Mapping the Human Appendix Using Single Cell Sequencing
- Conditions
- DiabetesAppendicitisInflammatory Bowel Diseases
- Interventions
- Other: Biopsy
- Registration Number
- NCT05209061
- Lead Sponsor
- Bispebjerg Hospital
- Brief Summary
The overall purpose of this study is to describe the cellular composition of the human appendix and its gene expression using scRNAseq and scATACseq methods. This will potentially provide is with a complete and detailed map of the appendix´ immunological properties and its role in neuro-endocrine/metabolic functions. Our results will be held up against current knowledge of the appendix and its role in the human body and thus hopefully expand our understanding of this organ and the consequences of its removal by appendectomy.
- Detailed Description
Until recently the human appendix was viewed as a rudimentary organ without any specific function in the human body. Our current knowledge of the cellular composition of the appendix is solely based on histological examinations combined with immunohistochemical stains. These examinations have shown that the structural composition of the appendix is similar to the large intestine, with mucosa, submucosa, muscularis externa and serosa. Uniquely, the appendix has almost circumferential lymphoid follicles in the submucosa and lamina propria, and thus becomes a secondary lymphoid organ. In addition to this, the appendix contains Lieberkühn's crypts, which in contrast to the large intestine contains Paneth cells and argentaffine (enterochromaffin) neuro-endocrine cells1 2
Recently, the appendix´ role in regulation of immunologic functions has been discovered. It is believed that the great bacterial diversity in the appendix stimulates the human immune system and aids in the maturation and diversification of white blood cells, especially B-cells in the lymphoid follicles in the appendix.3 The appendix contains a larger quantity of CD5+ (B1), CD19+, Immunoglobulin-secreting IgG and secretory IgA cells compared to the large intestine. In the luminal follicle-associated epithelium, a high concentration of intra-epithelial M-cells as well as human leukocyte antigen D-related (HLA-DR) T and B cells are seen.4
The human appendix has a unique cellular composition, which plays a role in bacterial homeostasis in the large intestine5 and entero-endocrine regulation6. Furthermore, removing the appendix can drastically change incidence of certain metabolic and immune-related diseases such as type II diabetes7 and ulcerative colitis8. Despite this, only very few studies have investigated the cellular composition of the human appendix, and none of these have used single-cell (sc) RNA or DNA-sequencing to aid in our understanding of this organ.
By using scRNAseq and scATACseq (Single-cell Assay of Transposase Accessible Chromatin sequencing) we will be able to map open regions in the cell's DNA and RNA, thus providing us with a unique "map" of the cells in the appendix as well is their gene expression9-11. ScATACseq visualizes open regions in the chromatin, generating "peaks" which can then be used to map DNA motifs, such as transcription factor binding sites. With the emergence of scATACseq, chromatin accessibility is in combination with gene expression data an extremely useful resource to study cell type specific regulatory DNA interactions. To further study the immunological aspects of the appendix, we will extract immune cells from the Peyer´s plaques. Lastly, full blood will be extracted to better analyse metabolic risk factors in relation to the appendix´ metabolic cellular regulation.
Recruitment & Eligibility
- Status
- RECRUITING
- Sex
- All
- Target Recruitment
- 5
Patients undergoing a right or extended right-hemicolectomy for colon cancer
Patients able to read and understand danish
Patients able to give informed consent
Patients of Scandinavian ethnicity
Previous large bowel resections
Suspicion pre or intraoperatively of disease in the appendix
Tumour <10cm from the appendiceal orifice.
Known inflammatory bowel disease
Immuno-modulation treatment
Neo-adjuvant chemotherapy.
< 18 years of age
Study & Design
- Study Type
- OBSERVATIONAL
- Study Design
- Not specified
- Arm && Interventions
Group Intervention Description Colo-rectal cancer patients Biopsy Patients receiving right colectomy or ileo-ceacal resection for colorectal cancer
- Primary Outcome Measures
Name Time Method Profiling of open chromatin regions 2 years Mapping of cell types, including rare cell types, using profiling of open chromatin regions. (ATAC-seq) in biopsies from the appendix
Evaluation of metabolic profile 2 years Using bioimpedance, insulin and glucose measurements and CHiP-seq we will determine patient phenotype and epigenetics to evaluate their metabolic risk-profile and correlate this to cell types in the appendix
- Secondary Outcome Measures
Name Time Method Appendix biofilm 2 years By sequencing bacterial DNA in our samples, we will evaluate the mucosa-associated microbiome of the appendix. This will be correlated to the two primary outcome measure
Trial Locations
- Locations (1)
Bispebjerg University Hospital
🇩🇰Copenhagen, Denmark