A58 ENTERIC TUFT CELLS MODULATE LOCAL BUT NOT SYSTEMIC HOST IMMUNE RESPONSES TO CO-ORDINATE TIMELY EXPULSION OF HYMENOLEPIS DIMINUTA

Background

The intestinal tuft cell is a versatile epithelial cell implicated in host detection and defence against enteric nematode and trematode parasites by producing interleukin(IL)-25 and cysteinyl leukotrienes. We have shown that immunocompetent mice develop small intestinal tuft cell hyperplasia during infection with the cestode, Hymenolepis diminuta. Whether tuft cells coordinate murine expulsion of H. diminuta and if this response is similar to other well-established parasitic models is unknown.

Purpose

To test 1) if tuft cells coordinate host detection and immune responses to H. diminuta; and, 2) if the lack of functional B, T cells and innate lymphoid cells (ILC2s) affect tuft cell hyperplasia and expulsion of the parasite.

Method

Male and female pou2f3^-/-/^-/+ littermates, rag-1^-/- and C57BL6 mice were infected with 5 cysticercoids of H. diminuta. ILC2s were depleted in rag-1^-/- with anti-CD90.2 (250μg/mouse, intraperitoneal). At necropsy, small intestines were flushed with cold PBS to count worms. IgG1, IgG2α and mast cell protease-1 (MCPT-1) was measured in serum and supernatants from splenic cells stimulated with ConA (48h) were assessed by ELISA for IL-4, -5, -10 and -13. Doublecortin-like kinase -1 (DCLK-1)+ tuft cells, goblet cells and eosinophils were identified in sections of paraffin embedded or cryopreserved mid-jejunum sections. mRNA of small intestinal epithelium enriched fractions isolated from mice at control and 11 days post-infection (dpi) was evaluated by qPCR.

Result(s)

Unlike pou2f3^+/- and C57Bl6 mice that expel H. diminuta by 8-11 dpi., pou2f3^-/- mice harbour H. diminuta at 11 dpi. Pou2f3^-/- mice show similar splenic IL-4, -5, -10, -13, and serum IgG1, IgG2a and MCPT-1 levels at 8 dpi. and higher splenic IL-4, -10 at 11 dpi. compared to pou2f3^+/- mice. In contrast, pou2f3^+/- mice show higher jejunal goblet cell hyperplasia at 8 dpi., higher levels of small intestinal epithelium expression of dclk-1, alox5 and il-25 and jejunal eosinophilia at 11 dpi. compared to pou2f3^-/- mice. At 11 dpi, ILC^depletedrag-1^-/- develop tuft cell hyperplasia to the same extent as infected PBS/isotype controls and show no trace of intestinal worms in the lumen.

Conclusion(s)

Enteric tuft cells coordinate rapid expulsion of H. diminuta from mice, but are not essential for the host to detect and develop Th2 systemic responses in response to the worm. However, in the absence of tuft cells, deficiencies are observed in gut-specific effector immune events commonly associated with timely expulsion of enteric helminths; illustrating a disparity between local and systemic immunity following infection with this tapeworm parasite in a non permissive host. The lack of a functional adaptive immune system and surprisingly, depletion of ILC2s, does not completely abrogate worm expulsion or tuft cell hyperplasia in rag-1^-/- at 11 dpi. with H. diminuta. This suggests that an innate immune cell population other than CD90.2⁺ ILC2s amplifies Th2 immunity to H. diminuta-infection.

Please acknowledge all funding agencies by checking the applicable boxes below

Other

Please indicate your source of funding;

NSERC, , Eyes High doctoral scholarship, Alberta Graduate excellence scholarship

Disclosure of Interest

None Declared

A232 TUFT CELLS COORDINATE RAPID EXPULSION OF THE TAPEWORM H. DIMINUTA BUT ARE NOT REQUIRED FOR ENHANCED IMMUNITY AGAINST THE NEMATODE, H. POLYGYRUS, IN MICE PREVIOUSLY INFECTED WITH H. DIMINUTA

Background

The tuft cell is an important sentinel that monitors the gut lumen and coordinates immunity against parasitic nematodes. We showed small intestinal tuft cell hyperplasia 11 days post-infection (dpi.) with the tapeworm Hymenolepis diminuta: a time when the parasite is no longer present in murine hosts. This may be a way by which the host protects itself from subsequent helminth-infections, a common phenomenon in parasite-endemic world regions. We test this supposition using Pou2f3^-/- mice that lack tuft cells.

