Biology subjects

LeVeque, R. M.

Publications and source records attributed to LeVeque, R. M..

3 recordsLinked to original sources

bioRxiv2026

Microbiota-derived indole limits Campylobacter jejuni colonization by inhibiting respiration and metabolism

How the microaerophilic Campylobacter jejuni grows in the inflamed gut is poorly understood, hampering our ability to identify novel targets for controlling infections by this pathogen. Our prior ferret study indicated that C. jejuni growth during infection is driven by intestinal inflammation. Without manipulating microbiota or introducing pro-inflammatory genetic lesions (or both), conventional mice are naturally resistant to C. jejuni colonization and infection. To test the impact of inflammation per se on C. jejuni infection, we induced transient intestinal inflammation in mice using short-term dextran sodium sulfate (DSS) treatment. The resulting colitis disrupted colonization resistance, enabling rapid C. jejuni growth in the murine colon within three days of infection, accompanied by exacerbated intestinal inflammation. DSS-induced colitis led to enrichment of mucin-degrading bacteria and depletion of taxa producing short-chain fatty acids and indole; metabolomic profiling confirmed a marked reduction in colonic indole levels in both DSS-treated and infected mice. At physiological concentrations, indole inhibited C. jejuni growth in vitro and resulted in reduced transcript levels from key energy-generating pathways, including nitrate respiration (napA), aerobic respiration (ccoN), lactate utilization (lctP), and the acetate switch (ackA/ptaA); consistent with this, mutations in these pathways led to fitness defects in DSS-treated mice, highlighting their importance for C. jejuni colonization in the inflamed gut. Moreover, treatment with indole or the indole-producing probiotic Escherichia coli Nissle 1917 significantly reduced C. jejuni colonization in vivo. Our findings show how C. jejuni establishes and grows in the inflamed gut and demonstrate that microbiota-derived metabolites play a key role in regulating C. jejuni pathogenicity. SignificanceThe mechanisms by which the microaerophilic pathogen C. jejuni proliferates in the inflamed intestine remain poorly understood. Using a DSS-induced colitis mouse model, we identify host physiological changes, microbiota alterations, and metabolic factors that promote C. jejuni colonization during intestinal inflammation. These findings provide mechanistic insight into why Campylobacter species are frequently detected in patients with Inflammatory Bowel Disease (IBD) and how infection can exacerbate intestinal inflammation and worsen disease symptoms. We further identify the microbiota-derived metabolite indole as a potent inhibitor of C. jejuni colonization, highlighting a potential metabolite-based therapeutic strategy to combat emerging multidrug-resistant C. jejuni infections.

microbiology↗

bioRxiv2023

Gut metabolite L-lactate supports Campylobacter jejuni population expansion during acute infection

How the microaerobic pathogen Campylobacter jejuni establishes its niche and expands in the gut lumen during infection is poorly understood. Using six-week-old ferrets as a natural disease model, we examined this aspect of C. jejuni pathogenicity. Unlike mice, which require significant genetic or physiological manipulation to become colonized with C. jejuni, ferrets are readily infected without the need to disarm the immune system or alter the gut microbiota. Disease after C. jejuni infection in ferrets reflects closely how human C. jejuni infection proceeds. Rapid growth of C. jejuni and associated intestinal inflammation was observed within two-three days of infection. We observed pathophysiological changes that were noted by cryptic hyperplasia through the induction of tissue repair systems, accumulation of undifferentiated amplifying cells on the colon surface, and instability of HIF-1 in colonocytes, which indicated increased epithelial oxygenation. Metabolomic analysis demonstrated that lactate levels in colon content were elevated in infected animals. A C. jejuni mutant lacking lctP, which encodes an L-lactate transporter, was significantly decreased for colonization during infection. Lactate also influences adhesion and invasion by C. jejuni to a colon carcinoma cell line (HCT116). The oxygenation required for expression of lactate transporter (lctP) led to discovery of a putative thiol based redox switch regulator (LctR) that may repress lctP transcription under anaerobic conditions. Our work provides new insights into the pathogenicity of C. jejuni. SignificanceThere is a gap in knowledge about the mechanisms by which C. jejuni populations expand during infection. Using an animal model which accurately reflects human infection without the need to alter the host microbiome or the immune system prior to infection, we explored pathophysiological alterations of the gut after C. jejuni infection. Our study identified the gut metabolite L-lactate as playing an important role as a growth substrate for C. jejuni during acute infection. We identified a DNA binding protein, LctR, that binds to the lctP promoter and may repress lctP expression, resulting in decreased lactate transport under low oxygen levels. This work provides new insights about C. jejuni pathogenicity.

microbiology↗

bioRxiv2019

Phosphate transporter PstSCAB of Campylobacter jejuni is essential for lactate-dependent growth and colonization in chickens

Campylobacter jejuni causes acute gastroenteritis world-wide and is transmitted primarily through poultry, in which it is often a commensal member of the intestinal microbiota. Previous RNASeq experiments showed that transcripts from an operon encoding a high affinity phosphate transporter (PstSCAB) of C. jejuni were among the most abundant when grown in chickens. Elevated levels of the pstSCAB mRNA were also identified in an RNASeq experiment from human infection studies. In this study, we explore the role of PstSCAB in the biology and colonization potential of C. jejuni. Our experimental results demonstrate that cells lacking PstSCAB survive poorly in stationary phase, nutrient-limiting media, and under osmotic conditions reflective of those in the chicken. Polyphosphate levels in the mutant cells were elevated at stationary phase, consistent with alterations in expression of polyphosphate metabolism genes. C. jejuni were highly attenuated in colonization of newly hatched chicks, recovered at levels several orders of magnitude below wild type. Mutant and wild type grew similarly in complex media but the pstSCAB mutant exhibited a significant growth defect in minimal media supplemented with L-lactate, postulated as a carbon source in vivo. Poor growth in lactate correlated with diminished expression of acetogenesis pathway genes previously demonstrated as important for colonizing chickens. The phosphate transport system is thus essential for diverse aspects of C. jejuni physiology and in vivo fitness and survival. ImportanceC. jejuni causes millions of gastrointestinal infections annually worldwide. Poultry and poultry products are major sources of C. jejuni infection to human as the microbe is a commensal colonizer of the chicken gastrointestinal tract. Due to the emergence of multi-drug resistance in C. jejuni, there is need to identify alternative ways to control this pathogen. Genes encoding the high-affinity phosphate transporter PstSCAB were highly expressed during colonization of C. jejuni in chicken and human. In this study, we address the role this high-affinity phosphate transporter PstSCAB of C. jejuni on chicken colonization and for its general physiology. PstSCAB is required for colonization in chicken, metabolism and survival under different stress responses and during growth on lactate, a potential substrate for growth of C. jejuni in chickens. Our study highlights that PstSCAB may be an effective target to develop mechanisms to control the bacterial burden in both chicken and human.

microbiology↗