Rigid bronchoscopy: a consultant survey.

INTRODUCTION: Inhalation of foreign bodies represents a potentially fatal emergency in both adults and children. Chest x-ray, in isolation, is neither sensitive nor specific. Rigid bronchoscopy represents the gold standard to diagnose and retrieve paediatric foreign bodies. Cases are encountered infrequently, creating anxieties about their management. Little is known about the confidence in, and maintenance of, rigid bronchoscopy skills by ear, nose and throat teams. METHODS: A 15-question survey was completed by 50 practising otolaryngology consultants in England. RESULTS: Results show that almost 40% of otolaryngology consultants covering rigid bronchoscopy have not performed bronchoscopy in more than 5 years. Consultants raised concerns about the anaesthetic support and the speed of equipment assembly. Questions on clinical practice showed disparities in practice in the same scenario. CONCLUSIONS: The authors advocate addressing many of the issues raised by the study with a greater availability of simulation courses and regular scheduled intradepartmental teaching days for all professionals involved. National guidelines on criteria for transfer to tertiary centres would improve the consistency of practice.

TGFßR signalling controls CD103+CD11b+ dendritic cell development in the intestine.

CD103+CD11b+ dendritic cells (DCs) are unique to the intestine, but the factors governing their differentiation are unclear. Here we show that transforming growth factor receptor 1 (TGFßR1) has an indispensable, cell intrinsic role in the development of these cells. Deletion of Tgfbr1 results in markedly fewer intestinal CD103+CD11b+ DCs and a reciprocal increase in the CD103-CD11b+ dendritic cell subset. Transcriptional profiling identifies markers that define the CD103+CD11b+ DC lineage, including CD101, TREM1 and Siglec-F, and shows that the absence of CD103+CD11b+ DCs in CD11c-Cre.Tgfbr1 fl/fl mice reflects defective differentiation from CD103-CD11b+ intermediaries, rather than an isolated loss of CD103 expression. The defect in CD103+CD11b+ DCs is accompanied by reduced generation of antigen-specific, inducible FoxP3+ regulatory T cells in vitro and in vivo, and by reduced numbers of endogenous Th17 cells in the intestinal mucosa. Thus, TGFßR1-mediated signalling may explain the tissue-specific development of these unique DCs.Developmental cues for the different dendritic cell (DC) subsets in the intestine are yet to be defined. Here the authors show that TGFßR1 signalling is needed for development of CD103+CD11b+ intestinal DCs from CD103-CD11b+ cells and that they contribute to the generation of Th17 and regulatory T cells.

Diversity and functions of intestinal mononuclear phagocytes.

The intestinal lamina propria (LP) contains a diverse array of mononuclear phagocyte (MNP) subsets, including conventional dendritic cells (cDC), monocytes and tissue-resident macrophages (mφ) that collectively play an essential role in mucosal homeostasis, infection and inflammation. In the current review we discuss the function of intestinal cDC and monocyte-derived MNP, highlighting how these subsets play several non-redundant roles in the regulation of intestinal immune responses. While much remains to be learnt, recent findings also underline how the various populations of MNP adapt to deal with the challenges specific to their environment. Understanding these processes should help target individual subsets for 'fine tuning' immunological responses within the intestine, a process that may be of relevance both for the treatment of inflammatory bowel disease (IBD) and for optimized vaccine design.

Tissue-specific differentiation of colonic macrophages requires TGFß receptor-mediated signaling.

Intestinal macrophages (mφ) form one of the largest populations of mφ in the body and are vital for the maintenance of gut homeostasis. They have several unique properties and are derived from local differentiation of classical Ly6Chi monocytes, but the factors driving this tissue-specific process are not understood. Here we have used global transcriptomic analysis to identify a unique homeostatic signature of mature colonic mφ that is acquired as they differentiate in the mucosa. By comparing the analogous monocyte differentiation process found in the dermis, we identify TGFß as an indispensable part of monocyte differentiation in the intestine and show that it enables mφ to adapt precisely to the requirements of their environment. Importantly, TGFßR signaling on mφ has a crucial role in regulating the accumulation of monocytes in the mucosa, via mechanisms that are distinct from those used by IL10.

The lymph nodes draining the small intestine and colon are anatomically separate and immunologically distinct.

