Comparison of systemic Listeria monocytogenes infection in esophageally inoculated mice anesthetized with isoflurane or pentobarbital

Transcription Factor Forkhead Box P (Foxp) 1 Reduces Brain Damage During Cerebral Ischemia-Reperfusion Injury in Mice Through FUN14 Domain-containing Protein 1

Mitophagy plays a significant role in modulating the activation of pyrin domain-containing protein 3 (NLRP3) inflammasome, which is a major contributor to the inflammatory response that exacerbates cerebral ischemia-reperfusion (I/R) injury. Despite this, the transcriptional regulation mechanism that governs mitophagy remains unclear. This study sought to explore the potential mechanism of Forkhead Box P1 (Foxp1) and its impact on cerebral I/R injury. We investigated the potential neuroprotective role of Foxp1 in cerebral I/R injury by the middle cerebral artery occlusion (MCAO) mouse model. Additionally, we assessed whether FUN14 domain-containing protein 1 (FUNDC1) could rescue the protective effect of Foxp1. Our results showed that overexpression of Foxp1 prevented brain damage during cerebral I/R injury and promoted NLRP3 inflammasome activation, whereas knockdown of Foxp1 had the opposite effect. Notably, Foxp1 overexpression directly promotes FUNDC1 expression, enhanced mitophagy activation, and inhibited the inflammatory response mediated by the NLRP3 inflammasome. Furthermore, we confirmed through chromatin immunoprecipitation (ChIP) and luciferase reporter assays that FUNDC1 is a direct target gene of Foxp1 downstream. Furthermore, the knockdown of FUNDC1 reversed the increased activation of mitophagy and suppressed NLRP3 inflammasome activation induced by Foxp1 overexpression. Collectively, our findings suggest that Foxp1 inhibits NLRP3 inflammasome activation through FUNDC1 to reduce cerebral I/R injury.

A Comparison of Oral and Intravenous Mouse Models of Listeriosis

Listeria monocytogenes is one of several enteric microbes that is acquired orally, invades the gastric mucosa, and then disseminates to peripheral tissues to cause systemic disease in humans. Intravenous (i.v.) inoculation of mice with L. monocytogenes has been the most widely-used small animal model of listeriosis over the past few decades. The infection is highly reproducible and has been invaluable in deciphering mechanisms of adaptive immunity in vivo, particularly CD8⁺ T cell responses to intracellular pathogens. However, the i.v. model completely bypasses the gut phase of the infection. Recent advances in generating both humanized mice and murinized bacteria, as well as the development of a foodborne route of transmission has reignited interest in studying oral models of listeriosis. In this review, we analyze previously published reports to highlight both the similarities and differences in tissue colonization and host response to infection using either oral or i.v. inoculation.

Animal models for oral transmission of Listeria monocytogenes

Listeria monocytogenes has been recognized as a food borne pathogen in humans since the 1980s, but we still understand very little about oral transmission of L. monocytogenes or the host factors that determine susceptibility to gastrointestinal infection, due to the lack of an appropriate small animal model of oral listeriosis. Early feeding trials suggested that many animals were highly resistant to oral infection, and the more reproducible intravenous or intraperitoneal routes of inoculation soon came to be favored. There are a fair number of previously published studies using an oral infection route, but the work varies widely in terms of bacterial strain choice, the methods used for oral transmission, and various manipulations used to enhance infectivity. This mini review summarizes the published literature using oral routes of L. monocytogenes infection and highlights recent technological advances that make oral infection a more attractive model system.

Comparing the effects of isoflurane and pentobarbital on the responses of cutaneous mechanoreceptive afferents

BACKGROUND

While pentobarbital has been used extensively in neurophysiological experiments investigating activity in peripheral nerves, it has fallen out of favor as an anesthetic because of safety concerns and is often replaced with isoflurane. However, the effects of isoflurane on the excitability of mechanoreceptive afferents have yet to be conclusively elucidated.

METHODS

To fill this gap, we collected extracellular single-unit recordings of cutaneous mechanoreceptive afferents from the sciatic nerve of 21 rats during vibratory stimulation of the hindpaw. We then compared the strength and temporal structure of the afferent response measured under pentobarbital and isoflurane anesthesia.

RESULTS

We found that the strength and temporal structure of afferent responses were statistically equivalent whether these were evoked under isoflurane or pentobarbital.

CONCLUSIONS

We conclude that, if these two anesthetics have any effect on the responses of mechanoreceptive afferents, their effects are indistinguishable.

The Key Events Dose-Response Framework: its potential for application to foodborne pathogenic microorganisms

The Key Events Dose-Response Framework (KEDRF) is an analytical approach that facilitates the use of currently available data to gain insight regarding dose-response relationships. The use of the KEDRF also helps identify critical knowledge gaps that once filled, will reduce reliance on assumptions. The present study considers how the KEDRF might be applied to pathogenic microorganisms, using fetal listeriosis resulting from maternal ingestion of food contaminated with L. monocytogenes as an initial example. Major biological events along the pathway between food ingestion and the endpoint of concern are systematically considered with regard to dose (i.e., number of organisms), pathogen factors (e.g., virulence), and protective host mechanisms (e.g., immune response or other homeostatic mechanisms). It is concluded that the KEDRF provides a useful structure for systematically evaluating the complex array of host and pathogen factors that influence the dose-response relationship. In particular, the KEDRF supports efforts to specify and quantify the sources of variability, a prerequisite to strengthening the scientific basis for food safety decision making.