Circulating and Tissue-Resident CD4+ T Cells With Reactivity to Intestinal Microbiota Are Abundant in Healthy Individuals and Function Is Altered During Inflammation.

BACKGROUND & AIMS: Interactions between commensal microbes and the immune system are tightly regulated and maintain intestinal homeostasis, but little is known about these interactions in humans. We investigated responses of human CD4+ T cells to the intestinal microbiota. We measured the abundance of T cells in circulation and intestinal tissues that respond to intestinal microbes and determined their clonal diversity. We also assessed their functional phenotypes and effects on intestinal resident cell populations, and studied alterations in microbe-reactive T cells in patients with chronic intestinal inflammation. METHODS: We collected samples of peripheral blood mononuclear cells and intestinal tissues from healthy individuals (controls, n = 13-30) and patients with inflammatory bowel diseases (n = 119; 59 with ulcerative colitis and 60 with Crohn's disease). We used 2 independent assays (CD154 detection and carboxy-fluorescein succinimidyl ester dilution assays) and 9 intestinal bacterial species (Escherichia coli, Lactobacillus acidophilus, Bifidobacterium animalis subsp lactis, Faecalibacterium prausnitzii, Bacteroides vulgatus, Roseburia intestinalis, Ruminococcus obeum, Salmonella typhimurium, and Clostridium difficile) to quantify, expand, and characterize microbe-reactive CD4+ T cells. We sequenced T-cell receptor Vß genes in expanded microbe-reactive T-cell lines to determine their clonal diversity. We examined the effects of microbe-reactive CD4+ T cells on intestinal stromal and epithelial cell lines. Cytokines, chemokines, and gene expression patterns were measured by flow cytometry and quantitative polymerase chain reaction. RESULTS: Circulating and gut-resident CD4+ T cells from controls responded to bacteria at frequencies of 40-4000 per million for each bacterial species tested. Microbiota-reactive CD4+ T cells were mainly of a memory phenotype, present in peripheral blood mononuclear cells and intestinal tissue, and had a diverse T-cell receptor Vß repertoire. These cells were functionally heterogeneous, produced barrier-protective cytokines, and stimulated intestinal stromal and epithelial cells via interleukin 17A, interferon gamma, and tumor necrosis factor. In patients with inflammatory bowel diseases, microbiota-reactive CD4+ T cells were reduced in the blood compared with intestine; T-cell responses that we detected had an increased frequency of interleukin 17A production compared with responses of T cells from blood or intestinal tissues of controls. CONCLUSIONS: In an analysis of peripheral blood mononuclear cells and intestinal tissues from patients with inflammatory bowel diseases vs controls, we found that reactivity to intestinal bacteria is a normal property of the human CD4+ T-cell repertoire, and does not necessarily indicate disrupted interactions between immune cells and the commensal microbiota. T-cell responses to commensals might support intestinal homeostasis, by producing barrier-protective cytokines and providing a large pool of T cells that react to pathogens.

Development of a Vitamin B12 Deficiency Patient-Reported Outcome Measure for Clinical Practice and Research.

BACKGROUND: It is difficult to recognize vitamin B12 deficiency and to evaluate the effect of B12 treatment due to a broad range of variable clinical symptoms overlapping with other diseases and diagnostic biomarkers that quickly normalize during treatment. This poses a risk of delay in diagnosis and a challenge to uniformly monitor the effect of B12 treatment. There is a need for a new clinical outcome measure suitable for clinical practice and clinical evaluation studies. OBJECTIVE: To develop a Patient-Reported Outcome Measure (PROM) which measures the severity of vitamin B12 deficiency symptoms. METHODS: The B12 PROM was developed by (1) gathering input from experts and literature review to define a construct and develop a conceptual model, (2) processing input from health care providers, scientists, and patients to develop items and response options, and (3) improving items based on the feedback from laypersons, test interviews, semi-structured cognitive interviews with patients, and forward and backward translation (ENG-NL). RESULTS: The B12 PROM includes 62 items grouped into 8 categories of symptoms related to vitamin B12 deficiency (General, Senses, Thinking, In limbs and/or face, Movement, Emotions, Mouth & Abdomen, Urinary tract & Reproductive organs). Cognitive interviews demonstrated good comprehensibility and comprehensiveness. CONCLUSIONS: This study is the first step in the development of a disease-specific PROM for vitamin B12 deficiency to measure the burden of symptoms. Further validation and reliability testing are necessary before the PROM can be applied in clinical practice and research.

Plain language titleDevelopment of a Vitamin B12 Deficiency Questionnaire for Clinical Practice and ResearchPlain language summaryThis study is the first step in the development of a questionnaire for vitamin B12 deficiency to measure the severity of vitamin B12 deficiency symptoms. The questionnaire includes 62 items grouped into 8 categories of symptoms related to vitamin B12 deficiency (General, Senses, Thinking, In limbs and/or face, Movement, Emotions, Mouth & Abdomen, Urinary tract & Reproductive organs). Interviews with patients demonstrated good comprehensibility and comprehensiveness of the questionnaire. Further testing is necessary before the questionnaire can be applied in clinical practice and research.

A Systematic Review of Symptoms of Pernicious Anemia.

BACKGROUND: Pernicious anemia (PA) is a type of macrocytic anemia caused by autoimmune gastritis. To facilitate timely diagnosis and treatment of PA there is a pressing need for improved understanding among Healthcare providers of the condition's symptoms and diagnostic criteria. OBJECTIVE: This systematic review aims to extend existing clinical knowledge on the presentation of PA by determining which symptoms and clinical complications are reported in published adult case studies. METHODS: Relevant studies were identified through electronic searches of PsycINFO, Embase, and MEDLINE, via OvidSP. During data extraction symptoms were categorized according to the International Classification of Diseases and were grouped based on frequency. RESULTS: Symptoms were documented for 103 adults with a diagnosis of PA; the most frequent symptoms were fatigue (55%), loss of sensation in limbs (32%), excessive weight loss (27%), and a sore tongue (23%). CONCLUSIONS: This review highlights the diverse symptomology of adults who are diagnosed with PA. Most symptoms documented in case studies are consistent with the core signs of B12 and folate deficiencies. Research is needed to identify if there are common clusters of PA symptoms that can be used as prompts for diagnostic testing in patients with suspected B12 deficiency.

Plain language titleA Review of Symptoms of Pernicious AnemiaPlain language summaryThis study reviewed case studies that have been written about adults with pernicious anemia, it has documented the frequency of the core symptoms and the impact these have on health.