therapeutic candidate for S. suis infections, offering a dual approach of inhibiting virulence and reducing inflammation.
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