Biology subjects

Mackie, G. M.

Publications and source records attributed to Mackie, G. M..

3 recordsLinked to original sources

bioRxiv2023

Salmonella cancer therapy metabolically disrupts tumours at the collateral cost of T cell immunity

Bacterial cancer therapy (BCT) is a promising therapeutic for solid tumours. Salmonella enterica Typhimurium (STm) is well-studied amongst bacterial vectors due to advantages in genetic modification and metabolic adaptation. A longstanding paradox is the redundancy of T cells for treatment efficacy; instead, STm BCT depends on innate phagocytes for tumour control. Here, we used distal T cell receptor (TCR) reporter mice (Nr4a3-Tocky-Ifng-YFP) and a colorectal cancer (CRC) model to interrogate T cell activity during BCT with attenuated STm. We found that colonic TILs exhibited a variety of activation defects, including IFN-{gamma} production decoupled from TCR signalling, decreased polyfunctionality and reduced TCM formation. Modelling of T-cell-tumour interactions with a tumour organoid platform revealed an intact TCR signalosome, but paralysed metabolic reprogramming due to inhibition of the master metabolic controller, c-Myc. Restoration of c-Myc by deletion of the bacterial asparaginase ansB reinvigorated T cell activation, but at the cost of decreased metabolic control of the tumour by STm. This work shows for the first time that T cells are metabolically defective during BCT, but also that this same phenomenon is inexorably tied to intrinsic tumour suppression by the bacterial vector.

immunology↗

bioRxiv2021

LRR protein RNH1 inhibits inflammasome activation through proteasome-mediated degradation of Caspase-1 and is associated with adverse clinical outcomes in COVID-19 patients.

Inflammasomes are cytosolic innate immune sensors of pathogen infection and cellular damage that induce caspase-1 mediated inflammation upon activation. Although inflammation is protective, uncontrolled excessive inflammation can cause inflammatory diseases and can be detrimental, such as in COVID-19. However, the underlying mechanisms that control inflammasome activation are incompletely understood. Here we report that the leucine rich repeat (LRR) protein Ribonuclease inhibitor (RNH1), which shares homology with LRRs of NLRP proteins, attenuates inflammasome activation. Deletion of RNH1 in macrophages increases IL-1{beta} production and caspase-1 activation for inflammasome stimuli. Mechanistically, RNH1 decreases pro-IL-1{beta} expression and induces proteasome-mediated caspase-1 degradation. Corroborating this, mouse models of monosodium urate (MSU)-induced peritonitis and LPS-induced endotoxemia, which are dependent on caspase-1, respectively show increased neutrophil infiltration and lethality in Rnh1-/- mice compared to WT mice. Furthermore, RNH1 protein levels are negatively correlated with inflammation and disease severity in hospitalized COVID-19 patients. We propose that RNH1 is a new inflammasome regulator with relevance to COVID-19 severity.

immunology↗

bioRxiv2019

Attenuated Salmonella typhimurium cancer therapy has direct effects on the tumor epithelium in colorectal cancer

Bacterial cancer therapy (BCT) shows great promise for treatment of solid tumors, yet basic mechanisms of bacterial-induced tumor suppression remain undefined. The intestinal epithelium is the natural route of infection for Salmonella and thus harbors innate immune defenses which protect against infection. Attenuated strains of Salmonella enterica serovar Typhimurium (STm) have commonly been used in mouse models of BCT, largely with the use of xenograft and orthotopic transplant cancer models. We aimed to better understand the tumor epithelium-targeted mechanisms of BCT by using mouse models of intestinal tumorigenesis and tumor organoid cultures to assess the effectiveness and mechanisms of treatment with aromatase A-deficient STm (STm{Delta}aroA). STm{Delta}aroA delivered by oral gavage could significantly reduce tumor burden and tumor load in both a colitis-associated colon cancer model (CAC) and in a spontaneous intestinal cancer model, Apcmin/+ mice. STm{Delta}aroA colonization of tumors caused alterations in transcription of mRNAs associated with epithelial-mesenchymal transition as well as metabolic and cell cycle-related transcripts. Metabolomic analysis of tumors demonstrated alteration in the metabolic environment of STm{Delta}aroA-treated tumors, suggesting STm{Delta}aroA imposes metabolic competition on the tumor. Use of tumor organoid cultures in vitro demonstrated that STm{Delta}aroA can directly affect the tumor epithelium with alterations in transcripts and metabolites similar to in vivo-treated tumors. Thereby, we demonstrate that bacterial cancer therapy is efficacious in autochthonous intestinal cancer models, that BCT imposes metabolic competition, and that BCT has direct effects on the tumor epithelium, which have not previously been appreciated.\n\nOne Sentence SummaryAttenuated Salmonella enterica serovar Typhimurium can home to gastrointestinal tumors and directly affect the tumor epithelium, inducing transcriptional and metabolic changes that lead to reduced tumor burden in mice.

cancer biology↗