Dendritic cells (DCs) in the small intestine (SI) and colon are fundamental to direct intestinal immune responses; they migrate to the mesenteric lymph nodes (MLNs) and prime T cells. We demonstrate anatomical segregation of lymphatic drainage from the intestine, specifically that DCs from the SI and colon migrate to different nodes within the MLN, here called the sMLN and cMLN. As a consequence, different frequencies of DC subsets observed in the SI and colon are reflected among the DCs in the sMLN and cMLN. Consistent with the SI's function in absorbing food, fed antigen is presented in the sMLN, but not in the cMLN. Furthermore, the levels of expression of CCR9 and α4ß7 are increased on T cells in the sMLN compared with the cMLN. DCs from the cMLN and colon are unable to metabolize vitamin A to retinoic acid (RA); thus, DCs may contribute to the differential expression of tissue homing markers observed in the sMLN and cMLN. In summary, the sMLN and cMLN, and the DCs that migrate to these LNs are anatomically and immunologically separate. This segregation allows immune responses in the SI and colon to be controlled independently.

Colonic tolerance develops in the iliac lymph nodes and can be established independent of CD103(+) dendritic cells.

Tolerance to harmless exogenous antigens is the default immune response in the gastrointestinal tract. Although extensive studies have demonstrated the importance of the mesenteric lymph nodes (MLNs) and intestinal CD103(+) dendritic cells (DCs) in driving small intestinal tolerance to protein antigen, the structural and immunological basis of colonic tolerance remain poorly understood. We show here that the caudal and iliac lymph nodes (ILNs) are inductive sites for distal colonic immune responses and that colonic T cell-mediated tolerance induction to protein antigen is initiated in these draining lymph nodes and not in MLNs. In agreement, colonic tolerance induction was not altered by mesenteric lymphadenectomy. Despite tolerance development, CD103(+)CD11b(+) DCs, which are the major migratory DC population in the MLNs, and the tolerance-related retinoic acid-generating enzyme RALDH2 were virtually absent from the ILNs. Administration of ovalbumin (OVA) to the distal colon did increase the number of CD11c(+)MHCII(hi) migratory CD103(-)CD11b(+) and CD103(+)CD11b(-) DCs in the ILNs. Strikingly, colonic tolerance was intact in Batf3-deficient mice specifically lacking CD103(+)CD11b(-) DCs, suggesting that CD103(-) DCs in the ILNs are sufficient to drive tolerance induction after protein antigen encounter in the distal colon. Altogether, we identify different inductive sites for small intestinal and colonic T-cell responses and reveal that distinct cellular mechanisms are operative to maintain tolerance at these sites.

Lymph-borne CD8α+ dendritic cells are uniquely able to cross-prime CD8+ T cells with antigen acquired from intestinal epithelial cells.

Cross-presentation of cellular antigens is crucial for priming CD8(+) T cells, and generating immunity to intracellular pathogens--particularly viruses. It is unclear which intestinal phagocytes perform this function in vivo. To address this, we examined dendritic cells (DCs) from the intestinal lymph of IFABP-tOVA 232-4 mice, which express ovalbumin in small intestinal epithelial cells (IECs). Among lymph DCs (LDCs) only CD103(+) CD11b(-) CD8α(+) DCs cross-present IEC-derived ovalbumin to CD8(+) OT-I T cells. Similarly, in the mesenteric lymph nodes (MLNs), cross-presentation of IEC-ovalbumin was limited to the CD11c(+) MHCII(hi) CD8α(+) migratory DCs, but absent from all other subsets, including the resident CD8α(hi) DCs. Crucially, delivery of purified CD8α(+) LDCs, but not other LDC subsets, into the MLN subcapsular lymphatic sinus induced proliferation of ovalbumin-specific, gut-tropic CD8(+) T cells in vivo. Finally, in 232-4 mice treated with R848, CD8α(+) LDCs were uniquely able to cross-prime interferon γ-producing CD8(+) T cells and drive their migration to the intestine. Our results clearly demonstrate that migrating CD8α(+) intestinal DCs are indispensable for cross-presentation of cellular antigens and, in conditions of inflammation, for the initial differentiation of effector CD8(+) T cells. They may therefore represent an important target for the development of antiviral vaccinations.

CCR2(+)CD103(-) intestinal dendritic cells develop from DC-committed precursors and induce interleukin-17 production by T cells.