Aims

To test the hypothesis that tuft cells are important in the anti-worm response in H. diminuta ( H.d.)-infected mice subsequently infected with the nematode parasite Heligosomoides polygyrus ( H.p.).

Methods

Male C57BL6 and Pou2f3^-/- mice (8–12 weeks) were infected with 5 H.d. cysticercoids ± 200 H.p. larvae at 10 dpi with H. diminuta (non H.p. mice - control). Upon necropsy at 24 dpi H. diminuta (i.e. 14 dpi H.p. in co-infected mice), both worms were ennumerated in small intestinal washings, H.p. granulomas examined and fecal egg counts performed. Small intestinal segments were stained for tuft (DCLK1⁺) and goblet cells (PAS⁺). As a surrogate of successful infection, IL-4 and IL-10 were measured in supernatants from concanavalin-A treated splenocytes.

Results

Wild-type (WT) mice expel H. diminuta by 11 dpi and this was delayed in Pou2f3^-/-mice, with worms readily detectable at 14 dpi and absent by 21 dpi. Despite the delayed expulsion, both WT and Pou2f3^-/- mice showed increased splenic production of IL-4 and IL-10; however, unlike WT mice, H. diminuta-infected Pou2f3^-/- mice show no increase in jejunal goblet cell numbers. Mice infected with H. diminuta displayed a degree of increased resistance to H.p.-infection defined by reduced worm and egg burdens, and increased granuloma formation in comparison to H.p.-only infected animals. In this sequential co-infection model, there were no significant differences between WT and Pou2f3^-/- mice in the response to H.p.

Conclusions

The absence of tuft cells slows expulsion of H. diminuta from its non-permissive mouse host and correlates with diminished goblet cell hyperplasia. Hypothesizing that H. diminuta-evoked tuft cell hyperplasia would enhance the immune response to a subsequent infection with an unrelated nematode parasite proved incorrect. While H. diminuta-infected mice were partially protected from H.p., response was similar in WT and Pou2f3^-/- mice. Thus tuft cells are important in worm detection: yet, our co-infection data suggests that other events initiated by the primary worm infection impact the outcome of subsequent infection with a different helminth and tuft cells have a limited, if any, role to play in this helminth-host-helminth interaction.

Funding Agencies

CIHRNSERC, Eye’s High International doctoral scholarship

A181 INFECTION WITH THE RAT TAPEWORM HYMENOLEPIS DIMINUTA REVEALS AN INTERLEUKIN-4 INDEPENDENT TUFT CELL ASSOCIATED WITH PEYER’S PATCHES

Background

Infection with the rat tapeworm Hymenolepis diminuta elicits a T helper 2 (Th2) imunity and suppresses dinitrobenzene sulphonic-acid-induced colitis in mice. However, the signaling cascade in an immunocompetent host that recognizes and mobilizies early immune events to expel the worm is poorly understood. To fully understand how helminth-infection can ameliorate concomitant disease, it is important to elucidate key cells/mediators in the detection of the worm and early events in the local anti-worm response. Here, we assess the chemosensory epithelial tuft cell and Peyer’s patches (PP) as the primary inductive sites of mucosal immunity in H. diminuta-infected mice.

Aims

To assess the role of tuft cells in PP development and worm expulsion following infection of H. diminuta.

Methods

BALB/c, BALB/c Il-4receptor-a^-/-, C57Bl/6 and C57Bl/6 pou2f3^-/- (transcription factor critial for tuft cell development) mice were infected with 5 cysticercoids of H. diminuta and necropsied 5-, 8- and 11-days post-infection (dpi); time-matched non-infected mice served as controls. PP number and size were counted and measured. Enteric tuft cells were assessed by immunostaining for the canonical marker double cortin like kinase (dclk)-1, and enumerated in PP-associated epithelium and villous epithelium distant from PP.

