Biology subjects

Ilango, G.

Publications and source records attributed to Ilango, G..

4 recordsLinked to original sources

bioRxiv2026

Hijacking of inflammasome responses by the complement system during Pseudomonas aeruginosa-Aspergillus fumigatus sur-infection

Patients with cystic fibrosis (pwCF) are highly susceptible to chronic pulmonary infections due to mutations in the CFTR gene. From early childhood, pwCF experience repeated lung infections and often develop chronic bacterial and/or fungal colonization. Among the most clinically relevant pathogens, Pseudomonas aeruginosa and Aspergillus fumigatus frequently co-infect and are associated with worse outcomes, including excessive IL-1{beta}-driven inflammation and accelerated lung function decline. Here we investigated the mechanisms underlying inflammasome overactivation during super-infection. We found that inflammasome hyperactivation occurred across macrophage populations, was independent of exogenous priming, and required live co-infection with both pathogens. P. aeruginosa and A. fumigatus cooperatively activated the NLRP3 inflammasome, and this response required both caspase-1 and caspase-8. Unexpectedly, gasdermin D was dispensable for IL-1{beta} release. Bacterial flagellin, type IV pili and the type III secretion system, as well as the fungal polysaccharide galactosaminogalactan (GAG), were each required for overactivation. Mechanistically, P. aeruginosa activated the MyD88-TLR pathway, enhancing macrophage responses and promoting ITGAM (CD11b) expression. Under fungal super-infection, macrophages secreted complement component C3, which may bound fungal surface and engaged the complement receptor C3R (CD11b/CD18). Downstream SYK and ERK signaling amplified inflammasome activation and IL-1{beta} release. Single-cell transcriptomic analysis of pwCF broncho-alveolar lavage and lung samples supported coordinated upregulation of complement and inflammasome pathways during bacterial-fungal infection. Together, these findings identify a complement-inflammasome signaling axis that drives pathological inflammation during bacterial-fungal co-infection in airways of pwCF and may represent a therapeutic target.

immunology↗

bioRxiv2025

MAIT cells protect in severe pneumococcal pneumonia by regulating neutrophil/macrophage antimicrobial activities

Mucosal-Associated Invariant T (MAIT) cells populate the lung tissue where they contribute to defense against respiratory infections. While MAIT cells have been implicated in host resistance to infections caused by Gram-negative bacteria, their contribution in immunity against Gram-positive bacteria-driven pneumonia is still enigmatic. Here, we demonstrate that both mouse and human MAIT cells are activated during severe infection caused by Streptococcus pneumoniae, the major cause of community-acquired bacterial pneumonia. Upon infection, lung MAIT cells undergo a transcriptional reprogramming associated with acquisition of potent antimicrobial properties. MAIT cell-deficient mice are more susceptible to pneumococcal pneumonia, including higher mortality, uncontrolled bacterial growth and dissemination, and impaired neutrophil and interstitial macrophage activity. Moreover, prophylactic stimulation of MAIT cells using cognate antigen protects from pneumococcus-induced lethal pneumonia. These findings demonstrate that MAIT cells are key cellular actors during Gram-positive bacterial infections.

immunology↗

bioRxiv2024

Bona fide cytotoxic iNKT cells with superior antitumour responses identified in mice and humans

Adoptive cell therapies (ACT) using unmodified or engineered invariant Natural Killer T (iNKT) cells are in clinical trials for cancer treatment. While promising, outcomes are still suboptimal, possibly due to iNKT cell heterogeneity. This study identified unique iNKT cell populations with strong cytotoxic activity in mice and humans. In mice, iNKT1c cells showed potent CD1d-dependent and -independent antitumor functions, with responses influenced by NK receptors. IL-15 enhances their cytolytic activity, while retinoic acid is essential for their generation. In humans, terminally differentiated CD57+ iNKT cells showed marked NK-receptor expression and most effectively killed C1R tumor cells in vitro. These cells appeared activated/exhausted within tumors of non-small cell lung cancer patients. Additionally, a central memory-like CD62L+ CD4- iNKT subset efficiently expanded and generated cytotoxic CD57+ iNKT cells in vitro, making them an appealing candidate for ACT. This study paves the way for the design of more effective iNKT cell-based immunotherapies.

immunology↗

bioRxiv2023

IFN-γ primes bone marrow neutrophils to acquire regulatory functions in severe viral respiratory infections

Neutrophil subsets endowed with regulatory/suppressive properties are widely regarded as deleterious immune cells that can jeopardize antitumoral response and/or antimicrobial resistance. Here, we describe a sizeable fraction of neutrophils characterized by the expression of Programmed death-ligand 1 (PD-L1) in biological fluids of humans and mice with severe viral respiratory infections (VRI). Biological and transcriptomic approaches indicated that VRI-driven PD-L1+ neutrophils are endowed with potent regulatory functions and reduced classical antimicrobial properties, as compared to their PD-L1- counterpart. VRI-induced regulatory PD-L1+ neutrophils were generated in the bone marrow in an IFN-{gamma}-dependent manner and were quickly mobilized into the inflamed lungs where they fulfilled their maturation. Neutrophil depletion and PD-L1 blockade during experimental VRI resulted in higher mortality, increased local inflammation and reduced expression of resolving factors. These findings suggest that PD-L1+ neutrophils are important players in disease tolerance by mitigating local inflammation during severe VRI and that they may constitute relevant targets for future immune interventions.

immunology↗