Biology subjects

Gil-Marques, M. L.

Publications and source records attributed to Gil-Marques, M. L..

3 recordsLinked to original sources

bioRxiv2026

NLRP11 promotes non-canonical inflammasome activation in human macrophages by enhancing caspase-4 recognition of cytosolic lipopolysaccharide

Innate immune detection of Gram-negative bacteria depends on sensing of cytosolic lipopolysaccharide (cLPS) by the non-canonical inflammasome, mediated in humans by NLRP11 and caspase-4 (CASP4). Activation of this pathway in human macrophages triggers gasdermin-D activation and pyroptotic cell death. Although CASP4 directly binds LPS in vitro, additional host factors are required for efficient activation in vivo. Here, we show that NLRP11, a primate-specific pattern recognition receptor, facilitates CASP4 recognition of cLPS and promotes non-canonical inflammasome activation. NLRP11 functions upstream CASP4, forming an ASC-independent complex that requires a conserved CASP4 p20 residue, binds cLPS, and enhances CASP4-dependent LPS recognition. Mutational analyses demonstrate that in human macrophages, in addition to LPS binding and CASP4 catalytic activity, CASP4 interaction with NLRP11 is essential for efficient pyroptosis. Together, these findings establish NLRP11 as a primate-specific determinant that enhances CASP4-mediated cLPS detection and non-canonical inflammasome activation, revealing a mechanism for human-specific regulation of innate immunity.

immunology↗

bioRxiv2025

Virus-like particle capture reveals coordination of actin remodeling during Shigella flexneri entry by host proteins

Shigella spp. are intracellular bacterial pathogens that enter the host via plasma membrane insertion of a type 3 secretion system (T3SS) translocon, which triggers signaling cascades that include modulation of cytoskeletal dynamics, resulting in bacterial uptake. To better understand translocon insertion-induced host processes, we adapted a method to capture in virus-like particles (VLP) host proteins that are recruited to the cytosolic face of natively delivered S. flexneri translocons. Proteomic analyses reveal enrichment of 14-3-3{zeta}, a signaling protein, and CAP2, a regulator of actin turnover. 14-3-3{zeta} and CAP2 are necessary for host entry by T3SS pathogens. 14-3-3{zeta} dimers function as molecular scaffolds in the formation of bacterial-associated membrane ruffles. Concurrently, CAP2 localizes to membrane ruffles and cooperates with 14-3-3{zeta} to enable the formation of membrane ruffles that function efficiently in bacterial uptake. The findings define a coordinated role for 14-3-3{zeta} and CAP2 in cytoskeletal dynamics during T3SS pathogen infection.

microbiology↗

bioRxiv2024

NLRP11 is required for canonical NLRP3 and non-canonical inflammasome activation during human macrophage infection with mycobacteria

The NLRP11 protein is only expressed in primates and participates in the activation of the canonical NLRP3 and non-canonical NLRP3 inflammasome activation after infection with gram-negative bacteria. Here, we generated a series of defined NLRP11 deletion mutants to further analyze the role of NLRP11 in NLRP3 inflammasome activation. Like the complete NLRP11 deletion mutant (NLRP11-/-), the NLRP11 mutant lacking the NACHT and LRR domains (NLRP11{Delta}N_LRR) showed reduced activation of the canonical NLRP3 inflammasome, whereas a pyrin domain mutant (NLRP11{Delta}PYD) had no effect on NLRP3 activation. The NLRP11-/- and NLRP11{Delta}N_LRR mutants but not the NLRP11{Delta}PYD mutant also displayed reduced activation of caspase-4 during infection with the intracytosolic, gram-negative pathogen Shigella flexneri. We found that the human adapted, acid-fast pathogen Mycobacterium tuberculosis and the opportunistic pathogen M. kansasii both activate the non-canonical NLRP11 inflammasome in a caspase-4/5-dependent pathway. In conclusion, we show that NLRP11 functions in the non-canonical caspase-4/5 inflammasome activation pathway and the canonical NRLP3 inflammasome pathway, and that NLRP11 is required for full recognition of mycobacteria by each of these pathways. Our work extends the spectrum of bacterial pathogen recognition by the non-canonical NLRP11-caspase4/5 pathway beyond gram-negative bacteria. IMPORTANCEThe activation of inflammasome complexes plays a crucial role in intracellular pathogen detection. NLRP11 and caspase-4 are essential for recognizing lipopolysaccharide (LPS), a molecule found in gram-negative bacteria such as the human pathogens Shigella spp., which activate both canonical NLRP3 and non-canonical inflammasome pathways. Through a series of deletion mutants, we demonstrate that the NACHT and LRR domains of NLRP11, but not its pyrin domain, are critical for detection of S. flexneri. Notably, our research reveals that the acid-fast bacterium M. tuberculosis is also detected by NLRP11 and caspase-4, despite not producing LPS. These findings significantly expand the range of pathogens recognized by NLRP11 and caspase-4 to now include acid - fast bacteria that do not contain LPS and underscore the versatility of these innate immune components in pathogen detection.

immunology↗