The identification of intestinal macrophages (mφs) and dendritic cells (DCs) is a matter of intense debate. Although CD103(+) mononuclear phagocytes (MPs) appear to be genuine DCs, the nature and origins of CD103(-) MPs remain controversial. We show here that intestinal CD103(-)CD11b(+) MPs can be separated clearly into DCs and mφs based on phenotype, gene profile, and kinetics. CD64(-)CD103(-)CD11b(+) MPs are classical DCs, being derived from Flt3 ligand-dependent, DC-committed precursors, not Ly6C(hi) monocytes. Surprisingly, a significant proportion of these CD103(-)CD11b(+) DCs express CCR2 and there is a selective decrease in CD103(-)CD11b(+) DCs in mice lacking this chemokine receptor. CCR2(+)CD103(-) DCs are present in both the murine and human intestine, drive interleukin (IL)-17a production by T cells in vitro, and show constitutive expression of IL-12/IL-23p40. These data highlight the heterogeneity of intestinal DCs and reveal a bona fide population of CCR2(+) DCs that is involved in priming mucosal T helper type 17 (Th17) responses.

Interleukin-22 binding protein (IL-22BP) is constitutively expressed by a subset of conventional dendritic cells and is strongly induced by retinoic acid.

Interleukin-22 (IL-22) is mainly produced at barrier surfaces by T cells and innate lymphoid cells and is crucial to maintain epithelial integrity. However, dysregulated IL-22 action leads to deleterious inflammation and is involved in diseases such as psoriasis, intestinal inflammation, and cancer. IL-22 binding protein (IL-22BP) is a soluble inhibitory IL-22 receptor and may represent a crucial regulator of IL-22. We show both in rats and mice that, in the steady state, the main source of IL-22BP is constituted by a subset of conventional dendritic cells (DCs) in lymphoid and non-lymphoid tissues. In mouse intestine, IL-22BP was specifically expressed in lamina propria CD103(+)CD11b(+) DC. In humans, IL-22BP was expressed in immature monocyte-derived DC and strongly induced by retinoic acid but dramatically reduced upon maturation. Our data suggest that a subset of immature DCs may actively participate in the regulation of IL-22 activity in the gut by producing high levels of IL-22BP.

Intestinal CD103(-) dendritic cells migrate in lymph and prime effector T cells.

Intestinal dendritic cells (DCs) continuously migrate through lymphatics to mesenteric lymph nodes where they initiate immunity or tolerance. Recent research has focused on populations of intestinal DCs expressing CD103. Here we demonstrate, for the first time, the presence of two distinct CD103(-) DC subsets in intestinal lymph. Similar to CD103(+) DCs, these intestine-derived CD103(-) DCs are responsive to Flt3 and they efficiently prime and confer a gut-homing phenotype to naive T cells. However, uniquely among intestinal DCs, CD103(-) CD11b(+) CX(3)CR1(int) lymph DCs induce the differentiation of both interferon-γ and interleukin-17-producing effector T cells, even in the absence of overt stimulation. Priming by CD103(-) CD11b(+) DCs represents a novel mechanism for the rapid generation of effector T-cell responses in the gut. Therefore, these cells may prove to be valuable targets for the treatment of intestinal inflammation or in the development of effective oral vaccines.

Resident and pro-inflammatory macrophages in the colon represent alternative context-dependent fates of the same Ly6Chi monocyte precursors.

Macrophages (mφ) are essential for intestinal homeostasis and the pathology of inflammatory bowel disease (IBD), but it is unclear whether discrete mφ populations carry out these distinct functions or if resident mφ change during inflammation. We show here that most resident mφ in resting mouse colon express very high levels of CX3CR1, are avidly phagocytic and MHCII(hi), but are resistant to Toll-like receptor (TLR) stimulation, produce interleukin 10 constitutively, and express CD163 and CD206. A smaller population of CX3CR1(int) cells is present in resting colon and it expands during experimental colitis. Ly6C(hi)CCR2(+) monocytes can give rise to all mφ subsets in both healthy and inflamed colon and we show that the CX3CR1(int) pool represents a continuum in which newly arrived, recently divided monocytes develop into resident CX3CR1(hi) mφ. This process is arrested during experimental colitis, resulting in the accumulation of TLR-responsive pro-inflammatory mφ. Phenotypic analysis of human intestinal mφ indicates that analogous processes occur in the normal and Crohn's disease ileum. These studies show for the first time that resident and inflammatory mφ in the intestine represent alternative differentiation outcomes of the same precursor and targeting these events could offer routes for therapeutic intervention in IBD.

