Mack, V. | bioRxiv Science

bioRxiv2025

Sterile- or pathogen-induced endolysosomal damage activate the NLRP6 inflammasome in human intestinal epithelial cells

NLRP6 controls host defense against bacteria and viruses in the gastrointestinal tract by a poorly understood mechanism. Here, we report that NLRP6 forms an inflammasome upon endolysosomal damage caused by sterile triggers or bacterial pathogens such as Listeria monocytogenes in human intestinal epithelial cells (IECs). NLRP6 activation required Listeriolysin O-dependent cytosolic invasion of L. monocytogenes and drove IEC pyroptosis via ASC/Caspase-1-mediated GSDMD cleavage. NLRP6 inflammasome formation was independent of bacterial PAMPs, such as lipoteichoic acid or dsRNA, which were previously reported to activate NLRP6. L. monocytogenes mutants deficient in cell-to-cell spread or escape from secondary vacuoles induced less cell death, linking bacteria-induced endolysosomal damage to NLRP6 activation. Finally, sterile endolysosomal damage recapitulated pathogen-induced NLRP6 activation and drove IEC pyroptosis. In summary, our study reveals that NLRP6 allows IECs to detect endolysosomal damage, thereby not only making it responsive to pathogens but more generally to wide-ranging sources of pathological endolysosomal damage.

immunology↗

bioRxiv2020

Activation of group II metabotropic receptors attenuates cortical E-I imbalance in a 15q13.3 microdeletion mouse model

Animal models reflecting human risk for schizophrenia are essential research tools for gaining further insight into the convergence of CNS pathology and clinical biomarkers. Amongst the variety of animal models that display schizophrenia-related neuronal network deficits, transgenic mice for rare and highly penetrant copy number variants (CNVs) provide a unique opportunity to study pathological correlates in models with strong construct validity. The Df(h15q13)/+ mouse model of the human 15q13.3 microdeletion CNV has been shown to mimic deficits in parvalbumin positive (PV+) interneuron and cortical network function. However, the corresponding changes in synapse density and activity within the medial prefrontal cortex (mPFC) have not been described. Using high-content immunofluorescence imaging, we have shown a reduced density of PV+ neurons and inhibitory synapses in the mPFC of Df(h15q13)/+ mice. We found that the reduced detection of PV+ synapses were accompanied by changes in spontaneous inhibitory and excitatory synaptic activity onto layer 2/3 pyramidal neurons. The aberrant cortical function was also evident in awake animals by a reduced high frequency auditory steady-state responses (ASSR), reliably monitored by EEG. Importantly, the imbalance of excitatory to inhibitory function could be attenuated on a cellular and cortical network level by activation of mGlu2/3 receptors, indicating the relevance of excessive excitatory transmission to the cortical network deficit in the Df(15q13)/+ mouse model. Our findings highlight the preclinical value of genetic risk and in particular CNV models such as the Df(15q13)/+ mice to investigate pathological network correlates of schizophrenia risk and to probe therapeutic opportunities based on clinically relevant biomarkers.

neuroscience↗