bims-ainimu 2025-11-23 papers

Issue of 2025–11–23
four papers selected by
Pedro Escoll Guerrero, Institut Pasteur

Gut Microbes. 2025 Dec 31. 17(1): 2580708

Proteome profiling indicates a link between mitochondrial pathways and the host-microbial sensor ELMO1 following Salmonella infection.

Sajan C Achi, Dominic McGrosso, Stefania Tocci, Isaac Amao, Baibaswata Saha, Stella-Rita Ibeawuchi, Ibrahim M Sayed, David J Gonzalez, Soumita Das.

The host EnguLfment and cell MOtility protein 1 (ELMO1) is a cytosolic microbial sensor that binds bacterial effector proteins, including pathogenic effectors from Salmonella (Salmonella enterica serovar Typhimurium) and controls host innate immune signaling. To understand the ELMO1-regulated host pathways, we have performed liquid chromatography Multinotch MS3-Tandem Mass Tag (TMT) multiplexed proteomics to determine the global quantification of proteins regulated by ELMO1 in macrophages during Salmonella infection. Comparative proteome analysis of control and ELMO1-depleted murine J774 macrophages after Salmonella infection quantified more than 7000 proteins with a notable enrichment in mitochondrial-related proteins. Gene ontology enrichment analysis revealed 19 upregulated and 11 downregulated proteins exclusive to ELMO1-depleted cells during infection, belonging to mitochondrial functions, metabolism, vesicle transport, and the immune system. Seahorse analysis showed that Salmonella infection alters mitochondrial metabolism from oxidative phosphorylation to glycolysis-a shift significantly influenced by the depletion of ELMO1. Furthermore, ELMO1 depletion decreased the ATP rate index following Salmonella infection, indicating its importance in counteracting the effects of Salmonella on immunometabolism. Among the proteins involved in mitochondrial pathways, the mitochondrial fission protein DRP1 was significantly upregulated in ELMO1-depleted cells and ELMO1-KO mice intestine following Salmonella infection. Pharmacological inhibition of DRP1 identified the role of ELMO1-DRP1 pathway in the regulation of pro-inflammatory cytokine TNF-α following infection. The role of ELMO1 has been further characterized by a Proteome profiling of ELMO1-depleted macrophage infected with SifA mutant displayed the involvement of ELMO1-SifA in mitochondrial function, metabolism and host immune/defense responses. Collectively, these findings reveal a novel role for ELMO1 in modulating mitochondrial functions, potentially pivotal in modulating inflammatory responses.

Keywords: DRP1; ELMO1; Microbial sensor; SifA; bacterial effector; macrophages; mitochondrial dynamics; mitochondrial fission; proteomics

DOI: https://doi.org/10.1080/19490976.2025.2580708

Metabolomics. 2025 Nov 15. 21(6): 173

Mycobacterium tuberculosis curli pili (MTP) facilitates pathogenicity by modulating oxidative phosphorylation and carbon flux during early infection of A549 epithelial cells.

Tarien J Naidoo, Shinese Ashokcoomar, Barry Truebody, Jared S Mackenzie, Bridgette M Cumming, Adrie J C Steyn, Manormoney Pillay.

BACKGROUND: The Mycobacterium tuberculosis (Mtb) curli pili (MTP) adhesin has been reported as a significant target for TB diagnostic and intervention strategies. The precise contribution of MTP in modulating oxidative phosphorylation (OXPHOS) and central carbon metabolism (CCM) within host epithelial cells is currently unknown.
OBJECTIVES: This study aimed to investigate the impact of MTP in whole cell bioenergetics during early stages of infection.
METHODS: Extracellular flux analysis was used to determine the role of MTP in modulating OXPHOS in A549 epithelial cells. 13C-metabolic flux analysis was performed on Mtb mtp proficient/deficient infected A549 epithelial cells to determine whether any specific changes in carbon flux through CCM are induced by the adhesin.
RESULTS: The absence of MTP led to an increase in OXPHOS in infected A549 cells, thereby increasing ATP synthesis. The Δmtp-infected A549 cells displayed a similar metabolic profile to the uninfected A549 cells. 13C-isotopomer metabolomic analysis of infected A549 cells suggested that MTP plays a role in decreasing glycolytic flux, enhancing flux through the pentose phosphate pathway (PPP), and modulating tricarboxylic acid (TCA) cycle intermediates by increasing flux through succinate.
CONCLUSIONS: The decreased basal respiration and flux through glycolysis and PPP of Mtb-infected A549 cells potentially decreased innate immune responses and production of signalling molecules to interact with immunocytes and activate adaptive immune responses. The similar metabolic profile of Δmtp-infected A549 cells and uninfected A549 cells suggests that the absence of the adhesin decreases virulence of Mtb. These findings substantiate MTP as an eminent biomarker for TB diagnostics/intervention strategies, and a novel target for vaccine development.

