Synthetic 5-amino-6-D-ribitylaminouracil paired with inflammatory stimuli facilitates MAIT cell expansion in vivo.

Introduction: Mucosal-associated invariant T (MAIT) cells are a population of innate-like T cells, which mediate host immunity to microbial infection by recognizing metabolite antigens derived from microbial riboflavin synthesis presented by the MHC-I-related protein 1 (MR1). Namely, the potent MAIT cell antigens, 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU) and 5-(2-oxoethylideneamino)-6-D-ribitylaminouracil (5-OE-RU), form via the condensation of the riboflavin precursor 5-amino-6-D-ribitylaminouracil (5-A-RU) with the reactive carbonyl species (RCS) methylglyoxal (MG) and glyoxal (G), respectively. Although MAIT cells are abundant in humans, they are rare in mice, and increasing their abundance using expansion protocols with antigen and adjuvant has been shown to facilitate their study in mouse models of infection and disease. Methods: Here, we outline three methods to increase the abundance of MAIT cells in C57BL/6 mice using a combination of inflammatory stimuli, 5-A-RU and MG. Results: Our data demonstrate that the administration of synthetic 5-A-RU in combination with one of three different inflammatory stimuli is sufficient to increase the frequency and absolute numbers of MAIT cells in C57BL/6 mice. The resultant boosted MAIT cells are functional and can provide protection against a lethal infection of Legionella longbeachae. Conclusion: These results provide alternative methods for expanding MAIT cells with high doses of commercially available 5-A-RU (± MG) in the presence of various danger signals.

CD8 coreceptor engagement of MR1 enhances antigen responsiveness by human MAIT and other MR1-reactive T cells.

Mucosal-associated invariant T (MAIT) cells detect microbial infection via recognition of riboflavin-based antigens presented by the major histocompatibility complex class I (MHC-I)-related protein 1 (MR1). Most MAIT cells in human peripheral blood express CD8αα or CD8αß coreceptors, and the binding site for CD8 on MHC-I molecules is relatively conserved in MR1. Yet, there is no direct evidence of CD8 interacting with MR1 or the functional consequences thereof. Similarly, the role of CD8αα in lymphocyte function remains ill-defined. Here, using newly developed MR1 tetramers, mutated at the CD8 binding site, and by determining the crystal structure of MR1-CD8αα, we show that CD8 engaged MR1, analogous to how it engages MHC-I molecules. CD8αα and CD8αß enhanced MR1 binding and cytokine production by MAIT cells. Moreover, the CD8-MR1 interaction was critical for the recognition of folate-derived antigens by other MR1-reactive T cells. Together, our findings suggest that both CD8αα and CD8αß act as functional coreceptors for MAIT and other MR1-reactive T cells.

The balance of interleukin-12 and interleukin-23 determines the bias of MAIT1 versus MAIT17 responses during bacterial infection.

Mucosal-associated invariant T (MAIT) cells are a major subset of innate-like T cells mediating protection against bacterial infection through recognition of microbial metabolites derived from riboflavin biosynthesis. Mouse MAIT cells egress from the thymus as two main subpopulations with distinct functions, namely, T-bet-expressing MAIT1 and RORγt-expressing MAIT17 cells. Previously, we reported that inducible T-cell costimulator and interleukin (IL)-23 provide essential signals for optimal MHC-related protein 1 (MR1)-dependent activation and expansion of MAIT17 cells in vivo. Here, in a model of tularemia, in which MAIT1 responses predominate, we demonstrate that IL-12 and IL-23 promote MAIT1 cell expansion during acute infection and that IL-12 is indispensable for MAIT1 phenotype and function. Furthermore, we showed that the bias toward MAIT1 or MAIT17 responses we observed during different bacterial infections was determined and modulated by the balance between IL-12 and IL-23 and that these responses could be recapitulated by cytokine coadministration with antigen. Our results indicate a potential for tailored immunotherapeutic interventions via MAIT cell manipulation.

Single-cut osteotomy for correction of a complex multiplanar deformity of the radius in a Shetland pony foal.

OBJECTIVE: To describe the surgical correction of a multiplanar deformity of the radius in a pony using a single-cut osteotomy. STUDY DESIGN: Case report. ANIMALS: A 9-week-old male Shetland pony foal with a bodyweight of 47 kg. METHODS: The foal presented with a complex multiplanar deformity of the right radius. A 3-dimensional model of the bone was created based on computed tomography (CT) imaging. To correct the deformity, the cutting plane for a single-cut osteotomy was calculated following the mathematical approach described by Sangeorzan et al. After osteotomy, the bone was realigned and stabilized with two 4.5 locking compression plates (LCPs). RESULTS: Recovery from surgery was uneventful, and the foal remained comfortable. A CT exam 15 weeks after surgery revealed that diaphyseal deformities improved substantially in procurvatum (from 8° to 1°), varus (from 27° to 0°), and rotation (30° to 5°). The operated radius was 2.1 cm shorter than the left. Eighteen-month follow up confirmed a functionally and cosmetically acceptable outcome. CONCLUSION: The single-cut osteotomy resulted in the successful correction of a multiplanar equine long-bone deformity with a favorable outcome in a Shetland pony. CLINICAL SIGNIFICANCE: Single-cut osteotomy is an alternative surgical technique for the correction of complex diaphyseal long-bone equine deformities. Computed tomography data and the possibility of printing 3D models provides a significant advantage for rehearsing the procedure and for evaluating the correction that was achieved.

Position of the midline septum of the guttural pouches in horses subjected to computed tomography.

Standing computed tomographic (CT) examination of the equine guttural pouch frequently reveals deviation of the midline septum. The significance of deviation is currently unknown. The aims of this retrospective, single-centre study were to determine the prevalence of deviation of the midline septum of the guttural pouch and determine whether there was an association between the presence and degree of deviation of the septum, and guttural pouch disease. Case records were reviewed, identifying 95 horses that had undergone a standing, sedated, head CT and guttural pouch endoscopy. The presence, laterality, subjective degree and angle of deviation of the midline septum on CT was recorded. A total of 69 (72.6%) horses were identified with deviation of the midline septum, with the mean angle of deviation 13.4o and a maximum deviation of 52.6o. No significant association between the presence of deviation of the midline septum (P = .722) or severity of deviation (P = .428) and an endoscopic abnormality within the guttural pouch was found. The laterality of deviation and guttural pouch abnormalities were also not associated (P = .000). Deviation of the midline septum of the guttural pouch is a common finding on CT examination, and does not have clinical significance in this study.

Improving outcomes for patients discharged early using a home assessment scheme.

BACKGROUND: With increased delayed discharges from acute NHS hospitals, especially for older patients, solutions like the 'Discharge to Assess' (D2A) scheme aim to facilitate quicker discharge and improve experiences for patients and carers. SETTING: This report examines the quality process from the patient perspective of the D2A scheme implemented in a London Northwest Healthcare NHS Trust (LNWHT). A retrospective audit was conducted using the first cohort of patients discharged through this pilot scheme from April to July 2017. QUESTION: A brief study to explore patient views of their experience of the D2A scheme. METHODS: An opportunistic audit comprised of brief telephone interviews with patients following discharge from hospital through the D2A scheme. RESULTS: 30 patients who had been discharged with the D2A scheme, agreed to participate. Overall, patients were positive about their experience and valued the support and services provided. However, there were concerns on the issue of communication. The scheme effectiveness from the patient's perspective improved over the duration of the evaluation. DISCUSSION: Patients' views about their experiences changed over time, which included patients' perceptions of the discharge process, patients' expectations and the way in which they were able to access services.