Helminth-induced reprogramming of the stem cell compartment inhibits type 2 immunity

Enteric helminths form intimate physical connections with the intestinal epithelium, yet their ability to directly alter epithelial stem cell fate has not been resolved. Here we demonstrate that infection of mice with the parasite Heligmosomoides polygyrus bakeri (Hpb) reprograms the intestinal epithelium into a fetal-like state marked by the emergence of Clusterin-expressing revival stem cells (revSCs). Organoid-based studies using parasite-derived excretory-secretory products reveal that Hpb-mediated revSC generation occurs independently of host-derived immune signals and inhibits type 2 cytokine-driven differentiation of secretory epithelial lineages that promote their expulsion. Reciprocally, type 2 cytokine signals limit revSC differentiation and, consequently, Hpb fitness, indicating that helminths compete with their host for control of the intestinal stem cell compartment to promote continuation of their life cycle.

Publisher Correction: Sex dependent effects of post-natal penicillin on brain, behavior and immune regulation are prevented by concurrent probiotic treatment

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Suboptimal treatment response to anti-IL-5 monoclonal antibodies in severe eosinophilic asthmatics with airway autoimmune phenomena

BACKGROUND

In clinical trials, the two anti-interleukin (IL)-5 monoclonal antibodies (mAbs: mepolizumab and reslizumab) approved to treat severe eosinophilic asthma reduce exacerbations by ∼50-60%.

OBJECTIVE

To observe response to anti-IL-5 mAbs in a real-life clinical setting, and to evaluate predictors of suboptimal response.

METHODS

In four Canadian academic centres, predefined clinical end-points in 250 carefully characterised moderate-to-severe asthmatic patients were collected prospectively to assess response to the two anti-IL-5 mAbs. Suboptimal response was determined based on failure to reduce maintenance corticosteroid (MCS) or asthma symptoms scores (Asthma Control Questionnaire (ACQ)) or exacerbations, in addition to persistence of sputum/blood eosinophils. Worsening in suboptimal responders was assessed based on reduced lung function by 25% or increase in MCS/ACQ. A representative subset of 39 patients was evaluated for inflammatory mediators, autoantibodies and complement activation in sputum (by ELISA) and for immune-complex deposition by immunostaining formalin-fixed paraffin-embedded sputum plugs.

RESULTS

Suboptimal responses were observed in 42.8% (107 out of 250) patients treated with either mepolizumab or reslizumab. Daily prednisone requirement, sinus disease and late-onset asthma diagnoses were the strongest predictors of suboptimal response. Asthma worsened in 13.6% (34 out of 250) of these patients. The majority (79%) of them were prednisone-dependent. Presence of sputum anti-eosinophil peroxidase immunoglobulin (Ig)G was a predictor of suboptimal response to an anti-IL-5 mAb. An increase in sputum C3c (marker of complement activation) and deposition of C1q-bound/IL-5-bound IgG were observed in the sputa of those patients who worsened on therapy, suggesting an underlying autoimmune-mediated pathology.

CONCLUSION

A significant number of patients who meet currently approved indications for anti-IL5 mAbs show suboptimal response to them in real-life clinical practice, particularly if they are on high doses of prednisone. Monitoring blood eosinophil count is not helpful to identify these patients. The concern of worsening of symptoms associated with immune-complex mediated complement activation in a small proportion of these patients highlights the relevance of recognising airway autoimmune phenomena and this requires further evaluation.

Sex dependent effects of post-natal penicillin on brain, behavior and immune regulation are prevented by concurrent probiotic treatment

There is increasing awareness of the need to consider potential long-term effects of antibiotics on the health of children. In addition to being associated with immune and metabolic diseases, there is evidence that early-life antibiotic exposure can affect neurodevelopment. Here we investigated the effect of low dose of penicillin V on mice when administered for 1 week immediately prior to weaning. We demonstrated that exposure to the antibiotic during the pre-weaning period led to long-term changes in social behaviour, but not anxiety-like traits, in male mice only. The change in behaviour of males was associated with decreased hippocampal expression of AVPR1A and AVPR1B while expression of both receptors was increased in females. Spleens of male mice also showed an increase in the proportion of activated dendritic cells and a corresponding decrease in regulatory T cells with penicillin exposure. All changes in brain, behaviour and immune cell populations, associated with penicillin exposure, were absent in mice that received L. rhamnosus JB-1 supplementation concurrent with the antibiotic. Our study indicates that post-natal exposure to a clinically relevant dose of antibiotic has long-term, sex dependent effects on the CNS and may have implications for the development of neuropsychiatric disorders. Importantly, we also provide further evidence that probiotic based strategies may be of use in counteracting detrimental effects of early-life antibiotics on neurodevelopment.