Results

Dclkl⁺ tuft cells were sparse throughout villus epithelium of control mice, but were notably aggregrated over PPs. Infection with H. diminuta resulted in more detectable PPs by visual inspection, but did not result in a statistically significant increase in either size or number of PP. Infected mice showed increased numbers of dclk1⁺ tuft cells in villus epithelium and PP-associated epithelium (n=3–6). Tuft cells were absent in pou2f3^-/- mice, that showed normal size and number of PPs ± infection with H. diminuta. Unexpectedly, analysis of small intestine from il4ra^-/- mice revealed dclk1⁺ tuft cells in association with PPs; perhaps a unique sub-type of this sentinel cell.

Conclusions

Analysis of tuft cells after infection with H. diminuta revealed that these cells aggregate around PPs under homeostatic conditions, and future studies will explore if this distrirbution is important for ‘M’ cell development and/or PP immune reactivity. Intrigingly, an il-4ra-independent tuft cell subtype was observed that awaits fuller characterization. Understanding the tuft cell may reveal novel aspects of development of mucosal immunity relevant to combating helminth-infection and perhaps autoinflammatory enteric disease.

Funding Agencies

NSERC

A47 ENTERIC TUFT CELL HYPERPLASIA FOLLOWING INFECTION WITH THE TAPEWORM HYMENOLEPIS DIMINUTA IS AFFECTED BY NEURONAL BUT NOT BACTERIAL FACTORS

Background

Tuft cells are a rare chemosensory population of the intestinal epithelium that detect intestinal parasitic nematodes and release IL-25 to mobilize innate lymphoid type 2 cells (ILC2), which then drive a Th2- dominant nematode expulsion response. Immunocompetent mice develop tuft cell hyperplasia in the small intestine during infection with Hymenolepis diminuta, a non-abrasive lumen dwelling small intestinal cestode parasite. Helminth infections are accompanied by alterations in sensory motor functions of the gut as well as the composition of the microbiota. It is poorly understood if tuft cell hyperplasia is regulated by these immunomodulatory influences.

Aims

To test if mice lacking (1) a functional adaptive immune system, (2) TRPV1+ gut-innervating sensory nerves and (3) a microbiome, display enteric tuft cell hyperplasia following infection with H. diminuta.

Methods

RAG-1-/- (male and female) and germ-free mice (n=3–6) were infected with 5 cysticercoids of H. diminuta and age matched non-infected mice served as control groups. Male C57BL/6j mice were treated with resiniferatoxin (RTX) to ablate TRPV1 +sensory neurons before infection. Mid-jejunum cryostat or paraffin embedded sections immunostained against doublecortin-like kinase -1 (DCLK-1) were blindly scored for tuft cell enumeration at 5–14 days post-infection.

Results

Tuft cell hyperplasia (~10-15-fold increase) was observed in the jejunum of wild-type mice at 11 days post infection with H. diminuta, by which time worms are expelled. Infected RAG-1-/- mice develop tuft cell hyperplasia of lesser magnitude than wild-type mice. Germ-free mice displayed tuft cell hyperplasia and kinetics of worm expulsion that were not different from wild-type mice. RTX-treated mice with confirmed loss of TRPV1+ nerve fibers in the gut and their cell soma in the dorsal root and nodose ganglia, had a greater increase (~2-fold) in tuft cell numbers compared to H. diminuta-only mice at 11 days post-infection.

Conclusions

Knowledge of how the host senses helminths in the gut lumen is central to the host-parasite interaction. Using the H. diminuta-mouse model system we find that tuft cell hyperplasia is largely, but not entirely dependent on adaptive immunity, occurs independent of the gut microbiota, and, intriguingly, TRPV1+ sensory nerves appear to act as a brake on the system, limiting the magnitude of the hyperplasia.

Funding Agencies

CIHRNSERC, Henry Koopman’s Memorial scholarship

Impact of storm runoff on Salmonella and Escherichia coli prevalence in irrigation ponds of fresh produce farms in southern Georgia

AIMS

To examine Salmonella and Escherichia coli in storm runoff and irrigation ponds used by fresh produce growers, and compare Salmonella serovars with those found in cases of human salmonellosis.

