Biology subjects

Robbins, J. R.

Publications and source records attributed to Robbins, J. R..

3 recordsLinked to original sources

bioRxiv2026

Colitis-induced visceral pain recruits central neurotensin neurons that modulate colonic sensitivity

Inflammatory bowel disease produces debilitating visceral pain that remains a major clinical challenge. Notably, many patients experience persistent pain even after the inflammation resolves, indicating a sustained sensitization of central neural circuits that drives enduring pain. The brainstem parabrachial nucleus integrates interoceptive signals from the gastrointestinal tract to elicit both pain perception and affective responses. Using activity-dependent mapping and an RNAscope assay, we identified a neurotensin (NT)-expressing neuronal population in the lateral PBN (PBNL) that is selectively activated during dextran sulfate sodium-induced colitis. In vivo neural activity recordings demonstrate that PBNL NT neurons encode colon-derived nociceptive signals in an intensity-dependent manner. Silencing these neurons attenuates colonic reflexes evoked by luminal distension and normalizes aberrant gastrointestinal transit and nociceptive licking behavior in colitic mice. Pharmacological blockade of NT signaling alleviates colitis-associated hypersensitivity. These findings identify a central neural population that encodes visceral inflammation and regulates peripheral organ function, and pinpoints neurotensin as a promising therapeutic target to treat colitis-induced visceral pain.

neuroscience↗

bioRxiv2018

In vivo virulence characterization of pregnancy-associated Listeria monocytogenes infections

Listeria monocytogenes is a foodborne pathogen that infects the placenta and can cause pregnancy complications. Listeriosis infections usually occur as sporadic infections, but large outbreaks are also reported. Virulence from clinical isolates is rarely analyzed due to the large number of animals required, but this knowledge could help guide the response to an outbreak. We implemented a DNA barcode system using signature tags that allowed us to efficiently assay variations in virulence across a large number of isolates. We tested 77 signature-tagged clones of clinical L. monocytogenes strains from 72 infected human placentas and five immunocompromised patients, all isolated since 2000. These strains were tested for virulence in a modified competition assay in comparison to the laboratory strain 10403S. We used two in vivo models of listeriosis: the non-pregnant mouse and the pregnant guinea pig. Strains that were frequently found at high abundance within infected organs were considered \"hypervirulent,\" while strains frequently found at low abundance were considered \"hypovirulent.\" Virulence split relatively evenly among hypovirulent, hypervirulent, and strains equally virulent to 10403S. The laboratory strain was found to have an intermediate virulence phenotype, supporting its suitability for pathogenesis studies. Further, we found that splenic and placental virulence are closely linked in both guinea pig and mouse models. This suggests that outbreak and sporadic pregnancy-associated L. monocytogenes are not generally more virulent than lab reference strains. However, some strains did show consistent and reproducible virulence differences, suggesting that their further study may reveal deeper insights into the biological underpinnings of listeriosis.

microbiology↗

bioRxiv2018

Listeria monocytogenes InlP interacts with afadin and facilitates basement membrane crossing

During pregnancy, the placenta protects the fetus against the maternal immune response, as well as bacterial and viral pathogens. Bacterial pathogens that have evolved specific mechanisms of breaching this barrier, such as Listeria monocytogenes, present a unique opportunity for learning how the placenta carries out its protective function. We previously identified the L. monocytogenes protein Internalin P (InlP) as a secreted virulence factor critical for placental infection (1). Here, we show that InlP, but not the highly similar L. monocytogenes internalin Lmo2027, binds to human afadin (encoded by AF-6), a protein associated with cell-cell junctions. A crystal structure of InlP reveals several unique features, including an extended leucine-rich repeat (LRR) domain with a distinctive Ca2+-binding site. Despite afadins involvement in the formation of cell-cell junctions, MDCK epithelial cells expressing InlP displayed a decrease in the magnitude of the traction stresses they could exert on deformable substrates, similar to the decrease in traction exhibited by AF-6 knock-out MDCK cells. L. monocytogenes {Delta}inlP mutants were deficient in their ability to form actin-rich protrusions from the basal face of polarized epithelial monolayers, a necessary step in the crossing of such monolayers (transcytosis). A similar phenotype was observed for bacteria expressing an internal in-frame deletion in inlP (inlP DLRR5) that specifically disrupts its interaction with afadin. However, afadin deletion in the host cells did not rescue the transcytosis defect. We conclude that secreted InlP targets cytosolic afadin to specifically promote L. monocytogenes transcytosis across the basal face of epithelial monolayers, which may contribute to the crossing of the basement membrane during placental infection.

microbiology↗