Phenotypic and functional characterisation of human macrophages – A potential role for gut resident macrophages in colorectal cancer.
High infiltration of macrophages in colorectal cancer is associated with improved patient prognosis. This association is the opposite of what is observed in other cancers, however, we are yet to understand why. Previous approaches to study this have been too superficial and overlooked the complexity of macrophages. As a result current data is conflicting. This study aims to characterise human macrophages in greater detail, and to therefore resolve these ambiguities. Multicolour flow cytometry, ELISAs, Greiss assays and qPCR, have been used to define a more detailed phenotype of human macrophage populations in vitro and also in colorectal cancer patient tissue samples. Using these methods, a further level of phenotypic complexity and plasticity, which was previously overlooked, has been unveiled. Macrophage phenotypes were defined, and the plasticity of these phenotypes under different stimuli was assessed. M1 macrophages were found to be CD11b+, CD64+, CD14-, CD206+/lo and CD163-. M2 populations were found to be CD11b+, CD64+, CD14hi, CD206+ and CD163. These were subsequently detected, using the same approach, in both tumour tissue and non-transformed bowel tissue from colorectal cancer patients. Analysis of this tissue also revealed a large population of gut resident macrophages, with a unique phenotype, present in both tumour and non-transformed bowel tissue. This study highlights the complexity of macrophages and also provides methods to examine them ex vivo from human tissue. Data gained from this work could be used for future work looking at macrophages as both prognostic and therapeutic targets.
Advisor: Kemp, Roslyn
Degree Name: Bachelor of Biomedical Sciences with Honours
Degree Discipline: Microbiology and Immunology
Publisher: University of Otago
Keywords: Macrophages; Cancer; Colorectal; M1; M2; Flow Cytometry; Immunology; Gut; gut resident macrophages; human samples
Research Type: Thesis