METHODS AND RESULTS

We collected water before and after rain events at two irrigation ponds on farms in southern Georgia, USA, and collected storm runoff/storm flow within the contributing watershed of each pond. Salmonella and E. coli concentrations were higher in ponds after rain events by an average of 0·46 (P < 0·01) and 0·61 (P < 0·05) log₁₀ most probable number (MPN) per 100 ml respectively. Salmonella concentrations in storm runoff from fields and forests were not significantly higher than in ponds before rain events, but concentrations in storm flow from streams and ditches were higher by an average of 1·22 log₁₀ MPN per 100 ml (P < 0·001). Eighteen Salmonella serovars were identified from 155 serotyped isolates, and eight serovars were shared between storm runoff/storm flow and ponds. Seven of the serovars, including five of the shared serovars, were present in cases of human illness in the study region in the same year. However, several serovars most commonly associated with human illness in the study region (e.g. Javiana, Enteritidis, and Montevideo) were not found in any water samples.

CONCLUSIONS

Salmonella and E. coli concentrations in irrigation ponds were higher, on average, after rain events, but concentrations of Salmonella were low, and the ponds met FDA water quality standards based on E. coli. Some similarities and notable differences were found between Salmonella serovars in water samples and in cases of human illness.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study directly examined storm runoff/storm flow into irrigation ponds and quantified increases in Salmonella and E. coli following rain events, with potential implications for irrigation pond management as well as human health.

Performance characterization of siemens primus linear accelerator under small monitor unit and small segments for the implementation of step-and-shoot intensity-modulated radiotherapy

Implementation of step-and-shoot intensity-modulated radiotherapy (IMRT) needs careful understanding of the accelerator start-up characteristic to ensure accurate and precise delivery of radiation dose to patient. The dosimetric characteristic of a Siemens Primus linear accelerator (LA) which delivers 6 and 18 MV x-rays at the dose rate of 300 and 500 monitor unit (MU) per minutes (min) respectively was studied under the condition of small MU ranging from 1 to 100. Dose monitor linearity was studied at different dose calibration parameter (D1_C0) by measuring ionization at 10 cm depth in a solid water phantom using a 0.6 cc ionization chamber. Monitor unit stability was studied from different intensity modulated (IM) groups comprising various combinations of MU per field and number of fields. Stability of beam flatness and symmetry was investigated under normal and IMRT mode for 20×20 cm² field under small MU using a 2D Profiler kept isocentrically at 5 cm depth. Inter segment response was investigated form 1 to 10 MU by measuring the dose per MU from various IM groups, each consisting of four segments with inter-segment separation of 2 cm.

In the range 1-4 MU, the dose linearity error was more than 5% (max −32% at 1 MU) for 6 MV x-rays at factory calibrated D1_C0 value of 6000. The dose linearity error was reduced to −10.95% at 1 MU, within −3% for 2 and 3 MU and ±1% for MU ≥4 when the D1_C0 was subsequently tuned at 4500. For 18 MV x-rays, the dose linearity error at factory calibrated D1_C0 value of 4400 was within ±1% for MU ≥3 with maximum of −13.5 observed at 1 MU. For both the beam energies and MU/field ≥4, the stability of monitor unit tested for different IM groups was within ±1% of the dose from the normal treatment field. This variation increases to −2.6% for 6 MV and −2.7% for 18 MV x-rays for 2 MU/field. No significant variation was observed in the stability of beam profile measured from normal and IMRT mode. The beam flatness was within 3% for 6 MV x-rays and more than 3% (Max 3.5%) for 18 MV x-rays at lesser irradiation time ≤3 MU. The beam stability improves with the increase in irradiation time. Both the beam energies show very good symmetry (≤2%) at all irradiation time.

