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Biology subjects

O'Sullivan, M. P.

Publications and source records attributed to O'Sullivan, M. P..

3 recordsLinked to original sources

HIV inhibits Warburg metabolism in human macrophages infected with Mycobacterium tuberculosis.

Tuberculosis (TB)-associated mortality remains disproportionately high among people living with HIV (PLWH), with macrophage dysfunction representing a key mechanism of impaired host defence against Mycobacterium tuberculosis (Mtb) infection. Using the U1 chronically HIV-infected macrophage cell line model coupled with primary human monocyte-derived macrophages (MDMs) exposed to HIV-1 gp120, we systematically characterized immunometabolic perturbations during Mtb infection. Nanostring RNA analysis revealed that Mtb monoinfection upregulated glycolytic genes while suppressing oxidative phosphorylation (OXPHOS) transcripts, consistent with a Warburg-type metabolic shift. Conversely, HIV infection downregulated glycolytic enzymes and enhanced mitochondrial respiratory chain components. Coinfection studies demonstrated HIV-mediated suppression of Mtb-induced glycolytic reprogramming. Extracellular flux analysis demonstrated that gp120 exposure increased basal oxygen consumption rate while impairing spare respiratory capacity in Mtb-infected MDMs, effectively blocking the Warburg metabolic transition. Notably, gp120 concentrations equivalent to those observed in antiretroviral therapy (ART)-treated PLWH significantly disrupted metabolic plasticity and high-dose gp120 attenuated Mtb-induced TNF- secretion. ImportanceThis study provides mechanistic insight into HIV-associated susceptibility to TB by demonstrating that HIV-1 infection fundamentally alters macrophage immunometabolic responses to Mtb. We establish that HIV-1, through gp120-mediated signaling, subverts the critical glycolytic induction required for effective antimicrobial responses against Mtb. The persistence of this metabolic dysregulation at clinically relevant gp120 concentrations, comparable to those observed in virologically suppressed PLWH, suggests ongoing immunological vulnerability despite ART. These findings identify HIV-induced metabolic reprogramming as a potential contributor to the persistently elevated TB risk in ART-treated individuals and highlight macrophage immunometabolism as a promising therapeutic target for host-directed therapies in HIV/TB coinfection. The dissociation between metabolic and cytokine responses suggests complex, multifactorial mechanisms underlying HIV-associated impairment of anti-mycobacterial immunity, warranting further investigation into the molecular pathways connecting cellular metabolism and immune effector functions.

immunology↗

Altered infective competence of the human gut microbiome in COVID-19

ObjectivesInfections with SARS-CoV-2 have a pronounced impact on the gastrointestinal tract and its resident microbiome. Clear differences between severe cases of infection and healthy individuals have been reported, including the loss of commensal taxa. We aimed to understand if microbiome alterations including functional shifts are unique to severe cases or a common effect of COVID-19. DesignWe used high-resolution systematic multi-omic analyses to profile the gut microbiome in asymptomatic-to-moderate COVID-19 individuals compared to a control group. ResultsWe found a striking increase in the overall abundance and expression of both virulence factors and antimicrobial resistance genes in COVID-19. Importantly, these genes are encoded and expressed by commensal taxa from families such as Acidaminococcaceae and Erysipelatoclostridiaceae, which we found to be enriched in COVID-19 positive individuals. We also found an enrichment in the expression of a betaherpesvirus and rotavirus C genes in COVID-19 positive individuals compared to healthy controls. ConclusionOur analyses identified an altered and increased infective competence of the gut microbiome in COVID-19 patients.

microbiology↗

Phenolic glycolipid facilitates mycobacterial escape from a microbicidal population of tissue-resident macrophages

Mycobacterium tuberculosis enters the host in aerosol droplets deposited in lung alveoli where the bacteria first encounter lung-resident alveolar macrophages. We studied the earliest mycobacterium-macrophage interactions in the optically transparent zebrafish. We find that the first-responding resident macrophages can phagocytose and eradicate infecting mycobacteria. So, to establish a successful infection, mycobacteria must escape out of the initial resident macrophage into growth-permissive monocytes. We define a critical role for the membrane phenolic glycolipid (PGL) in engineering this transition to a permissive niche. PGL activates the STING cytosolic sensing pathway, thereby inducing the chemokine CCL2 that recruits permissive peripheral monocytes. The bacteria then transfer from resident macrophage to recruited monocyte via transient fusion of the two immune cells. We show that interrupting this bacterial strategy so as to prolong the mycobacterial sojourn in resident macrophages promotes clearing of infection. Because PGL-dependent CCL2 induction is conserved in human alveolar macrophages, our findings suggest the potential of immunological or pharmacological PGL-blocking interventions to prevent tuberculosis.

immunology↗