NOD1 mediates interleukin-18 processing in epithelial cells responding to Helicobacter pylori infection in mice.

The interleukin-1 family members, IL-1ß and IL-18, are processed into their biologically active forms by multi-protein complexes, known as inflammasomes. Although the inflammasome pathways that mediate IL-1ß processing in myeloid cells have been defined, those involved in IL-18 processing, particularly in non-myeloid cells, are still not well understood. Here we report that the host defence molecule NOD1 regulates IL-18 processing in mouse epithelial cells in response to the mucosal pathogen, Helicobacter pylori. Specifically, NOD1 in epithelial cells mediates IL-18 processing and maturation via interactions with caspase-1, instead of the canonical inflammasome pathway involving RIPK2, NF-κB, NLRP3 and ASC. NOD1 activation and IL-18 then help maintain epithelial homoeostasis to mediate protection against pre-neoplastic changes induced by gastric H. pylori infection in vivo. Our findings thus demonstrate a function for NOD1 in epithelial cell production of bioactive IL-18 and protection against H. pylori-induced pathology.

Granzyme M has a critical role in providing innate immune protection in ulcerative colitis.

Inflammatory bowel disease (IBD) is an immunoregulatory disorder, associated with a chronic and inappropriate mucosal immune response to commensal bacteria, underlying disease states such as ulcerative colitis (UC) and Crohn's disease (CD) in humans. Granzyme M (GrzM) is a serine protease expressed by cytotoxic lymphocytes, in particular natural killer (NK) cells. Granzymes are thought to be involved in triggering cell death in eukaryotic target cells; however, some evidence supports their role in inflammation. The role of GrzM in the innate immune response to mucosal inflammation has never been examined. Here, we discover that patients with UC, unlike patients with CD, display high levels of GrzM mRNA expression in the inflamed colon. By taking advantage of well-established models of experimental UC, we revealed that GrzM-deficient mice have greater levels of inflammatory indicators during dextran sulfate sodium (DSS)-induced IBD, including increased weight loss, greater colon length reduction and more severe intestinal histopathology. The absence of GrzM expression also had effects on gut permeability, tissue cytokine/chemokine dynamics, and neutrophil infiltration during disease. These findings demonstrate, for the first time, that GrzM has a critical role during early stages of inflammation in UC, and that in its absence colonic inflammation is enhanced.

miR-223: infection, inflammation and cancer.

Expression of the microRNA miR-223 is deregulated during influenza or hepatitis B infection and in inflammatory bowel disease, type 2 diabetes, leukaemia and lymphoma. Although this may also be the result of the disease per se, increasing evidence suggests a role for miR-223 in limiting inflammation to prevent collateral damage during infection and in preventing oncogenic myeloid transformation. Validated targets for miR-223 that have effects on inflammation and infection include granzyme B, IKKα, Roquin and STAT3. With regard to cancer, validated targets include C/EBPß, E2F1, FOXO1 and NFI-A. The effect of miR-223 on these targets has been documented individually; however, it is more likely that miR-223 affects multiple targets simultaneously for key processes where the microRNA is important. Such processes include haematopoietic cell differentiation, particularly towards the granulocyte lineage (where miR-223 is abundant) and as cells progress down the myeloid lineage (where miR-223 expression decreases). NF-κB and the NLRP3 inflammasome are important inflammatory mechanisms that are dampened by miR-223 in these cell types. The miRNA can also directly target viruses such as HIV, leading to synergistic effects during infection. Here we review the recent studies of miR-223 function to show how it modulates inflammation, infection and cancer development.

Succinate is an inflammatory signal that induces IL-1ß through HIF-1α.

Macrophages activated by the Gram-negative bacterial product lipopolysaccharide switch their core metabolism from oxidative phosphorylation to glycolysis. Here we show that inhibition of glycolysis with 2-deoxyglucose suppresses lipopolysaccharide-induced interleukin-1ß but not tumour-necrosis factor-α in mouse macrophages. A comprehensive metabolic map of lipopolysaccharide-activated macrophages shows upregulation of glycolytic and downregulation of mitochondrial genes, which correlates directly with the expression profiles of altered metabolites. Lipopolysaccharide strongly increases the levels of the tricarboxylic-acid cycle intermediate succinate. Glutamine-dependent anerplerosis is the principal source of succinate, although the 'GABA (γ-aminobutyric acid) shunt' pathway also has a role. Lipopolysaccharide-induced succinate stabilizes hypoxia-inducible factor-1α, an effect that is inhibited by 2-deoxyglucose, with interleukin-1ß as an important target. Lipopolysaccharide also increases succinylation of several proteins. We therefore identify succinate as a metabolite in innate immune signalling, which enhances interleukin-1ß production during inflammation.

New chemistry of 1,2-closo-P2B10H10 and 1,2-closo-As2B10H10; in silico and gas electron diffraction structures, and new metalladiphospha- and metalladiarsaboranes.