For all the three segment sizes studied, the nonlinearity was observed at smaller MU/segment in both the energies. When the MU/segment is ≥4, all segment size shows fairly linear relation with dose/MU. The smaller segment size shows larger nonlinearity at smaller MU/segment and become more linear at larger MU/segment. Based on our study, we conclude that the Primus LA from Siemens installed at our hospital is ideally suited for step-and-shoot IMRT preferably for radiation ON time ≥4MU per segment.

Intrathecal neostigmine with bupivacaine for infants undergoing lower abdominal and urogenital procedures: dose response

BACKGROUND

Intrathecal (IT) neostigmine produces dose-dependent analgesia in adults. However, the dose of spinal neostigmine has not been investigated in infants. The purpose of this study was to assess spinal anesthesia (SA) duration provided by four doses of spinal neostigmine added to bupivacaine for lower abdominal and urogenital procedures in infants.

METHODS

Seventy-five infants were randomized into five groups. The control group B received IT plain 0.5% hyperbaric bupivacaine. Groups BN.25, BN.50, BN.75, and BN1.0 received bupivacaine with 0.25, 0.5, 0.75, and 1 microg/kg of neostigmine, respectively. The primary variable was the duration of anesthesia assessed by recovery of hip flexion. Postoperative pain with facial expression, leg activity, arm activity, crying and consolability scale score, and rescue analgesic requirements were the secondary variables measured, and the side effects were noted.

RESULTS

Seventy-three infants completed the study. There was a significant linear increase in SA duration with IT neostigmine to 65.2 (4.3) min with 0.5 microg/kg (P<0.01), 88.2 (5.1) with 0.75 microg/kg (P<0.001) and 92 (4.3) with 1 microg/kg (P<0.001) from 52.4 (4.3) min with bupivacaine alone. SA duration showed no significant difference between plain bupivacaine and BN.25 (P=0.100) or between groups BN.75 and BN1.0 (P=0.451). Groups BN.75 and BN1.0 had significantly reduced pain scores, and the median duration before the first dose rescue analgesic was requested prolonged significantly (P<0.001) compared with the other three groups.

CONCLUSIONS

IT neostigmine at a dose of 0.75 microg/kg added to bupivacaine significantly prolonged SA duration with reduced postoperative pain scores and rescue analgesic requirements in infants undergoing lower abdominal and urogenital procedures. No additional benefits were provided on increasing it to 1 microg/kg.

Combination of low doses of intrathecal ketamine and midazolam with bupivacaine improves postoperative analgesia in orthopaedic surgery

BACKGROUND

Intrathecal ketamine produces a short period of analgesia with stable haemodynamics. Midazolam with bupivacaine prolongs the duration of analgesia when administered intrathecally but does not prevent hypotension. The objective of this study was to assess the effect of a combination of intrathecal bupivacaine, ketamine and midazolam on the duration of analgesia and haemodynamic parameters.

METHODS

A prospective, randomized, double-blind study was carried out in 60 ASA I and II patients undergoing lower limb surgery under spinal anaesthesia. Patients were divided into three groups of 20 each. Patients in all the three groups received 3 mL of hyperbaric bupivacaine (0.5%) intrathecally. In addition, patients in Groups II and III received intrathecal ketamine (0.1 mg kg-1) and the same dose of ketamine along with midazolam (0.02 mg kg-1), respectively. All patients were evaluated for block characteristics, duration of pain-free period, total rescue analgesic requirement in the 24-h postoperative period, total dose of mephenteramine to treat hypotension and any central or neurological complication.

RESULTS

No patients in Group II required mephenteramine while 40% of patients in Group I and 10% in Group III required mephenteramine to maintain blood pressure after spinal anaesthesia. The mean +/- standard deviation duration of pain-free period was 331.5 +/- 89.9, 369.7 +/- 124.2 and 730.5 +/- 81.5 min in Group I, II and III, respectively. The pain-free interval was significantly greater in Group III compared to Groups I and II (P < 0.001). No patient had any complications.

CONCLUSION

A low dose of midazolam and ketamine with bupivacaine intrathecally results in prolonged analgesia and less haemodynamic fluctuations. However, the safety of this combination needs to be proved before its use in clinical practice.

