Biology subjects

Huffines, J. T.

Publications and source records attributed to Huffines, J. T..

3 recordsLinked to original sources

bioRxiv2024

Staphylococcus aureus Phenol-Soluble Modulins Mediate Interspecies Competition with Upper Respiratory Commensal Bacteria

In chronic rhinosinusitis (CRS) disease, microbial dysbiosis is considered a key contributor to inflammation and pathogenicity, with increased prevalence of upper respiratory tract (URT) pathogens concomitant with decreased abundance of commensal species. Staphylococcus aureus is a common URT pathobiont associated with higher carriage rates in CRS. S. aureus secreted toxins are implicated in CRS pathogenesis, and toxins and antibodies to S. aureus secreted factors have been observed in tissue from CRS subjects. CRS disease severity is positively correlated with immune reactivity to S. aureus proteins. Prior studies have examined polymicrobial interactions between S. aureus and URT commensals, however, no studies to date have described possible methods employed by S. aureus to outcompete commensals leading to a S. aureus-dominant microbiome as seen in CRS. This study addresses this gap in knowledge by characterizing how a CRS-associated secreted toxin from S. aureus can inhibit aggregation in commensal URT species. Using a model URT commensal, Corynebacterium pseudodiphtheriticum, we identified a CRS-associated secreted protein from S. aureus, {delta}-toxin (Hld), that can inhibit C. pseudodiphtheriticum aggregation at biologically relevant concentrations. Furthermore, we observed recombinant {delta}-toxin reduces C. pseudodiphtheriticum adherence and aggregation on human nasal epithelial cells in an air-liquid interface cell culture model. These results define a novel mechanism by which S. aureus can disrupt URT commensal lifestyles of microbial competitors, contributing to the establishment of microbial dysbiosis. IMPORTANCEMicrobial dysbiosis in the upper respiratory tract (URT) is associated with disease pathogenicity in chronic rhinosinusitis (CRS). There are significant links between Staphylococcus aureus and worse CRS outcomes, but no studies to date have demonstrated if S. aureus outcompetes other URT microbes through direct interactions. Here, we report that S. aureus {delta}-toxin, a secreted protein found in CRS patient tissue, can inhibit the ability of commensal bacteria to aggregate, adhere to, and grow in association with human nasal epithelial cells. These results suggest a potential mechanism for S. aureus to establish dominance in the URT microbiome through direct antagonism of commensals with a disease-associated toxin.

microbiology↗

bioRxiv2023

Temperature Influences Commensal-Pathogen Dynamics in a Nasal Epithelial Cell Co-culture Model

Chronic rhinosinusitis (CRS) is an inflammatory disease of the paranasal sinuses, and microbial dysbiosis associated with CRS is thought to be a key driver of host inflammation that contributes to disease progression. Staphylococcus aureus is a common upper respiratory tract (URT) pathobiont that is associated with higher carriage rates in CRS populations, where S. aureus secreted toxins can be identified in CRS tissue samples. Although many genera of bacteria colonize the URT, relatively few account for the majority of sequencing reads. These include S. aureus, as well as several species belonging to the genus Corynebacterium, including Corynebacterium propinquum and Corynebacterium pseudodiphtheriticum, which are observed at high relative abundance in the URT of healthy individuals. Studies have examined the bacterial interactions between the major microbionts of the URT and S. aureus, but few have done so in the context of a healthy versus diseased URT environment. Here, we examine the role of temperature in commensal, pathogen, and epithelial dynamics using an air-liquid interface cell culture model mimicking the nasal epithelial environment. The healthy URT temperature changes from the nares to the nasopharynx and is altered during disease. Temperatures representative of the healthy URT increase persistence and aggregate formation of commensal C. propinquum and C. pseudodiphtheriticum, reduce S. aureus growth, and lower epithelial cytotoxicity compared to higher temperatures correlating with the diseased CRS sinus. Dual-species colonization revealed species-specific interactions between commensal Corynebacterium species and S. aureus dependent on temperature. Our findings suggest that URT mucosal temperature plays a significant role in mediating polymicrobial and host-bacterial interactions that may exacerbate microbial dysbiosis found in chronic URT disease. IMPORTANCEChronic rhinosinusitis is a complex inflammatory disease with a significant healthcare burden. Although presence of S. aureus and microbial dysbiosis are considered mediators of inflammation in CRS, no studies have examined the influence of temperature on S. aureus interactions with the nasal epithelium and the dominant genus of the healthy URT, Corynebacterium. Interactions between Corynebacterium species and S. aureus have been documented in several studies, but none to date have examined how environmental changes in the URT may alter their interactions with the epithelium or each other. This study utilizes a polarized epithelial cell culture model at air-liquid interface to study the colonization and spatial dynamics of S. aureus and clinical isolates of Corynebacterium from people with CRS to characterize the role temperature has in single-and dual-species dynamics on the nasal epithelium.

microbiology↗

bioRxiv2021

The nitrogen phosphotransferase regulator PtsN (EIIANtr) regulates inorganic polyphosphate production in Escherichia coli

Inorganic polyphosphate (polyP) is synthesized by bacteria under stressful environmental conditions and acts by a variety of mechanisms to promote cell survival. While the kinase that synthesizes polyP (PPK, enocoded by the ppk gene) is well known, little is understood about how environmental stress signals lead to activation of this enzyme. Previous work has shown that the transcriptional regulators DksA, RpoN ({sigma}54), and RpoE ({sigma}24) positively regulate polyP production, but not ppk transcription, in Escherichia coli. In this work, we set out to examine the role of the alternative sigma factor RpoN and nitrogen starvation stress response pathways in controlling polyP synthesis in more detail. In the course of these experiments, we identified GlnG, GlrR, PhoP, PhoQ, RapZ, and GlmS as proteins that affect polyP production, and uncovered a central role for the nitrogen phosphotransferase regulator PtsN (EIIANtr) in a polyP regulatory pathway, acting upstream of DksA, downstream of RpoN, and apparently independently of RpoE. However, none of these regulators appears to act directly on PPK, and the mechanism(s) by which they modulate polyP production remain unclear. Unexpectedly, we also found that the pathways that regulate polyP production vary depending not only on the stress condition applied, but also on the composition of the media in which the cells were grown before exposure to polyP-inducing stress. These results constitute substantial progress towards deciphering the regulatory networks driving polyP production under stress, but highlight the remarkable complexity of this regulation and its connections to a broad range of stress-sensing pathways. IMPORTANCEBacteria respond to changes in their environments with a complex regulatory network that controls the expression and activity of a wide range of effectors important for their survival. This stress response network is critical for the virulence of pathogenic bacteria and for the ability of all bacteria to grow in natural environments. Inorganic polyphosphate (polyP) is an evolutionarily ancient and almost universally conserved stress response effector that plays multiple roles in virulence, stress response, and survival in diverse organisms. This work provides new insights into the connections between well characterized nitrogen starvation and cell envelope stress response signaling pathways and the production of polyP in Escherichia coli.

microbiology↗