SUMMARY Either caspase-1 or caspase-11 can cleave gasdermin D to cause pyroptosis, eliminating intracellular replication niches. We previously showed that macrophages detect Burkholderia thailandensis via NLRC4, triggering the release of interleukin (IL)-18 and driving an essential interferon (IFN)-γ response that primes caspase-11. We now identify the IFN-γ-producing cells as a mixture of natural killer (NK) and T cells. Although both caspase-1 and caspase-11 can cleave gasdermin D in macrophages and neutrophils, we find that NLRC4-activated caspase-1 triggers pyroptosis in macrophages, but this pathway does not trigger pyroptosis in neutrophils. In contrast, caspase-11 triggers pyroptosis in both macrophages and neutrophils. This translates to an absolute requirement for caspase-11 in neutrophils during B. thailandensis infection in mice. We present an example of inflammasome sensors causing diverging outcomes in different cell types. Thus, cell fates are dictated not simply by the pathogen or inflammasome, but also by how the cell is wired to respond to detection events.

A series of 2-and 3-OH Nile red dyes was prepared in order to generate water-soluble probes that could be used to probe lipid binding to proteins. Various substitutions in positions 2-/3-, 6-, and 7-shifted wavelengths while maintaining the environmental sensitivity of Nile red. In order to increase the solubility of the dyes in aqueous solutions, we attached butyric acid groups to the 2-or 3-OH position. In addition, phenothiazine dyes, which exhibited particularly long excitation properties, were synthesized and tested for the first time. All dyes showed Stoke's shifts of 70-100 nm and changes in excitation and emission of over 100 nm, depending on the hydrophobicity of the environment. Binding studies with bovine serum albumin and the non-specific lipid transfer protein SCP2 revealed emission changes of more than 30 nm upon binding to the protein and a five-fold increase in emission intensity. Titration of the dye-loaded proteins with various lipids or drugs replaced the dye and thereby reversed the shift in wavelength intensity. This allowed us to estimate the lipid binding affinity of the investigated proteins. For SCP2, isothermal calorimetry (ITC) data verified the titration experiments. NMR titration experiments of SCP2 with Nile red 2-O-butyric acid (1a) revealed that the dye is bound within the lipid binding pocket and competes with lipid ligands for this binding site. These results give valuable insight into lipid and drug transport by proteins outside and inside cells.

Summary Shigella flexneri , a cytosol-invasive gram-negative pathogen, deploys an array of type III-secreted effector proteins to evade host cell defenses. Caspase-11 and its human ortholog caspase-4 detect cytosolic lipopolysaccharide (LPS) and trigger gasdermin D-mediated pyroptosis to eliminate intra-cytoplasmic bacterial threats . However, the role of caspase-11 in combating S. flexneri is unclear. The Shigella T3SS effector OspC3 reportedly suppresses cytosolic LPS sensing by inhibiting caspase-4 but not caspase-11 activity. Surprisingly, we found that S. flexneri also uses OspC3 to inhibit murine caspase-11 activity. Mechanistically, we found that OspC3 binds only to primed caspase-11. Importantly, we demonstrate that S. flexneri employs OspC3 to prevent caspase-11-mediated pyroptosis in neutrophils, enabling bacteria to disseminate and evade clearance following intraperitoneal challenge. In contrast, S. flexneri lacking OspC3 is attenuated in a caspase-11- and gasdermin D-dependent fashion. Overall, our study reveals that OspC3 suppresses cytosolic LPS detection in a broad array of mammals.

The airway epithelium and underlying innate immune cells comprise the first line of host defense in the lung. They recognize pathogen-associated molecular patterns (PAMPs) using membrane-bound receptors, as well as cytosolic receptors such as inflammasomes. Inflammasomes activate inflammatory caspases, which in turn process and release the inflammatory cytokines IL-1β and IL-18. Additionally, inflammasomes trigger a form of lytic cell death termed pyroptosis. One of the most important inflammasomes at the host-pathogen interface is the non-canonical caspase-11 inflammasome that responds to LPS in the cytosol. Caspase-11 is important in defense against Gram-negative pathogens, and can drive inflammatory diseases such as LPS-induced sepsis. However, pathogens can employ evasive strategies to minimize or evade host caspase-11 detection. In this review, we present a comprehensive overview of the function of the non-canonical caspase-11 inflammasome in sensing of cytosolic LPS, and its mechanism of action with particular emphasis in the role of caspase-11 in the lung. We also explore some of the strategies pathogens use to evade caspase-11.

Highlights The review analyses the role of CAZymes in lignocellulose degradation with focus on the different approaches for improving the enzyme activity. Omics based approaches for the analysis of genes, transcripts, proteins and metabolites related to plant degrading mechanism. Directed evolution and rational design as approaches for engineering to enhancing the CAZyme properties. Microbial engineering of the fungal and microbial strains by adapting techniques like CRISPR/cas9 and use of various expression systems. Novel enzymes and cocktail formulation for biorefinery-based application for production of value-added products using low cost plant biomass.

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Given the high frequency of avoidable terminal ICU hospitalizations, health care leaders should develop strategies to prospectively identify patients at high risk and formulate interventions to improve end-of-life care.

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