Summary Background Alopecia areata (AA) is a common autoimmune disease, causing patchy hair loss that can progress to involve the entire scalp (totalis) or body (universalis). CD8+NKG2D+ T cells dominate hair follicle pathogenesis, but the specific mechanisms driving hair loss are not fully understood. Objectives To provide a detailed insight into the systemic cytokine signature associated with AA, and to assess the association between cytokines and depression. Methods We conducted multiplex analysis of plasma cytokines from patients with AA, patients with psoriatic arthritis (PsA) and healthy controls. We used the Hospital Anxiety and Depression Scale (HADS) to assess the occurrence of depression and anxiety in our cohort. Results Our analysis identified a systemic inflammatory signature associated with AA, characterized by elevated levels of interleukin (IL)‐17A, IL‐17F, IL‐21 and IL‐23 indicative of a type 17 immune response. Circulating levels of the type 2 cytokines IL‐33, IL‐31 and IL‐17E (IL‐25) were also significantly increased in AA. In comparison with PsA, AA was associated with higher levels of IL‐17F, IL‐17E and IL‐23. We hypothesized that circulating inflammatory cytokines may contribute to wider comorbidities associated with AA. Our assessment of psychiatric comorbidity in AA using HADS scores showed that 18% and 51% of people with AA experienced symptoms of depression and anxiety, respectively. Using linear regression modelling, we identified that levels of IL‐22 and IL‐17E are positively and significantly associated with depression. Conclusions Our data highlight changes in both type 17 and type 2 cytokines among people with AA, suggesting that complex systemic cytokine profiles may contribute both to the pathogenesis of AA and to the associated depression. What's already known about this topic? NKG2D+CD8+ T cells cause hair loss in alopecia areata (AA) but the immunological mechanisms underlying the disease are not fully understood. AA is associated with changes in levels of interleukin (IL)‐6, tumour necrosis factor‐α, IL‐1β and type 17 cytokines. Psychiatric comorbidity is common among people with AA. What does this study add? People with AA have increased plasma levels of the type 2 cytokines IL‐33, IL‐31 and IL‐17E (IL‐25), in addition to the type 17 cytokines IL‐17A, IL‐21, IL‐23 and IL‐17F. Levels of IL‐17E and IL‐22 positively predict depression score. What is the translational message? AA is associated with increased levels of multiple inflammatory cytokines, implicating both type 17‐ and type 2 immune pathways. Our data indicate that therapeutic strategies for treating AA may need to address the underlying type 17‐ and type 2 immune dysregulation, rather than focusing narrowly on the CD8+ T‐cell response. An immunological mechanism might contribute directly to the depression observed in people with AA.

Summary Crosstalk between the immune system and the nervous system, via neurotransmitters such as dopamine, is increasingly of interest as we begin to learn how lymphocytes in peripheral tissues can both produce and respond to these molecules. This crosstalk can modulate immune responses by influencing the local tissue environment and can, for instance, influence the activation status and migration of T cells. Immune cells also use neurotransmitters to communicate with each other. Understanding how neurotransmitters influence the immune system may provide novel approaches for targeting diseases associated with tissue‐specific inflammation, such as psoriasis.

Alopecia areata (AA) is an immune-mediated disease which causes non-scarring hair loss. Autoreactive CD8 T cells are key pathogenic effectors in the skin, and AA has been associated both with atopy, and with perturbations in intestinal homeostasis. This study aimed to investigate mechanisms driving AA by characterising the circulating immunophenotype and faecal microbiome, and by stratifying AA to understand how identified signatures associate with heterogeneous clinical features of the condition. Flow cytometric analyses identified alterations in circulating B cells and CD4 T cells, while 16S sequencing identified changes in alpha and beta diversity in the faecal microbiome in AA. The proportions of transitional and naïve B cells were found to be elevated in AA, particularly in AA samples from individuals with >50% hair loss and those with comorbid atopy, which is commonly associated with extensive hair loss. Although significant changes in circulating CD8 T cells were not observed, we found significant changes in CD4 + populations. In individuals with <50% hair loss higher frequencies of CCR6 +CD4 (“Th17”) and CCR6 +CXCR3 +CD4 (“Th1/17”) T cells were found. While microbial species richness was not altered, AA was associated with reduced evenness and Shannon diversity of the intestinal microbiota, again particularly in those with <50% hair loss. We have identified novel immunological and microbial signatures in individuals with alopecia areata. Surprisingly, these are associated with lower levels of hair loss, and may therefore provide a rationale for improved targeting of molecular therapeutics.

