The role of glycans in modulating innate immunity towards cancer prevention

• Main Author: Pedro Filipe Neves de Almeida
• Publication Date: 2023
• Format: Master thesis
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: https://hdl.handle.net/10216/157157
• topic: Ciências biológicas; Biological sciences

In 2020, over 500 000 cases of Bladder Cancer (BC) were diagnosed, which resulted in around 200 000 deaths directly related to this malignancy. The majority of cases (around 80%) are diagnosed in the non-muscle invasive (NMIBC) stage. Bacillus Calmette-Guérin (BCG) is often used as an adjuvant immunotherapy in early high risk NMIBC together with the resection of the tumour and has been shown to significantly improve recurrence-free survival. It is described that this bug induces an epigenetic reprogramming of innate immune cells, such as monocytes, triggering a memory-like enhanced immune phenotype named "Trained Immunity" (TI). This process translates into higher pro-inflammatory cytokine production, improved anti-tumoral response and T-cell independent protection against other infections. However, the mechanism that facilitates this augmented immune response in BC is not fully understood, and not all patients have a positive response. Glycans are macromolecular sugar structures added by enzymes to lipids or proteins, and they cover the cell membrane of all cells, forming the glycocalyx. This carbohydrate sheet plays a major role in several cellular processes in homeostasis, and in pathological settings, being involved in tumour immunoediting and progression. Previous work from our group demonstrated that aberrant expression of complex branched N-glycans is linked to tumour evasion in colorectal cancer, and the removal of these structures lead to a reinvigorated immune response. BCG has relevant glycan structures on its surface, namely lipomannans, which can be sensed by innate cells carrying Pattern-Recognizing Receptors (PRRs). With all of this in mind, in this thesis, we aimed to understand if the potency of pathogen-derived glycans as triggers of a more pro-inflammatory "trained" phenotype on monocytes, increasing the capacity of these cells to sense and kill tumour cells. In silico analysis shows that monocytes previously exposed to certain stimuli with pro-inflammatory priming capabilities present an increased expression of glycan binding receptors. As a proof of concept, we isolated monocytes from healthy donors and exposed them to different glycan structures. We observed an increased expression of certain PRRs. Furthermore, we analysed pro-inflammatory cytokine production and performed co-cultures with glycan trained monocytes and BC cell lines and evaluated their tumour killing capability. Then, we complemented our analysis by analysing monocytes from NMIBC patients' blood samples.