Explore the vast range of titles available.

Inflammasomes are protein platforms linking recognition of microbe, pathogen-associated and damage-associated molecular patterns by cytosolic sensory proteins to caspase-1 activation. Caspase-1 promotes pyroptotic cell death and the maturation and secretion of interleukin (IL)-1β and IL-18, which trigger inflammatory responses to clear infections and initiate wound-healing; however, excessive responses cause inflammatory disease. Inflammasome assembly requires the PYRIN domain (PYD)-containing adaptor ASC, and depends on PYD–PYD interactions. Here we show that the PYD-only protein POP2 inhibits inflammasome assembly by binding to ASC and interfering with the recruitment of ASC to upstream sensors, which prevents caspase-1 activation and cytokine release. POP2 also impairs macrophage priming by inhibiting the activation of non-canonical IκB kinase ɛ and IκBα, and consequently protects from excessive inflammation and acute shock in vivo . Our findings advance our understanding of the complex regulatory mechanisms that maintain a balanced inflammatory response and highlight important differences between individual POP members. Excessive inflammasome activation leads to inflammatory diseases, but how inflammasomes are regulated by PYD-only adaptors is unclear. Here the authors show that the PYD-only protein POP2 inhibits both inflammasome priming and assembly by interfering, respectively, with IκBα activation and NLRP3-ASC interaction.

Replicated sister chromatids are held in close association from the time of their synthesis until their separation during the next mitosis. This association is mediated by the ring-shaped cohesin complex that appears to embrace the sister chromatids. Upon proteolytic cleavage of the α-kleisin cohesin subunit at the metaphase-to-anaphase transition by separase, sister chromatids are separated and segregated onto the daughter nuclei. The more complex segregation of chromosomes during meiosis is thought to depend on the replacement of the mitotic α-kleisin cohesin subunit Rad21/Scc1/Mcd1 by the meiotic paralog Rec8. In Drosophila, however, no clear Rec8 homolog has been identified so far. Therefore, we have analyzed the role of the mitotic Drosophila α-kleisin Rad21 during female meiosis. Inactivation of an engineered Rad21 variant by premature, ectopic cleavage during oogenesis results not only in loss of cohesin from meiotic chromatin, but also in precocious disassembly of the synaptonemal complex (SC). We demonstrate that the lateral SC component C(2)M can interact directly with Rad21, potentially explaining why Rad21 is required for SC maintenance. Intriguingly, the experimentally induced premature Rad21 elimination, as well as the expression of a Rad21 variant with destroyed separase consensus cleavage sites, do not interfere with chromosome segregation during meiosis, while successful mitotic divisions are completely prevented. Thus, chromatid cohesion during female meiosis does not depend on Rad21-containing cohesin.

The rhs genes are a family of enigmatic composite genes, widespread among Gram-negative bacteria. In this study, we characterized rhsT, a Pseudomonas aeruginosa rhs gene that encodes a toxic protein. Expression of rhsT was induced upon contact with phagocytic cells. The RhsT protein was exposed on the bacterial surface and translocated into phagocytic cells; these cells subsequently underwent inflammasome-mediated death. Moreover, RhsT enhanced host secretion of the potent proinflammatory cytokines IL-18and IL-18 in an inflammasome-dependent manner. In a mouse model of acute pneumonia, infection with a P. aeruginosa strain lacking rhsT was associated with less IL-18 production, fewer recruited leukocytes, reduced pulmonary bacterial load, and enhanced animal survival. Thus, rhsT encodes a virulence determinant that activates the inflammasome.

Background Congenital hyperinsulinism (CHI) is a life threatening disease. Localization of affected intrapancreatic beta cells responsible for focal forms during surgery can be challenging. In this study we investigated a new radioguided surgical (RGS) approach using [ 68 Ga]Exendin to facilitate intraoperative focus detection. All patients were scanned initially with [ 18 F]-DOPA-PET followed by [ 68 Ga]Exendin PET to differentiate between focal and non-focal forms. Focal CHI patients were then operated. At the beginning of standard surgical dissection of the pancreas in CHI patients ( n  = 12), 46 MBq of [ 68 Ga]Exendin were injected intravenously. Intrapancreatic localization of the foci was determined by using a hand-held positron- and gamma-radiation probe. RGS was carried out as enucleation of CHI foci. Duration of surgery (defined as the time lapse from first incision until final suture placement) for RGS was compared with historical data of patients operated on without RGS. Long term follow-up data on euglycemic control were retrieved from patient´s medical files. Results [ 18 F]-DOPA- and [ 68 Ga]Exendin PET findings were concordant in all patients. Overall, 12 CHI patients underwent RGS. In 11/12 children (92%) the CHI foci localized pre-operatively by [ 68 Ga]Exendin PET could be detected intraoperatively using the hand-held positron probe. There was a high correlation between PET imaging results and positron probe findings in respect to the identification of the affected pancreatic region. One pancreatic lesion in close proximity to the left kidney could not be detected by the positron probe. Histopathology confirmed all resected lesions as CHI foci. Intraoperatively, the signal of the focus was > 10 times higher than the signal of normal adjacent pancreatic tissue. Median duration of surgery was 4.7 h (CI 3.5–6.7) in RGS patients compared to 5.5 h (CI 4-6.7) in patients undergoing surgery without radio guidance. All patients remained euglycemic after surgery (median follow-up 3 years, range 2 to 4.5). Conclusions In this study, we demonstrated the use of [ 68 Ga]Exendin for intraoperative localization of intrapancreatic CHI foci. RGS facilitates localization of intrapancreatic CHI focus and thus potentially reduces duration of surgery and perioperative complications.