Severe stridor following the repair of H-type tracheoesophageal fistula in an 11 month infant

Congenital tracheoesophageal fistula without esophageal atresia is commonly known as "H" type and this presents with a different clinical spectrum owing to the presence of a large and patent esophagus. There may be a time lag extending up-to 50 years between first presentation and confirmation of the diagnosis owing to the rarity of the condition, its nonspecific symptomatology, and limitations in its demonstration by contrast radiology and endoscopy. Respiratory sequelae are common following repair and may persist during the rest of life. We present here, the case of an 11 month old child who presented for a definitive repair of H-type tracheoesophageal fistula, diagnosed at the age of 9 months. Following an uneventful intraoperative course the child developed severe stridor in the postanesthesia care unit (PACU) 30 min after arrival necessitating endotracheal intubation. The further course of the child in the hospital, probable reasons for this unusual complication and its management are discussed.

Anesthetic implications of the catastrophic antiphospholipid syndrome

The antiphospholipid antibody syndrome (or the anticardiolipin antibody syndrome) is characterized by the presence of autoantibodies. Its major association is with systemic lupus erythematosus. 'Catastrophic' antiphospholipid syndrome (CAPS) is defined as an accelerated form of APS usually resulting in multiorgan failure and can be precipitated by surgery. We present the case of a 12-year-old male child who presented for enucleation of his left eye for fungal endopthalmitis. This patient had a history of CAPS 2 months before surgery with myocardial, gastrointestinal, renal and laryngeal involvement that improved on aggressive treatment and was subsequently managed on an outpatient basis for 2 months before presenting for enucleation. To the best of our knowledge, this is the first case of CAPS in a child reported in the anesthetic literature. Further aspects of this puzzling condition and its anesthesia implications are discussed.

Bordetella bronchiseptica fimbrial protein-enhanced immunogenicity of a Mannheimia haemolytica leukotoxin fragment

Leukotoxin produced by Mannheimia (Pasteurella) haemolytica is an important virulence factor in shipping fever pneumonia in feedlot cattle and is a critical protective antigen. In this study, the immune response to a chimeric protein generated by combining a gene fragment encoding neutralizing epitopes of M. haemolytica leukotoxin and a fimbrial protein gene (fim N) from Bordetella bronchiseptica was evaluated. The recombinant gene was cloned in a bacterial expression vector under the control of the tac promoter and expressed as a fusion protein with glutathione-S-transferase (GST) in Escherichia coli. Immunization of mice with the recombinant protein, GST-LTXFIM elicited a significantly stronger anti-leukotoxin antibody response than comparable immunizations with GST-LTX fusion proteins lacking FIM N. The GST-LTXFIM was also more stable than GST-LTX during storage at -80 degrees C, thus alleviating a stability problem inherent to leukotoxin. This chimeric protein may be a candidate for inclusion in new generation vaccines against shipping fever pneumonia.

Characterization of fimN, a new Bordetella bronchiseptica major fimbrial subunit gene

Fimbrial proteins play an important role in the binding of Bordetella bronchiseptica to mammalian cells, an event that is key to the pathogenesis of this organism. The fimbrial phenotype of B. bronchiseptica isolates is usually defined serologically by Fim2 and Fim3 antigens. In this study, a previously unidentified fimbrial gene, fimN, was cloned and sequenced. The identity of fimN is based on several observations. The predicted FimN protein has 59.4 and 52. 2% homology with B. bronchiseptica Fim2 and Fim3, respectively, and is similar in size to these fimbriae. fimN, expressed as a recombinant protein, is recognized by mAb prepared against Fim2 from Bordetella pertussis. The fimN promoter region contains a stretch of cytosine residues similar in length to those of other fimbrial genes expressed by Bordetella species. It also has an activator binding region, upstream from the C-stretch, that closely resembles a corresponding bvg regulated region in fim2, fim3, and fimX. The fimN gene was isolated from a cosmid prepared with B. bronchiseptica genomic DNA that restored normal properties of cellular adhesion to an adhesion deficient strain of B. bronchiseptica. As such, FimN may be a previously overlooked fimbrial antigen and may play an important role in the pathogenicity of B. bronchiseptica.