Labile crosslinked hyaluronic acid via urethane formation using bis(β- isocyanatoethyl) disulphide with tuneable physicochemical and immunomodulatory properties

Here, we synthesise a new isocyanate-based crosslinker with the aim of obtaining novel tailored gels. The newly crosslinked hyaluronic acid (HA) gels were analysed in terms of rheological properties, chemical structure, swelling, biocompatibility and immunological response. Results show that the synthesised di-isocyanate outperforms other more conventional di-isocyanates due to its alkyl-based which has been shown to be slower to degrade by hydrolysis than aryl isocyanates. The alkyl-based isocyanate reacts readily with hydroxyl groups on the HA to form stable carbamate crosslinkages. Importantly and uniquely, a centrally located disulphide bond allows versatility with respect to reversible crosslinking and this allows potentially controlled layer-by-layer deposition of the HA for tailored pharmaceutical applications

Targeting immune cell metabolism in the treatment of inflammatory bowel disease

The cells of the immune system are highly dynamic, constantly sensing and adapting to changes in their surroundings. Complex metabolic path-ways govern leukocytes’ ability to fine-tune their responses to external threats. Mammalian target of rapamycin complex 1 and hypoxia inducible factor are important hubs of these pathways and play a critical role coordinating cell activation and proliferation and cytokine production. For this reason, these molecules are attractive therapeutic targets in inflammatory disease. Insight into perturbations in immune cell metabolic path-ways and their impact on inflammatory bowel disease (IBD) progression are starting to emerge. However, it remains to be determined whether the aberrations in immune metabolism that occur in gut resident immune cells contribute to disease pathogenesis or are reflected in the peripheral blood of patients with IBD. In this review, we explore what is known about the metabolic profile of T cells, monocytes, macrophages, dendritic cells, and natural killer cells in IBD and discuss the potential of manipulating immune cell metabolism as a novel approach to treating IBD

Dysregulation of metabolic pathways in circulating natural killer cells isolated from inflammatory bowel disease patients

Background and Aims: Inflammatory bowel diseases [IBD], comprising Crohn’s disease [CD] and ulcerative colitis [UC], are chronic conditions characterized by severe dysregulation of innate and adaptive immunity resulting in the destruction of the intestinal mucosa. Natural killer [NK] cells play a pivotal role in the dynamic interaction between the innate and adaptive immune response. There is an increasing appreciation for the key role immunometabolism plays in the regulation of NK cell function, yet little remains known about the metabolic profile, cytokine secretion, and killing capacity of human NK cells during active IBD. Methods: Peripheral blood mononuclear cells were isolated from peripheral blood of patients with moderate to severely active IBD and healthy controls. NK cells were stained with a combination of cell surface receptors, intracellular cytokines, and proteins and analyzed by flow cytometry. For measurements of NK cell cytotoxicity, the calcein-AM release assay was performed. The metabolic profile was analyzed by an extracellular flux analyzer. Results: NK cells from IBD patients produce large quantities of pro-inflammatory cytokines, IL-17A and TNF-α ex vivo, but have limited killing capability. Furthermore, patient NK cells have reduced mitochondrial mass and oxidative phosphorylation. mTORC1, an important cell and metabolic regulator, demonstrated limited activity in both freshly isolated cells and cytokine-stimulated cells. Conclusions: Our results demonstrate that circulating NK cells of IBD patients have an unbalanced metabolic profile, with faulty mitochondria and reduced capacity to kill. These aberrations in NK cell metabolism may contribute to defective killing and thus the secondary infections and increased risk of cancer observed in IBD patients

Review article: vaccination for patients with inflammatory bowel disease during the COVID-19 pandemic

Background: Poor immune responses are frequently observed in patients with inflammatory bowel disease (IBD) receiving established vaccines; risk factors include immunosuppressants and active disease. Aims: To summarise available information regarding immune responses achieved in patients with IBD receiving established vaccines. Using this information, to identify risk factors in the IBD population related to poor vaccine-induced immunity that may be applicable to vaccines against COVID-19. Methods: We undertook a literature review on immunity to currently recommended vaccines for patients with IBD and to COVID-19 vaccines and summarised the relevant literature. Results: Patients with IBD have reduced immune responses following vaccination compared to the general population. Factors including the use of immunomodulators and anti-TNF agents reduce response rates. Patients with IBD should be vaccinated against COVID-19 at the earliest opportunity as recommended by International Advisory Committees, and vaccination should not be deferred because a patient is receiving immune-modifying therapies. Antibody titres to COVID-19 vaccines appear to be reduced in patients receiving anti-TNF therapy, especially in combination with immunomodulators after one vaccination. Therefore, we should optimise any established risk factors that could impact response to vaccination in patients with IBD before vaccination. Conclusions: Ideally, patients with IBD should be vaccinated at the earliest opportunity against COVID-19. Patients should be in remission and, if possible, have their corticosteroid dose minimised before vaccination. Further research is required to determine the impact of different biologics on vaccine response to COVID-19 and the potential for booster vaccines or heterologous prime-boost vaccinations in the IBD populatio