Keywords: Mycobacterium tuberculosis ; A549 pulmonary epithelial cells; Bioenergetics; LC-MS/MS

DOI: https://doi.org/10.1007/s11306-025-02366-5

Vaccine. 2025 Nov 14. pii: S0264-410X(25)01290-3. [Epub ahead of print]69 127992

Brucella secreted effector BspH stimulates intracellular ion flux and confers anti-Brucella immunity.

Chuanxin Shi, Qifeng Li, Shuli Wang, Ruirui Li, Yanyan Cui, Junfang Hao, Jinliang Zhang, Xiaolu Jia, Hui Zhang, Zhiqiang Li.

The facultative intracellular pathogen Brucella spp. relies on the translocation of secreted effector proteins, such as BspH, to establish and maintain its persistent niche within mammalian and human host cell. Following the cloning, expression, and purification of secreted protein BspH, we assessed its immunocompetence. The recombinant protein (rBspH) was used to stimulate murine RAW 264.7 macrophages, and the production of cytokines along with hydrogen (H+), calcium (Ca2+), and hydrogen peroxide (H2O2) ions was measured. Additionally, the immune responses in mice immunized with rBspH were evaluated by ELISA. The results indicated that stimulation of macrophages with rBspH specifically induced the production of H+ and Ca2+ ions, but not H2O2. Furthermore, it triggered the secretion of both Th1 and Th2-associated cytokines. In immunized mice, rBspH elicited a robust humoral response, characterized by the production of specific IgG and elevated levels of Th1 and Th2 cytokines. Crucially, this immune activation conferred significant protection against a subsequent challenge with B. abortus A19. Collectively, these results establish rBspH as a promising candidate for the development of a subunit vaccine against brucellosis.

Keywords: Brucella; BspH; Ions; Subunit vaccine

DOI: https://doi.org/10.1016/j.vaccine.2025.127992

Commun Med (Lond). 2025 Nov 19. 5(1): 483

Monitoring for early prediction of gram-negative bacteremia using machine learning and hematological data in the emergency department.

Yen-Wei Chiu, Yu-Hsin Chang, Tai-Yi Hsu, Chiung-Tzu Hsiao, Yu-Chang Chang, Hsin-Yu Lai, Hsiu-Hsien Lin, Chien-Chih Chen, Lin-Chen Hsu, Shih-Yun Wu, Hong-Mo Shih, Po-Ren Hsueh, Der-Yang Cho.

BACKGROUND: This study aims to develop an artificial intelligence-assisted tool for the prediction of Gram-negative bacteremia, using cell population data, complete blood count, and differential count. The model seeks to distinguish among nonbacteremia, Gram-negative bacteremia, and Gram-positive bacteremia in patients presenting to the emergency department.
METHODS: This retrospective study was conducted in the emergency departments of three hospitals in Taiwan. Data from adults with suspected bacterial infections were collected, including complete blood count, white blood cell differential count, and cell population data. A gradient boosting model (Catboost) was developed to classify nonbacteremia, Gram-negative and Gram-positive bacteremia. We evaluated the model through discrimination and calibration.
RESULTS: Here, we show an analysis of 28,503 cases from the China Medical University Hospital developing cohort, including 795 cases of Gram-positive and 2174 cases of Gram-negative bacteremia. Validation cohorts comprise 15,801 cases from China Medical University Hospital, 2632 from Wei-Gong Memorial Hospital, and 3811 from An-Nan Hospital. For Gram-negative bacteremia, the area under the receiver operating characteristic curve ranges from 0.861 to 0.869, with values for the area under the precision-recall curve ranging from 0.325 to 0.415. Predictions for Gram-positive bacteremia are less accurate, with areas under the curve ranging from 0.759 to 0.798 and values between 0.079 and 0.093 for the precision-recall curve.
CONCLUSIONS: This study shows that machine learning using hematological parameters provides robust early detection of Gram-negative bacteremia in emergency department settings. Cell population data are valuable predictors by reflecting host immune responses. Data imbalance and marked blood cell changes in Gram-negative bacteria may hinder recognition of Gram-positive bacteremia. Future research should explore the real-world impact of deploying the model in clinical settings.

DOI: https://doi.org/10.1038/s43856-025-01200-2