The Role of Intestinal Tuft Cells in the Murine Response to Infection with the Cestode, Hymenolepis diminuta

The small intestinal tuft cell has garnered considerable interest in the field of parasitic immunology over the past few years for being a sentinel cell in the host response against nematode, trematode, and protist parasites. The tuft cell displays versatility in its capacity to respond to various luminal stimuli and in the mediators it produces. Whether the tuft cell is involved in the host response to enteric cestodes has not been previously explored. My thesis seeks to determine if enteric tuft cells coordinate host anti-helminthic immunity against cestode parasites using murine infection with Hymenolepis diminuta as a model system. H. diminuta-infection induced tuft cell hyperplasia in mice which is dependent on IL-4R signalling and the adaptive immune system. Tuft cell hyperplasia still occurs in germ free mice, indicating that the parasite and host responses to the parasite and not microbial factors drive tuft cell hyperplasia. Using pou2f3-/- tuft cell-deficient mice, our study reveals that enteric tuft cells modulate local host responses to H. diminuta that are ultimately important in quicker worm expulsion from the mouse. At the same time, tuft cell deficiency does not abrogate the development of systemic immunity against H. diminuta, nor the ultimate (albeit delayed) expulsion of the worms. We further show that although infection with H. diminuta induces both tuft cell hyperplasia as well as protection from subsequent parasitic infection with H. bakeri, the tuft cell is not solely responsible for mediating systemic and other local Th2 responses against H. diminuta. This work reveals that while tuft cells play subtle roles in fine tuning the host response against the parasite H. diminuta, tuft cell deficiency is overcome by redundancies that exist in host’s mucosal immune arsenal leading to ultimate expulsion of the parasite

Infection with Hymenolepis diminuta Blocks Colitis and Hastens Recovery While Colitis Has Minimal Impact on Expulsion of the Cestode from the Mouse Host

Two experimental paradigms were adopted to explore host–helminth interactions involved in the regulation of colitis and to understand if colitis affects the outcome of helminth infection. First, male BALB/c mice infected with H. diminuta were challenged 4 days later with dinitrobenzene sulphonic acid (DNBS) and necropsied 3 days later. Second, mice were infected with H. diminuta 3 days after DNBS treatment and necropsied 11 or 14 days post-DNBS. Mice were assessed for colitic disease severity and infectivity with H. diminuta upon necropsy. Supporting the concept of helminth therapy, mice are protected from DNBS–colitis when infected with H. diminuta only 4 days previously, along with parallel increases in splenic production of Th2 cytokines. In the treatment regimen, H. diminuta infection produced a subtle, statistically significant, enhanced recovery from DNBS. Mice regained body weight quicker, had normalized colon lengths, and showed no overt signs of disease, in comparison to the DNBS-only mice, some of which displayed signs of mild disease at 14 days post-DNBS. Unexpectedly, colitis did not affect the hosts’ anti-worm response. The impact of inflammatory disease on helminth infection is deserving of study in a variety of models as auto-inflammatory diseases emerge in world regions where parasitic helminths are endemic

A Program to Reduce Post-Operative Opioid Prescribing at a Veteran’s Affairs Hospital

Variability in surgeon prescribing patterns is common in the post-operative period and can be the nidus for dependence and addiction. This project aims to reduce opioid overprescribing at the Veteran’s Affairs Pittsburgh Healthcare System (VAPHS). The VAPHS Opioid Stewardship Committee collaborated to create prescribing guidelines for inpatient and outpatient general, thoracic, and vascular surgery procedures. We incorporated bundled order sets into the provider workflow in the electronic medical system and performed a retrospective cohort study comparing opioid prescription patterns for Veterans who underwent any surgical procedure for a three-month period pre- and post- guideline implementation. After implementation of opioid prescribing guidelines, morphine milligram equivalents (MME), quantity of pills prescribed, and days prescribed were statistically significantly reduced for procedures with associated guidelines, including cholecystectomy (MME 140.8 vs. 57.5, p = 0.002; quantity 18.8 vs. 8, p = 0.002; days 5.1 vs. 2.8, p = 0.021), inguinal hernia repair (MME 129.9 vs. 45.3, p = 0.002; quantity 17.3 vs. 6.1, p = 0.002; days 5.0 vs. 2.4, p = 0.002), and umbilical hernia repair (MME 128.8 vs. 53.8, p = 0.002; quantity 17.1 vs. 7.8, p = 0.002; days 5.1 vs. 2.5, p = 0.022). Procedures without associated recommendations also preceded a decrease in overall opioid prescribing. Post-operative opioid prescribing guidelines can steer clinicians toward more conscientious opioid disbursement. There may also be reductions in prescribing opioids for procedures without guidelines as an indirect effect of practice change