Personalised mapping of tumour development in synchronous colorectal cancer patients

Synchronous colorectal cancers (syCRCs) are two or more primary tumours identified simultaneously in a patient. Previous studies report high inter-tumour heterogeneity between syCRCs, suggesting independent origin and different treatment response, making their management particularly challenging, with no specific guidelines currently in place. Here, we performed in-depth bioinformatic analyses of genomic and transcriptomic data of a total of eleven syCRCs and one metachronous CRC collected from three patients. We found mixed microsatellite status between and within patients. Overlap of mutations between synchronous tumours was consistently low (<0.5%) and heterogeneity of driver events across syCRCs was high in all patients. Microbial analysis revealed the presence of Fusobacterium nucleatum species in patients with MSI tumours, while quantification of tumour immune infiltration showed varying immune responses between syCRCs. Our results suggest high heterogeneity of syCRCs within patients but find clinically actionable biomarkers that help predict responses to currently available targeted therapies. Our study highlights the importance of personalised genome and transcriptome sequencing of all synchronous lesions to aid therapy decision and improve management of syCRC patients

Characterising the prognostic potential of HLA‑DR during colorectal cancer development

HLA-DR, an MHC class II molecule that mediates antigen presentation, is a favourable prognostic indicator in colorectal cancer (CRC). However, the dynamics and location of HLA-DR expression during CRC development are unclear. We aimed to define HLA-DR expression by immunohistochemistry in colorectal epithelium and stromal tissue at different stages of cancer development, assessing non-neoplastic colorectal adenocarcinoma–adjacent tissue, adenomas and carcinoma tissues, and to associate HLA-DR levels with clinical outcomes. Patients with higher than median HLA-DR expression survived at least twice as long as patients with lower expression. This association was significant for HLA-DR staining in the colorectal carcinoma epithelium (n = 152, p = 0.011, HR 1.9, 95% CI 1.15–3.15) and adjacent non-neoplastic epithelium (n = 152, p < 0.001, HR 2.7, 95% CI 1.59–4.66), but not stroma. In stage II cases, however, the prognostic value of HLA-DR expression was significant only in adjacent non-neoplastic tissues, for both epithelium (n = 63, p = 0.015, HR 3.6, 95% CI 1.279–10.25) and stroma (n = 63, p = 0.018, HR 5.07, 95% CI 1.32–19.49). HLA-DR was lower in carcinoma tissue compared to matched adenomas (n = 35), in epithelium (p < 0.01) and stroma (p < 0.001). HLA-DR was further reduced in late-stage carcinoma (n = 101) compared to early stage (n = 105), in epithelium (p < 0.001) and stroma (p < 0.01). HLA-DR expression was lower (p < 0.05) in the adjacent non-neoplastic epithelium of patients with cancer recurrence. We demonstrate a progressive loss of HLA-DR in epithelial and stromal tissue compartments during CRC development and show prognostic ability in carcinoma–adjacent non-neoplastic tissues, highlighting the importance of this molecule in the anti-cancer immune response. These findings may have wider implications for immunotherapeutic interventions

Role of myeloid regulatory cells (MRCs) in maintaining tissue homeostasis and promoting tolerance in autoimmunity, inflammatory disease and transplantation

Myeloid cells play a pivotal role in regulating innate and adaptive immune responses. In inflammation, autoimmunity, and after transplantation, myeloid cells have contrasting roles: on the one hand they initiate the immune response, promoting activation and expansion of effector T-cells, and on the other, they counter-regulate inflammation, maintain tissue homeostasis, and promote tolerance. The latter activities are mediated by several myeloid cells including polymorphonuclear neutrophils, macrophages, myeloid-derived suppressor cells, and dendritic cells. Since these cells have been associated with immune suppression and tolerance, they will be further referred to as myeloid regulatory cells (MRCs). In recent years, MRCs have emerged as a therapeutic target or have been regarded as a potential cellular therapeutic product for tolerance induction. However, several open questions must be addressed to enable the therapeutic application of MRCs including: how do they function at the site of inflammation, how to best target these cells to modulate their activities, and how to isolate or to generate pure populations for adoptive cell therapies. In this review, we will give an overview of the current knowledge on MRCs in inflammation, autoimmunity, and transplantation. We will discuss current strategies to target MRCs and to exploit their tolerogenic potential as a cell-based therapy

