IL-1β is an important inflammatory mediator of type 2 diabetes (T2D). Here we show that oligomers of islet amyloid polypeptide (IAPP), a protein that forms amyloid deposits in the pancreas during T2D, trigger the Nlrp3 inflammasome and generate mature interleukin (IL)-1β. A T2D therapy, glyburide, suppresses IAPP-mediated IL-1β production in vitro. Processing of IL-1β initiated by IAPP first requires priming, a process that involves glucose metabolism and can be facilitated by minimally oxidized low density lipoprotein. Finally, mice transgenic for human IAPP have increased IL-1β in pancreatic islets, which colocalizes with amyloid and macrophages. Our findings reveal novel mechanisms in the pathogenesis of T2D and treatment of pathology caused by IAPP.

SUMMARY Systemic infections with Gram-negative bacteria are characterized by high mortality rates due to the “sepsis syndrome,” a widespread and uncontrolled inflammatory response. Though it is well recognized that the immune response during Gram-negative bacterial infection is initiated after the recognition of endotoxin by Toll-like receptor 4, the molecular mechanisms underlying the detrimental inflammatory response during Gram-negative bacteremia remain poorly defined. Here, we identify a TRIF pathway that licenses NLRP3 inflammasome activation by all Gram-negative bacteria. By engaging TRIF, Gram-negative bacteria activate caspase-11. TRIF activates caspase-11 via type I IFN signaling, an event that is both necessary and sufficient for caspase-11 induction and autoactivation. Caspase-11 subsequently synergizes with the assembled NLRP3 inflammasome to regulate caspase-1 activation and leads to caspase-1-independent cell death. These events occur specifically during infection with Gram-negative, but not Gram-positive, bacteria. The identification of TRIF as a regulator of caspase-11 underscores the importance of TLRs as master regulators of inflammasomes during Gram-negative bacterial infection.

Particulate ligands including cholesterol crystals and amyloid fibrils induce NLRP3-dependent production of interleukin-1β (IL-1β) in atherosclerosis, Alzheimer's disease and diabetes. Soluble endogenous ligands including oxidized-LDL, amyloid-β and amylin peptides accumulate in these diseases. Here we identify a CD36-mediated endocytic pathway that coordinates the intracellular conversion of these soluble ligands to crystals or fibrils, resulting in lysosomal disruption and NLRP3-inflammasome activation. Consequently, macrophages lacking CD36 failed to elicit IL-1β production in response to these ligands and targeting CD36 in atherosclerotic mice reduced serum IL-1β and plaque cholesterol crystal accumulation. Collectively, these findings highlight the importance of CD36 in the accrual and nucleation of NLRP3 ligands from within the macrophage and position CD36 as a central regulator of inflammasome activation in sterile inflammation.