Multiple large enteroliths associated with an incisional hernia: a rare case.

The surgeon frequently encounters renal and biliary stones but rarely may also encounter enteric stones or enteroliths. An enterolith is a stony foreign body that is formed in the gastrointestinal tract. We present a rare case of multiple, large enteroliths found associated with a longstanding incarcerated incisional hernia.

Oral tolerance to food protein.

Oral tolerance is the state of local and systemic immune unresponsiveness that is induced by oral administration of innocuous antigen such as food proteins. An analogous but more local process also regulates responses to commensal bacteria in the large intestine and, together, mucosally induced tolerance appears to prevent intestinal disorders such as food allergy, celiac disease, and inflammatory bowel diseases. Here we discuss the anatomical basis of antigen uptake and recognition in oral tolerance and highlight possible mechanisms underlying the immunosuppression. We propose a model of stepwise induction of oral tolerance in which specialized populations of mucosal dendritic cells and the unique microenvironment of draining mesenteric lymph nodes combine to generate regulatory T cells that undergo subsequent expansion in the small intestinal lamina propria. The local and systemic effects of these regulatory T cells prevent potentially dangerous hypersensitivity reactions to harmless antigens derived from the intestine and hence are crucial players in immune homeostasis.

Directed antigen targeting in vivo identifies a role for CD103+ dendritic cells in both tolerogenic and immunogenic T-cell responses.

The αE integrin chain CD103 identifies a subset of migratory dendritic cells (DCs) in the gut, lung, and skin. To gain further understanding of the function of CD103(+) DCs in regulating adaptive immunity in vivo, we coupled ovalbumin (OVA) to the CD103 antibody M290 (M290.OVA). Intraperitoneal injection of M290.OVA induced OVA-specific CD8(+) and CD4(+) T-cell proliferation in lymph nodes (LNs) of wild-type but not CD103(-/-) mice, or in mice depleted of CD11c(+) cells. In the absence of maturation stimuli, systemic antigen targeting to CD103(+) DCs led to tolerance of CD8(+) T cells, whereas coadministration of adjuvant induced cytotoxic T-lymphocyte (CTL) immunity and antibody production. Mucosal intratracheal application of M290.OVA also induced T-cell proliferation in mediastinal LNs, yet the functional outcome was tolerance that inhibited subsequent development of allergic airway inflammation and immunoglobulin E (IgE) responses to inhaled OVA. These findings identify antigen targeting to CD103(+) DCs as a potential strategy to regulate immune responses in nonlymphoid mucosal tissues.

Efficacy and complications of adalimumab treatment for medically-refractory Crohn's disease: analysis of nationwide experience in Scotland (2004-2008).

BACKGROUND: Adalimumab is a second generation humanized anti-tumour necrosis factor (TNF) monoclonal antibody with established efficacy in Crohn's disease (CD). AIMS: To evaluate the efficacy and safety of adalimumab on a nationwide clinical setting. METHODS: We used the Scottish Society of Gastroenterology network to identify and follow up the clinical outcomes of patients with CD treated with adalimumab over a 4-year period (2004-2008). RESULTS: A total of 98 patients received adalimumab - 100.5 patient follow-up years were recorded (64.3% females; median age at diagnosis of 20.7 years; 88.8% treated with 80/40 mg induction regimen. Eighty eight (89.8%) had previous infliximab with 29 (32.9%) primary nonresponders; 32 (32.6%) were corticosteroid-dependent; 47 (47.9%) were intolerant/resistant to most immunosuppressive therapies (two or more). In all, 60% of patients were in clinical remission at 1-year follow-up, with 30% and 55% requiring dose escalation to weekly therapy at 1-and 2-year follow-up respectively. Overall, 29 (29.6%) patients developed complications with eight nonfatal serious (8.2%) adverse events and 2 (2.0%) case fatalities (sepsis following perforation and disseminated colorectal cancer, respectively). CONCLUSIONS: Adalimumab is efficacious in severe and refractory CD in the clinical setting, although there remain significant therapy- and disease-related risks of serious complications.

