Biology subjects

Sweere, J. M.

Publications and source records attributed to Sweere, J. M..

3 recordsLinked to original sources

bioRxiv2024

Disrupting CD38-driven T cell dysfunction restores sensitivity to cancer immunotherapy

A central problem in cancer immunotherapy with immune checkpoint blockade (ICB) is the development of resistance, which affects 50% of patients with metastatic melanoma1,2. T cell exhaustion, resulting from chronic antigen exposure in the tumour microenvironment, is a major driver of ICB resistance3. Here, we show that CD38, an ecto-enzyme involved in nicotinamide adenine dinucleotide (NAD+) catabolism, is highly expressed in exhausted CD8+ T cells in melanoma and is associated with ICB resistance. Tumour-derived CD38hiCD8+ T cells are dysfunctional, characterised by impaired proliferative capacity, effector function, and dysregulated mitochondrial bioenergetics. Genetic and pharmacological blockade of CD38 in murine and patient-derived organotypic tumour models (MDOTS/PDOTS) enhanced tumour immunity and overcame ICB resistance. Mechanistically, disrupting CD38 activity in T cells restored cellular NAD+ pools, improved mitochondrial function, increased proliferation, augmented effector function, and restored ICB sensitivity. Taken together, these data demonstrate a role for the CD38-NAD+ axis in promoting T cell exhaustion and ICB resistance, and establish the efficacy of CD38 directed therapeutic strategies to overcome ICB resistance using clinically relevant, patient-derived 3D tumour models.

cancer biology↗

bioRxiv2020

Methods for Extraction and Detection of Bacteriophage DNA from the Sputum of Patients with Cystic Fibrosis

There is increasing interest in the pulmonary microbiomes bacterial and viral communities, particularly in the context of chronic airway infections in cystic fibrosis (CF). However, the isolation of microbial DNA from the sputum from patients with CF is technically challenging and the optimal protocols for the analysis of viral species, including bacteriophage, from clinical samples remains challenging. Here, we evaluate a set of methods developed for processing and analyzing sputum from patients with CF with a particular emphasis on detecting bacteriophage viron-derived nucleic acid. We evaluate the impact of bead-beating, deoxyribonuclease digestion, and heating steps in these protocols focusing on the quantitative assessment of Pseudomonas aeruginosa and Pf bacteriophage in sputum as a proof of concept. Based on these comparative data, we describe an optimized protocol for processing sputum from patients with CF and isolating DNA for PCR or sequencing-based studies. These studies will facilitate future assessments of bacteriophage and bacteria in sputum from patients with CF. Author SummaryPatients with cystic fibrosis (CF) have thickened secretions and develop chronic infections in their airways. While we culture bacterial pathogens from expectorated sputum this method favors detection of certain organisms. There is greater understanding that the microbiome with in the airway of patients with cystic fibrosis is varied and contains more than just the bacteria that we selectively culture. Processing sputum is difficult as it is very thick. There are many different ways to process sputum depending on what aspect of the sputum is to be studied. We have an interest in a specific bacteriophage, or a virus that infects bacteria. We sought to find the best method to take sputum from a CF patient and extract DNA so that we could detect both bacteria and bacteriophage DNA. We compared different methods that included different combinations of heat, mechanical homogenization, chemical lysis and DNA extraction by commercially available kits. We describe the method we found easiest to execute and produced the best yield for detection of both bacteria and bacteriophage. Our purpose of publishing this method in detail is to facilitate further study of viral and bacterial communities in the sputum of patients with CF.

microbiology↗

bioRxiv2020

Filamentous Bacteriophage Delay Healing of Pseudomonas-Infected Wounds

We have identified a novel role for filamentous bacteriophage in the delayed healing associated with chronic Pseudomonas aeruginosa (Pa) wound infections. Pf phage delays wound re-epithelialization in the absence of live Pa, indicative that Pf effects on wound healing are independent of Pa pathogenesis. Pf phage directly inhibits autocrine signaling of CXCL1 (KC) to impede keratinocyte migration and wound re-epithelization. In agreement with these studies, a prospective cohort study of 36 human patients with chronic Pa wound infections revealed that wounds infected with Pf positive strains of Pa took longer to heal and were more likely to increase in size compared to wounds infected with Pf negative strains. Together, these data implicate Pf phage in the delayed wound healing associated with Pa infection through direct manipulation of mammalian target cells. We propose that Pf phage may have potential as a biomarker and therapeutic target in delayed wound healing.

microbiology↗