A coding polymorphism (Thr300Ala) in the essential autophagy gene, autophagy related 16-like 1 (ATG16L1), confers increased risk for the development of Crohn disease, although the mechanisms by which single disease-associated polymorphisms contribute to pathogenesis have been difficult to dissect given that environmental factors likely influence disease initiation in these patients. Here we introduce a knock-in mouse model expressing the Atg16L1 T300A variant. Consistent with the human polymorphism, T300A knock-in mice do not develop spontaneous intestinal inflammation, but exhibit morphological defects in Paneth and goblet cells. Selective autophagy is reduced in multiple cell types from T300A knock-in mice compared with WT mice. The T300A polymorphism significantly increases caspase 3-and caspase 7-mediated cleavage of Atg16L1, resulting in lower levels of full-length Atg16Ll T300A protein. Moreover, Atg16L1 T300A is associated with decreased antibacterial autophagy and increased IL-1β production in primary cells and in vivo. Quantitative proteomics for protein interactors of ATG16L1 identified previously unknown nonoverlapping sets of proteins involved in ATG16L1-dependent antibacterial autophagy or IL-1β production. These findings demonstrate how the T300A polymorphism leads to cell typeand pathway-specific disruptions of selective autophagy and suggest a mechanism by which this polymorphism contributes to disease. H uman genetic studies offer an unbiased approach to identify genes and DNA variants underlying susceptibility to complex diseases. Although this approach has been successful at identifying more than 160 loci associated with Crohn disease (CD), a chronic inflammatory condition affecting the gastrointestinal tract (1, 2), ascribing function to specific risk variants has been difficult. Individuals who harbor a common threonine to alanine coding variant at position 300 in autophagy related 16-like 1 (ATG16L1) (T300A) are at increased risk of developing CD compared with individuals who possess a threonine at this position (T300T) (3, 4). The T300A variant lies within a structurally unclassified region of ATG16L1, making it challenging to identify the effect of this polymorphism.ATG16L1 is a component of the core autophagy machinery that plays a critical role in immunity and inflammation. Initial studies investigating ATG16L1 used hypomorphic Atg16L1 mouse models, which show Paneth cell abnormalities relevant to CD such as abnormal mitochondria, irregular patterns of granule morphology and lysozyme distribution, and increased expression of genes implicated in inflammation (5, 6). Although these studies have been useful in highlighting the important role of autophagy proteins in intestinal cells such as Paneth cells and goblet cells, the precise mechanisms by which ATG16L1 T300A influences pathogenesis remain unclear (7)(8)(9)(10).Previous studies have demonstrated that Atg16L1-deficient macrophages produce elevated levels of active caspase 1 and secrete higher levels of the cytokines IL-1β and IL-18 u...

Phagocytosis is a fundamental cellular process that is pivotal for immunity as it coordinates microbial killing, innate immune activation and antigen presentation. An essential step in this process is phagosome acidification, which regulates a number of functions of these organelles that allow them to participate in processes essential to both innate and adaptive immunity. Here we report that acidification of phagosomes containing Gram-positive bacteria is regulated by the NLRP3-inflammasome and caspase-1. Active caspase-1 accumulates on phagosomes and acts locally to control the pH by modulating buffering by the NADPH oxidase NOX2. These data provide insight into a mechanism by which innate immune signals can modify cellular defenses and establish a new function for the NLRP3-inflammasome and caspase-1 in host defense.

We used event-related functional MRI to study awareness of prior episodes during memory retrieval and its relationship to the intention to retrieve memories. Participants completed cues with words from a prior list (intentional test) or with the first words that came to mind (incidental test). During both tests, explicit memory was separated from priming in the absence of explicit memory. Priming was associated with hemodynamic decreases in left fusiform gyrus and bilateral frontal and occipital brain regions; explicit memory was associated with bilateral parietal and temporal and left frontal increases. Retrieval intention did not change these patterns but was associated with activity in right prefrontal cortex. Our results provide firm evidence that implicit and explicit memory have distinct functional neuroanatomies, and that strategic control of retrieval engages brain structures distinct from those involved in both implicit and explicit memory. They have critical implications for theories of memory and consciousness, which often equate consciousness with control.

The innate immune system relies on a variety of pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs) to sense microbial structures that are present in pathogens. Various levels of crosstalk between the TLR and NLR pathways have been described, most notably the description of a molecular scaffold complex, termed the inflammasome, which requires input from both pathways and leads to the activation of the proinflammatory cytokines interleukin (IL)-1beta and IL-18. In certain cases, the inflammatory process becomes dysregulated and chronic inflammatory diseases may develop. Understanding the interactions of the TLR and NLR pathways will provide further clues to the pathogeneses of these diseases and to the development of efficient therapies to combat them.

Autophagy has been postulated to play role in mammalian host defense against fungal pathogens, although the molecular details remain unclear. Here, we show that primary macrophages deficient in the autophagic factor LC3 demonstrate diminished fungicidal activity but increased cytokine production in response to Candida albicans stimulation. LC3 recruitment to fungal phagosomes requires activation of the fungal pattern receptor dectin-1. LC3 recruitment to the phagosome also requires Syk signaling but is independent of all activity by Toll-like receptors and does not require the presence of the adaptor protein Card9. We further demonstrate that reactive oxygen species generation by NADPH oxidase is required for LC3 recruitment to the fungal phagosome. These observations directly link LC3 to the inflammatory pathway against C. albicans in macrophages.