Much is known about the activation of inflammasomes, but less is known about their negative regulation. Stehlik and colleagues demonstrate that the pyrin domain–only protein POP3 negatively regulates inflammasomes involved in sensing DNA. The innate immune system responds to infection and tissue damage by activating cytosolic sensory complexes called 'inflammasomes'. Cytosolic DNA is sensed by AIM2-like receptors (ALRs) during bacterial and viral infections and in autoimmune diseases. Subsequently, recruitment of the inflammasome adaptor ASC links ALRs to the activation of caspase-1. A controlled immune response is crucial for maintaining homeostasis, but the regulation of ALR inflammasomes is poorly understood. Here we identified the PYRIN domain (PYD)-only protein POP3, which competes with ASC for recruitment to ALRs, as an inhibitor of DNA virus–induced activation of ALR inflammasomes in vivo . Data obtained with a mouse model with macrophage-specific POP3 expression emphasize the importance of the regulation of ALR inflammasomes in monocytes and macrophages.

BackgroundCrohn’s disease (CD) significantly affects patients’ health-related quality of life and well-being.AimsCommunicating Needs and Features of IBD Experiences (CONFIDE) survey explores the experience and impact of moderate-to-severe CD symptoms on patients’ lives and identifies communication gaps between patients and health care professionals (HCPs).MethodsOnline, quantitative, cross-sectional surveys of patients, and HCPs were conducted in the United States (US), Europe (France, Germany, Italy, Spain, United Kingdom), and Japan. Criteria based on previous treatment, steroid use, and/or hospitalization defined moderate-to-severe CD. US and Europe data are presented as descriptive statistics.ResultsSurveys were completed by 215 US and 547 European patients and 200 US and 503 European HCPs. In both patient groups, top three symptoms currently (past month) experienced were diarrhea, bowel urgency, and increased stool frequency, with more than one-third patients wearing diaper/pad/protection at least once a week in past 3 months due to fear of bowel urgency-related accidents. HCPs ranked diarrhea, blood in stool, and increased stool frequency as the most common symptoms. Although 34.0% US and 27.2% European HCPs ranked bowel urgency among the top five symptoms affecting patient lives, only 12.0% US and 10.9% European HCPs ranked it among top three most impactful symptoms on treatment decisions.ConclusionBowel urgency is common and impactful among patients with CD in the US and Europe. Differences in patient and HCP perceptions of experiences and impacts of bowel urgency exist, with HCPs underestimating its burden. Proactive communication between HCPs and patients in clinical settings is crucial for improving health outcomes in patients with CD.

Introduction Although caspase-8 is a well-established initiator of apoptosis and suppressor of necroptosis, recent evidence suggests that this enzyme maintains functions beyond its role in cell death. As cells of the innate immune system, and in particular macrophages, are now at the forefront of autoimmune disease pathogenesis, we examined the potential involvement of caspase-8 within this population. Methods Cre LysM Casp8 fl/fl mice were bred via a cross between Casp8 fl/fl mice and Cre LysM mice, and RIPK3 −/− Cre LysM Casp8 fl/fl mice were generated to assess the contribution of receptor-interacting serine-threonine kinase (RIPK)3. Immunohistochemical and immunofluorescence analyses were used to examine renal damage. Flow cytometric analysis was employed to characterize splenocyte distribution and activation. Cre LysM Casp8 fl/fl mice were treated with either Toll-like receptor (TLR) agonists or oral antibiotics to assess their response to TLR activation or TLR agonist removal. Luminex-based assays and enzyme-linked immunosorbent assays were used to measure cytokine/chemokine and immunoglobulin levels in serum and cytokine levels in cell culture studies. In vitro cell culture was used to assess macrophage response to cell death stimuli, TLR activation, and M1/M2 polarization. Data were compared using the Mann–Whitney U test. Results Loss of caspase-8 expression in macrophages promotes onset of a mild systemic inflammatory disease, which is preventable by the deletion of RIPK3. In vitro cell culture studies reveal that caspase-8–deficient macrophages are prone to a caspase-independent death in response to death receptor ligation; yet, caspase-8–deficient macrophages are not predisposed to unchecked survival, as analysis of mixed bone marrow chimeric mice demonstrates that caspase-8 deficiency does not confer preferential expansion of myeloid populations. Loss of caspase-8 in macrophages dictates the response to TLR activation, as injection of TLR ligands upregulates expression of costimulatory CD86 on the Ly6C high CD11b + F4/80 + splenic cells, and oral antibiotic treatment to remove microbiota prevents splenomegaly and lymphadenopathy in Cre LysM Casp8 fl/fl mice. Further, caspase-8–deficient macrophages are hyperresponsive to TLR activation and exhibit aberrant M1 macrophage polarization due to RIPK activity. Conclusions These data demonstrate that caspase-8 functions uniquely in macrophages by controlling the response to TLR activation and macrophage polarization in an RIPK-dependent manner.