Nutritional care pathways in cancer patients with malignant bowel obstruction: A retrospective multi-centre study.

INTRODUCTION: Variation in access to parenteral nutrition (PN) in patients with intestinal failure secondary to malignant bowel obstruction (MBO) exists due to differing practice, beliefs and resource access. We aimed to examine differences in nutritional care pathways and outcomes, by referral to nutrition team for PN in patients with MBO. METHODS: This is a retrospective cohort study of MBO adults admitted to eight UK hospitals within a year and 1 year follow-up. Demographic, nutritional and medical data were analysed by comparing patients referred (R) or not referred (NR) for PN. Differences between groups were tested by Kruskal-Wallis, Chi-Squared tests and multi-level regression and survival using Cox regression. RESULTS: 232 patients with 347 MBO admissions [median 66yr, (IQR: 55-74yrs), 67 % female], 79/232 patients were referred for PN (R group). Underlying primary malignancies of gynaecological and gastrointestinal origin predominated (71 %) and 78 % with metastases. Those in the NR group were found to be older, weigh more on admission, and more likely to be treated conservatively compared to those in the R group. For 123 (35 %) admissions, patients were referred to a nutrition team, and for 204 (59 %) admissions, patients were reviewed by a dietician. Multi-disciplinary team discussion and dietetic contact were more likely to occur in the R group-123/347 admissions (R vs NR group: 27 % vs. 7 %, P = 0.001; 95 % vs 39 %, P < 0.0001). Median admission weight loss was 8 % (IQR: 0 to 14). 43/123 R group admissions received inpatient PN only, with 32 patients discharged or already established on home parenteral nutrition. Overall survival was 150 days (126-232) with no difference between R/NR groups. CONCLUSION: In this multi-centre study evaluating nutritional care management of patients with malignant bowel obstruction, only 1 in 3 admissions resulted in a referral to the nutrition team for PN, and just over half were reviewed by a dietician. Further prospective research is required to evaluate possible consequences of these differential care pathways on clinical outcomes and quality of life.

Single-cell analysis of human MAIT cell transcriptional, functional and clonal diversity.

Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognize microbial metabolites through a semi-invariant T cell receptor (TCR). Major questions remain regarding the extent of human MAIT cell functional and clonal diversity. To address these, we analyzed the single-cell transcriptome and TCR repertoire of blood and liver MAIT cells and developed functional RNA-sequencing, a method to integrate function and TCR clonotype at single-cell resolution. MAIT cell clonal diversity was comparable to conventional memory T cells, with private TCR repertoires shared across matched tissues. Baseline functional diversity was low and largely related to tissue site. MAIT cells showed stimulus-specific transcriptional responses in vitro, with cells positioned along gradients of activation. Clonal identity influenced resting and activated transcriptional profiles but intriguingly was not associated with the capacity to produce IL-17. Overall, MAIT cells show phenotypic and functional diversity according to tissue localization, stimulation environment and clonotype.

A conserved population of MHC II-restricted, innate-like, commensal-reactive T cells in the gut of humans and mice.

Interactions with commensal microbes shape host immunity on multiple levels and play a pivotal role in human health and disease. Tissue-dwelling, antigen-specific T cells are poised to respond to local insults, making their phenotype important in the relationship between host and microbes. Here we show that MHC-II restricted, commensal-reactive T cells in the colon of both humans and mice acquire transcriptional and functional characteristics associated with innate-like T cells. This cell population is abundant and conserved in the human and murine colon and endowed with polyfunctional effector properties spanning classic Th1- and Th17-cytokines, cytotoxic molecules, and regulators of epithelial homeostasis. T cells with this phenotype are increased in ulcerative colitis patients, and their presence aggravates pathology in dextran sodium sulphate-treated mice, pointing towards a pathogenic role in colitis. Our findings add to the expanding spectrum of innate-like immune cells positioned at the frontline of intestinal immune surveillance, capable of acting as sentinels of microbes and the local cytokine milieu.

Adenovirus vectors activate Vδ2+ γδT cells in a type I interferon-, TNF-, and IL-18-dependent manner.

Vδ2+ γδT cells are unconventional T cells that can be activated by cytokines without TCR signaling. Adenovirus vaccine vectors activated Vδ2+ γδT cells in an interleukin 18-, TNF-, and type I interferon-dependent manner. This stimulatory capacity was associated with adenovirus vectors of non-species C origin, including the ChAdOx1 vaccine platform.

Interferon-Gamma-Producing CD8+ Tissue Resident Memory T Cells Are a Targetable Hallmark of Immune Checkpoint Inhibitor-Colitis.