Enteric Tuft Cells in Host-Parasite Interactions

Enteric tuft cells are chemosensory epithelial cells gaining attention in the field of host-parasite interactions. Expressing a repertoire of chemosensing receptors and mediators, these cells have the potential to detect lumen-dwelling helminth and protozoan parasites and coordinate epithelial, immune, and neuronal cell defenses against them. This review highlights the versatility of enteric tuft cells and sub-types thereof, showcasing nuances of tuft cell responses to different parasites, with a focus on helminths reflecting the current state of the field. The role of enteric tuft cells in irritable bowel syndrome, inflammatory bowel disease and intestinal viral infection is assessed in the context of concomitant infection with parasites. Finally, the review presents pertinent questions germane to understanding the enteric tuft cell and its role in enteric parasitic infections. There is much to be done to fully elucidate the response of this intriguing cell type to parasitic-infection and there is negligible data on the biology of the human enteric tuft cell—a glaring gap in knowledge that must be filled

Crohns Disease Pathobiont Adherent-Invasive E coli Disrupts Epithelial Mitochondrial Networks With Implications for Gut Permeability

Background & aims: Adherent-invasive Escherichia coli are implicated in inflammatory bowel disease, and mitochondrial dysfunction has been observed in biopsy specimens from patients with inflammatory bowel disease. As a novel aspect of adherent-invasive E coli-epithelial interaction, we hypothesized that E coli (strain LF82) would elicit substantial disruption of epithelial mitochondrial form and function. Methods: Monolayers of human colon-derived epithelial cell lines were exposed to E coli-LF82 or commensal E coli and RNA sequence analysis, mitochondrial function (adenosine triphosphate synthesis) and dynamics (mitochondrial network imaging, immunoblotting for fission and fusion proteins), and epithelial permeability (transepithelial resistance, flux of fluorescein isothiocyanate-dextran and bacteria) were assessed. Results: E coli-LF82 significantly affected epithelial expression of ∼8600 genes, many relating to mitochondrial function. E coli-LF82-infected epithelia showed swollen mitochondria, reduced mitochondrial membrane potential and adenosine triphosphate, and fragmentation of the mitochondrial network: events not observed with dead E coli-LF82, medium from bacterial cultures, or control E coli. Treatment with Mitochondrial Division Inhibitor 1 (Mdivi1, inhibits dynamin-related peptide 1, guanosine triphosphatase principally responsible for mitochondrial fission) or P110 (prevents dynamin-related peptide 1 binding to mitochondrial fission 1 protein) partially reduced E coli-LF82-induced mitochondrial fragmentation in the short term. E coli-LF82-infected epithelia showed loss of the long isoform of optic atrophy factor 1, which mediates mitochondrial fusion. Mitochondrial Division Inhibitor 1 reduced the magnitude of E coli-LF82-induced increased transepithelial flux of fluorescein isothiocyanate dextran. By 8 hours after infection, increased cytosolic cytochrome C and DNA fragmentation were apparent without evidence of caspase-3 or apoptosis inducing factor activation. Conclusions: Epithelial mitochondrial fragmentation caused by E coli-LF82 could be targeted to maintain cellular homeostasis and mitigate infection-induced loss of epithelial barrier function. Data have been deposited in NCBI's Gene Expression Omnibus and are accessible through GEO series accession numbers GSE154121 and GSE154122 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE154121)