The Trypanosoma brucei-derived ketoacids, indole pyruvate and hydroxyphenylpyruvate, induce HO-1 expression and suppress inflammatory responses in human dendritic cells

The extracellular parasite and causative agent of African sleeping sickness Trypanosoma brucei (T. brucei) has evolved a number of strategies to avoid immune detection in the host. One recently described mechanism involves the conversion of host-derived amino acids to aromatic ketoacids, which are detected at relatively high concentrations in the bloodstream of infected individuals. These ketoacids have been shown to directly suppress inflammatory responses in murine immune cells, as well as acting as potent inducers of the stress response enzyme, heme oxygenase 1 (HO-1), which has proven anti-inflammatory properties. The aim of this study was to investigate the immunomodulatory properties of the T. brucei-derived ketoacids in primary human immune cells and further examine their potential as a therapy for inflammatory diseases. We report that the T. brucei-derived ketoacids, indole pyruvate (IP) and hydroxyphenylpyruvate (HPP), induce HO-1 expression through Nrf2 activation in human dendritic cells (DC). They also limit DC maturation and suppress the production of pro-inflammatory cytokines, which, in turn, leads to a reduced capacity to differentiate adaptive CD4+ T cells. Furthermore, the ketoacids are capable of modulating DC cellular metabolism and suppressing the inflammatory profile of cells isolated from patients with inflammatory bowel disease. This study therefore not only provides further evidence of the immune-evasion mechanisms employed by T. brucei, but also supports further exploration of this new class of HO-1 inducers as potential therapeutics for the treatment of inflammatory conditions

The tumour microenvironment of the upper and lower gastrointestinal tract differentially influences dendritic cell maturation

Background: Only 10–30% of oesophageal and rectal adenocarcinoma patients treated with neoadjuvant chemoradiotherapy have a complete pathological response. Inflammatory and angiogenic mediators in the tumour microenvironment (TME) may enable evasion of anti-tumour immune responses.Methods: The TME influence on infiltrating dendritic cells (DCs) was modelled by treating immature monocyte-derived DCs with Tumour Conditioned Media (TCM) from distinct gastrointestinal sites, prior to LPS-induced maturation. Results: Cell line conditioned media from gastrointestinal cell lines inhibited LPS-induced DC markers and TNF-α secretion. TCM generated from human tumour biopsies from oesophageal, rectal and colonic adenocarcinoma induced different effects on LPS-induced DC markers - CD54, CD80, HLA-DR, CD86 and CD83 were enhanced by oesophageal cancer; CD80, CD86 and CD83 were enhanced by rectal cancer, whereas CD54, HLA-DR, CD86, CD83 and PD-L1 were inhibited by colonic cancer. Notably, TCM from all GI cancer types inhibited TNF-α secretion. Additionally, TCM from irradiated biopsies inhibited DC markers. Profiling the TCM showed that IL-2 levels positively correlated with maturation marker CD54, while Ang-2 and bFGF levels negatively correlated with CD54. Conclusion: This study identifies that there are differences in DC maturational capacity induced by the TME of distinct gastrointestinal cancers. This could potentially have implications for anti-tumour immunity and response to radiotherapy

SARS-CoV-2 infection in general practice in Ireland: a seroprevalence study

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody testing in community settings may help us better understand the immune response to this virus and, therefore, help guide public health efforts. Aim: To conduct a seroprevalence study of immunoglobulin G (IgG) antibodies in Irish GP clinics. Design & setting: Participants were 172 staff and 799 patients from 15 general practices in the Midwest region of Ireland. Method: This seroprevalence study utilised two manufacturers’ point-of-care (POC) SARS-CoV-2 immunoglobulin M (IgM)—IgG combined antibody tests, which were offered to patients and staff in general practice from 15 June to 10 July 2020. Results: IgG seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%. Previous symptoms suggestive of COVID-19 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence. IgG antibodies were detected in approximately 80% of participants who had a previous PCR-confirmed infection. Average length of time between participants’ positive PCR test and positive IgG antibody test was 83 days. Conclusion: Patients and healthcare staff in general practice in Ireland had relatively high rates of IgG to SARS-CoV-2 compared with the national average between 15 June and 10 July 2020 (1.7%). Four fifths of participants with a history of confirmed COVID-19 disease still had detectable antibodies an average of 12 weeks post-infection. While not proof of immunity, SARS-CoV-2 POC testing can be used to estimate IgG seroprevalence in general practice settings