BACKGROUND & AIMS: The pathogenesis of immune checkpoint inhibitor (ICI)-colitis remains incompletely understood. We sought to identify key cellular drivers of ICI-colitis and their similarities to idiopathic ulcerative colitis, and to determine potential novel therapeutic targets. METHODS: We used a cross-sectional approach to study patients with ICI-colitis, those receiving ICI without the development of colitis, idiopathic ulcerative colitis, and healthy controls. A subset of patients with ICI-colitis were studied longitudinally. We applied a range of methods, including multiparameter and spectral flow cytometry, spectral immunofluorescence microscopy, targeted gene panels, and bulk and single-cell RNA sequencing. RESULTS: We demonstrate CD8+ tissue resident memory T (TRM) cells are the dominant activated T cell subset in ICI-colitis. The pattern of gastrointestinal immunopathology is distinct from ulcerative colitis at both the immune and epithelial-signaling levels. CD8+ TRM cell activation correlates with clinical and endoscopic ICI-colitis severity. Single-cell RNA sequencing analysis confirms activated CD8+ TRM cells express high levels of transcripts for checkpoint inhibitors and interferon-gamma in ICI-colitis. We demonstrate similar findings in both anti-CTLA-4/PD-1 combination therapy and in anti-PD-1 inhibitor-associated colitis. On the basis of our data, we successfully targeted this pathway in a patient with refractory ICI-colitis, using the JAK inhibitor tofacitinib. CONCLUSIONS: Interferon gamma-producing CD8+ TRM cells are a pathological hallmark of ICI-colitis and a novel target for therapy.

MAIT cell activation augments adenovirus vector vaccine immunogenicity.

Mucosal-associated invariant T (MAIT) cells are innate sensors of viruses and can augment early immune responses and contribute to protection. We hypothesized that MAIT cells may have inherent adjuvant activity in vaccine platforms that use replication-incompetent adenovirus vectors. In mice and humans, ChAdOx1 (chimpanzee adenovirus Ox1) immunization robustly activated MAIT cells. Activation required plasmacytoid dendritic cell (pDC)-derived interferon (IFN)-α and monocyte-derived interleukin-18. IFN-α-induced, monocyte-derived tumor necrosis factor was also identified as a key secondary signal. All three cytokines were required in vitro and in vivo. Activation of MAIT cells positively correlated with vaccine-induced T cell responses in human volunteers and MAIT cell-deficient mice displayed impaired CD8+ T cell responses to multiple vaccine-encoded antigens. Thus, MAIT cells contribute to the immunogenicity of adenovirus vectors, with implications for vaccine design.

Human intestinal tissue-resident memory T cells comprise transcriptionally and functionally distinct subsets.

Tissue-resident memory T (TRM) cells provide key adaptive immune responses in infection, cancer, and autoimmunity. However, transcriptional heterogeneity of human intestinal TRM cells remains undefined. Here, we investigate transcriptional and functional heterogeneity of human TRM cells through study of donor-derived TRM cells from intestinal transplant recipients. Single-cell transcriptional profiling identifies two transcriptional states of CD8+ TRM cells, delineated by ITGAE and ITGB2 expression. We define a transcriptional signature discriminating these populations, including differential expression of cytotoxicity- and residency-associated genes. Flow cytometry of recipient-derived cells infiltrating the graft, and lymphocytes from healthy gut, confirm these CD8+ TRM phenotypes. CD8+ CD69+CD103+ TRM cells produce interleukin-2 (IL-2) and demonstrate greater polyfunctional cytokine production, whereas ß2-integrin+CD69+CD103- TRM cells have higher granzyme expression. Analysis of intestinal CD4+ T cells identifies several parallels, including a ß2-integrin+ population. Together, these results describe the transcriptional, phenotypic, and functional heterogeneity of human intestinal CD4+ and CD8+ TRM cells.

Unique and Common Features of Innate-Like Human Vδ2+ γδT Cells and Mucosal-Associated Invariant T Cells.

Mucosal-associated invariant T (MAIT) cells are innate-like T cells abundant in humans that can be activated in a TCR-independent manner by inflammatory and antiviral cytokines. In humans, the capacity for TCR-independent activation is functionally linked to a transcriptional program that can be identified by the expression of the C-type lectin receptor, CD161. In addition to MAIT cells, it has been demonstrated that a subset of γδT cells expresses CD161 and can be activated by TCR-independent cytokine stimulation. In this study, we sought to clarify the nature of cytokine-responsive human γδT cells. We could link CD161 expression on Vδ2+ versus Vδ1+ γδT cells to the observation that Vδ2+ γδT cells, but not Vδ1+ γδT cells, robustly produced IFN-γ upon stimulation with a variety of cytokine combinations. Interestingly, both CD161+ and CD161- Vδ2+ γδT cells responded to these stimuli, with increased functionality within the CD161+ subset. This innate-like responsiveness corresponded to high expression of PLZF and IL-18Rα, analogous to MAIT cells. Vδ2+ γδT cells in human duodenum and liver maintained a CD161+ IL-18Rα+ phenotype and produced IFN-γ in response to IL-12 and IL-18 stimulation. In contrast to MAIT cells, we could not detect IL-17A production but observed higher steady-state expression of Granzyme B by Vδ2+ γδT cells. Finally, we investigated the frequency and functionality of γδT cells in the context of chronic hepatitis C virus infection, as MAIT cells are reduced in frequency in this disease. By contrast, Vδ2+ γδT cells were maintained in frequency and displayed unimpaired IFN-γ production in response to cytokine stimulation. In sum, human Vδ2+ γδT cells are a functionally distinct population of cytokine-responsive innate-like T cells that is abundant in blood and tissues with similarities to human MAIT cells.