A119 AN EX VIVO MODEL TO STUDY THE GUT SEROTONERGIC SYSTEM RESPONSE TO LIVE AND HEAT-KILLED LACTOBACILLUS RHAMNOSUS STRAIN JB-1

Background

Enterochromaffin (EC) cells are one of the most abundant enteroendocrine cells in the intestinal epithelium, responsible for producing and storing the largest pool of serotonin or 5-hydroxytryptamine (5-HT) in the body. 5-HT has been shown to be important for modulating a large number of gastrointestinal reflexes in health and disease. 5-HT can stimulate extrinsic (vagal and spinal afferents) or intrinsic primary afferent neurons (IPANs) which are involved in motility, secretion and vasodilation within the intestines. Where EC cell localized enzyme tryptophan hydroxylase (TpH) isoform 1 is responsible for 5-HT synthesis, serotonin reuptake transporter (Sert) and monoamine oxidase A (Mao A) are responsible for termination by uptake and metabolism of 5-HT respectively. Our previous research has demonstrated the effects Lactobacillus rhamnosus (JB-1) on the firing frequency of spinal nerve fibres and motility. Increasing interest is being focused on potential health benefits of heat-inactivated microbes and purified bacterial components. However, the effect of these heat-killed bacteria on the intestinal epithelium cells, particularly on EC cells, is unknown.

Aims

Small intestinal organoids are shown to recapitulate in vivo characteristics of the small intestine epithelium. The present study aims to assess the suitability of intestinal organoids to study bacterial effects on the serotonergic system in the gut. Here we determined changes in the gene expression of key mediators in the serotonergic system [serotonin reuptake transporter (Sert), tryptophan hydroxylase-1 (Tph-1) and monoamine oxidase A (Mao A)] in response to live and heat-killed JB-1.

Methods

Male C57bl/6 mice aged 6–8 weeks were used for both ex vivo and in vivo experiments. Jejunal organoids were grown from whole crypts isolated using DTT-EDTA solution. Live and heat-killed JB-1 bacteria were used as treatments. Gene expression analysis was performed on jejunal organoids and jejunum tissue using qRT-PCR.

Results

JB-1 induced a significant increase in gene expression of Sert, Mao A and Tph-1. No significant difference was observed between the effects of live and heat-killed bacteria. In contrast the JB-1 increased expression of the peptide hormone CCK. Effects of JB-1 on gene expression in organoid culture were reflective of changes observed in in vivo experiments involving feeding of the bacteria.

Conclusions

Ex vivo organoid culture could be a useful tool in studying mechanisms underlying bacterial effects on serotonergic signalling. The observation that heat-killed bacteria produced comparable effects to the live organism suggests the possibility of isolating active 5-HT modulating components from these strains. Future research will focus on identifying such bacterial components and how their effects on gene expression influence serotonin availability

Funding Agencies

None

Heterogeneity in histone 2B-green fluorescent protein-retaining putative small intestinal stem cells at cell position 4 and their absence in the colon

Stem cells have been identified in two locations in small intestinal crypts; those intercalated between Paneth cells and another population (which retains DNA label) are located above the Paneth cell zone, at cell position 4. Because of disadvantages associated with the use of DNA label, doxycycline-induced transient transgenic expression of histone 2B (H2B)-green fluorescent protein (GFP) was investigated. H2B-GFP-retaining putative stem cells were consistently seen, with a peak at cell position 4, over chase periods of up to 112 days. After a 28-day chase, a subpopulation of the H2B-GFP-retaining cells was cycling, but the slow cycling status of the majority was illustrated by lack of expression of pHistone H3 and Ki67. Although some H2B-GFP-retaining cells were sensitive to low-dose radiation, the majority was resistant to low- and high-dose radiation-induced cell death, and a proportion of the surviving cells proliferated during subsequent epithelial regeneration. Long-term retention of H2B-GFP in a subpopulation of small intestinal Paneth cells was also seen, implying that they are long lived. In contrast to the small intestine, H2B-GFP-retaining epithelial cells were not seen in the colon from 28-day chase onward. This implies important differences in stem cell function between these two regions of the gastrointestinal tract, which may have implications for region-specific susceptibility to diseases (such as cancer and ulcerative colitis), in which epithelial stem cells and their progeny are involved.