Journal of Microbiology

Journal Article

Thioredoxin A of Streptococcus suis Serotype 2 Contributes to Virulence by Inhibiting the Expression of Pentraxin 3 to Promote Survival Within Macrophages: Chijun Zhao , Xinglin Jia , Yanying Pan , Simeng Liao , Shuo Zhang , Chunxiao Ji , Guangwei Kuang , Xin Wu , Quan Liu , Yulong Tang , Lihua Fang; J. Microbiol. 2023;61(4):433-448. Published online April 3, 2023; DOI: https://doi.org/10.1007/s12275-023-00038-4

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Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen that can infect humans in contact with infected pigs or their byproducts. It can employ different types of genes to defend against oxidative stress and ensure its survival. The thioredoxin (Trx) system is a key antioxidant system that contributes adversity adaptation and pathogenicity. SS2 has been shown to encode putative thioredoxin genes, but the biological roles, coding sequence, and underlying mechanisms remains uncharacterized. Here, we demonstrated that SSU05_0237-ORF, from a clinical SS2 strain, ZJ081101, encodes a protein of 104 amino acids with a canonical CGPC active motif and an identity 70–85% similar to the thioredoxin A (TrxA) in other microorganisms. Recombinant TrxA efficiently catalyzed the thiol-disulfide oxidoreduction of insulin. The deletion of TrxA led to a significantly slow growth and markedly compromised tolerance of the pathogen to temperature stress, as well as impaired adhesion ability to pig intestinal epithelial cells (IPEC-J2). However, it was not involved in H2O2 and paraquat-induced oxidative stress. Compared with the wild-type strain, the ΔTrxA strain was more susceptible to killing by macrophages through increasing NO production. Treatment with TrxA mutant strain also significantly attenuated cytotoxic effects on RAW 264.7 cells by inhibiting inflammatory response and apoptosis. Knockdown of pentraxin 3 in RAW 264.7 cells was more vulnerable to phagocytic activity, and TrxA promoted SS2 survival in phagocytic cells depending on pentraxin 3 activity compared with the wild-type strain. Moreover, a co-inoculation experiment in mice revealed that TrxA mutant strain is far more easily cleared from the body than the wild type strain in the period from 8–24 h, and exhibits significantly attenuated oxidative stress and liver injury. In summary, we reveal the important role of TrxA in the pathogenesis of SS2.

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Thioredoxin C of Streptococcus suis serotype 2 contributes to virulence by inducing antioxidative stress and inhibiting autophagy via the MSR1/PI3K-Akt-mTOR pathway in macrophages
Chunxiao Ji, Yanying Pan, Bocheng Liu, Jianying Liu, Chijun Zhao, Zhuyuan Nie, Simeng Liao, Guangwei Kuang, Xin Wu, Quan Liu, Jie Ning, Yulong Tang, Lihua Fang
Veterinary Microbiology.2024; 298: 110263. CrossRef
A Comprehensive Review on the Roles of Metals Mediating Insect–Microbial Pathogen Interactions
Subhanullah Khan, Minglin Lang
Metabolites.2023; 13(7): 839. CrossRef

Randomized Controlled Trial

Antimicrobial Activity of Enterocins from Enterococcus faecalis SL-5 against Propionibacterium acnes, the Causative Agent in Acne Vulgaris, and Its Therapeutic Effect: Bong Seon Kang , Jae-Gu Seo , Gwa-Su Lee , Jung-Hwa Kim , Sei Yeon Kim , Ye Won Han , Hoon Kang , Hyung Ok Kim , Ji Hwan Rhee , Myung-Jun Chung , Young Min Park; J. Microbiol. 2009;47(1):101-109. Published online February 20, 2009; DOI: https://doi.org/10.1007/s12275-008-0179-y

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Abstract: A lactic acid bacterial strain was isolated from human fecal specimen and identified as Enterococcus faecalis SL-5. The isolated strain showed antimicrobial activity against Gram-positive pathogens assayed, especially the highest activity against Propionibacterium acnes. The antimicrobial substance was purified and verified as a bacteriocin (named ESL5) of E. faecalis SL-5 by activity-staining using P. acnes as an indicator. N-terminal sequence of ESL5 was determined (MGAIAKLVAK) and sequence analysis revealed that it is almost identical to the some of enterocins including L50A/B of E. faecium L50 and MR10A/B of E. faecalis MRR 10-3. From the sequencing data of L50A/B structural genes, the nucleotide sequence showed 100% identity with that of the MR10A/B structural genes, implying that ESL5 is an equivalent of enterocin MR10. Meanwhile, we also tested the therapeutic effect of anti-P. acnes activity in patients with mild to moderate acne because of its pathogenic role to acne vulgaris. For this purpose, a concentrated powder of CBT SL-5 was prepared using cell-free culture supernatant (CFCS) of E. faecalis SL-5 and included in a lotion for application in the patients. The study showed that CBT SL-5 lotion significantly reduced the inflammatory lesions like pustules compared to the placebo lotion. Therefore our results indicate that the anti-P. acnes activity produced by E. faecalis SL-5 has potential role to the treatment of acne as an alternative to topical antibiotics.

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