The effectiveness and cost-effectiveness of minimal access surgery amongst people with gastro-oesophageal reflux disease - a UK collaborative study. The REFLUX trial.

OBJECTIVES: To evaluate the clinical effectiveness, cost-effectiveness and safety of a policy of relatively early laparoscopic surgery compared with continued medical management amongst people with gastro-oesophageal reflux disease (GORD) judged suitable for both policies. DESIGN: Relative clinical effectiveness was assessed by a randomised trial (with parallel non-randomised preference groups) comparing a laparoscopic surgery-based policy with a continued medical management policy. The economic evaluation compared the cost-effectiveness of the two management policies in order to identify the most efficient provision of future care and describe the resource impact that various policies for fundoplication would have on the NHS. SETTING: A total of 21 hospitals throughout the UK with a local partnership between surgeon(s) and gastroenterologist(s) who shared the secondary care of patients with GORD. PARTICIPANTS: The 810 participants, who were identified retrospectively or prospectively via their participating clinicians, had both documented evidence of GORD (endoscopy and/or manometry/24-hour pH monitoring) and symptoms for longer than 12 months. In addition, the recruiting clinician(s) was clinically uncertain about which management policy was best. INTERVENTION: Of the 810 eligible patients who consented to participate, 357 were recruited to the randomised arm of the trial (178 allocated to surgical management, 179 allocated to continued, but optimised, medical management) and 453 recruited to the parallel non-randomised preference arm (261 chose surgical management, 192 chose to continue with best medical management). The type of fundoplication was left to the discretion of the surgeon. MAIN OUTCOME MEASURES: Participants completed a baseline REFLUX questionnaire, developed specifically for this study, containing a disease-specific outcome measure, the Short Form with 36 Items (SF-36), the EuroQol-5 Dimensions (EQ-5D) and the Beliefs about Medicines and Surgery questionnaires (BMQ/BSQ). Postal questionnaires were completed at participant-specific time intervals after joining the trial (equivalent to approximately 3 and 12 months after surgery). Intraoperative data were recorded by the surgeons and all other in-hospital data were collected by the research nurse. At the end of the study period, participants completed a discrete choice experiment questionnaire. RESULTS: The randomised groups were well balanced at entry. Participants had been taking GORD medication for a median of 32 months; the mean age of participants was 46 years and 66% were men. Of 178 randomised to surgery, 111 (62%) actually had fundoplication. There was a mixture of clinical and personal reasons why some patients did not have surgery, sometimes related to long waiting times. A total or partial wrap procedure was performed depending on surgeon preference. Complications were uncommon and there were no deaths associated with surgery. By the equivalent of 12 months after surgery, 38% in the randomised surgical group (14% amongst those who had surgery) were taking reflux medication compared with 90% in the randomised medical group. There were substantial differences (one-third to one-half standard deviation) favouring the randomised surgical group across the health status measures, the size depending on assumptions about the proportion that actually had fundoplication. These differences were the same or somewhat smaller than differences observed at 3 months. The lower the REFLUX score, the worse the symptoms at trial entry and the larger the benefit observed after surgery. The preference surgical group had the lowest REFLUX scores at baseline. These scores improved substantially after surgery, and by 12 months they were better than those in the preference medical group. The BMQ/BSQ and discrete choice experiment did distinguish the preference groups from each other and from the randomised groups. The latter indicated that the risk of serious complications was the most important single attribute of a treatment option. A within-trial cost-effectiveness analysis suggested that the surgery policy was more costly (mean 2049 pounds) but also more effective [+0.088 quality-adjusted life-years (QALYs)]. The estimated incremental cost per QALY was 19,000-23,000 pounds, with a probability between 46% (when 62% received surgery) and 19% (when all received surgery) of cost-effectiveness at a threshold of 20,000 pounds per QALY. Modelling plausible longer-term scenarios (such as lifetime benefit after surgery) indicated a greater likelihood (74%) of cost-effectiveness at a threshold of 20,000 pounds, but applying a range of alternative scenarios indicated wide uncertainty. The expected value of perfect information was greatest for longer-term quality of life and proportions of surgical patients requiring medication. CONCLUSIONS: Amongst patients requiring long-term medication to control symptoms of GORD, surgical management significantly increases general and reflux-specific health-related quality of life measures, at least up to 12 months after surgery. Complications of surgery were rare. A surgical policy is, however, more costly than continued medical management. At a threshold of 20,000 pounds per QALY it may well be cost-effective, especially when putative longer-term benefits are taken into account, but this is uncertain. The more troublesome the symptoms, the greater the potential benefit from surgery. Uncertainty about cost-effectiveness would be greatly reduced by more reliable information about relative longer-term costs and benefits of surgical and medical policies. This could be through extended follow-up of the REFLUX trial cohorts or of other cohorts of fundoplication patients. TRIAL REGISTRATION: Current Controlled Trials ISRCTN15517081.

