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Co-transcriptomic analysis of group A Streptococcus (GAS; Streptococcus pyogenes) invasions of human endothelial cells

ABSTRACT: Group A Streptococcus (GAS, aka Streptococcus pyogenes) causes an array of human diseases from mild pharyngitis to life-threatening necrotizing fasciitis. Invading host cells is a strategy for GAS to avoid antibiotic killing and immune system clearance. Our previous study showed that GAS is able to multiply in human microvascular endothelial cell line-1 (HMEC-1), and has higher survival in HMEC-1 cells due to insufficient acidification in lysosomes. GAS peroxide response regulator (PerR) modulates not only peroxide stress, but also metal homeostasis and bacterial virulence. Therefore, we aimed to investigate the role of PerR during GAS invading endothelial cells. First, we found that ΔperR mutant was more tolerant to H2O2 in vitro using hydrogen peroxide sensitivity assay. We further used cDNA-qPCR analysis to clarify the resistance mechanism of ΔperR mutant. The gene expressions of dpr, ahpC, and ahpF were up-regulated, explaining the enhanced resistance of the ΔperR mutant against peroxide stress. However, the proliferation of the ΔperR mutant in HMEC-1 cells was significantly lower than wild type strain after 5 h post-infection. To explore the underlying mechanisms of ΔperR mutant during infection, we performed dual RNAseq analysis to identify differentially expressed genes, and validated them using cDNA-qPCR analysis. The resulting up-regulated genes of iron efflux pump pmtA, iron/zinc chelating protein dpr, and zinc acquisition system (adcA, lmb/adcAII, phtD), and down-regulated zinc efflux pump czcD gave rise to impaired metal homeostasis in the ΔperR mutant. Furthermore, in vitro growth curve assays showed that the ΔperR mutant was sensitive to zinc deficiency and resistant to zinc toxicity. Taken together, this study has demonstrated the critical roles that GAS PerR plays in protecting from peroxide stress of host innate immune responses and zinc sequestration of nutritional immunity. Our novel findings open a new avenue of strategies in the development of antimicrobial agents. Our study demonstrates the importance of PerR. It aids GAS virulence in immune evasion during the LC3-associated phagocytosis in endothelial cells.

ORGANISM(S): Streptococcus pyogenes Homo sapiens

PROVIDER: GSE263247 | GEO | 2025/12/19

REPOSITORIES: GEO

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Project description:Background: During gut colonization, the enteric pathogen C. jejuni has to surmount the toxic effects of reactive oxygen species produced by its own metabolism, by the host immune system and by the intestinal microflora. Elucidation of C. jejuni oxidative stress defense mechanisms is critical for understanding Campylobacter pathophysiology. Results: The mechanisms of oxidative stress defenses in Campylobacter jejuni were characterized by transcriptional profiling, genes mutagenesis, and phenotypic analysis. The transcriptome changes, in response to H2O2, cumene hydroperoxide, or menadione exposure, were found to be oxidant specific and revealed the differential expression of genes belonging to a variety of biological pathways, from the classical oxidative stress defense systems, to the heat shock response, DNA repair and metabolism, fatty acid and capsule biosynthesis, and multidrug efflux pumps. To define the peroxide sensing regulator PerR, an isogenic mutant was constructed and its transcriptome profile compared to the wild-type strain. Sixty-six genes were found to belong to the PerR regulon. PerR appear to regulate gene expression both dependently and independently of the presence of iron and/or H2O2. The perR mutant was affected in its motility and attenuated in the chick colonization model. Mutagenic and phenotypic studies of the superoxide disumutase SodB, the alkyl-hydroxyperoxidase AhpC, and the catalase KatA, revealed their role in oxidative stress defenses and chick gut colonization. Conclusion: This study reveals the interplay between PerR, the iron metabolism and the oxidative stress defenses and highlights their role in the colonization and/or survival of C. jejuni in the chick cecum. Keywords: Transcriptional response to 3 oxidants (H2O2, menadione and cumene hydroperoxide) and characterization of the perR regulon (comparison of the transciptomes from the wild-type and perR mutant). To investigate the transcriptional responses of C. jejuni to oxidant exposure, hydrogen peroxide (H2O2), cumene hydroperoxide (CHP), or menadione sodium bisulfite (MND) was added to the 50 ml broth at a final concentration of 1 mM. The same amount of water or DMSO was added to the bacterial culture that served as reference samples for the transcriptional profile study in response to H2O2, MND or CHP. Furthermore, to investigate the transcriptional response of C. jejuni to H2O2 exposure in the presence of excess iron, ferrous sulfate was added to the bacterial culture at a final concentration of 40 µM, 15 min prior to H2O2 exposure. Ten minutes after the addition of the oxidant, total RNA was extracted and processed for microarray hybridization. To identify the PerR regulon, the wild-type strain C. jejuni NCTC 11168 and the perR mutant were grown in 500 ml flasks containing 250 ml of MEMα medium. At mid-log phase, 50 ml of the cultures were transferred to 100 ml flasks and ferrous sulfate and/or H2O2 were added . Ten minutes following the addition of H2O2 the cells were collected and the total RNA extracted.

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Co-transcriptomic analysis of group A Streptococcus (GAS; Streptococcus pyogenes) invasions of human endothelial cells

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