The molecular structures of 1,2-closo-P(2)B(10)H(10) (1) and 1,2-closo-As(2)B(10)H(10) (2) have been determined by gas electron diffraction and the results obtained compared with those from computation at the MP2/6-31G** level of theory. The level of agreement is good for 2 (root-mean-square [rms] misfit for As and B atoms 0.0297 Å) and very good for 1 (rms misfit for P and B atoms 0.0082 Å). In comparing the structures of 1 and 2 with that of 1,2-closo-C(2)B(10)H(12) (I) it is evident that expansion of the polyhedron from I to 1 to 2 is restricted only to the heteroatom vertices and the B(6) face to which these are bound. Following deboronation (at B3) and subsequent metallation, compounds 1 and 2 have been converted into the new metalladiheteroboranes 3-(η-C(9)H(7))-3,1,2-closo-CoAs(2)B(9)H(9) (4), 3-(η-C(10)H(14))-3,1,2-closo-RuAs(2)B(9)H(9) (5), 3-(η-C(5)H(5))-3,1,2-closo-CoP(2)B(9)H(9) (6), 3-(η-C(9)H(7))-3,1,2-closo-CoP(2)B(9)H(9) (7) and 3-(η-C(10)H(14))-3,1,2-closo-RuP(2)B(9)H(9) (8), the last three constituting the first examples of metalladiphosphaboranes. Together with the known compound 3-(η-C(5)H(5))-3,1,2-closo-CoAs(2)B(9)H(9) (3), compounds 4-8 have been analysed by NMR spectroscopy and (except for 8) single-crystal X-ray diffraction. The (11)B NMR spectra of analogous pairs of metalladiphosphaborane and metalladiarsaborane (6 and 3, 7 and 4, 8 and 5) reveal a consistently narrower (9-10 ppm) chemical shift range for the metalladiarsaboranes, the combined result of a deshielding of the lowest frequency resonance (B6) and an increased shielding of the highest frequency resonance (B8) via an antipodal effect. In crystallographic studies, compounds 3 and 5B (one of two crystallographically-independent molecules) suffer As/B disorder, but in both cases it was possible to refine distinct, ordered, components of the disorder, the first time this has been reported for metalladiarsaboranes. Moreover, whilst the Cp compounds 6 and 3 are disordered, their indenyl analogues 7 and 4 are either ordered or significantly less disordered, a consequence of both the reduced symmetry of an indenyl ligand compared to a Cp ligand and the preference of the former for a distinct conformation relative to the cage heteroatoms. Unexpectedly, whilst this conformation in the cobaltadiphosphaborane 7 is cis-staggered (similar to that previously established for the analogous cobaltadicarborane), in the cobaltadiarsaborane 4 the conformation is close to cis-eclipsed.

Clinical features and functional significance of the P369S/R408Q variant in pyrin, the familial Mediterranean fever protein.

OBJECTIVES: Familial Mediterranean fever (FMF) is caused by mutations in MEFV, which encodes pyrin. The nature of substitutions P369S and R408Q in exon 3 remains unclear. Exon 3 encoding pyrin's B-box domain is necessary for interactions with proline serine threonine phosphatase interacting protein 1 (PSTPIP1). The aim was to characterise the phenotype of patients with these substitutions and to determine their functional significance. METHODS: A database of genetic tests undertaken at the US National Institutes of Health was interrogated. Symptoms and signs were classified according to Tel-Hashomer criteria. Coimmunoprecipitation techniques were employed to determine the variants' effects on pyrin/PSTPIP1 interactions. RESULTS: A total of 40 symptomatic and 4 asymptomatic family members with these substitutions were identified. P369S and R408Q were found in cis, and cosegregated in all patients sequenced. Clinical details were available on 22 patients. In all, 5 patients had symptoms and signs fulfilling a clinical diagnosis of FMF, and 15 received colchicine. In patients not achieving the criteria, trials of anti-tumour necrosis factor (TNF) agents resulted in partial or no benefit; resolution of symptoms was noted in those receiving anakinra. The carrier frequency was higher in the patient cohort than in controls but was not statistically significant. Coimmunoprecipitation studies demonstrated that these pyrin variants did not affect binding to PSTPIP1. CONCLUSIONS: P369S/R408Q substitutions are associated with a highly variable phenotype, and are infrequently associated with typical FMF symptoms, however a trial of colchicine is warranted in all. Functional and modelling studies suggest that these substitutions do not significantly affect pyrin's interaction with PSTPIP1. This study highlights the need for caution in interpreting genetic tests in patients with atypical symptoms.

Genetic deletion of murine SPRY domain-containing SOCS box protein 2 (SSB-2) results in very mild thrombocytopenia.

The SSB family is comprised of four highly homologous proteins containing a C-terminal SOCS box motif and a central SPRY domain. No function has yet been ascribed to any member of this family in mammalian species despite a clear role for other SOCS proteins in negative regulation of cytokine signaling. To investigate its physiological role, the murine Ssb-2 gene was deleted by homologous recombination. SSB-2-deficient mice were shown to have a reduced rate of platelet production, resulting in very mild thrombocytopenia (25% decrease in circulating platelets). Tissue histology and other hematological parameters were normal, as was the majority of serum biochemistry, with the exception that blood urea nitrogen (BUN) levels were decreased in mice lacking SSB-2. Quantitative analysis of SSB mRNA levels indicated that SSB-1, -2, and -3 were ubiquitously expressed; however, SSB-4 was only expressed at very low levels. SSB-2 expression was observed in the kidney and in megakaryocytes, a finding consistent with the phenotype of mice lacking this gene. Deletion of SSB-2 thus perturbs the steady-state level of two tightly controlled homeostatic parameters and identifies a critical role for SSB-2 in regulating platelet production and BUN levels.