Enteropathy precedes type 1 diabetes in the BB rat.

BACKGROUND AND AIMS: There is increasing evidence implicating intestinal immune responses to dietary proteins in the pathogenesis of type 1 autoimmune diabetes (T1D). Here we investigated the association between intestinal pathology and dietary factors in T1D by examining the mucosal architecture in the BB rat model. METHODS: BB control (BBc) and diabetes prone (BBdp) rats were fed either a diabetes retardant hydrolysed casein based diet or one of two cereal based diets that promote the development of diabetes. Intestinal architecture was assessed in the jejunum by microdissection, histology, and immunohistology, and by measuring peroxidase activity and brush border invertase levels. RESULTS: Enteropathy was present in BBdp rats soon after weaning, as assessed by increases in crypt length and in the proliferative activity of crypt epithelial cells in the jejunum, and this remained constant until 120 days of age. There was also a decrease in invertase activity, as well as increased numbers of intraepithelial lymphocytes, increased levels of mucosal peroxidase activity, and infiltration of the mucosa by CD4(+) T lymphocytes. Equivalent enteropathy was present at all times in BBdp rats and was not influenced by the nature of the diet or by thymectomy at three weeks at age, procedures which prevent the development of diabetes. CONCLUSION: Enteropathy is a consistent feature in the diabetes prone BB rat but it precedes the onset of insulitis and appears to be due to mechanisms distinct from those which cause diabetes. The beneficial effects of the diabetes retardant hydrolysed casein diet on diabetes are not due to an effect on intestinal architecture per se but mucosal damage may be necessary for the development of autoreactivity in the pancreas.

CTA1-DD-immune stimulating complexes: a novel, rationally designed combined mucosal vaccine adjuvant effective with nanogram doses of antigen.

Mucosally active vaccine adjuvants that will prime a full range of local and systemic immune responses against defined antigenic epitopes are much needed. Cholera toxin and lipophilic immune stimulating complexes (ISCOMS) containing Quil A can both act as adjuvants for orally administered Ags, possibly by targeting different APCs. Recently, we have been successful in separating the adjuvant and toxic effects of cholera toxin by constructing a gene fusion protein, CTA1-DD, that combines the enzymatically active CTA1-subunit with a B cell-targeting moiety, D, derived from Staphylococcus aureus protein A. Here we have extended this work by combining CTA1-DD with ISCOMS, which normally target dendritic cells and/or macrophages. ISCOMS containing a fusion protein comprising the OVA(323-339) peptide epitope linked to CTA1-DD were highly immunogenic when given in nanogram doses by the s.c., oral, or nasal routes, inducing a wide range of T cell-dependent immune responses. In contrast, ISCOMS containing the enzymatically inactive CTA1-R7K-DD mutant protein were much less effective, indicating that at least part of the activity of the combined vector requires the ADP-ribosylating property of CTA1. No toxicity was observed by any route. To our knowledge, this is the first report on the successful combination of two mechanistically different principles of adjuvant action. We conclude that rationally designed vectors consisting of CTA1-DD and ISCOMS may provide a novel strategy for the generation of potent and safe mucosal vaccines.

Oral tolerance.

The ability of the mucosal immune system to distinguish between harmful and harmless antigens is essential for mounting protective immune responses and preventing the induction of mucosal pathology yet the basis for this remains unclear. As fed antigen can also exert systemic effects understanding oral tolerance and priming will also have important consequences for therapy and vaccination. Here we will not only review the increasing amount of information about the potential mechanisms of oral tolerance and priming but also attempt to shed some light on how differences in the uptake and handling i.e. 'the journey' of orally administered antigen may promote these mechanisms.