Background Crohn’s disease (CD) is a chronic inflammatory gastrointestinal condition, with globally increasing incidence. Patients with CD suffer from a loss of tolerance towards their commensal microbiota causing an aberrant immune response, occurring in a protracted relapse and remission cycle. Although a variety of frontline therapies is currently available, including targeted therapies such as biologic drugs, 30–40% of CD patients still require surgery to manage the disease. At present, the immunobiology of CD is not fully understood. However, differences in immune responses between patients might play an important role in diverse treatment responses. The aim of this study was to identify differences in peripheral and local immune responses of CD to understand differences in disease behaviour and treatment outcome. Methods Peripheral blood mononuclear cells and plasma were isolated from whole blood of a cross-sectional CD patient cohort (nCD = 12) and normal controls (NC, nNC = 28). Flow cytometry analysis and multiplex assays were used to quantify immune cell populations and cytokine levels, respectively. The local immune response was analysed by bulk RNA sequencing of mucosal colonic biopsies either from inflamed CD or normal tissue. Gene signatures were then followed up by validation in publicly deposited gene expression datasets (nCD = 36, nNC = 24), and by measurement of specific proteins using our archived samples. Results Peripheral immunophenotyping of the initial cross-sectional study displayed three different types of CD patients, characterised by either a decrease in leukocyte populations, an increase of cytokines, or a change in both. Analysis of the RNAseq data derived from colonic biopsies revealed four distinct clusters in genes associated with the immune response in CD patients. Further pathway analysis showed one cluster with an enriched B cell signature and another cluster with an elevated macrophage and neutrophil response. We utilised publicly available gene expression datasets to validate these signatures in a larger cohort and identified a selection of patients with an up-regulated pro-inflammatory macrophage response. Using correlation analysis, we suggest an immunopathotype with increased macrophage activation which is potentially associated with a more severe form of the disease. Conclusion We have identified distinct immunopathotypes in both the peripheral and local immune response of CD patients. Further investigation will correlate these distinct immune responses in CD with clinical parameters, to understand associations between diverse treatment responses and disease behaviours.

could rationalise testing and reduce unnecessary referrals, without delaying IBD diagnoses. Methods All primary care FCP tests processed for 0-16 year olds in Bristol were obtained for between Oct. 2016 -Mar. 2017 and Oct. 2018 -Mar. 2019. Hospital records were reviewed to identify associated referrals to specialist services and any subsequent diagnoses. Patients with a pre-existing IBD diagnosis were excluded.A clinical algorithm was subsequently constructed and tested against results available at referral from 50 IBD cases diagnosed at the Bristol Children's Hospital (May 2018 -Jul. 2019) to assess its sensitivity for IBD cases. ResultsThe number of patients receiving FCP tests had increased by 92% between the 2016/17 and 2018/19 samples to 254. Referrals in response to these presentations increased by 58% in the same period to 63.Of the 2018/19 referrals, 63% made explicit reference to a FCP result perceived to be elevated and 11 referrals (17%) resulted in a IBD diagnosis. 14% of referred patients were £ 4 years, 21% 5-8 years and 65% 9-16 years. The most common presenting symptoms were abdominal pain (67%), loose stools (57%), weight/growth concern (14%) and rectal blood (19%).Of all FCP tests ordered, 25% were moderately elevated (50-199 mg/g) and case examples highlighted a lack of consistency in the management of such equivocal results and presentations. The above analysis also illustrates a proportion of FCP testing in situations where it was unlikely to be instructive (e.g. those £ 4 years; active rectal bleeding). Such examples represented opportunities to rationalise testing and interpretation. Constructing an algorithm accordingly, we trialled this approach on 50 IBD diagnoses in a validation sample, which indicated all would have been successfully referred. Conclusion There has been an increase in faecal calprotectin testing in primary care since 2016/17, generating an associated increase in referrals. Our proposed clinical algorithm did not lead to missed or delayed IBD diagnoses in our validation sample, suggesting that faecal calprotectin testing and referrals to hospital care could be streamlined if the algorithm was used in primary care.