Inflammasomes are a group of protein complexes built around several proteins, including NLRP3, NLRC4, AIM2 and NLRP6. Recognition of a diverse range of microbial, stress and damage signals by inflammasomes results in direct activation of caspase-1, which subsequently induces secretion of potent pro-inflammatory cytokines and a form of cell death called pyroptosis. Inflammasome-mediated processes are important during microbial infections and also in regulating both metabolic processes and mucosal immune responses. We review the functions of the different inflammasome complexes and discuss how aberrations in them are implicated in the pathogenesis of human diseases.

https://www.weizmann.ac.il/immunology/elinav/sites/immunology.elinav/files/2012_elinav_nature_b.pdf

Inflammasomes in health and disease

Mechanism of the binding, insertion and destabilization of phospholipid bilayer membranes by alpha-helical antimicrobial and cell non-selective membrane-lytic peptides.

Cancer immunotherapy attempts to harness the power and specificity of the immune system to treat tumours. The molecular identification of human cancer-specific antigens has allowed the development of antigen-specific immunotherapy. In one approach, autologous antigen-specific T cells are expanded ex vivo and then re-infused into patients. Another approach is through vaccination; that is, the provision of an antigen together with an adjuvant to elicit therapeutic T cells in vivo. Owing to their properties, dendritic cells (DCs) are often called 'nature's adjuvants' and thus have become the natural agents for antigen delivery. After four decades of research, it is now clear that DCs are at the centre of the immune system owing to their ability to control both immune tolerance and immunity. Thus, DCs are an essential target in efforts to generate therapeutic immunity against cancer.

Cancer immunotherapy via dendritic cells

Water-membrane soluble protein and peptide toxins are used in the defense and offense systems of all organisms, including plants and humans. A major group includes antimicrobial peptides, which serve as a nonspecific defense system that complements the highly specific cell-mediated immune response. The increasing resistance of bacteria to conventional antibiotics stimulated the isolation and characterization of many antimicrobial peptides for potential use as new target antibiotics. The finding of thousands of antimicrobial peptides with variable lengths and sequences, all of which are active at similar concentrations, suggests a general mechanism for killing bacteria rather than a specific mechanism that requires preferred active structures. Such a mechanism is in agreement with the “carpet model” that does not require any specific structure or sequence. It seems that when there is an appropriate balance between hydrophobicity and a net positive charge the peptides are active on bacteria. However, selective activity depends also on other parameters, such as the volume of the molecule, its structure, and its oligomeric state in solution and membranes. Further, although many studies support that bacterial membrane damage is a lethal event for bacteria, other studies point to a multihit mechanism in which the peptide binds to several targets in the cytoplasmic region of the bacteria.

Mode of action of membrane active antimicrobial peptides.

The structure

Tryptophan- and arginine-rich antimicrobial peptides: structures and mechanisms of action.

As an approved vaccine adjuvant for use in humans, alum has vast health implications, but, as it is a crystal, questions remain regarding its mechanism. Furthermore, little is known about the target cells, receptors, and signaling pathways engaged by alum. Here we report that, independent of inflammasome and membrane proteins, alum binds dendritic cell (DC) plasma membrane lipids with substantial force. Subsequent lipid sorting activates an abortive phagocytic response that leads to antigen uptake. Such activated DCs, without further association with alum, show high affinity and stable binding with CD4(+) T cells via the adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1). We propose that alum triggers DC responses by altering membrane lipid structures. This study therefore suggests an unexpected mechanism for how this crystalline structure interacts with the immune system and how the DC plasma membrane may behave as a general sensor for solid structures.

Alum interaction with dendritic cell membrane lipids is essential for its adjuvanticity

Differential Scanning Calorimetry (DSC) is a highly sensitive technique to study the thermotropic properties of many different biological macromolecules and extracts. Since its early development, DSC has been applied to the pharmaceutical field with excipient studies and DNA drugs. In recent times, more attention has been applied to lipid-based drug delivery systems and drug interactions with biomimetic membranes. Highly reproducible phase transitions have been used to determine values, such as, the type of binding interaction, purity, stability, and release from a drug delivery mechanism. This review focuses on the use of DSC for biochemical and pharmaceutical applications.

Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions

Differential scanning calorimetry and X-ray diffraction studies of the specificity of the interaction of antimicrobial peptides with membrane-mimetic systems.

Elmar J. Prenner

Papers

Tryptophan- and arginine-rich antimicrobial peptides: structures and mechanisms of action.

Alum interaction with dendritic cell membrane lipids is essential for its adjuvanticity

Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions

Differential scanning calorimetry and X-ray diffraction studies of the specificity of the interaction of antimicrobial peptides with membrane-mimetic systems.

The interaction of the antimicrobial peptide gramicidin S with lipid bilayer model and biological membranes.